Patent ID: 6943074

Claim:
A method for manufacturing a nonvolatile semiconductor memory device comprising: forming a first polysilicon film over a semiconductor substrate with a gate insulating film formed therebetween; forming a first insulating film on the first polysilicon film; forming a second polysilicon film on the first insulating film; forming a second insulating film on the second polysilicon film; forming a third polysilicon film on the second insulating film; forming a mask material on the third polysilicon film; a first etching process which etches the third polysilicon film and the second insulating film by using the mask material as a mask, the first etching process forming a control gate; a second etching process which etches the second polysilicon film to the first insulating film by using the mask material as a mask under a condition where a greater selection ratio to the first insulating film is satisfied the second etching process forming a first floating gate; and a third etching process which etches the first polysilicon film by using the mask material as a mask under a condition where a greater selection ratio to the sate insulating film is satisfied, the third etching process forming a second floating gate.