Properties of AlN thin film deposited by reactive RF magnetron sputter for SAW device application

AlN thin film has been deposited on the Si wafer and the Al/sub 2/O/sub 3/ substrate by reactive radio frequency (RF) magnetron sputtering method under various operating conditions such as working pressure and fraction of nitrogen partial pressure. Scanning electron microscope (SEM), X-ray diffraction (XRD), atomic force microscope (AFM) have been measured to investigate structural properties and preferred orientation of AlN thin films. SAW velocity of IDTs/AlN/Si structure was about 5038 [m/sec] at the center frequency of 251.9 [MHz] and insertion loss was measured to be relatively low value of 35.6 [dB]. SAW velocity of IDTs/AlN/Al/sub 2/O/sub 3/ structure was improved to be about 5960 [m/sec] at the center frequency of 296.7 [MHz].