| 摘要 |
PROBLEM TO BE SOLVED: To restrain dispersion of a neutral threshold, when cell current flows into an NAND type memory cell of a nonvolatile semiconductor memory. SOLUTION: Impurity concentration of channel implantation regions 12 (1) to 12 (16) of memory cells M (1) to M (16) constituting an NAND-type memory cell is constituted, so that the impurity concentration increases toward. The direction of a current flow. That is, when cell current does not flow, the neutral threshold of a memory cell M at the source line contact SC side is constituted to be high. Thereby, the changes in the neutral threshold caused by board bias effect when a cell current is made to flow can be cancelled.
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