Patent ID: 6921947

Claim:
The semiconductor device comprising: a semiconductor substrate; an isolation insulating film selectively located in a surface of said semiconductor substrate; and first and second transistors located respectively on first and second active regions which are defined by and in direct contact with said isolation insulating film, said first transistor having a first gate insulating film of a first thickness which is selectively located on said first active region, said second transistor having a second gate insulating film of a second thickness which is selectively located on said second active region, said first thickness being greater than said second thickness, said isolation insulating film having a recessed portion in an edge portion on the side of said first active region, said recessed portion being located around said first active region, a depth of said recessed portion is defined as a vertical height between a main surface of said first active region and a deepest part of said recessed portion, and is not less than 10 nm.