Heterojunction Bipolar Transistor

摘要

A heterostructure bipolar transistor, HBT, includes shallow trench isolation, STI, structures 6 around a buried collector drift region 8 in contact with a buried collector. A gate stack 10 including a gate oxide 12 and a gate 14 is deposited and etched to define a base window 20 over the buried collector drift region 8 and overlapping the STI structures 6. The etching process is continued to selectively etch the buried collector drift region 8between the STI structures 6 to form a base well 22. SiGeC may be selectively deposited to form epitaxial silicon-germanium 26 in the base well in contact with the buried collector drift region 8 and poly silicon-germanium 28 on the side walls of the base well and base window. Spacers 32 are then formed as well as an emitter 34.