AlGaAs/GaAs HBTs fabricated by a self-alignment technology using polyimide for electrode separation

A self-aligned HBT (heterojunction bipolar transistor) technology using polymide for insulating the emitter contact from the base contact is described. A 1- mu m emitter-width HBT with maximum oscillation frequency of 86 GHz was successfully fabricated. This processing was also applied to fabricate frequency-divider ICs. An operating frequency of 18 GHz was obtained with good reproducibility.<
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