| 摘要 |
PROBLEM TO BE SOLVED: To provide a non-volatile semiconductor storage device having high writing and erasing characteristics and capable of holding electric charge for a long period. SOLUTION: An element separation area 12 is formed on the surface of a semiconductor substrate 11. After successively forming a tunnel oxide film 13 and a polysilicon layer which becomes a floating gate 14 in a succeeding process on the surface of the element separation area 12, nitrogen ions are injected to the surface of the polysilicon layer so as to be held only on the surface. Then the polysilicon layer is patterned to form the floating gate 14, and the floating gate 14 is thermally oxidized to form an inter-gate insulating film 15. Since thermal oxidation is suppressed by nitrogen ions, an oxide film on the side face can be formed thicker than an oxide film formed on the surface. Consequently, the inter-gate insulating film 15 on the edge of the floating gate 14 can be formed according to a design, and the non-volatile semiconductor storage device capable of holding electric charge for a long period without exerting an influence to electric writing and erasing can be obtained. COPYRIGHT: (C)2005,JPO&NCIPI
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