Low-pressure diffusion technique in solar cell silicon wafer production process

Abstract

The present invention provides a low-pressure diffusion technique in a solar cell silicon wafer production process, and belongs to the technical field of solar cell production. The technical problem that silicon wafer surface diffusion is not uniform in the conventional solar cell silicon wafer production process is solved. The low-pressure diffusion technique comprises a first step of vacuumizing, placing a silicon wafer into a reaction chamber of a diffusion furnace and vaccumizing the reaction chamber of the diffusion furnace to be of a 50 mbar-150 mbar vacuum state by using a vacuum pump; a second step of gas inflation, inflating a small amount of nitrogen and phosphorus oxychloride into the reaction chamber of the diffusion furnace; a third step of low-pressure diffusion, maintaining pressure inside the reaction chamber to be unchanged, low-pressure diffusion time being 700S-900S; and a fourth step of detection, detecting a low-pressure diffusion result to enable silicon wafer surface square resistance to be 80 omega-130 omega per square and uniformity being within +-3%. The technique provided by the present invention has the advantages of excellent diffusion uniformity, sharp reduction in losses of chemicals and special gases, long maintenance cycle, and the like.

Description

technical field [0001] The invention belongs to the technical field of solar cell production, and relates to a production process of solar cell silicon wafers, in particular to a low-voltage diffusion process in the production process of solar battery silicon wafers. Background technique [0002] Diffusion is an important process in the production of silicon wafers for solar cells. The quality of the PN junction of silicon wafers for solar cells directly determines the photoelectric conversion efficiency. The diffusion process requires stable temperature and gas fields in the reaction tube. However, the traditional atmospheric pressure diffusion process There are some deficiencies in the normal production process, which will affect the quality of the diffusion process, mainly including: due to the small partial pressure ratio of dopant atoms and the small distance between adjacent silicon wafers, the gap between the doping concentration in the middle of the silicon wafer and ...

AI Technical Summary

Problems solved by technology

[0004] The above-mentioned patent adopts the atmospheric pressure diffusion process, and the liquid phosphorus source is easy to diffuse, which will produce a large amount of residue (mainly phosphorus pentoxide) and waste gas (mainly chlorine gas)

If you encounter cold air with a lower temperature, the water in it will form metaphosphoric acid with phosphorus pentoxide, and hydrochloric acid with chlorine gas. Both metaphosphoric acid and hydrochloric acid can cause serious damage to the human body. Corrosion of equipment and instruments affects its service life and performance

Images