Aluminum oxide/titanium dioxide nanolaminates grown by atomic layer deposition: Growth and mechanical properties

Oili M. E. Ylivaara (Corresponding Author), Lauri Kilpi, Xuwen Liu, Sakari Sintonen, Saima Ali, Mikko Laitinen, Jaakko Julin, Eero Haimi, Timo Sajavaara, Harri Lipsanen, Simo-Pekka Hannula, Helena Ronkainen, Riikka L. Puurunen

    Research output: Contribution to journalArticleScientificpeer-review

    12 Citations (Scopus)

    Abstract

    Atomic layer deposition (ALD) is based on self-limiting surface reactions. This and cyclic process enable the growth of conformal thin films with precise thickness control and sharp interfaces. A multilayered thin film, which is nanolaminate, can be grown using ALD with tuneable electrical and optical properties to be exploited, for example, in the microelectromechanical systems. In this work, the tunability of the residual stress, adhesion, and mechanical properties of the ALD nanolaminates composed of aluminum oxide (Al2O3) and titanium dioxide (TiO2) films on silicon were explored as a function of growth temperature (110-300 C), film thickness (20-300 nm), bilayer thickness (0.1-100 nm), and TiO2 content (0%-100%). Al2O3 was grown from Me3Al and H2O, and TiO2 from TiCl4 and H2O. According to wafer curvature measurements, Al2O3/TiO2 nanolaminates were under tensile stress; bilayer thickness and growth temperature were the major parameters affecting the stress; the residual stress decreased with increasing bilayer thickness and ALD temperature. Hardness increased with increasing ALD temperature and decreased with increasing TiO2 fraction. Contact modulus remained approximately stable. The adhesion of the nanolaminate film was good on silicon.
    Original languageEnglish
    Article number01B105
    Number of pages14
    JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
    Volume35
    Issue number1
    DOIs
    Publication statusPublished - 2017
    MoE publication typeA1 Journal article-refereed

    Keywords

    • ALD
    • Atomic Layer Deposition
    • nanolaminate
    • residual stress
    • contact modulus
    • hardness
    • adhesion

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