Patents Represented by Attorney, Agent or Law Firm Beaver Weaver & Thomas LLP
  • Patent number: 6329698
    Abstract: An improved method and an apparatus for forming a self-aligned epitaxial base bipolar transistor in a semiconductor material is disclosed. The method of the invention involves forming an intrinsic base region formed by growing an epitaxial semiconductor material over a collector region. A raised sacrificial emitter core is then formed on the intrinsic base region followed by depositing a substantially conformal spacer layer over the sacrificial emitter core. Next, the spacer material is anisotropically etched such that a protective spacer ring is formed about the sacrificial emitter core. An extrinsic base is then formed by implanting dopant into the epitaxial base region wherein the sacrificial emitter core and the spacer ring preserve an emitter region. The spacer ring also serves to self-align the extrinsic base region to the emitter region. The protective sacrificial emitter core and spacer ring are then removed.
    Type: Grant
    Filed: September 21, 1999
    Date of Patent: December 11, 2001
    Assignee: National Semiconductor Corporation
    Inventors: Waclaw C. Koscielniak, Kulwant S. Egan, Jayasimha S. Prasad