WO2012005253A1 - Composition for forming impurity diffusion layer, process for producing impurity diffusion layer, and process for producing solar cell element - Google Patents

Composition for forming impurity diffusion layer, process for producing impurity diffusion layer, and process for producing solar cell element Download PDF

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WO2012005253A1
WO2012005253A1 PCT/JP2011/065386 JP2011065386W WO2012005253A1 WO 2012005253 A1 WO2012005253 A1 WO 2012005253A1 JP 2011065386 W JP2011065386 W JP 2011065386W WO 2012005253 A1 WO2012005253 A1 WO 2012005253A1
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diffusion layer
type diffusion
forming composition
layer forming
glass powder
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PCT/JP2011/065386
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French (fr)
Japanese (ja)
Inventor
修一郎 足立
吉田　誠人
野尻　剛
香 岡庭
洋一 町井
岩室　光則
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 claimed from JP2010155174A external-priority patent/JP5691269B2/en
Priority claimed from JP2010155173A external-priority patent/JP5691268B2/en
Application filed by 日立化成工業株式会社 filed Critical 日立化成工業株式会社
Priority to CN2011800271169A priority Critical patent/CN102934205A/en
Priority to KR1020127031636A priority patent/KR20130086146A/en
Publication of WO2012005253A1 publication Critical patent/WO2012005253A1/en

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    • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System 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
    • 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
    • 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
    • C03C8/04—Frit compositions, i.e. in a powdered or comminuted form 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
    • 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
    • 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
    • C03C8/18—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions containing free metals
    • 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 at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System 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
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier
    • H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by at least one potential-jump barrier or surface barrier the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
    • 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 System
    • 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 impurity diffusion layer forming composition, a method for manufacturing an impurity diffusion layer, and a method for manufacturing a solar cell element, and more specifically, forming an impurity diffusion layer in a specific portion of a silicon substrate which is a semiconductor substrate. More particularly, the present invention relates to a technology capable of reducing the internal stress of a silicon substrate, which is a semiconductor substrate, and to an impurity diffusion layer forming technology capable of suppressing damage at crystal grain boundaries, suppressing crystal defect growth, and suppressing warpage.
  • a p-type silicon substrate having a textured structure formed on the light receiving surface is prepared so as to promote the light confinement effect, and then a donor element-containing compound such as phosphorus oxychloride (POCl 3 ), nitrogen, oxygen
  • a donor element-containing compound such as phosphorus oxychloride (POCl 3 ), nitrogen, oxygen
  • POCl 3 phosphorus oxychloride
  • the n-type diffusion layer is uniformly formed on the substrate by performing several tens of minutes at 800 ° C. to 900 ° C. in the mixed gas atmosphere.
  • 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, side etching is performed to remove the n-type diffusion layer on the side surface.
  • the n-type diffusion layer on the back surface needs to be converted into a p + -type diffusion layer, and an aluminum paste is applied on the n-type diffusion layer on the back surface, and this is baked. It was converted to a p + type diffusion layer.
  • the aluminum layer formed from the aluminum paste has a low conductivity, and in order to reduce the sheet resistance, it is The aluminum layer formed on the entire surface must have a thickness of about 10 ⁇ m to 20 ⁇ m after firing. Furthermore, when a thick aluminum layer is formed in this way, the thermal expansion coefficient differs greatly between silicon and aluminum, so that a large internal stress is generated in the silicon substrate during the firing and cooling process, resulting in damage to the grain boundaries, In some cases, defects increased and warped.
  • n-type diffusion layer in the gas phase reaction using phosphorus oxychloride, not only one side (usually the light receiving surface or the surface) that originally requires the n-type diffusion layer but also the other side An n-type diffusion layer is also formed on the surface (non-light-receiving surface or 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 an n-type diffusion layer is formed 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. It is an object of the present invention to provide an n-type diffusion layer-forming composition, a method for producing an n-type diffusion layer, and a method for producing a solar cell element.
  • the present invention provides a p-type diffusion layer formation capable of forming a p-type diffusion layer while suppressing the occurrence of internal stress in the silicon substrate and warping of the substrate in a manufacturing process of a solar cell using a silicon substrate.
  • An object is to provide a p-type diffusion layer forming composition that is a composition and excellent in dispersion stability, a method for producing a p-type diffusion layer, and a method for producing a solar cell element.
  • An impurity diffusion layer forming composition comprising a glass powder containing a donor element or an acceptor element, a binder having a weight average molecular weight of 5,000 to 500,000, and a solvent.
  • the glass powder includes a glass component substance and a donor element-containing substance, and the content ratio of the donor element-containing substance is 1% by mass to 75% by mass with respect to the glass powder.
  • n-type diffusion layer forming composition according to any one of ⁇ 2> to ⁇ 4>, wherein 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. And at least one glass component material selected from Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , and MoO 3.
  • the n-type diffusion layer forming composition according to any one of the above.
  • n-type diffusion layer forming composition according to any one of ⁇ 2> to ⁇ 6>, further including at least one metal selected from Ag, Si, Cu, Fe, Zn, and Mn. .
  • An n-type diffusion comprising a step of applying the n-type diffusion layer forming composition according to any one of ⁇ 2> to ⁇ 8> on a semiconductor substrate and a step of performing a thermal diffusion treatment.
  • Layer manufacturing method
  • n-type diffusion layer forming composition according to any one of ⁇ 2> to ⁇ 8> above 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 a process and the process of forming an electrode on the formed n type diffused layer.
  • the glass powder includes a glass component substance and an acceptor element-containing substance, and a content ratio of the acceptor element-containing substance in the glass powder is 1% by mass or more and 90% by mass or less.
  • a p-type diffusion layer forming composition is a p-type diffusion layer forming composition.
  • ⁇ 14> The p-type according to any one of ⁇ 11> to ⁇ 13>, wherein the acceptor element is at least one selected from B (boron), Al (aluminum), and Ga (gallium). Diffusion layer forming composition.
  • the glass powder containing the acceptor element is at least one acceptor element-containing material selected from B 2 O 3 , Al 2 O 3, and Ga 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, Tl 2 O, SnO, ZrO 2 , and MoO 3.
  • the p-type diffusion layer forming composition according to any one of ⁇ 11> to ⁇ 14>.
  • a p-type diffusion having a step of applying the p-type diffusion layer forming composition according to any one of ⁇ 11> to ⁇ 15> on a semiconductor substrate and a step of performing a thermal diffusion treatment.
  • Layer manufacturing method
  • a step of applying the p-type diffusion layer forming composition according to any one of the above ⁇ 11> to ⁇ 15> on the semiconductor substrate and a thermal diffusion treatment to form a p-type diffusion layer The manufacturing method of the solar cell element which has a process and the process of forming an electrode on the formed p-type diffused layer.
  • n-type diffusion layer in the manufacturing process of a solar cell element using a silicon substrate, it is possible to form an n-type diffusion layer in a specific portion without forming an unnecessary n-type diffusion layer, thereby improving dispersion stability.
  • An excellent n-type diffusion layer forming composition can be provided.
  • the manufacturing method of the n type diffused layer using this n type diffused layer formation composition and the manufacturing method of a photovoltaic cell can be provided.
  • a p-type diffusion layer in the manufacturing process of a solar cell element using a silicon substrate, a p-type diffusion layer can be formed while suppressing internal stress in the silicon substrate and warping of the substrate.
  • a p-type diffusion layer forming composition that is a diffusion layer forming composition and excellent in dispersion stability, a method for producing a p-type diffusion layer, and a method for producing a solar battery cell can be provided.
  • 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 present invention is an impurity diffusion layer forming composition containing a glass powder containing a donor element or an acceptor element, a binder having a weight average molecular weight of 5,000 or more and 500,000 or less, and a solvent.
  • the impurity diffusion layer forming composition is an n-type diffusion layer forming composition
  • the glass powder contains a donor element
  • the impurity diffusion layer forming composition is a p-type diffusion layer forming composition
  • the glass powder contains an acceptor element.
  • the n-type diffusion layer forming composition and the p-type diffusion layer forming composition are The viscosity can be adjusted so that it can be uniformly applied on the silicon substrate. Further, the binder can be completely burned in the thermal diffusion treatment, and the diffusion of the donor element or the acceptor element becomes easy. Further, the dispersion stability of the n-type diffusion layer forming composition and the p-type diffusion layer forming composition is improved. Therefore, the n-type diffusion layer forming composition and the p-type diffusion layer forming composition of the present invention are excellent in dispersion stability, and an n-type diffusion layer or a p-type diffusion layer can be formed in a specific portion.
  • an n-type diffusion layer forming composition and a p-type diffusion layer forming composition of the present invention will be described, and then an n-type diffusion layer manufacturing method using the n-type diffusion layer forming composition, p-type diffusion layer forming composition
  • a method for manufacturing a p-type diffusion layer using a solar cell and a method for manufacturing a solar cell element 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 as long as the intended action of the process is achieved. included.
  • a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the 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 includes at least one kind of glass powder containing at least a donor element (hereinafter sometimes simply referred to as “glass powder”) and a binder having a weight average molecular weight of 5,000 to 500,000. And at least one solvent, and may further contain other additives as required in consideration of coating properties and the like.
  • the n-type diffusion layer forming composition contains a glass powder containing a donor element, and is a material capable of forming an n-type diffusion layer by thermally diffusing this donor element after being applied to a silicon substrate.
  • an n-type diffusion layer is formed at a desired site, and an unnecessary n-type diffusion layer is not formed on the back surface or side surface.
  • 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 necessary, 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. Therefore, 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. Although details will be described later, generation of internal stress in the silicon substrate due to the thickness of the back electrode is suppressed, and warpage of the 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 in the conventional gas phase reaction method and the method of applying a phosphate-containing solution, and thus the glass layer produced in the present invention is the same as the conventional method. Further, it can be removed by etching. 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.
  • the donor component of the glass powder is difficult to volatilize even during firing, the formation of an n-type diffusion layer not only on the surface but also on the back surface and side surfaces due to the generation of the volatilizing gas is suppressed.
  • 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), As (arsenic), and the like. 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 , Examples include 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 include SiO 2 , K 2 O, Na 2 O, Li 2 O. It is preferable to use at least one selected from BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 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 , including P 2 O 5 -V 2 O 5 system, P 2 O 5 -SnO-based, P 2 O 5 -GeO 2 system, a P 2 O 5 as a donor element-containing material of P 2
  • a donor element-containing material is used instead of P 2 O 5 in a system containing P 2 O 5 .
  • glass powder of a system containing Sb 2 O 3 instead of P 2 O 5 in a system containing P 2 O 5 , a donor element-containing material is used.
  • glass powder of a system containing Sb 2 O 3 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 is exemplified, but glass powder containing three or more components such as P 2 O 5 —SiO 2 —V 2 O 5 and 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 as appropriate in consideration of the doping concentration of the donor element into the silicon substrate, the melting temperature of the glass powder, the softening temperature, the glass transition temperature, and the chemical durability. In general, the content is preferably 1% by mass or more and 75% by mass or less.
  • the content ratio of the donor element-containing substance in the glass powder is 1% by mass or more, the doping concentration of the donor element into the silicon substrate does not become too low, and the n-type diffusion layer is sufficiently formed.
  • the content ratio of the donor element-containing material such as P 2 O 5 is 75% by mass or less, the donor element-containing material absorbs moisture in the glass powder.
  • the donor element-containing material is P 2 O 5 Can suppress the formation of phosphoric acid (H 3 PO 4 ).
  • H 3 PO 4 phosphoric acid
  • moisture-absorbing substances such as H 3 PO 4 are suppressed from being volatilized during the thermal diffusion treatment, and the diffusion of the donor element such as P (phosphorus) extends to the side surface and the back surface as well as the surface. It is possible to prevent the n-type diffusion layer from being formed on the side surface and the back surface other than the part.
  • the content of the donor element-containing material in the glass powder is 2% by mass or more and 75% by mass. % Or less, and more preferably 10% by mass or more and 70% by mass or less.
  • the content ratio of the donor element-containing material is more preferably 30% by mass or more and 70% by mass or less.
  • the content ratio of the glass component substance in the glass powder is preferably set as appropriate in consideration of the melting temperature, the softening temperature, the glass transition temperature, and the chemical durability, and generally 0.1% by mass or more and 95% by mass. % Or less, more preferably 0.5% by mass or more and 90% by mass or less.
  • the content ratio of SiO 2 is preferably 1% by mass or more and 90% by mass or less, and more preferably 3% by mass or more and 80% by mass or less. It is more preferable.
  • the softening point of the glass powder is preferably 200 ° C. to 1000 ° C., more preferably 300 ° C. to 900 ° C., from the viewpoints of diffusibility during the diffusion treatment and dripping.
  • 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.
  • raw materials for example, the donor element-containing material and the glass component material are weighed and filled in a crucible.
  • 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.
  • 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.
  • the obtained melt is poured onto a zirconia substrate, a carbon substrate or the like to vitrify the melt.
  • 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. Generally, 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, and more preferably 1% by mass or more and 90% by mass or less.
  • the n-type diffusion layer forming composition of the present invention contains at least one binder having a weight average molecular weight of 5000 to 500,000 and at least one solvent. These serve as a dispersion medium for the glass powder.
  • 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 and copolymers thereof, as well as appropriately selected and siloxane resin. These are used singly or in combination of two or more.
  • the n-type diffusion layer forming composition of the present invention has a weight average molecular weight of 5,000 or more and 500,000 or less of the binder contained therein. Thereby, it is possible to adjust the viscosity so that the n-type diffusion layer forming composition can be uniformly applied on the silicon substrate. If the molecular weight of the binder is less than 5000, the viscosity of the n-type diffusion layer forming composition may increase. This can be considered, for example, because the three-dimensional repulsion when adsorbed on glass particles is insufficient and the particles aggregate.
  • the weight average molecular weight of the binder when the weight average molecular weight of the binder is larger than 500,000, the binders aggregate in the solvent, and as a result, the viscosity of the n-type diffusion layer forming composition may increase.
  • the burning temperature of the binder increases, the binder is not completely burned in the thermal diffusion treatment, and the diffusion of the donor element is difficult to proceed. There is a possibility of diffusing to the substrate.
  • the molecular weight of the binder is preferably 6000 or more and 450,000 or less, and more preferably 6500 or more and 400,000 or less.
  • the weight average molecular weight of a binder is measured by the normal method using GPC.
  • 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 preferable from the viewpoint of applicability to the substrate.
  • the content ratio of the binder and the solvent in the n-type diffusion layer forming composition is appropriately selected in consideration of coating properties, donor element-containing substance concentration, and the like.
  • the content ratio of the binder can be, for example, 0.01% by mass to 5% by mass with respect to the n-type diffusion layer forming composition, and from the viewpoint of dispersion stability, 0.1% by mass to 3%. It is preferable that it is mass%.
  • the content ratio of the solvent can be 1% by mass to 60% by mass with respect to the n-type diffusion layer forming composition, and is preferably 5% by mass to 40% by mass from the viewpoint of dispersion stability. .
  • the viscosity of the n-type diffusion layer forming composition is preferably 10 mPa ⁇ s or more and 1000000 mPa ⁇ s or less, more preferably 50 mPa ⁇ s or more and 500000 mPa ⁇ s or less in consideration of applicability.
  • pH adjuster examples include dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, tartaric acid, citric acid, fumaric acid, malic acid, phytic acid, succinic acid, gluconic acid, lactic acid, sodium hydroxide, potassium carbonate, sodium bicarbonate, carbonate Sodium etc. are mentioned. These are used singly or in combination of two or more.
  • the pH of the n-type diffusion layer forming composition is appropriately set in consideration of the equipotential point of the glass composition (the pH at which the zeta potential becomes 0 and the particles easily aggregate), acid resistance, and alkali resistance.
  • the pH (25 ° C.) is preferably 2.0 or more and 13.0 or less, and more preferably 3.0 or more and 12.0 or less.
  • the pH is measured at 25 ° C. using a normal pH measuring device.
  • the pH (25 ° C.) of the n-type diffusion layer forming composition is preferably 3.0 or more and 11.0 or less. More preferably, it is 0 or more and 10.0 or less.
  • the n-type diffusion layer forming composition may contain other additives.
  • other additives include metals that easily react with the glass powder.
  • the n-type diffusion layer forming composition is applied on a semiconductor substrate and heat-treated at a high temperature to form an n-type diffusion layer. At that time, glass is formed on the surface. This glass is removed by dipping in an acid such as hydrofluoric acid, but some glass is difficult to remove depending on the type of glass. In that case, the glass can be easily removed after the acid cleaning by adding a metal such as Ag, Mn, Cu, Fe, Zn, or Si. Among these, it is preferable to use at least one selected from Ag, Si, Cu, Fe, Zn and Mn, more preferable to use at least one selected from Ag, Si and Zn. It is particularly preferred.
  • the content ratio of the metal is desirably adjusted as appropriate depending on the type of glass and the type of the metal, and is generally 0.01% by mass or more and 10% by mass or less with respect to the glass powder.
  • the said metal can be used with forms, such as a metal simple substance and a metal oxide.
  • the p-type diffusion layer forming composition of the present invention includes at least one kind of glass powder containing at least an acceptor element (hereinafter sometimes simply referred to as “glass powder”) and a binder having a weight average molecular weight of 5,000 to 500,000. And at least one solvent, and may further contain other additives as required in consideration of coating properties and the like.
  • the p-type diffusion layer forming composition contains an acceptor element.
  • the p-type diffusion layer is formed by thermally diffusing the acceptor element by applying thermal diffusion treatment (baking) after being applied to a silicon substrate. A material that can be used.
  • the p + -type diffusion layer forming step and the ohmic contact forming step can be separated, and the choice of electrode material for forming the ohmic contact is widened.
  • the options also expand. For example, if a low resistance material such as silver is used for the electrode, a low resistance can be achieved with a thin film thickness.
  • the electrodes need not be formed on the entire surface, and may be partially formed like a comb shape. As described above, by forming a partial shape such as a thin film or a comb shape, it is possible to form a p-type diffusion layer while suppressing the occurrence of internal stress in the silicon substrate and warping of the substrate.
  • the p-type diffusion layer forming composition of the present invention is applied, a conventionally widely employed method, that is, printing an aluminum paste and firing it to turn the n-type diffusion layer into a p + -type diffusion layer.
  • a conventionally widely employed method that is, printing an aluminum paste and firing it to turn the n-type diffusion layer into a p + -type diffusion layer.
  • the internal stress in the substrate and the warpage of the substrate that are generated by the method of obtaining the ohmic contact are suppressed.
  • the acceptor component in the glass powder is not easily volatilized even during firing, the formation of a p-type diffusion layer other than the desired region due to the generation of the volatilizing gas is suppressed. The reason for this is considered that the acceptor component is bonded to an element in the glass powder or is taken into the glass, so that it is difficult to volatilize.
  • the content ratio of the acceptor element-containing substance in the glass powder contained therein is preferably 1% by mass or more and 90% by mass or less. Thereby, a surface resistance value falls and the performance as a photovoltaic cell can be improved. Details of the acceptor element-containing material will be described later.
  • An acceptor element is an element that can form a p-type diffusion layer by doping into a silicon substrate.
  • a Group 13 element can be used, and examples thereof include B (boron), Al (aluminum), and Ga (gallium).
  • acceptor element-containing material used for introducing the acceptor element into the glass powder examples include B 2 O 3 , Al 2 O 3 , and Ga 2 O 3 , and B 2 O 3 , Al 2 O 3, and Ga 2 O. It is preferable to use at least one selected from 3 .
  • the glass powder containing an acceptor 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 components 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, Tl 2 O, SnO, ZrO 2 , MoO 3 , La 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Y 2 O 3 , TiO 2 , GeO 2 , TeO 2, and Lu 2 O 3, and the like can be mentioned.
  • SiO 2 , K 2 O, Na 2 O, Li 2 It is preferable to use at least one selected from O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, Tl 2 O, SnO, ZrO 2 , and MoO 3 .
  • the glass powder containing an acceptor element include a system containing both the acceptor element-containing substance and the glass component substance, and a B 2 O 3 —SiO 2 system (in order of acceptor element-containing substance—glass component substance). And the same applies hereinafter), B 2 O 3 —ZnO system, B 2 O 3 —PbO system, B 2 O 3 single system, etc., a system containing B 2 O 3 as an acceptor element-containing substance, Al 2 O 3 —SiO Glasses such as a system containing Al 2 O 3 as the acceptor element-containing material such as a 2 system and a system containing Ga 2 O 3 as the acceptor element containing material such as a Ga 2 O 3 —SiO 2 system can be given.
  • a glass powder containing two or more kinds of acceptor element-containing materials such as Al 2 O 3 —B 2 O 3 series, Ga 2 O 3 —B 2 O 3 series, etc. may be used.
  • acceptor element-containing materials such as Al 2 O 3 —B 2 O 3 series, Ga 2 O 3 —B 2 O 3 series, etc.
  • a single component glass or a composite glass containing two components is exemplified, but three or more types of composite glasses such as B 2 O 3 —SiO 2 —Na 2 O may be used as necessary.
  • the content ratio of the glass component substance in the glass powder is preferably set as appropriate in consideration of the melting temperature, the softening temperature, the glass transition temperature, and the chemical durability, and is generally 0.1% by mass to 95% by mass. It is preferable that it is 0.5 mass% or more and 90 mass% or less.
  • the softening temperature of the glass powder is preferably 200 ° C. to 1000 ° C., more preferably 300 ° C. to 900 ° C., from the viewpoints of diffusibility during the diffusion treatment and dripping.
  • 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 applicability to a substrate and uniform diffusibility when a p-type diffusion layer forming composition is used. It is desirable to have a substantially spherical shape, flat shape, or plate shape.
  • the particle size of the glass powder is desirably 50 ⁇ m or less. When glass powder having a particle size of 50 ⁇ m or less is used, a smooth coating film is easily obtained. Further, the particle size of the glass powder is more preferably 10 ⁇ 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 an acceptor 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 zirconia substrate, a carbon substrate 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 acceptor element in the p-type diffusion layer forming composition is determined in consideration of applicability, acceptor element diffusibility, and the like. Generally, the content ratio of the glass powder in the p-type diffusion layer forming composition is preferably 0.1% by mass or more and 95% by mass or less, and more preferably 1% by mass or more and 90% by mass or less.
  • the p-type diffusion layer forming composition of the present invention contains at least one binder having a weight average molecular weight of 5000 to 500,000 and at least one solvent. These serve as a dispersion medium for the glass powder.
  • 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 and copolymers thereof, as well as appropriately selected and siloxane resin. These are used singly or in combination of two or more.
  • the binder contained therein has a weight average molecular weight of 5,000 to 500,000.
  • coat a p-type diffused layer formation composition on a silicon substrate uniformly can be adjusted.
  • the molecular weight of the binder is less than 5000, the viscosity of the p-type diffusion layer forming composition may increase. This can be considered, for example, because the three-dimensional repulsion when adsorbed on glass particles is insufficient and the particles aggregate.
  • the weight average molecular weight of the binder when the weight average molecular weight of the binder is larger than 500,000, the binders aggregate in the solvent, and as a result, the viscosity of the p-type diffusion layer forming composition may increase.
  • the burning temperature of the binder increases, the binder is not completely burned in the thermal diffusion treatment, and the diffusion of the donor element is difficult to proceed. There is a possibility of diffusing to the substrate.
  • the molecular weight of the binder is preferably 6000 or more and 450,000 or less, and more preferably 6500 or more and 400,000 or less.
  • the weight average molecular weight of a binder is measured by the normal method using GPC.
  • the same solvent as the solvent in the n-type diffusion layer forming composition can be used, and the preferred range is also the same.
  • the content ratio of the binder and the solvent in the p-type diffusion layer forming composition is appropriately selected in consideration of coating properties, donor element-containing substance concentration, and the like.
  • the content ratio of the binder can be, for example, 0.01% by mass to 5% by mass with respect to the n-type diffusion layer forming composition. It is preferable that it is mass%.
  • the content ratio of the solvent can be 1% by mass to 60% by mass with respect to the n-type diffusion layer forming composition, and is preferably 5% by mass to 40% by mass from the viewpoint of dispersion stability. .
  • the viscosity of the p-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.
  • pH adjuster examples include dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, tartaric acid, citric acid, fumaric acid, malic acid, phytic acid, succinic acid, gluconic acid, lactic acid, sodium hydroxide, potassium carbonate, sodium bicarbonate, carbonate Sodium etc. are mentioned. These are used singly or in combination of two or more.
  • the pH of the p-type diffusion layer forming composition is appropriately set in consideration of the equipotential point of the glass composition (the pH at which the zeta potential becomes 0 and the particles easily aggregate), acid resistance, and alkali resistance.
  • the pH (25 ° C.) is preferably 2.0 or more and 13.0 or less, and more preferably 3.0 or more and 12.0 or less.
  • the pH is measured at 25 ° C. using a normal pH measuring device.
  • the pH (25 ° C.) of the p-type diffusion layer forming composition is preferably 3.0 or more and 11.0 or less. More preferably, it is 0 or more and 10.0 or less.
  • 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 coating amount of the n-type diffusion layer forming composition is not particularly limited.
  • the coating amount of the glass powder can be 10 g / m 2 to 250 g / m 2, and 20 g / m 2 to 150 g / m 2. 2 is preferable.
  • a drying step for volatilizing the solvent contained in the composition may be necessary 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 paste.
  • any conventionally known method can be adopted, and the options of the manufacturing method are expanded. Therefore, for example, the high-concentration electric field layer 14 can be formed by applying the composition 13 containing a Group 13 element such as B (boron).
  • the composition 13 containing a Group 13 element such as B (boron) for example, the aforementioned p-type diffusion layer forming composition of the present invention can be used.
  • 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.
  • the thermal diffusion treatment time can be appropriately selected according to the content of the donor element contained in the n-type diffusion layer forming composition. For example, it can be 1 minute to 60 minutes, 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 phosphate glass 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.
  • n-type diffusion layer 12 In the method for forming an n-type diffusion layer of the present invention in which the n-type diffusion layer 12 is formed using the n-type diffusion layer forming composition 11 of the present invention shown in FIGS. Only the n-type diffusion layer 12 is formed, and unnecessary n-type diffusion layers are not formed on the back surface and side surfaces. 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.
  • an aluminum amount of a certain amount or more is required in order to sufficiently convert to the p-type diffusion layer and to form a high concentration electric field layer of p + layer. Therefore, the aluminum layer is formed thick. There was a need.
  • n-type diffusion layer 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 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 may be formed using the p-type diffusion layer forming composition of the present invention.
  • 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. 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).
  • the mixed gas flow ratio NH 3 / SiH 4 is 0.05 to 1.0
  • the reaction chamber pressure is 13.3 Pa (0.1 Torr) to 266.6 Pa (2 Torr)
  • the temperature is 300 ° C. to 550 ° C. and the frequency for plasma discharge is 100 kHz or more.
  • 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 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 an enlarged perspective view illustrating 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.
  • tens of minutes of treatment is performed at 800 ° C. to 900 ° C. in a mixed gas atmosphere of phosphorus oxychloride (POCl 3 ), nitrogen, and oxygen to uniformly form an n-type diffusion layer.
  • a mixed gas atmosphere of phosphorus oxychloride (POCl 3 ), nitrogen, and oxygen to uniformly form an n-type diffusion layer.
  • the diffusion of phosphorus extends to the side surface and the back surface, and the n-type diffusion layer is formed not only on the surface but also on the side surface and the back surface. Therefore, side etching is performed to remove the n-type diffusion layer on the side surface.
  • the p-type diffusion layer forming composition is applied onto the n-type diffusion layer on the back surface of the p-type semiconductor substrate, that is, the surface that is not 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 coating amount of the p-type diffusion layer forming composition is not particularly limited.
  • the coating amount of the glass powder can be 10 g / m 2 to 250 g / m 2, and 20 g / m 2 to 150 g / m 2. 2 is preferable.
  • a drying step for volatilizing the solvent contained in the composition may be necessary 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 semiconductor substrate coated with the p-type diffusion layer forming composition is heat-treated at 600 ° C. to 1200 ° C. By this heat treatment, the acceptor element diffuses into the semiconductor substrate, and a p + -type diffusion layer is formed.
  • a known continuous furnace, batch furnace, or the like can be applied to the heat treatment. Further, the furnace atmosphere during the thermal diffusion treatment can be appropriately adjusted to air, oxygen, nitrogen or the like.
  • the thermal diffusion treatment time can be appropriately selected according to the content of the acceptor element contained in the p-type diffusion layer forming composition. For example, it can be 1 minute to 60 minutes, and more preferably 2 minutes to 30 minutes.
  • the glass 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.
  • an aluminum paste is printed on the back surface, and this is baked to change the n-type diffusion layer into a p + -type diffusion layer, and at the same time, an ohmic contact is obtained.
  • the electrical conductivity of the aluminum layer formed from the aluminum paste is low, and in order to reduce the sheet resistance, the aluminum layer generally formed on the entire back surface must have a thickness of about 10 ⁇ m to 20 ⁇ m after firing.
  • the thermal expansion coefficient differs greatly between silicon and aluminum, so that a large internal stress is generated in the silicon substrate during the firing and cooling process, causing warpage. This internal stress has a problem that the crystal grain boundary is damaged and the power loss increases.
  • the warp easily damages the element in the transportation of the solar cell element in the module process and the connection with a copper wire called a tab wire.
  • the thickness of the silicon substrate has been reduced due to the improvement of the slice processing technique, and the elements tend to be easily broken.
  • the material used for the back electrode is not limited to aluminum.
  • Ag (silver) or Cu (copper) can be applied, and the thickness of the back electrode can be made thinner than the conventional one. Further, it is not necessary to form the entire surface. Therefore, it is possible to reduce internal stress and warpage in the silicon substrate that occur during the firing and cooling processes.
  • an antireflection film is formed on the n-type diffusion layer formed above. This step is the same as that described with reference to FIG. 1 (4) in the formation of the n-type diffusion layer.
  • the surface electrode is formed by applying a surface electrode metal paste on the surface (light receiving surface) of the antireflection film by screen printing and drying. This step is the same as that described with reference to FIG. 1 (5) in the formation of the n-type diffusion layer.
  • a back electrode is also formed on the p + -type diffusion layer on the back surface.
  • the back electrode formation process is also the same as that described for the n-type diffusion layer.
  • the above electrode is fired to complete the solar cell element. This process is the same as that described with reference to FIG. 1 (6) in the formation of the n-type diffusion layer.
  • a mixed gas of phosphorus oxychloride (POCl 3 ), nitrogen and oxygen is used to form an n-type diffusion layer on a silicon substrate which is a p-type semiconductor substrate.
  • the n-type diffusion layer may be formed using the above-described n-type diffusion layer forming composition.
  • the n-type diffusion layer forming composition is applied to the light-receiving surface which is the surface of the p-type semiconductor substrate, and the back surface of the p-type semiconductor substrate according to the present invention is applied.
  • the mold diffusion layer forming composition is applied and subjected to thermal diffusion treatment at 600 ° C. to 1200 ° C.
  • the donor element diffuses into the p-type semiconductor substrate on the front surface to form an n-type diffusion layer
  • the acceptor element diffuses on the back surface to form a p + -type diffusion layer.
  • a solar cell element is produced by the same steps as those described above.
  • 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 provided on the respective layers has been described. If the diffusion layer forming composition and the p-type diffusion layer forming composition are used, a back contact type solar cell element can also be produced.
  • 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 and the p-type diffusion layer forming composition of the present invention can form an n-type diffusion site and a p-type diffusion site only at a specific site, and thus a back contact solar cell. It can be suitably applied to the manufacture of elements.
  • Example 1A 20 g of P 2 O 5 —SiO 2 glass (P 2 O 5 content: 10%) powder, 0.3 g of ethyl cellulose (weight average molecular weight 140000) as a binder, and 7 g of 2- (2-butoxyethoxy) ethyl acetate Then, using an automatic mortar kneading apparatus, the mixture was made into a paste to prepare an n-type diffusion layer forming composition 1. When the pH of the obtained n-type diffusion layer forming composition was measured at 25 ° C. using a pH measuring device, the pH (25 ° C.) was 5.6.
  • Example 2A In Example 1A, an n-type diffusion layer forming composition 2 was prepared in the same manner as in Example 1A, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 300,000. The pH (25 ° C.) was 5.6.
  • Example 3A In Example 1A, except that the glass powder was replaced with P 2 O 5 —ZnO-based glass powder (P 2 O 5 content: 10%), an n-type diffusion layer forming composition 3 was prepared in the same manner as in Example 1A. Prepared. The pH (25 ° C.) was 5.6.
  • Example 4A In Example 1A, an n-type diffusion layer forming composition 4 was prepared in the same manner as in Example 1A, except that the binder was changed to polyvinyl alcohol (weight average molecular weight 250,000). The pH (25 ° C.) was 5.6.
  • Example 5A 19.7 g of P 2 O 5 —SiO 2 glass (P 2 O 5 content: 10%) powder, 0.3 g of Ag, 0.3 g of ethyl cellulose (molecular weight 140000), and 2- (2-butoxyethoxy) acetate Ethyl 7g was mixed and pasted using an automatic mortar kneader to prepare n-type diffusion layer forming composition 5.
  • the pH (25 ° C.) was 5.6.
  • Example 6A In Example 1A, an n-type diffusion layer forming composition 6 was prepared in the same manner as in Example 1A, except that the pH was adjusted to 3.8 using citric acid.
  • Example 7A In Example 1A, an n-type diffusion layer forming composition 7 was prepared in the same manner as in Example 1A, except that the pH was adjusted to 9.8 using sodium hydrogen carbonate.
  • Example 8A In Example 1A, an n-type diffusion layer forming composition 8 was prepared in the same manner as in Example 1A, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 7000. The pH (25 ° C.) was 5.6.
  • Example 9A In Example 1A, an n-type diffusion layer forming composition 9 was prepared in the same manner as in Example 1A, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 450,000. The pH (25 ° C.) was 5.6.
  • Example 1A an n-type diffusion layer forming composition C1 was prepared in the same manner as in Example 1A, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 4500.
  • the pH (25 ° C.) was 5.6.
  • Example 1A an n-type diffusion layer forming composition C2 was prepared in the same manner as in Example 1A, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 750000.
  • the pH (25 ° C.) was 5.6.
  • Viscosity change rate was less than 0.05, and neither gelation nor aggregation of glass particles was observed.
  • B Viscosity change rate was 0.05 or more and less than 0.10, and neither gelation nor aggregation of glass particles was observed.
  • C Viscosity change rate was 0.10 or more and less than 0.15, and neither gelation nor aggregation of glass particles was observed.
  • D Viscosity change rate was less than 0.15, but glass particles were gelled or aggregated.
  • E Viscosity change rate was 0.15 or more, and glass particles were gelled or aggregated.
  • the n-type diffusion layer forming composition prepared in Example 1A to Example 9A was applied to the surface of the p-type silicon substrate by screen printing so that the application amount was 70 g / m 2 (as the glass powder application amount). 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 then dried.
  • the n-type diffusion layer forming compositions prepared in Comparative Example 1 and Comparative Example 2 had low dispersion stability and could not be screen printed.
  • the sheet resistance of the surface is 100 ⁇ / ⁇ or less, P (phosphorus) is diffused, and an n-type diffusion layer is formed. It was.
  • the sheet resistance on the back surface was 1000000 ⁇ / ⁇ or more, which was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.
  • Example 1B Using an automatic mortar kneading apparatus, 20 g of B 2 O 3 —SiO 2 glass (B 2 O 3 : 10%) powder, 3 g of ethyl cellulose (weight average molecular weight 140000), and 77 g of 2- (2-butoxyethoxy) ethyl acetate are used. And mixed to paste to prepare p-type diffusion layer forming composition 1. When the pH of the obtained p-type diffusion layer forming composition was measured at 25 ° C. using a pH measuring device, the pH (25 ° C.) was 5.6.
  • Example 2B In Example 1B, p-type diffusion layer forming composition 2 was prepared in the same manner as in Example 1B, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 300,000. The pH (25 ° C.) was 5.6.
  • Example 3B A p-type diffusion layer forming composition 3 was prepared in the same manner as in Example 1B, except that the glass powder was replaced with a B 2 O 3 —ZnO-based (B 2 O 3 content: 60%) in Example 1B. .
  • the pH (25 ° C.) was 5.6.
  • Example 4B In Example 1B, a p-type diffusion layer forming composition 4 was prepared in the same manner as in Example 1B, except that the binder was changed to polyvinyl alcohol (molecular weight 250,000). The pH (25 ° C.) was 5.6.
  • Example 5B In Example 1B, p-type diffusion layer forming composition 5 was prepared in the same manner as in Example 1B, except that the pH was adjusted to 3.8 using citric acid.
  • Example 6B In Example 1B, p-type diffusion layer forming composition 6 was prepared in the same manner as in Example 1B, except that the pH was adjusted to 10.6 using sodium hydrogen carbonate.
  • Example 7B A p-type diffusion layer forming composition 7 was prepared in the same manner as in Example 1B, except that in Example 1B, the binder was changed to ethyl cellulose having a weight average molecular weight of 8000. The pH (25 ° C.) was 5.6.
  • Example 8B A p-type diffusion layer forming composition 8 was prepared in the same manner as in Example 1B, except that in Example 1B, the binder was replaced with ethyl cellulose having a weight average molecular weight of 450,000. The pH (25 ° C.) was 5.6.
  • Example 1B A p-type diffusion layer forming composition C1 was prepared in the same manner as in Example 1B, except that in Example 1B, the binder was replaced with ethyl cellulose having a weight average molecular weight of 4500.
  • the pH (25 ° C.) was 5.6.
  • Example 2B A p-type diffusion layer forming composition C2 was prepared in the same manner as in Example 1B, except that in Example 1B, the binder was changed to ethyl cellulose having a weight average molecular weight of 750,000. The pH (25 ° C.) was 5.6.
  • the p-type diffusion layer forming composition prepared in Example 1B to Example 8B was applied to the surface of the p-type silicon substrate by screen printing so that the application amount was 70 g / m 2, and a hot plate at 150 ° C. Dry for 5 minutes above. 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 then dried.
  • the surface sheet resistance is 100 ⁇ / ⁇ or less, and B (boron) is diffused to form a p-type diffusion layer. It was.
  • the sheet resistance on the back surface was 1000000 ⁇ / ⁇ or more and could not be measured, and no p-type diffusion layer was formed. Further, the substrate was not warped.

Abstract

Disclosed is a composition for forming an impurity diffusion layer, the composition comprising a glass powder containing a donor element or acceptor element, a binder having a weight-average molecular weight of 5,000-500,000, and a solvent. When the composition is for forming an n-type diffusion layer, the glass powder contains a donor element. When the composition is for forming a p-type diffusion layer, the glass powder contains an acceptor element. By applying the composition for impurity diffusion layer formation and subjecting the applied composition to a thermal diffusion treatment, an n-type diffusion layer or a p-type diffusion layer is produced. A solar cell element having the n-type diffusion layer or p-type diffusion layer is produced.

Description

不純物拡散層形成組成物、不純物拡散層の製造方法、及び太陽電池素子の製造方法Impurity diffusion layer forming composition, method for producing impurity diffusion layer, and method for producing solar cell element
　本発明は、不純物拡散層形成組成物、不純物拡散層の製造方法、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不純物拡散層を形成することを可能とする技術、及び半導体基板であるシリコン基板の内部応力を低減し、結晶粒界のダメージ抑制、結晶欠陥増長抑制及び反り抑制可能な不純物拡散層形成技術に関するものである。 The present invention relates to an impurity diffusion layer forming composition, a method for manufacturing an impurity diffusion layer, and a method for manufacturing a solar cell element, and more specifically, forming an impurity diffusion layer in a specific portion of a silicon substrate which is a semiconductor substrate. More particularly, the present invention relates to a technology capable of reducing the internal stress of a silicon substrate, which is a semiconductor substrate, and to an impurity diffusion layer forming technology capable of suppressing damage at crystal grain boundaries, suppressing crystal defect growth, and suppressing warpage.
　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、受光面に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、続いてドナー元素含有化合物であるオキシ塩化リン（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、基板に一様に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。それゆえ、側面のｎ型拡散層を除去するためのサイドエッチングを行っている。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これを焼成して、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 formed on the light receiving surface is prepared so as to promote the light confinement effect, and then a donor element-containing compound such as phosphorus oxychloride (POCl 3 ), nitrogen, oxygen The n-type diffusion layer is uniformly formed on the substrate by performing several tens of minutes at 800 ° C. to 900 ° C. in the mixed gas atmosphere. 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, side etching is performed to remove the n-type diffusion layer on the side surface. Further, the n-type diffusion layer on the back surface needs to be converted into a p + -type diffusion layer, and an aluminum paste is applied on the n-type diffusion layer on the back surface, and this is baked. It was converted to a p + type diffusion layer.
　一方で、半導体の製造分野では、例えば、特開２００２－７５８９４号公報のように、ドナー元素含有化合物として、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、この方法ではドナー元素またはその含有化合物が、拡散源である溶液中から飛散するため、上記混合ガスを用いる気相反応法と同様、拡散層形成時にリンの拡散が側面及び裏面にもおよび、塗布した部分以外にもｎ型拡散層が形成される。 On the other hand, in the semiconductor manufacturing field, for example, as disclosed in JP-A-2002-75894, as a donor element-containing compound, phosphorus pentoxide (P 2 O 5 ) or ammonium dihydrogen phosphate (NH 4 H 2 PO 4 A method for forming an n-type diffusion layer by applying a solution containing a phosphate such as) has been proposed. However, in this method, since the donor element or the compound containing the same is scattered from the solution as the diffusion source, the diffusion of phosphorus also reaches the side surface and the back surface when the diffusion layer is formed, as in the gas phase reaction method using the mixed gas. The n-type diffusion layer is formed in addition to the applied part.
　また、前述のアルミニウムペーストを付与してｎ型拡散層からｐ＋型拡散層に変換する方法では、アルミニウムペーストから形成されるアルミ層は導電率が低く、シート抵抗を下げるためには、通常裏面全面に形成したアルミ層は焼成後において１０μｍ～２０μｍほどの厚みを有していなければならない。さらに、このように厚いアルミ層を形成すると、シリコンとアルミニウムでは熱膨張率が大きく異なることから、焼成および冷却の過程で、シリコン基板中に大きな内部応力を発生させ、結晶粒界のダメージ、結晶欠陥増長及び反りの原因となる場合があった。 In the method of converting the n-type diffusion layer to the p + -type diffusion layer by applying the above-described aluminum paste, the aluminum layer formed from the aluminum paste has a low conductivity, and in order to reduce the sheet resistance, it is The aluminum layer formed on the entire surface must have a thickness of about 10 μm to 20 μm after firing. Furthermore, when a thick aluminum layer is formed in this way, the thermal expansion coefficient differs greatly between silicon and aluminum, so that a large internal stress is generated in the silicon substrate during the firing and cooling process, resulting in damage to the grain boundaries, In some cases, defects increased and warped.
　この問題を解決するために、アルミニウムペーストの塗布量を減らし、裏面電極層を薄くする方法がある。しかしながら、アルミニウムペーストの塗布量を減らすと、ｐ型シリコン半導体基板の表面から内部に拡散するアルミニウムの量が不十分となる。その結果、所望のＢＳＦ（Ｂａｃｋ　Ｓｕｒｆａｃｅ　Ｆｉｅｌｄ）効果（ｐ＋型拡散層の存在により生成キャリアの収集効率が向上する効果）を達成することができないため、太陽電池の特性が低下するという問題が生じる。 In order to solve this problem, there is a method of reducing the amount of aluminum paste applied and making the back electrode layer thin. However, when the amount of aluminum paste applied is reduced, the amount of aluminum diffusing from the surface of the p-type silicon semiconductor substrate becomes insufficient. As a result, the desired BSF (Back Surface Field) effect (the effect of improving the collection efficiency of the generated carriers due to the presence of the p + -type diffusion layer) cannot be achieved, resulting in a problem that the characteristics of the solar cell deteriorate. .
　そこで、例えば、特開２００３－２２３８１３号公報では、アルミニウム粉末と、有機質ビヒクルと、熱膨張率がアルミニウムよりも小さく、かつ、溶融温度、軟化温度および分解温度のいずれかがアルミニウムの融点よりも高い無機化合物粉末とを含むペースト組成物が提案されている。 Therefore, for example, in Japanese Patent Application Laid-Open No. 2003-223913, aluminum powder, an organic vehicle, and a coefficient of thermal expansion are smaller than those of aluminum, and any of a melting temperature, a softening temperature, and a decomposition temperature is higher than the melting point of aluminum. A paste composition containing an inorganic compound powder has been proposed.
　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（通常は受光面、または表面）のみならず、もう一方の面（非受光面、または裏面）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, in forming a n-type diffusion layer, in the gas phase reaction using phosphorus oxychloride, not only one side (usually the light receiving surface or the surface) that originally requires the n-type diffusion layer but also the other side An n-type diffusion layer is also formed on the surface (non-light-receiving surface or 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特定の部分にｎ型拡散層を形成することが可能で、分散安定性に優れる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 an n-type diffusion layer is formed 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. It is an object of the present invention to provide an n-type diffusion layer-forming composition, a method for producing an n-type diffusion layer, and a method for producing a solar cell element.
　また、前出の特開２００３－２２３８１３号公報に記載のペースト組成物を用いた場合でも、充分に反りを抑制することができない場合があった。そこで本発明は、シリコン基板を用いた太陽電池セルの製造工程において、シリコン基板中の内部応力、基板の反りの発生を抑制しつつｐ型拡散層を形成することが可能なｐ型拡散層形成組成物であって、且つ分散安定性に優れるｐ型拡散層形成組成物、ｐ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。 Further, even when the paste composition described in the above-mentioned Japanese Patent Application Laid-Open No. 2003-223813 is used, there is a case where warpage cannot be sufficiently suppressed. Accordingly, the present invention provides a p-type diffusion layer formation capable of forming a p-type diffusion layer while suppressing the occurrence of internal stress in the silicon substrate and warping of the substrate in a manufacturing process of a solar cell using a silicon substrate. An object is to provide a p-type diffusion layer forming composition that is a composition and excellent in dispersion stability, a method for producing a p-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＞　ドナー元素又はアクセプタ元素を含むガラス粉末と、重量平均分子量が５０００以上５０００００以下であるバインダーと、溶剤とを含有する不純物拡散層形成組成物。 Means for solving the problems are as follows.
<1> An impurity diffusion layer forming composition comprising a glass powder containing a donor element or an acceptor element, a binder having a weight average molecular weight of 5,000 to 500,000, and a solvent.
＜２＞　ドナー元素を含むガラス粉末と、重量平均分子量が５０００以上５０００００以下であるバインダーと、溶剤とを含有するｎ型拡散層形成組成物。 <2> An n-type diffusion layer forming composition containing glass powder containing a donor element, a binder having a weight average molecular weight of 5,000 to 500,000, and a solvent.
＜３＞　前記ガラス粉末は、ガラス成分物質とドナー元素含有物質とを含み、前記ドナー元素含有物質の含有比率が該ガラス粉末に対して１質量％以上７５質量％以下である前記＜２＞に記載のｎ型拡散層形成組成物 <3> The <2>, wherein the glass powder includes a glass component substance and a donor element-containing substance, and the content ratio of the donor element-containing substance is 1% by mass to 75% by mass with respect to the glass powder. The n-type diffusion layer forming composition described
＜４＞　ｐＨ（２５℃）が２～１３の範囲である前記＜２＞又は＜３＞に記載のｎ型拡散層形成組成物。 <4> The composition for forming an n-type diffusion layer according to <2> or <3>, wherein the pH (25 ° C.) is in the range of 2 to 13.
＜５＞　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＜２＞～＜４＞のいずれか１項に記載のｎ型拡散層形成組成物。 <5> The n-type diffusion layer forming composition according to any one of <2> to <4>, wherein the donor element is at least one selected from P (phosphorus) and Sb (antimony).
＜６＞　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、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＜２＞～＜５＞のいずれか１項に記載のｎ型拡散層形成組成物。 <6> 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 , and MoO 3. <5> The n-type diffusion layer forming composition according to any one of the above.
＜７＞　更に、Ａｇ、Ｓｉ、Ｃｕ、Ｆｅ、Ｚｎ及びＭｎから選択される少なくとも１種の金属を含む前記＜２＞～＜６＞のいずれか１項に記載のｎ型拡散層形成組成物。 <7> The n-type diffusion layer forming composition according to any one of <2> to <6>, further including at least one metal selected from Ag, Si, Cu, Fe, Zn, and Mn. .
＜８＞　前記金属がＡｇ（銀）である前記＜７＞に記載のｎ型拡散層形成組成物。 <8> The n-type diffusion layer forming composition according to <7>, wherein the metal is Ag (silver).
＜９＞　半導体基板上に、前記＜２＞～＜８＞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。 <9> An n-type diffusion comprising a step of applying the n-type diffusion layer forming composition according to any one of <2> to <8> on a semiconductor substrate and a step of performing a thermal diffusion treatment. Layer manufacturing method.
＜１０＞　半導体基板上に、前記＜２＞～＜８＞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。 <10> A step of applying the n-type diffusion layer forming composition according to any one of <2> to <8> above 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 a process and the process of forming an electrode on the formed n type diffused layer.
＜１１＞　アクセプタ元素を含むガラス粉末と、重量平均分子量が５０００以上５０００００以下であるバインダーと、溶剤とを含有するｐ型拡散層形成組成物。 <11> A p-type diffusion layer forming composition containing glass powder containing an acceptor element, a binder having a weight average molecular weight of 5,000 to 500,000, and a solvent.
＜１２＞　前記ガラス粉末は、ガラス成分物質とアクセプタ元素含有物質とを含み、前記アクセプタ元素含有物質の該ガラス粉末における含有比率が１質量％以上９０質量％以下である前記＜１１＞に記載のｐ型拡散層形成組成物。 <12> The glass powder includes a glass component substance and an acceptor element-containing substance, and a content ratio of the acceptor element-containing substance in the glass powder is 1% by mass or more and 90% by mass or less. A p-type diffusion layer forming composition.
＜１３＞　ｐＨ（２５℃）が２～１３の範囲である前記＜１１＞又は＜１２＞に記載のｐ型拡散層形成組成物。 <13> The p-type diffusion layer forming composition according to <11> or <12>, wherein the pH (25 ° C.) is in the range of 2 to 13.
＜１４＞　前記アクセプタ元素が、Ｂ（ほう素）、Ａｌ（アルミニウム）及びＧａ（ガリウム）から選択される少なくとも１種である前記＜１１＞～＜１３＞のいずれか１項に記載のｐ型拡散層形成組成物。 <14> The p-type according to any one of <11> to <13>, wherein the acceptor element is at least one selected from B (boron), Al (aluminum), and Ga (gallium). Diffusion layer forming composition.
＜１５＞　前記アクセプタ元素を含むガラス粉末が、Ｂ２Ｏ３、Ａｌ２Ｏ３及びＧａ２Ｏ３から選択される少なくとも１種のアクセプタ元素含有物質と、ＳｉＯ２、Ｋ２Ｏ、Ｎａ２Ｏ、Ｌｉ２Ｏ、ＢａＯ、ＳｒＯ、ＣａＯ、ＭｇＯ、ＢｅＯ、ＺｎＯ、ＰｂＯ、ＣｄＯ、Ｔｌ２Ｏ、ＳｎＯ、ＺｒＯ２、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＜１１＞～＜１４＞のいずれか１項に記載のｐ型拡散層形成組成物。 <15> The glass powder containing the acceptor element is at least one acceptor element-containing material selected from B 2 O 3 , Al 2 O 3, and Ga 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, Tl 2 O, SnO, ZrO 2 , and MoO 3. The p-type diffusion layer forming composition according to any one of <11> to <14>.
＜１６＞　半導体基板上に、前記＜１１＞～＜１５＞のいずれか１項に記載のｐ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ｐ型拡散層の製造方法。 <16> A p-type diffusion having a step of applying the p-type diffusion layer forming composition according to any one of <11> to <15> on a semiconductor substrate and a step of performing a thermal diffusion treatment. Layer manufacturing method.
＜１７＞　半導体基板上に、前記＜１１＞～＜１５＞のいずれか１項に記載のｐ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ｐ型拡散層を形成する工程と、形成されたｐ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。 <17> A step of applying the p-type diffusion layer forming composition according to any one of the above <11> to <15> on the semiconductor substrate and a thermal diffusion treatment to form a p-type diffusion layer The manufacturing method of the solar cell element which has a process and the process of forming an electrode on the formed p-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特定の部分にｎ型拡散層を形成することが可能で、分散安定性に優れるｎ型拡散層形成組成物を提供することができる。また該ｎ型拡散層形成組成物を用いるｎ型拡散層の製造方法、及び太陽電池セルの製造方法を提供することができる。
　また、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、シリコン基板中の内部応力、基板の反りの発生を抑制しつつｐ型拡散層を形成することが可能なｐ型拡散層形成組成物であって、且つ分散安定性に優れるｐ型拡散層形成組成物、ｐ型拡散層の製造方法、及び太陽電池セルの製造方法の提供することができる。 According to the present invention, in the manufacturing process of a solar cell element using a silicon substrate, it is possible to form an n-type diffusion layer in a specific portion without forming an unnecessary n-type diffusion layer, thereby improving dispersion stability. An excellent n-type diffusion layer forming composition can be provided. Moreover, the manufacturing method of the n type diffused layer using this n type diffused layer formation composition and the manufacturing method of a photovoltaic cell can be provided.
In addition, according to the present invention, in the manufacturing process of a solar cell element using a silicon substrate, a p-type diffusion layer can be formed while suppressing internal stress in the silicon substrate and warping of the substrate. A p-type diffusion layer forming composition that is a diffusion layer forming composition and excellent in dispersion stability, a method for producing a p-type diffusion layer, and a method for producing a solar battery cell can be provided.
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.
　本発明は、ドナー元素又はアクセプタ元素を含むガラス粉末と、重量平均分子量が５０００以上５０００００以下であるバインダーと、溶剤とを含有する不純物拡散層形成組成物である。不純物拡散層形成組成物がｎ型拡散層形成組成物の場合には、前記ガラス粉末はドナー元素を含み、ｐ型拡散層形成組成物の場合には、前記ガラス粉末はアクセプタ元素を含む。 The present invention is an impurity diffusion layer forming composition containing a glass powder containing a donor element or an acceptor element, a binder having a weight average molecular weight of 5,000 or more and 500,000 or less, and a solvent. When the impurity diffusion layer forming composition is an n-type diffusion layer forming composition, the glass powder contains a donor element, and when the impurity diffusion layer forming composition is a p-type diffusion layer forming composition, the glass powder contains an acceptor element.
　ｎ型拡散層形成組成物及びｐ型拡散層形成組成物に含有されるバインダーの重量平均分子量が５０００以上５０００００以下の場合には、ｎ型拡散層形成組成物及びｐ型拡散層形成組成物をシリコン基板上に均一に塗布可能な粘度に調整することができる。また熱拡散処理においてバインダーを完全に燃焼でき、ドナー元素又はアクセプタ元素の拡散が容易になる。またｎ型拡散層形成組成物及びｐ型拡散層形成組成物の分散安定性が向上する。したがって、本発明のｎ型拡散層形成組成物及びｐ型拡散層形成組成物は分散安定性に優れ、特定の部分にｎ型拡散層又はｐ型拡散層を形成することができる。 When the weight average molecular weight of the binder contained in the n-type diffusion layer forming composition and the p-type diffusion layer forming composition is 5,000 or more and 500,000 or less, the n-type diffusion layer forming composition and the p-type diffusion layer forming composition are The viscosity can be adjusted so that it can be uniformly applied on the silicon substrate. Further, the binder can be completely burned in the thermal diffusion treatment, and the diffusion of the donor element or the acceptor element becomes easy. Further, the dispersion stability of the n-type diffusion layer forming composition and the p-type diffusion layer forming composition is improved. Therefore, the n-type diffusion layer forming composition and the p-type diffusion layer forming composition of the present invention are excellent in dispersion stability, and an n-type diffusion layer or a p-type diffusion layer can be formed in a specific portion.
　まず、本発明のｎ型拡散層形成組成物及びｐ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型拡散層の製造方法、ｐ型拡散層形成組成物を用いるｐ型拡散層の製造方法、及び太陽電池素子の製造方法について説明する。
　なお、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「～」を用いて示された数値範囲は、「～」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。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, an n-type diffusion layer forming composition and a p-type diffusion layer forming composition of the present invention will be described, and then an n-type diffusion layer manufacturing method using the n-type diffusion layer forming composition, p-type diffusion layer forming composition A method for manufacturing a p-type diffusion layer using a solar cell and a method for manufacturing a solar cell element will be described.
In the present 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 as long as the intended action of the process is achieved. included. In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the 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.
＜ｎ型拡散層形成組成物＞
　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むガラス粉末（以下、単に「ガラス粉末」と称する場合がある）と、重量平均分子量が５０００以上５０００００以下であるバインダーの少なくとも１種と、溶剤の少なくとも１種と、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、ドナー元素を含むガラス粉末を含有し、シリコン基板に塗布した後にこのドナー元素を熱拡散することで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、所望の部位にｎ型拡散層が形成され、裏面や側面には不要なｎ型拡散層が形成されない。 <N-type diffusion layer forming composition>
The composition for forming an n-type diffusion layer of the present invention includes at least one kind of glass powder containing at least a donor element (hereinafter sometimes simply referred to as “glass powder”) and a binder having a weight average molecular weight of 5,000 to 500,000. And at least one solvent, and may further contain other additives as required in consideration of coating properties and the like.
Here, the n-type diffusion layer forming composition contains a glass powder containing a donor element, and is a material capable of forming an n-type diffusion layer by thermally diffusing this donor element after being applied to a silicon substrate. Say. By using the n-type diffusion layer forming composition of the present invention, an n-type diffusion layer is formed at a desired site, and an unnecessary n-type diffusion layer is not formed on the back surface or side surface.
　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。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 necessary, 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. Therefore, 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. Although details will be described later, generation of internal stress in the silicon substrate due to the thickness of the back electrode is suppressed, and warpage of the 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おり、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 in the conventional gas phase reaction method and the method of applying a phosphate-containing solution, and thus the glass layer produced in the present invention is the same as the conventional method. Further, it can be removed by etching. 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。 Also, since the donor component of the glass powder is difficult to volatilize even during firing, the formation of an n-type diffusion layer not only on the surface but also on the back surface and side surfaces due to the generation of the volatilizing gas is suppressed. 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）、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), As (arsenic), and the like. 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、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、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 , Examples include 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 include SiO 2 , K 2 O, Na 2 O, Li 2 O. It is preferable to use at least one selected from BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 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－Ｖ２Ｏ５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－Ｖ２Ｏ５、Ｐ２Ｏ５－ＳｉＯ２－ＣａＯ等、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 , including P 2 O 5 -V 2 O 5 system, P 2 O 5 -SnO-based, P 2 O 5 -GeO 2 system, a P 2 O 5 as a donor element-containing material of P 2 O 5 -TeO 2 system, etc. Instead of P 2 O 5 in a system containing P 2 O 5 , a donor element-containing material is used. And glass powder of a system containing Sb 2 O 3 .
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 is exemplified, but glass powder containing three or more components such as P 2 O 5 —SiO 2 —V 2 O 5 and 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、ドナー元素のシリコン基板中へのドーピング濃度、ガラス粉末の溶融温度、軟化温度、ガラス転移温度、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、１質量％以上７５質量％以下であることが好ましい。 The content ratio of the glass component substance in the glass powder is preferably set as appropriate in consideration of the doping concentration of the donor element into the silicon substrate, the melting temperature of the glass powder, the softening temperature, the glass transition temperature, and the chemical durability. In general, the content is preferably 1% by mass or more and 75% by mass or less.
　ガラス粉末中のドナー元素含有物質の含有比率が１質量％以上であることで、ドナー元素のシリコン基板中へのドーピング濃度が低くなりすぎず、ｎ型拡散層が充分に形成される。またＰ２Ｏ５などのドナー元素含有物質の含有比率が７５質量％以下であることで、ガラス粉末中でドナー元素含有物質が吸湿し、例えば、ドナー元素含有物質がＰ２Ｏ５の場合にはリン酸（Ｈ３ＰＯ４）を形成することを抑制できる。この結果、Ｈ３ＰＯ４などの吸湿物質が熱拡散処理中に揮散してしまうことを抑制し、Ｐ（リン）などのドナー元素の拡散が側面及び裏面にも及び、表面のみならず、所望の部位以外の側面、裏面にもｎ型拡散層が形成されることを抑制できる。 When the content ratio of the donor element-containing substance in the glass powder is 1% by mass or more, the doping concentration of the donor element into the silicon substrate does not become too low, and the n-type diffusion layer is sufficiently formed. Moreover, when the content ratio of the donor element-containing material such as P 2 O 5 is 75% by mass or less, the donor element-containing material absorbs moisture in the glass powder. For example, when the donor element-containing material is P 2 O 5 Can suppress the formation of phosphoric acid (H 3 PO 4 ). As a result, moisture-absorbing substances such as H 3 PO 4 are suppressed from being volatilized during the thermal diffusion treatment, and the diffusion of the donor element such as P (phosphorus) extends to the side surface and the back surface as well as the surface. It is possible to prevent the n-type diffusion layer from being formed on the side surface and the back surface other than the part.
　また、ｎ型拡散層が充分に形成されるドナー元素の量を勘案しつつ、ｎ型拡散層形成組成物にドナー元素を一定量以上添加しても形成したｎ型拡散層を有する表面のシート抵抗は一定値以上には低下しなくなる点と、ドナー元素含有物質の揮散の影響を抑える必要がある点を考慮すると、ガラス粉末中におけるドナー元素含有物質の含有率は、２質量％以上７５質量％以下であることが好ましく、１０質量％以上７０質量％以下であることがより好ましい。 Further, a sheet having a surface having an n-type diffusion layer formed even when a certain amount or more of a donor element is added to the composition for forming an n-type diffusion layer while taking into account the amount of the donor element in which the n-type diffusion layer is sufficiently formed Considering that the resistance does not decrease beyond a certain value and that it is necessary to suppress the volatilization of the donor element-containing material, the content of the donor element-containing material in the glass powder is 2% by mass or more and 75% by mass. % Or less, and more preferably 10% by mass or more and 70% by mass or less.
　特に、ｎ型拡散層形成組成物を塗布した側の加熱処理後の表面のシート抵抗を変化させず、Ｈ３ＰＯ４などの吸湿物質の揮散の影響を抑えることを考慮すると、ガラス粉末中のドナー元素含有物質の含有比率は３０質量％以上７０質量％以下であることがいっそう好ましい。 In particular, in consideration of suppressing the influence of volatilization of a hygroscopic substance such as H 3 PO 4 without changing the sheet resistance of the surface after the heat treatment on the side where the n-type diffusion layer forming composition is applied, The content ratio of the donor element-containing material is more preferably 30% by mass or more and 70% by mass or less.
　また、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、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。 Further, the content ratio of the glass component substance in the glass powder is preferably set as appropriate in consideration of the melting temperature, the softening temperature, the glass transition temperature, and the chemical durability, and generally 0.1% by mass or more and 95% by mass. % Or less, more preferably 0.5% by mass or more and 90% by mass or less.
　具体的には、Ｐ２Ｏ５－ＳｉＯ２系ガラスの場合には、ＳｉＯ２の含有比率は、１質量％以上９０質量％以下であることが好ましく、３質量％以上８０質量％以下であることがより好ましい。 Specifically, in the case of P 2 O 5 —SiO 2 based glass, the content ratio of SiO 2 is preferably 1% by mass or more and 90% by mass or less, and more preferably 3% by mass or more and 80% by mass or less. It is more preferable.
　ガラス粉末の軟化点は、拡散処理時の拡散性、液だれの観点から、２００℃～１０００℃であることが好ましく、３００℃～９００℃であることがより好ましい。 The softening point of the glass powder is preferably 200 ° C. to 1000 ° C., more preferably 300 ° C. to 900 ° C., from the viewpoints of diffusibility during the diffusion treatment and dripping.
　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、例えば、前記ドナー元素含有物質とガラス成分物質を秤量し、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ジルコニア基板やカーボン基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, raw materials, for example, the donor element-containing material and the glass component material are weighed and filled in a 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 zirconia substrate, a carbon substrate 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. Generally, 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, and more preferably 1% by mass or more and 90% by mass or less.
　本発明のｎ型拡散層形成組成物は、重量平均分子量が５０００以上５０００００以下のバインダーの少なくとも１種と、溶剤の少なくとも１種とを含有する。これらは前記ガラス粉末の分散媒となる。 The n-type diffusion layer forming composition of the present invention contains at least one binder having a weight average molecular weight of 5000 to 500,000 and at least one solvent. These serve as a dispersion medium for the glass powder.
　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、スチレン樹脂及びこれらの共重合体、並びにシロキサン樹脂などを適宜選択し得る。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 and copolymers thereof, as well as appropriately selected and siloxane resin. These are used singly or in combination of two or more.
　本発明のｎ型拡散層形成組成物は、これに含まれるバインダーの重量平均分子量が５０００以上５０００００以下である。これにより、ｎ型拡散層形成組成物をシリコン基板上に均一に塗布可能な粘度に調整することができる。バインダーの分子量が５０００より小さいと、ｎ型拡散層形成組成物の粘度が増加してしまう場合がある。これは例えば、ガラス粒子に吸着させたときの立体的な反発作用が不足し、粒子同士が凝集してしまうためと考えることができる。 The n-type diffusion layer forming composition of the present invention has a weight average molecular weight of 5,000 or more and 500,000 or less of the binder contained therein. Thereby, it is possible to adjust the viscosity so that the n-type diffusion layer forming composition can be uniformly applied on the silicon substrate. If the molecular weight of the binder is less than 5000, the viscosity of the n-type diffusion layer forming composition may increase. This can be considered, for example, because the three-dimensional repulsion when adsorbed on glass particles is insufficient and the particles aggregate.
　一方、バインダーの重量平均分子量が５０００００より大きいと、バインダー同士が溶剤中で凝集してしまい、結果としてｎ型拡散層形成組成物の粘度が増加する場合がある。
　これに加え、バインダーの重量平均分子量が大きくなると、バインダーの燃焼温度が高くなり、熱拡散処理においてバインダーが完全に燃焼されず、ドナー元素の拡散が進行し難くなる他、バインダー中の不純物がシリコン基板に拡散してしまう可能性がある。 On the other hand, when the weight average molecular weight of the binder is larger than 500,000, the binders aggregate in the solvent, and as a result, the viscosity of the n-type diffusion layer forming composition may increase.
In addition, when the weight average molecular weight of the binder increases, the burning temperature of the binder increases, the binder is not completely burned in the thermal diffusion treatment, and the diffusion of the donor element is difficult to proceed. There is a possibility of diffusing to the substrate.
　以上を考慮すると、バインダーの分子量は６０００以上４５００００以下が好ましく、６５００以上４０００００以下がより好ましい。
　尚、バインダーの重量平均分子量は、ＧＰＣを用いる通常の方法で測定される。 Considering the above, the molecular weight of the binder is preferably 6000 or more and 450,000 or less, and more preferably 6500 or more and 400,000 or less.
In addition, the weight average molecular weight of a binder is measured by the normal method using GPC.
　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エチルエーテル、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、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、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モノメチルエーテル、エチレングリコールモノエチルエーテル、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 ethyl ether acetate, dipropylene glycol acetate Methyl ether, dipropylene glycol ethyl ether, glycol diacetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-butyl oxalate, 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, propylene glycol methyl ether acetate, propylene glycol ethyl Ester solvents such as ether acetate, propylene glycol propyl ether acetate, γ-butyrolactone, γ-valerolactone; acetonitrile Non-protons such as N-methylpyrrolidinone, N-ethylpyrrolidinone, N-propylpyrrolidinone, N-butylpyrrolidinone, N-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide Polar solvents: methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, sec-pen Tanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, n-octanol, 2-ethylhexanol, se c-octanol, n-nonyl alcohol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, phenol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, Alcohol solvents such as 1,2-propylene glycol, 1,3-butylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monophenyl ether, Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol Non-n-butyl ether, diethylene glycol mono-n-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 Glycol monoether solvents such as α-terpinene, α-terpineol, myrcene, alloocimene, limonene, dipentene, α-pinene, β-pinene, terpineol, carvone, ocimene, and ferrandrene; . 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 preferable from the viewpoint of applicability to the substrate.
　ｎ型拡散層形成組成物中のバインダーおよび溶剤の含有比率は、塗布性、ドナー元素含有物質濃度等を考慮し、適宜選択される。本発明においてバインダーの含有比率としては例えば、ｎ型拡散層形成組成物に対して０．０１質量％～５質量％とすることができ、分散安定性の観点から、０．１質量％～３質量％であることが好ましい。また溶剤の含有比率としては、ｎ型拡散層形成組成物に対して１質量％～６０質量％とすることができ、分散安定性の観点から、５質量％～４０質量％であることが好ましい。
　また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 binder and the solvent in the n-type diffusion layer forming composition is appropriately selected in consideration of coating properties, donor element-containing substance concentration, and the like. In the present invention, the content ratio of the binder can be, for example, 0.01% by mass to 5% by mass with respect to the n-type diffusion layer forming composition, and from the viewpoint of dispersion stability, 0.1% by mass to 3%. It is preferable that it is mass%. The content ratio of the solvent can be 1% by mass to 60% by mass with respect to the n-type diffusion layer forming composition, and is preferably 5% by mass to 40% by mass from the viewpoint of dispersion stability. .
The viscosity of the n-type diffusion layer forming composition is preferably 10 mPa · s or more and 1000000 mPa · s or less, more preferably 50 mPa · s or more and 500000 mPa · s or less in consideration of applicability.
　またｎ型拡散層形成組成物に、ｐＨ調整剤を少量添加することで、溶剤中のガラス粒子の分散性をさらに高めることも可能である。具体的には、ｐＨを調整することで、ゼータ電位（粒子表面電位の近似）を変化させ、ガラス粒子間に静電反発を付与することができる。 It is also possible to further enhance the dispersibility of the glass particles in the solvent by adding a small amount of a pH adjusting agent to the n-type diffusion layer forming composition. Specifically, by adjusting the pH, the zeta potential (approximation of the particle surface potential) can be changed, and electrostatic repulsion can be imparted between the glass particles.
　ｐＨ調整剤としては、例えば、希塩酸、希硫酸、希硝酸、酒石酸、クエン酸、フマル酸、リンゴ酸、フィチン酸、コハク酸、グルコン酸、乳酸、水酸化ナトリウム、炭酸カリウム、炭酸水素ナトリウム、炭酸ナトリウム等が挙げられる。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。 Examples of the pH adjuster include dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, tartaric acid, citric acid, fumaric acid, malic acid, phytic acid, succinic acid, gluconic acid, lactic acid, sodium hydroxide, potassium carbonate, sodium bicarbonate, carbonate Sodium etc. are mentioned. These are used singly or in combination of two or more.
　また、ｎ型拡散層形成組成物のｐＨは、ガラス組成の等電位点（ゼータ電位が０となるｐＨで、粒子が凝集しやすくなる）、耐酸性、耐アルカリ性を考慮して適宜設定することが望ましく、一般には、ｐＨ（２５℃）が２．０以上１３．０以下であることが好ましく、３．０以上１２．０以下であることがより好ましい。
　尚、ｐＨは２５℃において、通常のｐＨ測定装置を用いて測定される。 In addition, the pH of the n-type diffusion layer forming composition is appropriately set in consideration of the equipotential point of the glass composition (the pH at which the zeta potential becomes 0 and the particles easily aggregate), acid resistance, and alkali resistance. In general, the pH (25 ° C.) is preferably 2.0 or more and 13.0 or less, and more preferably 3.0 or more and 12.0 or less.
The pH is measured at 25 ° C. using a normal pH measuring device.
　具体的には、Ｐ２Ｏ５－ＳｉＯ２系ガラスの場合には、ｎ型拡散層形成組成物のｐＨ（２５℃）は、３．０以上１１．０以下であることが好ましく、５．０以上１０．０以下であることがより好ましい。 Specifically, in the case of P 2 O 5 —SiO 2 glass, the pH (25 ° C.) of the n-type diffusion layer forming composition is preferably 3.0 or more and 11.0 or less. More preferably, it is 0 or more and 10.0 or less.
　更に、ｎ型拡散層形成組成物は、その他の添加剤を含有してもよい。その他の添加物としては、例えば上記ガラス粉末と反応しやすい金属が挙げられる。
　ｎ型拡散層形成組成物は、半導体基板上に塗布され、高温で熱処理されることでｎ型拡散層を形成するが、その際に表面にガラスが形成される。このガラスは、ふっ酸等の酸に浸漬して除去されるが、ガラスの種類によっては除去し難いものがある。その場合に、Ａｇ、Ｍｎ、Ｃｕ、Ｆｅ、Ｚｎ、Ｓｉ等の金属を添加しておくことにより、酸洗浄後に容易にガラスを除去することができる。これらのなかでも、Ａｇ、Ｓｉ、Ｃｕ、Ｆｅ、Ｚｎ及びＭｎから選択される少なくとも１種を用いることが好ましく、Ａｇ、Ｓｉ及びＺｎから選択される少なくとも１種を用いることがより好ましく、Ａｇであることが特に好ましい。 Furthermore, the n-type diffusion layer forming composition may contain other additives. Examples of other additives include metals that easily react with the glass powder.
The n-type diffusion layer forming composition is applied on a semiconductor substrate and heat-treated at a high temperature to form an n-type diffusion layer. At that time, glass is formed on the surface. This glass is removed by dipping in an acid such as hydrofluoric acid, but some glass is difficult to remove depending on the type of glass. In that case, the glass can be easily removed after the acid cleaning by adding a metal such as Ag, Mn, Cu, Fe, Zn, or Si. Among these, it is preferable to use at least one selected from Ag, Si, Cu, Fe, Zn and Mn, more preferable to use at least one selected from Ag, Si and Zn. It is particularly preferred.
　前記金属の含有比率は、ガラスの種類や当該金属の種類によって適宜調整することが望ましく、一般的には上記ガラス粉末に対して０．０１質量％以上１０質量％以下であることが好ましい。また、前記金属は、金属単体、金属酸化物等の形態で用いることができる。 The content ratio of the metal is desirably adjusted as appropriate depending on the type of glass and the type of the metal, and is generally 0.01% by mass or more and 10% by mass or less with respect to the glass powder. Moreover, the said metal can be used with forms, such as a metal simple substance and a metal oxide.
＜ｐ型拡散層形成組成物＞
　本発明のｐ型拡散層形成組成物は、少なくともアクセプタ元素を含むガラス粉末（以下、単に「ガラス粉末」と称する場合がある）と、重量平均分子量が５０００以上５０００００以下であるバインダーの少なくとも１種と、溶剤の少なくとも１種と、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、ｐ型拡散層形成組成物とはアクセプタ元素を含有し、例えば、シリコン基板に塗布した後に熱拡散処理（焼成）することでこのアクセプタ元素を熱拡散させてｐ型拡散層を形成することが可能な材料をいう。本発明のｐ型拡散層形成組成物を用いることで、ｐ＋型拡散層形成工程とオーミックコンタクト形成工程とを分離でき、オーミックコンタクト形成のための電極材の選択肢が広がるとともに、電極の構造の選択肢も広がる。例えば銀等の低抵抗材を電極に用いれば薄い膜厚で低抵抗が達成できる。また、電極も全面に形成する必要はなく、櫛型等の形状のように部分的に形成してもよい。以上のように薄膜あるいは櫛型形状等の部分的形状にすることで、シリコン基板中の内部応力、基板の反りの発生を抑えながらｐ型拡散層を形成することが可能となる。 <P-type diffusion layer forming composition>
The p-type diffusion layer forming composition of the present invention includes at least one kind of glass powder containing at least an acceptor element (hereinafter sometimes simply referred to as “glass powder”) and a binder having a weight average molecular weight of 5,000 to 500,000. And at least one solvent, and may further contain other additives as required in consideration of coating properties and the like.
Here, the p-type diffusion layer forming composition contains an acceptor element. For example, the p-type diffusion layer is formed by thermally diffusing the acceptor element by applying thermal diffusion treatment (baking) after being applied to a silicon substrate. A material that can be used. By using the p-type diffusion layer forming composition of the present invention, the p + -type diffusion layer forming step and the ohmic contact forming step can be separated, and the choice of electrode material for forming the ohmic contact is widened. The options also expand. For example, if a low resistance material such as silver is used for the electrode, a low resistance can be achieved with a thin film thickness. Further, the electrodes need not be formed on the entire surface, and may be partially formed like a comb shape. As described above, by forming a partial shape such as a thin film or a comb shape, it is possible to form a p-type diffusion layer while suppressing the occurrence of internal stress in the silicon substrate and warping of the substrate.
　したがって、本発明のｐ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方法、つまりアルミペーストを印刷し、これを焼成してｎ型拡散層をｐ＋型拡散層にするのと同時にオーミックコンタクトを得る方法では発生してしまう基板中の内部応力及び基板の反りの発生が抑制される。
　さらにガラス粉末中のアクセプタ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所望の領域以外にまでｐ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、アクセプタ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。 Therefore, if the p-type diffusion layer forming composition of the present invention is applied, a conventionally widely employed method, that is, printing an aluminum paste and firing it to turn the n-type diffusion layer into a p + -type diffusion layer. At the same time, the internal stress in the substrate and the warpage of the substrate that are generated by the method of obtaining the ohmic contact are suppressed.
Furthermore, since the acceptor component in the glass powder is not easily volatilized even during firing, the formation of a p-type diffusion layer other than the desired region due to the generation of the volatilizing gas is suppressed. The reason for this is considered that the acceptor component is bonded to an element in the glass powder or is taken into the glass, so that it is difficult to volatilize.
　更に、本発明のｐ型拡散層形成粗組成物は、これに含まれるガラス粉末中のアクセプタ元素含有物質の含有比率が、１質量％以上９０質量％以下であることが好ましい。これにより、表面抵抗値が低下し、太陽電池セルとしての性能の向上が可能となる。アクセプタ元素含有物質の詳細は後述する。 Furthermore, in the p-type diffusion layer forming crude composition of the present invention, the content ratio of the acceptor element-containing substance in the glass powder contained therein is preferably 1% by mass or more and 90% by mass or less. Thereby, a surface resistance value falls and the performance as a photovoltaic cell can be improved. Details of the acceptor element-containing material will be described later.
　本発明に係るアクセプタ元素を含むガラス粉末について、詳細に説明する。
　アクセプタ元素とは、シリコン基板中にドーピングさせることによってｐ型拡散層を形成することが可能な元素である。アクセプタ元素としては第１３族の元素が使用でき、例えばＢ（ほう素）、Ａｌ（アルミニウム）及びＧａ（ガリウム）等が挙げられる。 The glass powder containing the acceptor element according to the present invention will be described in detail.
An acceptor element is an element that can form a p-type diffusion layer by doping into a silicon substrate. As the acceptor element, a Group 13 element can be used, and examples thereof include B (boron), Al (aluminum), and Ga (gallium).
　アクセプタ元素をガラス粉末に導入するために用いるアクセプタ元素含有物質としては、Ｂ２Ｏ３、Ａｌ２Ｏ３、及びＧａ２Ｏ３が挙げられ、Ｂ２Ｏ３、Ａｌ２Ｏ３及びＧａ２Ｏ３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 acceptor element-containing material used for introducing the acceptor element into the glass powder include B 2 O 3 , Al 2 O 3 , and Ga 2 O 3 , and B 2 O 3 , Al 2 O 3, and Ga 2 O. It is preferable to use at least one selected from 3 .
　また、アクセプタ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。更に以下に記す成分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、Ｔｌ２Ｏ、ＳｎＯ、ＺｒＯ２、ＭｏＯ３、Ｌａ２Ｏ３、Ｎｂ２Ｏ５、Ｔａ２Ｏ５、Ｙ２Ｏ３、ＴｉＯ２、ＧｅＯ２、ＴｅＯ２及びＬｕ２Ｏ３等が挙げられ、ＳｉＯ２、Ｋ２Ｏ、Ｎａ２Ｏ、Ｌｉ２Ｏ、ＢａＯ、ＳｒＯ、ＣａＯ、ＭｇＯ、ＢｅＯ、ＺｎＯ、ＰｂＯ、ＣｄＯ、Ｔｌ２Ｏ、ＳｎＯ、ＺｒＯ２、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 an acceptor 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 components 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, Tl 2 O, SnO, ZrO 2 , MoO 3 , La 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Y 2 O 3 , TiO 2 , GeO 2 , TeO 2, and Lu 2 O 3, and the like can be mentioned. SiO 2 , K 2 O, Na 2 O, Li 2 It is preferable to use at least one selected from O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, Tl 2 O, SnO, ZrO 2 , and MoO 3 .
　アクセプタ元素を含むガラス粉末の具体例としては、前記アクセプタ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、Ｂ２Ｏ３－ＳｉＯ２系（アクセプタ元素含有物質－ガラス成分物質の順で記載、以下同様）、Ｂ２Ｏ３－ＺｎＯ系、Ｂ２Ｏ３－ＰｂＯ系、Ｂ２Ｏ３単独系等のアクセプタ元素含有物質としてＢ２Ｏ３を含む系、Ａｌ２Ｏ３－ＳｉＯ２系等のアクセプタ元素含有物質としてＡｌ２Ｏ３を含む系、Ｇａ２Ｏ３－ＳｉＯ２系等のアクセプタ元素含有物質としてＧａ２Ｏ３を含む系などのガラスが挙げられる。
　また、Ａｌ２Ｏ３－Ｂ２Ｏ３系、Ｇａ２Ｏ３－Ｂ２Ｏ３系等のように、２種類以上のアクセプタ元素含有物質を含むガラス粉末でもよい。
　上記では１成分ガラスあるいは２成分を含む複合ガラスを例示したが、Ｂ２Ｏ３－ＳｉＯ２－Ｎａ２Ｏ等必要に応じて３種類以上の複合ガラスでもよい。 Specific examples of the glass powder containing an acceptor element include a system containing both the acceptor element-containing substance and the glass component substance, and a B 2 O 3 —SiO 2 system (in order of acceptor element-containing substance—glass component substance). And the same applies hereinafter), B 2 O 3 —ZnO system, B 2 O 3 —PbO system, B 2 O 3 single system, etc., a system containing B 2 O 3 as an acceptor element-containing substance, Al 2 O 3 —SiO Glasses such as a system containing Al 2 O 3 as the acceptor element-containing material such as a 2 system and a system containing Ga 2 O 3 as the acceptor element containing material such as a Ga 2 O 3 —SiO 2 system can be given.
Further, a glass powder containing two or more kinds of acceptor element-containing materials such as Al 2 O 3 —B 2 O 3 series, Ga 2 O 3 —B 2 O 3 series, etc. may be used.
In the above, a single component glass or a composite glass containing two components is exemplified, but three or more types of composite glasses such as B 2 O 3 —SiO 2 —Na 2 O may be used as necessary.
　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、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 as appropriate in consideration of the melting temperature, the softening temperature, the glass transition temperature, and the chemical durability, and is generally 0.1% by mass to 95% by mass. It is preferable that it is 0.5 mass% or more and 90 mass% or less.
　ガラス粉末の軟化温度は、拡散処理時の拡散性、液だれの観点から、２００℃～１０００℃であることが好ましく、３００℃～９００℃であることがより好ましい。 The softening temperature of the glass powder is preferably 200 ° C. to 1000 ° C., more preferably 300 ° C. to 900 ° C., from the viewpoints of diffusibility during the diffusion treatment and dripping.
　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、および鱗片状等が挙げられ、ｐ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、または板状であることが望ましい。ガラス粉末の粒径は、５０μｍ以下であることが望ましい。５０μｍ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１０μｍ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 applicability to a substrate and uniform diffusibility when a p-type diffusion layer forming composition is used. It is desirable to have a substantially spherical shape, flat shape, or plate shape. The particle size of the glass powder is desirably 50 μm or less. When glass powder having a particle size of 50 μm or less is used, a smooth coating film is easily obtained. Further, the particle size of the glass powder is more preferably 10 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.
　アクセプタ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ジルコニア基板やカーボン基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 an acceptor 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 zirconia substrate, a carbon substrate 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.
　ｐ型拡散層形成組成物中のアクセプタ元素を含むガラス粉末の含有比率は、塗布性、アクセプタ元素の拡散性等を考慮し決定される。一般には、ｐ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い。 The content ratio of the glass powder containing the acceptor element in the p-type diffusion layer forming composition is determined in consideration of applicability, acceptor element diffusibility, and the like. Generally, the content ratio of the glass powder in the p-type diffusion layer forming composition is preferably 0.1% by mass or more and 95% by mass or less, and more preferably 1% by mass or more and 90% by mass or less.
　本発明のｐ型拡散層形成組成物は、重量平均分子量が５０００以上５０００００以下のバインダーの少なくとも１種と、溶剤の少なくとも１種とを含有する。これらは前記ガラス粉末の分散媒となる。 The p-type diffusion layer forming composition of the present invention contains at least one binder having a weight average molecular weight of 5000 to 500,000 and at least one solvent. These serve as a dispersion medium for the glass powder.
　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、スチレン樹脂及びこれらの共重合体、並びにシロキサン樹脂などを適宜選択し得る。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 and copolymers thereof, as well as appropriately selected and siloxane resin. These are used singly or in combination of two or more.
　本発明のｐ型拡散層形成組成物は、これに含まれるバインダーの重量平均分子量が５０００以上５０００００以下である。これにより、ｐ型拡散層形成組成物をシリコン基板上に均一に塗布可能な粘度に調整することができる。バインダーの分子量が５０００より小さいと、ｐ型拡散層形成組成物の粘度が増加してしまう場合がある。これは例えば、ガラス粒子に吸着させたときの立体的な反発作用が不足し、粒子同士が凝集してしまうためと考えることができる。 In the p-type diffusion layer forming composition of the present invention, the binder contained therein has a weight average molecular weight of 5,000 to 500,000. Thereby, the viscosity which can apply | coat a p-type diffused layer formation composition on a silicon substrate uniformly can be adjusted. If the molecular weight of the binder is less than 5000, the viscosity of the p-type diffusion layer forming composition may increase. This can be considered, for example, because the three-dimensional repulsion when adsorbed on glass particles is insufficient and the particles aggregate.
　一方、バインダーの重量平均分子量が５０００００より大きいと、バインダー同士が溶剤中で凝集してしまい、結果としてｐ型拡散層形成組成物の粘度が増加する場合がある。
　これに加え、バインダーの重量平均分子量が大きくなると、バインダーの燃焼温度が高くなり、熱拡散処理においてバインダーが完全に燃焼されず、ドナー元素の拡散が進行し難くなる他、バインダー中の不純物がシリコン基板に拡散してしまう可能性がある。 On the other hand, when the weight average molecular weight of the binder is larger than 500,000, the binders aggregate in the solvent, and as a result, the viscosity of the p-type diffusion layer forming composition may increase.
In addition, when the weight average molecular weight of the binder increases, the burning temperature of the binder increases, the binder is not completely burned in the thermal diffusion treatment, and the diffusion of the donor element is difficult to proceed. There is a possibility of diffusing to the substrate.
　以上を考慮すると、バインダーの分子量は６０００以上４５００００以下が好ましく、６５００以上４０００００以下がより好ましい。
　尚、バインダーの重量平均分子量は、ＧＰＣを用いる通常の方法で測定される。 Considering the above, the molecular weight of the binder is preferably 6000 or more and 450,000 or less, and more preferably 6500 or more and 400,000 or less.
In addition, the weight average molecular weight of a binder is measured by the normal method using GPC.
　ｐ型拡散層形成組成物における溶剤は、ｎ型拡散層形成組成物における溶剤と同様のものを用いることができ、好適な範囲も同様である。
　ｐ型拡散層形成組成物中のバインダーおよび溶剤の含有比率は、塗布性、ドナー元素含有物質濃度等を考慮し、適宜選択される。本発明においてバインダーの含有比率としては例えば、ｎ型拡散層形成組成物に対して０．０１質量％～５質量％とすることができ、分散安定性の観点から、０．１質量％～３質量％であることが好ましい。また溶剤の含有比率としては、ｎ型拡散層形成組成物に対して１質量％～６０質量％とすることができ、分散安定性の観点から、５質量％～４０質量％であることが好ましい。
　ｐ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。 As the solvent in the p-type diffusion layer forming composition, the same solvent as the solvent in the n-type diffusion layer forming composition can be used, and the preferred range is also the same.
The content ratio of the binder and the solvent in the p-type diffusion layer forming composition is appropriately selected in consideration of coating properties, donor element-containing substance concentration, and the like. In the present invention, the content ratio of the binder can be, for example, 0.01% by mass to 5% by mass with respect to the n-type diffusion layer forming composition. It is preferable that it is mass%. The content ratio of the solvent can be 1% by mass to 60% by mass with respect to the n-type diffusion layer forming composition, and is preferably 5% by mass to 40% by mass from the viewpoint of dispersion stability. .
The viscosity of the p-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.
　またｐ型拡散層形成組成物に、ｐＨ調整剤を少量添加することで、溶剤中のガラス粒子の分散性をさらに高めることも可能である。具体的には、ｐＨを調整することで、ゼータ電位（粒子表面電位の近似）を変化させ、ガラス粒子間に静電反発を付与することができる。 It is also possible to further increase the dispersibility of the glass particles in the solvent by adding a small amount of a pH adjusting agent to the p-type diffusion layer forming composition. Specifically, by adjusting the pH, the zeta potential (approximation of the particle surface potential) can be changed, and electrostatic repulsion can be imparted between the glass particles.
　ｐＨ調整剤としては、例えば、希塩酸、希硫酸、希硝酸、酒石酸、クエン酸、フマル酸、リンゴ酸、フィチン酸、コハク酸、グルコン酸、乳酸、水酸化ナトリウム、炭酸カリウム、炭酸水素ナトリウム、炭酸ナトリウム等が挙げられる。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。 Examples of the pH adjuster include dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, tartaric acid, citric acid, fumaric acid, malic acid, phytic acid, succinic acid, gluconic acid, lactic acid, sodium hydroxide, potassium carbonate, sodium bicarbonate, carbonate Sodium etc. are mentioned. These are used singly or in combination of two or more.
　また、ｐ型拡散層形成組成物のｐＨは、ガラス組成の等電位点（ゼータ電位が０となるｐＨで、粒子が凝集しやすくなる）、耐酸性、耐アルカリ性を考慮して適宜設定することが望ましく、一般には、ｐＨ（２５℃）が２．０以上１３．０以下であることが好ましく、３．０以上１２．０以下であることがより好ましい。
　尚、ｐＨは２５℃において、通常のｐＨ測定装置を用いて測定される。 In addition, the pH of the p-type diffusion layer forming composition is appropriately set in consideration of the equipotential point of the glass composition (the pH at which the zeta potential becomes 0 and the particles easily aggregate), acid resistance, and alkali resistance. In general, the pH (25 ° C.) is preferably 2.0 or more and 13.0 or less, and more preferably 3.0 or more and 12.0 or less.
The pH is measured at 25 ° C. using a normal pH measuring device.
　具体的には、Ｂ２Ｏ３－ＳｉＯ２系ガラスの場合には、ｐ型拡散層形成組成物のｐＨ（２５℃）は、３．０以上１１．０以下であることが好ましく、５．０以上１０．０以下であることがより好ましい。 Specifically, in the case of B 2 O 3 —SiO 2 glass, the pH (25 ° C.) of the p-type diffusion layer forming composition is preferably 3.0 or more and 11.0 or less. More preferably, it is 0 or more and 10.0 or less.
＜ｎ型拡散層及び太陽電池素子の製造方法＞
　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。 <Manufacturing method of n-type diffusion layer and solar cell element>
Next, the manufacturing method of the n type diffused layer and solar cell element of this invention is demonstrated, referring 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無いが、例えば、ガラス粉末の塗布量として１０ｇ／ｍ２～２５０ｇ／ｍ２とすることができ、２０ｇ／ｍ２～１５０ｇ／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.
The coating amount of the n-type diffusion layer forming composition is not particularly limited. For example, the coating amount of the glass powder can be 10 g / m 2 to 250 g / m 2, and 20 g / m 2 to 150 g / m 2. 2 is preferable.
　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が必要な場合がある。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 necessary 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ペーストによる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１３を付与し、高濃度電界層１４を形成することができる。
　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、例えば既述の本発明のｐ型拡散層形成組成物を用いることができる。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。 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 paste. Without being done, any conventionally known method can be adopted, and the options of the manufacturing method are expanded. Therefore, for example, the high-concentration electric field layer 14 can be formed by applying the composition 13 containing a Group 13 element such as B (boron).
As the composition 13 containing a Group 13 element such as B (boron), for example, the aforementioned p-type diffusion layer forming composition of the present invention can be used. 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、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の含有率などに応じて適宜選択することができる。例えば、１分～６０分間とすることができ、２分～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.
The thermal diffusion treatment time can be appropriately selected according to the content of the donor element contained in the n-type diffusion layer forming composition. For example, it can be 1 minute to 60 minutes, 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、このリン酸ガラス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 phosphate glass 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。 In the method for forming an n-type diffusion layer of the present invention in which the n-type diffusion layer 12 is formed using the n-type diffusion layer forming composition 11 of the present invention shown in FIGS. Only the n-type diffusion layer 12 is formed, and unnecessary n-type diffusion layers are not formed on the back surface and side surfaces.
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＋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、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, in order to sufficiently convert to the p-type diffusion layer and to form a high concentration electric field layer of p + layer, an aluminum amount of a certain amount or more is required. Therefore, the aluminum layer is formed thick. There was a need. 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 warp easily damages the 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 elements tend 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、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 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、本発明のｐ型拡散層形成組成物を用いて、ｐ＋型拡散層を形成してもよい。
　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, a p + -type diffusion layer may be formed using the p-type diffusion layer forming composition of the present invention.
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１３．３Ｐａ（０．１Ｔｏｒｒ）～２６６．６Ｐａ（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 13.3 Pa (0.1 Torr) to 266.6 Pa (2 Torr), It is formed under conditions where the temperature is 300 ° C. to 550 ° C. and the frequency for plasma 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、又は銅など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 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 an enlarged perspective view illustrating 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.
＜ｐ型拡散層及び太陽電池素子の製造方法＞
　次に、本発明のｐ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。
　まず、ｐ型半導体基板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。この工程は、ｎ型拡散層の形成において、図１（１）を参照しながら説明したものと同様である。 <Manufacturing method of p-type diffusion layer and solar cell element>
Next, the manufacturing method of the p-type diffused layer and solar cell element of this invention is demonstrated.
First, an alkaline solution is applied to a silicon substrate which is a p-type semiconductor substrate to remove a damaged layer, and a texture structure is obtained by etching. This process is the same as that described with reference to FIG. 1A in the formation of the n-type diffusion layer.
　次に、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。このとき、オキシ塩化リン雰囲気を用いた方法では、リンの拡散は側面及び裏面にも及び、ｎ型拡散層は表面のみならず、側面、裏面にも形成される。そのために、側面のｎ型拡散層を除去するために、サイドエッチングが施される。 Next, tens of minutes of treatment is performed at 800 ° C. to 900 ° C. in a mixed gas atmosphere of phosphorus oxychloride (POCl 3 ), nitrogen, and oxygen to uniformly form an n-type diffusion layer. At this time, in the method using the phosphorus oxychloride atmosphere, the diffusion of phosphorus extends to the side surface and the back surface, and the n-type diffusion layer is formed not only on the surface but also on the side surface and the back surface. Therefore, side etching is performed to remove the n-type diffusion layer on the side surface.
　そして、ｐ型半導体基板の裏面すなわち受光面ではない面のｎ型拡散層の上に、上記ｐ型拡散層形成組成物を塗布する。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ｐ型拡散層形成組成物の塗布量としては特に制限は無いが、例えば、ガラス粉末の塗布量として１０ｇ／ｍ２～２５０ｇ／ｍ２とすることができ、２０ｇ／ｍ２～１５０ｇ／ｍ２であることが好ましい。 Then, the p-type diffusion layer forming composition is applied onto the n-type diffusion layer on the back surface of the p-type semiconductor substrate, that is, the surface that is not 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.
The coating amount of the p-type diffusion layer forming composition is not particularly limited. For example, the coating amount of the glass powder can be 10 g / m 2 to 250 g / m 2, and 20 g / m 2 to 150 g / m 2. 2 is preferable.
　なお、ｐ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が必要な場合がある。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 p-type diffusion layer forming composition, a drying step for volatilizing the solvent contained in the composition may be necessary 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.
　上記ｐ型拡散層形成組成物を塗布した半導体基板を、６００℃～１２００℃で熱処理する。この熱処理により、半導体基板中へアクセプタ元素が拡散し、ｐ＋型拡散層が形成される。熱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、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、ｐ型拡散層形成組成物に含まれるアクセプタ元素の含有率など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。 The semiconductor substrate coated with the p-type diffusion layer forming composition is heat-treated at 600 ° C. to 1200 ° C. By this heat treatment, the acceptor element diffuses into the semiconductor substrate, and a p + -type diffusion layer is formed. A known continuous furnace, batch furnace, or the like can be applied to the heat treatment. Further, the furnace atmosphere during the thermal diffusion treatment can be appropriately adjusted to air, oxygen, nitrogen or the like.
The thermal diffusion treatment time can be appropriately selected according to the content of the acceptor element contained in the p-type diffusion layer forming composition. For example, it can be 1 minute to 60 minutes, and more preferably 2 minutes to 30 minutes.
　ｐ＋型拡散層の表面には、ガラス層が形成されているため、このガラス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 is formed on the surface of the p + type diffusion layer, the glass 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.
　また、従来の製造方法では、裏面にアルミペーストを印刷し、これを焼成してｎ型拡散層をｐ＋型拡散層にするのと同時に、オーミックコンタクトを得ている。しかしながら、アルミペーストから形成されるアルミ層の導電率は低く、シート抵抗を下げるために、通常裏面全面に形成したアルミ層は焼成後において１０μｍ～２０μｍほどの厚みを有していなければならない。さらに、このように厚いアルミ層を形成すると、シリコンとアルミでは熱膨張率が大きく異なることから、焼成および冷却の過程で、シリコン基板中に大きな内部応力を発生させ、反りの原因となる。
　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、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、更に素子が割れ易い傾向にある。 Further, in the conventional manufacturing method, an aluminum paste is printed on the back surface, and this is baked to change the n-type diffusion layer into a p + -type diffusion layer, and at the same time, an ohmic contact is obtained. However, the electrical conductivity of the aluminum layer formed from the aluminum paste is low, and in order to reduce the sheet resistance, the aluminum layer generally formed on the entire back surface must have a thickness of about 10 μm to 20 μm after firing. Further, when such a thick aluminum layer is formed, the thermal expansion coefficient differs greatly between silicon and aluminum, so that a large internal stress is generated in the silicon substrate during the firing and cooling process, causing warpage.
This internal stress has a problem that the crystal grain boundary is damaged and the power loss increases. Further, the warp easily damages the 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 elements tend to be easily broken.
　しかし本発明の製造方法によれば、上記本発明のｐ型拡散層形成組成物によってｎ型拡散層をｐ＋型拡散層に変換した後、別途このｐ＋型拡散層の上に電極を設ける。そのため裏面の電極に用いる材料は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、裏面の電極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り、さらに全面に形成する必要もなくなる。そのため焼成および冷却の過程で発生するシリコン基板中の内部応力及び反りを低減できる。 However, according to the manufacturing method of the present invention, after the n-type diffusion layer is converted into the p + -type diffusion layer by the p-type diffusion layer forming composition of the present invention, an electrode is separately provided on the p + -type diffusion layer. . Therefore, the material used for the back electrode is not limited to aluminum. For example, Ag (silver) or Cu (copper) can be applied, and the thickness of the back electrode can be made thinner than the conventional one. Further, it is not necessary to form the entire surface. Therefore, it is possible to reduce internal stress and warpage in the silicon substrate that occur during the firing and cooling processes.
　そして、ガラスをエッチングにより除去した後、上記形成したｎ型拡散層の上に反射防止膜を形成する。この工程は、ｎ型拡散層の形成において、図１（４）を参照しながら説明したものと同様である。 Then, after removing the glass by etching, an antireflection film is formed on the n-type diffusion layer formed above. This step is the same as that described with reference to FIG. 1 (4) in the formation of the n-type diffusion layer.
　表面（受光面）の反射防止膜上に、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、表面電極を形成する。この工程は、ｎ型拡散層の形成において、図１（５）を参照しながら説明したものと同様である。 The surface electrode is formed by applying a surface electrode metal paste on the surface (light receiving surface) of the antireflection film by screen printing and drying. This step is the same as that described with reference to FIG. 1 (5) in the formation of the n-type diffusion layer.
　次いで、上記裏面のｐ＋型拡散層上にも裏面電極を形成する。この裏面電極の形成工程も、ｎ型拡散層で説明したものと同様である。 Next, a back electrode is also formed on the p + -type diffusion layer on the back surface. The back electrode formation process is also the same as that described for the n-type diffusion layer.
　上記電極を焼成して、太陽電池素子を完成させる。この工程は、ｎ型拡散層の形成において、図１（６）を参照しながら説明したものと同様である。 The above electrode is fired to complete the solar cell element. This process is the same as that described with reference to FIG. 1 (6) in the formation of the n-type diffusion layer.
　なお上述のｐ型拡散層及び太陽電池素子の製造方法では、ｐ型半導体基板であるシリコン基板にｎ型拡散層を形成するのに、オキシ塩化リン（ＰＯＣｌ３）、窒素および酸素の混合ガスを用いているが、前述のｎ型拡散層形成組成物を用いてｎ型拡散層を形成してもよい。 In the above-described method for manufacturing a p-type diffusion layer and a solar cell element, a mixed gas of phosphorus oxychloride (POCl 3 ), nitrogen and oxygen is used to form an n-type diffusion layer on a silicon substrate which is a p-type semiconductor substrate. However, the n-type diffusion layer may be formed using the above-described n-type diffusion layer forming composition.
　ｎ型拡散層の形成に上記ｎ型拡散層形成組成物を用いる方法では、まず、ｐ型半導体基板の表面である受光面にｎ型拡散層形成組成物を塗布し、裏面に本発明のｐ型拡散層形成組成物を塗布し、６００℃～１２００℃で熱拡散処理する。この熱拡散処理により、表面ではｐ型半導体基板中へドナー元素が拡散してｎ型拡散層が形成され、裏面ではアクセプタ元素が拡散してｐ＋型拡散層が形成される。この工程以外は上記方法と同様の工程により、太陽電池素子が作製される。 In the method of using the n-type diffusion layer forming composition for forming the n-type diffusion layer, first, the n-type diffusion layer forming composition is applied to the light-receiving surface which is the surface of the p-type semiconductor substrate, and the back surface of the p-type semiconductor substrate according to the present invention is applied. The mold diffusion layer forming composition is applied and subjected to thermal diffusion treatment at 600 ° C. to 1200 ° C. By this thermal diffusion treatment, the donor element diffuses into the p-type semiconductor substrate on the front surface to form an n-type diffusion layer, and the acceptor element diffuses on the back surface to form a p + -type diffusion layer. Except for this step, a solar cell element is produced by the same steps as those described above.
　また上記では、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及びｐ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及びｐ型拡散層形成組成物は、特定の部位にのみｎ型拡散部位及びｐ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 provided on the respective layers has been described. If the diffusion layer forming composition and the p-type diffusion layer forming composition are used, a back contact type solar cell element can also be produced.
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 and the p-type diffusion layer forming composition of the present invention can form an n-type diffusion site and a p-type diffusion site only at a specific site, and thus a back contact solar cell. It can be suitably applied to the manufacture of elements.
　なお、日本出願２０１０－１５５１７３号および２０１０－１５５１７４号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、および技術規格は、個々の文献、特許出願、およ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。 The entire disclosures of Japanese Application Nos. 2010-155173 and 2010-155174 are 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 described 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。
　またバインダーの重量平均分子量は、市販品についてはカタログデータを採用し、不明なものについては、ＧＰＣを用いてポリエチレン換算の重量平均分子量として測定した。 Examples of the present invention will be described more specifically below, but the present invention is not limited to these examples. Unless otherwise stated, all chemicals used reagents. “%” Means “% by mass” unless otherwise specified.
Further, the weight average molecular weight of the binder was measured as a weight average molecular weight in terms of polyethylene using GPC for a commercially available product and catalog data for unknown ones.
［実施例１Ａ］
　Ｐ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５含有量：１０％）粉末２０ｇと、バインダーとしてエチルセルロース（重量平均分子量１４００００）０．３ｇ、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１を調製した。
　得られたｎ型拡散層形成組成物のｐＨを２５℃で、ｐＨ測定装置を用いて測定したところ、ｐＨ（２５℃）は５．６であった。 [Example 1A]
20 g of P 2 O 5 —SiO 2 glass (P 2 O 5 content: 10%) powder, 0.3 g of ethyl cellulose (weight average molecular weight 140000) as a binder, and 7 g of 2- (2-butoxyethoxy) ethyl acetate Then, using an automatic mortar kneading apparatus, the mixture was made into a paste to prepare an n-type diffusion layer forming composition 1.
When the pH of the obtained n-type diffusion layer forming composition was measured at 25 ° C. using a pH measuring device, the pH (25 ° C.) was 5.6.
［実施例２Ａ］
　実施例１Ａにおいて、バインダーを重量平均分子量が３０００００のエチルセルロースに代えたこと以外は、実施例１Ａと同様にｎ型拡散層形成組成物２を調製した。ｐＨ（２５℃）は５．６であった。 [Example 2A]
In Example 1A, an n-type diffusion layer forming composition 2 was prepared in the same manner as in Example 1A, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 300,000. The pH (25 ° C.) was 5.6.
［実施例３Ａ］
　実施例１Ａにおいて、ガラス粉末をＰ２Ｏ５－ＺｎＯ系ガラス粉末（Ｐ２Ｏ５含有量：１０％）に代えたこと以外は、実施例１Ａと同様にｎ型拡散層形成組成物３を調製した。ｐＨ（２５℃）は５．６であった。 [Example 3A]
In Example 1A, except that the glass powder was replaced with P 2 O 5 —ZnO-based glass powder (P 2 O 5 content: 10%), an n-type diffusion layer forming composition 3 was prepared in the same manner as in Example 1A. Prepared. The pH (25 ° C.) was 5.6.
［実施例４Ａ］
　実施例１Ａにおいて、バインダーをポリビニルアルコール（重量平均分子量２５００００）に代えたこと以外は、実施例１Ａと同様にｎ型拡散層形成組成物４を調製した。ｐＨ（２５℃）は５．６であった。 [Example 4A]
In Example 1A, an n-type diffusion layer forming composition 4 was prepared in the same manner as in Example 1A, except that the binder was changed to polyvinyl alcohol (weight average molecular weight 250,000). The pH (25 ° C.) was 5.6.
［実施例５Ａ］
　Ｐ２Ｏ５－ＳｉＯ２系ガラス（Ｐ２Ｏ５含有量：１０％）粉末１９．７ｇと、Ａｇ０．３ｇと、エチルセルロース（分子量１４００００）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５を調製した。ｐＨ（２５℃）は５．６であった。 [Example 5A]
19.7 g of P 2 O 5 —SiO 2 glass (P 2 O 5 content: 10%) powder, 0.3 g of Ag, 0.3 g of ethyl cellulose (molecular weight 140000), and 2- (2-butoxyethoxy) acetate Ethyl 7g was mixed and pasted using an automatic mortar kneader to prepare n-type diffusion layer forming composition 5. The pH (25 ° C.) was 5.6.
［実施例６Ａ］
　実施例１Ａにおいて、クエン酸を用いてｐＨ＝３．８に調整したこと以外は実施例１Ａと同様にｎ型拡散層形成組成物６を調製した。 [Example 6A]
In Example 1A, an n-type diffusion layer forming composition 6 was prepared in the same manner as in Example 1A, except that the pH was adjusted to 3.8 using citric acid.
［実施例７Ａ］
　実施例１Ａにおいて、炭酸水素ナトリウムを用いてｐＨ＝９．８に調整したこと以外は実施例１Ａと同様にｎ型拡散層形成組成物７を調製した。 [Example 7A]
In Example 1A, an n-type diffusion layer forming composition 7 was prepared in the same manner as in Example 1A, except that the pH was adjusted to 9.8 using sodium hydrogen carbonate.
[実施例８Ａ]
　実施例１Ａにおいて、バインダーを重量平均分子量が７０００のエチルセルロースに代えたこと以外は、実施例１Ａと同様にｎ型拡散層形成組成物８を調製した。ｐＨ（２５℃）は５．６であった。 [Example 8A]
In Example 1A, an n-type diffusion layer forming composition 8 was prepared in the same manner as in Example 1A, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 7000. The pH (25 ° C.) was 5.6.
[実施例９Ａ]
　実施例１Ａにおいて、バインダーを重量平均分子量が４５００００のエチルセルロースに代えたこと以外は、実施例１Ａと同様にｎ型拡散層形成組成物９を調製した。ｐＨ（２５℃）は５．６であった。 [Example 9A]
In Example 1A, an n-type diffusion layer forming composition 9 was prepared in the same manner as in Example 1A, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 450,000. The pH (25 ° C.) was 5.6.
［比較例１Ａ］
　実施例１Ａにおいて、バインダーを重量平均分子量が４５００のエチルセルロースに代えたこと以外は、実施例１Ａと同様にｎ型拡散層形成組成物Ｃ１を調製した。ｐＨ（２５℃）は５．６であった。 [Comparative Example 1A]
In Example 1A, an n-type diffusion layer forming composition C1 was prepared in the same manner as in Example 1A, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 4500. The pH (25 ° C.) was 5.6.
［比較例２Ａ］
　実施例１Ａにおいて、バインダーを重量平均分子量が７５００００のエチルセルロースに代えたこと以外は、実施例１Ａと同様にｎ型拡散層形成組成物Ｃ２を調製した。ｐＨ（２５℃）は５．６であった。 [Comparative Example 2A]
In Example 1A, an n-type diffusion layer forming composition C2 was prepared in the same manner as in Example 1A, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 750000. The pH (25 ° C.) was 5.6.
［評価］
－分散安定性－
　上記方法により調製したｎ型拡散層形成組成物について、調製してから１時間以内に測定した初期粘度と、２０℃で６時間放置した後に測定した経時粘度とから、経持粘度と初期粘度との差の初期粘度に対する比率（（経時粘度－初期粘度）／初期粘度）として粘度変化率を求めた。尚、粘度は、回転式粘度計を用いて２０℃で測定した。
　併せて目視により、経時後のｎ型拡散層形成組成物の状態を観察した。
　粘度変化および目視観察の結果を、下記評価基準に従って評価した。その結果を表１に示す。 [Evaluation]
-Dispersion stability-
About the n-type diffusion layer forming composition prepared by the above method, the initial viscosity measured within 1 hour after preparation and the time-lapse viscosity measured after standing at 20 ° C. for 6 hours The rate of change in viscosity was determined as the ratio of the difference between the two to the initial viscosity ((viscosity with time−initial viscosity) / initial viscosity). The viscosity was measured at 20 ° C. using a rotary viscometer.
At the same time, the state of the n-type diffusion layer forming composition after aging was visually observed.
The viscosity change and visual observation results were evaluated according to the following evaluation criteria. The results are shown in Table 1.
～評価基準～
　Ａ・・・粘度変化率が０．０５未満で、ガラス粒子のゲル化及び凝集も認められなかった。
　Ｂ・・・粘度変化率が０．０５以上、０．１０未満で、ガラス粒子のゲル化及び凝集も認められなかった。
　Ｃ・・・粘度変化率が０．１０以上、０．１５未満で、ガラス粒子のゲル化及び凝集も認められなかった。
　Ｄ・・・粘度変化率が０．１５未満であったが、ガラス粒子がゲル化または凝集した。
　Ｅ・・・粘度変化率が０．１５以上であり、かつガラス粒子がゲル化または凝集した。 -Evaluation criteria-
A: Viscosity change rate was less than 0.05, and neither gelation nor aggregation of glass particles was observed.
B: Viscosity change rate was 0.05 or more and less than 0.10, and neither gelation nor aggregation of glass particles was observed.
C: Viscosity change rate was 0.10 or more and less than 0.15, and neither gelation nor aggregation of glass particles was observed.
D: Viscosity change rate was less than 0.15, but glass particles were gelled or aggregated.
E: Viscosity change rate was 0.15 or more, and glass particles were gelled or aggregated.
　次に、実施例１Ａ～実施例９Ａで調製したｎ型拡散層形成組成物をスクリーン印刷によって塗布量が７０ｇ／ｍ２（ガラス粉末塗布量として）となるように、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フッ酸に５分間浸漬し、流水洗浄を行い、その後、乾燥を行った。
　尚、比較例１および比較例２で調製したｎ型拡散層形成組成物は分散安定性が低く、スクリーン印刷を行うことができなかった。 Next, the n-type diffusion layer forming composition prepared in Example 1A to Example 9A was applied to the surface of the p-type silicon substrate by screen printing so that the application amount was 70 g / m 2 (as the glass powder application amount). 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 then dried.
The n-type diffusion layer forming compositions prepared in Comparative Example 1 and Comparative Example 2 had low dispersion stability and could not be screen printed.
　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及び裏面のシート抵抗を測定した。その結果を表１に示す。 The sheet resistance on the surface and the sheet resistance on the back surface on which the n-type diffusion layer forming composition was applied were measured. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　本発明のｎ型拡散層形成組成物を用いて、熱拡散処理を行った結果、表面のシート抵抗は１００Ω／□以下であり、Ｐ（りん）が拡散し、ｎ型拡散層が形成されていた。一方、裏面のシート抵抗は１００００００Ω／□以上で測定不能であり、ｎ型拡散層は実質的に形成されていないと判断された。
　また、ガラス粉末と反応して結晶化する金属元素としてＡｇ（銀）が配合されていることで、熱拡散処理後に形成されたガラスの除去性に優れていた。また、基板の反りは発生していなかった。 As a result of performing thermal diffusion treatment using the n-type diffusion layer forming composition of the present invention, the sheet resistance of the surface is 100Ω / □ or less, P (phosphorus) is diffused, and an n-type diffusion layer is formed. It was. On the other hand, the sheet resistance on the back surface was 1000000 Ω / □ or more, which was not measurable, and it was determined that the n-type diffusion layer was not substantially formed.
Moreover, it was excellent in the removability of the glass formed after the thermal diffusion process by mix | blending Ag (silver) as a metal element which reacts with glass powder and crystallizes. Further, the substrate was not warped.
［実施例１Ｂ］
　Ｂ２Ｏ３－ＳｉＯ２系ガラス（Ｂ２Ｏ３：１０％）粉末２０ｇとエチルセルロース（重量平均分子量１４００００）３ｇ、酢酸２－（２－ブトキシエトキシ）エチル７７ｇとを、自動乳鉢混練装置を用いて混合してペースト化し、ｐ型拡散層形成組成物１を調製した。
　得られたｐ型拡散層形成組成物のｐＨを２５℃で、ｐＨ測定装置を用いて測定したところ、ｐＨ（２５℃）は５．６であった。 [Example 1B]
Using an automatic mortar kneading apparatus, 20 g of B 2 O 3 —SiO 2 glass (B 2 O 3 : 10%) powder, 3 g of ethyl cellulose (weight average molecular weight 140000), and 77 g of 2- (2-butoxyethoxy) ethyl acetate are used. And mixed to paste to prepare p-type diffusion layer forming composition 1.
When the pH of the obtained p-type diffusion layer forming composition was measured at 25 ° C. using a pH measuring device, the pH (25 ° C.) was 5.6.
[実施例２Ｂ]
　実施例１Ｂにおいて、バインダーを重量平均分子量３０００００のエチルセルロースに代えたこと以外は、実施例１Ｂと同様にｐ型拡散層形成組成物２を調製した。ｐＨ（２５℃）は５．６であった。 [Example 2B]
In Example 1B, p-type diffusion layer forming composition 2 was prepared in the same manner as in Example 1B, except that the binder was changed to ethyl cellulose having a weight average molecular weight of 300,000. The pH (25 ° C.) was 5.6.
［実施例３Ｂ］
　実施例１Ｂにおいて、ガラス粉末をＢ２Ｏ３－ＺｎＯ系（Ｂ２Ｏ３含有量：６０％）に代えたこと以外は、実施例１Ｂと同様にｐ型拡散層形成組成物３を調製した。ｐＨ（２５℃）は５．６であった。 [Example 3B]
A p-type diffusion layer forming composition 3 was prepared in the same manner as in Example 1B, except that the glass powder was replaced with a B 2 O 3 —ZnO-based (B 2 O 3 content: 60%) in Example 1B. . The pH (25 ° C.) was 5.6.
［実施例４Ｂ］
　実施例１Ｂにおいて、バインダーをポリビニルアルコール（分子量２５００００）に代えたこと以外は、実施例１Ｂと同様にｐ型拡散層形成組成物４を調製した。ｐＨ（２５℃）は５．６であった。 [Example 4B]
In Example 1B, a p-type diffusion layer forming composition 4 was prepared in the same manner as in Example 1B, except that the binder was changed to polyvinyl alcohol (molecular weight 250,000). The pH (25 ° C.) was 5.6.
［実施例５Ｂ］
　実施例１Ｂにおいて、クエン酸を用いてｐＨ＝３．８に調整したこと以外は実施例１Ｂと同様にｐ型拡散層形成組成物５を調製した。 [Example 5B]
In Example 1B, p-type diffusion layer forming composition 5 was prepared in the same manner as in Example 1B, except that the pH was adjusted to 3.8 using citric acid.
［実施例６Ｂ］
　実施例１Ｂにおいて、炭酸水素ナトリウムを用いてｐＨ＝１０．６に調整したこと以外は実施例１Ｂと同様にｐ型拡散層形成組成物６を調製した。 [Example 6B]
In Example 1B, p-type diffusion layer forming composition 6 was prepared in the same manner as in Example 1B, except that the pH was adjusted to 10.6 using sodium hydrogen carbonate.
[実施例７Ｂ]
　実施例１Ｂにおいて、バインダーを重量平均分子量８０００のエチルセルロースに代えたこと以外は、実施例１Ｂと同様にｐ型拡散層形成組成物７を調製した。ｐＨ（２５℃）は５．６であった。 [Example 7B]
A p-type diffusion layer forming composition 7 was prepared in the same manner as in Example 1B, except that in Example 1B, the binder was changed to ethyl cellulose having a weight average molecular weight of 8000. The pH (25 ° C.) was 5.6.
[実施例８Ｂ]
　実施例１Ｂにおいて、バインダーを重量平均分子量４５００００のエチルセルロースに代えたこと以外は、実施例１Ｂと同様にｐ型拡散層形成組成物８を調製した。ｐＨ（２５℃）は５．６であった。 [Example 8B]
A p-type diffusion layer forming composition 8 was prepared in the same manner as in Example 1B, except that in Example 1B, the binder was replaced with ethyl cellulose having a weight average molecular weight of 450,000. The pH (25 ° C.) was 5.6.
［比較例１Ｂ］
　実施例１Ｂにおいて、バインダーを重量平均分子量４５００のエチルセルロースに代えたこと以外は、実施例１Ｂと同様にｐ型拡散層形成組成物Ｃ１を調製した。ｐＨ（２５℃）は５．６であった。 [Comparative Example 1B]
A p-type diffusion layer forming composition C1 was prepared in the same manner as in Example 1B, except that in Example 1B, the binder was replaced with ethyl cellulose having a weight average molecular weight of 4500. The pH (25 ° C.) was 5.6.
［比較例２Ｂ］
　実施例１Ｂにおいて、バインダーを重量平均分子量７５００００のエチルセルロースに代えたこと以外は、実施例１Ｂと同様にｐ型拡散層形成組成物Ｃ２を調製した。ｐＨ（２５℃）は５．６であった。 [Comparative Example 2B]
A p-type diffusion layer forming composition C2 was prepared in the same manner as in Example 1B, except that in Example 1B, the binder was changed to ethyl cellulose having a weight average molecular weight of 750,000. The pH (25 ° C.) was 5.6.
　上記方法により調製したｐ型拡散層形成組成物について、上記ｎ型拡散層形成組成物の場合と同様にして分散安定性を評価した。その結果を表２に示す。 The dispersion stability of the p-type diffusion layer forming composition prepared by the above method was evaluated in the same manner as in the case of the n-type diffusion layer forming composition. The results are shown in Table 2.
　次に、実施例１Ｂ～実施例８Ｂで調製したｐ型拡散層形成組成物をスクリーン印刷によって塗布量が７０ｇ／ｍ２となるように、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フッ酸に５分間浸漬し、流水洗浄を行い、その後、乾燥を行った。 Next, the p-type diffusion layer forming composition prepared in Example 1B to Example 8B was applied to the surface of the p-type silicon substrate by screen printing so that the application amount was 70 g / m 2, and a hot plate at 150 ° C. Dry for 5 minutes above. 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 then dried.
　ｐ型拡散層形成組成物を塗布した側の表面のシート抵抗及び裏面のシート抵抗を測定した。その結果を表２に示す。 The sheet resistance of the surface on the side where the p-type diffusion layer forming composition was applied and the sheet resistance of the back surface were measured. The results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
 
Figure JPOXMLDOC01-appb-T000002
 
　本発明のｐ型拡散層形成組成物を塗布し、熱拡散処理を行った結果、表面のシート抵抗は１００Ω／□以下であり、Ｂ（ほう素）が拡散しｐ型拡散層が形成されていた。裏面のシート抵抗は１００００００Ω／□以上で測定不能であり、ｐ型拡散層は形成されていなかった。また、基板の反りは発生していなかった。 As a result of applying the p-type diffusion layer forming composition of the present invention and performing thermal diffusion treatment, the surface sheet resistance is 100Ω / □ or less, and B (boron) is diffused to form a p-type diffusion layer. It was. The sheet resistance on the back surface was 1000000 Ω / □ or more and could not be measured, and no p-type diffusion layer was formed. Further, the substrate was not warped.

Claims (17)

  1. 　ドナー元素又はアクセプタ元素を含むガラス粉末と、重量平均分子量が５０００以上５０００００以下であるバインダーと、溶剤とを含有する不純物拡散層形成組成物。 An impurity diffusion layer forming composition containing a glass powder containing a donor element or an acceptor element, a binder having a weight average molecular weight of 5,000 to 500,000, and a solvent.
  2. 　ドナー元素を含むガラス粉末と、重量平均分子量が５０００以上５０００００以下であるバインダーと、溶剤とを含有するｎ型拡散層形成組成物。 An n-type diffusion layer forming composition containing glass powder containing a donor element, a binder having a weight average molecular weight of 5,000 to 500,000 and a solvent.
  3. 　前記ガラス粉末は、ガラス成分物質とドナー元素含有物質とを含み、前記ドナー元素含有物質の含有比率が該ガラス粉末に対して１質量％以上７５質量％以下である請求項２に記載のｎ型拡散層形成組成物 The n-type according to claim 2, wherein the glass powder includes a glass component substance and a donor element-containing substance, and a content ratio of the donor element-containing substance is 1% by mass or more and 75% by mass or less with respect to the glass powder. Diffusion layer forming composition
  4. 　ｐＨ（２５℃）が２～１３の範囲である請求項２又は請求項３に記載のｎ型拡散層形成組成物。 The n-type diffusion layer forming composition according to claim 2 or 3, wherein the pH (25 ° C) is in the range of 2 to 13.
  5. 　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２～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。 The n-type diffusion layer forming composition according to any one of claims 2 to 4, wherein the donor element is at least one selected from P (phosphorus) and Sb (antimony).
  6. 　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、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２～請求項５のいずれか１項に記載の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. 6. At least one glass component material selected from O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , and MoO 3 is contained. The n-type diffusion layer forming composition according to any one of the above.
  7. 　更に、Ａｇ、Ｓｉ、Ｃｕ、Ｆｅ、Ｚｎ及びＭｎから選択される少なくとも１種の金属を含む請求項２～請求項６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 2 to 6, further comprising at least one metal selected from Ag, Si, Cu, Fe, Zn, and Mn.
  8. 　前記金属がＡｇ（銀）である請求項７に記載のｎ型拡散層形成組成物。 The n-type diffusion layer forming composition according to claim 7, wherein the metal is Ag (silver).
  9. 　半導体基板上に、請求項２～請求項８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: applying a composition for forming an n-type diffusion layer according to any one of claims 2 to 8 on a semiconductor substrate; and applying a thermal diffusion treatment. .
  10. 　半導体基板上に、請求項２～請求項８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 2 to 8 on a semiconductor substrate, a step of forming a n-type diffusion layer by performing a thermal diffusion treatment, and formation Forming an electrode on the formed n-type diffusion layer, and a method for manufacturing a solar cell element.
  11. 　アクセプタ元素を含むガラス粉末と、重量平均分子量が５０００以上５０００００以下であるバインダーと、溶剤とを含有するｐ型拡散層形成組成物。 A p-type diffusion layer forming composition containing glass powder containing an acceptor element, a binder having a weight average molecular weight of 5,000 to 500,000, and a solvent.
  12. 　前記ガラス粉末は、ガラス成分物質とアクセプタ元素含有物質とを含み、前記アクセプタ元素含有物質の該ガラス粉末における含有比率が１質量％以上９０質量％以下である請求項１１に記載のｐ型拡散層形成組成物。 The p-type diffusion layer according to claim 11, wherein the glass powder includes a glass component substance and an acceptor element-containing substance, and a content ratio of the acceptor element-containing substance in the glass powder is 1% by mass or more and 90% by mass or less. Forming composition.
  13. 　ｐＨ（２５℃）が２～１３の範囲である請求項１１又は請求項１２に記載のｐ型拡散層形成組成物。 The p-type diffusion layer forming composition according to claim 11 or 12, wherein the pH (25 ° C) is in the range of 2 to 13.
  14. 　前記アクセプタ元素が、Ｂ（ほう素）、Ａｌ（アルミニウム）及びＧａ（ガリウム）から選択される少なくとも１種である請求項１１～請求項１３のいずれか１項に記載のｐ型拡散層形成組成物。 The p-type diffusion layer forming composition according to any one of claims 11 to 13, wherein the acceptor element is at least one selected from B (boron), Al (aluminum), and Ga (gallium). object.
  15. 　前記アクセプタ元素を含むガラス粉末が、Ｂ２Ｏ３、Ａｌ２Ｏ３及びＧａ２Ｏ３から選択される少なくとも１種のアクセプタ元素含有物質と、ＳｉＯ２、Ｋ２Ｏ、Ｎａ２Ｏ、Ｌｉ２Ｏ、ＢａＯ、ＳｒＯ、ＣａＯ、ＭｇＯ、ＢｅＯ、ＺｎＯ、ＰｂＯ、ＣｄＯ、Ｔｌ２Ｏ、ＳｎＯ、ＺｒＯ２、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１１～請求項１４のいずれか１項に記載のｐ型拡散層形成組成物。 The glass powder containing the acceptor element is at least one acceptor element-containing material selected from B 2 O 3 , Al 2 O 3 and Ga 2 O 3 , and SiO 2 , K 2 O, Na 2 O, Li 2. And at least one glass component substance selected from O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, Tl 2 O, SnO, ZrO 2 , and MoO 3. The p-type diffusion layer forming composition according to claim 14.
  16. 　半導体基板上に、請求項１１～請求項１５のいずれか１項に記載のｐ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ｐ型拡散層の製造方法。 A method for producing a p-type diffusion layer, comprising: applying a p-type diffusion layer forming composition according to any one of claims 11 to 15 on a semiconductor substrate; and applying a thermal diffusion treatment. .
  17. 　半導体基板上に、請求項１１～請求項１５のいずれか１項に記載のｐ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ｐ型拡散層を形成する工程と、形成されたｐ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 p-type diffusion layer forming composition according to any one of claims 11 to 15 on a semiconductor substrate, a step of applying a thermal diffusion treatment to form a p-type diffusion layer, and formation Forming an electrode on the formed p-type diffusion layer, and a method for manufacturing a solar cell element.
PCT/JP2011/065386 2010-07-07 2011-07-05 Composition for forming impurity diffusion layer, process for producing impurity diffusion layer, and process for producing solar cell element WO2012005253A1 (en)

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