| 摘要 |
PROBLEM TO BE SOLVED: To provide a structure to improve a coupling ratio of a memory cell, reduce fluctuation, and also improve breakdown voltage. SOLUTION: A silicon substrate 1 is isolated into active regions 3 with STI2 that is formed by embedding a silicon oxide film 4. At the upper part of the active region 3, a tunnel insulating film 5, a floating gate electrode 6, an electrode insulating film 7, and a control gate electrode 8 are laminated. The end 4b at both ends of a recess 4a of the silicon oxide film 4 is set in a way that a film thickness d1 of the part opposed to the active region 3 and floating gate electrode 6 is almost equal to the film thickness d2 of the electrode insulating film 7. The bottom surface 4c at the center of the silicon oxide film 4 is formed as the concave part at a location lower than the upper surface of the silicon substrate 1. COPYRIGHT: (C)2009,JPO&INPIT
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