Masato Nishimori

Fujitsu Limited

  • High-rate ICP Etching for GaN Through-substrate Via of GaN-on-GaN HEMTs

    Keiji Watanabe, Fujitsu Laboratories Ltd.
    Naoya Okamoto, Fujitsu Limited and Fujitsu Laboratories Ltd.
    Naoya Okamoto, Fujitsu Laboratories Ltd.
    Atsushi Takahashi, Fujitsu Laboratories Ltd.
    Atsushi Takahashi, Fujitsu Limited
    Yuichi Minoura, Fujitsu Limited and Fujitsu Laboratories Ltd.
    Yuichi Minoura, Fujitsu Laboratories Ltd.
    Yusuke Kumazaki, Fujitsu Limited
    Yusuke Kumazaki, Fujitsu Laboratories Ltd.
    Masato Nishimori, Fujitsu Limited
    Masato Nishimori, Fujitsu Laboratories Ltd.
    Shiro Ozaki, Fujitsu Limited and Fujitsu Laboratories Ltd.
    Shiro Ozaki, Fujitsu Limited
    Kozo Makiyama, Fujitsu Limited and Fujitsu Laboratories Ltd.
    Kozo Makiyama, Fujitsu Limited
    Toshihiro Ohki, Fujitsu Limited and Fujitsu Laboratories Ltd.
    Toshihiro Ohki, Fujitsu Laboratories Ltd.
    Norikazu Nakamura, Fujitsu Limited and Fujitsu Laboratories Ltd.
    Naoki Hara, Fujitsu Laboratories Ltd.
    Naoki Hara, Fujitsu Limited
    Keiji Watanabe, Fujitsu Limited

    In this study, we have developed a technique for forming GaN through-substrate vias (TSV) using inductively coupled plasma (ICP) dry etching with a gas mixture of Cl2/BCl3. A 91 μm-deep GaN via-hole having a diameter of 80 μm was successfully formed at a high etching rate of 1.5 μm/min and a high etching selectivity of 35. We discuss pillar formation, RIE lag, loading effects and etch uniformity in high-rate ICP etching, which are critical issues related to the yield of via-hole fabrication. Finally, we investigated the effect of GaN TSVs on heat dissipation by thermal simulation.

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