Data retention behavior of a SONOS type two-bit storage flash memory cell

Author

Tsai, W.J. ; Zous, N.K. ; Liu, C.J. ; Liu, C.C. ; Chen, C.H. ; Tahui Wang ; Pan, S. ; Chih-Yuan Lu ; Gu, S.H.

Author_Institution

Macronix Int. Co., Hsin-Chu, Taiwan

fYear

2001

fDate

2-5 Dec. 2001

Abstract

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.

Keywords

Poole-Frenkel effect; field effect memory circuits; flash memories; hot carriers; tunnelling; 2 bit; EEPROM; Frenkel-Poole emission; SONOS storage flash memory cell; data retention; erase-state threshold voltage drift; hot electron programming; hot hole erase; oxide trap assisted tunneling; positive trapped charge; program-state charge retention loss; retention lifetime measurement; Chaos; Charge carrier processes; EPROM; Electron traps; Flash memory cells; Hot carriers; SONOS devices; Stress; Threshold voltage; Tunneling;

fLanguage

English

Publisher

ieee

Conference_Titel

Electron Devices Meeting, 2001. IEDM '01. Technical Digest. International

Conference_Location

Washington, DC, USA

Print_ISBN

0-7803-7050-3

Type

conf

DOI

10.1109/IEDM.2001.979614

Filename

979614