Complementary field effect transistor

Claim 1

A complementary field effect transistor comprising an N-channel double-diffusion field effect transistor and a P-channel double-diffusion field effect transistor each of which is formed in a corresponding one of two well base regions of a first conductivity type formed with a given interval on a main surface of a semiconductor substrate of a second conductivity type which is opposite to the first conductivity type, said N-channel double-diffusion field effect transistor comprising a first base region of said second conductivity type, a first source region of said first conductivity type formed in said first base region, a first drain region of said first conductivity type formed in said well base region, a first high concentration drain region, and a first gate electrode formed on the semiconductor substrate between said first high concentration drain region and said first source region through a first gate insulating film, and said P-channel double-diffusion field effect transistor comprising a second drain region of said second conductivity type formed in said well base region, a second base region of said first conductivity type having a thickness which is greater than a thickness of said second drain region, a second source region of said second conductivity type formed in said second base region, a second high concentration drain region of said second conductivity type formed in said second drain region, and a second gate electrode formed on the semiconductor substrate between said second high concentration drain region and said second source region through a second gate insulating film.