Insulated gate bipolar transistor

An insulated gate bipolar transistor, comprising:

• a semiconductor substrate;
• an emitter electrode provided on an upper surface of the semiconductor substrate;
• a collector electrode provided on a lower surface of the semiconductor substrate;
• a rectangular trench provided in the upper surface and extending in a rectangular shape at the upper surface;
• a gate insulating film provided in the rectangular trench;
• a gate electrode provided in the rectangular trench, extending in a rectangular shape along the rectangular trench, and insulated from the semiconductor substrate by the gate insulating film;
• and
• an interlayer insulating film insulating the gate electrode from the emitter electrode,
• wherein
• the semiconductor substrate comprises:
• an emitter region of n-type provided in a rectangular region surrounded by the rectangular trench and being in direct contact with the emitter electrode;
• a body contact region of p-type provided in the rectangular region and being in direct contact with the emitter electrode;
• a surface layer body region of p-type provided in the rectangular region, being in direct contact with the emitter electrode, and having a p-type impurity concentration lower than that of the body contact region;
• a separation body region of p-type being in direct contact with the emitter region, the body contact region, and the surface layer body region from below, being in direct contact with the rectangular trench, and having a p-type impurity concentration lower than that of the body contact region;
• a drift region of n-type provided below the separation body region, separated from the emitter region by the separation body region, and being in direct contact with a lower end of the rectangular trench;
• and
• a collector region of p-type provided below the drift region, separated from the separation body region by the drift region, and being in direct contact with the collector electrode,
• the rectangular trench comprises a straight trench which constitutes one side of the rectangular trench,
• the emitter region is in direct contact with the straight trench,
• the surface layer body region is in direct contact with the straight trench in a range adjacent to the emitter region,
• the body contact region is in direct contact with the emitter region from an opposite side to the straight trench,
• the body contact region comprises a first part and a second part protruding toward the emitter region than the first part, and
• a width of the emitter region between the second part and the straight trench is narrower than a width of the emitter region between the first part and the straight trench.