Patent ID: 7507632

Claim:
A manufacturing method of a semiconductor device comprising: (a) a step of forming a silicon oxide film on a silicon substrate, and forming a high-k film on the silicon oxide film; (b) a step of forming a gate electrode on the high-k film; (c) a step of etching the gate electrode selectively, with exposing the high-k film in a region other than the lower portion of the gate electrode; (d) after the step (c), a step of nitridation from the surface of the exposed high-k film so that nitrogen is included in the high-k film beneath the gate electrode; and (e) after the step (d), a step of etching the silicon oxide film and exposed high-k film to form a gate insulator, wherein the gate insulator includes more nitrogen at the peripheral side than at the central side of the gate electrode in the gate-length direction of the gate electrode, and includes more nitrogen at the gate electrode side than at the silicon substrate side in the film thickness direction of the gate insulator.