Patent ID: 7939854

Claim:
Semiconductor device with a substrate and a semiconductor body of silicon comprising a bipolar transistor with an emitter region, a base region and a collector region which are respectively of the n-type conductivity, the p-type conductivity and the n-type conductivity by the provision of suitable doping atoms, wherein the base region comprises a mixed crystal of silicon and germanium, the base region is separated from the emitter region by an intermediate region of silicon having a doping concentration which is lower than the doping concentration of the emitter region and with a thickness smaller than the thickness of the emitter region and the emitter region comprises a sub-region comprising a mixed crystal of silicon and germanium which is positioned at the side of emitter region remote from the intermediate region, characterized in that the sub-region comprising the mixed crystal of silicon and germanium extend substantially through the whole emitter region up to the interface with the intermediate region and the doping atoms of the emitter region are arsenic atoms.