| 摘要 |
PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor memory device which controls variance of threshold values in a floating gate and prevents deterioration in reliability of retaining data. SOLUTION: In a NOR type nonvolatile semiconductor memory device 30, a plurality of nonvolatile semiconductor element cells 40 are arrayed on a substrate 1 through element isolating regions 50 composed of trench part 5. In each element cell 40, side wall edges 31 of a first floating gate 3 which are formed on the substrate 1 through an oxide film 2 is isolated from an edge 21 of the trench part 5.
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