scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Design, Modeling and Fabrication of TPoS MEMS Resonators With Improved Performance at 1 GHz

22 Apr 2021-IEEE\/ASME Journal of Microelectromechanical Systems (Institute of Electrical and Electronics Engineers (IEEE))-Vol. 30, Iss: 3, pp 375-383
TL;DR: In this paper, the effects of physical dimensions such as length, width and thickness as well as the mode of vibration and the number of anchors on the performance of longitudinal thin film piezoelectric on silicon (TPoS) MEMS resonators have been studied.
Abstract: In this work, the effects of physical dimensions such as length, width and thickness as well as the mode of vibration and the number of anchors on the performance of longitudinal thin film piezoelectric on silicon (TPoS) MEMS resonators have been studied. TPoS resonators, designed for a resonant frequency of around 1 GHz, were fabricated with a 4 mask CMOS compatible process. A $225~\mu \text{m}$ wide resonator excited in its $23^{rd}$ order had an unloaded quality factor of 9453 (in vacuum), which is the highest value reported so far for similar resonators, motional resistance of $107~\Omega $ and linear thermal coefficient of frequency of -28.4 ppm. We have also studied and modeled the different loss mechanisms in these devices. The model matches well with measured results for resonators of different geometries, modes of vibrations and number of anchors. [2020-0397]
Citations
More filters
DOI
TL;DR: In this article , the effect of orientation on the acoustic band gap (ABG) of two PnC designs and their effect on boosting quality factor (Q) was explored, and it was shown that adding a hole into the disk to form a ring changes its ABG to be much more sensitive to orientation.
Abstract: Phononic crystals (PnCs) have been used to boost the quality factor (Q) of AlN-on-Silicon Lamb Wave Resonators (LWRs). But most reports on applying PnCs to resonators have focused on the common $< 110>$ orientation within (100) silicon. Little is known on the applicability of other crystal orientations. In this work, we explore the effect of orientation on the acoustic band gap (ABG) of two PnC designs and their effect on boosting Q: a disk PnC and a ring PnC. From Finite Element simulation, we show that the disk PnC’s ABG is insensitive to orientation while adding a hole into the disk to form a ring changes its ABG to be much more sensitive to orientation. Leveraging the PnCs as anchoring boundary of LWRs, the disk PnC exhibits comparable effectiveness to boost Q >11,000 in the $< 110>$ and $< 100>$ directions while the ring PnC is effective only in the $< 110>$ direction. We further corroborate these trends by incorporating the disk PnC into delay lines in either crystal axis.

1 citations

Journal ArticleDOI
TL;DR: In this article , the effect of orientation on the acoustic band gap (ABG) of two PnC designs and their effect on boosting quality factor (Q) of AlN-on-Silicon Lamb Wave Resonators (LWRs) was explored.
Abstract: Phononic crystals (PnCs) have been used to boost the quality factor (Q) of AlN-on-Silicon Lamb Wave Resonators (LWRs). But most reports on applying PnCs to resonators have focused on the common $< 110>$ orientation within (100) silicon. Little is known on the applicability of other crystal orientations. In this work, we explore the effect of orientation on the acoustic band gap (ABG) of two PnC designs and their effect on boosting Q: a disk PnC and a ring PnC. From Finite Element simulation, we show that the disk PnC’s ABG is insensitive to orientation while adding a hole into the disk to form a ring changes its ABG to be much more sensitive to orientation. Leveraging the PnCs as anchoring boundary of LWRs, the disk PnC exhibits comparable effectiveness to boost Q >11,000 in the $< 110>$ and $< 100>$ directions while the ring PnC is effective only in the $< 110>$ direction. We further corroborate these trends by incorporating the disk PnC into delay lines in either crystal axis.

1 citations

Proceedings ArticleDOI
17 Apr 2023
TL;DR: In this paper , the effect of additional loss due to the isotropic etch used to release the extensional mode thin piezoelectric on silicon (TPoS) resonators is reported and validated.
Abstract: This paper reports and validates the effect of additional loss due to the isotropic etch used to release the extensional mode thin piezoelectric on silicon (TPoS) resonators. Devices fabricated to operate at a resonant frequency around 1 GHz are kept at varying times in vapor HF to remove the buried oxide, thereby changing the additional area etched. When devices designed with different geometries are present in the same wafer, the etching times differ, causing more undercuts than required in some of the devices. The Quality factor (Q) calculated from the measured transmission characteristics is used to derive a semi-analytical model for the additional loss due to undercut. The total quality factor of these devices is estimated after adding other loss mechanisms with the help of simulations and is validated with measured experimental data from our group as well as those found in the literature. The Q predicted using this model matches the measured data for state-of-the-art devices with different frequencies, dimensions, and materials.
Proceedings ArticleDOI
17 Apr 2023
TL;DR: In this paper , the effect of additional loss due to the isotropic etch used to release the extensional mode thin piezoelectric on silicon (TPoS) resonators is reported and validated.
Abstract: This paper reports and validates the effect of additional loss due to the isotropic etch used to release the extensional mode thin piezoelectric on silicon (TPoS) resonators. Devices fabricated to operate at a resonant frequency around 1 GHz are kept at varying times in vapor HF to remove the buried oxide, thereby changing the additional area etched. When devices designed with different geometries are present in the same wafer, the etching times differ, causing more undercuts than required in some of the devices. The Quality factor (Q) calculated from the measured transmission characteristics is used to derive a semi-analytical model for the additional loss due to undercut. The total quality factor of these devices is estimated after adding other loss mechanisms with the help of simulations and is validated with measured experimental data from our group as well as those found in the literature. The Q predicted using this model matches the measured data for state-of-the-art devices with different frequencies, dimensions, and materials.
References
More filters
Journal ArticleDOI
29 Aug 2005
TL;DR: As vibrating RF MEMS devices are perceived more as circuit building blocks than as stand-alone devices, and as the frequency processing circuits they enable become larger and more complex, the makings of an integrated micromechanical circuit technology begin to take shape, perhaps with a functional breadth not unlike that of integrated transistor circuits.
Abstract: An overview on the vise of microelectromechanical systems (MEMS) technologies for timing and frequency control is presented. In particular, micromechanical RF filters and reference oscillators based on recently demonstrated vibrating on-chip micromechanical resonators with Q's > 10,000 at 1.5 GHz are described as an attractive solution to the increasing count of RF components (e.g., filters) expected to be needed by future multiband, multimode wireless devices. With Q's this high in on-chip abundance, such devices might also enable a paradigm shift in the design of timing and frequency control functions, where the advantages of high-Q are emphasized, rather than suppressed (e.g., due to size and cost reasons), resulting in enhanced robustness and power savings. Indeed, as vibrating RF MEMS devices are perceived more as circuit building blocks than as stand-alone devices, and as the frequency processing circuits they enable become larger and more complex, the makings of an integrated micromechanical circuit technology begin to take shape, perhaps with a functional breadth not unlike that of integrated transistor circuits. With even more aggressive three-dimensional MEMS technologies, even higher on-chip Q's are possible, such as already achieved via chip-scale atomic physics packages, which so far have achieved Q's > 107 using atomic cells measuring only 10 mm3 in volume and consuming just 5 mW of power, all while still allowing atomic clock Allan deviations down to 10-11 at one hour

776 citations

Journal ArticleDOI
TL;DR: In this article, the design, fabrication, and characterization of piezoelectrically-transduced micromechanical single-crystal-silicon resonators operating in their lateral bulk acoustic modes to address the need for high-Q microelectronic-integrable frequency-selective components is presented.
Abstract: This paper reports on the design, fabrication, and characterization of piezoelectrically-transduced micromechanical single-crystal-silicon resonators operating in their lateral bulk acoustic modes to address the need for high-Q microelectronic-integrable frequency-selective components. A simple electromechanical model for optimizing performance is presented. For verification, resonators were fabricated on 5-mum-thick silicon-on- insulator substrates and use a 0.3-mum zinc oxide film for transduction. A bulk acoustic mode was observed from a 240 mum times 40 mum resonator with a 600-Omega impedance (Q=3400 at P=1 atm) at 90 MHz. A linear resonator absorbed power of -0.5 dBm and an output current of 1.3 mA rms were measured. The same device also exhibited a Q of 12 000 in its fundamental extensional mode at a pressure of 5 torr.

198 citations

Proceedings ArticleDOI
21 Jun 2009
TL;DR: In this paper, the authors discuss the contribution of phonon interactions in determining the upper limit of the f.Q product in micromechanical resonators, and show that for frequencies higher than ω τ = 1/τ, where τ is the phonon relaxation time, the FQ product is no longer constant but a linear function of frequency.
Abstract: We discuss the contribution of phonon interactions in determining the upper limit of f.Q product in micromechanical resonators. There is a perception in the MEMS community that the maximum f.Q product of a microresonator is limited to a “frequency-independent constant” determined by the material properties of the resonator [1]. In this paper, we discuss that for frequencies higher than ω τ = 1/τ, where τ is the phonon relaxation time, the f.Q product is no longer constant but a linear function of frequency. This makes it possible to reach very high Qs in GHz micromechanical resonators. Moreover, we show that 〈100〉 is the preferred crystalline orientation for obtaining very high Q in bulk-acoustic-mode silicon resonators above ∼750 MHz, while 〈100〉 is the preferred direction for achieving high-Q at lower frequencies.

172 citations

Journal ArticleDOI
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

Journal ArticleDOI
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.

148 citations