| 摘要 |
<p>PURPOSE:To suppress the variation of threshold value voltage between each bit caused by erasing in a stuck type flash EEPROM semiconductor memory, while to prevent the degradation of a cell current at the time of reading out. CONSTITUTION:At the time of erasing of a stuck type flash EE-PROM, high voltage is impressed to a source terminal or a gate terminal and low voltage is impressed to the source terminal, after all cell is excessively erased, voltage corresponding to a power supply voltage is impressed to a drain terminal or the source terminal. And after threshold level voltage of the cell is converged to a desired value, this time, by impressing the prescribed voltage to the gate terminal, threshold value voltage can be converged to a low value without degrading of a cell characteristic comparing with the case of a drain after excessive erasing or source stress.</p> |
