Oxygen-vacancy-induced threshold voltage shifts in Hf-related high-k gate stacks

Kenji Shiraishi, Keisaku Yamada, Kazuyoshi Torii, Yasushi Akasaka, Kiyomi Nakajima, Mitsuru Konno, Toyohiro Chikyow, Hiroshi Kitajima, Tsunetoshi Arikado, Yasuo Nara

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)

Abstract

We have investigated theoretically the cause of the substantial threshold voltage (Vth) shifts observed in Hf-related high-k gate stacks with p+poly-Si gates, by focusing on the ionic nature of HfO2. The oxygen vacancy (Vo) level in ionic HfO2 is located in a relatively higher part of the band gap. This high position of the Vo level results in a significant elevation of the Fermi level for p+poly-Si gates, if the p+poly-Si gate is in contact with the high-k HfO2. Vo formation in the HfO2 induces a subsequent electron transfer across the interface, causing a substantial Vth shifts in p+poly-Si gate MISFETs. Moreover, our theory also systematically reproduces other recent experimental results.

Original languageEnglish
Pages (from-to)305-310
Number of pages6
JournalThin Solid Films
Volume508
Issue number1-2
DOIs
Publication statusPublished - 2006 Jun 5
Externally publishedYes

Keywords

  • Fermi level pinning
  • High-k HfO dielectrics
  • Oxygen vacancy
  • Poly-Si gates

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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