Polycrystalline silicon wafer texturing auxiliary and application method thereof

Abstract

The invention provides a polycrystalline silicon wafer texturing auxiliary and an application method thereof. The auxiliary comprises a silver inducer, an oxidizing agent, a buffering agent, a dispersing agent and deionized water. The auxiliary is added to a traditional isotropic texturing liquid composed of mixed liquor of hydrofluoric acid and nitric acid, then a polycrystalline silicon wafer is immersed in the texturing liquid, and isotropic corrosion and anisotropic corrosion occur on the surface of the silicon wafer, thereby obtaining a silicon surface with coexisting isoropic corrosion pits whose reflectivity is lower than 10% and anisotropic inverted pyramid morphology. The function of the buffering agent is to maintain the stability of a PH value of the texturing liquid; the oxidizing agent can suppress anisotropic corrosion of the silver inducer, thereby avoiding formation of too deep holes; and the dispersing agent can avoid the ''raindrop'' defect, and also wraps nano-silver particles attached to the surface of the silicon wafer, thereby substantially reducing cleaning difficulty of the silicon wafer after texturing. The polycrystalline silicon wafer texturing auxiliary provided by the invention overcomes some deficiencies of existing polycrystalline silicon texturing methods, and is particularly suitable for texturing of a polycrystalline silicon wafer cut by diamond wires.

Description

technical field [0001] The invention relates to the technical field of solar cells, in particular to a polycrystalline silicon wafer texturing auxiliary agent and an application method thereof. Background technique [0002] Due to the existence of grains with multiple orientations on polycrystalline silicon wafers, isotropic acid etching is generally used to prepare the textured surface to reduce the surface reflectivity, but there are three problems in this method: 1) The surface reflectivity of the silicon wafer after texture is high, and the reflection The corrosion rate is generally above 20%, which severely restricts the photoelectric conversion efficiency of polycrystalline silicon solar cells; 2) The reaction solution needs to be cooled to below 10°C during the texturing process. Since the corrosion reaction is a violent exothermic reaction, the energy consumption of this method is very large ; 3) This texturing method is only suitable for polysilicon wafers obtaine...

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Problems solved by technology

[0002] Due to the existence of grains with multiple orientations on polycrystalline silicon wafers, isotropic acid etching is generally used to prepare the textured surface to reduce the surface reflectivity, but there are three problems in this method: 1) The surface reflectivity of the silicon wafer after texture is high, and the reflection The corrosion rate is generally above 20%, which severely restricts the photoelectric conversion efficiency of polycrystalline silicon solar cells; 2) The reaction solution needs to be cooled to below 10°C during the texturing process. Since the corrosion reaction is a violent exothermic reaction, the energy consumption of this method is very large ; 3) This texturing method is only suitable for polysilicon wafers obtained by mortar cutting, and diamond wire cutting is a more economical and environmentally friendly method, which is bound to replace the traditional mortar cutting method. There are few and shallow cutting defects on the surface of polysilicon wafers, and the traditional acid etching method cannot obtain a surface with qualified reflectivity. It is for this reason that diamond wire-cut polysilicon wafers have not been widely used in cell manufacturers

[0003] Patent CN101800264A mentions the method of preparing polysilicon textured surface by dry plasma etching. Although a lower surface reflectivity can be obtained, the surface of the silicon wafer is easily damaged by plasma bombardment, and subsequent treatment is required. Otherwise, the surface of the silicon wafer will be seriously compounded and c

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