In-plane acoustic reflectors for reducing effective anchor loss in lateral?extensional MEMS resonators
01 Aug 2011-Journal of Micromechanics and Microengineering (IOP Publishing)-Vol. 21, Iss: 8, pp 085021
TL;DR: In this paper, in-plane acoustic reflectors are proposed to enhance the quality factor (Q) in lateral-mode micromachined resonators, which can reduce the overall anchor loss with minimum modification in the resonator design.
Abstract: In this paper, novel in-plane acoustic reflectors are proposed to enhance the quality factor (Q) in lateral-mode micromachined resonators. Finite element coupled-domain simulation is used to model anchor loss and to estimate the relative change in the resonator's performance without and with the inclusion of acoustic reflectors. Several 27 and 110 MHz AlN-on-silicon resonators are fabricated and measured to validate the theoretical and simulated data. An average Q enhancement of up to 560% is reported for specific designs with reflectors over the same resonators without reflectors. The measured results trend well with the simulated data and support that the acoustic reflectors can reduce the overall anchor loss with minimum modification in the resonator design.
Citations
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TL;DR: In this paper, the state-of-the-art of the development of aluminum nitride (AlN) thin-film microelectromechanical systems (MEMS) with particular emphasis on acoustic devices for radio frequency (RF) signal processing.
Abstract: This article reports on the state-of-the-art of the development of aluminum nitride (AlN) thin-film microelectromechanical systems (MEMS) with particular emphasis on acoustic devices for radio frequency (RF) signal processing. Examples of resonant devices are reviewed to highlight the capabilities of AlN as an integrated circuit compatible material for the implementation of RF filters and oscillators. The commercial success of thin-film bulk acoustic resonators is presented to show how AlN has de facto become an industrial standard for the synthesis of high performance duplexers. The article also reports on the development of a new class of AlN acoustic resonators that are directly integrated with circuits and enable a new generation of reconfigurable narrowband filters and oscillators. Research efforts related to the deposition of doped AlN films and the scaling of sputtered AlN films into the nano realm are also provided as examples of possible future material developments that could expand the range of applicability of AlN MEMS.
172 citations
TL;DR: A review of the remarkable progress that has been made during the past few decades in design, modeling, and fabrication of micromachined resonators with references to the most influential contributions in the field for those interested in a deeper understanding of the material.
Abstract: This paper is a review of the remarkable progress that has been made during the past few decades in design, modeling, and fabrication of micromachined resonators. Although micro-resonators have come a long way since their early days of development, they are yet to fulfill the rightful vision of their pervasive use across a wide variety of applications. This is partially due to the complexities associated with the physics that limit their performance, the intricacies involved in the processes that are used in their manufacturing, and the trade-offs in using different transduction mechanisms for their implementation. This work is intended to offer a brief introduction to all such details with references to the most influential contributions in the field for those interested in a deeper understanding of the material.
162 citations
Cites background from "In-plane acoustic reflectors for re..."
...Such acoustic reflectors could simply be trenches etched into the substrate [104,105] or phononic crystal structures that are tuned to block a narrow band centered around the frequency trapped in the resonant cavity [106,107]....
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TL;DR: In this article, the authors make an overview of the progress made during the last decade with regard to a novel class of piezoelectric microwave devices employing acoustic Lamb waves in micromachined thin film membranes.
Abstract: This work makes an overview of the progress made during the last decade with regard to a novel class of piezoelectric microwave devices employing acoustic Lamb waves in micromachined thin film membranes. This class of devices is referred to as either thin film Lamb wave resonators or piezoelectric contour-mode resonators both employing thin film aluminum nitride membranes. These devices are of interest for applications in both frequency control and sensing. High quality factor Lamb wave resonators exhibiting low noise, low loss and thermally stable performance are demonstrated and their application in high resolution gravimetric and pressure sensors further discussed. A specific emphasis is put on the ability of these devices to operate in contact with liquids. Future research directions are further outlined.
140 citations
TL;DR: In this article, the authors analyzed possible sources of dissipation in AlN contour mode resonators for three different resonance frequency devices (220 MHz, 370 MHz, and 1.05 GHz).
Abstract: In this paper, we analyze possible sources of dissipation in aluminium nitride (AlN) contour mode resonators for three different resonance frequency devices ( ${f} _{\!r}$ ) (220 MHz, 370 MHz, and 1.05 GHz). For this purpose, anchors of different widths ( ${W} _{\!a}$ ) and lengths ( ${L} _{\!a}$ ) proportional to the acoustic wavelength ( $\lambda $ ) are designed as supports for resonators in which the dimensions of the vibrating body are kept fixed. The ${Q}$ extracted experimentally confirms that anchor losses are the dominant source of damping for most anchor designs when ${f} _{\!r}$ is equal to 220 and 370 MHz. For specific anchor dimensions ( ${W} _{\!a}$ / $\lambda $ is in the range of 1/4–1/2) that mitigate energy leakage through the supports, a temperature-dependent dissipation mechanism dominates as seen in higher ${f} _{\!r}$ resonators operating close to 1.05 GHz. To describe the ${Q}$ due to anchor losses, we use a finite-element method with absorbing boundary conditions. We also propose a simple analytical formulation for describing the dependence of the temperature-dependent damping mechanism on frequency. In this way, we are able to quantitatively predict ${Q}$ due to anchor losses and qualitatively describe the trends observed experimentally. [2014-0232]
113 citations
Additional excerpts
...in laterally-vibrating MEMS resonators [28]–[31]....
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01 Mar 2000
Abstract: The importance of thermoelastic damping as a fundamental dissipation mechanism for small-scale mechanical resonators is evaluated in light of recent efforts to design high-Q micrometer- and nanometer-scale electromechanical systems. The equations of linear thermoelasticity are used to give a simple derivation for thermoelastic damping of small flexural vibrations in thin beams. It is shown that Zener’s well-known approximation by a Lorentzian with a single thermal relaxation time slightly deviates from the exact expression.
106 citations
References
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TL;DR: Numerical experiments and numerical comparisons show that the PML technique works better than the others in all cases; using it allows to obtain a higher accuracy in some problems and a release of computational requirements in some others.
9,875 citations
TL;DR: In this paper, the importance of thermoelastic damping as a fundamental dissipation mechanism for small-scale mechanical resonators is evaluated in light of recent efforts to design high-Q micrometer-and nanometer-scale electromechanical systems.
Abstract: The importance of thermoelastic damping as a fundamental dissipation mechanism for small-scale mechanical resonators is evaluated in light of recent efforts to design high-Q micrometer- and nanometer-scale electromechanical systems. The equations of linear thermoelasticity are used to give a simple derivation for thermoelastic damping of small flexural vibrations in thin beams. It is shown that Zener’s well-known approximation by a Lorentzian with a single thermal relaxation time slightly deviates from the exact expression.
1,028 citations
Book•
22 Feb 2000
TL;DR: In this paper, the authors present a detailed development of the acoustical wave equation, including propagation in Stratified media and propagation in Dissipative Fluids: Absorption and Dispersion.
Abstract: Detailed Development of the Acoustical Wave Equation. Reflection and Transmission of Normally Incident Plane Waves of Arbitrary Waveform. Normal Incidence Continued: Steady-State Analysis. Transmission Phenomena: Oblique Incidence. Normal Modes in Cartesian Coordinates: Strings, Membranes, Rooms, and Rectangular Waveguides. Horns. Propagation in Stratified Media. Propagation in Dissipative Fluids: Absorption and Dispersion. Spherical Waves. Cylindrical Waves. Waveguides. Radiation from a Baffled Piston. Diffraction. Arrays. Appendices. Index.
920 citations
Book•
13 Aug 1998
TL;DR: A cognitive journey towards the reliable simulation of scattering problems using finite element methods, with the pre-asymptotic analysis of Galerkin FEM for the Helmholtz equation with moderate and large wave number forming the core of this book, is described in this article.
Abstract: A cognitive journey towards the reliable simulation of scattering problems using finite element methods, with the pre-asymptotic analysis of Galerkin FEM for the Helmholtz equation with moderate and large wave number forming the core of this book. Starting from the basic physical assumptions, the author methodically develops both the strong and weak forms of the governing equations, while the main chapter on finite element analysis is preceded by a systematic treatment of Galerkin methods for indefinite sesquilinear forms. In the final chapter, three dimensional computational simulations are presented and compared with experimental data. The author also includes broad reference material on numerical methods for the Helmholtz equation in unbounded domains, including Dirichlet-to-Neumann methods, absorbing boundary conditions, infinite elements and the perfectly matched layer. A self-contained and easily readable work.
859 citations
Book•
01 Jul 1998
TL;DR: In this paper, the authors present a comparison of SAW filter design for Arbitrary Amplitude/Phase Response (AQR) and second-order effects in SAW filters.
Abstract: Fundamentals of Surface Acoustic Waves and Devices: Introduction. Basics of Piezoelectricity and Acoustic Waves. Principles of Linear Phase SAW Filter Design. Equivalent Circuit and Analytic Models for a SAW Filter. SomeMatching and Trade-Off Concepts for SAW Filter Design. Compensation for Second-Order Effects in SAW Filters. Designing SAW Filters for Arbitrary Amplitude/Phase Response. Interdigital Transducers with Chirped or Slanted Fingers. IDT Finger Reflections andRadiation Conductance. Techniques, Devices and Mobile/Wireless Applications: Overview of Systems and Devices. SAW Reflection Gratings and Resonators. Single-Phase Unidirectional Transducers for Low-Loss Filters. RF and Antenna-Duplexer Filters forMobile/Wireless Transceivers. Other RF Front-end and Inter-stage Filters for Mobile/Wireless Transceivers. SAW IF Filters for Mobile Phones and Pagers. Fixed-Code SAW IDTs for Spread-Spectrum Communications. Real-Time SAW Convolvers for Voice and Data Spread-Spectrum Communications. Surface Wave Oscillators and Frequency Synthesizers. SAW Filters for Digital Microwave Radio, Fiber Optic, and Satellite Systems. Postscript. Subject Index.
696 citations