Image Number 4 for United States Patent #6924202.
A heterojunction bipolar transistor (HBT), and manufacturing method therfor, comprising a semiconductor substrate having a collector region is provided. A base contact layer is formed over the collector region, and a base trench is formed in the base contact layer and the collector region. An intrinsic base structure having a sidewall portion and a bottom portion is formed in the base trench. An insulating spacer is formed over the sidewall portion of the intrinsic base structure, and an emitter structure is formed over the insulating spacer and the bottom portion of the intrinsic base structure. An interlevel dielectric layer is formed over the base contact layer and the emitter structure. Connections are formed through the interlevel dielectric layer to the collector region, the base contact layer, and the emitter structure. The intrinsic base structure is silicon and at least one of silicon-germanium, silicon-germanium-carbon, and combinations thereof.