Etching method for back face and edge diffusion layer of solar cell silicon wafer

Abstract

The invention discloses a back-face polishing and edge etching method of a solar cell silicon wafer. The method comprises the following steps of: A, corroding a mask protection layer; B, corroding a diffusion layer and performing polishment; and C, performing cleaning. Compared with prior art, the method has the advantages that a diffusion face is protected by means of a mask; with the adoption of immersed corrosion, a favorable edge etching effect is guaranteed; phosphorosilicate glass (or borosilicate glass) which is naturally formed due to diffusion is adopted in the protection layer, an extra mask preparation process is not required, and no cost is added; a chemical polishing effect on a back face is synchronously realized, so that the efficiency of a solar cell is substantially improved; a back-face polishing process is combined with a back-face passivation technique, the method has wide prospect; tolerance for equipment machinery precision is high, equipment fabrication cost is saved; and meanwhile, the process is stable and easy to control. The method is wide in application and can be applicable for both of N-type and P-type solar cells.

Description

technical field [0001] The invention relates to the field of solar cell manufacturing technology, in particular to a back polishing and edge etching method of a solar cell silicon chip. Background technique [0002] The status and shortcomings of today's mainstream wet etching methods: [0003] 1. Use the surface tension of the solution to make the silicon wafer float on the etching liquid surface to etch the back and edge, and then use HF to remove PSG. The disadvantage of this method is: because PSG is hydrophilic, when the silicon wafer is floating, the hydrophilic PSG on the upper surface is easy to adsorb the solution to the upper surface, resulting in over-cutting, the effective working area of ​​the battery is reduced, and the performance of the product is affected. decline. Therefore, this method has high requirements on the mechanical precision of the equipment, and also has relatively high requirements on the stability of the exhaust air during use. [0004] 2. ...

AI Technical Summary

Problems solved by technology

The disadvantage of this method is: because PSG is hydrophilic, when the silicon wafer is floating, the hydrophilic PSG on the upper surface is easy to adsorb the solution to the upper surface, resulting in over-cutting, the effective working area of ​​the battery is reduced, and the performance of the product is affected. decline

The disadvantage of this method is: since the PSG is removed first, when the silicon wafer is subjected to the subsequent KOH porous silicon removal process, due to the lack of buffer protection of the PSG on the front side, the alkali solution will slightly corrode the PN junction, resulting in an uncontrollable rise in the square resistance. The situation has a great impact on the stability of the entire process

The disadvantage of this method is that the amount of liquid in the roller belt is limited, and it is easy to cause insufficient corrosion

The disadvantage of this method is that the process of forming a protective film or protective glue on the surface of the silicon wafer is a very expensive process, and it is often difficult to effectively remove the mask protective layer.