Fabrication of Sub-10 nm Metallic Lines of Low Line-Width Roughness by Hydrogen Reduction of Patterned Metal–Organic Materials

Authors

  • Mihaela Nedelcu,

    1. Department of Physics, University of Cambridge Madingley Road, Cambridge CB3 0HE (United Kingdom)
    2. Current address: Department of Chemistry and Biochemistry, Ludwig-Maximilians-Universität München, Butenandstr. 11 (Building E), München (Germany)
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  • Mohammad S. M. Saifullah,

    Corresponding author
    1. Patterning and Fabrication Capability Group, Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) 3 Research Link, Singapore 117602 (Republic of Singapore)
    • Patterning and Fabrication Capability Group, Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602 (Republic of Singapore).
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  • David G. Hasko,

    1. The Nanoscience Centre, University of Cambridge 11 J. J. Thomson Avenue, Cambridge CB3 0FF (United Kingdom)
    2. Current address: Centre for Advanced Electronics and Photonics (CAPE), University of Cambridge, 9 J. J. Thomson Avenue, Cambridge CB3 0FA (United Kingdom)
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  • Arang Jang,

    1. BK 21 Physics Research Division, Department of Energy Science, Institute of Basic Sciences, SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University 300 Cheoncheon-Dong, Jangan-Gu, Suwon 440-746 (South Korea)
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  • David Anderson,

    1. Department of Physics, University of Cambridge Madingley Road, Cambridge CB3 0HE (United Kingdom)
    2. Current address: School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)
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  • Wilhelm T. S. Huck,

    1. The Nanoscience Centre, University of Cambridge 11 J. J. Thomson Avenue, Cambridge CB3 0FF (United Kingdom)
    2. Melville Laboratory, Department of Chemistry, University of Cambridge Lensfield Road, Cambridge CB2 1EW (United Kingdom)
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  • Geraint A. C. Jones,

    1. Department of Physics, University of Cambridge Madingley Road, Cambridge CB3 0HE (United Kingdom)
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  • Mark E. Welland,

    1. The Nanoscience Centre, University of Cambridge 11 J. J. Thomson Avenue, Cambridge CB3 0FF (United Kingdom)
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  • Dae Joon Kang,

    Corresponding author
    1. BK 21 Physics Research Division, Department of Energy Science, Institute of Basic Sciences, SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University 300 Cheoncheon-Dong, Jangan-Gu, Suwon 440-746 (South Korea)
    • BK 21 Physics Research Division, Department of Energy Science, Institute of Basic Sciences, SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University 300 Cheoncheon-Dong, Jangan-Gu, Suwon 440-746 (South Korea).
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  • Ullrich Steiner

    Corresponding author
    1. Department of Physics, University of Cambridge Madingley Road, Cambridge CB3 0HE (United Kingdom)
    2. The Nanoscience Centre, University of Cambridge 11 J. J. Thomson Avenue, Cambridge CB3 0FF (United Kingdom)
    3. Freiburg Institute of Advanced Studies (FRIAS) Albert-Ludwigs-Universität Freiburg Albertstraße 19, D-79104 Freiburg i.Br. (Germany)
    • Department of Physics, University of Cambridge Madingley Road, Cambridge CB3 0HE (United Kingdom).
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  • To Professor Seshadri Seetharaman, for his contribution to extractive metallurgy

Abstract

The fabrication of very narrow metal lines by the lift-off technique, especially below sub-10 nm, is challenging due to thinner resist requirements in order to achieve the lithographic resolution. At such small length scales, when the grain size becomes comparable with the line-width, the built-in stress in the metal film can cause a break to occur at a grain boundary. Moreover, the line-width roughness (LWR) from the patterned resist can result in deposited metal lines with a very high LWR, leading to an adverse change in device characteristics. Here a new approach that is not based on the lift-off technique but rather on low temperature hydrogen reduction of electron-beam patterned metal naphthenates is demonstrated. This not only enables the fabrication of sub-10 nm metal lines of good integrity, but also of low LWR, below the limit of 3.2 nm discussed in the International Technology Roadmap for Semiconductors. Using this method, sub-10 nm nickel wires are obtained by reducing patterned nickel naphthenate lines in a hydrogen-rich atmosphere at 500 °C for 1 h. The LWR (i.e., 3 σLWR) of these nickel nanolines was found to be 2.9 nm. The technique is general and is likely to be suitable for fabrication of nanostructures of most commonly used metals (and their alloys), such as iron, cobalt, nickel, copper, tungsten, molybdenum, and so on, from their respective metal–organic compounds.

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