Variations of Vt retention loss in a SONOS flash memory due to a current-path percolation effect

Y. L. Chou; Y. T. Chung; Ta-Hui Wang; S. H. Ku; N. K. Zou; Vincent Chen; W. P. Lu; K. C. Chen; Chih Yuan Lu

doi:10.1109/LED.2011.2109031

Variations of V_t retention loss in a SONOS flash memory due to a current-path percolation effect

Y. L. Chou, Y. T. Chung, Ta-Hui Wang, S. H. Ku, N. K. Zou, Vincent Chen, W. P. Lu, K. C. Chen, Chih Yuan Lu

Department of Electronics Engineering

Research output: Contribution to journal › Article › peer-review

1 Scopus citations

Abstract

Discrete nitride program charge loss in a small-area SONOS Flash memory cell during retention is observed. Our measurement shows that a retention V _t of a programmed SONOS cell exhibits a stepwise evolution with retention time. Individual single-program charge-loss-induced threshold voltage shifts (Δ V_t) are characterized. We find the following: 1) The magnitude of Δ V_t exhibits an exponential distribution, which is believed due to a current-path percolation effect caused by random program charges and substrate dopants, and 2) program-state V_t retention loss has large variations in different cells and P/E cycles due to the percolation effect. We develop a Monte Carlo analysis to take into account the distribution of Δ V_t and a tunneling front model to study the spread of a retention V_t distribution in a SONOS Flash memory.

Original language	English
Article number	5723684
Pages (from-to)	458-460
Number of pages	3
Journal	IEEE Electron Device Letters
Volume	32
Issue number	4
DOIs	https://doi.org/10.1109/LED.2011.2109031
State	Published - 1 Apr 2011

Keywords

Percolation
retention loss
single-program charge
SONOS

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title = "Variations of Vt retention loss in a SONOS flash memory due to a current-path percolation effect",

abstract = "Discrete nitride program charge loss in a small-area SONOS Flash memory cell during retention is observed. Our measurement shows that a retention V t of a programmed SONOS cell exhibits a stepwise evolution with retention time. Individual single-program charge-loss-induced threshold voltage shifts (Δ Vt) are characterized. We find the following: 1) The magnitude of Δ Vt exhibits an exponential distribution, which is believed due to a current-path percolation effect caused by random program charges and substrate dopants, and 2) program-state Vt retention loss has large variations in different cells and P/E cycles due to the percolation effect. We develop a Monte Carlo analysis to take into account the distribution of Δ Vt and a tunneling front model to study the spread of a retention Vt distribution in a SONOS Flash memory.",

keywords = "Percolation, retention loss, single-program charge, SONOS",

author = "Chou, {Y. L.} and Chung, {Y. T.} and Ta-Hui Wang and Ku, {S. H.} and Zou, {N. K.} and Vincent Chen and Lu, {W. P.} and Chen, {K. C.} and Lu, {Chih Yuan}",

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T1 - Variations of Vt retention loss in a SONOS flash memory due to a current-path percolation effect

AU - Chou, Y. L.

AU - Chung, Y. T.

AU - Wang, Ta-Hui

AU - Ku, S. H.

AU - Zou, N. K.

AU - Chen, Vincent

AU - Lu, W. P.

AU - Chen, K. C.

AU - Lu, Chih Yuan

PY - 2011/4/1

Y1 - 2011/4/1

N2 - Discrete nitride program charge loss in a small-area SONOS Flash memory cell during retention is observed. Our measurement shows that a retention V t of a programmed SONOS cell exhibits a stepwise evolution with retention time. Individual single-program charge-loss-induced threshold voltage shifts (Δ Vt) are characterized. We find the following: 1) The magnitude of Δ Vt exhibits an exponential distribution, which is believed due to a current-path percolation effect caused by random program charges and substrate dopants, and 2) program-state Vt retention loss has large variations in different cells and P/E cycles due to the percolation effect. We develop a Monte Carlo analysis to take into account the distribution of Δ Vt and a tunneling front model to study the spread of a retention Vt distribution in a SONOS Flash memory.

AB - Discrete nitride program charge loss in a small-area SONOS Flash memory cell during retention is observed. Our measurement shows that a retention V t of a programmed SONOS cell exhibits a stepwise evolution with retention time. Individual single-program charge-loss-induced threshold voltage shifts (Δ Vt) are characterized. We find the following: 1) The magnitude of Δ Vt exhibits an exponential distribution, which is believed due to a current-path percolation effect caused by random program charges and substrate dopants, and 2) program-state Vt retention loss has large variations in different cells and P/E cycles due to the percolation effect. We develop a Monte Carlo analysis to take into account the distribution of Δ Vt and a tunneling front model to study the spread of a retention Vt distribution in a SONOS Flash memory.

KW - Percolation

KW - retention loss

KW - single-program charge

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