Patent ID: 8362586

Claim:
A semiconductor device, comprising: a semiconductor substrate formed of silicon carbide with an angle between a normal vector on the substrate surface and a <0001> direction or a <000-1> direction is not smaller than 0 degree and not larger than 8 degrees; a first conductive type semiconductor layer formed of the silicon carbide formed on the semiconductor substrate; an active region formed on a surface of the semiconductor layer; a second conductive type first semiconductor region formed on the surface of the semiconductor layer so as to surround the active region; a second semiconductor region provided on the surface of the semiconductor layer so as to contact outside of the first semiconductor region to surround the first semiconductor region, a second conductive type impurity region having impurity concentration and a depth identical to the impurity concentration and the depth of the first semiconductor region is formed into a mesh shape in the second semiconductor region; a first electrode provided on the active region; and a second electrode provided on a backside of the semiconductor substrate, wherein when a dielectric constant of the silicon carbide is set to ε, breakdown field strength of the silicon carbide in the <0001> direction and the breakdown field strength in a <11-20> direction are set to Ec 1 and Ec 2 , respectively, and an elementary electric charge is set to q, a value of integral in a depth direction of the impurity concentration of the first semiconductor region is not smaller than 0.8 εEc 1 /q and not larger than 1.2 εEc 1 /q, and a value obtained by averaging the value of integral in the depth direction of the impurity concentration of the impurity region in the second semiconductor region is not smaller than 0.4 εEc 2 /q and not larger than 1.1 εEc 2 /q.