ALLNAS/INGAAS BASED HETEROJUNCTION BIPOLAR-TRANSISTORS FABRICATED BY ELECTRON-CYCLOTRON RESONANCE ETCH

A dry etch fabrication technology for high-speed AlInAs/InGaAs heterojunction bipolar transistors (HBTs) utilizing low-damage electron cyclotron resonance (ECR) CH4/H-2/Ar plasma etching is detailed. Small-area (2 x 4 to 3 x 9-mu-m2) devices demonstrated current gains up to 160, unity gain cutoff frequency (f(T)) of 57 GHz and a maximum oscillation frequency (f(max)) of 35 GHz. The dry etch process uses triple self-alignment of the emitter and base metals and the base mesa, minimizing the base-collector capacitance (C(BC)). These results represent the first report of a truly scalable process for In-based HBTs and demonstrate the ability of ECR plasma etching to provide smooth, degradation-free etching of III-V semiconductors.