Patent ID: 8426267

Claim:
A method of manufacturing a semiconductor device comprising a first MIS transistor in a first region of a semiconductor substrate, and a second MIS transistor including a resistor in a second region of the semiconductor substrate, comprising: thermally oxidizing the semiconductor substrate to form a first insulating film in the first region and the second region; removing the first insulating film in the first region, and in a region for the resistor in the second region; thermally oxidizing the semiconductor substrate to form a first gate insulating film in the first region and the region for the resistor, and additionally oxidizing the first insulating film in the second region other than the region for the resistor to form a second gate insulating film; forming a first gate electrode on the first gate insulating film and a second gate electrode on the second gate insulating film; implanting an impurity into the semiconductor substrate in the first region and the region for the resistor with the first gate electrode as a mask to form a first impurity doped layer; and implanting an impurity into the semiconductor substrate in the second region with the second gate electrode as a mask to form a second impurity doped layer, the first impurity doped layer and the second impurity doped layer being formed in the region for the resistor.