| 摘要 |
<p>PURPOSE:To prevent the over write-in by narrowing distribution of threshold value voltage after the write-in. CONSTITUTION:After A control circuit 21 writes data in a desired memory cell of a memory cell array 14, verifies threshold value voltage of a memory cell in which data is written. Consequently, when a memory cell having a threshold value voltage higher than the power supply voltage is detected, a erasing voltage generating circuit 20 supplies negative erasing voltage -Vpp to a memory cell in which data is written for a short time, the threshold value voltage is slightly lowered. Therefore, the over write-in is prevented and distribution of threshold value voltage can be narrowed.</p> |
