Process for diffusing silicon solar cell adopting selective emitter junction realized through double diffusion

Abstract

The invention relates to the technical field of silicon solar cells, in particular to a process for diffusing a silicon solar cell adopting a selective emitter junction realized through double diffusion. The process comprises the following steps: placing a cleaned silicon wafer into a furnace, raising the temperature and introducing oxygen, nitrogen and phosphorus oxychloride into the furnace to carry out diffusion; and stopping introducing phosphorus oxychloride, continuing introducing oxygen and nitrogen and distributing after raising the temperature. The process has the following beneficial effects: the general condition of non-uniform sheet resistance is greatly improved under the condition of low surface concentration; the problem of ensuring low surface concentration of the silicon wafer while ensuring good sheet resistance uniformity in the low-concentration doped diffusion process is solved; the lightly-doped diffusion process has the following requirements: the surface concentration is 1E20-5E20Atom / cm2 and the junction depth is 0.2-0.35mu m; the sheet resistance uniformity is about 15% by adopting the general diffusion processes, but the sheet resistance uniformity is within 8% by adopting the technical scheme adopted by the invention; and through verification, the electrical performance yield of the solar cell plate is improved from 95% to 99.5%.

Description

technical field [0001] The invention relates to the technical field of silicon solar cells, in particular to a diffusion process for double diffusion selective emission junction silicon solar cells. Background technique [0002] Solar cells use the principle of photovoltaic effect to convert solar radiation energy into electrical energy. Solar cells are essentially a two-junction tube of a large-area semiconductor PN junction. The traditional solar cell preparation method has little room for improving the conversion efficiency of solar cells, but the selective emission junction can greatly improve the conversion efficiency of solar cells, and the selective emission junction can be realized by double diffusion of masking film. [0003] Double diffusion is the way to realize the selective emission junction, that is, at the electrode contact, a high-concentration doping diffusion process is used to reduce the series resistance and improve the fill factor, while a light-concentr...

AI Technical Summary

Problems solved by technology

The traditional diffusion process is generally completed by entering the boat→heating→stabilizing→diffusion→redistribution→cooling→out of the boat. The diffusion step and the redistribution step are completed at the same temperature. The result of the diffusion and redistribution at the same temperature is to ensure that Light doping concentration, the source flow rate of POCL3 (a liquid source that can be decomposed into phosphorus elements through chemical reactions) should not be large, otherwise the concentration will be high, but this will lead to poor square resistance uniformity and affect the electrical performance of the cell parameter yield