Patent ID: 7812392

Claim:
A semiconductor device comprising: a first first-conductivity-type semiconductor layer; a second first-conductivity-type semiconductor layer provided on a major surface of the first first-conductivity-type semiconductor layer; a third second-conductivity-type semiconductor layer being adjacent to the second first-conductivity-type semiconductor layer, provided on the major surface of the first first-conductivity-type semiconductor layer, and forming a periodic array structure in combination with the second first-conductivity-type semiconductor layer in a horizontal direction generally parallel to the major surface of the first first-conductivity-type semiconductor layer; a first main electrode electrically connected to the first first-conductivity-type semiconductor layer; a fourth second-conductivity-type semiconductor region provided on the third second-conductivity-type semiconductor layer; a fifth first-conductivity-type semiconductor region selectively provided in a surface of the fourth second-conductivity-type semiconductor region; a second main electrode provided in contact with the fifth first-conductivity-type semiconductor region and the fourth second-conductivity-type semiconductor region; a control electrode provided on the fifth first-conductivity-type semiconductor region, the fourth second-conductivity-type semiconductor region, and the second first-conductivity-type semiconductor layer via an insulating film; a sixth semiconductor layer located outside and adjacent to the periodic array structure of the second first-conductivity-type semiconductor layer and the third second-conductivity-type semiconductor layer, provided on the major surface of the first first-conductivity-type semiconductor layer, and having a lower impurity concentration than the periodic array structure; and a trench being adjacent to the sixth semiconductor layer and having a bottom reaching the first first-conductivity-type semiconductor layer, the amount of impurity in the outermost semiconductor layer of the first conductivity type or the second conductivity type adjacent to the sixth semiconductor layer in the periodic array structure being generally half the amount of impurity in the second first-conductivity-type semiconductor layer or the third second-conductivity-type semiconductor layer inside the outermost semiconductor layer.