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Jpn. J. Appl. Phys. 43 (2004) pp. L1413-L1415  |Next Article|  |Table of Contents|
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Oxygen Vacancy Induced Substantial Threshold Voltage Shifts in the Hf-based High-K MISFET with p+poly-Si Gates -A Theoretical Approach

Kenji Shiraishi^1,2,, Keisaku Yamada^2,3, Kazuyoshi Torii⁴, Yasushi Akasaka⁴, Kiyomi Nakajima², Mitsuru Konno⁵, Toyohiro Chikyow², Hiroshi Kitajima⁴ and Tsunetoshi Arikado⁴

¹Institute of Physics, University of Tsukuba, Tsukuba 305-8571, Japan
²National Institute for Material Science, Tsukuba 305-0044, Japan
³Nanotechnology Research Laboratory, Waseda University, Shinjuku-ku, Tokyo 169-0041, Japan
⁴Semiconductor Leading Edge Technologies Inc., Tsukuba 305-8569, Japan
⁵Application Technology Department, Naka Customer Center, Hitachi Science Systems, Ltd., Hitachi-Naka 312-0033, Japan

(Received September 3, 2004; accepted September 10, 2004; published October 8, 2004)

A theoretical investigation has been made of the origin of substantial threshold voltage (V_th) shifts observed in p+poly-Si gate Hf-based metal insulator semiconductor field effect transistors (MISFETs), by focusing on the effect of oxygen vacancy (V_O) formation in HfO₂. It has been found that V_O formation and subsequent electron transfer across the interface definitely causes substantial V_th shifts, especially in p+poly-Si gate MISFETs. Moreover, the theory also systematically reproduces recent experimental reports that large flat band (V_fb) shifts are observed, even in intrinsic poly-Si gates, and that the V_fb shifts exhibit a high dependence on HfSiO_x thickness.

URL: http://jjap.jsap.jp/link?JJAP/43/L1413/
DOI: 10.1143/JJAP.43.L1413

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16. The proposed “oxygen vacancy model” can also explain these experiments. It is believed that capping layers act as O blocking layers which suppress the interface reaction. This is the reason why V_fb shifts are slightly improved.

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