Patent ID: 7713805

Claim:
A method of manufacturing a silicon carbide semiconductor device having a metal-oxide semiconductor structure, the method comprising: preparing a substrate made of silicon carbide; forming a channel region made of silicon carbide on an (11-20) face of the substrate, wherein the channel region provides an electric current passage; forming a first impurity region on the substrate on an upstream side of the electric current passage; forming a second impurity region on the substrate on a downstream side of the electric current passage; forming a gate insulation layer on a surface of the channel region; forming a gate electrode on the gate insulation layer to form a semiconductor element; forming a film on the semiconductor element to provide a material of an interlayer insulation layer; performing a reflow process at a temperature about 700° C. or over in a wet atmosphere so that the interlayer insulation layer is formed from the film and an edge portion of the gate electrode is rounded and oxidized, and changing the wet atmosphere into an inert gas atmosphere when the temperature is decreased to a temperature of about 700° C. or lower; providing a first contact hole and a second contact hole at the interlayer insulation layer by performing an wet etching and a dry etching in this order, so that the first contact hole and the second hole reach the first impurity region and the gate electrode, respectively, and each of the first contact hole and the second contact hole has a two-step sidewall including an wet-etched region and a dry-etched region, wherein: the channel region provides a channel of the semiconductor element; and the channel is controlled by controlling a voltage applied to the gate electrode so that an electric current flowing between the first impurity region and the second impurity region is controlled.