In this study, ZnO film bulk acoustic resonators (FBARs) are proposed to fabricate the mass sensor of high sensitivity. The acoustic cavity is achieved by potassium hydroxide (KOH) etching. The FBAR structures are made of highly C-axis-oriented piezoelectric ZnO thin films using the technique of two-step deposition method. The titanium (Ti) seeding layer, platinum (Pt) bottom electrode, and aluminum (Al) top electrode were deposited by DC sputtering system using a dual gun. Finally, The remnants of silicon and silicon nitride (SiNx) are removed by reactive ion etching (RIE) etching. Furthermore, the two resonant frequencies of longitudinal mode and shear mode had been obtained.
From the experimental results of loading effect with titanium and molybdenum, the mass sensitivity of the longitudinal mode and the shear mode are about 3200 Hz cm /ng and 1100 Hz cm /ng respectively, which are larger than those of quartz resonator or other reports. The measurement system was composed of a thermoelectric cooling module to investigate the temperature coefficient of frequency (TCF) of the mass sensor, which is about -70.67 ppm/.
Bisides, the positive TCF material, silicon dioxode (SiO2) is deposited on ZnO thin films for the purpose of improving the TCF of FBAR devices. For SiO2/ZnO FBAR devices, the SiO2 reveal the compensation of TCF.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0727107-162155 |
| Date | 27 July 2007 |
| Creators | Chang, Wei-tsai |
| Contributors | Cheng-Fu Yang, Chien-Chuan Cheng, Ying-Chung Chen, Mau-Phon Houng, Rurng-Sheng Guo |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0727107-162155 |
| Rights | not_available, Copyright information available at source archive |
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