Heterojunction bipolar transistor, manufacturing method therefor, and communication device therewith

摘要

An emitter of a heterojunction bipolar transistor has a double-layer protrusion formed of a first emitter layer and a second emitter layer and protruded outside an external base region. The protrusion of 50 nm in total thickness is enough to prevent damage during formation of the protrusion by etching or during later fabricating processes. Penetration of moisture through damaged places is eliminated. A base ohmic electrode is continuously formed on the first and second emitter layers on the external base region up to the protrusion. Thus, the protrusion is reinforced so as to be further hard to damage. By ensuring a large area for the base ohmic electrode, an alignment margin can be taken during formation of a base lead electrode.