The Characterization of Surface Acoustic Wave Devices Based on AlN-Metal Structures

• Published in: Sensors (Basel, Switzerland) Vol. 16; no. 4; p. 526
• Main Authors: Shu, Lin, Peng, Bin, Li, Chuan, Gong, Dongdong, Yang, Zhengbing, Liu, Xingzhao, Zhang, Wanli
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 12.04.2016; MDPI
• Subjects: Adhesives; AlN film; Aluminum nitride; Design; Devices; Electrodes; Film thickness; Geometry; layered structure; Propagation; Sensors; Simulation; surface acoustic wave; Surface acoustic wave devices; Surface acoustic waves; TC4; Thickness; Titanium alloys; Velocity; Zinc oxides; China; AlN film; TC4; surface acoustic wave; simulation; layered structure
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s16040526

We report in this paper on the study of surface acoustic wave (SAW) resonators based on an AlN/titanium alloy (TC4) structure. The AlN/TC4 structure with different thicknesses of AlN films was simulated, and the acoustic propagating modes were discussed. Based on the simulation results, interdigital transducers with a periodic length of 24 μm were patterned by lift-off photolithography techniques on the AlN films/TC4 structure, while the AlN film thickness was in the range 1.5-3.5 μm. The device performances in terms of quality factor (Q-factor) and electromechanical coupling coefficient (k²) were determined from the measure S11 parameters. The Q-factor and k² were strongly dependent not only on the normalized AlN film thickness but also on the full-width at half-maximum (FWHM) of AlN (002) peak. The dispersion curve of the SAW phase velocity was analyzed, and the experimental results showed a good agreement with simulations. The temperature behaviors of the devices were also presented and discussed. The prepared SAW resonators based on AlN/TC4 structure have potential applications in integrated micromechanical sensing systems.