Micromachined High Frequency Acoustic Wave Resonators and Filters

A special issue of Micromachines (ISSN 2072-666X).

Deadline for manuscript submissions: closed (15 February 2012) | Viewed by 28451

Special Issue Editor


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Guest Editor
Imec, Leuven, Belgium
Interests: MEMS; actuators; acoustics; packaging; sensors; micromachining

Special Issue Information

Dear Colleagues,

Resonators find widespread use as frequency references, timing devices and as frequency selective devices in RF spectral processing, as well as for sensing purposes. Coupling of two or more resonators (either electrically or mechanically) is used to obtain filters with the desired characteristics. To meet the specifications for these applications, e.g., in terms of reference oscillator stability and phase noise, or, the filter insertion loss and out-of-band rejection, the resonators must have a high quality factor Q (of a few thousand, even exceeding ten thousand). Furthermore, “size matters” and electronics manufacturers are prompting the miniaturization of components. Silicon-based micromachining or MEMS technology is rapidly emerging as an enabling technology to bring about the much needed, cost-effective, small, low weight and high performance components, while offering multiple on-chip components and integrated signal processing. Although electromagnetic wave resonators (like LC resonators or cavity resonators) do exist, these cannot satisfy the size and Q requirements for a number of applications. Mechanical resonators or, more appropriately, acoustic wave (AW) resonators offer a very interesting alternative, and in some cases even present the only available solution, as for a given frequency the size is much smaller, while displaying Q-factors, that are one to two orders of magnitude better than the Q-factor of electromagnetic resonators.

Accordingly, we hereby announce a special issue addressing advances in design, fabrication, packaging, and, testing and characterization of micromachined high frequency acoustic wave resonators and filters, fashioned with silicon, dielectrics, piezoelectrics, carbon nanotube (CNT), metals and others. Example topics include RF bulk acoustic wave (RF-BAW) resonators and RF front-end filters, microelectromechanical (MEM) resonators (including quartz crystals), all-silicon CMOS-MEMS oscillator, drive and detection methods, frequency accuracy and trimming, resonator long term and temperature stability, Q-factor limitation, and, tunable resonators and filters. Related novel systems concepts and application proposals are acceptable contributions.

Dr. Harrie A. C. Tilmans
Guest Editor

Keywords

  • microelectromechanical resonator/filter
  • acoustic wave resonator
  • BAW resonator/filter
  • FBAR
  • SAW resonator/filter
  • flexural beam resonator
  • MEM-based reference oscillator
  • RF bandpass filter
  • RF radio front-end
  • vibration actuators
  • vibration sensors
  • acoustic resonators
  • vibrating ultrasound transducers

Published Papers (2 papers)

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3380 KiB  
Article
High-Q MEMS Resonators for Laser Beam Scanning Displays
by Ulrich Hofmann, Joachim Janes and Hans-Joachim Quenzer
Micromachines 2012, 3(2), 509-528; https://doi.org/10.3390/mi3020509 - 06 Jun 2012
Cited by 129 | Viewed by 19643
Abstract
This paper reports on design, fabrication and characterization of high-Q MEMS resonators to be used in optical applications like laser displays and LIDAR range sensors. Stacked vertical comb drives for electrostatic actuation of single-axis scanners and biaxial MEMS mirrors were realized in a [...] Read more.
This paper reports on design, fabrication and characterization of high-Q MEMS resonators to be used in optical applications like laser displays and LIDAR range sensors. Stacked vertical comb drives for electrostatic actuation of single-axis scanners and biaxial MEMS mirrors were realized in a dual layer polysilicon SOI process. High Q-factors up to 145,000 have been achieved applying wafer level vacuum packaging technology including deposition of titanium thin film getters. The effective reduction of gas damping allows the MEMS actuator to achieve large amplitudes at high oscillation frequencies while driving voltage and power consumption can be minimized. Exemplarily shown is a micro scanner that achieves a total optical scan angle of 86 degrees at a resonant frequency of 30.8 kHz, which fulfills the requirements for HD720 resolution. Furthermore, results of a new wafer based glass-forming technology for fabrication of three dimensionally shaped glass lids with tilted optical windows are presented. Full article
(This article belongs to the Special Issue Micromachined High Frequency Acoustic Wave Resonators and Filters)
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575 KiB  
Article
Temperature Frequency Characteristics of Hexamethyldisiloxane (HMDSO) Polymer Coated Rayleigh Surface Acoustic Wave (SAW) Resonators for Gas-Phase Sensor Applications
by Karekin D. Esmeryan, Ivan D. Avramov and Ekaterina I. Radeva
Micromachines 2012, 3(2), 413-426; https://doi.org/10.3390/mi3020413 - 02 May 2012
Cited by 10 | Viewed by 8352
Abstract
Temperature induced frequency shifts may compromise the sensor response of polymer coated acoustic wave gas-phase sensors operating in environments of variable temperature. To correct the sensor data with the temperature response of the sensor the latter must be known. This study presents and [...] Read more.
Temperature induced frequency shifts may compromise the sensor response of polymer coated acoustic wave gas-phase sensors operating in environments of variable temperature. To correct the sensor data with the temperature response of the sensor the latter must be known. This study presents and discusses temperature frequency characteristics (TFCs) of solid hexamethyldisiloxane (HMDSO) polymer coated sensor resonators using the Rayleigh surface acoustic wave (RSAW) mode on ST-cut quartz. Using a RF-plasma polymerization process, RSAW sensor resonators optimized for maximum gas sensitivity have been coated with chemosensitive HMDSO films at 4 different thicknesses: 50, 100, 150 and 250 nm. Their TFCs have been measured over a (−100 to +110) °C temperature range and compared to the TFC of an uncoated device. An exponential 2,500 ppm downshift of the resonant frequency and a 40 K downshift of the sensor’s turn-over temperature (TOT) are observed when the HMDSO thickness increases from 0 to 250 nm. A partial temperature compensation effect caused by the film is also observed. A third order polynomial fit provides excellent agreement with the experimental TFC curve. The frequency downshift due to mass loading by the film, the TOT and the temperature coefficients are unambiguously related to each other. Full article
(This article belongs to the Special Issue Micromachined High Frequency Acoustic Wave Resonators and Filters)
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