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US 5,471,078 AGranted
Self-aligned heterojunction bipolar transistor
AssigneeTexas Instruments Incorporated
InventorBurhan Bayraktaroglu
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Abstract
A method of fabricating heterojunction bipolar transistors (HBTs) including epitaxial growth of collector, base and emitter layers, allowing for self-aligned emitter-base contacts to minimize series base resistance and to reduce total base-collector capacitance.
Claims13
A heterojunction bipolar transistor device, comprising:
- (a) a substrate of semi-insulating semiconductor material having a first surface;
- (b) a doped collector layer over said first surface;
- (c) a doped base layer over said collector layer, said base layer of conductivity type opposite that of said collector layer;
- (d) a doped emitter layer over said base layer, said emitter layer of the same conductivity type as said collector;
- (e) an ohmic emitter contact layer over said emitter layer;
- (f) an insulator layer over said emitter contact layer, said insulator layer with edges aligned to said emitter contact layer;
- (g) an insulator sidewall covering the exposed vertical surfaces of said emitter contact layer and said insulator layer and extending a distance horizontally from said surfaces;
- and
- (h) a metal base contact layer covering said insulator layer, said insulator sidewall area and a portion of said base layer such that said base contact layer does not come into contact with said emitter layer or said emitter contact layer.
6 more elements
Dependencies are inferred from the claim text.