Patent ID: 7005678

Claim:
A silicon carbide semiconductor device comprising: a semiconductor substrate including a base substrate, a first semiconductor layer, a second semiconductor layer and a third semiconductor layer, which are laminated in this order; a cell portion disposed in the semiconductor substrate and providing an electric part forming portion; and a periphery portion surrounding the cell portion, wherein the base substrate has a first conductive type and is made of silicon carbide, wherein the first semiconductor layer is disposed on the base substrate, has the first conductive type, and is made of silicon carbide with a low impurity concentration lower than the base substrate, wherein the second semiconductor layer has a second conductive type and is made of silicon carbide, wherein the third semiconductor layer has the first conductive type and is made of silicon carbide, wherein the periphery portion includes a trench, which penetrates the second and the third semiconductor layers, reaches the first semiconductor layer, and surrounds the cell portion so that the second and the third semiconductor layers are divided by the trench substantially, and wherein the periphery portion further includes a fourth semiconductor layer having the first conductive type and disposed on an inner wall of the trench.