Patent ID: 7329577
Filing Date: 2008-02-12
Classification: H01L

Abstract:
1. A method of manufacturing a nonvolatile semiconductor storage device, comprising: a first step of successively forming a first insulating film and a first polysilicon layer on a semiconductor substrate, and implanting nitrogen ions into a front surface of the first polysilicon layer; a second step of patterning the first polysilicon layer and the first insulating film into the shape of a band; a third step of thermally oxidizing the patterned band-shaped first polysilicon layer, thereby to form a second insulating film which is thicker at side surfaces of the first polysilicon layer than at the front surface thereof; a fourth step of forming a second polysilicon layer on a front surface of the semiconductor substrate formed with the second insulating film; and a fifth step of performing patterning so as to form each storage element of the nonvolatile semiconductor storage device as including the first insulating film, a floating gate electrode made of the first polysilicon layer, the second insulating film, and a control gate electrode made of the second polysilicon layer.