Method and apparatus for chemical vapor deposition of polysilicon

Abstract

A method and apparatus, and product by process, for the production of bulk polysilicon by broad area chemical vapor deposition, consisting of a quartz envelope and base plate forming a reactor enclosure, with external radiant heaters providing the heat source. A thin wall, edge-defined film fed growth (EFG) silicon tube section is used as the deposition casing and reaction chamber wall. The tube is capped at the top and sealed to the base plate to form the reaction chamber. External heaters radiate heat through the quartz enclosure to heat the tube wall to deposition temperature. A through flow of process gas is introduced to initiate the deposition. A uniform wide surface area deposit occurs on the inside surface of the tube, causing the diameter to become increasingly smaller as the yield accumulates. In a two tube reactor, a smaller core tube is uniformly spaced and supported inside the outer tube for full flow of process gas around the core tube so that deposition occurs on both the outside and inside surface of the core tube. The outer tube may be configured for preheating by a flow of electrical current from the base plate to the cover plate.