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US 5,631,173 AGranted
Method for forming collector up heterojunction bipolar transistor having insulative extrinsic emitter
AssigneeTexas Instruments Incorporated
InventorsJoseph B. Delaney, Kirk E. Bracey
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Abstract
A process and structure for an improved collector-up bipolar transistor. The base is formed after the emitter is implanted to eliminate base damage during oxygen implantation typical in prior art collector-up bipolar transistors. In a preferred embodiment, an emitter layer of GaAlAs is implanted with oxygen in the extrinsic emitter region to damage the material and make it insulative. The base is epitaxially grown at low temperature to insure the emitter material remains damaged and insulative.
Claims11
A method of forming a collector-up microelectronic transistor structure, said method comprising steps:
- (a) forming a semiconductor substrate;
- (b) depositing an emitter contact layer on said substrate;
- (c) depositing an emitter layer on said emitter contact layer;
- (d) oxidizing said emitter layer using a mask to form an intrinsic emitter and an extrinsic emitter wherein said extrinsic emitter is insulative and said intrinsic emitter is conductive;
- (e) forming a low resistivity base having an intrinsic and extrinsic portion wherein said intrinsic base is over said intrinsic emitter layer and said extrinsic base is over a portion of said extrinsic emitter;
- and
- (f) forming a collector disposed over a portion of said base.
4 more elements
Dependencies are inferred from the claim text.