SEMICONDUCTOR DEVICE AND PRODUCTION METHOD THEREFOR

摘要

A simplified method of producing a multi-voltage semiconductor integrated circuit device. A method of producing a semiconductor device comprising (a) the step of forming a first gate insulation film with a first thickness in the first area of a semiconductor substrate, (b) the step of forming a second gate insulation film with a second thickness smaller than the first thickness in the second area of the semiconductor substrate, (c) the step of forming a gate electrode on the first and second gate insulation films with the first and second gate insulation films an the first and second areas kept unremoved, (d) the step of ion-implanting impurities into the first and second areas via the first and second gate insulation films to add impurities with a first low concentration to the first area and those with a second low concentration higher the first low concentration to the second area, (e) the step of removing the first and second gate insulation films in at least contact-forming areas, and (f) the step of adding high-concentration impurities to areas including the contact-forming areas in the first and second areas.