WO2017201702A1 - 一种单晶硅片表面织构化的方法 - Google Patents

一种单晶硅片表面织构化的方法 Download PDF

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WO2017201702A1
WO2017201702A1 PCT/CN2016/083413 CN2016083413W WO2017201702A1 WO 2017201702 A1 WO2017201702 A1 WO 2017201702A1 CN 2016083413 W CN2016083413 W CN 2016083413W WO 2017201702 A1 WO2017201702 A1 WO 2017201702A1
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silicon wafer
single crystal
crystal silicon
mixed solution
metal
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PCT/CN2016/083413
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English (en)
French (fr)
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孙雪云
李渊
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南京中云新材料有限公司
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Priority to CN201680003137.XA priority Critical patent/CN107924836B/zh
Priority to PCT/CN2016/083413 priority patent/WO2017201702A1/zh
Publication of WO2017201702A1 publication Critical patent/WO2017201702A1/zh

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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
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to the field of crystalline silicon, and more particularly to a method for surface texturing of a single crystal silicon wafer.
  • crystalline silicon photovoltaic cells are the mainstream in solar photovoltaic cells. Its outstanding properties have been proven by many successful applications and have been mass produced. However, in practical applications, when sunlight is incident on the surface of the crystalline silicon of the crystalline silicon photovoltaic cell, part of the light will reflect, greatly reducing the sunlight entering the battery and reducing the short-circuit optical current density of the crystalline silicon photovoltaic cell. In turn, it affects its photoelectric conversion efficiency. It can be seen that increasing the absorption of light by crystalline silicon is the key to improving the photoelectric conversion efficiency of crystalline silicon photovoltaic cells.
  • the texturing of the crystalline silicon surface of a crystalline silicon photovoltaic cell is a commonly used method to increase its light absorption and reduce light reflection. Textured, also known as texturing, utilizes the principle of trapping to reflect incident light multiple times to extend its propagation path on the surface of crystalline silicon and improve the light absorption efficiency of crystalline silicon photovoltaic cells.
  • the anisotropic etching principle of single crystal silicon can be used to form an inverted pyramid-like texture on the surface of the single crystal silicon wafer, which can effectively reduce the reflection of light.
  • the inverted pyramidal texture of the surface of the single crystal silicon wafer is basically realized by metal catalytic corrosion, that is, the deposition of Ag, Au, Cu, Fe, Al, Ni on the surface of the single crystal silicon wafer by chemical method. Or a metal particle such as Pt, and then catalytically etching, immersing the single crystal silicon wafer deposited with the metal particles in a mixed solution containing hydrofluoric acid and hydrogen peroxide for etching.
  • the above process can be carried out by a two-step process, that is, the first step is to deposit metal particles on the surface of the single crystal silicon wafer, and the second step is to immerse the single crystal silicon wafer deposited with the metal particles in a mixed solution containing hydrofluoric acid and hydrogen peroxide.
  • the catalytic etching is performed in the middle. It can also be accomplished by a one-step process in which a single crystal silicon wafer is immersed in a mixed solution containing hydrofluoric acid, an oxidizing agent such as hydrogen peroxide, and the above metal ions, while simultaneously depositing metal particles and catalytic etching on the surface of the single crystal silicon wafer.
  • the above method can basically realize the inverted pyramid-like texture of the surface of the single crystal silicon wafer, since the metal particles deposited on the surface of the single crystal silicon are poor in uniformity and easy to agglomerate, the surface texture size is difficult to control and remains after corrosion. The problem that the metal particles are difficult to remove and the single crystal silicon wafer after the texture is unstable is unstable.
  • the present invention provides a method for surface texturing of a single crystal silicon wafer.
  • the technical solutions are as follows:
  • a method for surface texturing a single crystal silicon wafer which can form an inverted pyramid surface texture on a surface of a single crystal silicon, and the method can include:
  • the single crystal silicon wafer is placed in the mixed solution A for surface metal deposition and etching treatment to form an inverted pyramid texture;
  • the mixed solution A comprises hydrofluoric acid, an oxidizing agent, a metal ion, a dispersing agent and water;
  • the dispersing agent comprises an anionic dispersing agent, a nonionic surfactant, a disintegrating agent and water, and the mass percentage of the anionic dispersing agent is 20-40% based on the total mass of the dispersing agent, and the nonionic surface active agent
  • the mass percentage of the agent is 8-15%, the mass percentage of the disintegrant is 3-8%, and the balance is water;
  • the metal or metal oxide remaining on the surface of the single crystal silicon wafer is removed by cleaning.
  • the anionic dispersant is preferably selected from the group consisting of calcium lignosulfonate, naphthalenesulfonate, polycarboxylate, sodium naphthalenesulfonate formaldehyde condensate, fatty acid amide-N-methyl taurate Or one or a combination of alkyl sulfosuccinates.
  • the said "calcium lignosulfonate” (referred to as wood calcium) is a multi-component high molecular polymer anionic surfactant, the appearance of light yellow to dark brown powder, slightly aromatic smell, the molecular weight is generally 800 ⁇ 10000 Between, it has strong dispersibility, cohesiveness and chelation.
  • the "naphthalene sulfonate” includes, but is not limited to, sodium 1-naphthalenesulfonate and sodium 2-naphthalenesulfonate.
  • the "polycarboxylate” includes, but is not limited to, maleic acid-sodium acrylate, sodium polyacrylate, and samarium diureate dispersant wgwin 600C.
  • the "sodium naphthalenesulfonate formaldehyde condensate” is also known as sodium methylene dinaphthalene sulfonate or a dispersant NNO, and is an anionic dispersant commonly used in the industry.
  • the fatty amides in the "fatty amide-N-methyl taurates” include C8-C24 fatty amides such as coconut oil (acid) amide, lauric acid (acid) amide, soybean meal (acid) amide, palm (acid) An amide, a stearic acid amide, an oil (acid) amide, and the like.
  • “Alkyl sulfosuccinate” is a product obtained by reacting maleic anhydride with a suitable fatty alcohol (such as a C8-C24 fatty alcohol) or an alkyl (C8-C24) phenol and reacting with a sulfite. .
  • the nonionic surfactant is preferably selected from one or a combination of a fatty alcohol polyether and an alkylphenol polyether.
  • a fatty alcohol polyether is a copolymer of a fatty alcohol or a fatty alcohol with ethylene oxide or epichlorohydrin. Such as fatty alcohol polyoxyethylene ether (preferably molecular weight 400-1200), commonly known as flat plus.
  • Alkylphenol polyether is formed by copolymerization of alkylphenol with ethylene oxide and epichlorohydrin, such as alkylphenol ethoxylate (preferably molecular weight 400-1200), which is commonly used in industry as nonylphenol. Polyoxyethylene ether and octylphenol ethoxylate, and other classic products such as TX-10, OP-10.
  • the disintegrant used may be selected from disintegrators commonly used in the medical field or other fields, and is preferably selected from the group consisting of sodium chloride, sodium sulfate, sodium carboxymethyl starch, ammonium sulfate, sodium carbonate, urea, and crosslinked polyvinylpyrrolidone ( One or a combination of crospovidone and sodium alginate.
  • sodium carboxymethyl starch, cross-linked polyvinylpyrrolidone, sodium alginate and sodium carbonate are all disintegrating agents commonly used in the field of medicine, and the present invention does not need to be specifically described herein, and those skilled in the art can use the present invention according to the present invention. Description The material is obtained and the invention is implemented.
  • a dispersant required for the present invention by selecting an appropriate amount of an anionic dispersant, a nonionic surfactant, a disintegrant and water in accordance with the above description; in addition, those skilled in the art can be prepared by those skilled in the art. It is possible to select a suitable commercial dispersant according to the above description regarding the dispersant. For example, the inventors of the present application found that the dispersant ZYFS-1000 produced by Nanjing Zhongyun New Material Co., Ltd. is suitable for the technical solution of the present invention.
  • the oxidizing agent in the above mixed solution A may be an oxidizing agent commonly used in catalytic etching of a single crystal silicon metal in the prior art, such as hydrogen peroxide, or ozone or the like as an oxidizing agent.
  • the oxidizing agent in the mixed solution A is preferably hydrogen peroxide, or ozone.
  • the ozone can be prepared by an ozone generator and dissolved in the mixed solution A to achieve its oxidation.
  • the ozone generator is a prior art, and the present invention is not limited thereto, and the skilled person can A suitable ozone generator is selected to implement the technical solution of the present invention.
  • the metal ion may include at least one of gold, silver, copper, iron, aluminum, nickel, and platinum ions.
  • the various ions described above may be provided by nitrates and/or sulfates, preferably by nitrates.
  • silver nitrate can provide silver ions
  • nickel nitrate can provide nickel ions and the like.
  • the mixed solution A in the present invention can be obtained by using hydrofluoric acid, an oxidizing agent, a metal ion and a dispersing agent. It is obtained by mixing and adding an appropriate amount of solvent water. among them,
  • the mass percentage of hydrofluoric acid is 1-20%, preferably 5-15%, more preferably 6-10%, based on the total mass of the mixed solution A;
  • the mass percentage of hydrogen peroxide is 1-20%, preferably 5-15%, more preferably 6-10%, based on the total mass of the mixed solution A; when the oxidizing agent is ozone, ozone
  • the concentration of the metal ion is 0.2-6 mmol/L, preferably 0.5-5 mmol/L, more preferably 1-3 mmol/L, based on the total volume of the mixed solution A;
  • the mass fraction of the dispersant is from 5 to 40%, preferably from 10 to 30%, more preferably from 15 to 25%, based on the total mass of the mixed solution A.
  • hydrofluoric acid or hydrogen peroxide as a solute refers to pure hydrofluoric acid or pure hydrogen peroxide, or can be understood as a hydrofluoric acid having a mass fraction of 100% or The mass fraction is 100% hydrogen peroxide. Since pure hydrofluoric acid or pure hydrogen peroxide is generally not available in practical applications, for example, commercially available hydrofluoric acid is generally hydrofluoric acid having a mass fraction of 40%, and hydrogen peroxide is generally The mass fraction is 30% hydrogen peroxide (hydrogen peroxide). Therefore, it is necessary to prepare the mixed solution A by converting the commercially available hydrofluoric acid or hydrogen peroxide into pure hydrofluoric acid or pure hydrogen peroxide by conversion of the mass fraction.
  • hydrofluoric acid As an example, to prepare a mixed solution A containing 10% hydrofluoric acid A 10 kg, the required solute hydrofluoric acid is 1 kg, if the purchased hydrofluoric acid The mass fraction is 40%, then 2.5 kg, the mass fraction of 40% hydrofluoric acid is equivalent to 1 kg of pure hydrofluoric acid.
  • the conversion method of hydrogen peroxide is the same. The invention will not be described here.
  • the water used is preferably deionized water, distilled water or double distilled water (re-distilled water).
  • the single crystal silicon wafer can be placed in the mixed solution A at a temperature of 10 to 95 ° C, preferably 30 to 85 ° C, more preferably 40 to 60 ° C for 1 to 60 minutes. It is preferably 10-30 minutes, more preferably 10-15 minutes.
  • the surface of the single crystal silicon wafer has some oily dirt, organic impurities, etc., it needs to be cleaned.
  • the surface gold can be placed in the mixed solution A in a single crystal silicon wafer.
  • the single crystal silicon wafer Prior to deposition and etching, the single crystal silicon wafer is placed in a lower alcohol for 1-30 minutes, preferably 10-20 minutes.
  • the lower alcohol is understood to be a C1-C6 alcohol, preferably a C1-C4 alcohol, for example, methanol, ethanol, isopropanol and n-butanol.
  • the surface may be damaged during the cutting process, especially the diamond wire cutting single crystal silicon wafer, the surface damage is more serious, which may make it difficult to generate inverted pyramid texture on the surface. Even if it is generated, it is difficult to control the shape of the texture.
  • the single crystal silicon wafer can be subjected to surface metal deposition and etching treatment before immersing the single crystal silicon wafer in the mixed solution A. It was placed in an alkali solution at a temperature of 30-85 ° C for 1 to 30 minutes to remove the surface damage layer of the single crystal silicon wafer, followed by washing with water. The thickness of the damaged layer is generally between 2 and 10 um.
  • the diamond wire-cut single crystal silicon wafer refers to a single crystal silicon wafer cut by a diamond wire cutting process.
  • the alkali solution in the lye (aqueous alkali solution) used in this step may have a mass fraction of 2 to 40%, preferably 10 to 20%.
  • Bases used in the lye include, but are not limited to, sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, sodium carbonate, and sodium hydrogencarbonate.
  • the single crystal silicon wafer may be first placed in the lower alcohol. Soak for 1-30 minutes.
  • the lower alcohol is understood to be a C1-C6 alcohol, preferably a C1-C4 alcohol, for example, methanol, ethanol, isopropanol and n-butanol.
  • the foregoing step of immersing the single crystal silicon wafer in the lower alcohol is generally only required to be performed once, that is, if the single crystal silicon wafer is required to be placed in the alkali liquid to remove the surface damage layer of the single crystal silicon wafer. Then, it can be carried out before this step. If it is not necessary to immerse the single crystal silicon wafer in the alkali solution to remove the surface damage layer of the single crystal silicon wafer, the surface metal deposition and etching are performed by placing the single crystal silicon wafer in the mixed solution A. Just do it before processing.
  • the existing metal or metal oxide may be used.
  • Technically related technical solutions are generally carried out by using a strong acid having an oxidizing property to deoxidize and corrode the remaining metal or metal oxide.
  • Ben Ming people found that when the existing method is used to clean the metal or metal oxide remaining on the surface of the single crystal silicon wafer, the time required is long and the efficiency is low.
  • the present invention creatively provides a method for cleaning and removing metal or metal oxide remaining on the surface of a single crystal silicon wafer, and the method may include:
  • the monocrystalline silicon wafer forming the inverted pyramid texture is placed in the mixed solution B at 20-60 ° C for 1-30 minutes, preferably 10-15 minutes, and then washed with water;
  • the mixed solution B contains an etchant, an oxidant and water; the etchant is selected from the group consisting of sulfuric acid, nitric acid and ammonia; and the oxidizing agent is selected from hydrogen hydride or ozone.
  • the mass percentage of the etchant is 3-30%, preferably 5-20%; when the oxidant is hydrogen hydride, the mass percentage of hydrogen peroxide is based on the total mass of the mixed solution B. 1-10%, preferably 4-8%; when the oxidizing agent is ozone, the concentration of ozone in the mixed solution B is 2-40 ppm, preferably 8-18 ppm, more preferably 10-15 ppm.
  • sulfuric acid, nitric acid, ammonia water and hydrogen peroxide as solute are all referred to as pure sulfuric acid, pure nitric acid, pure ammonia water or pure hydrogen peroxide, or can be understood as mass fraction. It is 100% sulfuric acid, 100% by mass of nitric acid, 100% by mass of ammonia or 100% by mass of hydrogen peroxide. Since the above pure sulfuric acid, pure nitric acid, pure ammonia water or pure hydrogen peroxide is generally not available in the actual application process, it is also required to be converted by the above-mentioned mass fraction conversion method, and the specific conversion method can be referred to. The foregoing examples of hydrofluoric acid are not described herein.
  • the method for cleaning and removing the residual metal or metal oxide on the surface of the single crystal silicon wafer can significantly improve the removal efficiency of the metal or metal oxide, and at the same time, can modify the surface texture morphology of the single crystal silicon wafer, that is, The microporous silicon produced during the surface metal deposition and etching treatment is removed.
  • an oxide layer may be formed on the surface of the single crystal silicon wafer, and if it is not removed, the subsequent steps may be affected.
  • the single crystal silicon wafer after removing the metal or metal oxide is placed in a hydrofluoric acid solution having a mass fraction of 1-10% for 1 to 30 minutes, preferably 2 to 7 minutes, and then washed with pure water to remove the single crystal. Silicon surface oxygen Layer. Further, the single crystal silicon wafer from which the surface oxide layer has been removed may be further subjected to a drying treatment.
  • the drying treatment of this step can be carried out by a conventional operation in the art, and the present invention is not specifically limited herein.
  • the mixed solution A used is specially added with a special formulation of a dispersing agent, and the dispersing agent can be added. Effectively prevent the agglomeration of metal particles, so that the deposition of metal particles on the surface of the single crystal silicon wafer is more uniform, so that it is easy to form a size-controlled inverted pyramid-like texture on the surface of the single crystal silicon wafer; and effective control of metal particle agglomeration is ensured.
  • the metal particle size is consistent. In the subsequent metal or metal oxide removal process, the reaction time is easy to control, and the metal or metal oxide particles are also easier to remove. Moreover, the metal particle size is consistent and can make the last single The inverted pyramid size of the surface of the crystalline silicon is consistent in size, and the uniformity of the aperture size ensures that the reflectivity of the single crystal silicon wafer is more stable.
  • the removal method of the metal or metal oxide remaining on the surface of the single crystal silicon wafer provided by the present invention has higher removal efficiency of the metal or metal oxide, and can further modify the surface texture morphology of the single crystal silicon wafer.
  • Example 1 is a micrograph of a surface textured by a single crystal silicon wafer by the method of Example 1;
  • Example 2 is a graph showing reflectance results of a single crystal silicon wafer treated in Example 1 and a conventional single pyramid silicon wafer treated with a conventional orthorhombic texturing technique.
  • a single crystal silicon wafer (Xi'an Longji Silicon Material Co., Ltd., 156*156N diamond wire monocrystalline silicon wafer) is taken as an example, and as mentioned above, King Kong The surface damage of the wire-cut single crystal silicon wafer is generally serious.
  • the single crystal silicon wafer Before placing the single crystal silicon wafer in the mixed solution A for surface metal deposition and etching, the single crystal silicon wafer needs to be immersed in the lower alcohol to remove impurities. The organic matter is then placed in an alkali solution to remove the surface damage layer of the single crystal silicon wafer.
  • the two steps are necessary for all the single crystal silicon wafers, and those skilled in the art can determine whether to perform the two steps according to the actual processing needs.
  • the single crystal silicon wafer was immersed in ethanol for 15 minutes at room temperature; it was placed in a 30% aqueous solution of sodium hydroxide at 60 ° C for 3 minutes; after washing with water, it was placed in a mixed solution A at 40 ° C. After 18 minutes, it was washed with water; then placed in mixed solution B at 40 ° C for 15 minutes, then washed with water, and then placed in a hydrofluoric acid solution of 10% by mass for 2 minutes at room temperature, washed with water. After drying.
  • the mass percentage of hydrofluoric acid in the mixed solution A is 10%
  • the mass percentage of hydrogen peroxide is 10%
  • the mass percentage of the dispersing agent is 10%.
  • the concentration of silver ions was 1 mmol/L, and silver ions were supplied by silver nitrate.
  • the mixed solution B contained 10% by mass of nitric acid and 10% by mass of hydrogen peroxide.
  • the single crystal silicon wafer was immersed in methanol at room temperature for 30 minutes; it was placed in a 40% sodium carbonate aqueous solution at 85 ° C for 2.5 minutes; after washing with water, it was placed in a mixed solution A at 60 ° C. After a minute, it was washed with water; it was further placed in a mixed solution B at 40 ° C for 12 minutes, and then washed with water, and then placed in a hydrofluoric acid solution having a mass fraction of 2% for 6 minutes, washed with water and dried.
  • the mass percentage of hydrofluoric acid in the mixed solution A is 15%
  • the mass percentage of hydrogen peroxide is 15%
  • the mass percentage of the dispersing agent is 15%
  • the concentration of copper ions is 0.5 mmol/L
  • the silver ion is composed of copper nitrate.
  • the mixed solution B contained 20% by mass of aqueous ammonia and 10% by mass of hydrogen peroxide.
  • the single crystal silicon wafer was immersed in isopropanol at room temperature for 10 minutes; it was placed in a 20% mass% aqueous solution of tetramethylammonium hydroxide at 40 ° C for 15 minutes; after washing with water, it was placed at 65 ° C.
  • the mass percentage of hydrofluoric acid in the mixed solution A is 6%
  • the mass percentage of hydrogen peroxide is 5%
  • the mass percentage of the dispersing agent is 25%
  • the concentration of nickel ions is 3 mmol/L
  • the nickel ion is provided by nickel nitrate.
  • the mixed solution B contained nitric acid having a mass fraction of 5% and a hydrogen peroxide content of 8% by mass.
  • the single crystal silicon wafer was immersed in n-butanol at room temperature for 5 minutes; it was placed in a 10% sodium hydroxide aqueous solution at 50 ° C for 16 minutes; after washing with water, it was placed in a mixed solution at 30 ° C. 30 minutes in A, then washed with water; then placed in mixed solution B at 20 ° C for 30 minutes, then washed with water, and then placed in a hydrofluoric acid solution of 8% by mass for 3 minutes, washed with water and dried .
  • the mass percentage of hydrofluoric acid in the mixed solution A is 5%
  • the mass percentage of hydrogen peroxide is 20%
  • the mass percentage of the dispersing agent is 30%
  • the concentration of nickel ions is 6 mmol/L
  • the nickel ion is provided by nickel nitrate.
  • the mixed solution B contained 20% by mass of nitric acid and 4% by mass of hydrogen peroxide.
  • the single crystal silicon wafer was immersed in ethanol at room temperature for 20 minutes; it was placed in a 30 ° C aqueous solution of 5% sodium hydroxide for 30 minutes; after washing with water, it was placed in a mixed solution A at 50 ° C. After 15 minutes, it was washed with water; it was further placed in a mixed solution B at 60 ° C for 4 minutes, then washed with water, and then placed in a hydrofluoric acid solution having a mass fraction of 5% for 7 minutes, washed with water and dried.
  • the mass percentage of hydrofluoric acid in the mixed solution A is 20%
  • the mass percentage of hydrogen peroxide is 6%
  • the mass percentage of the dispersing agent is 40%
  • the concentration of silver ions is 5 mmol/L
  • silver ions are provided by silver nitrate.
  • the mixed solution B contained ammonia water having a mass fraction of 30% and hydrogen peroxide having a mass fraction of 6%.
  • Example 6 The difference between Example 6 and Example 1 was that the oxidizing agent in the mixed solution A was ozone at a concentration of 8 ppm, and the temperature at which the single crystal silicon wafer was placed in the mixed solution A was 85 ° C for 8 minutes.
  • Example 7 The difference between Example 7 and Example 6 was that the concentration of ozone in the mixed solution A was 15 ppm; the oxidizing agent in the mixed solution B was ozone at a concentration of 8 ppm.
  • Example 8 The difference between Example 8 and Example 2 was that the oxidizing agent in the mixed solution A was ozone at a concentration of 18 ppm; the oxidizing agent in the mixed solution B was ozone at a concentration of 18 ppm.
  • Example 9 The difference between Example 9 and Example 3 is that the oxidant in the mixed solution A is ozone at a concentration of 40 ppm, the temperature at which the single crystal silicon wafer is placed in the mixed solution A is 30 ° C, and the time is 8 minutes; The oxidant is ozone and its concentration is 15 ppm.
  • Example 10 The difference between Example 10 and Example 4 was that the oxidizing agent in the mixed solution A was ozone at a concentration of 10 ppm; the oxidizing agent in the mixed solution B was ozone at a concentration of 10 ppm.
  • the single crystal silicon wafer subjected to the surface texturing treatment by the method of Example 1 was photographed with a 10*60 ⁇ microscope, and the photograph is shown in FIG. 1;
  • an inverted pyramid-like texture is formed on the surface of the single crystal silicon wafer, and the inverted pyramid has a low reflection and a black color, which is an excellent light trapping structure. .
  • the aperture size of the inverted pyramid-like texture is consistent and the distribution is relatively uniform, indicating that the size of the inverted pyramid-like texture is controllable.
  • the light trapping structure with low reflectivity is beneficial to the improvement of solar cell conversion efficiency.
  • the uniform distribution of the inverted pyramids is also conducive to the stability of the supporting process of the front and back channels. For example, in the subsequent removal of metal or metal oxides, the reaction time is easily controlled, and the metal or metal oxide particles are also more easily removed.
  • the convex portion is brightened in the inverted pyramid and between the inverted pyramids, and has a rugged microstructure, which further reduces the reflectance and improves the conversion efficiency, and not only does it fall.
  • the pyramid structure and microstructure are favorable for the contact between the silver paste and the surface of the single crystal silicon wafer after printing the silver paste, and the contact surface is superior to the positive pyramid, thereby generating a better eutectic interface and reducing the series resistance.
  • the commercially available Xi'an Longji Silicon Materials Co., Ltd., 156*156N diamond wire monocrystalline silicon wafers are traditional
  • the silicon wafer 1 obtained after the positive pyramid is obtained by the following method: the single crystal silicon wafer is placed in an aqueous sodium hydroxide solution having a mass fraction of 20% at 80 ° C for 10 minutes for initial polishing, washed with water, and then It was placed in an aqueous solution of sodium hydroxide having a mass fraction of 2% at 80 ° C for 15 minutes for texturing, washed with water, and then placed in a mass fraction of 20% hydrochloric acid at room temperature for 3 minutes to neutralize the residue.
  • the sodium hydroxide is washed with water, and then the single crystal silicon wafer is placed in a mass fraction of 7% hydrofluoric acid at room temperature for 1 minute, and the silicon dioxide layer on the surface of the silicon wafer is complexed, washed with water and dried.
  • the silicon wafer 1 and the single crystal silicon wafer (referred to as the silicon wafer 2) treated in the first embodiment were respectively subjected to a reflectance test by a D8 integral reflectometer of Shanghai Zhidong Optoelectronics Technology Co., Ltd., and the results are shown in Fig. 2.
  • the method for surface texturing of single crystal silicon provided by the present invention can effectively reduce the light reflectance of single crystal silicon.
  • the commercially available Xi'an Longji Silicon Material Co., Ltd., 156*156N diamond wire monocrystalline silicon wafer was washed with water in the mixed solution A for 10 minutes after the method of Example 2, and then divided into two groups: the control group and the experimental group, and the control group.
  • the group was treated with ammonia water having a mass fraction of 20% for 5 minutes; the experimental group was treated with the mixed solution B of Example 2 for 5 minutes.
  • the temperature is 40 ° C.
  • the method for cleaning and removing the residual metal or metal oxide on the surface of the single crystal silicon wafer provided by the invention has a faster reaction speed and higher efficiency.

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Abstract

本发明实施例公开了一种单晶硅片表面织构化的方法，包括：将单晶硅片置于混合溶液A中进行表面金属沉积和刻蚀处理，形成倒金字塔状织构；其中，所述混合溶液A包含氢氟酸、氧化剂、金属离子、分散剂及水；所述分散剂包括阴离子型分散剂、非离子表面活性剂、崩解剂及水，且基于所述分散剂的总质量，所述阴离子型分散剂的质量百分数为20-40％，非离子表面活性剂的质量百分数为8-15％，崩解剂的质量百分数为3-8％，余量为水；清洗去除单晶硅片表面残留的金属或金属氧化物。本发明的技术方案可以有效防止金属粒子团聚，使得单晶硅片表面金属粒子沉积的更加均匀，这样很容易在单晶硅片表面形成尺寸可控的倒金字塔状织构。

Description

一种单晶硅片表面织构化的方法 技术领域
本发明涉及晶体硅领域，特别涉及一种单晶硅片表面织构化的方法。
背景技术
目前，晶体硅光伏电池是太阳能光伏电池中的主流。其优异特性已为众多成功的应用所证实，并已实现大规模生产。但是在实际应用中，当太阳光入射到晶体硅光伏电池的晶体硅表面上时，部分光将产生反射现象，大大减少了进入电池的太阳光从而降低了晶体硅光伏电池的短路光电流密度，进而影响其光电转换效率。可见，尽可能增加晶体硅对光的吸收，是提高晶体硅光伏电池光电转换效率的关键所在。
对晶体硅光伏电池的晶体硅表面进行织构化处理是一种常用的增加其光吸收、减少光反射的方法。织构化又称制绒，其利用陷光原理，使入射光进行多次反射从而延长其在晶体硅表面的传播路径，提高晶体硅光伏电池对光的吸收效率。对于单晶硅光伏电池，可以利用单晶硅的各向异性腐蚀原理，在单晶硅片表面形成类似倒金字塔的织构，能够有效降低光的反射。
现有技术中，单晶硅片表面倒金字塔状织构基本是通过金属催化腐蚀来实现，也就是说，先通过化学法在单晶硅片表面沉积Ag、Au、Cu、Fe、Al、Ni、或Pt等金属颗粒，然后再进行催化刻蚀，将沉积有金属颗粒的单晶硅片浸入含有氢氟酸和过氧化氢组成的混合溶液中进行刻蚀。上述的过程可以采用两步法完成，即第一步在单晶硅片表面沉积金属颗粒，第二步将沉积有金属颗粒的单晶硅片浸入含有氢氟酸和过氧化氢组成的混合溶液中进行催化刻蚀。还可以采用一步法完成，即将单晶硅片浸入含有氢氟酸、氧化剂例如过氧化氢及上述金属离子的混合溶液中，同时实现单晶硅片表面沉积金属颗粒及催化刻蚀。
上述的方法虽然能够基本实现单晶硅片表面的倒金字塔状织构化，但由于沉积在单晶硅表面的金属颗粒均匀性差，容易团聚，因此存在表面织构尺寸难以控制、腐蚀后残余的金属颗粒难以去除、织构化后的单晶硅片反射率不稳定等问题。
发明内容
为解决上述现有技术中单晶硅片表面的倒金字塔状织构化所存在的问题，本发明提供了一种单晶硅片表面织构化的方法。技术方案如下：
一种单晶硅片表面织构化的方法，可以在单晶硅表面形成倒金字塔状的表面织构，该方法可以包括：
将单晶硅片置于混合溶液A中进行表面金属沉积和刻蚀处理，形成倒金字塔状织构；其中，所述混合溶液A包含氢氟酸、氧化剂、金属离子、分散剂及水；所述分散剂为包括阴离子型分散剂、非离子表面活性剂、崩解剂及水，且基于所述分散剂的总质量，所述阴离子分散剂的质量百分数为20-40％，非离子表面活性剂的质量百分数为8-15％，崩解剂的质量百分数为3-8％，余量为水；
清洗去除单晶硅片表面残留的金属或金属氧化物。
在上述方案中，所述阴离子型分散剂优选选自于木质素磺酸钙、萘磺酸盐、聚羧酸盐、萘磺酸钠甲醛缩合物、脂肪酰胺-N-甲基牛磺酸盐、烷基磺基琥珀酸盐中的一种或其组合。所说的“木质素磺酸钙”(简称木钙)是一种多组分高分子聚合物阴离子表面活性剂，外观为浅黄色至深棕色粉末，略有芳香气味，分子量一般在800～10000之间，具有很强的分散性、粘结性、螯合性。所说的“萘磺酸盐”包括但不限于1-萘磺酸钠及2-萘磺酸钠。所说的“聚羧酸盐”包括但不限于马来酸-丙烯酸钠盐、聚丙烯酸钠及朗钛达润分散剂wgwin 600C等。所说的“萘磺酸钠甲醛缩合物”又称为亚甲基二萘磺酸钠或分散剂NNO，为工业中常用的阴离子分散剂。所说的“脂肪酰胺-N-甲基牛磺酸盐”中的脂肪酰胺包括C8-C24脂肪酰胺，如椰油(酸)酰胺、月桂(酸)酰胺、豆蔻(酸)酰胺、棕榈(酸)酰胺、硬脂(酸)酰胺及油(酸)酰胺等。“烷基磺基琥珀酸盐”是由顺丁烯二酸酐与适当的脂肪醇(如C8-C24脂肪醇)、烷基(C8-C24)酚反应后，与亚硫酸盐反应后所得的产物。如琥珀酸二辛酯磺酸钠盐、辛基酚聚氧乙烯醚磺基琥珀酸钠盐、壬基酚聚氧乙烯醚磺基琥珀酸钠盐及十六醇琥珀酸单酯磺酸钠等。
非离子表面活性剂优选选自于脂肪醇聚醚及烷基酚聚醚中的一种或其组合。“脂肪醇聚醚”是由脂肪醇、或由脂肪醇与环氧乙烷、环氧氯丙烷共聚而 成，如脂肪醇聚氧乙烯醚(优选分子量400-1200)，俗称平平加。“烷基酚聚醚”是由烷基酚与环氧乙烷、环氧氯丙烷共聚而成，如烷基酚聚氧乙烯醚(优选分子量400-1200)，工业中常用的为壬基酚聚氧乙烯醚及辛基酚聚氧乙烯醚等，经典的产品如TX-10、OP-10等。
所用的崩解剂可以选自于医药领域或其它领域常用的崩解剂，优选选自氯化钠、硫酸钠、羧甲基淀粉钠、硫酸铵、碳酸钠、尿素、交联聚乙烯吡咯烷酮(交联聚维酮)及海藻酸钠中的一种或其组合。其中，羧甲基淀粉钠、交联聚乙烯吡咯烷酮、海藻酸钠及碳酸钠等均为医药领域常用的崩解剂，本发明在此无需进行具体说明，本领域技术人员可以根据本发明在此的描述获得该物质并实现本发明。
本领域技术人员根据上述的记载选择适量的阴离子型分散剂、非离子表面活性剂、崩解剂与水混合，从而可以制备出本发明所需的分散剂；除此之外，本领域技术人员可能根据上述关于分散剂的记载，选择合适的商品化分散剂，例如，本申请的发明人发现，南京中云新材料有限公司生产的分散剂ZYFS-1000就适用于本发明的技术方案。
上述混合溶液A中的氧化剂既可以采用现有技术中对单晶硅金属催化刻蚀时所常用的氧化剂，例如过氧化氢等，还可以采用臭氧等作为氧化剂。
在本发明的一种优选实施方式中，混合溶液A中的氧化剂优选为过氧化氢，或臭氧。当采用臭氧作为氧化剂时，臭氧可以通过臭氧发生器来制备，并溶于混合溶液A中来实现其氧化作用，臭氧发生器是现有技术，本发明在此不进行限定，技术人员可以根据需要来选择合适的臭氧发生器来实现本发明的技术方案。
在现有技术中，已经大量报道了可以实现在单晶硅表面沉积的金属离子，对于本发明技术方案中的混合溶液A，可以不限定的包含有现有技术中已知的各种金属离子，优选地，所述金属离子可以包括金、银、铜、铁、铝、镍及铂离子中的至少一种。在实际应用中，上述的各种离子可以由硝酸盐和/或硫酸盐提供，优选由硝酸盐提供。例如，硝酸银可以提供银离子，硝酸镍可以提供镍离子等。
本发明中的混合溶液A可以通过将氢氟酸、氧化剂、金属离子及分散剂 混合并添加适量的溶剂水来获得。其中，
基于混合溶液A的总质量，氢氟酸的质量百分数为1-20％，优选为5-15％，更优选为6-10％；
在氧化剂为过氧化氢时，基于混合溶液A的总质量，过氧化氢的质量百分数为1-20％，优选为5-15％，更优选为6-10％；在氧化剂为臭氧时，臭氧在混合溶液A中的浓度为2-40ppm，优选为8-18ppm，更优选为10-15ppm；在本发明中，1ppm＝1毫克/升；
基于混合溶液A的总体积，所述金属离子的浓度为0.2-6mmol/L，优选为0.5-5mmol/L，更优选为1-3mmol/L；
基于混合溶液A的总质量，分散剂的质量分数为5-40％，优选为10-30％，更优选为15-25％。
需要说明的是，在配制混合溶液A时，作为溶质的氢氟酸或过氧化氢均指的是纯氢氟酸或纯过氧化氢，或者可以理解为质量分数为100％的氢氟酸或质量分数为100％的过氧化氢。由于在实际的应用过程中，纯氢氟酸或纯过氧化氢一般是无法购得的，例如，市售的氢氟酸一般为质量分数为40％的氢氟酸，而过氧化氢一般为质量分数为30％的过氧化氢(双氧水)。因此，需要通过质量分数的换算将市售的氢氟酸或过氧化氢转换成纯氢氟酸或纯过氧化氢来配制混合溶液A。
下面以氢氟酸为例，对上述的换算过程进行说明，例如，要配制含10％氢氟酸的混合溶液A 10kg，所需要的溶质氢氟酸为1kg，如果购得的氢氟酸的质量分数为40％，那么2.5kg、质量分数为40％氢氟酸即相当于1kg纯氢氟酸。过氧化氢的换算方法相同。本发明在此不再进行说明。
在本发明中，所用的水优选为去离子水、蒸馏水或双蒸水(重蒸水)。
在本发明的一种具体实施方案中，可以将单晶硅片置于温度为10-95℃，优选为30-85℃，更优选为40-60℃的混合溶液A中1-60分钟，优选为10-30分钟，更优选10-15分钟。
在实际应用时，由于单晶硅片表面会有一些油污、有机物杂质等，需要对其进行清洁处理。具体的，可以在将单晶硅片置于混合溶液A中进行表面金 属沉积和刻蚀处理之前，先将单晶硅片置于低级醇中浸泡1-30分钟，优选为10-20分钟。所说的低级醇可以理解为C1-C6的醇，优选为C1-C4的醇，例如，甲醇、乙醇、异丙醇及正丁醇等。
对于单晶硅片，其在进行切割的过程中，表面可能会有损伤，尤其是金刚线切割单晶硅片，其表面损伤更严重，这会导致很难在其表面生成倒金字塔状织构，即使生成，也很难对该织构的形态大小进行控制。
所以当单晶硅片尤其是金刚线切割单晶硅片的表面损伤比较严重时，可以在将单晶硅片浸入混合溶液A中进行表面金属沉积和刻蚀处理之前，先将单晶硅片置于温度为30-85℃的碱液中1-30分钟，以去除单晶硅片表面损伤层，之后用水清洗。一般损伤层的去除厚度在2-10um之间。所说的金刚线切割单晶硅片指的是以金刚线切割工艺切割出的单晶硅片。
此步骤中所用的碱液(碱的水溶液)中碱的质量分数可以为2-40％，优选为10-20％。碱液中所用的碱包括但不限于氢氧化钠、氢氧化钾、四甲基氢氧化铵、碳酸钠及碳酸氢钠。
类似的，在将单晶硅片置于碱液中去除单晶硅片表面损伤层之前，为了去除单晶硅片表面的油污、有机物杂质等，也可以先将单晶硅片置于低级醇中浸泡1-30分钟。所说的低级醇可以理解为C1-C6的醇，优选为C1-C4的醇，例如，甲醇、乙醇、异丙醇及正丁醇等。
需要说明的是，前述的将单晶硅片置于低级醇中浸泡的步骤，一般只需要进行一次即可，即如果需要将单晶硅片置于碱液中去除单晶硅片表面损伤层，那么可以在此步骤之前进行，如果不需要将单晶硅片浸入碱液中去除单晶硅片表面损伤层，则在将单晶硅片置于混合溶液A中进行表面金属沉积和刻蚀处理之前进行即可。
在本发明的技术方案中，在将单晶硅片置于混合溶液A中进行表面金属沉积和刻蚀处理后，需要清洗去除单晶硅片表面残留的金属或金属氧化物，可以采用现有技术的相关技术方案来进行，其方法一般都是采用具有氧化性的强酸去氧化、腐蚀所残留的金属或金属氧化物。本明人在实际应用过程中发现，采用现有的方法来清洗去除单晶硅片表面残留的金属或金属氧化物时，所需的时间较长，效率较低。
为了提高清洗去除单晶硅片表面残留的金属或金属氧化物的效率，本发明创造性的提供了一种清洗去除单晶硅片表面残留的金属或金属氧化物的方法，该方法可以包括：
将形成倒金字塔状织构的单晶硅片置于20-60℃的混合溶液B中1-30分钟，优选10-15分钟，之后用水清洗；
所说的混合溶液B包含有腐蚀剂、氧化剂及水；所述腐蚀剂选自硫酸、硝酸及氨水中的一种；所述氧化剂选自过氢化氢或臭氧。
其中，基于混合溶液B的总质量，腐蚀剂的质量百分数为3-30％，优选为5-20％；在氧化剂为过氢化氢时，基于混合溶液B的总质量，过氧化氢的质量百分数为1-10％，优选为4-8％；在氧化剂为臭氧时，臭氧在混合溶液B中的浓度为2-40ppm，优选为8-18ppm，更优选为10-15ppm。
需要说明的是，本发明中配制混合溶液B时，作为溶质的硫酸、硝酸、氨水及过氧化氢均指的是纯硫酸、纯硝酸、纯氨水或纯过氧化氢，或者可以理解为质量分数为100％的硫酸、质量分数为100％的硝酸、质量分数为100％的氨水或质量分数为100％的过氧化氢。由于在实际的应用过程中，上述纯硫酸、纯硝酸、纯氨水或纯过氧化氢一般是无法购得的，所以也需要采用前述的质量分数换算的方法进行换算得到，具体的换算方法可以参考前述的氢氟酸的示例，本发明在此不进行赘述。
采用本发明提供的清洗去除单晶硅片表面残留的金属或金属氧化物的方法，可以显著提高金属或金属氧化物去除效率，并同时能够修饰单晶硅片表面织构形态，就是说，可以将表面金属沉积和刻蚀处理反应过程中产生的微孔硅除去。
经过上述的各步骤的处理后，单晶硅片表面可能形成氧化层，如果不去掉，会影响后续工序的进行。
所以，在去除单晶硅片表面残留的金属或金属氧化物后，还可以包括以下步骤：
将去除了金属或金属氧化物后的单晶硅片置于质量分数为1-10％的氢氟酸溶液中1-30分钟，优选为2-7分钟，之后用纯水清洗，去除单晶硅片表面氧 化层。进一步地，还可以将去除了表面氧化层的单晶硅片再进行干燥处理。此步的干燥处理，可以采用本领域的常规操作来实现，本发明在此不进行具体限定。
综上所述，本发明的技术方案，在对单晶硅片进行表面金属沉积和刻蚀处理时，所采用的混合溶液A中特别添加了特殊配方的分散剂，该分散剂的加入，可以有效防止金属粒子团聚，使得单晶硅片表面金属粒子沉积的更加均匀，这样很容易在单晶硅片表面形成尺寸可控的倒金字塔状织构；而对金属粒子团聚的有效控制，保证了金属粒子大小一致性好，在后续的金属或金属氧化物的去除过程中，反应时间容易控制，金属或金属氧化物颗粒也更容易去除；不仅如此，金属粒子大小一致性好，可以使得最后单晶硅表面织构化的倒金字塔孔径大小一致性好，而孔径大小一致性好则能够保证单晶硅片的反射率更稳定。
另外，采用本发明提供的单晶硅片表面残留的金属或金属氧化物的去除方法，金属或金属氧化物的去除效率更高，并能够进一步修饰单晶硅片表面织构形态。
附图说明
为了更清楚地说明本发明实施例和现有技术的技术方案，下面对实施例和现有技术中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为采用实施例1的方法对单晶硅片进行表面织构化后的显微镜照片；
图2为实施例1处理后的单晶硅片与传统正金字塔制绒技术处理后的单晶硅片的反射率结果图。
具体实施方式
为使本发明的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本发明进一步详细说明。显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
需要说明的是，下面各实施例中均以金刚线切割单晶硅片(西安隆基硅材料有限公司，156*156N型金刚线单晶硅片)为例进行说明，而如前所述，金刚线切割单晶硅片表面损伤一般比较严重，在将单晶硅片置于混合溶液A中进行表面金属沉积和刻蚀处理之前，需要先将单晶硅片置于低级醇中浸泡去除杂质及有机物，然后再置于碱液中去除单晶硅片表面损伤层。但并不表示这两步工序对所有的单晶硅片都是必需的，本领域技术人员可以根据实际的处理需要来确定是否进行这两步工序。
实施例1
将单晶硅片置于乙醇中室温浸泡15分钟后；再将其置于60℃的质量分数为30％的氢氧化钠水溶液中3分钟；水洗后将其置于40℃的混合溶液A中18分钟，之后用水清洗；再将其置于40℃的混合溶液B中15分钟，之后用水清洗，在室温下，再将其置于质量分数为10％的氢氟酸溶液中2分钟，水洗后烘干。
其中，混合溶液A中氢氟酸的质量百分数为10％，过氧化氢的质量百分数为10％，分散剂(南京中云新材料有限公司生产的分散剂ZYFS-1000)的质量百分数为10％，银离子的浓度为1mmol/L，银离子由硝酸银提供。混合溶液B包含质量分数为10％的硝酸，质量分数为10％的过氧化氢。
实施例2-10中所用的分散剂的配方如表1所示。
实施例2
将单晶硅片置于甲醇中常温浸泡30分钟后；再将其置于85℃的质量分数为40％的碳酸钠水溶液中2.5分钟；水洗后将其置于60℃的混合溶液A中10分钟，之后用水清洗；再将其置于40℃的混合溶液B中12分钟，之后用水清洗，再将其置于质量分数为2％的氢氟酸溶液中6分钟，水洗后烘干。
其中，混合溶液A中氢氟酸的质量百分数为15％，过氧化氢的质量百分数为15％，分散剂的质量百分数为15％，铜离子的浓度为0.5mmol/L，银离子由硝酸铜提供。混合溶液B包含质量分数为20％的氨水，质量分数为10％的过氧化氢。
实施例3
将单晶硅片置于异丙醇中常温浸泡10分钟后；再将其置于40℃的质量分数为20％的四甲基氢氧化铵水溶液中15分钟；水洗后将其置于65℃的混合溶液A中8分钟，之后用水清洗；再将其置于50℃的混合溶液B中10分钟，之后用水清洗，再将置于质量分数为5％的氢氟酸溶液中4分钟，水洗后烘干。
其中，混合溶液A中氢氟酸的质量百分数为6％，过氧化氢的质量百分数为5％，分散剂的质量百分数为25％，镍离子的浓度为3mmol/L，镍离子由硝酸镍提供。混合溶液B包含质量分数为5％的硝酸，质量分数为8％的过氧化氢。
实施例4
将单晶硅片置于正丁醇中常温浸泡5分钟后；再将其置于50℃的质量分数为10％的氢氧化钠水溶液中16分钟；水洗后将其置于30℃的混合溶液A中30分钟，之后用水清洗；再将其置于20℃的混合溶液B中30分钟，之后用水清洗，再将置于质量分数为8％的氢氟酸溶液中3分钟，水洗后烘干。
其中，混合溶液A中氢氟酸的质量百分数为5％，过氧化氢的质量百分数为20％，分散剂的质量百分数为30％，镍离子的浓度为6mmol/L，镍离子由硝酸镍提供。混合溶液B包含质量分数为20％的硝酸，质量分数为4％的过氧化氢。
实施例5
将单晶硅片置于乙醇中常温浸泡20分钟后；再将其置于30℃的质量分数为5％的氢氧化钠水溶液中30分钟；水洗后将其置于50℃的混合溶液A中15分钟，之后用水清洗；再将其置于60℃的混合溶液B中4分钟，之后用水清洗，再将置于质量分数为5％的氢氟酸溶液中7分钟，水洗后烘干。
其中，混合溶液A中氢氟酸的质量百分数为20％，过氧化氢的质量百分数为6％，分散剂的质量百分数为40％，银离子的浓度为5mmol/L，银离子由硝酸银提供。混合溶液B包含质量分数为30％的氨水，质量分数为6％的过氧化氢。
实施例6
实施例6与实施例1的区别在于：混合溶液A中的氧化剂为臭氧，其浓度为8ppm，单晶硅片置于混合溶液A中的温度为85℃，时间为8分钟。
实施例7
实施例7与实施例6的区别在于：混合溶液A中臭氧的浓度为15ppm；混合溶液B中的氧化剂为臭氧，其浓度为8ppm。
实施例8
实施例8与实施例2的区别在于：混合溶液A中的氧化剂为臭氧，其浓度为18ppm；混合溶液B中的氧化剂为臭氧，其浓度为18ppm。
实施例9
实施例9与实施例3的区别在于：混合溶液A中的氧化剂为臭氧，其浓度为40ppm，单晶硅片置于混合溶液A中的温度为30℃，时间为8分钟；混合溶液B中的氧化剂为臭氧，其浓度为15ppm。
实施例10
实施例10与实施例4的区别在于：混合溶液A中的氧化剂为臭氧，其浓度为10ppm；混合溶液B中的氧化剂为臭氧，其浓度为10ppm。
测试与结果
将采用实施例1的方法进行表面织构化处理后的单晶硅片用10*60倍显微镜进行拍照，其照片如图1所示；
从图1中可以看出：采用实施例1的方法进行处理后，单晶硅片表面生成了倒金字塔状织构，该倒金字塔处反光很低，颜色很黑，为极佳的陷光结构。而且从图1中也可以看出，倒金字塔状织构的孔径大小一致性好，而且分布也比较均匀，说明了倒金字塔状织构的尺寸可控性好。反射率低的陷光结构有利于太阳能电池转换效率的提升。倒金字塔分布比较均匀也有利于前后道配套工艺的稳定性，例如在后续的金属或金属氧化物的去除过程中，反应时间容易控制，金属或金属氧化物颗粒也更容易去除。
另外，从图1中还可以看出，在倒金字塔内及倒金字塔间发亮凸起部分，具有凹凸不平的微结构，这些微结构使反射率进一步下降，可提高转换效率，不仅如此，倒金字塔结构及微结构有利于印刷银浆后，银浆与单晶硅片表面的接触，接触面优于正金字塔，从而可生成更好的共晶界面，降低串联电阻，
提升填充因子FF从而提高太阳能电池的功率输出。
表1实施例2-10中所用的分散剂配方
Figure PCTCN2016083413-appb-000001
注：百分数均为质量百分数
反射率对比实验
将市售的西安隆基硅材料有限公司，156*156N型金刚线单晶硅片经传统 正金字塔制绒后获得的硅片1，其制绒方法如下：将单晶硅片置于80℃，质量分数为20％的氢氧化钠水溶液中10分钟进行初抛处理，用水清洗后，再将其置于80℃，质量分数为2％的氢氧化钠水溶液中15分钟进行制绒，用水清洗后于室温下将单晶硅片置于质量分数20％的盐酸中3分钟，中和残余的氢氧化钠，用水清洗后于室温下将单晶硅片置于质量分数7％的氢氟酸中1分钟，络合掉硅片表面的二氧化硅层，用水清洗后干燥即得。
将硅片1与实施例1处理后的单晶硅片(称为硅片2)采用上海致东光电科技有限公司D8积分式反射仪分别进行反射率测试，结果如图2所示。从图2中可以看出，本发明提供的单晶硅表面织构化的方法，可以有效的降低单晶硅的光反射率。
实施例11
将市售的西安隆基硅材料有限公司，156*156N型金刚线单晶硅片采用实施例2的方法在混合溶液A中10分钟后用水清洗，然后分成两组：对照组及实验组，对照组采用质量分数为20％的氨水处理5分钟；实验组采用实施例2中的混合溶液B处理5分钟。温度均为40℃。经肉眼观察，对照组在处理过程中产生的气泡不明显，处理5分钟后仍然看到硅片表面铜膜。实验组在处理过程中产生的气泡明显，处理5分钟后硅片表面铜膜肉眼无法观察到。可见，本发明提供的清洗去除单晶硅片表面残留的金属或金属氧化物的方法，反应速度更快，效率更高。
以上对本发明所提供的一种单晶硅片表面织构化的方法进行了详细介绍。本文中应用了具体实施例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其中心思想。应当指出，对于本领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以对本发明进行若干改进和修饰，这些改进和修饰也落入本发明权利要求的保护范围内。

Claims (23)

  1. 一种单晶硅片表面织构化的方法，其特征在于，包括：
    将单晶硅片置于混合溶液A中进行表面金属沉积和刻蚀处理，形成倒金字塔状织构；其中，所述混合溶液A包含氢氟酸、氧化剂、金属离子、分散剂及水；所述分散剂包括阴离子型分散剂、非离子表面活性剂、崩解剂及水，且基于所述分散剂的总质量，所述阴离子型分散剂的质量百分数为20-40％，非离子表面活性剂的质量百分数为8-15％，崩解剂的质量百分数为3-8％，余量为水；
    清洗去除单晶硅片表面残留的金属或金属氧化物。
  2. 如权利要求1所述的方法，其特征在于，所述阴离子型分散剂选自于木质素磺酸钙、萘磺酸盐、聚羧酸盐、萘磺酸钠甲醛缩合物、脂肪酰胺-N-甲基牛磺酸盐、烷基磺基琥珀酸盐中的一种或其组合。
  3. 如权利要求1所述的方法，其特征在于，所述非离子表面活性剂选自于脂肪醇聚醚及烷基酚聚醚中的一种或其组合。
  4. 如权利要求1所述的方法，其特征在于，所述崩解剂选自于氯化钠、硫酸钠、羧甲基淀粉钠、硫酸铵、碳酸钠、尿素、交联聚乙烯吡咯烷酮及海藻酸钠中的一种或其组合。
  5. 如权利要求1所述的方法，其特征在于，基于混合溶液A的总质量，氢氟酸的质量百分数为1-20％，优选为5-15％，更优选为6-10％。
  6. 如前述权利要求任意一项所述的方法，其特征在于，所述氧化剂为过氧化氢或臭氧。
  7. 如权利要求6所述的方法，其特征在于，在氧化剂为过氧化氢时，基于混合溶液A的总质量，过氧化氢的质量百分数为1-20％，优选为5-15％，更优选为6-10％；在氧化剂为臭氧时，臭氧在混合溶液A中的浓度为2-40ppm，优选为8-18ppm，更优选为10-15ppm。
  8. 如前述权利要求任意一项所述的方法，其特征在于，基于混合溶液A的总体积，所述金属离子的浓度为0.2-6mmol/L，优选为0.5-5mmol/L，更优选为1-3mmol/L。
  9. 如前述权利要求任意一项所述的方法，其特征在于，所述金属离子包括金、银、铜、铁、铝、镍及铂离子中的至少一种。
  10. 如前述权利要求任意一项所述的方法，其特征在于，所述金属离子由硝酸盐和/或硫酸盐提供。
  11. 如前述权利要求任意一项所述的方法，其特征在于，基于混合溶液A的总质量，分散剂的质量分数为5-40％，优选为10-30％，更优选为15-25％。
  12. 如前述权利要求任意一项所述的方法，其特征在于，混合溶液A的温度为10-95℃，优选为30-85℃，更优选为40-60℃。
  13. 如前述权利要求任意一项所述的方法，其特征在于，单晶硅片置于温混合溶液A中的时间为1-60分钟，优选为10-30分钟，更优选为10-15分钟。
  14. 如前述权利要求任意一项所述的方法，其特征在于，在将单晶硅片置于混合溶液A中进行表面金属沉积和刻蚀处理之前，还包括：
    将单晶硅片置于低级醇中浸泡1-30分钟。
  15. 如权利要求1-13中任意一项所述的方法，其特征在于，在将单晶硅片置于混合溶液A中进行表面金属沉积和刻蚀处理之前，还包括：
    将单晶硅片置于温度为30-85℃的碱液中1-30分钟，去除单晶硅片表面损伤层，之后用水清洗。
  16. 如权利要求15所述的方法，其特征在于，碱液中碱的质量分数为2-40％。
  17. 如权利要求15或16所述的方法，其特征在于，碱液中的碱选自于氢氧化钠、氢氧化钾、四甲基氢氧化铵、碳酸钠及碳酸氢钠中的至少一种。
  18. 如权利要求15-17中任一项所述的方法，其特征在于，在将单晶硅片置于碱液中去除单晶硅片表面损伤层之前，还包括：
    将单晶硅片置于低级醇中浸泡1-30分钟。
  19. 如前述权利要求任意一项所述的方法，其特征在于，所述清洗去除单晶硅片表面残留的金属或金属氧化物，包括：
    将形成倒金字塔状织构的单晶硅片置于20-60℃的混合溶液B中1-30分钟， 之后用水清洗；
    所述混合溶液B包含腐蚀剂、氧化剂及水；所述腐蚀剂选自硫酸、硝酸及氨水中的一种；所述氧化剂选自过氢化氢或臭氧。
  20. 如权利要求19所述的方法，其特征在于，基于混合溶液B的总质量，腐蚀剂的质量百分数为3-30％；在氧化剂为过氢化氢时，基于混合溶液B的总质量，过氧化氢的质量百分数为1-10％；在氧化剂为臭氧时，臭氧在混合溶液B中的浓度为2-40ppm。
  21. 如前述权利要求任意一项所述的方法，其特征在于，在去除单晶硅片表面残留的金属或金属氧化物后，还包括：
    将去除了金属或金属氧化物后的单晶硅片置于质量分数为1-10％的氢氟酸溶液中1-30分钟，之后用纯水清洗，去除单晶硅片表面氧化层。
  22. 如权利要求21所述的方法，其特征在于，将去除了表面氧化层的单晶硅片进行干燥处理。
  23. 如前述权利要求任意一项所述的方法，其特征在于，所述分散剂为南京中云新材料有限公司生产的分散剂ZYFS-1000。
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