Investigation of simulated and measured program characteristics in 4-bit/cell charge-trap flash (CTF) memories

Jae Moo Kim, Yu Jeong Seo, Ho Myoung An, Tae Geun Kim, Sung Wook Park, Dae Hwan Kim

Research output: Contribution to journalArticle


We investigate the simulated and measured program characteristics for 4-bit program operations in silicon-oxide-nitride-oxide-silicon (SONOS) devices by using two-dimensional (2-D) device simulations. For this calculation, the width of the region with charge trapped locally in the drain region is assumed to be as narrow as 44 nm to remove second-bit effects during the 2-bit and 4-bit operation. We determine the reverse read voltage for screening bit-1 to be 2.5 V and confirm that both 2-bit and 4-bit characteristics are successfully observed in our devices. From the threshold voltage shift, the densities of trapped charge are estimated to be 0 × 1019, 3 × 1019, 6 × 1019 and 9 × 1019 cm-3 at 4-level states, respectively. We also find that these simulation results are reasonably consistent with the experimental results achieved in this work.

Original languageEnglish
Pages (from-to)367-371
Number of pages5
JournalJournal of the Korean Physical Society
Issue number1
Publication statusPublished - 2009 Jul 1



  • 4-bit-per-cell
  • Localized trapped charge
  • NROM™

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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