Patent ID: 8471267

Claim:
A semiconductor device which has a semiconductor element region that is provided in part of a silicon carbide layer and a guard-ring region that is provided in another part of the silicon carbide layer surrounding the semiconductor element region when seen in a direction perpendicular to a principal surface of the silicon carbide layer, the semiconductor device comprising: an interlayer insulation film which is provided on the principal surface of the silicon carbide layer in the semiconductor element region and the guard-ring region, the interlayer insulation film having a relative dielectric constant of 20 or more; a first protective insulation film provided on the interlayer insulation film in the guard-ring region, the first protective insulation film being electrically insulative; and a second protective insulation film provided on the first protective insulation film, wherein the first protective insulation film has a linear expansion coefficient which is between a linear expansion coefficient of a material of the second protective insulation film and a linear expansion coefficient of a material of the interlayer insulation film, and wherein the semiconductor element region includes a field effect transistor, the field effect transistor comprising: a silicon carbide substrate of a first conductivity type, having the silicon carbide layer on one principal surface thereof; a gate insulation film provided on the principal surface of the silicon carbide layer; a gate electrode provided on the gate insulation film; a source electrode provided on the principal surface of the silicon carbide layer; a drain electrode provided on another principal surface of the silicon carbide substrate; and a pad electrode provided over the gate electrode with the interlayer insulation film interposed therebetween, the pad electrode being electrically connected to the source electrode, the first protective insulation film and the second protective insulation film are not located between the gate electrode and the pad electrode, and the first protective insulation film and the second protective insulation film cover a part of the pad electrode.