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WO2018012547A1 - Procédé de fabrication d'un substrat semi-conducteur avec une couche de diffusion de type p, substrat semi-conducteur avec couche de diffusion de type p, procédé de production d'un élément de cellule solaire et élément de cellule solaire - Google Patents

Procédé de fabrication d'un substrat semi-conducteur avec une couche de diffusion de type p, substrat semi-conducteur avec couche de diffusion de type p, procédé de production d'un élément de cellule solaire et élément de cellule solaire Download PDF

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Publication number
WO2018012547A1
WO2018012547A1 PCT/JP2017/025439 JP2017025439W WO2018012547A1 WO 2018012547 A1 WO2018012547 A1 WO 2018012547A1 JP 2017025439 W JP2017025439 W JP 2017025439W WO 2018012547 A1 WO2018012547 A1 WO 2018012547A1
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Prior art keywords
type diffusion
diffusion layer
boron
mass
semiconductor substrate
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English (en)
Japanese (ja)
Inventor
鉄也 佐藤
野尻　剛
田中　直敬
岩室　光則
成宜 清水
真年 森下
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Resonac Corp
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Hitachi Chemical Co Ltd
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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 potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
    • H01L21/225—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities using diffusion into or out of a solid from or into a solid phase, e.g. a doped oxide layer
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F10/00—Individual photovoltaic cells, e.g. solar cells
    • H10F10/10—Individual photovoltaic cells, e.g. solar cells having potential barriers
    • H10F10/14—Photovoltaic cells having only PN homojunction potential barriers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F71/00—Manufacture or treatment of devices covered by this subclass
    • 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 content of boron oxide in the boron-containing glass compound can be appropriately changed according to the purpose.
  • the content of boron oxide in the boron-containing glass compound is preferably 0.1% by mass to 60% by mass, and more preferably 0.5% by mass to 50% by mass. More preferably, the content is 1% by mass to 40% by mass.
  • the absolute amount of boron to be diffused into the semiconductor substrate tends to be ensured.
  • hydrofluoric acid performed after diffusion There is a tendency that the amount of etching residue generated in an etching process using an etching solution such as can be reduced.
  • the softening temperature of the boron-containing glass particles is preferably 200 ° C. to 1000 ° C. from the viewpoints of diffusibility of components of the p-type diffusion layer forming composition during heat treatment (thermal diffusion), suppression of dripping, etc. More preferably, the shape of the boron-containing glass particles is 300 ° C. to 900 ° C. Examples of the shape of the boron-containing glass particles include a spherical shape, a substantially spherical shape, a flat shape, a block shape, a plate shape, and a scale shape.
  • the boron-containing glass particles are preferably spherical, substantially spherical, flat, or plate-shaped in terms of imparting to a semiconductor substrate and improving diffusion uniformity when a p-type diffusion layer forming composition is used.
  • the desired form of the boron nitride crystal form can be obtained in any of the hexagonal, cubic, and rhombohedral crystal states. . From the viewpoint of easily controlling the particle size, hexagonal crystals are preferable.
  • R 7 to R 9 in the general formula (I) are each independently an organic group having 1 to 10 carbon atoms or a hydrogen atom, and at least one of R 7 to R 9 has 1 to 10 carbon atoms. Organic group.
  • examples of the hetero atom include a nitrogen atom, an oxygen atom, and a sulfur atom.
  • the organic group having a hetero atom represented by R 7 to R 9 has 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and 1 to 3 carbon atoms. Is more preferable.
  • Specific examples of the organic group having a hetero atom represented by R 7 to R 9 include a dimethylamino group, a diethylamino group, a diphenylamino group, a methyl sulfoxide group, an ethyl sulfoxide group, and a phenyl sulfoxide group. .
  • the organic group having an unsaturated bond represented by R 7 to R 9 has 2 to 10 carbon atoms, preferably 2 to 6 carbon atoms, and more preferably 2 to 4 carbon atoms. preferable.
  • Specific examples of the organic group having an unsaturated bond represented by R 7 to R 9 include an ethylenyl group, an ethynyl group, a propenyl group, a propynyl group, a butenyl group, a butynyl group, and a phenyl group.
  • boric acid ester used for the sol-gel reaction it is preferable to use at least one selected from the group consisting of trimethyl borate, triethyl borate, tripropyl borate, and tributyl borate.
  • the p-type diffusion layer forming composition may further contain a dispersion medium.
  • a dispersion medium is for adjusting a viscosity in a composition, and can mention a solvent and water.
  • the content of the dispersion medium in the p-type diffusion layer forming composition is determined in consideration of the imparting property and the viscosity.
  • the dispersion medium is not particularly limited.
  • acetone methyl ethyl ketone, methyl-n-propyl ketone, methyl isopropyl ketone, methyl-n-butyl ketone, methyl isobutyl ketone, methyl-n-pentyl ketone, methyl-n-hexyl ketone, Ketone solvents such as diethyl ketone, dipropyl ketone, diisobutyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone; diethyl ether, methyl ethyl ether, methyl-n-propyl Ether, diisopropyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethylene
  • Ester solvents acetonitrile, N-methylpyrrolidinone, N-ethylpyrrolidinone, N-propylpyrrolidinone, N-butyl Aprotic polar solvents such as pyrrolidinone, N-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide; methanol, ethanol, n-propanol, isopropanol, n-butanol, Isobutanol, sec-butanol, t-butanol, n-pentanol, isopentanol, 2-methylbutanol, sec-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol,
  • Binder From the viewpoint of applying the p-type diffusion layer forming composition on the semiconductor substrate and preventing scattering of the boron-containing compound in a dried state, if desired, or adjusting the viscosity of the p-type diffusion layer forming composition, It may further contain a binder.
  • the binder is not particularly limited.
  • polyvinyl alcohol polyacrylamide compound, polyvinyl amide compound, polyvinyl pyrrolidone, polyethylene oxide compound, polysulfonic acid, acrylamide alkyl sulfonic acid, cellulose ether compound, cellulose derivative (carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose) Etc.), gelatin, starch and starch derivatives, sodium alginate compounds, xanthan, guar gum and guar gum derivatives, scleroglucan and scleroglucan derivatives, tragacanth and tragacanth derivatives, dextrin and dextrin derivatives, acrylic resin ((meth) acrylic acid resin, (Meth) acrylic acid esters such as dimethylaminoethyl (meth) acrylate resin Butter, and the like), butadiene resins, styrene resins and copolymers thereof, siloxane resins, and metal alkoxides.
  • acrylic resin (
  • (meth) acrylic resin means at least one selected from the group consisting of “acrylic resin” and “methacrylic resin”
  • alkyl (meth) acrylate resin means “alkyl It means at least one selected from the group consisting of “acrylate resin” and “alkyl methacrylate resin”
  • (meth) acrylic ester resin is from the group consisting of “acrylic ester resin” and “methacrylic ester resin”. It means at least one selected.
  • the molecular weight of the binder is not particularly limited, and it is desirable to adjust appropriately in view of the desired viscosity of the p-type diffusion layer forming composition.
  • the content rate of the binder in a p-type diffused layer formation composition It is preferable that it is 15 mass% or less of the whole composition, It is more preferable that it is 12 mass% or less, It is 10 mass% or less. More preferably.
  • the p-type diffusion layer forming composition may further contain a high viscosity solvent.
  • the high-viscosity solvent is not particularly limited, and is isobornylcyclohexanol, isobornylphenol, 1-isopropyl-4-methyl-bicyclo [2.2.2] oct-5-ene-2,3-dicarboxylic acid anhydride And at least one selected from the group consisting of p-mentenylphenol, more preferably at least one selected from the group consisting of isobornylcyclohexanol and isobornylphenol. These compounds decompose or volatilize at a low temperature (for example, 400 ° C.
  • binders such as ethyl cellulose.
  • a p-type diffusion layer forming composition when applied to a semiconductor substrate by screen printing or the like, it tends to contain a large amount of a binder such as ethyl cellulose in order to increase the viscosity of the p-type diffusion layer forming composition. .
  • the binder that cannot be removed becomes a resistor, which may affect the power generation characteristics of the solar cell element.
  • the amount of the binder tends to be reduced to such an extent that residual does not become a problem.
  • the content of the high-viscosity solvent in the p-type diffusion layer forming composition can be appropriately changed according to the purpose.
  • the content of the high-viscosity solvent in the p-type diffusion layer forming composition is preferably 0.01% by mass to 90% by mass, and 1% by mass More preferably, it is ⁇ 80% by mass, and further preferably 1% by mass to 50% by mass.
  • the ratio of the compound containing boron and the high viscosity solvent there is no particular limitation on the ratio of the compound containing boron and the high viscosity solvent.
  • the p-type diffusion layer forming composition further contains a high-viscosity solvent
  • the p-type diffusion layer forming composition contains 1% by mass to 50% by mass of the boron-containing compound and 1% by mass to 99% by mass of the high-viscosity solvent. It is preferable to contain 5% by mass to 40% by mass of a compound containing boron and 5% by mass to 95% by mass of a high viscosity solvent.
  • the content of the inorganic filler in the p-type diffusion layer forming composition is preferably 0.01% by mass to 40% by mass, more preferably 0.1% by mass to 20% by mass, and 0.2% More preferably, the content is from 5% by mass to 5% by mass.
  • the alkoxy group constituting the alkoxysilane is preferably a linear or branched alkyloxy group, more preferably a linear or branched alkyloxy group having 1 to 24 carbon atoms. Further, a linear or branched alkyloxy group having 1 to 10 carbon atoms is more preferable, and a linear or branched alkyloxy group having 1 to 4 carbon atoms is particularly preferable.
  • T-octyloxy group decyloxy group, dodecyloxy group, tetradecyloxy group, 2-hexyldecyloxy group, hexadecyloxy group, octadecyloxy group, cyclohexylmethyloxy group, and octylcyclohexyloxy group.
  • the alkoxysilane it is preferable to use at least one selected from the group consisting of tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane.
  • the content of the alkoxysilane in the p-type diffusion layer forming composition can be, for example, 0.01% by mass to 50% by mass.
  • the content is preferably from 05% by mass to 40% by mass, and more preferably from 0.1% by mass to 30% by mass.
  • the p-type diffusion layer forming composition may further contain a silane coupling agent.
  • a silane coupling agent has a silicon atom in one molecule, and has an organic functional group and an alkoxy group.
  • a silane coupling agent For example, the compound represented by the following general formula (II) can be mentioned.
  • n represents an integer of 1 to 3.
  • X represents an alkoxy group.
  • Y represents an organic functional group.
  • R 1 represents a single bond, an alkylene group having 1 to 10 carbon atoms, or a divalent linking group having 2 to 5 main chain atoms and a nitrogen atom or oxygen atom in the main chain.
  • R 2 represents an alkyl group having 1 to 5 carbon atoms.
  • Y represents an organic functional group. Specifically, for example, vinyl group, mercapto group, epoxy group, amino group, styryl group, vinylphenyl group, isocyanurate group, isocyanate group, acrylic group, methacryl group, glycidoxy group, ureido group, sulfide group, carboxyl group , Acryloxy group, methacryloxy group, alkylene glycol group, amino alcohol group, and quaternary ammonium group.
  • Y is preferably a vinyl group, an amino group, an epoxy group, an acryloxy group, or a methacryloxy group, and more preferably an acryloxy group.
  • R 1 is a single bond, an alkylene group having 1 to 10 carbon atoms, or a divalent linking group having 2 to 5 atoms in the main chain and having a nitrogen atom or an oxygen atom in the main chain.
  • the alkylene group represented by R 1 is preferably an ethylene group or a propylene group.
  • the divalent linking group having a nitrogen atom in the main chain is preferably an amino group or the like.
  • the divalent linking group having an oxygen atom in the main chain is preferably an ether group, an ester group, an alkyl carboxylic acid group or the like.
  • R 2 represents an alkyl group having 1 to 5 carbon atoms. Of these, a methyl group or an ethyl group is preferable, and a methyl group is more preferable.
  • n 1, the plurality of R 2 may be different or the same.
  • TG / DTA Thermo Gravimetric Analyzer / Differential Thermal Analysis, differential thermal-thermogravimetric simultaneous measurement method) thermal analysis, NMR (Nuclear Magnetic Resonance (Nuclear Magnetic Resonance Method), HPLC (High Performance Liquid Chromatography, High Performance Liquid Chromatography Method), GPC (Gel Permeation Chromatography, Gel Permeation Chromatography Method), GC-MS (Gastro Chroma Chromatography) ), IR (Infrared) Pectroscopy, infrared spectroscopy) can be confirmed using MALDI-MS (Matrix Assisted Laser Desorption / Ionization, matrix-assisted laser desorption ionization) and the like.
  • MALDI-MS Microdesorption Assisted Laser Desorption / Ionization, matrix-assisted laser desorption ionization
  • the total amount of lifetime killer elements is preferably 1000 ppm or less, more preferably 500 ppm or less, still more preferably 100 ppm or less, and particularly preferably 50 ppm or less. .
  • the total amount of lifetime killer elements is 1000 ppm or less, the lifetime of the semiconductor substrate tends to be improved.
  • the lifetime killer element examples include Fe, Cu, Ni, Mn, Cr, W, and Au.
  • the amount of these elements can be analyzed with an ICP (Inductively Coupled Plasma) mass spectrometer, ICP emission spectrometer or atomic absorption spectrometer.
  • the lifetime in the semiconductor substrate can be measured by a microwave photoconductive decay method ( ⁇ -PCD method). Since the above elements have a high diffusion rate in the semiconductor substrate, they reach everywhere in the bulk of the semiconductor substrate and function as recombination centers.
  • the method for producing the p-type diffusion layer forming composition is not particularly limited. For example, it can be obtained by mixing a compound containing boron, a high-viscosity solvent, or the like using a blender, a mixer, a mortar, a rotor, or the like. Moreover, when mixing, you may heat as needed. When heating at the time of mixing, the heating temperature can be, for example, 30 ° C. to 100 ° C.
  • a p-type diffusion layer forming composition containing a compound containing boron is applied to the semiconductor substrate, and the mass of the compound containing boron per unit area is added.
  • Forming a p-type diffusion layer forming composition layer having a thickness of 0.001 mg / cm 2 to 0.1 mg / cm 2 (p-type diffusion layer forming composition layer forming step), and a p-type diffusion layer forming composition layer
  • a step of forming a p-type diffusion layer on the semiconductor substrate by heat-treating the semiconductor substrate to which p is applied (p-type diffusion layer forming step).
  • the manufacturing method of the semiconductor substrate with a p-type diffusion layer of the present embodiment may further include other steps as necessary.
  • the p-type diffusion layer forming composition layer forming step In the p-type diffusion layer forming composition layer forming step, the p-type diffusion layer forming composition is applied to at least a part of the region on the semiconductor substrate, and the mass of the compound containing boron per unit area is 0.001 mg / A p-type diffusion layer forming composition layer having a thickness of cm 2 to 0.1 mg / cm 2 is formed.
  • mass of the compound containing boron 0.1 mg / cm 2 or less it is possible to suppress the formation of a thick BRL and hardly generate a residue. Further, by setting the mass of the compound containing boron to 0.1 mg / cm 2 or less, it is possible to prevent boron from scattering to unnecessary regions of the semiconductor substrate.
  • the mass (applied amount) of boron per unit area of the semiconductor substrate in the p-type diffusion layer forming composition layer is preferably 0.05 ⁇ g / cm 2 or more and less than 10 ⁇ g / cm 2 , and preferably 0.07 ⁇ g / cm 2. More preferably, it is cm 2 to 5 ⁇ g / cm 2 , and still more preferably 0.3 ⁇ g / cm 2 to 1 ⁇ g / cm 2 .
  • the mass of boron in the p-type diffusion layer forming composition layer is 0.05 ⁇ g / cm 2 or more, a sufficient amount of boron can be diffused into the semiconductor substrate.
  • the mass of boron is less than 10 ⁇ g / cm 2 , the amount of boron scattered to an unnecessary region can be reduced, and outdiffusion can be suppressed.
  • the semiconductor substrate is not particularly limited, and a known semiconductor substrate used for solar cell elements can be applied.
  • silicon substrate, gallium phosphide substrate, gallium nitride substrate, diamond substrate, aluminum nitride substrate, indium nitride substrate, gallium arsenide substrate, germanium substrate, zinc selenide substrate, zinc telluride substrate, cadmium telluride substrate, cadmium sulfide Examples include substrates, indium phosphide substrates, silicon carbide, silicon germanium substrates, and copper indium selenium substrates.
  • the semiconductor substrate may be an n-type semiconductor substrate or a p-type semiconductor substrate.
  • the semiconductor substrate is preferably pretreated before applying (coating) the p-type diffusion layer forming composition.
  • pretreatment include the following steps. In the following, an example in which an n-type semiconductor substrate is used will be described, but a p-type semiconductor substrate may be used. The following embodiments are merely examples, and do not limit the present invention.
  • an alkaline solution may be applied to the n-type semiconductor substrate to remove the damaged layer, and a texture structure may be obtained by etching. Specifically, for example, a damaged layer on the surface of the n-type semiconductor substrate generated when slicing from an ingot is removed with a 20% by mass aqueous sodium hydroxide solution.
  • etching is performed with a mixed solution of 1% by mass sodium hydroxide and 10% by mass isopropyl alcohol to form a texture structure.
  • the p-type diffusion layer forming composition is applied (applied) to at least a part of the region on the semiconductor substrate pretreated in this way.
  • a p-type diffusion layer forming composition is applied on the n-type diffusion layer on the back surface (that is, the surface opposite to the light receiving surface).
  • a p-type diffusion layer forming composition is applied to the back surface.
  • the method for applying the p-type diffusion layer forming composition is not particularly limited, and examples thereof include a printing method, a spin coating method, a brush coating method, a spray coating method, a doctor blade method, a roll coating method, and an ink jet method.
  • a printing method such as screen printing is preferable from the viewpoints of pattern formability, impartability, and ease of adjusting the mass per unit area of the p-type diffusion layer forming composition.
  • the application amount of the p-type diffusion layer forming composition can be calculated from the mass change of the semiconductor substrate before and after applying the p-type diffusion layer forming composition. Specifically, from the mass change of the semiconductor substrate before and after applying the p-type diffusion layer forming composition, the mass of the p-type diffusion forming composition (p-type diffusion layer forming composition layer) applied on the semiconductor substrate is calculated. Calculate and measure the total area of the p-type diffusion layer forming composition layer. Based on the mass and total area of these p-type diffusion layer forming composition layers, the mass (applied amount) of the p-type diffusion layer forming composition per unit area can be calculated. In the present disclosure, the mass of the semiconductor substrate after applying the p-type diffusion layer forming composition represents the mass measured before the drying step described later.
  • drying step for volatilizing the dispersion medium and the like after applying (applying) the p-type diffusion layer forming composition to the semiconductor substrate and before the heat treatment step described later. May be necessary.
  • 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. This drying condition can be appropriately adjusted depending on the type and amount of the dispersion medium or the like of the p-type diffusion layer forming composition.
  • the semiconductor substrate provided with the p-type diffusion layer forming composition layer is heat-treated to form a p-type diffusion layer on the semiconductor substrate.
  • boron contained in the p-type diffusion layer forming composition layer diffuses into the semiconductor substrate, and a p-type diffusion layer, a p + -type diffusion layer, and the like are formed.
  • the heat treatment (thermal diffusion treatment) for diffusing boron is preferably performed at 600 ° C. to 1200 ° C., more preferably 800 ° C. to 1050 ° C., and further preferably 850 ° C. to 1000 ° C.
  • the treatment time is preferably 5 to 60 minutes.
  • a known continuous furnace, batch furnace, or the like can be applied to the heat treatment.
  • a specific example of the p-type diffusion layer forming step when using a silicon substrate will be described.
  • An atmosphere in which BRL (when a silicon substrate is used as a semiconductor substrate is referred to as boron silicide) is preferably formed.
  • the compound containing boron is a glass compound
  • the glass compound is softened by heat treatment, and the surface of the silicon substrate to which the p-type diffusion layer forming composition is applied is covered with the glass layer.
  • a boron silicide layer is easily formed. After the heat treatment product of the p-type diffusion layer forming composition coats the surface of the silicon substrate at the application portion, the ratio of the oxidizing gas such as oxygen may be increased.
  • the compound containing boron is a glass compound
  • heat treatment is performed in an inert gas atmosphere such as nitrogen alone until the glass compound softens at the softening point and covers the surface of the silicon substrate at the application portion. Is preferred.
  • an inert gas atmosphere such as nitrogen alone
  • the boron silicide layer getters, for example, impurity metals such as heavy metals (for example, iron and nickel) contained in the silicon substrate and the furnace tube. For this reason, the number of recombination centers in the silicon substrate is reduced, and the lifetime of the silicon substrate tends to be extended.
  • impurity metals such as heavy metals (for example, iron and nickel) contained in the silicon substrate and the furnace tube.
  • the gas composition of the atmosphere in the heat treatment after the boron silicide layer is formed is not particularly limited to components other than oxygen.
  • components other than oxygen For example, nitrogen, argon, neon, xenon, krypton, helium, carbon dioxide, hydrogen, air, or the like is used. be able to.
  • a gas composition mainly containing oxygen and nitrogen is preferable.
  • air is used as a gas other than oxygen, the oxygen concentration is adjusted in consideration of the amount of oxygen contained in the air.
  • the ratio of oxygen can be confirmed with an oxygen concentration meter installed at the exhaust side outlet of the diffusion furnace used for heat treatment.
  • the oxygen concentration meter is not particularly limited, and for example, a zirconia oxygen concentration meter (for example, NZ-3000 manufactured by Horiba, Ltd.) can be used.
  • Further heat treatment may be performed after the heat treatment or during the heat treatment by changing the oxygen ratio.
  • the boron silicide layer is oxidized by heat treatment in an atmosphere containing oxygen. Thereafter, when a hydrofluoric acid etching step for removing a boron silicate glass layer, which will be described later, is performed, the boron silicide layer can be removed at once.
  • a SiO 2 layer is formed, a mask layer for boron is formed on the silicon substrate, Diffusion to the applying part can be suppressed.
  • the gas composition at this time may contain, for example, 0.1% by volume to 100% by volume of oxygen.
  • the boron silicide layer is usually formed by setting the mass of the compound containing boron per unit area in the p-type diffusion layer forming composition layer to 0.001 mg / cm 2 to 0.1 mg / cm 2. Is not formed thick and tends to be easily oxidized. Therefore, the boron silicide layer tends to be sufficiently removed by the hydrofluoric acid etching process.
  • a boron silicate glass layer (boron glass layer) is formed as a heat-treated product (baked product) of the p-type diffusion layer forming composition on the surface of the p-type diffusion layer, p + -type diffusion layer, etc. formed by heat treatment.
  • a step of treating the silicon substrate with an etchant may be provided after the heat treatment. Thereby, the produced
  • etching liquid For example, aqueous solution, such as hydrogen fluoride, ammonium fluoride, ammonium hydrogen fluoride, and the aqueous solution of sodium hydroxide are mentioned.
  • a known method such as immersing a silicon substrate in an etching solution can be applied.
  • the boron silicide layer is preferably oxidized by dry oxidation, wet oxidation using water vapor, or wet oxidation using an oxidizing chemical solution, and then etched. By removing the boron silicide layer, the passivation effect of the passivation layer to be formed next tends to be further extracted.
  • Dry oxidation using oxygen gas is preferably performed at 400 ° C. to 780 ° C., more preferably 450 ° C. to 750 ° C., and further preferably 500 ° C. to 700 ° C.
  • the boron silicide layer can be effectively oxidized, and thereafter, the boron silicide layer tends to be easily removed by an etching solution. That is, it becomes easy to bring out the passivation effect in the subsequent passivation process.
  • dry oxidation at 780 ° C. or lower, there is a tendency that re-diffusion of impurity metal elements such as Fe gettered into the boron silicide layer into the silicon substrate can be suppressed.
  • Dry oxidation using oxygen gas is preferably performed in an atmosphere having an oxygen content of 20% by volume to 100% by volume, more preferably in an atmosphere of 50% by volume to 100% by volume, and 80% by volume. More preferably, it is carried out in an atmosphere of up to 100% by volume.
  • the oxygen concentration can be confirmed with an oxygen concentration meter installed at the exhaust side outlet of the diffusion furnace used for heat treatment.
  • the oxygen concentration meter is not particularly limited, and for example, a zirconia oxygen concentration meter (for example, NZ-3000 manufactured by Horiba, Ltd.) can be used.
  • the time for performing dry oxidation is not particularly limited as long as boron silicide is oxidized. For example, it is preferably 1 minute to 1 hour, more preferably 2 minutes to 40 minutes, and even more preferably 5 minutes to 30 minutes.
  • the time for performing dry oxidation for 1 minute or longer the thermal uniformity between the silicon substrates can be sufficiently maintained when processing a plurality of silicon substrates at a time, and variations in performance between the silicon substrates can be sufficiently suppressed. .
  • the throughput of silicon substrate processing can be improved.
  • the gas composition other than oxygen gas in the dry oxidation step is not particularly limited, and for example, nitrogen, argon, neon, xenon, krypton, helium, carbon dioxide, hydrogen, air, or the like can be used.
  • At least one chlorine compound selected from the group consisting of hydrochloric acid and dichloroethanol may be added.
  • an oxidizing atmosphere containing hydrochloric acid, dichloroethanol, etc. impurity alkali metal atoms (for example, Na), heavy metal atoms (for example, Fe and Ni), etc. contained in the silicon substrate and chlorine atoms combine to volatilize.
  • An impurity substance can be formed and an impurity metal element present in the silicon substrate or the heat treatment apparatus can be captured. That is, the lifetime of the silicon substrate can be extended by suppressing the diffusion of impurities such as alkali metal and heavy metal into the silicon substrate.
  • the ratio of the chlorine compound in the gas composition can be measured using a gas composition analyzer (for example, an automatic gas measuring instrument manufactured by Kyoto Electronics Industry Co., Ltd.).
  • the content of the chlorine compound is preferably 0.01% by volume to 5% by volume with respect to oxygen, more preferably 0.1% by volume to 4% by volume, and 0.2% by volume to 3% by volume. % Is more preferable.
  • Dry oxidation may be performed in oxygen plasma.
  • the oxygen plasma is made of, for example, argon gas and oxygen gas, and microwave-excited plasma is allowed to act on the surface of the silicon substrate in an atmosphere having an oxygen flow rate ratio of about 1% by volume under a high pressure of 100 Pa or more.
  • Plasma oxidation treatment may be performed.
  • the treatment temperature is preferably 20 ° C to 500 ° C.
  • Specific methods for wet oxidation are preferably an oxidation method using oxygen gas and water vapor, an oxidation method using water vapor, or an oxidation method using oxygen gas and hydrogen gas.
  • a method of bubbling deionized water in a bubbler with a carrier gas and oxidizing with water vapor, a method of flowing deionized water vapor as it is and oxidizing, or water vapor generated by reacting oxygen gas and hydrogen gas is generated. It is preferable that the method is used for oxidation.
  • carrier gas For example, nitrogen, argon, neon, xenon, krypton, helium, carbon dioxide, hydrogen, air, and these combinations can be used.
  • the wet oxidation is preferably performed at 300 ° C. to 780 ° C., more preferably 350 ° C. to 750 ° C., and further preferably 400 ° C. to 700 ° C.
  • the boron silicide layer can be effectively oxidized, and thereafter tends to be easily removed with an etching solution or the like. That is, it becomes easy to bring out the passivation effect in the subsequent passivation process.
  • impurity metal elements such as Fe gettered to the boron silicide layer can be prevented from re-diffusing into the silicon substrate.
  • the moisture content of the gas after bubbling is not particularly limited and is preferably 10 ppm (0.001% by mass) to 30% by mass, more preferably 100 ppm (0.01% by mass) to 20% by mass. More preferably, it is 200 ppm (0.02 mass%) to 10 mass%.
  • the moisture content of the gas is 10 ppm or more
  • the boron silicide layer tends to be efficiently oxidized, and when it is 30% by mass or less, while achieving a sufficient oxidation rate of the boron silicide layer,
  • the moisture content of the carrier gas tends to be easily controlled.
  • the water content is 1% by mass or less, the water content can be controlled by the dew point, and the dew point is preferably -72 ° C to 21 ° C.
  • the amount of moisture in the carrier gas can be measured by introducing a moisture meter, a dew point meter and a hygrometer in-line.
  • moisture IQ moisture meter
  • MI1 GE Sensing & Inspection Technologies, Inc.
  • M Series Probe GE Sensing & Inspection Technologies, Inc.
  • Aurora IR-300 Series manufactured by Horiba, Ltd., and the like can be used.
  • an external combustion apparatus having a hydrogen gas supply line and an oxygen gas supply line is used, and water vapor generated by burning in the external combustion apparatus is introduced into the heat treatment apparatus. Send in. It is preferable to supply the water vapor together with the dry nitrogen gas, the dry oxygen gas, and the carrier gas to the heat treatment section to control the atmosphere.
  • the gas flow rate is preferably controlled by a mass flow controller.
  • a mass flow controller For example, “Digital Mass Flow Controller SEC-Z500X series” or “Digital Mass Flow Controller SEC-N100 series” manufactured by Horiba, Ltd. can be used.
  • the oxidizing chemical solution in the wet oxidation method using an oxidizing chemical solution is not particularly limited as long as the boron silicide layer can be oxidized.
  • nitric acid, ozone-dissolved water, perchloric acid water, sulfuric acid, hydrogen peroxide solution, mixed solution of hydrochloric acid and hydrogen peroxide solution, mixed solution of sulfuric acid and hydrogen peroxide solution, mixed solution of ammonia and hydrogen peroxide solution It is preferably at least one oxidizing chemical solution selected from the group consisting of a mixed solution of sulfuric acid and nitric acid, perchloric acid, and boiling water, and is nitric acid, ozone-dissolved water, hydrogen peroxide solution, hydrochloric acid, and hydrogen peroxide solution.
  • nitric acid When nitric acid is used as the oxidizing chemical, it is preferable to use a 40% by mass to 98% by mass nitric acid aqueous solution, more preferably a 50% by mass to 80% by mass nitric acid aqueous solution, and 60% by mass to 75% by mass nitric acid. More preferably, an aqueous solution is used.
  • a nitric acid aqueous solution having a concentration close to the 68% by mass nitric acid aqueous solution in an azeotropic state the boiling point becomes high, so that treatment at a high temperature becomes possible.
  • an aqueous solution in which 1% by mass to 80% by mass of ozone is dissolved is preferable, and an aqueous solution in which 10% by mass to 70% by mass of ozone is dissolved is more preferable.
  • An aqueous solution in which 30% by mass to 60% by mass of ozone is dissolved is more preferable.
  • hydrogen peroxide When used as the oxidizing chemical, it is preferably a 1% to 60% by weight aqueous hydrogen peroxide solution, more preferably a 10% to 50% by weight aqueous hydrogen peroxide solution. Further, a 20% to 40% by mass aqueous hydrogen peroxide solution is more preferable. By using a 1% by mass to 60% by mass aqueous hydrogen peroxide solution, the boron silicide layer can be effectively oxidized.
  • a mixed solution of hydrochloric acid and hydrogen peroxide solution is used as the oxidizing chemical solution, it is preferably a mixed solution of 1% by mass to 60% by mass hydrochloric acid solution and 1% by mass to 60% by mass hydrogen peroxide solution.
  • a mixed solution of sulfuric acid and hydrogen peroxide solution is used as the oxidizing chemical solution, it is preferably a mixed solution of 1% by mass to 99% by mass sulfuric acid aqueous solution and 1% by mass to 60% by mass hydrogen peroxide solution.
  • a mixed solution of ammonia and hydrogen peroxide solution is used as the oxidizing chemical solution, it is preferably a mixed solution of 1% to 50% by weight aqueous ammonia solution and 1% to 60% by weight hydrogen peroxide solution.
  • a mixed solution of 1% to 50% by weight aqueous ammonia solution and 1% to 60% by weight hydrogen peroxide solution are used as the oxidizing chemical solution.
  • an SC-1 cleaning solution mixed in a 26 mass% aqueous ammonia solution: 30 mass% aqueous hydrogen peroxide solution: H 2 O 1: 1: 5 (volume ratio).
  • a mixed solution of sulfuric acid and nitric acid is used as the oxidizing chemical solution, it is preferably a mixed solution of 1% by mass to 99% by mass sulfuric acid aqueous solution and 1% by mass to 60% by mass nitric acid aqueous solution, for example, 99% by mass.
  • perchloric acid water When perchloric acid water is used as the oxidizing chemical solution, it is preferably 1% by mass to 80% by mass of perchloric acid water, more preferably 10% by mass to 70% by mass of perchloric acid water. 30% by mass to 60% by mass of perchloric acid water is more preferable. By using 1% by mass to 80% by mass of perchloric acid water, the boron silicide layer can be effectively oxidized.
  • sulfuric acid When sulfuric acid is used as the oxidizing chemical solution, it is preferable to use 1% by mass to 99.5% by mass sulfuric acid aqueous solution, more preferably 30% by mass to 99% by mass sulfuric acid aqueous solution, more preferably 50% by mass to It is more preferable to use a 98.5% by mass aqueous sulfuric acid solution.
  • 1% by mass to 99.5% by mass of sulfuric acid aqueous solution the boron silicide layer can be effectively oxidized (or decomposed).
  • the oxidation of the boron silicide layer using the oxidizing chemical solution is preferably performed at 25 ° C. to 300 ° C., more preferably 40 ° C. to 200 ° C., and further preferably 80 ° C. to 180 ° C.
  • the oxidation at 25 ° C. to 300 ° C. since the diffusion rate of iron is low, it is possible to suppress re-diffusion of impurity metal elements such as iron gettered into the boron silicide layer into the silicon substrate. It is in. That is, the content of the impurity metal element in the silicon substrate can be made as low as possible, and the lifetime of carriers generated in the substrate can be extended.
  • the treatment time of the step of oxidizing the boron silicide layer is not particularly limited as long as it is a time during which the boron silicide layer is oxidized.
  • the treatment time is preferably 1 minute to 1 hour, more preferably 2 minutes to 40 minutes, and even more preferably 5 minutes to 30 minutes.
  • the processing time is 1 minute or longer, the thermal uniformity between silicon substrates can be sufficiently maintained when processing a plurality of wafers at a time, and variations in performance between silicon substrates tend to be sufficiently suppressed. Further, by setting the processing time to 1 hour or less, the throughput of the silicon substrate processing tends to be improved.
  • the boron silicide oxide layer is removed by a known method such as immersing the silicon substrate in an etching solution.
  • the etchant include aqueous solutions of hydrogen fluoride, ammonium fluoride, ammonium hydrogen fluoride, and the like, and aqueous solutions of sodium hydroxide.
  • a p-type diffusion layer forming composition containing a compound containing boron is applied on a semiconductor substrate, and the mass of the compound containing boron per unit area is 0.001 mg / cm 2 to A step of forming a p-type diffusion layer forming composition of 0.1 mg / cm 2 (p-type diffusion layer forming composition layer forming step), and a thermal diffusion treatment on the semiconductor substrate provided with the p-type diffusion layer forming composition And forming a p-type diffusion layer on the semiconductor substrate (p-type diffusion layer formation step), and forming an electrode on the formed p-type diffusion layer (electrode formation step).
  • the p-type diffusion layer forming composition layer forming step and the p-type diffusion layer forming step For details of the p-type diffusion layer forming composition layer forming step and the p-type diffusion layer forming step, the p-type diffusion layer forming composition layer forming step and the p-type diffusion in the above-described method for manufacturing a semiconductor substrate with a p-type diffusion layer are described. This is the same as the details of the layer forming step.
  • FIG. 1 is a schematic cross-sectional view conceptually showing an example of a manufacturing process of a solar cell element.
  • a silicon substrate is used as the n-type semiconductor substrate.
  • the semiconductor substrate is not limited to a silicon substrate.
  • FIG. 1 (1) an alkaline solution is applied to the silicon substrate which is the n-type semiconductor substrate 10 to remove the damaged layer, and a texture structure is obtained by etching (the description of the texture structure is omitted in the figure).
  • a p-type diffusion layer forming composition layer 11 is formed by applying a p-type diffusion layer forming composition to the surface that becomes the light receiving surface of the n-type semiconductor substrate 10.
  • the p-type diffusion layer forming composition contains a solvent as a dispersion medium
  • the p-type diffusion layer forming composition was applied to remove at least part of the solvent contained in the composition before the thermal diffusion treatment.
  • the heat treatment in this case is performed at a temperature of 80 ° C. to 300 ° C., for example, under conditions of 1 minute to 10 minutes when using a hot plate and 10 minutes to 30 minutes when using a dryer or the like.
  • the heat treatment conditions depend on the type, composition, content, and the like of the solvent contained in the p-type diffusion layer forming composition, and are not particularly limited to the above conditions.
  • the p-type diffusion layer forming composition contains a binder as a dispersion medium
  • the p-type diffusion layer forming composition was applied to remove at least a part of the binder contained in the composition before the thermal diffusion treatment.
  • a process of heat-treating the subsequent n-type semiconductor substrate 10 is necessary.
  • a condition of treating at a temperature of 300 ° C. to 800 ° C. for 1 minute to 10 minutes is applied.
  • a known continuous furnace, batch furnace or the like can be applied to this heat treatment.
  • the heat treatment conditions depend on the type, composition, content, and the like of the binder contained in the p-type diffusion layer forming composition, and are not particularly limited to the above conditions.
  • the n-type semiconductor substrate 10 is subjected to a thermal diffusion process.
  • the acceptor element is diffused into the n-type semiconductor substrate 10, and a p-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 atmosphere in the furnace at the time of the thermal diffusion treatment can be selected according to desired conditions from an inert gas such as air, oxygen and nitrogen, and a mixed gas thereof.
  • a glass layer such as borate glass is formed on the surface of the p-type diffusion layer 12 formed on the light receiving surface of the n-type semiconductor substrate 10. For this reason, this borate glass is removed by etching.
  • any 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 an aqueous sodium hydroxide solution can be applied.
  • an etching treatment with hydrofluoric acid is preferable.
  • the etching treatment using hydrofluoric acid include a method of immersing the n-type semiconductor substrate 10 in hydrofluoric acid.
  • the immersion time is not particularly limited. Generally, it can be 0.5 minutes to 30 minutes, preferably 1 minute to 10 minutes.
  • boron silicide formed on the n-type semiconductor substrate 10 after boron diffusion is removed.
  • boron silicide is formed on the surface of the n-type semiconductor substrate 10, the surface passivation is hindered, and the power generation performance of the solar cell element is reduced. For this reason, the boron silicide on the surface is oxidized and converted into a boron silicate glass layer, and then etched.
  • the method for removing boron silicide is not particularly limited.
  • hydrofluoric acid may be used for etching with hydrofluoric acid while oxidizing the boron silicide with nitric acid, or boron silicide may be thermally oxidized in a furnace in an oxygen atmosphere and then etched with hydrofluoric acid.
  • the n-type diffusion layer forming composition layer 13 is formed by applying the n-type diffusion layer forming composition to the back surface of the n-type semiconductor substrate 10, that is, the surface opposite to the light receiving surface.
  • the method for applying the n-type diffusion layer forming composition can be performed by the same method as the method for applying the p-type diffusion layer forming composition described above to the light receiving surface of the n-type semiconductor substrate 10.
  • the thermal diffusion treatment is performed on the n-type semiconductor substrate 10 provided with the n-type diffusion layer forming composition on the back surface in the same manner as the thermal diffusion treatment in the p-type diffusion layer forming composition.
  • the n + -type diffusion layer 14 can be formed on the back surface of the n-type semiconductor substrate 10.
  • n-type diffusion layer forming composition for example, an n-type diffusion layer formation configured in the same manner as the p-type diffusion layer forming composition using glass particles containing a donor element instead of glass particles containing an acceptor element.
  • a composition can be mentioned.
  • the donor element include Group 15 elements such as P (phosphorus), Sb (antimony), and As (arsenic). Glass particles containing a donor element, when notation component oxides, P 2 O 5, Sb 2 O 3, and preferably contains at least one selected from the group consisting of As 2 O 3.
  • n-type diffusion layer may be formed by performing several tens of minutes.
  • phosphorus is diffused on the side surface and the back surface of the semiconductor substrate, and the n-type diffusion layer is formed not only on the light receiving surface but also on the side surface and the back surface. Therefore, a mask layer for preventing phosphorus diffusion is formed on the surface of the p-type diffusion layer.
  • the mask layer can be formed by applying a liquid containing a siloxane resin or the like serving as a precursor of SiO 2 and performing heat treatment (firing).
  • an antireflection film 15 is formed on the p-type diffusion layer 12.
  • the antireflection film 15 is formed by applying a known technique.
  • the antireflection film 15 is a silicon nitride film, it is formed by a plasma CVD (Chemical Vapor Deposition) method using a mixed gas of SiH 4 and NH 3 as a raw material.
  • a plasma CVD Chemical Vapor Deposition
  • SiH 4 and NH 3 a mixed gas of SiH 4 and NH 3 as a raw material.
  • hydrogen diffuses into the crystal, and orbitals that do not contribute to the bonding of silicon atoms, that is, dangling bonds and hydrogen are bonded to inactivate defects (hydrogen passivation).
  • the antireflection film 15 has, for example, a flow rate ratio (NH 3 / SiH 4 ) of the mixed gas of 0.05 to 1.0 and a reaction chamber pressure of 13.3 Pa (0.1 Torr) to The film is formed under the conditions of 266.6 Pa (2 Torr), a film forming temperature of 300 ° C. to 550 ° C., and a frequency for plasma discharge of 100 kHz or more.
  • a flow rate ratio (NH 3 / SiH 4 ) of the mixed gas of 0.05 to 1.0 and a reaction chamber pressure of 13.3 Pa (0.1 Torr) to The film is formed under the conditions of 266.6 Pa (2 Torr), a film forming temperature of 300 ° C. to 550 ° C., and a frequency for plasma discharge of 100 kHz or more.
  • a passivation layer may be formed on the p-type diffusion layer and the n-type diffusion layer.
  • an Al 2 O 3 layer may be laminated by an ALD (atomic layer deposition) method, or a SiO 2 film may be formed by thermal oxidation or the like.
  • the above-described antireflection film is formed on the passivation layer.
  • a light receiving surface electrode metal paste is printed on the light receiving surface antireflection film 15 by screen printing and dried to form a light receiving surface electrode metal paste layer 16.
  • a metal paste for light-receiving surface electrodes for example, a paste containing metal particles and glass particles, and containing a resin binder and other additives as required can be used.
  • the metal paste layer 18 for the back electrode is formed also on the back surface.
  • the material and forming method of the back electrode metal paste layer 18 are not particularly limited.
  • the back electrode metal paste layer 18 may be formed by applying a metal paste for the back electrode containing a metal such as aluminum, silver, or copper and drying the paste.
  • a silver paste for forming a silver electrode may be partially provided on the back surface for connection between solar cell elements in the module process.
  • the metal paste layer 16 for the light-receiving surface electrode is fired to complete the solar cell element.
  • the antireflection film 15 that is an insulating film is melted by the glass particles contained in the metal paste for the light receiving surface electrode on the light receiving surface side, and further the n-type semiconductor substrate 10 A part of the surface is also melted, and metal particles (for example, silver particles) in the paste are solidified by forming contact portions with the n-type semiconductor substrate 10.
  • the formed light receiving surface electrode 17 and the n-type semiconductor substrate 10 are electrically connected. This is called fire-through.
  • the back electrode metal paste of the back electrode metal paste layer 18 is baked to form the back electrode 19.
  • the light receiving surface electrode 17 includes a bus bar electrode 30 and a finger electrode 32 intersecting with the bus bar electrode 30.
  • FIG. 2A is a plan view of a solar cell element in which the light receiving surface electrode 17 includes a bus bar electrode 30 and a finger electrode 32 intersecting with the bus bar electrode 30 as viewed from the light receiving surface. It is a perspective view which expands and shows a part of 2A.
  • Such a light-receiving surface electrode 17 can be formed, for example, by means such as screen printing of the above-described metal paste for light-receiving surface electrode, plating of electrode material, deposition of electrode material by electron beam heating in high vacuum, or the like. .
  • the light-receiving surface electrode 17 having 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 known forming means for the bus bar electrode and the finger electrode on the light-receiving surface side are applied. Can do.
  • Example 1 (Preparation of p-type diffusion layer forming composition) A glass lump composed of B 2 O 3 , SiO 2 , Al 2 O 3 and CaO (composition molar ratio: 25 mol%, 65 mol%, 5 mol% and 5 mol%, respectively) was pulverized in an agate mortar, and then in a planetary ball mill Further, pulverization was performed to obtain glass particles (compound containing boron) having a spherical particle shape and an average particle diameter of 0.35 ⁇ m. 1 g, 2 g and 97 g of the glass particles, ethyl cellulose and terpineol were mixed to form a paste to prepare a p-type diffusion layer forming composition.
  • the shape of the glass particles was determined by observing using a scanning electron microscope (Hitachi High-Technologies Corporation, “TM-1000 type”). The average particle size of the glass was calculated using a laser scattering diffraction particle size distribution analyzer (Beckman Coulter, “LS 13, 320 type”, measurement wavelength: 632 nm).
  • a solid pattern (45 ⁇ 45 mm 2 ) is formed on one surface of an n-type silicon substrate (thickness: 725 ⁇ m, specific resistance: 3.1 ⁇ cm, sheet resistance: 200 ⁇ / sq.) On which a texture structure is formed by screen printing.
  • the p-type diffusion layer forming composition was applied to form a p-type diffusion layer forming composition layer and dried at 150 ° C. for 1 minute.
  • a screen plate having a mesh size of 460 mesh, a wire diameter of 27 ⁇ m, and a transmission volume of 11 cm 3 / m 2 was used.
  • the application amount of the p-type diffusion layer forming composition was 0.5 mg / cm 2
  • the application amount of glass particles (compound containing boron) was 0.005 mg / cm 2 .
  • the silicon substrate obtained above was put into a 700 ° C. diffusion furnace in which O 2 : 10 L / min was flowed, and held for 30 minutes.
  • the semiconductor substrate was taken out, allowed to cool, immersed in a 5% by mass HF aqueous solution for 5 minutes, washed with ultrapure water three times, and then air-dried. The surface was hydrophobic.
  • the sheet resistance of the application part was measured using a low resistivity meter (Mitsubishi Chemical Corporation, “Loresta MCP-T360”).
  • the sheet resistance of the applying portion is 49 ⁇ / sq. It was found that a p-type diffusion layer was formed.
  • a p-type diffusion layer forming composition was applied to both sides of the same silicon substrate as described above, and processed in the same manner to form a p-type diffusion layer.
  • the wafer was put in a polyethylene bag containing an ethanol solution containing 0.05 mol% of iodine, and the lifetime was measured using a ⁇ -PCD method lifetime measuring device WT-2000 (manufactured by Semilab). The lifetime was 150 ⁇ sec, and it was found that boron silicide on the surface of the silicon substrate could be removed. When boron silicide remains on the surface of the silicon substrate, the surface passivation of the silicon substrate becomes insufficient, and the lifetime is less than 100 ⁇ sec. Therefore, when the lifetime of 100 ⁇ sec or more was shown, it was determined that there was no residue on the surface of the silicon substrate and the passivation was “good”.
  • Example 2 to 4 and Comparative Examples 1 and 2 The treatment was performed in the same manner as in Example 1 except that the content of the boron-containing glass particles and the mesh of the screen plate were changed to the conditions described in Table 1. The evaluation results are summarized in Table 2.
  • SYMBOLS 10 ... n-type semiconductor substrate (silicon substrate), 11 ... p-type diffusion layer forming composition layer, 12 ... p-type diffusion layer, 13 ... n-type diffusion layer forming composition layer, 14 ... n + type diffusion layer, 15 reflection Prevention film, 16 ... Metal paste layer for light receiving surface electrode, 17 ... Light receiving surface electrode, 18 ... Metal paste layer for back electrode, 19 ... Back electrode, 30 ... Busbar electrode, 32 ... Finger electrode

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Abstract

Ce procédé de production d'un substrat semi-conducteur avec une couche de diffusion de type p comprend: une étape dans laquelle une composition formant une couche de diffusion de type p, qui contient un composé contenant du bore, est appliquée sur un substrat semi-conducteur, formant ainsi une couche de composition formant une couche de diffusion de type p dans laquelle la masse du composé contenant du bore par unité de surface est de 0,001 mg/cm 2 à 0,1 mg/cm 2; et une étape dans laquelle une couche de diffusion de type p est formée sur le substrat semi-conducteur par chauffage du substrat semi-conducteur, sur lequel la couche de composition formant une couche de diffusion de type p a été formée.
PCT/JP2017/025439 2016-07-14 2017-07-12 Procédé de fabrication d'un substrat semi-conducteur avec une couche de diffusion de type p, substrat semi-conducteur avec couche de diffusion de type p, procédé de production d'un élément de cellule solaire et élément de cellule solaire Ceased WO2018012547A1 (fr)

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CN114121624A (zh) * 2021-11-23 2022-03-01 浙江尚能实业股份有限公司 一种复合硼扩散源及其制备方法和半导体掺杂加工的方法
CN115995381A (zh) * 2023-02-17 2023-04-21 湖南红太阳光电科技有限公司 一种硼扩散工艺
JP2024026595A (ja) * 2020-03-26 2024-02-28 東京エレクトロン株式会社 基板処理方法および基板処理装置

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