Patent ID: 7312124

Claim:
A method of manufacturing a semiconductor device, comprising: preparing a support substrate; covering a surface of said support substrate with a first insulating film; covering a surface of said first insulating film with a second insulating film; removing said second insulating film from a region other than first and second predetermined regions; forming a field region at said region other than said first and second predetermined regions by subjecting said support substrate to thermal oxidation; covering an entirety of said first and second predetermined regions and said field region with a third insulating film; covering a surface of said third insulating film with a fourth insulating film; removing said third and fourth insulating films on said first and second predetermined regions until said second insulating film is exposed, so that said third insulating film remains on said field region; removing said first and second insulating films on said first and second predetermined regions, so that said third insulating film remains on said field region; forming a first gate insulating film in said first predetermined region; forming a second gate insulating film in said second active region, said second gate insulating film being thicker than said first gate insulating film; and forming respectively gate electrodes over said first and second predetermined regions.