Joining Copper Oxide Nanotube Arrays Driven by the Nanoscale Kirkendall Effect

Authors

  • Shu Rong Chun,

    1. School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798, Singapore
    2. GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D, Street 2, Singapore 738406, Singapore
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  • Wardhana Aji Sasangka,

    1. School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798, Singapore
    2. Advanced Materials for Micro- and Nano-Systems, Singapore-MIT Alliance, 4 Engineering Drive 3, Singapore 117576, Singapore
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  • Mei Zhen Ng,

    1. School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798, Singapore
    2. GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D, Street 2, Singapore 738406, Singapore
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  • Qing Liu,

    1. Temasek Laboratories, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798, Singapore
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  • Anyan Du,

    1. GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D, Street 2, Singapore 738406, Singapore
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  • Jie Zhu,

    1. GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D, Street 2, Singapore 738406, Singapore
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  • Chee Mang Ng,

    1. GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D, Street 2, Singapore 738406, Singapore
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  • Zhi Qiang Liu,

    1. GLOBALFOUNDRIES Singapore Pte Ltd, 60 Woodlands Industrial Park D, Street 2, Singapore 738406, Singapore
    2. Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Singapore
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  • Sing Yang Chiam,

    1. Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore
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  • Chee Lip Gan

    Corresponding author
    1. School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798, Singapore
    2. Advanced Materials for Micro- and Nano-Systems, Singapore-MIT Alliance, 4 Engineering Drive 3, Singapore 117576, Singapore
    • School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798, Singapore.
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Abstract

Various annealing conditions (environment, temperature, and duration) are applied to study the nanoscale Kirkendall effect of copper (Cu) nanowire (NW) arrays on a Si substrate. The results show that an appropriate amount of oxygen supply is crucial for uniform transformation from Cu NWs (average diameter ∼50 nm) into Cu oxide nanotube arrays. An annealing duration of 30 min at 200 °C in a low vacuum environment reveals that the voids are not uniformly distributed at the Cu/Cu oxide interface. This suggests that void growth is due to surface diffusion of Cu along void surfaces. Annealing above 200 °C for 60 min resulted in complete transformation from Cu NWs into Cu oxide nanotubes. X-ray photoelectron spectroscopy characterization indicates that the Cu oxides formed at 200 °C and 300 °C are Cu2O and CuO, respectively. It is demonstrated that the transformation from Cu NW arrays into Cu oxide nanotube arrays can be combined with the joining of stacked Si chips in a single-process step with reasonable joint shear strength. Transmission electron microscopy-electron energy loss spectroscopy elemental mapping analysis reveals that the joint interface is Cu oxide. The outward diffusion of Cu driven by the nanoscale Kirkendall effect is believed to enhance the joining process. By controlling the environment, temperature, and duration, joined Cu2O or CuO nanotube stacked chips can be achieved, which serve as a platform for the further development of nanostructured, stacked devices.

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