Patent ID: 7396731

Claim:
A method for preparing a heterojunction bipolar transistor comprising in uninterrupted sequence: a) preparing a patterned emitter metal on an emitter layer of a HBT structure on a substrate; b) preparing an emitter epitaxy disposed exclusively below the emitter metal; c) applying a resist layer on the surface covering the emitter metal and emitter epitaxy, and the base layer; d) applying lithography covering the peripheral edge of the emitter epitaxy and the emitter metal with a width p D and leaving a pattern according to a mask in the resist; e) depositing base metal on the entire surface; and f) removing the remaining resist and the base metal covering the resist defining a base metal, the base metal being spaced from the emitter epitaxy and the emitter metal by a distance x D from 0.05 μm to 0.7 μm.