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

doi:10.1016/j.tsf.2005.08.409

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 journal › Article › peer-review

52 Citations (Scopus)

Abstract

We have investigated theoretically the cause of the substantial threshold voltage (V_th) 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 V_th shifts in p+poly-Si gate MISFETs. Moreover, our theory also systematically reproduces other recent experimental results.

Original language	English
Pages (from-to)	305-310
Number of pages	6
Journal	Thin Solid Films
Volume	508
Issue number	1-2
DOIs	https://doi.org/10.1016/j.tsf.2005.08.409
Publication status	Published - 2006 Jun 5
Externally published	Yes

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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title = "Oxygen-vacancy-induced threshold voltage shifts in Hf-related high-k gate stacks",

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.",

keywords = "Fermi level pinning, High-k HfO dielectrics, Oxygen vacancy, Poly-Si gates",

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

note = "Funding Information: This work was partly supported by “High-k Network” cooperating with academic, industry and governmental institutes, a program for the “Promotion of Leading Researches” in Special Coordination Funds for Promoting Science and Technology by MEXT, and a Grant-in-Aid for Scientific Research No. 16560020 by MEXT. The numerical calculations in the present study were performed by the supercomputer centers of University of Tsukuba, Institute of Solid State Physics in University of Tokyo and Institute of Molecular Science.",

year = "2006",

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doi = "10.1016/j.tsf.2005.08.409",

language = "English",

volume = "508",

pages = "305--310",

journal = "Thin Solid Films",

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T1 - Oxygen-vacancy-induced threshold voltage shifts in Hf-related high-k gate stacks

AU - Shiraishi, Kenji

AU - Yamada, Keisaku

AU - Torii, Kazuyoshi

AU - Akasaka, Yasushi

AU - Nakajima, Kiyomi

AU - Konno, Mitsuru

AU - Chikyow, Toyohiro

AU - Kitajima, Hiroshi

AU - Arikado, Tsunetoshi

AU - Nara, Yasuo

N1 - Funding Information: This work was partly supported by “High-k Network” cooperating with academic, industry and governmental institutes, a program for the “Promotion of Leading Researches” in Special Coordination Funds for Promoting Science and Technology by MEXT, and a Grant-in-Aid for Scientific Research No. 16560020 by MEXT. The numerical calculations in the present study were performed by the supercomputer centers of University of Tsukuba, Institute of Solid State Physics in University of Tokyo and Institute of Molecular Science.

PY - 2006/6/5

Y1 - 2006/6/5

N2 - 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.

AB - 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.

KW - Fermi level pinning

KW - High-k HfO dielectrics

KW - Oxygen vacancy

KW - Poly-Si gates

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

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Keywords

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