CN110707001A - Method for texturing silicon wafer by repeatedly utilizing black silicon cleaning solution - Google Patents
Method for texturing silicon wafer by repeatedly utilizing black silicon cleaning solution Download PDFInfo
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- 229910021418 black silicon Inorganic materials 0.000 title claims abstract description 243
- 238000004140 cleaning Methods 0.000 title claims abstract description 142
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 111
- 239000010703 silicon Substances 0.000 title claims abstract description 111
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 110
- 238000000034 method Methods 0.000 title claims abstract description 51
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims abstract description 50
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 39
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 39
- 239000008367 deionised water Substances 0.000 claims abstract description 30
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 30
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 30
- 239000002923 metal particle Substances 0.000 claims abstract description 20
- 229910021645 metal ion Inorganic materials 0.000 claims abstract description 19
- 238000001035 drying Methods 0.000 claims abstract description 16
- 239000002994 raw material Substances 0.000 claims abstract description 11
- 150000003839 salts Chemical class 0.000 claims abstract description 11
- 238000004064 recycling Methods 0.000 claims abstract description 9
- 210000002268 wool Anatomy 0.000 claims abstract description 7
- 235000012431 wafers Nutrition 0.000 claims description 115
- 239000007788 liquid Substances 0.000 claims description 42
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 claims description 42
- 229910001961 silver nitrate Inorganic materials 0.000 claims description 21
- 229910003460 diamond Inorganic materials 0.000 claims description 19
- 239000010432 diamond Substances 0.000 claims description 19
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims description 19
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 claims description 16
- 238000005406 washing Methods 0.000 claims description 12
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims description 5
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical class [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims description 2
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical group [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 claims description 2
- 238000004065 wastewater treatment Methods 0.000 abstract description 5
- 239000012530 fluid Substances 0.000 abstract description 2
- 238000007664 blowing Methods 0.000 abstract 1
- 230000002378 acidificating effect Effects 0.000 description 34
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 22
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 14
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 9
- 239000007800 oxidant agent Substances 0.000 description 9
- 230000001590 oxidative effect Effects 0.000 description 9
- 238000001878 scanning electron micrograph Methods 0.000 description 8
- 229910052757 nitrogen Inorganic materials 0.000 description 7
- 230000000694 effects Effects 0.000 description 5
- 239000002699 waste material Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000005520 cutting process Methods 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000000861 blow drying Methods 0.000 description 1
- 229910021419 crystalline silicon Inorganic materials 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 150000003376 silicon Chemical class 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
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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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02041—Cleaning
- H01L21/02057—Cleaning during device manufacture
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/30604—Chemical etching
- H01L21/30608—Anisotropic liquid etching
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- 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
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention discloses a method for texturing a silicon wafer by repeatedly utilizing black silicon cleaning fluid, which comprises the following steps: (1) immersing a silicon wafer into a wool making solution containing 0.01-200mmol/L of metal ion salt, 1-10mol/L of hydrofluoric acid and 0.1-10mol/L of black silicon for wool making; (2) cleaning the silicon wafer subjected to texturing by using deionized water, and drying; (3) cleaning the dried silicon wafer obtained in the step (2) by using a 20-80 wt% nitric acid solution to remove metal particles deposited on the surface of the silicon wafer; (4) cleaning the silicon wafer cleaned by the black silicon cleaning solution by using deionized water, and drying the silicon wafer by blowing to obtain the silicon wafer with the textured structure; and (5) repeating the steps (1) to (4) until the black silicon cleaning solution reaches the service life, and preparing the black silicon texturing solution by using the black silicon cleaning solution reaching the service life as a raw material. The method can simply and effectively realize the recycling of the black silicon cleaning solution, particularly the metal ions in the black silicon cleaning solution, reduces the wool making cost and the wastewater treatment cost, and is environment-friendly.
Description
Technical Field
The invention relates to the field of semiconductors, in particular to a method for texturing a silicon wafer by repeatedly utilizing black silicon cleaning liquid.
Background
The solar energy has the characteristics of large reserve, wide distribution and the like, and has important significance for improving the existing energy structure. Solar power generation mainly utilizes a solar cell to realize conversion from solar energy to electric energy. Among them, the silicon-based solar cell is currently the most widely used solar cell. The silicon-based solar cell mainly includes a single crystalline silicon solar cell and a polycrystalline silicon solar cell.
At present, for single crystal silicon solar cells and polycrystalline silicon solar cells, the diamond wire slicing technology can significantly reduce the slicing cost of silicon ingots, and further finally reduce the cost of photovoltaic modules. However, the acid texturing effect of the polycrystalline silicon wafer cut by the diamond wire is poor, so that the diamond wire slicing technology cannot be comprehensively applied to the field of polycrystalline silicon solar cells.
The black silicon technology mainly realizes good light absorption in a wider waveband range by forming a specific textured structure on the surface of a silicon wafer. The black silicon technology can be mainly divided into a dry black silicon technology and a wet black silicon technology, wherein the wet black silicon technology mainly utilizes a metal catalytic etching method to form a specific textured structure on the surface of a silicon wafer. The problem of texturing of the diamond wire-cut polycrystalline silicon wafer can be solved by adopting a metal catalytic etching method in a wet black silicon technology, and the black silicon texturing technology becomes a research and development hotspot of the existing polycrystalline silicon solar cell.
In the process of texturing by using a metal catalytic etching method, firstly, black silicon texturing liquid is used for processing a silicon wafer, a certain amount of metal particles are deposited on the surface of the silicon wafer, and then black silicon cleaning liquid is used for dissolving the metal particles deposited on the surface of the silicon wafer to remove the metal particles, so that a corresponding texturing sheet is obtained. Hydrogen peroxide is often adopted as an oxidant in the conventional black silicon texturing solution, and nitric acid is usually adopted as a black silicon cleaning solution. The waste black silicon cleaning liquid reaching the service life is usually used as a waste acid liquid for recovery treatment, and the adsorption and deposition in the waste water treatment process are mainly adopted to collect metal ions in the waste black silicon cleaning liquid. However, to recycle these metal ions, an additional metal recycling system is usually required, which requires high cost.
Disclosure of Invention
Therefore, the invention aims to provide a method for texturing a silicon wafer by recycling black silicon cleaning solution, which can simply and effectively realize the recycling of the black silicon cleaning solution, particularly metal ions in the black silicon cleaning solution, in the production process of a black silicon solar cell, reduces the texturing cost and the wastewater treatment cost of the black silicon solar cell, and is green and environment-friendly.
The purpose of the invention is realized by the following technical scheme.
The inventor finds that by selecting the components and the contents of the black silicon texturing solution and the black silicon cleaning solution, for example, nitric acid is adopted as an oxidant in the black silicon texturing solution, not only can the corresponding texturing and cleaning functions be realized, but also the black silicon texturing solution can be prepared by utilizing the waste black silicon cleaning solution reaching the service life, so that the recycling of the black silicon cleaning solution, particularly metal ions in the black silicon cleaning solution is realized, the black silicon cleaning solution reaching the service life does not need to be treated as the waste acid solution, the texturing cost and the wastewater treatment cost of the silicon wafer are reduced, and the method is green and environment-friendly.
The invention provides a method for texturing a silicon wafer by repeatedly utilizing black silicon cleaning fluid, which comprises the following steps:
(1) immersing a silicon wafer into black silicon texturing liquid for texturing; wherein the black silicon texturing solution contains 0.01-200mmol/L of metal ion salt, 1-10mol/L of hydrofluoric acid and 0.1-10mol/L of nitric acid;
(2) washing the silicon wafer subjected to texturing prepared in the step (1) by using deionized water, and drying;
(3) cleaning the dried silicon wafer obtained in the step (2) by using a black silicon cleaning solution to remove metal particles deposited on the surface of the silicon wafer; wherein the black silicon cleaning solution is a nitric acid solution with the concentration of 20-80 wt%;
(4) washing the silicon wafer washed by the black silicon washing liquid obtained in the step (3) with deionized water, and drying to obtain a silicon wafer with a textured structure; and
(5) and (3) repeating the steps (1) to (4) until the black silicon cleaning solution reaches the service life, and preparing the black silicon texturing solution in the step (1) by taking the black silicon cleaning solution reaching the service life as a raw material.
The method provided by the invention has no special requirement on the type of the silicon wafer. In some embodiments, examples of suitable silicon wafers include, but are not limited to: the silicon chip comprises a P-type diamond wire-cutting polycrystalline silicon chip, a P-type diamond wire-cutting monocrystalline silicon chip, an N-type diamond wire-cutting monocrystalline silicon chip and a P-type mortar-cutting polycrystalline silicon chip. In some embodiments, the silicon wafer is a P-type diamond wire-cut polycrystalline silicon wafer.
According to the method provided by the invention, the black silicon texturing solution contains one or two metal ion salts.
The method provided according to the present invention, wherein examples of the metal ion salt include, but are not limited to: silver ion salts such as silver nitrate and copper ion salts such as copper nitrate.
In some preferred embodiments, the black silicon texturing solution comprises 0.1-0.5mmol/L silver nitrate and 0-50mmol/L copper nitrate.
According to the method provided by the invention, the concentration of hydrofluoric acid in the black silicon texturing solution is 3-4.5 mol/L; the concentration of nitric acid is 2-6mol/L, for example 4 mol/L.
The method provided by the invention is characterized in that the temperature for making the wool in the step (1) is 8-80 ℃, preferably 25-30 ℃; the time is 30 seconds to 10 minutes, preferably 3 to 5 minutes.
According to the method provided by the invention, the concentration of nitric acid in the black silicon cleaning solution is 20-69 wt%.
According to the method provided by the invention, the temperature for cleaning by using the black silicon cleaning solution in the step (3) is 10-60 ℃, preferably 25-40 ℃; the time is 30 seconds to 10 minutes, preferably 3 to 5 minutes.
According to the method provided by the invention, the service life of the black silicon texturing solution is 1000-200000 silicon wafers, and the service life of the black silicon cleaning solution is 1000-200000 silicon wafers. In some embodiments, the service lives of the black silicon texturing solution and the black silicon cleaning solution may be the same or different, and in some embodiments, the service lives of the black silicon texturing solution and the black silicon cleaning solution are 100000-120000 silicon wafers.
According to the method provided by the invention, in the process of repeating the texturing and the cleaning by using the black silicon cleaning solution, the loss of the black silicon texturing solution and the black silicon cleaning solution is generally caused, so that the black silicon texturing solution and the black silicon cleaning solution (or their corresponding components) can be appropriately supplemented to keep the volume thereof within a predetermined range and the composition thereof within the range so as to prolong the service life thereof. In some embodiments, every 200-1000 wafers processed, such as 200-400 wafers, are replenished.
In the invention, the service lives of the black silicon texturing solution and the black silicon cleaning solution are counted by the number of 156 mm-156 mm silicon wafers, such as P-type diamond wire-cut polycrystalline silicon wafers, which can be processed by the black silicon texturing solution and the black silicon cleaning solution. The service life of the black silicon texturing solution and the black silicon cleaning solution is determined by the composition and the volume of the black silicon texturing solution and the black silicon cleaning solution in principle.
According to the method provided by the invention, the gas used for blow-drying in the step (2) and the step (4) is high-purity nitrogen.
According to the method provided by the invention, when the black silicon wool making liquid in the step (1) is prepared by taking the black silicon cleaning liquid reaching the service life as a raw material in the step (5), the using amount of the black silicon cleaning liquid reaching the service life is 1-100% of the volume of the black silicon wool making liquid, and is preferably 15-70%.
In the invention, the cleaning solution remained in the preparation of the black silicon texturing solution can be stored in a corresponding container to be used in the next preparation of the black silicon texturing solution.
According to the method provided by the invention, when the black silicon texturing solution in the step (1) is prepared by taking the black silicon cleaning solution reaching the service life as a raw material in the step (5), metal ion salt, hydrofluoric acid, nitric acid and/or deionized water are added according to needs.
According to the method provided by the invention, the deionized water washed in the step (2) and the step (4) can be used for preparing a black silicon texturing solution and/or a black silicon cleaning solution. In some embodiments, the deionized water washed in step (2) is used to prepare a black silicon texturing solution, and the deionized water washed in step (4) is used to prepare a black silicon cleaning solution.
The method according to a preferred embodiment of the present invention, wherein the method comprises the steps of:
(1) immersing a silicon wafer into black silicon texturing liquid for texturing, wherein the texturing temperature is 25-30 ℃, and the texturing time is 3-5 minutes; wherein the black silicon texturing solution comprises 0.1-0.5mmol/L silver nitrate, 0-50mmol/L copper nitrate, 3-4.5mol/L hydrofluoric acid and 2-6mol/L nitric acid;
(2) washing the silicon wafer subjected to texturing prepared in the step (1) by using deionized water, and drying;
(3) cleaning the dried silicon wafer obtained in the step (2) by using a black silicon cleaning solution at the temperature of 25-40 ℃ for 3-5 minutes to remove metal particles deposited on the surface of the silicon wafer; wherein the black silicon cleaning solution is a nitric acid solution with the concentration of 20-69 wt%;
(4) washing the silicon wafer washed by the black silicon washing liquid obtained in the step (3) with deionized water, and drying to obtain a silicon wafer with a textured structure; and
(5) repeating the steps (1) to (4) until the black silicon texturing solution and the black silicon cleaning solution reach the service life, and preparing the black silicon texturing solution in the step (1) by taking the black silicon cleaning solution reaching the service life as a raw material; wherein the service lives of the black silicon texturing solution and the black silicon cleaning solution are 100000-120000 silicon wafers, and the consumption of the black silicon cleaning solution reaching the service life is 15-70% of the volume of the black silicon texturing solution.
According to the method provided by the invention, the black silicon texturing solution used in the step (1) and the black silicon cleaning solution used in the step (3) can have the same volume or different volumes.
The method of the invention has the following advantages:
(1) the method is suitable for industrial production of the black silicon solar cell and is mainly applied to the texturing stage of the black silicon solar cell.
(2) By selecting the components and contents of the black silicon texturing solution and the black silicon cleaning solution, the black silicon texturing solution contains metal ion salts, hydrofluoric acid and nitric acid (oxidant), and the nitric acid solution is adopted as the black silicon cleaning solution, so that the main components of the black silicon cleaning solution reaching the service life are nitric acid and metal ions corresponding to the metal ion salts in the black silicon texturing solution, the black silicon texturing solution can be prepared by adopting the black silicon cleaning solution reaching the service life, and the black silicon cleaning solution, especially the metal ions in the black silicon texturing solution can be recycled. Meanwhile, the black silicon texturing solution and the black silicon cleaning solution have the same service life by controlling the content of each component of the black silicon texturing solution and the black silicon cleaning solution, and at least 1 percent of the black silicon cleaning solution, such as 15 to 70 percent of the black silicon cleaning solution or the black silicon cleaning solution reaching the service life is used for preparing the black silicon texturing solution.
In addition, the black silicon texturing solution prepared by the black silicon cleaning solution with the service life is consistent with the texturing effect of the black silicon texturing solution prepared by the raw materials corresponding to the components of the black silicon texturing solution, and the recycling of the black silicon cleaning solution with the service life does not bring adverse effects to texturing.
Therefore, the method can simply and effectively realize the cleaning liquid in the production process of the black silicon solar cell, particularly the recycling of metal ions in the cleaning liquid, reduces the texturing cost and the wastewater treatment cost of the black silicon solar cell, and is green and environment-friendly.
(3) The method is simple to operate and easy for industrial production.
For the current industrialized black silicon texturing and cleaning process, because the conventional black silicon texturing liquid used by the black silicon texturing and cleaning process usually adopts hydrogen peroxide instead of nitric acid as an oxidant, the main components of the black silicon texturing and cleaning liquid are generally one or two metal ion salts, hydrofluoric acid, hydrogen peroxide and deionized water. When the conventional black silicon texturing solution is prepared by using a nitric acid cleaning solution with a certain service life, a new component, namely nitric acid, is introduced into the black silicon texturing solution, so that the component of the black silicon texturing solution is changed, the texture structure of a silicon wafer after texturing is changed, the texture structure is sharp and poor in flatness, subsequent diffusion and coating are not facilitated, and the recycling of the black silicon cleaning solution cannot be realized.
Drawings
Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:
FIG. 1 is an SEM image of a textured silicon wafer having metal particles deposited on the surface thereof prepared in step one of example 1 of the present invention;
FIG. 2 is an SEM image of a silicon wafer with textured structure prepared in step three of example 1 of the present invention;
FIG. 3 is an SEM image of a textured silicon wafer with metal particles deposited on the surface thereof prepared in step six of example 1 of the present invention;
FIG. 4 is an SEM image of a silicon wafer with textured structure prepared in step six of example 1 of the present invention;
FIG. 5 is an SEM image of a silicon wafer with textured structure prepared in step three of comparative example 1; and
fig. 6 is an SEM image of a silicon wafer having a textured structure prepared in step six of comparative example 1.
Detailed Description
The present invention is described in further detail below with reference to specific embodiments, which are given for the purpose of illustration only and are not intended to limit the scope of the invention.
Example 1
The method comprises the following steps: taking a P-type diamond wire-cut polycrystalline silicon wafer (the resistivity is 1-3 omega cm) with the size of 156mm multiplied by 156mm, immersing the P-type diamond wire-cut polycrystalline silicon wafer into acidic black silicon texturing liquid in a texturing groove for texturing, wherein the reaction temperature is 25 ℃, the reaction time is 5 minutes, and silver metal particles which are discretely distributed are formed on the surface of the silicon wafer; the acidic black silicon texturing solution is prepared from silver nitrate, copper nitrate, hydrofluoric acid, nitric acid and deionized water, the total volume is 300L, the concentration of the silver nitrate is 0.5mmol/L, the concentration of the copper nitrate is 50mmol/L, the concentration of the hydrofluoric acid is 3mol/L, and the concentration of the nitric acid is 4 mol/L.
Step two: and (4) taking out the silicon wafer subjected to texturing obtained in the step one, cleaning the silicon wafer with deionized water, and drying the silicon wafer with high-purity nitrogen.
Step three: cleaning the dried silicon wafer obtained in the second step by using a black silicon cleaning solution to remove silver metal particles on the surface of the silicon wafer, cleaning by using deionized water, and drying by using high-purity nitrogen to obtain the silicon wafer with a textured structure; wherein the black silicon cleaning solution is nitric acid solution, the total volume is 300L, the mass percentage concentration is 69 wt%, the temperature for cleaning with the black silicon cleaning solution is 40 ℃, and the time is 3 minutes.
Step four: and repeating the first step, the second step and the third step until the service lives of the acidic black silicon texturing solution and the black silicon cleaning solution are reached, wherein the service lives of the acidic black silicon texturing solution and the black silicon cleaning solution are 120000. Wherein, every time 400 silicon wafers are processed, black silicon texturing liquid and black silicon cleaning liquid are supplemented once, the total volume of the supplemented black silicon texturing liquid is 300L, the concentration of silver nitrate is 0.5mmol/L, the concentration of copper nitrate is 50mmol/L, the concentration of hydrofluoric acid is 3mol/L, and the concentration of nitric acid is 4 mol/L; and the total volume of the replenished black silicon cleaning solution is 300L, and the mass percentage concentration is 69 wt%.
Step five: emptying the acidic black silicon texturing solution in the texturing groove, injecting 50L of black silicon cleaning solution which is obtained in the fourth step and reaches the service life into the texturing groove, and adding deionized water, silver nitrate, copper nitrate, hydrofluoric acid and nitric acid into the texturing groove to prepare new acidic black silicon texturing solution; wherein the total volume of the new acidic black silicon texturing solution is 300L, the concentration of silver nitrate is 0.5mmol/L, the concentration of copper nitrate is 50mmol/L, the concentration of hydrofluoric acid is 3mol/L, the concentration of nitric acid is 4mol/L, and the rest 250L of black silicon cleaning solution reaching the service life is stored in a container for later use.
Step six: and (4) adopting the new acidic black silicon texturing solution prepared in the fifth step as the black silicon texturing solution, performing the operation of the first step, and then continuing to perform the second step and the third step to prepare the silicon wafer with the textured structure.
Fig. 1 shows an SEM image of a textured silicon wafer prepared in step one. As shown in fig. 1, silver metal particles are deposited on the surface of the silicon wafer and have a size distribution ranging from about 10nm to 1 μm.
Fig. 3 shows an SEM image of the textured silicon wafer prepared in step six. As shown in fig. 3, silver metal particles having a size ranging from about 10nm to 1 μm are deposited on the surface of the silicon wafer.
Fig. 2 and 4 show textured structures of the silicon wafer prepared in the third step and the sixth step, respectively.
Comparing fig. 1 and 3 with fig. 2 and 4, respectively, it can be found that the texture-making effect of the acidic black silicon texture-making liquid prepared by using the black silicon cleaning liquid with the service life is substantially the same as that of the acidic black silicon texture-making liquid prepared by using the raw materials corresponding to the components of the acidic black silicon texture-making liquid, and the texture structure of the silicon wafer prepared in the sixth step is substantially the same as that of the silicon wafer prepared in the third step.
Example 2
The method comprises the following steps: taking a P-type diamond wire-cut polycrystalline silicon wafer (the resistivity is 1-3 omega cm) with the size of 156mm multiplied by 156mm, immersing the P-type diamond wire-cut polycrystalline silicon wafer into acidic black silicon texturing liquid in a texturing groove for texturing, wherein the reaction temperature is 30 ℃, the reaction time is 5 minutes, and silver metal particles which are discretely distributed are formed on the surface of the silicon wafer; the acidic black silicon texturing solution is prepared from silver nitrate, hydrofluoric acid, nitric acid and deionized water, the total volume is 200L, the concentration of the silver nitrate is 0.5mmol/L, the concentration of the hydrofluoric acid is 4.5mol/L, and the concentration of the nitric acid is 4 mol/L.
Step two: and (4) taking out the silicon wafer subjected to texturing obtained in the step one, cleaning the silicon wafer with deionized water, and drying the silicon wafer with high-purity nitrogen.
Step three: cleaning the dried silicon wafer obtained in the second step by using a black silicon cleaning solution to remove silver metal particles on the surface of the silicon wafer, cleaning by using deionized water, and drying by using high-purity nitrogen to obtain the silicon wafer with a textured structure; wherein the black silicon cleaning solution is a nitric acid solution, the total volume is 200L, the mass percentage concentration is 20 wt%, the temperature for cleaning with the black silicon cleaning solution is 25 ℃, and the time is 5 minutes.
Step four: and repeating the first step, the second step and the third step until the service lives of the acidic black silicon texturing solution and the black silicon cleaning solution are reached, wherein the service lives of the acidic black silicon texturing solution and the black silicon cleaning solution are 100000. Wherein, every time 200 silicon wafers are processed, black silicon texturing liquid and black silicon cleaning liquid are supplemented, the total volume of the supplemented black silicon texturing liquid is 200L, the concentration of silver nitrate is 0.5mmol/L, the concentration of hydrofluoric acid is 4.5mol/L, and the concentration of nitric acid is 4 mol/L; and the total volume of the replenished black silicon cleaning solution is 200L, and the mass percentage concentration is 20 wt%.
Step five: emptying the acidic black silicon texturing solution in the texturing groove, injecting 140L of black silicon cleaning solution with the service life reached in the fourth step into the texturing groove, and adding deionized water, silver nitrate, hydrofluoric acid and nitric acid into the texturing groove to prepare new acidic black silicon texturing solution; wherein the total volume of the new acidic black silicon texturing solution is 200L, the concentration of silver nitrate is 0.5mmol/L, the concentration of hydrofluoric acid is 4.5mol/L, the concentration of nitric acid is 4mol/L, and the rest 60L of black silicon cleaning solution reaching the service life is stored in a container for later use.
Step six: and (4) adopting the new acidic black silicon texturing solution prepared in the fifth step as the black silicon texturing solution, performing the operation of the first step, and then continuing to perform the second step and the third step to prepare the silicon wafer with the textured structure.
And characterizing the silicon wafer subjected to texturing and the silicon wafer with a textured structure prepared in the first step, the third step and the sixth step by using an SEM (scanning Electron microscope). The results show that the texture-making effect of the acidic black silicon texture-making liquid prepared by using the black silicon cleaning liquid with the service life is basically consistent with that of the acidic black silicon texture-making liquid prepared by using raw materials corresponding to the components of the acidic black silicon texture-making liquid, and the texture structure of the silicon wafer prepared in the sixth step is basically consistent with that of the silicon wafer prepared in the third step.
Comparative example 1
The method comprises the following steps: taking a P-type diamond wire-cut polycrystalline silicon wafer (the resistivity is 1-3 omega cm) with the size of 156mm multiplied by 156mm, immersing the P-type diamond wire-cut polycrystalline silicon wafer into acidic black silicon texturing liquid in a texturing groove for texturing, wherein the reaction temperature is 25 ℃, the reaction time is 5 minutes, and silver metal particles which are discretely distributed are formed on the surface of the silicon wafer; the acidic black silicon texturing solution is prepared from silver nitrate, copper nitrate, hydrofluoric acid, hydrogen peroxide and deionized water, the total volume is 300L, the concentration of the silver nitrate is 0.5mmol/L, the concentration of the copper nitrate is 50mmol/L, the concentration of the hydrofluoric acid is 3mol/L, and the concentration of the hydrogen peroxide is 0.7 mol/L.
Step two: and (4) taking out the silicon wafer subjected to texturing obtained in the step one, cleaning the silicon wafer with deionized water, and drying the silicon wafer with high-purity nitrogen.
Step three: cleaning the dried silicon wafer obtained in the second step by using a black silicon cleaning solution to remove silver metal particles on the surface of the silicon wafer, cleaning by using deionized water, and drying by using high-purity nitrogen to obtain the silicon wafer with a textured structure; wherein the black silicon cleaning solution is nitric acid solution, the total volume is 300L, the mass percentage concentration is 69 wt%, the temperature for cleaning with the black silicon cleaning solution is 40 ℃, and the time is 3 minutes.
Step four: and repeating the first step, the second step and the third step until the service lives of the acidic black silicon texturing solution and the black silicon cleaning solution are reached, wherein the service lives of the acidic black silicon texturing solution and the black silicon cleaning solution are 120000. Wherein, every time 400 silicon wafers are processed, black silicon texturing liquid and black silicon cleaning liquid are supplemented once, the total volume of the supplemented black silicon texturing liquid is 300L, the concentration of silver nitrate is 0.5mmol/L, the concentration of copper nitrate is 50mmol/L, the concentration of hydrofluoric acid is 4.5mol/L, and the concentration of hydrogen peroxide is 0.7 mol/L; and the total volume of the replenished black silicon cleaning solution is 300L, and the mass percentage concentration is 69 wt%.
Step five: emptying the acidic black silicon texturing solution in the texturing groove, injecting 80L of black silicon cleaning solution with the service life reached in the fourth step into the texturing groove, and adding deionized water, silver nitrate, copper nitrate, hydrofluoric acid and hydrogen peroxide into the texturing groove to prepare new acidic black silicon texturing solution; wherein the total volume of the new acidic black silicon texturing solution is 300L, the concentration of silver nitrate is 0.5mmol/L, the concentration of copper nitrate is 50mmol/L, the concentration of hydrofluoric acid is 3mol/L, the concentration of hydrogen peroxide is 0.7mol/L, the concentration of nitric acid is 4mol/L, and the rest 220L of black silicon cleaning solution reaching the service life is stored in a container for later use.
Step six: and (4) adopting the new acidic black silicon texturing solution prepared in the fifth step as the texturing solution, performing the first step and the second step, and then continuing to perform the second step and the third step to prepare the silicon wafer with the textured structure.
And characterizing the silicon wafer subjected to texturing and the silicon wafer with a textured structure prepared in the first step, the third step and the sixth step by using an SEM (scanning Electron microscope).
The results show that the silver metal particles deposited on the surface of the textured silicon wafer prepared in the first step range in size from about 10nm to about 1 μm, and the silver metal particles deposited on the surface of the textured silicon wafer prepared in the sixth step range in size from about 10nm to about 1 μm.
Fig. 5 and 6 show textured structures of the silicon wafer prepared in the third step and the sixth step, respectively. Further referring to fig. 2, it is found through comparison that the texture structure (fig. 5) obtained after texture making in the acidic black silicon texturing solution using hydrogen peroxide as an oxidant is substantially identical to the texture structure (fig. 2) obtained after texture making in the acidic black silicon texturing solution using nitric acid as an oxidant, and the texture structure (fig. 6) obtained after texture making in the acidic black silicon texturing solution using a black silicon cleaning solution (the oxidant includes hydrogen peroxide and nitric acid) is sharp, and the surface flatness is poor, which is not favorable for subsequent diffusion and coating.
In addition, the acidic black silicon texturing solution adopting hydrogen peroxide as an oxidant and nitric acid as an oxidant may cause slight difference in structure under different concentrations, so that the texture structures shown in fig. 2 and 5 are slightly different but still substantially consistent.
Claims (10)
1. A method for texturing a silicon wafer by recycling black silicon cleaning solution, the method comprising the steps of:
(1) immersing a silicon wafer into black silicon texturing liquid for texturing; wherein the black silicon texturing solution contains 0.01-200mmol/L of metal ion salt, 1-10mol/L of hydrofluoric acid and 0.1-10mol/L of nitric acid;
(2) washing the silicon wafer subjected to texturing prepared in the step (1) by using deionized water, and drying;
(3) cleaning the dried silicon wafer obtained in the step (2) by using a black silicon cleaning solution to remove metal particles deposited on the surface of the silicon wafer; wherein the black silicon cleaning solution is a nitric acid solution with the concentration of 20-80 wt%;
(4) washing the silicon wafer washed by the black silicon washing liquid obtained in the step (3) with deionized water, and drying to obtain a silicon wafer with a textured structure; and
(5) and (3) repeating the steps (1) to (4) until the black silicon cleaning solution reaches the service life, and preparing the black silicon texturing solution in the step (1) by taking the black silicon cleaning solution reaching the service life as a raw material.
2. The method of claim 1, wherein the silicon wafer is a P-type diamond wire-cut polycrystalline silicon wafer, a P-type diamond wire-cut monocrystalline silicon wafer, an N-type diamond wire-cut monocrystalline silicon wafer, or a P-type mortar-cut polycrystalline silicon wafer, preferably a P-type diamond wire-cut polycrystalline silicon wafer.
3. The method of claim 1 or 2, wherein the black silicon texturing solution comprises one or two salts of metal ions;
preferably, the metal ion salt is selected from silver ion salts such as silver nitrate and copper ion salts such as copper nitrate;
further preferably, the black silicon texturing solution contains 0.1-0.5mmol/L of silver nitrate and 0-50mmol/L of copper nitrate.
4. The method according to any one of claims 1 to 3, wherein the concentration of hydrofluoric acid in the black silicon texturing solution is 3-4.5 mol/L; the concentration of nitric acid is 2-6mol/L, for example 4 mol/L.
5. The method according to any one of claims 1 to 4, wherein the temperature of the wool making in step (1) is 8-80 ℃, preferably 25-30 ℃; the time is 30 seconds to 10 minutes, preferably 3 to 5 minutes.
6. The method as claimed in any one of claims 1 to 5, wherein the concentration of nitric acid in the black silicon cleaning solution is 20-69 wt%.
7. The method as claimed in any one of claims 1 to 6, wherein the temperature for cleaning with black silicon cleaning solution in the step (3) is 10-60 ℃, preferably 25-40 ℃; the time is 30 seconds to 10 minutes, preferably 3 to 5 minutes.
8. The method as claimed in any one of claims 1 to 7, wherein the black silicon texturing solution has a service life of 1000-200000 silicon wafers, and the black silicon cleaning solution has a service life of 1000-200000 silicon wafers;
preferably, the service life of the black silicon texturing solution and the black silicon cleaning solution is 100000-120000 silicon wafers.
9. The method according to any one of claims 1 to 8, wherein when the black silicon texturing solution in the step (1) is prepared by taking a black silicon cleaning solution reaching the service life as a raw material in the step (5), the amount of the black silicon cleaning solution reaching the service life is 1-100% of the volume of the black silicon texturing solution, preferably 15-70%;
preferably, the deionized water washed in the step (2) and the step (4) is used for preparing a black silicon texturing solution and/or a black silicon cleaning solution;
more preferably, the deionized water washed in the step (2) is used for preparing a black silicon texturing solution, and the deionized water washed in the step (4) is used for preparing a black silicon cleaning solution.
10. The method according to any one of claims 1 to 9, wherein the method comprises the steps of:
(1) immersing a silicon wafer into black silicon texturing liquid for texturing, wherein the texturing temperature is 25-30 ℃, and the texturing time is 3-5 minutes; wherein the black silicon texturing solution comprises 0.1-0.5mmol/L silver nitrate, 0-50mmol/L copper nitrate, 3-4.5mol/L hydrofluoric acid and 2-6mol/L nitric acid;
(2) washing the silicon wafer subjected to texturing prepared in the step (1) by using deionized water, and drying;
(3) cleaning the dried silicon wafer obtained in the step (2) by using a black silicon cleaning solution at the temperature of 25-40 ℃ for 3-5 minutes to remove metal particles deposited on the surface of the silicon wafer; wherein the black silicon cleaning solution is a nitric acid solution with the concentration of 20-69 wt%;
(4) washing the silicon wafer washed by the black silicon washing liquid obtained in the step (3) with deionized water, and drying to obtain a silicon wafer with a textured structure; and
(5) repeating the steps (1) to (4) until the black silicon texturing solution and the black silicon cleaning solution reach the service life, and preparing the black silicon texturing solution in the step (1) by taking the black silicon cleaning solution reaching the service life as a raw material; wherein the service lives of the black silicon texturing solution and the black silicon cleaning solution are 100000-120000 silicon wafers, and the consumption of the black silicon cleaning solution reaching the service life is 15-70% of the volume of the black silicon texturing solution.
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