Patent ID: 7964288

Claim:
A method of manufacturing a semiconductor device, comprising: defining a plurality of stripe-shaped active regions, which are arranged in parallel with each other in the semiconductor substrate, by forming a device isolation insulating film on the semiconductor substrate, the active regions being formed at a distance from each other; forming a tunnel insulating film on the semiconductor substrate in the active region; forming a first conductive film on the tunnel insulating film and the device isolation insulating film; coating a photoresist on the first conductive film; exposing the photoresist by using an exposure mask in which a plurality of stripe-shaped light-shielding patterns are formed on a transparent substrate, where the light-shielding patterns being formed in parallel with each other, and the light-shielding patterns having two or more narrow width portions that becomes smaller in a stepwise fashion toward an end; developing the photoresist to form a plurality of stripe-shaped resist patterns, the resist patterns being formed at a distance from each other, and the resist pattern encompassing the corresponding active region; selectively etching the first conductive film using the resist patterns as a mask; removing the resist pattern; forming an intermediate insulating film on the device isolation insulating film and the first conductive film after removing the resist pattern; forming a second conductive film on the intermediate insulating film; and patterning the first conductive film, the intermediate insulating film, and the second conductive film to form a flash memory cell that is made by forming the tunnel insulating film, a floating gate, the intermediate insulating film, and control gate in this order on the active region, and to form a structure that is made by forming the island-like lower conductor pattern, a segment of the intermediate insulating film, and a dummy conductor pattern in this order on the device isolation insulating film at an end of the active region.