A NOVEL PROGRAMMING METHOD USING A REVERSE POLARITY PULSE IN FLASH EEPROMS

The data retention characteristics for Flash EEPROM degrade after a la rge number of write and erase cycles due to the increase of the tunnel oxide leakage current. This paper proposes a new write/erase method w hich uses a reverse polarity pulse after each erase pulse. By using th is method, the leakage current can be suppressed. As a result, the rea d disturb time after 10(5) cycles write/erase operation is more than 1 0 times longer in comparison with that of the conventional method. Mor eover, using this method, the endurance cycle dependence of the thresh old voltage after write and erase operation is also drastically improv ed.