ABSTRACT In this work, we report on the fabrication results of surface acoustic wave (SAW) devices operating at frequencies up to 8 GHz. In previous work, we have shown that high acoustic velocities (9 to 12 km/s) are obtained from the layered AlN/diamond structure. The interdigital transducers (IDTs) made of aluminium with resolutions up to 250 nm were successfully patterned on AlN/diamond-layered structures with an adapted technological process. The uniformity and periodicity of IDTs were confirmed by field emission scanning electron microscopy and atomic force microscopy analyses. A highly oriented (002) piezoelectric aluminum nitride thin film was deposited on the nucleation side of the CVD diamond by magnetron sputtering technique. The X-ray diffraction effectuated on the AlN/diamond-layered structure exhibits high intensity peaks related to the (002) AlN and (111) diamond orientations. According to the calculated dispersion curves of velocity and the electromechanical coupling coefficient (K2), the AlN layer thickness was chosen in order to combine high velocity and high K2. Experimental data extracted from the fabricated SAW devices match with theoretical values quite well.
Digital Object Identifier 10.1109/TUFFC.2007.411
© 2007, by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.