WO2019107211A1 - Solar cell element - Google Patents

Solar cell element Download PDF

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Publication number
WO2019107211A1
WO2019107211A1 PCT/JP2018/042747 JP2018042747W WO2019107211A1 WO 2019107211 A1 WO2019107211 A1 WO 2019107211A1 JP 2018042747 W JP2018042747 W JP 2018042747W WO 2019107211 A1 WO2019107211 A1 WO 2019107211A1
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Prior art keywords
protective layer
layer
solar cell
electrode
cell element
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PCT/JP2018/042747
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French (fr)
Japanese (ja)
Inventor
松島　徳彦
吉田　貴信
義生 川島
Original Assignee
京セラ株式会社
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Application filed by 京セラ株式会社 filed Critical 京セラ株式会社
Priority to CN201880077215.XA priority Critical patent/CN111492492A/en
Priority to JP2019516264A priority patent/JP6539010B1/en
Publication of WO2019107211A1 publication Critical patent/WO2019107211A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0216—Coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/547—Monocrystalline silicon PV cells

Definitions

  • the present disclosure relates to a solar cell element.
  • the passivation layer is located on the back surface of the semiconductor substrate. Furthermore, the back side current collection electrode is located on the passivation layer or on the protective layer located on the passivation layer.
  • a solar cell element is disclosed.
  • One aspect of a solar cell element includes a semiconductor substrate, a passivation layer, a protective layer, and an electrode layer.
  • the passivation layer is located on the first surface of the semiconductor substrate.
  • the protective layer is located on the passivation layer.
  • the electrode layer is located on the protective layer and includes a glass component.
  • the protective layer has a plurality of convex portions located on the surface on the electrode layer side. Each of the plurality of convex portions has a concave portion on the electrode layer side.
  • the glass component is located in the internal space of the concave portion.
  • FIG. 1 is a plan view showing the appearance of the front side of an example of the solar cell element according to the first embodiment.
  • FIG. 2 is a top view which shows the external appearance of the back surface side of an example of the solar cell element which concerns on 1st Embodiment.
  • FIG. 3 is a view showing an example of a virtual cut surface portion of the solar cell element taken along the line III-III in FIG. 1 and
  • FIG. 4A is an enlarged view showing an example of a virtual cut surface portion of the portion P1 of FIG.
  • FIG.4 (b) is an enlarged view which shows an example of the virtual cut surface part of the part P11 of Fig.4 (a).
  • FIG. 5A is an enlarged view showing an example of a virtual cut surface portion of the portion P1 of FIG. 3.
  • FIG.5 (b) is an enlarged view which shows an example of the virtual cut surface part of the part P11 of Fig.5 (a).
  • Fig.6 (a) is a figure for demonstrating the conditions of the peel test about the solar cell element which concerns on one reference example.
  • FIG.6 (b) is a figure which shows the result of the peeling test about the solar cell element which concerns on one reference example.
  • FIG. 7 is an enlarged view showing an example of a virtual cut surface portion of the portion P12 of FIG. 5 (a).
  • FIGS. 8 (a) to 8 (f) each show an example of a virtual cut surface portion corresponding to the virtual cut surface portion of FIG. 3 in a state in the middle of manufacturing the solar cell element according to the first embodiment.
  • FIG. 9 is a view for explaining an example of the structure of the protective layer according to the first embodiment.
  • Fig.10 (a) is an enlarged view which shows an example of the virtual cutting plane part of the part corresponding to the part P11 of Fig.4 (a) among the solar cell elements which concern on 2nd Embodiment.
  • FIG.10 (b) is an enlarged view which shows an example of the virtual cutting plane part of the part corresponding to the part P11 of Fig.5 (a) among the solar cell elements which concern on 2nd Embodiment.
  • FIG. 11 is a view for explaining an example of the structure of the protective layer according to the second embodiment.
  • FIG. 12 is a plan view showing the appearance of the back surface side of an example of the solar cell element according to the third embodiment.
  • FIG. 13 is a plan view showing an appearance of a front side of an example of a solar cell module according to a third embodiment.
  • FIG. 14 is a view showing an example of a virtual cross section of the solar cell element taken along line XIV-XIV in FIG.
  • FIG. 15 is a view showing an example of a virtual cut surface part corresponding to the virtual cut surface part of FIG. 14 in a state where the solar cell module according to the third embodiment is being manufactured.
  • FIG. 16A is an enlarged view showing an example of a virtual cut surface portion of the portion P16 of FIG.
  • FIG. 16B is an enlarged view showing a first example of a virtual cut surface portion of a portion corresponding to the portion P16 of FIG. 3 in the solar cell element according to a modification.
  • FIG. 16C is an enlarged view showing a second example of a virtual cut surface portion of a portion corresponding to the portion P16 of FIG. 3 in the solar cell element according to one modification.
  • Fig.17 (a) is an enlarged view which shows the 1st example of the virtual cutting plane part of the part corresponding to the part P16 of FIG. 3 among the solar cell elements which concern on another one modification.
  • FIG. 17B is an enlarged view showing a second example of a virtual cut surface portion of a portion corresponding to the portion P16 of FIG. 3 in a solar cell element according to another modification.
  • FIG. 17C is an enlarged view showing a third example of a virtual cut surface portion of a portion corresponding to the portion P16 of FIG. 3 in a solar cell element according to another modification.
  • a passivation layer, a protective layer, and a back electrode are formed in this order on the back surface of the semiconductor substrate.
  • the protective layer is formed of, for example, an oxide film formed of silicon oxide or the like, a nitride film formed of silicon nitride or the like, or a film in which an oxide film and a nitride film are stacked.
  • This protective layer is formed, for example, by a wet process or a dry process.
  • a coating method for applying and drying an insulating paste containing a siloxane resin is applied.
  • the dry process for example, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), sputtering or the like is applied.
  • the fine concavo-convex structure (texture) for reducing reflection of irradiated light may be formed in the front side of a semiconductor substrate, for example.
  • a texture is formed on the semiconductor substrate by performing wet etching using, for example, an alkaline aqueous solution such as sodium hydroxide or an acidic aqueous solution such as hydrofluoric-nitric acid.
  • texture may be formed on the entire surface including the back surface as well as the front surface of the semiconductor substrate.
  • a paste containing metal powder mainly containing aluminum, a glass component, and an organic vehicle (also referred to as a metal paste) is applied onto the protective layer, and the metal paste is fired to form the back surface side. It may form a collecting electrode.
  • the distribution of the components of the metal paste tends to be biased due to the presence of irregularities on the surface of the protective layer. For this reason, the adhesion strength of the current collection electrode to the protective layer tends to be nonuniform.
  • the protective layer may be peeled off from the back surface side of the semiconductor substrate.
  • the stress generated between the semiconductor substrate and the protective layer increases due to expansion and contraction accompanying the temperature change of the protective layer, the warpage of the solar cell element may increase, and the solar cell element may be cracked or broken. There is. As a result, the photoelectric conversion efficiency in the solar cell element may be reduced.
  • the present inventors have created a technology that can improve the photoelectric conversion efficiency of a PERC type solar cell element.
  • the longitudinal direction of the first output extraction electrode 7a is the + Y direction
  • the short direction of the first output extraction electrode 7a is the + X direction
  • the sun is orthogonal to both the + X direction and the + Y direction.
  • the normal direction of the front surface 10 fs of the battery element 10 is the + Z direction.
  • the solar cell element 10 according to the first embodiment is a PERC type solar cell element.
  • the solar cell element 10 mainly includes a light receiving surface (also referred to as a front surface) 10 fs, and a surface (also referred to as a back surface) 10 bs located on the opposite side of the front surface. And.
  • the front surface 10 fs faces the + Z direction
  • the back surface 10 bs faces the ⁇ Z direction.
  • the solar cell element 10 includes, for example, a semiconductor substrate 1, a passivation layer 4, an antireflection layer 5, a protective layer 6, a front electrode 7, and a back electrode 8.
  • the semiconductor substrate 1 has a first surface 1 bs, a second surface 1 fs, and a third surface 1 ss.
  • the first surface 1 bs is located on the back surface 10 bs side.
  • the second surface 1 fs is located on the front surface 10 fs side. In other words, the first surface 1 bs and the second surface 1 fs are located in directions opposite to each other.
  • the third surface 1ss is located in a state in which the first surface 1bs and the second surface 1fs are connected. In other words, the third surface 1 ss is an end surface in a state of forming the outer peripheral edge of the semiconductor substrate 1. In the example of FIGS. 1 to 3, the first surface 1 bs is in the state of facing the ⁇ Z direction.
  • the second surface 1 fs is in the state of facing the + Z direction.
  • the semiconductor substrate 1 has a flat form having a thickness along the + Z direction. For this reason, the first surface 1 bs and the second surface 1 fs are in the state of constituting the plate surface of the semiconductor substrate 1 along the XY plane.
  • the semiconductor substrate 1 also has a first semiconductor layer 2 and a second semiconductor layer 3.
  • the first semiconductor layer 2 is in a state of being constituted by a semiconductor having a first conductivity type.
  • the second semiconductor layer 3 is in a state of being constituted by a semiconductor having a second conductivity type opposite to the first conductivity type.
  • the first semiconductor layer 2 is located in a portion of the semiconductor substrate 1 on the first surface 1 bs side.
  • the second semiconductor layer 3 is located in the surface layer portion of the semiconductor substrate 1 on the second surface 1 fs side. In the example of FIG. 3, the second semiconductor layer 3 is located on the first semiconductor layer 2.
  • the semiconductor substrate 1 is a silicon substrate.
  • a polycrystalline or single crystal silicon substrate is employed as the silicon substrate.
  • the silicon substrate is, for example, a thin substrate having a thickness of 250 ⁇ m or less or 150 ⁇ m or less.
  • the silicon substrate has, for example, a rectangular outer edge shape in plan view. If the semiconductor substrate 1 having such a shape is adopted, the gaps between the solar cell elements 10 may be small when the solar cell module 10 is manufactured by arranging the plurality of solar cell elements 10.
  • the p-type silicon substrate is, for example, boron as a dopant element in polycrystalline or single crystal silicon crystal. Alternatively, it may be manufactured to contain an impurity such as gallium.
  • the n-type second semiconductor layer 3 can be generated by diffusing an impurity such as phosphorus as a dopant in the surface layer portion on the second surface 1 fs side of the p-type silicon substrate.
  • the semiconductor substrate 1 in which the p-type first semiconductor layer 2 and the n-type second semiconductor layer 3 are stacked can be formed.
  • the semiconductor substrate 1 has a pn junction located at the interface between the first semiconductor layer 2 and the second semiconductor layer 3.
  • the second surface 1 fs of the semiconductor substrate 1 may have, for example, a fine uneven structure (texture) for reducing the reflection of the irradiated light.
  • the height of the convex portion of the texture is, for example, about 0.1 ⁇ m to 10 ⁇ m.
  • the distance between the apexes of adjacent protrusions is, for example, about 0.1 ⁇ m to about 20 ⁇ m.
  • the recess may be substantially spherical, or the protrusion may be pyramidal.
  • the “height of the convex portion” described above is, for example, a straight line passing through the bottom of the recess in FIG. 3 as a reference line, and from the reference line in a direction (here, + Z direction) perpendicular to the reference line. It is the distance to the top of the convex part.
  • the semiconductor substrate 1 has a third semiconductor layer 2bs.
  • the third semiconductor layer 2 bs is located in the surface layer portion of the semiconductor substrate 1 on the first surface 1 bs side.
  • the conductivity type of the third semiconductor layer 2bs is the same as the conductivity type of the first semiconductor layer 2 (p type in this embodiment).
  • the concentration of the dopant contained in the third semiconductor layer 2 bs is higher than the concentration of the dopant contained in the first semiconductor layer 2.
  • the third semiconductor layer 2 bs forms an internal electric field on the side of the first surface 1 bs of the semiconductor substrate 1. Thereby, in the vicinity of the first surface 1 bs of the semiconductor substrate 1, recombination of minority carriers generated in the semiconductor substrate 1 by photoelectric conversion in response to light irradiation can be reduced.
  • the third semiconductor layer 2bs may be formed, for example, by diffusing a dopant element such as aluminum in the surface layer portion of the semiconductor substrate 1 on the first surface 1bs side.
  • the concentration of the dopant element contained in the first semiconductor layer 2 is about 5 ⁇ 10 15 atoms / cm 3 to 1 ⁇ 10 17 atoms / cm 3
  • the concentration of the dopant element contained in the third semiconductor layer 2 bs is And 1 ⁇ 10 18 atoms / cm 3 to 5 ⁇ 10 21 atoms / cm 3 or so.
  • the third semiconductor layer 2 bs is present at a contact portion between the second current collection electrode 8 b described later and the semiconductor substrate 1.
  • the passivation layer 4 is located on at least the first surface 1 bs of the semiconductor substrate 1.
  • the passivation layer 4 can reduce recombination of minority carriers generated by photoelectric conversion in response to light irradiation in the semiconductor substrate 1.
  • a material of the passivation layer 4 for example, one or more kinds of materials selected from aluminum oxide, zirconium oxide, hafnium oxide, silicon oxide, silicon nitride, silicon oxynitride and the like are employed.
  • the passivation layer 4 is, for example, in a state of being constituted by one layer or two or more layers containing different materials. In this case, the passivation layer 4 can be formed by, for example, a CVD method or an atomic layer deposition (ALD) method.
  • the passivation layer 4 contains aluminum oxide.
  • the aluminum oxide has a negative fixed charge. Therefore, minority carriers (in this case, electrons) generated on the first surface 1 bs side of the semiconductor substrate 1 by the field effect are generated from the interface (first surface 1 bs) between the p-type first semiconductor layer 2 and the passivation layer 4. It is kept away. Thereby, the recombination of minority carriers in the vicinity of the first surface 1 bs of the semiconductor substrate 1 can be reduced. For this reason, the photoelectric conversion efficiency of the solar cell element 10 can be improved.
  • the thickness of the passivation layer 4 is, for example, about 3 nm to 100 nm.
  • the passivation layer 4 may be located, for example, on the second surface 1 fs of the semiconductor substrate 1.
  • the passivation layer 4 may also be located, for example, on the third surface 1 ss as an end face connecting the second surface 1 fs of the semiconductor substrate 1 and the first surface 1 bs.
  • the antireflection layer 5 can reduce the reflectance of light irradiated to the front surface 10 fs of the solar cell element 10.
  • a material of the antireflective layer 5 for example, silicon oxide, aluminum oxide or silicon nitride is adopted.
  • the refractive index and thickness of the antireflective layer 5 are conditions (also referred to as low reflection conditions) in which the reflectance is low with respect to light in a wavelength range that can be absorbed by the semiconductor substrate 1 and contribute to power generation. It can be appropriately set to a value that can be realized. For example, it is conceivable to set the refractive index of the antireflective layer 5 to about 1.8 to 2.5 and to set the thickness of the antireflective layer 5 to about 20 nm to 120 nm.
  • the protective layer 6 is located on the passivation layer 4 located on the first surface 1 bs of the semiconductor substrate 1.
  • the protective layer 6 can protect the passivation layer 4.
  • a material of the protective layer 6 for example, one or more kinds of materials selected from silicon oxide, silicon nitride, silicon oxynitride and the like are employed.
  • the protective layer 6 is located on the passivation layer 4 in a state having a desired pattern.
  • the protective layer 6 has a gap penetrating the protective layer 6 in the thickness direction (here, the + Z direction).
  • This gap may be, for example, a hole in a state in which the periphery along the first surface 1 bs forms a closed through hole, or at least a part of the periphery along the first surface 1 bs It may be a slit-like hole in an open state.
  • FIG. 2 when the protective layer 6 is seen through the plan view from the back surface 10 bs side, it is assumed that the protective layer 6 has a plurality of holes CH1.
  • each hole CH1 may be in a dot (dot) shape or in a band (line) shape.
  • the diameter or width of the hole CH1 is, for example, about 10 ⁇ m to 500 ⁇ m.
  • the pitch of the holes CH1 is, for example, about 0.3 mm to 3 mm.
  • the pitch of the holes CH1 is, for example, the distance between the centers of the holes CH1 adjacent to each other when the protective layer 6 is seen through the plane from the back surface 10bs side.
  • 110 holes CH1 are present.
  • the combination of the size, shape, and number of the holes CH1 may be appropriately adjusted. For this reason, the number of the holes CH1 may be, for example, one or more.
  • the protective layer 6 has a desired pattern of insulating paste by a coating method such as a spray method, a coater method or a screen printing method. It is formed by being dried after being applied to have.
  • the protective layer 6 may be formed directly on the passivation layer 4 or the antireflective layer 5 directly, for example, on the third surface 1 ss of the semiconductor substrate 1. At this time, the leakage current in the solar cell element 10 can be reduced by the presence of the protective layer 6.
  • a metal paste (a first metal paste containing a metal powder mainly composed of aluminum, a glass component, and an organic vehicle) Is applied and baked on the protective layer 6 so as to have a desired shape.
  • the main component means a component having the largest ratio (also referred to as a content ratio) of the contained components.
  • the first metal paste applied directly on the passivation layer 4 causes a fire through of the passivation layer 4 in the hole portion CH1 of the protective layer 6, and the second surface 1bs of the semiconductor substrate 1
  • the collecting electrode 8b is directly connected.
  • the passivation layer 4 and the protective layer 6 are in a state of having a plurality of holes CH1 positioned respectively in a state of penetrating the passivation layer 4 and the protective layer 6.
  • the third semiconductor layer is formed by diffusing aluminum contained in the first metal paste located in the plurality of holes CH1 into the surface layer portion of the first surface 1bs of the semiconductor substrate 1 Two bs are formed.
  • the first metal paste is used as the passivation layer 4 in the portion covered with the protective layer 6 in the passivation layer 4. Do not fire through.
  • the passivation layer 4 can be present on the first surface 1 bs of the semiconductor substrate 1 in a pattern corresponding to the desired pattern of the protective layer 6.
  • the thickness of the protective layer 6 is, for example, about 0.5 ⁇ m to 10 ⁇ m.
  • the thickness of the protective layer 6 depends on the composition of the insulating paste to be described later for forming the protective layer 6, the shape of the first surface 1bs of the semiconductor substrate 1, and the firing conditions at the time of forming the second collector electrode 8b. , Is set appropriately.
  • the front surface electrode 7 is located on the second surface 1 fs side of the semiconductor substrate 1.
  • the surface electrode 7 has the 1st output extraction electrode 7a and several linear 1st current collection electrodes 7b, as FIG. 1 and FIG. 3 show.
  • the first output lead electrode 7 a can take out the carrier obtained by photoelectric conversion according to the irradiation of light in the semiconductor substrate 1 to the outside of the solar cell element 10.
  • a bus bar electrode having, for example, an elongated rectangular shape is employed in plan view of the front surface 10 fs.
  • the length (also referred to as the width) of the first output lead electrode 7a in the short direction is, for example, about 0.3 mm to 2.5 mm.
  • At least a part of the first output lead-out electrode 7a is in a state of being electrically connected in a state of intersecting with the first current collection electrode 7b.
  • the first current collecting electrode 7 b can collect carriers obtained by photoelectric conversion according to the light irradiation in the semiconductor substrate 1.
  • Each first current collecting electrode 7 b is, for example, a linear electrode having a width of about 20 ⁇ m to 200 ⁇ m. In other words, the width of each first current collecting electrode 7b is smaller than the width of the first output lead electrode 7a.
  • the plurality of first current collection electrodes 7b are located, for example, in a state of being spaced apart from each other by about 1 mm to 3 mm.
  • the thickness of the surface electrode 7 is, for example, about 3 ⁇ m to 30 ⁇ m.
  • Such a surface electrode 7 is formed by, for example, applying a metal paste (also referred to as a second metal paste) containing metal particles containing silver as a main component to a desired shape by screen printing or the like. Can be formed by firing. Further, for example, the auxiliary electrode 7c having the same shape as that of the first current collection electrode 7b is located along the edge portions respectively present on the + X direction side and the ⁇ X direction side of the semiconductor substrate 1 The first collecting electrodes 7b may be electrically connected to each other.
  • a metal paste also referred to as a second metal paste
  • the auxiliary electrode 7c having the same shape as that of the first current collection electrode 7b is located along the edge portions respectively present on the + X direction side and the ⁇ X direction side of the semiconductor substrate 1
  • the first collecting electrodes 7b may be electrically connected to each other.
  • the back electrode 8 is located on the first surface 1 bs side of the semiconductor substrate 1.
  • the back surface electrode 8 has the 2nd output extraction electrode 8a and the 2nd current collection electrode 8b, as FIG. 2 and FIG. 3 show.
  • the second output lead electrode 8 a is located on the first surface 1 bs side of the semiconductor substrate 1.
  • the second output extraction electrode 8 a is an electrode for extracting carriers obtained by photoelectric conversion in the solar cell element 10 to the outside of the solar cell element 10.
  • the thickness of the second output lead-out electrode 8a is, for example, about 3 ⁇ m to 20 ⁇ m.
  • the width of the second output lead-out electrode 8a is, for example, about 1.3 mm to 7 mm.
  • the second output lead-out electrode 8a contains silver as a main component
  • the second output lead-out electrode 8a is, for example, a metal paste (third metal paste) containing a metal powder mainly containing silver, a glass component and an organic vehicle
  • the third metal paste may be formed by firing after the coating is applied to a desired shape by screen printing or the like.
  • the second current collection electrode 8 b is located on the protective layer 6 on the first surface 1 bs side of the semiconductor substrate 1.
  • the second current collection electrode 8 b is in a state of being electrically connected to the semiconductor substrate 1.
  • the second current collection electrode 8b includes an electrode layer 8bl and a connection portion 8bc.
  • the electrode layer 8 bl is a layered portion located on the protective layer 6.
  • Connecting portion 8 bc electrically connects electrode layer 8 bl to first surface 1 bs of semiconductor substrate 1 at a plurality of holes CH 1 positioned respectively in a state of penetrating through passivation layer 4 and protective layer 6. It is the part located in the state where it is doing.
  • the second current collection electrode 8 b can collect carriers obtained by photoelectric conversion in the semiconductor substrate 1 according to the light irradiation on the first surface 1 bs side of the semiconductor substrate 1.
  • the second current collection electrode 8 b is located in a state electrically connected to at least a part of the second output extraction electrode 8 a.
  • the thickness of the electrode layer 8bl in the second current collection electrode 8b is, for example, about 15 ⁇ m to 50 ⁇ m.
  • the second current collection electrode 8 b has, for example, the same shape as the first current collection electrode 7 b on the first surface 1 bs of the solar cell element 10 and is connected to the second output extraction electrode 8 a It may be located in the state. If such a structure is adopted, light incident on the back surface 10 bs of the solar cell element 10 can also be used for photoelectric conversion in the solar cell element 10. Thereby, for example, the output of the solar cell element 10 can be improved.
  • the light incident on the back surface 10bs can be generated, for example, by the reflection of sunlight on the ground or the like.
  • FIGS. 4 (a) and 4 (b) The structure on the back surface 10bs side of the solar cell element 10 according to the first embodiment will be described based on FIGS. 4 (a) and 4 (b).
  • observing the surface shape of the protective layer 6 with an optical microscope or a scanning electron microscope (SEM: Scanning Electron Microscope) Can.
  • SEM Scanning Electron Microscope
  • the cross section of the protective layer 6 is observed by SEM or the like. can do.
  • the protective layer 6 has a plurality of convex portions 6p located on the surface of the second current collection electrode 8b on the electrode layer 8bl side.
  • the plurality of convex portions 6 p are located on the surface of the protective layer 6 opposite to the surface on which the passivation layer 4 is located.
  • the surface of the protective layer 6 opposite to the surface on which the passivation layer 4 is located is the surface of the protective layer 6 on which the electrode layer 8 b 1 is located.
  • the protective layer 6 has a plurality of convex portions 6 p and a non-convex portion 6 ap, which are located on the electrode layer 8 bl side of the second collecting electrode 8 b.
  • the non-convex portion 6 ap is a portion other than the plurality of convex portions 6 p, which is located on the surface of the protective layer 6 on the electrode layer 8 bl side.
  • the surface of the protective layer 6 on the electrode layer 8 bl side has a concavo-convex structure including the convex portion 6 p and the non-convex portion 6 ap.
  • each convex portion 6p is positioned in a state of projecting in the -Z direction with reference to the non-convex portion 6ap.
  • the protective layer 6 is located on the surface of the second current collection electrode 8b on the electrode layer 8bl side, and the convex portion 6p, and the convex shape You may have non-convex-shaped parts 6ap other than the part 6p.
  • the convex portion 6 p and the non-convex portion 6 ap are located on the surface of the protective layer 6 opposite to the surface on which the passivation layer 4 is located.
  • each convex portion 6p is positioned in a state of projecting in the -Z direction with reference to the non-convex portion 6ap.
  • the concavo-convex structure on the surface of the protective layer 6 may be derived from, for example, the concavo-convex structure 1 rg of the first surface 1 bs of the semiconductor substrate 1.
  • a portion (also referred to as a recess) 1r positioned in a state of being recessed in the + Z direction, and in the -Z direction.
  • a portion (also referred to as a convex portion) 1p positioned in a protruding state.
  • the concavo-convex structure 1 rg is in a state of being configured to have the concave portion 1 r and the convex portion 1 p.
  • the passivation layer 4 and the protective layer 6 having a small thickness are formed in this order on the concavo-convex structure 1 rg, so that the electrode layer 8 bl of the protective layer 6 is to be formed.
  • a concavo-convex structure corresponding to the concavo-convex structure 1 rg of the semiconductor substrate 1 may be formed on the surface.
  • the above-described fine on the second surface 1 fs side by wet etching using an alkaline aqueous solution such as sodium hydroxide or an acidic aqueous solution such as fluoronitric acid.
  • An uneven structure is formed.
  • the concavo-convex structure is formed on the second surface 1 fs side
  • the concavo-convex structure 1 rg may be formed on the first surface 1 bs side of the semiconductor substrate 1.
  • each of the plurality of convex portions 6p in the protective layer 6 has one or more concave shapes on the electrode layer 8bl side of the second current collection electrode 8b. It has a portion 6pr.
  • the convex portion 6p has a plurality of concave portions 6pr.
  • FIG. 4B six concave portions 6pr located in the convex portion 6p are drawn.
  • FIG. 5 (b) seven concave portions 6pr located in the convex portion 6p are drawn.
  • an organic filler is contained in the insulating paste used when forming the protective layer 6, and the organic filler is thermally decomposed when the insulating paste is dried.
  • the filler may be formed as a trace of the extinguished area.
  • a part of the electrode layer 8bl of the second collecting electrode 8b is located in the internal space SC1 of the concave portion 6pr.
  • a component also referred to as an electrode component
  • the electrode component contains at least a glass component. This glass component may be derived from, for example, the glass component contained in the first metal paste used when forming the second current collection electrode 8b.
  • the protective layer 6 and the second current collection are The adhesion to the electrode 8b is reduced.
  • four types of experimental solar cell elements 110 are manufactured as samples, and the adhesion of the second current collection electrode 108b to the protective layer 106 is obtained. Experiments were conducted. As a result, it was confirmed that when the content of the glass component contained in the first metal paste decreases, the adhesion of the second current collection electrode 108b to the protective layer 106 decreases.
  • a polycrystalline silicon substrate having rectangular front and back surfaces with a side of about 156 mm and a thickness of about 200 ⁇ m was prepared.
  • a passivation layer of about 50 nm was formed by the ALD method on the back surface side of this polycrystalline silicon substrate, and a protective layer 106 was formed on this passivation layer.
  • an insulating paste containing a siloxane resin, an organic solvent, and a plurality of inorganic fillers is applied by a coater method on the passivation layer, and dried at about 270 ° C. to have a thickness of about 1 ⁇ m.
  • the protective layer 106 was formed.
  • a first metal paste containing a metal powder containing aluminum (Al) as a main component, a glass component, and an organic vehicle was applied to substantially the entire surface of the protective layer 106 by screen printing.
  • four types of first metal pastes were used in which the content of the glass component was four levels of 2% by mass, 3.5% by mass, 4% by mass, and 5% by mass.
  • a third metal paste containing a metal powder containing silver as a main component, an organic vehicle, and a glass frit was applied by screen printing to a pattern of the second output extraction electrode 108a. Then, by firing the first metal paste and the third metal paste under the condition that the maximum temperature is about 740 ° C.
  • the heating time is about one minute (min)
  • the second output extraction electrode 108 a and the second output extraction electrode 108 a A back electrode 108 including the two current collection electrodes 108 b was formed. Thereby, samples of solar cell elements 110 for four types of experiments were produced.
  • ethylene vinyl acetate is provided in a region Aa0 surrounded by a two-dot chain line on the second current collection electrode 108b. It stuck, heating resin of copolymer (EVA). Then, an experiment was conducted to confirm whether or not the second current collection electrode 108 b is peeled off from the protective layer 106 by peeling off the EVA resin from the second current collection electrode 108 b. At this time, as shown in FIG. 6 (b), the content of the glass component in the first metal paste used for the preparation is 4 mass% and 5 among the samples of the four types of experimental solar cell elements 110.
  • the second current collection electrode 108 b was not peeled off from the protective layer 106 for the sample that was% by mass.
  • the content of the glass component in the first metal paste used for preparation is as low as 3.5 mass% and 2 mass%, it is recognized that the second current collection electrode 108 b peels off from the protective layer 106 It was done. From this experimental result, it was confirmed that when the content of the glass component contained in the first metal paste decreases, the adhesion of the second current collection electrode 108b to the protective layer 106 decreases. Thereby, it was found that if the content of the glass component in the first metal paste is increased, the adhesion between the protective layer 106 and the metal particles in the second current collection electrode 108b is enhanced due to the presence of the glass component.
  • the concave portion 6pr is present in the convex portion 6p present on the surface of the protective layer 6. Therefore, for example, when the first metal paste is applied on the protective layer 6 to form the second current collecting electrode 8b, the convex portion 6p may be formed even if the surface of the protective layer 6 has an uneven structure.
  • the glass component and the like in the first metal paste penetrate into the existing concave portion 6pr. Therefore, for example, when forming the configuration shown in FIG. 4A and FIG. 5A, in the first metal paste located on the convex portion 6p, the glass component, the organic vehicle, etc.
  • the diameter of the concave portion 6pr present on the surface of the protective layer 6 is, for example, 0.1 ⁇ m to It is about 10 ⁇ m.
  • a glass component in a molten state in the first metal paste can easily enter the concave portion 6pr.
  • the adhesion of the second current collection electrode 8b to the protective layer 6 can be improved.
  • the depth of the concave portion 6pr present on the surface on the electrode layer 8bl side of the second current collection electrode 8b of the protective layer 6 is, for example, about 0.1 ⁇ m to 1 ⁇ m. .
  • the depth of the concave portion 6pr is smaller than the height of the convex portion 6p, the component of the first metal paste applied on the protective layer 6 when forming the second current collecting electrode 8b. Distribution is less likely to occur. As a result, for example, the adhesion of the second current collection electrode 8 b on the protective layer 6 is unlikely to be uneven.
  • the thickness (also referred to as the minimum film thickness) of the protective layer 6 in the portion where the concave portion 6pr is present in the protective layer 6 is about 0.5 ⁇ m or more, passivation by the protective layer 6 is performed. The function of protecting the layer 4 can be secured.
  • the first distance is also referred to as D1.
  • D1 a distance between centers of adjacent concave portions 6pr is adopted.
  • the first distance D1 may be, for example, an average value of distances between centers of adjacent concave portions 6pr, or even a distance between adjacent concave portions 6pr (also referred to as a separation distance). It may be an average value of the separation distance between adjacent concave portions 6pr.
  • the distance (also referred to as a second distance) between adjacent convex portions 6p among the plurality of convex portions 6p is D2.
  • D2 the distance between the centers or the apexes of adjacent convex portions 6p is adopted.
  • the second distance D2 may be, for example, an average value of distances between centers or apexes of adjacent convex portions 6p, or may be a distance between adjacent convex portions 6p. It may be an average value of the separation distances of the adjacent convex portions 6p. Further, as shown in FIGS.
  • a distance (also referred to as a third distance) between adjacent connection portions 8bc among a plurality of connection portions 8bc existing in a plurality of hole portions CH1 is D3.
  • the third distance D3 may be, for example, an average value of distances between centers of adjacent connection portions 8bc, or may be a separation distance between adjacent connection portions 8bc, or adjacent connection portions 8bc.
  • the average value of the separation distances of for example, if the first distance D1 is shorter than any of the second distance D2 and the third distance D3, the adhesion of the second current collection electrode 8b to the protective layer 6 can be sufficiently improved.
  • partial peeling of the second current collection electrode 8 b from the protective layer 6 does not easily occur. Therefore, the photoelectric conversion efficiency in the PERC solar cell element 10 can be improved. Furthermore, here, for example, adjacent concave portions 6pr may be connected to each other. In this case, the adhesion of the second current collection electrode 8b to the protective layer 6 can be further improved. As a result, for example, partial peeling of the second current collection electrode 8 b from the protective layer 6 is less likely to occur.
  • the ratio of the concave portion 6pr to the area of the unit area in the convex portion 6p is about 5% to 40%.
  • the adhesion of the second current collection electrode 8b to the protective layer 6 can be easily improved.
  • the surface of the protective layer 6 on the electrode layer 8 bl side is observed by SEM.
  • the plane can be viewed in plan.
  • the unit area is set, for example, in the range of 10 ⁇ m 2 to 20 ⁇ m 2 .
  • the non-convex portion 6ap of the protective layer 6 also has one or more concave portions 6pr, similarly to the convex portion 6p. It may be Thereby, for example, a plurality of concave portions 6pr may exist over a wide range in the portion of the protective layer 6 on the electrode layer 8bl side of the second current collection electrode 8b. Then, for example, in the internal space SC1 of the concave portion 6pr of the non-convex portion 6ap, an electrode component including a glass component in a state of constituting the electrode layer 8bl of the second current collection electrode 8b is positioned .
  • the distribution of the components of the first metal paste applied onto the protective layer 6 is less likely to be uneven when the second current collection electrode 8 b is formed.
  • the distribution of the adhesion between the protective layer 6 and the second current collection electrode 8 b is unlikely to be biased.
  • partial peeling of the second current collection electrode 8 b from the protective layer 6 does not easily occur. Therefore, the photoelectric conversion efficiency in the PERC solar cell element 10 can be improved.
  • Insulating paste> In the first embodiment, for example, two types of insulating pastes are used to form the protective layer 6.
  • the two types of insulating pastes include a first insulating paste and a second insulating paste.
  • Each of the first insulating paste and the second insulating paste contains, for example, a siloxane resin, an organic solvent, and a plurality of fillers.
  • the siloxane resin is a siloxane compound having a Si—O—Si bond (siloxane bond).
  • siloxane resin for example, a low molecular weight resin having a molecular weight of 10,000 or less, which is produced by hydrolyzing alkoxysilane or silazane or the like and condensation polymerization, is employed.
  • the plurality of fillers in the first insulating paste include fillers (also referred to as inorganic fillers) whose main component is an inorganic material.
  • the plurality of fillers in the second insulating paste contain a filler whose main component is an organic material (also referred to as an organic filler).
  • the plurality of fillers in the second insulating paste may contain an inorganic filler.
  • the first insulating paste can be manufactured as follows.
  • a mixed solution is prepared by mixing a siloxane resin precursor, water, an organic solvent, a catalyst, and a filler.
  • silane compound having a Si—O bond or a silazane compound having a Si—N bond may be employed as a precursor of the siloxane resin. These compounds have the property of causing hydrolysis (also referred to as hydrolyzability). Moreover, the precursor of a siloxane resin becomes a siloxane resin by hydrolyzing and producing condensation polymerization.
  • the silane compound is represented by the following general formula 1.
  • N in the general formula 1 is, for example, an integer of 0, 1, 2 or 3.
  • R1 and R2 in formula 1 is a methyl group (-CH 3) and ethyl group (-C 2 H 5) alkyl groups such as (-C m H 2m + 1) or phenyl group (-C 6 H 5), etc.
  • m is a natural number.
  • the silane compound includes, for example, a silane compound in which at least R 1 has an alkyl group (also referred to as an alkyl group-based silane compound).
  • the alkyl group-based silane compound for example, methyltrimethoxysilane (CH 3 -Si- (OCH 3 ) 3 ), dimethyldimethoxysilane ((CH 3 ) 2 -Si- (OCH 3 ) 2 ), Triethoxymethylsilane (CH 3 -Si- (OC 2 H 5 ) 3 ), diethoxydimethylsilane ((CH 3 ) 2 -Si- (OC 2 H 5 ) 2 ), trimethoxypropylsilane ((CH 3 ) 3 O) 3 -Si- (CH 2 ) 2 CH 3 ), triethoxypropylsilane ((C 2 H 5 O) 3 -Si- (CH 2 ) 2 CH 3 ), hexyltrimethoxys
  • the alkyl group is a methyl group, an ethyl group or a propyl group
  • an alcohol as a by-product which has a small number of carbon atoms and is easy to volatilize may be generated when the precursor of the siloxane resin is hydrolyzed.
  • by-products are easily removed in the process described later.
  • the protective layer 6 is formed, generation of pores due to evaporation of by-products hardly occurs, so that the protective layer 6 becomes dense, and the barrier property of the protective layer 6 can be improved.
  • the precursor of the siloxane resin has a phenyl group
  • the precursor of the siloxane resin is hydrolyzed and subjected to condensation polymerization, and byproducts generated by the hydrolysis and condensation polymerization of the phenyl group are removed.
  • an insulating paste is formed by mixing a siloxane resin, an organic solvent and a filler in a state in which by-products are removed, the amount of by-products contained in the insulating paste is reduced. .
  • an insulating paste is generated, for example, in the case of applying the insulating paste by screen printing, it is reduced that the emulsion of the screen plate making is dissolved by a by-product. As a result, the dimension of the pattern of the screen plate making is less likely to change.
  • the silane compounds also include, for example, silane compounds in which R1 and R2 have both a phenyl group and an alkyl group.
  • a silane compound for example, trimethoxyphenylsilane (C 6 H 5 -Si- (OCH 3 ) 3 ), dimethoxydiphenylsilane ((C 6 H 5 ) 2 -Si- (OCH 3 ) 2 ), Methoxytriphenylsilane ((C 6 H 5 ) 3 -Si-OCH 3 ), triethoxyphenylsilane (C 6 H 5 -Si- (OC 2 H 5 ) 3 ), diethoxydiphenylsilane ((C 6 H 5) ) 2- Si- (OC 2 H 5 ) 2 ), ethoxytriphenylsilane ((C 6 H 5 ) 3 -Si-OC 2 H 5 ), triisopropoxyphenylsilane (C 6 H 5 -Si- (OC
  • silane compounds for example, if a silane compound containing two or more OR bonds is adopted, a siloxane bond (Si-O-Si bond) is generated by causing condensation polymerization after the silane compound is hydrolyzed. The number of) can be increased. This can increase the number of siloxane bond networks in the silicon oxide that forms the protective layer 6. As a result, the barrier properties of the protective layer 6 can be improved.
  • the silazane compound may be either an inorganic silazane compound or an organic silazane compound.
  • examples of the inorganic silazane compound include polysilazane (— (H 2 SiNH) —).
  • the organic silazane compound for example, hexamethyldisilazane ((CH 3 ) 3 -Si-NH-Si- (CH 3 ) 3 ), tetramethylcyclodisilazane ((CH 3 ) 2 -Si- (NH) 2 And -Si- (CH 3 ) 2 ) and tetraphenylcyclodisilazane ((C 6 H 5 ) 2 -Si- (NH) 2 -Si- (C 6 H 5 ) 2 ).
  • Water is a liquid for hydrolyzing the precursor of the siloxane resin.
  • pure water is used as water.
  • water reacts to the bond of Si-OCH 3 of the silane compound to form Si-OH bond and HO-CH 3 (methanol).
  • the organic solvent is a solvent for producing a paste containing a siloxane resin from a precursor of the siloxane resin. Moreover, the organic solvent can mix the precursor of siloxane resin, and water.
  • the organic solvent for example, diethylene glycol monobutyl ether, methyl cellosolve, ethyl cellosolve, ethyl alcohol, 2- (4-methylcyclohex-3-enyl) propan-2-ol, 2-propanol or the like is used.
  • any one of these organic solvents and an organic solvent in which two or more organic solvents are mixed may be used.
  • the catalyst can control the rate of reaction as the precursor of the siloxane resin undergoes hydrolysis and condensation polymerization.
  • hydrolysis and condensation polymerization are caused to the Si-OR bond (for example, R is an alkyl group) included in the precursor of the siloxane resin to generate Si-O-Si bond and H 2 O from two or more Si-OH bonds.
  • the rate of reaction to produce (water) can be adjusted.
  • the catalyst for example, one or more inorganic acids or one or more organic acids of hydrochloric acid, nitric acid, sulfuric acid, boric acid, phosphoric acid, hydrofluoric acid, acetic acid and the like are used.
  • a catalyst for example, one or more types of inorganic bases or one or more types of organic bases among ammonia, sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide and pyridine may be used.
  • the catalyst may be, for example, a combination of an inorganic acid and an organic acid, or a combination of an inorganic base and an organic base.
  • the filler is, for example, an inorganic filler containing silicon oxide, aluminum oxide or titanium oxide.
  • the concentration of the precursor of the siloxane resin becomes 7 mass% to 60 mass%, and the concentration of water is 5 mass % To 40 wt% (may be 10 wt% to 20 wt%), the concentration of the catalyst is 1 ppm to 1000 ppm, the concentration of the organic solvent is 5 wt% to 50 wt%, the concentration of the inorganic filler is 3 wt% to It is adjusted to be 30% by mass.
  • a siloxane resin produced by hydrolysis and condensation polymerization of a precursor of a siloxane resin can be contained in the insulating paste at an appropriate concentration. Also, for example, in the insulating paste, excessive increase in viscosity due to gelation does not easily occur.
  • the siloxane resin precursor and water react with each other to initiate hydrolysis of the siloxane resin precursor. Also, the precursor of the hydrolyzed siloxane resin causes condensation polymerization to begin to form the siloxane resin.
  • the mixed solution is stirred.
  • the mixed solution is stirred using, for example, a mix rotor or a stirrer.
  • the hydrolysis of the precursor of the siloxane resin further proceeds.
  • the precursor of the hydrolyzed siloxane resin causes condensation polymerization, and the siloxane resin continues to be produced.
  • the rotation conditions of the rotation roller of the mix rotor are set to about 400 rpm to 600 rpm, and the stirring conditions are set such that the stirring time is about 30 minutes to 90 minutes.
  • stirring conditions are adopted, the precursor of the siloxane resin, water, the catalyst and the organic solvent can be uniformly mixed.
  • the mixed solution when the mixed solution is stirred, for example, if the mixed solution is heated, hydrolysis and condensation polymerization of the precursor of the siloxane resin easily proceed. As a result, for example, the productivity can be improved by shortening the stirring time, and the viscosity of the mixed solution can be easily stabilized.
  • the first insulating paste can be manufactured by volatilizing water and the catalyst from the mixed solution.
  • the by-products and the organic solvent are also volatilized so that the emulsion of the screen is unlikely to melt and change in size.
  • By-products include, for example, organic components such as alcohols generated by the reaction of a siloxane resin precursor with water.
  • the processing temperature is about room temperature to 90 ° C. (may be about 50 ° C. to 90 ° C.) and the processing time is about 10 minutes to 600 minutes.
  • the mixed solution after stirring is treated.
  • By-products can be removed if the treatment temperature is within the above temperature range.
  • the organic component which is a by-product is easily volatilized within the said temperature range, the improvement of productivity by shortening of processing time may be achieved.
  • the by-product organic component is likely to be volatilized.
  • productivity can be improved by shortening the processing time.
  • the precursor of the siloxane resin remaining without being hydrolyzed may be further hydrolyzed.
  • the method for producing the second insulating paste can be realized, for example, by adding an organic filler to the mixed solution in place of all or part of the inorganic filler in the method for producing the first insulating paste described above.
  • the organic filler is added to the mixed solution after volatilizing the by-products and the organic solvent in the mixed solution so that the dissolution of the organic filler by the by-product and the organic solvent in the mixed solution is less likely to occur.
  • the mixed solution may be stirred.
  • the organic filler for example, one containing as a main component a material that causes thermal decomposition at a temperature at which the second insulating paste is dried when forming the protective layer 6 is employed.
  • the temperature at which the organic filler causes thermal decomposition is, for example, 300 ° C. or less.
  • Such materials include acrylic materials and the like.
  • the average particle size of the organic filler is, for example, about 1 ⁇ m or less.
  • the viscosity of the mixed solution and the concave portion 6pr formed in the protective layer 6 The number can be easily adjusted.
  • the semiconductor substrate 1 has a first surface 1 bs and a second surface 1 fs facing in the opposite direction to the first surface 1 bs.
  • the semiconductor substrate 1 is prepared as shown in FIG.
  • the semiconductor substrate 1 can be formed, for example, using the existing CZ method or casting method.
  • an example using a p-type polycrystalline silicon ingot manufactured by a casting method will be described.
  • the ingot is sliced to a thickness of, for example, 250 ⁇ m or less to manufacture the semiconductor substrate 1.
  • an aqueous solution such as sodium hydroxide, potassium hydroxide, hydrofluoric acid or fluoronitric acid, mechanical damage to the cut surface of the semiconductor substrate 1 And the contaminated layer can be removed.
  • a part of the above-described texture may be formed on the second surface 1 fs of the semiconductor substrate 1, and at least a part of the above-described uneven structure 1 rg may be formed on the first surface 1 bs of the semiconductor substrate 1.
  • the texture is formed on the second surface 1 fs of the semiconductor substrate 1.
  • the texture can be formed by wet etching using an alkaline aqueous solution such as sodium hydroxide or an acidic aqueous solution such as hydrofluoric-nitric acid, or dry etching using a reactive ion etching (RIE) method or the like.
  • RIE reactive ion etching
  • the second semiconductor layer 3 which is an n-type semiconductor region is formed in the surface layer portion on the second surface 1 fs side of the semiconductor substrate 1 having texture.
  • the second semiconductor layer 3 is formed, for example, by applying a paste-like diphosphorus pentoxide (P 2 O 5 ) on the surface of the semiconductor substrate 1 to thermally diffuse phosphorus, or a gaseous oxychloride It can be formed by using a vapor phase thermal diffusion method using phosphorus (POCl 3 ) as a diffusion source.
  • the second semiconductor layer 3 is formed to have, for example, a depth of about 0.1 ⁇ m to 2 ⁇ m and a sheet resistance value of about 40 ⁇ / ⁇ to 200 ⁇ / ⁇ .
  • the semiconductor substrate 1 is subjected to heat treatment for about 5 minutes to 30 minutes at a temperature of about 600 ° C. to 800 ° C. in an atmosphere having a diffusion gas mainly containing POCl 3 or the like.
  • Phosphorous glass is formed on the surface of the semiconductor substrate 1.
  • the semiconductor substrate 1 is subjected to heat treatment for about 10 minutes to about 40 minutes at a relatively high temperature of about 800 ° C. to 900 ° C. in an atmosphere of an inert gas such as argon or nitrogen.
  • an inert gas such as argon or nitrogen.
  • the second semiconductor layer may be formed on the side of the first surface 1 bs.
  • the second semiconductor layer formed on the first surface 1 bs side is removed by etching.
  • the second semiconductor layer formed on the first surface 1 bs side can be removed by immersing a portion on the first surface 1 bs side of the semiconductor substrate 1 in an aqueous solution of hydrofluoric-nitric acid. Thereby, the region having the p-type conductivity type can be exposed on the first surface 1 bs of the semiconductor substrate 1. Thereafter, when the second semiconductor layer 3 is formed, the phosphorus glass attached to the second surface 1 fs side of the semiconductor substrate 1 is removed by etching.
  • the second semiconductor layer formed on the first surface 1 bs side is removed by etching, the second semiconductor layer 3 on the second surface 1 fs side is removed. Removal and damage can be reduced. At this time, the second semiconductor layer formed on the third surface 1 ss of the semiconductor substrate 1 may be removed together.
  • a diffusion mask may be formed in advance on the first surface 1 bs side of the semiconductor substrate 1, the second semiconductor layer 3 may be formed by a vapor phase thermal diffusion method or the like, and then the diffusion mask may be removed.
  • the second semiconductor layer is not formed on the first surface 1 bs side, the step of removing the second semiconductor layer on the first surface 1 bs side is unnecessary.
  • the second semiconductor layer 3 which is an n-type semiconductor layer is located on the second surface 1 fs side, has texture on the second surface 1 fs, and has the concavo-convex structure 1 rg on the first surface 1 bs.
  • the semiconductor substrate 1 including the one semiconductor layer 2 can be prepared.
  • the step of forming passivation layer 4 (also referred to as a second step) is performed.
  • the passivation layer 4 is formed at least on the first surface 1 bs of the semiconductor substrate 1.
  • aluminum oxide is mainly contained on the first surface 1 bs of the first semiconductor layer 2 and the second surface 1 fs of the second semiconductor layer 3.
  • the passivation layer 4 is formed.
  • the antireflective layer 5 is formed on the passivation layer 4.
  • the antireflection layer 5 is made of, for example, a silicon nitride film or the like.
  • Passivation layer 4 can be formed by, for example, a CVD method or an ALD method. According to the ALD method, for example, the passivation layer 4 can be formed all around the semiconductor substrate 1 including the third surface 1ss.
  • the step of forming the passivation layer 4 by the ALD method first, the semiconductor substrate 1 on which the second semiconductor layer 3 is formed is placed in the chamber of the film forming apparatus. Then, in a state where the semiconductor substrate 1 is heated to a temperature range of about 100 ° C. to about 250 ° C., the following steps A to D are repeated a plurality of times to form a passivation layer 4 mainly containing aluminum oxide. Thereby, the passivation layer 4 having a desired thickness is formed.
  • Step A An aluminum source such as trimethylaluminum (TMA) for forming aluminum oxide is supplied onto the semiconductor substrate 1 together with a carrier gas such as Ar gas or nitrogen gas. Thereby, the aluminum source is adsorbed on the entire periphery of the semiconductor substrate 1.
  • the time for which the TMA is supplied is, for example, about 15 milliseconds (msec: msec) to about 3000 milliseconds.
  • the surface of the semiconductor substrate 1 may be terminated with an OH group.
  • the surface of the semiconductor substrate 1 may have a Si—O—H structure. This structure can be formed, for example, by treating the semiconductor substrate 1 with dilute hydrofluoric acid and then washing with pure water.
  • Step B The inside of the chamber of the film forming apparatus is cleaned with nitrogen gas, whereby the aluminum source in the chamber is removed. Furthermore, among the aluminum raw materials physically and chemically adsorbed to the semiconductor substrate 1, aluminum raw materials other than the components chemically adsorbed at the atomic layer level are removed.
  • the time for cleaning the inside of the chamber with nitrogen gas is, for example, about one second (sec) to several tens of seconds.
  • Step C By supplying an oxidizing agent such as water or ozone gas into the chamber of the film forming apparatus, the alkyl group contained in TMA is removed and substituted by an OH group. Thereby, an atomic layer of aluminum oxide is formed on the semiconductor substrate 1.
  • the time during which the oxidizing agent is supplied into the chamber is, for example, about 750 milliseconds to 1100 milliseconds. Also, for example, if hydrogen is supplied together with the oxidizing agent in the chamber, the hydrogen atoms are more easily contained in the aluminum oxide.
  • Step D The oxidizing agent in the chamber is removed by cleaning the chamber of the film forming apparatus with nitrogen gas. At this time, for example, an oxidizing agent which does not contribute to the reaction at the time of formation of aluminum oxide at the atomic layer level on the semiconductor substrate 1 is removed.
  • the time during which the inside of the chamber is purified by nitrogen gas is, for example, about one second or more to several tens of seconds.
  • step A a layer of aluminum oxide having a desired film thickness is formed.
  • the antireflective layer 5 is formed, for example, using a PECVD method or a sputtering method.
  • the semiconductor substrate 1 is previously heated to a temperature higher than the temperature during the formation of the antireflective layer 5. Thereafter, a mixed gas of silane (SiH 4 ) and ammonia (NH 3 ) is diluted with nitrogen (N 2 ) gas, and the reaction pressure is set to about 50 Pa to 200 Pa, and the one that has been plasmatized by glow discharge decomposition is It is deposited on the heated semiconductor substrate 1.
  • the antireflective layer 5 is formed on the semiconductor substrate 1.
  • the film forming temperature is set to about 350 ° C.
  • the preheating temperature of the semiconductor substrate 1 is set to about 50 ° C. higher than the film forming temperature.
  • a frequency of about 10 kHz to 500 kHz is adopted as the frequency of the high frequency power source required for the glow discharge.
  • the flow rate of the gas is appropriately determined depending on the size of the reaction chamber and the like.
  • the flow rate of the gas may be in the range of about 150 milliliters / minute (sccm) to about 6000 milliliters / minute (sccm).
  • the value (B / A) obtained by dividing the flow rate B of the ammonia gas by the flow rate A of the silane gas is in the range of 0.5 to 15.
  • the step of forming the protective layer 6 (also referred to as a third step) is performed.
  • the protective layer 6 is formed by applying a solution so as to form a pattern including the hole CH1 on the passivation layer 4 at least on the first surface 1 bs side of the semiconductor substrate 1 and drying the solution. Is formed.
  • the protective layer 6 having the plurality of concave portions 6pr can be formed.
  • Such a protective layer 6 can be formed, for example, by the following process.
  • a second insulating paste is applied on the layer of the first insulating paste applied on the passivation layer 4.
  • the maximum temperature of the first insulating paste and the second insulating paste after application is set to about 200 ° C. to 350 ° C. using a hot plate or a drying furnace, and the heating time is about 1 minute to 10 minutes. Dry under the conditions that are considered.
  • a protective layer region 6 b is formed.
  • the organic filler contained in the second insulating paste is thermally decomposed by the heat treatment at the time of drying. Thereby, the part which the organic filler lose
  • such a protective layer 6 may be formed, for example, by the following process.
  • the first insulating paste is applied on the passivation layer 4.
  • a second insulating paste is applied on the layer of the first insulating paste applied on the passivation layer 4.
  • the organic filler contained in the second insulating paste does not undergo thermal decomposition, using the first insulating paste and the second insulating paste after application, using a hot plate or a drying furnace, etc., relatively It is dried at a low temperature (for example, about 100 ° C.).
  • an organic solvent is used to dissolve the organic filler located on the surface of the dried second insulating paste.
  • a drying process of evaporating the organic solvent is performed using a hot plate, a drying furnace, or the like. Thereby, a protective layer 6 having a plurality of concave portions 6pr on the surface is formed.
  • the first insulating paste and the second insulating paste described above are applied in a desired pattern on at least a part of the passivation layer 4 using, for example, a spray method, a coater method, a screen printing method, or the like.
  • the protective layer 6 is formed on at least a part of the passivation layer 4.
  • a step of forming an electrode including the front surface electrode 7 and the back surface electrode 8 (also referred to as a fourth step) is performed.
  • a material for electrode formation is disposed on the protective layer 6 and in the hole CH1, and the material for electrode formation is heated, whereby the back electrode 8 is formed.
  • the back surface electrode 8 formed at this time includes the second output extraction electrode 8 a and the second current collection electrode 8 b.
  • the second current collection electrode 8b includes an electrode layer 8bl and a connection portion 8bc.
  • the surface electrode 7 and the back surface electrode 8 are formed.
  • the surface electrode 7 is produced using, for example, a metal powder containing silver as a main component, an organic vehicle, and a second metal paste (also referred to as a silver paste) containing a glass frit.
  • a metal powder containing silver as a main component an organic vehicle
  • a second metal paste also referred to as a silver paste
  • the second metal paste is applied to the second surface 1 fs side of the semiconductor substrate 1.
  • the second metal paste is applied on the antireflection layer 5 formed on the passivation layer 4 on the second surface 1 fs.
  • the application of the second metal paste can be realized by, for example, screen printing.
  • the solvent in the second metal paste may be evaporated and dried at a predetermined temperature.
  • the first output extraction electrode 7a, the first current collection electrode 7b, and the auxiliary electrode 7c included in the surface electrode 7 can be formed in one step. Thereafter, for example, the surface metal 7 is fired by firing the second metal paste under the condition that the maximum temperature is set to 600 ° C. to 850 ° C. in the firing furnace and the heating time is set to about several tens seconds to several tens of minutes. Form.
  • the second output lead-out electrode 8a included in the back surface electrode 8 is manufactured using, for example, a third metal paste (also referred to as silver paste) containing a metal powder containing silver as a main component, an organic vehicle, a glass frit and the like.
  • a third metal paste also referred to as silver paste
  • a screen printing method can be used.
  • the solvent in the third metal paste may be evaporated and dried at a predetermined temperature.
  • the second output extraction electrode is fired by firing the third metal paste under the condition that the maximum temperature is set to 600 ° C. to 850 ° C. in the firing furnace and the heating time is set to about several tens of seconds to several tens of minutes.
  • 8 a is formed on the first surface 1 bs side of the semiconductor substrate 1.
  • the second current collection electrode 8b included in the back surface electrode 8 is produced, for example, using a first metal paste (Al paste) containing a metal powder containing aluminum as a main component, an organic vehicle and a glass frit.
  • a first metal paste Al paste
  • the first metal paste is applied to the first surface 1 bs side of the semiconductor substrate 1 so as to be in contact with a part of the previously applied third metal paste.
  • the first metal paste is applied on the protective layer 6 formed on the passivation layer 4 on the first surface 1 bs and in the hole CH1.
  • the first metal paste may be applied to almost the entire surface on the first surface 1 bs side of the semiconductor substrate 1 except for a part of the portion where the second output lead-out electrode 8 a is formed.
  • the application of the first metal paste can be realized by, for example, screen printing. Further, at this time, the first metal paste also intrudes into the internal space SC1 of the plurality of concave portions 6pr of the protective layer 6.
  • the solvent in the first metal paste may be evaporated and dried at a predetermined temperature.
  • the second current collection is performed by firing the first metal paste under the condition that the maximum temperature is set to 600 ° C. to 850 ° C. in the firing furnace and the heating time is about several tens seconds to several tens of minutes.
  • the electrode 8 b is formed on the first surface 1 bs side of the semiconductor substrate 1. At this time, an electrode component including the glass of the second current collection electrode 8b enters the internal space SC1 of the plurality of concave portions 6pr of the protective layer 6.
  • the first metal paste fires through the passivation layer 4 when it is fired, and is electrically connected to the first semiconductor layer 2.
  • the second current collection electrode 8b is formed.
  • the third semiconductor layer 2bs is also formed along with the formation of the second current collection electrode 8b.
  • the first metal paste on the protective layer 6 is blocked by the protective layer 6. Therefore, when the first metal paste is fired, the passivation layer 4 blocked by the protective layer 6 is hardly affected by the firing.
  • the back electrode 8 can be formed.
  • the first metal paste and the third metal paste are employed as the material for forming the back electrode 8.
  • the second output lead-out electrode 8a may be formed after the second current collection electrode 8b is formed. Even when the second output lead-out electrode 8a is in direct contact with the semiconductor substrate 1, for example, the passivation layer 4 is present between the second output lead-out electrode 8a and the semiconductor substrate 1, It does not have to be in contact.
  • the second output lead electrode 8 a may be formed on the protective layer 6.
  • the surface electrode 7 and the back surface electrode 8 may be formed by applying baking after simultaneously applying each metal paste. Thereby, the productivity of the solar cell element 10 can be improved. Further, in this case, the heat history applied to the semiconductor substrate 1 is reduced, so that the output characteristics of the solar cell element 10 can be improved.
  • the glass in a state in which the electrode layer 8 bl of the second current collection electrode 8 b is formed in the concave portion 6 pr existing in the convex portion 6 p of the protective layer 6 An electrode component comprising the component is located. If such a configuration is adopted, for example, when the first metal paste is applied on the protective layer 6 to form the second current collecting electrode 8 b, the uneven structure exists on the surface of the protective layer 6. Also, the glass component or the like in the first metal paste intrudes into the concave portion 6pr present in the convex portion 6p.
  • the adhesion between the protective layer 6 and the metal particles in the second current collection electrode 8b can be improved in the convex portion 6p due to the presence of the glass component.
  • a so-called anchor effect may occur when a part of the second current collection electrode 8b enters the concave portion 6pr of the protective layer 6, a so-called anchor effect may occur.
  • the adhesion of the second current collection electrode 8 b to the protective layer 6 can be improved.
  • partial peeling of the second current collection electrode 8 b from the protective layer 6 does not easily occur. Therefore, the photoelectric conversion efficiency in the PERC solar cell element 10 can be improved.
  • the protective layer 6 has a plurality of air gaps 6vd located inside the protective layer 6.
  • the diameter of the void 6vd is d4.
  • a mode in which the diameter d4 is shorter than any one of the second distance D2 between adjacent convex portions 6p and the third distance D3 between adjacent connection portions 8bc may be considered.
  • the air gap 6vd for example, a minute air gap having an internal space of a diameter d4 of about 0.1 ⁇ m to 1 ⁇ m is adopted.
  • the thickness (minimum film thickness) of the protective layer 6 excluding the void 6vd is 0.5 ⁇ m. If it is about above, the function which protects passivation layer 4 by protective layer 6 may be secured.
  • the protective layer 6 when the protective layer 6 is formed and when the solar cell element 10 is used, the protective layer 6 may expand or contract according to the temperature change, and may cause contraction according to the condensation polymerization reaction of the protective layer 6 is there. At this time, stress may be generated between the protective layer 6 and a layer adjacent to the protective layer 6 (also referred to as an adjacent layer).
  • a layer adjacent to the protective layer 6 also referred to as an adjacent layer.
  • stress generated between the protective layer 6 and an adjacent layer in a state adjacent to the protective layer 6 occurs.
  • And may be relieved by the plurality of air gaps 6 vd in the protective layer 6.
  • peeling does not easily occur between the protective layer 6 and the adjacent layer in a state adjacent to the protective layer 6.
  • the photoelectric conversion efficiency in the PERC solar cell element 10 can be improved.
  • the distance (also referred to as a fourth distance) between adjacent gap portions 6 vd among the plurality of void portions 6 vd is set to D4.
  • the fourth distance D4 for example, the distance between the centers of the adjacent air gaps 6vd is adopted.
  • the fourth distance D4 may be, for example, the average value of the distance between the centers of the adjacent void portions 6vd, or the separation distance between the adjacent void portions 6vd, or the adjacent void portions 6vd.
  • the density of the plurality of air gaps 6 vd in the protective layer 6 is somewhat high. Thereby, for example, the stress generated between the protective layer 6 and the adjacent layer in a state adjacent to the protective layer 6 is easily relaxed by the plurality of voids 6 vd in the protective layer 6. For this reason, the photoelectric conversion efficiency in the PERC solar cell element 10 can be easily improved.
  • the protective layer 6 having the plurality of voids 6 vd inside can be formed, for example, by the following process.
  • the first insulating paste is applied on the passivation layer 4.
  • a second insulating paste is applied on the layer of the first insulating paste applied on the passivation layer 4.
  • the first insulating paste is applied on the layer of the second insulating paste applied on the layer of the first insulating paste.
  • the second insulating paste is applied on the layer of the first insulating paste applied on the layer of the second insulating paste.
  • the layer of the first insulating paste, the layer of the second insulating paste, the layer of the first insulating paste, and the layer of the second insulating paste after application are dried using a hot plate or a drying furnace. At this time, as the drying conditions, a maximum temperature of about 200 ° C.
  • a heating time of about 1 minute to 10 minutes are adopted.
  • Ru a heating time of about 1 minute to 10 minutes.
  • the first protective layer region 6a and the third protective layer region 6c are formed by drying the first insulating paste.
  • the second protective layer region 6b and the fourth protective layer region 6d are formed by drying the second insulating paste.
  • the organic filler contained in the second insulating paste is thermally decomposed by the heat treatment at the time of drying.
  • a plurality of void portions 6vd are formed in the second protective layer region 6b by the disappearance of the organic filler, and a plurality of concave portions 6pr are formed in the surface of the fourth protective layer region 6d by the disappearance of the organic filler.
  • a protective layer 6 having a plurality of concave portions 6pr on the surface and a plurality of voids 6vd on the inside can be formed.
  • a layer in which an organic binder is contained in the first insulating paste may be applied instead of the layer of the second insulating paste for forming the second protective layer region 6b of FIG. 11.
  • the plurality of void portions 6vd are formed by volatilization of a part of the organic binders among the organic binders present in the layer of the first insulating paste. It can occur.
  • the layer of the second insulating paste for forming at least one of the fourth protective layer region 6d of FIG. 11 and the second protective layer region 6b of FIG. A layer containing a binder may be applied.
  • the plurality of concave portions 6pr are formed by volatilization of a part of the organic binder among the organic binders present in the layer of the first insulating paste. It can occur.
  • the protective layer 6 when the protective layer 6 is seen through from the electrode layer 8bl side of the second current collection electrode 8b, the protective layer 6 is per unit area of the concave portion 6pr.
  • the first region Ar1 and the second region Ar2 may have different numbers.
  • the first region Ar1 is located on the outer peripheral portion OP1 side of the solar cell element 10.
  • the second region Ar2 is located on the central portion CP1 side of the solar cell element 10.
  • the unit area is set to, for example, about 100 mm 2 to 400 mm 2 .
  • the number per unit area of concave portions 6pr present in the first region Ar1 may be larger than the number per unit area of concave portions 6pr present in the second region Ar2.
  • the protective layer 6 having the first area Ar1 and the second area Ar2 may be formed, for example, when the second insulating paste is applied on the layer of the first insulating paste applied on the passivation layer 4. It can be formed by performing the following process. First, the second insulating paste is applied to a region corresponding to the first region Ar1. Next, a second insulating paste having a lower organic filler content than the already applied second insulating paste is applied to the area corresponding to the second area Ar2. Also, for example, in such a process, the second insulating paste is applied on the layer of the first insulating paste applied on the passivation layer 4 to form the first insulating paste and the second insulating paste.
  • the drying may be performed when the second insulating paste is applied on the layer of the first insulating paste further applied on the layer of the second insulating paste.
  • the protective layer 6 having the plurality of void portions 6vd and the first region Ar1 and the second region Ar2 can be formed.
  • the solar cell modules 100 are positioned in a state in which the plurality of solar cell elements 10 are electrically connected in series by the wiring member Tb and aligned in a plane.
  • a plurality of solar cell modules are covered with the sealing material 102 in the gap between the first protective member 101 and the second protective member 104 located in a state of facing each other.
  • a portion (also referred to as a photoelectric conversion portion) 103 including the element 10 is located.
  • the solar cell module 100 has a surface (also referred to as a front surface) 100 fs that mainly receives light, and a surface (also referred to as a back surface) 100 bs that is located on the opposite side of the front surface 100 fs.
  • the light transmitting plate-like second protection member 104 is positioned on the front surface 100 fs side
  • the plate-like or sheet-like first protection member 101 is positioned on the back surface 100 bs.
  • the sealing material 102 located in the gap between the first protective member 101 and the second protective member 104 is located on the front surface 100 fs side with the first sealing material 102 b located on the back surface 100 bs side.
  • a second sealing material 102u is used in the solar cell module 100 .
  • this solar cell module 100 includes a first protective member 101, a first sheet SH1, a photoelectric conversion unit 103, a second sheet SH2, and a second protective member 104.
  • stacked in order of this description may be manufactured by integrating by lamination process.
  • the first sheet SH1 is a sheet-like material that is the source of the first sealing material 102b
  • the second sheet SH2 is a sheet-like material that is the source of the second sealing material 102u.
  • the thickness of the sealing material 102 is large between several solar cell elements 10 comrades. For this reason, expansion and contraction of the sealing material 102 become large between the plurality of solar cell elements 10.
  • the protective layer 6 and the second collection are formed in the first region Ar1 on the outer peripheral portion OP1 side than the second region Ar2 on the central portion CP1 side.
  • the adhesion to the electrode 8 b is high. For this reason, for example, when the lamination process of a laminated body is performed, it is hard to peel off the 2nd current collection electrode 8b from the protective layer 6. As shown in FIG.
  • the second output lead-out electrode 8 a located on the protective layer 6 may be an electrode layer containing a glass component.
  • the glass component of the second output extraction electrode 8 a may be located in the internal space of the concave portion 6 pr of the protective layer 6.
  • the ratio of the concave portion 6pr to the area of the unit area in the convex portion 6p is 5% to 40. It is not limited to about%.
  • This ratio is appropriately set according to, for example, the content of the glass component and the type of the glass component in the second current collection electrode 8 b or the first metal paste for forming the second current collection electrode 8 b.
  • the adhesion of the second current collection electrode 8b to the protective layer 6 can be easily improved. In other words, for example, even if this ratio is appropriately set to a range of a different ratio including a part or all of the range of about 5% to 40% or a range of a ratio different from about 5% to about 40% Good.
  • the passivation layer 4 is positioned from the top of the first surface 1 bs to the top of the third surface 1 ss, and the protective layer 6 is Although it has been located on the passivation layer 4 located on the outer edge Ed1 of the surface 1bs, it is not limited thereto.
  • the passivation layer 4 and the protective layer 6 on the region (also referred to as the outer edge region) Ao1 along the outer edge Ed1 of the first surface 1bs of the first surface 1bs, the passivation layer 4 and the protective layer 6
  • the antireflective layer 5 may not be located.
  • the passivation layer 4 and the antireflective layer 5 located on the third surface 1ss and the passivation layer 4 and the protective layer 6 located on the first surface 1bs are separated on the outer peripheral area Ao1. It may be At this time, it is conceivable that the outer edge area Ao1 is located in the range of the distance L1 from the outer edge Ed1 of the first surface 1bs.
  • the distance L1 may be, for example, about 0.5 mm to 2 mm.
  • the second current collection electrode 8b may not be located on the outer edge area Ao1 of the first surface 1bs. As shown in FIG.
  • the second current collection electrode 8b may be located on at least a part of the outer edge area Ao1 of the first surface 1bs.
  • the third surface 1s to the upper surface of a portion on the outer edge portion Ed1 of the outer edge region Ao1 of the first surface 1bs.
  • Passivation layer 4 and anti-reflective film 5 may be located. At this time, it is conceivable that the passivation layer 4 and the anti-reflection film 5 are located in the range of the distance L2 from the outer edge portion Ed1 on the outer edge region Ao1.
  • the distance L2 may be, for example, about 0.1 mm to 1 mm.
  • a passivation layer is formed from the third surface 1ss to the outer surface area Ao1 of the first surface 1bs.
  • the anti-reflection layer 5 may be positioned to a portion closer to the central portion of the first surface 1 bs than 4.
  • both the passivation layer 4 and the anti-reflection film 5 may be located from the outer edge portion Ed1 to the portion of the distance L2 on the outer edge region Ao1.
  • the second current collection is performed on at least a part of the outer edge area Ao1 of the first surface 1bs.
  • the electrode 8b may be located.

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Abstract

A solar cell element comprises: a semiconductor substrate; a passivation layer; a protective layer; and an electrode layer. The passivation layer is positioned above a first surface of the semiconductor substrate. The protective layer is positioned above the passivation layer. The electrode layer is positioned above the protective layer, and includes a glass component. The protective layer has a plurality of convex parts positioned at a surface of the electrode layer side. The plurality of convex parts respectively have a concave portion at the electrode layer side. The glass component is positioned in the internal space of the concave portion.

Description

太陽電池素子Solar cell element
　本開示は、太陽電池素子に関する。 The present disclosure relates to a solar cell element.
　太陽電池素子には、ＰＥＲＣ（Passivated Emitter and Rear Cell）型の太陽電池素子がある（例えば、特開２０１３－４９４４号公報の記載を参照）。この太陽電池素子では、半導体基板の裏面上にパッシベーション層が位置している。さらに、パッシベーション層の上、あるいはパッシベーション層の上に位置している保護層の上に、裏面側の集電電極が位置している。 As a solar cell element, there is a PERC (Passivated Emitter and Rear Cell) type solar cell element (see, for example, the description of Japanese Patent Application Laid-Open No. 2013-4944). In this solar cell element, the passivation layer is located on the back surface of the semiconductor substrate. Furthermore, the back side current collection electrode is located on the passivation layer or on the protective layer located on the passivation layer.
　太陽電池素子が開示される。 A solar cell element is disclosed.
　太陽電池素子の一態様は、半導体基板と、パッシベーション層と、保護層と、電極層と、を備えている。前記パッシベーション層は、前記半導体基板の第１面の上に位置している。前記保護層は、前記パッシベーション層の上に位置している。前記電極層は、前記保護層の上に位置し、ガラス成分を含む。前記保護層は、前記電極層側の面に位置している複数の凸状部を有する。該複数の凸状部は、それぞれ前記電極層側に凹状部分を有する。該凹状部分の内部空間には、前記ガラス成分が位置している。 One aspect of a solar cell element includes a semiconductor substrate, a passivation layer, a protective layer, and an electrode layer. The passivation layer is located on the first surface of the semiconductor substrate. The protective layer is located on the passivation layer. The electrode layer is located on the protective layer and includes a glass component. The protective layer has a plurality of convex portions located on the surface on the electrode layer side. Each of the plurality of convex portions has a concave portion on the electrode layer side. The glass component is located in the internal space of the concave portion.
図１は、第１実施形態に係る太陽電池素子の一例の前面側の外観を示す平面図である。FIG. 1 is a plan view showing the appearance of the front side of an example of the solar cell element according to the first embodiment. 図２は、第１実施形態に係る太陽電池素子の一例の裏面側の外観を示す平面図である。FIG. 2: is a top view which shows the external appearance of the back surface side of an example of the solar cell element which concerns on 1st Embodiment. 図３は、図１および図２のIII－III線に沿った太陽電池素子の仮想的な切断面部の一例を示す図である。FIG. 3 is a view showing an example of a virtual cut surface portion of the solar cell element taken along the line III-III in FIG. 1 and FIG. 図４（ａ）は、図３の部分Ｐ１の仮想的な切断面部の一例を示す拡大図である。図４（ｂ）は、図４（ａ）の部分Ｐ１１の仮想的な切断面部の一例を示す拡大図である。FIG. 4A is an enlarged view showing an example of a virtual cut surface portion of the portion P1 of FIG. FIG.4 (b) is an enlarged view which shows an example of the virtual cut surface part of the part P11 of Fig.4 (a). 図５（ａ）は、図３の部分Ｐ１の仮想的な切断面部の一例を示す拡大図である。図５（ｂ）は、図５（ａ）の部分Ｐ１１の仮想的な切断面部の一例を示す拡大図である。FIG. 5A is an enlarged view showing an example of a virtual cut surface portion of the portion P1 of FIG. 3. FIG.5 (b) is an enlarged view which shows an example of the virtual cut surface part of the part P11 of Fig.5 (a). 図６（ａ）は、一参考例に係る太陽電池素子についてのピール試験の条件を説明するための図である。図６（ｂ）は、一参考例に係る太陽電池素子についてのピール試験の結果を示す図である。Fig.6 (a) is a figure for demonstrating the conditions of the peel test about the solar cell element which concerns on one reference example. FIG.6 (b) is a figure which shows the result of the peeling test about the solar cell element which concerns on one reference example. 図７は、図５（ａ）の部分Ｐ１２の仮想的な切断面部の一例を示す拡大図である。FIG. 7 is an enlarged view showing an example of a virtual cut surface portion of the portion P12 of FIG. 5 (a). 図８（ａ）から図８（ｆ）は、それぞれ第１実施形態に係る太陽電池素子を製造する途中の状態における、図３の仮想的な切断面部に対応する仮想的な切断面部の一例を示す図である。FIGS. 8 (a) to 8 (f) each show an example of a virtual cut surface portion corresponding to the virtual cut surface portion of FIG. 3 in a state in the middle of manufacturing the solar cell element according to the first embodiment. FIG. 図９は、第１実施形態に係る保護層の構造の一例を説明するための図である。FIG. 9 is a view for explaining an example of the structure of the protective layer according to the first embodiment. 図１０（ａ）は、第２実施形態に係る太陽電池素子のうち、図４（ａ）の部分Ｐ１１に対応する部分の仮想的な切断面部の一例を示す拡大図である。図１０（ｂ）は、第２実施形態に係る太陽電池素子のうち、図５（ａ）の部分Ｐ１１に対応する部分の仮想的な切断面部の一例を示す拡大図である。Fig.10 (a) is an enlarged view which shows an example of the virtual cutting plane part of the part corresponding to the part P11 of Fig.4 (a) among the solar cell elements which concern on 2nd Embodiment. FIG.10 (b) is an enlarged view which shows an example of the virtual cutting plane part of the part corresponding to the part P11 of Fig.5 (a) among the solar cell elements which concern on 2nd Embodiment. 図１１は、第２実施形態に係る保護層の構造の一例を説明するための図である。FIG. 11 is a view for explaining an example of the structure of the protective layer according to the second embodiment. 図１２は、第３実施形態に係る太陽電池素子の一例の裏面側の外観を示す平面図である。FIG. 12 is a plan view showing the appearance of the back surface side of an example of the solar cell element according to the third embodiment. 図１３は、第３実施形態に係る太陽電池モジュールの一例の前面側の外観を示す平面図である。FIG. 13 is a plan view showing an appearance of a front side of an example of a solar cell module according to a third embodiment. 図１４は、図１３のXIV－XIV線に沿った太陽電池素子の仮想的な切断面部の一例を示す図である。FIG. 14 is a view showing an example of a virtual cross section of the solar cell element taken along line XIV-XIV in FIG. 図１５は、第３実施形態に係る太陽電池モジュールを製造する途中の状態における、図１４の仮想的な切断面部に対応する仮想的な切断面部の一例を示す図である。FIG. 15 is a view showing an example of a virtual cut surface part corresponding to the virtual cut surface part of FIG. 14 in a state where the solar cell module according to the third embodiment is being manufactured. 図１６（ａ）は、図３の部分Ｐ１６の仮想的な切断面部の一例を示す拡大図である。図１６（ｂ）は、一変形例に係る太陽電池素子のうちの図３の部分Ｐ１６に対応する部分の仮想的な切断面部の第１の例を示す拡大図である。図１６（ｃ）は、一変形例に係る太陽電池素子のうちの図３の部分Ｐ１６に対応する部分の仮想的な切断面部の第２の例を示す拡大図である。FIG. 16A is an enlarged view showing an example of a virtual cut surface portion of the portion P16 of FIG. FIG. 16B is an enlarged view showing a first example of a virtual cut surface portion of a portion corresponding to the portion P16 of FIG. 3 in the solar cell element according to a modification. FIG. 16C is an enlarged view showing a second example of a virtual cut surface portion of a portion corresponding to the portion P16 of FIG. 3 in the solar cell element according to one modification. 図１７（ａ）は、他の一変形例に係る太陽電池素子のうちの図３の部分Ｐ１６に対応する部分の仮想的な切断面部の第１の例を示す拡大図である。図１７（ｂ）は、他の一変形例に係る太陽電池素子のうちの図３の部分Ｐ１６に対応する部分の仮想的な切断面部の第２の例を示す拡大図である。図１７（ｃ）は、他の一変形例に係る太陽電池素子のうちの図３の部分Ｐ１６に対応する部分の仮想的な切断面部の第３の例を示す拡大図である。Fig.17 (a) is an enlarged view which shows the 1st example of the virtual cutting plane part of the part corresponding to the part P16 of FIG. 3 among the solar cell elements which concern on another one modification. FIG. 17B is an enlarged view showing a second example of a virtual cut surface portion of a portion corresponding to the portion P16 of FIG. 3 in a solar cell element according to another modification. FIG. 17C is an enlarged view showing a third example of a virtual cut surface portion of a portion corresponding to the portion P16 of FIG. 3 in a solar cell element according to another modification.
　ＰＥＲＣ型の太陽電池素子が製作される際には、例えば、半導体基板の裏面上に、パッシベーション層と保護層と裏面電極とがこの記載の順に形成される。保護層は、例えば、酸化珪素などで構成される酸化膜、窒化珪素などで構成される窒化膜、または酸化膜と窒化膜とが積層された膜によって構成される。この保護層は、例えば、湿式プロセスまたは乾式プロセスによって形成される。湿式プロセスには、例えば、シロキサン樹脂を含む絶縁性ペーストの塗布と乾燥とを行う塗布法などが適用される。乾式プロセスには、例えば、化学気相成長（Chemical Vapor Deposition：ＣＶＤ）、プラズマＣＶＤ（plasma-enhanced chemical vapor deposition：ＰＥＣＶＤ）またはスパッタリングなどが適用される。 When a PERC type solar cell element is manufactured, for example, a passivation layer, a protective layer, and a back electrode are formed in this order on the back surface of the semiconductor substrate. The protective layer is formed of, for example, an oxide film formed of silicon oxide or the like, a nitride film formed of silicon nitride or the like, or a film in which an oxide film and a nitride film are stacked. This protective layer is formed, for example, by a wet process or a dry process. In the wet process, for example, a coating method for applying and drying an insulating paste containing a siloxane resin is applied. For the dry process, for example, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), sputtering or the like is applied.
　ところで、太陽電池素子における光電変換効率を向上させるために、例えば、半導体基板の前面側に、照射された光の反射を低減するための微細な凹凸構造（テクスチャ）を形成する場合がある。この場合には、半導体基板に対して、例えば、水酸化ナトリウムなどのアルカリ性の水溶液またはフッ硝酸などの酸性の水溶液を用いた湿式のエッチングを施すことで、テクスチャが形成される。このとき、半導体基板の前面だけでなく裏面を含む全面にテクスチャが形成され得る。 By the way, in order to improve the photoelectric conversion efficiency in a solar cell element, the fine concavo-convex structure (texture) for reducing reflection of irradiated light may be formed in the front side of a semiconductor substrate, for example. In this case, a texture is formed on the semiconductor substrate by performing wet etching using, for example, an alkaline aqueous solution such as sodium hydroxide or an acidic aqueous solution such as hydrofluoric-nitric acid. At this time, texture may be formed on the entire surface including the back surface as well as the front surface of the semiconductor substrate.
　このように、半導体基板の裏面にテクスチャなどの凹凸が存在していれば、半導体基板の裏面上に形成される、パッシベーション層および保護層の表面にも凹凸が生じやすい。ここで、例えば、保護層の上に、主としてアルミニウムを含む金属粉末とガラス成分と有機ビヒクルとを含むペースト（金属ペーストともいう）を塗布し、この金属ペーストの焼成を行うことで、裏面側の集電電極を形成する場合がある。この場合には、保護層の表面における凹凸の存在により、金属ペーストの成分の分布に偏りが生じやすい。このため、保護層に対する集電電極の密着強度が不均一になりやすい。これにより、保護層上において集電電極の部分的な剥離が生じるおそれがある。具体的には、例えば、流動性を有するガラス成分および有機ビヒクルが、保護層の凸状部上から金属粉末の間を通って保護層の凹状部上などの重力方向においてより低い部分に流れ込みやすい。このため、保護層の凸状部上において集電電極の部分的な剥離が生じるおそれがある。そして、保護層から集電電極が剥離すると、太陽電池素子の裏面側において集電電極の剥離が進行し、太陽電池素子の裏面側における集電の効率が低下するおそれがある。その結果、太陽電池素子における光電変換効率が低下するおそれがある。 As described above, if there is an unevenness such as texture on the back surface of the semiconductor substrate, the unevenness is easily generated on the surface of the passivation layer and the protective layer formed on the back surface of the semiconductor substrate. Here, for example, a paste containing metal powder mainly containing aluminum, a glass component, and an organic vehicle (also referred to as a metal paste) is applied onto the protective layer, and the metal paste is fired to form the back surface side. It may form a collecting electrode. In this case, the distribution of the components of the metal paste tends to be biased due to the presence of irregularities on the surface of the protective layer. For this reason, the adhesion strength of the current collection electrode to the protective layer tends to be nonuniform. Thereby, there exists a possibility that partial peeling of a current collection electrode may arise on a protective layer. Specifically, for example, it is easy for the fluid glass component and the organic vehicle to flow into the lower part in the direction of gravity such as over the convex portion of the protective layer and between the metal powder and over the concave portion of the protective layer. . For this reason, there exists a possibility that partial peeling of a current collection electrode may arise on the convex-shaped part of a protective layer. And when a current collection electrode exfoliates from a protective layer, exfoliation of a current collection electrode advances on the back side of a solar cell element, and there is a possibility that the efficiency of current collection in the back side of a solar cell element may fall. As a result, the photoelectric conversion efficiency in the solar cell element may be reduced.
　そこで、保護層上における集電電極の部分的な剥離を低減するために、例えば、金属ペーストにおけるガラス成分の含有率を増加させることが考えられる。しかしながら、金属ペーストにおけるガラス成分の含有率が増加すると、金属ペーストの焼成時に、金属ペーストによる保護層のファイヤースルー（焼成貫通）が生じやすい。このため、太陽電池素子の裏面側におけるパッシベーション効果の低下によって、太陽電池素子における光電変換効率が低下するおそれがある。 Then, in order to reduce the partial peeling of the current collection electrode on a protective layer, it is possible to, for example, increase the content rate of the glass component in a metal paste. However, when the content of the glass component in the metal paste is increased, fire through (fired penetration) of the protective layer by the metal paste tends to occur at the time of firing the metal paste. For this reason, there exists a possibility that the photoelectric conversion efficiency in a solar cell element may fall by the fall of the passivation effect in the back surface side of a solar cell element.
　また、上記の点に対して、例えば、金属ペーストによる保護層のファイヤースルーを生じにくくするために、保護層の厚さを大きくすることが考えられる。しかしながら、保護層の厚さが大きくなると、金属ペーストの焼成時および太陽電池素子の使用時に、半導体基板と保護層との間において、温度変化に伴う膨張および収縮によって生じる応力が大きくなりやすい。これにより、半導体基板の裏面側から保護層が剥離するおそれがある。また、例えば、保護層の温度変化に伴う膨張および収縮によって半導体基板と保護層との間で生じる応力が大きくなると、太陽電池素子の反りが増大して、太陽電池素子にクラックあるいは割れが生じるおそれがある。その結果、太陽電池素子における光電変換効率が低下するおそれがある。 Moreover, in order to make it hard to produce fire through of the protective layer by a metal paste with respect to said point, it is possible to enlarge the thickness of a protective layer, for example. However, when the thickness of the protective layer is increased, stress caused by expansion and contraction with temperature change tends to be increased between the semiconductor substrate and the protective layer during firing of the metal paste and when using the solar cell element. Thus, the protective layer may be peeled off from the back surface side of the semiconductor substrate. In addition, for example, if the stress generated between the semiconductor substrate and the protective layer increases due to expansion and contraction accompanying the temperature change of the protective layer, the warpage of the solar cell element may increase, and the solar cell element may be cracked or broken. There is. As a result, the photoelectric conversion efficiency in the solar cell element may be reduced.
　そこで、本発明者らは、ＰＥＲＣ型の太陽電池素子について、光電変換効率を向上させることができる技術を創出した。 Therefore, the present inventors have created a technology that can improve the photoelectric conversion efficiency of a PERC type solar cell element.
　これについて、以下、各種実施形態を図面に基づいて説明する。図面においては同様な構成および機能を有する部分に同じ符号が付されており、下記説明では重複説明が省略される。図面は模式的に示されたものである。図１から図６（ａ）、図７、図９から図１７（ｃ）には、右手系のＸＹＺ座標系が付されている。このＸＹＺ座標系では、第１出力取出電極７ａの長手方向が＋Ｙ方向とされ、第１出力取出電極７ａの短手方向が＋Ｘ方向とされ、＋Ｘ方向と＋Ｙ方向との両方に直交する、太陽電池素子１０における前面１０ｆｓの法線方向が＋Ｚ方向とされている。 Hereinafter, various embodiments will be described based on the drawings. In the drawings, portions having similar configurations and functions are denoted by the same reference numerals, and redundant description will be omitted in the following description. The drawings are schematically shown. The XYZ coordinate system of the right-handed system is attached to FIGS. 1 to 6 (a), 7 and 9 to 17 (c). In this XYZ coordinate system, the longitudinal direction of the first output extraction electrode 7a is the + Y direction, the short direction of the first output extraction electrode 7a is the + X direction, and the sun is orthogonal to both the + X direction and the + Y direction. The normal direction of the front surface 10 fs of the battery element 10 is the + Z direction.
　＜１．第１実施形態＞
　　＜１－１．太陽電池素子の概略的な構成＞
　第１実施形態に係る太陽電池素子１０の概略的な構成を、図１から図３に基づいて説明する。図３では、半導体基板１の第２面１ｆｓにおいて意図的に形成されたテクスチャが便宜的に大きなサイズで描かれている。一方、図３では、半導体基板１の第１面１ｂｓにおいて形成されてしまったテクスチャは、実際のサイズに合うように省略されている。第１実施形態に係る太陽電池素子１０は、ＰＥＲＣ型の太陽電池素子である。 <1. First embodiment>
<1-1. Schematic Configuration of Solar Cell Element>
The schematic configuration of the solar cell element 10 according to the first embodiment will be described based on FIGS. 1 to 3. In FIG. 3, the texture intentionally formed on the second surface 1 fs of the semiconductor substrate 1 is drawn in a large size for convenience. On the other hand, in FIG. 3, the texture formed on the first surface 1 bs of the semiconductor substrate 1 is omitted so as to fit the actual size. The solar cell element 10 according to the first embodiment is a PERC type solar cell element.
　図１から図３で示されるように、太陽電池素子１０は、主に光を受光する面（前面ともいう）１０ｆｓと、この前面の逆側に位置している面（裏面ともいう）１０ｂｓと、を有する。図１から図３の例では、前面１０ｆｓが、＋Ｚ方向を向いており、裏面１０ｂｓが、－Ｚ方向を向いている状態にある。 As shown in FIGS. 1 to 3, the solar cell element 10 mainly includes a light receiving surface (also referred to as a front surface) 10 fs, and a surface (also referred to as a back surface) 10 bs located on the opposite side of the front surface. And. In the example of FIGS. 1 to 3, the front surface 10 fs faces the + Z direction, and the back surface 10 bs faces the −Z direction.
　太陽電池素子１０は、例えば、半導体基板１と、パッシベーション層４と、反射防止層５と、保護層６と、表面電極７と、裏面電極８と、を有する。 The solar cell element 10 includes, for example, a semiconductor substrate 1, a passivation layer 4, an antireflection layer 5, a protective layer 6, a front electrode 7, and a back electrode 8.
　半導体基板１は、第１面１ｂｓと、第２面１ｆｓと、第３面１ｓｓと、を有する。第１面１ｂｓは、裏面１０ｂｓ側に位置している。第２面１ｆｓは、前面１０ｆｓ側に位置している。換言すれば、第１面１ｂｓと第２面１ｆｓとは相互に反対方向を向いている状態で位置している。第３面１ｓｓは、第１面１ｂｓと第２面１ｆｓとを接続している状態で位置している。換言すれば、第３面１ｓｓは、半導体基板１の外周縁を構成している状態にある端面である。図１から図３の例では、第１面１ｂｓは、－Ｚ方向を向いている状態にある。第２面１ｆｓは、＋Ｚ方向を向いている状態にある。半導体基板１は、＋Ｚ方向に沿った厚さを有する平板状の形態を有する。このため、第１面１ｂｓおよび第２面１ｆｓは、それぞれＸＹ平面に沿った半導体基板１の板面を構成している状態にある。 The semiconductor substrate 1 has a first surface 1 bs, a second surface 1 fs, and a third surface 1 ss. The first surface 1 bs is located on the back surface 10 bs side. The second surface 1 fs is located on the front surface 10 fs side. In other words, the first surface 1 bs and the second surface 1 fs are located in directions opposite to each other. The third surface 1ss is located in a state in which the first surface 1bs and the second surface 1fs are connected. In other words, the third surface 1 ss is an end surface in a state of forming the outer peripheral edge of the semiconductor substrate 1. In the example of FIGS. 1 to 3, the first surface 1 bs is in the state of facing the −Z direction. The second surface 1 fs is in the state of facing the + Z direction. The semiconductor substrate 1 has a flat form having a thickness along the + Z direction. For this reason, the first surface 1 bs and the second surface 1 fs are in the state of constituting the plate surface of the semiconductor substrate 1 along the XY plane.
　また、半導体基板１は、第１半導体層２と、第２半導体層３と、を有する。第１半導体層２は、第１導電型を有する半導体によって構成されている状態にある。第２半導体層３は、第１導電型とは逆の第２導電型を有する半導体によって構成されている状態にある。第１半導体層２は、半導体基板１のうちの第１面１ｂｓ側の部分に位置している。第２半導体層３は、半導体基板１のうちの第２面１ｆｓ側の表層部に位置している。図３の例では、第１半導体層２上に第２半導体層３が位置している。 The semiconductor substrate 1 also has a first semiconductor layer 2 and a second semiconductor layer 3. The first semiconductor layer 2 is in a state of being constituted by a semiconductor having a first conductivity type. The second semiconductor layer 3 is in a state of being constituted by a semiconductor having a second conductivity type opposite to the first conductivity type. The first semiconductor layer 2 is located in a portion of the semiconductor substrate 1 on the first surface 1 bs side. The second semiconductor layer 3 is located in the surface layer portion of the semiconductor substrate 1 on the second surface 1 fs side. In the example of FIG. 3, the second semiconductor layer 3 is located on the first semiconductor layer 2.
　ここで、例えば、半導体基板１がシリコン基板である場合を想定する。この場合、シリコン基板として、多結晶または単結晶のシリコン基板が採用される。シリコン基板は、例えば、２５０μｍ以下あるいは１５０μｍ以下の厚さを有する薄い基板である。また、シリコン基板は、例えば、平面視して矩形状の外縁形状を有する。このような形状を有する半導体基板１が採用されれば、複数の太陽電池素子１０を並べて太陽電池モジュールが製造される際に、太陽電池素子１０同士の間の隙間が小さくなり得る。 Here, for example, it is assumed that the semiconductor substrate 1 is a silicon substrate. In this case, a polycrystalline or single crystal silicon substrate is employed as the silicon substrate. The silicon substrate is, for example, a thin substrate having a thickness of 250 μm or less or 150 μm or less. The silicon substrate has, for example, a rectangular outer edge shape in plan view. If the semiconductor substrate 1 having such a shape is adopted, the gaps between the solar cell elements 10 may be small when the solar cell module 10 is manufactured by arranging the plurality of solar cell elements 10.
　また、例えば、第１導電型がｐ型であり且つ第２導電型がｎ型である場合、ｐ型のシリコン基板は、例えば、多結晶あるいは単結晶のシリコンの結晶に、ドーパント元素として、ボロンあるいはガリウムなどの不純物を含有させて製作され得る。この場合、ｐ型のシリコン基板の第２面１ｆｓ側の表層部にドーパントとしての燐などの不純物を拡散させることで、ｎ型の第２半導体層３が生成され得る。このとき、ｐ型の第１半導体層２とｎ型の第２半導体層３とが積層された半導体基板１が形成され得る。これにより、半導体基板１は、第１半導体層２と第２半導体層３との界面に位置しているｐｎ接合部を有する。 Also, for example, when the first conductivity type is p-type and the second conductivity type is n-type, the p-type silicon substrate is, for example, boron as a dopant element in polycrystalline or single crystal silicon crystal. Alternatively, it may be manufactured to contain an impurity such as gallium. In this case, the n-type second semiconductor layer 3 can be generated by diffusing an impurity such as phosphorus as a dopant in the surface layer portion on the second surface 1 fs side of the p-type silicon substrate. At this time, the semiconductor substrate 1 in which the p-type first semiconductor layer 2 and the n-type second semiconductor layer 3 are stacked can be formed. Thus, the semiconductor substrate 1 has a pn junction located at the interface between the first semiconductor layer 2 and the second semiconductor layer 3.
　図３に示されるように、半導体基板１の第２面１ｆｓは、例えば、照射された光の反射を低減するための微細な凹凸構造（テクスチャ）を有していてもよい。このとき、テクスチャの凸部の高さは、例えば、０．１μｍから１０μｍ程度とされる。隣り合う凸部の頂点の間の距離は、例えば、０．１μｍから２０μｍ程度とされる。テクスチャでは、例えば、凹部が略球面状であってもよいし、凸部がピラミッド形状であってもよい。上述した「凸部の高さ」とは、例えば、図３において、凹部の底面を通る直線を基準線とし、この基準線に対して垂直な方向（ここでは＋Ｚ方向）において、この基準線から凸部の頂点までの距離のことである。 As shown in FIG. 3, the second surface 1 fs of the semiconductor substrate 1 may have, for example, a fine uneven structure (texture) for reducing the reflection of the irradiated light. At this time, the height of the convex portion of the texture is, for example, about 0.1 μm to 10 μm. The distance between the apexes of adjacent protrusions is, for example, about 0.1 μm to about 20 μm. In the texture, for example, the recess may be substantially spherical, or the protrusion may be pyramidal. The “height of the convex portion” described above is, for example, a straight line passing through the bottom of the recess in FIG. 3 as a reference line, and from the reference line in a direction (here, + Z direction) perpendicular to the reference line. It is the distance to the top of the convex part.
　さらに、半導体基板１は、第３半導体層２ｂｓを有する。第３半導体層２ｂｓは、半導体基板１のうちの第１面１ｂｓ側の表層部に位置している。第３半導体層２ｂｓの導電型は、第１半導体層２の導電型（本実施形態ではｐ型）と同一とされる。そして、第３半導体層２ｂｓが含有するドーパントの濃度は、第１半導体層２が含有するドーパントの濃度よりも高い。第３半導体層２ｂｓは、半導体基板１の第１面１ｂｓ側において内部電界を形成する。これにより、半導体基板１の第１面１ｂｓの近傍では、半導体基板１において光の照射に応じた光電変換によって生じる少数キャリアの再結合が低減され得る。その結果、太陽電池素子１０における光電変換効率の低下が生じにくい。第３半導体層２ｂｓは、例えば、半導体基板１のうちの第１面１ｂｓ側の表層部に、アルミニウムなどのドーパント元素が拡散されることで形成され得る。このとき、第１半導体層２が含有するドーパント元素の濃度を、５×１０１５ａｔｏｍｓ／ｃｍ３から１×１０１７ａｔｏｍｓ／ｃｍ３程度とし、第３半導体層２ｂｓが含有するドーパント元素の濃度を、１×１０１８ａｔｏｍｓ／ｃｍ３から５×１０２１ａｔｏｍｓ／ｃｍ３程度とすることができる。第３半導体層２ｂｓは、後述する第２集電電極８ｂと半導体基板１との接触部分に存在する。 Furthermore, the semiconductor substrate 1 has a third semiconductor layer 2bs. The third semiconductor layer 2 bs is located in the surface layer portion of the semiconductor substrate 1 on the first surface 1 bs side. The conductivity type of the third semiconductor layer 2bs is the same as the conductivity type of the first semiconductor layer 2 (p type in this embodiment). The concentration of the dopant contained in the third semiconductor layer 2 bs is higher than the concentration of the dopant contained in the first semiconductor layer 2. The third semiconductor layer 2 bs forms an internal electric field on the side of the first surface 1 bs of the semiconductor substrate 1. Thereby, in the vicinity of the first surface 1 bs of the semiconductor substrate 1, recombination of minority carriers generated in the semiconductor substrate 1 by photoelectric conversion in response to light irradiation can be reduced. As a result, a decrease in photoelectric conversion efficiency in the solar cell element 10 does not easily occur. The third semiconductor layer 2bs may be formed, for example, by diffusing a dopant element such as aluminum in the surface layer portion of the semiconductor substrate 1 on the first surface 1bs side. At this time, the concentration of the dopant element contained in the first semiconductor layer 2 is about 5 × 10 15 atoms / cm 3 to 1 × 10 17 atoms / cm 3, and the concentration of the dopant element contained in the third semiconductor layer 2 bs is And 1 × 10 18 atoms / cm 3 to 5 × 10 21 atoms / cm 3 or so. The third semiconductor layer 2 bs is present at a contact portion between the second current collection electrode 8 b described later and the semiconductor substrate 1.
　パッシベーション層４は、半導体基板１の少なくとも第１面１ｂｓ上に位置している。パッシベーション層４は、半導体基板１において、光の照射に応じた光電変換によって生成される少数キャリアの再結合を低減することができる。パッシベーション層４の素材としては、例えば、酸化アルミニウム、酸化ジルコニウム、酸化ハフニウム、酸化シリコン、窒化シリコンおよび酸窒化シリコンなどから選択される１種類以上の素材が採用される。パッシベーション層４は、例えば、１層あるいは互いに異なる素材を含む２層以上によって構成されている状態にある。この場合、パッシベーション層４は、例えば、ＣＶＤ法または原子層堆積（Atomic Layer Deposition：ＡＬＤ）法で形成され得る。ここで、パッシベーション層４が酸化アルミニウムを含む場合を想定する。この場合、この酸化アルミニウムは負の固定電荷を有する。このため、電界効果によって、半導体基板１の第１面１ｂｓ側で生じる少数キャリア（この場合は電子）が、ｐ型の第１半導体層２とパッシベーション層４との界面（第１面１ｂｓ）から遠ざけられる。これにより、半導体基板１のうちの第１面１ｂｓの近傍における少数キャリアの再結合が低減され得る。このため、太陽電池素子１０の光電変換効率が向上し得る。パッシベーション層４の厚さは、例えば、３ｎｍから１００ｎｍ程度とされる。パッシベーション層４は、例えば、半導体基板１の第２面１ｆｓ上にも位置していてもよい。また、パッシベーション層４は、例えば、半導体基板１の第２面１ｆｓと第１面１ｂｓとを接続する端面としての第３面１ｓｓ上にも位置していてもよい。 The passivation layer 4 is located on at least the first surface 1 bs of the semiconductor substrate 1. The passivation layer 4 can reduce recombination of minority carriers generated by photoelectric conversion in response to light irradiation in the semiconductor substrate 1. As a material of the passivation layer 4, for example, one or more kinds of materials selected from aluminum oxide, zirconium oxide, hafnium oxide, silicon oxide, silicon nitride, silicon oxynitride and the like are employed. The passivation layer 4 is, for example, in a state of being constituted by one layer or two or more layers containing different materials. In this case, the passivation layer 4 can be formed by, for example, a CVD method or an atomic layer deposition (ALD) method. Here, it is assumed that the passivation layer 4 contains aluminum oxide. In this case, the aluminum oxide has a negative fixed charge. Therefore, minority carriers (in this case, electrons) generated on the first surface 1 bs side of the semiconductor substrate 1 by the field effect are generated from the interface (first surface 1 bs) between the p-type first semiconductor layer 2 and the passivation layer 4. It is kept away. Thereby, the recombination of minority carriers in the vicinity of the first surface 1 bs of the semiconductor substrate 1 can be reduced. For this reason, the photoelectric conversion efficiency of the solar cell element 10 can be improved. The thickness of the passivation layer 4 is, for example, about 3 nm to 100 nm. The passivation layer 4 may be located, for example, on the second surface 1 fs of the semiconductor substrate 1. The passivation layer 4 may also be located, for example, on the third surface 1 ss as an end face connecting the second surface 1 fs of the semiconductor substrate 1 and the first surface 1 bs.
　反射防止層５は、太陽電池素子１０の前面１０ｆｓに照射される光の反射率を低減することができる。反射防止層５の素材としては、例えば、酸化シリコン、酸化アルミニウムまたは窒化シリコンなどが採用される。反射防止層５の屈折率および厚さは、太陽光のうち、半導体基板１に吸収されて発電に寄与し得る波長範囲の光に対して、反射率が低い条件（低反射条件ともいう）を実現することが可能な値に適宜設定され得る。例えば、反射防止層５の屈折率を１．８から２．５程度とし、この反射防止層５の厚さを、２０ｎｍから１２０ｎｍ程度とすることが考えられる。 The antireflection layer 5 can reduce the reflectance of light irradiated to the front surface 10 fs of the solar cell element 10. As a material of the antireflective layer 5, for example, silicon oxide, aluminum oxide or silicon nitride is adopted. The refractive index and thickness of the antireflective layer 5 are conditions (also referred to as low reflection conditions) in which the reflectance is low with respect to light in a wavelength range that can be absorbed by the semiconductor substrate 1 and contribute to power generation. It can be appropriately set to a value that can be realized. For example, it is conceivable to set the refractive index of the antireflective layer 5 to about 1.8 to 2.5 and to set the thickness of the antireflective layer 5 to about 20 nm to 120 nm.
　保護層６は、半導体基板１の第１面１ｂｓ上に位置しているパッシベーション層４上に位置している。保護層６は、パッシベーション層４を保護することができる。保護層６の素材としては、例えば、酸化シリコン、窒化シリコンおよび酸窒化シリコンなどから選択される１種類以上の素材が採用される。保護層６は、パッシベーション層４上において、所望のパターンを有する状態で位置している。保護層６は、厚さ方向（ここでは＋Ｚ方向）にこの保護層６を貫通する間隙を有する。この間隙は、例えば、第１面１ｂｓに沿った周囲が閉じられた貫通孔を形成している状態にある孔部であってもよいし、第１面１ｂｓに沿った周囲の少なくとも一部が開口している状態にあるスリット状の孔部であってもよい。例えば、図２で示されるように、裏面１０ｂｓ側から保護層６を平面透視した際に、保護層６が複数の孔部ＣＨ１を有する場合が想定される。ここで、裏面１０ｂｓ側から保護層６を平面透視した際に、各孔部ＣＨ１は、ドット（点）状であってもよいし、帯（線）状であってもよい。孔部ＣＨ１の直径または幅は、例えば、１０μｍから５００μｍ程度とされる。孔部ＣＨ１のピッチは、例えば、０．３ｍｍから３ｍｍ程度とされる。孔部ＣＨ１のピッチは、例えば、裏面１０ｂｓ側から保護層６を平面透視した際の互い隣り合う孔部ＣＨ１の中心同士の距離とされる。図２の例では、１１０個の孔部ＣＨ１が存在している。ただし、各孔部ＣＨ１の大きさ、形状、数の組合せは、適宜調整され得る。このため、孔部ＣＨ１の数は、例えば、１つ以上であればよい。 The protective layer 6 is located on the passivation layer 4 located on the first surface 1 bs of the semiconductor substrate 1. The protective layer 6 can protect the passivation layer 4. As a material of the protective layer 6, for example, one or more kinds of materials selected from silicon oxide, silicon nitride, silicon oxynitride and the like are employed. The protective layer 6 is located on the passivation layer 4 in a state having a desired pattern. The protective layer 6 has a gap penetrating the protective layer 6 in the thickness direction (here, the + Z direction). This gap may be, for example, a hole in a state in which the periphery along the first surface 1 bs forms a closed through hole, or at least a part of the periphery along the first surface 1 bs It may be a slit-like hole in an open state. For example, as shown in FIG. 2, when the protective layer 6 is seen through the plan view from the back surface 10 bs side, it is assumed that the protective layer 6 has a plurality of holes CH1. Here, when the protective layer 6 is seen through the plan view from the back surface 10bs side, each hole CH1 may be in a dot (dot) shape or in a band (line) shape. The diameter or width of the hole CH1 is, for example, about 10 μm to 500 μm. The pitch of the holes CH1 is, for example, about 0.3 mm to 3 mm. The pitch of the holes CH1 is, for example, the distance between the centers of the holes CH1 adjacent to each other when the protective layer 6 is seen through the plane from the back surface 10bs side. In the example of FIG. 2, 110 holes CH1 are present. However, the combination of the size, shape, and number of the holes CH1 may be appropriately adjusted. For this reason, the number of the holes CH1 may be, for example, one or more.
　ところで、保護層６は、例えば、半導体基板１の第１面１ｂｓ上に形成されたパッシベーション層４上に、絶縁性ペーストがスプレー法、コーター法またはスクリーン印刷法などの塗布法によって所望のパターンを有するように塗布された後に乾燥されることで形成される。保護層６は、例えば、半導体基板１の第３面１ｓｓ上において、直接、パッシベーション層４上あるいは反射防止層５上にも形成されてもよい。このとき、保護層６の存在によって、太陽電池素子１０におけるリーク電流の低減が図られ得る。 By the way, for example, on the passivation layer 4 formed on the first surface 1 bs of the semiconductor substrate 1, the protective layer 6 has a desired pattern of insulating paste by a coating method such as a spray method, a coater method or a screen printing method. It is formed by being dried after being applied to have. The protective layer 6 may be formed directly on the passivation layer 4 or the antireflective layer 5 directly, for example, on the third surface 1 ss of the semiconductor substrate 1. At this time, the leakage current in the solar cell element 10 can be reduced by the presence of the protective layer 6.
　ここで、例えば、保護層６の上に後述する第２集電電極８ｂを形成する際には、アルミニウムを主成分とする金属粉末とガラス成分と有機ビヒクルとを含む金属ペースト（第１金属ペーストともいう）が保護層６上に所望の形状を有するように塗布されて焼成される。主成分とは、含有成分のうち含有される比率（含有率ともいう）が最も大きい（高い）成分のことを意味する。このとき、パッシベーション層４上に直接塗布された第１金属ペーストは、保護層６の孔部ＣＨ１においてパッシベーション層４のファイヤースルー（焼成貫通）を生じ、半導体基板１の第１面１ｂｓに第２集電電極８ｂが直接接続される。これにより、パッシベーション層４および保護層６は、パッシベーション層４および保護層６を貫通している状態でそれぞれ位置している複数の孔部ＣＨ１を有する状態となる。また、このとき、例えば、複数の孔部ＣＨ１内に位置している第１金属ペーストが含有しているアルミニウムが半導体基板１の第１面１ｂｓの表層部内に拡散することで、第３半導体層２ｂｓが形成される。また、例えば、保護層６の厚さが、パッシベーション層４の厚さよりも十分大きければ、パッシベーション層４のうちの保護層６で覆われた状態にある部分では、第１金属ペーストはパッシベーション層４のファイヤースルーを生じない。これにより、太陽電池素子１０において、半導体基板１の第１面１ｂｓ上に、保護層６の所望のパターンに対応するパターンでパッシベーション層４を存在させることが可能となる。 Here, for example, when forming a second current collection electrode 8b described later on the protective layer 6, a metal paste (a first metal paste containing a metal powder mainly composed of aluminum, a glass component, and an organic vehicle) Is applied and baked on the protective layer 6 so as to have a desired shape. The main component means a component having the largest ratio (also referred to as a content ratio) of the contained components. At this time, the first metal paste applied directly on the passivation layer 4 causes a fire through of the passivation layer 4 in the hole portion CH1 of the protective layer 6, and the second surface 1bs of the semiconductor substrate 1 The collecting electrode 8b is directly connected. As a result, the passivation layer 4 and the protective layer 6 are in a state of having a plurality of holes CH1 positioned respectively in a state of penetrating the passivation layer 4 and the protective layer 6. At this time, for example, the third semiconductor layer is formed by diffusing aluminum contained in the first metal paste located in the plurality of holes CH1 into the surface layer portion of the first surface 1bs of the semiconductor substrate 1 Two bs are formed. Also, for example, if the thickness of the protective layer 6 is sufficiently larger than the thickness of the passivation layer 4, the first metal paste is used as the passivation layer 4 in the portion covered with the protective layer 6 in the passivation layer 4. Do not fire through. Thereby, in the solar cell element 10, the passivation layer 4 can be present on the first surface 1 bs of the semiconductor substrate 1 in a pattern corresponding to the desired pattern of the protective layer 6.
　保護層６の厚さは、例えば、０．５μｍから１０μｍ程度とされる。保護層６の厚さは、保護層６を形成するための後述する絶縁性ペーストの組成、半導体基板１の第１面１ｂｓの形状、および第２集電電極８ｂの形成時の焼成条件などによって、適宜設定される。 The thickness of the protective layer 6 is, for example, about 0.5 μm to 10 μm. The thickness of the protective layer 6 depends on the composition of the insulating paste to be described later for forming the protective layer 6, the shape of the first surface 1bs of the semiconductor substrate 1, and the firing conditions at the time of forming the second collector electrode 8b. , Is set appropriately.
　表面電極７は、半導体基板１の第２面１ｆｓ側に位置している。表面電極７は、図１および図３で示されるように、第１出力取出電極７ａと複数の線状の第１集電電極７ｂとを有する。 The front surface electrode 7 is located on the second surface 1 fs side of the semiconductor substrate 1. The surface electrode 7 has the 1st output extraction electrode 7a and several linear 1st current collection electrodes 7b, as FIG. 1 and FIG. 3 show.
　第１出力取出電極７ａは、半導体基板１における光の照射に応じた光電変換によって得られたキャリアを太陽電池素子１０の外部に取り出すことができる。第１出力取出電極７ａとしては、前面１０ｆｓを平面視して、例えば、細長い長方形状の形状を有するバスバー電極が採用される。第１出力取出電極７ａの短手方向の長さ（幅ともいう）は、例えば０．３ｍｍから２．５ｍｍ程度とされる。第１出力取出電極７ａの少なくとも一部は、第１集電電極７ｂに対して交差している状態で電気的に接続している状態にある。 The first output lead electrode 7 a can take out the carrier obtained by photoelectric conversion according to the irradiation of light in the semiconductor substrate 1 to the outside of the solar cell element 10. As the first output lead-out electrode 7a, a bus bar electrode having, for example, an elongated rectangular shape is employed in plan view of the front surface 10 fs. The length (also referred to as the width) of the first output lead electrode 7a in the short direction is, for example, about 0.3 mm to 2.5 mm. At least a part of the first output lead-out electrode 7a is in a state of being electrically connected in a state of intersecting with the first current collection electrode 7b.
　第１集電電極７ｂは、半導体基板１において光の照射に応じた光電変換によって得られたキャリアを集めることができる。各第１集電電極７ｂは、例えば、２０μｍから２００μｍ程度の幅を有する線状の電極である。換言すれば、各第１集電電極７ｂの幅は、第１出力取出電極７ａの幅よりも小さい。複数の第１集電電極７ｂは、例えば、互いに１ｍｍから３ｍｍ程度の間隔を空けて並んでいる状態で位置している。表面電極７の厚さは、例えば、３μｍから３０μｍ程度とされる。このような表面電極７は、例えば、銀を主成分とする金属粒子などを含有する金属ペースト（第２金属ペーストともいう）をスクリーン印刷などによって所望の形状に塗布した後に、この第２金属ペーストを焼成することで形成され得る。また、例えば、第１集電電極７ｂと同様の形状の補助電極７ｃが、半導体基板１の＋Ｘ方向の側および－Ｘ方向の側にそれぞれ存在している縁部に沿って位置していることで、第１集電電極７ｂ同士を電気的に接続していてもよい。 The first current collecting electrode 7 b can collect carriers obtained by photoelectric conversion according to the light irradiation in the semiconductor substrate 1. Each first current collecting electrode 7 b is, for example, a linear electrode having a width of about 20 μm to 200 μm. In other words, the width of each first current collecting electrode 7b is smaller than the width of the first output lead electrode 7a. The plurality of first current collection electrodes 7b are located, for example, in a state of being spaced apart from each other by about 1 mm to 3 mm. The thickness of the surface electrode 7 is, for example, about 3 μm to 30 μm. Such a surface electrode 7 is formed by, for example, applying a metal paste (also referred to as a second metal paste) containing metal particles containing silver as a main component to a desired shape by screen printing or the like. Can be formed by firing. Further, for example, the auxiliary electrode 7c having the same shape as that of the first current collection electrode 7b is located along the edge portions respectively present on the + X direction side and the −X direction side of the semiconductor substrate 1 The first collecting electrodes 7b may be electrically connected to each other.
　裏面電極８は、半導体基板１の第１面１ｂｓ側に位置している。裏面電極８は、図２および図３で示されるように、第２出力取出電極８ａと第２集電電極８ｂとを有する。 The back electrode 8 is located on the first surface 1 bs side of the semiconductor substrate 1. The back surface electrode 8 has the 2nd output extraction electrode 8a and the 2nd current collection electrode 8b, as FIG. 2 and FIG. 3 show.
　第２出力取出電極８ａは、半導体基板１の第１面１ｂｓ側に位置している。この第２出力取出電極８ａは、太陽電池素子１０において光電変換によって得られたキャリアを太陽電池素子１０の外部に取り出すための電極である。第２出力取出電極８ａの厚さは、例えば、３μｍから２０μｍ程度とされる。第２出力取出電極８ａの幅は、例えば、１．３ｍｍから７ｍｍ程度とされる。第２出力取出電極８ａが、主成分として銀を含む場合、第２出力取出電極８ａは、例えば、銀を主成分とする金属粉末とガラス成分と有機ビヒクルとを含む金属ペースト（第３金属ペーストともいう）がスクリーン印刷などによって所望の形状に塗布された後に、この第３金属ペーストを焼成することで形成され得る。 The second output lead electrode 8 a is located on the first surface 1 bs side of the semiconductor substrate 1. The second output extraction electrode 8 a is an electrode for extracting carriers obtained by photoelectric conversion in the solar cell element 10 to the outside of the solar cell element 10. The thickness of the second output lead-out electrode 8a is, for example, about 3 μm to 20 μm. The width of the second output lead-out electrode 8a is, for example, about 1.3 mm to 7 mm. When the second output lead-out electrode 8a contains silver as a main component, the second output lead-out electrode 8a is, for example, a metal paste (third metal paste) containing a metal powder mainly containing silver, a glass component and an organic vehicle The third metal paste may be formed by firing after the coating is applied to a desired shape by screen printing or the like.
　第２集電電極８ｂは、半導体基板１の第１面１ｂｓ側において、保護層６上に位置している。この第２集電電極８ｂは、半導体基板１に電気的に接続している状態にある。具体的には、第２集電電極８ｂは、電極層８ｂｌと、接続部８ｂｃと、を有する。電極層８ｂｌは、保護層６の上に位置している層状の部分である。接続部８ｂｃは、パッシベーション層４および保護層６を貫通している状態でそれぞれ位置している複数の孔部ＣＨ１において、それぞれ電極層８ｂｌと半導体基板１の第１面１ｂｓとを電気的に接続している状態で位置している部分である。 The second current collection electrode 8 b is located on the protective layer 6 on the first surface 1 bs side of the semiconductor substrate 1. The second current collection electrode 8 b is in a state of being electrically connected to the semiconductor substrate 1. Specifically, the second current collection electrode 8b includes an electrode layer 8bl and a connection portion 8bc. The electrode layer 8 bl is a layered portion located on the protective layer 6. Connecting portion 8 bc electrically connects electrode layer 8 bl to first surface 1 bs of semiconductor substrate 1 at a plurality of holes CH 1 positioned respectively in a state of penetrating through passivation layer 4 and protective layer 6. It is the part located in the state where it is doing.
　第２集電電極８ｂは、半導体基板１の第１面１ｂｓ側において、半導体基板１において光の照射に応じた光電変換によって得られたキャリアを集めることができる。第２集電電極８ｂは、第２出力取出電極８ａの少なくとも一部に対して電気的に接続している状態で位置している。第２集電電極８ｂにおける電極層８ｂｌの厚さは、例えば、１５μｍから５０μｍ程度とされる。第２集電電極８ｂが、主成分としてアルミニウムを含む場合、第２集電電極８ｂは、例えば、第１金属ペーストが所望の形状に塗布された後に、この第１金属ペーストを焼成することで形成され得る。 The second current collection electrode 8 b can collect carriers obtained by photoelectric conversion in the semiconductor substrate 1 according to the light irradiation on the first surface 1 bs side of the semiconductor substrate 1. The second current collection electrode 8 b is located in a state electrically connected to at least a part of the second output extraction electrode 8 a. The thickness of the electrode layer 8bl in the second current collection electrode 8b is, for example, about 15 μm to 50 μm. When the second current collection electrode 8b contains aluminum as a main component, for example, after the first metal paste is applied in a desired shape, the second current collection electrode 8b is fired by baking the first metal paste. It can be formed.
　さらに、第２集電電極８ｂは、例えば、太陽電池素子１０の第１面１ｂｓ上において第１集電電極７ｂと同様な形状を有しており且つ第２出力取出電極８ａに接続している状態で位置していてもよい。このような構造が採用されれば、太陽電池素子１０の裏面１０ｂｓに入射する光も太陽電池素子１０における光電変換に利用され得る。これにより、例えば、太陽電池素子１０における出力が向上し得る。裏面１０ｂｓに入射する光は、例えば、地面などにおける太陽光の反射によって生じ得る。 Furthermore, the second current collection electrode 8 b has, for example, the same shape as the first current collection electrode 7 b on the first surface 1 bs of the solar cell element 10 and is connected to the second output extraction electrode 8 a It may be located in the state. If such a structure is adopted, light incident on the back surface 10 bs of the solar cell element 10 can also be used for photoelectric conversion in the solar cell element 10. Thereby, for example, the output of the solar cell element 10 can be improved. The light incident on the back surface 10bs can be generated, for example, by the reflection of sunlight on the ground or the like.
　　＜１－２．太陽電池素子の裏面側における構造＞
　第１実施形態に係る太陽電池素子１０の裏面１０ｂｓ側における構造について、図４（ａ）および図４（ｂ）に基づいて説明する。ここで、例えば、塩酸などを用いたエッチングで太陽電池素子１０の裏面電極８を除去した後に、光学顕微鏡または走査型電子顕微鏡（ＳＥＭ：Scanning Electron Microscope）によって保護層６の表面形状を観察することができる。また、例えば、太陽電池素子１０を切断し、塩酸などを用いたエッチングで太陽電池素子１０の切断面において切断による歪みおよび傷を有する部分を除去した後に、ＳＥＭなどによって保護層６の断面を観察することができる。 <1-2. Structure on Back Side of Solar Cell>
The structure on the back surface 10bs side of the solar cell element 10 according to the first embodiment will be described based on FIGS. 4 (a) and 4 (b). Here, for example, after removing the back surface electrode 8 of the solar cell element 10 by etching using hydrochloric acid or the like, observing the surface shape of the protective layer 6 with an optical microscope or a scanning electron microscope (SEM: Scanning Electron Microscope) Can. In addition, for example, after cutting the solar cell element 10 and removing a portion having distortion and flaws due to cutting on the cut surface of the solar cell element 10 by etching using hydrochloric acid or the like, the cross section of the protective layer 6 is observed by SEM or the like. can do.
　図４（ａ）で示されるように、例えば、保護層６は、第２集電電極８ｂの電極層８ｂｌ側の面に位置している、複数の凸状部６ｐを有する。換言すれば、例えば、複数の凸状部６ｐは、保護層６のうちのパッシベーション層４が位置している側の面とは反対側の面に位置している。ここで、保護層６のうちのパッシベーション層４が位置している側の面とは反対側の面は、保護層６のうちの電極層８ｂ１が位置している側の面である。第１実施形態では、保護層６は、第２集電電極８ｂの電極層８ｂｌ側に位置している、複数の凸状部６ｐと、非凸状部６ａｐと、を有する。非凸状部６ａｐは、保護層６のうちの電極層８ｂｌ側の面に位置している、複数の凸状部６ｐ以外の部分である。換言すれば、保護層６における電極層８ｂｌ側の表面は、凸状部６ｐと、非凸状部６ａｐと、を含む凹凸構造を有する。図４（ａ）の例では、各凸状部６ｐは、非凸状部６ａｐを基準として、－Ｚ方向に突出している状態で位置している。 As shown in FIG. 4A, for example, the protective layer 6 has a plurality of convex portions 6p located on the surface of the second current collection electrode 8b on the electrode layer 8bl side. In other words, for example, the plurality of convex portions 6 p are located on the surface of the protective layer 6 opposite to the surface on which the passivation layer 4 is located. Here, the surface of the protective layer 6 opposite to the surface on which the passivation layer 4 is located is the surface of the protective layer 6 on which the electrode layer 8 b 1 is located. In the first embodiment, the protective layer 6 has a plurality of convex portions 6 p and a non-convex portion 6 ap, which are located on the electrode layer 8 bl side of the second collecting electrode 8 b. The non-convex portion 6 ap is a portion other than the plurality of convex portions 6 p, which is located on the surface of the protective layer 6 on the electrode layer 8 bl side. In other words, the surface of the protective layer 6 on the electrode layer 8 bl side has a concavo-convex structure including the convex portion 6 p and the non-convex portion 6 ap. In the example of FIG. 4A, each convex portion 6p is positioned in a state of projecting in the -Z direction with reference to the non-convex portion 6ap.
　また、例えば、図５（ａ）で示されるような態様で、保護層６は、第２集電電極８ｂの電極層８ｂｌ側の面に位置している、凸状部６ｐと、この凸状部６ｐ以外の非凸状部６ａｐと、を有していてもよい。換言すれば、例えば、凸状部６ｐおよび非凸状部６ａｐは、保護層６のうちのパッシベーション層４が位置している側の面とは反対側の面に位置している。図５（ａ）の例では、各凸状部６ｐは、非凸状部６ａｐを基準として、－Ｚ方向に突出している状態で位置している。 Also, for example, in a mode as shown in FIG. 5A, the protective layer 6 is located on the surface of the second current collection electrode 8b on the electrode layer 8bl side, and the convex portion 6p, and the convex shape You may have non-convex-shaped parts 6ap other than the part 6p. In other words, for example, the convex portion 6 p and the non-convex portion 6 ap are located on the surface of the protective layer 6 opposite to the surface on which the passivation layer 4 is located. In the example of FIG. 5A, each convex portion 6p is positioned in a state of projecting in the -Z direction with reference to the non-convex portion 6ap.
　保護層６の表面における凹凸構造は、例えば、半導体基板１の第１面１ｂｓの凹凸構造１ｒｇに由来し得る。図４（ａ）および図５（ａ）の例では、半導体基板１の第１面１ｂｓに、＋Ｚ方向に凹んでいる状態で位置している部分（凹部ともいう）１ｒと、－Ｚ方向に突出している状態で位置している部分（凸部ともいう）１ｐと、が存在している。凹凸構造１ｒｇは、これらの凹部１ｒと凸部１ｐとを有する状態で構成されている状態にある。このため、例えば、この凹凸構造１ｒｇ上に、厚さが小さなパッシベーション層４および保護層６がこの記載の順に形成されることで、保護層６のうちの電極層８ｂｌが形成される対象となる表面において、半導体基板１の凹凸構造１ｒｇに対応する凹凸構造が形成され得る。 The concavo-convex structure on the surface of the protective layer 6 may be derived from, for example, the concavo-convex structure 1 rg of the first surface 1 bs of the semiconductor substrate 1. In the example of FIG. 4A and FIG. 5A, in the first surface 1bs of the semiconductor substrate 1, a portion (also referred to as a recess) 1r positioned in a state of being recessed in the + Z direction, and in the -Z direction. There is a portion (also referred to as a convex portion) 1p positioned in a protruding state. The concavo-convex structure 1 rg is in a state of being configured to have the concave portion 1 r and the convex portion 1 p. Therefore, for example, the passivation layer 4 and the protective layer 6 having a small thickness are formed in this order on the concavo-convex structure 1 rg, so that the electrode layer 8 bl of the protective layer 6 is to be formed. A concavo-convex structure corresponding to the concavo-convex structure 1 rg of the semiconductor substrate 1 may be formed on the surface.
　第１実施形態では、半導体基板１では、上述したように、水酸化ナトリウムなどのアルカリ性の水溶液またはフッ硝酸などの酸性の水溶液を用いた湿式のエッチングによって、第２面１ｆｓ側に上述した微細な凹凸構造（テクスチャ）が形成される。例えば、この凹凸構造が第２面１ｆｓ側に形成される際に、半導体基板１の第１面１ｂｓ側にも凹凸構造１ｒｇが形成され得る。 In the first embodiment, in the semiconductor substrate 1, as described above, the above-described fine on the second surface 1 fs side by wet etching using an alkaline aqueous solution such as sodium hydroxide or an acidic aqueous solution such as fluoronitric acid. An uneven structure (texture) is formed. For example, when the concavo-convex structure is formed on the second surface 1 fs side, the concavo-convex structure 1 rg may be formed on the first surface 1 bs side of the semiconductor substrate 1.
　また、図４（ｂ）および図５（ｂ）で示されるように、保護層６における複数の凸状部６ｐのそれぞれは、第２集電電極８ｂの電極層８ｂｌ側において１つ以上の凹状部分６ｐｒを有する。これにより、凸状部６ｐは、複数の凹状部分６ｐｒを有する。図４（ｂ）には、凸状部６ｐに位置している６つの凹状部分６ｐｒが描かれている。図５（ｂ）には、凸状部６ｐに位置している７つの凹状部分６ｐｒが描かれている。このような凹状部分６ｐｒは、例えば、保護層６を形成する際に用いる絶縁性ペーストに有機フィラーを含有させ、この絶縁性ペーストを乾燥させる際に、有機フィラーを熱分解させることで、この有機フィラーが消滅した領域の痕跡として形成され得る。 Also, as shown in FIGS. 4B and 5B, each of the plurality of convex portions 6p in the protective layer 6 has one or more concave shapes on the electrode layer 8bl side of the second current collection electrode 8b. It has a portion 6pr. Thus, the convex portion 6p has a plurality of concave portions 6pr. In FIG. 4B, six concave portions 6pr located in the convex portion 6p are drawn. In FIG. 5 (b), seven concave portions 6pr located in the convex portion 6p are drawn. In such a concave portion 6pr, for example, an organic filler is contained in the insulating paste used when forming the protective layer 6, and the organic filler is thermally decomposed when the insulating paste is dried. The filler may be formed as a trace of the extinguished area.
　この凹状部分６ｐｒの内部空間ＳＣ１には、第２集電電極８ｂの電極層８ｂｌの一部が位置している。換言すれば、凹状部分６ｐｒの内部空間ＳＣ１には、第２集電電極８ｂの電極層８ｂｌを構成している状態にある成分（電極成分ともいう）が位置している。この電極成分には、少なくともガラス成分が含まれている。このガラス成分は、例えば、第２集電電極８ｂを形成する際に使用した第１金属ペーストに含まれているガラス成分に由来し得る。 In the internal space SC1 of the concave portion 6pr, a part of the electrode layer 8bl of the second collecting electrode 8b is located. In other words, a component (also referred to as an electrode component) in a state of constituting the electrode layer 8bl of the second current collection electrode 8b is located in the internal space SC1 of the concave portion 6pr. The electrode component contains at least a glass component. This glass component may be derived from, for example, the glass component contained in the first metal paste used when forming the second current collection electrode 8b.
　ところで、例えば、第２集電電極８ｂを形成する際に保護層６上に塗布する第１金属ペーストが含有しているガラス成分の含有量を仮に低下させると、保護層６と第２集電電極８ｂとの間における密着性が低下する。例えば、下記のように、４種類の実験用の太陽電池素子１１０（図６（ａ）および図６（ｂ）参照）を試料として作製し、保護層１０６に対する第２集電電極１０８ｂの密着性について実験を行った。その結果、第１金属ペーストに含有されたガラス成分の含有量が低下すると、保護層１０６に対する第２集電電極１０８ｂの密着性が低下することが確認された。 By the way, when, for example, the content of the glass component contained in the first metal paste to be applied on the protective layer 6 is temporarily reduced when forming the second current collection electrode 8b, the protective layer 6 and the second current collection are The adhesion to the electrode 8b is reduced. For example, as described below, four types of experimental solar cell elements 110 (see FIGS. 6A and 6B) are manufactured as samples, and the adhesion of the second current collection electrode 108b to the protective layer 106 is obtained. Experiments were conducted. As a result, it was confirmed that when the content of the glass component contained in the first metal paste decreases, the adhesion of the second current collection electrode 108b to the protective layer 106 decreases.
　４種類の実験用の太陽電池素子１１０を作製する際には、まず、１辺が約１５６ｍｍの矩形状の表裏面と、約２００μｍの厚さと、を有する多結晶のシリコン基板を準備した。この多結晶のシリコン基板の裏面側に、ＡＬＤ法で約５０ｎｍのパッシベーション層を形成し、このパッシベーション層の上に保護層１０６を形成した。このとき、パッシベーション層の上に、シロキサン樹脂と有機溶剤と複数の無機フィラーとを含む絶縁性ペーストを、コーター法で塗布して、約２７０℃で乾燥させることで、約１μｍの厚さを有する保護層１０６を形成した。次に、この保護層１０６の上の略全面に、主成分としてアルミニウム（Ａｌ）を含む金属粉末と、ガラス成分と、有機ビヒクルと、を含有する第１金属ペーストをスクリーン印刷法で塗布した。ここでは、ガラス成分の含有率が、２質量％、３．５質量％、４質量％および５質量％の４水準である４種類の第１金属ペーストを使用した。さらに主成分として銀を含む金属粉末と、有機ビヒクルと、ガラスフリットと、を含有する第３金属ペーストをスクリーン印刷法で第２出力取出電極１０８ａのパターンとなるように塗布した。そして、最高温度が約７４０℃で、加熱時間が約１分（ｍｉｎ）間とされる条件で、第１金属ペーストおよび第３金属ペーストの焼成を行うことで、第２出力取出電極１０８ａと第２集電電極１０８ｂとを含む裏面電極１０８を形成した。これにより、４種類の実験用の太陽電池素子１１０の試料を作製した。 In producing four types of experimental solar cell elements 110, first, a polycrystalline silicon substrate having rectangular front and back surfaces with a side of about 156 mm and a thickness of about 200 μm was prepared. A passivation layer of about 50 nm was formed by the ALD method on the back surface side of this polycrystalline silicon substrate, and a protective layer 106 was formed on this passivation layer. At this time, an insulating paste containing a siloxane resin, an organic solvent, and a plurality of inorganic fillers is applied by a coater method on the passivation layer, and dried at about 270 ° C. to have a thickness of about 1 μm. The protective layer 106 was formed. Next, a first metal paste containing a metal powder containing aluminum (Al) as a main component, a glass component, and an organic vehicle was applied to substantially the entire surface of the protective layer 106 by screen printing. Here, four types of first metal pastes were used in which the content of the glass component was four levels of 2% by mass, 3.5% by mass, 4% by mass, and 5% by mass. Furthermore, a third metal paste containing a metal powder containing silver as a main component, an organic vehicle, and a glass frit was applied by screen printing to a pattern of the second output extraction electrode 108a. Then, by firing the first metal paste and the third metal paste under the condition that the maximum temperature is about 740 ° C. and the heating time is about one minute (min), the second output extraction electrode 108 a and the second output extraction electrode 108 a A back electrode 108 including the two current collection electrodes 108 b was formed. Thereby, samples of solar cell elements 110 for four types of experiments were produced.
　そして、図６（ａ）で示されるように、４種類の実験用の太陽電池素子１１０の試料のそれぞれについて、第２集電電極１０８ｂ上の二点鎖線で囲まれた領域Ａａ０にエチレン酢酸ビニル共重合体（ＥＶＡ）の樹脂を加熱しながら貼付した。そして、このＥＶＡ樹脂を第２集電電極１０８ｂ上から剥がすことで、第２集電電極１０８ｂが保護層１０６から剥離するか否かを確認する実験を行った。このとき、図６（ｂ）で示されるように、４種類の実験用の太陽電池素子１１０の試料のうち、作製に使用した第１金属ペースト中のガラス成分の含有率が４質量％および５質量％であった試料については、第２集電電極１０８ｂが保護層１０６から剥離しないことが認められた。これに対して、作製に使用した第１金属ペースト中のガラス成分の含有率が３．５質量％および２質量％と低ければ、第２集電電極１０８ｂが保護層１０６から剥離することが認められた。この実験結果より、第１金属ペーストに含有されていたガラス成分の含有量が低下すると、保護層１０６に対する第２集電電極１０８ｂの密着性が低下することが確認された。これにより、第１金属ペーストにおけるガラス成分の含有量が高まれば、ガラス成分の存在によって、保護層１０６と第２集電電極１０８ｂ中の金属粒子との間で密着性が高まることが分かった。 Then, as shown in FIG. 6A, for each of the samples of the four types of experimental solar cell elements 110, ethylene vinyl acetate is provided in a region Aa0 surrounded by a two-dot chain line on the second current collection electrode 108b. It stuck, heating resin of copolymer (EVA). Then, an experiment was conducted to confirm whether or not the second current collection electrode 108 b is peeled off from the protective layer 106 by peeling off the EVA resin from the second current collection electrode 108 b. At this time, as shown in FIG. 6 (b), the content of the glass component in the first metal paste used for the preparation is 4 mass% and 5 among the samples of the four types of experimental solar cell elements 110. It was found that the second current collection electrode 108 b was not peeled off from the protective layer 106 for the sample that was% by mass. On the other hand, if the content of the glass component in the first metal paste used for preparation is as low as 3.5 mass% and 2 mass%, it is recognized that the second current collection electrode 108 b peels off from the protective layer 106 It was done. From this experimental result, it was confirmed that when the content of the glass component contained in the first metal paste decreases, the adhesion of the second current collection electrode 108b to the protective layer 106 decreases. Thereby, it was found that if the content of the glass component in the first metal paste is increased, the adhesion between the protective layer 106 and the metal particles in the second current collection electrode 108b is enhanced due to the presence of the glass component.
　これに対して、第１実施形態に係る太陽電池素子１０では、保護層６の表面に存在している凸状部６ｐに凹状部分６ｐｒが存在している。このため、例えば、保護層６上に第１金属ペーストを塗布して第２集電電極８ｂを形成する際に、保護層６の表面に凹凸構造が存在していても、凸状部６ｐに存在している凹状部分６ｐｒに、第１金属ペースト中のガラス成分などが入り込む。このため、例えば、図４（ａ）および図５（ａ）で示された構成を形成する際には、凸状部６ｐ上に位置している第１金属ペーストにおいて、ガラス成分および有機ビヒクルなどを含む流動性を有する成分が重力方向に沿った方向（図４（ａ）および図５（ａ）の例では＋Ｚ方向）へ流出しにくくなる。これにより、凸状部６ｐ上に位置している第１金属ペーストにおいて、ガラス成分の含有量が減少しにくい。その結果、第２集電電極８ｂを形成する際に、保護層６上に塗布される第１金属ペーストの成分の分布に偏りが生じにくい。このとき、例えば、保護層６上における第２集電電極８ｂの密着性に偏りが生じにくい。そして、第１金属ペーストを焼成する際に、凹状部分６ｐｒではガラス成分の存在によって、凸状部６ｐにおいて保護層６と第２集電電極８ｂ中の金属粒子との間で密着性が向上し得る。また、例えば、第２集電電極８ｂの一部が保護層６の凹状部分６ｐｒに入り込むことで、いわゆるアンカー効果も生じ得る。これにより、保護層６に対する第２集電電極８ｂの密着性が向上し得る。その結果、例えば、保護層６からの第２集電電極８ｂの部分的な剥離が生じにくい。したがって、ＰＥＲＣ型の太陽電池素子１０における光電変換効率が向上し得る。 On the other hand, in the solar cell element 10 according to the first embodiment, the concave portion 6pr is present in the convex portion 6p present on the surface of the protective layer 6. Therefore, for example, when the first metal paste is applied on the protective layer 6 to form the second current collecting electrode 8b, the convex portion 6p may be formed even if the surface of the protective layer 6 has an uneven structure. The glass component and the like in the first metal paste penetrate into the existing concave portion 6pr. Therefore, for example, when forming the configuration shown in FIG. 4A and FIG. 5A, in the first metal paste located on the convex portion 6p, the glass component, the organic vehicle, etc. It becomes difficult for the fluid component including Y to flow out in the direction along the direction of gravity (the + Z direction in the example of FIG. 4A and FIG. 5A). Thereby, in the 1st metal paste located on convex-shaped part 6p, content of a glass component does not reduce easily. As a result, when the second current collection electrode 8 b is formed, the distribution of the components of the first metal paste applied on the protective layer 6 is less likely to be biased. At this time, for example, the adhesion of the second current collection electrode 8b on the protective layer 6 is unlikely to be uneven. And when baking a 1st metal paste, adhesiveness improves between the protective layer 6 and the metal particle in the 2nd current collection electrode 8b in convex part 6p by presence of a glass component in concave part 6pr. obtain. Further, for example, when a part of the second current collection electrode 8b enters the concave portion 6pr of the protective layer 6, a so-called anchor effect can also be generated. Thereby, the adhesion of the second current collection electrode 8 b to the protective layer 6 can be improved. As a result, for example, partial peeling of the second current collection electrode 8 b from the protective layer 6 does not easily occur. Therefore, the photoelectric conversion efficiency in the PERC solar cell element 10 can be improved.
　ここで、例えば、保護層６を第２集電電極８ｂの電極層８ｂｌ側から平面透視した場合に、保護層６の表面に存在している凹状部分６ｐｒの径は、例えば、０．１μｍから１０μｍ程度とされる。この場合には、例えば、第１金属ペーストの焼成を行う際に第１金属ペースト内で溶融している状態にあるガラス成分が、凹状部分６ｐｒに容易に入り込むことができる。その結果、保護層６に対する第２集電電極８ｂの密着性が向上し得る。 Here, for example, when the protective layer 6 is seen through in plan from the electrode layer 8bl side of the second current collection electrode 8b, the diameter of the concave portion 6pr present on the surface of the protective layer 6 is, for example, 0.1 μm to It is about 10 μm. In this case, for example, when firing the first metal paste, a glass component in a molten state in the first metal paste can easily enter the concave portion 6pr. As a result, the adhesion of the second current collection electrode 8b to the protective layer 6 can be improved.
　また、ここで、例えば、保護層６のうちの第２集電電極８ｂの電極層８ｂｌ側の表面に存在している凹状部分６ｐｒの深さは、例えば、０．１μｍから１μｍ程度とされる。ここで、例えば、凹状部分６ｐｒの深さが、凸状部６ｐの高さよりも小さければ、第２集電電極８ｂを形成する際に、保護層６上に塗布される第１金属ペーストの成分の分布に偏りが生じにくい。その結果、例えば、保護層６上における第２集電電極８ｂの密着性に偏りが生じにくい。また、ここで、例えば、保護層６において凹状部分６ｐｒが存在している部分における保護層６の厚さ（最小膜厚ともいう）が、０．５μｍ以上程度であれば、保護層６によってパッシベーション層４を保護する機能が確保され得る。 Here, for example, the depth of the concave portion 6pr present on the surface on the electrode layer 8bl side of the second current collection electrode 8b of the protective layer 6 is, for example, about 0.1 μm to 1 μm. . Here, for example, when the depth of the concave portion 6pr is smaller than the height of the convex portion 6p, the component of the first metal paste applied on the protective layer 6 when forming the second current collecting electrode 8b. Distribution is less likely to occur. As a result, for example, the adhesion of the second current collection electrode 8 b on the protective layer 6 is unlikely to be uneven. In addition, here, for example, if the thickness (also referred to as the minimum film thickness) of the protective layer 6 in the portion where the concave portion 6pr is present in the protective layer 6 is about 0.5 μm or more, passivation by the protective layer 6 is performed. The function of protecting the layer 4 can be secured.
　ところで、ここで、図４（ｂ）および図５（ｂ）で示されるように、例えば、凸状部６ｐに存在している複数の凹状部分６ｐｒのうちの隣り合う凹状部分６ｐｒ同士の距離（第１距離ともいう）をＤ１とする。第１距離Ｄ１としては、例えば、隣り合う凹状部分６ｐｒ同士の中心間の距離が採用される。この第１距離Ｄ１は、例えば、隣り合う凹状部分６ｐｒ同士の中心間の距離の平均値であってもよいし、隣り合う凹状部分６ｐｒが離れている距離（離間距離ともいう）であってもよいし、隣り合う凹状部分６ｐｒの離間距離の平均値であってもよい。また、図４（ａ）および図５（ａ）で示されるように、例えば、複数の凸状部６ｐのうちの隣り合う凸状部６ｐ同士の距離（第２距離ともいう）をＤ２とする。第２距離Ｄ２としては、例えば、隣り合う凸状部６ｐ同士の中心間あるいは頂部間の距離が採用される。この第２距離Ｄ２は、例えば、隣り合う凸状部６ｐ同士の中心間あるいは頂部間の距離の平均値であってもよいし、隣り合う凸状部６ｐの離間距離であってもよいし、隣り合う凸状部６ｐの離間距離の平均値であってもよい。また、図２および図３で示されるように、例えば、複数の孔部ＣＨ１に存在している複数の接続部８ｂｃのうちの隣り合う接続部８ｂｃ同士の距離（第３距離ともいう）をＤ３とする。第３距離Ｄ３としては、例えば、隣り合う接続部８ｂｃ同士の中心間の距離が採用される。この第３距離Ｄ３は、例えば、隣り合う接続部８ｂｃ同士の中心間の距離の平均値であってもよいし、隣り合う接続部８ｂｃの離間距離であってもよいし、隣り合う接続部８ｂｃの離間距離の平均値であってもよい。この場合に、例えば、第１距離Ｄ１が、第２距離Ｄ２および第３距離Ｄ３の何れよりも短ければ、保護層６に対する第２集電電極８ｂの密着性が十分に向上し得る。その結果、例えば、保護層６からの第２集電電極８ｂの部分的な剥離が生じにくい。したがって、ＰＥＲＣ型の太陽電池素子１０における光電変換効率が向上し得る。さらに、ここで、例えば、隣り合う凹状部分６ｐｒ同士がつながっていてもよい。この場合には、保護層６に対する第２集電電極８ｂの密着性がより向上し得る。その結果、例えば、保護層６からの第２集電電極８ｂの部分的な剥離がより生じにくい。 By the way, here, as shown in FIGS. 4 (b) and 5 (b), for example, the distance between adjacent concave portions 6pr among the plurality of concave portions 6pr present in the convex portion 6p The first distance is also referred to as D1. As the first distance D1, for example, a distance between centers of adjacent concave portions 6pr is adopted. The first distance D1 may be, for example, an average value of distances between centers of adjacent concave portions 6pr, or even a distance between adjacent concave portions 6pr (also referred to as a separation distance). It may be an average value of the separation distance between adjacent concave portions 6pr. Further, as shown in FIGS. 4A and 5A, for example, the distance (also referred to as a second distance) between adjacent convex portions 6p among the plurality of convex portions 6p is D2. . As the second distance D2, for example, the distance between the centers or the apexes of adjacent convex portions 6p is adopted. The second distance D2 may be, for example, an average value of distances between centers or apexes of adjacent convex portions 6p, or may be a distance between adjacent convex portions 6p. It may be an average value of the separation distances of the adjacent convex portions 6p. Further, as shown in FIGS. 2 and 3, for example, a distance (also referred to as a third distance) between adjacent connection portions 8bc among a plurality of connection portions 8bc existing in a plurality of hole portions CH1 is D3. I assume. As the third distance D3, for example, the distance between the centers of adjacent connection portions 8bc is adopted. The third distance D3 may be, for example, an average value of distances between centers of adjacent connection portions 8bc, or may be a separation distance between adjacent connection portions 8bc, or adjacent connection portions 8bc. The average value of the separation distances of In this case, for example, if the first distance D1 is shorter than any of the second distance D2 and the third distance D3, the adhesion of the second current collection electrode 8b to the protective layer 6 can be sufficiently improved. As a result, for example, partial peeling of the second current collection electrode 8 b from the protective layer 6 does not easily occur. Therefore, the photoelectric conversion efficiency in the PERC solar cell element 10 can be improved. Furthermore, here, for example, adjacent concave portions 6pr may be connected to each other. In this case, the adhesion of the second current collection electrode 8b to the protective layer 6 can be further improved. As a result, for example, partial peeling of the second current collection electrode 8 b from the protective layer 6 is less likely to occur.
　また、ここで、例えば、保護層６の電極層８ｂｌ側の面を平面視した場合に、凸状部６ｐにおける単位面積の領域を凹状部分６ｐｒが占める割合が、５％から４０％程度とされると、保護層６に対する第２集電電極８ｂの密着性が向上しやすくなる。ここでは、例えば、太陽電池素子１０の裏面電極８を塩酸などによるエッチングで除去した後に、ＳＥＭによって保護層６の電極層８ｂｌ側の面を観察することで、保護層６の電極層８ｂｌ側の面を平面視することができる。単位面積は、例えば、１０μｍ２から２０μｍ２の範囲に設定される。 Here, for example, when the surface on the electrode layer 8bl side of the protective layer 6 is viewed in plan, the ratio of the concave portion 6pr to the area of the unit area in the convex portion 6p is about 5% to 40%. Thus, the adhesion of the second current collection electrode 8b to the protective layer 6 can be easily improved. Here, for example, after the back electrode 8 of the solar cell element 10 is removed by etching with hydrochloric acid or the like, the surface of the protective layer 6 on the electrode layer 8 bl side is observed by SEM. The plane can be viewed in plan. The unit area is set, for example, in the range of 10 μm 2 to 20 μm 2 .
　また、ここで、例えば、図４（ｂ）および図７で示されるように、保護層６の非凸状部６ａｐも、凸状部６ｐと同様に、１つ以上の凹状部分６ｐｒを有していてもよい。これにより、例えば、保護層６のうちの第２集電電極８ｂの電極層８ｂｌ側の部分における広範囲にわたって、複数の凹状部分６ｐｒが存在し得る。そして、例えば、この非凸状部６ａｐの凹状部分６ｐｒの内部空間ＳＣ１にも、第２集電電極８ｂの電極層８ｂｌを構成している状態にあるガラス成分を含む電極成分が位置している。このような構成が採用されれば、第２集電電極８ｂの形成時に、保護層６上に塗布される第１金属ペーストの成分の分布が偏りを生じにくい。これにより、例えば、太陽電池素子１０の裏面１０ｂｓ側において、保護層６と第２集電電極８ｂとの間における密着性の分布に偏りが生じにくい。その結果、例えば、保護層６からの第２集電電極８ｂの部分的な剥離が生じにくい。したがって、ＰＥＲＣ型の太陽電池素子１０における光電変換効率が向上し得る。 Furthermore, here, as shown in, for example, FIGS. 4B and 7, the non-convex portion 6ap of the protective layer 6 also has one or more concave portions 6pr, similarly to the convex portion 6p. It may be Thereby, for example, a plurality of concave portions 6pr may exist over a wide range in the portion of the protective layer 6 on the electrode layer 8bl side of the second current collection electrode 8b. Then, for example, in the internal space SC1 of the concave portion 6pr of the non-convex portion 6ap, an electrode component including a glass component in a state of constituting the electrode layer 8bl of the second current collection electrode 8b is positioned . If such a configuration is adopted, the distribution of the components of the first metal paste applied onto the protective layer 6 is less likely to be uneven when the second current collection electrode 8 b is formed. Thereby, for example, on the back surface 10 bs side of the solar cell element 10, the distribution of the adhesion between the protective layer 6 and the second current collection electrode 8 b is unlikely to be biased. As a result, for example, partial peeling of the second current collection electrode 8 b from the protective layer 6 does not easily occur. Therefore, the photoelectric conversion efficiency in the PERC solar cell element 10 can be improved.
　　＜１－３．絶縁性ペースト＞
　第１実施形態では、例えば、保護層６を形成するために、２種類の絶縁性ペーストが用いられる。この２種類の絶縁性ペーストは、第１絶縁性ペーストおよび第２絶縁性ペーストを含む。 <1-3. Insulating paste>
In the first embodiment, for example, two types of insulating pastes are used to form the protective layer 6. The two types of insulating pastes include a first insulating paste and a second insulating paste.
　第１絶縁性ペーストおよび第２絶縁性ペーストのそれぞれは、例えば、シロキサン樹脂と、有機溶剤と、複数のフィラーと、を含む。シロキサン樹脂は、Ｓｉ－Ｏ－Ｓｉ結合（シロキサン結合）を有するシロキサン化合物である。具体的には、シロキサン樹脂としては、例えば、アルコキシシランまたはシラザンなどを加水分解させて縮合重合させることで生成された、分子量１万以下の低分子量の樹脂が採用される。 Each of the first insulating paste and the second insulating paste contains, for example, a siloxane resin, an organic solvent, and a plurality of fillers. The siloxane resin is a siloxane compound having a Si—O—Si bond (siloxane bond). Specifically, as the siloxane resin, for example, a low molecular weight resin having a molecular weight of 10,000 or less, which is produced by hydrolyzing alkoxysilane or silazane or the like and condensation polymerization, is employed.
　ここで、第１絶縁性ペーストにおける複数のフィラーは、主成分が無機材料であるフィラー（無機フィラーともいう）を含む。第２絶縁性ペーストにおける複数のフィラーは、主成分が有機材料であるフィラー（有機フィラーともいう）を含む。第２絶縁性ペーストにおける複数のフィラーは、無機フィラーを含んでいてもよい。 Here, the plurality of fillers in the first insulating paste include fillers (also referred to as inorganic fillers) whose main component is an inorganic material. The plurality of fillers in the second insulating paste contain a filler whose main component is an organic material (also referred to as an organic filler). The plurality of fillers in the second insulating paste may contain an inorganic filler.
　　＜１－４．絶縁性ペーストの製造＞
　　　＜１－４－１．第１絶縁性ペーストの製造＞
　第１絶縁性ペーストは、次のようにして製造され得る。 <1-4. Production of insulating paste>
<1-4-1. Production of first insulating paste>
The first insulating paste can be manufactured as follows.
　まず、シロキサン樹脂の前駆体と、水と、有機溶剤と、触媒と、フィラーと、を混合することで混合溶液を作製する。 First, a mixed solution is prepared by mixing a siloxane resin precursor, water, an organic solvent, a catalyst, and a filler.
　シロキサン樹脂の前駆体としては、例えば、Ｓｉ－Ｏ結合を有するシラン化合物またはＳｉ－Ｎ結合を有するシラザン化合物などが採用され得る。これらの化合物は、加水分解を生じる性質（加水分解性ともいう）を有する。また、シロキサン樹脂の前駆体は、加水分解して縮合重合を生じることでシロキサン樹脂となる。 As a precursor of the siloxane resin, for example, a silane compound having a Si—O bond or a silazane compound having a Si—N bond may be employed. These compounds have the property of causing hydrolysis (also referred to as hydrolyzability). Moreover, the precursor of a siloxane resin becomes a siloxane resin by hydrolyzing and producing condensation polymerization.
　シラン化合物は、次の一般式１で表される。 The silane compound is represented by the following general formula 1.
　（Ｒ１）ｎＳｉ（ＯＲ２）（４－ｎ）　・・・　（一般式１）。 (R1) n Si (OR2) (4-n) ... (general formula 1).
　一般式１のｎは、例えば、０、１、２および３のうちのいずれかの整数である。また、一般式１のＲ１およびＲ２は、メチル基（－ＣＨ３）およびエチル基（－Ｃ２Ｈ５）などのアルキル基（－ＣｍＨ２ｍ＋１）あるいはフェニル基（－Ｃ６Ｈ５）などといった炭素水素基を示す。ここで、ｍは、自然数である。 N in the general formula 1 is, for example, an integer of 0, 1, 2 or 3. Further, R1 and R2 in formula 1 is a methyl group (-CH 3) and ethyl group (-C 2 H 5) alkyl groups such as (-C m H 2m + 1) or phenyl group (-C 6 H 5), etc. Represents a carbon-hydrogen group such as Here, m is a natural number.
　ここで、シラン化合物は、例えば、少なくともＲ１がアルキル基を有するシラン化合物（アルキル基系のシラン化合物ともいう）を含む。具体的には、アルキル基系のシラン化合物としては、例えば、メチルトリメトキシシラン（ＣＨ３－Ｓｉ－（ＯＣＨ３）３）、ジメチルジメトキシシラン（（ＣＨ３）２－Ｓｉ－（ＯＣＨ３）２）、トリエトキシメチルシラン（ＣＨ３－Ｓｉ－（ＯＣ２Ｈ５）３）、ジエトキシジメチルシラン（（ＣＨ３）２－Ｓｉ－（ＯＣ２Ｈ５）２）、トリメトキシプロピルシラン（（ＣＨ３Ｏ）３－Ｓｉ－（ＣＨ２）２ＣＨ３）、トリエトキシプロピルシラン（（Ｃ２Ｈ５Ｏ）３－Ｓｉ－（ＣＨ２）２ＣＨ３）、ヘキシルトリメトキシシラン（（ＣＨ３Ｏ）３－Ｓｉ－（ＣＨ２）５ＣＨ３）、トリエトキシヘキシルシラン（（Ｃ２Ｈ５Ｏ）３－Ｓｉ－（ＣＨ２）５ＣＨ３）、トリエトキシオクチルシラン（（Ｃ２Ｈ５Ｏ）３－Ｓｉ－（ＣＨ２）７ＣＨ３）およびデシルトリメトキシシラン（（ＣＨ３Ｏ）３－Ｓｉ－（ＣＨ２）９ＣＨ３）などが挙げられる。 Here, the silane compound includes, for example, a silane compound in which at least R 1 has an alkyl group (also referred to as an alkyl group-based silane compound). Specifically, as the alkyl group-based silane compound, for example, methyltrimethoxysilane (CH 3 -Si- (OCH 3 ) 3 ), dimethyldimethoxysilane ((CH 3 ) 2 -Si- (OCH 3 ) 2 ), Triethoxymethylsilane (CH 3 -Si- (OC 2 H 5 ) 3 ), diethoxydimethylsilane ((CH 3 ) 2 -Si- (OC 2 H 5 ) 2 ), trimethoxypropylsilane ((CH 3 ) 3 O) 3 -Si- (CH 2 ) 2 CH 3 ), triethoxypropylsilane ((C 2 H 5 O) 3 -Si- (CH 2 ) 2 CH 3 ), hexyltrimethoxysilane ((CH 3 O) ) 3- Si- (CH 2 ) 5 CH 3 ), triethoxyhexylsilane ((C 2 H 5 O) 3 -Si- (CH 2 ) 5 CH 3 ), triethoxyoctyl Silane ((C 2 H 5 O) 3 -Si- (CH 2 ) 7 CH 3 ) and decyltrimethoxysilane ((CH 3 O) 3 -Si- (CH 2 ) 9 CH 3 ) and the like can be mentioned.
　ここで、例えば、アルキル基が、メチル基、エチル基またはプロピル基であれば、シロキサン樹脂の前駆体が加水分解する際に炭素数が少なく揮発しやすい副生成物としてのアルコールが生成され得る。これにより、後述する工程で副生成物が除去されやすくなる。その結果、例えば、保護層６を形成する際に、副生成物の蒸発による空孔の発生が起こりにくくなることで、保護層６が緻密となり、保護層６のバリア性が向上し得る。 Here, for example, when the alkyl group is a methyl group, an ethyl group or a propyl group, an alcohol as a by-product which has a small number of carbon atoms and is easy to volatilize may be generated when the precursor of the siloxane resin is hydrolyzed. Thereby, by-products are easily removed in the process described later. As a result, for example, when the protective layer 6 is formed, generation of pores due to evaporation of by-products hardly occurs, so that the protective layer 6 becomes dense, and the barrier property of the protective layer 6 can be improved.
　ここで、例えば、シロキサン樹脂の前駆体がフェニル基を有する場合には、シロキサン樹脂の前駆体は、加水分解して縮合重合し、フェニル基の加水分解および縮合重合で生じた副生成物が除去されたシロキサン樹脂とされた状態で、用いられてもよい。これにより、例えば、シロキサン樹脂の加水分解および縮合重合の反応による絶縁性ペーストの粘度の変動が低減され、絶縁性ペーストの粘度が安定しやすくなる。また、例えば、副生成物が除去された状態で、シロキサン樹脂と有機溶剤とフィラーとを混合して絶縁性ペーストを生成すれば、絶縁性ペーストに含有される副生成物の量が低減される。このため、このような絶縁性ペーストを生成すれば、例えば、スクリーン印刷法によって絶縁性ペーストの塗布を行う場合には、スクリーン製版の乳剤が副生成物によって溶解されることが低減される。その結果、スクリーン製版のパターンの寸法が変動しにくくなる。 Here, for example, when the precursor of the siloxane resin has a phenyl group, the precursor of the siloxane resin is hydrolyzed and subjected to condensation polymerization, and byproducts generated by the hydrolysis and condensation polymerization of the phenyl group are removed. You may be used in the state made into the produced siloxane resin. Thereby, for example, the fluctuation of the viscosity of the insulating paste due to the reaction of hydrolysis and condensation polymerization of the siloxane resin is reduced, and the viscosity of the insulating paste is easily stabilized. Also, for example, if an insulating paste is formed by mixing a siloxane resin, an organic solvent and a filler in a state in which by-products are removed, the amount of by-products contained in the insulating paste is reduced. . For this reason, if such an insulating paste is generated, for example, in the case of applying the insulating paste by screen printing, it is reduced that the emulsion of the screen plate making is dissolved by a by-product. As a result, the dimension of the pattern of the screen plate making is less likely to change.
　また、シラン化合物は、例えば、Ｒ１およびＲ２が、フェニル基とアルキル基の双方を有するシラン化合物を含む。このようなシラン化合物としては、例えば、トリメトキシフェニルシラン（Ｃ６Ｈ５－Ｓｉ－（ＯＣＨ３）３）、ジメトキシジフェニルシラン（（Ｃ６Ｈ５）２－Ｓｉ－（ＯＣＨ３）２）、メトキシトリフェニルシラン（（Ｃ６Ｈ５）３－Ｓｉ－ＯＣＨ３）、トリエトキシフェニルシラン（Ｃ６Ｈ５－Ｓｉ－（ＯＣ２Ｈ５）３）、ジエトキシジフェニルシラン（（Ｃ６Ｈ５）２－Ｓｉ－（ＯＣ２Ｈ５）２）、エトキシトリフェニルシラン（（Ｃ６Ｈ５）３－Ｓｉ－ＯＣ２Ｈ５）、トリイソプロポキシフェニルシラン（Ｃ６Ｈ５－Ｓｉ－（ＯＣＨ（ＣＨ３）２）３）、ジイソプロポキシジフェニルシラン（（Ｃ６Ｈ５）２－Ｓｉ－（ＯＣＨ（ＣＨ３）２）２）およびイソプロポキシトリフェニルシラン（（Ｃ６Ｈ５）３－Ｓｉ－ＯＣＨ（ＣＨ３）２）などが挙げられる。 The silane compounds also include, for example, silane compounds in which R1 and R2 have both a phenyl group and an alkyl group. As such a silane compound, for example, trimethoxyphenylsilane (C 6 H 5 -Si- (OCH 3 ) 3 ), dimethoxydiphenylsilane ((C 6 H 5 ) 2 -Si- (OCH 3 ) 2 ), Methoxytriphenylsilane ((C 6 H 5 ) 3 -Si-OCH 3 ), triethoxyphenylsilane (C 6 H 5 -Si- (OC 2 H 5 ) 3 ), diethoxydiphenylsilane ((C 6 H 5) ) 2- Si- (OC 2 H 5 ) 2 ), ethoxytriphenylsilane ((C 6 H 5 ) 3 -Si-OC 2 H 5 ), triisopropoxyphenylsilane (C 6 H 5 -Si- (OCH) (CH 3) 2) 3) , diisopropoxy diphenylsilane ((C 6 H 5) 2 -Si- (OCH (CH 3) 2) 2) and Isopuropokishito Phenyl silane ((C 6 H 5) 3 -Si-OCH (CH 3) 2) can be mentioned.
　これらのシラン化合物のうち、例えば、２つ以上のＯＲ結合を含むシラン化合物が採用されれば、シラン化合物が加水分解した後に縮合重合を生じることで生成されるシロキサン結合（Ｓｉ－Ｏ－Ｓｉ結合）の数が増加し得る。これにより、保護層６を形成する酸化シリコンにおけるシロキサン結合のネットワークが多くなり得る。その結果、保護層６のバリア性が向上し得る。 Among these silane compounds, for example, if a silane compound containing two or more OR bonds is adopted, a siloxane bond (Si-O-Si bond) is generated by causing condensation polymerization after the silane compound is hydrolyzed. The number of) can be increased. This can increase the number of siloxane bond networks in the silicon oxide that forms the protective layer 6. As a result, the barrier properties of the protective layer 6 can be improved.
　また、シラザン化合物は、無機シラザン化合物および有機シラザン化合物の何れであってもよい。ここで、無機シラザン化合物としては、例えば、ポリシラザン（－（Ｈ２ＳｉＮＨ）－）が挙げられる。有機シラザン化合物としては、例えば、ヘキサメチルジシラザン（（ＣＨ３）３－Ｓｉ－ＮＨ－Ｓｉ－（ＣＨ３）３）、テトラメチルシクロジシラザン（（ＣＨ３）２－Ｓｉ－（ＮＨ）２－Ｓｉ－（ＣＨ３）２）およびテトラフェニルシクロジシラザン（（Ｃ６Ｈ５）２－Ｓｉ－（ＮＨ）２－Ｓｉ－（Ｃ６Ｈ５）２）などが挙げられる。 The silazane compound may be either an inorganic silazane compound or an organic silazane compound. Here, examples of the inorganic silazane compound include polysilazane (— (H 2 SiNH) —). As the organic silazane compound, for example, hexamethyldisilazane ((CH 3 ) 3 -Si-NH-Si- (CH 3 ) 3 ), tetramethylcyclodisilazane ((CH 3 ) 2 -Si- (NH) 2 And -Si- (CH 3 ) 2 ) and tetraphenylcyclodisilazane ((C 6 H 5 ) 2 -Si- (NH) 2 -Si- (C 6 H 5 ) 2 ).
　水は、シロキサン樹脂の前駆体を加水分解させるための液体である。例えば、水として、純水を用いる。例えば、シラン化合物のＳｉ－ＯＣＨ３の結合に対して水が反応することで、Ｓｉ－ＯＨ結合とＨＯ－ＣＨ３（メタノール）を生じさせる。 Water is a liquid for hydrolyzing the precursor of the siloxane resin. For example, pure water is used as water. For example, water reacts to the bond of Si-OCH 3 of the silane compound to form Si-OH bond and HO-CH 3 (methanol).
　有機溶剤は、シロキサン樹脂の前駆体からシロキサン樹脂を含むペーストを生成するための溶剤である。また、有機溶剤は、シロキサン樹脂の前駆体と水とを混合させることができる。有機溶剤としては、例えば、ジエチレングリコールモノブチルエーテル、メチルセロソルブ、エチルセロソルブ、エチルアルコール、２－（４－メチルシクロヘキサ－３－エニル）プロパン－２－オールまたは２－プロパノールなどが用いられる。ここでは、これらの有機溶剤のうちの１種類の有機溶剤および２種類以上の有機溶剤を混合した有機溶剤の何れが用いられてもよい。 The organic solvent is a solvent for producing a paste containing a siloxane resin from a precursor of the siloxane resin. Moreover, the organic solvent can mix the precursor of siloxane resin, and water. As the organic solvent, for example, diethylene glycol monobutyl ether, methyl cellosolve, ethyl cellosolve, ethyl alcohol, 2- (4-methylcyclohex-3-enyl) propan-2-ol, 2-propanol or the like is used. Here, any one of these organic solvents and an organic solvent in which two or more organic solvents are mixed may be used.
　触媒は、シロキサン樹脂の前駆体が加水分解および縮合重合を生じる際に、反応の速度を制御することができる。例えば、シロキサン樹脂の前駆体が含むＳｉ－ＯＲ結合（例えば、Ｒはアルキル基）に加水分解および縮合重合を生じさせて、２つ以上のＳｉ－ＯＨからＳｉ－Ｏ－Ｓｉ結合とＨ２Ｏ（水）とを生じさせる反応の速度が調整され得る。触媒としては、例えば、塩酸、硝酸、硫酸、ホウ酸、燐酸、フッ化水素酸および酢酸などのうちの１種類以上の無機酸または１種類以上の有機酸が用いられる。また、触媒として、例えば、アンモニア、水酸化ナトリウム、水酸化カリウム、水酸化バリウム、水酸化カルシウムおよびピリジンなどのうちの１種類以上の無機塩基または１種類以上の有機塩基が用いられてもよい。さらに、触媒は、例えば、無機酸と有機酸とが組み合わされたものでもよく、無機塩基と有機塩基とが組み合わされたものであってもよい。 The catalyst can control the rate of reaction as the precursor of the siloxane resin undergoes hydrolysis and condensation polymerization. For example, hydrolysis and condensation polymerization are caused to the Si-OR bond (for example, R is an alkyl group) included in the precursor of the siloxane resin to generate Si-O-Si bond and H 2 O from two or more Si-OH bonds. The rate of reaction to produce (water) can be adjusted. As the catalyst, for example, one or more inorganic acids or one or more organic acids of hydrochloric acid, nitric acid, sulfuric acid, boric acid, phosphoric acid, hydrofluoric acid, acetic acid and the like are used. Further, as a catalyst, for example, one or more types of inorganic bases or one or more types of organic bases among ammonia, sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide and pyridine may be used. Furthermore, the catalyst may be, for example, a combination of an inorganic acid and an organic acid, or a combination of an inorganic base and an organic base.
　フィラーは、例えば、酸化シリコン、酸化アルミニウムまたは酸化チタンなどを含む無機フィラーである。 The filler is, for example, an inorganic filler containing silicon oxide, aluminum oxide or titanium oxide.
　ここで混合される各材料の混合比率については、例えば、全ての材料を混合した後の混合溶液において、シロキサン樹脂の前駆体の濃度が７質量％から６０質量％となり、水の濃度が５質量％から４０質量％（１０質量％から２０質量％でもよい）となり、触媒の濃度が１ｐｐｍから１０００ｐｐｍとなり、有機溶剤の濃度が５質量％から５０質量％となり、無機フィラーの濃度が３質量％から３０質量％となるように調整される。このような混合比率であれば、例えば、シロキサン樹脂の前駆体の加水分解および縮合重合によって生じるシロキサン樹脂を、絶縁性ペースト中に適切な濃度で含有させることができる。また、例えば、絶縁性ペーストにおいてゲル化による過度な粘度の増大が生じにくい。 As for the mixing ratio of each material mixed here, for example, in the mixed solution after mixing all the materials, the concentration of the precursor of the siloxane resin becomes 7 mass% to 60 mass%, and the concentration of water is 5 mass % To 40 wt% (may be 10 wt% to 20 wt%), the concentration of the catalyst is 1 ppm to 1000 ppm, the concentration of the organic solvent is 5 wt% to 50 wt%, the concentration of the inorganic filler is 3 wt% to It is adjusted to be 30% by mass. With such a mixing ratio, for example, a siloxane resin produced by hydrolysis and condensation polymerization of a precursor of a siloxane resin can be contained in the insulating paste at an appropriate concentration. Also, for example, in the insulating paste, excessive increase in viscosity due to gelation does not easily occur.
　このようにして材料が混合される際には、シロキサン樹脂の前駆体と水とが反応して、シロキサン樹脂の前駆体の加水分解が始まる。また、加水分解したシロキサン樹脂の前駆体が縮合重合を生じて、シロキサン樹脂が生成され始める。 Thus, when the materials are mixed, the siloxane resin precursor and water react with each other to initiate hydrolysis of the siloxane resin precursor. Also, the precursor of the hydrolyzed siloxane resin causes condensation polymerization to begin to form the siloxane resin.
　次に、混合溶液を攪拌する。ここでは、混合溶液を、例えば、ミックスローターまたはスターラーなどを用いて攪拌する。混合溶液を攪拌すると、さらに、シロキサン樹脂の前駆体の加水分解が進行する。また、加水分解したシロキサン樹脂の前駆体が縮合重合を生じ、シロキサン樹脂が生成され続ける。例えば、ミックスローターで攪拌を行なう場合には、ミックスローターの回転ローラーの回転数が４００ｒｐｍから６００ｒｐｍ程度とされ、攪拌時間が３０分間から９０分間程度とされる攪拌条件が採用される。このような攪拌条件が採用されると、シロキサン樹脂の前駆体、水、触媒および有機溶剤を均一に混合することができる。また、混合溶液を攪拌する際には、例えば、混合溶液が加熱されれば、シロキサン樹脂の前駆体の加水分解および縮合重合が進行しやすい。これにより、例えば、攪拌時間の短縮による生産性の向上が図られ得るとともに、混合溶液の粘度が安定しやすくなる。 Next, the mixed solution is stirred. Here, the mixed solution is stirred using, for example, a mix rotor or a stirrer. When the mixed solution is stirred, the hydrolysis of the precursor of the siloxane resin further proceeds. Also, the precursor of the hydrolyzed siloxane resin causes condensation polymerization, and the siloxane resin continues to be produced. For example, in the case of stirring with a mix rotor, the rotation conditions of the rotation roller of the mix rotor are set to about 400 rpm to 600 rpm, and the stirring conditions are set such that the stirring time is about 30 minutes to 90 minutes. When such stirring conditions are adopted, the precursor of the siloxane resin, water, the catalyst and the organic solvent can be uniformly mixed. In addition, when the mixed solution is stirred, for example, if the mixed solution is heated, hydrolysis and condensation polymerization of the precursor of the siloxane resin easily proceed. As a result, for example, the productivity can be improved by shortening the stirring time, and the viscosity of the mixed solution can be easily stabilized.
　次に、混合溶液から水と触媒とを揮発させることで、第１絶縁性ペーストが製造され得る。ここで、例えば、第１絶縁性ペーストをスクリーン印刷法で塗布する場合には、スクリーンの乳剤が溶けて寸法が変動することが起こりにくくなるように、副生成物および有機溶剤も揮発させる。副生成物は、例えば、シロキサン樹脂の前駆体と水との反応によって発生したアルコールなどの有機成分を含む。 Next, the first insulating paste can be manufactured by volatilizing water and the catalyst from the mixed solution. Here, for example, when the first insulating paste is applied by screen printing, the by-products and the organic solvent are also volatilized so that the emulsion of the screen is unlikely to melt and change in size. By-products include, for example, organic components such as alcohols generated by the reaction of a siloxane resin precursor with water.
　ここでは、例えば、ホットプレートまたは乾燥炉などを用いて、処理温度が室温から９０℃程度（５０℃から９０℃程度でもよい）であり且つ処理時間が１０分間から６００分間程度である条件で、攪拌後の混合溶液に処理を施す。処理温度が上記温度範囲内であれば副生成物が除去され得る。また、上記温度範囲内では、副生成物である有機成分が揮発しやすいため、処理時間の短縮による生産性の向上が図られ得る。ここで、例えば、減圧下であれば、副生成物である有機成分が揮発しやすい。その結果、処理時間の短縮による生産性の向上が図られ得る。また、例えば、ここで、混合溶液が攪拌された際に加水分解せずに残存したシロキサン樹脂の前駆体をさらに加水分解させてもよい。 Here, for example, using a hot plate or a drying furnace, the processing temperature is about room temperature to 90 ° C. (may be about 50 ° C. to 90 ° C.) and the processing time is about 10 minutes to 600 minutes. The mixed solution after stirring is treated. By-products can be removed if the treatment temperature is within the above temperature range. Moreover, since the organic component which is a by-product is easily volatilized within the said temperature range, the improvement of productivity by shortening of processing time may be achieved. Here, for example, under reduced pressure, the by-product organic component is likely to be volatilized. As a result, productivity can be improved by shortening the processing time. Also, for example, when the mixed solution is stirred, the precursor of the siloxane resin remaining without being hydrolyzed may be further hydrolyzed.
　　　＜１－４－２．第２絶縁性ペーストの製造＞
　第２絶縁性ペーストの製造方法は、例えば、上述した第１絶縁性ペーストの製造方法において、無機フィラーの全部あるいは一部に代えて、混合溶液に有機フィラーを添加することで実現され得る。ここでは、例えば、混合溶液中の副生成物および有機溶剤による有機フィラーの溶解が生じにくくなるように、混合溶液中の副生成物および有機溶剤を揮発させた後に、混合溶液に有機フィラーを添加し、混合溶液を攪拌してもよい。 <1-4-2. Production of second insulating paste>
The method for producing the second insulating paste can be realized, for example, by adding an organic filler to the mixed solution in place of all or part of the inorganic filler in the method for producing the first insulating paste described above. Here, for example, the organic filler is added to the mixed solution after volatilizing the by-products and the organic solvent in the mixed solution so that the dissolution of the organic filler by the by-product and the organic solvent in the mixed solution is less likely to occur. And the mixed solution may be stirred.
　ここで、有機フィラーとしては、例えば、保護層６を形成する際に第２絶縁性ペーストを乾燥させる温度以下において、熱分解を生じる素材を主成分として含むものが採用される。有機フィラーが熱分解を生じる温度は、例えば、３００℃以下である。このような素材としては、アクリル系の素材などが挙げられる。有機フィラーの平均粒径は、例えば、１μｍ程度以下とされる。また、ここでは、例えば、１００質量部の混合溶液に対して、５質量部から２０質量部程度の有機フィラーが添加されれば、混合溶液の粘度ならびに保護層６に形成される凹状部分６ｐｒの数が容易に調整され得る。 Here, as the organic filler, for example, one containing as a main component a material that causes thermal decomposition at a temperature at which the second insulating paste is dried when forming the protective layer 6 is employed. The temperature at which the organic filler causes thermal decomposition is, for example, 300 ° C. or less. Such materials include acrylic materials and the like. The average particle size of the organic filler is, for example, about 1 μm or less. Here, for example, if about 5 parts by mass to about 20 parts by mass of the organic filler is added to 100 parts by mass of the mixed solution, the viscosity of the mixed solution and the concave portion 6pr formed in the protective layer 6 The number can be easily adjusted.
　　＜１－５．太陽電池素子の製造方法＞
　太陽電池素子１０の製造方法の一例について、図８（ａ）から図８（ｆ）に基づいて説明する。 <1-5. Method of manufacturing solar cell element>
An example of the manufacturing method of the solar cell element 10 is demonstrated based on FIG. 8 (a)-FIG.8 (f).
　まず、半導体基板１を準備する工程（第１工程ともいう）を実施する。半導体基板１は、第１面１ｂｓおよびこの第１面１ｂｓとは逆方向を向いた第２面１ｆｓを有する。 First, the step of preparing the semiconductor substrate 1 (also referred to as a first step) is performed. The semiconductor substrate 1 has a first surface 1 bs and a second surface 1 fs facing in the opposite direction to the first surface 1 bs.
　ここでは、例えば、まず、図８（ａ）で示されるように半導体基板１を準備する。半導体基板１は、例えば、既存のＣＺ法または鋳造法などを用いて形成され得る。ここでは、鋳造法によって作製されたｐ型の多結晶シリコンのインゴットを用いた例について説明する。このインゴットを、例えば２５０μｍ以下の厚さにスライスして半導体基板１を作製する。ここで、例えば、半導体基板１の表面に対して、水酸化ナトリウム、水酸化カリウム、フッ酸またはフッ硝酸などの水溶液でごく微量のエッチングを施すと、半導体基板１の切断面の機械的なダメージを受けた層および汚染された層を除去することができる。このとき、例えば、半導体基板１の第２面１ｆｓに上述したテクスチャの一部が形成され得るとともに、半導体基板１の第１面１ｂｓにも上述した凹凸構造１ｒｇの少なくとも一部が形成され得る。 Here, for example, first, the semiconductor substrate 1 is prepared as shown in FIG. The semiconductor substrate 1 can be formed, for example, using the existing CZ method or casting method. Here, an example using a p-type polycrystalline silicon ingot manufactured by a casting method will be described. The ingot is sliced to a thickness of, for example, 250 μm or less to manufacture the semiconductor substrate 1. Here, for example, when a very small amount of etching is performed on the surface of the semiconductor substrate 1 with an aqueous solution such as sodium hydroxide, potassium hydroxide, hydrofluoric acid or fluoronitric acid, mechanical damage to the cut surface of the semiconductor substrate 1 And the contaminated layer can be removed. At this time, for example, a part of the above-described texture may be formed on the second surface 1 fs of the semiconductor substrate 1, and at least a part of the above-described uneven structure 1 rg may be formed on the first surface 1 bs of the semiconductor substrate 1.
　次に、図８（ｂ）で示されるように、半導体基板１の第２面１ｆｓにテクスチャを形成する。テクスチャは、水酸化ナトリウムなどのアルカリ性の水溶液またはフッ硝酸などの酸性の水溶液を用いたウエットエッチング、あるいは反応性イオンエッチング（Reactive Ion Etching：ＲＩＥ）法などを使用したドライエッチングによって形成され得る。このとき、例えば半導体基板１の第１面１ｂｓに、上述した凹凸構造１ｒｇの少なくとも一部が形成されてもよい。 Next, as shown in FIG. 8B, the texture is formed on the second surface 1 fs of the semiconductor substrate 1. The texture can be formed by wet etching using an alkaline aqueous solution such as sodium hydroxide or an acidic aqueous solution such as hydrofluoric-nitric acid, or dry etching using a reactive ion etching (RIE) method or the like. At this time, for example, at least a part of the concavo-convex structure 1 rg described above may be formed on the first surface 1 bs of the semiconductor substrate 1.
　次に、図８（ｃ）で示されるように、テクスチャを有する半導体基板１の第２面１ｆｓ側の表層部に、ｎ型の半導体領域である第２半導体層３を形成する。第２半導体層３は、例えば、ペースト状にした五酸化二燐（Ｐ２Ｏ５）を半導体基板１の表面に塗布して燐を熱拡散させる塗布熱拡散法、あるいはガス状にしたオキシ塩化燐（ＰＯＣｌ３）を拡散源とした気相熱拡散法などを用いて形成され得る。第２半導体層３は、例えば、０．１μｍから２μｍ程度の深さと４０Ω／□から２００Ω／□程度のシート抵抗値とを有するように形成される。 Next, as shown in FIG. 8C, the second semiconductor layer 3 which is an n-type semiconductor region is formed in the surface layer portion on the second surface 1 fs side of the semiconductor substrate 1 having texture. The second semiconductor layer 3 is formed, for example, by applying a paste-like diphosphorus pentoxide (P 2 O 5 ) on the surface of the semiconductor substrate 1 to thermally diffuse phosphorus, or a gaseous oxychloride It can be formed by using a vapor phase thermal diffusion method using phosphorus (POCl 3 ) as a diffusion source. The second semiconductor layer 3 is formed to have, for example, a depth of about 0.1 μm to 2 μm and a sheet resistance value of about 40 Ω / □ to 200 Ω / □.
　例えば、気相熱拡散法では、まず、ＰＯＣｌ３などを主として含有する拡散ガスを有する雰囲気中において６００℃から８００℃程度の温度において半導体基板１に５分間から３０分間程度の熱処理を施して、燐ガラスを半導体基板１の表面に形成する。その後、アルゴンまたは窒素などの不活性ガスの雰囲気中において８００℃から９００℃程度の比較的高温において、半導体基板１に１０分間から４０分間程度の熱処理を施す。これにより、燐ガラスから半導体基板１に燐が拡散して、半導体基板１の第２面１ｆｓ側の表層部に第２半導体層３が形成される。 For example, in the vapor phase thermal diffusion method, first, the semiconductor substrate 1 is subjected to heat treatment for about 5 minutes to 30 minutes at a temperature of about 600 ° C. to 800 ° C. in an atmosphere having a diffusion gas mainly containing POCl 3 or the like. Phosphorous glass is formed on the surface of the semiconductor substrate 1. Thereafter, the semiconductor substrate 1 is subjected to heat treatment for about 10 minutes to about 40 minutes at a relatively high temperature of about 800 ° C. to 900 ° C. in an atmosphere of an inert gas such as argon or nitrogen. Thereby, phosphorus is diffused from the phosphorus glass to the semiconductor substrate 1, and the second semiconductor layer 3 is formed in the surface layer portion on the second surface 1 fs side of the semiconductor substrate 1.
　ここで、第２半導体層３を形成する際に、第１面１ｂｓ側にも第２半導体層が形成される場合がある。この場合には、第１面１ｂｓ側に形成された第２半導体層をエッチングで除去する。例えば、フッ硝酸の水溶液に半導体基板１の第１面１ｂｓ側の部分を浸すことで、第１面１ｂｓ側に形成された第２半導体層を除去することができる。これにより、半導体基板１の第１面１ｂｓにｐ型の導電型を有する領域を露出させることができる。その後、第２半導体層３を形成する際に半導体基板１の第２面１ｆｓ側に付着した燐ガラスをエッチングで除去する。このように、第２面１ｆｓ側に燐ガラスを残存させた状態で、第１面１ｂｓ側に形成された第２半導体層をエッチングで除去すれば、第２面１ｆｓ側の第２半導体層３の除去およびダメージが低減され得る。このとき、半導体基板１の第３面１ｓｓに形成された第２半導体層も併せて除去してもよい。 Here, when the second semiconductor layer 3 is formed, the second semiconductor layer may be formed on the side of the first surface 1 bs. In this case, the second semiconductor layer formed on the first surface 1 bs side is removed by etching. For example, the second semiconductor layer formed on the first surface 1 bs side can be removed by immersing a portion on the first surface 1 bs side of the semiconductor substrate 1 in an aqueous solution of hydrofluoric-nitric acid. Thereby, the region having the p-type conductivity type can be exposed on the first surface 1 bs of the semiconductor substrate 1. Thereafter, when the second semiconductor layer 3 is formed, the phosphorus glass attached to the second surface 1 fs side of the semiconductor substrate 1 is removed by etching. As described above, with the phosphorus glass remaining on the second surface 1 fs side, if the second semiconductor layer formed on the first surface 1 bs side is removed by etching, the second semiconductor layer 3 on the second surface 1 fs side is removed. Removal and damage can be reduced. At this time, the second semiconductor layer formed on the third surface 1 ss of the semiconductor substrate 1 may be removed together.
　また、例えば、半導体基板１の第１面１ｂｓ側に予め拡散マスクを形成しておき、気相熱拡散法などによって第２半導体層３を形成し、続いて拡散マスクを除去してもよい。この場合には、第１面１ｂｓ側に第２半導体層は形成されないため、第１面１ｂｓ側の第２半導体層を除去する工程が不要となる。 Alternatively, for example, a diffusion mask may be formed in advance on the first surface 1 bs side of the semiconductor substrate 1, the second semiconductor layer 3 may be formed by a vapor phase thermal diffusion method or the like, and then the diffusion mask may be removed. In this case, since the second semiconductor layer is not formed on the first surface 1 bs side, the step of removing the second semiconductor layer on the first surface 1 bs side is unnecessary.
　以上の処理によって、第２面１ｆｓ側にｎ型の半導体層である第２半導体層３が位置し、第２面１ｆｓにテクスチャを有し、且つ第１面１ｂｓに凹凸構造１ｒｇを有する、第１半導体層２を含む半導体基板１が準備され得る。 By the above processing, the second semiconductor layer 3 which is an n-type semiconductor layer is located on the second surface 1 fs side, has texture on the second surface 1 fs, and has the concavo-convex structure 1 rg on the first surface 1 bs. The semiconductor substrate 1 including the one semiconductor layer 2 can be prepared.
　次に、パッシベーション層４を形成する工程（第２工程ともいう）を実施する。第１実施形態では、少なくとも、半導体基板１の第１面１ｂｓ上にパッシベーション層４が形成される。 Next, the step of forming passivation layer 4 (also referred to as a second step) is performed. In the first embodiment, the passivation layer 4 is formed at least on the first surface 1 bs of the semiconductor substrate 1.
　ここでは、例えば、図８（ｄ）で示されるように、第１半導体層２の第１面１ｂｓの上と、第２半導体層３の第２面１ｆｓの上に、酸化アルミニウムを主として含有するパッシベーション層４を形成する。また、パッシベーション層４の上に反射防止層５を形成する。反射防止層５は、例えば、窒化シリコン膜などによって構成される。 Here, for example, as shown in FIG. 8 (d), aluminum oxide is mainly contained on the first surface 1 bs of the first semiconductor layer 2 and the second surface 1 fs of the second semiconductor layer 3. The passivation layer 4 is formed. In addition, the antireflective layer 5 is formed on the passivation layer 4. The antireflection layer 5 is made of, for example, a silicon nitride film or the like.
　パッシベーション層４は、例えば、ＣＶＤ法またはＡＬＤ法などによって形成され得る。ＡＬＤ法によれば、例えば、半導体基板１の第３面１ｓｓを含む全周囲にパッシベーション層４が形成され得る。ＡＬＤ法によるパッシベーション層４の形成工程では、まず、成膜装置のチャンバー内に、第２半導体層３までが形成された半導体基板１を載置する。そして、半導体基板１を１００℃から２５０℃程度の温度域まで加熱した状態で、次の工程Ａから工程Ｄを複数回繰り返し行い、酸化アルミニウムを主に含有するパッシベーション層４を形成する。これにより、所望の厚さを有するパッシベーション層４が形成される。 Passivation layer 4 can be formed by, for example, a CVD method or an ALD method. According to the ALD method, for example, the passivation layer 4 can be formed all around the semiconductor substrate 1 including the third surface 1ss. In the step of forming the passivation layer 4 by the ALD method, first, the semiconductor substrate 1 on which the second semiconductor layer 3 is formed is placed in the chamber of the film forming apparatus. Then, in a state where the semiconductor substrate 1 is heated to a temperature range of about 100 ° C. to about 250 ° C., the following steps A to D are repeated a plurality of times to form a passivation layer 4 mainly containing aluminum oxide. Thereby, the passivation layer 4 having a desired thickness is formed.
　［工程Ａ］酸化アルミニウムを形成するためのトリメチルアルミニウム（ＴＭＡ）などのアルミニウム原料が、Ａｒガスまたは窒素ガスなどのキャリアガスとともに、半導体基板１上に供給される。これにより、半導体基板１の全周囲にアルミニウム原料が吸着される。ＴＭＡが供給される時間は、例えば、１５ミリ秒（ｍ秒：ｍｓｅｃ）間から３０００ミリ秒間程度とされる。ここで、工程Ａの開始時には、半導体基板１の表面はＯＨ基で終端されていてもよい。換言すれば、半導体基板１の表面がＳｉ－Ｏ－Ｈの構造であってもよい。この構造は、例えば、半導体基板１を希フッ酸で処理した後に純水で洗浄することで形成され得る。 [Step A] An aluminum source such as trimethylaluminum (TMA) for forming aluminum oxide is supplied onto the semiconductor substrate 1 together with a carrier gas such as Ar gas or nitrogen gas. Thereby, the aluminum source is adsorbed on the entire periphery of the semiconductor substrate 1. The time for which the TMA is supplied is, for example, about 15 milliseconds (msec: msec) to about 3000 milliseconds. Here, at the start of step A, the surface of the semiconductor substrate 1 may be terminated with an OH group. In other words, the surface of the semiconductor substrate 1 may have a Si—O—H structure. This structure can be formed, for example, by treating the semiconductor substrate 1 with dilute hydrofluoric acid and then washing with pure water.
　［工程Ｂ］窒素ガスによって成膜装置のチャンバー内の浄化が行なわれることで、チャンバー内のアルミニウム原料が除去される。さらに、半導体基板１に物理吸着および化学吸着したアルミニウム原料の内、原子層レベルで化学吸着した成分以外のアルミニウム原料が除去される。窒素ガスによってチャンバー内が浄化される時間は、例えば、１秒（ｓｅｃ）間から数十秒間程度とされる。 [Step B] The inside of the chamber of the film forming apparatus is cleaned with nitrogen gas, whereby the aluminum source in the chamber is removed. Furthermore, among the aluminum raw materials physically and chemically adsorbed to the semiconductor substrate 1, aluminum raw materials other than the components chemically adsorbed at the atomic layer level are removed. The time for cleaning the inside of the chamber with nitrogen gas is, for example, about one second (sec) to several tens of seconds.
　［工程Ｃ］水またはオゾンガスなどの酸化剤が、成膜装置のチャンバー内に供給されることで、ＴＭＡが含むアルキル基が除去されてＯＨ基で置換される。これにより、半導体基板１の上に酸化アルミニウムの原子層が形成される。酸化剤がチャンバー内に供給される時間は、例えば、７５０ミリ秒間から１１００ミリ秒間程度とされる。また、例えば、チャンバー内に酸化剤ととともに水素が供給されれば、酸化アルミニウムに水素原子がより含有されやすくなる。 [Step C] By supplying an oxidizing agent such as water or ozone gas into the chamber of the film forming apparatus, the alkyl group contained in TMA is removed and substituted by an OH group. Thereby, an atomic layer of aluminum oxide is formed on the semiconductor substrate 1. The time during which the oxidizing agent is supplied into the chamber is, for example, about 750 milliseconds to 1100 milliseconds. Also, for example, if hydrogen is supplied together with the oxidizing agent in the chamber, the hydrogen atoms are more easily contained in the aluminum oxide.
　［工程Ｄ］窒素ガスによって成膜装置のチャンバー内の浄化が行なわれることで、チャンバー内の酸化剤が除去される。このとき、例えば、半導体基板１上における原子層レベルの酸化アルミニウムの形成時において反応に寄与しなかった酸化剤などが除去される。ここで、窒素ガスによってチャンバー内が浄化される時間は、例えば、１秒間以上から数十秒間程度とされる。 [Step D] The oxidizing agent in the chamber is removed by cleaning the chamber of the film forming apparatus with nitrogen gas. At this time, for example, an oxidizing agent which does not contribute to the reaction at the time of formation of aluminum oxide at the atomic layer level on the semiconductor substrate 1 is removed. Here, the time during which the inside of the chamber is purified by nitrogen gas is, for example, about one second or more to several tens of seconds.
　以後、工程Ａ、工程Ｂ、工程Ｃおよび工程Ｄがこの記載の順に行われる一連の工程を複数回繰り返すことで、所望の膜厚の酸化アルミニウムの層が形成される。 Thereafter, by repeating a series of steps in which step A, step B, step C and step D are sequentially performed in this order, a layer of aluminum oxide having a desired film thickness is formed.
　反射防止層５は、例えば、ＰＥＣＶＤ法またはスパッタリング法を用いて形成される。ＰＥＣＶＤ法を用いる場合は、事前に半導体基板１を反射防止層５の成膜中の温度よりも高い温度まで加熱しておく。その後、シラン（ＳｉＨ４）とアンモニア（ＮＨ３）との混合ガスを、窒素（Ｎ２）ガスで希釈し、反応圧力を５０Ｐａから２００Ｐａ程度にして、グロー放電分解でプラズマ化させたものを、加熱された半導体基板１上に堆積させる。これにより、半導体基板１上に反射防止層５が形成される。このとき、成膜温度を、３５０℃から６５０℃程度とし、半導体基板１の事前の加熱温度を成膜温度よりも５０℃程度高くする。また、グロー放電に必要な高周波電源の周波数として、１０ｋＨｚから５００ｋＨｚ程度の周波数が採用される。また、ガスの流量は、反応室の大きさなどによって適宜決定される。例えば、ガスの流量は、１５０ミリリットル（ｍｌ）／分（ｓｃｃｍ）から６０００ミリリットル／分（ｓｃｃｍ）程度の範囲とされる。このとき、アンモニアガスの流量Ｂをシランガスの流量Ａで除した値（Ｂ／Ａ）は、０．５から１５の範囲とされる。 The antireflective layer 5 is formed, for example, using a PECVD method or a sputtering method. In the case of using the PECVD method, the semiconductor substrate 1 is previously heated to a temperature higher than the temperature during the formation of the antireflective layer 5. Thereafter, a mixed gas of silane (SiH 4 ) and ammonia (NH 3 ) is diluted with nitrogen (N 2 ) gas, and the reaction pressure is set to about 50 Pa to 200 Pa, and the one that has been plasmatized by glow discharge decomposition is It is deposited on the heated semiconductor substrate 1. Thus, the antireflective layer 5 is formed on the semiconductor substrate 1. At this time, the film forming temperature is set to about 350 ° C. to 650 ° C., and the preheating temperature of the semiconductor substrate 1 is set to about 50 ° C. higher than the film forming temperature. Also, a frequency of about 10 kHz to 500 kHz is adopted as the frequency of the high frequency power source required for the glow discharge. Further, the flow rate of the gas is appropriately determined depending on the size of the reaction chamber and the like. For example, the flow rate of the gas may be in the range of about 150 milliliters / minute (sccm) to about 6000 milliliters / minute (sccm). At this time, the value (B / A) obtained by dividing the flow rate B of the ammonia gas by the flow rate A of the silane gas is in the range of 0.5 to 15.
　次に、保護層６を形成する工程（第３工程ともいう）を実施する。第１実施形態では、少なくとも半導体基板１の第１面１ｂｓ側において、パッシベーション層４上に、孔部ＣＨ１を含むパターンを形成するように溶液を塗布してこの溶液を乾燥することで保護層６が形成される。このとき、溶液として、例えば、第１絶縁性ペーストおよび第２絶縁性ペーストが用いられることで、複数の凹状部分６ｐｒを有する保護層６が形成され得る。 Next, the step of forming the protective layer 6 (also referred to as a third step) is performed. In the first embodiment, the protective layer 6 is formed by applying a solution so as to form a pattern including the hole CH1 on the passivation layer 4 at least on the first surface 1 bs side of the semiconductor substrate 1 and drying the solution. Is formed. At this time, by using, for example, the first insulating paste and the second insulating paste as the solution, the protective layer 6 having the plurality of concave portions 6pr can be formed.
　このような保護層６は、例えば、次のような処理によって形成され得る。ここでは、まず、パッシベーション層４上に、第１絶縁性ペーストを塗布する。次に、パッシベーション層４上に塗布された第１絶縁性ペーストの層の上に、第２絶縁性ペーストを塗布する。次に、塗布後の第１絶縁性ペーストおよび第２絶縁性ペーストを、ホットプレートまたは乾燥炉などを用いて、最高温度が２００℃から３５０℃程度とされ、加熱時間が１分間から１０分間程度とされる条件で乾燥させる。このとき、図９で示されるように、第１絶縁性ペーストに由来する第１保護層領域６ａと、この第１保護層領域６ａ上に位置している第２絶縁性ペーストに由来する第２保護層領域６ｂと、を有する保護層６が形成される。ここでは、乾燥時における熱処理により、第２絶縁性ペーストが含有している有機フィラーが熱分解する。これにより、有機フィラーが熱分解によって消失した部分が凹状部分６ｐｒとなり、表面に複数の凹状部分６ｐｒを有する保護層６が形成される。 Such a protective layer 6 can be formed, for example, by the following process. Here, first, the first insulating paste is applied on the passivation layer 4. Next, a second insulating paste is applied on the layer of the first insulating paste applied on the passivation layer 4. Next, the maximum temperature of the first insulating paste and the second insulating paste after application is set to about 200 ° C. to 350 ° C. using a hot plate or a drying furnace, and the heating time is about 1 minute to 10 minutes. Dry under the conditions that are considered. At this time, as shown in FIG. 9, the first protective layer region 6a derived from the first insulating paste, and the second derived from the second insulating paste located on the first protective layer region 6a. And a protective layer region 6 b is formed. Here, the organic filler contained in the second insulating paste is thermally decomposed by the heat treatment at the time of drying. Thereby, the part which the organic filler lose | disappeared by thermal decomposition becomes concave part 6pr, and the protective layer 6 which has several concave part 6pr on the surface is formed.
　また、このような保護層６は、例えば、次のような処理によって形成されてもよい。ここでは、まず、パッシベーション層４上に、第１絶縁性ペーストを塗布する。次に、パッシベーション層４上に塗布された第１絶縁性ペーストの層の上に、第２絶縁性ペーストを塗布する。次に、塗布後の第１絶縁性ペーストおよび第２絶縁性ペーストを、ホットプレートまたは乾燥炉などを用いて、第２絶縁性ペーストが含有している有機フィラーが熱分解を生じない、比較的低温（例えば、１００℃程度）で乾燥させる。次に、有機溶剤を用いて、乾燥した第２絶縁性ペーストの表面に位置している有機フィラーを溶解させる。次に、ホットプレートまたは乾燥炉などを用いて、有機溶剤を蒸散させる乾燥処理を行う。これにより、表面に複数の凹状部分６ｐｒを有する保護層６が形成される。 Also, such a protective layer 6 may be formed, for example, by the following process. Here, first, the first insulating paste is applied on the passivation layer 4. Next, a second insulating paste is applied on the layer of the first insulating paste applied on the passivation layer 4. Next, the organic filler contained in the second insulating paste does not undergo thermal decomposition, using the first insulating paste and the second insulating paste after application, using a hot plate or a drying furnace, etc., relatively It is dried at a low temperature (for example, about 100 ° C.). Next, an organic solvent is used to dissolve the organic filler located on the surface of the dried second insulating paste. Next, a drying process of evaporating the organic solvent is performed using a hot plate, a drying furnace, or the like. Thereby, a protective layer 6 having a plurality of concave portions 6pr on the surface is formed.
　ここでは、例えば、スプレー法、コーター法またはスクリーン印刷法などを用いてパッシベーション層４上の少なくとも一部に上述した第１絶縁性ペーストおよび第２絶縁性ペーストを所望のパターンで塗布する。これにより、例えば、図８（ｅ）で示されるように、パッシベーション層４上の少なくとも一部に保護層６を形成する。 Here, the first insulating paste and the second insulating paste described above are applied in a desired pattern on at least a part of the passivation layer 4 using, for example, a spray method, a coater method, a screen printing method, or the like. Thereby, for example, as shown in FIG. 8E, the protective layer 6 is formed on at least a part of the passivation layer 4.
　次に、表面電極７および裏面電極８を含む電極を形成する工程（第４工程ともいう）を実施する。ここでは、例えば、保護層６上および孔部ＣＨ１内に電極形成用の材料を配してこの電極形成用の材料を加熱することで、裏面電極８を形成する。このとき形成される裏面電極８は、第２出力取出電極８ａと第２集電電極８ｂとを含む。第２集電電極８ｂは、電極層８ｂｌと接続部８ｂｃとを含む。 Next, a step of forming an electrode including the front surface electrode 7 and the back surface electrode 8 (also referred to as a fourth step) is performed. Here, for example, a material for electrode formation is disposed on the protective layer 6 and in the hole CH1, and the material for electrode formation is heated, whereby the back electrode 8 is formed. The back surface electrode 8 formed at this time includes the second output extraction electrode 8 a and the second current collection electrode 8 b. The second current collection electrode 8b includes an electrode layer 8bl and a connection portion 8bc.
　ここでは、例えば、図８（ｆ）で示されるように、表面電極７および裏面電極８が形成される。 Here, for example, as shown in FIG. 8F, the surface electrode 7 and the back surface electrode 8 are formed.
　表面電極７は、例えば、主成分として銀を含む金属粉末、有機ビヒクルおよびガラスフリットを含有する第２金属ペースト（銀ペーストともいう）を用いて作製する。まず、第２金属ペーストを、半導体基板１の第２面１ｆｓ側に塗布する。第１実施形態では、第２面１ｆｓ上のパッシベーション層４上に形成された反射防止層５上に、第２金属ペーストを塗布する。ここでは、第２金属ペーストの塗布は、例えば、スクリーン印刷などによって実現され得る。そして、第２金属ペーストの塗布後、所定の温度で第２金属ペースト中の溶剤を蒸散させて乾燥させてもよい。スクリーン印刷によって第２金属ペーストを塗布するのであれば、例えば、表面電極７に含まれる第１出力取出電極７ａ、第１集電電極７ｂおよび補助電極７ｃを１つの工程で形成することができる。その後、例えば、焼成炉内で最高温度が６００℃から８５０℃とされ、加熱時間が数十秒間から数十分間程度とされる条件で、第２金属ペーストを焼成することで表面電極７を形成する。 The surface electrode 7 is produced using, for example, a metal powder containing silver as a main component, an organic vehicle, and a second metal paste (also referred to as a silver paste) containing a glass frit. First, the second metal paste is applied to the second surface 1 fs side of the semiconductor substrate 1. In the first embodiment, the second metal paste is applied on the antireflection layer 5 formed on the passivation layer 4 on the second surface 1 fs. Here, the application of the second metal paste can be realized by, for example, screen printing. Then, after applying the second metal paste, the solvent in the second metal paste may be evaporated and dried at a predetermined temperature. If the second metal paste is applied by screen printing, for example, the first output extraction electrode 7a, the first current collection electrode 7b, and the auxiliary electrode 7c included in the surface electrode 7 can be formed in one step. Thereafter, for example, the surface metal 7 is fired by firing the second metal paste under the condition that the maximum temperature is set to 600 ° C. to 850 ° C. in the firing furnace and the heating time is set to about several tens seconds to several tens of minutes. Form.
　裏面電極８に含まれる第２出力取出電極８ａは、例えば、主成分として銀を含む金属粉末、有機ビヒクルおよびガラスフリットなどを含有する第３金属ペースト（銀ペーストともいう）を用いて作製する。半導体基板１へ第３金属ペーストを塗布する方法としては、例えば、スクリーン印刷法などを用いることができる。第３金属ペーストの塗布後、所定の温度で第３金属ペースト中の溶剤を蒸散させて乾燥してもよい。その後、焼成炉内で最高温度が６００℃から８５０℃とされ、加熱時間が数十秒間から数十分間程度とされる条件で、第３金属ペーストを焼成することで、第２出力取出電極８ａが半導体基板１の第１面１ｂｓ側に形成される。 The second output lead-out electrode 8a included in the back surface electrode 8 is manufactured using, for example, a third metal paste (also referred to as silver paste) containing a metal powder containing silver as a main component, an organic vehicle, a glass frit and the like. As a method of applying the third metal paste to the semiconductor substrate 1, for example, a screen printing method can be used. After application of the third metal paste, the solvent in the third metal paste may be evaporated and dried at a predetermined temperature. Then, the second output extraction electrode is fired by firing the third metal paste under the condition that the maximum temperature is set to 600 ° C. to 850 ° C. in the firing furnace and the heating time is set to about several tens of seconds to several tens of minutes. 8 a is formed on the first surface 1 bs side of the semiconductor substrate 1.
　裏面電極８に含まれる第２集電電極８ｂは、例えば、主成分としてアルミニウムを含む金属粉末、有機ビヒクルおよびガラスフリットを含有する第１金属ペースト（Ａｌペースト）を用いて作製する。まず、第１金属ペーストを、予め塗布された第３金属ペーストの一部と接触するように、半導体基板１の第１面１ｂｓ側に塗布する。第１実施形態では、第１面１ｂｓ上のパッシベーション層４上に形成された保護層６上および孔部ＣＨ１内に、第１金属ペーストを塗布する。このとき、第２出力取出電極８ａが形成される部位の一部を除いて、半導体基板１の第１面１ｂｓ側のほぼ全面に第１金属ペーストを塗布してもよい。ここでは、第１金属ペーストの塗布は、例えば、スクリーン印刷などによって実現され得る。また、このとき、第１金属ペーストは、保護層６の複数の凹状部分６ｐｒの内部空間ＳＣ１にも入り込む。 The second current collection electrode 8b included in the back surface electrode 8 is produced, for example, using a first metal paste (Al paste) containing a metal powder containing aluminum as a main component, an organic vehicle and a glass frit. First, the first metal paste is applied to the first surface 1 bs side of the semiconductor substrate 1 so as to be in contact with a part of the previously applied third metal paste. In the first embodiment, the first metal paste is applied on the protective layer 6 formed on the passivation layer 4 on the first surface 1 bs and in the hole CH1. At this time, the first metal paste may be applied to almost the entire surface on the first surface 1 bs side of the semiconductor substrate 1 except for a part of the portion where the second output lead-out electrode 8 a is formed. Here, the application of the first metal paste can be realized by, for example, screen printing. Further, at this time, the first metal paste also intrudes into the internal space SC1 of the plurality of concave portions 6pr of the protective layer 6.
　ここで、第１金属ペーストの塗布後、所定の温度で第１金属ペースト内の溶剤を蒸散させて乾燥させてもよい。その後、例えば、焼成炉内において最高温度が６００℃から８５０℃とされ、加熱時間が数十秒間から数十分間程度とされる条件で第１金属ペーストを焼成することで、第２集電電極８ｂが半導体基板１の第１面１ｂｓ側に形成される。このとき、保護層６の複数の凹状部分６ｐｒの内部空間ＳＣ１には、第２集電電極８ｂのガラスを含む電極成分が入り込んだ状態となる。また、このとき、孔部ＣＨ１内において、第１金属ペーストは、焼成される際にパッシベーション層４をファイヤースルーして、第１半導体層２と電気的に接続する。これにより、第２集電電極８ｂが形成される。また、このとき、第２集電電極８ｂの形成に伴い、第３半導体層２ｂｓも形成される。ただし、このとき、保護層６上にある第１金属ペーストは、保護層６でブロックされる。このため、第１金属ペーストが焼成される際には、保護層６でブロックされたパッシベーション層４へは焼成による悪影響がほとんど及ばない。 Here, after the application of the first metal paste, the solvent in the first metal paste may be evaporated and dried at a predetermined temperature. After that, for example, the second current collection is performed by firing the first metal paste under the condition that the maximum temperature is set to 600 ° C. to 850 ° C. in the firing furnace and the heating time is about several tens seconds to several tens of minutes. The electrode 8 b is formed on the first surface 1 bs side of the semiconductor substrate 1. At this time, an electrode component including the glass of the second current collection electrode 8b enters the internal space SC1 of the plurality of concave portions 6pr of the protective layer 6. Further, at this time, in the hole portion CH1, the first metal paste fires through the passivation layer 4 when it is fired, and is electrically connected to the first semiconductor layer 2. Thereby, the second current collection electrode 8b is formed. At this time, the third semiconductor layer 2bs is also formed along with the formation of the second current collection electrode 8b. However, at this time, the first metal paste on the protective layer 6 is blocked by the protective layer 6. Therefore, when the first metal paste is fired, the passivation layer 4 blocked by the protective layer 6 is hardly affected by the firing.
　このようにして、裏面電極８が形成され得る。このため、第１実施形態では、裏面電極８を形成するための電極形成用の材料として、第１金属ペーストおよび第３金属ペーストが採用される。ここでは、例えば、第２集電電極８ｂを形成した後に第２出力取出電極８ａを形成してもよい。第２出力取出電極８ａは、例えば、半導体基板１と直接接触していても、第２出力取出電極８ａと半導体基板１との間にパッシベーション層４が存在するなどして、半導体基板１と直接接触していなくてもよい。また、第２出力取出電極８ａは保護層６の上に位置するように形成されてもよい。また、表面電極７および裏面電極８は、各々の金属ペーストを塗布した後に、同時に焼成を施すことで形成してもよい。これにより、太陽電池素子１０の生産性が向上し得る。また、この場合、半導体基板１に施される熱履歴が低減されるため、太陽電池素子１０の出力特性が向上し得る。 Thus, the back electrode 8 can be formed. For this reason, in the first embodiment, the first metal paste and the third metal paste are employed as the material for forming the back electrode 8. Here, for example, the second output lead-out electrode 8a may be formed after the second current collection electrode 8b is formed. Even when the second output lead-out electrode 8a is in direct contact with the semiconductor substrate 1, for example, the passivation layer 4 is present between the second output lead-out electrode 8a and the semiconductor substrate 1, It does not have to be in contact. Further, the second output lead electrode 8 a may be formed on the protective layer 6. Further, the surface electrode 7 and the back surface electrode 8 may be formed by applying baking after simultaneously applying each metal paste. Thereby, the productivity of the solar cell element 10 can be improved. Further, in this case, the heat history applied to the semiconductor substrate 1 is reduced, so that the output characteristics of the solar cell element 10 can be improved.
　　＜１－６．第１実施形態のまとめ＞
　第１実施形態に係る太陽電池素子１０では、例えば、保護層６の凸状部６ｐに存在している凹状部分６ｐｒに第２集電電極８ｂの電極層８ｂｌを構成している状態にあるガラス成分を含む電極成分が位置している。このような構成が採用されれば、例えば、保護層６上に第１金属ペーストを塗布して第２集電電極８ｂを形成する際に、保護層６の表面に凹凸構造が存在していても、凸状部６ｐに存在している凹状部分６ｐｒに、第１金属ペースト中のガラス成分などが入り込む。このため、例えば、凸状部６ｐ上に位置している第１金属ペーストにおいて、ガラス成分および有機ビヒクルなどを含む流動性を有する成分が重力方向においてより低い部分へ流出しにくい。これにより、凸状部６ｐ上に位置している第１金属ペーストにおいて、ガラス成分の含有量が減少しにくい。その結果、第２集電電極８ｂを形成する際に、保護層６上に塗布される第１金属ペーストの成分の分布に偏りが生じにくい。このとき、例えば、保護層６上における第２集電電極８ｂの密着性に偏りが生じにくい。そして、凹状部分６ｐｒではガラス成分の存在によって、凸状部６ｐにおいて保護層６と第２集電電極８ｂ中の金属粒子との間で密着性が向上し得る。また、例えば、第２集電電極８ｂの一部が保護層６の凹状部分６ｐｒに入り込むことで、いわゆるアンカー効果が生じ得る。これにより、保護層６に対する第２集電電極８ｂの密着性が向上し得る。その結果、例えば、保護層６からの第２集電電極８ｂの部分的な剥離が生じにくい。したがって、ＰＥＲＣ型の太陽電池素子１０における光電変換効率が向上し得る。 <1-6. Summary of First Embodiment>
In the solar cell element 10 according to the first embodiment, for example, the glass in a state in which the electrode layer 8 bl of the second current collection electrode 8 b is formed in the concave portion 6 pr existing in the convex portion 6 p of the protective layer 6 An electrode component comprising the component is located. If such a configuration is adopted, for example, when the first metal paste is applied on the protective layer 6 to form the second current collecting electrode 8 b, the uneven structure exists on the surface of the protective layer 6. Also, the glass component or the like in the first metal paste intrudes into the concave portion 6pr present in the convex portion 6p. For this reason, for example, in the first metal paste located on the convex portion 6p, it is difficult for the fluid component including the glass component and the organic vehicle to flow out to a lower part in the gravity direction. Thereby, in the 1st metal paste located on convex-shaped part 6p, content of a glass component does not reduce easily. As a result, when the second current collection electrode 8 b is formed, the distribution of the components of the first metal paste applied on the protective layer 6 is less likely to be biased. At this time, for example, the adhesion of the second current collection electrode 8b on the protective layer 6 is unlikely to be uneven. Then, in the concave portion 6pr, the adhesion between the protective layer 6 and the metal particles in the second current collection electrode 8b can be improved in the convex portion 6p due to the presence of the glass component. In addition, for example, when a part of the second current collection electrode 8b enters the concave portion 6pr of the protective layer 6, a so-called anchor effect may occur. Thereby, the adhesion of the second current collection electrode 8 b to the protective layer 6 can be improved. As a result, for example, partial peeling of the second current collection electrode 8 b from the protective layer 6 does not easily occur. Therefore, the photoelectric conversion efficiency in the PERC solar cell element 10 can be improved.
　＜２．他の実施形態＞
　本開示は上述の第１実施形態に限定されるものではなく、本開示の要旨を逸脱しない範囲において種々の変更、改良などが可能である。 <2. Other Embodiments>
The present disclosure is not limited to the above-described first embodiment, and various changes, improvements, and the like can be made without departing from the scope of the present disclosure.
　　＜２－１．第２実施形態＞
　上記第１実施形態において、例えば、図１０（ａ）および図１０（ｂ）で示されるように、保護層６は、この保護層６の内部に位置している複数の空隙部６ｖｄを有していてもよい。ここで、空隙部６ｖｄの径をｄ４とする。この場合に、例えば、径ｄ４が、隣り合う凸状部６ｐ同士の第２距離Ｄ２および隣り合う接続部８ｂｃ同士の第３距離Ｄ３の何れよりも短い形態が考えられる。具体的には、空隙部６ｖｄとしては、例えば、０．１μｍから１μｍ程度の径ｄ４の内部空間を有する微小な空隙部が採用される。また、ここで、例えば、保護層６のうちの凹状部分６ｐｒおよび空隙部６ｖｄが存在している部分において、空隙部６ｖｄを除いた保護層６の厚さ（最小膜厚）が、０．５μｍ以上程度であれば、保護層６によってパッシベーション層４を保護する機能が確保され得る。 <2-1. Second embodiment>
In the first embodiment, for example, as shown in FIGS. 10 (a) and 10 (b), the protective layer 6 has a plurality of air gaps 6vd located inside the protective layer 6. It may be Here, the diameter of the void 6vd is d4. In this case, for example, a mode in which the diameter d4 is shorter than any one of the second distance D2 between adjacent convex portions 6p and the third distance D3 between adjacent connection portions 8bc may be considered. Specifically, as the air gap 6vd, for example, a minute air gap having an internal space of a diameter d4 of about 0.1 μm to 1 μm is adopted. Furthermore, here, for example, in the portion where the concave portion 6pr and the void 6vd of the protective layer 6 exist, the thickness (minimum film thickness) of the protective layer 6 excluding the void 6vd is 0.5 μm. If it is about above, the function which protects passivation layer 4 by protective layer 6 may be secured.
　ところで、例えば、保護層６の形成時および太陽電池素子１０の使用時に、保護層６が温度変化に応じた膨張または収縮を生じ、保護層６の縮合重合の反応に応じた収縮を生じる場合がある。このとき、保護層６とこの保護層６に隣接している状態にある層（隣接層ともいう）との間に応力が生じ得る。これに対して、例えば、保護層６の内部に複数の空隙部６ｖｄが位置してれば、保護層６とこの保護層６に隣接している状態にある隣接層との間において生じる応力が、保護層６内の複数の空隙部６ｖｄによって緩和され得る。これにより、保護層６とこの保護層６に隣接している状態にある隣接層との間で、剥離が生じにくい。その結果、ＰＥＲＣ型の太陽電池素子１０における光電変換効率が向上し得る。 By the way, for example, when the protective layer 6 is formed and when the solar cell element 10 is used, the protective layer 6 may expand or contract according to the temperature change, and may cause contraction according to the condensation polymerization reaction of the protective layer 6 is there. At this time, stress may be generated between the protective layer 6 and a layer adjacent to the protective layer 6 (also referred to as an adjacent layer). On the other hand, for example, if a plurality of air gaps 6vd are located inside the protective layer 6, stress generated between the protective layer 6 and an adjacent layer in a state adjacent to the protective layer 6 occurs. , And may be relieved by the plurality of air gaps 6 vd in the protective layer 6. As a result, peeling does not easily occur between the protective layer 6 and the adjacent layer in a state adjacent to the protective layer 6. As a result, the photoelectric conversion efficiency in the PERC solar cell element 10 can be improved.
　また、ここで、例えば、複数の空隙部６ｖｄのうちの隣り合う空隙部６ｖｄ同士の距離（第４距離ともいう）をＤ４とする。第４距離Ｄ４としては、例えば、隣り合う空隙部６ｖｄ同士の中心間の距離が採用される。この第４距離Ｄ４は、例えば、隣り合う空隙部６ｖｄ同士の中心間の距離の平均値であってもよいし、隣り合う空隙部６ｖｄの離間距離であってもよいし、隣り合う空隙部６ｖｄの離間距離の平均値であってもよい。この場合に、例えば、第４距離Ｄ４が、隣り合う凸状部６ｐ同士の第２距離Ｄ２および隣り合う接続部８ｂｃ同士の第３距離Ｄ３の何れよりも短い形態が考えられる。このとき、例えば、保護層６における複数の空隙部６ｖｄの密度がある程度高い。これにより、例えば、保護層６とこの保護層６に隣接している状態にある隣接層との間において生じる応力が、保護層６内の複数の空隙部６ｖｄによって緩和されやすい。このため、ＰＥＲＣ型の太陽電池素子１０における光電変換効率が向上しやすい。 Also, here, for example, the distance (also referred to as a fourth distance) between adjacent gap portions 6 vd among the plurality of void portions 6 vd is set to D4. As the fourth distance D4, for example, the distance between the centers of the adjacent air gaps 6vd is adopted. The fourth distance D4 may be, for example, the average value of the distance between the centers of the adjacent void portions 6vd, or the separation distance between the adjacent void portions 6vd, or the adjacent void portions 6vd. The average value of the separation distances of In this case, for example, it is conceivable that the fourth distance D4 is shorter than any one of the second distance D2 between adjacent convex portions 6p and the third distance D3 between adjacent connection portions 8bc. At this time, for example, the density of the plurality of air gaps 6 vd in the protective layer 6 is somewhat high. Thereby, for example, the stress generated between the protective layer 6 and the adjacent layer in a state adjacent to the protective layer 6 is easily relaxed by the plurality of voids 6 vd in the protective layer 6. For this reason, the photoelectric conversion efficiency in the PERC solar cell element 10 can be easily improved.
　内部に複数の空隙部６ｖｄを有する保護層６は、例えば、次のような処理によって形成され得る。 The protective layer 6 having the plurality of voids 6 vd inside can be formed, for example, by the following process.
　ここでは、まず、パッシベーション層４上に、第１絶縁性ペーストを塗布する。次に、パッシベーション層４上に塗布された第１絶縁性ペーストの層の上に、第２絶縁性ペーストを塗布する。次に、第１絶縁性ペーストの層の上に塗布された第２絶縁性ペーストの層の上に、第１絶縁性ペーストを塗布する。次に、第２絶縁性ペーストの層の上に塗布された第１絶縁性ペーストの層の上に、第２絶縁性ペーストを塗布する。そして、塗布後の第１絶縁性ペーストの層、第２絶縁性ペーストの層、第１絶縁性ペーストの層および第２絶縁性ペーストの層を、ホットプレートまたは乾燥炉などを用いて乾燥させる。このとき、乾燥の条件として、第２絶縁性ペーストに含まれている有機フィラーが熱分解される２００℃から３５０℃程度の最高温度と、１分間から１０分間程度の加熱時間と、が採用される。このとき、図１１で示されるように、パッシベーション層４の上に、第１保護層領域６ａと、第２保護層領域６ｂと、第３保護層領域６ｃと、第４保護層領域６ｄと、がこの記載の順に積層している状態で位置している保護層６が形成される。ここでは、第１保護層領域６ａおよび第３保護層領域６ｃは、第１絶縁性ペーストの乾燥によって形成される。第２保護層領域６ｂおよび第４保護層領域６ｄは、第２絶縁性ペーストの乾燥によって形成される。そして、このとき、乾燥時における熱処理により、第２絶縁性ペーストが含有する有機フィラーが熱分解する。これにより、第２保護層領域６ｂにおいて有機フィラーの消失によって複数の空隙部６ｖｄが形成され、第４保護層領域６ｄの表面において有機フィラーの消失によって複数の凹状部分６ｐｒが形成される。その結果、表面に複数の凹状部分６ｐｒを有し且つ内部に複数の空隙部６ｖｄを有する保護層６が形成され得る。 Here, first, the first insulating paste is applied on the passivation layer 4. Next, a second insulating paste is applied on the layer of the first insulating paste applied on the passivation layer 4. Next, the first insulating paste is applied on the layer of the second insulating paste applied on the layer of the first insulating paste. Next, the second insulating paste is applied on the layer of the first insulating paste applied on the layer of the second insulating paste. Then, the layer of the first insulating paste, the layer of the second insulating paste, the layer of the first insulating paste, and the layer of the second insulating paste after application are dried using a hot plate or a drying furnace. At this time, as the drying conditions, a maximum temperature of about 200 ° C. to 350 ° C. at which the organic filler contained in the second insulating paste is thermally decomposed, and a heating time of about 1 minute to 10 minutes are adopted. Ru. At this time, as shown in FIG. 11, on the passivation layer 4, a first protective layer area 6a, a second protective layer area 6b, a third protective layer area 6c, and a fourth protective layer area 6d, Is formed in the state of being stacked in the order of this description. Here, the first protective layer region 6a and the third protective layer region 6c are formed by drying the first insulating paste. The second protective layer region 6b and the fourth protective layer region 6d are formed by drying the second insulating paste. At this time, the organic filler contained in the second insulating paste is thermally decomposed by the heat treatment at the time of drying. Thereby, a plurality of void portions 6vd are formed in the second protective layer region 6b by the disappearance of the organic filler, and a plurality of concave portions 6pr are formed in the surface of the fourth protective layer region 6d by the disappearance of the organic filler. As a result, a protective layer 6 having a plurality of concave portions 6pr on the surface and a plurality of voids 6vd on the inside can be formed.
　ここで、例えば、図１１の第２保護層領域６ｂを形成するための第２絶縁性ペーストの層の代わりに、第１絶縁性ペーストに有機バインダを含有させた層が塗布されてもよい。この場合には、例えば、第１絶縁性ペーストを乾燥させる際に、第１絶縁性ペーストの層に存在している有機バインダのうちの一部の有機バインダにおける揮発によって、複数の空隙部６ｖｄが生じ得る。また、ここで、図１１の第４保護層領域６ｄおよび図９の第２保護層領域６ｂの少なくとも一方を形成するための第２絶縁性ペーストの層の代わりに、第１絶縁性ペーストに有機バインダを含有させた層が塗布されてもよい。この場合には、例えば、第１絶縁性ペーストを乾燥させる際に、第１絶縁性ペーストの層に存在している有機バインダのうちの一部の有機バインダにおける揮発によって、複数の凹状部分６ｐｒが生じ得る。 Here, for example, instead of the layer of the second insulating paste for forming the second protective layer region 6b of FIG. 11, a layer in which an organic binder is contained in the first insulating paste may be applied. In this case, for example, when drying the first insulating paste, the plurality of void portions 6vd are formed by volatilization of a part of the organic binders among the organic binders present in the layer of the first insulating paste. It can occur. Further, here, instead of the layer of the second insulating paste for forming at least one of the fourth protective layer region 6d of FIG. 11 and the second protective layer region 6b of FIG. A layer containing a binder may be applied. In this case, for example, when the first insulating paste is dried, the plurality of concave portions 6pr are formed by volatilization of a part of the organic binder among the organic binders present in the layer of the first insulating paste. It can occur.
　　＜２－２．第３実施形態＞
　上記各実施形態において、例えば、図１２で示されるように、第２集電電極８ｂの電極層８ｂｌ側から保護層６を平面透視した場合に、保護層６が、凹状部分６ｐｒの単位面積当たりの数が異なる、第１領域Ａｒ１と第２領域Ａｒ２とを有していてもよい。ここでは、第１領域Ａｒ１は、太陽電池素子１０の外周部ＯＰ１側に位置している。第２領域Ａｒ２は、太陽電池素子１０の中央部ＣＰ１側に位置している。単位面積は、例えば、１００ｍｍ２から４００ｍｍ２程度に設定される。そして、第１領域Ａｒ１に存在している凹状部分６ｐｒの単位面積当たりの数が、第２領域Ａｒ２に存在している凹状部分６ｐｒの単位面積当たりの数よりも多くてもよい。このような構成が採用されると、例えば、太陽電池素子１０の裏面１０ｂｓ側において、中央部ＣＰ１側の部分よりも外周部ＯＰ１側の部分において、保護層６と第２集電電極８ｂとの密着性が高くなる。 <2-2. Third embodiment>
In each of the above embodiments, for example, as shown in FIG. 12, when the protective layer 6 is seen through from the electrode layer 8bl side of the second current collection electrode 8b, the protective layer 6 is per unit area of the concave portion 6pr. The first region Ar1 and the second region Ar2 may have different numbers. Here, the first region Ar1 is located on the outer peripheral portion OP1 side of the solar cell element 10. The second region Ar2 is located on the central portion CP1 side of the solar cell element 10. The unit area is set to, for example, about 100 mm 2 to 400 mm 2 . The number per unit area of concave portions 6pr present in the first region Ar1 may be larger than the number per unit area of concave portions 6pr present in the second region Ar2. When such a configuration is employed, for example, on the back surface 10bs side of the solar cell element 10, the protective layer 6 and the second current collection electrode 8b in the portion on the outer peripheral portion OP1 side than the portion on the central portion CP1 side. Adhesion becomes high.
　このような第１領域Ａｒ１と第２領域Ａｒ２とを有する保護層６は、例えば、パッシベーション層４上に塗布された第１絶縁性ペーストの層の上に第２絶縁性ペーストを塗布する際に次のような処理を行うことで、形成され得る。まず、第１領域Ａｒ１に対応する領域に、第２絶縁性ペーストを塗布する。次に、既に塗布された第２絶縁性ペーストよりも有機フィラーの含有率が低い第２絶縁性ペーストを、第２領域Ａｒ２に対応する領域に塗布する。また、例えば、このような処理は、パッシベーション層４上に塗布された第１絶縁性ペーストの層の上に第２絶縁性ペーストを塗布して、第１絶縁性ペーストおよび第２絶縁性ペーストを乾燥させた後に、さらに第２絶縁性ペーストの層の上に塗布された第１絶縁性ペーストの層の上に第２絶縁性ペーストを塗布する際に行ってもよい。これにより、複数の空隙部６ｖｄを有するとともに、第１領域Ａｒ１と第２領域Ａｒ２とを有する保護層６が形成され得る。 The protective layer 6 having the first area Ar1 and the second area Ar2 may be formed, for example, when the second insulating paste is applied on the layer of the first insulating paste applied on the passivation layer 4. It can be formed by performing the following process. First, the second insulating paste is applied to a region corresponding to the first region Ar1. Next, a second insulating paste having a lower organic filler content than the already applied second insulating paste is applied to the area corresponding to the second area Ar2. Also, for example, in such a process, the second insulating paste is applied on the layer of the first insulating paste applied on the passivation layer 4 to form the first insulating paste and the second insulating paste. The drying may be performed when the second insulating paste is applied on the layer of the first insulating paste further applied on the layer of the second insulating paste. Thus, the protective layer 6 having the plurality of void portions 6vd and the first region Ar1 and the second region Ar2 can be formed.
　ところで、例えば、図１３および図１４で示されるように、複数の太陽電池素子１０は、配線材Ｔｂで電気的に直列に接続され且つ平面的に並んだ状態で位置している太陽電池モジュール１００の形態で使用され得る。この太陽電池モジュール１００では、相互に対向している状態で位置している第１保護部材１０１と第２保護部材１０４との間隙において、封止材１０２で覆われている状態で複数の太陽電池素子１０を含む部分（光電変換部ともいう）１０３が位置している。ここでは、太陽電池モジュール１００は、主として光を受光する面（前面ともいう）１００ｆｓと、前面１００ｆｓとは逆側に位置している面（裏面ともいう）１００ｂｓと、を有する。そして、太陽電池モジュール１００では、前面１００ｆｓ側に透光性を有する板状の第２保護部材１０４が位置し、裏面１００ｂｓ側に板状あるいはシート状の第１保護部材１０１が位置している。また、第１保護部材１０１と第２保護部材１０４との間隙に位置している封止材１０２は、裏面１００ｂｓ側に位置している第１封止材１０２ｂと、前面１００ｆｓ側に位置している第２封止材１０２ｕと、を含む。 By the way, for example, as shown in FIG. 13 and FIG. 14, the solar cell modules 100 are positioned in a state in which the plurality of solar cell elements 10 are electrically connected in series by the wiring member Tb and aligned in a plane. Can be used in the form of In this solar cell module 100, a plurality of solar cell modules are covered with the sealing material 102 in the gap between the first protective member 101 and the second protective member 104 located in a state of facing each other. A portion (also referred to as a photoelectric conversion portion) 103 including the element 10 is located. Here, the solar cell module 100 has a surface (also referred to as a front surface) 100 fs that mainly receives light, and a surface (also referred to as a back surface) 100 bs that is located on the opposite side of the front surface 100 fs. In the solar cell module 100, the light transmitting plate-like second protection member 104 is positioned on the front surface 100 fs side, and the plate-like or sheet-like first protection member 101 is positioned on the back surface 100 bs. Also, the sealing material 102 located in the gap between the first protective member 101 and the second protective member 104 is located on the front surface 100 fs side with the first sealing material 102 b located on the back surface 100 bs side. And a second sealing material 102u.
　この太陽電池モジュール１００は、例えば、図１５で示されるように、第１保護部材１０１と、第１シートＳＨ１と、光電変換部１０３と、第２シートＳＨ２と、第２保護部材１０４と、がこの記載の順に積層された積層体が、ラミネート処理で一体化されることで製造され得る。第１シートＳＨ１は、第１封止材１０２ｂのもととなるシート状の素材であり、第２シートＳＨ２は、第２封止材１０２ｕのもととなるシート状の素材である。ここで、積層体のラミネート処理が行われる際には、複数の太陽電池素子１０同士の間において、封止材１０２の厚さが大きい。このため、複数の太陽電池素子１０同士の間において封止材１０２の膨張および収縮が大きくなる。これにより、ラミネート処理が行われる際には、例えば、太陽電池素子１０の裏面１０ｂｓ側では、この裏面１０ｂｓの外周部ＯＰ１に沿った領域に大きな応力が加わり得る。これに対して、第３実施形態に係る太陽電池素子１０の裏面１０ｂｓ側では、中央部ＣＰ１側の第２領域Ａｒ２よりも外周部ＯＰ１側の第１領域Ａｒ１において、保護層６と第２集電電極８ｂとの密着性が高い。このため、例えば、積層体のラミネート処理が行われる際に、保護層６から第２集電電極８ｂが剥離しにくい。 For example, as shown in FIG. 15, this solar cell module 100 includes a first protective member 101, a first sheet SH1, a photoelectric conversion unit 103, a second sheet SH2, and a second protective member 104. The laminated body laminated | stacked in order of this description may be manufactured by integrating by lamination process. The first sheet SH1 is a sheet-like material that is the source of the first sealing material 102b, and the second sheet SH2 is a sheet-like material that is the source of the second sealing material 102u. Here, when lamination processing of a laminated body is performed, the thickness of the sealing material 102 is large between several solar cell elements 10 comrades. For this reason, expansion and contraction of the sealing material 102 become large between the plurality of solar cell elements 10. Thereby, when lamination processing is performed, for example, on the back surface 10 bs side of the solar cell element 10, a large stress may be applied to a region along the outer peripheral portion OP1 of the back surface 10 bs. On the other hand, on the back surface 10bs side of the solar cell element 10 according to the third embodiment, the protective layer 6 and the second collection are formed in the first region Ar1 on the outer peripheral portion OP1 side than the second region Ar2 on the central portion CP1 side. The adhesion to the electrode 8 b is high. For this reason, for example, when the lamination process of a laminated body is performed, it is hard to peel off the 2nd current collection electrode 8b from the protective layer 6. As shown in FIG.
　　＜２－３．その他＞
　上記各実施形態および各種変形例において、例えば、保護層６の上に位置している第２出力取出電極８ａがガラス成分を含む電極層であってもよい。この場合、保護層６の凹状部分６ｐｒの内部空間に、第２出力取出電極８ａのガラス成分が位置していてもよい。これにより、保護層６に対する第２出力取出電極８ａの密着性を向上させることで、太陽電池素子１０における光電変換効率を向上させてもよい。 <2-3. Other>
In each of the above-described embodiments and various modifications, for example, the second output lead-out electrode 8 a located on the protective layer 6 may be an electrode layer containing a glass component. In this case, the glass component of the second output extraction electrode 8 a may be located in the internal space of the concave portion 6 pr of the protective layer 6. Thereby, by improving the adhesion of the second output lead electrode 8 a to the protective layer 6, the photoelectric conversion efficiency in the solar cell element 10 may be improved.
　上記各実施形態および上記各種変形例において、保護層６の電極層８ｂｌ側の面を平面視した場合に、凸状部６ｐにおける単位面積の領域を凹状部分６ｐｒが占める割合は、５％から４０％程度に限られない。この割合は、例えば、第２集電電極８ｂまたはこの第２集電電極８ｂを形成するための第１金属ペーストにおける、ガラス成分の含有量およびガラス成分の種類などに応じて、適宜設定されれば、保護層６に対する第２集電電極８ｂの密着性が向上しやすくなる。換言すれば、例えば、この割合は、５％から４０％程度の範囲のうちの一部もしくは全部を含む異なる割合の範囲あるいは５％から４０％程度とは異なる割合の範囲に適宜設定されてもよい。 In each of the above-described embodiments and the above-described various modifications, when the surface of the protective layer 6 on the electrode layer 8bl side is viewed in plan, the ratio of the concave portion 6pr to the area of the unit area in the convex portion 6p is 5% to 40. It is not limited to about%. This ratio is appropriately set according to, for example, the content of the glass component and the type of the glass component in the second current collection electrode 8 b or the first metal paste for forming the second current collection electrode 8 b. For example, the adhesion of the second current collection electrode 8b to the protective layer 6 can be easily improved. In other words, for example, even if this ratio is appropriately set to a range of a different ratio including a part or all of the range of about 5% to 40% or a range of a ratio different from about 5% to about 40% Good.
　上記各実施形態および上記各種変形例では、例えば、図１６（ａ）で示されるように、パッシベーション層４が、第１面１ｂｓ上から第３面１ｓｓ上にかけて位置し、保護層６が、第１面１ｂｓの外縁部Ｅｄ１上に位置しているパッシベーション層４上に位置していたが、これに限られない。例えば、図１６（ｂ）で示されるように、第１面１ｂｓのうちの第１面１ｂｓの外縁部Ｅｄ１に沿った領域（外縁領域ともいう）Ａｏ１上には、パッシベーション層４および保護層６ならびに反射防止層５が位置していなくてもよい。換言すれば、第３面１ｓｓ上に位置しているパッシベーション層４および反射防止層５と、第１面１ｂｓ上に位置しているパッシベーション層４および保護層６と、が外周領域Ａｏ１上で離れていてもよい。このとき、外縁領域Ａｏ１は、第１面１ｂｓのうちの外縁部Ｅｄ１から距離Ｌ１の範囲に位置している形態が考えられる。距離Ｌ１は、例えば、０．５ｍｍから２ｍｍ程度とされ得る。このような構成が採用される場合には、例えば、図１６（ｂ）で示されるように、第１面１ｂｓの外縁領域Ａｏ１上に第２集電電極８ｂが位置していなくてもよいし、図１６（ｃ）で示されるように、第１面１ｂｓの外縁領域Ａｏ１の少なくとも一部の上に第２集電電極８ｂが位置していてもよい。また、ここで、例えば、図１７（ａ）から図１７（ｃ）で示されるように、第３面１ｓｓ上から第１面１ｂｓの外縁領域Ａｏ１のうちの外縁部Ｅｄ１の側の部分の上にかけて、パッシベーション層４および反射防止膜５が位置していてもよい。このとき、外縁領域Ａｏ１上において、パッシベーション層４および反射防止膜５が、外縁部Ｅｄ１から距離Ｌ２の範囲に位置している形態が考えられる。距離Ｌ２は、例えば、０．１ｍｍから１ｍｍ程度とされ得る。このような構成が採用される場合には、例えば、図１７（ａ）および図１７（ｂ）で示されるように、第３面１ｓｓ上から第１面１ｂｓの外縁領域Ａｏ１上にかけて、パッシベーション層４よりも反射防止層５の方が、第１面１ｂｓの中央部に近い部分まで位置していてもよい。また、例えば、図１７（ｃ）で示されるように、外縁領域Ａｏ１上のうちの外縁部Ｅｄ１から距離Ｌ２の部分まで、パッシベーション層４および反射防止膜５の両方が位置していてもよい。なお、図１７（ｃ）で示される例においても、図１６（ｃ）または図１７（ｂ）で示されるように、第１面１ｂｓの外縁領域Ａｏ１の少なくとも一部の上に第２集電電極８ｂが位置していてもよい。 In each of the above embodiments and the above various modifications, for example, as shown in FIG. 16A, the passivation layer 4 is positioned from the top of the first surface 1 bs to the top of the third surface 1 ss, and the protective layer 6 is Although it has been located on the passivation layer 4 located on the outer edge Ed1 of the surface 1bs, it is not limited thereto. For example, as shown in FIG. 16B, on the region (also referred to as the outer edge region) Ao1 along the outer edge Ed1 of the first surface 1bs of the first surface 1bs, the passivation layer 4 and the protective layer 6 Also, the antireflective layer 5 may not be located. In other words, the passivation layer 4 and the antireflective layer 5 located on the third surface 1ss and the passivation layer 4 and the protective layer 6 located on the first surface 1bs are separated on the outer peripheral area Ao1. It may be At this time, it is conceivable that the outer edge area Ao1 is located in the range of the distance L1 from the outer edge Ed1 of the first surface 1bs. The distance L1 may be, for example, about 0.5 mm to 2 mm. When such a configuration is adopted, for example, as shown in FIG. 16B, the second current collection electrode 8b may not be located on the outer edge area Ao1 of the first surface 1bs. As shown in FIG. 16C, the second current collection electrode 8b may be located on at least a part of the outer edge area Ao1 of the first surface 1bs. In addition, here, for example, as shown in FIGS. 17A to 17C, the third surface 1ss to the upper surface of a portion on the outer edge portion Ed1 of the outer edge region Ao1 of the first surface 1bs. Passivation layer 4 and anti-reflective film 5 may be located. At this time, it is conceivable that the passivation layer 4 and the anti-reflection film 5 are located in the range of the distance L2 from the outer edge portion Ed1 on the outer edge region Ao1. The distance L2 may be, for example, about 0.1 mm to 1 mm. When such a configuration is employed, for example, as shown in FIGS. 17A and 17B, a passivation layer is formed from the third surface 1ss to the outer surface area Ao1 of the first surface 1bs. The anti-reflection layer 5 may be positioned to a portion closer to the central portion of the first surface 1 bs than 4. Further, for example, as shown in FIG. 17C, both the passivation layer 4 and the anti-reflection film 5 may be located from the outer edge portion Ed1 to the portion of the distance L2 on the outer edge region Ao1. Also in the example shown in FIG. 17 (c), as shown in FIG. 16 (c) or FIG. 17 (b), the second current collection is performed on at least a part of the outer edge area Ao1 of the first surface 1bs. The electrode 8b may be located.
　上記各実施形態および各種変形例をそれぞれ構成する全部または一部を、適宜、矛盾しない範囲で組み合わせ可能であることは、言うまでもない。 It is needless to say that all or part of each of the above-described embodiments and various modifications may be combined as appropriate, as long as no contradiction arises.
　１　半導体基板
　１ｂｓ　第１面
　１ｆｓ　第２面
　１ｐ　凸部
　１ｒ　凹部
　１ｓｓ　第３面
　２　第１半導体層
　２ｂｓ　第３半導体層
　３　第２半導体層
　４　パッシベーション層
　６　保護層
　６ａｐ　非凸状部
　６ｐ　凸状部
　６ｐｒ　凹状部分
　６ｖｄ　空隙部
　８　裏面電極
　８ａ　第２出力取出電極
　８ｂ　第２集電電極
　８ｂｃ　接続部
　８ｂｌ　電極層
　１０　太陽電池素子
　１０ｂｓ，１００ｂｓ　裏面
　１０ｆｓ，１００ｆｓ　前面
　Ａｒ１　第１領域
　Ａｒ２　第２領域
　ＣＨ１　孔部
　ＣＰ１　中央部
　Ｄ１　第１距離
　Ｄ２　第２距離
　Ｄ３　第３距離
　Ｄ４　第４距離
　ＯＰ１　外周部
　ＳＣ１　内部空間
　ｄ４　径 REFERENCE SIGNS LIST 1 semiconductor substrate 1 bs first surface 1 fs second surface 1 p convex portion 1 r concave portion 1 ss third surface 2 first semiconductor layer 2 bs third semiconductor layer 3 second semiconductor layer 4 passivation layer 6 protective layer 6 ap non-convex portion 6 p convex portion 6pr recessed portion 6vd gap 8 back surface electrode 8a second output extraction electrode 8b second collecting electrode 8bc connection portion 8bl electrode layer 10 solar cell element 10bs, 100bs back surface 10fs, 100fs front surface Ar1 first region Ar2 second region CH2 hole portion CP1 Central part D1 First distance D2 Second distance D3 Third distance D4 Fourth distance OP1 Outer peripheral part SC1 Internal space d4 diameter

Claims (5)

  1. 　半導体基板と、
    　該半導体基板の第１面の上に位置しているパッシベーション層と、
    　該パッシベーション層の上に位置している保護層と、
    　該保護層の上に位置している、ガラス成分を含む電極層と、を備え、
    　前記保護層は、前記電極層側の面に位置している複数の凸状部を有し、
    　該複数の凸状部は、それぞれ前記電極層側において前記ガラス成分が内部空間に位置している凹状部分を有する、太陽電池素子。     A semiconductor substrate,
    A passivation layer located on the first surface of the semiconductor substrate;
    A protective layer located on the passivation layer,
    An electrode layer comprising a glass component located on the protective layer,
    The protective layer has a plurality of convex portions located on the surface on the electrode layer side,
    The solar cell element, wherein each of the plurality of convex portions has a concave portion in which the glass component is located in the internal space on the electrode layer side.
  2. 　請求項１に記載の太陽電池素子であって、
    　前記パッシベーション層および前記保護層は、該パッシベーション層および該保護層を貫通している状態でそれぞれ位置している複数の孔部を有し、
    　前記太陽電池素子は、
    　前記複数の孔部においてそれぞれ前記電極層と前記半導体基板とを電気的に接続している状態で位置している複数の接続部と、
    　複数の前記凹状部分と、を備え、
    　該複数の凹状部分のうちの隣り合う凹状部分同士の第１距離は、前記複数の凸状部のうちの隣り合う凸状部同士の第２距離および前記複数の接続部のうちの隣り合う接続部同士の第３距離の何れよりも短い、太陽電池素子。     The solar cell element according to claim 1, wherein
    The passivation layer and the protective layer have the passivation layer and a plurality of holes positioned through the protective layer, respectively.
    The solar cell element is
    A plurality of connecting portions positioned in a state of electrically connecting the electrode layer and the semiconductor substrate in the plurality of holes, respectively;
    A plurality of the concave portions;
    The first distance between adjacent concave portions of the plurality of concave portions is the second distance between adjacent convex portions among the plurality of convex portions and the adjacent connection among the plurality of connection portions. A solar cell element shorter than any of the 3rd distance of parts.
  3. 　請求項１または請求項２に記載の太陽電池素子であって、
    　前記保護層は、前記電極層側の面に位置し、前記複数の凸状部とは異なる非凸状部を有し、
    　該非凸状部は、それぞれ前記電極層側において前記ガラス成分が内部空間に位置している凹状部分を有する、太陽電池素子。     A solar cell element according to claim 1 or 2,
    The protective layer is located on the surface on the electrode layer side, and has a non-convex portion different from the plurality of convex portions.
    The solar cell element, wherein each of the non-convex portions has a concave portion in which the glass component is located in the internal space on the electrode layer side.
  4. 　請求項１から請求項３の何れか１つの請求項に記載の太陽電池素子であって、
    　前記保護層は、前記電極層側から前記保護層および前記半導体基板を平面透視した場合に、前記太陽電池素子の外周部側に位置している第１領域と、前記太陽電池素子の中央部側に位置している第２領域と、を有しており、
    　前記第１領域に存在している前記凹状部分の単位面積当たりの数が、前記第２領域に存在している前記凹状部分の前記単位面積当たりの数よりも多い、太陽電池素子。     The solar cell element according to any one of claims 1 to 3, wherein
    When the protective layer is seen through the protective layer and the semiconductor substrate from the electrode layer side, a first region located on the outer peripheral portion side of the solar cell element, and a central portion side of the solar cell element And a second region located at
    The solar cell element, wherein the number per unit area of the concave portion present in the first region is larger than the number per unit area of the concave portion present in the second region.
  5. 　請求項１から請求項４の何れか１つの請求項に記載の太陽電池素子であって、
    　前記保護層は、該保護層の内部に位置している複数の空隙部を有する、太陽電池素子。     The solar cell element according to any one of claims 1 to 4, wherein
    The solar cell element, wherein the protective layer has a plurality of air gaps located inside the protective layer.
PCT/JP2018/042747 2017-11-30 2018-11-20 Solar cell element WO2019107211A1 (en)

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JP6539010B1 (en) 2019-07-03

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