Silicon carbide semiconductor device

A silicon carbide semiconductor device, comprising:

• a semiconductor substrate containing silicon carbide and having a first main surface and a second main surface that are opposite to each other, the entire first main surface being flat;
• an active region provided in the semiconductor substrate;
• a termination region provided in the semiconductor substrate, surrounding a periphery of the active region;
• a first semiconductor region of a first conductivity type, provided in the semiconductor substrate, spanning the active region and the termination region;
• a second semiconductor region of a second conductivity type, provided in the active region, between the first main surface and the first semiconductor region;
• a device element structure provided in the active region, and having a pn junction between the first semiconductor region and the second semiconductor region, a current passing through the pn junction flowing through the device element structure;
• a second-conductivity-type peripheral region provided between the first main surface and the first semiconductor region, between the device element structure and the termination region, the second-conductivity-type peripheral region surrounding a periphery of the device element structure;
• a first electrode provided at the first main surface, the first electrode being electrically connected to the second semiconductor region and the second-conductivity-type peripheral region;
• a second electrode provided at the second main surface of the semiconductor substrate, the second electrode being electrically connected to the first semiconductor region;
• a plurality of second-conductivity-type withstand voltage regions provided in the first semiconductor region in the termination region, at a position apart from the first main surface in a depth direction, the second-conductivity-type withstand voltage regions being provided in a concentric shape surrounding the periphery of the active region and being apart from one another in a direction of a normal to the concentric shape;
• and
• a voltage withstanding structure configured by the second-conductivity-type withstand voltage regions and having an overall impurity concentration of the second conductivity type, which gradually decreases in a direction from the active region to the termination region, wherein
• the second-conductivity-type peripheral region has an outer end at a side thereof where the termination region is provided, the outer end of the second-conductivity-type peripheral region being orthogonal to the first main surface,
• bottoms of the second-conductivity-type withstand voltage regions are positioned deeper in the depth direction from the first main surface than is a bottom of the second-conductivity-type peripheral region, and
• a first second-conductivity-type withstand voltage region, which is an innermost one of the second-conductivity-type withstand voltage regions, surrounds the second-conductivity-type peripheral region so as to cover an outer-side corner of the bottom of the second-conductivity-type peripheral region.