SEMICONDUCTOR DEVICE AND PRODUCING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor device having a multi-gate insulating film and a producing method therefor. SOLUTION: This semiconductor device is provided with a device isolation area 307 formed in the prescribed area of a wafer 301 having a main surface, at least one first active area 1a and at least one second active area 1b limited by the device isolation area 307, first gate insulating film 305a formed on the surface of the first active area 1a, second gate insulating film 305b formed on the surface of the second active area 1b while having thickness thinner than the first gate insulating film 305a, and device isolation film 309 covering the entire side walls of the first and second gate insulating films 305a and 305b while filling the device isolation area 307.