DEPOSITION OF HIGH-PURITY SILICON VIA HIGH-SURFACE AREA GAS-SOLID OR GAS-LIQUID INTERFACES AND RECOVERY VIA LIQUED PHASE

摘要

Solid silicon is deposited onto electrically heated deposition plates by the reduction reaction of gaseous thchlorosilane and hydrogen which are mixed and pumped across the surfaces of the plates. The plates can have a number of high-surface area geometries such as concentric cylinders, spirals, or repeating S-shapes. Once the desired amount of silicon has been deposited, the deposition plates are heated to above the melting point of silicon causing the deposited silicon to slide off the plates in the form of a crust due to gravitational force. The plates are left coated with a thin film of liquid silicon which contains any impurities leached from the plates. This film is melted off separately from the main silicon crust to avoid contamination of the latter and the plates are then ready for the next deposition cycle.