Patent ID: 8071449

Claim:
A semiconductor storage device manufacturing method comprising: forming on a semiconductor substrate a plurality of word lines separated by a predetermined interval, each including a first insulating film, a charge storing layer, a second insulating film and a control gate electrode layered in the stated order, and a selection transistor at each end of each of the plurality of word lines at a location adjacent to a plurality of memory regions; forming a first oxide film so as to cover the word lines, the selection transistors and the semiconductor substrate; forming, on the first oxide film, a high-permittivity film which includes a metal oxide and has a higher permittivity than the first oxide film; forming a second oxide film on the high-permittivity film so as to be embedded in gaps between the word lines; removing the second oxide film, the high-permittivity film and the first oxide film so as to expose a surface of the semiconductor substrate between adjacent selection transistors and a surface of the semiconductor substrate between the selection transistors and the word lines adjacent to the selection transistors, and forming sidewall films made up of the first oxide film, the high-permittivity film and the second oxide film on sidewall portions of the selection transistors and on sidewall portions which are of the word lines adjacent to the selection transistors and oppose the selection transistors; forming a nitride film so as to cover the sidewall films and the semiconductor substrate; forming a third oxide film so as to be embedded between the selection transistors and between the selection transistors and the word line adjacent to the selection transistors; removing the third oxide film and the nitride film so as to expose upper surfaces of the control gate electrodes and an upper surface of the second oxide film; removing the second oxide film; and forming a fourth oxide film so as to cover an upper portion of regions from which the second oxide film has been removed.