Low-resistivity α-phase tungsten films grown by hot-wire assisted atomic layer deposition in high-aspect-ratio structures

Mengdi Yang (Corresponding Author), Antonius A.I. Aarnink, Jurriaan Schmitz, Alexey Y. Kovalgin

    Research output: Contribution to journalArticleAcademicpeer-review

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    Abstract

    In this work, the so-called hot-wire (HW) assisted atomic layer deposition (HWALD) technique is employed to grow high-purity α-phase tungsten (W) films at a substrate temperature of 275 °C. The films are deposited on thermally grown silicon dioxide (SiO2) in a home-built hot-wall reactor, using alternating pulses of WF6 and HW-generated atomic hydrogen in the self-limiting surface-reaction manner characteristic for ALD. A W seed layer, needed to enable the HWALD-W process on a SiO2 surface, is formed prior to each deposition. In-situ spectroscopic ellipsometry is used to monitor the growth behavior and film properties. The films exhibit a high-purity (99 at.%) W, according to X-ray photoelectron spectroscopy. The X-ray diffraction scans reveal the existence of α-phase W. The resistivity measurements by means of four point probe, transfer length method test structures and the Drude-Lorentz SE model all reveal a low resistivity of 15 μΩ·cm. The high-resolution transmission electron microscopy analysis shows a uniform and conformal coverage of high aspect ratio structures, confirming the effective ALD process and the sufficient diffusion of both WF6 and at-H into deep trenches.
    Original languageEnglish
    Pages (from-to)199-208
    Number of pages10
    JournalThin solid films
    Volume646
    DOIs
    Publication statusPublished - 31 Jan 2018

    Keywords

    • Hot wire
    • Tungsten
    • ALD
    • Alpha-phase
    • Low resistivity
    • High-aspect-ratio substrates

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