Characterization of Acoustic Losses in Interdigitated VHF to mmWave Piezoelectric M/NEMS Resonators

This work reports on a technology-agnostic and frequency-independent methodology combining a-priori modeling, Finite Element Analysis (FEA), and experimental results for the characterization of acoustic losses in interdigitated piezoelectric micro- and nano-electromechanical (M/NEMS) resonators. The proposed approach models the mechanical quality factor (Q<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</inf>) and its dependency on piezoelectric (Q<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">piezo</inf>) and metal (Q<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">metal</inf>) acoustic losses, as a function of the mode of vibration dispersion characteristics. The model is finally experimentally validated by exploiting the intrinsic on-chip multifrequency manufacturability of interdigitated devices.A broad range of available resonator technologies, frequencies, and piezoelectric materials are investigated for this purpose, including bulk X-cut Lithium Niobate (XLN) leaky surface acoustic wave resonators operating at Ultra High Frequency (UHF), thin film XLN Lamb Wave resonators spanning between Very High Frequency (VHF) and the K<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</inf> band, and Aluminum Nitride (AlN) and scandium-doped AlN (ScAlN) cross-sectional lamé mode resonators ranging from the K<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</inf> to K<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</inf> band (mmWave).