Patent ID: 6962842

Claim:
A method of forming a bipolar device and CMOS device, comprising: forming an isolation structure within a substrate; forming a collector implant region within said substrate on a first side of said isolation structure; forming a polysilicon gate of said CMOS device above said substrate and laterally on a second side of said isolation structure, wherein said second side is opposite said first side; forming a protection layer over said polysilicon gate; forming an intrinsic base structure over said collector implant region; forming a sacrificial emitter structure over said intrinsic base structure; forming an extrinsic base structure over said intrinsic base region adjacent to said sacrificial emitter structure and over said sacrificial emitter structure; forming a first portion of a mask layer over said extrinsic base structure adjacent said sacrificial emitter structure and a second portion of said mask layer over said extrinsic base structure over said sacrificial emitter structure, wherein a thickness of said first portion of said mask layer is greater than a thickness of said second portion of said mask layer; removing said second portion of said mask layer without removing all of said first portion; and removing said sacrificial emitter structure and the extrinsic base structure thereover while said first portion of said mask layer protects said extrinsic base structure adjacent said sacrificial emitter structure.