N-type back junction crystalline silicon cell and preparation method thereof

Abstract

The invention provides an N-type back junction crystalline silicon cell and a preparation method thereof. The battery comprises a front surface Ag electrode, a front surface antireflection film, a phosphorus diffusion N+ front surface field layer, an N-type base, a boron diffusion emitter P+ layer, a back passivation composite film and a back AgAl electrode, wherein the PN junction is located on the back surface of the cell; a polishing structure is adopted by the back surface of the battery; the back passivation composite film comprises a borosilicate glass layer and a silicon nitride layer; the borosilicate glass layer is located on the boron diffusion emitter P+ layer; and the silicon nitride layer is deposited on the borosilicate glass layer; a boron emitter is passivated by the borosilicate glass layer and silicon nitride laminated film structure generated in the boron diffusion process; the polishing structure is adopted by the back surface; and the passivation effect of the boron emitter is further improved. The preparation technology of the battery is relatively simple, can be compatible with equipment of the current crystalline silicon cell production line, and is suitable for large-scale industrial production; and the cost can be reduced.

Description

technical field [0001] The invention relates to the technical field of solar cell production, in particular to an N-type back crystalline silicon cell structure and a preparation method thereof. Background technique [0002] At present, crystalline silicon cells are the mainstream products in the solar cell market, and crystalline silicon solar cells can be divided into P-type crystalline silicon cells and N-type crystalline silicon cells in terms of material and substrate types. Compared with P-type monocrystalline silicon cells, N-type monocrystalline silicon cells have the characteristics of small light-induced attenuation, good resistance to metal impurity pollution, and long diffusion length of minority carriers. It requires multiple diffusions and passivation treatment of the boron emitter, and the preparation process is relatively complicated. [0003] For N-type crystalline silicon cells with a simple structure, since one-time boron diffusion and one-time phosphorus...

AI Technical Summary

Problems solved by technology

This high temperature process will easily lead to changes in the diffusion curve of the p+ layer, such as the decrease of the surface doping concentration and the increase of the junction depth, resulting in an increase in the series resistance of the battery and a decrease in electrical contact performance; at the same time, the high temperature process will easily lead to an increase in the impurity concentration of the silicon substrate , the bulk recombination of the battery will intensify, and finally manifest as a decrease in the open circuit voltage and overall efficiency

Patent CN102544236B reports that after completing single-sided B doping to form a p+ boron emitter layer, the borosilicate glass layer is removed, and then SiN is deposited on both sides of the silicon wafer by low-pressure chemical vapor deposition (LPCVD) x film, and then expand the SiN surface on the B x SiO deposited on 2 , using phosphoric acid to remove uncoated SiO 2 Protected SiN x surface, and then perform phosphorus diffusion on this surface. This method involves multiple coating and cleaning processes. The process is relatively complicated, which is not conducive to improving production efficiency and reducing production costs.

Images