Film bulk acoustic resonators integrated on arbitrary substrates using a polymer support layer

Chen, Guohao; Zhao, Xinbao; Wang, Xiaozhi; Jin, Hao; Li, Shijian; Dong, Shurong; Flewitt, Andrew J.; Milne, W. I.; Luo, Jikui

doi:10.1038/srep09510

Cited by 50 publications

(29 citation statements)

References 45 publications

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“…Recently, a new type of FBAR structure has been developed by utilizing a polymer layer with very low acoustic impedance as the acoustic reflector, and the FBARs can be made on any solid substrate such as glass and copper film even with uneven surfaces (Chen et al 2015a). There are two basic resonant modes operated in FBARs: (1) longitudinal mode which is a longitudinal acoustic standing wave generated between two surfaces of the electrodes when an alternating voltage is applied (Fu et al 2010;Lin et al 2011;Zhang et al 2010); (2) thickness shear mode which is a shear wave generated between two electrodes with applied alternating electric field.…”

Section: Theory Of Fbarsmentioning

confidence: 99%

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Film bulk acoustic resonators (FBARs) as biosensors: A review

Zhang

Luo

Flewitt

et al. 2018

Biosensors and Bioelectronics

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Biosensors play important roles in different applications such as medical diagnostics, environmental monitoring, food safety, and the study of biomolecular interactions. Highly sensitive, label-free and disposable biosensors are particularly desired for many clinical applications. In the past decade, film bulk acoustic resonators (FBARs) have been developed as biosensors because of their high resonant frequency and small base mass (hence greater sensitivity), lower cost, label-free capability and small size. This paper reviews the piezoelectric materials used for FBARs, the optimisation of device structures, and their applications as biosensors in a wide range of biological applications such as the detection of antigens, DNAs and small biomolecules. Their integration with microfluidic devices and high-throughput detection are also discussed.

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Section: Theory Of Fbarsmentioning

confidence: 99%

“…A maximum fr shift of more than 20 MHz can be achieved. Furthermore, Chen et al(Chen et al 2015a) recently reported that FBAR devices can be integrated on arbitrary substrates using a polymer support layer, making it possible for integrating FBAR sensors onto a variety of substrates, therefore enabling wider applications.…”

mentioning

confidence: 99%

Film bulk acoustic resonators (FBARs) as biosensors: A review

Zhang

Luo

Flewitt

et al. 2018

Biosensors and Bioelectronics

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“…For example, FBAR devices are very promising for sensing and monitoring pressure [2], mass [3], ultraviolet (UV) light [4], and biomolecules [5] owing to their small size, high sensitivity, and low power consumption. Over the past several decades, a number of FBAR studies have focused on the development of novel materials (piezoelectric layer, substrate membrane) for the fabrication of high-performance FBARs [6], and flexible polymer substrates such as polyethylene terephthalate (PET) [7] and polyimide (PI) [8] have been successfully used in the fabrication of flexible FBAR devices. However, commonly used piezoelectric materials for FBAR devices (materials such as zinc oxide (ZnO), aluminum nitride (AlN), and lead zirconate titanate (PZT)) are inorganic, and are either brittle or not biocompatible.…”

Section: Introductionmentioning

confidence: 99%

A Flexible Film Bulk Acoustic Resonator Based on β-Phase Polyvinylidene Fluoride Polymer

Jin

Dong

et al. 2020

Sensors

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This paper reports a novel flexible film bulk acoustic resonator (FBAR) based on β-phase polyvinylidene fluoride (PVDF) piezoelectric polymer. The proposed device was simulated and evaluated; then, a low-temperature photolithography process with a double exposure method was developed to pattern the electrodes for the device, which enabled the device to retain the piezoelectric properties of the β-phase PVDF film. Results showed that the β-phase PVDF FBARs had a resonant frequency round 9.212 MHz with a high electromechanical coupling coefficient (k 2 ) of 12.76% ± 0.56%. The device performed well over a wide bending-strain range up to 2400 µε owing to its excellent flexibility. It showed good stability as a strain sensor with a sensitivity of 80 Hz/µε, and no visible deterioration was observed after cyclic bending tests. The PVDF FBAR also exhibited an exceptionally large temperature coefficient of frequency (TCF) of −4630 ppm/K, two orders of magnitude larger than those of other FBARs based on common inorganic piezoelectric materials, extraordinarily high sensitivity for temperature sensing. All results showed that β-phase PVDF FBARs have the potential to expand the application scope for future flexible electronics.with high-cost equipment for the deposit of these highly crystalline films can limit their widespread application and commercialization.Polyvinylidine difluoride (PVDF), a well-known high-performance piezoelectric polymer, could be a strong candidate as a new flexible FBAR material due to its remarkable inherent flexibility, lightness, and robustness, as well as its high piezoelectric response and low acoustic impedance, similar to those of biological tissue. Since the discovery of the piezoelectric activity of the PVDF material by Kawai in 1969 [9], PVDF-based piezoelectric polymer has been used in a wide range of actuators and sensors, such as underwater acoustic transducers [10], ultrasonic inspection sensors [11], acceleration sensors [12], surface acoustic-wave devices [13], pressure sensors [14], and energy harvesters [15]. In addition, it has been utilized in medical and biological applications such as artificial muscles and organs [16], medical imaging [17], and blood-flow monitors [18]. However, a PVDF polymer cannot be processed by a standard lithography process, limiting its application in MEMS devices and electronics.In this paper, we report on the feasibility of using a β-phase PVDF polymer for the development of FBARs. In this research, an FBAR device was designed with a 100 µm thick β-phase PVDF film sandwiched between two metal electrodes with a simulated resonant frequency of 9.418 MHz. A facile and reliable fabrication method was developed to successfully fabricate β-phase PVDF FBAR, which is compatible with the standard lithography process. The stability of the crystalline phase and the piezoelectricity of the β-phase PVDF film after the fabrication process were verified by X-ray diffraction (XRD) and piezoelectric coefficient d 33 measurement, respectively. The performance of the β...

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“…Hospitals, for example, reduced the rates of hospital-acquired drugresistant infections by 25% using ultraviolet disinfection (via mercury lamps (254 nm)), as reported by various clinical trials [19,20]. Furthermore, the AlN or AlGaN epi-transfer 2 and heterogeneous integration technology can be employed to enhance the performance of photodiodes (PDs) [21], high electron mobility transistors (HEMTs) [22,23], bulk acoustic resonators (BARs) [24][25][26], and high-aspect-ratio SiC microstructures and devices [27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Fabrication technology for high light-extraction ultraviolet thin-film flip-chip (UV TFFC) LEDs grown on SiC

SaifAddin¹,

Almogbel

Zollner³

et al. 2019

Semicond. Sci. Technol.

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The light output of deep ultraviolet (UV-C) AlGaN light-emitting diodes (LEDs) is limited due to their poor light extraction efficiency (LEE). To improve the LEE of AlGaN LEDs, we developed a fabrication technology to process AlGaN LEDs grown on SiC into thinfilm flip-chip LEDs (TFFC LEDs) with high LEE. This process transfers the AlGaN LED epi onto a new substrate by wafer-to-wafer bonding, and by removing the absorbing SiC substrate with a highly selective SF6 plasma etch that stops at the AlN buffer layer. We optimized the inductively coupled plasma (ICP) SF6 etch parameters to develop a substrateremoval process with high reliability and precise epitaxial control, without creating micromasking defects or degrading the health of the plasma etching system. The SiC etch rate by SF6 plasma was ~46 µm/hr at a high RF bias (400 W), and ~7 µm/hr at a low RF bias (49 W) with very high etch selectivity between SiC and AlN. The high SF6 etch selectivity between SiC and AlN was essential for removing the SiC substrate and exposing a pristine, smooth AlN surface. We demonstrated the epi-transfer process by fabricating high light extraction TFFC LEDs from AlGaN LEDs grown on SiC. To further enhance the light extraction, the exposed N-face AlN was anisotropically etched in dilute KOH. The LEE of the AlGaN LED improved by ~3X after KOH roughening at room temperature. This AlGaN TFFC LED process establishes a viable path to high external quantum efficiency (EQE) and power conversion efficiency (PCE) UV-C LEDs.

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Film bulk acoustic resonators integrated on arbitrary substrates using a polymer support layer

Cited by 50 publications

References 45 publications

Film bulk acoustic resonators (FBARs) as biosensors: A review

Film bulk acoustic resonators (FBARs) as biosensors: A review

A Flexible Film Bulk Acoustic Resonator Based on β-Phase Polyvinylidene Fluoride Polymer

Fabrication technology for high light-extraction ultraviolet thin-film flip-chip (UV TFFC) LEDs grown on SiC

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