Patent ID: 8101491

Claim:
A method of manufacture of a heterostructure bipolar transistor, HBT, comprising: defining shallow trench isolation, STI, structures in a substrate around a buried collector drift region, the buried collector drift region being in contact with a buried collector; depositing a gate stack including a gate oxide, a gate, and a gate insulator above the gate; etching the gate stack to define a base window over the buried collector drift region and overlapping the STI structures and continuing to selectively etch the buried collector drift region between the STI structures to form a base well between the STI structures; selectively depositing silicon-germanium in the base well and in the base window to form epitaxial silicon-germanium in the base well in contact with the buried collector drift region and poly silicon-germanium on the side walls of the base well and base window; forming insulator on the inner sidewalls of the poly-silicon germanium; and forming an emitter above the epitaxial silicon germanium and inside the insulator on the inner sidewalls.