Heterojunction bipolar transistor

Abstract

A method of fabricating a semiconductor device includes producing a collector layer, a base layer, and an emitter layer on a semiconductor substrate; producing a dummy emitter electrode on a region of the emitter layer; forming a first resist except where the dummy emitter electrode is present; completely removing the dummy emitter electrode to expose the surface of the emitter layer; depositing an emitter electrode material on the first resist and the emitter layer that is exposed by the removal of the dummy emitter electrode; forming a mask on a region of the emitter electrode material film where an emitter electrode is later produced; and etching the emitter electrode material film using the mask; and removing the first resist, thereby producing an emitter electrode layer, a peripheral side part extending upward from the bottom part, and an upper fringe part protruding outward from the peripheral side part perpendicular to the peripheral side part. A minute emitter electrode is produced without employing vacuum evaporation and lift-off techniques that can cause burrs on the emitter electrode. Since a refractory metal can be employed as the emitter electrode material, a highly-reliable emitter electrode is produced with high stability.

Dependencies are inferred from the claim text.