Patent ID: 8076718

Claim:
An insulation gate type semiconductor device including a body region which is positioned on an upper surface inside a semiconductor substrate and is a first conductive type semiconductor; and a drift region which is in contact with the downward of the body region and is a second conductive type semiconductor; comprising: a first trench portion group passing through the body region in the thickness direction of the semiconductor substrate, positioned in a cell area, and each gate trench of the first trench portion group internally incorporating a first gate electrode; first floating regions enclosed by the drift region and surrounding a bottom portion of at least one trench portion in the first trench portion group, which is the first conductive type semiconductor; a second trench portion group passing through the body region in the thickness direction of the semiconductor substrate, positioned in a terminal area surrounding the cell area, and formed to be annular so as to surround the cell area when being viewed from above; and second floating regions enclosed by the drift region and surrounding a bottom portion of at least one trench portion in the second trench portion group, which is the first conductive type semiconductor; wherein the semiconductor device is adapted such that electric field strength peak at two places in the semiconductor substrate in a thickness direction: at a PN junction between the first or second floating regions and the drift region; and at a PN junction between the body region and the drift region; wherein a second gate electrode is internally incorporated in at least the innermost positioned trench portion in the second trench portion group; wherein a lower end of the second gate electrode in the second trench portion group is equal to a lower end of the first gate electrode in the first trench group in a position in the substrate in the thickness direction.