Semiconducting device, esp. high speed bipolar transistor

摘要

The device has a semiconducting substrate (1), an embedded collector layer (2) of a first conductor type formed on the substrate, and an epitaxial layer (4) of the first conductor type formed on the collector layer. Also provided is a recess (20) in the surface of the epitaxial layer of depth not grater than 0.1 microns. An internal base region (12) of a second conductor type is formed on the epitaxial layer directly below the recess. An external base (11) of the second conductor type is formed on the epitaxial layer surface outside the recess and bounding on the internal base region. An emitter region (14) of the first conductor type is formed on a central region of the base region.