Patent ID: 6900105

Claim:
A method of manufacturing a semiconductor device having a bipolar transistor comprising: providing a substrate of a first conductivity type; providing an epitaxial layer of the first conductivity type overlying the substrate; providing an oxide layer overlying the epitaxial layer; implanting dopants of a second conductivity type different from the first conductivity type to form a base region within the epitaxial layer; providing a nitride layer overlying the oxide layer; etching first and second trenches through the nitride layer, the oxide layer, the base region and into the epitaxial layer to form a pedestal collector region within the epitaxial layer disposed between the first and second trenches; depositing a dielectric into the first and second trenches to fill the first and second trenches; etching recesses in the dielectric within the first and second trenches, the recesses extending below a top surface at the epitaxial layer proximate the base region; and depositing polysilicon of the second conductivity type into the recesses, wherein the polysilicon acts as a dopant source upon an anneal of the semiconductor device to form a base enhancement region at opposite sides of the base region by diffusing dopants out of the polysilicon and into the base region.