Acoustic dispersion of solidly mounted resonators with an optimized reflector stack for dual wave reflection

Sumy Jose, Raymond Josephus Engelbart Hueting, Andreas Jansman

    Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

    Abstract

    Spurious resonance suppression in Bulk Acoustic Wave (BAW) resonators is essential for achieving excellent filter characteristics. These spurious resonances are undesired resonances caused by the finite device edges. The type I mode is the preferred dispersion response for "spurious modes" suppression, since it allows for the direct use of the frame region as the edge termination of the device. In this work we present a novel analytical approach to adjust the dispersion response in a desired way for various material combinations. By employing the diffraction grating method (DGM), which provides dual wave reflection after tailoring the layer stack thickness analytically, we obtain a type I dispersion curve despite the use of a type II piezoelectric material for the resonator. The dispersion response was verified from analytical impedance curves and FEM simulations. The reason for this type of response can be the inherent thicker top-oxide layer. A transmission of -37dB is maintained for longitudinal waves whereas shear waves reach value below -22 dB for a five layer SiO2/W stack, while for a three layer SiOC/Pt (935/555nm) stack -36dB and -24dB is obtained, respectively.
    Original languageUndefined
    Title of host publicationProceedings of the IEEE International Ultrasonics Symposium, IUS 2010
    Place of PublicationUSA
    PublisherIEEE Ultrasonics, Ferroelectrics & Frequency Control Society
    Pages91-94
    Number of pages4
    ISBN (Print)978-1-4577-0382-9
    DOIs
    Publication statusPublished - 11 Oct 2010
    EventIEEE International Ultrasonics Symposium, IUS 2010 - San Diego, United States
    Duration: 11 Oct 201014 Oct 2010

    Publication series

    Name
    PublisherIEEE Ultrasonics, Ferroelectrics & Frequency Control Society

    Conference

    ConferenceIEEE International Ultrasonics Symposium, IUS 2010
    Abbreviated titleIUS
    CountryUnited States
    CitySan Diego
    Period11/10/1014/10/10

    Keywords

    • METIS-279672
    • Dual reflection
    • Bulk Acoustic Wave (BAW)
    • EWI-20733
    • Dispersion
    • Diffraction grating (DG)
    • Solidly Mounted Resonator (SMR)
    • IR-78328

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