MOS device with dual gate insulators and method of forming the same

摘要

A MOS device with dual gate insulators has a first gate insulator formed on a predetermined area of a semiconductor substrate, and a second gate insulator formed outside the predetermined area of the semiconductor substrate to surround the first gate insulator. The second gate insulator is thicker than the first gate insulator. In addition, a gate electrode layer is patterned on the dual gate insulators. The bottom center of the gate electrode layer covers the first gate insulator, and the bottom edge of the gate electrode layer extends to cover the second gate insulator.