Experimental Investigation of Acoustic Substrate Losses in 1850-MHz Thin Film BAW Resonators

Tuomas Pensala, Robert Thalhammer, James Dekker, Jyrki Kaitila

    Research output: Contribution to journalArticleScientificpeer-review

    10 Citations (Scopus)

    Abstract

    After optimizing for electromechanical coupling coefficient K2, the main performance improvement in the thin film bulk acoustic wave resonators and filters can be achieved by improving the Q value, i.e., minimizing the losses. In Bragg-reflector-based solidly mounted resonator technology, a significant improvement of Q has been achieved by optimizing the reflector not only for longitudinal wave, the intended operation mode, but also for shear waves. We have investigated the remaining acoustic radiation losses to the substrate in so-optimized 1850-MHz AlN resonators by removing the substrate underneath the resonators and comparing the devices with and without substrate by electrical characterization before and after the substrate removal. Several methods to extract Q-values of the resonators are compared. Changes caused by substrate removal are observed in resonator behavior, but no significant improvement in Q-values can be confirmed. Loss mechanisms other than substrate leakage are concluded to dominate the resonator Q-value. Difficulties of detecting small changes in the Q-values of the resonators are also discussed.
    Original languageEnglish
    Pages (from-to)2544-2552
    Number of pages9
    JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
    Volume56
    Issue number11
    DOIs
    Publication statusPublished - 2009
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Resonators
    Acoustics
    resonators
    Thin films
    acoustics
    Substrates
    thin films
    Bragg reflectors
    Electromechanical coupling
    Shear waves
    longitudinal waves
    coupling coefficients
    sound waves
    reflectors
    S waves
    leakage
    Acoustic waves
    filters
    Radiation

    Cite this

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    title = "Experimental Investigation of Acoustic Substrate Losses in 1850-MHz Thin Film BAW Resonators",
    abstract = "After optimizing for electromechanical coupling coefficient K2, the main performance improvement in the thin film bulk acoustic wave resonators and filters can be achieved by improving the Q value, i.e., minimizing the losses. In Bragg-reflector-based solidly mounted resonator technology, a significant improvement of Q has been achieved by optimizing the reflector not only for longitudinal wave, the intended operation mode, but also for shear waves. We have investigated the remaining acoustic radiation losses to the substrate in so-optimized 1850-MHz AlN resonators by removing the substrate underneath the resonators and comparing the devices with and without substrate by electrical characterization before and after the substrate removal. Several methods to extract Q-values of the resonators are compared. Changes caused by substrate removal are observed in resonator behavior, but no significant improvement in Q-values can be confirmed. Loss mechanisms other than substrate leakage are concluded to dominate the resonator Q-value. Difficulties of detecting small changes in the Q-values of the resonators are also discussed.",
    author = "Tuomas Pensala and Robert Thalhammer and James Dekker and Jyrki Kaitila",
    year = "2009",
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    journal = "IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control",
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    Experimental Investigation of Acoustic Substrate Losses in 1850-MHz Thin Film BAW Resonators. / Pensala, Tuomas; Thalhammer, Robert; Dekker, James; Kaitila, Jyrki.

    In: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 56, No. 11, 2009, p. 2544-2552.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Experimental Investigation of Acoustic Substrate Losses in 1850-MHz Thin Film BAW Resonators

    AU - Pensala, Tuomas

    AU - Thalhammer, Robert

    AU - Dekker, James

    AU - Kaitila, Jyrki

    PY - 2009

    Y1 - 2009

    N2 - After optimizing for electromechanical coupling coefficient K2, the main performance improvement in the thin film bulk acoustic wave resonators and filters can be achieved by improving the Q value, i.e., minimizing the losses. In Bragg-reflector-based solidly mounted resonator technology, a significant improvement of Q has been achieved by optimizing the reflector not only for longitudinal wave, the intended operation mode, but also for shear waves. We have investigated the remaining acoustic radiation losses to the substrate in so-optimized 1850-MHz AlN resonators by removing the substrate underneath the resonators and comparing the devices with and without substrate by electrical characterization before and after the substrate removal. Several methods to extract Q-values of the resonators are compared. Changes caused by substrate removal are observed in resonator behavior, but no significant improvement in Q-values can be confirmed. Loss mechanisms other than substrate leakage are concluded to dominate the resonator Q-value. Difficulties of detecting small changes in the Q-values of the resonators are also discussed.

    AB - After optimizing for electromechanical coupling coefficient K2, the main performance improvement in the thin film bulk acoustic wave resonators and filters can be achieved by improving the Q value, i.e., minimizing the losses. In Bragg-reflector-based solidly mounted resonator technology, a significant improvement of Q has been achieved by optimizing the reflector not only for longitudinal wave, the intended operation mode, but also for shear waves. We have investigated the remaining acoustic radiation losses to the substrate in so-optimized 1850-MHz AlN resonators by removing the substrate underneath the resonators and comparing the devices with and without substrate by electrical characterization before and after the substrate removal. Several methods to extract Q-values of the resonators are compared. Changes caused by substrate removal are observed in resonator behavior, but no significant improvement in Q-values can be confirmed. Loss mechanisms other than substrate leakage are concluded to dominate the resonator Q-value. Difficulties of detecting small changes in the Q-values of the resonators are also discussed.

    U2 - 10.1109/TUFFC.2009.1341

    DO - 10.1109/TUFFC.2009.1341

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    EP - 2552

    JO - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

    JF - IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control

    SN - 0885-3010

    IS - 11

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