Lateral bipolar transistor

Claim 1

A method of forming a transistor comprising: providing a semiconductor substrate of a first conductivity type without an epitaxial layer and having a first surface; forming a collector region of a second conductivity type by doping a portion of the substrate with a retrograde doping profile that has a peak doping concentration a first distance from the first surface wherein the peak doping concentration forms a low resistance collector region; forming a base dopant in a layer overlying the first surface; forming a base region within the collector region wherein the base region is on the first surface and includes an active base area formed from a first portion of the base dopant and an inactive base area formed from a second portion of the base dopant; forming an emitter region within the active base area wherein current substantially flows through the emitter region through the active base region and through the low resistance collector region; and forming a collector ohmic area immediately adjacent to the active base area.

Claim 2

A method of forming a transistor comprising: providing a semiconductor substrate of a first conductivity type without an epitaxial layer and having a first surface; forming a collector region of a second conductivity type by doping a portion of the substrate with a retrograde doping profile that has a peak doping concentration a first distance from the first surface wherein the peak doping concentration forms a low resistance collector region; forming a base dopant in a layer overlying the first surface; forming a base region within the collector region wherein the base region is on the first surface and includes an active base area formed from a first portion of the base dopant and an inactive base area formed from a second portion of the base dopant; forming an emitter region within the active base area wherein current substantially flows through the emitter region through the active base region and through the low resistance collector region; and forming a collector ohmic area immediately adjacent to the active base area.

Claim 8

A method of forming a lateral bipolar transistor comprising: providing a substrate having a retrograde doping profile with a peak doping concentration that is a first distance from a first surface of the substrate; covering a portion of the substrate with a layer of polysilicon; forming a base dopant of a first conductivity type within a portion of the polysilicon layer; forming a plurality of openings in the polysilicon layer to form the polysilicon layer into a base contact, an emitter contact, and a collector contact wherein a first portion of the base dopant is in the base contact and a second portion of the base dopant is in the emitter contact; diffusing the first portion of the base dopant and the second portion of the base dopant into the substrate wherein the first portion of the base dopant forms an inactive base region and the second portion of the base dopant forms an active base region; forming a dielectric plug in each of the plurality of openings; forming an inactive base dopant of the first conductivity type within the base contact; forming an emitter dopant of a second conductivity type within the emitter contact and a collector dopant of the second conductivity type within the collector contact wherein the emitter dopant and the collector dopant are formed substantially simultaneously; diffusing the emitter dopant into the active base region to form an emitter, the collector dopant into the substrate to form a collector ohmic area, and the inactive base dopant into the inactive base region; and covering the base contact, the emitter contact, and the collector contact with a conductor.

Claim 9

A method of forming a lateral bipolar transistor comprising: providing a substrate having a retrograde doping profile with a peak doping concentration that is a first distance from a first surface of the substrate; covering a portion of the substrate with a layer of polysilicon; forming a base dopant of a first conductivity type within a portion of the polysilicon layer; forming a plurality of openings in the polysilicon layer to form the polysilicon layer into a base contact, an emitter contact, and a collector contact wherein a first portion of the base dopant is in the base contact and a second portion of the base dopant is in the emitter contact; diffusing the first portion of the base dopant and the second portion of the base dopant into the substrate wherein the first portion of the base dopant forms an inactive base region and the second portion of the base dopant forms an active base region; forming a dielectric plug in each of the plurality of openings; forming an inactive base dopant of the first conductivity type within the base contact; forming an emitter dopant of a second conductivity type within the emitter contact and a collector dopant of the second conductivity type within the collector contact wherein the emitter dopant and the collector dopant are formed substantially simultaneously; diffusing the emitter dopant into the active base region to form an emitter, the collector dopant into the substrate to form a collector ohmic area, and the inactive base dopant into the inactive base region; and covering the base contact, the emitter contact, and the collector contact with a conductor.