Nucleation and conformality of iridium and iridium oxide thin films grown by atomic layer deposition

Miika Mattinen, Jani Hämäläinen, Feng Gao, Pasi Jalkanen, Kenichiro Mizohata, Jyrki Räisänen, Riikka Puurunen, Mikko Ritala, Markku Leskelä

    Research output: Contribution to journalArticleScientificpeer-review

    16 Citations (Scopus)

    Abstract

    Nucleation and conformality are important issues, when depositing thin films for demanding applications. In this study, iridium and iridium dioxide (IrO2) films were deposited by atomic layer deposition (ALD), using five different processes. Different reactants, namely, O2, air, consecutive O2 and H2 (O2 + H2), and consecutive O3 and H2 (O3 + H2) pulses were used with iridium acetylacetonate [Ir(acac)3] to deposit Ir, while IrO2 was deposited using Ir(acac)3 and O3. Nucleation was studied using a combination of methods for film thickness and morphology evaluation. In conformality studies, microscopic lateral high-aspect-ratio (LHAR) test structures, specifically designed for accurate and versatile conformality testing of ALD films, were used. The order of nucleation, from the fastest to the slowest, was O2 + H2 > air ~ O2 > O3 > O3 + H2, whereas the order of conformality, from the best to the worst, was O3 + H2 > O2 + H2 > O2 > O3. In the O3 process, a change in film composition from IrO2 to metallic Ir was seen inside the LHAR structures. Compared to the previous reports on ALD of platinum-group metals, most of the studied processes showed good to excellent results.
    Original languageEnglish
    Pages (from-to)10559-10569
    Number of pages11
    JournalLangmuir
    Volume32
    Issue number41
    DOIs
    Publication statusPublished - 18 Oct 2016
    MoE publication typeA1 Journal article-refereed

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