Effects of Coating Layers on Properties of LGS SAW Resonators

Ling LI, Bin PENG, Heng YU
2018 DEStech Transactions on Engineering and Technology Research  
Surface acoustic wave (SAW) sensors are very sensitive to the external environment, when the devices are working in a complex environment, SAW sensors must be protected. This paper reports the study of SAW resonators based on coating layer/LGS substrate package-less structure. AlN, Al 2 O 3 and Si 3 N 4 thin films were selected as protective coating layer materials. The SAW resonators with different thicknesses of coating layers were simulated and fabricated. The device performances in terms of
more » ... rmances in terms of SAW velocity, quality factor (Q factor) and electromechanical coupling coefficient (K 2 ) were determined from the measured S 11 parameters. The SAW velocity is 2500 m/s in the SAW resonators without any coating layer and with the increase of the thickness of coating layers, the SAW velocity increases. K 2 and Q factor decrease as the thickness of Al 2 O 3 and Si 3 N 4 coating layers increasing. For AlN coating layer, K 2 and Q factor of the SAW resonators with 0.2 µm-thick AlN coating layer are greater than the SAW resonators without any coating layer. When the thickness is more than 0.2 µm, K 2 and Q factor decline as other two kinds of coating layers devices.
doi:10.12783/dtetr/apop2017/18772 fatcat:uo7oboeenfcdtc7k4e6sriop5y