Patent ID: 7087979
Filing Date: 2006-08-08
Classification: H01L

Abstract:
1. A bipolar transistor formed on a wafer, the wafer having a buried layer and an epitaxial layer of a first conductivity type formed over the buried layer, the epitaxial layer having a top surface and a smaller dopant concentration than the buried layer, the transistor comprising: an intrinsic base region of a second conductivity type formed on the epitaxial layer, the intrinsic base region including silicon and germanium, and having a first top surface and a vertically spaced-apart second top surface; an isolation region formed on the first top surface and the second top surface of the intrinsic base region, the isolation region having a side wall; a first emitter region formed on the isolation region, the first emitter region having a side wall that is substantially aligned with the side wall of the isolation region; and a second emitter region that contacts the intrinsic base region and the first emitter region.