Influence of the seed layer on structural and electro-acoustic properties of sputter-deposited AlN resonators

Tommi Riekkinen (Corresponding Author), Arto Nurmela, Jyrki Molarius, Tuomas Pensala, P. Kostamo, Markku Ylilammi, S. van Dijken

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    The growth of high-quality AlN films has been studied by reactive sputtering onto Mo electrodes with Ni, Ti, and TiW seed layers and subsequent integration into thin film bulk acoustic wave resonators. The crystalline structure and morphology of the Mo and c-axis oriented AlN films were found to vary strongly with seed layer material and thickness. The smoothest Mo electrodes were obtained on thin Ti films. Reactive sputtering of AlN on top of these optimized electrodes resulted in a dense columnar grain structure with a well-aligned (002) crystal orientation and good electro-acoustic properties, including an effective coupling coefficient of 6.89% and quality factor above 1000.

    Original languageEnglish
    Pages (from-to)6588-6592
    Number of pages5
    JournalThin Solid Films
    Issue number24
    Publication statusPublished - 2009
    MoE publication typeA1 Journal article-refereed



    • Aluminium nitride
    • Sputtering
    • Piezoelectric effect
    • Crystallization
    • Surface morphology
    • Molybdenum
    • Nickel
    • Titanium

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