Patent ID: 6878998

Claim:
A semiconductor device comprising: a semiconductor substrate of a first conductivity type; a first region of a second conductivity type formed on and in direct contact with said semiconductor substrate; a second region of the second conductivity type formed at and near the surface of said first region; a third region of the first conductivity type formed at and near the surface of said first region, and surrounding said second region; a first electrode portion formed on the surface of said third region located between said first and second regions with an insulating film therebetween; a second electrode portion connected to said second region; a third electrode portion connected to said first region and spaced by a distance from said third region; a fourth region of the first conductivity type formed at and near the surface of said first region between said third electrode portion and said third region; wherein, a position of an interface between the first region and the fourth region in a depth direction changes for a cross section crossing a region along a direction substantially orthogonal to the direction of the current flow; and a fifth region of the second conductivity type formed between the semiconductor substrate of the first conductivity type and the first region of the second conductivity type, the fifth region having an impurity concentration that is higher than the impurity concentration of the first region and extending toward the first region.