Quality factor improvement of piezoelectric MEMS resonator by the conjunction of frame structure and phononic crystals (original) (raw)
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Micromachines, 2019
Phononic crystals (PnC) are a remarkable example of acoustic metamaterials with superior wave attenuation mechanisms for piezoelectric micro-electro-mechanical systems (MEMS) resonators to reduce the energy dissipation. Herein, a spider web-like PnC (SW-PnC) is proposed to sufficiently isolate the wave vibration. Finite-element analysis is performed to gain insight into the transmission property of finite PnC, and band characteristics by infinite periods. In comparison with the circle hole PnC at a similar bandgap, due to its already very lightweight PnC structure compared with previously reported PnCs, the proposed PnC offers a significantly lighter weight, smaller lattice constant, and greater energy leakage inhibition. More specifically, the resonator with the SW-PnC plate as the anchoring substrate exhibited a quality factor as high as 66569.7 at 75.82 MHz.
Micromachines
Thin-film piezoelectric-on-silicon (TPoS) microelectromechanical (MEMS) resonators are required to have high Q-factor to offer satisfactory results in their application areas, such as oscillator, filter, and sensors. This paper proposed a phononic crystal (PnC)-reflector composite structure to improve the Q factor of TPoS resonators. A one-dimensional phononic crystal is designed and deployed on the tether aiming to suppress the acoustic leakage loss as the acoustic wave with frequency in the range of the PnC is not able to propagate through it, and a reflector is fixed on the anchoring boundaries to reflect the acoustic wave that lefts from the effect of the PnC. Several 10 MHz TPoS resonators are fabricated and tested from which the Q-factor of the proposed 10 MHz TPoS resonator which has PnC-reflector composite structure on the tether and anchoring boundaries achieved offers a loaded Q-factor of 4682 which is about a threefold improvement compared to that of the conventional reso...
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Journal of Microelectromechanical Systems, 2000
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High-Q multi-frequency ring-shaped piezoelectric MEMS resonators
Microelectronics Journal, 2020
While MEMS resonators are emerging as a promising integrated clock-chip solution, often quality factor (Q) and spurious modes limit device performance. Moreover, realizing high-Q and multi-frequency simultaneously in a piezoelectric MEMS resonator is still comparatively difficult. In this research, a ring-shaped MEMS resonator outfitted with optimized electrodes was proposed to significantly suppress undesired resonant modes and then boosts the Q of rest resonant modes. To systematically explore the proposed design, numerical and experimental investigations were performed, revealing that the presence of optimized electrodes helps to counterpoise distributions of surface charge density and displacement current density in vertical direction, thereby results in the suppression of spurious modes. The maximum unloaded quality factor (Q u) of the fabricated ring-shaped resonators was up to 10,069 at 83.59 MHz. The measurement results of the resonator with optimized electrodes yielded three resonant modes with Q u large than 5,000, indicating that the high-Q and multi-frequency ringshaped resonator was satisfactorily achieved.
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Available online xxx a b s t r a c t This paper presents a numerical study on anchor and interfacial dissipation in piezoelectric MEMS resonators with in-plane longitudinal-mode vibrations. According to recent proposals, interfacial dissipation is formulated in terms of the stress jump across the interface. A refined dedicated numerical tool is employed both to evaluate anchor losses and to implement the model of interface dissipation. Extensive comparisons with experimental data are performed showing excellent quantitative agreement.
Applied Physics Express, 2018
Thin-film piezoelectric-on-silicon acoustic wave resonators are promising for the development of system-on-chip integrated circuits with micro/ nano-engineered timing reference. However, in order to realize their large potentials, a further enhancement of the quality factor (Q) is required. In this study, a novel approach, based on a multi-stage phononic crystal (PnC) structure, was proposed to achieve an ultra-high Q. A systematical study revealed that the multi-stage PnC structure formed a frequency-selective band-gap to effectively prohibit the dissipation of acoustic waves through tethers, which significantly reduced the anchor loss, leading to an insertion-loss reduction and enhancement of Q. The maximum unloaded Q u of the fabricated resonators reached the value of >10,000 at 109.85 MHz, indicating an enhancement by 19.4 times.
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Frequency Characterization of AlN Piezoelectric Resonators
2007 IEEE International Frequency Control Symposium Joint with the 21st European Frequency and Time Forum, 2007
In this paper, we analyze the vibrational spectra of mechanical resonators actuated piezoelectrically with aluminum nitride (AlN) films. The microresonators consist in bimorph cantilevers with different lengths containing a piezoelectric metal/AlN/metal stack supported by a silicon nitride structural layer. The thicknesses of both the AlN and Si 3 N 4 layers are varied between 0.3 µm and 1 µm to study their influence on the mechanical response of the cantilevers. The motion of the cantilevers electrically driven is first assessed by optical laser interferometry; resonant frequencies varying between 100 kHz and 8 MHz are obtained. Additionally, many of the vibrational modes are detected by measuring the changes of the electrical impedance at the resonant frequencies. The mass detection factor of the cantilevers is assessed by measuring the frequency shift after mass loading with thin SiO 2 layers. A value of 0.18 fg/Hz is obtained for vibrational modes around MHz.
This article presents a new design of supporting tethers through the concept of force distribution. The transmitted force applied on tethers will be distributed on the new tether design area resulting in low acoustic energy transferred to anchor boundaries and stored energy enhancement. This technique achieves an anchor quality factor of 175,000 compared to 58,000 obtained from con-ventional tether design representing 3-fold enhancement. Also, the unloaded quality factor of the proposed design improved from 23,750 to 27,442 representing 1.2-fold improvements.
Waveguide-Based Phononic Crystal Micro/Nanomechanical High-$Q$ Resonators
Journal of Microelectromechanical Systems, 2000
In this paper, we report the design, analysis, fabrication, and characterization of a very high frequency phononic crystal (PnC) micro/nanomechanical resonator architecture based on silicon PnC slab waveguides. The PnC structure completely surrounds the resonant area, and the resonator is excited by a thin aluminum nitride-based piezoelectric transducer stack directly fabricated on top of the resonator. This architecture highly suppresses the support loss of the resonator to the surroundings while providing mechanical support and electrical signal delivery to the resonator. Qs as high as 13 500 in air at a frequency of ∼134 MHz with a motional resistance of ∼600 Ω and 35-dB spurious-free range of ∼20 MHz are obtained. Comparing the Q of this resonator with the previously reported lateral bulk acoustic wave resonators with a similar stack of layers confirms the support loss suppression in this architecture.