C-axis parallel oriented A1N film resonator fabricated by ion-beam assisted RF magnetron sputtering

c-axis parallel oriented AlN films excite only pure shear wave. These films are suitable for thickness shear mode film resonators and SH-SAW devices. However, c-axis in the wurzite film such as ZnO and AlN tends to grow normal to the substrate. We previously found that c-axis parallel orientation is induced by ion-beam irradiation during deposition in ZnO films. In this study, we investigated the orientation control of AlN films by using ion-beam assisted RF magnetron sputtering. c-axis parallel oriented AlN films were obtained in the sample deposited under 3 kV accelerated ion beam irradiation The direction of c-axis corresponded to the ion beam direction. c-axis parallel AlN film SMR with asymmetric Bragg reflector was then prepared. Pure shear mode was excited in the resonator. Effective k₁₅´ of the resonator was determined to be 0.052, and TCF was found to be -30.2 ppm/°C.