| 摘要 |
PROBLEM TO BE SOLVED: To enable adjusting thickness of gate oxide films in such a manner that performance of a circuit is maximized, by forming a damage layer by simple ion implantation. SOLUTION: An element isolation film 12 is formed on a semiconductor substrate 10 having a normal operating region and a high voltage operating region, and a photoresist film pattern 16 is so formed that the high voltage operating region 14 is exposed on the semiconductor substrate 10. Silicon 17 which is electrically inert atom to the semiconductor substrate formed of silicon is ion-implanted by using the photoresist film pattern 16 as a mask. The photoresist film pattern 16 is eliminated, and each gate oxide film is formed on each region. In this case, a gate oxide film of the high voltage operating region is made relatively thicker than that of the normal voltage operating region by forming a damage layer by ion implantation of silicon. |
