CN111524985A - Method for texturing surface of polycrystalline silicon wafer - Google Patents
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- 229910021420 polycrystalline silicon Inorganic materials 0.000 title claims abstract description 112
- 238000000034 method Methods 0.000 title claims abstract description 39
- 239000008151 electrolyte solution Substances 0.000 claims abstract description 11
- 239000012670 alkaline solution Substances 0.000 claims abstract description 10
- 238000005530 etching Methods 0.000 claims description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 31
- 238000005406 washing Methods 0.000 claims description 30
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 24
- 238000004140 cleaning Methods 0.000 claims description 23
- 238000001035 drying Methods 0.000 claims description 18
- 229910001868 water Inorganic materials 0.000 claims description 17
- 239000002253 acid Substances 0.000 claims description 14
- 239000007864 aqueous solution Substances 0.000 claims description 10
- 229910017604 nitric acid Inorganic materials 0.000 claims description 10
- 239000000243 solution Substances 0.000 claims description 10
- 239000012459 cleaning agent Substances 0.000 claims description 7
- 239000011259 mixed solution Substances 0.000 claims description 5
- 238000007602 hot air drying Methods 0.000 claims description 3
- 238000005554 pickling Methods 0.000 claims description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 claims description 2
- 235000012431 wafers Nutrition 0.000 abstract description 81
- 238000005260 corrosion Methods 0.000 abstract description 18
- 230000007797 corrosion Effects 0.000 abstract description 17
- 238000006056 electrooxidation reaction Methods 0.000 abstract description 11
- 229910021426 porous silicon Inorganic materials 0.000 abstract description 6
- 238000002310 reflectometry Methods 0.000 abstract description 6
- 238000001228 spectrum Methods 0.000 abstract description 5
- 239000008367 deionised water Substances 0.000 description 14
- 229910021641 deionized water Inorganic materials 0.000 description 14
- 230000000694 effects Effects 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 7
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 6
- 229910052802 copper Inorganic materials 0.000 description 6
- 239000010949 copper Substances 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 239000010703 silicon Substances 0.000 description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 5
- 229910003460 diamond Inorganic materials 0.000 description 5
- 239000010432 diamond Substances 0.000 description 5
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 210000002268 wool Anatomy 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000001020 plasma etching Methods 0.000 description 3
- 229920005591 polysilicon Polymers 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 238000003486 chemical etching Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 229910021419 crystalline silicon Inorganic materials 0.000 description 2
- 238000005034 decoration Methods 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 239000002923 metal particle Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 239000004570 mortar (masonry) Substances 0.000 description 2
- 238000012805 post-processing Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000007847 structural defect Effects 0.000 description 2
- 235000009421 Myristica fragrans Nutrition 0.000 description 1
- 229910021418 black silicon Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 125000005843 halogen group Chemical group 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000001115 mace Substances 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
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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
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- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
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- H01L31/02—Details
- H01L31/0236—Special surface textures
- H01L31/02363—Special surface textures of the semiconductor body itself, e.g. textured active layers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
- H01L31/182—Special manufacturing methods for polycrystalline Si, e.g. Si ribbon, poly Si ingots, thin films of polycrystalline Si
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/546—Polycrystalline silicon PV cells
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- 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
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Abstract
The invention provides a method for texturing the surface of a polycrystalline silicon wafer, and belongs to the technical field of texturing of polycrystalline silicon wafers. The method takes a polycrystalline silicon wafer as an anode and an alkaline solution as an electrolyte solution to carry out electrochemical corrosion texturing on the surface of the polycrystalline silicon wafer. According to the invention, by electrochemically corroding the surface of the polycrystalline silicon wafer, a hundred-nanometer-level porous silicon corrosion suede surface which is uniformly distributed can be prepared on the surface of the polycrystalline silicon wafer, so that the reflectivity of the surface of the polycrystalline silicon wafer is greatly reduced. Meanwhile, the method of the invention has simple operation and lower cost. The embodiment result shows that the weighted average surface reflectivity of the polycrystalline silicon wafer obtained by the method for texturing the surface of the polycrystalline silicon wafer in the range of 400nm to 1100nm relative to the AM1.5G solar spectrum can reach 17.5-18.5%.
Description
Technical Field
The invention relates to the technical field of polycrystalline silicon wafer texturing, in particular to a method for texturing the surface of a polycrystalline silicon wafer.
Background
As an important form of reducing the cost of crystalline silicon solar cells, polycrystalline silicon solar cells have a relatively large market share in the photovoltaic market. The preparation of the suede on the surface of the silicon wafer to reduce the light reflectivity is an important means for improving the conversion efficiency of the crystalline silicon solar cell. On the polysilicon chip, a viaHNO is often used3/HF/H2The O system is used for preparing the suede, and the acid system can generate isotropic corrosion on the silicon wafer, so that a random 'corrosion pit' structure with a micron scale is obtained on the surface of the polycrystalline silicon wafer. For the polycrystalline silicon slice obtained by cutting the mortar, a thicker damage layer exists on the surface of the polycrystalline silicon slice, the damage layer can bring structural defects of the polycrystalline silicon slice, the position with the structural defects can be used as a reaction starting point of acid texturing, and the reflectivity of the obtained 'corrosion pit' texturing is relatively low.
However, in recent years, the mortar slicing technology is gradually replaced by more advanced diamond wire slicing technology, the surface damage layer of the diamond wire-cut polycrystalline silicon wafer is shallow, and HNO3/HF/H2The O system has few reaction starting points for texturing, and the suede effect can not meet the requirements of the industry any more. As such, some black silicon texturing techniques have been created for diamond wire cut polycrystalline silicon wafers. Representative of these techniques are dry Reactive Ion Etching (RIE) and wet metal-catalyzed chemical Etching (MCCE or MACE). RIE prepares the textured surface by chemical etching of halogen atoms on a silicon wafer and physical bombardment of high-energy ions on the silicon wafer in plasma, but the technology needs vacuum equipment, and has high preparation cost and complex process. The MCCE technique uses noble metal particles of Cu, Ag, Pt, Au, etc. as catalysts to etch the surface of a silicon wafer in HF/oxidant solution, generally obtaining nano-scale porous silicon. The technology has the defects that metal particles are easy to be left on the silicon chip to pollute, the process control difficulty is high, and the cost is high.
Disclosure of Invention
In view of the above, the present invention provides a method for texturing a surface of a polysilicon wafer. The method provided by the invention is simple to operate, low in cost and suitable for the polycrystalline silicon wafer prepared by the diamond wire slicing method, and the obtained etched texture has a good antireflection effect.
In order to achieve the purpose of the invention, the invention provides the following technical scheme:
the invention provides a method for texturing the surface of a polycrystalline silicon wafer, which comprises the following steps:
and (3) electrochemically corroding and texturing the surface of the polycrystalline silicon wafer by taking the polycrystalline silicon wafer as an anode and an alkaline solution as an electrolyte solution.
Preferably, the alkaline solution is an aqueous solution of NaOH and/or KOH, and the molar concentration of solute in the alkaline solution is 0.1-5.0 mol/L.
Preferably, the current for electrochemical corrosion texturing is 10-50 mA/cm2The time is 20-60 min.
Preferably, before the electrochemical etching texturing, the method further comprises pre-etching the polycrystalline silicon wafer, wherein the pre-etching solution for pre-etching is HNO3HF and H2Mixed solution of O, HNO in the pre-etching solution3The molar concentration of the hydrogen fluoride is 7-10 mol/L, and the molar concentration of the HF is 2-7 mol/L.
Preferably, the pre-etching time is 1-3 min.
Preferably, the method further comprises post-processing the electrochemically etched polycrystalline silicon wafer after the electrochemical etching texturing, wherein the post-processing comprises the following steps:
and cleaning and drying the electrochemically corroded polycrystalline silicon wafer in sequence.
Preferably, the cleaning is water washing, or acid washing and water washing which are sequentially carried out, or water washing, acid washing and water washing which are sequentially carried out;
the cleaning agent for acid cleaning is HF, HCl and H2And (3) a mixed solution of O.
Preferably, the molar concentration of HCl in the cleaning agent for acid washing is 1.0-1.4 mol/L, and the molar concentration of HF is 1.2-1.6 mol/L; the pickling time is independently 2-5 min.
Preferably, the drying is hot air drying; the temperature for drying the hot air is 50-70 ℃.
The invention provides a method for texturing the surface of a polycrystalline silicon wafer. In the electrochemical corrosion process, the surface of the polycrystalline silicon chip is subjected to anodic oxidation reaction to generate a porous silicon corrosion suede with the size of hundreds of nanometers, so that the reflectivity of the surface of the polycrystalline silicon chip is greatly reduced. Meanwhile, the method of the invention has simple and convenient operation, lower cost and safety. The embodiment result shows that the method for texturing the surface of the polycrystalline silicon wafer can enable the weighted average surface reflectivity of the polycrystalline silicon wafer relative to the AM1.5G solar spectrum within the range of 400nm to 1100nm to reach 17.5-18.5%.
Drawings
FIG. 1 is an SEM photograph of a textured surface of a polycrystalline silicon wafer after texturing in example 1;
FIG. 2 is a graph of surface reflectance of textured polycrystalline silicon wafers of example 1 and comparative example 1;
FIG. 3 is an SEM photograph of the textured surface of the polycrystalline silicon wafer after texturing in example 5;
FIG. 4 is a graph showing the surface reflectance of the textured polycrystalline silicon wafers obtained in example 5 and comparative example 1.
Detailed Description
The invention provides a method for texturing the surface of a polycrystalline silicon wafer, which comprises the following steps:
and (3) electrochemically corroding and texturing the surface of the polycrystalline silicon wafer by taking the polycrystalline silicon wafer as an anode and an alkaline solution as an electrolyte solution.
In the invention, the polycrystalline silicon wafer is preferably a polycrystalline silicon wafer prepared by a diamond wire slicing method.
The invention does not require any particular kind of cathode, and it is sufficient to use a conductive electrode which does not react with alkali, as is well known to those skilled in the art.
In the present invention, the alkaline solution is preferably an aqueous solution of NaOH and/or KOH; the molar concentration of the solute in the alkaline solution is preferably 0.1-5.0 mol/L, and more preferably 2-4 mol/L. The current of the electrochemical corrosion texturing is preferably 10-50 mA/cm2More preferably 20 to 40mA/cm2(ii) a The time for the electrochemical corrosion texturing is preferably 20-60 min, and more preferably 30-50 min.
According to the invention, the surface of the polycrystalline silicon wafer is subjected to electrochemical corrosion texturing, so that a porous silicon corrosion textured surface with the size of hundreds of nanometers can be prepared on the surface of the polycrystalline silicon wafer, and the reflectivity of the surface of the polycrystalline silicon wafer is greatly reduced.
In the invention, before the electrochemical etching texturing, pre-etching is preferably performed on the polycrystalline silicon wafer; the pre-etching solution for pre-etching is preferably HNO3HF and H2Mixed solution of O, HNO in the pre-etching solution3The molar concentration of the (b) is preferably 7-10 mol/L, and more preferably 8-9 mol/L; the molar concentration of the HF is preferably 2-7 mol/L, and more preferably 4-6 mol/L; the pre-etching time is preferably 1-3 min. The invention carries out HNO on the polycrystalline silicon chip3/HF/H2And O pre-corrosion can remove a damage layer on the surface of the polycrystalline silicon wafer, can prepare micron-sized randomly-distributed corrosion pits on the surface of the polycrystalline silicon wafer, and can form a micro-nano-sized composite suede structure through subsequent alkali solution electrochemical corrosion, so that the antireflection effect is better.
After the pre-etching, the pre-etched polycrystalline silicon wafer obtained after the pre-etching is preferably cleaned. In the present invention, the cleaning agent is preferably deionized water. The present invention does not require any particular manner of cleaning, and may be performed using cleaning methods known to those skilled in the art.
In the invention, after the electrochemical etching texturing, the method further comprises the step of carrying out post-treatment on the electrochemically etched polycrystalline silicon wafer, wherein the post-treatment comprises the following steps:
and cleaning and drying the polycrystalline silicon wafer subjected to electrochemical corrosion in sequence to obtain the dried polycrystalline silicon wafer with the textured surface.
In the present invention, the washing is preferably water washing, or acid washing and water washing performed in this order, or water washing, acid washing and water washing performed in this order. In the invention, the time for washing is preferably 10-15 min independently, and more preferably 12-14 min independently; the cleaning agent for acid cleaning is preferably HF, HCl and H2O, wherein the molar concentration of HCl in the cleaning agent for acid washing is preferably 1.0-1.4 mol/L, and more preferably 1.2 mol/L; the molar concentration of the HF is preferably 1.2-1.6 mol/L, and more preferably 1.3-1.5 mol/L; the pickling time is preferably 2-5 min, and more preferably 3-4 min.
In the invention, the drying is preferably hot air drying; the temperature for drying by hot air is preferably 50-70 ℃, and more preferably 60 ℃; the invention has no special requirement on the drying time, and can completely remove the moisture on the surface of the polycrystalline silicon wafer.
The method for texturing the surface of a polycrystalline silicon wafer according to the present invention will be described in detail with reference to the following examples, which should not be construed as limiting the scope of the present invention.
Example 1
(1) Adopting 0.3mol/L NaOH aqueous solution as electrolyte solution, polycrystalline silicon slice as anode and copper electrode as cathode, electrochemically corroding the polycrystalline silicon slice to make wool, the corrosion current is 28mA/cm2Etching time is 30 min;
(2) and cleaning the polycrystalline silicon wafer subjected to electrochemical corrosion with deionized water for 15min, and drying with hot air at 50 ℃ to obtain the polycrystalline silicon wafer with the textured surface.
The SEM photograph of the surface texture obtained on the polysilicon sheet by the method of this example is shown in fig. 1, and it can be seen from fig. 1 that the obtained texture is composed of porous silicon uniformly distributed at 100nm to 200 nm.
Comparative example 1
(1) Carrying out conventional HNO on polycrystalline silicon wafer3/HF/H2Corrosion by O, HNO in corrosive liquid3The dosage of the catalyst is 8mol/L, the dosage of the HF is 6mol/L, and the corrosion time is 2 min;
(2) for HNO3/HF/H2And cleaning the polycrystalline silicon wafer subjected to O corrosion by using deionized water for 15min, and drying by using hot air at 50 ℃ to obtain the polycrystalline silicon wafer with the textured surface.
Test example 1
The surface-textured polycrystalline silicon wafers obtained in example 1 and comparative example 1 were subjected to reflectance tests at wavelengths of 400nm to 1100nm, respectively, using an QEX7 tester by pvmeasurements, and the obtained surface reflectance maps were shown in fig. 2.
As can be seen from fig. 2, the surface-textured polycrystalline silicon wafer obtained in example 1 exhibited a very good antireflection effect in the wavelength range of 400nm to 1100nm, and the weighted average surface reflectance with respect to the am1.5g solar spectrum was 18.5%; whereas comparative example 1 obtained a pile with a weighted average surface reflectance of up to 24.8% in the same range.
Example 2
(1) Using 5.0mol/L KOH aqueous solution as electrolyte solution, polycrystalline silicon slice as anode and copper electrode as cathode, electrochemically etching the polycrystalline silicon slice to make texture with the etching current of 50mA/cm2Etching time is 20 min;
(2) and (3) washing the electrochemically corroded polycrystalline silicon wafer with deionized water for 15min and drying the polycrystalline silicon wafer with hot air at 60 ℃.
The SEM photograph of the textured surface on the surface of the polycrystalline silicon wafer obtained in this embodiment is similar to that shown in fig. 1, and can obtain a similar antireflection effect.
Example 3
(1) Adopting 0.1mol/L NaOH aqueous solution as electrolyte solution, polycrystalline silicon slice as anode and copper electrode as cathode, electrochemically corroding the polycrystalline silicon slice to make wool, the corrosion current is 10mA/cm2Etching time is 60 min;
(2) adopting HF/HCl/H to the polycrystalline silicon slice after electrochemical corrosion2Cleaning with O mixed liquor, wherein the molar concentration of HCl in the mixed liquor is 1.0mol/L, the molar concentration of HF in the mixed liquor is 1.6mol/L, and the cleaning time is 3 min;
(3) for HF/HCl/H2And cleaning the polycrystalline silicon wafer cleaned by the O solution with deionized water for 15min and drying the polycrystalline silicon wafer by using hot air at 70 ℃.
The SEM photograph of the textured surface on the surface of the polycrystalline silicon wafer obtained in this embodiment is similar to that shown in fig. 1, and can obtain a similar antireflection effect.
Example 4
(1) Adopting 3mol/L NaOH aqueous solution as electrolyte solution, polycrystalline silicon slice as anode and graphite electrode as cathode, electrochemically corroding the polycrystalline silicon slice to make wool, wherein the corrosion current is 30mA/cm2Etching time is 40 min;
(2) cleaning the electrochemically corroded polycrystalline silicon wafer for 10min by using deionized water;
(3) the polycrystalline silicon chip cleaned by deionized water adopts HF/HCl/H2Cleaning with O mixed solutionThe molar concentration of HCl in the solution is 1.2mol/L, the molar concentration of HF is 1.4mol/L, and the cleaning time is 5 min;
(4) and washing the pickled polycrystalline silicon wafer for 15min by using deionized water, and drying by using hot air at 60 ℃.
The SEM photograph of the textured surface on the surface of the polycrystalline silicon wafer obtained in this embodiment is similar to that shown in fig. 1, and can obtain a similar antireflection effect.
Example 5
(1) HNO is carried out on the polycrystalline silicon slice3/HF/H2O Pre-etching, HNO3The dosage of the catalyst is 8mol/L, the dosage of the HF is 6mol/L, and the corrosion time is 2 min;
(2) adopting 0.3mol/L NaOH aqueous solution as electrolyte solution, polycrystalline silicon slice as anode and copper electrode as cathode, electrochemically corroding the pre-corroded polycrystalline silicon slice with corrosion current of 28mA/cm to make wool2Etching time is 30 min;
(3) and (3) washing the electrochemically corroded polycrystalline silicon wafer with deionized water for 15min and drying the polycrystalline silicon wafer with hot air at 60 ℃.
An SEM photograph of the surface texture obtained on the polycrystalline silicon wafer by the method of the present embodiment is shown in fig. 3, and it can be seen from fig. 3 that the obtained texture has a composite antireflection structure composed of porous silicon etch pits uniformly distributed at 100nm to 200nm and micron-scale etch pits.
Test example 2
The surface-textured polycrystalline silicon wafers obtained in example 5 and comparative example 1 were subjected to reflectance tests at wavelengths of 400nm to 1100nm, respectively, using an QEX7 tester by pvmeasurements, and the resulting surface reflectance maps were shown in fig. 4.
As can be seen from fig. 4, the surface-textured polycrystalline silicon wafer obtained in example 5 exhibited a very good antireflection effect in the wavelength range of 400nm to 1100nm, and the weighted average surface reflectance with respect to the am1.5g solar spectrum was 17.5%; whereas comparative example 1 obtained a pile with a weighted average surface reflectance of up to 24.8% in the same range.
Example 6
(1) HNO is carried out on the polycrystalline silicon slice3/HF/H2O Pre-etching, HNO3By usingThe amount is 10mol/L, the dosage of HF is 3mol/L, and the corrosion time is 1 min;
(2) using 0.1mol/L KOH aqueous solution as electrolyte solution, polycrystalline silicon wafer as anode, copper electrode as cathode, and HNO3/HF/H2Electrochemically etching and texturing the O pre-etched polycrystalline silicon wafer with the etching current of 20mA/cm2Etching time is 50 min;
(3) adopting HF/HCl/H to the polycrystalline silicon slice after electrochemical corrosion2Cleaning with O mixed liquor, wherein the molar concentration of HCl in the mixed liquor is 1.4mol/L, the molar concentration of HF in the mixed liquor is 1.2mol/L, and the cleaning time is 2 min;
(4) and washing the pickled polycrystalline silicon wafer for 10min by using deionized water, and drying by using hot air at 50 ℃.
The SEM photograph of the textured surface on the surface of the polycrystalline silicon wafer obtained in this embodiment is similar to that shown in fig. 3, and can obtain a similar antireflection effect.
Example 7
(1) HNO is carried out on the polycrystalline silicon slice3/HF/H2O Pre-etching, HNO3The dosage of the catalyst is 7mol/L, the dosage of HF is 2mol/L, and the corrosion time is 1.5 min;
(2) cleaning the pre-etched polycrystalline silicon wafer for 10min by using deionized water;
(3) adopting 3mol/L NaOH aqueous solution as electrolyte solution, polycrystalline silicon slice as anode and graphite as cathode, electrochemically etching the pre-etched polycrystalline silicon slice after washing with water to prepare texture with the etching current of 30mA/cm2Etching time is 40 min;
(4) cleaning the electrochemically corroded polycrystalline silicon wafer for 15min by using deionized water;
(5) the polycrystalline silicon chip cleaned by deionized water adopts HF/HCl/H2Cleaning with O mixed liquor, wherein the molar concentration of HCl in the mixed liquor is 1.2mol/L, the molar concentration of HF in the mixed liquor is 1.4mol/L, and the cleaning time is 3 min;
(6) and washing the pickled polycrystalline silicon wafer for 15min by using deionized water, and drying by using hot air at 70 ℃.
The SEM photograph of the textured surface on the surface of the polycrystalline silicon wafer obtained in this embodiment is similar to that shown in fig. 3, and can obtain a similar antireflection effect.
From the above embodiments, the texture morphology obtained on the polycrystalline silicon wafer by the method of the present invention has a very good antireflection effect, and the weighted average surface reflectance in the range of 400nm to 1100nm relative to the am1.5g solar spectrum is much lower than that of the conventional HNO3/HF/H2O-texturing results in a weighted average surface reflectance of the textured surface in the same range. Meanwhile, the method of the invention has simple and convenient operation, lower cost and safety.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (9)
1. A method for texturing the surface of a polycrystalline silicon wafer is characterized by comprising the following steps:
and (3) electrochemically corroding and texturing the surface of the polycrystalline silicon wafer by taking the polycrystalline silicon wafer as an anode and an alkaline solution as an electrolyte solution.
2. The method according to claim 1, wherein the alkaline solution is an aqueous solution of NaOH and/or KOH, and the molar concentration of the solute in the alkaline solution is 0.1-5.0 mol/L.
3. The method according to claim 1, wherein the electrochemical etching texturing current is 10-50 mA/cm2The time is 20-60 min.
4. The method according to claim 1, further comprising pre-etching the polycrystalline silicon wafer before the electrochemical etching texturing, wherein the pre-etching solution for pre-etching is HNO3HF and H2Mixed solution of O, HNO in the pre-etching solution3The molar concentration of the hydrogen fluoride is 7-10 mol/L, and the molar concentration of the HF is 2-7 mol/L.
5. The method according to claim 4, wherein the pre-etching time is 1-3 min.
6. The method of claim 1, wherein said electrochemically etching texturing further comprises post-treating the electrochemically etched polycrystalline silicon wafer, said post-treating comprising the steps of:
and cleaning and drying the electrochemically corroded polycrystalline silicon wafer in sequence.
7. The method according to claim 6, wherein the washing is water washing, or acid washing and water washing performed in sequence, or water washing, acid washing and water washing performed in sequence;
the cleaning agent for acid cleaning is HF, HCl and H2And (3) a mixed solution of O.
8. The method according to claim 7, wherein the molar concentration of HCl in the cleaning agent for acid washing is 1.0 to 1.4mol/L, and the molar concentration of HF is 1.2 to 1.6 mol/L; the pickling time is independently 2-5 min.
9. The method of claim 6, wherein the drying is hot air drying; the temperature for drying the hot air is 50-70 ℃.
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| CN102113123A (en) * | 2008-03-14 | 2011-06-29 | 诺鲁纳为股份有限公司 | Method for texturing silicon surfaces and wafers thereof |
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