Method of fabricating bipolar transistors with buried collector region

摘要

A method of fabricating a bipolar transistor with a buried subcollector by forming a collector layer and a base layer in a semiconductor substrate. A polysilicon layer is deposited over the base layer and spaced emitter and base contact regions formed in the base layer. A mask is formed over the emitter and base contact regions and the substrate anisotropically etched to form pedestals with vertical sidewalls. A masking layer is formed on the vertical sidewalls, and a large angle ion implant used to introduce ions beneath the collector layer, thereby forming a subcollector region.