Nonvolatile semiconductor memory element and method for fabricating the

Abstract

This invention relates to a nonvolatile semiconductor memory element having elevated source and drain regions, a well-shaped floating gate surrounding a control gate, and leveled surface, and a method for fabricating the same. The nonvolatile semiconductor memory element includes a first conduction type substrate having a channel region, an elevated source and drain regions of second conduction type formed to have a step on the substrate separated by the channel region, a floating gate insulation film formed on exposed surfaces of the substrate corresponding to the channel region and the source and drain regions, as well-shaped floating gate formed on the floating gate insulation film on the channel region having a fixed depth and a fixed thickness, a control gate having a fixed thickness formed fully buried in the well of the floating gate so that the floating gate can surround the control gate, and an interlayer insulation film formed between the floating gate and the control gate so as to insulate the floating gate and the control gate.