| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method of controlling a threshold of a nonvolatile semiconductor memory device capable of suppressing an adjacency effect. <P>SOLUTION: The method of controlling the threshold in the nonvolatile semiconductor memory device capable of performing writing by applying a writing voltage to a memory cell capable of holding a multivalued state and a wordline, includes: performing writing at least once on at least one of the memory cells with an applied voltage that does not cause excess writing, with verify reading being not performed; and performing verify reading by applying a verify voltage corresponding to a target threshold of the memory cell to a wordline after the writing is performed on the at least one of the memory cells, and, when the threshold of the memory cell is determined to be lower than the target threshold, repeating the writing with the applied voltage that does not cause excess writing and the verify reading until the threshold of the memory cell becomes equal to or higher than the target threshold. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
