Patent ID: 7648882

Claim:
A method for fabricating a silicon-oxide-nitride-oxide-silicon (SONOS) flash memory, comprising the steps of: preparing a silicon substrate including a silicon oxide-silicon nitride-silicon oxide (ONO) layer, a first polysilicon layer and a first etch stop layer in sequence; etching the first etch stop layer along a direction of bit line; selectively etching the first polysilicon layer with the first etch stop layer as a mask, till the silicon oxide-silicon nitride-silicon oxide (ONO) layer is exposed, the etched first polysilicon layer having an inverse trapezia section along a direction of word line; filling a dielectic layer between portions of the first polysilicon layer, the dielectric layer having a trapezia section along the direction of word line; removing the first etch stop layer; sequentially forming a second polysilicon layer and a second etch stop layer on the surface of the first polysilicon layer and the dielectric layer; etching the second etch stop layer, the second polysilicon layer and the first polysilicon layer along the direction of word line till the silicon oxide-silicon nitride-silicon oxide (ONO) layer is exposed; and removing the second etch stop layer.