A ZnO Driven Silicon Cantilever for Nanoscale Actuation

A micro silicon cantilever actuated by ZnO thin film was designed, fabricated and characterized. The ZnO thin film was deposited by RF sputtering at room temperature. The transverse piezoelectric constant d31 was found to be-4.66 pC/N. Time and frequency responses of the cantilever actuator were investigated by means of a laser Doppler vibrometer. The actuator has a sensitivity of 12 nm/V at 15 kHz. Its 1st bending resonance was observed at 53 kHz. The bandwidth was found to be 27 kHz with damping of 0.35%. The cantilever demonstrated capability of high frequency actuation on a nanometer level.

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Modeling, Fabrication and Characterization of Piezoelectric ZnO-Based Micro-Sensors and Micro-Actuators

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.444-445.1636 ◽

2013 ◽

Vol 444-445 ◽

pp. 1636-1643 ◽

Cited By ~ 1

Author(s):

Yan Hui Yuan ◽

He Jun Du ◽

Xin Xia ◽

Yoke Rung Wong

Keyword(s):

Thin Film ◽

Room Temperature ◽

Laser Doppler Vibrometer ◽

Zno Thin Film ◽

Design Specifications ◽

Piezoelectric Cantilever ◽

Fabrication And Characterization ◽

Micro Cantilever ◽

Microfabrication Techniques

In this study, capabilities of zinc oxide (ZnO) thin films in sensing and actuating were investigated using micromachined micro-cantilevers. A heterogeneous piezoelectric cantilever was modeled to study its response under voltage and/or external mechanical loading. A ZnO thin-film micro-cantilever was designed based on the developed theoretical model. Simulated tip deflections of the micro-cantilever were on the nanometer level under typical electrical and mechanical input. A prototype was fabricated with microfabrication techniques. The ZnO thin film was sputtered at room temperature and demonstrated good compatibility with common chemicals and processes in micromachining. The fabricated micro-cantilever was experimentally characterized for its actuating and sensing performance. For actuator characterization tip deflection of the micro-cantilever was detected by a laser Doppler vibrometer, while for sensor characterization the micro-cantilever was calibrated as an acceleration sensor using a reference accelerometer. The experimental resonant frequency, actuating and sensing sensitivities agreed well the design specifications.

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Effects of Thermal Annealing on the Characteristics of High Frequency FBAR Devices

Coatings ◽

10.3390/coatings11040397 ◽

2021 ◽

Vol 11 (4) ◽

pp. 397

Author(s):

Yu-Chen Chang ◽

Ying-Chung Chen ◽

Bing-Rui Li ◽

Wei-Che Shih ◽

Jyun-Min Lin ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Thermal Annealing ◽

Electromechanical Coupling ◽

Zno Thin Films ◽

Electromechanical Coupling Coefficient ◽

Back Side ◽

Zno Thin Film ◽

Frequency Responses ◽

Sputtering System

In this study, piezoelectric zinc oxide (ZnO) thin film was deposited on the Pt/Ti/SiNx/Si substrate to construct the FBAR device. The Pt/Ti multilayers were deposited on SiNx/Si as the bottom electrode and the Al thin film was deposited on the ZnO piezoelectric layer as the top electrode by a DC sputtering system. The ZnO thin film was deposited onto the Pt thin film by a radio frequency (RF) magnetron sputtering system. The cavity on back side for acoustic reflection of the FBAR device was achieved by KOH solution and reactive ion etching (RIE) processes. The crystalline structures and surface morphologies of the films were analyzed by X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The optimized as-deposited ZnO thin films with preferred (002)-orientation were obtained under the sputtering power of 80 W and sputtering pressure of 20 mTorr. The crystalline characteristics of ZnO thin films and the frequency responses of the FBAR devices can be improved by using the rapid thermal annealing (RTA) process. The optimized annealing temperature and annealing time are 400 °C and 10 min, respectively. Finally, the FBAR devices with structure of Al/ZnO/Pt/Ti/SiNx/Si were fabricated. The frequency responses showed that the return loss of the FBAR device with RTA annealing was improved from −24.07 to −34.66 dB, and the electromechanical coupling coefficient (kt2) was improved from 1.73% to 3.02% with the resonance frequency of around 3.4 GHz.

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