Highly oriented ta2o5 piezoelectric thin films prepared by rf-magnetron sputtering

Highly X-axis-oriented tantalum pentoxide (Ta₂O₅) piezoelectric thin films were deposited on a SiO₂ substrate using an RF-magnetron sputtering system with a metal tantalum target and an O₂-radical source. The degree of orientation and the Rayleigh-type surface acoustic wave properties were evaluated. When the SiO₂ substrate temperature was 700°C and the O₂ flow rate was 10 ccm, the coupling factor K² of the oriented Ta₂O₅ thin film with a normalized thickness h/¿ of 0.21 was measured to be 0.88% and was about 3/4 of that for the previously obtained thin film using a DC-diode sputtering system. In the deposition on Si(100), a higher orientation was observed. Moreover, for the 1st mode of the Rayleigh-type SAW on the Ta₂O₅/MgO(100), the K² of 1.42% and the phase velocity of 5,126 m/s were obtained for the normalized thickness h/¿ of 0.225.