Laser PN isolation process for back surface field of solar cell

Abstract

The invention discloses a laser PN isolation process for a back surface field of a solar cell. The process comprises steps as follows: front cleaning and texturing, diffusion, PN isolation, post cleaning, silicon nitride deposition with a plasma enhanced chemical vapor deposition method, screen printing and sintering, and testing and sorting, wherein the PN isolation adopts laser etching and specifically comprises steps as follows: edge slotting is performed on the back surface of the solar cell with a fiber laser at a line scribing speed of 100-120 mm/s by surrounding the surface of the back surface of a silicon wafer, the distance between a slotting edge and the silicon wafer edge is 0.5mm, and the slotting depth is 10-15 mu m, so that PN isolation is realized. According to the process, a traditional wet etching process is replaced with laser isolation, and a traditional laser etching process is improved, so that the process requirement of removing an edge PN junction during the production process of solar cells can be met.

Description

Technical field [0001] The invention relates to a laser PN isolation process, in particular to a solar cell back field laser PN isolation process. It belongs to the field of solar cell manufacturing technology. Background technique [0002] In the solar cell production process, the thermal diffusion process used, after the diffusion of phosphorus oxychloride, the front electrode and the back electrode are conductive under the connection of the edge PN, so the edge PN junction must be removed by PN isolation technology. Traditional laser isolation is completed after screen printing, which can easily cause dust pollution and laser alignment offset ( figure 1 ); At present, the PN isolation technology used in the production process of most manufacturers is wet etching, which achieves the effect of PN isolation through chemical corrosion, which can easily lead to incomplete edge etching and loss of excessive front light receiving area ( figure 2 ). [0003] The effect of PN junction ...

AI Technical Summary

Problems solved by technology

[0004] The traditional laser PN isolation is to use laser scribing and groove method to achieve PN isolation on the front side of the silicon wafer after the screen is sintered. The disadvantage is that the dust generated by the laser groove is easy to pollute the surface of the solar cell and lose a part of the front side. As a result, the photoelectric conversion efficiency of solar cells decreases; with the advancement of technology, wet etching gradually replaces laser scribing technology, but wet etching generally needs to corrode the front emitter by 1 to 2mm by chemical liquid

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