Patent ID: 7592232

Claim:
A method for manufacturing a semiconductor device, the method comprising the steps of: forming a dummy gate insulating film and a dummy gate electrode over a semiconductor substrate having a channel forming region; forming source and drain regions in the semiconductor substrate by using the dummy gate electrode as a mask; forming a first insulating film by using an insulating material having higher resistance against a hydrofluoric acid than silicon oxide in such a way that the first insulating film has a thickness larger than a thickness of the dummy gate electrode and covers the dummy gate electrode; forming a second insulating film on the first insulating film by using an insulating material different from the insulating material of the first insulating film; removing the second insulating film from a top surface of the second insulating film until a top part of the first insulating film is exposed; simultaneously removing the first insulating film and the second insulating film that remains, while planarizing the first insulating film and the second insulating film that remains, from a top surface of the first insulating film until the dummy gate electrode is exposed; forming a gate electrode trench by removing the dummy gate electrode and the dummy gate insulating film; forming a gate insulating film on a bottom of the gate electrode trench; and forming a gate electrode by filling an inside of the gate electrode trench above the gate insulating film with an electrically-conductive material, wherein a field effect transistor is formed by the method.