| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the problem that an erroneous writing occurs when the threshold voltage of a memory cell becomes equal to or less than a prescribed voltage after an erasing. <P>SOLUTION: A first sense latch circuit S/L1 is connected to bit lines BLE and BLO through transistors QNH3 and QNL1 and a second sense latch circuit S/L2 is connected to the lines through transistors QNH4 and QNL2. After erasing the data in a memory cell, data are read for excessive erasing detection and the read data are latched to the circuit S/L1. The presence and/or the absence of an excessively erased cell is detected from the latched data. When an excessively erased cell exists, a soft writing is conducted so that the threshold voltage is converged into a prescribed range. <P>COPYRIGHT: (C)2004,JPO</p> |
