Boron diffusion method and N-type solar cell preparation method

Abstract

The invention provides a boron diffusion method. The boron diffusion method comprises the following steps: 1) selecting an N-type silicon substrate as a substrate to carry out double-sided texturing treatment; 2) carrying out wet oxidation on the N-type silicon substrate to form a silicon oxide layer on the silicon surface; 3) preparing a double-sided p+ doped region on the surface of the N-type silicon substrate by using boron tribromide as a boron source; 4) putting one surface of the N-type silicon substrate into a mixed solution of HF, HNO3 and H2SO4 for etching treatment to remove the silicon oxide layer on the back surface and the p+ doped region on the back surface and obtain an etched smooth pyramid surface, and putting an HF solution into the other surface of the N-type silicon substrate to remove the silicon oxide layer on the front surface. According to the invention, a silicon oxide film is prepared on the silicon surface before boron diffusion to prevent the formation of BRL; the silicon oxide layer prepared by a wet method is good in uniformity; the process is simple, and procedures do not need to be increased; the oxidation and HF cleaning processes are separately carried out, so the process window is greatly widened.

Description

technical field [0001] The invention relates to the technical field of solar cells, in particular to a method for boron diffusion and a method for preparing N-type solar cells based on boron diffusion. Background technique [0002] N-type crystalline silicon has a high tolerance to metal contamination, and correspondingly has a high body minority carrier lifetime. P-type boron-doped CZ silicon solar cells will have obvious performance attenuation under light, which is called light-induced attenuation, while N-type phosphorus-doped CZ silicon does not have obvious light-induced attenuation phenomenon. The core of solar cells is the p-n junction. At present, there are three methods for realizing p-n junctions on N-type silicon substrates: boron diffusion junctions, amorphous silicon / crystalline silicon heterojunctions, and Al push junctions. Among them, boron diffusion is the most widely used. Knot making. However, it is inevitable to form a thin boron-rich layer (BRL for sh...

AI Technical Summary

Problems solved by technology

Since this layer of B atoms is inactive, and BRL will cause structural defects in this part, the boron-rich layer seriously affects the life of minority carriers in the silicon wafer, and ultimately affects the efficiency of the battery.

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