C-axis inclined AlN film growth in planar system for shear wave devices

Abstract

AlN thin films are of continued interest for exciting acoustic waves for surface and bulk acoustic wave devices. This work reports on the growth and the characterisation of AlN films with the c-axis inclined. These films are of significant interest for shear wave generation in view of realisation of surface acoustic wave devices operating as liquid sensors. AlN films were deposited on 3inch silicon wafers, covered by a SiO 2 buffer layer. The deposition was carried out using an RF magnetron sputtering planar system under various deposition parameters, including pressure and temperature. The crystalline orientation and the inclination of the c-axis of the obtained AlN films were investigated using X-ray diffraction and by scanning electronic microscopy. These analyses showed that a c-axis inclination of up to 13° was obtained in our planar charging system under high pressure and at a temperature of 300°C. The shear mode acoustic wave device based on the deposited c-axis inclined AlN film was produced and showed that a phase velocity of 5832m/s was obtained. This value of shear velocity is discussed.