US Patent 7537992 Method for manufacturing flash memory device

A flash memory device incorporating: a semiconductor substrate having an active region and a field region defined therein; a device isolation layer formed in the field region of the substrate; a floating gate having an edge portion overlapping the device isolation layer, the overlapped portion being etched back a depth about equal to a height of a protruding portion of the device isolation layer, the floating gate having a tunneling oxide layer interposed in the active region of the semiconductor substrate; and a gate insulation layer and a control gate sequentially formed on the floating gate.