A method for polishing the back of a silicon wafer

Abstract

The invention discloses a silicon chip back-polishing method. The silicon chip back-polishing method comprises texture surface making, diffusion, etching, PECVD, screen printing and testing steps. When the texture surface making step is carried out, a primary back polishing step is carried out, after the primary back polishing step is carried out, an etching machine is used to carry out more than one time subsequent back polishing step, after the subsequent back polishing steps, conventional diffusion, etching, PECVD, screen printing and testing operations are carried out. According to the invention, two back polishing steps are superposed to form a good back polishing effect; the back reflectivity is greatly improved, and the cell performance is finally improved; in the subsequent multiple back polishing steps, the thickness reduction amount is reasonably adjusted, different degrees of back polishing effects are obtained, etching lines on edges are effectively reduced, the resistance value of the square resistor does not rise too high, the case that when the silicon chip passes through an alkaline tank, the silicon chip reacts with high-concentration alkali lye and is not stable is avoided, at the same time, the alkaline tank passing time is prolonged, and the polishing effect is further enhanced.

Description

technical field [0001] The invention relates to a method for producing a crystalline silicon solar cell, in particular to a method for polishing the back of a silicon wafer. Background technique [0002] At present, there are many ways to improve the efficiency of crystalline silicon solar cells with p-type substrates. Back polishing is an important method. The long-wave response of the battery can be significantly improved by back polishing, and the battery performance such as Voc, Isc, and Eta can be improved. [0003] The back polishing of the existing conventional production line is mainly completed in the etching stage, and it is difficult to achieve the effect of back polishing. Some equipment can obtain a higher back reflectivity through a large amount of etching, but requires a higher concentration of mixed acid. A higher concentration of mixed acid is prepared in the etching tank. This method can form a relatively high amount of backside etching, thereby obtaining...

AI Technical Summary

Problems solved by technology

[0003] The back polishing of the existing conventional production line is mainly completed in the etching stage, and it is difficult to achieve the effect of back polishing. Some equipment can obtain a higher back reflectivity through a large amount of etching, but requires a higher concentration of mixed acid. A higher concentration of mixed acid is prepared in the etching tank. This method can form a relatively high amount of backside etching, thereby obtaining a certain polishing effect, but a high concentration of acid mist will be formed during this process, and it is difficult to control the etching of the edge. The square resistance of the wire and the phosphorus-silicate glass is removed. At the same time, it is difficult to further increase the corrosion amount due to the concentration ratio, and the polishing effect is limited.