Patent ID: 6573539
Filing Date: 2003-06-03
Classification: H01L

Abstract:
A heterojunction bipolar transistor, comprising:a silicon substrate having a collector and a mesa surrounded by a trench, said mesa having a top surface; a silicon-germanium base on said top surface of said mesa, said silicon-germanium base having a top surface and a side wall; a silicon nitride layer on said silicon-germanium base; a dielectric layer adjacent said silicon-germanium base, said dielectric layer filling said trench and leaving a portion of said side wall of said silicon-germanium base exposed; an extrinsic base on said dielectric layer such that said extrinsic base covers the exposed portion of said side wall of said silicon-germanium base; a silicon nitride cap on said extrinsic base, and a portion of said silicon nitride layer is exposed; a self-aligned spacer on a portion of the exposed silicon nitride layer adjacent said extrinsic base and said silicon nitride cap, and the top surface of said silicon-germanium base is exposed; and an emitter on the exposed portion of said top surface of said silicon-germanium base.