To provide a method of manufacturing a nonvolatile semiconductor memory device which can suppress bird's beak near an end of a floating gate and reducing a manufacturing cost, and to provide the nonvolatile semiconductor memory device.
The method includes: a separating step of forming a separated portion 2 on a silicon substrate 1; insulating film forming step of forming a gate insulating film 3 on the main surface of the silicon substrate 1; polysilicon forming step of forming a polysilicon constituting a floating gate 4 on the surface of the gate insulating film 3; first oxide film forming step of forming a first oxidation film 5 on the surface of the polysilicon; nitride film forming step of forming a nitride film 6 on the surface of the first oxide film; etching step of forming a resist 30 on the surface of the nitride film 6 in a nonvolatile memory section, and etching the polysilicon, the first oxide film 5, the nitride film 6 and the gate insulating film 3; and second oxide film forming step of removing the resist and forming an inter-gate insulating film over the entire surface and forming a second oxide film 7 constituting a CMOS gate oxide film.
KATADA MITSUTAKA
YOGO YUKIAKI
Taihei Nonobe