Solar grade silicon refining by chemical vapour deposition.

摘要

To reduce the cost of producing solar grade silicon, a new process to refine metallurgical grade silicon has been investigated. The new process is based on modifications of the Siemens Process. In the new process, the production of trichiorosilane gas and deposition of purer silicon occurs in one reactor using Cu-Si alloys as the silicon source. A 1:1 gas mixture of H2 and HC1 was used to react with Cu-Si to form SiHCl3 gas. The SiHCl3 gas then decomposed on a hot silicon filament to produce purer silicon. The feasibility of the process was tested in lab scale with emphasis on factors affecting the production rate. It was found that the production rate increases linearly with increasing deposition area and that boundary layer diffusion might be the rate-controlling step of deposition. A possible reaction mechanism and the prevention of Cu-Si alloy disintegration were also addressed.