WO2024057722A1 - Impurity diffusion composition, method for producing semiconductor element using same, and method for producing solar cell - Google Patents

Impurity diffusion composition, method for producing semiconductor element using same, and method for producing solar cell Download PDF

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WO2024057722A1
WO2024057722A1 PCT/JP2023/026935 JP2023026935W WO2024057722A1 WO 2024057722 A1 WO2024057722 A1 WO 2024057722A1 JP 2023026935 W JP2023026935 W JP 2023026935W WO 2024057722 A1 WO2024057722 A1 WO 2024057722A1
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impurity diffusion
mass
diffusion composition
parts
composition according
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French (fr)
Japanese (ja)
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脩平 田邉
智之 弓場
邦彦 橘
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東レ株式会社
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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
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof

Definitions

  • the present invention relates to an impurity diffusion composition for diffusing impurities in a semiconductor substrate, a method for manufacturing a semiconductor element, and a method for manufacturing a solar cell using the composition.
  • Non-Patent Document 1 and Patent Document 1 solar cells with a selective emitter structure have been proposed in order to reduce contact resistance with electrodes and suppress carrier recombination (see, for example, Non-Patent Document 1 and Patent Document 1).
  • a high-concentration p-type diffusion layer p ++ layer
  • p + layer p + layer
  • the photoelectric conversion efficiency of the solar cell will improve.
  • a p + layer in advance on the entire surface of an n-type substrate, selectively forming a pattern on it using a coating liquid containing an impurity diffusion component, and performing heat treatment, p ++ is applied to the coating liquid pattern area.
  • a method of forming a layer has been proposed as a promising method for improving photoelectric conversion efficiency because it causes less contamination of impurities from the coating liquid to the p + layer.
  • An impurity diffusion coating liquid for forming an impurity diffusion layer on a semiconductor substrate may contain, for example, a polyvinyl alcohol resin (A), an impurity (B), and a polyhydric alcohol (C) with a boiling point of 100° C. or higher.
  • a coating liquid for impurity diffusion characterized in that the content of the polyhydric alcohol (C) is 70% by weight or more in the coating liquid for example, see Patent Document 3
  • Patent Document 4 a specific structure with a side chain impurity diffusion compositions (for example, see Patent Document 4) have been proposed, which include a polymer contained in (B) and an impurity diffusion component (B).
  • the present invention has been made based on the above-mentioned circumstances, and provides an impurity diffusion composition that enables uniform impurity diffusion at a high concentration even when diffusing into a substrate on which an impurity diffusion layer is previously formed.
  • the purpose is to provide.
  • An impurity diffusion composition containing (A) polyvinyl alcohol having a saponification degree of 30 mol% or more and less than 70 mol%, (B) an impurity diffusion component, and (C) inorganic fine particles, the impurity diffusion composition comprising (A) An impurity diffusion composition containing 0.01 to 27.5 parts by mass of (C) inorganic fine particles per 100 parts by mass of polyvinyl alcohol.
  • ⁇ 3> The impurity diffusion composition according to ⁇ 1> or ⁇ 2>, wherein the polyvinyl alcohol (A) has an average degree of polymerization of 100 or more and 1,000 or less.
  • ⁇ 4> The impurity diffusion composition according to any one of ⁇ 1> to ⁇ 3>, wherein the average degree of polymerization N and the degree of saponification X of the polyvinyl alcohol (A) satisfy the relationship of the following formula (Y1).
  • the impurity diffusion composition according to any one of ⁇ 1> to ⁇ 4>, further comprising (D) a solvent, and (D) a solvent having a structure represented by the following general formula (1) as the solvent. thing.
  • R 1 represents hydrogen, a hydroxyl group, or a monovalent organic group having 1 to 3 carbon atoms.
  • R 2 to R 6 may be the same or different, and each represents hydrogen or a monovalent organic group having 1 to 3 carbon atoms.
  • ⁇ 6> The impurity diffusion composition according to ⁇ 5>, which contains 5 to 90 parts by mass of the solvent having the structure represented by the general formula (1), based on the total 100 parts by mass of the solvent (D).
  • D The impurity diffusion composition according to ⁇ 5> or ⁇ 6>, further containing water as a solvent.
  • the impurity diffusion composition according to ⁇ 7> which contains the water in an amount of 0.2 to 3 parts by mass based on 100 parts by mass of the total solvent (D).
  • Impurity diffusion according to any one of ⁇ 1> to ⁇ 8> wherein the total content of the alkoxysilane compound, silanol compound, and siloxane resin is less than 15 parts by mass based on 100 parts by mass of (A) polyvinyl alcohol.
  • Composition. ⁇ 10> Applying the impurity diffusion composition according to any one of ⁇ 1> to ⁇ 9> on a semiconductor substrate to form an impurity diffusion composition pattern, and diffusing impurities from the impurity diffusion composition pattern.
  • a method for manufacturing a semiconductor device including a step of forming an impurity diffusion layer on a semiconductor substrate.
  • Method. ⁇ 12> The method for manufacturing a semiconductor element according to ⁇ 10> or ⁇ 11>, including the step of forming impurity diffusion layers having two or more different impurity concentrations on the semiconductor substrate.
  • a method for manufacturing a solar cell comprising a step of manufacturing a semiconductor element by the method according to any one of ⁇ 10> to ⁇ 12>, a step of forming a passivation layer, and a step of forming an electrode.
  • an impurity diffusion composition that enables uniform impurity diffusion at a high concentration even when diffusing into a substrate on which an impurity diffusion layer is previously formed.
  • FIG. 1A and 1B are process cross-sectional views showing a method for manufacturing a semiconductor device according to an embodiment of the present invention.
  • FIG. 1 is a process cross-sectional view showing a method for manufacturing a solar cell according to an embodiment of the present invention. It is a figure showing the measurement position of the resistance value in an example.
  • FIG. 3 is a diagram showing the relationship between the average degree of polymerization N and saponification degree X of PVA-1 to PVA-25 in Examples.
  • the impurity diffusion composition of the present invention comprises (A) polyvinyl alcohol having a saponification degree of 30 mol% or more and less than 70 mol% (hereinafter sometimes abbreviated as "(A) PVA"), (B) impurity diffusion component and (C) inorganic fine particles.
  • the impurity diffusion component is a component for forming an impurity diffusion layer, and (A) PVA forms a complex with the (B) impurity diffusion component to form a uniform impurity diffusion layer.
  • the stability of the complex of (A) PVA and (B) impurity diffusion component in the impurity diffusion composition is increased, Even in the case of diffusion into a substrate on which an impurity diffusion layer has been formed in advance, high concentration diffusion can be promoted and the uniformity of the impurity diffusion layer can be improved.
  • (C) Inorganic fine particles have been conventionally known as a component that imparts thixotropy to an impurity diffusion composition and improves the coating properties when applying the impurity diffusion composition by screen printing or the like.
  • (A) PVA forms a complex with (B) impurity diffusion component to form a uniform impurity diffusion layer. It is a component of By setting the degree of saponification of PVA to 30 mol% or more and less than 70 mol%, the stability of the complex of (A) PVA and (B) impurity diffusion component in the impurity diffusion composition is increased, and the impurity diffusion layer is In the case of diffusion into the substrate where the impurity is formed, it is possible to promote high-concentration diffusion and improve the uniformity of the impurity diffusion layer.
  • the degree of saponification is less than 30 mol%, the formation of a complex will not be sufficient, and the diffusion of high concentration into the substrate on which the impurity diffusion layer has been formed will be insufficient, and the uniformity of the impurity diffusion layer will be poor. descend.
  • the degree of saponification is preferably 35 mol% or more, and more preferably 40 mol% or more from the viewpoint of further promoting high concentration diffusion and further improving the uniformity of the impurity diffusion layer.
  • the degree of saponification is 70 mol% or more, the formed complex will not be stabilized and will aggregate in the impurity diffusion composition, resulting in high concentration diffusion into the substrate on which the impurity diffusion layer has been formed in advance.
  • the degree of saponification is preferably less than 65 mol%, more preferably less than 60 mol%, and more preferably less than 55 mol% from the viewpoint of further promoting high concentration diffusion and further improving the uniformity of the impurity diffusion layer.
  • the degree of saponification of PVA can be measured by the back titration method of JIS K 6726 (1994).
  • the degree of saponification of PVA means the degree of saponification of the two or more types of PVA as a whole.
  • the average degree of polymerization of PVA is preferably 100 or more and 1,000 or less, which further improves the stability of the complex in the impurity diffusion composition, and also allows for high diffusion into a substrate on which an impurity diffusion layer is formed in advance. It is possible to further promote concentration diffusion and further improve the uniformity of the impurity diffusion layer.
  • the average degree of polymerization of PVA can be measured by the back titration method according to JIS K 6726 (1994).
  • the average degree of polymerization of PVA means the average degree of polymerization of the two or more types of PVA as a whole.
  • the average degree of polymerization N and saponification degree X of PVA satisfy the relationship of the following formula (Y1), which further improves the stability of the complex in the impurity diffusion composition and prevents the impurity diffusion layer from being formed in advance. Even in the case of diffusion into a substrate containing an impurity, high concentration diffusion can be further promoted, and the uniformity of the impurity diffusion layer can be further improved.
  • Formula (Y1) indicates that as the saponification degree X of PVA increases, it is preferable that the average degree of polymerization N decrease within a certain range.
  • the formed complex can be further stabilized, and the effect of suppressing aggregation and association in the impurity diffusion composition can be further enhanced.
  • the average degree of polymerization N and the degree of saponification X of PVA satisfy the relationship of the following formula (Y2). 2.5 ⁇ (50-X)+210 ⁇ N ⁇ 12.5 ⁇ (50-X)+500 (Y2).
  • the content of PVA in the impurity diffusion composition is preferably 1% by mass or more, more preferably 5% by mass or more, and more preferably 10% by mass or more, from the viewpoint of further improving the uniformity of the high concentration impurity diffusion layer.
  • the content of PVA is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.
  • (B) Impurity Diffusion Component is a component for forming an impurity diffusion layer.
  • a compound containing an element of group 13 is preferable, and a boron compound is more preferable.
  • a compound containing a Group 15 element is preferable, and a phosphorus compound is more preferable.
  • (A) forms a more stable complex with PVA, and even when diffusing into a substrate on which an impurity diffusion layer has been formed, it promotes high concentration diffusion and improves the uniformity of the impurity diffusion layer. From the viewpoint of improving the performance, boron compounds are preferred.
  • boron compounds include boric acid, diboron trioxide, methylboronic acid, phenylboronic acid, trimethyl borate, triethyl borate, tripropyl borate, tributyl borate, trioctyl borate, triphenyl borate, etc. It will be done. Two or more types of these may be contained. Among these, boric acid is preferred from the viewpoint of doping properties.
  • Examples of phosphorus compounds include diphosphorus pentoxide, phosphoric acid, polyphosphoric acid, methyl phosphate, dimethyl phosphate, trimethyl phosphate, ethyl phosphate, diethyl phosphate, triethyl phosphate, propyl phosphate, dipropyl phosphate, Phosphate esters such as tripropyl phosphate, butyl phosphate, dibutyl phosphate, tributyl phosphate, phenyl phosphate, diphenyl phosphate, triphenyl phosphate, methyl phosphite, dimethyl phosphite, trimethyl phosphite , ethyl phosphite, diethyl phosphite, triethyl phosphite, propyl phosphite, dipropyl phosphite, tripropyl phosphite, butyl phosphite,
  • the content of the impurity diffusion component in the impurity diffusion composition is preferably 0.1% by mass or more, more preferably 0.5% by mass, and 1% by mass from the viewpoint of further improving the uniformity of the high concentration impurity diffusion layer. is more preferable.
  • the content of the impurity diffusion component in the impurity diffusion composition is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.
  • Inorganic fine particles examples include fine particles of silicon, titanium, germanium, zirconium, and their oxides and nitrides. Two or more types of these may be contained. From the viewpoint of the balance between thixotropy and impurity diffusion characteristics, silicon, its oxides, and nitrides are preferred, and silicon oxide fine particles are more preferred.
  • the number average particle diameter of the inorganic fine particles (C) is preferably 5 nm or more, and higher thixotropy can be imparted through appropriate intermolecular interactions.
  • the number average particle diameter of the inorganic fine particles is more preferably 7 nm or more, and even more preferably 10 nm or more.
  • the number average particle diameter of the inorganic fine particles (C) is preferably 500 nm or less, and higher thixotropy can be imparted through appropriate intermolecular interactions.
  • the number average particle diameter of the inorganic fine particles is more preferably 400 nm or less, further preferably 300 nm or less, and even more preferably 250 nm or less.
  • the number average particle diameter of the inorganic fine particles (C) in the present invention refers to the number average value of the major diameters of the particles. Specifically, it can be determined by observing (C) inorganic fine particles under magnification using a transmission electron microscope, measuring the long diameter of 10 randomly selected particles, and calculating the number average value. .
  • (C) inorganic fine particles have the effect of imparting thixotropy to the impurity diffusion composition, but the content thereof is 27.5 parts by mass relative to 100 parts by mass of (A) PVA. If it exceeds this, the stability of the complex of (A) PVA and (B) impurity diffusion component decreases, making it difficult to form a highly concentrated impurity diffusion layer. Therefore, in the present invention, by setting the content of (C) inorganic fine particles to 27.5 parts by mass or less with respect to 100 parts by mass of (A) PVA, it is possible to form a complex between (A) PVA and (B) impurity diffusion component. Even in the case of diffusion into a substrate on which an impurity diffusion layer has been formed in advance, it is possible to promote high concentration diffusion and improve the uniformity of the impurity diffusion layer.
  • the content of (C) inorganic fine particles in the impurity diffusion composition of the present invention is 0.01 parts by mass or more based on 100 parts by mass of (A) PVA, which imparts higher thixotropy and improves the impurity diffusion layer. Even in the case of diffusion into a substrate that has been formed in advance, it is possible to promote high concentration diffusion and improve the uniformity of the impurity diffusion layer.
  • the content of the inorganic fine particles is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more.
  • the content of the inorganic fine particles (C) is more preferably 3 parts by mass or more, and even more preferably 10 parts by mass or more. , more preferably 15 parts by mass or more.
  • the content of (C) inorganic fine particles is preferably 25 parts by mass or less with respect to 100 parts by mass of (A) PVA, and furthermore, even after the impurity diffusion composition is stored at room temperature, diffusion at a higher concentration is further promoted.
  • the content of the inorganic fine particles (C) is more preferably 24.5 parts by mass or less, more preferably 22.5 parts by mass or less.
  • the amount is more preferably 20.5 parts by mass or less.
  • the impurity diffusion composition of the present invention preferably further contains (D) a solvent.
  • the boiling point of the solvent (D) is preferably 100° C. or higher from the viewpoint of improving printability.
  • the boiling point is 100° C. or higher, for example, when printing the impurity diffusion composition by screen printing, it is possible to prevent the impurity diffusion composition from drying and fixing on the printing plate.
  • the boiling point of the solvent is more preferably 160°C or higher, and even more preferably 180°C or higher.
  • solvents with a boiling point of 100°C or higher include ethyl lactate (boiling point 155°C), diacetone alcohol (boiling point 169°C), propylene glycol monomethyl ether acetate (boiling point 145°C), propylene glycol monomethyl ether (boiling point 120°C), -Methoxy-3-methyl-1-butanol (boiling point 174°C), ⁇ -butyrolactone (boiling point 204°C), N-methyl-2-pyrrolidone (boiling point 204°C), N,N-dimethylimidazolidinone (boiling point 226°C) ), terpineol (boiling point 219°C), and 1,3-propanediol (214°C). Two or more types of these may be contained.
  • the content of the solvent (D) in the impurity diffusion composition is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 50% by mass or more, and even more preferably 65% by mass or more.
  • the content of the solvent (D) is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.
  • the solvent (D) contains a solvent having a structure represented by the following general formula (1).
  • the solvent having the structure represented by the following general formula (1) in the impurity diffusion composition of the present invention, even if the impurity diffusion composition is stored at room temperature, (A) PVA and (B) impurity diffusion The stability of the complex with the components can be maintained, and the uniformity of the impurity diffusion layer can be further improved.
  • R 1 represents hydrogen, a hydroxyl group, or a monovalent organic group having 1 to 3 carbon atoms.
  • R 2 to R 6 may be the same or different, and each represents hydrogen or a monovalent organic group having 1 to 3 carbon atoms.
  • the organic group having 1 to 3 carbon atoms is preferably a hydrocarbon group, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and the like.
  • Examples of the solvent having the structure represented by the above general formula (1) include 1,3-propanediol (boiling point 214°C), 1,3-butanediol (boiling point 207°C), 2-methyl-1,3- Propanediol (boiling point 214°C), glycerol (boiling point 290°C), 2,2-dimethyl-1,3-propanediol (boiling point 210°C), 3-methyl-1,3-butanediol (boiling point 203°C), 2 , 4-pentanediol (boiling point 198°C), and 1,2,3-butanetriol (boiling point 312°C). Two or more types of these may be contained.
  • the content of the solvent having the structure represented by the general formula (1) is determined to be 100% of the total amount of (D) solvent.
  • the content of the solvent having the structure represented by the general formula (1) is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and 60 parts by mass or less out of 100 parts by mass of the total solvent (D). is more preferable, and even more preferably 55 parts by mass or less.
  • the solvent (D) contains an alicyclic alcohol, a monoterpene alcohol, a sesquiterpene alcohol, and/or a diterpene alcohol together with the solvent having the structure represented by the general formula (1), and has an impurity diffusion composition. Even if the product is stored at room temperature, the stability of the complex of (A) PVA and (B) impurity diffusion component can be maintained, and the uniformity of the impurity diffusion layer can be further improved.
  • Examples of the alicyclic alcohol include cyclohexanol (boiling point 161°C) and 4-hydroxycyclohexan-1-one (boiling point 256°C).
  • Examples of monoterpene alcohols include terpineol (boiling point 219°C), linalool (boiling point 198°C), geraniol (boiling point 230°C), nerol (boiling point 225°C), terpinen-4-ol (boiling point 210°C), citronellol (boiling point 225°C), L-menthol (boiling point 212°C), lavandulol (boiling point 203°C), and borneol (boiling point 213°C).
  • sesquiterpene alcohol examples include farnesol (boiling point 111°C), patcholol (boiling point 140°C), viridiflorol (boiling point 290°C), and casinool (boiling point 139°C).
  • diterpene alcohols examples include sclareol (boiling point 360°C), manol (boiling point 390°C), and phytol (boiling point 204°C). Two or more types of these may be contained. Among these, monoterpene alcohol, sesquiterpene alcohol, and diterpene alcohol are more preferred, and monoterpene alcohol is even more preferred.
  • the content of the solvent having the structure represented by the general formula (1) ((1) content) and the total content of alicyclic alcohol, monoterpene alcohol, sesquiterpene alcohol, and diterpene alcohol (alcohol content) (1) content maintains the stability of the complex of (A) PVA and (B) impurity diffusion component even if the impurity diffusion composition is stored at room temperature, and From the viewpoint of further improving the uniformity of the layer, the amount is preferably 8 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more.
  • the alcohol content maintains the stability of the complex of (A) PVA and (B) impurity diffusion component even when the impurity diffusion composition is stored at room temperature, and further improves the uniformity of the impurity diffusion layer.
  • the content is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, and even more preferably 55 parts by mass or less.
  • the solvent (D) it is more preferable to contain water together with the solvent having the structure represented by the general formula (1), and by containing a small amount of water that forms strong hydrogen bonds as the solvent (D), Even when the impurity diffusion composition is stored at room temperature, the stability of the complex between (A) PVA and (B) impurity diffusion component is maintained, and even after the impurity diffusion composition is stored at room temperature, a higher concentration of diffusion is achieved. This can be further promoted.
  • the content of water is preferably 0.2 to 3 parts by weight, more preferably 0.2 to 2 parts by weight, and even more preferably 0.2 to 1 part by weight based on the total 100 parts by weight of the solvent (D).
  • the impurity diffusion composition of the present invention may contain a thixotropic agent other than the inorganic fine particles (C) from the viewpoint of further improving thixotropic properties.
  • a thixotropic agent other than inorganic fine particles include those exemplified as thixotropic agents in International Publication No. 2020/116340, other than (C) inorganic fine particles.
  • the impurity diffusion composition of the present invention preferably does not substantially contain an alkoxysilane compound, a silanol compound, and a siloxane resin, and stabilizes the complex of (A) PVA and (B) impurity diffusion component in the impurity diffusion composition. Even in the case of diffusion into a substrate on which an impurity diffusion layer has been formed in advance, diffusion of high concentration can be further promoted, and the uniformity of the impurity diffusion layer can be further improved.
  • the total content of the alkoxysilane compound, silanol compound, and siloxane resin is preferably less than 15 parts by mass based on 100 parts by mass of (A) polyvinyl alcohol.
  • the total content of alkoxysilane compounds, silanol compounds, and siloxane resins refers to the content if any one of alkoxysilane compounds, silanol compounds, or siloxane resins is contained, and the content if two or more of these are contained. refers to its total content.
  • the impurity diffusion composition of the present invention includes, for example, (A) PVA, (B) an impurity diffusion component, (C) inorganic fine particles, and optionally (D) a solvent, thixotropic agent, surfactant, thickener, etc. It can be obtained by mixing additives.
  • the mixing temperature is preferably 5 to 90°C, more preferably 20 to 80°C.
  • the mixing time is preferably 1 to 20 hours, more preferably 2 to 8 hours.
  • (A) to (C) and other additives may be added to (D) solvent at the same time and mixed, or (C) inorganic
  • (A) PVA, (B) impurity diffusion component, and other additives as necessary may be added and mixed.
  • (A) PVA and (B) impurity diffusion component are added and mixed in (D) solvent to form a complex, and then (C) inorganic fine particles and other additives are added and mixed as necessary. It is preferable to do so.
  • the method for manufacturing a semiconductor device of the present invention includes a step of applying the impurity diffusion composition of the present invention to a semiconductor substrate to form an impurity diffusion composition pattern (hereinafter sometimes abbreviated as “impurity diffusion composition pattern forming step”). ) and a step (hereinafter sometimes abbreviated as “impurity diffusion layer forming step”) of diffusing impurities from the impurity diffusion composition pattern to form an impurity diffusion layer on the semiconductor substrate.
  • impurity diffusion composition pattern forming step a step of diffusing impurities from the impurity diffusion composition pattern to form an impurity diffusion layer on the semiconductor substrate.
  • impurity diffusion composition pattern forming step a step of diffusing impurities from the impurity diffusion composition pattern to form an impurity diffusion layer on the semiconductor substrate.
  • impurity diffusion layer forming step For selective emitter formation, it is preferable that the same type of impurity as the impurity diffusion composition is diffused into the surface of the semiconductor substrate. Further, it is preferable to include
  • FIG. 1 shows an example of an embodiment of the method for manufacturing a semiconductor device of the present invention.
  • a method for forming a p-type impurity diffusion layer using a p-type impurity diffusion composition will be described.
  • a semiconductor substrate 1 is used.
  • Semiconductor substrates include, for example, n-type single crystal silicon with an impurity concentration of 10 15 to 10 16 atoms/cm 3 , polycrystalline silicon, a crystal substrate in which silicon is mixed with other elements such as germanium and carbon, and p-type Examples include semiconductor substrates other than silicon, such as crystalline silicon and gallium arsenide. Further, in order to form selective emitters, a p-type impurity diffusion layer may be formed in advance on the surface of the n-type single crystal silicon substrate.
  • the thickness of the semiconductor substrate is preferably 50 to 300 ⁇ m.
  • the shape of the semiconductor substrate is preferably a substantially rectangular outer shape with a side of 100 to 250 mm. Further, the surface of the semiconductor substrate is preferably etched using a hydrofluoric acid solution, an alkaline solution, or the like, so that slice damage and a natural oxide film can be removed.
  • the p-type impurity diffusion method may be, for example, a p-type impurity gas atmosphere.
  • Examples include a method in which the p-type impurity diffusion composition is applied and then heated and thermally diffused.
  • heating methods include uniform heating methods such as electric heating and infrared heating, and local heating methods such as laser heating.
  • the temperature and time of thermal diffusion are preferably, for example, 800° C. or higher and 1200° C. or lower for 1 to 120 minutes.
  • Thermal diffusion may be performed in the atmosphere, or the amount of oxygen in the atmosphere may be adjusted as appropriate using an inert gas such as nitrogen or argon. From the viewpoint of shortening the diffusion time, it is preferable that the oxygen concentration in the atmosphere is 3% or less.
  • baking may be performed in the range of 200° C. to 850° C. before diffusion.
  • the p-type impurity diffusion composition of the present invention is partially applied onto the p-type impurity diffusion layer 2 to form a p-type impurity diffusion composition pattern 3.
  • methods for applying the impurity diffusion composition include spin coating, screen printing, inkjet printing, slit coating, spray coating, letterpress printing, and intaglio printing.
  • the thickness of the impurity diffusion composition film after drying is preferably 100 nm or more from the viewpoint of impurity diffusibility, and preferably 10 ⁇ m or less from the viewpoint of the residue after etching.
  • impurities are diffused into the semiconductor substrate 1 to form a p-type impurity diffusion layer 4.
  • impurity diffusion methods include thermal diffusion.
  • Examples of the heating method for thermal diffusion include the method exemplified above as a heating method for p-type impurities.
  • the p-type impurity diffusion composition pattern 3 formed on the surface of the semiconductor substrate 1 is removed.
  • the removal method include known etching methods.
  • the material used for etching is preferably one containing an etching component and water or an organic solvent, for example.
  • etching components include hydrogen fluoride, ammonium, phosphoric acid, sulfuric acid, and nitric acid.
  • the impurity diffusion composition of the present invention and a semiconductor device using the same can be used in photovoltaic devices such as solar cells, and semiconductor devices in which impurity diffusion regions are patterned on the semiconductor surface, such as transistor arrays, diode arrays, and photodiode arrays. , it can also be expanded to transducers, etc.
  • the method for manufacturing a solar cell of the present invention includes a step of manufacturing a semiconductor element by the method described above, a step of forming a passivation layer, and a step of forming an electrode.
  • FIG. 2 shows an example of an embodiment of the method for manufacturing a solar cell of the present invention.
  • a method for manufacturing a solar cell will be described below with reference to FIG. 2.
  • the solar cell obtained in this example embodiment is a single-sided power generation solar cell.
  • a semiconductor element having a p-type impurity diffusion layer 2 and a p-type impurity diffusion layer 4 is prepared on a semiconductor element substrate 1, and as shown in (b) of FIG.
  • a passivation layer 5 is formed on the front surface, and a passivation layer 6 is formed on the back surface.
  • Examples of the passivation layer and its formation method include those exemplified as the protective layer in International Publication No. 2016/136474.
  • the passivation layer 5 is partially opened by etching a photoresist in the region of the light receiving surface, and the passivation layer 6 is formed on the entire back surface.
  • a contact electrode 7 is formed in the opening of the passivation layer 5 on the light receiving surface.
  • the electrode can be formed by applying an electrode forming paste and then subjecting it to heat treatment.
  • the semiconductor device manufacturing method and the solar cell manufacturing method of the present invention are not limited to the above-described embodiments, and modifications such as various design changes can be made based on the knowledge of those skilled in the art. Embodiments with such modifications are also included within the scope of the present invention.
  • KBM-13 Methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
  • KBM-103 Phenyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
  • GBL ⁇ -butyrolactone.
  • Synthesis Example 1 (Synthesis of PVA-1) Into a reaction vessel equipped with a reflux condenser, a dropping funnel, and a stirrer, 1,500 parts by mass of vinyl acetate, 648 parts by mass of methanol, and 0.33 mol% of azobisisobutyronitrile (based on the charged vinyl acetate) were charged, The temperature was raised under a nitrogen stream while stirring, and polymerization was started at 60°C. When the polymerization rate of vinyl acetate reaches 90%, m-dinitrobenzene is added to terminate the polymerization, and unreacted vinyl acetate monomer is removed from the system by blowing methanol vapor into the polymer. A methanol solution of vinyl acetate was prepared.
  • the above methanol solution was further diluted with methanol, adjusted to a concentration of 30% by mass, and charged into a kneader. While maintaining the solution temperature at 35°C, a 2% by mass methanol solution of sodium hydroxide was added to the vinyl acetate in the copolymer. Saponification was performed by adding Na at a ratio of 3.40 mmol per 1 mole of the structural unit. As the saponification progressed, the saponified product precipitated, and when it became particulate, it was filtered off, thoroughly washed with methanol, and dried in a hot air dryer to obtain the target PVA-1.
  • the saponification degree of the obtained PVA-1 was measured by the back titration method according to JIS K 6726 (1994) and was found to be 78 mol%. Further, the average degree of polymerization measured by the back titration method according to JIS K 6726 (1994) was 1,400.
  • Synthesis Examples 2 to 25 (Synthesis of PVA-2 to PVA-25) Except for the input amount of azobisisobutyronitrile (ratio to vinyl acetate charged) and the amount of Na in the 2% by mass methanol solution of sodium hydroxide (1 mol of vinyl acetate structural unit) as shown in Table 1.
  • PVA-2 to PVA25 were produced in the same manner as in Synthesis Example 1.
  • Table 1 shows the results of measuring the degree of saponification and average degree of polymerization of PVA-2 to PVA25 obtained in the same manner as in Synthesis Example 1.
  • Synthesis Example 26 (Preparation of siloxane solution A) A 500 mL three-necked flask was charged with 164.93 g of KBM-13, 204.07 g of KBM-103, and 363.03 g of GBL, and while stirring at 40°C, a formic acid aqueous solution prepared by dissolving 1.215 g of formic acid in 130.76 g of water was added at 30 °C. It was added over a period of minutes. After the dropwise addition was completed, the mixture was stirred at 40°C for 1 hour, then heated to 70°C, and stirred for 30 minutes. Thereafter, the temperature of the oil bath was raised to 115°C.
  • the internal temperature of the solution reached 100°C, and from there it was heated and stirred for 1 hour (internal temperature was 100 to 110°C).
  • the obtained solution was cooled in an ice bath to obtain a siloxane solution.
  • the solid content concentration of the siloxane solution was 39.8% by mass, and the moisture content was 4.5% by mass.
  • a semiconductor substrate made of n-type single crystal silicon with a side of 156 mm was prepared as a substrate, and both surfaces were alkali-etched to remove slice damage and natural oxides. At this time, numerous uneven textures having a typical width of about 40 to 100 ⁇ m and depth of about 3 to 4 ⁇ m were formed on both sides of the semiconductor substrate, and this was used as a substrate.
  • This substrate was placed in a diffusion furnace (manufactured by Koyo Thermo Systems Co., Ltd.), and boron bromide (BBr 3 ) was bubbled with nitrogen at 0.06 L/min in an atmosphere of 19 L/min of nitrogen and 0.6 L/min of oxygen.
  • the inside of the furnace was made into an atmosphere containing a p-type impurity diffusion component by flowing the atmosphere, and the temperature was maintained at 950° C. for 30 minutes to form a p-type impurity diffusion layer over the entire surface of the substrate.
  • the substrate was immersed in a 5% by weight hydrofluoric acid aqueous solution at 23° C. for 1 minute to clean the surface.
  • the substrate after impurity diffusion was subjected to p/n determination using a p/n determination device, and the sheet resistance value was measured using a four-probe surface resistance measuring device RT-70V (manufactured by Napson Co., Ltd.).
  • the substrate was an n-type silicon wafer with p-type impurities diffused therein, and its sheet resistance value was 50 ⁇ .
  • a screen printing machine (Microtech Co., Ltd. TM-750 model) and a screen mask (manufactured by SUS Co., Ltd., 400 mesh) were applied to the surface of this substrate where the p-type impurity was diffused.
  • the impurity diffusion compositions obtained in Examples and Comparative Examples were printed on the entire surface by screen printing. Thereafter, the substrate was heated in the air on a hot plate at 200° C. for 5 minutes and then in an oven at 230° C. for 30 minutes to form a pattern of an impurity diffusion composition film having a thickness of about 4 ⁇ m.
  • the substrate after thermal diffusion was immersed in a 5% by weight hydrofluoric acid aqueous solution at 23° C. for 1 minute to peel off the diffusing agent and mask.
  • the substrate after impurity diffusion was subjected to p/n determination using a p/n determination device, and the sheet resistance value was measured using a four-probe surface resistance measuring device RT-70V (manufactured by Napson Co., Ltd.). .
  • the sheet resistance value is measured at 25 points (A to Y) shown in Figure 3, and the average value is the sheet resistance value, and (maximum value - minimum value)/average value x 100 (%) is the resistance value. It was defined as uniformity.
  • the sheet resistance value is an index of impurity diffusibility, and it can be said that the smaller the resistance value, the greater the amount of impurity diffusion, and the higher the concentration.
  • the resistance was 10 ⁇ or more lower than that of the substrate (sheet resistance value: 50 ⁇ )
  • it was considered to be a pass and if it was less than that, it was judged to be a fail.
  • resistance value uniformity of 25% or less was considered to be passed, and when it exceeded it, it was judged to be failed.
  • Example 1 11.63 g of PVA-2 obtained in Synthesis Example 2, 1.31 g of boric acid, 5.84 g of siloxane solution obtained in Synthesis Example 26, silicon oxide fine particles "Aerosil (registered trademark)" VPNKC130 (Nippon Aerosil Co., Ltd.) 3.02 g (manufactured by: number average particle diameter 200 nm), 24.64 g of GBL, and 35.10 g of terpineol were mixed and thoroughly stirred to become uniform, to obtain Impurity Diffusion Composition 1.
  • Examples 2 to 60, Comparative Examples 1 to 5 PVA, boric acid, Aerosil, siloxane solution, water, GBL and other solvents were blended in the proportions shown in Tables 2 to 5 to obtain impurity diffusion compositions 2 to 65.
  • compositions of each example and comparative example are shown in Table 2, and the main compositions and evaluation results are shown in Tables 5 to 9.

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Abstract

The present invention provides an impurity diffusion composition which contains (A) a polyvinyl alcohol that has a saponification degree of not less than 30% by mole but less than 70% by mole, (B) an impurity diffusion component and (C) inorganic fine particles, wherein 0.01 part by mass to 27.5 parts by mass of the inorganic fine particles (C) are contained relative to 100 parts by mass of the polyvinyl alcohol (A). This impurity diffusion composition enables uniform impurity diffusion at a high concentration even in the case of diffusion into a substrate that has been provided with an impurity diffusion layer in advance.

Description

不純物拡散組成物、それを用いた半導体素子の製造方法および太陽電池の製造方法Impurity diffusion composition, method for manufacturing a semiconductor device using the same, and method for manufacturing a solar cell
　本発明は、半導体基板において不純物を拡散させるための不純物拡散組成物、それを用いた半導体素子の製造方法および太陽電池の製造方法に関する。 The present invention relates to an impurity diffusion composition for diffusing impurities in a semiconductor substrate, a method for manufacturing a semiconductor element, and a method for manufacturing a solar cell using the composition.
　近年、電極との接触抵抗を低くし、かつ、キャリアの再結合を抑制するために、選択エミッタ構造の太陽電池が提案されている（例えば、非特許文献１、特許文献１参照）。例えば、ｎ型シリコン基板をベースとする選択エミッタ構造の太陽電池には、受光面側のｐ型拡散層において、電極直下に高濃度ｐ型拡散層（ｐ＋＋層）が形成され、電極直下以外の受光面に低濃度から中濃度のｐ型拡散層（ｐ＋層）が形成される。この時、ｐ＋＋層とｐ＋層のシート抵抗値に１０Ω以上の差があると、太陽電池の光電変換効率が向上する。とりわけ、ｎ型基板表面全体にあらかじめｐ＋層を形成し、その上に不純物拡散成分を含んだ塗液を用いて選択的にパターンを形成し、熱処理をすることで塗液パターン部分にｐ＋＋層を形成する方法（例えば、特許文献２参照）などは、塗液からｐ＋層への不純物のコンタミネーションが小さく、光電変換効率向上の有望な方法として提案されている。 In recent years, solar cells with a selective emitter structure have been proposed in order to reduce contact resistance with electrodes and suppress carrier recombination (see, for example, Non-Patent Document 1 and Patent Document 1). For example, in a solar cell with a selective emitter structure based on an n-type silicon substrate, a high-concentration p-type diffusion layer (p ++ layer) is formed directly under the electrode in the p-type diffusion layer on the light-receiving surface side. A p-type diffusion layer (p + layer) with a low to medium concentration is formed on the light-receiving surface of the substrate. At this time, if there is a difference of 10Ω or more between the sheet resistance values of the p ++ layer and the p + layer, the photoelectric conversion efficiency of the solar cell will improve. In particular, by forming a p + layer in advance on the entire surface of an n-type substrate, selectively forming a pattern on it using a coating liquid containing an impurity diffusion component, and performing heat treatment, p ++ is applied to the coating liquid pattern area. A method of forming a layer (for example, see Patent Document 2) has been proposed as a promising method for improving photoelectric conversion efficiency because it causes less contamination of impurities from the coating liquid to the p + layer.
　半導体基板に不純物拡散層を形成するための不純物拡散用塗布液としては、例えば、ポリビニルアルコール系樹脂（Ａ）、不純物（Ｂ）、および沸点が１００℃以上の多価アルコール（Ｃ）を含有し、該多価アルコール（Ｃ）の含有量が塗布液中の７０重量％以上であることを特徴とする不純物拡散用塗布液（例えば、特許文献３参照）、（Ａ）特定の構造を側鎖に含むポリマー、および、（Ｂ）不純物拡散成分を含有する不純物拡散組成物（例えば、特許文献４参照）などが提案されている。 An impurity diffusion coating liquid for forming an impurity diffusion layer on a semiconductor substrate may contain, for example, a polyvinyl alcohol resin (A), an impurity (B), and a polyhydric alcohol (C) with a boiling point of 100° C. or higher. , a coating liquid for impurity diffusion characterized in that the content of the polyhydric alcohol (C) is 70% by weight or more in the coating liquid (for example, see Patent Document 3), (A) a specific structure with a side chain impurity diffusion compositions (for example, see Patent Document 4) have been proposed, which include a polymer contained in (B) and an impurity diffusion component (B).
特開２００４－１９３３５０号公報Japanese Patent Application Publication No. 2004-193350 国際公開第２０２０／１１６３４０号International Publication No. 2020/116340 特開２０１３－８９５３号公報Japanese Patent Application Publication No. 2013-8953 国際公開第２０１９／１７６７１６号International Publication No. 2019/176716
　しかしながら、上記従来の不純物拡散組成物を用いた場合、不純物拡散層があらかじめ形成されている基板への拡散において、円滑な拡散が起こりにくく、基板と比較してシート抵抗値が１０Ω以上低い高濃度の不純物拡散層を部分的に形成することが困難である、高濃度の不純物拡散層の基板面内における抵抗値のばらつきが大きいなど、異なる濃度の不純物拡散領域を形成する上での課題があった。 However, when using the above-mentioned conventional impurity diffusion composition, smooth diffusion is difficult to occur when diffusing into a substrate on which an impurity diffusion layer has been formed in advance, and the sheet resistance value is 10Ω or more lower than that of the substrate. There are challenges in forming impurity diffusion regions with different concentrations, such as difficulty in partially forming impurity diffusion layers with different concentrations, and large variations in the resistance value within the substrate surface of the high concentration impurity diffusion layer. Ta.
　本発明は、上述のような事情に基づいてなされたものであり、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度で均一な不純物拡散を可能とする不純物拡散組成物を提供することを目的とする。 The present invention has been made based on the above-mentioned circumstances, and provides an impurity diffusion composition that enables uniform impurity diffusion at a high concentration even when diffusing into a substrate on which an impurity diffusion layer is previously formed. The purpose is to provide.
＜１＞（Ａ）ケン化度が３０モル％以上７０モル％未満であるポリビニルアルコール、（Ｂ）不純物拡散成分および（Ｃ）無機微粒子を含有する不純物拡散組成物であって、前記（Ａ）ポリビニルアルコール１００質量部に対して（Ｃ）無機微粒子を０．０１～２７．５質量部含有する不純物拡散組成物。
＜２＞前記（Ｂ）不純物拡散成分としてホウ素化合物を含有する＜１＞に記載の不純物拡散組成物。
＜３＞前記（Ａ）ポリビニルアルコールの平均重合度が１００以上１，０００以下である＜１＞または＜２＞に記載の不純物拡散組成物。
＜４＞前記（Ａ）ポリビニルアルコールの平均重合度Ｎとケン化度Ｘが下記式（Ｙ１）の関係を満たす＜１＞～＜３＞のいずれかに記載の不純物拡散組成物。
２．５×（７０－Ｘ）＋１００≦Ｎ≦１２．５×（７０－Ｘ）＋５００　（Ｙ１）
＜５＞さらに（Ｄ）溶剤を含有し、（Ｄ）溶剤として下記一般式（１）で表される構造を有する溶剤を含有する＜１＞～＜４＞のいずれかに記載の不純物拡散組成物。 <1> An impurity diffusion composition containing (A) polyvinyl alcohol having a saponification degree of 30 mol% or more and less than 70 mol%, (B) an impurity diffusion component, and (C) inorganic fine particles, the impurity diffusion composition comprising (A) An impurity diffusion composition containing 0.01 to 27.5 parts by mass of (C) inorganic fine particles per 100 parts by mass of polyvinyl alcohol.
<2> The impurity diffusion composition according to <1>, which contains a boron compound as the impurity diffusion component (B).
<3> The impurity diffusion composition according to <1> or <2>, wherein the polyvinyl alcohol (A) has an average degree of polymerization of 100 or more and 1,000 or less.
<4> The impurity diffusion composition according to any one of <1> to <3>, wherein the average degree of polymerization N and the degree of saponification X of the polyvinyl alcohol (A) satisfy the relationship of the following formula (Y1).
2.5×(70-X)+100≦N≦12.5×(70-X)+500 (Y1)
<5> The impurity diffusion composition according to any one of <1> to <4>, further comprising (D) a solvent, and (D) a solvent having a structure represented by the following general formula (1) as the solvent. thing.
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
上記一般式（１）中、Ｒ１は、水素、水酸基または炭素数１～３の１価の有機基を表す。Ｒ２～Ｒ６は、それぞれ同じでも異なってもよく、水素または炭素数１～３の１価の有機基を表す。
＜６＞前記一般式（１）で表される構造を有する溶剤を、（Ｄ）溶剤全１００質量部中、５～９０質量部含有する＜５＞に記載の不純物拡散組成物。
＜７＞（Ｄ）溶剤としてさらに水を含有する＜５＞または＜６＞に記載の不純物拡散組成物。
＜８＞前記水を、（Ｄ）溶剤全１００質量部中、０．２～３質量部含有する＜７＞に記載の不純物拡散組成物。
＜９＞アルコキシシラン化合物、シラノール化合物およびシロキサン樹脂の合計含有量が、（Ａ）ポリビニルアルコール１００質量部に対して１５質量部未満である＜１＞～＜８＞のいずれかに記載の不純物拡散組成物。
＜１０＞半導体基板に＜１＞～＜９＞のいずれかに記載の不純物拡散組成物を塗布して不純拡散組成物パターンを形成する工程、および、前記不純物拡散組成物パターンから不純物を拡散させて半導体基板に不純物拡散層を形成する工程を含む半導体素子の製造方法。
＜１１＞半導体基板が、請求項＜１＞～＜９＞のいずれかに記載の不純物拡散組成物と同型の不純物が表面に拡散されている基板である＜１０＞に記載の半導体素子の製造方法。
＜１２＞半導体基板上に２水準以上の異なる不純物濃度の不純物拡散層を形成する工程を含む＜１０＞または＜１１＞に記載の半導体素子の製造方法。
＜１３＞＜１０＞～＜１２＞のいずれかに記載の方法により半導体素子を製造する工程、パッシベーション層形成工程および電極形成工程を含む太陽電池の製造方法。 In the above general formula (1), R 1 represents hydrogen, a hydroxyl group, or a monovalent organic group having 1 to 3 carbon atoms. R 2 to R 6 may be the same or different, and each represents hydrogen or a monovalent organic group having 1 to 3 carbon atoms.
<6> The impurity diffusion composition according to <5>, which contains 5 to 90 parts by mass of the solvent having the structure represented by the general formula (1), based on the total 100 parts by mass of the solvent (D).
<7>(D) The impurity diffusion composition according to <5> or <6>, further containing water as a solvent.
<8> The impurity diffusion composition according to <7>, which contains the water in an amount of 0.2 to 3 parts by mass based on 100 parts by mass of the total solvent (D).
<9> Impurity diffusion according to any one of <1> to <8>, wherein the total content of the alkoxysilane compound, silanol compound, and siloxane resin is less than 15 parts by mass based on 100 parts by mass of (A) polyvinyl alcohol. Composition.
<10> Applying the impurity diffusion composition according to any one of <1> to <9> on a semiconductor substrate to form an impurity diffusion composition pattern, and diffusing impurities from the impurity diffusion composition pattern. A method for manufacturing a semiconductor device, including a step of forming an impurity diffusion layer on a semiconductor substrate.
<11> Manufacturing the semiconductor element according to <10>, wherein the semiconductor substrate is a substrate on which the same type of impurity as the impurity diffusion composition according to any one of claims <1> to <9> is diffused. Method.
<12> The method for manufacturing a semiconductor element according to <10> or <11>, including the step of forming impurity diffusion layers having two or more different impurity concentrations on the semiconductor substrate.
<13> A method for manufacturing a solar cell, comprising a step of manufacturing a semiconductor element by the method according to any one of <10> to <12>, a step of forming a passivation layer, and a step of forming an electrode.
　本発明によれば、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度で均一な不純物拡散を可能とする不純物拡散組成物を提供することができる。 According to the present invention, it is possible to provide an impurity diffusion composition that enables uniform impurity diffusion at a high concentration even when diffusing into a substrate on which an impurity diffusion layer is previously formed.
本発明の実施形態にかかる半導体素子の製造方法を示す工程断面図である。1A and 1B are process cross-sectional views showing a method for manufacturing a semiconductor device according to an embodiment of the present invention. 本発明の実施形態にかかる太陽電池の製造方法を示す工程断面図である。FIG. 1 is a process cross-sectional view showing a method for manufacturing a solar cell according to an embodiment of the present invention. 実施例における抵抗値の測定位置を示す図である。It is a figure showing the measurement position of the resistance value in an example. 実施例におけるＰＶＡ－１～２５の平均重合度Ｎおよびケン化度Ｘの関係を示す図である。FIG. 3 is a diagram showing the relationship between the average degree of polymerization N and saponification degree X of PVA-1 to PVA-25 in Examples.
　以下、本発明の不純物拡散組成物、これを用いた半導体素子および太陽電池の製造方法の好適な実施形態を、必要に応じて図面を参照しながら詳細に説明する。なお、本発明は、これらの実施形態により限定されるものではない。 Hereinafter, preferred embodiments of the impurity diffusion composition of the present invention, a semiconductor device using the same, and a method for manufacturing a solar cell will be described in detail with reference to the drawings as necessary. Note that the present invention is not limited to these embodiments.
　本発明の不純物拡散組成物は、（Ａ）ケン化度が３０モル％以上７０モル％未満であるポリビニルアルコール（以下、「（Ａ）ＰＶＡ」と略記する場合がある）、（Ｂ）不純物拡散成分および（Ｃ）無機微粒子を含有する。（Ｂ）不純物拡散成分は、不純物拡散層を形成するための成分であり、（Ａ）ＰＶＡは、（Ｂ）不純物拡散成分と錯体を形成し、均一な不純物拡散層を形成する作用を有する。本発明においては、ＰＶＡのケン化度を３０モル％以上７０モル％未満とすることにより、不純物拡散組成物中における（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性を高め、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度の拡散を促進し、不純物拡散層の均一性を向上させることができる。（Ｃ）無機微粒子は、従来、不純物拡散組成物にチクソ性を付与し、スクリーン印刷などによる不純物拡散組成物の塗布において、塗布性を向上させる成分として知られていた。しかしながら、本発明者らの検討により、ＰＶＡのケン化度を前述の範囲にすることにより（Ｂ）不純物拡散成分との錯体を形成しても、（Ｃ）無機微粒子の含有量が（Ａ）ＰＶＡ１００質量部に対して２７．５質量部を超えると、粒子表面の作用によって（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性が低下し、高濃度の不純物拡散層の形成が困難となることを見いだした。とりわけ、基板表面に不純物拡散層があらかじめ形成されている場合、この層の影響によって、塗布した不純物拡散組成物からの不純物拡散が大きく阻害される傾向にあるため、（Ａ）ＰＶＡ、（Ｂ）不純物拡散成分、（Ｃ）無機微粒子の相互作用によって錯体をより一層安定化することが、高濃度の不純物拡散層の形成にとってより重要となる。そこで、本発明においては、（Ｃ）無機微粒子の含有量を（Ａ）ＰＶＡ１００質量部に対して０．０１～２７．５質量部とすることにより、（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性を高め、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度の拡散を促進し、不純物拡散層の均一性を向上させることができる。 The impurity diffusion composition of the present invention comprises (A) polyvinyl alcohol having a saponification degree of 30 mol% or more and less than 70 mol% (hereinafter sometimes abbreviated as "(A) PVA"), (B) impurity diffusion component and (C) inorganic fine particles. (B) The impurity diffusion component is a component for forming an impurity diffusion layer, and (A) PVA forms a complex with the (B) impurity diffusion component to form a uniform impurity diffusion layer. In the present invention, by setting the degree of saponification of PVA to 30 mol% or more and less than 70 mol%, the stability of the complex of (A) PVA and (B) impurity diffusion component in the impurity diffusion composition is increased, Even in the case of diffusion into a substrate on which an impurity diffusion layer has been formed in advance, high concentration diffusion can be promoted and the uniformity of the impurity diffusion layer can be improved. (C) Inorganic fine particles have been conventionally known as a component that imparts thixotropy to an impurity diffusion composition and improves the coating properties when applying the impurity diffusion composition by screen printing or the like. However, as a result of the studies conducted by the present inventors, by setting the degree of saponification of PVA within the above-mentioned range, even if a complex is formed with (B) the impurity diffusion component, the content of (C) inorganic fine particles is reduced to (A). When the amount exceeds 27.5 parts by mass based on 100 parts by mass of PVA, the stability of the complex between (A) PVA and (B) impurity diffusion component decreases due to the action of the particle surface, and the formation of a highly concentrated impurity diffusion layer is caused. I found it difficult. In particular, when an impurity diffusion layer is previously formed on the substrate surface, the influence of this layer tends to greatly inhibit impurity diffusion from the applied impurity diffusion composition. It is more important to further stabilize the complex through the interaction of the impurity diffusion component and (C) inorganic fine particles in order to form a highly concentrated impurity diffusion layer. Therefore, in the present invention, by setting the content of (C) inorganic fine particles to 0.01 to 27.5 parts by mass with respect to 100 parts by mass of (A) PVA, it is possible to combine (A) PVA and (B) impurity diffusion components. It is possible to enhance the stability of the complex with the impurity diffusion layer, promote high concentration diffusion even in a substrate on which an impurity diffusion layer has been formed, and improve the uniformity of the impurity diffusion layer.
　（Ａ）ケン化度が３０モル％以上７０モル％未満であるポリビニルアルコール
　前述のとおり、（Ａ）ＰＶＡは、（Ｂ）不純物拡散成分と錯体を形成し、均一な不純物拡散層を形成するための成分である。ＰＶＡのケン化度を３０モル％以上７０モル％未満とすることにより、不純物拡散組成物中における（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性を高め、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度の拡散を促進し、不純物拡散層の均一性を向上させることができる。ケン化度が３０モル％未満であると、錯体の形成が十分でなく、不純物拡散層があらかじめ形成されている基板への高濃度の拡散が不十分となり、また、不純物拡散層の均一性が低下する。ケン化度は、３５モル％以上が好ましく、高濃度の拡散をより促進し、不純物拡散層の均一性をより向上させる観点から、４０モル％以上がより好ましい。一方、ケン化度が７０モル％以上であると、形成した錯体が安定化せずに不純物拡散組成物中で凝集し、やはり、不純物拡散層があらかじめ形成されている基板への高濃度の拡散が不十分となり、また、不純物拡散層の均一性が低下する。ケン化度は、６５モル％未満が好ましく、高濃度の拡散をより促進し、不純物拡散層の均一性をより向上させる観点から、６０モル％未満がより好ましく、５５モル％未満がより好ましい。 (A) Polyvinyl alcohol whose degree of saponification is 30 mol% or more and less than 70 mol% As mentioned above, (A) PVA forms a complex with (B) impurity diffusion component to form a uniform impurity diffusion layer. It is a component of By setting the degree of saponification of PVA to 30 mol% or more and less than 70 mol%, the stability of the complex of (A) PVA and (B) impurity diffusion component in the impurity diffusion composition is increased, and the impurity diffusion layer is In the case of diffusion into the substrate where the impurity is formed, it is possible to promote high-concentration diffusion and improve the uniformity of the impurity diffusion layer. If the degree of saponification is less than 30 mol%, the formation of a complex will not be sufficient, and the diffusion of high concentration into the substrate on which the impurity diffusion layer has been formed will be insufficient, and the uniformity of the impurity diffusion layer will be poor. descend. The degree of saponification is preferably 35 mol% or more, and more preferably 40 mol% or more from the viewpoint of further promoting high concentration diffusion and further improving the uniformity of the impurity diffusion layer. On the other hand, if the degree of saponification is 70 mol% or more, the formed complex will not be stabilized and will aggregate in the impurity diffusion composition, resulting in high concentration diffusion into the substrate on which the impurity diffusion layer has been formed in advance. In addition, the uniformity of the impurity diffusion layer decreases. The degree of saponification is preferably less than 65 mol%, more preferably less than 60 mol%, and more preferably less than 55 mol% from the viewpoint of further promoting high concentration diffusion and further improving the uniformity of the impurity diffusion layer.
　ここで、ＰＶＡのケン化度は、ＪＩＳ　Ｋ　６７２６（１９９４年）の逆滴定法により測定することができる。２種以上のＰＶＡを含有する場合、ＰＶＡのケン化度とは、２種以上のＰＶＡ全体としてのケン化度を意味する。 Here, the degree of saponification of PVA can be measured by the back titration method of JIS K 6726 (1994). When containing two or more types of PVA, the degree of saponification of PVA means the degree of saponification of the two or more types of PVA as a whole.
　（Ａ）ＰＶＡの平均重合度は、１００以上１，０００以下が好ましく、不純物拡散組成物中における錯体安定性をより向上させ、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度の拡散をより促進し、不純物拡散層の均一性をより向上させることができる。 (A) The average degree of polymerization of PVA is preferably 100 or more and 1,000 or less, which further improves the stability of the complex in the impurity diffusion composition, and also allows for high diffusion into a substrate on which an impurity diffusion layer is formed in advance. It is possible to further promote concentration diffusion and further improve the uniformity of the impurity diffusion layer.
　ここで、ＰＶＡの平均重合度は、ＪＩＳ　Ｋ　６７２６（１９９４年）の逆滴定法により測定することができる。２種以上のＰＶＡを含有する場合、ＰＶＡの平均重合度とは、２種以上のＰＶＡ全体としての平均重合度を意味する。 Here, the average degree of polymerization of PVA can be measured by the back titration method according to JIS K 6726 (1994). When two or more types of PVA are contained, the average degree of polymerization of PVA means the average degree of polymerization of the two or more types of PVA as a whole.
　（Ａ）ＰＶＡの平均重合度Ｎとケン化度Ｘは、下記式（Ｙ１）の関係を満たすことが好ましく、不純物拡散組成物中における錯体安定性をより向上させ、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度の拡散をより促進し、不純物拡散層の均一性をより向上させることができる。
２．５×（７０－Ｘ）＋１００≦Ｎ≦１２．５×（７０－Ｘ）＋５００　（Ｙ１）
式（Ｙ１）は、ＰＶＡのケン化度Ｘが大きくなるほど、一定の範囲で平均重合度Ｎが小さいことが好ましいことを示している。式（Ｙ１）の範囲において、形成した錯体をより安定化することができ、不純物拡散組成物中における凝集や会合を抑止する効果をより高めることができる。（Ａ）ＰＶＡの平均重合度Ｎとケン化度Ｘは、下記式（Ｙ２）の関係を満たすことがより好ましい。
２．５×（５０－Ｘ）＋２１０≦Ｎ≦１２．５×（５０－Ｘ）＋５００　（Ｙ２）。 (A) It is preferable that the average degree of polymerization N and saponification degree X of PVA satisfy the relationship of the following formula (Y1), which further improves the stability of the complex in the impurity diffusion composition and prevents the impurity diffusion layer from being formed in advance. Even in the case of diffusion into a substrate containing an impurity, high concentration diffusion can be further promoted, and the uniformity of the impurity diffusion layer can be further improved.
2.5×(70-X)+100≦N≦12.5×(70-X)+500 (Y1)
Formula (Y1) indicates that as the saponification degree X of PVA increases, it is preferable that the average degree of polymerization N decrease within a certain range. Within the range of formula (Y1), the formed complex can be further stabilized, and the effect of suppressing aggregation and association in the impurity diffusion composition can be further enhanced. (A) It is more preferable that the average degree of polymerization N and the degree of saponification X of PVA satisfy the relationship of the following formula (Y2).
2.5×(50-X)+210≦N≦12.5×(50-X)+500 (Y2).
　不純物拡散組成物におけるＰＶＡの含有量は、高濃度の不純物拡散層の均一性をより向上させる観点から、１質量％以上が好ましく、５質量％以上がより好ましく、１０質量％以上がより好ましい。一方、ＰＶＡの含有量は、同様の観点から、３０質量％以下が好ましく、２５質量％以下がより好ましく、２０質量％以下がさらに好ましい。 The content of PVA in the impurity diffusion composition is preferably 1% by mass or more, more preferably 5% by mass or more, and more preferably 10% by mass or more, from the viewpoint of further improving the uniformity of the high concentration impurity diffusion layer. On the other hand, from the same viewpoint, the content of PVA is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.
　（Ｂ）不純物拡散成分
　（Ｂ）不純物拡散成分は、不純物拡散層を形成するための成分である。ｐ型の不純物拡散成分としては、１３属の元素を含む化合物が好ましく、ホウ素化合物がより好ましい。ｎ型の不純物拡散成分としては、１５族の元素を含む化合物が好ましく、リン化合物がより好ましい。これらの中でも、（Ａ）ＰＶＡとより安定な錯体を形成し、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度の拡散をより促進し、不純物拡散層の均一性をより向上させる観点から、ホウ素化合物が好ましい。 (B) Impurity Diffusion Component (B) Impurity Diffusion Component is a component for forming an impurity diffusion layer. As the p-type impurity diffusion component, a compound containing an element of group 13 is preferable, and a boron compound is more preferable. As the n-type impurity diffusion component, a compound containing a Group 15 element is preferable, and a phosphorus compound is more preferable. Among these, (A) forms a more stable complex with PVA, and even when diffusing into a substrate on which an impurity diffusion layer has been formed, it promotes high concentration diffusion and improves the uniformity of the impurity diffusion layer. From the viewpoint of improving the performance, boron compounds are preferred.
　ホウ素化合物としては、例えば、ホウ酸、三酸化二ホウ素、メチルボロン酸、フェニルボロン酸、ホウ酸トリメチル、ホウ酸トリエチル、ホウ酸トリプロピル、ホウ酸トリブチル、ホウ酸トリオクチル、ホウ酸トリフェニル等が挙げられる。これらを２種以上含有してもよい。これらの中でも、ドーピング性の点から、ホウ酸が好ましい。 Examples of boron compounds include boric acid, diboron trioxide, methylboronic acid, phenylboronic acid, trimethyl borate, triethyl borate, tripropyl borate, tributyl borate, trioctyl borate, triphenyl borate, etc. It will be done. Two or more types of these may be contained. Among these, boric acid is preferred from the viewpoint of doping properties.
　リン化合物としては、例えば、五酸化二リン、リン酸、ポリリン酸、リン酸メチル、リン酸ジメチル、リン酸トリメチル、リン酸エチル、リン酸ジエチル、リン酸トリエチル、リン酸プロピル、リン酸ジプロピル、リン酸トリプロピル、リン酸ブチル、リン酸ジブチル、リン酸トリブチル、リン酸フェニル、リン酸ジフェニル、リン酸トリフェニルなどのリン酸エステルや、亜リン酸メチル、亜リン酸ジメチル、亜リン酸トリメチル、亜リン酸エチル、亜リン酸ジエチル、亜リン酸トリエチル、亜リン酸プロピル、亜リン酸ジプロピル、亜リン酸トリプロピル、亜リン酸ブチル、亜リン酸ジブチル、亜リン酸トリブチル、亜リン酸フェニル、亜リン酸ジフェニル、亜リン酸トリフェニルなどの亜リン酸エステルなどが挙げられる。これらを２種以上含有してもよい。これらの中でも、ドーピング性の点から、リン酸、五酸化二リン、ポリリン酸が好ましい。 Examples of phosphorus compounds include diphosphorus pentoxide, phosphoric acid, polyphosphoric acid, methyl phosphate, dimethyl phosphate, trimethyl phosphate, ethyl phosphate, diethyl phosphate, triethyl phosphate, propyl phosphate, dipropyl phosphate, Phosphate esters such as tripropyl phosphate, butyl phosphate, dibutyl phosphate, tributyl phosphate, phenyl phosphate, diphenyl phosphate, triphenyl phosphate, methyl phosphite, dimethyl phosphite, trimethyl phosphite , ethyl phosphite, diethyl phosphite, triethyl phosphite, propyl phosphite, dipropyl phosphite, tripropyl phosphite, butyl phosphite, dibutyl phosphite, tributyl phosphite, phosphorous acid Examples include phosphite esters such as phenyl, diphenyl phosphite, and triphenyl phosphite. Two or more types of these may be contained. Among these, phosphoric acid, diphosphorus pentoxide, and polyphosphoric acid are preferred from the viewpoint of doping properties.
　不純物拡散組成物における不純物拡散成分の含有量は、高濃度の不純物拡散層の均一性をより向上させる観点から、０．１質量％以上が好ましく、０．５質量％がより好ましく、１質量％がより好ましい。一方、不純物拡散組成物における不純物拡散成分の含有量は、同様の観点から、２０質量％以下が好ましく、１０質量％以下がより好ましく、５質量％以下がさらに好ましい。 The content of the impurity diffusion component in the impurity diffusion composition is preferably 0.1% by mass or more, more preferably 0.5% by mass, and 1% by mass from the viewpoint of further improving the uniformity of the high concentration impurity diffusion layer. is more preferable. On the other hand, from the same viewpoint, the content of the impurity diffusion component in the impurity diffusion composition is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.
　（Ｃ）無機微粒子
　（Ｃ）無機微粒子としては、例えば、シリコン、チタン、ゲルマニウム、ジルコニウムやそれらの酸化物、窒化物などの微粒子が挙げられる。これらを２種以上含有してもよい。チクソ性と不純物拡散特性とのバランスの観点から、シリコンやその酸化物、窒化物が好ましく、酸化ケイ素の微粒子がより好ましい。 (C) Inorganic fine particles (C) Examples of the inorganic fine particles include fine particles of silicon, titanium, germanium, zirconium, and their oxides and nitrides. Two or more types of these may be contained. From the viewpoint of the balance between thixotropy and impurity diffusion characteristics, silicon, its oxides, and nitrides are preferred, and silicon oxide fine particles are more preferred.
　（Ｃ）無機微粒子の数平均粒子径は、５ｎｍ以上が好ましく、適度な分子間相互作用により、より高いチクソ性を付与することができる。（Ｃ）無機微粒子の数平均粒子径は、７ｎｍ以上がより好ましく、１０ｎｍ以上がさらに好ましい。一方、（Ｃ）無機微粒子の数平均粒子径は、５００ｎｍ以下が好ましく、適度な分子間相互作用により、より高いチクソ性を付与することができる。（Ｃ）無機微粒子の数平均粒子径は、４００ｎｍ以下がより好ましく、３００ｎｍ以下がさらに好ましく、２５０ｎｍ以下がさらに好ましい。 The number average particle diameter of the inorganic fine particles (C) is preferably 5 nm or more, and higher thixotropy can be imparted through appropriate intermolecular interactions. (C) The number average particle diameter of the inorganic fine particles is more preferably 7 nm or more, and even more preferably 10 nm or more. On the other hand, the number average particle diameter of the inorganic fine particles (C) is preferably 500 nm or less, and higher thixotropy can be imparted through appropriate intermolecular interactions. (C) The number average particle diameter of the inorganic fine particles is more preferably 400 nm or less, further preferably 300 nm or less, and even more preferably 250 nm or less.
　ここで、本発明における（Ｃ）無機微粒子の数平均粒子径とは、粒子の長径の数平均値を言う。具体的には、透過型電子顕微鏡を用いて（Ｃ）無機微粒子を拡大観察し、無作為に選択した１０個の粒子の長径を測定し、その数平均値を算出することにより求めることができる。 Here, the number average particle diameter of the inorganic fine particles (C) in the present invention refers to the number average value of the major diameters of the particles. Specifically, it can be determined by observing (C) inorganic fine particles under magnification using a transmission electron microscope, measuring the long diameter of 10 randomly selected particles, and calculating the number average value. .
　前述のとおり、不純物拡散組成物において、（Ｃ）無機微粒子は、不純物拡散組成物にチクソ性を付与する作用を有するものの、その含有量が（Ａ）ＰＶＡ１００質量部に対して２７．５質量部を超えると、（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性が低下し、高濃度の不純物拡散層の形成が困難となる。そこで、本発明においては、（Ｃ）無機微粒子の含有量を（Ａ）ＰＶＡ１００質量部に対して２７．５質量部以下とすることにより、（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性を高め、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度の拡散を促進し、不純物拡散層の均一性を向上させることができる。 As mentioned above, in the impurity diffusion composition, (C) inorganic fine particles have the effect of imparting thixotropy to the impurity diffusion composition, but the content thereof is 27.5 parts by mass relative to 100 parts by mass of (A) PVA. If it exceeds this, the stability of the complex of (A) PVA and (B) impurity diffusion component decreases, making it difficult to form a highly concentrated impurity diffusion layer. Therefore, in the present invention, by setting the content of (C) inorganic fine particles to 27.5 parts by mass or less with respect to 100 parts by mass of (A) PVA, it is possible to form a complex between (A) PVA and (B) impurity diffusion component. Even in the case of diffusion into a substrate on which an impurity diffusion layer has been formed in advance, it is possible to promote high concentration diffusion and improve the uniformity of the impurity diffusion layer.
　本発明の不純物拡散組成物中における（Ｃ）無機微粒子の含有量は、（Ａ）ＰＶＡ１００質量部に対して、０．０１質量部以上であり、より高いチクソ性を付与し、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度の拡散を促進し、不純物拡散層の均一性を向上させることができる。（Ｃ）無機微粒子の含有量は、０．１質量部以上が好ましく、０．５質量部以上がより好ましく、１質量部以上がより好ましい。さらに、不純物拡散組成物を室温で保存した後にもより高濃度の拡散をより促進する観点から、（Ｃ）無機微粒子の含有量は、３質量部以上がより好ましく、１０質量部以上がさらに好ましく、１５質量部以上がさらに好ましい。一方、（Ｃ）無機微粒子の含有量は、（Ａ）ＰＶＡ１００質量部に対して２５質量部以下が好ましく、さらに、不純物拡散組成物を室温で保存した後にもより高濃度の拡散をより促進する観点から、（Ｃ）無機微粒子の含有量は、２４．５質量部以下がより好ましく、２２．５質量部以下がより好ましい。さらに、不純物拡散組成物を室温で保存した後の高濃度の拡散をより促進する観点から、２０．５質量部以下がさらに好ましい。 The content of (C) inorganic fine particles in the impurity diffusion composition of the present invention is 0.01 parts by mass or more based on 100 parts by mass of (A) PVA, which imparts higher thixotropy and improves the impurity diffusion layer. Even in the case of diffusion into a substrate that has been formed in advance, it is possible to promote high concentration diffusion and improve the uniformity of the impurity diffusion layer. (C) The content of the inorganic fine particles is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more. Furthermore, from the viewpoint of promoting higher concentration diffusion even after the impurity diffusion composition is stored at room temperature, the content of the inorganic fine particles (C) is more preferably 3 parts by mass or more, and even more preferably 10 parts by mass or more. , more preferably 15 parts by mass or more. On the other hand, the content of (C) inorganic fine particles is preferably 25 parts by mass or less with respect to 100 parts by mass of (A) PVA, and furthermore, even after the impurity diffusion composition is stored at room temperature, diffusion at a higher concentration is further promoted. From this point of view, the content of the inorganic fine particles (C) is more preferably 24.5 parts by mass or less, more preferably 22.5 parts by mass or less. Furthermore, from the viewpoint of further promoting high-concentration diffusion after storing the impurity diffusion composition at room temperature, the amount is more preferably 20.5 parts by mass or less.
　（Ｄ）溶剤
　本発明の不純物拡散組成物は、さらに（Ｄ）溶剤を含有することが好ましい。 (D) Solvent The impurity diffusion composition of the present invention preferably further contains (D) a solvent.
　本発明の不純物拡散組成物をスクリーン印刷法やスピンコート印刷法などにより塗布する場合、印刷性を向上させる観点から、（Ｄ）溶剤の沸点は１００℃以上が好ましい。沸点が１００℃以上であると、例えば、スクリーン印刷法により不純物拡散組成物を印刷する際に、不純物拡散組成物が印刷版上で乾燥し固着することを抑制することができる。（Ｄ）溶剤の沸点は、１６０℃以上がより好ましく、１８０℃以上がさらに好ましい。 When applying the impurity diffusion composition of the present invention by a screen printing method, a spin coat printing method, etc., the boiling point of the solvent (D) is preferably 100° C. or higher from the viewpoint of improving printability. When the boiling point is 100° C. or higher, for example, when printing the impurity diffusion composition by screen printing, it is possible to prevent the impurity diffusion composition from drying and fixing on the printing plate. (D) The boiling point of the solvent is more preferably 160°C or higher, and even more preferably 180°C or higher.
　沸点１００℃以上の溶剤としては、例えば、乳酸エチル（沸点１５５℃）、ジアセトンアルコール（沸点１６９℃）、プロピレングリコールモノメチルエーテルアセテート（沸点１４５℃）、プロピレングリコールモノメチルエーテル（沸点１２０℃）、３－メトキシ－３－メチル－１－ブタノール（沸点１７４℃）、γ－ブチロラクトン（沸点２０４℃）、Ｎ－メチル－２－ピロリドン（沸点２０４℃）、Ｎ、Ｎ－ジメチルイミダゾリジノン（沸点２２６℃）、テルピネオール（沸点２１９℃）、１，３－プロパンジオール（２１４℃）などが挙げられる。これらを２種以上含有してもよい。 Examples of solvents with a boiling point of 100°C or higher include ethyl lactate (boiling point 155°C), diacetone alcohol (boiling point 169°C), propylene glycol monomethyl ether acetate (boiling point 145°C), propylene glycol monomethyl ether (boiling point 120°C), -Methoxy-3-methyl-1-butanol (boiling point 174°C), γ-butyrolactone (boiling point 204°C), N-methyl-2-pyrrolidone (boiling point 204°C), N,N-dimethylimidazolidinone (boiling point 226°C) ), terpineol (boiling point 219°C), and 1,3-propanediol (214°C). Two or more types of these may be contained.
　不純物拡散組成物における（Ｄ）溶剤の含有量は、１０質量％以上が好ましく、２０質量％以上がより好ましく、５０質量％以上がさらに好ましく、６５質量％以上がさらに好ましい。一方、（Ｄ）溶剤の含有量は、９５質量％以下が好ましく、９０質量％以下がより好ましく、８５質量％以下がさらに好ましい。 The content of the solvent (D) in the impurity diffusion composition is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 50% by mass or more, and even more preferably 65% by mass or more. On the other hand, the content of the solvent (D) is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.
　不純物拡散組成物の保存安定性をより向上させる観点から、溶剤（Ｄ）として、下記一般式（１）で表される構造を有する溶剤を含有することが好ましい。本発明の不純物拡散組成物に下記一般式（１）で表される構造を有する溶剤を含有することにより、不純物拡散組成物を室温で保存しても、（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性を維持し、不純物拡散層の均一性をより向上させることができる。 From the viewpoint of further improving the storage stability of the impurity diffusion composition, it is preferable that the solvent (D) contains a solvent having a structure represented by the following general formula (1). By containing the solvent having the structure represented by the following general formula (1) in the impurity diffusion composition of the present invention, even if the impurity diffusion composition is stored at room temperature, (A) PVA and (B) impurity diffusion The stability of the complex with the components can be maintained, and the uniformity of the impurity diffusion layer can be further improved.
Figure JPOXMLDOC01-appb-C000003
Figure JPOXMLDOC01-appb-C000003
　上記一般式（１）中、Ｒ１は水素、水酸基または炭素数１～３の１価の有機基を表す。Ｒ２～Ｒ６は、それぞれ同じでも異なってもよく、水素または炭素数１～３の１価の有機基を表す。 In the above general formula (1), R 1 represents hydrogen, a hydroxyl group, or a monovalent organic group having 1 to 3 carbon atoms. R 2 to R 6 may be the same or different, and each represents hydrogen or a monovalent organic group having 1 to 3 carbon atoms.
　炭素数１～３の有機基としては、炭化水素基が好ましく、メチル基、エチル基、プロピル基、イソプロピル基などが挙げられる。 The organic group having 1 to 3 carbon atoms is preferably a hydrocarbon group, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and the like.
　上記一般式（１）で表される構造を有する溶剤としては、例えば、１，３－プロパンジオール（沸点２１４℃）１，３－ブタンジオール（沸点２０７℃）、２－メチル－１，３－プロパンジオール（沸点２１４℃）、グリセロール（沸点２９０℃）、２，２－ジメチル－１，３－プロパンジオール（沸点２１０℃）、３－メチル－１，３－ブタンジオール（沸点２０３℃）、２，４－ペンタンジオール（沸点１９８℃）、１，２，３－ブタントリオール（沸点３１２℃）などが挙げられる。これらを２種以上含有してもよい。 Examples of the solvent having the structure represented by the above general formula (1) include 1,3-propanediol (boiling point 214°C), 1,3-butanediol (boiling point 207°C), 2-methyl-1,3- Propanediol (boiling point 214°C), glycerol (boiling point 290°C), 2,2-dimethyl-1,3-propanediol (boiling point 210°C), 3-methyl-1,3-butanediol (boiling point 203°C), 2 , 4-pentanediol (boiling point 198°C), and 1,2,3-butanetriol (boiling point 312°C). Two or more types of these may be contained.
　前記一般式（１）で表される構造を有する溶剤の含有量は、不純物拡散組成物を室温で保存した場合にも不純物拡散層の均一性をより向上させる観点から、（Ｄ）溶剤全１００質量部中、５質量部以上が好まく、１０質量部以上がより好ましく、２０質量部以上がさらに好ましい。一方、前記一般式（１）で表される構造を有する溶剤の含有量は、（Ｄ）溶剤全１００質量部中、９０質量部以下が好ましく、７０質量部以下がより好ましく、６０質量部以下がより好ましく、５５質量部以下がさらに好ましい。 From the viewpoint of further improving the uniformity of the impurity diffusion layer even when the impurity diffusion composition is stored at room temperature, the content of the solvent having the structure represented by the general formula (1) is determined to be 100% of the total amount of (D) solvent. Among parts by mass, 5 parts by mass or more is preferable, 10 parts by mass or more is more preferable, and even more preferably 20 parts by weight or more. On the other hand, the content of the solvent having the structure represented by the general formula (1) is preferably 90 parts by mass or less, more preferably 70 parts by mass or less, and 60 parts by mass or less out of 100 parts by mass of the total solvent (D). is more preferable, and even more preferably 55 parts by mass or less.
　溶剤（Ｄ）として、前記一般式（１）で表される構造を有する溶剤とともに、脂環式アルコール、モノテルペンアルコール、セスキテルペンアルコールおよび／またはジテルペンアルコールを含有することがより好ましく、不純物拡散組成物を室温で保存しても、（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性を維持し、不純物拡散層の均一性をより向上させることができる。 It is more preferable that the solvent (D) contains an alicyclic alcohol, a monoterpene alcohol, a sesquiterpene alcohol, and/or a diterpene alcohol together with the solvent having the structure represented by the general formula (1), and has an impurity diffusion composition. Even if the product is stored at room temperature, the stability of the complex of (A) PVA and (B) impurity diffusion component can be maintained, and the uniformity of the impurity diffusion layer can be further improved.
　脂環式アルコールとしては、例えば、シクロヘキサノール（沸点１６１℃）、４－ヒドロキシシクロヘキサン－１－オン（沸点２５６℃）などが挙げられる。モノテルペンアルコールとしては、例えば、テルピネオール（沸点２１９℃）、リナロール（沸点１９８℃）、ゲラニオール（沸点２３０℃）、ネロール（沸点２２５℃）、テルピネン－４－オール（沸点２１０℃）、シトロネロール（沸点２２５℃）、Ｌ－メントール（沸点２１２℃）、ラバンジュロール（沸点２０３℃）、ボルネオール（沸点２１３℃）などが挙げられる。セスキテルペンアルコールとしては、例えば、ファルネソール（沸点１１１℃）、パチョロール（沸点１４０℃）、ビリジフロロール（沸点２９０℃）、カジノール（沸点１３９℃）などが挙げられる。ジテルペンアルコールとしては、例えば、スクラレオール（沸点３６０℃）、マノオール（沸点３９０℃）、フィトール（沸点２０４℃）などが挙げられる。これらを２種以上含有してもよい。これらの中でも、モノテルペンアルコール、セスキテルペンアルコール、ジテルペンアルコールがより好ましく、モノテルペンアルコールがさらに好ましい。 Examples of the alicyclic alcohol include cyclohexanol (boiling point 161°C) and 4-hydroxycyclohexan-1-one (boiling point 256°C). Examples of monoterpene alcohols include terpineol (boiling point 219°C), linalool (boiling point 198°C), geraniol (boiling point 230°C), nerol (boiling point 225°C), terpinen-4-ol (boiling point 210°C), citronellol (boiling point 225°C), L-menthol (boiling point 212°C), lavandulol (boiling point 203°C), and borneol (boiling point 213°C). Examples of the sesquiterpene alcohol include farnesol (boiling point 111°C), patcholol (boiling point 140°C), viridiflorol (boiling point 290°C), and casinool (boiling point 139°C). Examples of diterpene alcohols include sclareol (boiling point 360°C), manol (boiling point 390°C), and phytol (boiling point 204°C). Two or more types of these may be contained. Among these, monoterpene alcohol, sesquiterpene alcohol, and diterpene alcohol are more preferred, and monoterpene alcohol is even more preferred.
　前記一般式（１）で表される構造を有する溶剤の含有量（（１）含有量）と、脂環式アルコール、モノテルペンアルコール、セスキテルペンアルコールおよびジテルペンアルコールの合計含有量（アルコール含有量）との合計１００質量部中、（１）含有量は、不純物拡散組成物を室温で保存しても、（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性を維持し、不純物拡散層の均一性をより向上させる観点から、８質量部以上が好ましく、１５質量部以上がより好ましく、２０質量部以上がさらに好ましい。一方、アルコール含有量は、不純物拡散組成物を室温で保存しても、（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性を維持し、不純物拡散層の均一性をより向上させる観点から、９０質量部以下が好ましく、８５質量部以下がより好ましく、５５質量部以下がさらに好ましい。 The content of the solvent having the structure represented by the general formula (1) ((1) content) and the total content of alicyclic alcohol, monoterpene alcohol, sesquiterpene alcohol, and diterpene alcohol (alcohol content) (1) content maintains the stability of the complex of (A) PVA and (B) impurity diffusion component even if the impurity diffusion composition is stored at room temperature, and From the viewpoint of further improving the uniformity of the layer, the amount is preferably 8 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more. On the other hand, the alcohol content maintains the stability of the complex of (A) PVA and (B) impurity diffusion component even when the impurity diffusion composition is stored at room temperature, and further improves the uniformity of the impurity diffusion layer. From the viewpoint, the content is preferably 90 parts by mass or less, more preferably 85 parts by mass or less, and even more preferably 55 parts by mass or less.
　溶剤（Ｄ）として、前記一般式（１）で表される構造を有する溶剤とともに、水を含有することがより好ましく、（Ｄ）溶剤として強い水素結合を形成する水を微量含有することによって、不純物拡散組成物を室温で保存しても、（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性を維持し、不純物拡散組成物を室温で保存した後にもより高濃度の拡散をより促進することができる。 As the solvent (D), it is more preferable to contain water together with the solvent having the structure represented by the general formula (1), and by containing a small amount of water that forms strong hydrogen bonds as the solvent (D), Even when the impurity diffusion composition is stored at room temperature, the stability of the complex between (A) PVA and (B) impurity diffusion component is maintained, and even after the impurity diffusion composition is stored at room temperature, a higher concentration of diffusion is achieved. This can be further promoted.
　水の含有量は、（Ｄ）溶剤全１００質量部中、０．２質量部～３質量部が好ましく、０．２～２質量部がより好ましく、０．２～１質量部がさらに好ましい。 The content of water is preferably 0.2 to 3 parts by weight, more preferably 0.2 to 2 parts by weight, and even more preferably 0.2 to 1 part by weight based on the total 100 parts by weight of the solvent (D).
　本発明の不純物拡散組成物は、チクソ性をより向上させる観点から、前記（Ｃ）無機微粒子以外のチクソ剤を含有してもよい。（Ｃ）無機微粒子以外のチクソ剤としては、例えば、国際公開第２０２０／１１６３４０号においてチクソ剤として例示されたもののうち、（Ｃ）無機微粒子以外のものが挙げられる。 The impurity diffusion composition of the present invention may contain a thixotropic agent other than the inorganic fine particles (C) from the viewpoint of further improving thixotropic properties. (C) Examples of thixotropic agents other than inorganic fine particles include those exemplified as thixotropic agents in International Publication No. 2020/116340, other than (C) inorganic fine particles.
　本発明の不純物拡散組成物は、アルコキシシラン化合物、シラノール化合物およびシロキサン樹脂を実質的に含有しないことが好ましく、不純物拡散組成物中における（Ａ）ＰＶＡと（Ｂ）不純物拡散成分との錯体の安定性をより高め、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度の拡散をより促進し、不純物拡散層の均一性をより向上させることができる。具体的には、アルコキシシラン化合物、シラノール化合物およびシロキサン樹脂の合計含有量は、（Ａ）ポリビニルアルコール１００質量部に対して１５質量部未満が好ましい。これらの合計含有量は少なければ少ないほどよく、不純物拡散組成物を室温で保存した後、不純物拡散層があらかじめ形成されている基板への拡散においても、高濃度の拡散をより促進する観点から、１０質量部未満がより好ましく、５質量部未満がさらに好ましく、１質量部未満がさらに好ましい。ここで、アルコキシシラン化合物、シラノール化合物およびシロキサン樹脂の合計含有量とは、アルコキシシラン化合物、シラノール化合物またはシロキサン樹脂のいずれか一つを含有する場合はその含有量を、これらを二以上含有する場合はその総含有量をいう。 The impurity diffusion composition of the present invention preferably does not substantially contain an alkoxysilane compound, a silanol compound, and a siloxane resin, and stabilizes the complex of (A) PVA and (B) impurity diffusion component in the impurity diffusion composition. Even in the case of diffusion into a substrate on which an impurity diffusion layer has been formed in advance, diffusion of high concentration can be further promoted, and the uniformity of the impurity diffusion layer can be further improved. Specifically, the total content of the alkoxysilane compound, silanol compound, and siloxane resin is preferably less than 15 parts by mass based on 100 parts by mass of (A) polyvinyl alcohol. The lower the total content of these, the better; from the viewpoint of further promoting high-concentration diffusion even when the impurity diffusion composition is stored at room temperature and diffused into a substrate on which an impurity diffusion layer has been formed in advance. It is more preferably less than 10 parts by weight, even more preferably less than 5 parts by weight, even more preferably less than 1 part by weight. Here, the total content of alkoxysilane compounds, silanol compounds, and siloxane resins refers to the content if any one of alkoxysilane compounds, silanol compounds, or siloxane resins is contained, and the content if two or more of these are contained. refers to its total content.
　本発明の不純物拡散組成物は、例えば、（Ａ）ＰＶＡ、（Ｂ）不純物拡散成分、（Ｃ）無機微粒子および必要に応じて（Ｄ）溶剤、チクソ剤、界面活性剤、増粘剤等の添加物を混合することにより得ることができる。混合温度は、５～９０℃が好ましく、２０～８０℃がより好ましい。混合時間は、１～２０時間が好ましく、２～８時間がより好ましい。 The impurity diffusion composition of the present invention includes, for example, (A) PVA, (B) an impurity diffusion component, (C) inorganic fine particles, and optionally (D) a solvent, thixotropic agent, surfactant, thickener, etc. It can be obtained by mixing additives. The mixing temperature is preferably 5 to 90°C, more preferably 20 to 80°C. The mixing time is preferably 1 to 20 hours, more preferably 2 to 8 hours.
　混合順序としては、（Ｄ）溶剤中に（Ａ）～（Ｃ）および必要に応じてその他添加剤を同時に添加して混合してもよいし、まず、（Ｄ）溶剤中に（Ｃ）無機微粒子を分散させてから（Ａ）ＰＶＡ、（Ｂ）不純物拡散成分および必要に応じてその他添加剤を添加して混合してもよい。まず（Ａ）ＰＶＡと（Ｂ）不純物拡散成分を（Ｄ）溶剤中に添加して混合し、錯体を形成させてから、（Ｃ）無機微粒子および必要に応じてその他添加剤を添加して混合することが好ましい。 As for the mixing order, (A) to (C) and other additives may be added to (D) solvent at the same time and mixed, or (C) inorganic After the fine particles are dispersed, (A) PVA, (B) impurity diffusion component, and other additives as necessary may be added and mixed. First, (A) PVA and (B) impurity diffusion component are added and mixed in (D) solvent to form a complex, and then (C) inorganic fine particles and other additives are added and mixed as necessary. It is preferable to do so.
　＜半導体素子の製造方法＞
　本発明の半導体素子の製造方法は、半導体基板に本発明の不純物拡散組成物を塗布して不純物拡散組成物パターンを形成する工程（以下、「不純物拡散組成物パターン形成工程」と略記する場合がある）と、前記不純物拡散組成物パターンから不純物を拡散させて半導体基板に不純物拡散層を形成する工程（以下、「不純物拡散層形成工程」と略記する場合がある）を含む。選択エミッター形成のため、半導体基板の表面には、不純物拡散組成物と同型の不純物が拡散されていることが好ましい。また、半導体基板上に２水準以上の異なる不純物濃度の不純物拡散層を形成する工程を含むことが好ましい。 <Method for manufacturing semiconductor devices>
The method for manufacturing a semiconductor device of the present invention includes a step of applying the impurity diffusion composition of the present invention to a semiconductor substrate to form an impurity diffusion composition pattern (hereinafter sometimes abbreviated as "impurity diffusion composition pattern forming step"). ) and a step (hereinafter sometimes abbreviated as "impurity diffusion layer forming step") of diffusing impurities from the impurity diffusion composition pattern to form an impurity diffusion layer on the semiconductor substrate. For selective emitter formation, it is preferable that the same type of impurity as the impurity diffusion composition is diffused into the surface of the semiconductor substrate. Further, it is preferable to include a step of forming impurity diffusion layers having two or more different impurity concentrations on the semiconductor substrate.
　図１に、本発明の半導体素子の製造方法の実施形態の一例を示す。以下に、図１を参照しながら、ｐ型不純物拡散組成物を利用してｐ型不純物拡散層を形成する方法について説明する。 FIG. 1 shows an example of an embodiment of the method for manufacturing a semiconductor device of the present invention. Hereinafter, with reference to FIG. 1, a method for forming a p-type impurity diffusion layer using a p-type impurity diffusion composition will be described.
　まず、不純物拡散組成物パターン形成工程について説明する。 First, the impurity diffusion composition pattern forming process will be explained.
　まず、図１の（ａ）に示すように、半導体基板１を用いる。 First, as shown in FIG. 1(a), a semiconductor substrate 1 is used.
　半導体基板としては、例えば不純物濃度が１０１５～１０１６ａｔｏｍｓ／ｃｍ３であるｎ型単結晶シリコン、多結晶シリコン、シリコンにゲルマニウムや炭素などの他の元素が混合されている結晶基板、ｐ型結晶シリコンや、ガリウムヒ素など、シリコン以外の半導体基板などが挙げられる。また、選択エミッター形成のため、あらかじめｎ型単結晶シリコン基板の表面にｐ型不純物拡散層が形成されていてもよい。 Semiconductor substrates include, for example, n-type single crystal silicon with an impurity concentration of 10 15 to 10 16 atoms/cm 3 , polycrystalline silicon, a crystal substrate in which silicon is mixed with other elements such as germanium and carbon, and p-type Examples include semiconductor substrates other than silicon, such as crystalline silicon and gallium arsenide. Further, in order to form selective emitters, a p-type impurity diffusion layer may be formed in advance on the surface of the n-type single crystal silicon substrate.
　半導体基板の厚さは５０～３００μｍが好ましい。半導体基板の形状は、外形が一辺１００～２５０ｍｍの概略四角形が好ましい。また、半導体基板の表面は、フッ酸溶液やアルカリ溶液などによりエッチングされていることが好ましく、スライスダメージや自然酸化膜を除去することができる。 The thickness of the semiconductor substrate is preferably 50 to 300 μm. The shape of the semiconductor substrate is preferably a substantially rectangular outer shape with a side of 100 to 250 mm. Further, the surface of the semiconductor substrate is preferably etched using a hydrofluoric acid solution, an alkaline solution, or the like, so that slice damage and a natural oxide film can be removed.
　次に、図１の（ｂ）に示すように、選択エミッター形成のため、あらかじめ表面にｐ型不純物拡散層２を形成する場合、ｐ型不純物の拡散方法としては、例えば、ｐ型不純物ガス雰囲気中で加熱して熱拡散する方法や、ｐ型不純物拡散組成物を塗布した後に加熱して熱拡散する方法が挙げられる。加熱方法としては、例えば、電気加熱、赤外加熱などによる均一な加熱方法や、レーザ－などによる局所的な加熱方法などが挙げられる。熱拡散の温度および時間は、例えば、８００℃以上１２００℃以下、１～１２０分間が好ましい。熱拡散は、大気中で行ってもよいし、窒素、アルゴンなどの不活性ガスを用いて雰囲気中の酸素量等を適宜調整してもよい。拡散時間短縮の観点から、雰囲気中の酸素濃度を３％以下にすることが好ましい。また、必要に応じて拡散前に２００℃～８５０℃の範囲で焼成を行ってもよい。 Next, as shown in FIG. 1(b), when forming a p-type impurity diffusion layer 2 on the surface in advance for selective emitter formation, the p-type impurity diffusion method may be, for example, a p-type impurity gas atmosphere. Examples include a method in which the p-type impurity diffusion composition is applied and then heated and thermally diffused. Examples of heating methods include uniform heating methods such as electric heating and infrared heating, and local heating methods such as laser heating. The temperature and time of thermal diffusion are preferably, for example, 800° C. or higher and 1200° C. or lower for 1 to 120 minutes. Thermal diffusion may be performed in the atmosphere, or the amount of oxygen in the atmosphere may be adjusted as appropriate using an inert gas such as nitrogen or argon. From the viewpoint of shortening the diffusion time, it is preferable that the oxygen concentration in the atmosphere is 3% or less. Further, if necessary, baking may be performed in the range of 200° C. to 850° C. before diffusion.
　次に、図１の（ｃ）に示すように、ｐ型不純物拡散層２上に本発明のｐ型不純物拡散組成物を部分的に塗布し、ｐ型不純物拡散組成物パターン３を形成する。不純物拡散組成物の塗布方法としては、例えば、スピンコート法、スクリーン印刷法、インクジェット印刷法、スリット塗布法、スプレー塗布法、凸版印刷法、凹版印刷法などが挙げられる。 Next, as shown in FIG. 1C, the p-type impurity diffusion composition of the present invention is partially applied onto the p-type impurity diffusion layer 2 to form a p-type impurity diffusion composition pattern 3. Examples of methods for applying the impurity diffusion composition include spin coating, screen printing, inkjet printing, slit coating, spray coating, letterpress printing, and intaglio printing.
　不純物拡散組成物膜を、ホットプレート、オーブンなどで、５０～２００℃の範囲で３０秒～３０分間乾燥することが好ましい。乾燥後の不純物拡散組成物膜の膜厚は、不純物の拡散性の観点から、１００ｎｍ以上が好ましく、エッチング後の残渣の観点から１０μｍ以下が好ましい。 It is preferable to dry the impurity diffusion composition film at a temperature of 50 to 200°C for 30 seconds to 30 minutes using a hot plate, oven, or the like. The thickness of the impurity diffusion composition film after drying is preferably 100 nm or more from the viewpoint of impurity diffusibility, and preferably 10 μm or less from the viewpoint of the residue after etching.
　次に、不純物拡散層形成工程について説明する。 Next, the impurity diffusion layer forming process will be explained.
　図１の（ｄ）に示すように、不純物を半導体基板１に拡散させ、ｐ型不純物拡散層４を形成する。不純物の拡散方法としては、例えば、熱拡散する方法が挙げられる。熱拡散のための加熱方法としては、ｐ型不純物の加熱方法として先に例示した方法が挙げられる。 As shown in FIG. 1(d), impurities are diffused into the semiconductor substrate 1 to form a p-type impurity diffusion layer 4. Examples of impurity diffusion methods include thermal diffusion. Examples of the heating method for thermal diffusion include the method exemplified above as a heating method for p-type impurities.
　次に、図１の（ｅ）に示すように、半導体基板１の表面に形成されたｐ型不純物拡散組成物パターン３を除去する。除去方法としては、例えば、公知のエッチング法が挙げられる。 Next, as shown in FIG. 1(e), the p-type impurity diffusion composition pattern 3 formed on the surface of the semiconductor substrate 1 is removed. Examples of the removal method include known etching methods.
　エッチングに用いる材料としては、例えば、エッチング成分と、水や有機溶媒を含むものが好ましい。エッチング成分としては、例えば、フッ化水素、アンモニウム、リン酸、硫酸、硝酸などが挙げられる。 The material used for etching is preferably one containing an etching component and water or an organic solvent, for example. Examples of etching components include hydrogen fluoride, ammonium, phosphoric acid, sulfuric acid, and nitric acid.
　本発明の不純物拡散組成物およびそれを用いた半導体素子は、太陽電池などの光起電力素子や、半導体表面に不純物拡散領域をパターン形成する半導体デバイス、例えば、トランジスターアレイやダイオードアレイ、フォトダイオードアレイ、トランスデューサーなどにも展開することができる。 The impurity diffusion composition of the present invention and a semiconductor device using the same can be used in photovoltaic devices such as solar cells, and semiconductor devices in which impurity diffusion regions are patterned on the semiconductor surface, such as transistor arrays, diode arrays, and photodiode arrays. , it can also be expanded to transducers, etc.
　＜太陽電池の製造方法＞
　本発明の太陽電池の製造方法は、前述の方法により半導体素子を製造する工程、パッシベーション層形成工程および電極形成工程を含む。 <Method for manufacturing solar cells>
The method for manufacturing a solar cell of the present invention includes a step of manufacturing a semiconductor element by the method described above, a step of forming a passivation layer, and a step of forming an electrode.
　図２に、本発明の太陽電池の製造方法の実施形態の一例を示す。以下に、図２を参照しながら、太陽電池の製造方法について説明する。この実施形態の一例で得られる太陽電池は、片面発電型太陽電池である。 FIG. 2 shows an example of an embodiment of the method for manufacturing a solar cell of the present invention. A method for manufacturing a solar cell will be described below with reference to FIG. 2. The solar cell obtained in this example embodiment is a single-sided power generation solar cell.
　まず、半導体素子を製造する方法としては、前述の本発明の半導体素子の製造方法が挙げられる。 First, as a method for manufacturing a semiconductor element, the above-described method for manufacturing a semiconductor element of the present invention can be mentioned.
　次に、パッシベーション層形成工程について説明する。図２の（ａ）に示すように、半導体素子基板１上にｐ型不純物拡散層２およびｐ型不純物拡散層４を有する半導体素子を用意し、図２の（ｂ）に示すように、その表面にパッシベーション層５、裏面にパッシベーション層６を形成する。 Next, the passivation layer forming process will be explained. As shown in (a) of FIG. 2, a semiconductor element having a p-type impurity diffusion layer 2 and a p-type impurity diffusion layer 4 is prepared on a semiconductor element substrate 1, and as shown in (b) of FIG. A passivation layer 5 is formed on the front surface, and a passivation layer 6 is formed on the back surface.
　パッシベーション層およびその形成方法としては、それぞれ、例えば、国際公開第２０１６／１３６４７４号において保護層として例示されたものが挙げられる。 Examples of the passivation layer and its formation method include those exemplified as the protective layer in International Publication No. 2016/136474.
　この実施形態の一例では、パッシベーション層５は受光面の領域にフォトレジストを用いてエッチングする等により部分的に開口された状態で、パッシベーション層６は裏面の全面に形成されている。 In one example of this embodiment, the passivation layer 5 is partially opened by etching a photoresist in the region of the light receiving surface, and the passivation layer 6 is formed on the entire back surface.
　次に、電極形成工程について説明する。図１の（ｃ）に示すように、受光面のパッシベーション層５の開口部分にコンタクト電極７を形成する。電極は、電極形成用ペーストを付与した後に加熱処理して形成することができる。 Next, the electrode forming process will be explained. As shown in FIG. 1C, a contact electrode 7 is formed in the opening of the passivation layer 5 on the light receiving surface. The electrode can be formed by applying an electrode forming paste and then subjecting it to heat treatment.
　これにより、片面発電型太陽電池８が得られる。 As a result, a single-sided power generation solar cell 8 is obtained.
　本発明の半導体素子の製造方法および太陽電池の製造方法は、上述の実施形態に限定されるものではなく、当業者の知識に基づいて各種の設計変更などの変形を加えることも可能であり、そのような変形が加えられた実施形態も本発明の範囲に含まれるものである。 The semiconductor device manufacturing method and the solar cell manufacturing method of the present invention are not limited to the above-described embodiments, and modifications such as various design changes can be made based on the knowledge of those skilled in the art. Embodiments with such modifications are also included within the scope of the present invention.
　以下、実施例を挙げて、本発明をさらに具体的に説明するが、本発明はこれら実施例に限定されない。なお、用いた化合物のうち、略語を使用しているものについて、以下に示す。
ＫＢＭ－１３：メチルトリメトキシシラン（信越化学（株）製）
ＫＢＭ－１０３：フェニルトリメトキシシラン（信越化学（株）製）
ＧＢＬ：γ－ブチロラクトン。 EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, among the compounds used, those using abbreviations are shown below.
KBM-13: Methyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
KBM-103: Phenyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)
GBL: γ-butyrolactone.
　合成例１（ＰＶＡ－１の合成）
　還流冷却器、滴下漏斗、撹拌機を備えた反応容器に、酢酸ビニル１，５００質量部、メタノール６４８質量部、アゾビスイソブチロニトリル０．３３モル％（対仕込み酢酸ビニル）を投入し、撹拌しながら窒素気流下で温度を上昇させ、６０℃で重合を開始した。酢酸ビニルの重合率が９０％となった時点で、ｍ－ジニトロベンゼンを添加して重合を終了し、続いて、メタノール蒸気を吹き込む方法により未反応の酢酸ビニルモノマーを系外に除去し、ポリ酢酸ビニルのメタノール溶液とした。 Synthesis Example 1 (Synthesis of PVA-1)
Into a reaction vessel equipped with a reflux condenser, a dropping funnel, and a stirrer, 1,500 parts by mass of vinyl acetate, 648 parts by mass of methanol, and 0.33 mol% of azobisisobutyronitrile (based on the charged vinyl acetate) were charged, The temperature was raised under a nitrogen stream while stirring, and polymerization was started at 60°C. When the polymerization rate of vinyl acetate reaches 90%, m-dinitrobenzene is added to terminate the polymerization, and unreacted vinyl acetate monomer is removed from the system by blowing methanol vapor into the polymer. A methanol solution of vinyl acetate was prepared.
　ついで、上記メタノール溶液をさらにメタノールで希釈し、濃度３０質量％に調整してニーダーに仕込み、溶液温度を３５℃に保ちながら、水酸化ナトリウムの２質量％メタノール溶液を共重合体中の酢酸ビニル構造単位の１モルに対してＮａ量として３．４０ミリモルとなる割合で加えてケン化を行った。ケン化が進行するとともにケン化物が析出し、粒子状となった時点で濾別し、メタノールでよく洗浄して熱風乾燥機中で乾燥し、目的とするＰＶＡ－１を得た。 Next, the above methanol solution was further diluted with methanol, adjusted to a concentration of 30% by mass, and charged into a kneader.While maintaining the solution temperature at 35°C, a 2% by mass methanol solution of sodium hydroxide was added to the vinyl acetate in the copolymer. Saponification was performed by adding Na at a ratio of 3.40 mmol per 1 mole of the structural unit. As the saponification progressed, the saponified product precipitated, and when it became particulate, it was filtered off, thoroughly washed with methanol, and dried in a hot air dryer to obtain the target PVA-1.
　得られたＰＶＡ－１のケン化度を、ＪＩＳ　Ｋ　６７２６（１９９４年）の逆滴定法により測定したところ、７８モル％であった。また、ＪＩＳ　Ｋ　６７２６（１９９４年）の逆滴定法により測定した平均重合度は、１，４００であった。 The saponification degree of the obtained PVA-1 was measured by the back titration method according to JIS K 6726 (1994) and was found to be 78 mol%. Further, the average degree of polymerization measured by the back titration method according to JIS K 6726 (1994) was 1,400.
　合成例２～２５（ＰＶＡ－２～ＰＶＡ－２５の合成）
　アゾビスイソブチロニトリルの投入量（対仕込み酢酸ビニル比）、および、水酸化ナトリウムの２質量％メタノール溶液のＮａ量（酢酸ビニル構造単位１モル）を表１に記載の量とした以外は合成例１と同様にして、ＰＶＡ－２～ＰＶＡ２５を作製した。合成例１と同様に得られたＰＶＡ－２～ＰＶＡ２５のケン化度と平均重合度を測定した結果を表１に示す。また、平均重合度Ｎとケン化度Ｘの測定値と、式（Ｙ１）、式（Ｙ２）、ケン化度３０モル％以上７０モル％未満の範囲との関係を図４に示す。 Synthesis Examples 2 to 25 (Synthesis of PVA-2 to PVA-25)
Except for the input amount of azobisisobutyronitrile (ratio to vinyl acetate charged) and the amount of Na in the 2% by mass methanol solution of sodium hydroxide (1 mol of vinyl acetate structural unit) as shown in Table 1. PVA-2 to PVA25 were produced in the same manner as in Synthesis Example 1. Table 1 shows the results of measuring the degree of saponification and average degree of polymerization of PVA-2 to PVA25 obtained in the same manner as in Synthesis Example 1. Moreover, the relationship between the measured values of the average degree of polymerization N and the saponification degree X, formula (Y1), formula (Y2), and the range of saponification degree of 30 mol% or more and less than 70 mol% is shown in FIG.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　合成例２６（シロキサン溶液Ａの調製）
　５００ｍＬの三口フラスコにＫＢＭ－１３を１６４．９３ｇ、ＫＢＭ－１０３を２０４．０７ｇ、ＧＢＬを３６３．０３ｇ仕込み、４０℃で撹拌しながら水１３０．７６ｇにギ酸１．２１５ｇを溶かしたギ酸水溶液を３０分間かけて添加した。滴下終了後、４０℃で１時間撹拌した後、７０℃に昇温し、３０分間撹拌した。その後、オイルバスを１１５℃まで昇温した。昇温開始１時間後に溶液の内温が１００℃に到達し、そこから１時間加熱撹拌した（内温は１００～１１０℃）。得られた溶液を氷浴にて冷却し、シロキサン溶液を得た。シロキサン溶液の固形分濃度は３９．８質量％であり、水分率は４．５質量％であった。 Synthesis Example 26 (Preparation of siloxane solution A)
A 500 mL three-necked flask was charged with 164.93 g of KBM-13, 204.07 g of KBM-103, and 363.03 g of GBL, and while stirring at 40°C, a formic acid aqueous solution prepared by dissolving 1.215 g of formic acid in 130.76 g of water was added at 30 °C. It was added over a period of minutes. After the dropwise addition was completed, the mixture was stirred at 40°C for 1 hour, then heated to 70°C, and stirred for 30 minutes. Thereafter, the temperature of the oil bath was raised to 115°C. One hour after the start of heating, the internal temperature of the solution reached 100°C, and from there it was heated and stirred for 1 hour (internal temperature was 100 to 110°C). The obtained solution was cooled in an ice bath to obtain a siloxane solution. The solid content concentration of the siloxane solution was 39.8% by mass, and the moisture content was 4.5% by mass.
　次に、各実施例および比較例における評価方法について説明する。 Next, evaluation methods in each example and comparative example will be explained.
　（１）シート抵抗値、抵抗値均一性測定
　基板として、一辺１５６ｍｍのｎ型単結晶シリコンからなる半導体基板を用意し、スライスダメージや自然酸化物を除去するために、両表面をアルカリエッチングした。この際、半導体基板の両面には典型的な幅が４０～１００μｍ、深さ３～４μｍ程度の無数の凹凸テクスチャーが形成され、これを基板とした。 (1) Measurement of sheet resistance and resistance uniformity A semiconductor substrate made of n-type single crystal silicon with a side of 156 mm was prepared as a substrate, and both surfaces were alkali-etched to remove slice damage and natural oxides. At this time, numerous uneven textures having a typical width of about 40 to 100 μm and depth of about 3 to 4 μm were formed on both sides of the semiconductor substrate, and this was used as a substrate.
　この基板を拡散炉（（株）光洋サーモシステムズ製）に配置し、窒素１９Ｌ／分、酸素０．６Ｌ／分の雰囲気下、臭化ホウ素（ＢＢｒ３）を窒素０．０６Ｌ／分でバブリングして流すことによって、炉内をｐ型不純物拡散成分を含む雰囲気とし、９５０℃で３０分間維持して基板全面にｐ型不純物拡散層を形成した。 This substrate was placed in a diffusion furnace (manufactured by Koyo Thermo Systems Co., Ltd.), and boron bromide (BBr 3 ) was bubbled with nitrogen at 0.06 L/min in an atmosphere of 19 L/min of nitrogen and 0.6 L/min of oxygen. The inside of the furnace was made into an atmosphere containing a p-type impurity diffusion component by flowing the atmosphere, and the temperature was maintained at 950° C. for 30 minutes to form a p-type impurity diffusion layer over the entire surface of the substrate.
　熱拡散後の基板を、５重量％のフッ酸水溶液に２３℃で１分間浸浸させて、表面を洗浄した。不純物拡散後の基板に対して、ｐ／ｎ判定機を用いてｐ／ｎ判定し、四探針式表面抵抗測定装置ＲＴ－７０Ｖ（ナプソン（株）製）を用いてシート抵抗値を測定したところ、ｎ型シリコンウェハー上にｐ型の不純物が拡散された基板であり、そのシート抵抗値は５０Ωであった。 After thermal diffusion, the substrate was immersed in a 5% by weight hydrofluoric acid aqueous solution at 23° C. for 1 minute to clean the surface. The substrate after impurity diffusion was subjected to p/n determination using a p/n determination device, and the sheet resistance value was measured using a four-probe surface resistance measuring device RT-70V (manufactured by Napson Co., Ltd.). Incidentally, the substrate was an n-type silicon wafer with p-type impurities diffused therein, and its sheet resistance value was 50Ω.
　次に、この基板のｐ型の不純物が拡散された面に、スクリーン印刷機（マイクロテック（株）ＴＭ－７５０型）とスクリーンマスク（ＳＵＳ（株）製、４００メッシュ）を用いて、各実施例および比較例により得られた不純物拡散組成物を、スクリーン印刷により全面印刷した。その後、空気中にて基板を２００℃のホットプレートで５分間、さらに２３０℃のオーブンで３０分間加熱し、厚さ約４μｍの不純物拡散組成物膜のパターンを形成した。 Next, a screen printing machine (Microtech Co., Ltd. TM-750 model) and a screen mask (manufactured by SUS Co., Ltd., 400 mesh) were applied to the surface of this substrate where the p-type impurity was diffused. The impurity diffusion compositions obtained in Examples and Comparative Examples were printed on the entire surface by screen printing. Thereafter, the substrate was heated in the air on a hot plate at 200° C. for 5 minutes and then in an oven at 230° C. for 30 minutes to form a pattern of an impurity diffusion composition film having a thickness of about 4 μm.
　続いて、この基板を電気炉内に配置し、窒素：酸素＝９９：１（体積比）の雰囲気下、９８０℃で６０分間維持して不純物を熱拡散させた。熱拡散後の基板を、５重量％のフッ酸水溶液に２３℃で１分間浸浸させて、拡散剤およびマスクを剥離した。不純物拡散後の基板に対して、ｐ／ｎ判定機を用いてｐ／ｎ判定し、四探針式表面抵抗測定装置ＲＴ－７０Ｖ（ナプソン（株）製）を用いてシート抵抗値を測定した。ここで、シート抵抗値の測定は、図３に示す２５点（Ａ～Ｙ）で行い、その平均値をシート抵抗値、（最大値－最小値）／平均値×１００（％）を抵抗値均一性とした。 Subsequently, this substrate was placed in an electric furnace and maintained at 980° C. for 60 minutes in an atmosphere of nitrogen:oxygen=99:1 (volume ratio) to thermally diffuse impurities. The substrate after thermal diffusion was immersed in a 5% by weight hydrofluoric acid aqueous solution at 23° C. for 1 minute to peel off the diffusing agent and mask. The substrate after impurity diffusion was subjected to p/n determination using a p/n determination device, and the sheet resistance value was measured using a four-probe surface resistance measuring device RT-70V (manufactured by Napson Co., Ltd.). . Here, the sheet resistance value is measured at 25 points (A to Y) shown in Figure 3, and the average value is the sheet resistance value, and (maximum value - minimum value)/average value x 100 (%) is the resistance value. It was defined as uniformity.
　シート抵抗値は不純物拡散性の指標となるものであり、抵抗値が小さい方が、不純物拡散量が大きく、高濃度で拡散されていると言える。本発明の場合、基板（シート抵抗値：５０Ω）と比較して１０Ω以上低抵抗であれば合格、それ未満を不合格とした。また、抵抗値均一性は２５％以下を合格、それを越えると不合格とした。 The sheet resistance value is an index of impurity diffusibility, and it can be said that the smaller the resistance value, the greater the amount of impurity diffusion, and the higher the concentration. In the case of the present invention, if the resistance was 10Ω or more lower than that of the substrate (sheet resistance value: 50Ω), it was considered to be a pass, and if it was less than that, it was judged to be a fail. Further, resistance value uniformity of 25% or less was considered to be passed, and when it exceeded it, it was judged to be failed.
　（２）室温保存後のシート抵抗値、抵抗値均一性測定
　各実施例および比較例により得られた不純物拡散組成物を室温で１４日、および、２８日静置した後、それぞれ上記（１）と同様にシート抵抗値、抵抗値均一性の評価を行った。合格、不合格の判定は（１）と同様とした。 (2) Measurement of sheet resistance value and resistance uniformity after storage at room temperature After the impurity diffusion compositions obtained in each example and comparative example were left to stand at room temperature for 14 days and 28 days, the above (1) was performed, respectively. The sheet resistance value and resistance value uniformity were evaluated in the same manner as above. The determination of pass and fail was the same as in (1).
　実施例１
　合成例２により得られたＰＶＡ－２　１１．６３ｇ、ホウ酸１．３１ｇ、合成例２６により得られたシロキサン溶液５．８４ｇ、酸化ケイ素微粒子“アエロジル（登録商標）”ＶＰＮＫＣ１３０（日本アエロジル（株）製：数平均粒子径２００ｎｍ）３．０２ｇ、ＧＢＬ２４．６４ｇ、テルピネオール３５．１０ｇを混合し、均一になるように十分撹拌し、不純物拡散組成物１を得た。 Example 1
11.63 g of PVA-2 obtained in Synthesis Example 2, 1.31 g of boric acid, 5.84 g of siloxane solution obtained in Synthesis Example 26, silicon oxide fine particles "Aerosil (registered trademark)" VPNKC130 (Nippon Aerosil Co., Ltd.) 3.02 g (manufactured by: number average particle diameter 200 nm), 24.64 g of GBL, and 35.10 g of terpineol were mixed and thoroughly stirred to become uniform, to obtain Impurity Diffusion Composition 1.
　実施例２～６０、比較例１～５
　ＰＶＡ、ホウ酸、アエロジル、シロキサン溶液、水、ＧＢＬおよび他溶剤を表２～５に記載の配合で配合し、不純物拡散組成物２～６５を得た。 Examples 2 to 60, Comparative Examples 1 to 5
PVA, boric acid, Aerosil, siloxane solution, water, GBL and other solvents were blended in the proportions shown in Tables 2 to 5 to obtain impurity diffusion compositions 2 to 65.
　各実施例および比較例の組成を表２に、主な組成と評価結果を表５～９に示す。 The compositions of each example and comparative example are shown in Table 2, and the main compositions and evaluation results are shown in Tables 5 to 9.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000011
Figure JPOXMLDOC01-appb-T000012
Figure JPOXMLDOC01-appb-T000012
１　半導体基板
２　ｐ型不純物拡散層
３　ｐ型不純物拡散組成物パターン
４　ｐ型不純物拡散組成物による不純物拡散層
５、６　パッシベーション層
７　コンタクト電極
８　太陽電池
Ａ　ケン化度が３０モル％以上７０モル％未満であり、さらに式（Ｙ１）を満たす領域
Ｂ　ケン化度が３０モル％以上７０モル％未満であり、さらに式（Ｙ２）を満たす領域 1 Semiconductor substrate 2 P-type impurity diffusion layer 3 P-type impurity diffusion composition pattern 4 Impurity diffusion layers 5, 6 made of p-type impurity diffusion composition Passivation layer 7 Contact electrode 8 Solar cell A Saponification degree of 30 mol% or more 70 mol Area B where the saponification degree is 30 mol% or more and less than 70 mol% and further satisfies formula (Y2)

Claims (13)

  1. （Ａ）ケン化度が３０モル％以上７０モル％未満であるポリビニルアルコール、（Ｂ）不純物拡散成分および（Ｃ）無機微粒子を含有する不純物拡散組成物であって、前記（Ａ）ポリビニルアルコール１００質量部に対して（Ｃ）無機微粒子を０．０１～２７．５質量部含有する不純物拡散組成物。 An impurity diffusion composition comprising (A) polyvinyl alcohol having a saponification degree of 30 mol% or more and less than 70 mol%, (B) an impurity diffusion component, and (C) inorganic fine particles, wherein the (A) polyvinyl alcohol 100 An impurity diffusion composition containing 0.01 to 27.5 parts by mass of (C) inorganic fine particles.
  2. 前記（Ｂ）不純物拡散成分としてホウ素化合物を含有する請求項１に記載の不純物拡散組成物。 The impurity diffusion composition according to claim 1, containing a boron compound as the impurity diffusion component (B).
  3. 前記（Ａ）ポリビニルアルコールの平均重合度が１００以上１，０００以下である請求項１または２に記載の不純物拡散組成物。 The impurity diffusion composition according to claim 1 or 2, wherein the polyvinyl alcohol (A) has an average degree of polymerization of 100 or more and 1,000 or less.
  4. 前記（Ａ）ポリビニルアルコールの平均重合度Ｎとケン化度Ｘが下記式（Ｙ１）の関係を満たす請求項３に記載の不純物拡散組成物。
    ２．５×（７０－Ｘ）＋１００≦Ｎ≦１２．５×（７０－Ｘ）＋５００　（Ｙ１）     The impurity diffusion composition according to claim 3, wherein the average degree of polymerization N and the degree of saponification X of the polyvinyl alcohol (A) satisfy the relationship of the following formula (Y1).
    2.5×(70-X)+100≦N≦12.5×(70-X)+500 (Y1)
  5. さらに（Ｄ）溶剤を含有し、（Ｄ）溶剤として下記一般式（１）で表される構造を有する溶剤を含有する請求項１または２に記載の不純物拡散組成物。
    Figure JPOXMLDOC01-appb-C000001
     （上記一般式（１）中、Ｒ１は、水素、水酸基または炭素数１～３の１価の有機基を表す。Ｒ２～Ｒ６は、それぞれ同じでも異なってもよく、水素または炭素数１～３の１価の有機基を表す。）     The impurity diffusion composition according to claim 1 or 2, further comprising (D) a solvent, and further comprising (D) a solvent having a structure represented by the following general formula (1).
    Figure JPOXMLDOC01-appb-C000001
     (In the above general formula (1), R 1 represents hydrogen, a hydroxyl group, or a monovalent organic group having 1 to 3 carbon atoms. R 2 to R 6 may be the same or different, and Represents a monovalent organic group of 1 to 3.)
  6. 前記一般式（１）で表される構造を有する溶剤を、（Ｄ）溶剤全１００質量部中、５～９０質量部含有する請求項５に記載の不純物拡散組成物。 The impurity diffusion composition according to claim 5, which contains the solvent having the structure represented by the general formula (1) in an amount of 5 to 90 parts by mass based on 100 parts by mass of the total solvent (D).
  7. （Ｄ）溶剤としてさらに水を含有する請求項５に記載の不純物拡散組成物。 (D) The impurity diffusion composition according to claim 5, further containing water as a solvent.
  8. 前記水を、（Ｄ）溶剤全１００質量部中、０．２～３質量部含有する請求項７に記載の不純物拡散組成物。 The impurity diffusion composition according to claim 7, wherein the water is contained in an amount of 0.2 to 3 parts by mass based on 100 parts by mass of the total solvent (D).
  9. アルコキシシラン化合物、シラノール化合物およびシロキサン樹脂の合計含有量が、（Ａ）ポリビニルアルコール１００質量部に対して１５質量部未満である請求項１または２に記載の不純物拡散組成物。 The impurity diffusion composition according to claim 1 or 2, wherein the total content of the alkoxysilane compound, silanol compound, and siloxane resin is less than 15 parts by mass based on 100 parts by mass of (A) polyvinyl alcohol.
  10. 半導体基板に請求項１または２に記載の不純物拡散組成物を塗布して不純拡散組成物パターンを形成する工程、および、前記不純物拡散組成物パターンから不純物を拡散させて半導体基板に不純物拡散層を形成する工程を含む半導体素子の製造方法。 A step of applying the impurity diffusion composition according to claim 1 or 2 on a semiconductor substrate to form an impurity diffusion composition pattern, and diffusing impurities from the impurity diffusion composition pattern to form an impurity diffusion layer on the semiconductor substrate. A method for manufacturing a semiconductor device, including a step of forming it.
  11. 半導体基板が、請求項１または２に記載の不純物拡散組成物と同型の不純物が表面に拡散されている基板である請求項１０に記載の半導体素子の製造方法。 11. The method for manufacturing a semiconductor device according to claim 10, wherein the semiconductor substrate is a substrate on which the same type of impurity as the impurity diffusion composition according to claim 1 or 2 is diffused.
  12. 半導体基板上に２水準以上の異なる不純物濃度の不純物拡散層を形成する工程を含む請求項１０に記載の半導体素子の製造方法。 11. The method of manufacturing a semiconductor device according to claim 10, comprising the step of forming impurity diffusion layers having two or more different impurity concentrations on the semiconductor substrate.
  13. 請求項１０に記載の方法により半導体素子を製造する工程、パッシベーション層形成工程および電極形成工程を含む太陽電池の製造方法。 A method for manufacturing a solar cell, comprising a step of manufacturing a semiconductor element by the method according to claim 10, a step of forming a passivation layer, and a step of forming an electrode.
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