Microfabrication of surface acoustic wave devices with AlN thin film deposited on half-inch quartz wafer

Abstract

In this paper, we have fabricated surface acoustic wave (SAW) devices with six sets of interdigital transducers (IDTs) on half-inch wafers of quartz with deposited thin films of aluminum nitride (AlN). Firstly, AlN thin films have been deposited by reactive sputtering in Ar-N₂ gas mixture at 400°C with the high-power impulse magnetron sputtering (HiPIMS) system which was developed for microfabrication process in the localized clean environment with half-inch wafer (Minimal Fab). After that, IDTs of Al thin films have been prepared on the AlN thin films. The X-ray diffraction (XRD) pattern of the AlN thin films shows that the AlN films have c-axis (002) orientation. Furthermore, the frequency responses have been measured with four paired IDTs of the SAW devices, which were selected from six sets of IDTs as an input electrode and an output electrode. These results show device properties responding to the design of the IDTs and also suggest the potential of the fabricated SAW devices as the four-paralleled frequency filter and/or sensing system.