Microelectromechanical filters for signal processing

Author

Lin, Liwei ; Howe, Roger T. ; Pisano, Albert P.

Author_Institution

Dept. of Mech. Eng., Michigan Univ., Ann Arbor, MI, USA

Volume

7

Issue

3

fYear

1998

fDate

9/1/1998 12:00:00 AM

Firstpage

286

Lastpage

294

Abstract

Microelectromechanical filters based on coupled lateral microresonators are demonstrated. This new class of microelectromechanical systems (MEMS) has potential signal-processing applications for filters which require narrow bandwidth (high Q), good signal-to-noise ratio, and stable temperature and aging characteristics. Microfilters presented in this paper are made by surface-micromachining technologies and tested by using an off-chip modulation technique. The frequency range of these filters is from approximately 5 kHz to on the order of 1 MHz for polysilicon microstructures with suspension beams having a 2-μm-square cross section. A series-coupled resonator pair, designed for operation at atmospheric pressure, has a measured center frequency of 18.7 kHz and a pass bandwidth of 1.2 kHz. A planar hermetic sealing process has been developed to enable high quality factors for these mechanical filters and make possible wafer-level vacuum encapsulations. This process uses a low-stress silicon nitride shell for vacuum sealing, and experimental results show that a measured quality factor of 2200 for comb-shape microresonators can be achieved

Keywords

Q-factor; ageing; elemental semiconductors; micromachining; micromechanical resonators; resonator filters; seals (stoppers); silicon; 1.2 kHz; 5 kHz to 1 MHz; Si; aging characteristics; bandwidth; center frequency; comb-shape microresonators; coupled lateral microresonators; microelectromechanical filters; microfilters; off-chip modulation technique; pass bandwidth; planar hermetic sealing process; polysilicon microstructures; quality factors; series-coupled resonator pair; signal-processing applications; signal-to-noise ratio; surface-micromachining technologies; suspension beams; temperature characteristics; vacuum sealing; wafer-level vacuum encapsulations; Band pass filters; Bandwidth; Frequency; Microcavities; Microelectromechanical systems; Micromechanical devices; Q factor; Resonator filters; Signal processing; Signal to noise ratio;

fLanguage

English

Journal_Title

Microelectromechanical Systems, Journal of

Publisher

ieee

ISSN

1057-7157

Type

jour

DOI

10.1109/84.709645

Filename

709645