Patent ID: 7400017

Claim:
A reverse conducting semiconductor device comprising an insulated gate bipolar transistor and a free wheeling diode which are formed on a substrate made of a first conductive type semiconductor, said the free wheeling diode comprising; a second conductive type base layer formed by doping the one surface of said substrate with second conductive type impurities to constitute the insulated gate bipolar transistor, a first conductive type base layer of said first conductive type semiconductor for constituting said insulated gate bipolar transistor, an anode electrode which is an emitter electrode formed on said one surface of said substrate so as to cover a first conductor type emitter layer formed on the part of the second conductive type base layer and the second conductive type base layer, a cathode electrode which is a collector electrode formed on the other surface of the substrate so as to cover the first conductor type base layer and a second conductive type collector layer formed on the part of the first conductor type base layer, wherein a short lifetime region where a lifetime of the carrier is set shorter than the other portion of the first conductive type base layer is formed on a part of the first conductive type base layer.