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
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 (Vth) shifts observed in p+poly-Si gate Hf-based metal insulator semiconductor field effect transistors (MISFETs), by focusing on the effect of oxygen vacancy (VO) formation in HfO2. It has been found that VO formation and subsequent electron transfer across the interface definitely causes substantial Vth shifts, especially in p+poly-Si gate MISFETs. Moreover, the theory also systematically reproduces recent experimental reports that large flat band (Vfb) shifts are observed, even in intrinsic poly-Si gates, and that the Vfb shifts exhibit a high dependence on HfSiOx thickness.
- G. D. Wilk and R. M. Wallace:
Appl. Phys. Lett. 74 (1999) 2854[AIP Scitation].
- K. Yamada: Ext. Abstr. 1986 Int. Conf. Solid State Devices and Materials, Tokyo, 1986, p. 257.
- C. Hobbs et al.: Tech. Dig. 2003 Symp. VLSI Technology, Kyoto, 2003, p. 9.
- M. Koyama, A. Kaneko, T. Ino, M. Koike, Y. Kamata, R. Iijima, Y. Kamimuta, A. Takashima, M. Suzuki, C. Hongo, S. Inumiya, M. Takayanagi and A. Nishiyama: Tech. Dig. 2002 IEEE Int. Electron Devices Meeting, San Francisco, 2002, p. 849.
- M. Takayanagi, T. Watanabe, R. Iijima, A. Kaneko, S. Inumiya, I. Hirano, K. Sekine, A. Nishiyama, K. Eguchi and Y. Tsunashima: Ext. Abstr. Int. Workshop Gate Insulator, Tokyo, 2003, p. 174.
- K. Shiraishi, K. Yamada, K. Torii, Y. Akasaka, K. Nakajima, M. Konno, T. Chikyo, H. Kitajima and T. Arikado: Tech. Dig. 2004 Symp. VLSI Technology, Honolulu, 2004, p. 108.
- C. Hobbs et al.:
IEEE Trans. Electron Devices 51 (2004) 978[CrossRef].
- H. Takeuchi, D. Ha and T.-J. King:
J. Vac. Sci. & Technol A 22 (2004) 1337[AIP Scitation].
- A. Oshiyama:
Jpn. J. Appl. Phys. 37 (1998) L232[JSAP].
- W. L. Scopel, Antonio J. R. da Silva, W. Orellana and A. Fazzio:
Appl. Phys. Lett. 84 (2004) 1492[AIP Scitation].
- In the present study, the interfacial reaction and the electron transfer only due to energetics are investigated for simplicity, without using a statistical mechanical treatment. The present treatment is quite reasonable since estimated energy gain for the p+poly-Si gate case has a particularly large value of 1.8 eV.
- E. Cartier et al.: Tech. Dig. 2004 Symp. VLSI Technology, Honolulu, 2004, p. 44.
- L. Pantisano, P. J. Chen, V. Afanas'ev, L-A, Ragnarsson, G.. Pourtois and G. Groeseneken: Tech. Dig. 2004 Symp. VLSI Technology, Honolulu, 2004, p. 122.
- E. Ikenaga, I. Hirosawa, Y. Takata, A. Chainani, H. Kitajima, A. Muto, T. Maeda, K. Torii, K. Tamasaku, Y. Nishino, T. Ishizawa, S. Shin, S. Komiya and K. Kobayashi: Ext. Abstr. 2004 Int. Workshop Dielectric Thin Films for Future ULSI Devices, Tokyo, 2004, p. 83.
- M. Miyamaura, K. Masuzaki, H. Watanabe, N. Ikarashi and T. Tatsumi: Ext. Abstr. 2004 Int. Workshop Dielectric Thin Films for Future ULSI Devices, Tokyo, 2004, p. 13.
- 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 Vfb shifts are slightly improved.