| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor memory device that has a plurality of sub-blocks in a memory string and, even when a part of the sub-blocks is deleted, can prevent the range of a threshold voltage distribution of memory cells of adjacent sub-blocks from increasing.SOLUTION: A memory cell array 11 has a plurality of memory strings which include a plurality of memory cells connected to a word line. The plurality of memory strings are divided into a plurality of sub-blocks for each of which data can be deleted. A control unit 15 changes a verification level that is supplied to a selection word line included in a selected sub-block depending on whether unselected sub-blocks are written or not in writing data.</p> |
