Silicon carbide semiconductor device and method of manufacturing the same

A silicon carbide semiconductor device comprising an MOSFET that includes:

• a well region formed in an upper surface portion of a silicon carbide semiconductor layer;
• a source region formed in an upper surface portion of said well region;
• a gate oxide film formed on said well region and said source region;
• and
• a gate electrode formed on said gate oxide film,
• wherein an impurity concentration at an upper surface portion of said source region is 1×1018 cm−3 or more, and
• said gate oxide film is formed by performing at least dry oxidation or CVD process first.

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

• (a) forming a well region of an MOSFET by ion-implanting impurities of a first conductivity type into an upper surface portion of a silicon carbide semiconductor layer;
• (b) forming a source region of said MOSFET by ion-implanting impurities of a second conductivity type into an upper surface portion of said well region;
• (c) forming a gate oxide film of said MOSFET on said well region and said source region;
• and
• (d) forming a gate electrode of said MOSFET on said gate oxide film,
• wherein a concentration of said impurities of said second conductivity type ion-implanted in said step (b) is 1×1018 cm−3 or less at an upper surface portion of said source region.

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

• (a) forming a well region of an MOSFET by ion-implanting impurities of a first conductivity type into an upper surface portion of a silicon carbide semiconductor layer;
• (b) forming a source region of said MOSFET by ion-implanting impurities of a second conductivity type into an upper surface portion of said well region;
• (c) forming a gate oxide film of said MOSFET on said well region and said source region;
• and
• (d) forming a gate electrode of said MOSFET on said gate oxide film, wherein a concentration of said impurities of said second conductivity type ion-implanted in said step (b) is 1×1018 cm−3 or more at an upper surface portion of said source region, and
• in said step (c), said gate oxide film is formed by performing at least dry oxidation or CVD process first.