Semiconductor device and method of manufacturing the same

A semiconductor device comprising:

• a semiconductor substrate;
• a first isolation insulating film isolating a first region from a second region in the semiconductor substrate;
• a second isolation insulating film isolating a third region from a fourth region in the semiconductor substrate;
• first impurity regions formed in the first region, the second region, and the fourth region, the first impurity regions including an impurity of a first conductivity type and having a first depth;
• a second impurity region formed in the third region, the second impurity region including an impurity of a second conductivity type and having a second depth deeper than the first depth;
• a third impurity region formed in the third region, the third impurity region including an impurity of the second conductivity type and having a third depth shallower than the second depth;
• a first transistor formed in the third region, the first transistor including first source/drain regions of the first conductivity type;
• and
• a second transistor formed in the fourth region, the second transistor having second source/drain regions of the second conductivity type.