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oai:recercat.cat:2117/871902026-02-04T03:34:50Zcom_2072_1033col_2072_452950

A thickness-shear MEMS resonator employing electromechanical transduction through a coplanar waveguide Johnson, W.L. Wallis, T.M. Kabos, P. Rocas Cantenys, Eduard Collado Gómez, Juan Carlos Liew, L.A. Ha, J.Y. Davydov, A.V. Plankis, A. Heyliger, P.R. Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions Universitat Politècnica de Catalunya. CSC - Components and Systems for Communications Research Group Microelectromechanical systems Acoustic power Acoustic resonance Electromechanical transduction Fabricated device Finite-element High damping MEMS resonators Noise levels Non-Linearity Nulling Orders of magnitude Out-of-plane displacement Reference lines Shear displacement Silicon-bridge SOI wafers Swept-frequency Thermoelastic damping Thickness-shear Vibrational trapping Waveguide thickness Sistemes microelectromecànics The design, modeling, fabrication, and characterization of a vibrationally trapped thickness-shear MEMS resonator is presented. This device is intended to avoid various limitations of flexural MEMS resonators, including nonlinearity, clamping losses, thermoelastic damping, and high damping in liquid. It includes a silicon bridge and a reference line on an SOI wafer, a coupled Au/Cr coplanar waveguide, Lorentz-force coupling, variations in waveguide thickness for vibrational trapping, and circuitry for nulling the components of the signal that are unrelated to the acoustic resonance. Finite-element vibrational modeling shows the lowest thickness-shear mode with a bridge thickness of 4.9 µm to be dominated by shear displacements, with the magnitude of out-of-plane displacements decreasing with increasing bridge width. Two-dimensional modeling of vibrational trapping, with central regions of the waveguides having 43 nm greater thickness, indicates that amplitudes are reduced by several orders of magnitude at the ends of the bridges for the fundamental ~ 400 MHz thickness-shear resonance. Sweptfrequency network-analyzer measurements of fabricated devices reveal no evidence for an acoustic resonance, despite a calculated prediction of levels of acoustic power absorption that are well above the measured noise level. A possible explanation for this result is stiction of the bridges to the substrate. Peer Reviewed Postprint (published version) 2012 Conference report Johnson, W., Wallis, T., Kabos, P., Rocas, E., Collado, J., Liew, L., Ha, J., Davydov, A., Plankis, A., Heyliger, P. A thickness-shear MEMS resonator employing electromechanical transduction through a coplanar waveguide. A: IEEE Frequency Control Symposium. "2012 IEEE International Frequency Control Symposium, IFCS 2012, Proceedings". 2012, p. 452-457. 978-145771819-9 https://hdl.handle.net/2117/87190 10.1109/FCS.2012.6243722 eng Restricted access - publisher's policy 6 p. application/pdf