Intrinsically Switchable Ferroelectric Scandium Aluminum Nitride Lamb-Mode Resonators

Rassay, Sushant; Mo, Dicheng; Li, Chao; Choudhary, Nitin; Forgey, Christian; Tabrizian, Roozbeh

doi:10.1109/led.2021.3078444

Cited by 30 publications

(14 citation statements)

References 18 publications

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“…Piezoelectrically transduced microscale resonant devices have broad applications such as inertial sensing, [ 33–36 ] radio frequency (RF) signal processing, [ 37–43 ] and environmental monitoring. [ 44,45 ] Within these fields, microscale piezoelectric resonators are widely used in various applications like frequency filtering, sensing, and clock generation.…”

Section: Introductionmentioning

confidence: 99%

Influence of a Tailored Oxide Interface on the Quality Factor of Microelectromechanical Resonators

Lynes

Chandrahalim

2023

Adv Materials Inter

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Piezoelectric microelectromechanical systems (MEMS) are used as sensors, actuators, energy harvesters, accelerometers, and communication modules. Aluminum nitride (AlN) is an especially attractive piezoelectric material because its fabrication process allows it to be integrated into semiconductor circuitry to deliver a fully integrated solution. Microelectromechanical resonators with AlN sandwiched between n‐type silicon (Si) and top metal electrode with and without a silicon oxide layer are designed and fabricated. The effect of the oxide film is up to a fourfold increase in quality factor (Q) that is consistent from very high frequency (VHF) to super high frequency (SHF). This effect is demonstrated using thin plate bulk acoustic wave modes from 70–80 MHz using the second contour mode and first width extensional mode and from 9.5–10.5 GHz using high overtone thickness modes. To explore potential applications of AlN‐transduced Q‐enhanced MEMS devices in harsh environments, measurements from −200 °C to +200 °C are performed. The Q enhancement is persistent across a wide temperature range for both VHF and SHF resonators with the added oxide layer. Furthermore, AlN‐on‐Si resonators that have a comparable temperature coefficient of frequency to silicon carbide‐based resonators in commercial applications are demonstrated.

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Section: Introductionmentioning

confidence: 99%

Influence of a Tailored Oxide Interface on the Quality Factor of Microelectromechanical Resonators

Lynes

Chandrahalim

2023

Adv Materials Inter

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“…After a few years, in 2018, Fichtner [10] demonstrated a robust and repeatable ferroelectric behavior within the material, which opened new paths to multi-functional MEMS by combining the improved piezoelectric performance with the memory capability within the same BEOL-compatible process flow. Examples are the switchable FBARs [11,12], diodes [13], and ferroelectric transducers [14]. Nonetheless, the ferroelectric properties still face large limitations in their applicability.…”

Section: Introductionmentioning

confidence: 99%

Effect of Substrate-RF on Sub-200 nm Al0.7Sc0.3N Thin Films

et al. 2022

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Sc-doped aluminum nitride is emerging as a new piezoelectric material which can substitute undoped aluminum nitride (AlN) in radio-frequency MEMS applications, thanks to its demonstrated enhancement of the piezoelectric coefficients. Furthermore, the recent demonstration of the ferroelectric-switching capability of the material gives AlScN the possibility to integrate memory functionalities in RF components. However, its high-coercive field and high-leakage currents are limiting its applicability. Residual stress, growth on different substrates, and testing-temperature have already been demonstrated as possible knobs to flatten the energy barrier needed for switching, but no investigation has been reported yet on the whole impact on the dielectric and ferroelectric dynamic behavior of a single process parameter. In this context, we analyze the complete spectrum of variations induced by the applied substrate-RF, from deposition characteristics to dielectric and ferroelectric properties, proving its effect on all of the material attributes. In particular, we demonstrate the possibility of engineering the AlScN lattice cell to properly modify leakage, breakdown, and coercive fields, as well as polarization charge, without altering the crystallinity level, making substrate-RF an effective and efficient fabrication knob to ease the limitations the material is facing.

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“…This facilitates the creation of radio-frequency (RF) filters with significantly lower loss and higher bandwidth compared to AlN counterparts [ 2 , 3 , 4 , 5 ]. Besides the

enhancement, the recent discovery of ferroelectricity in Sc x Al 1−x N [ 6 ] has initiated extensive research efforts for the creation of configurable RF components, such as varactors, and tunable and switchable resonators and filters [ 7 , 8 , 9 , 10 , 11 , 12 ]. These components are of particular interest for emerging wireless communication systems that require multi-band adaptive operation over a wide frequency spectrum [ 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

Dual-Mode Scandium-Aluminum Nitride Lamb-Wave Resonators Using Reconfigurable Periodic Poling

Rassay

Tabrizian

2022

Micromachines

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This paper presents the use of ferroelectric behavior in scandium–aluminum nitride (ScxAl1−xN) to create dual-mode Lamb-wave resonators for the realization of intrinsically configurable radio-frequency front-end systems. An integrated array of intrinsically switchable dual-mode Lamb-wave resonators with frequencies covering the 0.45–3 GHz spectrum. The resonators are created in ferroelectric scandium–aluminum nitride (Sc0.28Al0.72N) film and rely on period poling for intrinsic configuration between Lamb modes with highly different wavelengths and frequencies. A comprehensive analytical model is presented, formulating intrinsically switchable dual-mode operation and providing closed-form derivation of electromechanical coupling (kt2) in the two resonance modes as a function of electrode dimensions and scandium content. Fabricated resonator prototypes show kt2s as high as 4.95%, when operating in the first modes over 0.45–1.6 GHz, 2.23% when operating in the second mode of operation over 0.8–3 GHz, and series quality factors (Qs) over 300–800. Benefiting from lithographical frequency tailorability and intrinsic switchability that alleviate the need for external multiplexers, and large kt2 and Q, dual-mode Sc0.28Al0.72N Lamb-wave resonators are promising candidates to realize single-chip multi-band reconfigurable spectral processors for radio-frequency front-ends of modern wireless systems.

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Intrinsically Switchable Ferroelectric Scandium Aluminum Nitride Lamb-Mode Resonators

Cited by 30 publications

References 18 publications

Influence of a Tailored Oxide Interface on the Quality Factor of Microelectromechanical Resonators

Influence of a Tailored Oxide Interface on the Quality Factor of Microelectromechanical Resonators

Effect of Substrate-RF on Sub-200 nm Al0.7Sc0.3N Thin Films

Dual-Mode Scandium-Aluminum Nitride Lamb-Wave Resonators Using Reconfigurable Periodic Poling

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