Insulated gate semiconductor device and method for producing the same

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.