| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor memory device having improved reliability of data retention. <P>SOLUTION: After a threshold voltage Vth of a memory cell is adjusted within a threshold voltage distribution E, to be set to an erased state, a control circuit writes data. In this case, the data is written by adjusting a threshold voltage Vth to any one of the threshold voltage distribution A<SB>2</SB>-D<SB>2</SB>at final storage processing, after the threshold voltage of a memory cell MC is adjusted within an initial voltage distribution A<SB>1</SB>having a voltage distribution width narrower than the voltage distribution width Vw of the threshold voltage distribution E. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
