Patent ID: 7612430

Claim:
A silicon bipolar transistor, having: a base; an emitter, the entirety of which is heavily doped with doping atoms; and a collector, where the base has a first base region having a first base width and a second base region having a second base width, the first base width being thinner than the second base width, wherein the base contains germanium atoms, where the first base region is doped with 10 19 to 2×10 20 cm −3 doping atoms to reduce the sheet resistance of the base compared to the sheet resistance of a base having a lower average doping concentration than an average doping concentration of the first and the second base region, where the second base region is doped with 5×10 17 to 1×10 19 cm −3 doping atoms, merging in stepped fashion into the first base region, where the emitter is applied directly on the second base region, and where at least a part of the first base region at least partly has a higher concentration of germanium atoms than at least a part of the second base region.