Patent ID: 7008851
Filing Date: 2006-03-07
Classification: H01L

Abstract:
1. A method in the fabrication of a silicon-germanium mesa transistor in a semiconductor process flow, particularly in a process flow designed for a bipolar integrated circuit for radio frequency applications, comprising by the steps of: providing a p-type doped silicon bulk substrate having an n depositing epitaxially thereon a silicon layer comprising n-type dopant; depositing epitaxially thereon a silicon layer comprising germanium and p-type dopant; forming in said n-type and p-type epitaxial layers field isolation areas around, in a horizontal plane, a portion of said epitaxial layers to simultaneously define an n-type doped collector region for the mesa transistor on the subcollector; a p-type doped base region for the mesa transistor thereon; and an n-type doped collector plug on the subcollector, but separated from the n-type doped collector region and the p-type doped base region; and thereafter forming in said p-type doped base region an n-type doped emitter region for the mesa transistor.