Patent ID: 7253476

Claim:
A semiconductor device comprising: a layer with low electrical resistance; a semiconductive substrate region on the layer with low electrical resistance; the semiconductive substrate region providing a current path when the semiconductor device is ON and being depleted when the semiconductor device is OFF; the semiconductive substrate region comprising regions of a first conductivity type and regions of a second conductivity type and a layer with high electrical resistance, the layer with high electrical resistance being a further semiconductive substrate region between the regions of a first conductivity type and the regions of a second conductivity type; the regions of the first conductivity type and the regions of the second conductivity type being arranged alternately with each other, and being in contact with each other; a first major surface above the semiconductive substrate region; a second major surface on the back surface of the layer with low electrical resistance; one or more trenches formed in depth from the first major surface to at least portions of the regions of a first conductivity type of the semiconductive substrate region; one or more insulating films are formed inside of the trench; and one or more insulators or one or more electrodes are buried in the trenches enough to cover over the entrances of the trenches.