| 摘要 |
PROBLEM TO BE SOLVED: To improve data retention characteristics and retention time in a vertical non-volatile semiconductor memory cell. SOLUTION: A trench 5 is formed vertically to the surface of a board 20 from a source area 3 to a drain area 1 in the vertical direction. A first dielectric layer 8 formed on the wall of the trench, a charge accumulation layer 9 formed on the first dielectric layer 8, a second dielectric layer 10 formed on the surface of the charge accumulation layer 9, and control layers 11, 11' formed on the surface of the second dielectric layer 10 are provided. A trench extension part 5' is formed downward of the trench 5, and has a third dielectric layer 6 formed on the surface of the trench and a filling material 7 for at least partially filling the trench extension part 5'.
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