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US 5,344,786 AGranted
Method of fabricating self-aligned heterojunction bipolar transistors
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.
Claims12
A method of fabricating a heterojunction bipolar transistor, comprising the steps of:
- (a) forming a collector layer over a semi-insulating semiconductor substrate;
- (b) forming a base layer over said collector layer;
- (c) forming an emitter layer over said base layer;
- (d) forming an ohmic emitter contact layer over said emitter layer;
- (e) forming an insulator layer over said ohmic emitter contact layer;
- (f) removing said insulator layer and said ohmic emitter contact layer from all areas not covering an emitter location;
- (g) forming insulator sidewalls abutting vertical surfaces of said insulator layer and said ohmic emitter contact layer, said insulator sidewalls also abutting a portion of a horizontal surface of said emitter layer;
- (h) removing said emitter layer from all areas not covered by said insulator layer or by said insulator sidewalls;
- and
- (i) forming an ohmic base contact layer to be horizontally continuous over said insulator layer, said insulator sidewalls and a portion of said base layer, and to be vertically discontinuous between said insulator sidewalls and said portion of said base layer.
7 more elements
Dependencies are inferred from the claim text.