WO2016010095A1 - Method for manufacturing semiconductor substrate having n-type diffusion layer, and method for manufacturing solar cell element - Google Patents

Method for manufacturing semiconductor substrate having n-type diffusion layer, and method for manufacturing solar cell element Download PDF

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WO2016010095A1
WO2016010095A1 PCT/JP2015/070322 JP2015070322W WO2016010095A1 WO 2016010095 A1 WO2016010095 A1 WO 2016010095A1 JP 2015070322 W JP2015070322 W JP 2015070322W WO 2016010095 A1 WO2016010095 A1 WO 2016010095A1
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Prior art keywords
diffusion layer
type diffusion
semiconductor substrate
type
manufacturing
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PCT/JP2015/070322
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French (fr)
Japanese (ja)
Inventor
岩室　光則
野尻　剛
倉田　靖
芦沢　寅之助
明博 織田
麻理 清水
鉄也 佐藤
佐藤　英一
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日立化成株式会社
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Priority to JP2016534479A priority Critical patent/JPWO2016010095A1/en
Priority to CN201580038703.6A priority patent/CN106537559A/en
Publication of WO2016010095A1 publication Critical patent/WO2016010095A1/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 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
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
    • 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
    • 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 a method for manufacturing a semiconductor substrate having an n-type diffusion layer and a method for manufacturing a solar cell element.
  • the crystalline silicon solar cell element is a power generation element including a p-type semiconductor region and an n-type semiconductor region.
  • a p-type semiconductor region or an n-type semiconductor region is formed on the whole or part of the crystalline silicon substrate.
  • p-type such as boron or aluminum used for forming the p-type semiconductor region.
  • barrier layer it is common to use a silicon oxide film that does not decompose even when subjected to a high-temperature treatment and can be removed by dissolving with hydrofluoric acid when unnecessary.
  • a method for forming a silicon oxide film a dry oxidation method or a wet oxidation method is often used.
  • a silicon oxide film is formed by these silicon oxide film forming methods, a thick silicon oxide film is selectively formed on the n-type semiconductor region (see, for example, JP-A-2014-86587).
  • the barrier layer protecting the n-type semiconductor region needs to be thick so that p-type dopants such as boron and aluminum used to form the p-type semiconductor do not diffuse into the n-type semiconductor region. .
  • p-type dopants such as boron and aluminum used to form the p-type semiconductor do not diffuse into the n-type semiconductor region.
  • the present invention has been made in view of the above circumstances, and enables an n-type diffusion layer to be formed in a desired portion of a semiconductor substrate, and a p-type dopant used for forming a p-type semiconductor is an n-type.
  • Means for solving the above problems include the following embodiments.
  • a method for manufacturing a semiconductor substrate having an n-type diffusion layer comprising a step of heat-treating under conditions that are seconds.
  • ⁇ 3> The method for producing a semiconductor substrate having an n-type diffusion layer according to ⁇ 1> or ⁇ 2>, wherein the donor element is at least one selected from the group consisting of P (phosphorus) and Sb (antimony) .
  • Glass particles containing the donor element are At least one donor element-containing material selected from the group consisting of P 2 O 3 , P 2 O 5 and Sb 2 O 3 , and SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, ⁇ 1> to ⁇ 3> containing at least one glass component material selected from the group consisting of CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5 , SnO, ZrO 2 and MoO 3
  • the manufacturing method of the semiconductor substrate which has an n type diffused layer of any one of these.
  • ⁇ 5> The method for producing a semiconductor substrate having an n-type diffusion layer according to any one of ⁇ 1> to ⁇ 4>, further including a step of oxidizing the semiconductor substrate having the n-type diffusion layer.
  • ⁇ 6> Production of a semiconductor substrate having an n-type diffusion layer according to any one of ⁇ 1> to ⁇ 5>, wherein the oxidation treatment is at least one selected from the group consisting of dry oxidation and wet oxidation Method.
  • ⁇ 7> The method for producing a semiconductor substrate having an n-type diffusion layer according to any one of ⁇ 1> to ⁇ 6>, wherein the semiconductor substrate is a silicon substrate.
  • n-type diffusion layer in a desired portion of a semiconductor substrate and prevent the p-type dopant used for forming the p-type semiconductor from diffusing into the n-type semiconductor region.
  • a method for manufacturing a semiconductor substrate having an n-type diffusion layer and a method for manufacturing a solar cell element which can form a barrier layer and reduce variation in sheet resistance.
  • the present invention will be described in detail. However, the present invention is not limited to the following embodiments.
  • the constituent elements including element steps and the like) are not essential unless explicitly specified, unless otherwise clearly considered essential in principle.
  • the term “process” includes a process that is independent of other processes and includes the process if the purpose of the process is achieved even if it cannot be clearly distinguished from the other processes. It is.
  • numerical values indicated by using “to” include numerical values described before and after “to” as the minimum value and the maximum value, respectively.
  • each component in the composition is the sum of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. It means the content rate of.
  • the particle diameter of each component in the composition is a mixture of the plurality of types of particles present in the composition unless there is a specific indication when there are a plurality of types of particles corresponding to each component in the composition. Means the value of.
  • the term “layer” refers to the case where the layer is formed only in a part of the region in addition to the case where the layer is formed over the entire region. Is also included.
  • the method for manufacturing a semiconductor substrate having an n-type diffusion layer includes an n-type diffusion layer forming composition containing glass particles containing a donor element and a dispersion medium (hereinafter referred to as “specific n-type diffusion layer formation”).
  • the method for manufacturing a semiconductor substrate having an n-type diffusion layer may further include other steps as necessary.
  • linear velocity in the heat treatment step means a distance that the gas travels per unit time.
  • the value of the linear velocity is a value that does not depend on the conditions of the diffusion furnace to be used (for example, the design value (diameter) of the quartz tube). For example, when the diameter of the quartz tube of the diffusion furnace is 252 mm and the linear velocity is 10 mm / second, the flow rate per unit time is obtained by multiplying the cross-sectional area calculated from the diameter of the quartz tube by the linear velocity. In this case, 30 L of gas flows in the quartz tube per minute. If the linear velocity is 3 mm / second or 60 mm / second with the diameter of the quartz tube made of 252 mm, the gas flow rate is 9 L / min or 180 L / min, respectively.
  • the manufacturing method of a semiconductor substrate having an n-type diffusion layer can form an oxide film having a sufficient thickness as a barrier layer that prevents the p-type dopant from diffusing into the n-type semiconductor region by having the above structure. .
  • the reason is not clear, but is presumed as follows.
  • the specific n-type diffusion layer forming composition contains glass particles containing a donor element and a dispersion medium. Glass particles soften at high temperatures during heat treatment. The donor element moves from the softened glass particles to the semiconductor substrate to form an n-type semiconductor region, and a glass layer is formed on the n-type semiconductor region by the glass component in the glass particles.
  • the n-type semiconductor region on the semiconductor substrate is exposed by removing the glass layer by etching with hydrofluoric acid or the like.
  • the exposed n-type semiconductor region is more easily oxidized than a region where the donor element is not diffused. Therefore, by performing the oxidation treatment, an oxide film is formed thicker on the n-type semiconductor region than the region where the donor element is not diffused. This oxide film functions as a barrier film when the p-type dopant is diffused in a later step.
  • the gas flow rate to 3 mm / second to 60 mm / second, the dispersion medium contained in the n-type diffusion layer forming composition is efficiently scattered and the glass layer is easily formed. Furthermore, the residual ratio of the dispersion medium in the glass layer to be formed can be reduced, and variations in sheet resistance of the manufactured semiconductor substrate and solar cell element having the n-type diffusion layer are reduced.
  • n-type diffusion layer forming composition a specific n-type diffusion layer forming composition will be described, and then a semiconductor substrate manufacturing method and a solar cell element manufacturing method using these n-type diffusion layer forming compositions will be described.
  • the specific n-type diffusion layer forming composition contains glass particles containing a donor element (hereinafter also referred to as “glass particles”) and a dispersion medium.
  • the specific n-type diffusion layer forming composition may contain other components as required in consideration of coating properties and the like.
  • the n-type diffusion layer forming composition contains a donor element, and is applied to the semiconductor substrate, and then thermally diffuses the donor element, so that the n-type diffusion layer forming composition of the semiconductor substrate is applied to the site.
  • an n-type diffusion layer can be selectively formed in a desired portion of the semiconductor substrate to which the specific n-type diffusion layer forming composition is applied, and on the back surface, side surface, etc. of the semiconductor substrate It becomes easy not to form an unnecessary n-type diffusion layer. Therefore, if the specific n-type diffusion layer forming composition is applied, the side etching step performed by the gas phase reaction method that has been widely adopted conventionally becomes unnecessary, and the process tends to be simplified. Further, there is no need to convert the n-type diffusion layer formed on the back surface of the semiconductor substrate into a p + -type diffusion layer.
  • the method for forming the p + -type diffusion layer on the back surface, the material, shape, thickness, and the like of the back electrode are not limited, and options for the manufacturing method, material, shape, and the like to be applied are expanded. Moreover, although mentioned later for details, generation
  • the glass particles contained in the specific n-type diffusion layer forming composition are melted by heat treatment to form a glass layer on the n-type diffusion layer.
  • a glass layer is formed on the n-type diffusion layer even in a conventional gas phase reaction method, a method of applying a phosphate-containing solution, or the like. Therefore, the glass layer formed in the method of the present embodiment can be removed by etching as in the conventional method. Therefore, the specific n-type diffusion layer forming composition tends not to generate unnecessary products and increase the number of steps as compared with the conventional method.
  • the glass particles are not volatilized even during the heat treatment, the generation of the volatilized gas tends to prevent the n-type diffusion layer from being formed not only on the surface of the semiconductor substrate but also on the back surface or side surface of the semiconductor substrate. For this reason, for example, it is considered that the donor component is not easily volatilized because it is bonded to the element in the glass particle or is taken into the glass.
  • the donor element contained in the glass particles means an element that can be diffused into the semiconductor substrate by doping to form an n-type diffusion layer.
  • a Group 15 element can be used.
  • the Group 15 element include P (phosphorus), Sb (antimony), and As (arsenic). From the viewpoint of safety, ease of vitrification, etc., the donor element is preferably at least one selected from the group consisting of P (phosphorus) and Sb (antimony).
  • Examples of the donor element-containing material used for introducing the donor element into the glass particles include P 2 O 3 , P 2 O 5 , Sb 2 O 3 , Bi 2 O 3 , and As 2 O 3. At least one selected from the group consisting of 2 O 3 , P 2 O 5 and Sb 2 O 3 is preferable.
  • the glass particles can be controlled in terms of melting temperature, softening point, glass transition point, chemical durability, and the like by adjusting the component ratio as necessary. From this viewpoint, it is preferable that the glass particles further contain a glass component substance as described below.
  • the glass component material include SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, WO 3 , MoO 3 , MnO, and La. 2 O 3 , 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 may be mentioned.
  • the glass particles are made of SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , WO 3 , MoO 3 and MnO. It is preferable to include at least one selected from the glass component substances.
  • the glass particles are composed of SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5 , SnO, ZrO 2 and MoO 3. It is more preferable that at least one selected from the above is included as a glass component substance.
  • the glass particles containing a donor element include at least one donor element-containing material selected from the group consisting of P 2 O 3 , P 2 O 5 and Sb 2 O 3 , and SiO 2 , K 2 O. , Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5 , SnO, ZrO 2, and MoO 3. It is preferable to contain a substance.
  • the glass particles containing a donor element in the present invention include, for example, P 2 O 5 —SiO 2 glass particles, P 2 O 5 —K 2 O glass particles, and P 2 O 5 —Na 2 O glass.
  • the glass particles may be composite glass particles containing three or more kinds of components such as P 2 O 5 —SiO 2 —CaO as desired.
  • the content of the glass component substance in the glass particles is desirably set as appropriate in consideration of the melting temperature, softening point, glass transition point, chemical durability, and the like.
  • the content of the glass component substance is preferably 0.1% by mass to 95% by mass, and more preferably 0.5% by mass to 90% by mass.
  • the softening point of the glass particles is preferably 200 ° C. to 1000 ° C., for example, from 300 ° C. to 900 ° C. from the viewpoint of diffusibility of the components of the specific n-type diffusion layer forming composition during heat treatment, dripping, etc. It is more preferable that
  • the shape of the glass particles examples include a substantially spherical shape, a flat shape, a block shape, a plate shape, and a scale shape.
  • the glass particles are preferably substantially spherical, flat or plate-like from the viewpoint of application properties to a semiconductor substrate, uniform diffusibility, and the like when an n-type diffusion layer forming composition is used.
  • the average particle size of the glass particles is preferably 100 ⁇ m or less, for example. When glass particles having an average particle size of 100 ⁇ m or less are used, a smooth composition layer is easily obtained.
  • the average particle size of the glass particles is, for example, preferably 50 ⁇ m or less, and more preferably 30 ⁇ m or less.
  • the lower limit is not particularly limited, but is preferably 0.01 ⁇ m or more, for example.
  • the average particle diameter of the glass particles represents a volume average particle diameter, and can be measured by a laser scattering diffraction particle size distribution measuring apparatus or the like.
  • the volume average particle diameter is a value (D 50 ) when the accumulation from the small diameter side is 50% in the volume-based particle diameter distribution.
  • Glass particles containing a donor element can be produced by the following procedure.
  • a glass particle raw material containing a donor element is weighed and filled in a crucible.
  • the material for the crucible include platinum, platinum-rhodium, gold, iridium, alumina, quartz, carbon, and the like, which 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 so that the melt is sufficiently mixed.
  • the heating temperature is not particularly limited as long as it is a temperature at which the donor element-containing material is combined with the glass component material.
  • the glass component substance when SiO 2 is used as the glass component substance, it is preferable to produce a glass particle containing the donor element by heating a mixture containing the glass component substance and the donor element-containing substance to 1400 ° C. or higher. Subsequently, the obtained melt is poured onto a metal plate or the like to vitrify the melt. Next, the obtained glass is pulverized into particles.
  • a known method using a stamp mill, a jet mill, a bead mill, a ball mill or the like can be applied.
  • the content ratio of the glass particles containing the donor element in the n-type diffusion layer forming composition is determined in consideration of the coating property, the diffusibility of the donor element, and the like.
  • the glass particle content in the n-type diffusion layer forming composition is, for example, 0.1% by mass to 95% by mass with respect to the total mass of the n-type diffusion layer forming composition. It is preferably 1% by mass to 90% by mass, more preferably 2% by mass to 80% by mass.
  • the content of the glass particles containing the donor element in the n-type diffusion layer forming composition is, for example, 0.1% by mass to 99% by mass with respect to the total amount of nonvolatile components in the n-type diffusion layer forming composition. It is preferably 1% by mass to 95% by mass, more preferably 2% by mass to 90% by mass.
  • the “nonvolatile component” means a component in the n-type diffusion layer forming composition other than a volatile substance such as a solvent described later.
  • the volatile substance means a substance having a boiling point of 250 ° C. or lower under atmospheric pressure.
  • the dispersion medium is a medium in which the glass particles are dispersed in the specific n-type diffusion layer forming composition.
  • a binder, a solvent, or the like is used as the dispersion medium.
  • binder examples include dimethylaminoethyl (meth) acrylate polymer, polyvinyl alcohol, polyacrylamides, polyvinylamides, polyvinylpyrrolidone, poly (meth) acrylic acids, polyethylene oxides, polysulfonic acid, acrylamide alkyl sulfonic acid, and cellulose ether.
  • Cellulose derivatives carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, gelatin, starch and starch derivatives, sodium alginate, xanthan, guar gum and guar gum derivatives, scleroglucan, tragacanth, dextrin derivatives, acrylic acid resin, acrylate resin, butadiene Examples thereof include resins, styrene resins, copolymers thereof, and silicon dioxide.
  • a binder is used individually by 1 type or in combination of 2 or more types.
  • the weight average molecular weight of the binder is not particularly limited, and it is desirable to appropriately adjust in consideration of a desired viscosity as the specific n-type diffusion layer forming composition.
  • Examples of the solvent include 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, diethyl ketone, and dipropyl.
  • Ketone solvents such as ketone, diisobutylketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, ⁇ -butyrolactone, ⁇ -valerolactone, diethyl ether, methyl ethyl ether, Methyl-n-di-n-propyl ether, diisopropyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethylene glycol dimethyl ether, ethyl Lenglycol diethyl ether, 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
  • the content of the dispersion medium in the specific n-type diffusion layer forming composition is determined in consideration of coating properties, donor concentration, and the like.
  • the viscosity of the specific n-type diffusion layer forming composition is, for example, preferably from 10 mPa ⁇ S to 1000000 mPa ⁇ S, and more preferably from 50 mPa ⁇ S to 500000 mPa ⁇ S, from the viewpoint of applicability.
  • the specific n-type diffusion layer forming composition may contain other additives.
  • other additives include metals.
  • 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, and at that time, a glass layer is formed on the surface of the n-type diffusion layer. This glass layer can be removed by etching. However, it may be difficult to remove depending on the type of glass formed. In that case, the glass is removed during the etching by adding a metal such as Al, Ag, Mn, Cu, Fe, Zn, Si, which easily crystallizes with the glass layer, to the n-type diffusion layer forming composition. It tends to be easier.
  • the metal as a conductive material is not a main component, and the metal content depends on the type of glass, the type of metal, and the like. It is desirable to adjust appropriately.
  • the content of the metal in the n-type diffusion layer forming composition is 10% by mass with respect to the glass particles from the viewpoint of not reducing the bulk lifetime of the semiconductor substrate. Is preferably 7% by mass or less, more preferably 5% by mass or less.
  • the metal content is preferably 0.01% by mass or more with respect to the glass particles from the viewpoint of the glass layer removal efficiency, The content is more preferably 1% by mass or more, and further preferably 3% by mass or more.
  • the semiconductor substrate used in the present invention is not particularly limited, and a semiconductor substrate used for a solar cell element can be applied.
  • Examples include substrates, indium phosphide substrates, silicon carbide, silicon germanium substrates, and copper indium selenium substrates.
  • An example of the silicon substrate is a crystalline silicon substrate.
  • the semiconductor substrate is preferably pretreated before applying the specific n-type diffusion layer forming composition.
  • pretreatment include the following steps. In the following description, a specific n-type semiconductor substrate is used, but a p-type semiconductor substrate may be used.
  • An alkaline solution is applied to the n-type semiconductor substrate to remove the damaged layer, and a texture structure is obtained by etching. Specifically, the damaged layer on the surface of the n-type semiconductor substrate generated when slicing from the ingot is removed with a 20% by mass aqueous sodium hydroxide solution.
  • etching is performed with a mixed liquid of 1% by mass caustic soda and 10% by mass isopropyl alcohol to form a texture structure.
  • the solar cell element has a texture structure on the light receiving surface side, thereby promoting a light confinement effect and increasing efficiency.
  • the method for producing a semiconductor substrate having an n-type diffusion layer according to the present invention comprises an n-type diffusion layer forming composition (hereinafter referred to as “specific”) containing glass particles containing a donor element and a dispersion medium before the heat treatment step.
  • the n-type diffusion layer forming composition layer (hereinafter also referred to as “n-type diffusion composition layer”) is formed by applying at least part of the semiconductor substrate.
  • a step hereinafter also referred to as “n-type diffusion composition layer forming step”) may be included.
  • the method for applying the specific n-type diffusion layer forming composition to at least a part of the semiconductor substrate is not particularly limited.
  • a printing method, a spin coating method, a brush coating, a spray method, a doctor blade method, a roll coating method, and an ink jet method can be mentioned.
  • the shape of the region to which the specific n-type diffusion layer forming composition is applied can be appropriately changed depending on the region where the n-type diffusion layer is to be formed.
  • the n-type diffusion composition layer is dried to obtain a dispersion medium. You may remove at least one part.
  • the drying temperature is not particularly limited, and examples thereof include a temperature of about 80 ° C. to 300 ° C. For example, it can be dried 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 dispersion medium composition of the specific n-type diffusion layer forming composition, and are not particularly limited to the above conditions in the present invention.
  • Heat treatment process In the heat treatment step, a semiconductor substrate to which at least part of the composition for forming an n-type diffusion layer containing glass particles containing a donor element and a dispersion medium is applied at a gas flow rate of 3 mm / second to 60 mm at a linear velocity.
  • the heat treatment is performed under the condition of / sec.
  • the donor element diffuses into the n-type semiconductor substrate, and an n-type diffusion layer is formed.
  • a glass layer such as phosphate glass is formed on the surface of the n-type diffusion layer.
  • the gas flow rate in the heat treatment step is 3 mm / second or more in linear velocity, there is a tendency that a high concentration of the donor element can be diffused in the formed n-type diffusion layer. If the gas flow rate is 60 mm / sec or less in terms of linear velocity, it is easy to suppress variations in the heat treatment temperature, and a stable quality n-type diffusion layer is likely to be obtained.
  • the flow rate of the gas is, for example, preferably 4 mm / second or more, more preferably 5 mm / second or more, and 6 mm / second or more in linear velocity. Is more preferable.
  • the flow rate of the gas is, for example, preferably 50 mm / second or less, more preferably 40 mm / second or less, and further preferably 30 mm / second or less in linear velocity. It is particularly preferably 20 mm / second or less.
  • the heat treatment temperature is not particularly limited, and examples thereof include 600 ° C. to 1200 ° C. From the viewpoint of suppressing temperature variations in the heating device, the temperature is preferably 700 ° C. to 1150 ° C., more preferably 750 ° C. to 1100 ° C.
  • the heat treatment time is not particularly limited and may be, for example, 1 minute to 60 minutes, and may be 2 minutes to 40 minutes from the viewpoint of mass productivity of manufacturing a semiconductor substrate having an n-type diffusion layer and a solar cell element. Preferably, it is 3 minutes to 25 minutes.
  • the kind of gas in the heat treatment step is not particularly limited, and can be selected from a single gas, a compound gas, and the like.
  • the single gas include nitrogen gas, oxygen gas, hydrogen gas, helium gas, neon gas, argon gas, krypton gas, xenon gas, radon gas, and halogen gas.
  • the compound gas organic gases such as methane and propane, phosphorus oxychloride, boron tribromide, boron trichloride, etc. that can be gasified by heating can be used. These can be used alone or in combination of two or more.
  • the gas in the heat treatment step may contain air.
  • the gas in the heat treatment step preferably contains oxygen gas from the viewpoint of forming an n-type diffusion layer on which variation in thickness and the like is suppressed on the semiconductor substrate.
  • the mixing ratio of oxygen gas is not particularly limited in the present invention.
  • a known continuous diffusion furnace, batch diffusion furnace, or the like can be used.
  • the method for manufacturing a semiconductor substrate having an n-type diffusion layer according to the present invention further includes a step of removing the glass layer formed on the semiconductor substrate by etching after the heat treatment step (hereinafter also referred to as “etching step”). May be included.
  • etching step a step of removing the glass layer formed on the semiconductor substrate by etching after the heat treatment step.
  • the n-type semiconductor substrate can be cooled to room temperature and then etched.
  • Etching can be performed by 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.
  • the glass layer formed on the surface of the n-type diffusion layer by the heat treatment step is formed by melting the glass particles at the above heat treatment temperature and cooling it.
  • the cooling rate is preferably in the range of 5 ° C./second to 300 ° C./second, for example.
  • the cooling rate is 300 ° C./second or less, the surface of the glass layer is suppressed from being cooled more rapidly than the other parts, and the decrease in the cooling rate inside the glass layer is suppressed. Generation is easily suppressed.
  • the cooling rate is more preferably 10 ° C./second to 50 ° C./second.
  • the n-type semiconductor substrate may be washed and dried.
  • the method for manufacturing a semiconductor substrate having an n-type diffusion layer may further include a step of oxidizing the semiconductor substrate having the n-type diffusion layer (hereinafter also referred to as “oxidation processing step”).
  • An oxide film such as a silicon oxide film is formed by the oxidation treatment.
  • the oxide film tends to be formed thick in the region of the n-type diffusion layer and thin in other regions.
  • the oxide film other than the region of the n-type diffusion layer is preferably removed by etching. At that time, the thickness of the oxide film formed in the region of the n-type diffusion layer also tends to be reduced by etching.
  • the method for the oxidation treatment is not particularly limited, and is preferably at least one selected from the group consisting of dry oxidation and wet oxidation.
  • Dry oxidation means an oxidation method by treating at a high temperature in an oxygen gas atmosphere. Dry oxidation conditions are not particularly limited, and for example, it is preferable to perform the treatment at 800 ° C. to 1100 ° C. for 10 minutes to 240 minutes.
  • Wet oxidation means an oxidation method by processing at a high temperature using oxygen gas and deionized water vapor.
  • the conditions for wet oxidation are not particularly limited. For example, it is preferable to perform the treatment at 800 ° C. to 1100 ° C. for 10 minutes to 240 minutes.
  • a step of diffusing a p-type donor element may be further included after the oxidation treatment step.
  • a p-type donor element source for example, a gas containing a p-type donor element such as boron tribromide (BBr 3 ) or boron trichloride (BCl 3 ), and other components such as a p-type donor element and a dispersion medium The composition containing these is mentioned.
  • a diffusion gas such as BBr 3 can be introduced into a heated diffusion furnace to diffuse and deposit the p-type donor element on the surface of the n-type semiconductor substrate.
  • the method for applying the boron-containing composition to the surface of the n-type semiconductor substrate is not particularly limited. Examples thereof include a printing method, a spin coating method, a brush coating, a spray method, a doctor blade method, a roll coating method, and an ink jet method.
  • a composition containing boron is applied to the n-type semiconductor substrate, and the p-type donor element can be diffused by heat treatment in a diffusion furnace.
  • the oxidation treatment is performed before the step of diffusing the p-type donor element, an oxide film functioning as a barrier layer is formed on the n-type diffusion layer before diffusing the p-type donor element. For this reason, even if the gas or composition containing a p-type donor element is used, it is easy to prevent the p-type donor element from diffusing into the n-type diffusion layer.
  • the method for manufacturing a solar cell element of the present invention includes a step of forming an electrode on a semiconductor substrate having an n-type diffusion layer manufactured by the method for manufacturing a semiconductor substrate having an n-type diffusion layer of the present invention.
  • the step of forming the electrode can be performed separately from the step of forming the n-type diffusion layer. Since it is possible to form the n-type diffusion layer and the electrode separately, as will be described later, there is a tendency for options such as the material of the electrode and the forming method to expand.
  • the material and forming method of the electrode are not particularly limited, and materials and forming methods known in the art can be adopted.
  • the material of the electrode is not limited to Group 13 aluminum used in the prior art, and Ag (silver), Cu (copper), etc. can be applied, and the thickness of the electrode is also thinner than the conventional one. It becomes possible to do.
  • a semiconductor substrate having an n-type diffusion layer manufactured by a method for manufacturing a semiconductor substrate having an n-type diffusion layer is manufactured using a specific n-type diffusion layer forming composition, it is selected as a desired portion of the semiconductor substrate. In particular, an n-type diffusion layer is formed.
  • a p-type diffusion layer is formed by applying a heat treatment by applying an aluminum paste as a group 13 element to an n-type diffusion layer formed in a region other than a desired region, and diffusing aluminum in the n-type diffusion layer.
  • the method of converting to is widely adopted. In this method, conversion to the p-type diffusion layer is sufficient, and in order to form a high-concentration electric field layer of the p + -type diffusion layer, a certain amount of aluminum is required. Need to form.
  • the thermal expansion coefficient of aluminum is significantly different from that of the semiconductor substrate, a large internal stress tends to be generated in the semiconductor substrate during the heat treatment and cooling. This internal stress damages the crystal grain boundary when crystalline silicon is used as the semiconductor substrate, and there is a problem that power loss increases in a solar cell using this semiconductor substrate.
  • the semiconductor substrate may be warped due to internal stress. The warpage of the semiconductor substrate facilitates damage of the solar cell element when transporting the solar cell element in the module process, connecting to a copper wire called a tab wire, or the like.
  • the silicon substrate which is a semiconductor substrate, has been thinned due to the improvement of the slicing technique, and the solar cell element is more easily damaged by warping.
  • a semiconductor substrate having an n-type diffusion layer in which an n-type diffusion layer is formed in a desired portion is used, other than the desired portion that has been performed by the conventional method.
  • Side etching or the like for removing the n-type diffusion layer formed on the substrate becomes unnecessary, and the process tends to be simplified.
  • the step of converting the n-type diffusion layer formed in a region other than the desired portion into the p + -type diffusion layer is not necessary, and the necessity of increasing the thickness of the aluminum layer is eliminated. As a result, generation of internal stress in the semiconductor substrate and warpage of the semiconductor substrate can be suppressed.
  • the method for forming the p + -type diffusion layer, the material, shape, thickness, etc. of the electrode are not limited to the conventional methods, and there are tendencies to expand the choices of manufacturing method, material, shape, etc. to be applied.
  • 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.
  • symbol is attached
  • an alkaline solution is applied to a crystalline silicon substrate which is an n-type semiconductor substrate 1 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 surface of the silicon substrate generated when slicing from the ingot is removed with 20% by mass caustic soda.
  • etching is performed using a mixed liquid of 1% by mass caustic soda and 10% by mass isopropyl alcohol to form a textured structure (in FIG. 1 (1), only one side of the n-type semiconductor substrate 1 has a description of the textured structure) To do).
  • the solar cell element by forming a texture structure on the light receiving surface (the lower surface in FIG. 1 (1)), a light confinement effect is promoted, and high efficiency is achieved.
  • the specific n-type diffusion layer forming composition according to the present invention is partially applied to the surface of the n-type semiconductor substrate 1, that is, the surface to be the light-receiving surface, thereby forming an n-type diffusion composition layer. 2 is formed.
  • the n-type semiconductor substrate 1 having the n-type diffusion composition layer 2 shown in FIG. 1 (2) is set to 600 ° C. to 1200 ° C., and the gas flow rate is set in the range of 3 mm / second to 60 mm / second in linear velocity.
  • Heat treatment thermal diffusion
  • the donor element diffuses into the semiconductor substrate, and the n-type diffusion layer 3 is formed.
  • a glass layer (not shown) such as phosphate glass is formed on the surface of the n-type diffusion layer 3.
  • the n-type semiconductor substrate 1 After the heat treatment, the n-type semiconductor substrate 1 is cooled to room temperature. Thereafter, the glass layer formed on the n-type semiconductor substrate 1 is removed by etching.
  • a silicon oxide film 4 shown in FIG. 1 (3) is formed by oxidation treatment.
  • the silicon oxide film 4 is formed thick in the region of the n-type diffusion layer 3 and thin in other regions.
  • the silicon oxide film 4 other than the region of the n-type diffusion layer 3 is removed by etching.
  • the thickness of the silicon oxide film formed in the region of the n-type diffusion layer 3 also tends to be reduced by etching. Therefore, the etching is stopped when the silicon oxide film 4 other than the region of the n-type diffusion layer 3 is sufficiently removed.
  • FIG. 1 (4) an n-type semiconductor substrate having the silicon oxide film 4 as a barrier layer only in the region of the n-type diffusion layer 3 is obtained.
  • a boron silicate glass layer 5 is formed on the n-type semiconductor substrate 1 and the silicon oxide film 4 shown in FIG. 1 (4), and a p-type diffusion layer 6 is formed by diffusing a p-type donor element.
  • a p-type diffusion layer 6 is formed in a region where the boron silicate glass layer 5 is in contact with the n-type semiconductor substrate 1.
  • the n-type diffusion layer 3 since the silicon oxide film 4 existing on the n-type diffusion layer 3 functions as a barrier layer, the donor element from the boron silicate glass layer 5 does not diffuse.
  • the boron silicate glass layer 5 and the silicon oxide film 4 are removed by etching to obtain the n-type semiconductor substrate 1 including the n-type diffusion layer 3 and the p-type diffusion layer 6 as shown in FIG.
  • the method for manufacturing the back contact type solar cell element including the n-type diffusion layer 3 and the p-type diffusion layer 6 on one surface of the n-type semiconductor substrate 1 has been described. However, if the method for producing a semiconductor substrate having an n-type diffusion layer of the present invention is used, a double-sided electrode type solar cell element can also be produced.
  • the method of manufacturing the back contact type solar cell element provided with the n-type diffusion layer and the p-type diffusion layer on one side of the n-type semiconductor substrate has been described.
  • An electrode-type solar cell element can also be manufactured.
  • Example 1 9. P 2 O 5 —SiO 2 —MgO glass (P 2 O 5 : 34%, SiO 2 : 39%, CaO: 27%) particles having an average particle size of 1 ⁇ m, 9 g of ethyl cellulose, 2.1 g of terpineol, and 18. 9 g was mixed to prepare a paste-like n-type diffusion layer forming composition. Next, the prepared n-type diffusion layer forming composition was applied to the surface of the n-type silicon substrate by screen printing and dried on a hot plate at 150 ° C. for 5 minutes. Next, it was kept in an oven set at 450 ° C. for 1.5 minutes to release ethyl cellulose.
  • the sheet resistance was measured at five points within the surface where the n-type diffusion layer forming composition of the obtained silicon substrate having a length of 156 mm and a width of 156 mm was applied. The standard deviation of the obtained sheet resistance was obtained, and the degree of variation in sheet resistance was evaluated based on the value calculated by dividing by the average value as a numerical value of 100 minutes.
  • the sheet resistance was measured by a four-probe method using a “Loresta-EP MCP-T360 type low resistivity meter” (Mitsubishi Chemical Corporation).
  • the silicon oxide film and the boron silicate glass film were removed by hydrofluoric acid etching.
  • the secondary ion mass spectrometer “IMS-7F” CAMECA
  • the n-type diffusion layer region of the obtained silicon substrate was subjected to a primary ion energy of 6000 eV while flowing oxygen gas into the analysis chamber. Secondary ion mass spectrometry was performed to a depth of 2 ⁇ m, and the amount of boron was measured. When the amount of boron was less than 1E16 (1 ⁇ 10 16 ) atoms / cm 3 , it was determined that the silicon oxide film had a barrier property. The results are shown in Table 1.
  • Example 2 to Example 4> Other than changing the linear velocity of the gas flowing in the diffusion furnace to 7 mm / second (Example 2), 10 mm / second (Example 3), or 20 mm / second (Example 4) during the thermal diffusion in Example 1 Performed the same treatment as in Example 1, and evaluated the average thickness of the silicon oxide film and the presence or absence of barrier properties. The results are shown in Table 1.

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Abstract

　A method for manufacturing a semiconductor substrate having an n-type diffusion layer including a step for heat-treating a semiconductor substrate such that the gas flow rate is 3-60 mm/sec in linear speed, at least a part of the semiconductor substrate being imparted with an n-type-diffusion-layer-forming composition that contains a dispersion medium and glass particles containing a donor element.

Description

ｎ型拡散層を有する半導体基板の製造方法及び太陽電池素子の製造方法Manufacturing method of semiconductor substrate having n-type diffusion layer and manufacturing method of solar cell element
　本発明は、ｎ型拡散層を有する半導体基板の製造方法及び太陽電池素子の製造方法に関する。 The present invention relates to a method for manufacturing a semiconductor substrate having an n-type diffusion layer and a method for manufacturing a solar cell element.
　従来の結晶シリコン太陽電池素子の製造工程について説明する。結晶シリコン太陽電池素子は、ｐ型半導体領域及びｎ型半導体領域を備えた発電素子である。結晶シリコン太陽電池素子の製造過程において、結晶シリコン基板の全体又は一部にｐ型半導体領域又はｎ型半導体領域を形成する。ここで、ｎ型半導体領域を形成した後、ｎ型半導体領域以外の領域にｐ型半導体領域を形成する場合には、ｐ型半導体領域を形成するために使用されるホウ素、アルミニウム等のｐ型ドーパントがｎ型半導体領域に拡散しないように、ｎ型半導体領域に予めバリア層を形成して保護することが一般的である。 A manufacturing process of a conventional crystalline silicon solar cell element will be described. The crystalline silicon solar cell element is a power generation element including a p-type semiconductor region and an n-type semiconductor region. In the process of manufacturing a crystalline silicon solar cell element, a p-type semiconductor region or an n-type semiconductor region is formed on the whole or part of the crystalline silicon substrate. Here, after forming the n-type semiconductor region, when forming the p-type semiconductor region in a region other than the n-type semiconductor region, p-type such as boron or aluminum used for forming the p-type semiconductor region. In order to prevent the dopant from diffusing into the n-type semiconductor region, it is common to protect the n-type semiconductor region by forming a barrier layer in advance.
　上述のバリア層としては、高温処理を行っても分解することなく、且つ不必要となった際にはフッ酸で溶解することにより除去できる酸化シリコン膜を使用することが一般的である。酸化シリコン膜を形成する方法としては、ドライ酸化法又はウェット酸化法がよく用いられる。これらの酸化シリコン膜形成法で酸化シリコン膜を形成すると、ｎ型半導体領域上に選択的に厚い酸化シリコン膜が形成される（例えば、特開２０１４－８６５８７号公報参照）。 As the above-described barrier layer, it is common to use a silicon oxide film that does not decompose even when subjected to a high-temperature treatment and can be removed by dissolving with hydrofluoric acid when unnecessary. As a method for forming a silicon oxide film, a dry oxidation method or a wet oxidation method is often used. When a silicon oxide film is formed by these silicon oxide film forming methods, a thick silicon oxide film is selectively formed on the n-type semiconductor region (see, for example, JP-A-2014-86587).
　上述のように、ｐ型半導体を形成するために使用されるホウ素、アルミニウム等のｐ型ドーパントがｎ型半導体領域に拡散しないように、ｎ型半導体領域を保護するバリア層を厚くする必要がある。このような厚いバリア層を形成するためには、ｎ型半導体領域にＰ（リン）、Ｓｂ（アンチモン）等に代表されるｎ型ドーパントが多く熱拡散されていることが望ましい。 As described above, the barrier layer protecting the n-type semiconductor region needs to be thick so that p-type dopants such as boron and aluminum used to form the p-type semiconductor do not diffuse into the n-type semiconductor region. . In order to form such a thick barrier layer, it is desirable that a large amount of n-type dopants typified by P (phosphorus), Sb (antimony), etc. be thermally diffused in the n-type semiconductor region.
　本発明は、上記事情に鑑みなされたものであり、半導体基板の所望の部位にｎ型拡散層を形成することを可能とし、ｐ型半導体を形成するために使用されるｐ型ドーパントがｎ型半導体領域に拡散するのを防止するバリア層を形成可能であり、且つシート抵抗のバラつきの低減が可能である、ｎ型拡散層を有する半導体基板の製造方法及び太陽電池素子の製造方法を提供する。 The present invention has been made in view of the above circumstances, and enables an n-type diffusion layer to be formed in a desired portion of a semiconductor substrate, and a p-type dopant used for forming a p-type semiconductor is an n-type. Provided is a method for manufacturing a semiconductor substrate having an n-type diffusion layer and a method for manufacturing a solar cell element, which can form a barrier layer that prevents diffusion into a semiconductor region and can reduce variation in sheet resistance. .
　上記課題を解決するための手段には、以下の実施態様が含まれる。
＜１＞　ドナー元素を含むガラス粒子と、分散媒と、を含有するｎ型拡散層形成組成物が少なくとも一部に付与された半導体基板を、ガスの流量が線速度で３ｍｍ／秒～６０ｍｍ／秒である条件下で熱処理する工程を含む、ｎ型拡散層を有する半導体基板の製造方法。
＜２＞　前記熱処理する工程の後、前記半導体基板上に形成されたガラス層をエッチングにより除去する工程を更に含む＜１＞に記載のｎ型拡散層を有する半導体基板の製造方法。
＜３＞　前記ドナー元素が、Ｐ（リン）及びＳｂ（アンチモン）からなる群より選択される少なくとも１種である＜１＞又は＜２＞に記載のｎ型拡散層を有する半導体基板の製造方法。
＜４＞　前記ドナー元素を含むガラス粒子が、
　Ｐ２Ｏ３、Ｐ２Ｏ５及びＳｂ２Ｏ３からなる群より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、Ｖ２Ｏ５、ＳｎＯ、ＺｒＯ２及びＭｏＯ３からなる群より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＜１＞～＜３＞のいずれか１項に記載のｎ型拡散層を有する半導体基板の製造方法。
＜５＞　前記ｎ型拡散層を有する半導体基板を酸化処理する工程を更に含む＜１＞～＜４＞のいずれか１項に記載のｎ型拡散層を有する半導体基板の製造方法。
＜６＞　前記酸化処理が、ドライ酸化及びウェット酸化からなる群より選択される少なくとも１種である＜１＞～＜５＞のいずれか１項に記載のｎ型拡散層を有する半導体基板の製造方法。
＜７＞　前記半導体基板がシリコン基板である＜１＞～＜６＞のいずれか１項に記載のｎ型拡散層を有する半導体基板の製造方法。
＜８＞　＜１＞～＜７＞のいずれか１項に記載のｎ型拡散層を有する半導体基板の製造方法により製造されるｎ型拡散層を有する半導体基板に、電極を形成する工程を含む、太陽電池素子の製造方法。 Means for solving the above problems include the following embodiments.
<1> A semiconductor substrate to which at least part of an n-type diffusion layer forming composition containing glass particles containing a donor element and a dispersion medium is applied at a gas flow rate of 3 mm / second to 60 mm / second. A method for manufacturing a semiconductor substrate having an n-type diffusion layer, comprising a step of heat-treating under conditions that are seconds.
<2> The method for producing a semiconductor substrate having an n-type diffusion layer according to <1>, further including a step of removing the glass layer formed on the semiconductor substrate by etching after the heat treatment step.
<3> The method for producing a semiconductor substrate having an n-type diffusion layer according to <1> or <2>, wherein the donor element is at least one selected from the group consisting of P (phosphorus) and Sb (antimony) .
<4> Glass particles containing the donor element are
At least one donor element-containing material selected from the group consisting of P 2 O 3 , P 2 O 5 and Sb 2 O 3 , and SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, <1> to <3> containing at least one glass component material selected from the group consisting of CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5 , SnO, ZrO 2 and MoO 3 The manufacturing method of the semiconductor substrate which has an n type diffused layer of any one of these.
<5> The method for producing a semiconductor substrate having an n-type diffusion layer according to any one of <1> to <4>, further including a step of oxidizing the semiconductor substrate having the n-type diffusion layer.
<6> Production of a semiconductor substrate having an n-type diffusion layer according to any one of <1> to <5>, wherein the oxidation treatment is at least one selected from the group consisting of dry oxidation and wet oxidation Method.
<7> The method for producing a semiconductor substrate having an n-type diffusion layer according to any one of <1> to <6>, wherein the semiconductor substrate is a silicon substrate.
<8> A step of forming an electrode on a semiconductor substrate having an n-type diffusion layer manufactured by the method for manufacturing a semiconductor substrate having an n-type diffusion layer according to any one of <1> to <7>. The manufacturing method of a solar cell element.
　本発明によれば、半導体基板の所望の部位にｎ型拡散層を形成することを可能とし、ｐ型半導体を形成するために使用されるｐ型ドーパントがｎ型半導体領域に拡散するのを防止するバリア層を形成可能であり、且つシート抵抗のバラつきの低減が可能である、ｎ型拡散層を有する半導体基板の製造方法及び太陽電池素子の製造方法が提供される。 According to the present invention, it is possible to form an n-type diffusion layer in a desired portion of a semiconductor substrate and prevent the p-type dopant used for forming the p-type semiconductor from diffusing into the n-type semiconductor region. There are provided a method for manufacturing a semiconductor substrate having an n-type diffusion layer and a method for manufacturing a solar cell element, which can form a barrier layer and reduce variation in sheet resistance.
本実施の形態の太陽電池素子の製造方法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 method of the solar cell element of this Embodiment.
　以下、本発明について詳細に説明する。ただし、本発明は以下の実施形態に限定されるものではない。以下の実施形態において、その構成要素（要素ステップ等も含む）は、特に明示した場合、原理的に明らかに必須であると考えられる場合等を除き、必須ではない。数値及びその範囲についても同様であり、本発明を制限するものではない。
　本明細書において「工程」との語には、他の工程から独立した工程に加え、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目的が達成されれば、当該工程も含まれる。
　本明細書において「～」を用いて示された数値範囲には、「～」の前後に記載される数値がそれぞれ最小値及び最大値として含まれる。
　本明細書において組成物中の各成分の含有率は、組成物中に各成分に該当する物質が複数種存在する場合、特に断らない限り、組成物中に存在する当該複数種の物質の合計の含有率を意味する。
　本明細書において組成物中の各成分の粒子径は、組成物中に各成分に該当する粒子が複数種存在する場合、特に断らない限り、組成物中に存在する当該複数種の粒子の混合物についての値を意味する。
　本明細書において「層」との語には、当該層が存在する領域を観察したときに、当該領域の全体に形成されている場合に加え、当該領域の一部にのみ形成されている場合も含まれる。 Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps and the like) are not essential unless explicitly specified, unless otherwise clearly considered essential in principle. The same applies to numerical values and ranges thereof, and the present invention is not limited thereto.
In this specification, the term “process” includes a process that is independent of other processes and includes the process if the purpose of the process is achieved even if it cannot be clearly distinguished from the other processes. It is.
In the present specification, numerical values indicated by using “to” include numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In the present specification, the content of each component in the composition is the sum of the plurality of substances present in the composition unless there is a specific indication when there are a plurality of substances corresponding to each component in the composition. It means the content rate of.
In the present specification, the particle diameter of each component in the composition is a mixture of the plurality of types of particles present in the composition unless there is a specific indication when there are a plurality of types of particles corresponding to each component in the composition. Means the value of.
In this specification, the term “layer” refers to the case where the layer is formed only in a part of the region in addition to the case where the layer is formed over the entire region. Is also included.
　本実施の形態のｎ型拡散層を有する半導体基板の製造方法は、ドナー元素を含むガラス粒子と、分散媒と、を含有するｎ型拡散層形成組成物（以下、「特定ｎ型拡散層形成組成物」とも称する）が少なくとも一部に付与された半導体基板を、ガスの流量が線速度で３ｍｍ／秒～６０ｍｍ／秒である条件下で熱処理する工程（以下、「熱処理工程」とも称する）を含む。ｎ型拡散層を有する半導体基板の製造方法は、更に必要に応じてその他の工程を有していてもよい。 The method for manufacturing a semiconductor substrate having an n-type diffusion layer according to the present embodiment includes an n-type diffusion layer forming composition containing glass particles containing a donor element and a dispersion medium (hereinafter referred to as “specific n-type diffusion layer formation”). A step of heat-treating a semiconductor substrate provided with at least a part of the composition (also referred to as “composition”) under a condition that the gas flow rate is 3 mm / second to 60 mm / second in linear velocity (hereinafter also referred to as “heat treatment step”). including. The method for manufacturing a semiconductor substrate having an n-type diffusion layer may further include other steps as necessary.
　ｎ型拡散層を有する半導体基板の製造方法において、熱処理工程における「線速度」とは、単位時間にガスが進む距離を意味する。線速度の値は、使用する拡散炉の条件（例えば、石英製チューブの設計値（直径））に依存しない値である。例えば、拡散炉の石英製チューブの直径が２５２ｍｍであり、かつ線速度が１０ｍｍ／秒であると、前記石英製チューブの直径から算出される断面積に前記線速度を乗じて単位時間当たりの流量が求まり、この場合、前記石英製チューブ内には毎分３０Ｌのガスが流れることになる。前期石英製チューブの直径を２５２ｍｍとしたまま、線速度を３ｍｍ／秒あるいは６０ｍｍ／秒とすれば、ガス流量はそれぞれ毎分９Ｌあるいは毎分１８０Ｌとなる。 In the method of manufacturing a semiconductor substrate having an n-type diffusion layer, “linear velocity” in the heat treatment step means a distance that the gas travels per unit time. The value of the linear velocity is a value that does not depend on the conditions of the diffusion furnace to be used (for example, the design value (diameter) of the quartz tube). For example, when the diameter of the quartz tube of the diffusion furnace is 252 mm and the linear velocity is 10 mm / second, the flow rate per unit time is obtained by multiplying the cross-sectional area calculated from the diameter of the quartz tube by the linear velocity. In this case, 30 L of gas flows in the quartz tube per minute. If the linear velocity is 3 mm / second or 60 mm / second with the diameter of the quartz tube made of 252 mm, the gas flow rate is 9 L / min or 180 L / min, respectively.
　ｎ型拡散層を有する半導体基板の製造方法は、上記構成を有することにより、ｐ型ドーパントがｎ型半導体領域に拡散するのを防ぐバリア層として充分な厚さの酸化膜を形成することができる。その理由は明らかではないが、下記のように推察される。
　特定ｎ型拡散層形成組成物は、ドナー元素を含むガラス粒子及び分散媒を含有する。ガラス粒子は、熱処理の際の高温において軟化する。軟化したガラス粒子からドナー元素が半導体基板へ移動し、ｎ型半導体領域を形成し、ｎ型半導体領域上にはガラス粒子中のガラス成分によりガラス層が形成される。その後、フッ酸等によるエッチングでガラス層を除去することによって、半導体基板上のｎ型半導体領域が露出する。露出したｎ型半導体領域は、ドナー元素が拡散されていない領域と比較して酸化されやすい。そこで、酸化処理を行うことによって、ｎ型半導体領域上にはドナー元素が拡散されていない領域と比較し、酸化膜が厚く形成される。この酸化膜が、後の工程でｐ型ドーパントを拡散する際のバリア膜として機能する。
　また、ガスの流量を３ｍｍ／秒～６０ｍｍ／秒とすることにより、ｎ型拡散層形成組成物に含まれる分散媒が効率良く飛散し、ガラス層が形成されやすくなる。更に、形成されるガラス層中の分散媒の残存率を低減することができ、製造されたｎ型拡散層を有する半導体基板及び太陽電池素子のシート抵抗のバラつきが低減される。 The manufacturing method of a semiconductor substrate having an n-type diffusion layer can form an oxide film having a sufficient thickness as a barrier layer that prevents the p-type dopant from diffusing into the n-type semiconductor region by having the above structure. . The reason is not clear, but is presumed as follows.
The specific n-type diffusion layer forming composition contains glass particles containing a donor element and a dispersion medium. Glass particles soften at high temperatures during heat treatment. The donor element moves from the softened glass particles to the semiconductor substrate to form an n-type semiconductor region, and a glass layer is formed on the n-type semiconductor region by the glass component in the glass particles. Then, the n-type semiconductor region on the semiconductor substrate is exposed by removing the glass layer by etching with hydrofluoric acid or the like. The exposed n-type semiconductor region is more easily oxidized than a region where the donor element is not diffused. Therefore, by performing the oxidation treatment, an oxide film is formed thicker on the n-type semiconductor region than the region where the donor element is not diffused. This oxide film functions as a barrier film when the p-type dopant is diffused in a later step.
In addition, by setting the gas flow rate to 3 mm / second to 60 mm / second, the dispersion medium contained in the n-type diffusion layer forming composition is efficiently scattered and the glass layer is easily formed. Furthermore, the residual ratio of the dispersion medium in the glass layer to be formed can be reduced, and variations in sheet resistance of the manufactured semiconductor substrate and solar cell element having the n-type diffusion layer are reduced.
　以下、ｎ型拡散層を有する半導体基板の製造方法について詳細に説明する。
　まず、特定ｎ型拡散層形成組成物について説明し、次に、これらのｎ型拡散層形成組成物を用いる半導体基板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。 Hereinafter, a method for manufacturing a semiconductor substrate having an n-type diffusion layer will be described in detail.
First, a specific n-type diffusion layer forming composition will be described, and then a semiconductor substrate manufacturing method and a solar cell element manufacturing method using these n-type diffusion layer forming compositions will be described.
＜特定ｎ型拡散層形成組成物＞
　特定ｎ型拡散層形成組成物は、ドナー元素を含むガラス粒子（以下、「ガラス粒子」とも称する）と、分散媒と、を含有する。特定ｎ型拡散層形成組成物は、塗布性等を考慮して、その他の成分を必要に応じて含有してもよい。
　ここで、ｎ型拡散層形成組成物とは、ドナー元素を含有し、半導体基板に付与した後にこのドナー元素を熱拡散することで、半導体基板のｎ型拡散層形成組成物を付与した部位にｎ型拡散層を形成することが可能な材料をいう。特定ｎ型拡散層形成組成物を用いることで、特定ｎ型拡散層形成組成物を付与した半導体基板の所望の部位に選択的にｎ型拡散層を形成でき、半導体基板の裏面、側面等に不要なｎ型拡散層を形成しないことが容易となる。
　従って、特定ｎ型拡散層形成組成物を適用すれば、従来より広く採用されている気相反応法で行われている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傾向にある。また、半導体基板の裏面に形成された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、裏面電極の材質、形状及び厚さ等が制限されず、適用する製造方法、材質、形状等の選択肢が広がる。また、詳細は後述するが、裏面電極の厚さに起因した半導体基板内の内部応力の発生が抑えられ、半導体基板の反りも抑えられる傾向にある。 <Specific n-type diffusion layer forming composition>
The specific n-type diffusion layer forming composition contains glass particles containing a donor element (hereinafter also referred to as “glass particles”) and a dispersion medium. The specific n-type diffusion layer forming composition may contain other components as required in consideration of coating properties and the like.
Here, the n-type diffusion layer forming composition contains a donor element, and is applied to the semiconductor substrate, and then thermally diffuses the donor element, so that the n-type diffusion layer forming composition of the semiconductor substrate is applied to the site. A material that can form an n-type diffusion layer. By using the specific n-type diffusion layer forming composition, an n-type diffusion layer can be selectively formed in a desired portion of the semiconductor substrate to which the specific n-type diffusion layer forming composition is applied, and on the back surface, side surface, etc. of the semiconductor substrate It becomes easy not to form an unnecessary n-type diffusion layer.
Therefore, if the specific n-type diffusion layer forming composition is applied, the side etching step performed by the gas phase reaction method that has been widely adopted conventionally becomes unnecessary, and the process tends to be simplified. Further, there is no need to convert the n-type diffusion layer formed on the back surface of the semiconductor substrate into a p + -type diffusion layer. Therefore, the method for forming the p + -type diffusion layer on the back surface, the material, shape, thickness, and the like of the back electrode are not limited, and options for the manufacturing method, material, shape, and the like to be applied are expanded. Moreover, although mentioned later for details, generation | occurrence | production of the internal stress in the semiconductor substrate resulting from the thickness of a back surface electrode is suppressed, and it exists in the tendency for the curvature of a semiconductor substrate to be suppressed.
　尚、特定ｎ型拡散層形成組成物に含有されるガラス粒子は熱処理により溶融し、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、リン酸塩含有の溶液を塗布する方法等においてもｎ型拡散層の上にガラス層が形成される。よって、本実施の形態の方法において形成されたガラス層は、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。従って、特定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傾向にある。 In addition, the glass particles contained in the specific n-type diffusion layer forming composition are melted by heat treatment to form a glass layer on the n-type diffusion layer. However, a glass layer is formed on the n-type diffusion layer even in a conventional gas phase reaction method, a method of applying a phosphate-containing solution, or the like. Therefore, the glass layer formed in the method of the present embodiment can be removed by etching as in the conventional method. Therefore, the specific n-type diffusion layer forming composition tends not to generate unnecessary products and increase the number of steps as compared with the conventional method.
　また、ガラス粒子は熱処理中でも揮散しないため、揮散ガスの発生によって半導体基板の表面のみでなく、半導体基板の裏面又は側面にまでｎ型拡散層が形成されるということが防止される傾向にある。この理由として例えば、ドナー成分がガラス粒子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。 Further, since the glass particles are not volatilized even during the heat treatment, the generation of the volatilized gas tends to prevent the n-type diffusion layer from being formed not only on the surface of the semiconductor substrate but also on the back surface or side surface of the semiconductor substrate. For this reason, for example, it is considered that the donor component is not easily volatilized because it is bonded to the element in the glass particle or is taken into the glass.
　ガラス粒子に含まれるドナー元素とは、ドーピングにより半導体基板中に拡散してｎ型拡散層を形成することが可能な元素を意味する。ドナー元素としては、第１５族の元素が使用できる。第１５族の元素としては、例えば、Ｐ（リン）、Ｓｂ（アンチモン）及びＡｓ（ヒ素）が挙げられる。安全性、ガラス化の容易さ等の観点からは、ドナー元素が、Ｐ（リン）及びＳｂ（アンチモン）からなる群より選択される少なくとも１種であることが好ましい。 The donor element contained in the glass particles means an element that can be diffused into the semiconductor substrate by doping to form an n-type diffusion layer. As the donor element, a Group 15 element can be used. Examples of the Group 15 element include P (phosphorus), Sb (antimony), and As (arsenic). From the viewpoint of safety, ease of vitrification, etc., the donor element is preferably at least one selected from the group consisting of P (phosphorus) and Sb (antimony).
　ドナー元素をガラス粒子に導入するために用いるドナー元素含有物質としては、例えば、Ｐ２Ｏ３、Ｐ２Ｏ５、Ｓｂ２Ｏ３、Ｂｉ２Ｏ３、及びＡｓ２Ｏ３が挙げられ、Ｐ２Ｏ３、Ｐ２Ｏ５及びＳｂ２Ｏ３からなる群より選択される少なくとも１種が好ましい。 Examples of the donor element-containing material used for introducing the donor element into the glass particles include P 2 O 3 , P 2 O 5 , Sb 2 O 3 , Bi 2 O 3 , and As 2 O 3. At least one selected from the group consisting of 2 O 3 , P 2 O 5 and Sb 2 O 3 is preferable.
　ガラス粒子は、必要に応じてその成分比率を調整することによって、溶融温度、軟化点、ガラス転移点、化学的耐久性等を制御することが可能である。この観点から、ガラス粒子は、更に以下に記すような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、例えば、ＳｉＯ２、Ｋ２Ｏ、Ｎａ２Ｏ、Ｌｉ２Ｏ、ＢａＯ、ＳｒＯ、ＣａＯ、ＭｇＯ、ＢｅＯ、ＺｎＯ、ＰｂＯ、ＣｄＯ、ＳｎＯ、ＷＯ３、ＭｏＯ３、ＭｎＯ、Ｌａ２Ｏ３、Ｎｂ２Ｏ５、Ｔａ２Ｏ５、Ｙ２Ｏ３、ＴｉＯ２、ＺｒＯ２、ＧｅＯ２、ＴｅＯ２、及びＬｕ２Ｏ３が挙げられる。
　ガラス粒子は、ＳｉＯ２、Ｋ２Ｏ、Ｎａ２Ｏ、Ｌｉ２Ｏ、ＢａＯ、ＳｒＯ、ＣａＯ、ＭｇＯ、ＢｅＯ、ＺｎＯ、ＰｂＯ、ＣｄＯ、ＳｎＯ、ＺｒＯ２、ＷＯ３、ＭｏＯ３及びＭｎＯからなる群より選択される少なくとも１種をガラス成分物質として含むことが好ましい。ガラス粒子は、ＳｉＯ２、Ｋ２Ｏ、Ｎａ２Ｏ、Ｌｉ２Ｏ、ＢａＯ、ＳｒＯ、ＣａＯ、ＭｇＯ、ＢｅＯ、ＺｎＯ、ＰｂＯ、ＣｄＯ、Ｖ２Ｏ５、ＳｎＯ、ＺｒＯ２及びＭｏＯ３からなる群より選択される少なくとも１種をガラス成分物質として含むことがより好ましい。 The glass particles can be controlled in terms of melting temperature, softening point, glass transition point, chemical durability, and the like by adjusting the component ratio as necessary. From this viewpoint, it is preferable that the glass particles further contain a glass component substance as described below.
Examples of the glass component material include SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, WO 3 , MoO 3 , MnO, and La. 2 O 3 , 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 may be mentioned.
The glass particles are made of SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, SnO, ZrO 2 , WO 3 , MoO 3 and MnO. It is preferable to include at least one selected from the glass component substances. The glass particles are composed of SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5 , SnO, ZrO 2 and MoO 3. It is more preferable that at least one selected from the above is included as a glass component substance.
　ある実施態様では、ドナー元素を含むガラス粒子は、Ｐ２Ｏ３、Ｐ２Ｏ５及びＳｂ２Ｏ３からなる群より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、Ｖ２Ｏ５、ＳｎＯ、ＺｒＯ２及びＭｏＯ３からなる群より選択される少なくとも１種のガラス成分物質と、を含有することが好ましい。 In one embodiment, the glass particles containing a donor element include at least one donor element-containing material selected from the group consisting of P 2 O 3 , P 2 O 5 and Sb 2 O 3 , and SiO 2 , K 2 O. , Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5 , SnO, ZrO 2, and MoO 3. It is preferable to contain a substance.
　本発明におけるドナー元素を含むガラス粒子の具体例としては、例えば、Ｐ２Ｏ５－ＳｉＯ２系ガラス粒子、Ｐ２Ｏ５－Ｋ２Ｏ系ガラス粒子、Ｐ２Ｏ５－Ｎａ２Ｏ系ガラス粒子、Ｐ２Ｏ５－Ｌｉ２Ｏ系ガラス粒子、Ｐ２Ｏ５－ＢａＯ系ガラス粒子、Ｐ２Ｏ５－ＳｒＯ系ガラス粒子、Ｐ２Ｏ５－ＣａＯ系ガラス粒子、Ｐ２Ｏ５－ＭｇＯ系ガラス粒子、Ｐ２Ｏ５－ＢｅＯ系ガラス粒子、Ｐ２Ｏ５－ＺｎＯ系ガラス粒子、Ｐ２Ｏ５－ＣｄＯ系ガラス粒子、Ｐ２Ｏ５－ＰｂＯ系ガラス粒子、Ｐ２Ｏ５－ＳｎＯ系ガラス粒子、Ｐ２Ｏ５－ＧｅＯ２系ガラス粒子、Ｐ２Ｏ５－Ｓｂ２Ｏ３系ガラス粒子、Ｐ２Ｏ５－ＴｅＯ２系ガラス粒子、Ｐ２Ｏ５－Ａｓ２Ｏ３系ガラス粒子等のＰ２Ｏ５系ガラス粒子、及びＳｂ２Ｏ３系ガラス粒子が挙げられる。
　上記では２成分を含む複合ガラスを例示した。ガラス粒子は、所望に応じて、Ｐ２Ｏ５－ＳｉＯ２－ＣａＯ等の３種類以上の成分を含む複合ガラス粒子であってもよい。 Specific examples of the glass particles containing a donor element in the present invention include, for example, P 2 O 5 —SiO 2 glass particles, P 2 O 5 —K 2 O glass particles, and P 2 O 5 —Na 2 O glass. Particles, P 2 O 5 —Li 2 O based glass particles, P 2 O 5 —BaO based glass particles, P 2 O 5 —SrO based glass particles, P 2 O 5 —CaO based glass particles, P 2 O 5 —MgO Glass particles, P 2 O 5 —BeO glass particles, P 2 O 5 —ZnO glass particles, P 2 O 5 —CdO glass particles, P 2 O 5 —PbO glass particles, P 2 O 5 —SnO system glass particles, P 2 O 5 -GeO 2 glass particles, P 2 O 5 -Sb 2 O 3 based glass particles, P 2 O 5 -TeO 2 glass particles, P 2 O 5 -As 2 O 3 based glass P 2 O 5 based glass particles, etc. Scan particles, and Sb 2 O 3 based glass particles and the like.
In the above, the composite glass containing two components was illustrated. The glass particles may be composite glass particles containing three or more kinds of components such as P 2 O 5 —SiO 2 —CaO as desired.
　ガラス粒子中のガラス成分物質の含有率は、溶融温度、軟化点、ガラス転移点、化学的耐久性等を考慮して適宜設定することが望ましい。ガラス成分物質の含有率は、例えば、０．１質量％～９５質量％であることが好ましく、０．５質量％～９０質量％であることがより好ましい。 The content of the glass component substance in the glass particles is desirably set as appropriate in consideration of the melting temperature, softening point, glass transition point, chemical durability, and the like. For example, the content of the glass component substance is preferably 0.1% by mass to 95% by mass, and more preferably 0.5% by mass to 90% by mass.
　ガラス粒子の軟化点は、熱処理の際の特定ｎ型拡散層形成組成物の成分の拡散性、液だれ等の観点から、例えば、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 particles is preferably 200 ° C. to 1000 ° C., for example, from 300 ° C. to 900 ° C. from the viewpoint of diffusibility of the components of the specific n-type diffusion layer forming composition during heat treatment, dripping, etc. It is more preferable that
　ガラス粒子の形状としては、略球状、扁平状、ブロック状、板状、鱗片状等が挙げられる。ｎ型拡散層形成組成物とした場合の半導体基板への塗布性、均一拡散性等の点から、ガラス粒子は略球状、扁平状又は板状であることが好ましい。
　ガラス粒子の平均粒径は、例えば、１００μｍ以下であることが好ましい。１００μｍ以下の平均粒径を有するガラス粒子を用いる場合、平滑な組成物層が得られやすい。ガラス粒子の平均粒径は、例えば、５０μｍ以下であることが好ましく、３０μｍ以下であることが更に好ましい。なお、下限は特に制限されないが、例えば、０．０１μｍ以上であることが好ましい。
　ここで、ガラス粒子の平均粒径は、体積平均粒子径を表し、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。体積平均粒子径は、体積基準の粒子径分布において小径側からの累積が５０％となるときの値（Ｄ５０）とする。 Examples of the shape of the glass particles include a substantially spherical shape, a flat shape, a block shape, a plate shape, and a scale shape. The glass particles are preferably substantially spherical, flat or plate-like from the viewpoint of application properties to a semiconductor substrate, uniform diffusibility, and the like when an n-type diffusion layer forming composition is used.
The average particle size of the glass particles is preferably 100 μm or less, for example. When glass particles having an average particle size of 100 μm or less are used, a smooth composition layer is easily obtained. The average particle size of the glass particles is, for example, preferably 50 μm or less, and more preferably 30 μm or less. The lower limit is not particularly limited, but is preferably 0.01 μm or more, for example.
Here, the average particle diameter of the glass particles represents a volume average particle diameter, and can be measured by a laser scattering diffraction particle size distribution measuring apparatus or the like. The volume average particle diameter is a value (D 50 ) when the accumulation from the small diameter side is 50% in the volume-based particle diameter distribution.
　ドナー元素を含むガラス粒子は、以下の手順で作製することができる。
　最初に、ドナー元素を含むガラス粒子の原料を秤量し、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、金、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。この際、融液が充分混合されるよう攪拌することが望ましい。加熱温度は、ドナー元素含有物質がガラス成分物質と結合する温度であれば、特に限定されない。例えば、ガラス成分物質としてＳｉＯ２を使用する場合、ガラス成分物質及びドナー元素含有物質を含む混合物を１４００℃以上に加熱して、ドナー元素を含むガラス粒子を製造することが好ましい。
　続いて、得られた融液を金属板等の上に流し出して融液をガラス化する。次に、得られたガラスを粉砕して粒子状とする。粉砕は、例えば、スタンプミル、ジェットミル、ビーズミル、ボールミル等を用いる公知の方法が適用できる。 Glass particles containing a donor element can be produced by the following procedure.
First, a glass particle raw material containing a donor element is weighed and filled in a crucible. Examples of the material for the crucible include platinum, platinum-rhodium, gold, iridium, alumina, quartz, carbon, and the like, which 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 so that the melt is sufficiently mixed. The heating temperature is not particularly limited as long as it is a temperature at which the donor element-containing material is combined with the glass component material. For example, when SiO 2 is used as the glass component substance, it is preferable to produce a glass particle containing the donor element by heating a mixture containing the glass component substance and the donor element-containing substance to 1400 ° C. or higher.
Subsequently, the obtained melt is poured onto a metal plate or the like to vitrify the melt. Next, the obtained glass is pulverized into particles. For the pulverization, for example, a known method using a stamp mill, a jet mill, a bead mill, a ball mill or the like can be applied.
　ｎ型拡散層形成組成物中のドナー元素を含むガラス粒子の含有率は、塗布性、ドナー元素の拡散性等を考慮して決定される。一般には、ｎ型拡散層形成組成物中のガラス粒子の含有率は、例えば、ｎ型拡散層形成組成物の全質量に対して、例えば、０．１質量％～９５質量％であることが好ましく、１質量％～９０質量％であることがより好ましく、２質量％～８０質量％であることが更に好ましい。 The content ratio of the glass particles containing the donor element in the n-type diffusion layer forming composition is determined in consideration of the coating property, the diffusibility of the donor element, and the like. In general, the glass particle content in the n-type diffusion layer forming composition is, for example, 0.1% by mass to 95% by mass with respect to the total mass of the n-type diffusion layer forming composition. It is preferably 1% by mass to 90% by mass, more preferably 2% by mass to 80% by mass.
　ｎ型拡散層形成組成物中のドナー元素を含むガラス粒子の含有率は、ｎ型拡散層形成組成物の不揮発成分の総量に対して、例えば、０．１質量％～９９質量％であることが好ましく、１質量％～９５質量％であることがより好ましく、２質量％～９０質量％であることが更に好ましい。
　ここで、「不揮発成分」とは、後述する溶剤等の揮発する物質以外のｎ型拡散層形成組成物中の成分を意味する。ここで、揮発する物質とは、沸点が大気圧下で２５０℃以下である物質のことを意味する。 The content of the glass particles containing the donor element in the n-type diffusion layer forming composition is, for example, 0.1% by mass to 99% by mass with respect to the total amount of nonvolatile components in the n-type diffusion layer forming composition. It is preferably 1% by mass to 95% by mass, more preferably 2% by mass to 90% by mass.
Here, the “nonvolatile component” means a component in the n-type diffusion layer forming composition other than a volatile substance such as a solvent described later. Here, the volatile substance means a substance having a boiling point of 250 ° C. or lower under atmospheric pressure.
　次に、分散媒について説明する。
　分散媒とは、特定ｎ型拡散層形成組成物中において上記ガラス粒子を分散させる媒体である。分散媒としては、バインダー、溶剤等が使用される。 Next, the dispersion medium will be described.
The dispersion medium is a medium in which the glass particles are dispersed in the specific n-type diffusion layer forming composition. As the dispersion medium, a binder, a solvent, or the like is used.
　バインダーとしては、例えば、ジメチルアミノエチル（メタ）アクリレートポリマー、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（メタ）アクリル酸類、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、グアーガム及びグアーガム誘導体、スクレログルカン、トラガカント、デキストリン誘導体、アクリル酸樹脂、アクリル酸エステル樹脂、ブタジエン樹脂、スチレン樹脂、これらの共重合体、二酸化ケイ素が挙げられる。バインダーは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 dimethylaminoethyl (meth) acrylate polymer, polyvinyl alcohol, polyacrylamides, polyvinylamides, polyvinylpyrrolidone, poly (meth) acrylic acids, polyethylene oxides, polysulfonic acid, acrylamide alkyl sulfonic acid, and cellulose ether. , Cellulose derivatives, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, gelatin, starch and starch derivatives, sodium alginate, xanthan, guar gum and guar gum derivatives, scleroglucan, tragacanth, dextrin derivatives, acrylic acid resin, acrylate resin, butadiene Examples thereof include resins, styrene resins, copolymers thereof, and silicon dioxide. A binder is used individually by 1 type or in combination of 2 or more types.
　バインダーの重量平均分子量は特に制限されず、特定ｎ型拡散層形成組成物としての所望の粘度を考慮して、適宜調整することが望ましい。 The weight average molecular weight of the binder is not particularly limited, and it is desirable to appropriately adjust in consideration of a desired viscosity as the specific n-type diffusion layer forming composition.
　溶剤としては、例えば、アセトン、メチルエチルケトン、メチル－ｎ－プロピルケトン、メチルイソプロピルケトン、メチル－ｎ－ブチルケトン、メチルイソブチルケトン、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、ジイソブチルケトン、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、γ－ブチロラクトン、γ－バレロラク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－ジ－ｎ－プロピルエーテル、ジイソプロピルエーテル、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モノ－ｎ－プロピルエーテル、ジエチレングリコールメチルモノ－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モノ－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モノ－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モノ－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モノ－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モノ－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モノ－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モノ－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モノ－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モノ－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モノ－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モノ－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、酢酸イソプロピル、酢酸ｎ－ブチル、酢酸イソブチル、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モノメチルエーテル、酢酸ジエチレングリコールモノエチルエーテル、酢酸ジエチレングリコールモノ－ｎ－ブチルエーテル、酢酸ジプロピレングリコールモノメチルエーテル、酢酸ジプロピレングリコールモノエチルエーテル、ジ酢酸グリコール、酢酸メトキシトリエチレングリコール、プロピオン酸エチル、プロピオン酸ｎ－ブチル、プロピオン酸イソアミル、シュウ酸ジエチル、シュウ酸ジ－ｎ－ブチル等のエステル系溶媒、エチレングリコールメチルエーテルプロピオネート、エチレングリコールエチルエーテルプロピオネート、エチレングリコールメチルエーテルアセテート、エチレングリコールエチルエーテルアセテート、ジエチレングリコールメチルエーテルアセテート、ジエチレングリコールエチルエーテルアセテート、ジエチレングリコール－ｎ－ブチルエーテルアセテート、プロピレングリコールメチルエーテルアセテート、プロピレングリコールエチルエーテルアセテート、プロピレングリコールプロピルエーテルアセテート、ジプロピレングリコールメチルエーテルアセテート、ジプロピレングリコールエチルエーテルアセテート等のエーテルアセテート系溶剤、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、Ｎ，Ｎ－ジメチルスルホキシド、メタノール、エタノール、ｎ－プロパノール、イソプロパノール、ｎ－ブタノール、イソブタノール、ｓｅｃ－ブタノール、ｔ－ブタノール、ｎ－ペンタノール、イソペンタノール、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、テルピネオール等のアルコール系溶剤、エチレングリコールメチルエーテル、エチレングリコールエチルエーテル、エチレングリコールモノフェニルエーテル、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノエチルエーテル、ジエチレングリコールモノ－ｎ－ブチルエーテル、ジエチレングリコールモノ－ｎ－ヘキシルエーテル、エトキシトリグリコール、テトラエチレングリコールモノ－ｎ－ブチルエーテル、プロピレングリコールモノメチルエーテル、ジプロピレングリコールモノメチルエーテル、ジプロピレングリコールモノエチルエーテル、トリプロピレングリコールモノメチルエーテル等のエーテル系溶剤、乳酸メチル、乳酸エチル、乳酸ｎ－ブチル、乳酸ｎ－アミル等のエステル系溶剤、水等が挙げられる。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 solvent include 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, diethyl ketone, and dipropyl. Ketone solvents such as ketone, diisobutylketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, γ-butyrolactone, γ-valerolactone, diethyl ether, methyl ethyl ether, Methyl-n-di-n-propyl ether, diisopropyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethylene glycol dimethyl ether, ethyl Lenglycol diethyl ether, 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 mono-n-propyl ether, diethylene glycol methyl mono-n-butyl ether, diethylene glycol di -N-propyl ether, diethylene glycol di-n-butyl ether, diethylene glycol methyl mono-n-hexyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol methyl mono-n-butyl ether, Triech Glycol di-n-butyl ether, triethylene glycol methyl mono-n-hexyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol methyl ethyl ether, tetraethylene glycol methyl mono-n-butyl ether, diethylene glycol di- n-butyl ether, tetraethylene glycol methyl mono-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, dipropylene glycol methyl mono-n-butyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl mono-n-hexyl ether, tripropylene Glycol dimethyl ether, tripropylene glycol diethyl ether, tripropylene glycol methyl ethyl ether, tripropylene glycol methyl mono-n-butyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol methyl mono-n-hexyl ether, tetrapropylene glycol dimethyl ether , Tetrapropylene glycol diethyl ether, tetrapropylene glycol methyl ethyl Ether solvents such as ether, tetrapropylene glycol methyl mono-n-butyl ether, dipropylene glycol di-n-butyl ether, tetrapropylene glycol methyl mono-n-hexyl ether, tetrapropylene glycol di-n-butyl ether, methyl acetate, acetic acid Ethyl, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, acetic acid 2 -Ethylhexyl, 2- (2-butoxyethoxy) ethyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, nonyl acetate, methyl acetoacetate, ethyl acetoacetate, diethylene glycol monomethyl acetate Ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate, methoxytriethylene glycol acetate, ethyl propionate, n-butyl propionate Ester solvents such as isoamyl propionate, diethyl oxalate, di-n-butyl oxalate, ethylene glycol methyl ether propionate, ethylene glycol ethyl ether propionate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, Diethylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, diethylene Recall-n-butyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, dipropylene glycol methyl ether acetate, dipropylene glycol ethyl ether acetate and other ether acetate solvents, acetonitrile, N-methyl Pyrrolidinone, N-ethylpyrrolidinone, N-propylpyrrolidinone, N-butylpyrrolidinone, N-hexylpyrrolidinone, N-cyclohexylpyrrolidinone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-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, sec-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n-nonyl alcohol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl Alcohol, phenol, cyclohexanol, methylcyclohexanol, benzyl alcohol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, diethylene glycol, dipro Alcohol solvents such as lenglycol, triethylene glycol, tripropylene glycol, terpineol, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, Ether solvents such as 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, Methyl lactate, ethyl lactate , Lactate n- butyl, ester solvents such as lactic acid n- amyl, water and the like. These are used singly or in combination of two or more.
　特定ｎ型拡散層形成組成物中の分散媒の含有率は、塗布性、ドナー濃度等を考慮して決定される。特定ｎ型拡散層形成組成物の粘度は、塗布性の観点からは、例えば、１０ｍＰａ・Ｓ～１００００００ｍＰａ・Ｓであることが好ましく、５０ｍＰａ・Ｓ～５０００００ｍＰａ・Ｓであることがより好ましい。 The content of the dispersion medium in the specific n-type diffusion layer forming composition is determined in consideration of coating properties, donor concentration, and the like. The viscosity of the specific n-type diffusion layer forming composition is, for example, preferably from 10 mPa · S to 1000000 mPa · S, and more preferably from 50 mPa · S to 500000 mPa · S, from the viewpoint of applicability.
　更に、特定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、金属が挙げられる。
　ｎ型拡散層形成組成物は、半導体基板上に付与され、高温で熱処理されることでｎ型拡散層を形成し、その際にｎ型拡散層の表面にガラス層が形成される。このガラス層はエッチングにより除去することができる。しかし、形成されるガラスの種類によっては除去し難い場合がある。その場合に、ガラス層と結晶化しやすいＡｌ、Ａｇ、Ｍｎ、Ｃｕ、Ｆｅ、Ｚｎ、Ｓｉ等の金属をｎ型拡散層形成組成物に添加しておくことにより、エッチングの際にガラスを除去し易くなる傾向がある。これらのなかでも、Ａｌ、Ａｇ、Ｓｉ、Ｃｕ、Ｆｅ、Ｚｎ及びＭｎからなる群より選択される少なくとも１種を用いることが好ましく、Ａｌ、Ａｇ、Ｓｉ及びＺｎからなる群より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を用いることが特に好ましい。 Furthermore, the specific n-type diffusion layer forming composition may contain other additives. Examples of other additives include metals.
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, and at that time, a glass layer is formed on the surface of the n-type diffusion layer. This glass layer can be removed by etching. However, it may be difficult to remove depending on the type of glass formed. In that case, the glass is removed during the etching by adding a metal such as Al, Ag, Mn, Cu, Fe, Zn, Si, which easily crystallizes with the glass layer, to the n-type diffusion layer forming composition. It tends to be easier. Among these, it is preferable to use at least one selected from the group consisting of Al, Ag, Si, Cu, Fe, Zn and Mn, and at least one selected from the group consisting of Al, Ag, Si and Zn. It is more preferable to use seeds, and it is particularly preferable to use Ag.
　特定ｎ型拡散層形成組成物は、電極形成用組成物と区別されることから、導電物質である金属を主成分とせず、金属の含有率は、ガラスの種類、金属の種類等に応じて適宜調整することが望ましい。
ｎ型拡散層形成組成物が金属を含有する場合、ｎ型拡散層形成組成物中の金属の含有率は、半導体基板のバルクライフタイムを低下させない観点から、ガラス粒子に対して、１０質量％以下であることが好ましく、７質量％以下であることがより好ましく、５質量％以下であることが更に好ましい。ｎ型拡散層形成組成物が金属を含有する場合、金属の含有率は、ガラス層の除去効率の観点からは、ガラス粒子に対して、例えば、０．０１質量％以上であることが好ましく、１質量％以上であることがより好ましく、３質量％以上であることが更に好ましい。 Since the specific n-type diffusion layer forming composition is distinguished from the electrode forming composition, the metal as a conductive material is not a main component, and the metal content depends on the type of glass, the type of metal, and the like. It is desirable to adjust appropriately.
When the n-type diffusion layer forming composition contains a metal, the content of the metal in the n-type diffusion layer forming composition is 10% by mass with respect to the glass particles from the viewpoint of not reducing the bulk lifetime of the semiconductor substrate. Is preferably 7% by mass or less, more preferably 5% by mass or less. When the n-type diffusion layer forming composition contains a metal, the metal content is preferably 0.01% by mass or more with respect to the glass particles from the viewpoint of the glass layer removal efficiency, The content is more preferably 1% by mass or more, and further preferably 3% by mass or more.
［半導体基板］
　本発明において使用される半導体基板は、特に制限されず、太陽電池素子に用いられる半導体基板を適用することができる。例えば、シリコン基板、リン化ガリウム基板、窒化ガリウム基板、ダイヤモンド基板、窒化アルミニウム基板、窒化インジウム基板、ヒ化ガリウム基板、ゲルマニウム基板、セレン化亜鉛基板、テルル化亜鉛基板、テルル化カドミウム基板、硫化カドミウム基板、リン化インジウム基板、炭化シリコン、シリコンゲルマニウム基板、及び銅インジウムセレン基板が挙げられる。シリコン基板としては、例えば、結晶シリコン基板が挙げられる。 [Semiconductor substrate]
The semiconductor substrate used in the present invention is not particularly limited, and a semiconductor substrate used for a solar cell element can be applied. For example, 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. An example of the silicon substrate is a crystalline silicon substrate.
　半導体基板は、特定ｎ型拡散層形成組成物を付与する前に、前処理することが好ましい。前処理としては、例えば、以下の工程が挙げられる。なお、以下では、特定ｎ型半導体基板を用いる場合で説明するが、ｐ型半導体基板を用いてもよい。
　ｎ型半導体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ｎ型半導体基板の表面のダメージ層を２０質量％水酸化ナトリウム水溶液で除去する。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と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。太陽電池素子は、受光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。 The semiconductor substrate is preferably pretreated before applying the specific n-type diffusion layer forming composition. Examples of the pretreatment include the following steps. In the following description, a specific n-type semiconductor substrate is used, but a p-type semiconductor substrate may be used.
An alkaline solution is applied to the n-type semiconductor substrate to remove the damaged layer, and a texture structure is obtained by etching. Specifically, the damaged layer on the surface of the n-type semiconductor substrate generated when slicing from the ingot is removed with a 20% by mass aqueous sodium hydroxide solution. Next, etching is performed with a mixed liquid of 1% by mass caustic soda and 10% by mass isopropyl alcohol to form a texture structure. The solar cell element has a texture structure on the light receiving surface side, thereby promoting a light confinement effect and increasing efficiency.
＜ｎ型拡散層を有する半導体基板の製造方法＞
［ｎ型拡散組成物層形成工程］
　本発明のｎ型拡散層を有する半導体基板の製造方法は、上記熱処理工程の前に、ドナー元素を含むガラス粒子と、分散媒と、を含有するｎ型拡散層形成組成物（以下、「特定ｎ型拡散層形成組成物」とも称する）を半導体基板の少なくとも一部に付与することにより、ｎ型拡散層形成組成物の層（以下、「ｎ型拡散組成物層」とも称する）を形成する工程（以下、「ｎ型拡散組成物層形成工程」とも称する）を含んでいてもよい。 <Manufacturing method of semiconductor substrate having n-type diffusion layer>
[N-type diffusion composition layer forming step]
The method for producing a semiconductor substrate having an n-type diffusion layer according to the present invention comprises an n-type diffusion layer forming composition (hereinafter referred to as “specific”) containing glass particles containing a donor element and a dispersion medium before the heat treatment step. The n-type diffusion layer forming composition layer (hereinafter also referred to as “n-type diffusion composition layer”) is formed by applying at least part of the semiconductor substrate. A step (hereinafter also referred to as “n-type diffusion composition layer forming step”) may be included.
　特定ｎ型拡散層形成組成物を半導体基板の少なくとも一部に付与する方法は特に限定されない。例えば、印刷法、スピンコート法、刷毛塗り、スプレー法、ドクターブレード法、ロールコート法、及びインクジェット法が挙げられる。特定ｎ型拡散層形成組成物を付与する領域は、ｎ型拡散層を形成したい領域に合わせて適宜その形状を変更できる。 The method for applying the specific n-type diffusion layer forming composition to at least a part of the semiconductor substrate is not particularly limited. For example, a printing method, a spin coating method, a brush coating, a spray method, a doctor blade method, a roll coating method, and an ink jet method can be mentioned. The shape of the region to which the specific n-type diffusion layer forming composition is applied can be appropriately changed depending on the region where the n-type diffusion layer is to be formed.
　特定ｎ型拡散層形成組成物を半導体基板の少なくとも一部に付与してｎ型拡散組成物層を形成した後、必要に応じて、ｎ型拡散組成物層を乾燥することにより、分散媒の少なくとも一部を除去してもよい。乾燥温度は特に限定されず、例えば、８０℃～３００℃程度の温度が挙げられる。例えば、ホットプレートを使用する場合は１分～１０分、乾燥機等を用いる場合は１０分～３０分程度乾燥させることができる。この乾燥条件は、特定ｎ型拡散層形成組成物の分散媒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。 After applying the specific n-type diffusion layer forming composition to at least a part of the semiconductor substrate to form the n-type diffusion composition layer, if necessary, the n-type diffusion composition layer is dried to obtain a dispersion medium. You may remove at least one part. The drying temperature is not particularly limited, and examples thereof include a temperature of about 80 ° C. to 300 ° C. For example, it can be dried 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 dispersion medium composition of the specific n-type diffusion layer forming composition, and are not particularly limited to the above conditions in the present invention.
［熱処理工程］
　熱処理工程では、ドナー元素を含むガラス粒子と、分散媒と、を含有するｎ型拡散層形成組成物が少なくとも一部に付与された半導体基板を、ガスの流量が線速度で３ｍｍ／秒～６０ｍｍ／秒である条件下で熱処理する。熱処理することにより、ｎ型半導体基板中にドナー元素が拡散し、ｎ型拡散層が形成される。更に、このｎ型拡散層の表面には、リン酸ガラス等のガラス層が形成される。 [Heat treatment process]
In the heat treatment step, a semiconductor substrate to which at least part of the composition for forming an n-type diffusion layer containing glass particles containing a donor element and a dispersion medium is applied at a gas flow rate of 3 mm / second to 60 mm at a linear velocity. The heat treatment is performed under the condition of / sec. By performing the heat treatment, the donor element diffuses into the n-type semiconductor substrate, and an n-type diffusion layer is formed. Furthermore, a glass layer such as phosphate glass is formed on the surface of the n-type diffusion layer.
　熱処理工程におけるガスの流量が線速度で３ｍｍ／秒以上であると、形成されるｎ型拡散層中に高濃度のドナー元素を拡散できる傾向にある。ガスの流量が線速度で６０ｍｍ／秒以下であると、熱処理温度のばらつきを抑制しやすく、安定した品質のｎ型拡散層が得られやすい。 When the gas flow rate in the heat treatment step is 3 mm / second or more in linear velocity, there is a tendency that a high concentration of the donor element can be diffused in the formed n-type diffusion layer. If the gas flow rate is 60 mm / sec or less in terms of linear velocity, it is easy to suppress variations in the heat treatment temperature, and a stable quality n-type diffusion layer is likely to be obtained.
　更に高濃度のドナー元素を拡散できる観点から、ガスの流量は、例えば、線速度で４ｍｍ／秒以上であることが好ましく、５ｍｍ／秒以上であることがより好ましく、６ｍｍ／秒以上であることが更に好ましい。
　熱処理温度の維持の観点から、ガスの流量は、例えば、線速度で５０ｍｍ／秒以下であることが好ましく、４０ｍｍ／秒以下であることがより好ましく、３０ｍｍ／秒以下であることが更に好ましく、２０ｍｍ／秒以下であることが特に好ましい。 Further, from the viewpoint of diffusing a high concentration of the donor element, the flow rate of the gas is, for example, preferably 4 mm / second or more, more preferably 5 mm / second or more, and 6 mm / second or more in linear velocity. Is more preferable.
From the viewpoint of maintaining the heat treatment temperature, the flow rate of the gas is, for example, preferably 50 mm / second or less, more preferably 40 mm / second or less, and further preferably 30 mm / second or less in linear velocity. It is particularly preferably 20 mm / second or less.
　熱処理温度は特に限定されず、例えば、６００℃～１２００℃が挙げられる。加熱装置内の温度のばらつきを抑制する観点からは、７００℃～１１５０℃であることが好ましく、７５０℃～１１００℃であることがより好ましい。
　熱処理時間は特に限定されず、例えば、１分～６０分が挙げられ、ｎ型拡散層を有する半導体基板及び太陽電池素子の製造の量産性の観点からは、２分～４０分であることが好ましく、３分～２５分であることがより好ましい。 The heat treatment temperature is not particularly limited, and examples thereof include 600 ° C. to 1200 ° C. From the viewpoint of suppressing temperature variations in the heating device, the temperature is preferably 700 ° C. to 1150 ° C., more preferably 750 ° C. to 1100 ° C.
The heat treatment time is not particularly limited and may be, for example, 1 minute to 60 minutes, and may be 2 minutes to 40 minutes from the viewpoint of mass productivity of manufacturing a semiconductor substrate having an n-type diffusion layer and a solar cell element. Preferably, it is 3 minutes to 25 minutes.
　熱処理工程におけるガスの種類は特に限定されず、単体ガス、化合物ガス等から選択することができる。単体ガスとしては、例えば、窒素ガス、酸素ガス、水素ガス、ヘリウムガス、ネオンガス、アルゴンガス、クリプトンガス、キセノンガス、ラドンガス、及びハロゲンガスが挙げられる。化合物ガスとしては、メタン、プロパン等の有機ガス、加熱によりガス化可能なオキシ塩化リン、三臭化ホウ素、三塩化ホウ素なども使用できる。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できる。熱処理工程におけるガスは、空気を含んでいてもよい。 The kind of gas in the heat treatment step is not particularly limited, and can be selected from a single gas, a compound gas, and the like. Examples of the single gas include nitrogen gas, oxygen gas, hydrogen gas, helium gas, neon gas, argon gas, krypton gas, xenon gas, radon gas, and halogen gas. As the compound gas, organic gases such as methane and propane, phosphorus oxychloride, boron tribromide, boron trichloride, etc. that can be gasified by heating can be used. These can be used alone or in combination of two or more. The gas in the heat treatment step may contain air.
　熱処理工程におけるガスは、厚み等のばらつきが抑制されたｎ型拡散層を半導体基板上に形成する観点からは、酸素ガスを含むことが好ましい。酸素ガスの混合比は、本発明においては特に限定されない。 The gas in the heat treatment step preferably contains oxygen gas from the viewpoint of forming an n-type diffusion layer on which variation in thickness and the like is suppressed on the semiconductor substrate. The mixing ratio of oxygen gas is not particularly limited in the present invention.
　熱処理には、公知の連続拡散炉、バッチ拡散炉等が使用できる。 For the heat treatment, a known continuous diffusion furnace, batch diffusion furnace, or the like can be used.
［エッチング工程］
　本発明のｎ型拡散層を有する半導体基板の製造方法は、上記熱処理する工程の後、半導体基板上に形成されたガラス層をエッチングにより除去する工程（以下、「エッチング工程」とも称する）を更に含んでいてもよい。例えば、熱処理工程の後、ｎ型半導体基板を常温まで冷却した後でエッチングを行うことができる。 [Etching process]
The method for manufacturing a semiconductor substrate having an n-type diffusion layer according to the present invention further includes a step of removing the glass layer formed on the semiconductor substrate by etching after the heat treatment step (hereinafter also referred to as “etching step”). May be included. For example, after the heat treatment step, the n-type semiconductor substrate can be cooled to room temperature and then etched.
　エッチングは、フッ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の、公知の方法により行うことができる。熱処理工程によりｎ型拡散層の表面に形成されるガラス層は、上記熱処理温度でガラス粒子が溶融し、それが冷却されることで形成される。このとき、冷却速度が低くなることで、結晶成分がガラス層に混在し、その後のフッ酸によるエッチングで、除去が困難となり、残渣となることがある。そのため、冷却速度は、例えば、５℃／秒～３００℃／秒の範囲であることが好ましい。冷却速度が３００℃／秒以下であると、ガラス層の表面が他の部分よりも急激に冷却されることが抑制され、ガラス層内部の冷却速度の低下が抑制され、その結果、微結晶の生成が抑制されやすくなる。また、現在流通する熱拡散炉を用いて冷却速度の制御を行う場合の工程時間を考慮すると、冷却速度は１０℃／秒～５０℃／秒であることがより好ましい。 Etching can be performed by 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. The glass layer formed on the surface of the n-type diffusion layer by the heat treatment step is formed by melting the glass particles at the above heat treatment temperature and cooling it. At this time, since the cooling rate is low, the crystal component is mixed in the glass layer, and the subsequent etching with hydrofluoric acid makes it difficult to remove and may result in a residue. Therefore, the cooling rate is preferably in the range of 5 ° C./second to 300 ° C./second, for example. When the cooling rate is 300 ° C./second or less, the surface of the glass layer is suppressed from being cooled more rapidly than the other parts, and the decrease in the cooling rate inside the glass layer is suppressed. Generation is easily suppressed. In consideration of the process time when the cooling rate is controlled using a currently distributed thermal diffusion furnace, the cooling rate is more preferably 10 ° C./second to 50 ° C./second.
　エッチングを行った後、ｎ型半導体基板を洗浄及び乾燥してもよい。 After the etching, the n-type semiconductor substrate may be washed and dried.
［酸化処理工程］
　ｎ型拡散層を有する半導体基板の製造方法は、上記ｎ型拡散層を有する半導体基板を酸化処理する工程（以下、「酸化処理工程」とも称する）を更に含んでいてもよい。酸化処理により、酸化シリコン膜等の酸化膜が形成される。酸化膜はｎ型拡散層の領域に厚く形成され、それ以外の領域には薄く形成される傾向にある。
　ｎ型拡散層の領域以外の酸化膜は、エッチングにより除去することが好ましい。その際、ｎ型拡散層の領域に形成された酸化膜の厚さもエッチングにより減少する傾向にある。従って、ｎ型拡散層の領域以外の酸化膜が充分除去された段階でエッチングを止める必要がある。ｎ型拡散層の領域に酸化膜をバリア層として残すためには、エッチング前の段階で、ｎ型拡散層３の領域以外の酸化膜の５倍～６倍程度の厚さの酸化膜が形成されていることが望ましい。 [Oxidation treatment process]
The method for manufacturing a semiconductor substrate having an n-type diffusion layer may further include a step of oxidizing the semiconductor substrate having the n-type diffusion layer (hereinafter also referred to as “oxidation processing step”). An oxide film such as a silicon oxide film is formed by the oxidation treatment. The oxide film tends to be formed thick in the region of the n-type diffusion layer and thin in other regions.
The oxide film other than the region of the n-type diffusion layer is preferably removed by etching. At that time, the thickness of the oxide film formed in the region of the n-type diffusion layer also tends to be reduced by etching. Therefore, it is necessary to stop etching when the oxide film other than the region of the n-type diffusion layer is sufficiently removed. In order to leave the oxide film as a barrier layer in the n-type diffusion layer region, an oxide film about 5 to 6 times thicker than the oxide film other than the n-type diffusion layer 3 is formed before the etching. It is desirable that
　酸化処理の方法は特に限定されず、ドライ酸化及びウェット酸化からなる群より選択される少なくとも１種であることが好ましい。
　ドライ酸化とは、酸素ガス雰囲気下で、高温で処理することによる酸化方法を意味する。ドライ酸化の条件は特に限定されず、例えば、８００℃～１１００℃で１０分～２４０分処理を行うことが好ましい。
　ウェット酸化とは、酸素ガス及び脱イオン水蒸気を用いて高温で処理することによる酸化方法を意味する。ウェット酸化の条件は特に限定されず、例えば、８００℃～１１００℃で１０分～２４０分処理を行うことが好ましい。 The method for the oxidation treatment is not particularly limited, and is preferably at least one selected from the group consisting of dry oxidation and wet oxidation.
Dry oxidation means an oxidation method by treating at a high temperature in an oxygen gas atmosphere. Dry oxidation conditions are not particularly limited, and for example, it is preferable to perform the treatment at 800 ° C. to 1100 ° C. for 10 minutes to 240 minutes.
Wet oxidation means an oxidation method by processing at a high temperature using oxygen gas and deionized water vapor. The conditions for wet oxidation are not particularly limited. For example, it is preferable to perform the treatment at 800 ° C. to 1100 ° C. for 10 minutes to 240 minutes.
［ｐ型ドナー元素拡散工程］
　酸化処理工程の後、ｐ型ドナー元素を拡散する工程を更に含んでいてもよい。
　ｐ型ドナー元素源としては、例えば、三臭化ホウ素（ＢＢｒ３）、三塩化ホウ素（ＢＣｌ３）等のｐ型ドナー元素を含有するガス、及びｐ型ドナー元素と分散媒等の他の成分とを含む組成物が挙げられる。
　ｐ型ドナー元素をガス拡散する場合、加熱した拡散炉内にＢＢｒ３等の拡散ガスを導入し、ｎ型半導体基板の表面にｐ型ドナー元素を拡散及び堆積させることができる。
　ｐ型ドナー元素源としてホウ素を含む組成物を使用する場合、ホウ素を含む組成物をｎ型半導体基板の表面に付与する方法は特に制限されない。例えば、印刷法、スピンコート法、刷毛塗り、スプレー法、ドクターブレード法、ロールコート法、及びインクジェット法等が挙げられる。ｎ型半導体基板上にホウ素を含む組成物を付与し、拡散炉内で熱処理によりｐ型ドナー元素を拡散することができる。
　ｐ型ドナー元素を拡散する工程の前に酸化処理を行う場合は、ｐ型ドナー元素を拡散する前のｎ型拡散層上に、バリア層として機能する酸化膜が形成される。このため、ｐ型ドナー元素を含むガス又は組成物を使用しても、ｎ型拡散層にｐ型ドナー元素が拡散することを防止し易い。 [P-type donor element diffusion process]
A step of diffusing a p-type donor element may be further included after the oxidation treatment step.
As a p-type donor element source, for example, a gas containing a p-type donor element such as boron tribromide (BBr 3 ) or boron trichloride (BCl 3 ), and other components such as a p-type donor element and a dispersion medium The composition containing these is mentioned.
In the case of gas diffusion of the p-type donor element, a diffusion gas such as BBr 3 can be introduced into a heated diffusion furnace to diffuse and deposit the p-type donor element on the surface of the n-type semiconductor substrate.
When a composition containing boron is used as the p-type donor element source, the method for applying the boron-containing composition to the surface of the n-type semiconductor substrate is not particularly limited. Examples thereof include a printing method, a spin coating method, a brush coating, a spray method, a doctor blade method, a roll coating method, and an ink jet method. A composition containing boron is applied to the n-type semiconductor substrate, and the p-type donor element can be diffused by heat treatment in a diffusion furnace.
When the oxidation treatment is performed before the step of diffusing the p-type donor element, an oxide film functioning as a barrier layer is formed on the n-type diffusion layer before diffusing the p-type donor element. For this reason, even if the gas or composition containing a p-type donor element is used, it is easy to prevent the p-type donor element from diffusing into the n-type diffusion layer.
＜太陽電池素子に製造方法＞
　本発明の太陽電池素子の製造方法は、本発明のｎ型拡散層を有する半導体基板の製造方法により製造されるｎ型拡散層を有する半導体基板に、電極を形成する工程を含む。
　本発明の太陽電池素子の製造方法によれば、電極を形成する工程をｎ型拡散層を形成する工程とは個別に行うことができる。ｎ型拡散層と電極とを個別に形成することが可能であるため、後述するように、電極の材質、形成方法等の選択肢が広がる傾向にある。
　電極の材質及び形成方法は特に限定されず、当該技術分野において既知の材質及び形成方法を採用できる。電極の材質としては、従来技術で使用されている第１３族のアルミニウムに限定されず、Ａｇ（銀）、Ｃｕ（銅）等を適用することができ、電極の厚さも従来のものよりも薄くすることが可能となる。 <Production method for solar cell element>
The method for manufacturing a solar cell element of the present invention includes a step of forming an electrode on a semiconductor substrate having an n-type diffusion layer manufactured by the method for manufacturing a semiconductor substrate having an n-type diffusion layer of the present invention.
According to the method for manufacturing a solar cell element of the present invention, the step of forming the electrode can be performed separately from the step of forming the n-type diffusion layer. Since it is possible to form the n-type diffusion layer and the electrode separately, as will be described later, there is a tendency for options such as the material of the electrode and the forming method to expand.
The material and forming method of the electrode are not particularly limited, and materials and forming methods known in the art can be adopted. The material of the electrode is not limited to Group 13 aluminum used in the prior art, and Ag (silver), Cu (copper), etc. can be applied, and the thickness of the electrode is also thinner than the conventional one. It becomes possible to do.
　ｎ型拡散層を有する半導体基板の製造方法により製造されるｎ型拡散層を有する半導体基板は、特定ｎ型拡散層形成組成物を使用して製造されるため、半導体基板の所望の部位に選択的にｎ型拡散層が形成されている。 Since a semiconductor substrate having an n-type diffusion layer manufactured by a method for manufacturing a semiconductor substrate having an n-type diffusion layer is manufactured using a specific n-type diffusion layer forming composition, it is selected as a desired portion of the semiconductor substrate. In particular, an n-type diffusion layer is formed.
　従来より広く採用されている気相反応法では、所望の部位以外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る。この変換方法としては、所望の部位以外に形成された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付与して熱処理し、ｎ型拡散層にアルミニウムを拡散させてｐ型拡散層に変換する方法が広く採用されている。この方法においてｐ型拡散層への変換を充分なものとし、更にｐ＋型拡散層の高濃度電界層を形成するためには、ある程度以上のアルミニウム量が必要であることから、アルミニウム層を厚く形成する必要がある。しかしながら、アルミニウムの熱膨張率は、半導体基板の熱膨張率と大きく異なることから、熱処理及び冷却の過程で半導体基板中に大きな内部応力を発生させる傾向にある。
　この内部応力は、半導体基板として結晶シリコンを用いたときに結晶粒界に損傷を与え、この半導体基板を用いた太陽電池では電力損失が大きくなるという課題がある。
　また、内部応力が原因となって半導体基板の反りが生じる場合がある。半導体基板の反りは、モジュール工程における太陽電池素子の搬送、タブ線と呼ばれる銅線との接続等を行う際に、太陽電池素子を破損させ易くする。近年では、スライス加工技術の向上から、半導体基板であるシリコン基板の薄型化が進み、太陽電池素子が反りによっていっそう破損しやすくなっている。 In the gas phase reaction method that has been widely adopted conventionally, it is necessary to convert an unnecessary n-type diffusion layer formed in a region other than a desired site into a p-type diffusion layer. As this conversion method, a p-type diffusion layer is formed by applying a heat treatment by applying an aluminum paste as a group 13 element to an n-type diffusion layer formed in a region other than a desired region, and diffusing aluminum in the n-type diffusion layer. The method of converting to is widely adopted. In this method, conversion to the p-type diffusion layer is sufficient, and in order to form a high-concentration electric field layer of the p + -type diffusion layer, a certain amount of aluminum is required. Need to form. However, since the thermal expansion coefficient of aluminum is significantly different from that of the semiconductor substrate, a large internal stress tends to be generated in the semiconductor substrate during the heat treatment and cooling.
This internal stress damages the crystal grain boundary when crystalline silicon is used as the semiconductor substrate, and there is a problem that power loss increases in a solar cell using this semiconductor substrate.
Further, the semiconductor substrate may be warped due to internal stress. The warpage of the semiconductor substrate facilitates damage of the solar cell element when transporting the solar cell element in the module process, connecting to a copper wire called a tab wire, or the like. In recent years, the silicon substrate, which is a semiconductor substrate, has been thinned due to the improvement of the slicing technique, and the solar cell element is more easily damaged by warping.
　しかし、本発明の太陽電池素子の製造方法では、所望の部位にｎ型拡散層が形成されたｎ型拡散層を有する半導体基板を使用するため、従来の方法で行われていた所望の部位以外に形成されたｎ型拡散層を除去するためのサイドエッチング等が不要となり、工程が簡易化される傾向にある。また、所望の部位以外に形成された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、半導体基板の内部応力の発生及び半導体基板の反りを抑えることができる。結果として、この半導体基板を用いた太陽電池における電力損失の増大、及び太陽電池セルの破損を抑えることが可能となる。
　その結果、ｐ＋型拡散層の形成方法、電極の材質、形状、厚さ等が従来の方法に制限されず、適用する製造方法、材質、形状等の選択肢が広がる傾向にある。 However, in the method for manufacturing a solar cell element of the present invention, since a semiconductor substrate having an n-type diffusion layer in which an n-type diffusion layer is formed in a desired portion is used, other than the desired portion that has been performed by the conventional method. Side etching or the like for removing the n-type diffusion layer formed on the substrate becomes unnecessary, and the process tends to be simplified. Further, the step of converting the n-type diffusion layer formed in a region other than the desired portion into the p + -type diffusion layer is not necessary, and the necessity of increasing the thickness of the aluminum layer is eliminated. As a result, generation of internal stress in the semiconductor substrate and warpage of the semiconductor substrate can be suppressed. As a result, it is possible to suppress an increase in power loss and damage of the solar battery cell in the solar battery using this semiconductor substrate.
As a result, the method for forming the p + -type diffusion layer, the material, shape, thickness, etc. of the electrode are not limited to the conventional methods, and there are tendencies to expand the choices of manufacturing method, material, shape, etc. to be applied.
　次に、本発明のｎ型拡散層を有する半導体基板の製造方法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。尚、共通する構成要素には同じ符号を付す。 Next, a method for manufacturing a semiconductor substrate having an n-type diffusion layer and a method for manufacturing a solar cell element according to the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view conceptually showing an example of the manufacturing process of the solar cell element of the present invention. In addition, the same code | symbol is attached | subjected to a common component.
　まず、図１（１）に示すように、ｎ型半導体基板１である結晶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基板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との混合液を用いてエッチングを行い、テクスチャー構造を形成する（図１（１）中では、ｎ型半導体基板１の片面のみテクスチャー構造の記載とする）。太陽電池素子は、受光面（図１（１）中下面）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。 First, as shown in FIG. 1A, an alkaline solution is applied to a crystalline silicon substrate which is an n-type semiconductor substrate 1 to remove a damaged layer, and a texture structure is obtained by etching. Specifically, the damaged layer on the surface of the silicon substrate generated when slicing from the ingot is removed with 20% by mass caustic soda. Next, etching is performed using a mixed liquid of 1% by mass caustic soda and 10% by mass isopropyl alcohol to form a textured structure (in FIG. 1 (1), only one side of the n-type semiconductor substrate 1 has a description of the textured structure) To do). In the solar cell element, by forming a texture structure on the light receiving surface (the lower surface in FIG. 1 (1)), a light confinement effect is promoted, and high efficiency is achieved.
　図１（２）では、ｎ型半導体基板１の表面、すなわち受光面となる面に、本発明に係る特定ｎ型拡散層形成組成物を部分的に塗布することにより、ｎ型拡散組成物層２を形成する。 In FIG. 1 (2), the specific n-type diffusion layer forming composition according to the present invention is partially applied to the surface of the n-type semiconductor substrate 1, that is, the surface to be the light-receiving surface, thereby forming an n-type diffusion composition layer. 2 is formed.
　次に、図１（２）に示すｎ型拡散組成物層２を有するｎ型半導体基板１を、６００℃～１２００℃で、ガスの流量を線速度で３ｍｍ／秒～６０ｍｍ／秒の範囲として熱処理（熱拡散）する。この熱処理により、半導体基板中にドナー元素が拡散し、ｎ型拡散層３が形成される。このとき、ｎ型拡散層３の表面にはリン酸ガラス等のガラス層（不図示）が形成される。 Next, the n-type semiconductor substrate 1 having the n-type diffusion composition layer 2 shown in FIG. 1 (2) is set to 600 ° C. to 1200 ° C., and the gas flow rate is set in the range of 3 mm / second to 60 mm / second in linear velocity. Heat treatment (thermal diffusion). By this heat treatment, the donor element diffuses into the semiconductor substrate, and the n-type diffusion layer 3 is formed. At this time, a glass layer (not shown) such as phosphate glass is formed on the surface of the n-type diffusion layer 3.
　熱処理後に、ｎ型半導体基板１を常温まで冷却する。その後、ｎ型半導体基板１の上に形成されたガラス層をエッチングにより除去する。 After the heat treatment, the n-type semiconductor substrate 1 is cooled to room temperature. Thereafter, the glass layer formed on the n-type semiconductor substrate 1 is removed by etching.
　その後、酸化処理により図１（３）に示す酸化シリコン膜４を形成する。酸化シリコン膜４は、ｎ型拡散層３の領域に厚く形成され、それ以外の領域には薄く形成される。次に、ｎ型拡散層３の領域以外の酸化シリコン膜４をエッチングにより除去する。その際ｎ型拡散層３の領域に形成された酸化シリコン膜の厚さもエッチングにより減少する傾向にある。従って、ｎ型拡散層３の領域以外の酸化シリコン膜４が充分除去された段階でエッチングを止める。これにより、図１（４）に示すように、ｎ型拡散層３の領域にのみ酸化シリコン膜４をバリア層として有するｎ型半導体基板を得る。 Thereafter, a silicon oxide film 4 shown in FIG. 1 (3) is formed by oxidation treatment. The silicon oxide film 4 is formed thick in the region of the n-type diffusion layer 3 and thin in other regions. Next, the silicon oxide film 4 other than the region of the n-type diffusion layer 3 is removed by etching. At this time, the thickness of the silicon oxide film formed in the region of the n-type diffusion layer 3 also tends to be reduced by etching. Therefore, the etching is stopped when the silicon oxide film 4 other than the region of the n-type diffusion layer 3 is sufficiently removed. Thereby, as shown in FIG. 1 (4), an n-type semiconductor substrate having the silicon oxide film 4 as a barrier layer only in the region of the n-type diffusion layer 3 is obtained.
　次に、図１（４）に示すｎ型半導体基板１及び酸化シリコン膜４上に、ホウ素シリケートガラス層５を形成し、ｐ型ドナー元素を拡散してｐ型拡散層６を形成する。ホウ素シリケートガラス層５がｎ型半導体基板１に接触している領域にはｐ型拡散層６が形成される。一方、ｎ型拡散層３には、その上層に存在する酸化シリコン膜４がバリア層として機能するので、ホウ素シリケートガラス層５からのドナー元素が拡散することはない。 Next, a boron silicate glass layer 5 is formed on the n-type semiconductor substrate 1 and the silicon oxide film 4 shown in FIG. 1 (4), and a p-type diffusion layer 6 is formed by diffusing a p-type donor element. A p-type diffusion layer 6 is formed in a region where the boron silicate glass layer 5 is in contact with the n-type semiconductor substrate 1. On the other hand, in the n-type diffusion layer 3, since the silicon oxide film 4 existing on the n-type diffusion layer 3 functions as a barrier layer, the donor element from the boron silicate glass layer 5 does not diffuse.
　その後、ホウ素シリケートガラス層５及び酸化シリコン膜４をエッチングにより除去して、図１（６）に示すような、ｎ型拡散層３及びｐ型拡散層６を備えるｎ型半導体基板１を得る。 Thereafter, the boron silicate glass layer 5 and the silicon oxide film 4 are removed by etching to obtain the n-type semiconductor substrate 1 including the n-type diffusion layer 3 and the p-type diffusion layer 6 as shown in FIG.
　次に、パッシベーション膜７及び反射防止膜９を設け、更に電極８を形成することにより、図１（７）に示す太陽電池素子が得られる。 Next, by providing a passivation film 7 and an antireflection film 9 and further forming an electrode 8, a solar cell element shown in FIG. 1 (7) is obtained.
　上記では、ｎ型半導体基板１の片面にｎ型拡散層３及びｐ型拡散層６を備えるバックコンタクト型の太陽電池素子の製造方法について説明した。しかし、本発明のｎ型拡散層を有する半導体基板の製造方法を用いれば、両面電極型の太陽電池素子も製造可能である。 In the above description, the method for manufacturing the back contact type solar cell element including the n-type diffusion layer 3 and the p-type diffusion layer 6 on one surface of the n-type semiconductor substrate 1 has been described. However, if the method for producing a semiconductor substrate having an n-type diffusion layer of the present invention is used, a double-sided electrode type solar cell element can also be produced.
　上記では、ｎ型半導体基板の片面にｎ型拡散層とｐ型拡散層を備えたバックコンタクト型の太陽電池素子の製造方法について説明したが、本発明のｎ型拡散層形成方法を用いれば両面電極型の太陽電池素子も製造可能である。 In the above, the method of manufacturing the back contact type solar cell element provided with the n-type diffusion layer and the p-type diffusion layer on one side of the n-type semiconductor substrate has been described. However, if the n-type diffusion layer forming method of the present invention is used, An electrode-type solar cell element can also be manufactured.
　以下、本発明を、実施例を参照して具体的に説明する。しかし、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、薬品は試薬を使用した。また、「％」は断りがない限り「質量％」を意味する。 Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples. Unless otherwise stated, chemicals used reagents. “%” Means “% by mass” unless otherwise specified.
＜実施例１＞
　平均粒子径が１μｍであるＰ２Ｏ５－ＳｉＯ２－ＭｇＯガラス（Ｐ２Ｏ５：３４％、ＳｉＯ２：３９％、ＣａＯ：２７％）粒子９ｇと、エチルセルロース２．１ｇと、テルピネオール１８．９ｇとを混合して、ペースト状のｎ型拡散層形成組成物を調製した。
　次に、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、ｎ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。次に、４５０℃に設定したオーブンで１．５分間保持し、エチルセルロースを脱離した。 <Example 1>
9. P 2 O 5 —SiO 2 —MgO glass (P 2 O 5 : 34%, SiO 2 : 39%, CaO: 27%) particles having an average particle size of 1 μm, 9 g of ethyl cellulose, 2.1 g of terpineol, and 18. 9 g was mixed to prepare a paste-like n-type diffusion layer forming composition.
Next, the prepared n-type diffusion layer forming composition was applied to the surface of the n-type silicon substrate by screen printing and dried on a hot plate at 150 ° C. for 5 minutes. Next, it was kept in an oven set at 450 ° C. for 1.5 minutes to release ethyl cellulose.
　続いて、９５０℃に設定した拡散炉中で２０分間保持することで熱拡散処理を行った。その際、拡散炉内には、線速度３ｍｍ／秒で窒素と酸素の混合ガス(窒素：酸素の体積比＝５０：５０)を流した。その後、拡散炉からシリコン基板を取り出した。
　取り出したシリコン基板のｎ型拡散層形成組成物を塗布した面内では、透明なガラス層が形成されていた。このガラス層を除去するために、シリコン基板をフッ酸に５分間浸漬し、流水にて洗浄し、自然乾燥を行った。
　得られた縦１５６ｍｍ、横１５６ｍｍのシリコン基板のｎ型拡散層形成組成物を塗布した面内の５点のシート抵抗を測定した。得られたシート抵抗の標準偏差を求め、平均値で割って１００分率の数値として算出した値に基づいて、シート抵抗のバラつきの大小を評価した。尚、シート抵抗は、「Ｌｏｒｅｓｔａ－ＥＰ　ＭＣＰ－Ｔ３６０型低抵抗率計」（三菱化学（株））を用いて四探針法により測定した。 Subsequently, thermal diffusion treatment was performed by holding in a diffusion furnace set at 950 ° C. for 20 minutes. At that time, a mixed gas of nitrogen and oxygen (nitrogen: oxygen volume ratio = 50: 50) was flowed into the diffusion furnace at a linear velocity of 3 mm / second. Thereafter, the silicon substrate was taken out from the diffusion furnace.
A transparent glass layer was formed in the surface where the n-type diffusion layer forming composition of the silicon substrate was applied. In order to remove this glass layer, the silicon substrate was immersed in hydrofluoric acid for 5 minutes, washed with running water, and naturally dried.
The sheet resistance was measured at five points within the surface where the n-type diffusion layer forming composition of the obtained silicon substrate having a length of 156 mm and a width of 156 mm was applied. The standard deviation of the obtained sheet resistance was obtained, and the degree of variation in sheet resistance was evaluated based on the value calculated by dividing by the average value as a numerical value of 100 minutes. The sheet resistance was measured by a four-probe method using a “Loresta-EP MCP-T360 type low resistivity meter” (Mitsubishi Chemical Corporation).
　その後、下記の方法でドライ酸化を行った。まず、酸素１０Ｌを流した状態で拡散炉を１０００℃まで加熱し、上記シリコン基板を拡散炉に入れ、３時間放置した。
　取り出したシリコン基板のｎ型拡散層形成組成物を塗布した面には、青みがかった酸化シリコン膜が形成されていた。この酸化シリコン膜の平均厚さ（Å）を、エリプソメーターを用いて測定した。結果を表１に示す。 Thereafter, dry oxidation was performed by the following method. First, the diffusion furnace was heated to 1000 ° C. with 10 L of oxygen flowing, and the silicon substrate was placed in the diffusion furnace and left for 3 hours.
A bluish silicon oxide film was formed on the surface of the extracted silicon substrate on which the n-type diffusion layer forming composition was applied. The average thickness (Å) of this silicon oxide film was measured using an ellipsometer. The results are shown in Table 1.
　その後、ＢＢｒ３ガスを使用してホウ素の熱拡散を行った後、フッ酸エッチングにより酸化シリコン膜及びホウ素シリケートガラス膜を除去した。
　得られたシリコン基板のｎ型拡散層領域を、２次イオン質量分析装置「ＩＭＳ－７Ｆ」（ＣＡＭＥＣＡ社）を用いて、分析室に酸素ガスを流しながら、一次イオンエネルギー６０００ｅＶにてシリコン基板の２μｍ深さまで、２次イオン質量分析し、ホウ素の量を測定した。ホウ素の量が１Ｅ１６（１×１０１６）ａｔｏｍｓ／ｃｍ３未満である場合、酸化シリコン膜がバリア性を有すると判断した。結果を表１に示す。 Then, after performing thermal diffusion of boron using BBr 3 gas, the silicon oxide film and the boron silicate glass film were removed by hydrofluoric acid etching.
Using the secondary ion mass spectrometer “IMS-7F” (CAMECA), the n-type diffusion layer region of the obtained silicon substrate was subjected to a primary ion energy of 6000 eV while flowing oxygen gas into the analysis chamber. Secondary ion mass spectrometry was performed to a depth of 2 μm, and the amount of boron was measured. When the amount of boron was less than 1E16 (1 × 10 16 ) atoms / cm 3 , it was determined that the silicon oxide film had a barrier property. The results are shown in Table 1.
＜実施例２～実施例４＞
　実施例１における熱拡散の際に、拡散炉内に流すガスの線速度を７ｍｍ／秒（実施例２）、１０ｍｍ／秒（実施例３）又は２０ｍｍ／秒（実施例４）に変更した以外は、実施例１と同様の処理を行い、酸化シリコン膜の平均厚さ及びバリア性の有無を評価した。結果を表１に示す。 <Example 2 to Example 4>
Other than changing the linear velocity of the gas flowing in the diffusion furnace to 7 mm / second (Example 2), 10 mm / second (Example 3), or 20 mm / second (Example 4) during the thermal diffusion in Example 1 Performed the same treatment as in Example 1, and evaluated the average thickness of the silicon oxide film and the presence or absence of barrier properties. The results are shown in Table 1.
＜比較例１～比較例２＞
　実施例１における熱拡散の際に、拡散炉内に流すガスの線速度を１ｍｍ／秒（比較例１）又は２ｍｍ／秒（比較例２）に変更した以外は、実施例１と同様の処理を行い、酸化シリコン膜の平均厚さ及びバリア性の有無を評価した。結果を表１に示す。 <Comparative Example 1 to Comparative Example 2>
The same treatment as in Example 1 except that the linear velocity of the gas flowing in the diffusion furnace during the thermal diffusion in Example 1 was changed to 1 mm / second (Comparative Example 1) or 2 mm / second (Comparative Example 2). Then, the average thickness of the silicon oxide film and the presence or absence of barrier properties were evaluated. The results are shown in Table 1.
Figure JPOXMLDOC01-appb-I000001

 
Figure JPOXMLDOC01-appb-I000001

 
　日本国特許出願第２０１４－１４５３７５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、及び技術規格は、個々の文献、特許出願、及び技術規格が参照により取り込まれることが具体的かつ個々に記された場合と同程度に、本明細書に参照により取り込まれる。 The entire disclosure of Japanese Patent Application No. 2014-145375 is incorporated herein by reference. All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims (8)

  1. 　ドナー元素を含むガラス粒子と、分散媒と、を含有するｎ型拡散層形成組成物が少なくとも一部に付与された半導体基板を、ガスの流量が線速度で３ｍｍ／秒～６０ｍｍ／秒である条件下で熱処理する工程を含む、ｎ型拡散層を有する半導体基板の製造方法。 A semiconductor substrate provided with at least a part of an n-type diffusion layer forming composition containing glass particles containing a donor element and a dispersion medium has a gas flow rate of 3 mm / second to 60 mm / second at a linear velocity. A method for manufacturing a semiconductor substrate having an n-type diffusion layer, comprising a step of heat-treating under conditions.
  2. 　前記熱処理する工程の後、前記半導体基板上に形成されたガラス層をエッチングにより除去する工程を更に含む請求項１に記載のｎ型拡散層を有する半導体基板の製造方法。 The method for manufacturing a semiconductor substrate having an n-type diffusion layer according to claim 1, further comprising a step of removing the glass layer formed on the semiconductor substrate by etching after the heat treatment step.
  3. 　前記ドナー元素が、Ｐ（リン）及びＳｂ（アンチモン）からなる群より選択される少なくとも１種である請求項１又は請求項２に記載のｎ型拡散層を有する半導体基板の製造方法。 The method for producing a semiconductor substrate having an n-type diffusion layer according to claim 1 or 2, wherein the donor element is at least one selected from the group consisting of P (phosphorus) and Sb (antimony).
  4. 　前記ドナー元素を含むガラス粒子が、
    　Ｐ２Ｏ３、Ｐ２Ｏ５及びＳｂ２Ｏ３からなる群より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、Ｖ２Ｏ５、ＳｎＯ、ＺｒＯ２及びＭｏＯ３からなる群より選択される少なくとも１種のガラス成分物質と、
    　を含有する請求項１～請求項３のいずれか１項に記載のｎ型拡散層を有する半導体基板の製造方法。     Glass particles containing the donor element are
    At least one donor element-containing material selected from the group consisting of P 2 O 3 , P 2 O 5 and Sb 2 O 3 ;
    Selected from the group consisting of SiO 2 , K 2 O, Na 2 O, Li 2 O, BaO, SrO, CaO, MgO, BeO, ZnO, PbO, CdO, V 2 O 5 , SnO, ZrO 2 and MoO 3. At least one glass component substance;
    The method for producing a semiconductor substrate having an n-type diffusion layer according to any one of claims 1 to 3, comprising:
  5. 　前記ｎ型拡散層を有する半導体基板を酸化処理する工程を更に含む請求項１～請求項４のいずれか１項に記載のｎ型拡散層を有する半導体基板の製造方法。 The method for producing a semiconductor substrate having an n-type diffusion layer according to any one of claims 1 to 4, further comprising a step of oxidizing the semiconductor substrate having the n-type diffusion layer.
  6. 　前記酸化処理が、ドライ酸化及びウェット酸化からなる群より選択される少なくとも１種である請求項１～請求項５のいずれか１項に記載のｎ型拡散層を有する半導体基板の製造方法。 The method for manufacturing a semiconductor substrate having an n-type diffusion layer according to any one of claims 1 to 5, wherein the oxidation treatment is at least one selected from the group consisting of dry oxidation and wet oxidation.
  7. 　前記半導体基板がシリコン基板である請求項１～請求項６のいずれか１項に記載のｎ型拡散層を有する半導体基板の製造方法。 The method for producing a semiconductor substrate having an n-type diffusion layer according to any one of claims 1 to 6, wherein the semiconductor substrate is a silicon substrate.
  8. 　請求項１～請求項７のいずれか１項に記載のｎ型拡散層を有する半導体基板の製造方法により製造されるｎ型拡散層を有する半導体基板に、電極を形成する工程を含む、太陽電池素子の製造方法。 A solar cell comprising a step of forming an electrode on a semiconductor substrate having an n-type diffusion layer manufactured by the method for manufacturing a semiconductor substrate having an n-type diffusion layer according to any one of claims 1 to 7. Device manufacturing method.
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JP2013026344A (en) * 2011-07-19 2013-02-04 Hitachi Chem Co Ltd Manufacturing method of n-type diffusion layer, manufacturing method of solar cell element, and solar cell element
JP2013026579A (en) * 2011-07-25 2013-02-04 Hitachi Chem Co Ltd Manufacturing method of p-type diffusion layer and manufacturing method of solar cell element
JP2013026467A (en) * 2011-07-21 2013-02-04 Hitachi Chem Co Ltd Manufacturing method of n-type diffusion layer and manufacturing method of solar cell element
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JP2013026344A (en) * 2011-07-19 2013-02-04 Hitachi Chem Co Ltd Manufacturing method of n-type diffusion layer, manufacturing method of solar cell element, and solar cell element
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