Silicon carbide semiconductor device and method of manufacturing same

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

• preparing a silicon carbide substrate, said silicon carbide substrate including a first impurity region having a first conductivity type, a well region being in contact with said first impurity region and having a second conductivity type different from said first conductivity type, and a second impurity region separated from said first impurity region by said well region and having said first conductivity type;
• forming a silicon dioxide layer in contact with said first impurity region and said well region;
• and
• forming a gate electrode on said silicon dioxide layer,
• said step of forming a silicon dioxide layer including the steps of
• forming a silicon-containing-material on said first impurity region,
• oxidizing said silicon-containing-material, and
• oxidizing a surface of said well region sandwiched between said first impurity region and said second impurity region,
• said silicon dioxide layer including a first silicon dioxide region on said first impurity region, and a second silicon dioxide region on said well region sandwiched between said first impurity region and said second impurity region,
• assuming that the thickness of said first silicon dioxide region is a first thickness and the thickness of said second silicon dioxide region is a second thickness, said first thickness being greater than said second thickness.