## Abstract

A V _{t} retention distribution tail in a multitime-program (MTP) silicon-oxide-nitride-oxide-silicon (SONOS) memory is investigated. We characterize a single-program-charge-loss-induced $\Delta V _{t} in nor-type SONOS multilevel cells (MLCs). Our measurement shows the following: 1) A single-charge-loss-induced $\Delta V _{t} exhibits an exponential distribution in magnitudes, which is attributed to a random-program-charge-induced current-path percolation effect, and 2) the standard deviation of the exponential distribution depends on the program-charge density and increases with a program V _{t} level in an MLC SONOS. In addition, we measure a V _{t} retention distribution in a 512-Mb MTP SONOS memory and observe a significant V _{t} retention tail. A numerical V _{t} retention distribution model including the percolation effect and a Poisson-distribution-based multiple-charge-loss model is developed. Our model agrees with the measured V _{t} retention distribution in a 512-Mb SONOS well. The observed V _{t} tail is realized mainly due to the percolation effect.

Original language | English |
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Article number | 6175940 |

Pages (from-to) | 1371-1376 |

Number of pages | 6 |

Journal | IEEE Transactions on Electron Devices |

Volume | 59 |

Issue number | 5 |

DOIs | |

State | Published - 1 May 2012 |

## Keywords

- Model
- V retention distribution
- percolation
- silicon-oxide-nitride-oxide-silicon (SONOS)