Patent ID: 8809942

Claim:
A semiconductor device, comprising: a first trench structure in which a first trench is provided in a surface of a device termination portion of a first semiconductor layer of a first conductive type that includes a device portion and the device termination portion, a silicon dioxide film (SiO 2 film) is provided on bottom and side surfaces of the first trench, and a first insulator is buried in the first trench in such a manner to cover the first trench via the silicon dioxide film (SiO 2 film); a second semiconductor layer of a second conductive type provided on the surface of the first semiconductor layer, the second semiconductor layer being in contact with a device portion side of the first trench, the second semiconductor layer having a smaller depth than the first trench; and a second trench structure in which a second trench is provided in the surface of the first semiconductor layer, the second trench being in contact with a side of the first trench opposite to the second semiconductor layer and wider than the first trench, and a second insulator is buried in the second trench in such a manner to cover the second trench, wherein the second trench extends in such a manner to cover a bottom portion of the first trench, and a portion of the second trench below the bottom portion of the first trench has a taper shape inclined toward the device portion.