Semiconductor device

A semiconductor device comprising:

• a first P-type region having a first impurity concentration;
• an N-channel MOS transistor, in the first P-type region, including
• a source,
• a channel juxtaposed to the source, and
• a drain juxtaposed to the channel;
• a second P-type region on the first P-type region, and having an impurity concentration higher than the first impurity concentration;
• a third P-type region on the first P-type region, and having a side adjacent to the channel and extending from the source to the drain, the third P-type region having a third impurity concentration higher than the first impurity concentration;
• a fourth P-type region on the first P-type region, in an area between the second P-type region and the third P-type region, and having an impurity concentration lower than the third impurity concentration and higher than the first impurity concentration;
• and
• an insulation film having a first thickness in an area on the fourth P-type region, having a second thickness in an area on the second P-type region, the second thickness being smaller than the first thickness, and having a third thickness in an area on the third P-type region, the third thickness being smaller than the first thickness.