Photoacoustic Imaging Based on Broadened Bandwidth Aluminum Nitride Piezoelectric Micromachined Ultrasound Transducers

Cai, Junxiang; Wang, Yiyun; Jiang, Daohuai; Gu, Yuandong; Lou, Liang; Gao, Fei; Wu, Tao

doi:10.1109/lsens.2023.3254593

Cited by 9 publications

(3 citation statements)

References 25 publications

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“…Since a bent diaphragm is significantly softer than rigid ceramics, its acoustic impedance is closer to that of the operating medium. Furthermore, the MEMS processing technique facilitates the creation of high-density 2D ultrasonic transducer arrays [9][10][11], thereby enhancing ultrasound sensitivity and resolution. Compared to capacitive micromachined ultrasound transducers (CMUTs), piezoelectric micromachined ultrasound transducers (PMUTs) demonstrate significant potential for ultrasound applications [12][13][14][15] attributable to their low output acoustic impedance and zero bias voltage requirement.…”

Section: Introductionmentioning

confidence: 99%

Piezoelectric Micromachined Ultrasonic Transducers with Micro-Hole Inter-Etch and Sealing Process on (111) Silicon Wafer

Wang,

Wu,

Wang

et al. 2024

Micromachines

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Piezoelectric micromachined ultrasound transducers (PMUTs) have gained significant popularity in the field of ultrasound ranging and medical imaging owing to their small size, low power consumption, and affordability. The scar-free “MIS” (micro-hole inter-etch and sealing) process, a novel bulk-silicon manufacturing technique, has been successfully developed for the fabrication of pressure sensors, flow sensors, and accelerometers. In this study, we utilize the MIS process to fabricate cavity diaphragm structures for PMUTs, resulting in the formation of a flat cavity diaphragm structure through anisotropic etching of (111) wafers in a 70 °C tetramethylammonium hydroxide (TMAH) solution. This study investigates the corrosion characteristics of the MIS technology on (111) silicon wafers, arranges micro-pores etched on bulk silicon around the desired cavity structure in a regular pattern, and takes into consideration the distance compensation for lateral corrosion, resulting in a fully connected cavity structure closely approximating an ortho-hexagonal shape. By utilizing a sputtering process to deposit metallic molybdenum as upper and lower electrodes, as well as piezoelectric materials above the cavity structure, we have successfully fabricated aluminum nitride (AlN) piezoelectric ultrasonic transducer arrays of various sizes and structures. The final hexagonal PMUT cells of various sizes that were fabricated achieved a maximum quality factor (Q) of 251 and a displacement sensitivity of 18.49 nm/V across a range of resonant frequencies from 6.28 MHz to 11.99 MHz. This fabrication design facilitates the achievement of IC-compatible and cost-effective mass production of PMUT array devices with high resonance frequencies.

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Section: Introductionmentioning

confidence: 99%

Piezoelectric Micromachined Ultrasonic Transducers with Micro-Hole Inter-Etch and Sealing Process on (111) Silicon Wafer

Wang,

Wu,

Wang

et al. 2024

Micromachines

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“…In the last decade, researchers have started conducting comprehensive research on PMUT. PMUT has been widely used in fingerprint identification, gesture recognition, medical imaging, flow meters, distance measurement, humidity sensors, and other applications [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

“…Currently, various piezoelectric materials such as lead zirconate titanate (PZT), barium calcium zirconate titanate ceramics (BCZT), and aluminum nitride film (AIN) have been widely applied [ 8 , 10 , 11 ]. However, the preparation of PZT requires a high temperature environment (>480 °C) due to the lead content in the process, which is gradually being replaced in today’s environmentally conscious context.…”

Section: Introductionmentioning

confidence: 99%

Stepped-Tube Backside Cavity Piezoelectric Ultrasound Transducer Based on Sc0.2AI0.8N Thin Films

Li,

Lyu,

Safari

et al. 2023

Micromachines

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This paper presents a novel piezoelectric micromachined ultrasonic transducer (PMUT) with theoretical simulation, fabrication, and testing. Conventional methods using a PCB or an external horn to adjust the PMUT acoustic field angle are limited by the need for transducer size. To address this limitation, the stepped-tube (expanded tube) backside cavity PMUT has been proposed. The stepped-tube PMUT and the tube PMUT devices have the same membrane structure, and the acoustic impedance matching of the PMUT is optimized by modifying the boundary conditions of the back cavity structure. The acoustic comparison experiments show that the average output sound pressure of the stepped-tube backside cavity PMUT has increased by 17%, the half-power-beam-width (θ-3db) has been reduced from 55° to 30° with a reduction of 45%, and the side lobe level signal is reduced from 147 mV to 66 mV. In addition, this work is fabricated on an eight-inch wafer. The process is compatible with standard complementary metal oxide semiconductor (CMOS), conditions are stable, and the cost is controllable, plus it facilitates the batch process. These conclusions suggest that the stepped-tube backside cavity PMUT will bring new, effective, and reliable solutions to ranging applications.

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The effects of three profiles on the mechanical properties and grain size of self-piercing riveting joints using ultrasonic welding

Zixin,

Zhao,

Abbas

et al. 2023

Int J Adv Manuf Technol

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Photoacoustic Imaging Based on Broadened Bandwidth Aluminum Nitride Piezoelectric Micromachined Ultrasound Transducers

Cited by 9 publications

References 25 publications

Piezoelectric Micromachined Ultrasonic Transducers with Micro-Hole Inter-Etch and Sealing Process on (111) Silicon Wafer

Piezoelectric Micromachined Ultrasonic Transducers with Micro-Hole Inter-Etch and Sealing Process on (111) Silicon Wafer

Stepped-Tube Backside Cavity Piezoelectric Ultrasound Transducer Based on Sc0.2AI0.8N Thin Films

The effects of three profiles on the mechanical properties and grain size of self-piercing riveting joints using ultrasonic welding

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