| 摘要 |
A silicon dioxide film, located over an active region in a well, is annealed at 1050° C. within an N2O ambient, thereby diffusing nitrogen into the silicon dioxide film and forming a nitrogen-containing silicon dioxide film. Next, two polysilicon films, interposing an ONO film therebetween, are deposited and then those films are patterned. In this manner, a memory gate electrode section, consisting of floating gate electrode, interelectrode insulating film and control gate electrode, is formed on the nitrogen-containing silicon dioxide film as a tunnel insulating film. At the same time, a select gate electrode section is also formed beside the memory gate electrode section. Then, p-type source/drain regions and intermediate diffused region are defined below these electrode sections. In this structure, electrons can be injected through a particular part of the tunnel insulating film and holes are trapped in a limited region of the tunnel insulating film.
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