Etching and polishing method of single-crystal silicon wafer

Abstract

The invention discloses an etching and polishing method of a single-crystal silicon wafer. The method comprises the processes of etching, washing, alkali washing, acid washing, washing and drying, inwhich the alkali washing process comprises a polishing process and a spraying process which are performed in an alkali groove, a polishing part and a spraying part are arranged in the alkali groove, the polishing part comprises a plurality of rollers, a lower surface of the silicon wafer is polished by the plurality of rollers when the silicon wafer passes through the polishing part, the sprayingpart comprises a plurality of spraying heads, and an upper surface of the silicon wafer is processed by a normal-temperature alkali liquid sprayed from the plurality of spraying heads when the siliconwafer passes through the spraying part. The etching and polishing method is suitable for an etching and polishing process of the single-crystal silicon wafer; and a part of acid groove is substitutedby the alkali groove, thus, the problem of difficulty in acid mist treatment in the etching process is solved, the reflectivity of a back surface of the silicon wafer after etching is improved, the pressure of improving the reflectivity only by an etching groove is shared, and the cost of acid dosage is reduced.

Description

technical field [0001] The invention relates to the field of solar cell manufacturing, in particular to a method for polishing the back of a single crystal silicon wafer for improving the reflectivity and uniformity of the back of the silicon wafer. Background technique [0002] The etching and polishing process of solar cells is a crucial step in the manufacturing process of high-efficiency solar cells. It has a significant impact on the electrical properties of the finished cells and the EL yield rate. The uniformity of the back reflectivity of the silicon wafer after etching determines the The uniformity of the chemical coating, the uniformity of the coating determines the uniformity of the laser opening rate and size. Therefore, etching plays a pivotal role in the entire PERC cell (Passivated emitter rear contact solar cells) production process. [0003] Acid throwing is another relatively common technical means, but there are three problems with this treatment method: ...

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Problems solved by technology

[0003] Acid throwing is another relatively common technical means, but there are three problems with this treatment method: first, the high-concentration acid mist generated by acid throwing is difficult to deal with, and it is easy to cause environmental protection to fail to meet standards; second, acid throwing reflects The efficiency is difficult to improve, and the stability is poor; third, it is difficult to adjust during the acid throwing production process. If the exhaust air is not smooth, the acid mist will not be discharged, and the acid mist will remain in the equipment, which will not only corrode the equipment but also cause acid residue on the silicon wafer. After the finished battery is made, the EL black spot is serious, which reduces the qualified rate of the finished product and has a high rework rate; fourth, the cost of acid throwing is very high

[0004] Therefore, the uniformity of conventional etching back reflectivity is low and unstable, which can easily lead to poor uniformity of back passivation coating, uneven laser drilling, low conversion efficiency and etching; while alkali polishing has good uniformity, easy adjustment, reflection If the conventional etching and alkali polishing can be combined, the conversion efficiency of the finished cell can be better improved

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