Hot-wire assisted ALD of tungsten films: In-situ study of the interplay between CVD, etching, and ALD modes

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    Abstract

    In this work, we investigated an approach of hot-wire assisted ALD (HWALD), utilizing a hot (up to 2000 8C) tungsten (W) wire. Tungsten films were deposited by this method using alternating pulses of WF6 gas and atomic hydrogen (at-H). The latter was generated by catalytic dissociation of molecular hydrogen (H2) upon the hot-wire. The W films were grown on a 100-nm thick thermal SiO2. The growth process was monitored in real time by an in-situ spectroscopic ellipsometer (SE). The real-time SE monitoring revealed the coexistence of three processes: CVD, etching, and ALD of the W film. WF6 could back-stream diffuse to the hot-wire, resulting in WF6 decomposition and generation of a flux of fluorine (F). The latter caused etching of the grown W film and the filament, and provided extra tungsten supply, which might cause CVD. Higher pressure and higher carrier gas flow rate were found to largely suppress the back-stream diffusion of WF6, which efficiently limited CVD. By controlling the dose of WF6 and process pressure, the etching had also been minimized. X-ray photoelectron spectroscopy of optimized HWALD grown W revealed 99 at% of W; concentrations of oxygen and fluorine were lower than 1%, below the detection limit.
    Original languageUndefined
    Pages (from-to)1607-1614
    Number of pages8
    JournalPhysica status solidi A
    Volume212
    Issue number7
    DOIs
    Publication statusPublished - 25 May 2015

    Keywords

    • METIS-312664
    • Tungsten
    • Thin Films
    • in-situ spectroscopic ellipsometer
    • Etching
    • IR-96409
    • atomic layer depositionetchinghot wirein-situ spectroscopic ellipsometerthin filmstungsten
    • Atomic Layer Deposition
    • hot wire
    • EWI-26132

    Cite this

    @article{60dc86fa53944a5cbaa8d9d711257a55,
    title = "Hot-wire assisted ALD of tungsten films: In-situ study of the interplay between CVD, etching, and ALD modes",
    abstract = "In this work, we investigated an approach of hot-wire assisted ALD (HWALD), utilizing a hot (up to 2000 8C) tungsten (W) wire. Tungsten films were deposited by this method using alternating pulses of WF6 gas and atomic hydrogen (at-H). The latter was generated by catalytic dissociation of molecular hydrogen (H2) upon the hot-wire. The W films were grown on a 100-nm thick thermal SiO2. The growth process was monitored in real time by an in-situ spectroscopic ellipsometer (SE). The real-time SE monitoring revealed the coexistence of three processes: CVD, etching, and ALD of the W film. WF6 could back-stream diffuse to the hot-wire, resulting in WF6 decomposition and generation of a flux of fluorine (F). The latter caused etching of the grown W film and the filament, and provided extra tungsten supply, which might cause CVD. Higher pressure and higher carrier gas flow rate were found to largely suppress the back-stream diffusion of WF6, which efficiently limited CVD. By controlling the dose of WF6 and process pressure, the etching had also been minimized. X-ray photoelectron spectroscopy of optimized HWALD grown W revealed 99 at{\%} of W; concentrations of oxygen and fluorine were lower than 1{\%}, below the detection limit.",
    keywords = "METIS-312664, Tungsten, Thin Films, in-situ spectroscopic ellipsometer, Etching, IR-96409, atomic layer depositionetchinghot wirein-situ spectroscopic ellipsometerthin filmstungsten, Atomic Layer Deposition, hot wire, EWI-26132",
    author = "Mengdi Yang and Aarnink, {Antonius A.I.} and Kovalgin, {Alexeij Y.} and Wolters, {Robertus A.M.} and Jurriaan Schmitz",
    note = "eemcs-eprint-26132 ; http://eprints.ewi.utwente.nl/26132",
    year = "2015",
    month = "5",
    day = "25",
    doi = "10.1002/pssa.201532305",
    language = "Undefined",
    volume = "212",
    pages = "1607--1614",
    journal = "Physica status solidi A",
    issn = "1862-6300",
    publisher = "Wiley-VCH Verlag",
    number = "7",

    }

    TY - JOUR

    T1 - Hot-wire assisted ALD of tungsten films: In-situ study of the interplay between CVD, etching, and ALD modes

    AU - Yang, Mengdi

    AU - Aarnink, Antonius A.I.

    AU - Kovalgin, Alexeij Y.

    AU - Wolters, Robertus A.M.

    AU - Schmitz, Jurriaan

    N1 - eemcs-eprint-26132 ; http://eprints.ewi.utwente.nl/26132

    PY - 2015/5/25

    Y1 - 2015/5/25

    N2 - In this work, we investigated an approach of hot-wire assisted ALD (HWALD), utilizing a hot (up to 2000 8C) tungsten (W) wire. Tungsten films were deposited by this method using alternating pulses of WF6 gas and atomic hydrogen (at-H). The latter was generated by catalytic dissociation of molecular hydrogen (H2) upon the hot-wire. The W films were grown on a 100-nm thick thermal SiO2. The growth process was monitored in real time by an in-situ spectroscopic ellipsometer (SE). The real-time SE monitoring revealed the coexistence of three processes: CVD, etching, and ALD of the W film. WF6 could back-stream diffuse to the hot-wire, resulting in WF6 decomposition and generation of a flux of fluorine (F). The latter caused etching of the grown W film and the filament, and provided extra tungsten supply, which might cause CVD. Higher pressure and higher carrier gas flow rate were found to largely suppress the back-stream diffusion of WF6, which efficiently limited CVD. By controlling the dose of WF6 and process pressure, the etching had also been minimized. X-ray photoelectron spectroscopy of optimized HWALD grown W revealed 99 at% of W; concentrations of oxygen and fluorine were lower than 1%, below the detection limit.

    AB - In this work, we investigated an approach of hot-wire assisted ALD (HWALD), utilizing a hot (up to 2000 8C) tungsten (W) wire. Tungsten films were deposited by this method using alternating pulses of WF6 gas and atomic hydrogen (at-H). The latter was generated by catalytic dissociation of molecular hydrogen (H2) upon the hot-wire. The W films were grown on a 100-nm thick thermal SiO2. The growth process was monitored in real time by an in-situ spectroscopic ellipsometer (SE). The real-time SE monitoring revealed the coexistence of three processes: CVD, etching, and ALD of the W film. WF6 could back-stream diffuse to the hot-wire, resulting in WF6 decomposition and generation of a flux of fluorine (F). The latter caused etching of the grown W film and the filament, and provided extra tungsten supply, which might cause CVD. Higher pressure and higher carrier gas flow rate were found to largely suppress the back-stream diffusion of WF6, which efficiently limited CVD. By controlling the dose of WF6 and process pressure, the etching had also been minimized. X-ray photoelectron spectroscopy of optimized HWALD grown W revealed 99 at% of W; concentrations of oxygen and fluorine were lower than 1%, below the detection limit.

    KW - METIS-312664

    KW - Tungsten

    KW - Thin Films

    KW - in-situ spectroscopic ellipsometer

    KW - Etching

    KW - IR-96409

    KW - atomic layer depositionetchinghot wirein-situ spectroscopic ellipsometerthin filmstungsten

    KW - Atomic Layer Deposition

    KW - hot wire

    KW - EWI-26132

    U2 - 10.1002/pssa.201532305

    DO - 10.1002/pssa.201532305

    M3 - Article

    VL - 212

    SP - 1607

    EP - 1614

    JO - Physica status solidi A

    JF - Physica status solidi A

    SN - 1862-6300

    IS - 7

    ER -