Silicon carbide semiconductor device

A silicon carbide semiconductor device, comprising:

• a semiconductor substrate of a second conductivity type;
• a first semiconductor layer of a first conductivity type provided on the semiconductor substrate;
• a second semiconductor layer of the second conductivity type provided on a first side of the first semiconductor layer, opposite a second side of the first semiconductor layer facing toward the semiconductor substrate;
• a first semiconductor region of the first conductivity type selectively provided in a surface layer of the second semiconductor layer on a first side of the second semiconductor layer, opposite a second side of the second semiconductor layer facing toward the first semiconductor layer, the first semiconductor region having an impurity concentration that is higher than an impurity concentration of the first semiconductor layer;
• and
• a gate electrode provided opposing at least a part of a surface of the second semiconductor layer between the first semiconductor region and the first semiconductor layer, across a gate insulating film,
• wherein
• protons are implanted in a first region of the semiconductor substrate, the first region spanning a first predetermined distance from a surface of the semiconductor substrate facing toward the first semiconductor layer,
• protons are implanted in a second region of the first semiconductor layer, the second region spanning a second predetermined distance from a surface of the first semiconductor layer on the second side of the first semiconductor layer facing toward the semiconductor substrate,
• protons are implanted in a third region of the first semiconductor layer, the third region spanning a third predetermined distance from a surface of the first semiconductor layer on the first side of the first semiconductor layer facing toward the second semiconductor layer, and
• protons are implanted in a fourth region of the second semiconductor layer, the fourth region spanning a fourth predetermined distance from a surface of the second semiconductor layer on the second side of the second semiconductor layer facing toward the first semiconductor layer.