Insulated gate semiconductor device and method of manufacturing same

An insulated gate semiconductor device, comprising:

• a drift layer of a first conductivity type made of a semiconductor material having a wider bandgap than silicon, a top surface of the semiconductor material having an off-angle;
• a base region of a second conductivity type made of said semiconductor material, disposed above the drift layer;
• a first high-impurity region of the first conductivity type, embedded in a top of the base region and having a higher impurity density than the drift layer, wherein a trench is provided penetrating the first high-impurity region and the base region;
• a gate insulating film disposed on side surfaces and a bottom surface of the trench;
• an embedded gate electrode embedded inside the trench, with the gate insulating film being interposed between the trench and the embedded gate electrode;
• a second high-impurity region of the first conductivity type made of said semiconductor material, disposed on a bottom surface side of the drift layer;
• a gate bottom protection region of the second conductivity type, embedded in the drift layer at a bottom of the trench;
• and
• a base bottom embedded region of the second conductivity type, embedded in the drift layer below the base region separately from the gate bottom protection region, and having a higher impurity density than the base region,
• wherein a cross-section of the base bottom embedded region has a trapezoid-shaped portion on at least a bottom side of the base bottom embedded region, an upper base and a lower base of the trapezoid are parallel, and a virtual straight line that connects a midpoint of the upper base and a midpoint of the lower base is tilted from a line normal to the top surface of the drift layer towards a direction of the off-angle by a prescribed tilt angle, and
• wherein a bottom surface of the base bottom embedded region is deeper than a bottom surface of the gate bottom protection region.