Patent ID: 7355207

Claim:
A silicon carbide semiconductor device comprising: a semiconductor substrate including a silicon carbide substrate, a drift layer and a first semiconductor layer, which are disposed in this order, where in the silicon carbide substrate has a first conductive type, wherein the drift layer has the first conductive type and is made of silicon carbide, and wherein the first semiconductor layer has the first conductive type and is made of silicon carbide; a plurality of first trenches disposed in a cell portion of the semiconductor substrate, wherein each of the first trenches has a depth from a surface of the first semiconductor layer to the drift layer, and has a rectangular cross section in a vertical direction of the semiconductor substrate; a gate layer disposed on an inner wall of each first trench, wherein the gate layer is made of silicon carbide, has a second conductive type, and has an epitaxial construction; a channel region disposed between the gate layer; a first insulation film disposed on a surface of the semiconductor substrate; a gate electrode disposed on the first insulation film and connected to the gate layer electrically; a source electrode electrically connected to the first semiconductor layer disposed in the cell portion; a drain electrode electrically connected to the silicon carbide substrate a plurality of second trenches disposed in a region, which is different from the cell portion, wherein each second trench has a depth from the surface of the first semiconductor layer to the drift layer, and has an interval between two neighboring second trenches, the interval being wider than an interval between two neighboring first trenches; a second semiconductor layer disposed on an inner wall of each second trench, wherein the second semiconductor layer has the second conductive type and connected to the source electrode electrically, wherein the second semiconductor layer in the second trench and the drift layer provide a diode; a third trench disposed between the cell portion and the diode, wherein the third trench has a depth from the surface of the first semiconductor layer to the drift layer; and a third semiconductor layer disposed on an inner wall of the third trench, wherein the third semiconductor layer has the second conductive type and is made of silicon carbide, and the third semiconductor layer is electrically isolated from the gate electrode and the source electrode.