Browsing by Author "Chen, Vincent"

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Program Charge Effect on Random Telegraph Noise Amplitude and Its Device Structural Dependence in SONOS Flash Memory
(2009)
Chiu, J. P.
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Chou, Y. L.
;
Ma, H. C.
;
Wang, Tahui
;
Ku, S. H.
Nitride program charge effects on random telegraph noise (RTN) in SONOS flash cells are investigated. We measure and simulate RTN amplitudes in floating gate flash, planar SONOS, and FinFET SONOS cells. We find that a planar SONOS has a wide spread in RTN amplitude after programming while a floating gate flash cell has identical RTN amplitude in erase and program states. The spread of program-state RTN amplitudes in a planar SONOS is attributed to a current-path percolation effect caused by random discrete nitride charges. The program-state RTN spread can be significantly reduced in FinFET SONOS.
Program Trapped-Charge Effect on Random Telegraph-Noise Amplitude in a Planar SONOS Flash Memory Cell
(2009-11-01)
Ma, H. C.
;
Chou, Y. L.
;
Chiu, J. P.
;
Wang, Tahui
;
Ku, S. H.
Program-charge effects in a SONOS Flash cell on the amplitude of random telegraph noise (RTN) are investigated. We measure RTN in 45 planar SONOS cells and 40 floating-gate (FG) cells in erase state and program state, respectively. We find that a SONOS cell has a wide spread in RTN amplitudes after programming, while an FG cell has identical RTN amplitudes in erase and program states at the same read-current level. A 3-D atomistic simulation is performed to calculate RTN amplitudes. Our result shows that the wide spread of program-state RTN amplitudes in a SONOS cell is attributed to a current-path-percolation effect caused by random discrete nitride charges.
Variations of V(t) Retention Loss in a SONOS Flash Memory Due to a Current-Path Percolation Effect
(2011-04-01)
Chou, Y. L.
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Chung, Y. T.
;
Wang, Tahui
;
Ku, S. H.
;
Zou, N. K.
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 (Delta V(t)) are characterized. We find the following: 1) The magnitude of Delta 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 Delta V(t) and a tunneling front model to study the spread of a retention V(t) distribution in a SONOS Flash memory.
Variations of V-t Retention Loss in a SONOS Flash Memory Due to a Current-Path Percolation Effect
(2011-04-01)
Chou, Y. L.
;
Chung, Y. T.
;
Wang, Tahui
;
Ku, S. H.
;
Zou, N. K.
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 (Delta V-t) are characterized. We find the following: 1) The magnitude of Delta 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 Delta V-t and a tunneling front model to study the spread of a retention V-t distribution in a SONOS Flash memory.