Development of a Polysilicon Process Based on Chemical Vapor Deposition of Dichlorosilane in an Advanced Siemen's Reactor. Final Report, October 11, 1982-May 21, 1983

摘要

Dichlorosilane (DCS) was used as the feedstock for an advanced decomposition reactor for silicon production. The advanced reactor had a cool bell jar wall temperature, 300 exp 0 C, when compared to Siemen's reactors previously used for DCS decomposition by Hemlock Semiconductor Corporation. Previous reactors had bell jar wall temperatures of approximately 750 exp 0 C. The cooler wall temperature allows higher DCS flow rates and concentrations. A silicon deposition rate of 2.28 gm/hr-cm was achieved with power consumption of 59 kWh/kg. Interpretation of data suggests that a 2.8 gm/hr-cm deposition rate is possible. The 2.8 gm/hr-cm deposition rate surpasses the goal of 2.0 gm/hr-cm. Power consumption and conversion should approach the program goals of 60 kWh/kg and 40%. Screening of lower cost materials of construction was done as a separate program segment. Stainless Steel (304 and 316), Hastalloy B, Monel 400 and 1010-1020 Carbon Steel were placed individually in an experimental scale reactor. Silicon was deposited from trichlorosilane feedstock. The resultant silicon was analyzed for electrically active and metallic impurities as well as carbon. No material contributed significant amounts of electrically active or metallic impurities, but all contributed carbon. Single crystal growth could not be maintained in most zone refining evaluations. No material need be excluded from consideration for use in construction of decomposition reactor components for production of photovoltaic grade silicon; however, further evaluation and the use of the low carbon alloys is considered essential. (ERA citation 09:043091)