CN109427930B - Method for selectively preparing suede on surface of crystal silicon wafer - Google Patents

Method for selectively preparing suede on surface of crystal silicon wafer Download PDF

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CN109427930B
CN109427930B CN201710787717.9A CN201710787717A CN109427930B CN 109427930 B CN109427930 B CN 109427930B CN 201710787717 A CN201710787717 A CN 201710787717A CN 109427930 B CN109427930 B CN 109427930B
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silicon wafer
crystalline silicon
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texturing
alkaline solution
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CN109427930A (en
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季静佳
覃榆森
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Sharesun Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
    • C30B33/08—Etching
    • C30B33/10—Etching in solutions or melts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
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    • 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
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    • 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
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Abstract

The invention discloses a method for preparing a textured surface by performing chemical solution corrosion on the surface of a crystal silicon wafer. The method for preparing the texture surface by performing the chemical solution corrosion on the surface of the crystal silicon wafer disclosed by the invention is different from the method for directly adding the texture surface making additive into the chemical corrosion texture surface making solution which is commonly adopted at present, and the texture surface making additive is coated on the surface of the crystal silicon wafer to be textured before the step of preparing the texture surface by performing the chemical solution corrosion on the crystal silicon wafer. The texturing additive coated on the surface of the crystal silicon wafer does not react with the crystal silicon wafer, then the chemical corrosion solution wets the surface of the crystal silicon wafer coated with the texturing additive, and the step of preparing the texture surface by chemical corrosion is carried out on the surface of the crystal silicon wafer.

Description

Method for selectively preparing suede on surface of crystal silicon wafer
Technical Field
The invention relates to a technology for preparing a solar cell, in particular to a method for preparing a textured surface on the surface of a crystalline silicon wafer by chemical solution corrosion. The method for preparing the suede by chemical solution corrosion on the surface of the crystal silicon wafer has the characteristic of selectively implementing chemical solution corrosion on certain specific areas of the surface of the crystal silicon wafer to prepare the suede, and is particularly suitable for being applied to preparing solar cells with high photoelectric conversion efficiency.
Background
The texture surface on the surface of the crystal silicon wafer plays an important role in improving the photoelectric conversion efficiency of the solar cell. The texture is a series of regular or irregular surface shapes with different heights and sizes formed on the surface of a crystal silicon wafer. When sunlight is incident to the surface of the crystal silicon wafer with the textured surface, reflected light of the sunlight can generate the effect of secondary or multiple incidence between the textured surfaces on the surface of the crystal silicon wafer. In other words, the texture surface on the surface of the crystalline silicon wafer can improve the absorption of the solar cell to sunlight, thereby improving the photoelectric conversion efficiency of the crystalline silicon solar cell.
There are various methods for preparing a textured surface on the surface of a crystalline silicon wafer, such as a chemical solution etching texturing method, a plasma etching texturing method, a laser etching texturing method, and the like. The method for preparing the texture on the surface of the crystal silicon wafer, which is most widely applied in industrial production, is a method for preparing the texture by corroding the surface of the crystal silicon wafer with a chemical solution, namely a chemical solution corrosion texture-making method. The chemical solution etching texturing method is a method for etching crystalline silicon by using a chemical solution to generate a textured surface on the surface of the crystalline silicon. For example, the textured surface on the surface of a monocrystalline silicon wafer is generally formed by etching the monocrystalline silicon wafer with an alkaline chemical solution, while the textured surface on the surface of a polycrystalline silicon wafer is generally formed by etching with an acidic solution.
In industrial production, various texturing additives are generally added into an alkaline chemical etching solution or an acidic chemical etching solution in order to improve the quality of the textured surface on the surface of the crystalline silicon wafer. For example, EP0477424a1 discloses a texturing additive which is an alkaline polyethylene glycol solution and which, when added to a chemically aggressive texturing solution, helps to produce a texture of small and uniform texture size. CN2011102128769 discloses another texturing additive, which is added into an acidic chemical etching solution, and a polycrystalline silicon wafer is etched by the chemical etching solution containing the texturing additive, so that a smaller and more uniform textured surface can be generated on the surface of the polycrystalline silicon wafer. In the texturing step of the present mass production of crystalline silicon solar cells, various types of texturing additives have been commonly used.
Although the texture quality of the surface of the crystalline silicon wafer is remarkably improved after various texture additives are used, the stability of the texture quality of each batch still has large fluctuation. The reason is that the texture quality of the surface of the crystal silicon wafer after being etched and textured by the chemical solution not only depends on the texturing additive, but also is related to other texturing conditions. For example, the effective content of the texturing additive in the etching solution and the content of the sodium silicate which is an etching product are changed along with the texturing reaction, so that the texture quality of the surface of the crystal silicon wafer is changed. In order to ensure the stability of the quality of the suede, the suede making process must be continuously adjusted according to the specific conditions of the suede making result of each batch in the suede making production. This not only makes the texturing operation difficult, but also fails to maintain the consistency of the textured surface on the surface of the textured silicon wafer in each batch, which is not favorable for the stability of the production.
With the continuous and deep research on improving the photoelectric conversion efficiency of the crystalline silicon solar cell, a new challenge is also provided for the texturing process. For example, it has been found that the photoelectric conversion efficiency of a crystalline silicon solar cell can be improved if a texturing process is performed only on the light receiving surface of the crystalline silicon solar cell or the main light receiving surface of the crystalline silicon solar cell while maintaining a flat surface on the other surface thereof. In order to achieve the effect that one surface of a crystal silicon wafer has a textured surface and the other surface of the crystal silicon wafer has a smooth surface, the current method is to simultaneously texture two surfaces of the crystal silicon wafer and then polish one surface of the crystal silicon wafer. Obviously, this method increases the complexity of production.
Disclosure of Invention
Aiming at the defects of the prior art, the invention discloses a method for preparing a suede surface by chemical etching on the surface of a crystalline silicon wafer.
One of the objectives of the present invention is to find a method for preparing a textured surface on a crystalline silicon wafer surface by chemical solution etching, which can improve the stability of the texturing process.
Another object of the present invention is to find a method for preparing a textured surface on a surface of a crystalline silicon wafer by chemical solution etching, which can meet the requirements for preparing a high-efficiency solar cell, and can perform selective texturing on the surface of the crystalline silicon wafer.
The last purpose of the invention is to find a method for preparing the texture surface on the surface of the crystalline silicon wafer by chemical solution corrosion, which can be applied to the production of all crystalline silicon solar cells, including single crystal silicon solar cells, quasi-single crystal silicon solar cells, polycrystalline silicon solar cells, n-type crystalline silicon solar cells and p-type crystalline silicon solar cells, and the application range of the invention is expanded.
In order to realize the purpose, the invention discloses a method for preparing a textured surface by carrying out chemical solution corrosion on the surface of a crystal silicon wafer. The method for preparing the texture surface by performing the chemical solution corrosion on the surface of the crystal silicon wafer disclosed by the invention is different from the method for directly adding the texture surface making additive into the chemical corrosion texture surface making solution which is commonly adopted at present, and the texture surface making additive is coated on the surface of the crystal silicon wafer to be textured before the step of preparing the texture surface by performing the chemical solution corrosion on the crystal silicon wafer. The texturing additive coated on the surface of the crystal silicon wafer does not react with the crystal silicon wafer, then the chemical corrosion solution wets the surface of the crystal silicon wafer coated with the texturing additive, and the step of preparing the texture surface by chemical corrosion is carried out on the surface of the crystal silicon wafer.
The method for preparing the suede by carrying out chemical solution corrosion on the surface of the crystal silicon wafer comprises the following steps of:
1) coating a texturing additive on the surface of a crystal silicon wafer needing to prepare a textured surface;
2) and contacting the surface of the crystal silicon wafer coated with the texturing additive with a chemical etching solution, and etching the surface of the crystal silicon wafer by using the chemical etching solution to prepare the textured surface.
The texturing additive is obviously not a reactant for corroding the silicon wafer by a chemical corrosion solution, or the texturing additive does not appear in a reaction equation for corroding the silicon wafer by the chemical corrosion solution. Such as hydroxide ion (OH) in alkaline etching solution reaction-) Hydrofluoric acid (HF), various oxidation (nitric acid, hydrogen peroxide and the like) and various metal elements in metal induced corrosion reaction in the acid corrosion solution reaction all belong to reactants for corroding the silicon wafer by the chemical corrosion solution, and do not belong to the category of the texturing additive.
The texturing additives of the present invention are also often referred to as texturing promoters, or by other names. The texturing additive provided by the invention has the effects of improving the uniformity of a textured surface generated on the surface of a crystal silicon wafer and reducing the reflectivity. Furthermore, other functions of the texturing additive provided by the invention include shortening texturing time on the surface of a crystal silicon wafer, reducing the dosage of chemicals, reducing the cost of chemicals, improving the production stability and the like.
The method for preparing the texture surface on the surface of the crystalline silicon wafer by chemical corrosion has the advantages that the texture surface making additive is directly coated on the surface of the crystalline silicon wafer before the texture surface is prepared by chemical corrosion on the surface of the crystalline silicon wafer, so that in the subsequent step of preparing the texture surface by chemical corrosion, the coated texture surface making additive can be directly generated on the surface of the crystalline silicon wafer and can rapidly play a role in promoting the texture surface making, and the texture surface making additive is effectively utilized.
In the process of preparing the texture surface by chemical corrosion on the surface of the crystal silicon wafer, the quality and the uniformity of the texture surface generated on the surface of the crystal silicon wafer are related to the concentration of the texture surface additive on the surface of the crystal silicon wafer. Because the texturing additive is coated on the surface of the crystal silicon wafer, the concentration of the texturing additive on the surface of all the crystal silicon wafers can be easily kept consistent in the whole production process in the texturing step of the method for preparing the textured surface by chemical corrosion on the surface of the crystal silicon wafer, and the guarantee is provided for stable production.
In some cases, the texturing additive is easily ineffective in some chemical etching solutions, which results in the disadvantages of unstable production and high production cost due to the excessive use of the texturing additive. Therefore, the invention has another advantage that the texturing additive is not directly added into the chemical etching solution, so that the texturing additive with the same concentration can be ensured to exist on the surface of each crystal silicon wafer, and the production stability is ensured.
The method for preparing the suede by the chemical corrosion on the surface of the crystalline silicon wafer has the advantages that the suede preparation additive is coated on the surface of the crystalline silicon wafer, and the reaction of generating the suede on the surface of the crystalline silicon wafer can be instantly carried out when the crystalline silicon wafer is contacted with the solution for preparing the suede by the chemical corrosion, so that the method for preparing the suede by the chemical corrosion on the surface of the crystalline silicon wafer has the another advantage of reducing the corrosion amount of the crystalline silicon wafer. The thinning amount of the crystal silicon wafer in the process of preparing the texture surface by chemical corrosion is reduced, namely, the consumption of chemicals in a corrosion solution is reduced, and the production cost of the texture surface making step is reduced. Meanwhile, the time for preparing the suede by chemical corrosion is shortened, the capacity of equipment is increased, or the investment cost of the equipment is reduced.
The preparation method of the texture of the crystalline silicon solar cell has the outstanding advantages that the texture can be generated on the local surface area of the crystalline silicon wafer, and the texture is not generated on other surface areas. Because the texturing additive is directly coated on the surface of the crystal silicon wafer, the effect of the texturing additive can be quickly exerted on the area of the crystal silicon wafer coated with the texturing additive in the step of preparing the textured surface by chemical corrosion, and the textured surface is quickly generated on the area. On the area which is not coated with the texturing additive, the generation of the textured surface is very slow, and the effect of preparing the textured surface by local chemical corrosion is achieved. For example, the invention can easily realize the purpose of texturing one surface of a crystal silicon wafer, namely achieving the purpose of single-side texturing.
A further advantage of the present invention is that the chemical etching method of making a textured surface of the present invention can expand the selection range of texturing additives. For example, some texturing additives have a problem of low solubility in the chemical etching solution used to chemically etch the prepared texture surface, and cannot function as their texturing additives in the chemical etching solution. As the texturing additive is not added into the chemical etching solution in the method for preparing the textured surface on the surface of the crystal silicon wafer, the texturing additive can well play a role in the step of preparing the textured surface by chemical etching provided that the texturing additive can be uniformly covered on the surface of the crystal silicon wafer. For another example, some texturing additives react rapidly with the chemical solution used to chemically etch the textured surface and lose the effectiveness of the texturing additive. After the method of the invention is adopted, the texturing additives can play a role rapidly in the step of preparing the textured surface by chemical corrosion, so as long as the reaction time of the texturing additives and the chemical solution for preparing the textured surface by chemical corrosion is longer than the texturing time, the texturing additives can still play a good role in promoting the texturing in the method for preparing the textured surface by chemical corrosion.
Drawings
FIG. 1 is a schematic representation of a dip-coated texturing additive of the present invention.
FIG. 2 is a schematic representation of a spray-coated texturing additive of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings. It is to be understood that this description is not intended to limit the invention. Various other corresponding combinations, alterations, and modifications may be made in accordance with the present invention by those skilled in the art without departing from the spirit and substance of the invention. Such corresponding combinations, variations and modifications are intended to be within the scope of the appended claims.
The method for preparing the texture surface on the surface of the crystal silicon wafer by chemical corrosion is to coat the texture surface additive on the surface of the crystal silicon wafer needing to be prepared with the texture surface before preparing the texture surface by chemical corrosion. In some embodiments, the manner of applying the texturing additive may be dip coating the texturing additive. In the step of coating the texturing additive by the dipping method, referring to fig. 1, the texturing additive 30 is filled into the texturing additive tank 20, and the crystalline silicon wafer 10 is placed into the texturing additive tank 20, so that the texturing additive 30 submerges and wets the surface of the crystalline silicon wafer 10. Thus, when the crystalline silicon wafer 10 is removed from the texturing additive tank 20, the texturing additive 30 is coated on the surface of the crystalline silicon wafer 10. The step of soaking and coating the texturing additive in the method for preparing the suede on the surface of the crystalline silicon wafer by chemical corrosion can be vertical soaking shown in the attached figure 1, and the step of coating the texturing additive can also be implemented by adopting a horizontal soaking method.
In other embodiments of the method for preparing the textured surface on the surface of the crystalline silicon wafer by chemical etching of the surface of the crystalline silicon wafer according to the present invention, a method of spraying the texturing additive 30 on the surface of the crystalline silicon wafer may be used. Referring to fig. 2, a texturing additive 30 is placed in a texturing additive tank 20, and the texturing additive 20 is sprayed on the surface of the crystalline silicon wafer 10 through a texturing additive spray head 40 by a liquid level difference or a pressure difference. In some embodiments, the additive wool tip 40 may be comprised of one or more holes, or jets. In the embodiment of the method for preparing the texture surface on the surface of the crystalline silicon wafer by chemical etching, in order to achieve the purpose of uniform coating, the crystalline silicon wafer 10 may be moved while spraying the texture-making additive, and the nozzle 40 of the texture-making additive may also be moved.
In other embodiments of the method for preparing textured surfaces on the surface of a crystalline silicon wafer by chemical etching, the texturing additive 30 may be applied to the surface of the crystalline silicon wafer by spin coating. The advantage of applying the texturing additive 30 to the surface of the crystalline silicon wafer by spin coating is that the texturing additive 30 can be uniformly applied to the surface of the crystalline silicon wafer. Another advantage of the spin coating method is that the applied texturing additive can be dried relatively quickly on the surface of the crystalline silicon wafer after the spin coating process is completed.
In other embodiments, other coating methods may be used to perform the additive-applying step of the present invention, for example, screen printing may be used to apply the texturing additive to the surface of the crystalline silicon wafer. The texturing additive 30 can also be coated on the surface of the crystalline silicon wafer by adopting a method of ultrasonically atomizing the texturing additive 30. The use rate of the texturing additive 30 can be improved by coating the texturing additive 30 on the surface of the crystalline silicon by adopting an ultrasonic atomization method, and the uniformity of the coating of the texturing additive 30 can also be improved.
The texturing additive 30 of the method for preparing the textured surface on the surface of the crystalline silicon wafer by chemical corrosion can be various compounds capable of promoting the generation of the required textured surface on the surface of the crystalline silicon wafer. In the texturing additive, one or more compounds are contained. The additive has the function of enabling the texturing process to be controlled more easily; the size of the prepared suede is more uniform; the size of the suede is smaller; the reflectivity of the crystal silicon wafer is lower; the conditions of the texturing production are easier to control and stabilize; and more favorable for surface cleaning. In summary, a texturing additive is a mixture of one or more compounds that can improve the texturing effect and the texturing process. Alternatively, the texturing additive is a compound that contributes to the improvement of the quality of the texture on the surface of the crystalline silicon, such as the reduction of the size of the texture, the improvement of the uniformity of the texture, the reduction of the reflectance, and the like, or a compound that contributes to the texturing production, such as the reduction of the texturing time, the reduction of the amount of chemicals used, the reduction of the chemical cost, the improvement of the production stability, and the like.
The step of coating the texturing additive on the surface of the crystal silicon wafer in the method for preparing the textured surface on the surface of the crystal silicon wafer by chemical corrosion can be coating the texturing additive. In other applications, more than one texturing additive may be applied. For example, in some applications of the present invention, special compounds are required to adsorb the texturing additive onto the surface of the crystalline silicon wafer to ensure that the texturing additive will function as the texturing additive to the greatest extent possible when the chemical solution corrodes the crystalline silicon. In these applications of the present invention, two or more texturing additives must be applied. When more than one texturing additive is applied, the step of applying the additive may be more than one step of applying the texturing additive.
The method for preparing the texture surface on the surface of the crystalline silicon wafer by chemical corrosion is suitable for all types of crystalline silicon wafers, such as monocrystalline silicon wafers, polycrystalline silicon wafers and cast monocrystalline silicon wafers. Further, these types of wafers may be p-type wafers, such as boron doped wafers, or n-type wafers, such as phosphorous doped wafers.
The crystalline silicon wafer 10 on which the texturing additive coating step of the method for producing a textured surface by chemical etching of the surface of a crystalline silicon wafer according to the present invention is carried out may be a virgin silicon wafer, for example, a virgin silicon wafer directly purchased from a silicon wafer supplier. Not only remains the damaged layer produced during the dicing process, but also some uncleaned chemical contaminants, such as cutting lubricants, may remain more or less on the surface of these original wafers.
In some embodiments of the present invention, the crystalline silicon wafer 10 may be a raw silicon wafer after chemical pretreatment. For example, the original silicon wafer may be first subjected to a chemical pre-soaking treatment, and then the step of coating the texturing additive in the method for preparing the textured surface by chemical etching on the surface of the crystalline silicon wafer according to the present invention is performed. In mass production practice, the purpose of chemical incipient bath silicon wafers is to clean chemical contaminants, such as some organic chemical contaminants, remaining on the original silicon wafer. The chemical primary soaking step is carried out before the textured surface is prepared on the surface of the crystalline silicon wafer, so that the surface of the crystalline silicon wafer does not contain any pollutant after the textured surface is prepared, and various spots formed on the surface of the crystalline silicon can be avoided.
In other embodiments of the present invention, the chemically pretreated crystalline silicon wafer 10 may be a crystalline silicon wafer after cleaning a damaged layer on the surface of the crystalline silicon wafer generated in the cutting process, that is, an original silicon wafer is first chemically treated by cleaning the damaged layer, and then the step of coating the texturing additive in the method for preparing the textured surface by chemical etching on the surface of the crystalline silicon wafer according to the present invention is performed. When the method for preparing the texture surface by chemical corrosion on the surface of the crystal silicon wafer is applied to the crystal silicon wafer after the damaged layer is removed, the texture-making time can be obviously shortened when the texture-making step of the method for preparing the texture surface by chemical corrosion on the surface of the crystal silicon wafer is implemented.
In other embodiments of the present invention, the chemically pretreated crystalline silicon wafer 10 may be a chemically polished crystalline silicon wafer, that is, an original silicon wafer is first chemically polished, and then the step of coating the texturing additive in the method for preparing the textured surface on the surface of the crystalline silicon wafer by chemical corrosion according to the present invention is performed. When the method for preparing the suede by chemical corrosion on the surface of the crystal silicon wafer is applied to the crystal silicon wafer after chemical polishing, the suede with the size of about 1 micron and very uniform suede can be prepared on the surface of the crystal silicon wafer after the suede making step of the method for preparing the suede by chemical corrosion on the surface of the crystal silicon wafer is implemented.
The crystalline silicon wafer 10 may also be a crystalline silicon wafer after the original silicon wafer has undergone some physical treatment. For example, in order to reduce the surface reflectivity of the polycrystalline silicon wafer after the textured surface is prepared, the texturing additive coating step of the method for preparing the textured surface by chemical etching on the surface of the crystalline silicon wafer can be performed with laser treatment to increase the surface roughness of the polycrystalline silicon wafer. These increased surface roughness can effectively reduce the reflectivity of the surface of the polycrystalline silicon wafer after texturing is performed.
The crystalline silicon wafer 10 prior to the step of applying the texturing additive in the method of producing a textured surface by chemical etching of a surface of a crystalline silicon wafer according to the present invention may be dried, for example, a raw silicon wafer without any pretreatment. Or a crystalline silicon wafer dried after a pretreatment, for example, a chemical preliminary soaking and drying.
In other embodiments of the present invention, the crystalline silicon wafer 10 before the step of applying the texturing additive in the method of preparing the textured surface by chemical etching on the surface of the crystalline silicon wafer according to the present invention may be wet without being dried, for example, after the crystalline silicon wafer is subjected to chemical initial soaking and deionized water washing, the step of applying the texturing additive in the method of preparing the textured surface by chemical etching on the surface of the crystalline silicon wafer according to the present invention may be directly performed.
One of the advantages of the method for preparing the textured surface by chemically etching the surface of the crystalline silicon wafer is that the textured surface can be prepared on the local surface of the crystalline silicon wafer 10. As shown in fig. 2, after the step of coating the texturing additive on the crystalline silicon wafer 10 by the method for preparing the textured surface by chemical etching on the surface of the crystalline silicon wafer according to the present invention, the texturing additive is coated only on the upper surface of the crystalline silicon wafer 10. If the lower surface of the crystal silicon wafer 10 is not coated with the texturing additive, the optimized texturing step of the method for preparing the textured surface by chemical corrosion on the surface of the crystal silicon wafer can ensure that the process of preparing the textured surface by chemical corrosion only occurs on the upper surface, namely only the upper surface of the crystal silicon wafer 10 is provided with the textured surface.
Further, the method for preparing the textured surface by chemical etching of the surface of the crystalline silicon wafer of the present invention can also prepare the textured surface on a specific area on one surface of the crystalline silicon wafer 10. For example, the present invention may apply the texturing additive 30 only on certain areas of the upper surface of the crystalline silicon wafer 10 that need to be textured. The optimized texturing step of the method for preparing the textured surface on the surface of the crystalline silicon wafer by chemical corrosion can ensure that the process of preparing the textured surface by chemical corrosion only occurs in the areas of the upper surface of the crystalline silicon wafer 10 coated with the texturing additive.
After the step of coating the texturing additive in the method for preparing the textured surface by chemical corrosion on the surface of the crystalline silicon wafer is implemented, the step of preparing the textured surface by chemical corrosion in the method for preparing the textured surface by chemical corrosion on the surface of the crystalline silicon wafer is implemented. In some embodiments of the present invention, the texturing additive 30 on the surface of the crystalline silicon wafer 10 may be dried first. In other embodiments, the chemical etching texturing step of the method for producing textured surfaces by chemical etching of the surface of a crystalline silicon wafer according to the present invention is performed directly after the step of applying a texturing additive.
According to the characteristics of the crystalline silicon wafer 10 and the characteristics of the texturing additive 30, and in combination with different requirements on various textured surfaces, the step of preparing the textured surface by chemical etching in the method for preparing the textured surface by chemical etching on the surface of the crystalline silicon wafer can adopt alkaline solution to implement chemical etching to prepare the textured surface, and also can adopt acidic solution to implement chemical etching to prepare the textured surface. For example, the chemical etching of the invention is used to prepare the suede on the surface of the monocrystalline silicon piece and the surface of the quasi-monocrystalline silicon piece by using alkaline chemical solution. In the step of preparing the suede by alkaline chemical etching, inorganic alkali can be adopted, and organic alkali can also be adopted. The temperature for preparing the suede by optimized alkaline solution chemical corrosion is between 60 ℃ and 100 ℃. The alkali concentration in the alkaline solution for preparing the suede by optimized alkaline solution chemical corrosion is between 0.5% and 5%. The optimized chemical corrosion time of the alkaline solution for preparing the suede is between 5 minutes and 30 minutes.
In some embodiments of the present invention, various other additives may be added to the alkaline solution for preparing the suede by chemical etching in the alkaline solution, for example, 1% to 10% of isopropanol may be added to the alkaline solution, depending on the specific implementation conditions.
The step of preparing the suede surface by chemical corrosion of the method for preparing the suede surface by chemical corrosion of the surface of the crystal silicon wafer can also adopt acid solution to carry out chemical corrosion to prepare the suede surface. For example, a mixed acid solution of nitric acid and hydrofluoric acid may be used.
The step of preparing the suede surface by chemical corrosion of the method for preparing the suede surface by chemical corrosion of the surface of the crystal silicon wafer can adopt a method for preparing the suede surface by slot time gap. In the method for preparing the textured surface in the groove type gap, the crystal silicon wafer 10 is normally vertically soaked in the solution for preparing the textured surface by chemical corrosion, and the step of preparing the textured surface by chemical corrosion is completed. The step of preparing the suede surface by chemical corrosion of the method for preparing the suede surface by chemical corrosion of the surface of the crystal silicon wafer can also adopt a method for horizontally and continuously preparing the suede surface. In the method of continuously fabricating the texture, the crystalline silicon wafer 10 is generally subjected to a solution for fabricating the texture by chemical etching under the transportation of various transport means such as various rollers, thereby completing the step of fabricating the texture by chemical etching.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
Example 1
First, the original p-type monocrystalline silicon wafer is subjected to initial soaking in order to clean organic contaminants and a part of a damaged layer remaining during slicing and packaging. The monocrystalline silicon piece is washed by deionized water after initial soaking, then a texturing additive (such as alkaline polyethylene glycol) is coated on the surface of the silicon piece by adopting a soaking method, the silicon piece is horizontally placed, the upper surface of the silicon piece is constantly wetted by a 1.5 percent sodium hydroxide chemical etching solution which is mixed with a proper amount of IPA and has the temperature of 80 ℃, and the step of carrying out chemical etching on the crystalline silicon piece to prepare the textured surface horizontal texturing is carried out. After 20 minutes, the process of preparing the texture surface by chemically corroding the crystal silicon wafer is finished. After cleaning and blow-drying, the average size of the pyramid textured surface measured on the upper surface of the crystal silicon wafer is 2 microns, the average reflectivity of the upper surface is 10.2%, and the average reflectivity of the lower surface is 20.5%.
Example 2
A texturing additive (such as alkaline polyethylene glycol) is arranged on a light receiving area of a silicon wafer by adopting an ink-jet printing method, so that the electrode area of the silicon wafer is free of the texturing additive, the silicon wafer is placed into a mixed solution of 4% tetramethyl ammonium hydroxide and a proper amount of IPA at the temperature of 80 ℃ after the texturing additive is dried, and after 10 minutes, the process of preparing the textured surface by carrying out chemical corrosion on the crystal silicon wafer is finished. After cleaning and blow-drying, the average size of the pyramid matte measured on the area of the upper surface of the crystalline silicon wafer coated with the texturing additive was 1 micron, and the average size of the pyramid matte on the crystalline silicon surface not covered with the texturing additive was 5 microns.
Example 3
The step of coating the texturing additive on the surface of the crystalline silicon wafer according to the present invention is performed by spin-coating the texturing additive (e.g., a mixture of PEG200 and polyvinylpyrrolidone) on the upper surface of the p-type polycrystalline silicon wafer. After the upper surface of the crystal silicon wafer is coated with the texturing additive, the crystal silicon wafer is directly put into continuous acid solution chemical corrosion texturing equipment without any treatment, and the horizontal texturing step of preparing the textured surface by carrying out chemical corrosion on the crystal silicon wafer is implemented. The conditions of continuous acid solution chemical corrosion are hydrofluoric acid: nitric acid: water = 1: 4: 3, the etching temperature is 5 ℃, and after 2 minutes, the process of preparing the texture surface by chemically etching the crystal silicon wafer is finished. After cleaning and blow-drying, the average reflectivity of the upper surface of the crystal silicon wafer is 20%, and the average reflectivity of the lower surface of the crystal silicon wafer is 23%.
Example 4
One surface of an original n-type polycrystalline silicon wafer is roughened by adopting a laser roughening technology, and then the roughened surface of the silicon wafer is subjected to the step of coating the texturing additive on the surface of the crystal silicon wafer. In this embodiment, the coating of the texturing additive is divided into two steps, in which triethanolamine is first coated on the surface of the crystalline silicon wafer by a spraying method, and polyvinyl alcohol is then coated on the triethanolamine by a spraying method. After the texturing additive is coated on the upper surface of the crystal silicon wafer, the crystal silicon wafer is dried by blowing, and then the crystal silicon wafer is put into continuous acid-soluble tank type chemical corrosion texturing equipment to implement the horizontal texturing step of preparing the textured surface by implementing chemical corrosion on the crystal silicon wafer. The chemical etching texturing equipment contains hydrofluoric acid: nitric acid: water = 1: 4: 2.5, the corrosion temperature is 5 ℃, and after 2 minutes, the process of preparing the suede by chemically corroding the crystal silicon wafer is finished. After cleaning and blow drying, the average reflectance was measured at the roughened surface of the wafer to be 15%, and the reflectance at the other surface of the wafer to be 26%.

Claims (11)

1. A method for preparing a suede by performing alkaline solution corrosion on the surface of a crystal silicon wafer is characterized in that a suede making additive is coated on the surface of the crystal silicon wafer before the step of preparing the suede by performing alkaline solution corrosion on the surface of the crystal silicon wafer, and comprises the following steps:
(1) coating a texturing additive on the surface of the crystal silicon wafer;
(2) and performing alkaline solution corrosion on the surface of the crystal silicon wafer to prepare a suede.
2. The method for preparing a textured surface by alkaline solution etching of the surface of a crystalline silicon wafer as claimed in claim 1, wherein the texturing additive is used as a texturing additive which contributes to the improvement of the quality of the textured surface of the crystalline silicon wafer and the texturing production in the subsequent step of preparing the textured surface by alkaline solution etching.
3. The method of claim 1, wherein the texturing additive is applied to at least a portion of the entire surface area of the wafer.
4. The method for preparing a textured surface by subjecting the surface of a crystalline silicon wafer to alkaline solution etching according to claim 1, wherein the texturing additive contains at least one compound, and the step of applying the texturing additive to the surface of the crystalline silicon wafer is at least one application step.
5. The method for preparing a textured surface by performing alkaline solution etching on the surface of a crystalline silicon wafer according to claim 1, wherein the coating method used in the step of coating the texturing additive on the surface of the crystalline silicon wafer is a method of coating the texturing additive on all the surfaces of the crystalline silicon wafer by a soaking method; the texturing additive is applied to a portion of the surface of the crystalline silicon wafer by either spray coating, spin coating, or printing, or a combination of these coating techniques.
6. The method for preparing a textured surface by performing alkaline solution etching on the surface of a crystalline silicon wafer as claimed in claim 1, wherein the surface of the crystalline silicon wafer is dried or is not dried before the step of coating the texturing additive on the surface of the crystalline silicon wafer.
7. The method for preparing a textured surface by subjecting the surface of a crystalline silicon wafer to alkaline solution etching as set forth in claim 1, wherein a drying step is performed on the texturing additive after the step of applying the texturing additive on the surface of the crystalline silicon wafer, or the drying step is not performed on the texturing additive.
8. The method for preparing a textured surface by performing alkaline solution etching on the surface of a crystalline silicon wafer as claimed in claim 1, wherein the crystalline silicon wafer is an original crystalline silicon wafer or a crystalline silicon wafer subjected to various pretreatment steps including chemical solution pre-cleaning, chemical solution cleaning of a damaged layer, chemical solution polishing, laser roughening, or mechanical roughening, before the step of coating the texturing additive on the surface of the crystalline silicon wafer.
9. The method for preparing a textured surface by performing alkaline solution etching on the surface of a crystalline silicon wafer according to claim 1, wherein the crystalline silicon wafer is a crystalline silicon wafer for producing a solar cell.
10. The method for preparing the textured surface by performing the alkaline solution etching on the surface of the crystalline silicon wafer as claimed in claim 1, wherein the alkaline solution for preparing the textured surface by the alkaline solution etching contains other additives.
11. The method for preparing the textured surface by performing the alkaline solution etching on the surface of the crystalline silicon wafer as claimed in claim 1, wherein the texture surface prepared by performing the alkaline solution etching is a texture surface prepared by performing the alkaline solution etching on the crystalline silicon surface in a groove type gap or a texture surface prepared by performing the alkaline solution etching on the crystalline silicon surface in a horizontal continuous manner.
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