Data retention loss mechanisms in a 2-bit SONOS type flash EEPROM cell with hot electron programming and hot hole erase are investigated. In erase (low-Vt) state, a threshold voltage drift with storage time is observed after P/E cycling stress. Positive trapped charge creation in the bottom oxide is found to be responsible for the drift. In program (high-Vt) state, data retention loss is attributed mostly to nitride charge escape by Frenkel-Poole emission and oxide trap assisted tunneling. A square-root dependence of the nitride charge loss on electric field is obtained. A Vg-acceleration method for retention lifetime measurement is proposed.
|Number of pages||4|
|Journal||Technical Digest - International Electron Devices Meeting|
|State||Published - 1 Dec 2001|
|Event||IEEE International Electron Devices Meeting IEDM 2001 - Washington, DC, United States|
Duration: 2 Dec 2001 → 5 Dec 2001