Silicon carbide semiconductor device

A silicon carbide semiconductor device, comprising:

• a silicon carbide semiconductor substrate of a first conductivity type, having an active region through which a main current flows and a termination region that surrounds a periphery of the active region in a top view of the silicon carbide semiconductor device;
• a first silicon carbide semiconductor layer of the first conductivity type, provided at a surface of the silicon carbide semiconductor substrate, the first silicon carbide semiconductor layer having an impurity concentration that is lower than an impurity concentration of the silicon carbide semiconductor substrate;
• and
• a first semiconductor region, a second semiconductor region, a third semiconductor region, and a fourth semiconductor region that are formed in the termination region, wherein
• the first semiconductor region is of a second conductivity type,
• the second semiconductor region is of the second conductivity type, and is provided on an outer side of the first semiconductor region in the top view of the silicon carbide semiconductor device, the second semiconductor region having an impurity concentration that is lower than an impurity concentration of the first semiconductor region, the second semiconductor region having a plurality of first small regions of the second conductivity type, the plurality of first small regions having a same impurity concentration as the impurity concentration of the first semiconductor region,
• the third semiconductor region is of the second conductivity type, and is provided on an outer side of the second semiconductor region in the top view of the silicon carbide semiconductor device, the third semiconductor region having an impurity concentration that is lower than the impurity concentration of the first semiconductor region,
• the fourth semiconductor region is of the second conductivity type, and is provided on an outer side of the third semiconductor region in the top view of the silicon carbide semiconductor device, the fourth semiconductor region having a plurality of second small regions of the second conductivity type, the plurality of second small regions having a same impurity concentration as the impurity concentration of the third semiconductor region, and
• the first semiconductor region, the second semiconductor region, the third semiconductor region, and the fourth semiconductor region are provided within the first silicon carbide semiconductor layer.