Patent ID: 7662696

Claim:
A method for fabricating a semiconductor device, the method comprising: (a) forming a laminated film by performing the following steps at least twice: depositing an insulator made of silicon oxide over a semiconductor substrate by a chemical vapor deposition method; and performing a plasma treatment to said deposited insulator in an atmosphere containing oxygen atoms; (b) patterning said laminated film so that a relatively thick insulator comprised of said laminated film can be left at least in a thick-film region over said semiconductor substrate; (c) forming a relatively thin insulator in a thin-film region over said semiconductor substrate; and (d) forming gate electrodes in said thick-film region and said thin-film region, wherein said plasma treatment is a treatment with plasma mainly comprised of ions containing oxygen atoms, and wherein said plasma treatment is performed under a condition that the ratio of ions in the plasma is larger than that of radicals.