CN110872729A - Texturing and hole digging additive, texturing and silver sinking hole digging liquid, silicon wafer and solar cell of diamond wire cutting polycrystalline silicon wafer - Google Patents
Texturing and hole digging additive, texturing and silver sinking hole digging liquid, silicon wafer and solar cell of diamond wire cutting polycrystalline silicon wafer Download PDFInfo
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- CN110872729A CN110872729A CN201811001506.9A CN201811001506A CN110872729A CN 110872729 A CN110872729 A CN 110872729A CN 201811001506 A CN201811001506 A CN 201811001506A CN 110872729 A CN110872729 A CN 110872729A
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- silicon wafer
- silver
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- polyethylene glycol
- digging
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 187
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 186
- 239000010703 silicon Substances 0.000 title claims abstract description 186
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims abstract description 128
- 229910052709 silver Inorganic materials 0.000 title claims abstract description 114
- 239000004332 silver Substances 0.000 title claims abstract description 114
- 229910021420 polycrystalline silicon Inorganic materials 0.000 title claims abstract description 82
- 239000000654 additive Substances 0.000 title claims abstract description 73
- 229910003460 diamond Inorganic materials 0.000 title claims abstract description 72
- 239000010432 diamond Substances 0.000 title claims abstract description 72
- 230000000996 additive effect Effects 0.000 title claims abstract description 69
- 238000005520 cutting process Methods 0.000 title claims description 49
- 239000007788 liquid Substances 0.000 title claims description 25
- 239000002253 acid Substances 0.000 claims abstract description 85
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 83
- 239000008367 deionised water Substances 0.000 claims abstract description 66
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 66
- YXIWHUQXZSMYRE-UHFFFAOYSA-N 1,3-benzothiazole-2-thiol Chemical compound C1=CC=C2SC(S)=NC2=C1 YXIWHUQXZSMYRE-UHFFFAOYSA-N 0.000 claims abstract description 46
- 230000007797 corrosion Effects 0.000 claims abstract description 37
- 238000005260 corrosion Methods 0.000 claims abstract description 37
- 239000003112 inhibitor Substances 0.000 claims abstract description 36
- 239000002202 Polyethylene glycol Substances 0.000 claims abstract description 24
- 229920001223 polyethylene glycol Polymers 0.000 claims abstract description 24
- FJLUATLTXUNBOT-UHFFFAOYSA-N 1-Hexadecylamine Chemical compound CCCCCCCCCCCCCCCCN FJLUATLTXUNBOT-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000002360 preparation method Methods 0.000 claims abstract description 19
- 210000002268 wool Anatomy 0.000 claims abstract description 16
- REYJJPSVUYRZGE-UHFFFAOYSA-N Octadecylamine Chemical compound CCCCCCCCCCCCCCCCCCN REYJJPSVUYRZGE-UHFFFAOYSA-N 0.000 claims abstract description 13
- 150000001412 amines Chemical class 0.000 claims abstract description 13
- 239000003760 tallow Substances 0.000 claims abstract description 13
- 235000012431 wafers Nutrition 0.000 claims description 223
- 239000000243 solution Substances 0.000 claims description 62
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 58
- 238000004140 cleaning Methods 0.000 claims description 56
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- 238000000034 method Methods 0.000 claims description 42
- 239000003795 chemical substances by application Substances 0.000 claims description 36
- 238000000151 deposition Methods 0.000 claims description 35
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 28
- 239000002245 particle Substances 0.000 claims description 23
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 22
- 230000008021 deposition Effects 0.000 claims description 22
- 229910017604 nitric acid Inorganic materials 0.000 claims description 22
- 238000007654 immersion Methods 0.000 claims description 21
- 230000001376 precipitating effect Effects 0.000 claims description 21
- 239000002270 dispersing agent Substances 0.000 claims description 20
- 229940068918 polyethylene glycol 400 Drugs 0.000 claims description 18
- 229940057847 polyethylene glycol 600 Drugs 0.000 claims description 18
- 238000005498 polishing Methods 0.000 claims description 15
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 14
- 239000003513 alkali Substances 0.000 claims description 13
- 238000002310 reflectometry Methods 0.000 claims description 13
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 10
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 10
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 10
- 229910021426 porous silicon Inorganic materials 0.000 claims description 9
- 238000001556 precipitation Methods 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 7
- 238000001579 optical reflectometry Methods 0.000 claims description 6
- 235000008216 herbs Nutrition 0.000 claims description 5
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 4
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 4
- 235000014113 dietary fatty acids Nutrition 0.000 claims description 4
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 claims description 4
- 239000000194 fatty acid Substances 0.000 claims description 4
- 229930195729 fatty acid Natural products 0.000 claims description 4
- 150000004665 fatty acids Chemical class 0.000 claims description 4
- 150000002500 ions Chemical class 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 229920002401 polyacrylamide Polymers 0.000 claims description 4
- 229940113116 polyethylene glycol 1000 Drugs 0.000 claims description 4
- 229940113115 polyethylene glycol 200 Drugs 0.000 claims description 4
- 229940085675 polyethylene glycol 800 Drugs 0.000 claims description 4
- 229920001522 polyglycol ester Polymers 0.000 claims description 4
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 4
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 4
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 claims description 4
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 239000004570 mortar (masonry) Substances 0.000 abstract description 19
- 238000006243 chemical reaction Methods 0.000 abstract description 13
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- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 15
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 14
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
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- 230000017260 vegetative to reproductive phase transition of meristem Effects 0.000 description 5
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
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- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 239000000969 carrier Substances 0.000 description 3
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- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- QRUDEWIWKLJBPS-UHFFFAOYSA-N benzotriazole Chemical compound C1=CC=C2N[N][N]C2=C1 QRUDEWIWKLJBPS-UHFFFAOYSA-N 0.000 description 2
- 239000012964 benzotriazole Substances 0.000 description 2
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- 235000012239 silicon dioxide Nutrition 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 101710099518 Dickkopf-related protein 1 Proteins 0.000 description 1
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- 238000010668 complexation reaction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
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Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
- C30B33/08—Etching
- C30B33/10—Etching in solutions or melts
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
- C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
- C23C18/31—Coating with metals
- C23C18/42—Coating with noble metals
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/02—Elements
- C30B29/06—Silicon
-
- 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
- H01L31/02—Details
- H01L31/0236—Special surface textures
- H01L31/02363—Special surface textures of the semiconductor body itself, e.g. textured active layers
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Abstract
The invention relates to the field of crystalline silicon solar cell preparation, and discloses a texturing and hole digging additive for a diamond wire-cut polycrystalline silicon wafer, a texturing and silver sinking hole digging solution for the diamond wire-cut polycrystalline silicon wafer, a silicon wafer and a solar cell. The additive for making the wool and digging the holes comprises 0.01-0.20 wt% of polyethylene glycol, 0.01-0.10 wt% of corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the molecular weight of the polyethylene glycol is less than 1000, and the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine. The silicon wafer has the advantages of fuzzy grain boundary, uniform color and small chromatic aberration, has good appearance and no obvious phenomenon of blooming after being prepared into a battery piece, and has certain improvement on photoelectric conversion efficiency compared with the battery obtained by acid texturing of the conventional mortar cut silicon wafer.
Description
Technical Field
The invention relates to the field of crystalline silicon solar cell preparation, in particular to a texturing and hole-digging additive for a diamond wire-cutting polycrystalline silicon wafer, a texturing, silver-depositing and hole-digging solution containing the texturing and hole-digging additive for the diamond wire-cutting polycrystalline silicon wafer and a preparation method thereof, a silicon wafer prepared by using the hole-digging solution, and a solar cell prepared by using the silicon wafer.
Background
Solar cell photovoltaic power generation is an important approach to solve the global energy crisis and environmental pollution problems, and nearly 90% of the solar cell is a silicon wafer solar cell. The diamond wire saw cutting technology is applied to the cutting production of crystal silicon wafers in recent years, and compared with the existing mainstream silicon carbide abrasive mortar wire cutting technology, the diamond wire saw cutting technology has the advantages of high cutting rate, small environmental load, small mechanical damage on the surfaces of the silicon wafers, less silicon sawdust, easiness in recovery, and small bending degree and total thickness deviation of the silicon wafers, and the diamond wire saw cutting technology can greatly reduce the cost of polycrystalline silicon wafers. Compared with the existing mortar wire saw cutting silicon wafer, the surface of the diamond wire saw cutting silicon wafer always presents obvious cutting lines and higher surface reflectivity. For the diamond-cut polycrystalline silicon wafer, the conventional mixed acid etching texturing is adopted, the reflectivity of the diamond-cut polycrystalline silicon wafer cannot be reduced to the current industrial standard, and the diamond-cut polycrystalline silicon wafer has obvious appearance defects such as line marks and the like, so that the battery efficiency is seriously reduced.
The metal ion assisted texturing technology is a method for better solving texturing of a diamond wire silicon cutting wafer developed in recent years. The technology adopts metal ions such as silver, copper and the like, hydrogen peroxide and hydrofluoric acid to form combined etching liquid, in the process of etching a silicon wafer, the metal ions are reduced into nano particles by silicon and are attached to the surface of the silicon wafer, then the metal particles are used as a cathode, the silicon is used as an anode, and a micro electrochemical reaction channel is formed on the surface of the silicon. The hydrogen peroxide acts on the surface of the silicon to generate silicon dioxide, and the hydrofluoric acid carries out complexation on the silicon dioxide to generate a water-soluble complex, so that micro-nano-scale holes are quickly etched below the nano-metal particles. The hole structure has good light trapping effect. However, due to the boundary effect and the crystal orientation, the size, direction and depth of the opening of the micro-nano-scale hole are often greatly different. The difference causes that the metal ions assist in texturing to form a micro-nano silicon wafer textured surface, the surface color is not uniform, and the phenomenon of color difference exists. After the finished battery piece is prepared, the color difference still exists, the battery piece has a flowering phenomenon, the attractiveness of the battery piece is influenced, and the sale of subsequent components is possibly adversely affected.
Disclosure of Invention
The invention aims to solve the problems that the grain boundary of a textured silicon wafer is obvious and the crystal face is prone to appear in the prior art, and provides a texturing and hole digging additive (also referred to as a hole digging additive for short) for a diamond wire-cut polycrystalline silicon wafer, a texturing and silver-depositing hole digging solution containing the hole digging additive for the diamond wire-cut polycrystalline silicon wafer and a preparation method thereof, a silicon wafer prepared by using the hole digging solution, and a solar cell prepared by using the silicon wafer.
The diamond wire-cut polycrystalline silicon wafer is subjected to texturing by the texturing solution containing the hole digging additive, a truncated cone-shaped micro-nano hole structure with certain shape, size and depth can be formed on the surface of the silicon wafer (the truncated cone can be a quasi-truncated cone or a roughly truncated cone because the hole is of a microstructure), and the corroded micro-nano hole can have small difference in opening size in different crystal directions, hole gradient and hole longitudinal depth after the hole digging additive is used. In addition, the silicon wafer provided by the invention has the advantages of fuzzy grain boundary, uniform color and small chromatic aberration, and the silicon wafer prepared into a battery piece has good appearance and no obvious flowering phenomenon. Compared with the conventional battery obtained by acid texturing of the mortar cut silicon wafer, the photoelectric conversion efficiency of the battery is improved to a certain extent.
The inventor of the present invention has found through intensive research that if no additive is used in the step of silver deposition and hole digging, due to the influence of the surface effect of the nanoparticles and the boundary effect at the grain boundary, the size and depth of the micro-nano-scale holes formed by corrosion in the step are greatly different, and after the subsequent texturing process, the obtained micro-nano-scale holes on the textured silicon wafer have the continuously larger difference in the pore diameter and depth, so that the grain boundary of the textured silicon wafer is obvious, and the crystal face has a blooming phenomenon.
Based on the above findings, the inventors of the present invention tried to intervene in the formation of micro-nano-scale pores of each crystal orientation by using additives in the silver immersion hole-digging process, and found that, when polyethylene glycol having a specific content and a specific molecular weight and additives of a specific corrosion inhibitor are used in the silver immersion hole-digging step, the difference degree of the opening size of the formed micro-nano-scale pores, the inclination of the pores and the longitudinal depth of the pores is small, the grain boundary of the silicon wafer after texturing is relatively fuzzy, the effect is close to the conventional acid texturing effect of mortar cut silicon wafers, and no obvious crystal flower phenomenon exists, thereby completing the present invention.
Therefore, according to a first aspect of the invention, the texturing and hole-digging additive for diamond wire-cutting polycrystalline silicon wafers comprises 0.01-0.20 wt% of polyethylene glycol, 0.01-0.10 wt% of a corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the molecular weight of the polyethylene glycol is 1000 or less, and the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine.
By adding the hole digging additive into the silver sinking hole digging liquid, due to the effect of the hole digging additive, in the step of silver sinking and hole digging of the silicon wafer, the opening size of the formed micro-nano-scale hole, the inclination of the hole and the difference degree of the longitudinal depth of the hole are small, the grain boundary of the silicon wafer after texturing is fuzzy, the effect is close to the conventional acid texturing effect of a mortar cut silicon wafer, and no obvious crystal flower phenomenon exists. In addition, after the subsequent conventional preparation process of the polycrystalline silicon solar cell, namely the processes of diffusion, secondary cleaning, PECVD (plasma enhanced chemical vapor deposition) antireflection film plating, metallization and the like, the obtained polycrystalline silicon solar cell has uniform surface color, small color difference in the cell and no obvious flowering phenomenon.
Preferably, the hole digging additive comprises 0.01-0.10 wt% of polyethylene glycol 400, 0.01-0.10 wt% of polyethylene glycol 600, 0.01-0.10 wt% of corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine.
Preferably, the corrosion inhibitor is selected from mercaptobenzothiazole and/or hexadecylamine.
The second aspect of the invention provides a texturing silver-precipitating hole-digging liquid for diamond wire-cutting polycrystalline silicon wafers, which contains the hole-digging additive provided by the invention, a silver-precipitating agent and an acid solution, wherein the hole-digging additive comprises the following components in percentage by volume: silver deposition agent: 0.1-0.5% of acid solution: 0.1-0.5: 100, the silver precipitation agent contains silver nitrate, nitric acid, a dispersing agent and deionized water, and the acid solution contains hydrofluoric acid, aqueous hydrogen peroxide and deionized water.
Preferably, the dispersant is one or more of polyvinylpyrrolidone, polyacrylamide, sodium dodecylbenzene sulfonate, fatty acid polyglycol ester and sodium carboxymethylcellulose.
Preferably, the silver precipitating agent contains 0.1-1.0 wt% of silver nitrate, 0.1-1.0 wt% of nitric acid, 0.1-1.0 wt% of dispersing agent and 99.7-99.97 wt% of deionized water.
The third aspect of the invention provides a preparation method of a texturing, silver precipitating and hole digging liquid for diamond wire-cutting polycrystalline silicon wafers, wherein the method comprises the steps of preparing a texturing and hole digging additive, a silver precipitating agent and an acid solution, and mixing the texturing and hole digging additive, the silver precipitating agent and the acid solution according to a volume ratio of 0.1-0.5: 0.1-0.5: 100, wherein the additive for making piles and digging holes comprises 0.01-0.20 wt% of polyethylene glycol, 0.01-0.1 wt% of corrosion inhibitor and 99.7-99.97 wt% of deionized water, wherein the molecular weight of the polyethylene glycol is less than 1000, and the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine; the silver precipitation agent contains silver nitrate, nitric acid, a dispersing agent and deionized water; the acid solution contains hydrofluoric acid, aqueous hydrogen peroxide and deionized water.
Preferably, the polyethylene glycol is selected from one or more of polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 800 and polyethylene glycol 1000; more preferably, the polyethylene glycol is selected from polyethylene glycol 400 and polyethylene glycol 600.
Preferably, the additive for making herbs into wool and digging holes comprises 0.01-0.10 wt% of polyethylene glycol 400, 0.01-0.10 wt% of polyethylene glycol 600, 0.01-0.10 wt% of corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine.
Preferably, the corrosion inhibitor is selected from mercaptobenzothiazole and/or hexadecylamine.
According to a fourth aspect of the present invention, there is provided a method for preparing a silicon wafer, the method comprising the steps of subjecting a diamond wire-cut polycrystalline silicon wafer to alkali primary polishing, first acid cleaning, silver deposition and hole digging, hole expanding, porous silicon removal, nano silver particle removal, second acid cleaning and slow pulling, wherein the silver deposition and hole digging step comprises: and carrying out first contact on the diamond wire-cutting polycrystalline silicon wafer cleaned by the first acid and the texturing, silver sinking and hole digging liquid of the diamond wire-cutting polycrystalline silicon wafer.
According to the preparation method of the silicon wafer, the truncated cone-shaped micro-nano hole structure with certain shape, size and depth and the suede with the truncated cone-shaped micro-nano holes can be formed on the surface of the silicon wafer, the collecting effect of photon-generated carriers is good, the short-circuit current and the open-circuit voltage of the battery are improved, and the average photoelectric efficiency of the battery is improved to a certain extent compared with that of a conventional mortar sheet battery.
Preferably, the silver immersion hole digging conditions include: the contact temperature is 20-50 ℃, and the contact time is 120-300 s.
Preferably, the silver sinking and hole digging step further comprises a third cleaning step of using deionized water to carry out a third cleaning on the diamond wire-cutting polycrystalline silicon wafer after the silver sinking and hole digging step.
Preferably, the third cleaning is washing with deionized water for 120-240 s.
Preferably, after the silver depositing and hole digging step, the average reflectivity of the obtained diamond wire-cutting polycrystalline silicon wafer is 1.0-4.0%.
According to a fifth aspect of the present invention, there is provided a silicon wafer produced by the method for producing a silicon wafer of the present invention.
Preferably, the concentration of residual metal atoms or ions on the surface of the silicon wafer is 50ppb or less.
Preferably, the silicon wafer has a truncated cone-shaped micro-nano-scale hole with an opening width, an inclination and a depth, and the maximum difference Δ d1 between the opening widths of the top surfaces of the micro-nano-scale holemax200-300 nm, and the maximum difference value delta α of the included angle between the side surface and the vertical surface of the bottom surfacemaxIs 10-20 degrees, and the maximum difference value delta h of the hole depthsmaxIs 100 to 200 nm.
Preferably, the average light reflectivity of the silicon wafer is within a wave band of 400-1100 nm
18 to 22 percent.
According to a sixth aspect of the present invention, there is provided a solar cell prepared using the silicon wafer of the present invention.
The texturing solution containing the texturing and hole digging additive is adopted to carry out texturing on the diamond wire-cut polycrystalline silicon wafer, so that uniformly distributed micro-nano holes can be obtained on the corroded silicon surface, and particularly, the difference degree of the opening size, the hole inclination and the hole longitudinal depth of the micro-nano holes with different crystal directions is small. In addition, the silicon wafer provided by the invention has the advantages of fuzzy grain boundary, uniform color and small chromatic aberration, and the silicon wafer has good appearance and no obvious blooming phenomenon after being prepared into a battery piece.
In addition, compared with the acid flocking sheet of the common mortar sheet, the silicon wafer prepared by the invention has a certain reduction in reflectivity, and the average light reflectivity of the silicon wafer is within a 400-1100 nm waveband
18-22%, therefore, the solar cell has good collection effect of photon-generated carriers, the short-circuit current and the open-circuit voltage of the cell are higher, and the average photoelectric efficiency is improved to a certain extent compared with the cell prepared by the conventional mortar silicon slice.
Drawings
FIG. 1 is a schematic cross-sectional view of a truncated cone-shaped micro-nano-scale hole along a central axis of a diamond wire-cut silicon wafer after texturing the silicon wafer by the method of the present invention.
Fig. 2 is an SEM image (magnified 50000 times) of micro-nano-scale holes with inverted bell-mouth shapes on a certain crystal orientation on a silicon surface after texturing a diamond wire-cut silicon wafer by using the method according to the embodiment of the present invention.
Fig. 3 is an SEM image (10000 times magnification) of a crater of a certain crystal orientation on a silicon surface after a mortar-cut silicon wafer is subjected to texturing using a conventional acid.
FIG. 4 is a physical appearance diagram of a silicon wafer with a textured surface after texturing is performed on a diamond wire cut silicon wafer by the methods of embodiments 1 to 9 of the present invention.
FIG. 5 is a physical appearance diagram of a silicon wafer with a textured surface after texturing a diamond wire cut silicon wafer by using the method of comparative example 1 or comparative example 2 of the present invention.
FIG. 6 is a physical appearance diagram of a silicon wafer with a textured surface after a mortar cut silicon wafer is textured with a conventional acid by using the method of comparative example 3 of the present invention.
Fig. 7 is a physical appearance diagram of a diamond wire-cut silicon wafer subjected to texturing and prepared into a solar cell by the methods of embodiments 1 to 9 of the present invention.
Fig. 8 is a diagram showing an appearance of a diamond wire-cut silicon wafer subjected to texturing by the method of comparative example 1 or comparative example 2 according to the present invention, and then the silicon wafer is fabricated into a solar cell.
Fig. 9 is a diagram showing the appearance of a mortar-cut silicon wafer subjected to texturing using a conventional acid and prepared into a solar cell by the method of comparative example 3.
Description of the reference numerals
1 is a micro-nano-scale hole, 2 is a velvet surface layer, d1 is the opening width of the top surface of the micro-nano-scale hole, d2 is the width of the bottom surface of the micro-nano-scale hole, h is the depth of the micro-nano-scale hole, and α is the included angle between the side surface of the micro-nano-scale hole and the vertical surface of the bottom surface.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The additive for making the texture etching and the hole digging of the diamond wire-cutting polycrystalline silicon wafer, the texture etching, silver sinking and hole digging solution for the diamond wire-cutting polycrystalline silicon wafer and the preparation method thereof, the silicon wafer and the preparation method thereof, and the solar cell are respectively explained below.
1. Texturing and hole digging additive for diamond wire cutting polycrystalline silicon wafer
The invention provides a texturing and hole digging additive for diamond wire cutting polycrystalline silicon wafers, wherein the hole digging additive comprises 0.01-0.20 wt% of polyethylene glycol, 0.01-0.10 wt% of corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the molecular weight of the polyethylene glycol is less than 1000, and the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine.
The hole digging additive is used for the silver immersion and hole digging step of diamond wire cutting polycrystalline silicon slices, and the hole digging additive is added into the silver immersion and hole digging step, so that the opening size of the formed micro-nano-scale holes, the inclination of the holes and the difference degree of the longitudinal depth of the holes are small in the silver immersion and hole digging step due to the effect of the hole digging additive, the grain boundary of the silicon slice after texturing is fuzzy, the effect of the silicon slice is close to the conventional acid texturing effect of a mortar silicon slice, and the obvious crystal pattern phenomenon does not exist. In addition, after the subsequent conventional polycrystalline solar cell preparation process, namely the processes of diffusion, secondary cleaning, PECVD (plasma enhanced chemical vapor deposition) antireflection film plating, metallization and the like, the obtained polycrystalline solar cell has uniform surface color, small color difference in the cell and no obvious flowering phenomenon.
In order to further improve the color uniformity of the silicon wafer after texturing, the hole digging additive preferably contains 0.05 to 0.10 weight percent of polyethylene glycol, 0.03 to 0.08 weight percent of corrosion inhibitor and 99.82 to 99.92 weight percent of deionized water.
Preferably, the polyethylene glycol is selected from one or more of polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 800 and polyethylene glycol 1000.
Furthermore, from the viewpoint of further enhancing the effect of removal of subsequent additives, it is preferable that the corrosion inhibitor is selected from mercaptobenzothiazole and/or hexadecylamine.
In a preferred embodiment of the invention, the etching and hole digging additive for diamond wire-cutting polycrystalline silicon wafers is provided, wherein the hole digging additive comprises 0.01-0.10 wt% of polyethylene glycol 400, 0.01-0.10 wt% of polyethylene glycol 600, 0.01-0.1 wt% of a corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine.
By combining polyethylene glycol 400 and polyethylene glycol 600, there is an advantage in that the amount of polyethylene glycol used is reduced.
In the above preferred embodiment, in order to further improve the color uniformity of the silicon wafer after texturing, the texturing and hole-digging additive preferably contains 0.02 to 0.05 wt% of polyethylene glycol 400, 0.02 to 0.05 wt% of polyethylene glycol 600, 0.03 to 0.08 wt% of a corrosion inhibitor, and 99.82 to 99.93 wt% of deionized water.
Furthermore, from the viewpoint of further enhancing the effect of removal of subsequent additives, it is preferable that the corrosion inhibitor is selected from mercaptobenzothiazole and/or hexadecylamine.
2. Texturing silver-sinking hole digging liquid for diamond wire cutting polycrystalline silicon wafer
The second aspect of the invention provides a texturing silver-depositing hole-digging liquid for diamond wire-cutting polycrystalline silicon wafers, which contains the texturing hole-digging additive, a silver-depositing agent and an acid solution, wherein the texturing hole-digging additive comprises the following components in percentage by volume: silver deposition agent: 0.1-0.5% of acid solution: 0.1-0.5: 100, the silver precipitation agent contains silver nitrate, nitric acid, a dispersing agent and deionized water, and the acid solution contains hydrofluoric acid, aqueous hydrogen peroxide and deionized water.
Preferably, the hole making and digging additive comprises the following components in percentage by volume: silver deposition agent: 0.2-0.4% of acid solution: 0.2-0.4: 100.
the dispersant may be various substances commonly used in the art for dispersion, and preferably, the dispersant is one or more of polyvinylpyrrolidone, polyacrylamide, sodium dodecylbenzene sulfonate, fatty acid polyglycol ester, and sodium carboxymethylcellulose; more preferably, the dispersant is polyvinylpyrrolidone.
Preferably, the silver precipitating agent contains 0.1-1.0 wt% of silver nitrate, 0.1-1.0 wt% of nitric acid, 0.1-1.0 wt% of dispersing agent and 99.70-99.97 wt% of deionized water; more preferably, the silver precipitating agent contains 0.3-0.8 wt% of silver nitrate, 0.2-0.5 wt% of nitric acid, 0.2-0.5 wt% of dispersing agent and 98.20-99.30 wt% of deionized water.
Preferably, the acid solution consists of hydrofluoric acid: aqueous hydrogen peroxide solution: deionized water (20-30): (1-5): (70-90); more preferably, the acid solution consists of hydrofluoric acid: aqueous hydrogen peroxide solution: deionized water (22-28): (2-4): (75-85).
Preferably, the concentration of the aqueous hydrogen peroxide solution is 1.1 to 5.4 wt%; more preferably, the concentration of the aqueous hydrogen peroxide solution is 1.5 to 4.5 wt%.
3. Preparation method of texturing, silver sinking and hole digging liquid for diamond wire cutting polycrystalline silicon wafer
The third aspect of the invention provides a preparation method of the texturing, silver precipitating and hole digging liquid for the diamond wire-cutting polycrystalline silicon wafer, wherein the method comprises the steps of preparing a texturing and hole digging additive, a silver precipitating agent and an acid solution, and mixing the texturing and hole digging additive, the silver precipitating agent and the acid solution according to a volume ratio of 0.1-0.5: 0.1-0.5: 100, wherein the additive for making piles and digging holes comprises 0.01-0.20 wt% of polyethylene glycol, 0.01-0.1 wt% of corrosion inhibitor and 99.7-99.97 wt% of deionized water, wherein the molecular weight of the polyethylene glycol is less than 1000, and the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine; the silver precipitation agent contains silver nitrate, nitric acid, a dispersing agent and deionized water; the acid solution contains hydrofluoric acid, aqueous hydrogen peroxide and deionized water.
Preferably, the polyethylene glycol is selected from one or more of polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 800 and polyethylene glycol 1000; more preferably, the polyethylene glycol is selected from polyethylene glycol 400 and polyethylene glycol 600.
Preferably, the additive for making herbs into wool and digging holes comprises 0.01-0.10 wt% of polyethylene glycol 400, 0.01-0.10 wt% of polyethylene glycol 600, 0.01-0.10 wt% of corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine.
Preferably, the corrosion inhibitor is selected from mercaptobenzothiazole and/or hexadecylamine.
Preferably, the wool making and hole digging additive, the silver precipitation agent and the acid solution are mixed in a volume ratio of 0.2-0.4: 0.2-0.4: 100 were mixed.
The dispersant may be various substances commonly used in the art for dispersion, and preferably, the dispersant is one or more of polyvinylpyrrolidone, polyacrylamide, sodium dodecylbenzene sulfonate, fatty acid polyglycol ester, and sodium carboxymethylcellulose; more preferably, the dispersant is polyvinylpyrrolidone.
Preferably, the silver precipitating agent contains 0.1-1.0 wt% of silver nitrate, 0.1-1.0 wt% of nitric acid, 0.1-1.0 wt% of dispersing agent and 99.70-99.97 wt% of deionized water; more preferably, the silver precipitating agent contains 0.3-0.8 wt% of silver nitrate, 0.2-0.5 wt% of nitric acid, 0.2-0.5 wt% of dispersing agent and 98.20-99.30 wt% of deionized water.
Preferably, the acid solution consists of hydrofluoric acid: aqueous hydrogen peroxide solution: deionized water (20-30): (1-5): (70-90); more preferably, the acid solution consists of hydrofluoric acid: aqueous hydrogen peroxide solution: deionized water (22-28): (2-4): (75-85).
Preferably, the concentration of the aqueous hydrogen peroxide solution is 1.1 to 5.4 wt%; more preferably, the concentration of the aqueous hydrogen peroxide solution is 1.5 to 4.5 wt%.
4. Preparation method of silicon wafer
According to a fourth aspect of the present invention, there is provided a method for preparing a silicon wafer, the method comprising the steps of subjecting a diamond wire-cut polycrystalline silicon wafer to alkali primary polishing, first acid cleaning, silver deposition and hole digging, hole expanding, porous silicon removal, nano silver particle removal, second acid cleaning and slow pulling, wherein the silver deposition and hole digging step comprises: and carrying out first contact on the diamond wire-cutting polycrystalline silicon wafer cleaned by the first acid and the texturing, silver sinking and hole digging liquid of the diamond wire-cutting polycrystalline silicon wafer.
According to the preparation method of the silicon wafer, the truncated cone-shaped micro-nano hole structure with certain shape, size and depth can be formed on the surface of the silicon wafer, the suede with the truncated cone-shaped micro-nano holes is provided, the collection effect of photon-generated carriers is good, the short-circuit current and the open-circuit voltage of the battery are higher, and the average photoelectric efficiency of the battery is improved to a certain extent compared with the battery prepared by cutting the silicon wafer by conventional mortar.
The method for producing the silicon wafer of the present invention will be explained below in terms of steps.
S1: preliminary alkali polishing step
In the invention, the diamond wire-cut polycrystalline silicon wafer is subjected to alkali primary polishing for the purposes of eliminating nicks of diamond wires and obtaining a flat silicon surface.
The manner of the alkali initial polishing is not particularly limited, and various manners generally used in the art may be employed, and preferably, the diamond wire-cut polycrystalline silicon wafer is initially polished using an alkali solution.
Preferably, the conditions of the primary polishing include: the temperature of the primary polishing solution is 60-90 ℃, and the reaction time is 60-300 s; more preferably, the conditions of the primary polishing include: the temperature of the primary polishing solution is 70-85 ℃, and the reaction time is 180-240 s.
Preferably, the concentration of the alkali solution is 2.0 to 15 wt%, more preferably 4.0 to 9.0 wt%.
Preferably, the alkali solution is an aqueous solution of sodium hydroxide or potassium hydroxide.
Preferably, the alkali initial polishing step further comprises a first cleaning of the diamond wire-cut polycrystalline silicon wafer with deionized water after the alkali initial polishing step. Preferably, the first cleaning is performed by deionized water leaching for 120-240 s.
Preferably, after the initial polishing step, the weight reduction rate of the obtained diamond wire-electrode cutting polycrystalline silicon wafer is 2.0-3.5 wt%, more preferably 2.3-3.2 wt%, and even more preferably 2.4-2.8 wt%.
S2: first acid cleaning step
In the present invention, in order to remove the alkali remaining in step S1, the diamond wire-cut polycrystalline silicon wafer is subjected to a first acid cleaning.
Preferably, the conditions of the first acid wash include: the temperature is 10-45 ℃ and the time is 50-150 seconds; more preferably, the conditions of the first acid wash include: the temperature is 20-30 ℃ and the time is 80-120 seconds
Preferably, the concentration of the acid solution used for the first acid cleaning is 0.2 to 2.0 wt%, and more preferably 0.5 to 1.0 wt%.
Preferably, the acid solution used for the first acid cleaning is a nitric acid solution.
Preferably, the first acid cleaning step further comprises performing a second cleaning on the diamond wire-cut polycrystalline silicon wafer using deionized water after the first acid cleaning step. Preferably, the second cleaning is performed by rinsing with deionized water for 120-240 s.
S3: silver depositing and hole digging step
In the invention, the silver depositing and hole digging step comprises the following steps: and carrying out first contact on the diamond wire-cutting polycrystalline silicon wafer cleaned by the first acid and the texturing, silver sinking and hole digging liquid of the diamond wire-cutting polycrystalline silicon wafer.
In the silver sinking and hole digging step, nano silver particles on the surface of a polycrystalline silicon wafer are used as a cathode, silicon is used as an anode, a micro electrochemical reaction channel is formed on the surface of the silicon, and hydrogen peroxide and hydrofluoric acid are jointly used as etching liquid, so that a micro-nano hole structure is quickly etched below the nano silver particles.
Further, since the etching action of the chemical solution on silicon in the same crystal orientation is substantially the same except for the crystal boundaries, the shape, the diameter, the inclination of the open hole, and the longitudinal depth of the hole in the same crystal orientation are substantially the same. However, for different crystal orientations, the etching speeds of the mixed acid in the crystal orientations are generally different and have large differences due to the etching anisotropy, so that the parameters of the micro-nano-scale holes formed by etching with the mixed acid in the different crystal orientations have large differences. According to the invention, the etching of silicon by mixed acid is slightly inhibited by adding the etching agent for making the texture in the silver sinking and hole digging steps, and the difference of different crystal orientations of polycrystalline silicon by the mixed acid is reduced, so that the difference between the pore diameter and the longitudinal depth of the micro-nano-scale holes formed in different crystal orientations is reduced under the condition of catalytic etching of metal nano-silver, thereby reducing the chromatic aberration among the grain boundaries of the textured silicon wafer, blurring the grain boundaries and avoiding the phenomenon of flower formation.
Preferably, the silver immersion hole digging conditions include: the contact temperature is 20-50 ℃, and the contact time is 120-300 s; more preferably, the silver immersion hole digging conditions include: the contact temperature is 30-40 ℃, and the contact time is 180-240 s.
Preferably, the silver sinking and hole digging step further comprises a third cleaning step of using deionized water to carry out a third cleaning on the diamond wire-cutting polycrystalline silicon wafer after the silver sinking and hole digging step. Preferably, the third cleaning is washing with deionized water for 120-240 s.
In view of further optimizing the relationship between the pore diameter and the depth of the nano-micropores, the weight reduction rate of the diamond wire-cut polycrystalline silicon wafer obtained after the silver immersion and hole digging step is preferably 0.18 to 0.93 wt%, more preferably 0.24 to 0.86 wt%, and still more preferably 0.37 to 0.74 wt%.
In addition, in view of further improving the light trapping performance of the surface of the silicon wafer, the average reflectivity of the diamond wire-cut polycrystalline silicon wafer obtained after the silver immersion and hole digging step is preferably 1.0-4.0%, and more preferably 2.0-3.5%.
S4: reaming step
According to the present invention, preferably, the reaming step comprises: and enabling a mixed acid solution of nitric acid and hydrofluoric acid to be in second contact with the diamond wire-cutting polycrystalline silicon wafer subjected to the silver immersion and hole digging step.
Preferably, the conditions of the second contacting include: the contact temperature is 8-15 ℃, and the contact time is 120-250 s.
Preferably, the volume ratio of the mixed acid solution of nitric acid and hydrofluoric acid is nitric acid: hydrofluoric acid: water (5-9): 1: (7-10).
Preferably, the reaming step further comprises performing a fourth cleaning on the diamond wire-cut polycrystalline silicon wafer with deionized water after the reaming step.
Preferably, the fourth cleaning is washing with deionized water for 120-240 s.
In the step, the micro-nano-scale hole formed by etching the silicon surface is jointly etched by nitric acid and hydrofluoric acid, so that the round platform-shaped micro-nano-scale hole with the shape of the inverted trumpet is formed.
Preferably, after the reaming step, the weight reduction rate of the obtained diamond wire-cut polycrystalline silicon wafer is 0.92-1.85 wt%, more preferably 1.1-1.85 wt%, and further preferably 1.39-1.67 wt%.
S5: step of removing porous silicon
According to the present invention, preferably, the step of removing porous silicon comprises: and enabling sodium hydroxide or potassium hydroxide solution to be in third contact with the diamond wire-cutting polycrystalline silicon wafer after the hole expanding step.
Preferably, the conditions of the third contacting include: the contact temperature is 10-45 ℃, and the contact time is 5-50 s.
Preferably, the concentration of the sodium hydroxide solution and the concentration of the potassium hydroxide solution are each 0.2 to 5.0 wt%.
Preferably, the step of removing porous silicon further comprises performing a fifth cleaning of the diamond wire-cut polycrystalline silicon wafer using deionized water after the step of removing porous silicon. Preferably, the fifth cleaning is washing with deionized water for 120-240 s.
S6: step of removing porous silicon
According to the present invention, preferably, the step of removing the nano silver particles comprises: and fourthly, enabling the mixed solution of ammonia water and hydrogen peroxide to be in fourth contact with the diamond wire-cutting polycrystalline silicon wafer after the step of removing the porous silicon.
Preferably, the conditions of the fourth contacting include: the contact temperature is 10-45 ℃, and the contact time is 50-300 s.
Preferably, the mixing volume ratio of the mixed solution of ammonia and hydrogen peroxide is ammonia water: hydrogen peroxide: water 1: (1-4): (30-50); more preferably, the mixing volume ratio of the mixed solution of ammonia and hydrogen peroxide is ammonia: hydrogen peroxide: water 1: (2-3): (35-45).
Preferably, the step of removing the nano silver particles further comprises a sixth cleaning of the diamond wire-cutting polycrystalline silicon wafer by using deionized water after the step of removing the nano silver particles. Preferably, the sixth cleaning is washing with deionized water for 120-240 s.
S7: second acid cleaning step
More preferably, the second acid washing conditions include: the cleaning temperature is 10-45 ℃, and the cleaning time is 50-300 s.
Preferably, the acid solution used for the second acid cleaning is a mixed acid solution of hydrofluoric acid and hydrochloric acid.
Preferably, the mixing volume ratio of the mixed acid solution of hydrofluoric acid and hydrochloric acid is hydrofluoric acid: hydrochloric acid: water 1: (1-5): (3-8); more preferably, the mixed volume ratio of the mixed acid solution of hydrofluoric acid and hydrochloric acid is hydrofluoric acid: hydrochloric acid: water 1: (2-3): (5-6).
Preferably, the second acid cleaning step further comprises a seventh cleaning of the diamond wire-cut polycrystalline silicon wafer with deionized water after the second acid cleaning. Preferably, the seventh cleaning is performed by deionized water leaching for 120-240 s.
S8: slow pulling step
According to the present invention, preferably, the slow pulling step comprises: and cleaning the polycrystalline silicon wafer with deionized water at the temperature of 60-80 ℃ for 120-240 seconds, and then slowly lifting the polycrystalline silicon wafer to lift the polycrystalline silicon wafer from the water surface.
In addition, in order to ensure that the silicon wafer is cleaned and the residual ion concentration of water in the tank is controlled, a conductivity meter is preferably adopted to test the resistance value of the deionized water, and the conductivity value is controlled to be less than or equal to 1.0 mu S/cm at the temperature of 70 +/-2 ℃.
S9: drying step
According to the present invention, preferably, the method further comprises: a step of drying after the slow pulling step;
preferably, the drying conditions include: the drying temperature is 100-150 ℃, and the drying time is 300-900 s.
5. Silicon wafer
According to a fifth aspect of the present invention, there is provided a silicon wafer produced by the method for producing a silicon wafer of the present invention.
According to the silicon wafer of the present invention, it is preferable that the concentration of metal atoms or ions remaining on the surface of the silicon wafer is 50ppb or less. The above concentrations were measured using an inductively coupled plasma mass spectrometer (ICP-MS).
Further, as shown in FIG. 4, the present inventionThe silicon wafer has uniform surface texture making and no crystal boundary phenomenon. In addition, the average light reflectivity is detected by a suede reflectivity meter within a wave band of 400-1100 nm
Preferably 18 to 22%.
When the textured surface of the silicon wafer of the present invention is observed under a Scanning Electron Microscope (SEM), it can be seen that the textured surface is composed of truncated cone-shaped micro-nano-scale holes having a certain opening width, inclination angle, and hole depth. As shown in FIGS. 1 and 2, when the opening width of the truncated cone-shaped micro-nano-scale hole is d1 (i.e., the width of the top surface of the hole), the maximum difference Δ d1 between the opening widths of the top surfacesmax200-300 nm, and the maximum difference value delta α of the included angle between the vertical surfaces of the side surface and the bottom surface of the truncated cone-shaped micro-nano-scale hole is αmaxIs 10-20 degrees, and when the hole depth of the truncated cone-shaped micro-nano-scale hole is h, the maximum difference value delta h of the hole depthsmaxIs 100 to 200 nm.
6. Solar cell
According to a seventh aspect of the present invention, there is provided a solar cell prepared using the silicon wafer of the present invention.
According to the present invention, there is no particular limitation in the preparation of a solar cell, and other steps and conditions may be carried out according to conventional steps and conditions in the art, except for using the silicon wafer of the present invention. For example, the following method can be used.
The silicon chip of the invention enters a diffusion furnace to prepare PN junctions through phosphorus diffusion, and the diffusion process is approximately the same as that of a mortar silicon chip textured by conventional acid.
In the invention, the average sheet resistance of the diffused silicon wafer is preferably adjusted to 85-90 omega/□ by adjusting the diffusion temperature or the phosphorus source amount, and the matching degree of the sheet resistance range and the silicon wafer texture surface is better.
After the diffusion process, the silicon wafer is subjected to secondary cleaning to remove the PSG layer and etch the periphery of the silicon wafer; then, PECVD is carried out for SiN platingxAnd (5) processing the antireflection film. The coating process is approximately the same as that of the conventional acid textured mortar sheet. The thickness of the antireflection film can be controlled to be 80-85 nm, and the average refractive index is controlled to be 2.00-2.20. And printing back silver paste, back aluminum paste and front silver paste on the coated silicon wafer, and sintering the silicon wafer in a sintering furnace to obtain the polycrystalline silicon solar cell.
The present invention will be described in detail below by way of examples.
Example 1
The resistivity value range of the 156mm multiplied by 156mm polycrystalline silicon wafer cut by diamond wires is 1.20-2.50 omega cm, and the resistivity requirement of the silicon wafer is met. The minority carrier lifetime value range is 1.10-1.60 mu s, and the minority carrier lifetime requirement of the silicon wafer is met. Each time, 200 pieces (2 flower baskets, 100 pieces per basket) are adopted for the experiment, the experimental results are averaged, and the volume of each process tank is 120 liters.
The whole texturing process comprises the following process steps:
s1 (alkali initial polishing): adding 15L of potassium hydroxide solution into the primary polishing groove, adding 105L of water to obtain 7.83% of potassium hydroxide solution, heating the solution to 80 ℃, putting the silicon wafer into the solution, and etching for 240 s. And after the etching is finished, the silicon wafer is washed for 150s away from water, and the polycrystalline silicon wafer without greasy dirt and damage layers is obtained. The weight loss in this step was 2.61 wt% by electronic weighing.
S2 (first acid wash): and (3) putting the silicon wafer in the step into a cleaning tank, wherein the cleaning solution in the cleaning tank is diluted nitric acid with the volume concentration of 1.0%, the cleaning time is 120s, and the silicon wafer is cleaned for 150s away from water.
S3 (depositing nano silver and digging micro-nano-scale holes, also called silver depositing and digging holes): the method comprises the following steps.
1) Preparing a hole digging additive: according to the mass percentage, 0.02 percent of polyethylene glycol 400, 0.02 percent of polyethylene glycol 600, 0.05 percent of mercaptobenzothiazole and the balance of deionized water are mixed evenly to prepare 1000g of hole digging additive.
2) Preparing a mixed acid solution: 24L of hydrofluoric acid, 2.5L of hydrogen peroxide and 82L of deionized water are added into the silver sinking hole digging groove and mixed evenly to obtain 108.5L of mixed acid solution for silver sinking hole digging.
3) Preparing a silver precipitation agent: according to the following mass percentage, 0.60 percent of silver nitrate, 0.50 percent of nitric acid, 0.02 percent of polyvinylpyrrolidone (PVP) and the balance of deionized water are uniformly mixed to prepare 1000g of silver precipitating agent.
4) Preparing a wool making silver precipitating hole digging liquid: adding 400mL of the hole digging additive prepared in the step 1) into 108.5L of the mixed acid solution for hole digging obtained in the step 2), adding 250mL of the silver precipitating agent prepared in the step 3), and uniformly mixing, wherein the hole digging additive: silver deposition agent: the volume ratio of the mixed acid is 0.37: 0.23: and 100, obtaining the wool making silver deposition hole digging liquid.
5) And (4) placing the silicon wafer cleaned in the step S2 in a texture-making silver-precipitating hole digging liquid tank. The reaction temperature was 35 ℃ and the reaction time was 230 s. The nano silver particles on the surface of the silicon wafer are used as a cathode, the silicon is used as an anode, a micro electrochemical reaction channel is formed on the surface of the silicon, and hydrogen peroxide and hydrofluoric acid are combined to be used as etching liquid, so that a micro-nano hole structure is quickly etched below the nano silver particles. The reflectivity of the polycrystalline silicon wafer after silver deposition and hole digging is tested to be 2.5 percent by a reflectivity tester. The weight reduction in this step was 0.55% by weight as measured by an electronic scale. And after the silver deposition and hole digging are finished, cleaning the silicon wafer for 150s by using deionized water.
S4 (hole expansion): placing the silicon wafer in the last step into a micro-nano scale hole cutting and expanding groove, wherein the volume ratio of nitric acid to hydrofluoric acid in the groove is as follows: hydrofluoric acid: water 7: 1: 9, the temperature of the mixed acid solution is 12 ℃, the reaction time is 170 seconds, the silicon wafer is taken out after the reaction is finished, the silicon wafer is washed for 150 seconds away from water, and the weight loss rate of the working procedure is 1.16 percent by weight by an electronic scale.
S5 (nanoporous silicon): and (3) putting the silicon wafer in the step into a tank with sodium hydroxide to perform correction reaction, wherein the mass concentration of the sodium hydroxide is 2.0%. The reaction temperature is 20 ℃, the reaction time is 15s, and after the reaction is finished, the silicon wafer is washed away from water for 150 s.
S6 (removal of nano silver particles): and (3) putting the silicon wafer in the step into a mixed liquid tank of ammonia water and hydrogen peroxide to clean the nano silver particles, wherein the volume concentration of the ammonia water in the tank is 3.0%, and the volume concentration of the hydrogen peroxide in the tank is 5%. The temperature of the solution was 20 c and the cleaning time was 200 seconds, after which the wafer was washed away from water for 150 seconds.
S7 (second acid wash): and (3) cleaning the silicon wafer in the previous step in a mixed acid solution of hydrofluoric acid and hydrochloric acid, wherein the volume concentration of the hydrofluoric acid in the mixed solution is 10%, the volume concentration of the hydrochloric acid is 20%, the temperature of the solution is 20 ℃, the pickling time is 200s, and then cleaning the silicon wafer in water for 150 s.
S8 (slow pull): and cleaning the silicon wafer cleaned in the previous step for 150s by adopting hot deionized water, wherein the temperature of the water is 70 ℃, and then slowly lifting and pulling the silicon wafer out of the water surface. The pulling time was 10 seconds. And testing the conductivity value of the deionized water in the tank at 70 ℃ to be 0.50-0.70S/cm by using a conductivity meter.
S9 (dry): and (3) carrying out heat drying on the silicon wafer cleaned in the previous step, wherein the drying temperature is 120 ℃, and the drying time is 600 s.
After the above steps are carried out, the silicon wafer K1 prepared in the embodiment is obtained, and the ICP-MS instrument is adopted to test the concentration of residual silver particles on the surface of the silicon wafer K1 to be 17.50 ppb.
After the silicon chip with the texture surface characteristic is prepared, the silicon chip enters a diffusion furnace to prepare PN junctions through phosphorus diffusion, the diffusion process is approximately the same as that of a mortar silicon chip subjected to conventional acid texturing, and the average square resistance value of the diffused silicon chip is 88 omega/□. After the diffusion process, the silicon wafer is subjected to a secondary cleaning process; then, the silicon wafer is subjected to PECVD SiN platingxAnd (3) processing an antireflection film, wherein the average thickness of the antireflection film is 83nm, the average refractive index is 2.06, and then printing back aluminum paste, back paste and front silver paste on a silicon wafer, and sintering in a sintering furnace to obtain the polycrystalline silicon solar cell. The solar cell sheet obtained in this example was designated KK 1.
Example 2
The procedure was carried out in the same manner as in example 1 except that step 1) in the S3 (silver immersion hole drilling) step in example 1 was replaced with the following hole drilling additive placement method. The micro-nano textured silicon wafer prepared by the embodiment is marked as K2, and the obtained solar cell is marked as KK 2. In addition, the silicon wafer surface obtained in this example was tested by an ICP-MS instrument to have a residual silver particle concentration of 19.83 ppb.
Preparing a hole digging additive: according to the mass percentage, 0.01 percent of polyethylene glycol 400, 0.01 percent of polyethylene glycol 600, 0.01 percent of mercaptobenzothiazole and 99.97 percent of deionized water are taken to be evenly mixed to prepare 1000g of hole digging additive.
Example 3
The procedure was carried out in the same manner as in example 1 except that step 1) in the S3 (silver immersion hole drilling) step in example 1 was replaced with the following hole drilling additive placement method. The micro-nano textured silicon wafer prepared by the embodiment is marked as K3, and the obtained solar cell is marked as KK 3. In addition, the silicon wafer surface prepared in this example was tested by an ICP-MS instrument for a residual silver particle concentration of 24.43 ppb.
Preparing a hole digging additive: according to the mass percentage, 0.1 percent of polyethylene glycol 400, 0.1 percent of polyethylene glycol 600, 0.1 percent of hexadecylamine and 99.7 percent of deionized water are taken to be evenly mixed to prepare 1000g of hole digging additive
Example 4
The procedure was carried out in the same manner as in example 1 except that step 4) in the step S3 (silver immersion hole drilling) in example 1 was replaced with the following method for disposing a matte silver immersion hole drilling liquid. The micro-nano textured silicon wafer prepared by the embodiment is marked as K4, and the obtained solar cell is marked as KK 4. In addition, the silicon wafer surface obtained in this example was tested by an ICP-MS instrument to have a residual silver particle concentration of 21.93 ppb.
Preparing a wool making silver precipitating hole digging liquid: adding 120mL of the hole digging additive prepared in the step 1) into 108.5L of the mixed acid solution for hole digging obtained in the step 2), adding 250mL of the silver precipitating agent prepared in the step 3), and uniformly mixing, wherein the hole digging additive: silver deposition agent: the volume ratio of the mixed acid is 0.11: 0.23: and 100, obtaining the wool making silver deposition hole digging liquid.
Example 5
The procedure was carried out in the same manner as in example 1 except that step 3) in the S3 (silver deposition and hole drilling) step in example 1 was replaced with the following silver deposition agent arranging method. The micro-nano textured silicon wafer prepared by the embodiment is marked as K5, and the obtained solar cell is marked as KK 5. In addition, the silicon wafer surface prepared in this example was tested by an ICP-MS instrument to have a residual silver particle concentration of 22.67 ppb.
Preparing a silver precipitation agent: according to the following mass percentage, 1.0 percent of silver nitrate, 0.50 percent of nitric acid, 0.10 percent of polyvinylpyrrolidone (PVP) and the balance of deionized water are uniformly mixed to prepare 1000g of silver precipitating agent.
Example 6
The reflectance of the polycrystalline silicon wafer after silver immersion and hole excavation was measured by a reflectance meter to be 3.8% and the weight loss in this step was measured by an electronic scale to be 0.24% by weight in the same manner as in example 1, except that in step 5) in the step S3 (silver immersion and hole excavation) in example 1, the reaction temperature was changed to 20 ℃ and the reaction time was changed to 230 seconds. The micro-nano textured silicon wafer prepared by the embodiment is marked as K6, and the obtained solar cell is marked as KK 6. In addition, the silicon wafer surface obtained in this example was tested by an ICP-MS instrument for a residual silver particle concentration of 17.33 ppb.
Example 7
The reflectance of the polycrystalline silicon wafer after silver immersion and hole excavation was measured by a reflectance meter to be 2.0% and the weight loss in this step was measured by an electronic balance to be 0.86% in the same manner as in example 1, except that in step 5) in the step S3 (silver immersion and hole excavation) in example 1, the reaction temperature was changed to 35 ℃ and the reaction time was changed to 300 seconds. The micro-nano textured silicon wafer prepared by the embodiment is marked as K7, and the obtained solar cell is marked as KK 7. In addition, the silicon wafer surface prepared in this example was tested by an ICP-MS instrument to have a residual silver particle concentration of 28.64 ppb.
Example 8
The weight reduction rate in this step (hole expansion) was 1.16 wt% by electronic weighing in the same manner as in example 1, except that the temperature of the mixed acid solution in the step S4 (hole expansion) in example 1 was changed to 9 ℃. The micro-nano textured silicon wafer prepared by the embodiment is marked as K8, and the obtained solar cell is marked as KK 8. In addition, the silicon wafer surface prepared in this example was tested by an ICP-MS instrument to have a residual silver particle concentration of 25.54 ppb.
Example 9
The weight reduction in this step (hole expansion) was 1.85 wt% by electronic weighing in the same manner as in example 1, except that the reaction time in the step S4 (hole expansion) in example 1 was changed to 250S. The micro-nano textured silicon wafer prepared by the embodiment is marked as K9, and the obtained solar cell is marked as KK 9. The silicon wafer surface prepared in this example was tested by an ICP-MS instrument for a residual silver particle concentration of 17.64 ppb.
Comparative example 1
The same procedure as in example 1 was repeated except that step 1) in the S3 (silver immersion hole digging) step in example 1) was removed, and 400mL of the wool making hole digging additive in step 4) was removed. The textured silicon wafer prepared in the comparative example is marked as DK1, and the obtained solar cell is marked as DKK 1. In addition, the silicon wafer surface prepared in this example was tested by an ICP-MS instrument to have a residual silver particle concentration of 18.87 ppb.
Comparative example 2
The procedure was repeated as in example 1 except that mercaptobenzothiazole was used in an amount of 0.01% in the hole-digging additive prepared in step S3 (silver deposition hole-digging) in example 1 in place of benzotriazole in an amount of 0.01%. The micro-nano textured silicon wafer prepared by the comparative example is marked as DK2, and the obtained solar cell is marked as DKK 2. In addition, the silicon wafer surface prepared in this example was tested by an ICP-MS instrument to have a residual silver particle concentration of 37.69 ppb.
Comparative example 3
156mm × 156mm polycrystalline silicon wafers cut by mortar are used, the polycrystalline silicon suede is prepared on a Schmid or Rena chain machine by using traditional mixed acid (namely, a one-step cleaning process), the suede silicon wafer of the comparative example is obtained, and the subsequent battery preparation process is the same as that of the example 1. The textured silicon wafer prepared in the comparative example is marked as DK3, and the obtained solar cell is marked as DKK 3.
Performance testing
Characterization parameters of the textured silicon wafer: under a Scanning Electron Microscope (SEM), the micro-nano-scale holes of the textured silicon wafer obtained in each example and each comparative example are observed and tested, and the shape parameters of the micro-nano-scale holes are as follows:the maximum difference between the width of the top opening (d1, unit: nm) and the width of the top opening of the micro-nano-scale hole in the same silicon wafer (delta d 1)max) The maximum difference between the angle between the vertical surfaces of the side and bottom surfaces (α, unit: degree) and the micro-nano-scale hole of the same silicon wafer (Delta α)maxThe unit: degree), depth of the hole (h, unit: nm), maximum difference in depth (Δ h) of micro-nano-scale holes of the same silicon wafermaxThe unit: nm). The average light reflectivity of the textured silicon wafer in the wave band of 400-1100 nm is detected by a textured reflectivity meter
(unit:%).
The electrical performance parameters of the battery piece are as follows: and testing by using a special testing instrument for the solar cell, such as a single flash simulator. Test conditions were Standard Test Conditions (STC): light intensity: 1000W/m 2; spectrum: 1.5 of AM; temperature: 25. the test method was carried out according to IEC 904-1. The main electrical property parameters of the battery piece are as follows: photoelectric conversion efficiency (Eta, unit:%), short-circuit current (Isc, unit: A), open-circuit voltage (Voc, unit: V), (fill factor (FF, unit:%), leakage current (IRev)2The unit: A) series resistance (Rs, unit: Ω), parallel resistance (Rsh, unit: Ω).
The characterization parameter test results of the textured silicon wafer are shown in table 1, and the electrical performance parameter test results of the battery piece are shown in table 2.
TABLE 1
TABLE 2
| Sample (I) | Eta | Isc | Voc | FF | IRev2 | Rs | Rsh |
| KK1 | 19.22 | 9.1431 | 0.6383 | 80.54 | 0.089 | 0.00139 | 369.634 |
| KK2 | 19.15 | 9.1359 | 0.6372 | 80.44 | 0.051 | 0.00146 | 273.829 |
| KK3 | 18.99 | 9.0638 | 0.6368 | 80.46 | 0.049 | 0.00141 | 163.820 |
| KK4 | 19.03 | 9.1317 | 0.6370 | 80.44 | 0.051 | 0.00146 | 273.829 |
| KK5 | 18.95 | 9.0612 | 0.6362 | 80.36 | 0.045 | 0.00157 | 167.845 |
| KK6 | 19.12 | 9.1327 | 0.6370 | 80.37 | 0.112 | 0.00146 | 363.891 |
| KK7 | 18.94 | 9.0732 | 0.6365 | 80.41 | 0.051 | 0.00146 | 478.769 |
| KK8 | 18.95 | 9.0655 | 0.6368 | 80.54 | 0.047 | 0.00132 | 235.464 |
| KK9 | 19.10 | 9.1335 | 0.6368 | 80.61 | 0.178 | 0.00130 | 345.875 |
| DKK1 | 18.93 | 9.0555 | 0.6371 | 80.20 | 0.057 | 0.00159 | 168.944 |
| DKK2 | 18.91 | 9.0636 | 0.6370 | 80.65 | 0.125 | 0.00138 | 136.434 |
| DKK3 | 18.64 | 8.9900 | 0.6319 | 80.64 | 0.297 | 0.00136 | 101.357 |
As can be seen from the test results in Table 1, the maximum difference Δ d1 between the widths of the openings on the top surfaces of the textured silicon wafers K1 and K9, the micro-nano-scale holes on the same silicon wafer, and the silicon wafers K1 and K9 of examples 1 to 9 are obtainedmaxMaximum difference Δ α between the vertical planes of the side and bottom surfacesmaxMaximum difference of hole depth Δ hmaxThe grain boundary of the surface of the textured silicon wafer is fuzzy and has no obvious chromatic aberration as shown in figure 4; the finished cell sheet had good appearance and no flowering as shown in fig. 7.
In comparative example 1, since no etching and hole digging additive was added to the silver deposition hole digging groove, the maximum difference Δ d of the top opening width of the textured silicon wafer was obtained1maxMaximum difference Δ α between the vertical planes of the side and bottom surfacesmaxMaximum difference of hole depth Δ hmaxAll are larger than the embodiment, which means that the size difference of the holes is larger on the same textured silicon wafer, as shown in fig. 5, which is expressed in appearance as follows: the grain boundary on the surface of the silicon wafer is relatively clear, and the chromatic aberration phenomenon exists; in addition, as shown in fig. 8, the finished battery piece also has a blooming phenomenon.
In comparative example 2, the main component of the etching and hole digging additive was benzotriazole, and the etching and hole digging additive was added during silver deposition and hole digging, and the obtained textured silicon wafer was similar to comparative example 1 in that the maximum difference Δ d of the top surface opening width was obtained1maxMaximum difference Δ α between the vertical planes of the side and bottom surfacesmaxMaximum difference of hole depth Δ hmaxThe sizes of the holes are larger than those of the silicon chips in the embodiments 1 to 9, which shows that the size difference of the holes is larger on the same textured silicon chip, the textured silicon chip shows that the grain boundary is relatively clear, the color difference phenomenon exists, and the appearance is similar to that of the silicon chip in FIG. 5; the obtained finished battery piece also has a blooming phenomenon, and the appearance of the finished battery piece is similar to that of the finished battery piece shown in figure 8.
The comparative example 3 is a polycrystalline silicon wafer cut by adopting mortar, the polycrystalline silicon suede is prepared on a Schmid or Rena chain machine by adopting a traditional mixed acid (mixed hydrofluoric acid and nitric acid) solution (namely, a one-time cleaning process), as shown in figure 3, the shimmer shape of the suede is groove-shaped, the size is in micron level, the maximum size difference of the grooves of the same silicon wafer is 1-3 microns, the opening of the groove is relatively large, the reflectivity of the suede is 23-26%, so that the reflectivity difference of each crystal direction is small, the crystal boundary is relatively fuzzy, the surface chromatic aberration of the whole silicon wafer is also small (figure 6), the prepared finished battery piece has good appearance, the phenomenon of blooming does not exist (figure 9), and the photoelectric conversion efficiency of the battery is relatively low.
As can be seen from the results in table 2, the cell KK 1-cell KK9 prepared in examples 1-9 have reduced average light reflectivity and light trapping effect due to the metal ion assisted texturing, and the short-circuit current and open-circuit voltage of the cell are greatly improved compared with those of the conventional mortar cell (comparative example 3), so that the photoelectric conversion efficiency of the cell is significantly improved.
The textured silicon wafers of comparative examples 1 and 2 had the maximum difference Δ d1 between the top opening widths of the surfacesmaxMaximum difference Δ α between the vertical planes of the side and bottom surfacesmaxMaximum difference of hole depth Δ hmaxAre all large, but have an average reflectivity
Also lower than the polycrystalline silicon piece flocking piece that the mortar was cut, certain light trapping effect also exists on cell piece surface, consequently, the photoelectric conversion efficiency of battery compares traditional cell piece, still has certain promotion.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (12)
1. The additive for making the diamond wire cut polycrystalline silicon wafer into the holes is characterized by comprising 0.01-0.20 wt% of polyethylene glycol, 0.01-0.10 wt% of corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the molecular weight of the polyethylene glycol is less than 1000, and the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine.
2. The additive for making herbs into wool and digging holes of claim 1, wherein the additive for making herbs into wool and digging holes comprises 0.01-0.10 wt% of polyethylene glycol 400, 0.01-0.10 wt% of polyethylene glycol 600, 0.01-0.10 wt% of corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine.
3. A wool making and hole digging additive according to claim 1 or 2, wherein said corrosion inhibitor is selected from mercaptobenzothiazole and/or hexadecylamine.
4. A texturing, silver-depositing and hole-digging liquid for diamond wire-cutting polycrystalline silicon wafers, which is characterized by comprising the texturing, hole-digging additive, silver-depositing agent and acid solution of the diamond wire-cutting polycrystalline silicon wafers according to any one of claims 1 to 3,
wherein, by volume ratio, the additive for making the wool and digging the holes: silver deposition agent: 0.1-0.5% of acid solution: 0.1-0.5: 100,
the silver precipitation agent contains silver nitrate, nitric acid, a dispersing agent and deionized water, and the acid solution contains hydrofluoric acid, a hydrogen peroxide aqueous solution and deionized water.
5. The wool making silver settling hole digging liquid according to claim 4, wherein the dispersing agent is one or more of polyvinylpyrrolidone, polyacrylamide, sodium dodecylbenzene sulfonate, fatty acid polyglycol ester and sodium carboxymethylcellulose;
preferably, the silver precipitating agent contains 0.1-1.0 wt% of silver nitrate, 0.1-1.0 wt% of nitric acid, 0.1-1.0 wt% of dispersing agent and 99.70-99.97 wt% of deionized water.
6. The preparation method of the texturing, silver precipitating and hole digging liquid for the diamond wire-cutting polycrystalline silicon wafer is characterized by comprising the steps of preparing a texturing and hole digging additive, a silver precipitating agent and an acid solution, wherein the texturing and hole digging additive, the silver precipitating agent and the acid solution are mixed according to the volume ratio of 0.1-0.5: 0.1-0.5: the step of mixing is carried out in a ratio of 100,
the additive for making the wool and digging the holes comprises 0.01-0.2 wt% of polyethylene glycol, 0.01-0.1 wt% of corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the molecular weight of the polyethylene glycol is less than 1000, and the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine; the silver precipitation agent contains silver nitrate, nitric acid, a dispersing agent and deionized water; the acid solution contains hydrofluoric acid, aqueous hydrogen peroxide and deionized water.
7. The preparation method according to claim 6, wherein the polyethylene glycol is selected from one or more of polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 800 and polyethylene glycol 1000;
preferably, the polyethylene glycol is selected from polyethylene glycol 400 and polyethylene glycol 600;
preferably, the additive for making herbs into wool and digging holes comprises 0.01-0.10 wt% of polyethylene glycol 400, 0.01-0.10 wt% of polyethylene glycol 600, 0.01-0.10 wt% of corrosion inhibitor and 99.70-99.97 wt% of deionized water, wherein the corrosion inhibitor is selected from one or more of mercaptobenzothiazole, tallow amine, hexadecylamine and octadecylamine;
preferably, the corrosion inhibitor is selected from mercaptobenzothiazole and/or hexadecylamine.
8. The preparation method of the silicon wafer comprises the steps of carrying out alkali primary polishing, first acid cleaning, silver deposition and hole digging, hole expanding, porous silicon removal, nano silver particle removal, second acid cleaning and slow pulling on a diamond wire cutting polycrystalline silicon wafer, and is characterized in that the silver deposition and hole digging step comprises the following steps: carrying out first contact on the diamond wire-cut polycrystalline silicon wafer after the first acid cleaning and the texturing and silver-depositing hole digging solution of the diamond wire-cut polycrystalline silicon wafer according to claim 4 or 5.
9. The method of claim 8, wherein the immersion silver boring conditions comprise: the contact temperature is 20-50 ℃, and the contact time is 120-300 s;
preferably, the silver sinking and hole digging step further comprises a third cleaning step of using deionized water to carry out a third cleaning on the diamond wire-cutting polycrystalline silicon wafer after the silver sinking and hole digging step;
preferably, the third cleaning is washing with deionized water for 120-240 s;
preferably, after the silver depositing and hole digging step, the average reflectivity of the obtained diamond wire-cutting polycrystalline silicon wafer is 1.0-4.0%.
10. A silicon wafer, characterized in that it is produced by the method of any one of claims 8 to 9.
11. The silicon wafer according to claim 10, wherein the concentration of metal atoms or ions remaining on the surface of the silicon wafer is 50ppb or less;
preferably, the surface of the silicon wafer is formed with a truncated cone-shaped micro-nano-scale hole having an opening width, an inclination and a depth, and a maximum difference Δ d of the opening width of the top surface of the micro-nano-scale hole1max200-300 nm, and the included angle between the side surface and the vertical surface of the bottom surface is the largestLarge difference Δ αmaxIs 10-20 degrees, and the maximum difference value delta h of the hole depthsmax100 to 200 nm;
preferably, the average light reflectivity of the silicon wafer is within a wave band of 400-1100 nm
18 to 22 percent.
12. A solar cell prepared using the silicon wafer according to claim 10 or 11.
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