Patent ID: 6355971
Filing Date: 2002-03-12
Classification: H01L

Abstract:
A semiconductor switch device in the form of a bipolar transistor comprising a semiconductor body in which a base region of a first conductivity type is present between emitter and collector regions that are of an opposite second conductivity type and that form respective emitter-base and base-collector p-n junctions with the base region, wherein the base region includes the following structure of three zones in between the emitter region and the collector region:a high-doped zone that has a higher doping concentration of the first conductivity type than a low-doped zone of the base region, and a distinct additional zone between the low-doped and high-doped zones, the low-doped zone comprises a body portion having a substantially uniform doping concentration of the first conductivity type which forms the base-collector p-n junction with the collector region, the higher doping concentration of the high-doped zone forms the emitter-base p-n junction with the emitter region and decreases towards the additional zone over a part of the thickness of the body, and the additional zone has an additional doping concentration of the first conductivity type which is lower than the doping concentration of the high-doped zone and which decreases towards the low-doped zone, the additional zone providing a path for extracting charge carriers from the low-doped zone when the transistor is being switched off.