A semiconductor device, comprising:
- a first MOS structure portion having the following elements:
- a semiconductor substrate of a first conductivity type, having a front surface and a back surface opposite to each other;
- a first semiconductor layer of the first conductivity type, provided on the front surface of the semiconductor substrate and having an impurity concentration that is lower than an impurity concentration of the semiconductor substrate, the first semiconductor layer having a first surface and a second surface opposite to each other, the second surface facing the semiconductor substrate;
- a first second-semiconductor-layer of a second conductivity type,
- provided on the first surface of the first semiconductor layer, the first second-semiconductor-layer having a first surface and a second surface opposite to each other, the second surface facing the semiconductor substrate;
- a plurality of first first-semiconductor-regions of the first conductivity type, selectively provided in the first second-semiconductor-layer, at the first surface thereof, each of the first first-semiconductor-regions having a first surface and a second surface opposite to each other, the second surface facing the semiconductor substrate;
- a plurality of first gate insulating films in contact with the first second-semiconductor-layer, each of the first gate insulating films having a first surface and a second surface opposite to each other, the second surface being in contact with the first second-semiconductor-layer;
- a plurality of first gate electrodes provided on the first surfaces of the first gate insulating films;
- a plurality of first first-electrodes provided on the first surface of the first second-semiconductor-layer and the first surface of each of the first first-semiconductor-regions;
- and
- a second electrode provided on the back surface of the semiconductor substrate;
- a second MOS structure portion that detects overcurrent flowing in the first MOS structure portion, the second MOS structure portion including the following elements:
- the semiconductor substrate;
- the first semiconductor layer;
- a second second-semiconductor-layer of the second conductivity type, provided on the first surface of the first semiconductor layer;
- a plurality of second first-semiconductor-regions of the first conductivity type, selectively provided in the second second-semiconductor-layer, at the first surface thereof, each of the second first-semiconductor-regions having a first surface and a second surface opposite to each other, the second surface facing the semiconductor substrate;
- a plurality of second gate insulating films in contact with the second second-semiconductor-layer, each of the second gate insulating films having a first surface and a second surface opposite to each other, the second surface being in contact with the second second-semiconductor-layer;
- a plurality of second gate electrodes provided on the first surfaces of the second gate insulating films;
- a plurality of second first-electrodes provided on the first surface of the second second-semiconductor-layer and the first surfaces of the second first-semiconductor-regions;
- and
- the second electrode;
- a first portion that includes all of the elements of the first MOS structure portion other than the first first-semiconductor-regions and the first gate insulating films, and being located below the first surface of the first first-semiconductor-regions;
- and
- a second portion that includes all of the elements of the second MOS structure portion other than the second first-semiconductor-regions and the second gate insulating films, and being located below the first surface of the second first-semiconductor-regions, wherein
- a structure of at least one of the elements of the first portion that includes any one of a thickness or width thereof is not identical to a structure of a functionally corresponding at least one element of the second portion so that the first MOS structure has a MOS characteristic different from a MOS characteristic of the second MOS structure.