Hot-wire assisted atomic layer deposition of Tungsten films

Mengdi Yang

    Research output: ThesisPhD Thesis - Research UT, graduation UT

    301 Downloads (Pure)


    This thesis aims to establish a novel technique of atomic layer deposition (ALD) for the future ultra-large-scale integration (ULSI) of microelectronics. We developed a hot-wire assisted ALD (HWALD), where a heated tungsten (W) filament is utilized instead of a plasma to generate radicals. HWALD is expected to be another candidate for deposition in future ULSI technology. Particularly, this thesis focuses on the application of HWALD for W deposition by providing sequential pulses of atomic hydrogen (at-H) and WF6.

    This thesis demonstrates the results of HWALD W in the cold-/hot-wall reactor. In the cold-wall reactor, β-phase W of high resistivity was obtained, whereas the α-phase W of low resistivity was obtained in the hot-wall reactor.
    The α-phase W possessed a low resistivity of 15 µΩ•cm. Furthermore, a uniform and conformal coverage of HWALD W on high aspect ratio structures (up to an aspect ratio of 36).

    Moreover, an inherent area-selective HWALD of W was proposed. The nucleation and growth of HWALD W on various substrates were studied. No nucleation was found on a thermally-grown SiO2 surface nor on (ALD-grown) TiN and Al2O3 surfaces. On the contrary, HWALD W could be successfully deposited on W and Co surfaces. Due to the nucleation delays on different surfaces, an area-selective HWALD W process was achieved on W/SiO2 and Co/SiO2 patterned surfaces.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Awarding Institution
    • University of Twente
    • Schmitz, Jurriaan, Supervisor
    • Kovalgin, Alexey Y., Co-Supervisor
    Award date2 Feb 2018
    Place of PublicationEnschede
    Electronic ISBNs978-90-365-4469-6
    Publication statusPublished - 19 Jan 2018


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