The Liquid Sensor Using Thin Film Bulk Acoustic Resonator with C-Axis Tilted AlN Films

Dual-mode thin film bulk acoustic resonator (TFBAR) devices are fabricated with c-axis tilted AlN films. To fabricate dual-mode TFBAR devices, the off-axis RF magnetron sputtering method for the growth of tilted piezoelectric AlN thin films is adopted. In this report, the AlN thin films are deposited with tilting angles of 15° and 23°. The frequency response of the TFBAR device with 23° tilted AlN thin film is measured to reveal its ability to provide dual-mode resonance. The sensitivities of the longitudinal and shear modes to mass loading are calculated to be 2295 Hz cm2/ng and 1363 Hz cm2/ng with the mechanical quality factors of 480 and 287, respectively. The sensitivities of the longitudinal and shear modes are calculated to be 0 and 15 Hz cm2/μg for liquid loading.

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Investigation of Liquid Sensor Using a Dual-Mode Thin Film Bulk Acoustic Resonator (FBAR) Combined with Au/Cr Layers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.201-203.700 ◽

2011 ◽

Vol 201-203 ◽

pp. 700-703

Author(s):

Wei Tsai Chang ◽

Ying Chung Chen ◽

Re Ching Lin ◽

Kuo Sheng Kao ◽

Jia Ming Jiang ◽

...

Keyword(s):

Thin Film ◽

High Sensitivity ◽

Rf Magnetron Sputtering ◽

Acoustic Resonator ◽

Zno Thin Film ◽

Dual Mode ◽

Resonant Frequencies ◽

Film Bulk Acoustic Resonator ◽

Shear Modes ◽

Film Bulk

This paper reports a dual-mode film bulk acoustic resonator (FBAR) device combined with Au/Cr layer to construct a liquid sensor. In order to obtain a liquid sensor with high sensitivity, the dual-mode FBAR with piezoelectric layer of ZnO thin film has been investigated. The dual-mode characteristics of FBAR appeared by off-axis deposition of ZnO thin film with the RF magnetron sputtering. The top and bottom electrodes consisted of a titanium (Ti) and a platinum (Pt) layers were deposited by dual-gun DC sputtering system. Owing to the chemical stability, the Pt layer is not only a perfect bottom electrode but also an etching stop layer. The gold layer (Au) is adopted for the formation of sensory area. In order to improve the adhesion between the Au layer and the Pt layer, a chromium (Cr) layer was deposited onto the backside cavity of the FBAR device before the Au layer was deposited by a DC sputter. The Au/Cr layer is used as the binding layer with analytes of DI water because of its hydrophile. The frequency response is measured using an HP8720 network analyzer and a CASCADE probe station. The resonant frequencies of longitude and shear modes in air appear at 2262.5 MHz and 1012.5MHz, whereas the resonant frequencies of longitude and shear modes in DI water are 2062.5 MHz and 955MHz, respectively.

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Design and Fabrication of Wafer Level Dual-Band Thin Film Bulk Acoustic Resonator Filters

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.308-310.201 ◽

2011 ◽

Vol 308-310 ◽

pp. 201-208

Author(s):

Wei Tsai Chang ◽

Ying Chung Chen ◽

Chien Chuan Cheng ◽

Kuo Sheng Kao ◽

Re Ching Lin ◽

...

Keyword(s):

Thin Films ◽

Rf Magnetron Sputtering ◽

Acoustic Resonator ◽

Dual Band ◽

Zno Thin Films ◽

Pass Band ◽

Wafer Level ◽

Dual Mode ◽

Film Bulk Acoustic Resonator ◽

Film Bulk

This paper describes the design and fabrication of dual-mode film bulk acoustic resonator (TFBAR) devices to construct wafer level dual-band T-ladder type filters. The T-ladder type filters is selected in this study for its high quality and simple fabrication processes. The c-axis-tilted ZnO thin films to obtain dual-mode TFBAR devices have been investigated. The characteristics of dual-mode TFBAR devices appeared by off-axis deposition of ZnO thin films with the RF magnetron sputtering. The top and bottom electrodes consisted of titanium (Ti) and platinum (Pt) layers are deposited by dual-gun DC sputtering system. The pass-band width of filters is controlled by the mass loading on the dual-mode. The frequency response is measured using an HP8720 network analyzer and a CASCADE probe station.

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Characteristics of ZnO Thin Film by Atomic Layer Deposition for Film Bulk Acoustic Resonator

Materials Science Forum ◽

10.4028/www.scientific.net/msf.449-452.977 ◽

2004 ◽

Vol 449-452 ◽

pp. 977-980 ◽

Cited By ~ 1

Author(s):

S.G. Kim ◽

Seung Boo Jung ◽

Ji Hun Oh ◽

H.J. Kim ◽

Yong Hyeon Shin

Keyword(s):

Thin Films ◽

Atomic Layer Deposition ◽

Magnetron Sputtering ◽

Atomic Layer ◽

Rf Magnetron Sputtering ◽

Acoustic Resonator ◽

Film Deposition ◽

Layer Deposition ◽

Film Bulk Acoustic Resonator ◽

Film Bulk

Polycrystalline ZnO thin films were for the first time deposited on SiO2/Si (100) substrate using 2-step deposition; atomic layer deposition (ALD) and RF magnetron sputtering, for Film Bulk Acoustic Resonator (FBAR) applications. The film deposition performed in this study was composed of following two procedures; the 1st deposition was using ALD method and 2nd deposition was using RF magnetron sputtering. The ZnO buffer layer ALD films were deposited using alternating diethylzinc (DEZn)/H2O exposures and ultrahigh purity argon gas for purging. Exposure time of 1 sec and purge time of 23 sec yielded an ALD cycle time. Two-step deposited ZnO films revealed stronger c-axis preferred-orientation than one-step deposited. Therefore, this method could be applied to the FBAR applications, since FBAR devices require high quality of thin films.

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