A kind of wet etching method of silicon solar cell and the water film solution used therefor

Abstract

The invention discloses a wet etching method of a silicon solar cell. The wet etching method of the silicon solar cell comprises the following steps: (1) water film protecting step: forming a water film protecting layer on a diffusion surface of a silicon wafer by using a water film solution, wherein the water film protecting layer always exists until etching of the silicon is finished, the concentration of H+ ions in the water film solution is greater than 10-7 mol / L, and the viscosity of the water film solution is greater than that of water under equal conditions; and (2) etching step: feeding the silicon wafer in an etching module, and etching PN junctions on the back surfaces and edges, wherein in the etching module, the silicon wafer floats on etching liquid when etched. By the wet etching method of the silicon solar cell, the etching amount of acid etching is greatly improved; and the wet etching method can be used on existing equipment and technological processes, and unexpected effects are achieved.

Description

Technical field [0001] The invention relates to a wet etching method for a silicon solar cell and a water film solution used therein, and belongs to the technical field of solar cells. Background technique [0002] Conventional fossil fuels are increasingly depleted. Among the existing sustainable energy sources, solar energy is undoubtedly the cleanest, most common and most potential alternative energy source. Solar power generation devices are also called solar cells or photovoltaic cells, which can directly convert solar energy into electrical energy. The power generation principle is based on the photovoltaic effect of semiconductor PN junction. Among them, silicon solar cells have been widely used due to abundant silicon reserves. [0003] At present, in the production of silicon solar cells, there are three main wet etching methods used: (1) The first method is to increase the surface tension of the solution by adding concentrated sulfuric acid to the etching bath to prevent...

AI Technical Summary

Problems solved by technology

[0005] However, it has been found in practical applications: (1) When etching or polishing with mixed acid, the high-concentration acid (such as HF, nitric acid, etc.) Dissolved in the water film, causing gas phase corrosion on the surface of the battery and destroying the PN junction on the surface; (2) The etching amount of general acid polishing can only reach 4~5 microns, resulting in unclean removal of the suede on the back of the silicon wafer, and polishing Problems such as surface unevenness are especially obvious for back passivated batteries, which will further affect the reflectivity of long-wavelength light and increase the back recombination

In order to remove the suede on the back of the silicon wafer to form a back polishing structure, a large amount of etching is required, and at the same time, the corrosion damage to the PN junction is further aggravated. A simple water film can no longer protect the front PN junction very well.

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