SOI BICMOS process

Abstract

This invention is an SOI BICMOS process which uses oxygen implanted wafers as the starting substrate. The bipolar transistor is constructed in two stacked epitaxial layers on the surface of the oxygen implanted substrate. A buried collector is formed in the first epitaxial layer that is also used for the CMOS transistors. The buried collector minimizes the collector resistance. Selective epitaxial silicon is then grown over the first epitaxial layer and is used to form the tanks for the bipolar transistors. An oxide layer is formed over the base to serve as an insulator between the emitter poly and the extrinsic base, and also as an etch stop for the emitter etch. The emitter is formed of a polysilicon layer which is deposited through an opening in the oxide layer such that the polysilicon layer contacts the epitaxial layer and overlaps the oxide layer.

Dependencies are inferred from the claim text.