Simultaneous formation of n- and p-Type Ohmic contacts to 4H-SiC using the binary Ni/Al system

Kazuhiro Ito, Toshitake Onishi, Hidehisa Takeda, Susumu Tsukimoto, Mitsuru Konno, Yuya Suzuki, Masanori Murakami

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    Fabrication procedure for silicon carbide power metal oxide semiconductor field effect transistors can be improved through simultaneous formation of ohmic contacts on both the n-source and p-well regions. We have succeeded in the simultaneous formation of Ni/Al ohmic contacts to n- and p-type SiC after annealing at 1000°C for 5 mins in an ultra-high vacuum. Ohmic contacts to n-type SiC were found when Al-layer thickness was less than about 5 nm while ohmic contacts to p-type SiC were observed for an Al-layer thickness greater than about 5 nm. Only the contacts with Al-layer thicknesses in the range of 5 to 6 nm exhibited ohmic behavior to both n- and p-type SiC, with specific contact resistances of 1.8 × 10-4 Ωcm2 and 1.2 × 102 Ωcm2 for n- and p-type SiC, respectively. An about 100 nm-thick contact layer was uniformly formed on the SiC substrate and polycrystalline δ-Ni2Si(Al) grains were formed at the contact/SiC interface. The distribution in values for the Al/Ni ratio in the δ-Ni2Si(Al) grains which exhibited ohmic behavior to both n- and p-type SiC was the largest. The smallest average δ-Ni 2Si(Al) grain size was also observed in these contacts. Thus, the large distribution in the Al/Ni ratios and a fine microstructure were found to be characteristic of the ohmic contacts to both n- and p-type SiC.

    Original languageEnglish
    Title of host publicationMaterials Research Society Symposium Proceedings - Silicon Carbide 2008 - Materials, Processing and Devices
    Pages189-194
    Number of pages6
    Publication statusPublished - 2008 Nov 17
    EventSilicon Carbide 2008 - Materials, Processing and Devices - San Francisco, CA, United States
    Duration: 2008 Mar 252008 Mar 27

    Publication series

    NameMaterials Research Society Symposium Proceedings
    Volume1069
    ISSN (Print)0272-9172

    Other

    OtherSilicon Carbide 2008 - Materials, Processing and Devices
    CountryUnited States
    CitySan Francisco, CA
    Period08/3/2508/3/27

    ASJC Scopus subject areas

    • Materials Science(all)
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering

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  • Cite this

    Ito, K., Onishi, T., Takeda, H., Tsukimoto, S., Konno, M., Suzuki, Y., & Murakami, M. (2008). Simultaneous formation of n- and p-Type Ohmic contacts to 4H-SiC using the binary Ni/Al system. In Materials Research Society Symposium Proceedings - Silicon Carbide 2008 - Materials, Processing and Devices (pp. 189-194). (Materials Research Society Symposium Proceedings; Vol. 1069).