Patent ID: 7132332

Claim:
A manufacturing method of a semiconductor memory device comprising the steps of: forming a tunnel insulating film on a semiconductor substrate; forming sequentially an Al 2 O 3 film, an insulating film, and a material film of a gate electrode on the tunnel insulating film; forming a gate electrode by processing the material film of the gate electrode, the insulating film, and the Al 2 O 3 film into a planar shape of the gate electrode; making a retreat of an outer edge of the Al 2 O 3 film to be smaller than an outer edge of the gate electrode by performing isotropic etching to the Al 2 O 3 film so as to form a pair of spaces under the insulating film; forming charge storage layers respectively in the pair of spaces; and forming a source region and a drain region sandwiching the gate electrode in plain view, as a pair, on a surface of the semiconductor substrate.