Patent ID: 7026666
Filing Date: 2006-04-11
Classification: H01L

Abstract:
1. A bipolar transistor, comprising: a substrate to provide a collector region; a base region having an intrinsic base region and an extrinsic base region, the extrinsic base region includes a first epitaxial layer and a second epitaxial layer on the first epitaxial layer, each of the intrinsic base region and the extrinsic base region having a mono-crystalline portion over a mono-crystalline portion of the substrate, the extrinsic base region further has a poly-crystalline portion over an oxide portion of the substrate; and an emitter structure over the intrinsic base region; wherein the extrinsic base region is raised relative to the intrinsic base region; wherein the extrinsic base region has a thickness x and the intrinsic base region has a thickness y, and wherein x is greater than y.