WO2011132781A1 - n-TYPE DIFFUSION LAYER FORMING COMPOSITION, METHOD OF PRODUCING n-TYPE DIFFUSION LAYER, AND METHOD OF PRODUCING SOLAR CELL ELEMENT - Google Patents

n-TYPE DIFFUSION LAYER FORMING COMPOSITION, METHOD OF PRODUCING n-TYPE DIFFUSION LAYER, AND METHOD OF PRODUCING SOLAR CELL ELEMENT Download PDF

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WO2011132781A1
WO2011132781A1 PCT/JP2011/059973 JP2011059973W WO2011132781A1 WO 2011132781 A1 WO2011132781 A1 WO 2011132781A1 JP 2011059973 W JP2011059973 W JP 2011059973W WO 2011132781 A1 WO2011132781 A1 WO 2011132781A1
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diffusion layer
type diffusion
forming composition
layer forming
glass powder
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PCT/JP2011/059973
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French (fr)
Japanese (ja)
Inventor
野尻　剛
吉田　誠人
香 岡庭
洋一 町井
岩室　光則
修一郎 足立
鉄也 佐藤
木沢　桂子
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日立化成工業株式会社
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Priority to CN201180018428.3A priority Critical patent/CN102834898B/en
Priority to KR1020127030146A priority patent/KR20130066613A/en
Priority to JP2012511723A priority patent/JP5541358B2/en
Publication of WO2011132781A1 publication Critical patent/WO2011132781A1/en

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/06—Glass compositions containing silica with more than 90% silica by weight, e.g. quartz
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/062—Glass compositions containing silica with less than 40% silica by weight
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/062—Glass compositions containing silica with less than 40% silica by weight
    • C03C3/07—Glass compositions containing silica with less than 40% silica by weight containing lead
    • C03C3/072—Glass compositions containing silica with less than 40% silica by weight containing lead containing boron
    • C03C3/074—Glass compositions containing silica with less than 40% silica by weight containing lead containing boron containing zinc
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/097—Glass compositions containing silica with 40% to 90% silica, by weight containing phosphorus, niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/12—Silica-free oxide glass compositions
    • C03C3/16—Silica-free oxide glass compositions containing phosphorus
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
    • C03C8/02—Frit compositions, i.e. in a powdered or comminuted form
    • C03C8/08—Frit compositions, i.e. in a powdered or comminuted form containing phosphorus
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
    • C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
    • C03C8/16—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions with vehicle or suspending agents, e.g. slip
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
    • H01L21/2225—Diffusion sources
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
    • H01L21/225—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities using diffusion into or out of a solid from or into a solid phase, e.g. a doped oxide layer
    • H01L21/2251—Diffusion into or out of group IV semiconductors
    • H01L21/2254—Diffusion into or out of group IV semiconductors from or through or into an applied layer, e.g. photoresist, nitrides
    • H01L21/2255—Diffusion into or out of group IV semiconductors from or through or into an applied layer, e.g. photoresist, nitrides the applied layer comprising oxides only, e.g. P2O5, PSG, H3BO3, doped oxides
    • 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
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to an n-type diffusion layer forming composition for a solar cell element, a method for producing an n-type diffusion layer, and a method for producing a solar cell element, and more specifically, a specific portion of a silicon substrate that is a semiconductor substrate.
  • the present invention relates to a technique that makes it possible to form an n-type diffusion layer.
  • a p-type silicon substrate having a textured structure is prepared so as to promote the light confinement effect and achieve high efficiency.
  • a mixed gas atmosphere of phosphorus oxychloride (POCl 3 ), nitrogen and oxygen is used at 800 to 900 ° C.
  • the n-type diffusion layer is uniformly formed by performing several tens of minutes.
  • n-type diffusion layers are formed not only on the surface but also on the side surface and the back surface. Therefore, a side etching process for removing the side n-type diffusion layer is necessary.
  • the n-type diffusion layer on the back surface needs to be converted into a p + -type diffusion layer.
  • An aluminum paste is applied on the n-type diffusion layer on the back surface, and the p + -type diffusion is performed from the n-type diffusion layer by the diffusion of aluminum. Was converted into a layer.
  • phosphorus such as phosphorus pentoxide (P 2 O 5 ) or ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) is used.
  • a method for forming an n-type diffusion layer by applying a solution containing an acid salt has been proposed.
  • this method uses a solution, as in the gas phase reaction method using the above mixed gas, the diffusion of phosphorus extends to the side surface and back surface, and n-type diffusion layers are formed not only on the surface but also on the side surface and back surface. Is done.
  • n-type diffusion layer in the gas phase reaction using phosphorus oxychloride, not only one surface (usually the light receiving surface, the surface) that originally requires the n-type diffusion layer but also the other surface ( An n-type diffusion layer is also formed on the non-light-receiving surface, back surface) and side surfaces. Further, even in the method of applying a solution containing phosphate and thermally diffusing, an n-type diffusion layer is formed on the surface other than the surface as in the gas phase reaction method. Therefore, in order to have a pn junction structure as an element, it is necessary to perform etching on the side surface and convert the n-type diffusion layer to the p-type diffusion layer on the back surface. In general, an aluminum paste which is a Group 13 element is applied to the back surface and fired to convert the n-type diffusion layer into a p-type diffusion layer.
  • the present invention has been made in view of the above-described conventional problems, and in a manufacturing process of a solar cell element using a silicon substrate, a specific part can be more efficiently performed without forming an unnecessary n-type diffusion layer. It is an object to provide an n-type diffusion layer forming composition capable of forming an n-type diffusion layer, a method for producing an n-type diffusion layer, and a method for producing a solar cell element.
  • n-type diffusion layer forming composition comprising a glass powder containing a donor element and having a softening temperature of 300 ° C. to 950 ° C., and a dispersion medium.
  • the donor element is at least one selected from P (phosphorus) and Sb (antimony).
  • the glass powder containing the donor element includes at least one donor element-containing material selected from P 2 O 3 , P 2 O 5 and Sb 2 O 3 , and SiO 2 , K 2 O, and Na 2 O.
  • n-type diffusion layer forming composition At least one glass component material selected from Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , CeO 2 and MoO 3 ⁇ 1 > Or ⁇ 2> The n-type diffusion layer forming composition. ⁇ 4> The n-type diffusion layer forming composition according to any one of ⁇ 1> to ⁇ 3>, wherein the crystallization temperature of the glass powder is 1050 ° C. or higher.
  • ⁇ 5> A method for producing an n-type diffusion layer, comprising a step of applying the n-type diffusion layer forming composition according to any one of ⁇ 1> to ⁇ 4> and a step of performing a thermal diffusion treatment.
  • ⁇ 6> A step of applying the n-type diffusion layer forming composition according to any one of ⁇ 1> to ⁇ 4> on a semiconductor substrate and a thermal diffusion treatment to form an n-type diffusion layer.
  • the manufacturing method of the solar cell element which has the process to form and the process of forming an electrode on the formed said n type diffused layer.
  • n-type diffusion layer in a specific portion without forming an unnecessary n-type diffusion layer in a manufacturing process of a solar cell element using a silicon substrate.
  • FIG. 2A It is sectional drawing which shows notionally an example of the manufacturing process of the solar cell element of this invention. It is the top view which looked at the solar cell element from the surface. It is a perspective view which expands and shows a part of FIG. 2A.
  • the n-type diffusion layer forming composition of the present invention will be described, and then the n-type diffusion layer and solar cell element manufacturing method using the n-type diffusion layer forming composition will be described.
  • the term “process” is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term “process” is used if the intended action of the process is achieved. included.
  • “to” indicates a range including numerical values described before and after that as a minimum value and a maximum value, respectively.
  • the amount of each component in the composition in the present specification when there are a plurality of substances corresponding to each component in the composition, the plurality of the components present in the composition unless otherwise specified. It means the total amount of substance.
  • the composition for forming an n-type diffusion layer of the present invention comprises a glass powder containing at least a donor element and a softening temperature of 300 ° C. to 950 ° C. (hereinafter sometimes simply referred to as “glass powder”), a dispersion medium And may further contain other additives as required in consideration of applicability and the like.
  • the n-type diffusion layer forming composition contains a donor element.
  • the n-type diffusion layer is formed by thermally diffusing the donor element by thermal diffusion treatment (firing). A material that can be formed.
  • an n-type diffusion layer is formed only at a desired site to which the n-type diffusion layer forming composition is applied, and the n-type diffusion layer forming composition is applied. Unnecessary n-type diffusion layers are not formed on the back and side surfaces.
  • the composition for forming an n-type diffusion layer of the present invention is applied, the side etching step that is essential in the gas phase reaction method that has been widely employed is not required, and the process is simplified.
  • the step of converting the n-type diffusion layer formed on the back surface into the p + -type diffusion layer is not necessary.
  • the method for forming the p + -type diffusion layer on the back surface and the material, shape, and thickness of the back electrode are not limited, and the choice of manufacturing method, material, and shape to be applied is widened.
  • production of the internal stress in the silicon substrate resulting from the thickness of a back surface electrode is suppressed, and the curvature of a silicon substrate is also suppressed.
  • the glass powder contained in the n-type diffusion layer forming composition of the present invention is melted by firing to form a glass layer on the n-type diffusion layer.
  • a glass layer is formed on the n-type diffusion layer also in the conventional gas phase reaction method and the method of applying a phosphate-containing solution. Therefore, the glass layer produced
  • the donor component in the glass powder is difficult to volatilize even during firing, it is suppressed that the n-type diffusion layer is formed not only on the surface but also on the back surface and side surfaces due to the generation of the volatilizing gas. The reason for this is considered that the donor component is bonded to an element in the glass powder or is taken into the glass, so that it is difficult to volatilize.
  • the n-type diffusion layer forming composition of the present invention can form an n-type diffusion layer having a desired concentration at a desired site, a selective region having a high n-type dopant concentration is formed. It becomes possible to form. On the other hand, it is generally difficult to form a selective region having a high n-type dopant concentration by a gas phase reaction method, which is a general method of an n-type diffusion layer, or a method using a phosphate-containing solution. .
  • a donor element is an element that can form an n-type diffusion layer by doping into a silicon substrate.
  • a Group 15 element can be used, and examples thereof include P (phosphorus), Sb (antimony), Bi (bismuth), and As (arsenic). From the viewpoints of safety, ease of vitrification, etc., P or Sb is preferred.
  • Examples of the donor element-containing material used for introducing the donor element into the glass powder include P 2 O 3 , P 2 O 5 , Sb 2 O 3 , Bi 2 O 3 and As 2 O 3 , and P 2 O 3 It is preferable to use at least one selected from P 2 O 5 and Sb 2 O 3 .
  • the glass powder containing a donor element can control a melting temperature, a softening temperature, a glass transition temperature, chemical durability, etc. by adjusting a component ratio as needed. Furthermore, it is preferable to contain the glass component substance described below.
  • glass component materials include SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , MoO 3 , La 2 O 3 , CeO 2, Nb 2 O 5, Ta 2 O 5, Y 2 O 3, TiO 2, ZrO 2, GeO 2, TeO 2 , and Lu 2 O 3 and the like, SiO 2, K 2 O, Na 2 O, It is preferable to use at least one selected from Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , CeO 2 and MoO 3 .
  • the glass powder containing a donor element include a system containing both the donor element-containing substance and the glass component substance, and a P 2 O 5 -SiO 2 system (in order of donor element-containing substance-glass component substance). in described, the same applies hereinafter), P 2 O 5 -K 2 O based, P 2 O 5 -Na 2 O-based, P 2 O 5 -Li 2 O system, P 2 O 5 -BaO-based, P 2 O 5 - SrO-based, P 2 O 5 -CaO-based, P 2 O 5 -MgO-based, P 2 O 5 -BeO based, P 2 O 5 -ZnO-based, P 2 O 5 -CdO based, P 2 O 5 -PbO system
  • a system containing P 2 O 5 as a donor element-containing substance such as a P 2 O 5 —CeO 2 system, a P 2 O 5 —SnO system, a P 2 O 5 —Ge
  • a glass powder containing two or more kinds of donor element-containing substances such as a P 2 O 5 —Sb 2 O 3 system and a P 2 O 5 —As 2 O 3 system, may be used.
  • a composite glass containing two components has been exemplified, but glass powder containing three or more components such as P 2 O 5 —SiO 2 —CeO 2 or P 2 O 5 —SiO 2 —CaO may be used.
  • the content ratio of the glass component substance in the glass powder is preferably set appropriately in consideration of the melting temperature, softening temperature, glass transition temperature, crystallization temperature, chemical durability, and generally 0.1% by mass or more. It is preferably 95% by mass or less, and more preferably 0.5% by mass or more and 90% by mass or less.
  • the content ratio of CeO 2 is preferably 1% by mass or more and 50% by mass or less, and more preferably 3% by mass or more and 40% by mass or less. It is more preferable. With such a content ratio, the n-type diffusion layer can be formed more uniformly.
  • the softening temperature of the glass powder is important from the viewpoint of obtaining a more uniform n-type diffusion layer by more effectively diffusing the donor element into the silicon substrate during the thermal diffusion treatment described later.
  • the softening temperature is 300 ° C. to 950 ° C., preferably 350 ° C. to 900 ° C., more preferably 370 ° C. to 850 ° C., and further preferably 390 ° C. to 800 ° C.
  • the softening temperature of the glass powder is less than 300 ° C., the glass component tends to crystallize during the thermal diffusion treatment at a high temperature, and the etching removability tends to decrease in the etching removal step of the glass component after the thermal diffusion treatment.
  • the donor element since the melting point is lowered, the donor element is likely to volatilize and the n-type diffusion layer tends to be easily formed in an unnecessary portion during the thermal diffusion treatment.
  • the softening temperature of glass powder exceeds 950 degreeC, it becomes difficult to soften glass at the time of a thermal-diffusion process, and the glass powder remains with the granular shape. Therefore, the diffusion of the donor element proceeds without the glass component being microscopically uniformly covered on the silicon substrate, and as a result, the formability of the n-type diffusion layer tends to be non-uniform, and the sheet resistance value May rise.
  • the softening temperature of the glass powder can be easily measured from its endothermic peak using a known differential thermal analyzer (DTA).
  • the crystallization temperature of glass powder is 1050 degreeC or more, It is more preferable that it is 1100 degreeC or more, It is further more preferable that it is 1200 degreeC or more.
  • the crystallization temperature is 1050 ° C. or higher, crystallization of the glass component during the thermal diffusion treatment is suppressed. Thereby, the residual of the crystallized substance in the glass component etching removal step after the thermal diffusion treatment is suppressed, and the etching removability of the glass component is improved.
  • the crystallization temperature of glass powder can be easily measured from the exothermic peak with a well-known differential thermal analyzer (DTA).
  • DTA differential thermal analyzer
  • the shape of the glass powder examples include a substantially spherical shape, a flat shape, a block shape, a plate shape, a scale shape, and the like. From the viewpoint of the application property to the substrate and the uniform diffusibility when it is an n-type diffusion layer forming composition, It is desirable to have a substantially spherical shape, a flat shape, or a plate shape.
  • the particle size of the glass powder is desirably 100 ⁇ m or less. When glass powder having a particle size of 100 ⁇ m or less is used, a smooth coating film is easily obtained. Furthermore, the particle size of the glass powder is more desirably 50 ⁇ m or less. The lower limit is not particularly limited, but is preferably 0.01 ⁇ m or more.
  • the particle diameter of glass represents an average particle diameter, and can be measured by a laser scattering diffraction particle size distribution measuring apparatus or the like.
  • the glass powder containing a donor element is produced by the following procedure. First, weigh the ingredients and fill the crucible. Examples of the material for the crucible include platinum, platinum-rhodium, iridium, alumina, quartz, carbon, and the like, and are appropriately selected in consideration of the melting temperature, atmosphere, reactivity with the molten material, and the like. Next, it heats with the temperature according to a glass composition with an electric furnace, and is set as a melt. At this time, it is desirable to stir the melt uniformly. Subsequently, the obtained melt is poured onto a graphite plate, a platinum plate, a platinum-rhodium alloy plate, a zirconia plate or the like to vitrify the melt. Finally, the glass is crushed into powder. A known method such as a jet mill, a bead mill, or a ball mill can be applied to the pulverization.
  • the content ratio of the glass powder containing the donor element in the n-type diffusion layer forming composition is determined in consideration of the coating property, the diffusibility of the donor element, and the like.
  • the content ratio of the glass powder in the n-type diffusion layer forming composition is preferably 0.1% by mass or more and 95% by mass or less, more preferably 1% by mass or more and 90% by mass or less, The content is more preferably 1.5% by mass or more and 85% by mass or less, and particularly preferably 2% by mass or more and 80% by mass or less.
  • the dispersion medium is a medium in which the glass powder is dispersed in the composition. Specifically, a binder, a solvent, or the like is employed as the dispersion medium.
  • binder examples include polyvinyl alcohol, polyacrylamides, polyvinylamides, polyvinylpyrrolidone, polyethylene oxides, polysulfonic acid, acrylamide alkylsulfonic acid, cellulose ethers, cellulose derivatives, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, gelatin, starch And starch derivatives, sodium alginates, xanthan, gua and gua derivatives, scleroglucan and scleroglucan derivatives, tragacanth and tragacanth derivatives, dextrin and dextrin derivatives, (meth) acrylic acid resins, (meth) acrylic acid ester resins (e.g.
  • Alkyl (meth) acrylate resins Alkyl (meth) acrylate resins, dimethylaminoethyl (meth) acrylate resins, etc.), butadiene Fat, styrene resins, copolymers thereof, Additional be appropriately selected siloxane resin. These are used singly or in combination of two or more.
  • the molecular weight of the binder is not particularly limited, and it is desirable to adjust appropriately in view of the desired viscosity as the composition.
  • the solvent examples include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-iso-propyl ketone, methyl-n-butyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, methyl-n-hexyl ketone, Ketone solvents such as diethyl ketone, dipropyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone; diethyl ether, methyl ethyl ether, methyl -N-propyl ether, di-iso-propyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane,
  • n-type diffusion layer forming composition ⁇ -terpineol, diethylene glycol mono-n-butyl ether, and 2- (2-butoxyethoxy) ethyl acetate are preferred from the viewpoint of applicability to the substrate.
  • the content ratio of the dispersion medium in the n-type diffusion layer forming composition is determined in consideration of applicability and donor concentration.
  • the viscosity of the n-type diffusion layer forming composition is preferably 10 mPa ⁇ s or more and 1000000 mPa ⁇ s or less, and more preferably 50 mPa ⁇ s or more and 500000 mPa ⁇ s or less in consideration of applicability.
  • FIG. 1 is a schematic cross-sectional view conceptually showing an example of the manufacturing process of the solar cell element of the present invention.
  • common constituent elements are denoted by the same reference numerals.
  • an alkaline solution is applied to a silicon substrate which is a p-type semiconductor substrate 10 to remove a damaged layer, and a texture structure is obtained by etching.
  • a texture structure is obtained by etching.
  • the damaged layer on the silicon surface generated when slicing from the ingot is removed with 20% by mass caustic soda.
  • etching is performed with a mixed solution of 1% by mass caustic soda and 10% by mass isopropyl alcohol to form a texture structure (the description of the texture structure is omitted in the figure).
  • a texture structure on the light receiving surface (surface) side, a light confinement effect is promoted, and high efficiency is achieved.
  • the n-type diffusion layer forming composition layer 11 is formed by applying the n-type diffusion layer forming composition to the surface of the p-type semiconductor substrate 10, that is, the surface that becomes the light receiving surface.
  • the coating method is not limited, and examples thereof include a printing method, a spin method, a brush coating, a spray method, a doctor blade method, a roll coater method, and an ink jet method.
  • the glass powder amount can be 0.01 g / m 2 to 100 g / m 2, and preferably 0.1 g / m 2 to 10 g / m 2 .
  • a drying step for volatilizing the solvent contained in the composition may be provided after coating.
  • drying is performed at a temperature of about 80 ° C. to 300 ° C. for about 1 to 10 minutes when using a hot plate, and about 10 to 30 minutes when using a dryer or the like.
  • the drying conditions depend on the solvent composition of the n-type diffusion layer forming composition, and are not particularly limited to the above conditions in the present invention.
  • the manufacturing method of the p + -type diffusion layer (high concentration electric field layer) 14 on the back surface is limited to a method by conversion from an n-type diffusion layer to a p-type diffusion layer with aluminum. Therefore, any conventionally known method can be adopted, and the options of the manufacturing method are expanded. Therefore, for example, the composition layer 13 can be formed by applying a composition containing a Group 13 element such as B (boron), and the high concentration electric field layer 14 can be formed.
  • composition 13 containing a Group 13 element such as B (boron) for example, a glass powder containing an acceptor element is used instead of a glass powder containing a donor element, and the same as the composition for forming an n-type diffusion layer.
  • a p-type diffusion layer forming composition constituted as described above can be given.
  • the acceptor element may be an element belonging to Group 13, and examples thereof include B (boron), Al (aluminum), and Ga (gallium).
  • the glass powder containing acceptor element preferably comprises at least one selected from B 2 O 3, Al 2 O 3 and Ga 2 O 3.
  • the method for applying the p-type diffusion layer forming composition to the back surface of the silicon substrate is the same as the method for applying the n-type diffusion layer forming composition described above on the silicon substrate.
  • the high-concentration electric field layer 14 can be formed on the back surface by subjecting the p-type diffusion layer forming composition applied to the back surface to a thermal diffusion treatment similar to the thermal diffusion treatment in the n-type diffusion layer forming composition described later. .
  • the thermal diffusion treatment of the p-type diffusion layer forming composition is preferably performed simultaneously with the thermal diffusion treatment of the n-type diffusion layer forming composition.
  • the semiconductor substrate 10 on which the n-type diffusion layer forming composition layer 11 is formed is subjected to thermal diffusion treatment at 600 ° C. to 1200 ° C.
  • thermal diffusion treatment As shown in FIG. 1C, the donor element diffuses into the semiconductor substrate, and the n-type diffusion layer 12 is formed.
  • a known continuous furnace, batch furnace, or the like can be applied to the thermal diffusion treatment. Further, the furnace atmosphere during the thermal diffusion treatment can be appropriately adjusted to air, oxygen, nitrogen or the like as necessary.
  • the thermal diffusion treatment time can be appropriately selected according to the donor element content contained in the n-type diffusion layer forming composition, the softening temperature of the glass powder, and the like. For example, it can be 1 minute to 60 minutes, and more preferably 2 minutes to 30 minutes.
  • a glass layer such as phosphate glass is formed on the surface of the formed n-type diffusion layer 12, this glass layer is removed by etching.
  • etching a known method such as a method of immersing in an acid such as hydrofluoric acid or a method of immersing in an alkali such as caustic soda can be applied.
  • the n-type diffusion layer 12 is formed using the n-type diffusion layer forming composition layer 11 of the present invention.
  • the n-type diffusion layer 12 is formed only at the site, and an unnecessary n-type diffusion layer is not formed on the back surface or the side surface. Therefore, in the conventional method of forming an n-type diffusion layer by a gas phase reaction method, a side etching process for removing an unnecessary n-type diffusion layer formed on a side surface is essential. According to the manufacturing method of the invention, the side etching process is not required, and the process is simplified.
  • n-type diffusion layer formed on the back surface it is necessary to convert an unnecessary n-type diffusion layer formed on the back surface into a p-type diffusion layer.
  • a group 13 element is added to the n-type diffusion layer on the back surface.
  • a method is adopted in which an aluminum paste is applied and baked to diffuse aluminum into the n-type diffusion layer and convert it into a p-type diffusion layer.
  • conversion to the p-type diffusion layer is sufficient, and in order to form a high-concentration electric field layer of the p + -type diffusion layer, a certain amount of aluminum is required. There was a need to form.
  • the manufacturing method of the present invention since an unnecessary n-type diffusion layer is not formed on the back surface, it is not necessary to perform conversion from the n-type diffusion layer to the p-type diffusion layer, and the necessity of increasing the thickness of the aluminum layer is eliminated. . As a result, generation of internal stress and warpage in the silicon substrate can be suppressed. As a result, it is possible to suppress an increase in power loss and damage to the solar cell element.
  • the manufacturing method of the p + -type diffusion layer (high concentration electric field layer) 14 on the back surface is limited to a method by conversion from an n-type diffusion layer to a p-type diffusion layer with aluminum. Therefore, any conventionally known method can be adopted, and the options of the manufacturing method are expanded.
  • a p-type diffusion layer forming composition configured in the same manner as the n-type diffusion layer forming composition is formed on the back surface (n).
  • the p + -type diffusion layer (high-concentration electric field layer) 14 is preferably formed on the back surface by applying to the surface opposite to the surface on which the mold diffusion layer forming composition is applied and baking.
  • the material used for the back surface electrode 20 is not limited to Group 13 aluminum, and for example, Ag (silver), Cu (copper), or the like can be applied. In addition, it can be formed thinner than the conventional one.
  • an antireflection film 16 is formed on the n-type diffusion layer 12.
  • the antireflection film 16 is formed by applying a known technique.
  • the antireflection film 16 is a silicon nitride film, it is formed by a plasma CVD method using a mixed gas of SiH 4 and NH 3 as a raw material.
  • hydrogen diffuses into the crystal, and orbits that do not contribute to the bonding of silicon atoms, that is, dangling bonds and hydrogen are combined to inactivate defects (hydrogen passivation).
  • the mixed gas flow ratio NH 3 / SiH 4 is 0.05 to 1.0
  • the reaction chamber pressure is 0.1 Torr to 2 Torr
  • the temperature during film formation is 300 ° C. to 550 ° C.
  • a surface electrode metal paste is printed, applied and dried by a screen printing method on the antireflection film 16 on the surface (light receiving surface) to form the surface electrode 18.
  • the metal paste for a surface electrode contains (1) metal particles and (2) glass particles as essential components, and includes (3) a resin binder and (4) other additives as necessary.
  • the back electrode 20 is also formed on the high-concentration electric field layer 14 on the back surface.
  • the material and forming method of the back electrode 20 are not particularly limited.
  • the back electrode 20 may be formed by applying and drying a back electrode paste containing a metal such as aluminum, silver, or copper.
  • a silver paste for forming a silver electrode may be partially provided on the back surface for connection between solar cell elements in the module process.
  • the electrode is fired to complete the solar cell element.
  • the antireflection film 16 as an insulating film is melted by the glass particles contained in the electrode metal paste on the surface side, and the silicon 10 surface is also partially melted.
  • the metal particles (for example, silver particles) in the paste form a contact portion with the silicon substrate 10 and solidify. Thereby, the formed surface electrode 18 and the silicon substrate 10 are electrically connected. This is called fire-through.
  • FIG. 2A is a plan view of a solar cell element in which the surface electrode 18 includes a bus bar electrode 30 and a finger electrode 32 intersecting with the bus bar electrode 30 as viewed from the surface.
  • FIG. 2B is a perspective view showing a part of FIG.
  • Such a surface electrode 18 can be formed, for example, by means such as screen printing of the above-described metal paste, plating of the electrode material, or vapor deposition of the electrode material by electron beam heating in a high vacuum.
  • the surface electrode 18 composed of the bus bar electrode 30 and the finger electrode 32 is generally used as an electrode on the light receiving surface side and is well known, and it is possible to apply known forming means for the bus bar electrode and finger electrode on the light receiving surface side. it can.
  • the solar cell element in which the n-type diffusion layer is formed on the front surface, the p + -type diffusion layer is formed on the back surface, and the front surface electrode and the back surface electrode are further provided on the respective layers has been described.
  • a layer formation composition it is also possible to produce a back contact type solar cell element.
  • the back contact type solar cell element has all electrodes provided on the back surface to increase the area of the light receiving surface. That is, in the back contact type solar cell element, it is necessary to form both the n-type diffusion region and the p + -type diffusion region on the back surface to form a pn junction structure.
  • the n-type diffusion layer forming composition of the present invention can form an n-type diffusion site only at a specific site, and therefore can be suitably applied to the production of a back contact type solar cell element.
  • Example 1 P 2 O 5 —CeO 2 -based glass (P 2 O 5 : 39.6%, CeO 2 : 10%, BaO: 10.4%, MoO 3 having a substantially spherical particle shape and an average particle diameter of 3.5 ⁇ m) : 10%, ZnO: 30%) 20 g of powder, 0.3 g of ethyl cellulose and 7 g of 2- (2-butoxyethoxy) ethyl acetate were mixed using an automatic mortar kneader to form a paste, forming an n-type diffusion layer A composition was prepared.
  • the above P 2 O 5 -CeO 2 glass powder was subjected to thermal analysis with a thermal analyzer manufactured by Shimadzu Corporation (TG-DTA, DTG60H type, measurement conditions: heating rate 20 ° C./min, air flow rate 100 ml / min).
  • a thermal analyzer manufactured by Shimadzu Corporation (TG-DTA, DTG60H type, measurement conditions: heating rate 20 ° C./min, air flow rate 100 ml / min).
  • the softening temperature was 520 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the glass particle shape was determined by observation using a TM-1000 scanning electron microscope manufactured by Hitachi High-Technologies Corporation.
  • the average particle size of the glass was calculated using a LS 13 320 type laser scattering diffraction particle size distribution analyzer (measurement wavelength: 632 nm) manufactured by Beckman Coulter, Inc.
  • the prepared paste (n-type diffusion layer forming composition) was applied to the surface of the p-type silicon substrate by screen printing and dried on a hot plate at 150 ° C. for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set at 1000 ° C., and then the substrate was immersed in 10% hydrofluoric acid for 5 minutes to remove the glass layer, and washed with running water. Thereafter, drying was performed.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 45 ⁇ / ⁇ , P (phosphorus) diffused, and an n-type diffusion layer was formed.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • the evaluation results are shown in Table 1.
  • the sheet resistance was measured by a four-probe method using a Loresta-EP MCP-T360 type low resistivity meter manufactured by Mitsubishi Chemical Corporation.
  • Example 2 An n-type diffusion layer was formed in the same manner as in Example 1 except that the thermal diffusion treatment time was 15 minutes.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 30 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • Example 3 An n-type diffusion layer was formed in the same manner as in Example 1 except that the thermal diffusion treatment time was 30 minutes.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 17 ⁇ / ⁇ , and P (phosphorus) was diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • Example 4 A glass powder having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m P 2 O 5 —ZnO-based glass (P 2 O 5 : 40%, ZnO: 40%, CeO 2 : 10%, MgO: 5) %, CaO: 5%).
  • An n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition.
  • the softening temperature of the glass powder was 480 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 41 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • the glass powder is made of P 2 O 5 —SiO 2 glass (P 2 O 5 : 30%, SiO 2 : 50%, CeO 2 : 10%, ZnO) having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m. : 10%), an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition.
  • the softening temperature of the glass powder was 610 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 48 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • Example 6 An n-type diffusion layer was formed in the same manner as in Example 5 except that the thermal diffusion treatment time was 30 minutes.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 30 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • Example 7 Except that the glass powder was made into P 2 O 5 —PbO glass (P 2 O 5 : 30%, PbO: 50%, ZnO: 20%) having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m. Then, an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition.
  • the softening temperature of the glass powder was 330 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 15 ⁇ / ⁇ , and P (phosphorus) was diffused to form an n-type diffusion layer. On the other hand, it was judged that the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured and was not substantially formed.
  • the glass powder is a P 2 O 5 —SiO 2 glass (P 2 O 5 : 40%, SiO 2 : 10%, PbO: 30%, ZnO: having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m). 10%, CaO: 10%)
  • An n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition.
  • the softening temperature of the glass powder was 360 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 21 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • the glass powder is made of P 2 O 5 —SiO 2 glass (P 2 O 5 : 40%, SiO 2 : 10%, PbO: 20%, ZnO: having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m).
  • An n-type diffusion layer forming composition was prepared in the same manner as in Example 1 except that 20% and NaO: 10%), and an n-type diffusion layer was formed using this composition.
  • the softening temperature of the glass powder was 385 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 25 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • the glass powder is made of P 2 O 5 —ZnO-based glass (P 2 O 5 : 30%, ZnO: 40%, CaO: 20%, Al 2 O 3) having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m. : 10%), an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition.
  • the softening temperature of the glass powder was 450 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 36 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • the glass powder is a P 2 O 5 —SiO 2 glass (P 2 O 5 : 50%, SiO 2 : 10%, ZnO: 30%, CaO: having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m). 10), except that the thermal diffusion treatment time was 20 minutes, an n-type diffusion layer forming composition was prepared as Example 1, and an n-type diffusion layer was similarly formed using this composition.
  • the softening temperature of the glass powder was 610 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 40 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • the glass powder was P 2 O 5 —SiO 2 glass (P 2 O 5 : 27%, SiO 2 : 58%, CaO: 15%) having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m. Except for the above, an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition.
  • the softening temperature of the glass powder was 830 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 69 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • the glass powder was P 2 O 5 —SiO 2 glass (P 2 O 5 : 30%, SiO 2 60%, CaO 10%) having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m. Except for the above, an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition.
  • the softening temperature of the glass powder was 875 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 71 ⁇ / ⁇ , and P (phosphorus) was diffused to form an n-type diffusion layer. On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • the glass powder is made of P 2 O 5 —SiO 2 glass (P 2 O 5 : 25%, SiO 2 : 65%, CaO: 5%, Al 2) having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m. Except that O 3 : 5%), an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition.
  • the softening temperature of the glass powder was 930 ° C.
  • the crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 83 ⁇ / ⁇ , and P (phosphorus) was diffused to form an n-type diffusion layer.
  • the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 14 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer.
  • the sheet resistance on the back surface was 50 ⁇ / ⁇ , and an n-type diffusion layer was also formed on the back surface.
  • a solution was prepared by mixing 1 g of ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) powder, 7 g of pure water, 0.7 g of polyvinyl alcohol, and 1.5 g of isopropyl alcohol.
  • the prepared solution was applied to the surface of the p-type silicon substrate by a spin coater (2000 rpm, 30 sec) and dried on a hot plate at 150 ° C. for 5 minutes.
  • a thermal diffusion treatment was performed for 10 minutes in an electric furnace set at 1000 ° C., and then the substrate was immersed in hydrofluoric acid for 5 minutes to remove the glass layer, washed with running water, and dried.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 10 ⁇ / ⁇ , and P (phosphorus) was diffused to form an n-type diffusion layer.
  • the sheet resistance on the back surface was 100 ⁇ / ⁇ , and an n-type diffusion layer was also formed on the back surface.
  • the glass powder was P 2 O 5 —SiO 2 glass (P 2 O 5 : 10%, SiO 2 : 20%, NaO: 70%) having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m. Except for the above, an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 230 ° C. The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 61 ⁇ / ⁇ , and P (phosphorus) diffused to form an n-type diffusion layer. However, the sheet resistance of the part where the n-type diffusion layer forming composition including the back surface is not applied is 65 ⁇ / ⁇ , and the n-type diffusion layer is formed even in an unnecessary part, An n-type diffusion layer could not be formed.
  • the glass powder was P 2 O 5 —SiO 2 glass (P 2 O 5 : 5%, SiO 2 : 93%, NaO: 2%) having a substantially spherical particle shape and an average particle diameter of 3.2 ⁇ m. Except for the above, an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition.
  • the softening temperature of the glass powder exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
  • the sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
  • the n-type diffusion layer forming composition of the present invention can be uniformly formed only at a specific site.

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Abstract

The disclosed n-type diffusion layer forming composition is constituted so as to contain a glass powder containing a donor element and having a softening temperature of 300-950C, and a dispersion medium. By applying a coating of said n-type diffusion layer forming composition and performing thermal diffusion treatment, an n-type diffusion layer, and a solar cell element having the n-type diffusion layer, are produced.

Description

ｎ型拡散層形成組成物、ｎ型拡散層の製造方法、及び太陽電池素子の製造方法N-type diffusion layer forming composition, n-type diffusion layer manufacturing method, and solar cell element manufacturing method
　本発明は、太陽電池素子のｎ型拡散層形成組成物、ｎ型拡散層の製造方法、及び太陽電池素子の製造方法に関するものであり、更に詳しくは、半導体基板であるシリコン基板の特定の部分にｎ型拡散層を形成することを可能とする技術に関するものである。 The present invention relates to an n-type diffusion layer forming composition for a solar cell element, a method for producing an n-type diffusion layer, and a method for producing a solar cell element, and more specifically, a specific portion of a silicon substrate that is a semiconductor substrate. The present invention relates to a technique that makes it possible to form an n-type diffusion layer.
　従来のシリコン太陽電池素子の製造工程について説明する。
　まず、光閉じ込め効果を促して高効率化を図るよう、テクスチャー構造を形成したｐ型シリコン基板を準備し、続いてオキシ塩化リン（ＰＯＣｌ３）、窒素、酸素の混合ガス雰囲気において８００～９００℃で数十分の処理を行って一様にｎ型拡散層を形成する。この従来の方法では、混合ガスを用いてリンの拡散を行うため、表面のみならず、側面、裏面にもｎ型拡散層が形成される。そのため、側面のｎ型拡散層を除去するためのサイドエッチング工程が必要であった。また、裏面のｎ型拡散層はｐ＋型拡散層へ変換する必要があり、裏面のｎ型拡散層の上にアルミニウムペーストを付与して、アルミニウムの拡散によってｎ型拡散層からｐ＋型拡散層に変換させていた。 The manufacturing process of the conventional silicon solar cell element is demonstrated.
First, a p-type silicon substrate having a textured structure is prepared so as to promote the light confinement effect and achieve high efficiency. Subsequently, a mixed gas atmosphere of phosphorus oxychloride (POCl 3 ), nitrogen and oxygen is used at 800 to 900 ° C. The n-type diffusion layer is uniformly formed by performing several tens of minutes. In this conventional method, since phosphorus is diffused using a mixed gas, n-type diffusion layers are formed not only on the surface but also on the side surface and the back surface. Therefore, a side etching process for removing the side n-type diffusion layer is necessary. Further, the n-type diffusion layer on the back surface needs to be converted into a p + -type diffusion layer. An aluminum paste is applied on the n-type diffusion layer on the back surface, and the p + -type diffusion is performed from the n-type diffusion layer by the diffusion of aluminum. Was converted into a layer.
　一方、半導体の製造分野では、例えば特開２００２－７５８９４号公報に開示されているように、五酸化リン（Ｐ２Ｏ５）あるいはリン酸二水素アンモニウム（ＮＨ４Ｈ２ＰＯ４）等のリン酸塩を含有する溶液の塗布によってｎ型拡散層を形成する方法が提案されている。しかしながら、この方法では溶液を用いるために、上記混合ガスを用いる気相反応法と同様、リンの拡散が側面及び裏面にも及び、表面のみならず、側面、裏面にもｎ型拡散層が形成される。 On the other hand, in the semiconductor manufacturing field, as disclosed in, for example, JP-A-2002-75894, phosphorus such as phosphorus pentoxide (P 2 O 5 ) or ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) is used. A method for forming an n-type diffusion layer by applying a solution containing an acid salt has been proposed. However, since this method uses a solution, as in the gas phase reaction method using the above mixed gas, the diffusion of phosphorus extends to the side surface and back surface, and n-type diffusion layers are formed not only on the surface but also on the side surface and back surface. Is done.
　上述のように、ｎ型拡散層形成の際、オキシ塩化リンを用いた気相反応では、本来ｎ型拡散層が必要となる片面（通常受光面、表面）のみならず、もう一方の面（非受光面、裏面）や側面にもｎ型拡散層が形成されてしまう。また、リン酸塩を含有する溶液を塗布して熱拡散させる方法でも、気相反応法と同様、表面以外にもｎ型拡散層が形成されてしまう。そのため、素子としてｐｎ接合構造を有するためには、側面においてはエッチングを行い、裏面においてはｎ型拡散層をｐ型拡散層へ変換しなければならない。一般には、裏面に第１３族元素であるアルミニウムのペーストを塗布、焼成し、ｎ型拡散層をｐ型拡散層へ変換している。 As described above, when forming the n-type diffusion layer, in the gas phase reaction using phosphorus oxychloride, not only one surface (usually the light receiving surface, the surface) that originally requires the n-type diffusion layer but also the other surface ( An n-type diffusion layer is also formed on the non-light-receiving surface, back surface) and side surfaces. Further, even in the method of applying a solution containing phosphate and thermally diffusing, an n-type diffusion layer is formed on the surface other than the surface as in the gas phase reaction method. Therefore, in order to have a pn junction structure as an element, it is necessary to perform etching on the side surface and convert the n-type diffusion layer to the p-type diffusion layer on the back surface. In general, an aluminum paste which is a Group 13 element is applied to the back surface and fired to convert the n-type diffusion layer into a p-type diffusion layer.
　本発明は、以上の従来の問題点に鑑みなされたものであり、シリコン基板を用いた太陽電池素子の製造工程において、不要なｎ型拡散層を形成させることなく、より効率的に特定の部分にｎ型拡散層を形成することが可能なｎ型拡散層形成組成物、ｎ型拡散層の製造方法、及び太陽電池素子の製造方法の提供を課題とする。 The present invention has been made in view of the above-described conventional problems, and in a manufacturing process of a solar cell element using a silicon substrate, a specific part can be more efficiently performed without forming an unnecessary n-type diffusion layer. It is an object to provide an n-type diffusion layer forming composition capable of forming an n-type diffusion layer, a method for producing an n-type diffusion layer, and a method for producing a solar cell element.
　前記課題を解決する手段は以下の通りである。
＜１＞　ドナー元素を含み軟化温度が３００℃～９５０℃であるガラス粉末と、分散媒と、を含有するｎ型拡散層形成組成物。
＜２＞　前記ドナー元素が、Ｐ（リン）及びＳｂ（アンチモン）から選択される少なくとも１種である前記＜１＞に記載のｎ型拡散層形成組成物。
＜３＞　前記ドナー元素を含むガラス粉末が、Ｐ２Ｏ３、Ｐ２Ｏ５及びＳｂ２Ｏ３から選択される少なくとも１種のドナー元素含有物質と、ＳｉＯ２、Ｋ２Ｏ、Ｎａ２Ｏ、Ｌｉ２Ｏ、ＢａＯ、ＳｒＯ、ＣａＯ、ＭｇＯ、ＢｅＯ、ＺｎＯ、ＰｂＯ、ＣｄＯ、ＳｎＯ、ＺｒＯ２、ＣｅＯ２及びＭｏＯ３から選択される少なくとも１種のガラス成分物質と、を含有する前記＜１＞又は＜２＞に記載のｎ型拡散層形成組成物。
＜４＞　更に、前記ガラス粉末の結晶化温度が１０５０℃以上である前記＜１＞～＜３＞のいずれか１項に記載のｎ型拡散層形成組成物。 Means for solving the problems are as follows.
<1> An n-type diffusion layer forming composition comprising a glass powder containing a donor element and having a softening temperature of 300 ° C. to 950 ° C., and a dispersion medium.
<2> The n-type diffusion layer forming composition according to <1>, wherein the donor element is at least one selected from P (phosphorus) and Sb (antimony).
<3> The glass powder containing the donor element includes at least one donor element-containing material selected from P 2 O 3 , P 2 O 5 and Sb 2 O 3 , and SiO 2 , K 2 O, and Na 2 O. And at least one glass component material selected from Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , CeO 2 and MoO 3 <1 > Or <2> The n-type diffusion layer forming composition.
<4> The n-type diffusion layer forming composition according to any one of <1> to <3>, wherein the crystallization temperature of the glass powder is 1050 ° C. or higher.
＜５＞　前記＜１＞～＜４＞のいずれか１項に記載のｎ型拡散層形成組成物を塗布する工程と、熱拡散処理を施す工程と、を有するｎ型拡散層の製造方法。
＜６＞　半導体基板上に、前記＜１＞～＜４＞のいずれか１項に記載のｎ型拡散層形成組成物を塗布する工程と、熱拡散処理を施して、ｎ型拡散層を形成する工程と、形成された前記ｎ型拡散層上に電極を形成する工程とを有する太陽電池素子の製造方法。 <5> A method for producing an n-type diffusion layer, comprising a step of applying the n-type diffusion layer forming composition according to any one of <1> to <4> and a step of performing a thermal diffusion treatment.
<6> A step of applying the n-type diffusion layer forming composition according to any one of <1> to <4> on a semiconductor substrate and a thermal diffusion treatment to form an n-type diffusion layer The manufacturing method of the solar cell element which has the process to form and the process of forming an electrode on the formed said n type diffused layer.
　本発明によれば、シリコン基板を用いた太陽電池素子の製造工程において、不要なｎ型拡散層を形成させることなく、より効率的に特定の部分にｎ型拡散層を形成することが可能となる。 According to the present invention, it is possible to more efficiently form an n-type diffusion layer in a specific portion without forming an unnecessary n-type diffusion layer in a manufacturing process of a solar cell element using a silicon substrate. Become.
本発明の太陽電池素子の製造工程の一例を概念的に示す断面図である。It is sectional drawing which shows notionally an example of the manufacturing process of the solar cell element of this invention. 太陽電池素子を表面から見た平面図である。It is the top view which looked at the solar cell element from the surface. 図２Ａの一部を拡大して示す斜視図である。It is a perspective view which expands and shows a part of FIG. 2A.
　まず、本発明のｎ型拡散層形成組成物について説明し、次にｎ型拡散層形成組成物を用いるｎ型拡散層及び太陽電池素子の製造方法について説明する。
　尚、本明細書において「工程」との語は、独立した工程だけではなく、他の工程と明確に区別できない場合であってもその工程の所期の作用が達成されれば、本用語に含まれる。また、本明細書において「～」は、その前後に記載される数値をそれぞれ最小値及び最大値として含む範囲を示すものとする。さらに本明細書において組成物中の各成分の量について言及する場合、組成物中に各成分に該当する物質が複数存在する場合には、特に断らない限り、組成物中に存在する当該複数の物質の合計量を意味する。 First, the n-type diffusion layer forming composition of the present invention will be described, and then the n-type diffusion layer and solar cell element manufacturing method using the n-type diffusion layer forming composition will be described.
In this specification, the term “process” is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term “process” is used if the intended action of the process is achieved. included. Further, in this specification, “to” indicates a range including numerical values described before and after that as a minimum value and a maximum value, respectively. Further, when referring to the amount of each component in the composition in the present specification, when there are a plurality of substances corresponding to each component in the composition, the plurality of the components present in the composition unless otherwise specified. It means the total amount of substance.
　本発明のｎ型拡散層形成組成物は、少なくともドナー元素を含み、かつ、軟化温度が３００℃～９５０℃であるガラス粉末（以下、単に「ガラス粉末」と称する場合がある）と、分散媒と、を含有し、更に塗布性などを考慮してその他の添加剤を必要に応じて含有してもよい。
　ここで、ｎ型拡散層形成組成物とは、ドナー元素を含有し、例えば、シリコン基板に塗布した後に、熱拡散処理（焼成）することでこのドナー元素を熱拡散させてｎ型拡散層を形成することが可能な材料をいう。本発明のｎ型拡散層形成組成物を用いることで、ｎ型拡散層形成組成物が付与された所望の部位にのみｎ型拡散層が形成され、ｎ型拡散層形成組成物が付与されていない裏面や側面には不要なｎ型拡散層が形成されない。 The composition for forming an n-type diffusion layer of the present invention comprises a glass powder containing at least a donor element and a softening temperature of 300 ° C. to 950 ° C. (hereinafter sometimes simply referred to as “glass powder”), a dispersion medium And may further contain other additives as required in consideration of applicability and the like.
Here, the n-type diffusion layer forming composition contains a donor element. For example, after being applied to a silicon substrate, the n-type diffusion layer is formed by thermally diffusing the donor element by thermal diffusion treatment (firing). A material that can be formed. By using the n-type diffusion layer forming composition of the present invention, an n-type diffusion layer is formed only at a desired site to which the n-type diffusion layer forming composition is applied, and the n-type diffusion layer forming composition is applied. Unnecessary n-type diffusion layers are not formed on the back and side surfaces.
　したがって、本発明のｎ型拡散層形成組成物を適用すれば、従来広く採用されている気相反応法では必須のサイドエッチング工程が不要となり、工程が簡易化される。また、裏面に形成されたｎ型拡散層をｐ＋型拡散層へ変換する工程も不要となる。さらにそのため、裏面のｐ＋型拡散層の形成方法や、裏面電極の材質、形状及び厚さが制限されず、適用する製造方法や材質、形状の選択肢が広がる。また詳細については後述するが、裏面電極の厚さに起因したシリコン基板内の内部応力の発生が抑えられ、シリコン基板の反りも抑えられる。 Therefore, if the composition for forming an n-type diffusion layer of the present invention is applied, the side etching step that is essential in the gas phase reaction method that has been widely employed is not required, and the process is simplified. In addition, the step of converting the n-type diffusion layer formed on the back surface into the p + -type diffusion layer is not necessary. For this reason, the method for forming the p + -type diffusion layer on the back surface and the material, shape, and thickness of the back electrode are not limited, and the choice of manufacturing method, material, and shape to be applied is widened. Moreover, although mentioned later for details, generation | occurrence | production of the internal stress in the silicon substrate resulting from the thickness of a back surface electrode is suppressed, and the curvature of a silicon substrate is also suppressed.
　なお、本発明のｎ型拡散層形成組成物に含有されるガラス粉末は焼成により溶融し、ｎ型拡散層の上にガラス層を形成する。しかしながら従来の気相反応法やリン酸塩含有の溶液を塗布する方法においてもｎ型拡散層の上にガラス層が形成されている。よって本発明において生成したガラス層は、従来の方法と同様に、エッチングにより除去することができる。したがって本発明のｎ型拡散層形成組成物は、従来の方法と比べても不要な生成物を発生させず、工程を増やすこともない。 The glass powder contained in the n-type diffusion layer forming composition of the present invention is melted by firing to form a glass layer on the n-type diffusion layer. However, a glass layer is formed on the n-type diffusion layer also in the conventional gas phase reaction method and the method of applying a phosphate-containing solution. Therefore, the glass layer produced | generated in this invention can be removed by an etching similarly to the conventional method. Therefore, the n-type diffusion layer forming composition of the present invention does not generate unnecessary products and does not increase the number of steps as compared with the conventional method.
　また、ガラス粉末中のドナー成分は焼成中でも揮散しにくいため、揮散ガスの発生によって表面のみでなく裏面や側面にまでｎ型拡散層が形成されるということが抑制される。
この理由として、ドナー成分がガラス粉末中の元素と結合しているか、又はガラス中に取り込まれているため、揮散しにくいものと考えられる。 In addition, since the donor component in the glass powder is difficult to volatilize even during firing, it is suppressed that the n-type diffusion layer is formed not only on the surface but also on the back surface and side surfaces due to the generation of the volatilizing gas.
The reason for this is considered that the donor component is bonded to an element in the glass powder or is taken into the glass, so that it is difficult to volatilize.
　このように、本発明のｎ型拡散層形成組成物は、所望の部位に所望の濃度のｎ型拡散層を形成することが可能であることから、ｎ型ドーパント濃度の高い選択的な領域を形成することが可能となる。一方、ｎ型拡散層の一般的な方法である気相反応法や、リン酸塩含有溶液を用いる方法によってｎ型ドーパント濃度の高い選択的な領域を形成することは一般的には困難である。 Thus, since the n-type diffusion layer forming composition of the present invention can form an n-type diffusion layer having a desired concentration at a desired site, a selective region having a high n-type dopant concentration is formed. It becomes possible to form. On the other hand, it is generally difficult to form a selective region having a high n-type dopant concentration by a gas phase reaction method, which is a general method of an n-type diffusion layer, or a method using a phosphate-containing solution. .
　本発明に係るドナー元素を含むガラス粉末について、詳細に説明する。
　ドナー元素とは、シリコン基板中にドーピングさせることによってｎ型拡散層を形成することが可能な元素である。ドナー元素としては第１５族の元素が使用でき、例えばＰ（リン）、Ｓｂ（アンチモン）、Ｂｉ（ビスマス）及びＡｓ（ヒ素）等が挙げられる。安全性、ガラス化の容易さ等の観点から、Ｐ又はＳｂが好適である。 The glass powder containing the donor element according to the present invention will be described in detail.
A donor element is an element that can form an n-type diffusion layer by doping into a silicon substrate. As the donor element, a Group 15 element can be used, and examples thereof include P (phosphorus), Sb (antimony), Bi (bismuth), and As (arsenic). From the viewpoints of safety, ease of vitrification, etc., P or Sb is preferred.
　ドナー元素をガラス粉末に導入するために用いるドナー元素含有物質としては、Ｐ２Ｏ３、Ｐ２Ｏ５、Ｓｂ２Ｏ３、Ｂｉ２Ｏ３及びＡｓ２Ｏ３が挙げられ、Ｐ２Ｏ３、Ｐ２Ｏ５及びＳｂ２Ｏ３から選択される少なくとも１種を用いることが好ましい。 Examples of the donor element-containing material used for introducing the donor element into the glass powder include P 2 O 3 , P 2 O 5 , Sb 2 O 3 , Bi 2 O 3 and As 2 O 3 , and P 2 O 3 It is preferable to use at least one selected from P 2 O 5 and Sb 2 O 3 .
　また、ドナー元素を含むガラス粉末は、必要に応じて成分比率を調整することによって、溶融温度、軟化温度、ガラス転移温度、化学的耐久性等を制御することが可能である。更に以下に記す、ガラス成分物質を含むことが好ましい。
　ガラス成分物質としては、ＳｉＯ２、Ｋ２Ｏ、Ｎａ２Ｏ、Ｌｉ２Ｏ、ＢａＯ、ＳｒＯ、ＣａＯ、ＭｇＯ、ＢｅＯ、ＺｎＯ、ＰｂＯ、ＣｄＯ、ＳｎＯ、ＺｒＯ２、ＭｏＯ３、Ｌａ２Ｏ３、ＣｅＯ２、Ｎｂ２Ｏ５、Ｔａ２Ｏ５、Ｙ２Ｏ３、ＴｉＯ２、ＺｒＯ２、ＧｅＯ２、ＴｅＯ２及びＬｕ２Ｏ３等が挙げられ、ＳｉＯ２、Ｋ２Ｏ、Ｎａ２Ｏ、Ｌｉ２Ｏ、ＢａＯ、ＳｒＯ、ＣａＯ、ＭｇＯ、ＢｅＯ、ＺｎＯ、ＰｂＯ、ＣｄＯ、ＳｎＯ、ＺｒＯ２、ＣｅＯ２及びＭｏＯ３から選択される少なくとも１種を用いることが、好ましい。 Moreover, the glass powder containing a donor element can control a melting temperature, a softening temperature, a glass transition temperature, chemical durability, etc. by adjusting a component ratio as needed. Furthermore, it is preferable to contain the glass component substance described below.
Examples of glass component materials include SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , MoO 3 , La 2 O 3 , CeO 2, Nb 2 O 5, Ta 2 O 5, Y 2 O 3, TiO 2, ZrO 2, GeO 2, TeO 2 , and Lu 2 O 3 and the like, SiO 2, K 2 O, Na 2 O, It is preferable to use at least one selected from Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , CeO 2 and MoO 3 .
　ドナー元素を含むガラス粉末の具体例としては、前記ドナー元素含有物質と前記ガラス成分物質の双方を含む系が挙げられ、Ｐ２Ｏ５－ＳｉＯ２系（ドナー元素含有物質－ガラス成分物質の順で記載、以下同様）、Ｐ２Ｏ５－Ｋ２Ｏ系、Ｐ２Ｏ５－Ｎａ２Ｏ系、Ｐ２Ｏ５－Ｌｉ２Ｏ系、Ｐ２Ｏ５－ＢａＯ系、Ｐ２Ｏ５－ＳｒＯ系、Ｐ２Ｏ５－ＣａＯ系、Ｐ２Ｏ５－ＭｇＯ系、Ｐ２Ｏ５－ＢｅＯ系、Ｐ２Ｏ５－ＺｎＯ系、Ｐ２Ｏ５－ＣｄＯ系、Ｐ２Ｏ５－ＰｂＯ系、Ｐ２Ｏ５－ＣｅＯ２系、Ｐ２Ｏ５－ＳｎＯ系、Ｐ２Ｏ５－ＧｅＯ２系、Ｐ２Ｏ５－ＴｅＯ２系等のドナー元素含有物質としてＰ２Ｏ５を含む系、前記のＰ２Ｏ５を含む系のＰ２Ｏ５の代わりにドナー元素含有物質としてＳｂ２Ｏ３を含む系のガラス粉末が挙げられる。
　なお、Ｐ２Ｏ５－Ｓｂ２Ｏ３系、Ｐ２Ｏ５－Ａｓ２Ｏ３系等のように、２種類以上のドナー元素含有物質を含むガラス粉末でもよい。
　上記では２成分を含む複合ガラスを例示したが、Ｐ２Ｏ５－ＳｉＯ２－ＣｅＯ２、Ｐ２Ｏ５－ＳｉＯ２－ＣａＯ等のように、３成分以上の物質を含むガラス粉末でもよい。 Specific examples of the glass powder containing a donor element include a system containing both the donor element-containing substance and the glass component substance, and a P 2 O 5 -SiO 2 system (in order of donor element-containing substance-glass component substance). in described, the same applies hereinafter), P 2 O 5 -K 2 O based, P 2 O 5 -Na 2 O-based, P 2 O 5 -Li 2 O system, P 2 O 5 -BaO-based, P 2 O 5 - SrO-based, P 2 O 5 -CaO-based, P 2 O 5 -MgO-based, P 2 O 5 -BeO based, P 2 O 5 -ZnO-based, P 2 O 5 -CdO based, P 2 O 5 -PbO system A system containing P 2 O 5 as a donor element-containing substance, such as a P 2 O 5 —CeO 2 system, a P 2 O 5 —SnO system, a P 2 O 5 —GeO 2 system, or a P 2 O 5 —TeO 2 system, a donor element-containing material instead of P 2 O 5 of system containing P 2 O 5 of the Glass powder system containing sb 2 O 3 and the like.
Note that a glass powder containing two or more kinds of donor element-containing substances, such as a P 2 O 5 —Sb 2 O 3 system and a P 2 O 5 —As 2 O 3 system, may be used.
In the above, a composite glass containing two components has been exemplified, but glass powder containing three or more components such as P 2 O 5 —SiO 2 —CeO 2 or P 2 O 5 —SiO 2 —CaO may be used.
　ガラス粉末中のガラス成分物質の含有比率は、溶融温度、軟化温度、ガラス転移温度、結晶化温度、化学的耐久性を考慮して適宜設定することが望ましく、一般には、０．１質量％以上９５質量％以下であることが好ましく、０．５質量％以上９０質量％以下であることがより好ましい。 The content ratio of the glass component substance in the glass powder is preferably set appropriately in consideration of the melting temperature, softening temperature, glass transition temperature, crystallization temperature, chemical durability, and generally 0.1% by mass or more. It is preferably 95% by mass or less, and more preferably 0.5% by mass or more and 90% by mass or less.
　具体的には、Ｐ２Ｏ５－ＣｅＯ２系ガラスの場合には、ＣｅＯ２の含有比率は、１質量％以上５０質量％以下であることが好ましく、３質量％以上４０質量％以下であることがより好ましい。かかる含有比率であることで、より均一にｎ型拡散層を形成することができる。 Specifically, in the case of P 2 O 5 —CeO 2 -based glass, the content ratio of CeO 2 is preferably 1% by mass or more and 50% by mass or less, and more preferably 3% by mass or more and 40% by mass or less. It is more preferable. With such a content ratio, the n-type diffusion layer can be formed more uniformly.
　ガラス粉末の軟化温度は、後述する熱拡散処理時にドナー元素をより効果的にシリコン基板中へ拡散させ、より均一なｎ型拡散層を得る観点から重要である。本発明において軟化温度は３００℃～９５０℃であるが、３５０℃～９００℃であることが好ましく、３７０℃～８５０℃であることがより好ましく、３９０℃～８００℃であることがさらに好ましい。
　ガラス粉末の軟化温度が３００℃未満の場合には、高温での熱拡散処理時にガラス成分が結晶化し易くなり、熱拡散処理後のガラス成分のエッチング除去工程において、そのエッチング除去性が低下する傾向があり、また融点が低下することからドナー元素が揮発し易くなって、熱拡散処理時において不要な部分にｎ型拡散層を形成し易くなる傾向がある。また、ガラス粉末の軟化温度が９５０℃を超える場合には、熱拡散処理時にガラスが軟化し難くなり、ガラス粉末が粒状の形状を維持したままになる。そのためガラス成分がシリコン基板上において微視的に均一に覆われることなくドナー元素の拡散が進行することとなり、結果的にｎ型拡散層の形成性が不均一になる傾向があり、シート抵抗値が上昇することがある。
　なお、ガラス粉末の軟化温度は公知の示差熱分析装置（ＤＴＡ）によって、その吸熱ピークから容易に測定することができる。 The softening temperature of the glass powder is important from the viewpoint of obtaining a more uniform n-type diffusion layer by more effectively diffusing the donor element into the silicon substrate during the thermal diffusion treatment described later. In the present invention, the softening temperature is 300 ° C. to 950 ° C., preferably 350 ° C. to 900 ° C., more preferably 370 ° C. to 850 ° C., and further preferably 390 ° C. to 800 ° C.
When the softening temperature of the glass powder is less than 300 ° C., the glass component tends to crystallize during the thermal diffusion treatment at a high temperature, and the etching removability tends to decrease in the etching removal step of the glass component after the thermal diffusion treatment. In addition, since the melting point is lowered, the donor element is likely to volatilize and the n-type diffusion layer tends to be easily formed in an unnecessary portion during the thermal diffusion treatment. Moreover, when the softening temperature of glass powder exceeds 950 degreeC, it becomes difficult to soften glass at the time of a thermal-diffusion process, and the glass powder remains with the granular shape. Therefore, the diffusion of the donor element proceeds without the glass component being microscopically uniformly covered on the silicon substrate, and as a result, the formability of the n-type diffusion layer tends to be non-uniform, and the sheet resistance value May rise.
The softening temperature of the glass powder can be easily measured from its endothermic peak using a known differential thermal analyzer (DTA).
　また本発明において、ガラス粉末の結晶化温度は１０５０℃以上であることが好ましく、１１００℃以上であることがより好ましく、１２００℃以上であることがさらに好ましい。結晶化温度が１０５０℃以上であることで、熱拡散処理時におけるガラス成分の結晶化が抑制される。これにより、熱拡散処理後のガラス成分エッチング除去工程における結晶化物の残存が抑制され、ガラス成分のエッチング除去性が向上する。
　なお、ガラス粉末の結晶化温度は公知の示差熱分析装置（ＤＴＡ）によって、その発熱ピークから容易に測定することができる。 Moreover, in this invention, it is preferable that the crystallization temperature of glass powder is 1050 degreeC or more, It is more preferable that it is 1100 degreeC or more, It is further more preferable that it is 1200 degreeC or more. When the crystallization temperature is 1050 ° C. or higher, crystallization of the glass component during the thermal diffusion treatment is suppressed. Thereby, the residual of the crystallized substance in the glass component etching removal step after the thermal diffusion treatment is suppressed, and the etching removability of the glass component is improved.
In addition, the crystallization temperature of glass powder can be easily measured from the exothermic peak with a well-known differential thermal analyzer (DTA).
　ガラス粉末の形状としては、略球状、扁平状、ブロック状、板状及び鱗片状等が挙げられ、ｎ型拡散層形成組成物とした場合の基板への塗布性や均一拡散性の点から、略球状、扁平状又は板状であることが望ましい。ガラス粉末の粒径は、１００μｍ以下であることが望ましい。１００μｍ以下の粒径を有するガラス粉末を用いた場合には、平滑な塗膜が得られやすい。更に、ガラス粉末の粒径は５０μｍ以下であることがより望ましい。なお、下限は特に制限されないが、０．０１μｍ以上であることが好ましい。
　ここで、ガラスの粒径は、平均粒子径を表し、レーザー散乱回折法粒度分布測定装置等により測定することができる。 Examples of the shape of the glass powder include a substantially spherical shape, a flat shape, a block shape, a plate shape, a scale shape, and the like. From the viewpoint of the application property to the substrate and the uniform diffusibility when it is an n-type diffusion layer forming composition, It is desirable to have a substantially spherical shape, a flat shape, or a plate shape. The particle size of the glass powder is desirably 100 μm or less. When glass powder having a particle size of 100 μm or less is used, a smooth coating film is easily obtained. Furthermore, the particle size of the glass powder is more desirably 50 μm or less. The lower limit is not particularly limited, but is preferably 0.01 μm or more.
Here, the particle diameter of glass represents an average particle diameter, and can be measured by a laser scattering diffraction particle size distribution measuring apparatus or the like.
　ドナー元素を含むガラス粉末は、以下の手順で作製される。
　最初に原料を秤量し、るつぼに充填する。るつぼの材質としては白金、白金―ロジウム、イリジウム、アルミナ、石英、炭素等が挙げられるが、溶融温度、雰囲気、溶融物質との反応性等を考慮して適宜選ばれる。
　次に、電気炉でガラス組成に応じた温度で加熱し融液とする。このとき融液が均一となるよう攪拌することが望ましい。
　続いて得られた融液をグラファイト板、白金板、白金－ロジウム合金板、ジルコニア板等の上に流し出して融液をガラス化する。
　最後にガラスを粉砕し粉末状とする。粉砕にはジェットミル、ビーズミル、ボールミル等公知の方法が適用できる。 The glass powder containing a donor element is produced by the following procedure.
First, weigh the ingredients and fill the crucible. Examples of the material for the crucible include platinum, platinum-rhodium, iridium, alumina, quartz, carbon, and the like, and are appropriately selected in consideration of the melting temperature, atmosphere, reactivity with the molten material, and the like.
Next, it heats with the temperature according to a glass composition with an electric furnace, and is set as a melt. At this time, it is desirable to stir the melt uniformly.
Subsequently, the obtained melt is poured onto a graphite plate, a platinum plate, a platinum-rhodium alloy plate, a zirconia plate or the like to vitrify the melt.
Finally, the glass is crushed into powder. A known method such as a jet mill, a bead mill, or a ball mill can be applied to the pulverization.
　ｎ型拡散層形成組成物中のドナー元素を含むガラス粉末の含有比率は、塗布性、ドナー元素の拡散性等を考慮し決定される。一般には、ｎ型拡散層形成組成物中のガラス粉末の含有比率は、０．１質量％以上９５質量％以下であることが好ましく、１質量％以上９０質量％以下であることがより好ましく、１．５質量％以上８５質量％以下であることがさらに好ましく、２質量％以上８０質量％以下が特に好ましい。 The content ratio of the glass powder containing the donor element in the n-type diffusion layer forming composition is determined in consideration of the coating property, the diffusibility of the donor element, and the like. In general, the content ratio of the glass powder in the n-type diffusion layer forming composition is preferably 0.1% by mass or more and 95% by mass or less, more preferably 1% by mass or more and 90% by mass or less, The content is more preferably 1.5% by mass or more and 85% by mass or less, and particularly preferably 2% by mass or more and 80% by mass or less.
　次に、分散媒について説明する。
　分散媒とは、組成物中において上記ガラス粉末を分散させる媒体である。具体的に分散媒としては、バインダーや溶剤などが採用される。 Next, the dispersion medium will be described.
The dispersion medium is a medium in which the glass powder is dispersed in the composition. Specifically, a binder, a solvent, or the like is employed as the dispersion medium.
　バインダーとしては、例えば、ポリビニルアルコール、ポリアクリルアミド類、ポリビニルアミド類、ポリビニルピロリドン、ポリエチレンオキサイド類、ポリスルホン酸、アクリルアミドアルキルスルホン酸、セルロースエーテル類、セルロース誘導体、カルボキシメチルセルロース、ヒドロキシエチルセルロース、エチルセルロース、ゼラチン、澱粉及び澱粉誘導体、アルギン酸ナトリウム類、キサンタン、グア及びグア誘導体、スクレログルカン及びスクレログルカン誘導体、トラガカント及びトラガカント誘導体、デキストリン及びデキストリン誘導体、（メタ）アクリル酸樹脂、（メタ）アクリル酸エステル樹脂（例えば、アルキル（メタ）アクリレート樹脂、ジメチルアミノエチル（メタ）アクリレート樹脂等）、ブタジエン樹脂、スチレン樹脂、又はこれらの共重合体、他にも、シロキサン樹脂を適宜選択しうる。これらは１種類を単独で又は２種類以上を組み合わせて使用される。 Examples of the binder include polyvinyl alcohol, polyacrylamides, polyvinylamides, polyvinylpyrrolidone, polyethylene oxides, polysulfonic acid, acrylamide alkylsulfonic acid, cellulose ethers, cellulose derivatives, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, gelatin, starch And starch derivatives, sodium alginates, xanthan, gua and gua derivatives, scleroglucan and scleroglucan derivatives, tragacanth and tragacanth derivatives, dextrin and dextrin derivatives, (meth) acrylic acid resins, (meth) acrylic acid ester resins (e.g. , Alkyl (meth) acrylate resins, dimethylaminoethyl (meth) acrylate resins, etc.), butadiene Fat, styrene resins, copolymers thereof, Additional be appropriately selected siloxane resin. These are used singly or in combination of two or more.
　バインダーの分子量は特に制限されず、組成物としての所望の粘度を鑑みて適宜調整することが望ましい。 The molecular weight of the binder is not particularly limited, and it is desirable to adjust appropriately in view of the desired viscosity as the composition.
　溶剤としては、例えば、アセトン、メチルエチルケトン、メチル－ｎ－プロピルケトン、メチル－ｉｓｏ－プロピルケトン、メチル－ｎ－ブチルケトン、メチル－ｉｓｏ－ブチルケトン、メチル－ｎ－ペンチルケトン、メチル－ｎ－ヘキシルケトン、ジエチルケトン、ジプロピルケトン、ジ－ｉｓｏ－ブチルケトン、トリメチルノナノン、シクロヘキサノン、シクロペンタノン、メチルシクロヘキサノン、２，４－ペンタンジオン、アセトニルアセトン等のケトン系溶剤；ジエチルエーテル、メチルエチルエーテル、メチル－ｎ－プロピルエーテル、ジ－ｉｓｏ－プロピルエーテル、テトラヒドロフラン、メチルテトラヒドロフラン、ジオキサン、ジメチルジオキサン、エチレングリコールジメチルエーテル、エチレングリコールジエチルエーテル、エチレングリコールジ－ｎ－プロピルエーテル、エチレングリコールジブチルエーテル、ジエチレングリコールジメチルエーテル、ジエチレングリコールジエチルエーテル、ジエチレングリコールメチルエチルエーテル、ジエチレングリコールメチル－ｎ－プロピルエーテル、ジエチレングリコールメチル－ｎ－ブチルエーテル、ジエチレングリコールジ－ｎ－プロピルエーテル、ジエチレングリコールジ－ｎ－ブチルエーテル、ジエチレングリコールメチル－ｎ－ヘキシルエーテル、トリエチレングリコールジメチルエーテル、トリエチレングリコールジエチルエーテル、トリエチレングリコールメチルエチルエーテル、トリエチレングリコールメチル－ｎ－ブチルエーテル、トリエチレングリコールジ－ｎ－ブチルエーテル、トリエチレングリコールメチル－ｎ－ヘキシルエーテル、テトラエチレングリコールジメチルエーテル、テトラエチレングリコールジエチルエーテル、テトラジエチレングリコールメチルエチルエーテル、テトラエチレングリコールメチル－ｎ－ブチルエーテル、ジエチレングリコールジ－ｎ－ブチルエーテル、テトラエチレングリコールメチル－ｎ－ヘキシルエーテル、テトラエチレングリコールジ－ｎ－ブチルエーテル、プロピレングリコールジメチルエーテル、プロピレングリコールジエチルエーテル、プロピレングリコールジ－ｎ－プロピルエーテル、プロピレングリコールジブチルエーテル、ジプロピレングリコールジメチルエーテル、ジプロピレングリコールジエチルエーテル、ジプロピレングリコールメチルエチルエーテル、ジプロピレングリコールメチル－ｎ－ブチルエーテル、ジプロピレングリコールジ－ｎ－プロピルエーテル、ジプロピレングリコールジ－ｎ－ブチルエーテル、ジプロピレングリコールメチル－ｎ－ヘキシルエーテル、トリプロピレングリコールジメチルエーテル、トリプロピレングリコールジエチルエーテル、トリプロピレングリコールメチルエチルエーテル、トリプロピレングリコールメチル－ｎ－ブチルエーテル、トリプロピレングリコールジ－ｎ－ブチルエーテル、トリプロピレングリコールメチル－ｎ－ヘキシルエーテル、テトラプロピレングリコールジメチルエーテル、テトラプロピレングリコールジエチルエーテル、テトラジプロピレングリコールメチルエチルエーテル、テトラプロピレングリコールメチル－ｎ－ブチルエーテル、ジプロピレングリコールジ－ｎ－ブチルエーテル、テトラプロピレングリコールメチル－ｎ－ヘキシルエーテル、テトラプロピレングリコールジ－ｎ－ブチルエーテル等のエーテル系溶剤；酢酸メチル、酢酸エチル、酢酸ｎ－プロピル、酢酸ｉ－プロピル、酢酸ｎ－ブチル、酢酸ｉ－ブチル、酢酸ｓｅｃ－ブチル、酢酸ｎ－ペンチル、酢酸ｓｅｃ－ペンチル、酢酸３－メトキシブチル、酢酸メチルペンチル、酢酸２－エチルブチル、酢酸２－エチルヘキシル、酢酸２－（２－ブトキシエトキシ）エチル、酢酸ベンジル、酢酸シクロヘキシル、酢酸メチルシクロヘキシル、酢酸ノニル、アセト酢酸メチル、アセト酢酸エチル、酢酸ジエチレングリコールメチルエーテル、酢酸ジエチレングリコールモノエチルエーテル、酢酸ジエチレングリコール－ｎ－ブチルエーテル、酢酸ジプロピレングリコールメチルエーテル、酢酸ジプロピレングリコールエチルエーテル、ジ酢酸グリコール、酢酸メトキシトリグリコール、プロピオン酸エチル、プロピオン酸ｎ－ブチル、プロピオン酸ｉ－アミル、シュウ酸ジエチル、シュウ酸ジ－ｎ－ブチル、乳酸メチル、乳酸エチル、乳酸ｎ－ブチル、乳酸ｎ－アミル、エチレングリコールメチルエーテルプロピオネート、エチレングリコールエチルエーテルプロピオネート、エチレングリコールメチルエーテルアセテート、エチレングリコールエチルエーテルアセテート、ジエチレングリコールメチルエーテルアセテート、ジエチレングリコールエチルエーテルアセテート、ジエチレングリコール－ｎ－ブチルエーテルアセテート、プロピレングリコールメチルエーテルアセテート、プロピレングリコールエチルエーテルアセテート、プロピレングリコールプロピルエーテルアセテート、ジプロピレングリコールメチルエーテルアセテート、ジプロピレングリコールエチルエーテルアセテート、γ－ブチロラクトン、γ－バレロラクトン等のエステル系溶剤；アセトニトリル、Ｎ－メチルピロリジノン、Ｎ－エチルピロリジノン、Ｎ－プロピルピロリジノン、Ｎ－ブチルピロリジノン、Ｎ－ヘキシルピロリジノン、Ｎ－シクロヘキシルピロリジノン、Ｎ，Ｎ－ジメチルホルムアミド、Ｎ，Ｎ－ジメチルアセトアミド、ジメチルスルホキシド等の非プロトン性極性溶剤；メタノール、エタノール、ｎ－プロパノール、ｉ－プロパノール、ｎ－ブタノール、ｉ－ブタノール、ｓｅｃ－ブタノール、ｔ－ブタノール、ｎ－ペンタノール、ｉ－ペンタノール、２－メチルブタノール、ｓｅｃ－ペンタノール、ｔ－ペンタノール、３－メトキシブタノール、ｎ－ヘキサノール、２－メチルペンタノール、ｓｅｃ－ヘキサノール、２－エチルブタノール、ｓｅｃ－ヘプタノール、ｎ－オクタノール、２－エチルヘキサノール、ｓｅｃ－オクタノール、ｎ－ノニルアルコール、ｎ－デカノール、ｓｅｃ－ウンデシルアルコール、トリメチルノニルアルコール、ｓｅｃ－テトラデシルアルコール、ｓｅｃ－ヘプタデシルアルコール、フェノール、シクロヘキサノール、メチルシクロヘキサノール、ベンジルアルコール、エチレングリコール、１，２－プロピレングリコール、１，３－ブチレングリコール、ジエチレングリコール、ジプロピレングリコール、トリエチレングリコール、トリプロピレングリコール等のアルコール系溶剤；エチレングリコールメチルエーテル、エチレングリコールエチルエーテル、エチレングリコールモノフェニルエーテル、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノエチルエーテル、ジエチレングリコールモノ－ｎ－ブチルエーテル、ジエチレングリコールモノ－ｎ－ヘキシルエーテル、エトキシトリグリコール、テトラエチレングリコールモノ－ｎ－ブチルエーテル、プロピレングリコールモノメチルエーテル、ジプロピレングリコールモノメチルエーテル、ジプロピレングリコールモノエチルエーテル、トリプロピレングリコールモノメチルエーテル等のグリコールモノエーテル系溶剤；α－テルピネン、α－テルピネオール、ミルセン、アロオシメン、リモネン、ジペンテン、α－ピネン、β－ピネン、ターピネオール、カルボン、オシメン、フェランドレン等のテルペン系溶剤；水が挙げられる。これらは１種類を単独で又は２種類以上を組み合わせて使用される。
　ｎ型拡散層形成組成物とした場合、基板への塗布性の観点から、α－テルピネオール、ジエチレングリコールモノ－ｎ－ブチルエーテル、酢酸２－（２－ブトキシエトキシ）エチルが好ましい。 Examples of the solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-iso-propyl ketone, methyl-n-butyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, methyl-n-hexyl ketone, Ketone solvents such as diethyl ketone, dipropyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone; diethyl ether, methyl ethyl ether, methyl -N-propyl ether, di-iso-propyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether Ter, ethylene glycol di-n-propyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl n-propyl ether, diethylene glycol methyl n-butyl ether, diethylene glycol di-n-propyl ether , Diethylene glycol di-n-butyl ether, diethylene glycol methyl n-hexyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol methyl n-butyl ether, triethylene glycol di-n- Butyl ether, G Ethylene glycol methyl-n-hexyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetradiethylene glycol methyl ethyl ether, tetraethylene glycol methyl n-butyl ether, diethylene glycol di-n-butyl ether, tetraethylene glycol methyl n-hexyl Ether, tetraethylene glycol di-n-butyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol dibutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol methyl ethyl Ether, zip Lopylene glycol methyl-n-butyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl-n-hexyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene Glycol methyl ethyl ether, tripropylene glycol methyl-n-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl-n-hexyl ether, tetrapropylene glycol dimethyl ether, tetrapropylene glycol diethyl ether, tetradipropylene glycol methyl ethyl Ether, tetrapropylene glycol methyl-n-butyl ether Ether solvents such as dipropylene glycol di-n-butyl ether, tetrapropylene glycol methyl-n-hexyl ether, tetrapropylene glycol di-n-butyl ether; methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, acetic acid n-butyl, i-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, 2- (2- Butoxyethoxy) ethyl, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, diethylene glycol methyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycoacetate Ru-n-butyl ether, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl ether acetate, diacetic acid glycol, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, sulphate Di-n-butyl acid, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, ethylene glycol methyl ether propionate, ethylene glycol ethyl ether propionate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate , Diethylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol-n-butyl ether acetate, propylene glycol Ester solvents such as rumethyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl ether acetate, γ-butyrolactone, γ-valerolactone; acetonitrile, N-methyl Aprotic polar solvents such as pyrrolidinone, N-ethylpyrrolidinone, N-propylpyrrolidinone, N-butylpyrrolidinone, N-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide Methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t -Butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethyl Butanol, sec-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, Phenol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, diethylene glycol, dipropylene glycol Alcohol solvents such as triethylene glycol and tripropylene glycol; ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-n -Glycol monoether solvents such as hexyl ether, ethoxytriglycol, tetraethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether; α- Terpinene, α-terpineol, Mi It includes water; Sen, alloocimene, limonene, dipentene, alpha-pinene, beta-pinene, terpineol, carvone, ocimene, terpene solvent such as phellandrene. These are used singly or in combination of two or more.
In the case of an n-type diffusion layer forming composition, α-terpineol, diethylene glycol mono-n-butyl ether, and 2- (2-butoxyethoxy) ethyl acetate are preferred from the viewpoint of applicability to the substrate.
　ｎ型拡散層形成組成物中の分散媒の含有比率は、塗布性、ドナー濃度を考慮し決定される。
　ｎ型拡散層形成組成物の粘度は、塗布性を考慮して、１０ｍＰａ・ｓ以上１００００００ｍＰａ・ｓ以下であることが好ましく、５０ｍＰａ・ｓ以上５０００００ｍＰａ・ｓ以下であることがより好ましい。 The content ratio of the dispersion medium in the n-type diffusion layer forming composition is determined in consideration of applicability and donor concentration.
The viscosity of the n-type diffusion layer forming composition is preferably 10 mPa · s or more and 1000000 mPa · s or less, and more preferably 50 mPa · s or more and 500000 mPa · s or less in consideration of applicability.
　次に、本発明のｎ型拡散層及び太陽電池素子の製造方法について、図１を参照しながら説明する。図１は、本発明の太陽電池素子の製造工程の一例を概念的に表す模式断面図である。以降の図面においては、共通する構成要素に同じ符号を付す。 Next, a method for manufacturing the n-type diffusion layer and solar cell element of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view conceptually showing an example of the manufacturing process of the solar cell element of the present invention. In the subsequent drawings, common constituent elements are denoted by the same reference numerals.
　図１（１）では、ｐ型半導体基板１０であるシリコン基板にアルカリ溶液を付与してダメージ層を除去し、テクスチャー構造をエッチングにて得る。
　詳細には、インゴットからスライスした際に発生するシリコン表面のダメージ層を２０質量％苛性ソーダで除去する。次いで１質量％苛性ソーダと１０質量％イソプロピルアルコールの混合液によりエッチングを行い、テクスチャー構造を形成する（図中ではテクスチャー構造の記載を省略する）。太陽電池素子は、受光面（表面）側にテクスチャー構造を形成することにより、光閉じ込め効果が促され、高効率化が図られる。 In FIG. 1A, an alkaline solution is applied to a silicon substrate which is a p-type semiconductor substrate 10 to remove a damaged layer, and a texture structure is obtained by etching.
Specifically, the damaged layer on the silicon surface generated when slicing from the ingot is removed with 20% by mass caustic soda. Next, etching is performed with a mixed solution of 1% by mass caustic soda and 10% by mass isopropyl alcohol to form a texture structure (the description of the texture structure is omitted in the figure). In the solar cell element, by forming a texture structure on the light receiving surface (surface) side, a light confinement effect is promoted, and high efficiency is achieved.
　図１（２）では、ｐ型半導体基板１０の表面すなわち受光面となる面に、上記ｎ型拡散層形成組成物を塗布して、ｎ型拡散層形成組成物層１１を形成する。本発明では、塗布方法には制限がないが、例えば、印刷法、スピン法、刷毛塗り、スプレー法、ドクターブレード法、ロールコーター法、インクジェット法などがある。
　上記ｎ型拡散層形成組成物の塗布量としては特に制限はない。例えば、ガラス粉末量として０．０１ｇ／ｍ２～１００ｇ／ｍ２とすることができ、０．１ｇ／ｍ２～１０ｇ／ｍ２であることが好ましい。 In FIG. 1B, the n-type diffusion layer forming composition layer 11 is formed by applying the n-type diffusion layer forming composition to the surface of the p-type semiconductor substrate 10, that is, the surface that becomes the light receiving surface. In the present invention, the coating method is not limited, and examples thereof include a printing method, a spin method, a brush coating, a spray method, a doctor blade method, a roll coater method, and an ink jet method.
There is no restriction | limiting in particular as an application quantity of the said n type diffused layer formation composition. For example, the glass powder amount can be 0.01 g / m 2 to 100 g / m 2, and preferably 0.1 g / m 2 to 10 g / m 2 .
　なお、ｎ型拡散層形成組成物の組成によっては、塗布後に、組成物中に含まれる溶剤を揮発させるための乾燥工程を設けてもよい。この場合には、８０℃～３００℃程度の温度で、ホットプレートを使用する場合は１分～１０分、乾燥機などを用いる場合は１０分～３０分程度で乾燥させる。この乾燥条件は、ｎ型拡散層形成組成物の溶剤組成に依存しており、本発明では特に上記条件に限定されない。 Depending on the composition of the n-type diffusion layer forming composition, a drying step for volatilizing the solvent contained in the composition may be provided after coating. In this case, drying is performed at a temperature of about 80 ° C. to 300 ° C. for about 1 to 10 minutes when using a hot plate, and about 10 to 30 minutes when using a dryer or the like. The drying conditions depend on the solvent composition of the n-type diffusion layer forming composition, and are not particularly limited to the above conditions in the present invention.
　また、本発明の製造方法を用いる場合には、裏面のｐ＋型拡散層（高濃度電界層）１４の製造方法はアルミニウムによるｎ型拡散層からｐ型拡散層への変換による方法に限定されることなく、従来公知のいずれの方法も採用でき、製造方法の選択肢が広がる。したがって、例えば、Ｂ（ボロン）などの第１３族の元素を含む組成物を付与して組成物層１３を形成し、高濃度電界層１４を形成することができる。 Further, when the manufacturing method of the present invention is used, the manufacturing method of the p + -type diffusion layer (high concentration electric field layer) 14 on the back surface is limited to a method by conversion from an n-type diffusion layer to a p-type diffusion layer with aluminum. Therefore, any conventionally known method can be adopted, and the options of the manufacturing method are expanded. Therefore, for example, the composition layer 13 can be formed by applying a composition containing a Group 13 element such as B (boron), and the high concentration electric field layer 14 can be formed.
　前記Ｂ（ボロン）等の第１３族の元素を含む組成物１３としては、例えば、ドナー元素を含むガラス粉末の代わりにアクセプタ元素を含むガラス粉末を用いて、ｎ型拡散層形成組成物と同様にして構成されるｐ型拡散層形成組成物を挙げることができる。アクセプタ元素は第１３族の元素であればよく、例えば、Ｂ（ボロン）、Ａｌ（アルミニウム）及びＧａ（ガリウム）等を挙げることができる。またアクセプタ元素を含むガラス粉末はＢ２Ｏ３、Ａｌ２Ｏ３及びＧａ２Ｏ３から選択される少なくとも１種を含むことが好ましい。
　さらにｐ型拡散層形成組成物をシリコン基板の裏面に付与する方法は、既述のｎ型拡散層形成組成物をシリコン基板上に塗布する方法と同様である。
　裏面に付与されたｐ型拡散層形成組成物を、後述するｎ型拡散層形成組成物における熱拡散処理と同様に熱拡散処理することで、裏面に高濃度電界層１４を形成することができる。尚、ｐ型拡散層形成組成物の熱拡散処理は、ｎ型拡散層形成組成物の熱拡散処理と同時に行なうことが好ましい。 As the composition 13 containing a Group 13 element such as B (boron), for example, a glass powder containing an acceptor element is used instead of a glass powder containing a donor element, and the same as the composition for forming an n-type diffusion layer. A p-type diffusion layer forming composition constituted as described above can be given. The acceptor element may be an element belonging to Group 13, and examples thereof include B (boron), Al (aluminum), and Ga (gallium). The glass powder containing acceptor element preferably comprises at least one selected from B 2 O 3, Al 2 O 3 and Ga 2 O 3.
Furthermore, the method for applying the p-type diffusion layer forming composition to the back surface of the silicon substrate is the same as the method for applying the n-type diffusion layer forming composition described above on the silicon substrate.
The high-concentration electric field layer 14 can be formed on the back surface by subjecting the p-type diffusion layer forming composition applied to the back surface to a thermal diffusion treatment similar to the thermal diffusion treatment in the n-type diffusion layer forming composition described later. . The thermal diffusion treatment of the p-type diffusion layer forming composition is preferably performed simultaneously with the thermal diffusion treatment of the n-type diffusion layer forming composition.
　次いで、上記ｎ型拡散層形成組成物層１１を形成した半導体基板１０を、６００℃～１２００℃で熱拡散処理する。この熱拡散処理により、図１（３）に示すように半導体基板中へドナー元素が拡散し、ｎ型拡散層１２が形成される。熱拡散処理には公知の連続炉、バッチ炉等が適用できる。また、熱拡散処理時の炉内雰囲気は、必要に応じて、空気、酸素、窒素等に適宜調整することもできる。
　熱拡散処理時間は、ｎ型拡散層形成組成物に含まれるドナー元素含有率や、ガラス粉末の軟化温度等に応じて適宜選択することができる。例えば、１分間～６０分間とすることができ、２分間～３０分間であることがより好ましい。 Next, the semiconductor substrate 10 on which the n-type diffusion layer forming composition layer 11 is formed is subjected to thermal diffusion treatment at 600 ° C. to 1200 ° C. By this thermal diffusion treatment, as shown in FIG. 1C, the donor element diffuses into the semiconductor substrate, and the n-type diffusion layer 12 is formed. A known continuous furnace, batch furnace, or the like can be applied to the thermal diffusion treatment. Further, the furnace atmosphere during the thermal diffusion treatment can be appropriately adjusted to air, oxygen, nitrogen or the like as necessary.
The thermal diffusion treatment time can be appropriately selected according to the donor element content contained in the n-type diffusion layer forming composition, the softening temperature of the glass powder, and the like. For example, it can be 1 minute to 60 minutes, and more preferably 2 minutes to 30 minutes.
　形成されたｎ型拡散層１２の表面には、リン酸ガラスなどのガラス層（不図示）が形成されているため、このガラス層をエッチングにより除去する。エッチングとしては、ふっ酸等の酸に浸漬する方法、苛性ソーダ等のアルカリに浸漬する方法など公知の方法が適用できる。 Since a glass layer (not shown) such as phosphate glass is formed on the surface of the formed n-type diffusion layer 12, this glass layer is removed by etching. As the etching, a known method such as a method of immersing in an acid such as hydrofluoric acid or a method of immersing in an alkali such as caustic soda can be applied.
　図１（２）及び（３）に示される、本発明のｎ型拡散層形成組成物層１１を用いてｎ型拡散層１２を形成する本発明のｎ型拡散層の形成方法では、所望の部位にのみｎ型拡散層１２が形成され、裏面や側面には不要なｎ型拡散層が形成されない。
　したがって、従来広く採用されている気相反応法によりｎ型拡散層を形成する方法では、側面に形成された不要なｎ型拡散層を除去するためのサイドエッチング工程が必須であったが、本発明の製造方法によれば、サイドエッチング工程が不要となり、工程が簡易化される。 1 (2) and (3), the n-type diffusion layer 12 is formed using the n-type diffusion layer forming composition layer 11 of the present invention. The n-type diffusion layer 12 is formed only at the site, and an unnecessary n-type diffusion layer is not formed on the back surface or the side surface.
Therefore, in the conventional method of forming an n-type diffusion layer by a gas phase reaction method, a side etching process for removing an unnecessary n-type diffusion layer formed on a side surface is essential. According to the manufacturing method of the invention, the side etching process is not required, and the process is simplified.
　また、従来の製造方法では、裏面に形成された不要なｎ型拡散層をｐ型拡散層へ変換する必要があり、この変換方法としては、裏面のｎ型拡散層に、第１３族元素であるアルミニウムのペーストを塗布、焼成し、ｎ型拡散層にアルミニウムを拡散させてｐ型拡散層へ変換する方法が採用されている。この方法においてｐ型拡散層への変換を充分なものとし、更にｐ＋型拡散層の高濃度電界層を形成するためには、ある程度以上のアルミニウム量が必要であることから、アルミニウム層を厚く形成する必要があった。しかしながら、アルミニウムの熱膨張率は、基板として用いるシリコンの熱膨張率と大きく異なることから、焼成及び冷却の過程でシリコン基板中に大きな内部応力を発生させ、シリコン基板の反りの原因となっていた。
　この内部応力は、結晶の結晶粒界に損傷を与え、電力損失が大きくなるという課題があった。また、反りは、モジュール工程における太陽電池素子の搬送や、タブ線と呼ばれる銅線との接続において、太陽電池素子を破損させ易くしていた。近年では、スライス加工技術の向上から、シリコン基板の厚みが薄型化されつつあり、更に太陽電池素子が割れ易い傾向にある。 Further, in the conventional manufacturing method, it is necessary to convert an unnecessary n-type diffusion layer formed on the back surface into a p-type diffusion layer. As this conversion method, a group 13 element is added to the n-type diffusion layer on the back surface. A method is adopted in which an aluminum paste is applied and baked to diffuse aluminum into the n-type diffusion layer and convert it into a p-type diffusion layer. In this method, conversion to the p-type diffusion layer is sufficient, and in order to form a high-concentration electric field layer of the p + -type diffusion layer, a certain amount of aluminum is required. There was a need to form. However, since the thermal expansion coefficient of aluminum is significantly different from that of silicon used as a substrate, a large internal stress is generated in the silicon substrate during the firing and cooling process, causing warpage of the silicon substrate. .
This internal stress has a problem that the crystal grain boundary is damaged and the power loss increases. Further, the warpage easily damages the solar cell element in the transportation of the solar cell element in the module process and the connection with a copper wire called a tab wire. In recent years, the thickness of the silicon substrate has been reduced due to the improvement of the slice processing technique, and the solar cell element tends to be easily broken.
　しかし本発明の製造方法によれば、裏面に不要なｎ型拡散層が形成されないことから、ｎ型拡散層からｐ型拡散層への変換を行う必要がなくなり、アルミニウム層を厚くする必然性がなくなる。その結果、シリコン基板内の内部応力の発生や反りを抑えることができる。結果として、電力損失の増大や、太陽電池素子の破損を抑えることが可能となる。 However, according to the manufacturing method of the present invention, since an unnecessary n-type diffusion layer is not formed on the back surface, it is not necessary to perform conversion from the n-type diffusion layer to the p-type diffusion layer, and the necessity of increasing the thickness of the aluminum layer is eliminated. . As a result, generation of internal stress and warpage in the silicon substrate can be suppressed. As a result, it is possible to suppress an increase in power loss and damage to the solar cell element.
　また、本発明の製造方法を用いる場合には、裏面のｐ＋型拡散層（高濃度電界層）１４の製造方法はアルミニウムによるｎ型拡散層からｐ型拡散層への変換による方法に限定されることなく、従来公知のいずれの方法も採用でき、製造方法の選択肢が広がる。
　例えば、ドナー元素を含むガラス粉末の代わりにアクセプタ元素を含むガラス粉末を用いて、ｎ型拡散層形成組成物と同様にして構成されるｐ型拡散層形成組成物を、シリコン基板の裏面（ｎ型拡散層形成組成物を塗布した面とは反対側の面）に塗布し、焼成処理することで、裏面にｐ＋型拡散層（高濃度電界層）１４を形成することが好ましい。
　また後述するように、裏面の表面電極２０に用いる材料は第１３族のアルミニウムに限定されず、例えばＡｇ（銀）やＣｕ（銅）などを適用することができ、裏面の表面電極２０の厚さも従来のものよりも薄く形成することが可能となる。 Further, when the manufacturing method of the present invention is used, the manufacturing method of the p + -type diffusion layer (high concentration electric field layer) 14 on the back surface is limited to a method by conversion from an n-type diffusion layer to a p-type diffusion layer with aluminum. Therefore, any conventionally known method can be adopted, and the options of the manufacturing method are expanded.
For example, using a glass powder containing an acceptor element instead of a glass powder containing a donor element, a p-type diffusion layer forming composition configured in the same manner as the n-type diffusion layer forming composition is formed on the back surface (n The p + -type diffusion layer (high-concentration electric field layer) 14 is preferably formed on the back surface by applying to the surface opposite to the surface on which the mold diffusion layer forming composition is applied and baking.
As will be described later, the material used for the back surface electrode 20 is not limited to Group 13 aluminum, and for example, Ag (silver), Cu (copper), or the like can be applied. In addition, it can be formed thinner than the conventional one.
　図１（４）では、ｎ型拡散層１２の上に反射防止膜１６を形成する。反射防止膜１６は公知の技術を適用して形成される。例えば、反射防止膜１６がシリコン窒化膜の場合には、ＳｉＨ４とＮＨ３の混合ガスを原料とするプラズマＣＶＤ法により形成する。このとき、水素が結晶中に拡散し、シリコン原子の結合に寄与しない軌道、即ちダングリングボンドと水素が結合し、欠陥を不活性化（水素パッシベーション）する。
　より具体的には、上記混合ガス流量比ＮＨ３／ＳｉＨ４が０．０５～１．０、反応室の圧力が０．１Ｔｏｒｒ～２Ｔｏｒｒ、成膜時の温度が３００℃～５５０℃、プラズマの放電のための周波数が１００ｋＨｚ以上の条件下で形成される。 In FIG. 1 (4), an antireflection film 16 is formed on the n-type diffusion layer 12. The antireflection film 16 is formed by applying a known technique. For example, when the antireflection film 16 is a silicon nitride film, it is formed by a plasma CVD method using a mixed gas of SiH 4 and NH 3 as a raw material. At this time, hydrogen diffuses into the crystal, and orbits that do not contribute to the bonding of silicon atoms, that is, dangling bonds and hydrogen are combined to inactivate defects (hydrogen passivation).
More specifically, the mixed gas flow ratio NH 3 / SiH 4 is 0.05 to 1.0, the reaction chamber pressure is 0.1 Torr to 2 Torr, the temperature during film formation is 300 ° C. to 550 ° C., It is formed under the condition that the frequency for discharge is 100 kHz or more.
　図１（５）では、表面（受光面）の反射防止膜１６上に、表面電極用金属ペーストをスクリーン印刷法で印刷塗布乾燥させ、表面電極１８を形成する。表面電極用金属ペーストは、（１）金属粒子と（２）ガラス粒子とを必須成分とし、必要に応じて（３）樹脂バインダー、（４）その他の添加剤などを含む。 In FIG. 1 (5), a surface electrode metal paste is printed, applied and dried by a screen printing method on the antireflection film 16 on the surface (light receiving surface) to form the surface electrode 18. The metal paste for a surface electrode contains (1) metal particles and (2) glass particles as essential components, and includes (3) a resin binder and (4) other additives as necessary.
　次いで、上記裏面の高濃度電界層１４上にも裏面電極２０を形成する。前述のように、本発明では裏面電極２０の材質や形成方法は特に限定されない。例えば、アルミニウム、銀、銅等の金属を含む裏面電極用ペーストを塗布し、乾燥させて、裏面電極２０を形成してもよい。このとき、裏面にも、モジュール工程における太陽電池素子間の接続のために、一部に銀電極形成用銀ペーストを設けてもよい。 Next, the back electrode 20 is also formed on the high-concentration electric field layer 14 on the back surface. As described above, in the present invention, the material and forming method of the back electrode 20 are not particularly limited. For example, the back electrode 20 may be formed by applying and drying a back electrode paste containing a metal such as aluminum, silver, or copper. At this time, a silver paste for forming a silver electrode may be partially provided on the back surface for connection between solar cell elements in the module process.
　図１（６）では、電極を焼成して、太陽電池素子を完成させる。６００℃～９００℃の範囲で数秒～数分間焼成すると、表面側では電極用金属ペーストに含まれるガラス粒子によって絶縁膜である反射防止膜１６が溶融し、更にシリコン１０表面も一部溶融して、ペースト中の金属粒子（例えば銀粒子）がシリコン基板１０と接触部を形成し凝固する。これにより、形成した表面電極１８とシリコン基板１０とが導通される。これはファイアースルーと称されている。 In FIG. 1 (6), the electrode is fired to complete the solar cell element. When fired in the range of 600 ° C. to 900 ° C. for several seconds to several minutes, the antireflection film 16 as an insulating film is melted by the glass particles contained in the electrode metal paste on the surface side, and the silicon 10 surface is also partially melted. The metal particles (for example, silver particles) in the paste form a contact portion with the silicon substrate 10 and solidify. Thereby, the formed surface electrode 18 and the silicon substrate 10 are electrically connected. This is called fire-through.
　表面電極１８の形状について説明する。表面電極１８は、バスバー電極３０、及び該バスバー電極３０と交差しているフィンガー電極３２で構成される。図２（Ａ）は、表面電極１８を、バスバー電極３０、及び該バスバー電極３０と交差しているフィンガー電極３２からなる構成とした太陽電池素子を表面から見た平面図であり、図２（Ｂ）は、図２（Ａ）の一部を拡大して示す斜視図である。 The shape of the surface electrode 18 will be described. The surface electrode 18 includes a bus bar electrode 30 and finger electrodes 32 intersecting with the bus bar electrode 30. FIG. 2A is a plan view of a solar cell element in which the surface electrode 18 includes a bus bar electrode 30 and a finger electrode 32 intersecting with the bus bar electrode 30 as viewed from the surface. FIG. 2B is a perspective view showing a part of FIG.
　このような表面電極１８は、例えば、上述の金属ペーストのスクリーン印刷、又は電極材料のメッキ、高真空中における電子ビーム加熱による電極材料の蒸着などの手段により形成することができる。バスバー電極３０とフィンガー電極３２とからなる表面電極１８は受光面側の電極として一般的に用いられていて周知であり、受光面側のバスバー電極及びフィンガー電極の公知の形成手段を適用することができる。 Such a surface electrode 18 can be formed, for example, by means such as screen printing of the above-described metal paste, plating of the electrode material, or vapor deposition of the electrode material by electron beam heating in a high vacuum. The surface electrode 18 composed of the bus bar electrode 30 and the finger electrode 32 is generally used as an electrode on the light receiving surface side and is well known, and it is possible to apply known forming means for the bus bar electrode and finger electrode on the light receiving surface side. it can.
　上記では、表面にｎ型拡散層、裏面にｐ＋型拡散層を形成し、更にそれぞれの層の上に表面電極及び裏面電極を設けた太陽電池素子について説明したが、本発明のｎ型拡散層形成組成物を用いればバックコンタクト型の太陽電池素子を作製することも可能である。
　バックコンタクト型の太陽電池素子は、電極を全て裏面に設けて受光面の面積を大きくするものである。つまりバックコンタクト型の太陽電池素子では、裏面にｎ型拡散部位及びｐ＋型拡散部位の両方を形成しｐｎ接合構造とする必要がある。本発明のｎ型拡散層形成組成物は、特定の部位にのみｎ型拡散部位を形成することが可能であり、よってバックコンタクト型の太陽電池素子の製造に好適に適用することができる。 In the above description, the solar cell element in which the n-type diffusion layer is formed on the front surface, the p + -type diffusion layer is formed on the back surface, and the front surface electrode and the back surface electrode are further provided on the respective layers has been described. If a layer formation composition is used, it is also possible to produce a back contact type solar cell element.
The back contact type solar cell element has all electrodes provided on the back surface to increase the area of the light receiving surface. That is, in the back contact type solar cell element, it is necessary to form both the n-type diffusion region and the p + -type diffusion region on the back surface to form a pn junction structure. The n-type diffusion layer forming composition of the present invention can form an n-type diffusion site only at a specific site, and therefore can be suitably applied to the production of a back contact type solar cell element.
　なお、日本出願２０１０－１００２２６の開示はその全体が参照により本明細書に取り込まれる。
　本明細書に記載された全ての文献、特許出願、及び技術規格は、個々の文献、特許出願、及び技術規格が参照により取り込まれることが具体的かつ個々に記された場合と同程度に、本明細書中に参照により取り込まれる。 Note that the entire disclosure of Japanese application 2010-1000022 is incorporated herein by reference.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.
　以下、本発明の実施例をさらに具体的に説明するが、本発明はこれらの実施例に制限するものではない。なお、特に記述が無い限り、薬品は全て試薬を使用した。また「％」は断りがない限り「質量％」を意味する。 Hereinafter, examples of the present invention will be described more specifically, but the present invention is not limited to these examples. Unless otherwise stated, all chemicals used reagents. “%” Means “% by mass” unless otherwise specified.
［実施例１］
　粒子形状が略球状で、平均粒子径が３．５μｍのＰ２Ｏ５－ＣｅＯ２系ガラス（Ｐ２Ｏ５：３９．６％、ＣｅＯ２：１０％、ＢａＯ：１０．４％、ＭｏＯ３：１０％、ＺｎＯ：３０％）粉末２０ｇと、エチルセルロース０．３ｇと、酢酸２－（２－ブトキシエトキシ）エチル７ｇとを自動乳鉢混練装置を用いて混合してペースト化し、ｎ型拡散層形成組成物を調製した。
　 (株)島津製作所製熱分析装置（ＴＧ-ＤＴＡ、ＤＴＧ６０Ｈ型、測定条件：昇温速度２０℃／分、空気流量１００ｍｌ／分）で上記Ｐ２Ｏ５－ＣｅＯ２系ガラス粉末を熱分析した結果、軟化温度は５２０℃であった。
　また結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
　尚、ガラス粒子形状は、（株）日立ハイテクノロジーズ製ＴＭ－１０００型走査型電子顕微鏡を用いて観察して判定した。ガラスの平均粒子径はベックマン・コールター（株）製ＬＳ　１３　３２０型レーザー散乱回折法粒度分布測定装置（測定波長：６３２ｎｍ）を用いて算出した。 [Example 1]
P 2 O 5 —CeO 2 -based glass (P 2 O 5 : 39.6%, CeO 2 : 10%, BaO: 10.4%, MoO 3 having a substantially spherical particle shape and an average particle diameter of 3.5 μm) : 10%, ZnO: 30%) 20 g of powder, 0.3 g of ethyl cellulose and 7 g of 2- (2-butoxyethoxy) ethyl acetate were mixed using an automatic mortar kneader to form a paste, forming an n-type diffusion layer A composition was prepared.
The above P 2 O 5 -CeO 2 glass powder was subjected to thermal analysis with a thermal analyzer manufactured by Shimadzu Corporation (TG-DTA, DTG60H type, measurement conditions: heating rate 20 ° C./min, air flow rate 100 ml / min). As a result, the softening temperature was 520 ° C.
The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The glass particle shape was determined by observation using a TM-1000 scanning electron microscope manufactured by Hitachi High-Technologies Corporation. The average particle size of the glass was calculated using a LS 13 320 type laser scattering diffraction particle size distribution analyzer (measurement wavelength: 632 nm) manufactured by Beckman Coulter, Inc.
　次に、調製したペースト（ｎ型拡散層形成組成物）をスクリーン印刷によってｐ型シリコン基板表面に塗布し、１５０℃のホットプレート上で５分間乾燥させた。続いて、１０００℃に設定した電気炉で１０分間熱拡散処理を行い、その後ガラス層を除去するため基板を１０％ふっ酸に５分間浸漬し、流水洗浄を行った。その後、乾燥を行った。 Next, the prepared paste (n-type diffusion layer forming composition) was applied to the surface of the p-type silicon substrate by screen printing and dried on a hot plate at 150 ° C. for 5 minutes. Subsequently, thermal diffusion treatment was performed for 10 minutes in an electric furnace set at 1000 ° C., and then the substrate was immersed in 10% hydrofluoric acid for 5 minutes to remove the glass layer, and washed with running water. Thereafter, drying was performed.
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は４５Ω／□であり、Ｐ（リン）が拡散し、ｎ型拡散層が形成されていた。一方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、またｎ型拡散層は実質的に形成されていないと判断された。評価結果を表１に示す。 The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 45Ω / □, P (phosphorus) diffused, and an n-type diffusion layer was formed. On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed. The evaluation results are shown in Table 1.
　なお、シート抵抗は、三菱化学（株）製Ｌｏｒｅｓｔａ－ＥＰ　ＭＣＰ－Ｔ３６０型低抵抗率計を用いて四探針法により測定した。 The sheet resistance was measured by a four-probe method using a Loresta-EP MCP-T360 type low resistivity meter manufactured by Mitsubishi Chemical Corporation.
［実施例２］
　熱拡散処理時間を１５分とした以外は実施例１と同様にｎ型拡散層形成を行った。ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は３０Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　一方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、またｎ型拡散層は実質的に形成されていないと判断された。 [Example 2]
An n-type diffusion layer was formed in the same manner as in Example 1 except that the thermal diffusion treatment time was 15 minutes. The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 30Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例３］
　熱拡散処理の時間を３０分とした以外は実施例１と同様にｎ型拡散層形成を行った。ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は１７Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　一方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、またｎ型拡散層は実質的に形成されていないと判断された。 [Example 3]
An n-type diffusion layer was formed in the same manner as in Example 1 except that the thermal diffusion treatment time was 30 minutes. The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 17Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例４］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＺｎＯ系ガラス（Ｐ２Ｏ５：４０％、ＺｎＯ：４０％、ＣｅＯ２：１０％、ＭｇＯ：５％、ＣａＯ：５％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は４８０℃であった。また、結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は４１Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　一方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、またｎ型拡散層は実質的に形成されていないと判断された。 [Example 4]
A glass powder having a substantially spherical particle shape and an average particle diameter of 3.2 μm P 2 O 5 —ZnO-based glass (P 2 O 5 : 40%, ZnO: 40%, CeO 2 : 10%, MgO: 5) %, CaO: 5%). An n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 480 ° C. The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 41 Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例５］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５：３０％、ＳｉＯ２：５０％、ＣｅＯ２：１０％、ＺｎＯ：１０％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、上記ガラス粉末の軟化温度は６１０℃であった。また、結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は４８Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　他方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、またｎ型拡散層は実質的に形成されていないと判断された。 [Example 5]
The glass powder is made of P 2 O 5 —SiO 2 glass (P 2 O 5 : 30%, SiO 2 : 50%, CeO 2 : 10%, ZnO) having a substantially spherical particle shape and an average particle diameter of 3.2 μm. : 10%), an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 610 ° C. The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 48Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例６］
　熱拡散処理の時間を３０分とした以外は実施例５と同様にｎ型拡散層形成を行った。ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は３０Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　他方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、またｎ型拡散層は実質的に形成されていないと判断された。 [Example 6]
An n-type diffusion layer was formed in the same manner as in Example 5 except that the thermal diffusion treatment time was 30 minutes. The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 30Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例７］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＰｂＯ系ガラス（Ｐ２Ｏ５：３０％、ＰｂＯ：５０％、ＺｎＯ：２０％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は３３０℃であった。また、結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は１５Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　他方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、また実質的に形成されていないと判断された。 [Example 7]
Except that the glass powder was made into P 2 O 5 —PbO glass (P 2 O 5 : 30%, PbO: 50%, ZnO: 20%) having a substantially spherical particle shape and an average particle diameter of 3.2 μm. Then, an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 330 ° C. The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 15Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer.
On the other hand, it was judged that the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured and was not substantially formed.
［実施例８］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５：４０％、ＳｉＯ２：１０％、ＰｂＯ：３０％、ＺｎＯ：１０％、ＣａＯ：１０％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は３６０℃であった。また、結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は２１Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　他方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、またｎ型拡散層は実質的に形成されていないと判断された。 [Example 8]
The glass powder is a P 2 O 5 —SiO 2 glass (P 2 O 5 : 40%, SiO 2 : 10%, PbO: 30%, ZnO: having a substantially spherical particle shape and an average particle diameter of 3.2 μm). 10%, CaO: 10%) An n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 360 ° C. The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 21Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例９］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５：４０％、ＳｉＯ２：１０％、ＰｂＯ：２０％、ＺｎＯ：２０％、ＮａＯ：１０％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は３８５℃であった。また、結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は２５Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　他方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、またｎ型拡散層は実質的に形成されていないと判断された。 [Example 9]
The glass powder is made of P 2 O 5 —SiO 2 glass (P 2 O 5 : 40%, SiO 2 : 10%, PbO: 20%, ZnO: having a substantially spherical particle shape and an average particle diameter of 3.2 μm). An n-type diffusion layer forming composition was prepared in the same manner as in Example 1 except that 20% and NaO: 10%), and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 385 ° C. The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 25Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例１０］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＺｎＯ系ガラス（Ｐ２Ｏ５：３０％、ＺｎＯ：４０％、ＣａＯ：２０％、Ａｌ２Ｏ３：１０％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は４５０℃であった。また、結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は３６Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　他方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、ｎ型拡散層は実質的に形成されていないと判断された。 [Example 10]
The glass powder is made of P 2 O 5 —ZnO-based glass (P 2 O 5 : 30%, ZnO: 40%, CaO: 20%, Al 2 O 3) having a substantially spherical particle shape and an average particle diameter of 3.2 μm. : 10%), an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 450 ° C. The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 36Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例１１］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５：５０％、ＳｉＯ２：１０％、ＺｎＯ：３０％、ＣａＯ：１０）とし、熱拡散処理時間を２０分間とした以外は、実施例１としてｎ型拡散層形成組成物を調製し、これを用いて同様にｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は６１０℃であった。また、結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は４０Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　他方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、ｎ型拡散層は実質的に形成されていないと判断された。 [Example 11]
The glass powder is a P 2 O 5 —SiO 2 glass (P 2 O 5 : 50%, SiO 2 : 10%, ZnO: 30%, CaO: having a substantially spherical particle shape and an average particle diameter of 3.2 μm). 10), except that the thermal diffusion treatment time was 20 minutes, an n-type diffusion layer forming composition was prepared as Example 1, and an n-type diffusion layer was similarly formed using this composition. The softening temperature of the glass powder was 610 ° C. The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 40Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例１２］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５：２７％、ＳｉＯ２：５８％、ＣａＯ：１５％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は８３０℃であった。また、結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は６９Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　他方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、ｎ型拡散層は実質的に形成されていないと判断された。 [Example 12]
The glass powder was P 2 O 5 —SiO 2 glass (P 2 O 5 : 27%, SiO 2 : 58%, CaO: 15%) having a substantially spherical particle shape and an average particle diameter of 3.2 μm. Except for the above, an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 830 ° C. The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 69Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例１３］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５：３０％、ＳｉＯ２：６０％、ＣａＯ：１０％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は８７５℃であった。また、結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は７１Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　他方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、ｎ型拡散層は実質的に形成されていないと判断された。 [Example 13]
The glass powder was P 2 O 5 —SiO 2 glass (P 2 O 5 : 30%, SiO 2 60%, CaO 10%) having a substantially spherical particle shape and an average particle diameter of 3.2 μm. Except for the above, an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 875 ° C. The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 71 Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［実施例１４］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５：２５％、ＳｉＯ２：６５％、ＣａＯ：５％、Ａｌ２Ｏ３：５％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は９３０℃であった。また、結晶化温度は熱分析装置の測定範囲を超えており、１１００℃以上であった。
ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は８３Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。
　他方、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は大きすぎて測定不能であり、ｎ型拡散層は実質的に形成されていないと判断された。 [Example 14]
The glass powder is made of P 2 O 5 —SiO 2 glass (P 2 O 5 : 25%, SiO 2 : 65%, CaO: 5%, Al 2) having a substantially spherical particle shape and an average particle diameter of 3.2 μm. Except that O 3 : 5%), an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 930 ° C. The crystallization temperature exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 83Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer.
On the other hand, the sheet resistance of the portion where the n-type diffusion layer forming composition including the back surface was not applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
［比較例１］
　リン酸二水素アンモニウム（ＮＨ４Ｈ２ＰＯ４）粉末２０ｇと、エチルセルロース３ｇと、酢酸２－（２－ブトキシエトキシ）エチル７ｇとを自動乳鉢混練装置を用いて混合してペースト化し、ｎ型拡散層形成組成物（ペースト）を調製した。
　次に、調製したペーストをスクリーン印刷によってｐ型シリコン基板表面に塗布し、１５０℃のホットプレート上で５分間乾燥させた。続いて、１０００℃に設定した電気炉で１０分間熱拡散処理を行い、その後ガラス層を除去するため基板をふっ酸に５分間浸漬し、流水洗浄、乾燥を行った。 [Comparative Example 1]
20 g of ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) powder, 3 g of ethyl cellulose, and 7 g of 2- (2-butoxyethoxy) ethyl acetate are mixed using an automatic mortar kneader to make a paste, and n-type diffusion A layer forming composition (paste) was prepared.
Next, the prepared paste was applied to the surface of the p-type silicon substrate by screen printing and dried on a hot plate at 150 ° C. for 5 minutes. Subsequently, a thermal diffusion treatment was performed for 10 minutes in an electric furnace set at 1000 ° C., and then the substrate was immersed in hydrofluoric acid for 5 minutes to remove the glass layer, washed with running water, and dried.
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は１４Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。しかしながら、裏面のシート抵抗は５０Ω／□であり、裏面にもｎ型拡散層が形成されていた。 The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 14Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer. However, the sheet resistance on the back surface was 50Ω / □, and an n-type diffusion layer was also formed on the back surface.
［比較例２］
　リン酸二水素アンモニウム（ＮＨ４Ｈ２ＰＯ４）粉末１ｇと純水７ｇ、ポリビニルアルコール０．７ｇ、イソプロピルアルコール１．５ｇを混合して溶液を調製した。
　次に、調製した溶液をスピンコータ（２０００ｒｐｍ、３０ｓｅｃ）によってｐ型シリコン基板表面に塗布し、１５０℃のホットプレート上で５分間乾燥させた。続いて、１０００℃に設定した電気炉で１０分間熱拡散処理を行い、その後ガラス層を除去するため基板をふっ酸に５分間浸漬し、流水洗浄、乾燥を行った。 [Comparative Example 2]
A solution was prepared by mixing 1 g of ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) powder, 7 g of pure water, 0.7 g of polyvinyl alcohol, and 1.5 g of isopropyl alcohol.
Next, the prepared solution was applied to the surface of the p-type silicon substrate by a spin coater (2000 rpm, 30 sec) and dried on a hot plate at 150 ° C. for 5 minutes. Subsequently, a thermal diffusion treatment was performed for 10 minutes in an electric furnace set at 1000 ° C., and then the substrate was immersed in hydrofluoric acid for 5 minutes to remove the glass layer, washed with running water, and dried.
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は１０Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。しかしながら、裏面のシート抵抗は１００Ω／□であり、裏面にもｎ型拡散層が形成されていた。 The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 10Ω / □, and P (phosphorus) was diffused to form an n-type diffusion layer. However, the sheet resistance on the back surface was 100Ω / □, and an n-type diffusion layer was also formed on the back surface.
［比較例３］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５：１０％、ＳｉＯ２：２０％、ＮａＯ：７０％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は２３０℃であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は６１Ω／□であり、Ｐ（リン）が拡散しｎ型拡散層が形成されていた。しかしながら、裏面を含むｎ型拡散層形成組成物が塗布されていなかった部分のシート抵抗は６５Ω／□であり、不要な部分にまでｎ型拡散層が形成されており、目的とする部分的なｎ型拡散層の形成ができなかった。 [Comparative Example 3]
The glass powder was P 2 O 5 —SiO 2 glass (P 2 O 5 : 10%, SiO 2 : 20%, NaO: 70%) having a substantially spherical particle shape and an average particle diameter of 3.2 μm. Except for the above, an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder was 230 ° C.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was 61Ω / □, and P (phosphorus) diffused to form an n-type diffusion layer. However, the sheet resistance of the part where the n-type diffusion layer forming composition including the back surface is not applied is 65Ω / □, and the n-type diffusion layer is formed even in an unnecessary part, An n-type diffusion layer could not be formed.
［比較例４］
　ガラス粉末を、粒子形状が略球状で、平均粒子径が３．２μｍのＰ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５：５％、ＳｉＯ２：９３％、ＮａＯ：２％）とした以外は、実施例１と同様にしてｎ型拡散層形成組成物を調製し、これを用いてｎ型拡散層形成を行った。なお、ガラス粉末の軟化温度は、熱分析装置の測定範囲を超えており、１１００℃以上であった。
　ｎ型拡散層形成組成物を塗布した側の表面のシート抵抗は、大きすぎて測定不能であり、ｎ型拡散層は実質的に形成されていないと判断された。 [Comparative Example 4]
The glass powder was P 2 O 5 —SiO 2 glass (P 2 O 5 : 5%, SiO 2 : 93%, NaO: 2%) having a substantially spherical particle shape and an average particle diameter of 3.2 μm. Except for the above, an n-type diffusion layer forming composition was prepared in the same manner as in Example 1, and an n-type diffusion layer was formed using this composition. The softening temperature of the glass powder exceeded the measurement range of the thermal analyzer and was 1100 ° C. or higher.
The sheet resistance of the surface on which the n-type diffusion layer forming composition was applied was too large to be measured, and it was determined that the n-type diffusion layer was not substantially formed.
Figure JPOXMLDOC01-appb-T000001
 
Figure JPOXMLDOC01-appb-T000001
 
　以上から、本発明のｎ型拡散層形成組成物を用いることで、ｎ型拡散層を特定の部位にのみ、均一に形成可能であることが分かる。 From the above, it can be seen that by using the n-type diffusion layer forming composition of the present invention, the n-type diffusion layer can be uniformly formed only at a specific site.
１０　ｐ型半導体基板
１２　ｎ型拡散層
１４　高濃度電界層
１６　反射防止膜
１８　表面電極
２０　裏面電極（電極層）
３０　バスバー電極
３２　フィンガー電極 10 p-type semiconductor substrate 12 n-type diffusion layer 14 high-concentration electric field layer 16 antireflection film 18 surface electrode 20 back electrode (electrode layer)
30 Busbar electrode 32 Finger electrode

Claims (6)

  1. 　ドナー元素を含み軟化温度が３００℃～９５０℃であるガラス粉末と、分散媒と、を含有するｎ型拡散層形成組成物。 An n-type diffusion layer forming composition containing glass powder having a donor element and a softening temperature of 300 ° C. to 950 ° C., and a dispersion medium.
  2. 　前記ドナー元素が、Ｐ（リン）及びＳｂ（アンチモン）から選択される少なくとも１種である請求項１に記載のｎ型拡散層形成組成物。 The n-type diffusion layer forming composition according to claim 1, wherein the donor element is at least one selected from P (phosphorus) and Sb (antimony).
  3. 　前記ドナー元素を含むガラス粉末が、Ｐ２Ｏ３、Ｐ２Ｏ５及びＳｂ２Ｏ３から選択される少なくとも１種のドナー元素含有物質と、ＳｉＯ２、Ｋ２Ｏ、Ｎａ２Ｏ、Ｌｉ２Ｏ、ＢａＯ、ＳｒＯ、ＣａＯ、ＭｇＯ、ＢｅＯ、ＺｎＯ、ＰｂＯ、ＣｄＯ、ＳｎＯ、ＺｒＯ２、ＣｅＯ２及びＭｏＯ３から選択される少なくとも１種のガラス成分物質と、を含有する請求項１又は請求項２に記載のｎ型拡散層形成組成物。 The glass powder containing the donor element includes at least one donor element-containing material selected from P 2 O 3 , P 2 O 5 and Sb 2 O 3 , SiO 2 , K 2 O, Na 2 O, Li 2. The at least one glass component substance selected from O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , CeO 2 and MoO 3 is contained. 3. The n-type diffusion layer forming composition according to 2.
  4. 　前記ガラス粉末の結晶化温度が１０５０℃以上である請求項１～請求項３のいずれか１項に記載のｎ型拡散層形成組成物。 The n-type diffusion layer forming composition according to any one of claims 1 to 3, wherein the crystallization temperature of the glass powder is 1050 ° C or higher.
  5. 　請求項１～請求項４のいずれか１項に記載のｎ型拡散層形成組成物を塗布する工程と、熱拡散処理を施す工程と、を有するｎ型拡散層の製造方法。 A method for producing an n-type diffusion layer, comprising a step of applying the n-type diffusion layer forming composition according to any one of claims 1 to 4 and a step of applying a thermal diffusion treatment.
  6. 　半導体基板上に、請求項１～請求項４のいずれか１項に記載のｎ型拡散層形成組成物を塗布する工程と、熱拡散処理を施して、ｎ型拡散層を形成する工程と、形成された前記ｎ型拡散層上に電極を形成する工程と、を有する太陽電池素子の製造方法。 A step of applying the n-type diffusion layer forming composition according to any one of claims 1 to 4 on a semiconductor substrate; a step of applying a thermal diffusion treatment to form an n-type diffusion layer; And a step of forming an electrode on the formed n-type diffusion layer.
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