New write/erase operation technology for flash EEPROM cells to improve the read disturb characteristics

This paper describes the new write/erase operation methods in order to improve the read disturb characteristics for Flash EEPROM cells which are written by channel hot electron injection and erased by F-N tunneling emission from the floating gate to the substrate. The new operation methods is either applying a reverse polarity pulse after each erase pulse or applying a series of shorter erase pulses instead of a long single erase pulse. It is confirmed that by using the above operation methods, the leakage current can be suppressed, and then the read disturb life time after 10⁵ cycles write/erase operation is , more than 10 times longer in comparison with the conventional method. This memory cell by using the proposed write/erase operation method has superior potential for application to 256 Mbit Flash memories as beyond.