Patent ID: 7875523

Claim:
A method for fabricating a heterojunction bipolar transistor (HBT), comprising: providing a structure comprising sequentially a substrate, a collector layer for the HBT, a base layer for the HBT, an epitaxial layer, and an emitter metal layer for the HBT; etching the emitter metal layer and the epitaxial layer to form an emitter electrode comprised of an emitter epitaxy pedestal underlying an emitter metal cap and having horizontal dimensions that are equal to the emitter metal cap; depositing a photoresist layer over the emitter electrode and onto the base layer and in direct contact with the base layer; masking the photoresist layer with a mask that exposes an area over and a predetermined distance away from the emitter electrode; irradiating the photoresist layer through the mask; removing the exposed photoresist layer to expose a portion of the base layer that is spaced the predetermined distance away from the emitter electrode; depositing base metal over the structure; and removing the remainder of the photoresist layer together with the base metal deposited thereupon; wherein the predetermined distance is between 0.05 μm and 0.2 μm; and wherein one or more of the emitter epitaxy and base layer comprise one or more of InGaAs, InAlAs, InAs, InSb, AlInGaAs, InGaSb, InP, Si and SiGe.