Silicon carbide semiconductor device

A silicon carbide semiconductor device comprising:

• a silicon carbide substrate having a main surface;
• and
• a gate insulating film on the silicon carbide substrate,
• the silicon carbide substrate including
• a first impurity region having n type,
• a second impurity region in contact with the first impurity region and having p type,
• a third impurity region, on the first impurity region and the second impurity region, having an impurity concentration higher than that of the first impurity region, and having n type,
• a body region on the third impurity region and having p type, and
• a source region, on the body region, separated from the third impurity region by the body region, and having n type, wherein
• the main surface is provided with a trench defined by a side surface and a bottom surface continuous with the side surface,
• the gate insulating film is in contact with the source region, the body region and the third impurity region at the side surface, and is in contact with the third impurity region at the bottom surface,
• when viewed in a direction perpendicular to the main surface, the second impurity region contains the bottom surface, and an area of the second impurity region is greater than an area of the bottom surface, and is not more than three times the area of the bottom surface,
• an impurity concentration of the second impurity region exceeds 1×1019 cm−3, and is not more than 1×1021 cm−3,
• when viewed in the direction perpendicular to the main surface, an outer edge of the second impurity region is spaced from an outer edge of the bottom surface around an entire periphery of the bottom surface, and
• in a direction parallel to the main surface, a width of an opening in the trench is greater than a width of the bottom surface and smaller than a width of the second impurity region.

A silicon carbide semiconductor device comprising:

• a silicon carbide substrate having a main surface;
• and
• a gate insulating film on the silicon carbide substrate,
• the silicon carbide substrate including
• a first impurity region having n type,
• a second impurity region in contact with the first impurity region and having p type,
• a third impurity region, on the first impurity region and the second impurity region, having an impurity concentration higher than that of the first impurity region, and having n type,
• a body region on the third impurity region and having p type, and
• a source region, on the body region, separated from the third impurity region by the body region, and having n type, wherein
• the main surface is provided with a trench defined by a side surface and a bottom surface continuous with the side surface,
• the gate insulating film is in contact with the source region, the body region and the third impurity region at the side surface, and is in contact with the third impurity region at the bottom surface,
• when viewed in a direction perpendicular to the main surface, the second impurity region contains the bottom surface, and an area of the second impurity region is greater than an area of the bottom surface, and is not more than three times the area of the bottom surface,
• an impurity concentration of the second impurity region exceeds 1×1019 cm−3, and is not more than 1×1021 cm−3,
• when viewed in the direction perpendicular to the main surface, an outer edge of the second impurity region is spaced from an outer edge of the bottom surface around an entire periphery of the bottom surface, and
• in a direction parallel to the main surface, a width of the second impurity region is greater than a width of the bottom surface and smaller than a width of an opening in the trench.