Semiconductor device, and method for manufacturing the same

A method of manufacturing a silicon carbide semiconductor device, the method comprising:

• preparing a semiconductor substrate including a first n-type semiconductor layer made of silicon carbide and a second n-type semiconductor layer made of silicon carbide on the first n-type semiconductor layer, the second n-type semiconductor layer having a lower impurity concentration than that of the first n-type semiconductor layer;
• forming a first p-type semiconductor layer by irradiating p-type impurity ions to a surface of the semiconductor substrate in a manner such that the first p-type semiconductor layer has a first boundary bottom between the second n-type semiconductor layer and the first p-type semiconductor layer;
• forming a second p-type semiconductor layer by irradiating p-type impurity ions to the surface of the semiconductor substrate in a manner such that the second p-type semiconductor layer has a second boundary bottom between the second n-type semiconductor layer and the second p-type semiconductor layer, the second boundary bottom being at a depth position shallower than the first boundary bottom;
• forming a gate trench in a region where the second p-type semiconductor layer is formed, in a manner such that the gate trench penetrates through the second p-type semiconductor layer and reaches the second n-type semiconductor layer;
• and
• forming a gate insulating layer and a gate electrode in the gate trench.