Semiconductor device and method of manufacturing semiconductor device

A semiconductor device comprising:

• 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 a first side facing the semiconductor substrate and a second side opposite to the first side, an impurity concentration of the first semiconductor layer being lower than that of the semiconductor substrate, the first semiconductor layer including a high-concentration region of the first conductivity type;
• a first semiconductor region of the first conductivity type, selectively provided in the first semiconductor layer, a peak impurity concentration of the first semiconductor region being higher than that of the first semiconductor layer;
• a first base region of a second conductivity type, selectively provided in the first semiconductor layer;
• a second semiconductor layer of the second conductivity type, provided on a surface of the first semiconductor layer at the second side thereof;
• a second semiconductor region of the first conductivity type, selectively provided in the second semiconductor layer at a surface thereof;
• a trench that penetrates the second semiconductor layer and the second semiconductor region, and reaches the first semiconductor layer;
• a gate electrode provided in the trench, via a gate insulating film;
• an interlayer insulating film provided on the gate electrode;
• a second base region in contact with a bottom of the trench;
• a first electrode in contact with the second semiconductor layer and the second semiconductor region;
• and
• a second electrode provided on the back surface of the semiconductor substrate, wherein
• the trench includes a plurality of trench portions, each of which extends in a first direction;
• the first semiconductor region is provided between adjacent two of the plurality of trench portions, and is closer to the second electrode than is the first base region, the first semiconductor region including a plurality of first semiconductor region portions;
• the first base region is in direct contact with the bottom of the trench, and extends along a second direction that intersects the first direction, at a depth that is the same as the bottom of the trench, or is closer to the second electrode than is the bottom of the trench, the first base region including a plurality of first base region portions;
• the second base region extends in the first direction in parallel to the plurality of trench portions, the second base region including a plurality of second base region portions;
• and
• a width of each of the first base region portions or a width of each of the second base region portions is wider than a width of each of the first semiconductor region portions.