Patent ID: 7235476

Claim:
A method of manufacturing a semiconductor device comprising the steps of: forming a first insulating film on first and second regions of a semiconductor substrate; forming a first conductive film on the first insulating film; forming a second insulating film on the first conductive film; forming on the second insulating film a first resist pattern having a first window in a contact region on the first conductive film of the first region; forming a first opening, through which the contact region exposes, in the second insulating film under the first window, by etching the second insulating film while using the first resist pattern as a mask; removing the first resist pattern; forming a third insulating film on the first conductive film exposed from the first opening; forming a second conductive film on the second and third insulating films; forming a second resist pattern having a first resist portion in the first region and a second resist portion in the second region, the first resist portion having a size to cover the first opening; etching the first and second conductive films and the second insulating film while using the second resist pattern as a mask, thus making the first and second conductive film under the first resist portion into a first and second conductor respectively, making the first and second conductive film under the second resist portion into a floating gate and a control gate respectively, and making the second insulating film into an intermediate insulating film; removing the second resist pattern; forming a third resist pattern in the first and second regions, where the third resist pattern having, in the first region, a second window that has a size to encompass the contact region of the first conductor; selectively removing the second conductor under the second window by etching the second conductor while using the third resist pattern as a mask; removing the third resist pattern; exposing the contact region by removing the third insulating film on the contact region of the first conductor; forming an inter-layer insulating film to cover the first conductor; forming a hole in the inter-layer insulating film on the contact region of the first conductor; and forming a conductive plug in the hole, the conductive plug being electrically connected to the contact region of the first conductor.