RF-MEMS load sensors with enhanced Q-factor and sensitivity in a suspended architecture

  • Authors:

  • Rohat Melik;Emre Unal;Nihan Kosku Perkgoz;Christian Puttlitz;Hilmi Volkan Demir

  • Affiliations:

  • Departments of Electrical Engineering and Physics, Nanotechnology Research Center, and Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey;Departments of Electrical Engineering and Physics, Nanotechnology Research Center, and Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey;Departments of Electrical Engineering and Physics, Nanotechnology Research Center, and Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey;Department of Mechanical Engineering, Orthopaedic Bioengineering Research Laboratory, Colorado State University, Fort Collins, CO 80523, USA;Departments of Electrical Engineering and Physics, Nanotechnology Research Center, and Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey

  • Venue:
  • Microelectronic Engineering
  • Year:
  • 2011

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Abstract

In this paper, we present and demonstrate RF-MEMS load sensors designed and fabricated in a suspended architecture that increases their quality-factor (Q-factor), accompanied with an increased resonance frequency shift under load. The suspended architecture is obtained by removing silicon under the sensor. We compare two sensors that consist of 195@mmx195@mm resonators, where all of the resonator features are of equal dimensions, but one's substrate is partially removed (suspended architecture) and the other's is not (planar architecture). The single suspended device has a resonance of 15.18GHz with 102.06 Q-factor whereas the single planar device has the resonance at 15.01GHz and an associated Q-factor of 93.81. For the single planar device, we measured a resonance frequency shift of 430MHz with 3920N of applied load, while we achieved a 780MHz frequency shift in the single suspended device. In the planar triplet configuration (with three devices placed side by side on the same chip, with the two outmost ones serving as the receiver and the transmitter), we observed a 220MHz frequency shift with 3920N of applied load while we obtained a 340MHz frequency shift in the suspended triplet device with 3920N load applied. Thus, the single planar device exhibited a sensitivity level of 0.1097MHz/N while the single suspended device led to an improved sensitivity of 0.1990MHz/N. Similarly, with the planar triplet device having a sensitivity of 0.0561MHz/N, the suspended triplet device yielded an enhanced sensitivity of 0.0867MHz/N.