Method for making selective subcollector heterojunction bipolar transistors
AssigneeTRW Inc.
InventorsDwight Christopher Streit, Michael Lammert, Aaron Kenji Oki
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Abstract
A method for fabricating an HBT in which the subcollector-base junction, which contributes to the base-collector capacitance of the device, is reduced by using a selective subcollector. In particular, subcollector areas of the device that do not contribute to collector resistance reduction are eliminated, thereby reducing the subcollector area, which, in turn, reduces the base-collector capacitance. As such, the maximum power-gain frequency f.sub.max is increased.
Claims7
A method for fabricating a heterojunction bipolar transistor (HBT) with an increased maximum power gain frequency, comprising the steps of:
- (a) providing a substrate;
- (b) patterning a photo-resist over a portion of said substrate;
- (c) implanting silicon ions in a portion of said substrate not covered by said photo-resist, forming a subcollector;
- (d) forming collector, base and emitter regions over said subcollector;
- and
- (e) forming ohmic contacts on said collector, base and emitter regions.
Dependencies are inferred from the claim text.