Heterojunction bipolar transistors.

摘要

A heterojunction bipolar transistor formed as a collector top type or emitter top type can operate at high speed and can be fabricated into a semiconductor integrated circuit with ease. The transistor comprises an external base region (36b), an intrinsic base region (38b), an emitter region (33E) and a collector region (39C). The external base region (36b) contacts the emitter region (33E) - or the collector region - at side surfaces thereof. The intrinsic base region (38B) is formed on a region including the boundary between the emitter region (33E) - or the collector region - and the external base region (36b). The collector region (39C) - or the emitter region - is formed on the intrinsic base region (38B).