Patent ID: 8450179

Claim:
A method for fabricating a semiconductor device comprising a first bipolar device and a second bipolar device being of the same dopant type, the method comprising the steps of: depositing a first gate oxide dielectric layer over a semiconductor layer; depositing a gate conductor layer over the first gate oxide dielectric layer; defining base regions of the first and second bipolar devices of the same dopant type; removing the gate conductor layer and the first gate oxide dielectric layer in the base regions of the first and second bipolar devices; depositing a base layer on the gate conductor layer and on the exposed semiconductor layer the base regions of the first and second bipolar devices, both base regions part of the base layer; depositing a first insulating layer over the base layer; depositing a second insulating layer over the first insulating layer, patterning emitter regions through patterning a first photoresist layer, thereby defining the emitter regions of the first and second bipolar devices; etching the second insulating layer down to the first insulating layer; removing the first photoresist layer thereby forming two emitter windows, wherein each of the two emitter windows allows an implantation of a emitter of each bipolar device when not covered in a photoresist, and wherein each emitter window is over the base layer; patterning a second photoresist having an associated emitter window for an emitter enhancing implant on the second bipolar device, but not on the first bipolar device, thereby masking the emitter of the first bipolar device; exposing the base layer in the base region of the second bipolar device to the emitter enhancing implant through the associated emitter window; removing the second photoresist layer of the first and second bipolar devices thereby forming two emitter windows, wherein the second emitter area of the base layer is doped by the emitter enhancing implanting while the first emitter area of the base layer does not have emitter species yet; removing an oxide of an emitter area depositing a polysilicon emitter layer over the base layer of the first and second bipolar devices; implanting emitter species into the deposited polysilicon layer to dope the polysilicon; and annealing to diffuse: a) the second implanted emitter species in the deposited emitter polysilicon into the emitter area of the first and second bipolar device; and b) the first implanted emitter species from the emitter enhancing implant in the emitter area of the second bipolar device, wherein the annealing of the first bipolar device and the second bipolar device occur at the same time.