Base profile of self-aligned bipolar transistors for power amplifier applications

摘要

According to a bipolar transistor structure having a transistor top and a transistor bottom herein, a silicon substrate located at the transistor bottom has a collector region of a first conductivity type. An epitaxial base layer of a second conductivity type overlies, relative to the transistor top and bottom, a portion of the collector region. The epitaxial base layer has a bottom surface on the silicon substrate and a top surface opposite the bottom surface. A top region, relative to the transistor top and bottom, of the epitaxial base layer comprises a concentration of germanium having atomic compositions sufficient to avoid impacting transistor parameters, and sufficient to be resistant to selective chemical etching. A silicon emitter layer of the first conductivity type overlies, relative to the transistor top and bottom, a portion of the epitaxial base layer adjacent to the top surface of the epitaxial base layer.

主权项

1. A method of forming a bipolar transistor structure comprising:
forming a collector region of a first conductivity type within a semiconductor substrate; forming a base of a second conductivity type on a portion of said collector region; forming an etch-stop region in a surface layer of said base, said surface layer being located opposite said semiconductor substrate; controlling a concentration of germanium in said etch-stop region to have atomic compositions between 1% and 15% at the top of said surface layer, said concentration of germanium being sufficient to avoid impacting transistor parameters and sufficient to be resistant to selective chemical etching; and forming an emitter of said first conductivity type on said etch-stop region of said base.