High Coupling Coefficient Resonance Mode in Al0.68Sc0.32N Surface Acoustic Wave Resonator with AlN Buffer Layer on a Silicon Substrate

We report on a resonance mode with high electro-mechanical coupling coefficient (kt 2) in an Aluminum Scandium Nitride (AlScN) Surface Acoustic Wave (SAW) resonator with an Aluminum Nitride (AlN) buffer layer on a silicon substrate. We demonstrate the influence of electrode material, electrode thickness, AlScN thickness, and device orientation on the kt 2. We utilize the optimized parameters from this study to realize SAW devices in a CMOS compatible fabrication process and measured a kt 2 as high as 4.78%, which is a high value for AlScN SAW devices reported on low cost single crystal silicon substrates.