Patent ID: 7763504

Claim:
A method for manufacturing a silicon carbide semiconductor device, the method comprising the steps of: preparing a semiconductor substrate including a silicon carbide substrate, a drift layer and a first semiconductor layer, wherein the silicon carbide substrate has a first conductive type, wherein the drift layer has the first conductive type, is made of silicon carbide and is disposed on the silicon carbide substrate, and wherein the first semiconductor layer has the first conductive type, is made of silicon carbide and is disposed on the drift layer; forming a plurality of first trenches 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; forming a gate layer on an inner wall of each first trench by an epitaxial growth method, wherein the gate layer has a second conductive type and is made of silicon carbide; forming a first insulation film on the surface of the semiconductor substrate; forming a gate electrode on the first insulation film, wherein the gate electrode is connected to the gate layer electrically; forming a source electrode on the first insulation film, wherein the source electrode is connected to the first semiconductor layer in the cell portion; and forming a drain electrode connected to the silicon carbide substrate electrically, forming a plurality of second trenches between the step of preparing the semiconductor substrate and the step of forming the source electrode, wherein the second trenches are formed on a region, which is different from the cell portion, and wherein the second trenches have intervals between two neighboring second trenches, each interval being wider than an interval between two neighboring first trenches; and forming a second semiconductor layer on an inner wall of each second trench by an epitaxial growth method, wherein the second semiconductor layer has the second conductive type and is made of silicon carbide, wherein in the step of forming the source electrode, the source electrode is connected to the second semiconductor layer electrically so that a diode is provided, the diode is formed in the region, which is different from the cell portion, is connected to the source electrode electrically, and is provided by the drift layer and the second semiconductor layer, the step of forming the first trenches and the step of forming the second trenches are performed at the same time, and the step of forming the gate layer and the step of forming the second semiconductor layer are performed at the same time.