Design and Optimization of SHF Composite FBAR Resonators

Pillai, Gayathri; Zope, Anurag A.; Tsai, J. M.; Li, Sheng-Shian

doi:10.1109/tuffc.2017.2759811

“…material and the acoustic mode used [7][8][9][10][11][12][13]. To cater to some of the highly difficult bands featuring very wide fractional bandwidth more than 10% [14], researchers have been putting efforts to develop resonators with large electromechanical coupling and high-quality factor (Q) [15].…”

Section: Introductionmentioning

confidence: 99%

Thin-film lithium niobate-on-insulator (LNOI) shear horizontal surface acoustic wave resonators

Hsu

¹

,

Tseng

²

,

Li

³

2021

J. Micromech. Microeng.

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This work investigates the design methodology to obtain large electromechanical coupling factor ( k eff 2 ) and high quality factor (Q) of shear-horizontal surface acoustic wave (SH-SAW) resonators based on the thin-film lithium niobate-on-insulator (LNOI) technology. The guided SH wave can be excited through interdigital transducers and propagate at the very surface of the material stackings. Such a guided SH wave in LN/SiO2 double layer structure is expected to offer high k eff 2 by confining the elastic strain energy in the piezoelectric thin film. To capture the optimum design window for high-performance LNOI SH-SAW devices, the impact of electrode material and its thickness on the k eff 2 dispersive characteristics are intensively investigated by finite element method (FEM). In this study, various one-port resonators with wavelengths from 2.8 μm to 8 μm were fabricated on a LNOI wafer with LN and SiO2 thickness of 0.7 and 2 μm, respectively. The 100 nm thick gold film was chosen as the electrode of the devices, which demonstrate a similar k eff 2 dispersive behavior to the FEM simulation with small discrepancy. Among the measurement results over several tested samples, a high- k eff 2 of 25.5% and Q of 960 was recorded at a resonance frequency of 581 MHz (FOM = k eff 2 ⋅ Q = 245), revealing great potential for the application of wide-band frequency selection in telecommunications.

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“…The stimulating RF power was set to −5 dbm during the measurement. To extract the device performance for both FBAR and LWR devices, the parasitic effect between signal and ground is removed by on-chip deembedding structures [39].…”

Section: Measurement Resultsmentioning

confidence: 99%

An 8-inch commercial aluminum nitride MEMS platform for the co-existence of Lamb wave and film bulk acoustic wave resonators

Hsu

¹

,

Tung

²

,

Huang

³

et al. 2023

J. Micromech. Microeng.

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This work investigates a co-design approach for fundamental symmetric Lamb wave (S0) resonators (LWR) and film bulk acoustic wave resonators (FBAR) in a commercial 8-inch aluminum nitride (AlN) microelectromechanical system (MEMS) platform to enable multi-band operation. The platform utilizes surface micromachining to define local release cavities, providing an undercut-free solution for acoustic resonators to achieve a high quality factor (Q). However, being based on a standardized platform initially tailored for FBAR devices, many design considerations and trade-offs need to be investigated for the co-existence between LWR and FBAR design. Hence, to capture the optimal design window for S0 LWRs while analyzing its performance impact on existing FBARs, the electrode configuration and its thickness are thoroughly investigated by the finite element method (FEM). In this work, a 2.2 GHz FBAR, a 700 MHz S0 LWR, and a 2.19 GHz S0 Lamé LWR are demonstrated for performance evaluation across different types of devices in this platform. The measurement results revealed a baseline performance for the FBAR device with an electromechanical coupling factor (kt 2) of 6.73% and Q of 3,017 at 2.2 GHz, resulting in a high figure-of-merit (FoM = kt 2∙Q) over 200. In comparison, the 700 MHz S0 LWR exhibits a high Q of 2,532 as well and a kt 2 of 1.1% (FoM = 27.8), while the 2.19 GHz S0 Lamé LWR also exhibits a high Q of 1,752 and a kt 2 of 2.44% (FoM = 42.7), respectively. These performance indexes are all comparable with the current state-of-the-art, revealing the excellent potential of this AlN MEMS platform being implemented for future LWR development design or even mass production.

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“…However, challenges constrain the operating frequency to around 2.5 GHz [112]. Thus, based on the literature, it is evident that AlN-based devices dominate high-band applications [113]. Additionally, with Sc doping, the piezoelectric strain coefficient d33 of the AlScN thin film can increase significantly, as discussed earlier; thus, the AlScN piezoelectric thin film shows a greater advantage for emerging FBARs [114], [115], [116], [117].…”

Section: B Telecommunication Applicationsmentioning

confidence: 97%

A Review of the Recent Applications of Aluminum Nitride-Based Piezoelectric Devices

Haider

¹

,

Shah

²

,

Lee

³

et al. 2023

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Piezoelectric materials have attracted considerable attention over the last two decades because many technologies utilize their core properties of piezoelectric materials. Previous applications consisted of bulk structures; however, a shift towards better performance and a more simplified and compatible fabrication method are required. Aluminum nitride (AlN) is a material that fits these criteria; it has a non-centrosymmetric crystal structure with a polarized c-axis and exhibits piezoelectric properties. Furthermore, it has an added benefit as the fabrication process of AIN is compatible with complementary metal-oxide semiconductor technology. This has led to a rapid increase in the adoption and interest in AlNbased devices. In this review, the crystal structure of AlN and its piezoelectric properties are compared with those of aluminum scandium nitride. Subsequently, functional devices such as consumer-based devices, telecommunication-based devices, industrial-related applications, and medical applications are presented. Finally, a summary and discussion of the future AlN research are presented.

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Design and Optimization of SHF Composite FBAR Resonators

Cited by 28 publications

References 16 publications

Thin-film lithium niobate-on-insulator (LNOI) shear horizontal surface acoustic wave resonators

Thin-film lithium niobate-on-insulator (LNOI) shear horizontal surface acoustic wave resonators

An 8-inch commercial aluminum nitride MEMS platform for the co-existence of Lamb wave and film bulk acoustic wave resonators

A Review of the Recent Applications of Aluminum Nitride-Based Piezoelectric Devices

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