Patent ID: 7192840

Claim:
A method of fabricating a semiconductor device, having a silicon layer disposed on an insulating film, the method comprising: oxidizing a surface of the silicon layer to form a pad oxide film; passing oxygen ions into an upper surface of the pad oxide film, and out of a lower surface of the pad oxide film to implant the oxygen ions into selected parts of the silicon layer that are in direct contact with the lower surface of the pad oxide film, directly under, and completely covered by the pad oxide film, wherein the implanted oxygen ions have a peak concentration in a lower half of the silicon layer, the peak concentration being centered above the insulating film, so that all other concentrations of the implanted oxygen ions, both above and below the lower half of the silicon layer, are less than the peak concentration; and oxidizing the selected parts of the silicon layer, into which the oxygen ions have been implanted, and while the selected parts are still covered by the pad oxide film, to form isolation regions dividing the silicon layer into a plurality of mutually isolated active regions.