| Summary: | 碩士 === 國立中山大學 === 電機工程學系研究所 === 98 === Acoustic micro-sensors have already been applied in mass sensing including surface acoustic wave (SAW), flexural plate wave (FPW), thickness shear mode (TSM) and shear horizontal acoustic plate mode (SH-APM). The FPW micro-sensor is very suitable for liquid-sensing and bio-sensing applications due to the high mass-sensitivity and low phase-velocity in liquid. However, the conventional FPW micro-sensors presented a high insertion-loss (IL) and a low signal-to-noise ratio so it is difficult to combine with IC into a micro-system.
To overcome these drawbacks, this study combine the Microelectromechanical System (MEMS) technology and the high C-axis orientation ZnO piezoelectric thin-film to develop a low insertion loss, low operation frequency, and high electromechanical coupling coefficient FPW device. In this study, a high C-axis orientation ZnO piezoelectric thin-film with a 20944A.U. X-Ray diffraction intensity at 34.200 degree and a 0.573 degree full width at half maximum (FWHM) was deposited by a commercial magnetic radio-frequency (RF) sputter system. The total processes of the FPW micro-sensor included five photolithography and seven thin-film depositions. In this study a low operation frequency (0.1MHz), low insertion loss (11dB to 14dB) and high electromechanical coupling coefficient (11%) FPW sensor was developed and fabricated.
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