Patent ID: 7833856

Claim:
A method for manufacturing a semiconductor device, comprising: forming a first insulating layer on a semiconductor substrate; forming a first conductive layer as a floating gate on the first insulating layer; forming a second insulating layer on the first conductive layer; forming a trench for isolation by etching the second insulating layer, the first conductive layer, the first insulating layer, and the semiconductor substrate; forming a third insulating layer within the trench; removing a part of the third insulating layer until a surface of the third insulating layer is lower than an upper surface of the first conductive layer but higher than a lower surface of the first conductive layer; removing the second insulating layer; forming a fourth insulating layer as an interelectrode insulating film on the first conductive layer and the third insulating layer; and forming a second conductive layer as a control gate on the fourth insulating layer, wherein said forming the fourth insulating layer includes: forming a first film mainly including silicon and oxygen; forming, on the first film, a second film mainly including silicon and nitrogen and having a composition ratio between the silicon and the nitrogen where silicon is in excess of a stoichiometric composition; and forming a third film mainly containing silicon and oxygen on the second film.