Floating-gate nonvolatile semiconductor memory device and method of making

Abstract

The present invention provides a floating-gate non-volatile semiconductor memory device and a method of making the same. The floating-gate non-volatile semiconductor memory device comprises a semiconductor substrate, a source, a drain, a first insulator layer, a first polysilicon layer, a second insulator layer, a second polysilicon layer, a protective layer and sidewalls. The source and drain are disposed on the semiconductor substrate. The first insulator layer is disposed over a region of the semiconductor substrate other than regions corresponding to the source and drain. The first polysilicon layer is disposed over the first insulator layer, forming a floating gate. The second insulator layer is disposed over the first polysilicon layer. The second polysilicon layer is disposed over the second insulator layer, forming a control gate and a wordline. The sidewalls are disposed on two sides of the wordline, and the protective layer is disposed over the second polysilicon layer. A semiconductor junction at a drain region is a P-N junction, while a semiconductor junction at a source region is a metal-semiconductor junction.