Reliability mechanisms of LTPS-TFT with HfO 2 gate dielectric: PBTI, NBTI, and hot-carrier stress

Ming Wen Ma*, Chi Yang Chen, Woei Cheng Wu, Chun Jung Su, Kuo Hsing Kao, Tien-Sheng Chao, Tan Fu Lei

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


In this paper, a comprehensive study of the reliability mechanisms of high-performance low-temperature polycrystalline-Si thin-film transistor (LTPS-TFT) with HfO 2 gate dielectric is reported for the first time. Various bias- and temperature-stress conditions, which correspond to positive-bias stress (PBS), positive-bias temperature instability (PBTI), negative-bias stress (NBS), negative-bias temperature instability (NBTI), and hot-carrier stress, are used to differentiate the distribution and mechanism of trap density states. The generation of deep-trap states of the effective interfacial layer (IL), tail-trap states of poly-Si grain boundaries, and electron trapping of the HfO 2 gate dielectric is observed for the PBS and PBTI of the HfO 2 LTPS-TFT. In addition, both the deep- and tail-trap states of the effective IL are generated under NBS and NBTI of the HfO 2 LTPS-TFT.

Original languageEnglish
Pages (from-to)1153-1160
Number of pages8
JournalIEEE Transactions on Electron Devices
Issue number5
StatePublished - 1 May 2008


  • HfO gate dielectric
  • Hot-carrier stress (HCS)
  • Low-temperature polycrystalline-Si thin-film transistor (LTPS-TFT)
  • Negative-bias temperature instability (NBTI)
  • Positive-bias temperature instability (PBTI)
  • Reliability


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