P3O-1 5GHz SAW Devices Based on AlN/Diamond Layered Structure

In this work, we report on the fabrication results of SAW devices operating at frequencies up to 8GHz. In previous work, we have shown that high acoustic velocity (9 to 12 km/s) is obtained from the layered AlN/diamond structure. The interdigital transducers (IDTs) made in aluminum with resolutions down to 300nm were successfully patterned on AlN/diamond layered structures with an adapted technological process. The uniformity and periodicity of IDTs were corroborated by field emission scanning electron microscopy and atomic force microscopy analyses. Highly oriented (002) piezoelectric aluminum nitride thin film was deposited on nucleation side of CVD diamond by magnetron sputtering technique. The X-ray diffraction made 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 electromechanical coupling coefficient (K² ), the AlN layer thickness was chosen in order to combine high velocity and high K². Thus, the expected values predicted by calculation match quite well the experimental data extracted from fabricated SAW device