Patent ID: 7662686

Claim:
A method of manufacturing a semiconductor device having a non-volatile memory cell including a word line extending to a first direction and a floating gate, comprising the steps of: (a) forming a plurality of first insulating films over a semiconductor substrate, wherein the first insulating films extend in a second direction opposite to the first direction; (b) after the step (a), forming a first conductive film over the first insulating film and in first grooves formed between each of the first insulating films; (c) after the step (b), removing the first conductive film outside of the first grooves, whereby the first conductive films are left in the first grooves; (d) after the step (c), etching the first insulating films by using the first conductive films as a mask, to form second grooves between each of the first conductive films; (e) after the step (d) forming a second insulating film over the first conductive films and in the second grooves; (f) after the step (e), forming a second conductive film over the second insulating film and in the second grooves, to fill the second grooves with the second insulating film and the second conductive film; (g) after the step (f), forming a third conductive film over the second conductive film; and (h) after the step (g), patterning the third conductive film, the second conductive film, the second insulating film and the first conductive film, respectively, wherein, by the step (h), the word lines including the second and third conductive films are formed, and the floating gates including the first conductive film are formed, and wherein the floating gates are formed so that, for each floating gate, a length of the floating gate in the second direction is longer than a length of the floating gate in the first direction.