Electrically erasable and programmable read only memory device and manufacturing therefor

Abstract

A fabrication method for an electrically erasable programmable read only memory is described in which the memory cell has a sharp-cornered polysilicon pillar in junction with the source region to enhance the source side Fowler-Nordheim tunneling effect. The fabrication method sequentially forms an oxide layer and a silicon nitride on a silicon substrate, and then patterns the oxide layer and the silicon nitride layer to form a plurality of trenches. A first doped polysilicon layer is then formed on the substrate and fills the trenches. A wet oxidation is then conducted to grow an oxide layer on the first doped polysilicon layer, from which a sharp-cornered doped polysilicon layer results. A first dielectric layer is further formed on the substrate and the doped polysilicon layer, followed by forming a floating gate on the first dielectric layer. After this, a second dielectric layer is formed on the substrate, covering the floating gate, and a control gate is formed on the second dielectric layer.