Patent ID: 9281375
Filing Date: 2016-03-08
CPC Classification: H01L

Claim Text:
1. A method for producing a bipolar transistor, comprising: providing a semiconductor-containing substrate with an upper surface, and having therein a buried layer collector region of a first conductivity type located below the upper surface and of a buried layer collector region doping concentration, wherein a first portion of the substrate located below the buried layer collector region and a second portion of the substrate located above the buried layer collector region are of a second, opposite conductivity type; during one or more first doping steps, forming in the second portion of the substrate first and second adjacent emitter regions of the first conductivity type near the first surface, the first emitter region extending substantially to the first surface and laterally separated from the buried layer collector region; and during one or more second doping steps, forming in the second portion of the substrate first and second adjacent base regions of the second conductivity type, respectively, beneath the first and second emitter regions, wherein the first base region has a first base region doping concentration and the second base region has a second base region doping concentration different than the first base region doping concentration, and the first emitter region and first base region providing a first NP or PN junction at a first depth beneath the upper surface, and the second emitter region and the second base region providing a second NP or PN junction at a second depth beneath the upper surface.