Power semiconductor device and method for manufacturing same

A power semiconductor device comprising:

• a semiconductor substrate of a first conductivity type;
• a drift layer of the first conductivity type which is formed on a first main surface side of said semiconductor substrate;
• a cell region formed in a part of said drift layer and comprising a plurality of unit cells;
• a well region of a second conductivity type which is formed in another part of said drift layer;
• a gate insulating film formed on said cell region;
• a field insulating film formed on said well region;
• a gate electrode formed over said cell region and over said well region;
• a source pad for electrically connecting said cell region and said well region through a source contact hole formed on said cell region and a well contact hole formed on said well region;
• a gate pad electrically connected to said gate electrode;
• and
• a drain electrode formed on a second main surface of said semiconductor substrate wherein the well contact hole defines opposite sides, with the cell region on one of said sides of the well contact hole and the gate electrode on another of said sides of the well contact hole,
• wherein the field insulating film under an entire portion of the gate electrode at said another side is thicker than the gate insulating film at said one side over said well region.