| 摘要 |
An operation of erasing data in a memory block of a nonvolatile semiconductor memory device employs an operation of collectively applying an erase pulse to the memory block, and an operation of collectively applying an erase pulse to a limited region in the memory block. Thereby, the number of the erase pulses excessively applied to the memory cells, which passed verify, can be reduced as compared with a conventional structure so that the number of the memory cells to be subjected to over-erase recovery write decreases, and the total block erase time can be short.
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