Patent ID: 7317213

Claim:
A semiconductor device comprising: a center region, in which a semiconductor switching device is disposed; a periphery region surrounding the center region; and a semiconductor layer including a plurality of pairs of a first region having a first conductive type and a second region having a second conductive type, wherein the semiconductor layer is disposed from the center region to the periphery region, the first and the second regions extend in a thickness direction of the device, the first and the second regions are alternately aligned in a plane perpendicular to the thickness direction of the device, the first region includes a first impurity amount, and the second region includes a second impurity amount, the periphery region includes an utmost outer periphery pair of the first and the second regions and an utmost inner periphery pair of the first and the second regions, the utmost inner periphery pair is disposed next to the center region, and the utmost outer periphery pair is disposed on outmost of the periphery region, the utmost outer periphery pair has a difference between the second impurity amount of the second region and the first impurity amount of the first region, the difference which is smaller than a maximum difference between the second impurity amount and the first impurity amount of another pair of the first and the second regions in the periphery region, and the utmost inner periphery pair has a difference between the second impurity amount of the second region and the first impurity amount of the first region, the difference which is larger than a difference between the second impurity amount and the first impurity amount of a pair of the first and the second regions in the center region.