Byoung Gue Min

Characteristics of self-aligned InP/InGaAs heterojunction bipolar transistor assisted by silicon nitride sidewall

A reliable fabrication method for providing close spacing between the emitter mesa and the base contact metal of InP-based heterojunction bipolar transistor is disclosed. The silicon nitride sidewall was formed on the emitter electrode and mesa periphery. It was used as a mask for emitter mesa etching and also as an overhang to self-align the base contact with respect to the emitter mesa. The self-aligned device fabricated by this technique exhibited better high-frequency performances with fT of 138 GHz and fmax of 143 GHz, respectively, superior to the re-aligned one on the same epitaxy wafer.