Internal combustion engine igniter semiconductor device

An internal combustion engine igniter semiconductor device, comprising:

• a semiconductor substrate including a first conductive collector layer, a second conductive buffer layer, and a second conductive base layer in that order, the second conductive buffer layer having a second buffer layer with a higher impurity concentration than that of the second conductive base layer disposed on the second conductive base layer side, and a first buffer layer with a higher impurity concentration than that of the second buffer layer disposed on the first conductive collector layer side;
• an insulated gate bipolar transistor including a first conductive base region disposed on a surface layer of the second conductive base layer of the semiconductor substrate, a gate electrode across a gate insulating film on a surface of the first conductive base region sandwiched between a second conductive emitter region disposed on a surface layer in the first conductive base region and the second conductive base layer surface, and an emitter electrode in common contact with a collector electrode, the second conductive base layer, and the second conductive emitter region on the first conductive collector layer surface;
• a clamp diode between the gate electrode and the collector electrode with the gate electrode side as an anode side;
• and
• a control circuit which, being on the same semiconductor substrate as the insulated gate bipolar transistor, and enclosed in a ring form by an other conductive region connected by wire to the emitter electrode, detects an abnormal condition of the insulated gate bipolar transistor using a signal from the emitter electrode, and prevents a breakdown of the insulated gate bipolar transistor by controlling a gate voltage, wherein
• a total thickness of the first buffer layer and second buffer layer is 50 μm or less, and an overall impurity amount of the two layers is 20×1013 cm−2 or less, and
• the thickness of the first buffer layer is from 1 to 10 μm or less, the impurity concentration of the first buffer layer is in the range of 2×1016 cm−3 to 8×1016 cm−3, the thickness of the second buffer layer is 49 μm or less, and the impurity concentration of the second buffer layer is in the range of 1×1016 cm−3 to 4×1016 cm−3.