• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.156-159
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• 2002

Film Bulk Acoustic wave Resonator (FBAR) using thin piezoelectric films can be fabricated as monolithic integrated devices with compatibility to semiconductor process, leading to small size, low cost and high Q RF circuit elements with wide applications in communications area. This paper presents a MMIC compatible Suspended FBAR using surface micromachining. It is possible to make Si$_3$N$_4$/SiO$_2$/Si$_3$N$_4$membrane by using surface micromachining and its good effect is to remove the substrate silicon loss. FBAR was made on 2$\mu\textrm{m}$ multi-layered membrane using CVD process. According to our result, Fabricated film bulk acoustic wave resonator has two adventages. First, in the respect of device Process, our Process of the resonator using surface micromachining is very simple better than that of resonator using bull micromachining. Second, because of using the multiple layer, thermal expansion coefficient is compensated, so, the stress of thin film is reduced.

• Journal of Biosystems Engineering
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• v.34 no.4
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• pp.260-268
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• 2009

As a basic study to develop a high sensitive biosensor using film bulk acoustic resonator, the mathematical model for analyzing the resonance characteristics of bulk acoustic resonator with acoustic Bragg reflectors was investigated. The simulation results due to the number of acoustic Bragg reflectors with low and high acoustic impedance materials were compared with the experimental results for 1, 2.25 and 5 MHz of PZT based bulk acoustic resonators with various acoustic Bragg reflectors. At the fabricated bulk acoustic resonator with an odd number of acoustic Bragg reflectors, low and high acoustic impedance materials in sequence under the bottom electrode showed better resonance characteristics than even number of acoustic Bragg reflectors. The changes of resonance frequencies due to the increase of number of acoustic Bragg reflectors by simulation and experiment, respectively showed approximately similar tendency but some differences in input impedance between the experiment and simulation were found. The derived mathematical model for describing the resonance characteristics of the bulk acoustic resonator with acoustic Bragg reflector will be available for analyzing the design parameters for development of biosensor using bulk acoustic resonator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.838-841
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• 2003

The aim of the study is to scrutinize the relationship between the area of resonance and insertion loss by analyzing the characteristics of 2-port resonator. This was done through designing an air-gap type Film Bulk Acoustic Resonator (FBAR) by using CAD model for the application of bandpass filter of high-frequency band with piezoelectric thin film. Moreover, through the design of ladder-type BPF, we were able to observe changes in bandwidth, resonation, out-of-band rejection depending on the number and area of resonator.

• Journal of information and communication convergence engineering
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• v.4 no.3
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• pp.111-113
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• 2006

A new thin film deposition technique of piezoelectric ZnO film and its successful application for film bulk: acoustic resonator (FBAR) devices are presented. The two-step deposition used seems to be able to deposit ZnO film with a highly preferred orientation. The FBAR devices with the ZnO films show an excellent return loss of $35{\sim}50$ dB at $1.5{\sim}2$ GHz.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.95-98
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• 2000

Film bulk acoustic resonator used in microwave region can be analyzed by one-dimension Mason's model and one-dimensional numerical method, but it had several constraints to analyze effects of area variation, electrode-area variation, electrode-shape variation and spurious characteristics. To overcome these constraints film bulk acoustic resonator must be analysed by three dimensional numerical method. So, in this paper three dimensional finite element method was used to analyze several moles of resonance and was compared with the one dimension Mason's model analysis and analytic solution.

• Journal of information and communication convergence engineering
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• v.3 no.3
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• pp.137-141
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• 2005

The paper presents some methods to improve characteristics of film bulk acoustic resonator (FBAR) devices. The FBAR devices were fabricated on Bragg reflectors. Thermal treatments were done by sintering and/or annealing processes. The measurement showed a considerable improvement of return loss $(S_{11})$ and quality factor $(Q_{s/p}).$ These thermal treatment techniques seem very promising for enhancing FBAR resonance performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.94-97
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• 2003

This study uses ZnO thin film as a piezoelectric material and Pt as bottom electrode for FBAR (film bulk acoustic resonator) device. ZnO thin film and Pt were deposited by RF-magnetron sputtering method. ZnO thin film and Pt were oriented to c-axis. Top electrode Al was deposited by thermal evaporation. The membrane was formed of bulk micromachining. The FBAR was evaluated by XRD, SEM and electrical characterization. The resonant frequency was measured by HP 8753C Network Analyzer. A fabricated FBAR device exhibited a resonant frequency of 700 MHz ~ 1.5 GHz. When bottom electrode and top electrode thickness were fixed, the resonant frequency was increased as decreasing ZnO thin film thickness.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.323-329
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• 2003

In this paper, the method of material constants extraction in a thin-film bulk acoustic resonator(FBAR) using a genetic algorithm(GA) is proposed. The material constants are extracted from the input impedance of a FBAR by a GA optimizer. The characteristics of the FBAR input impedance affected by the material constants were studied to decide the fitness function for GA. As a result, the fitness was estimated by the series- and parallel -resonance frequencies and the FBAR bandwidth, as determined from the input impedance of the FBAR. A flowchart for the GA and a procedure fur the proposed extraction method are explained in detail, and the results of the material constants extraction are presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.275-278
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• 2003

The aim of the study is to scrutinize the relationship between the area of resonance and center frequency with varying thickness by analyzing the characteristics of 2-port resonator. This was done through ideal design using Leach model equivalent model modified Mason model equivalent circuit for the application of bandpass filter high-frequency band with resonator Moreover, through the design of ladder-type BPF, we were able to observe changes in bandwidth, resonation, out-of-band rejection depending on the number and area of resonator.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.8
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• pp.716-722
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• 2003

ZnO thin films were deposited on Al and Pt electrodes by an RF reactive sputtering system for the fabrication of FBAR (film bulk acoustic wave resonator), and the effect of thermal treatment temperature on their c-axis preferred orientation was investigated. SEM experiments show that columnar structure of ZnO thin films were grown with c-axis normal to electrode material, and XRD experiments show that both ZnO films were grown with (002) plane preferred orientation, but larger diffraction peak was observed with Pt electrode. The peak intensity increased with higher thermal treatment temperature, but c-axis preferred orientation was diminished. The surface roughness of Al thin film was higher than that of Pt, and these affect the surface roughness of ZnO film deposited on the electrode. Though the preferred orientation with respect to Pt(111) plane was improved with higher thermal treatment temperature, this could not improve the c-axis orientation of ZnO film.