Bipolar transistors having fixed gain characteristics

Claim 2

A bipolar transistor comprising: a semiconductor body having first and second opposed surfaces with opposing edge surfaces therebetween; an emitter region, a base region and a first collector region in said semiconductor body with an emitter-base junction between said emitter and base regions and a base-collector junction between said base and first collection regions; said emitter region extending to said first surface and said emitter-base junction extending across said semiconductor body and terminating at said edge surfaces such that injection across said emitter-base junction is substantially uniform across said semiconductor body; said first collector region extending to said second surface; means for making a low ohmic collector contact to said first collection region at said second surface; a highly conductive substrate supporting said semiconductor body; means making a low ohmic emitter contact between said substrate and said first surface of said semiconductor body; said base region extending to said second surface; a second collector region in said semiconductor body and independent of said first collector region, said second collector region extending to said second surface; and means for making a low ohmic base contact to both said base region and said second collector region at said second surface.

Claim 3

A bipolar transistor as recited in claim 1 wherein said base contact means comprises a first metal layer on said second surface and overlying a portion of said base and second collector region on said second surface.

Claim 4

A bipolar transistor as recited in claim 2 wherein said second surface defines a plurality of mesas, a first one of said mesas defining said first collector region in said semiconductor body and a second one of said mesas including said second collector region therein.

Claim 5

A bipolar transistor as recited in claim 1 wherein said second surface comprises a substantially flat surface, and wherein said means for making a low ohmic base contact comprises a highly conductive portion of said base region extending to said second surface.

Claim 6

A bipolar transistor as recited in claim 4 wherein said low ohmic base contact further comprises a base metal layer overlying said highly conductive portion at said second surface.

Claim 7

A bipolar transistor comprising: a high condictivity substrate; a semiconductor body having first and second opposed surfaces with opposed edge surfaces therebetween; an emitter region of a first conductivity type in said semiconductor body and extending to said first surface, said emitter region making a low ohmic contact with a substrate at said first surface; a base region in said semiconductor body of a second conductivity type opposite to said first conductivity type, said base region being adjacent to said emitter region and extending to said second surface; means for making low ohmic contact to said base region at said second surface; an emitter-base junction between said emitter and base regions and extending across said semiconductor body and terminating at said edge surfaces; a first collector region in said semiconductor body of said first conductivity type and adjacent said base region with a first base-collector junction therebetween, said collector region extending to said second surface; a second collector region in said semiconductor body of said first conductivity type adjacent said base region with a second base-collector junction therebetween; said base region low ohmic contact means comprising a highly conductive path interconnecting said base region and said second collector region; and wherein injection across said emitter-base junction is substantially uniform between said edge surfaces.

Claim 8

A bipolar transistor comprising: a high condictivity substrate; a semiconductor body having first and second opposed surfaces with opposed edge surfaces therebetween; an emitter region of a first conductivity type in said semiconductor body and extending to said first surface, said emitter region making a low ohmic contact with a substrate at said first surface; a base region in said semiconductor body of a second conductivity type opposite to said first conductivity type, said base region being adjacent to said emitter region and extending to said second surface; means for making low ohmic contact to said base region at said second surface; an emitter-base junction between said emitter and base regions and extending across said semiconductor body and terminating at said edge surfaces; a first collector region in said semiconductor body of said first conductivity type and adjacent said base region with a first base-collector junction therebetween, said collector region extending to said second surface; a second collector region in said semiconductor body of said first conductivity type adjacent said base region with a second base-collector junction therebetween; said base region low ohmic contact means comprising a highly conductive path interconnecting said base region and said second collector region; and wherein injection across said emitter-base junction is substantially uniform between said edge surfaces.

Claim 9

A bipolar transistor as recited in claim 6 wherein said highly conductive path comprises a metal layer disposed on said second surface.

Claim 10

A bipolar transistor as recited in claim 6 wherein the thickness of said emitter region is substantially uniform between said edge surfaces, whereby injection across said emitter-base junction is substantially uniform in a direction towards said collector region in said base region metal layer from said second surface.