Numerical Simulation of Trapped Hole Lateral Migration and Induced Threshold Voltage Retention Loss in a SONOS Flash Memory

Cheng Min Jiang*, Chih Jung Wu, Tahui Wang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We establish a one-dimensional transient simulation to study trapped hole lateral migration in the silicon nitride of a silicon-oxide-nitride-oxide-silicon (SONOS) flash memory cell. In our model, the nitride traps have a continuous energy distribution. Trapped hole emissions to the valence band of the silicon nitride, free hole recapture into the nitride traps, and hole drift-diffusion in the valance band are included in the simulation. Two major trapped hole emission processes, thermally assisted tunneling (ThAT) and the Frenkel-Poole emission are considered. We simulate trapped hole lateral migration in a SONOS cell with program electrons stored at the source side and erase holes at the drain side. Our simulation shows that the ThAT is a dominant transport mechanism for trapped hole lateral migration in retention. We also simulate a threshold voltage (Vt) retention loss due to trapped hole lateral migration at different program levels. The trend of the simulated Vt retention loss is consistent with the measurement result.

Original languageEnglish
Pages (from-to)147-152
Number of pages6
JournalIEEE Transactions on Device and Materials Reliability
Volume23
Issue number1
DOIs
StatePublished - 1 Mar 2023

Keywords

  • charge lateral migration
  • Flash memory
  • simulation
  • Vt retention loss

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