Method of making a nonvolatile semiconductor memory device

Abstract

A nonvolatile semiconductor memory device and the method thereof is disclosed. The nonvolatile semiconductor memory device comprises a first conductive type semiconductor substrate, a field oxide film formed on the semiconductor substrate to define an active region, a source region and a drain region which are separated by a channel region near the surface of semiconductor substrate of the active region and diffused with an impurity of the opposite conductive type to the semiconductor substrate, a thin gate insulating film formed on the channel region and partially on the source and drain regions, a first conductive layer formed on the gate insulating film and provided as a floating electrode for accumulating charges, an interlayer insulating film formed on the first conductive layer, and a second conductive layer formed on the interlayer insulating film and provided as a control electrode. In the nonvolatile semiconductor memory device, cell characteristics can be greatly improved by thickening the exposed edge of the gate insulating film damaged during fabrication by the reoxidation process, after the formation of the patterns of the floating gate electrode and the control gate electrode.