Patent ID: 7119379

Claim:
A semiconductor device comprising: a first base region which is of a first conductivity type; a second base region which is of a second conductivity type and which is selectively formed on a major surface of the first base region; a stopper region which is of a first conductivity type and which is formed on the major surface of the first base region, the stopper region being a predetermined distance away from the second base region and surrounding the second base region; and a ring region which is of a second conductivity type which is formed on the major surface of the first base region between the second base region and the stopper region, the ring region being spirally around the second base region and electrically connected to the second base region and the stopper region; wherein corner auxiliary members are formed in corner portions of the ring region, the corner auxiliary members being electrically connected to the ring region and having a resistance lower than the ring region, lengths of straight portions which are portions of the ring region excluding the corner portions are equal irrespective of whether the straight portions are on an inner circumferential side or on an outer circumferential side.