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The fabrication of thin-film bulk acoustic resonator

In this study, the FBAR devices fabrication was used by back-etched type. The titanium (Ti) seeding layer and platinum (Pt) bottom electrode were deposited by DC sputtering system using a dual gun. To improve the platinum (Pt) adhesion, a seeding layer titanium (Ti) is used. The piezoelectric zinc oxide (ZnO) thin films were deposited by RF reactive
magnetron sputtering. By increase the substrate temperature and annealing treatment in order to improve the ZnO thin films quality. The FBAR device was fabricated with different top electrode of Al, Mo and
Pt that was compared different frequency response characteristic. When ZnO thin films are deposited on Pt/Ti/SiNx/Si substrate by RF reactive magnetron sputtering, due to the lattice mismatch between the
Zno thin film and Pt electrode and rapid deposition rate, the ZnO films have high Zn interstitials and O vacancy, which introduce the stress in ZnO films. By thermal annealing treatment the stress could be relaxed and the defects in ZnO films could be suppressed. We used the ZnO films at the different annealing temperature to fabricated the FBAR device, and also discussed the resonant characteristics of the FBAR device with the stress in the ZnO films.
Top electrode of Al is suitable for using as electrode materials for FBAR device. The Al top electrode revealed the best frequency response
characteristic among the various top electrodes in this research. Postdeposition annealing at 400¢Jmakes ZnO films more suitable for high Q FBAR device, it makes ZnO films with stronger c-axis (002)
orientation, denser structure, smoother surface and relieved stress. The resonant frequency, the effective electromechanical coupling coefficient ( k eff ) and the quality factor (Q) were about 2.21GHz, 2.88% and 2659, respectively.

Identiferoai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0814107-170036
Date14 August 2007
CreatorsDeng, Chih-Wen
ContributorsWei-Hsing Tuan, Ying-Chung Chen, Chen-Chia Chou, Chien-Chuan Cheng, Jow-Lay Hung
PublisherNSYSU
Source SetsNSYSU Electronic Thesis and Dissertation Archive
LanguageCholon
Detected LanguageEnglish
Typetext
Formatapplication/pdf
Sourcehttp://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0814107-170036
Rightsnot_available, Copyright information available at source archive

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