c-Axis-tilted ScAlN films grown on silicon substrates for surface acoustic wave devices

ScAlN films are currently being investigated for their potential use in surface acoustic wave (SAW) devices for next-generation mobile networks because of their high piezoelectricity. This paper describes the numerical simulation of SAW propagation in c-axis-tilted ScAlN films on silicon substrates and a fabrication technique for preparing c-axis-tilted ScAlN films on silicon substrates. The electromechanical coupling coefficient K 2 of SAW propagating in the ScAlN film/silicon substrate increased due to the c-axis tilt angle. The maximum K 2 value is approximately 3.90%. This value is 2.6 times the maximum K 2 value of the c-axis-oriented ScAlN film/silicon substrate structure. The c-axis-tilted ScAlN films with an Sc concentration of 40% were prepared on a silicon substrate via RF magnetron sputtering based on the self-shadowing effect, and the maximum c-axis tilt angle was 57.4°. These results indicate that this device structure has the potential for SAW device applications with well-established micromachining technology derived from silicon substrates.