High-Q mechanical tuning of MEMS resonators using a metal deposition - annealing technique

Courcimault, Christophe; Allen, Mark G.

doi:10.1109/sensor.2005.1496557

Cited by 23 publications

(14 citation statements)

References 11 publications

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“…Whereas it is believed that AlN is a high Q material, the metal electrodes might be a primary source of energy loss. It has been shown in the literature [34], [35] that metals generally have low Q and could dramatically affect the overall Q of the resonator. Although this statement is purely speculative and has not been proven experimentally for contour-mode resonators, the authors strongly believe that the internal mechanical losses in the electrodes could be one of the primary reasons of Q degradation.…”

Section: Quality Factormentioning

confidence: 99%

Piezoelectric Aluminum Nitride Vibrating Contour-Mode MEMS Resonators

Piazza

Stephanou

Pisano

2006

J. Microelectromech. Syst.

573

307

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This paper reports theoretical analysis and experimental results on a new class of rectangular plate and ringshaped contour-mode piezoelectric aluminum nitride radio-frequency microelectromechanical systems resonators that span a frequency range from 19 to 656 MHz showing high-quality factors in air (Q max = 4300 at 229.9 MHz), low motional resistance (ranging from 50 to 700 Ω), and center frequencies that are lithographically defined. These resonators achieve the lowest value of motional resistance ever reported for contour-mode resonators and combine it with high Q factors, therefore enabling the fabrication of arrays of high-performance microresonators with different frequencies on a single chip. Uncompensated temperature coefficients of frequency of approximately 25 ppm/°C were also recorded for these resonators. Initial discussions on mass loading mechanisms induced by metal electrodes and energy loss phenomenon are provided. KeywordsAluminum nitride, contour-mode resonators, microelectromechanical systems (MEMS) resonators, piezoelectric resonators, radio-frequency (RF) MEMS This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Pennsylvania's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to pubs-permissions@ieee.org. By choosing to view this document, you agree to all provisions of the copyright laws protecting it. Abstract-This paper reports theoretical analysis and experimental results on a new class of rectangular plate and ring-shaped contour-mode piezoelectric aluminum nitride radio-frequency microelectromechanical systems resonators that span a frequency range from 19 to 656 MHz showing high-quality factors in air (Q max = 4300 at 229.9 MHz), low motional resistance (ranging from 50 to 700 ), and center frequencies that are lithographically defined. These resonators achieve the lowest value of motional resistance ever reported for contour-mode resonators and combine it with high Q factors, therefore enabling the fabrication of arrays of high-performance microresonators with different frequencies on a single chip. Uncompensated temperature coefficients of frequency of approximately 25 ppm C were also recorded for these resonators. Initial discussions on mass loading mechanisms induced by metal electrodes and energy loss phenomenon are provided.[ 2006-0019]Index Terms-Aluminum nitride, contour-mode resonators, microelectromechanical systems (MEMS) resonators, piezoelectric resonators, radio-frequency (RF) MEMS.

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Section: Quality Factormentioning

confidence: 99%

Piezoelectric Aluminum Nitride Vibrating Contour-Mode MEMS Resonators

Piazza

Stephanou

Pisano

2006

J. Microelectromech. Syst.

573

307

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“…In fact, experimental data shows that as the thickness of a piezoelectric resonator's electrode increases, both the resonance frequency and Q of the resonator drop due to mass loading and electrode loss, respectively [29]. Electrode-derived energy loss perhaps also contributes to the lower Q's measured for d 31 -transduced AlN resonators, where electrodes often cover maximum-strain locations, versus those for d 33 -transduced thickness-mode resonators, for which electrodes are placed very close to the antinodes of the acoustic standing waves.…”

Section: Metal Electrode-induced Degradationmentioning

confidence: 99%

Capacitive-Piezoelectric Transducers for High-<inline-formula> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> Micromechanical AlN Resonators

Hung

Nguyen

2015

J. Microelectromech. Syst.

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A capacitive-piezoelectric (also known as, capacitive-piezo) transducer that combines the strengths of capacitive and piezoelectric mechanisms to achieve a combination of electromechanical coupling and Q higher than otherwise attainable by either mechanism separately, has allowed demonstration of a 1.2-GHz contour-mode aluminum nitride (AlN) ring resonator with Q > 3000 on par with the highest measured d 31 -transduced AlN-only piezoelectric resonators past 1 GHz, and a 50-MHz disk array with an even higher Q > 12 000. Here, the key innovation is to separate the piezoelectric resonator from its metal electrodes by tiny gaps to eliminate metal material and metal-to-piezoelectric interface losses thought to limit thin-film piezoelectric resonator Q, while also maintaining high electric field strength to preserve a strong piezoelectric effect. While Q increases, electromechanical coupling decreases, but the k 2 eff · Q product can still increase overall. More importantly, use of the capacitive-piezo transducer allows a designer to trade electromechanical coupling for Q, providing a very useful method to tailor Q and coupling for narrowband radio frequency (RF) channel-selecting filters for which Q trumps coupling. This capacitive-piezo transducer concept does not require dc-bias voltages and allows for much thicker electrodes that reduce series resistance without mass loading the resonant structure. The latter is especially important as resonators and their supports continue to scale toward even higher frequencies.[2013-0395]

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“…In fact, numerous experimental data at the time showed that both Q and resonance frequency decrease with increasing metal electrode thickness [8]. These observations eventually led to the demonstration of the spaced-electrode quartz BVA resonator design, which used a non-contacting electrode to alleviate or eliminate such electrode-derived problems as damping, stress, contamination, and ion migration.…”

Section: Capacitive-piezoelectric Transductionmentioning

confidence: 99%

High-Q capacitive-piezoelectric AlN Lamb wave resonators

Yen

Pisano

Nguyen

2013

2013 IEEE 26th International Conference on Micro Electro Mechanical Systems (MEMS)

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The use of capacitive-piezoelectric transducers, formed by separating a piezoelectric structure from its electrodes by sub-micron gaps, has raised the measured quality factor of aluminum nitride (AlN) Lamb wave resonators (LWR) from the ~1,000 of typical square-edged conventional devices (with contacting electrodes) to over 5,000 at 940 MHz, posting the highest reported Q for non-overmoded pure AlN resonators using d 31 (e 31 ) transduction at this frequency range. The Q · f product achieved here is significantly higher than that of a previous 1.2-GHz capacitive-piezoelectric contour-mode ring, mainly due to the use of Lamb wave modes that allow better support isolation to prevent energy loss to the substrate. In addition, the use of interdigital transducer (IDT) electrodes successfully decouples the resonance frequency from overall device dimensions, offering a CAD-definable design parameter for fine-frequency control. The effective coupling coefficient of k eff 2 = 0.3% achieved by this device is lower than the 1.6% typically observed for conventional AlN Lamb wave resonators, but still sufficient to avoid pass-band distortion in the 0.1% bandwidth filters needed for next-generation RF channel-selecting communication front-ends.

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High-Q mechanical tuning of MEMS resonators using a metal deposition - annealing technique

Cited by 23 publications

References 11 publications

Piezoelectric Aluminum Nitride Vibrating Contour-Mode MEMS Resonators

Piezoelectric Aluminum Nitride Vibrating Contour-Mode MEMS Resonators

Capacitive-Piezoelectric Transducers for High-<inline-formula> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> Micromechanical AlN Resonators

High-Q capacitive-piezoelectric AlN Lamb wave resonators

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