Silicon carbide semiconductor device and manufacturing method for the same

A silicon carbide semiconductor device comprising:

• a silicon carbide semiconductor substrate;
• a silicon carbide drift layer of a first conductive type provided on the silicon carbide semiconductor substrate;
• first well regions of a second conductive type provided in surface layer portions of the silicon carbide drift layer;
• second well regions of the second conductive type provided adjacent to respective bottom faces of the first well regions;
• source regions of the first conductive type provided in respective surface layer portions of the first well regions;
• a highly concentrated JFET region of the first conductive type formed deeper than the second well regions and provided between the first well regions as well as between the second well regions, wherein an impurity concentration of the first conductive type is larger than that of the silicon carbide drift layer;
• a gate insulating film provided on a top face of the highly concentrated JFET region, top faces of the first well regions, and top faces of the source regions in contact with the highly concentrated JFET region, the first well regions, and the source regions;
• and
• a gate electrode provided on and in contact with the gate insulating film,
• wherein a separation distance W2 of the second well regions is larger than a separation distance W1 of the first well regions by 0.8 μm or more and an impurity concentration of the second conductive type in the first well regions is 1.1 times to 4.2 times an impurity concentration of the second conductive type in the second well regions.