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.
Original language | English |
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Article number | 5723684 |
Pages (from-to) | 458-460 |
Number of pages | 3 |
Journal | IEEE Electron Device Letters |
Volume | 32 |
Issue number | 4 |
DOIs | |
State | Published - 1 Apr 2011 |
Keywords
- Percolation
- retention loss
- single-program charge
- SONOS