Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
  • H01L21/2225—Diffusion sources
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/22—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
  • H01L21/225—Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities using diffusion into or out of a solid from or into a solid phase, e.g. a doped oxide layer
  • H01L21/2251—Diffusion into or out of group IV semiconductors
  • H01L21/2254—Diffusion into or out of group IV semiconductors from or through or into an applied layer, e.g. photoresist, nitrides
• • 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
  • H01L21/228—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 liquid phase, e.g. alloy diffusion processes

Definitions

• the present invention relates to a dopant diffusion coating solution used for printing on a substrate in forming a dopant source coating layer on a semiconductor substrate, and more specifically, dopant diffusion capable of obtaining a semiconductor having a low surface resistance value. It is related with the coating liquid.
• a liquid material containing a dopant (impurity) such as phosphorus or boron is applied to a semiconductor substrate such as germanium or silicon, a film is formed, and then fired.
• a method of forming a dopant diffusion layer in a substrate is widely used.
• the coating liquids described in Patent Documents 1 and 2 need to be a water-soluble compound as a dopant source because the main solvent is water, and as a phosphorus compound used for manufacturing an n-type semiconductor, Examples of boron compounds used in the manufacture of phosphoric acid, diphosphorus pentoxide, and p-type semiconductors include boric acid.
• the present invention relates to a dopant diffusion coating solution in which a dopant printed on a substrate surface is efficiently diffused into the substrate and a semiconductor having a low surface resistance is obtained, a coating method thereof, and a semiconductor manufacturing method using the same.
• the purpose is to provide a semiconductor.
• the present invention contains, as a dopant source, an organic amine salt of an acid selected from phosphoric acids and boric acids and an organic amine compound ( ⁇ ) having 1 to 4 nitrogen atoms. It was found that the object of the present invention was achieved by the coating solution for dopant diffusion to be completed, and the present invention was completed.
• the coating solution for dopant diffusion of the present invention is extremely useful industrially because a semiconductor having a low surface resistance value can be obtained by using it.
• the organic amine salt used as the dopant source is an acid such as phosphoric acid or boric acid, or an ammonium salt of these acids (metal salts are not suitable for the use of the present invention) and esters. Because the volatility is small and the volatilization from the substrate surface during the diffusion process is small, the yield of the dopant is improved, the dopant is efficiently diffused into the substrate, and a good diffusion amount is obtained. It is guessed.
• the number of nitrogen atoms of the organic amine compound represented by ( ⁇ ) is defined as 1 to 4, uniform solubility of the organic amine salt in the solvent can be obtained.
• the advantage is that nozzles are not clogged and stable printing can be performed when applied to inkjet printing. have.
• the coating liquid for dopant diffusion of the present invention does not use an acid as a dopant source as it is, it has an advantage that it does not corrode metal nozzles when applied to ink jet printing.
• the dopant source used in the coating solution for dopant diffusion of the present invention water or a mixed solvent of water and an organic solvent is preferably used as the solvent, and these solvents are low in volatility, and thus screen printing. In any printing method of ink jet printing, good printability can be obtained.
• the coating solution for dopant diffusion of the present invention contains a solvent and, if necessary, other additives as constituent components in addition to the specific dopant source of the present invention. These will be described sequentially.
• the dopant source used for the dopant diffusion coating solution of the present invention is an organic amine salt of an acid selected from phosphoric acids and boric acids and an organic amine compound ( ⁇ ) having 1 to 4 nitrogen atoms.
• the organic amine compound represented by ( ⁇ ) has 1 to 4 nitrogen atoms (preferably 1 or 2), uniform solubility in a solvent such as water or alcohol can be obtained.
• a solvent such as water or alcohol
• the acid may be selected as appropriate according to the type of semiconductor desired.
• phosphoric acid phosphorous acid, hypophosphorous acid, polyphosphoric acid, and phosphoric anhydride
• dipentapentoxide When phosphoric acids such as phosphorus form a p-type doped layer, boric acids such as boric acid, metaboric acid, boronic acid, perboric acid, hypoboric acid, and boric anhydride such as diboron trioxide are used. Used.
• an organic amine compound having 1 to 4 nitrogen atoms is used as shown in ( ⁇ ) above.
• An organic amine compound having 1 or 2 nitrogen atoms is preferred.
• the organic amine compound shown in ( ⁇ ) above is a compound in which a hydrogen atom of ammonia is substituted with a hydrocarbon group. From the type and structure of the hydrocarbon group, an aliphatic amine compound, an aromatic amine compound, Broadly divided into nitrogen cyclic compounds. Moreover, it divides roughly into a primary amine compound, a secondary amine compound, and a tertiary amine compound according to the number of substituents. Nitrogen-containing cyclic compounds are roughly classified into nitrogen-containing aliphatic cyclic compounds and nitrogen-containing aromatic compounds.
• aliphatic amine compounds include allylamine, methylamine, ethylamine, 2-aminoethanol, isobutylamine, n-butylamine, sec-butylamine, tert-butylamine, stearylamine, n-octylamine, sec-octylamine.
• aromatic amine compound examples include aniline, 1-aminonaphthalene (1-naphthylamine), benzylamine, 2-chlorobenzylamine, cumylamine, 1-naphthylamine, and other primary amine compounds, N, N-dimethylaniline. And tertiary amine compounds such as tribenzylamine and triphenylamine.
• nitrogen-containing aliphatic cyclic compounds include triethylenediamine, pyrrolidine compounds, piperidine compounds, etc.
• nitrogen-containing aromatic compounds include imidazole compounds, pyrrole compounds, pyridine compounds, pyrimidine compounds, etc. Can be mentioned.
• nitrogen-containing aromatic compounds are particularly preferred. More preferably, it is an imidazole compound.
• imidazole compounds include imidazole; 1-methylimidazole, 1-ethylimidazole, 1-propylimidazole, 1-butylimidazole, 1-pentylimidazole, 1-hexylimidazole, 1-heptylimidazole, 1-octylimidazole, 1-nonylimidazolium, 1-decylimidazole An imidazole substituted at the 1-position with an alkyl group; 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 2-butylimidazole, 2-pentylimidazole, 2-hexylimidazole, 2-heptylimidazole, 2-octylimidazole, 2-nonylimidazolium, 2-decylimidazole An imidazole substituted in the 2-position with alkyl; 4-methylimidazole, 4-ethylimidazole,
• organic amine compound used in the present invention those having 1 to 12 carbon atoms are usually used, and those having 2 to 10, particularly 3 to 8 carbon atoms are preferred. If the number of carbon atoms is too large, the compatibility with phosphoric acids and boric acids tends to decrease, and conversely if too small, the volatility during dopant diffusion tends to increase.
• organic amine compounds may be used alone or in combination of two or more.
• the molecular weight of the organic amine compound is preferably in the range of 30 to 300, more preferably 50 to 250, and particularly preferably 60 to 150. This is because if the molecular weight is too large or too small, the solubility in a solvent tends to be lowered.
• the organic amine salt used as a dopant source in the coating solution for dopant diffusion of the present invention is a neutralized product of phosphoric acid or boric acid and the above-mentioned organic amine compound, and a known production method thereof can be used.
• a neutralization reaction in a solution is usually preferably used from the viewpoints of reaction control and heat removal from the heat of neutralization reaction.
• the organic amine salt of the present invention obtained in water can be isolated and used once, but when the neutralization reaction solvent and the coating solution solvent are common, the acid and organic amine are used at the time of preparing the coating solution. It is an industrially useful embodiment to mix and neutralize and use as it is without isolation.
• the solubility of the dopant source (organic amine salt) used in the coating solution for dopant diffusion of the present invention in the solvent is usually 1 g / 100 g solvent or more, preferably 3 g / 100 g solvent or more, more preferably 5 g / 100 g solvent or more. .
• the upper limit is usually 80 g / 100 g solvent.
• the content of the dopant source (organic amine salt) in the coating solution for dopant diffusion of the present invention may be appropriately selected depending on the desired diffusion concentration, but is usually 0.1 to 30% by weight, A range of 1 to 25% by weight, particularly 0.1 to 20% by weight, is preferably used. If the content of such a dopant source is too small, the content of the dopant in the diffusion layer decreases, and a sufficient resistance value tends to be difficult to obtain.
• the solvent used for the dopant diffusion coating solution of the present invention is not particularly limited as long as it can disperse or dissolve the dopant source of the present invention, that is, an organic amine salt of phosphoric acid and boric acid. Is possible.
• the organic amine salt of phosphoric acid and boric acid dissolves well.
• the solvent of the coating solution for dopant diffusion of the present invention contains water in an amount of usually 10 to 90% by weight, preferably 20 to 80% by weight, particularly preferably 30 to 70% by weight. preferable.
• Such water is preferably contaminated with alkali metal or heavy metal and less contaminated, and usually has a total organic carbon (hereinafter sometimes referred to as TOC) of 50 ppb or less, preferably 10 ppb or less, and an electric resistance.
• the rate is usually 16 M ⁇ ⁇ cm or more, preferably 17 M ⁇ ⁇ cm or more, more preferably 18 M ⁇ ⁇ cm or more.
• Ultrapure water is most preferable, but ion-exchanged water or distilled water can also be used.
• the solvent of the coating solution for dopant diffusion of the present invention can be only water, but the solubility of organic amine, wettability to the substrate, solubility of various additives, leveling properties after printing, In order to adjust flow stability, volatility, etc., it is preferable to use various organic solvents in combination. Any organic solvent that is miscible with water can be used. Examples thereof include ketones and alcohols, and alcohols are particularly preferably used.
• alcohols include monohydric alcohols such as methanol (65 ° C.), ethanol (78 ° C.), isopropanol (82 ° C.); ethylene glycol (197 ° C.), diethylene glycol (244 ° C.), triethylene glycol (287 ° C), tetraethylene glycol (314 ° C), propylene glycol (188 ° C) and other dihydric alcohols; glycerin (290 ° C), trimethylolpropane (292 ° C), sorbitol (296 ° C), mannitol (290-295 ° C) , Pentaerythritol (276 ° C), polyglycerin and other polyhydric alcohols; and ethylene glycol monomethyl ether (124 ° C), ethylene glycol nomonoethyl ether (136 ° C), ethylene glycol mono-n-butyl Monoalkyl ethers of dihydric alcohols such as ether (171 ° C
• ketones include acetone (56 ° C.), methyl ethyl ketone (78 ° C.), methyl isobutyl ketone (116 ° C.), diisobutyl ketone (163 ° C.), and cyclohexanone (156 ° C.).
• the values in parentheses are boiling points. These may be used alone or in combination of two or more.
• an organic solvent having a boiling point higher than that of water that is, a boiling point of 100 ° C. or higher, in that rapid drying of the coated film after printing is suppressed and the leveling effect is greatly improved.
• Those having a temperature of -350 ° C, particularly 190-300 ° C are preferably used.
• the dopant diffusion coating liquid of the present invention preferably uses a mixed solvent of water and an organic solvent.
• a mixed solvent of water and organic solvent the amount of the organic solvent used together with water is usually 10 to 200 parts by weight, particularly 20 to 150 parts by weight, especially 50 to 50 parts by weight per 100 parts by weight of water.
• a range of 120 parts by weight is preferably used.
• the mixed solvent is preferably a mixed solvent of water and an alcohol, particularly preferably a mixed solvent of water and an alcohol having a boiling point of 100 ° C. or higher, particularly preferably water and a polyhydric alcohol and / or a polyhydric alcohol. It is a mixed solvent of monohydric alcohol with monoalkyl ether.
• a surfactant is further added to the dopant diffusion coating solution of the present invention.
• a surfactant By blending such a surfactant, wettability to the semiconductor surface is improved, foaming of the coating liquid is suppressed, and printing defects due to bubbles can be prevented.
• Surfactants used in aqueous liquids can be broadly classified into nonionic surfactants, cationic surfactants, and anionic surfactants, and any of them can be used. Therefore, nonionic surfactants are preferable. As such nonionic surfactants, known ones can be used.
• hydrocarbon surfactants such as block copolymers of ethylene oxide-propylene oxide, acetylene glycol derivatives, silicon -Based surfactants, fluorine-based surfactants and the like.
• hydrocarbon surfactants, particularly acetylene glycol derivatives are preferably used because they are excellent in suppressing foaming and defoaming in the coating solution of the present invention.
• acetylene glycol derivatives those represented by the following formula (1) are preferably used.
• R 7 and R 10 each independently represents an alkyl group having 1 to 20 carbon atoms, preferably having 1 to 5 carbon atoms, particularly preferably having 3 to 5 carbon atoms.
• R 8 and R 9 each independently represents an alkyl group having 1 to 3 carbon atoms, and a methyl group is particularly preferably used.
• R 7 and R 10 , and R 8 and R 9 may be the same or different, but those having the same structure are preferably used.
• n and m are each an integer of 0 to 30, and those in which m + n is 1 to 10, particularly 1 to 5, particularly 1 to 3 are preferably used.
• acetylene glycol derivatives include 2,5,8,11-tetramethyl-6-dodecin-5,8-diol ethylene oxide adduct, 5,8-dimethyl-6-dodecin-5,8. -Ethylene oxide adduct of diol, ethylene oxide adduct of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 4,7-dimethyl-5-decyne-4,7-diol Ethylene oxide adduct, 2,3,6,7-tetramethyl-4-octyne-3,6-diol ethylene oxide adduct, 3,6-dimethyl-4-octyne-3,6-diol ethylene oxide addition And an ethylene oxide adduct of 2,5-dimethyl-3-hexyne-2,5-diol. Among these, ethylene oxide adducts of 2,4,7,9-tetramethyl-6-
• Examples of such commercially available surfactants that are acetylene glycol derivatives include the Surfinol series manufactured by Nissin Chemical Industry Co., Ltd. and the acetylenol series manufactured by Kawasaki Fine Chemical Co., Ltd.
• the amount of the surfactant to be blended in the dopant diffusion coating solution of the present invention is usually from 0.1 to 10% by weight, particularly from 0.3 to 8% by weight, particularly from 0.5 to 0.5% in the coating solution. 5% by weight. If the amount of such a surfactant is too small, the intended anti-foaming / defoaming effect may be insufficient. Conversely, if it is too large, the solution tends to be separated from the liquid and the uniformity of the solution tends to decrease. .
• inorganic fine particles In the coating liquid for dopant diffusion of the present invention, various inorganic fine particles can be blended for the purpose of improving printing characteristics.
• silicas such as colloidal silica, amorphous silica, and fumed silica are suitable, and among them, colloidal silica is preferably used.
• the amount of such inorganic fine particles is usually 0.5 to 20% by weight in the coating solution, and particularly 1 to 10% by weight.
• water-soluble polymer various polymer compounds can be blended in the coating solution for dopant diffusion of the present invention.
• the coating solution of the present invention is used for screen printing, the printability can be improved by blending the polymer compound.
• known compounds used for coating solutions can be used.
• water-soluble polymers include polyvinyl alcohol resins (hereinafter abbreviated as PVA resins), acrylic resins, and the like.
• PVA resins polyvinyl alcohol resins
• acrylic resins acrylic resins
• a PVA resin is preferably used.
• the PVA resin used for the dopant diffusion coating solution of the present invention will be described.
• the PVA resin is generally obtained by saponifying polyvinyl acetate obtained by copolymerizing vinyl acetate, and is composed of a vinyl alcohol structural unit and a vinyl acetate structural unit corresponding to the degree of saponification.
• the average degree of polymerization (measured in accordance with JIS K6726) of the PVA resin used in the present invention is usually 100 to 4000, particularly 200 to 2000, more preferably 300 to 1500. If the average degree of polymerization is too small, the coating solution tends to have a low viscosity, and the desired printability tends to be difficult to obtain, and the coating film becomes a thin film and the amount of dopant supplied may be insufficient. On the other hand, even if it is too large, the intended printability tends to be difficult to obtain, and printing defects tend to occur.
• the PVA resin used in the present invention those having a saponification degree (measured in accordance with JIS K6726) of 50 to 100 mol% can be used.
• a mixed solvent of water and an organic solvent having a large amount of an organic solvent component is used for the coating liquid of the present invention, and when the concentration of the dopant source is high, the PVA-based resin has a high saponification degree.
• the saponification degree is preferably 50 to 90 mol%, more preferably 60 to 85 mol%, particularly preferably 70 to 80 mol%. .
• PVA resin various known modified PVA resins can be used.
• a PVA resin having a structural unit having a 1,2-diol structure in the side chain represented by the following general formula (2) is preferably used.
• R 1 , R 2 and R 3 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms
• X represents a single bond or a bonded chain
• R 4 , R 3 5 and R 6 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.
• R 1 to R 3 and R 4 to R 6 are all hydrogen atoms, and X is a single bond.
• a PVA resin having a structural unit represented by ') is most preferred.
• a saponification degree of 50 to 100 mol% can be used, and further 60 to 100 mol can be used. %, Particularly 70 to 100 mol% is preferably used. This is because, due to the 1,2-diol structure of the side chain, even if the degree of saponification is higher than that of unmodified PVA, the decrease in solubility due to the blending of salts and blending of organic solvents could be suppressed. is there.
• the content of 1,2-diol structural units contained in such a PVA resin is usually 1 to 30 mol%, more preferably 3 to 20 mol%, particularly 5 to 10 mol%. . If the content is too low, the solubility in an organic solvent may be insufficient in the case of a high saponification degree. Conversely, if the content is too high, the drying efficiency tends to decrease and the productivity tends to decrease. is there.
• the content of the 1,2-diol structural unit in the PVA resin is determined from a 1 H-NMR spectrum (solvent: DMSO-d6, internal standard: tetramethylsilane) of a completely saponified PVA resin. Specifically, it can be calculated from the peak area derived from hydroxyl protons, methine protons, and methylene protons in the 1,2-diol unit, methylene protons in the main chain, protons in the hydroxyl group linked to the main chain, etc. Good.
• the PVA resin used in the present invention may be one kind or a mixture of two or more kinds.
• the above-mentioned unmodified PVA, unmodified PVA and general formula (2) PVA resins having a structural unit represented by the formula, PVA resins having a structural unit represented by the general formula (2) having different saponification degree, polymerization degree, modification degree, etc., unmodified PVA, or general formula (2)
• a combination of a PVA-based resin having a structural unit represented by the above and another modified PVA-based resin can be used.
• the content of the water-soluble polymer in the coating solution for dopant diffusion of the present invention is usually 1 to 40% by weight, preferably 3 to 30% by weight, particularly 5 to 25% by weight. If the content of the water-soluble polymer fat is too small, the viscosity of the coating liquid tends to be low and the coating film tends to be difficult to be formed stably. Conversely, if the content is too large, the viscosity of the coating liquid becomes high. Therefore, there is a tendency that the coating workability is deteriorated or the screen mesh is easily clogged in screen printing.
• the dopant diffusion coating solution of the present invention contains the above-described phosphoric acids or boric acid organic amine salts as a dopant source, and is formed by blending a solvent and various additives as required. .
• Such a coating solution for dopant diffusion can be obtained by dissolving an organic amine salt of phosphoric acid or boric acid in a solvent.
• the organic amine salt a commercially available one or a compound synthesized by neutralizing the above acid and organic amine in advance can be used. It is also possible to carry out in water, preferably in water or an aqueous solvent. In that case, a method in which both are put into a solvent at the same time, a method in which an acid is dissolved in a solvent in advance, and then an organic amine is added. Either of these can be adopted. However, since heat of neutralization reaction is generated, it is preferable to blend one and gradually add the other.
• the coating solution for dopant diffusion of the present invention can be blended with surfactants, inorganic fine particles, water-soluble polymers, etc., if necessary. You may mix
• the viscosity of the coating solution for dopant diffusion of the present invention is usually 1 to 10000 mPa ⁇ s, particularly 2 to 5000 mPa ⁇ s, particularly 3 to 3000 mPa ⁇ s.
• the viscosity is a value measured at 20 ° C. using a B-type viscometer.
• the viscosity of the coating solution for dopant diffusion can be adjusted by, for example, blending and blending amount of the above water-soluble polymer.
• the coating liquid of the present invention when used for screen printing, those having a viscosity of usually 100 to 10000 mPa ⁇ s, particularly 200 to 5000 mPa ⁇ s are preferably used. If the viscosity of the coating solution is too small, it may be difficult to stably form a coating film by screen printing, or the dopant content in the diffusion layer may be insufficient. Tend to decrease or clogging of the screen mesh tends to occur.
• the coating liquid of the present invention when used for ink jet printing, one having a viscosity of usually 1 to 100 mPa ⁇ s, particularly 2 to 50 mPa ⁇ s is preferably used. If the viscosity of the coating solution is too small, the printed image may be easily spread or the content of the dopant in the diffusion layer may be insufficient. Conversely, if the viscosity is too large, the coating solution nozzle may be clogged. It tends to occur easily. Such a viscosity tends to increase when the water-soluble polymer and / or surfactant is blended. Therefore, particularly when the coating liquid of the present invention is used for inkjet printing, the water-soluble polymer and / or It is preferable to adjust to the above viscosity by not containing a surfactant.
• the pH at 20 ° C. of the coating solution for dopant diffusion of the present invention is usually 4 to 10, particularly 4.5 to 9.5, particularly 5 to 9 is preferably used. If the pH is too high or too low, various metal members used in the printing press may be corroded. Particularly, when used for ink jet printing, the metal nozzle is corroded and causes nozzle clogging. There is a case.
• pH of this coating liquid for dopant diffusion can be adjusted by mix
• the surface tension at 20 ° C. is usually 10 to 80 mN / m, particularly 15 to 70 mN / m, particularly 20 to 60 mN / m. Preferably used. If the surface tension is too high or too low, ink jet ejection tends to be defective.
• Such a semiconductor is manufactured by applying (printing) the coating liquid for dopant diffusion of the present invention on a semiconductor substrate and forming a diffusion layer of the dopant in the semiconductor substrate by a diffusion process.
• a semiconductor substrate a known substrate can be used, but a silicon or germanium single crystal or a polycrystalline substrate is usually used.
• the thickness of the substrate may be appropriately selected according to the desired purpose, but a thickness of 150 to 300 ⁇ m is usually used.
• the damaged layer on the substrate surface is removed by etching using an acid or alkali, or the wettability of the coating solution is improved by plasma oxidation or removal of hydrofluoric acid from the oxide film. It is also possible to use a controlled one.
• a known method can be used as a method for applying the dopant diffusion coating solution on the semiconductor substrate. Specifically, a screen printing method, a gravure printing method, a relief printing method, a lithographic printing method, a spin coating method. , Spray method, inkjet printing method, and the like.
• the coating liquid of the present invention is suitable for the screen printing method and the ink jet printing method, and these methods are preferable because of the uniformity of the printing density for a large wafer and the ease of pattern formation necessary for the production of semiconductors for solar cells. Used.
• the coating liquid for dopant diffusion of the present invention does not use an acid as a dopant source as it is, it has an advantage that it does not corrode metal nozzles when applied to ink jet printing.
• the nozzle is not easily clogged, particularly when applied to inkjet printing, and stable printing can be performed.
• the amount of the coating solution applied (printed) to the semiconductor substrate varies depending on the type of the substrate, the use of the semiconductor, the dopant content in the coating solution and the desired diffusion amount, but is usually 0.01 to 100 g / m 2. In particular, it is carried out at 0.05 to 50 g / m 2 .
• the semiconductor substrate having the dopant source layer formed on the surface by such application has a dopant diffusion layer by diffusing the dopant in the dopant source layer into the surface layer portion of the semiconductor substrate by the diffusion process.
• the diffusion method in the diffusion step is usually a thermal diffusion method, and a known heating method / apparatus can be used, for example, a laser doping method, or an electric furnace, a tube furnace, a muffle furnace, a belt furnace. And the like.
• the temperature condition in the diffusion step is usually 700 to 1400 ° C., particularly 800 to 1200 ° C., and the time is usually 1 to 60 minutes, particularly 5 to 30 minutes.
• the diffusion step is performed in nitrogen, argon, or a mixed atmosphere of nitrogen-oxygen and argon-oxygen, and a nitrogen-oxygen mixed atmosphere is particularly preferable.
• the oxygen content is usually 1 with respect to the total amount. Is preferably 10 to 10% by volume, particularly 1 to 3% by volume.
• diffusion may be performed in an atmosphere containing only nitrogen, and oxygen may be added during or after the diffusion. In this case, the oxygen is usually 1 to 100% by volume, particularly 10 to 100% by volume, based on the total amount.
• coating process using the coating liquid for dopant diffusion and the said diffusion process, it aims at the drying process aiming at the removal of the volatile component which remains in an application part as needed, and the removal of an organic component. It is also possible to provide a degreasing process.
• a drying time is usually used at a temperature of 20 to 300 ° C., particularly 50 to 200 ° C., usually 1 to 60 minutes, particularly 5 to 30 minutes.
• the drying method is not particularly limited, and known methods such as hot air drying, infrared heat drying, and vacuum drying can be used.
• the degreasing step an electric furnace or the like is used, and the conditions are usually 300 to 1000 ° C., particularly 400 to 800 ° C., and usually 1 to 120 minutes, particularly 5 to 60 minutes.
• a degreasing step can be carried out continuously with the drying step, and the degreasing step can also be carried out as an initial step of the diffusion step.
• the heat treatment such as the diffusion step, the drying step, the degreasing step and the like can be performed in a plurality of steps at once, continuously, or omitted as necessary. That is, the heat treatment such as the diffusion process, the drying process, the degreasing process, and the like does not necessarily need to be performed in all steps.
• the semiconductor having the dopant diffusion layer of the present invention thus obtained can obtain a semiconductor with low surface resistance because the dopant is efficiently diffused in the semiconductor substrate.
• the value of the surface resistance of the dopant diffusion layer varies depending on the intended use and the amount of diffusion of the dopant, but is usually 10 to 300 ⁇ / ⁇ , particularly 15 to 200 ⁇ / ⁇ , particularly 20 to 100 ⁇ / ⁇ . Those are preferably used.
• the amount of dopant on the surface of the dopant diffusion layer is usually 10 18 to 10 23 atoms, particularly 10 19. ⁇ 10 22 atoms.
• the present invention will be described with reference to examples. However, the present invention is not limited to the description of the examples unless it exceeds the gist.
• “parts” and “%” mean weight basis unless otherwise specified.
• “ultra pure water” means water having a TOC of 1.0 ppb or less and an electrical resistivity of 18.2 M ⁇ ⁇ cm.
• Example 1 Preparation of coating solution for dopant diffusion> To 40 parts of ultrapure water, 40 parts of methyl carbitol and 10 parts of phosphoric acid aqueous solution (manufactured by Kanto Chemical Co., Ltd., for EL, 85% phosphoric acid, 15% water) were added and mixed with stirring at room temperature. 10 parts of methylimidazole was added while stirring little by little to obtain a coating solution for dopant diffusion containing imidazole phosphate (1-methylimidazole phosphate) by neutralization reaction. The obtained dopant diffusion coating solution had a pH of 6 at 20 ° C., a viscosity of 6 mPa ⁇ s, and a surface tension of 40 mN / m.
• ⁇ Printing on semiconductor substrate> The surface of P-type single crystal silicon (manufactured by Space Energy Co., Ltd.) is subjected to alkali etching texture processing, and then immersed in 5% hydrofluoric acid for 1 minute and washed at the center of a semiconductor substrate (156 mm square, 200 ⁇ m thick).
• a printing machine (“Nanoprinter-1100” manufactured by Microjet Co., Ltd.) and “SE-128” manufactured by Dimatix Co. as the head, the following conditions and patterns of Example 1 were used in an environment of 23 ° C. and 50% RH.
• the dopant diffusion coating solution was inkjet printed to draw a line pattern.
• the semiconductor substrate on which the dopant diffusion coating solution of Example 1 was printed by inkjet printing was put into a tube furnace at 700 ° C., heated to 875 ° C. over 15 minutes, held at that temperature for 10 minutes, and further 40 minutes The temperature was lowered to 700 ° C. During this period, the nitrogen flow rate was 20 L / min, and the oxygen flow rate was 0.4 L / min. After the heat treatment, the semiconductor substrate was taken out, immersed in a 10% hydrogen fluoride aqueous solution, allowed to stand for 3 minutes, and then washed twice with ultrapure water to obtain a semiconductor having a phosphorus diffusion layer in the semiconductor substrate.
• the surface resistance value of the obtained semiconductor was measured using a resistance measuring instrument (“Lorestar” manufactured by Mitsubishi Analytech Co., Ltd., using a PSP probe).
• Example 2 instead of 1-methylimidazole in Example 1, triethylamine was used, and the salt in the dopant diffusion coating solution was triethylamine phosphate. Other than that was carried out similarly to Example 1, and produced the coating liquid for dopant diffusion.
• the obtained dopant diffusion coating solution had a pH of 20 at 20 ° C., a viscosity of 5 mPa ⁇ s, and a surface tension of 40 mN / m.
• inkjet printing was performed on the substrate in the same manner as in Example 1. When the drawing line was visually observed, no bleeding was observed, and no nozzle ejection failure occurred during printing.
• the semiconductor substrate after printing was subjected to diffusion treatment in the same manner as in Example 1 to produce a semiconductor.
• the phosphorus element concentration on the surface was 10 20 atoms / cm 2 and the doping depth was 0.3 ⁇ m.
• Comparative Example 1 The amount of ultrapure water in the coating solution for dopant diffusion of Example 1 was 30 parts by weight, and no imidazole was used. Other than that was carried out similarly to Example 1, and produced the coating liquid for dopant diffusion.
• the obtained dopant diffusion coating solution had a pH of 1 at 20 ° C., a viscosity of 5 mPa ⁇ s, and a surface tension of 40 mN / m. Since the obtained coating solution for dopant diffusion was strongly acidic and highly likely to damage the ink jet nozzle, ink jet printing using this coating solution could not be performed.
• Comparative Example 2 instead of 1-methylimidazole in Example 1, ammonia was used, and the salt in the dopant diffusion coating solution was an ammonium phosphate salt. Other than that was carried out similarly to Example 1, and when it was going to produce the coating liquid for dopant diffusion, the solution became cloudy and ammonium phosphate precipitated during the stirring after ammonia addition. Therefore, inkjet printing using this coating solution could not be performed.
• Comparative Example 3 Instead of the phosphoric acid aqueous solution in Example 1, 20 parts of phosphoric acid ester (“JP-502” manufactured by Johoku Chemical Co., Ltd.) was used. Other than that was carried out similarly to Example 1, and produced the coating liquid for dopant diffusion.
• the obtained dopant diffusion coating solution had a pH of 6 at 20 ° C., a viscosity of 4 mPa ⁇ s, and a surface tension of 26 mN / m.
• inkjet printing was performed on the substrate in the same manner as in Example 1. When the drawing line was visually observed, the line width increased due to bleeding, and a good printing result was not obtained.
• Comparative Example 4 Melamine was used in place of 1-methylimidazole in Example 1, and the salt in the coating solution for dopant diffusion was melamine phosphate. Other than that was carried out similarly to Example 1, and when it was going to produce the coating liquid for dopant diffusion, the solution became cloudy and became a heterogeneous solution. Therefore, inkjet printing using this coating solution could not be performed.
• the coating solution for dopant diffusion containing the phosphoric acid organic amine salt of Examples as a dopant source has good ink jet printability, and the semiconductor obtained therefrom has a large number of dopant atoms on the surface, Since the diffusion depth was also deep, the diffusibility of the dopant was good.
• phosphoric acid or ammonium phosphate when phosphoric acid or ammonium phosphate is used as a dopant source, a coating liquid capable of ink jet printing cannot be obtained, and phosphoric acid esters have good printing results. It was not obtained.
• melamine phosphate was used, it became a heterogeneous solution and inkjet printing could not be performed.
• Example 3 Manufacture of PVA resin> A reaction vessel equipped with a reflux condenser, a dropping funnel and a stirrer was charged with 1500 parts of vinyl acetate, 800 parts of methanol, and 240 parts of 3,4-diacetoxy-1-butene, and 0.05 mol of azobisisobutyronitrile. % (Vs. vinyl acetate charged) was added, the temperature was raised under a nitrogen stream while stirring, and polymerization was started. When the polymerization rate of vinyl acetate reaches 87%, m-dinitrobenzene is added to complete the polymerization, and then unreacted vinyl acetate monomer is removed from the system by blowing methanol vapor. A combined methanol solution was obtained.
• the methanol solution is further diluted with methanol, adjusted to a concentration of 40%, charged into a kneader, and while maintaining the solution temperature at 40 ° C., sodium hydroxide is used as a 2% methanol solution to form a vinyl acetate structural unit in the copolymer.
• saponification was carried out by adding 8 mmol with respect to 1 mol of the total amount of 3,4-diacetoxy-1-butene structural units. As saponification progressed, when saponified substances were precipitated and formed into particles, they were separated by filtration, washed well with methanol and dried in a hot air drier to produce the intended PVA resin.
• the saponification degree of the obtained PVA-based resin was 99.8 mol% when analyzed by the alkali consumption required for hydrolysis of residual vinyl acetate and 3,4-diacetoxy-1-butene.
• the average degree of polymerization was 350 when analyzed according to JIS K 6726.
• the content of the 1,2-diol structural unit represented by the general formula (2 ′) is 1 H-NMR (300 MHz proton NMR, d6-DMSO solution, internal standard substance: tetramethylsilane, 50 ° C.). It was 8 mol% when it computed from the integrated value measured in this way.
• a solution ⁇ 2 1 part of “Surfinol 420” manufactured by Nissin Chemical Industry Co., Ltd.) was added to prepare a solution ⁇ 2.
• the solution ⁇ 2 was added to the solution ⁇ 1 and stirred to prepare a phosphorus diffusion coating solution ⁇ .
• the resulting dopant diffusion coating solution had a pH of 6 at 20 ° C. and a viscosity of 1000 mPa ⁇ s.
• Example 3 results of Example 3 and Comparative Example 5 are summarized as shown in Table 2 below.
• the semiconductor obtained using the coating solution for dopant diffusion containing the phosphoric acid organic amine salt of the example as a dopant source has a surface dopant as compared with that using an ammonium phosphate salt. Since the number of atoms is large and the diffusion depth is deep, it can be seen that the diffusibility of the dopant is good.
• the coating liquid for dopant diffusion of the present invention does not use an acid as a dopant source, it has an advantage that it does not corrode metal nozzles when applied to ink jet printing.

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