The Influence of Negative Ions Generation on the Arc-Melted and Hot Press Sintered Scal Alloy Targets to the Crystalline Orientation and kt2 of the Scaln Films

摘要

Film Bulk Acoustic Resonator (FBAR) will become commonplace for the frequency filter used in mobile communication. AIN films were used for piezoelectric material of FBAR. High piezoelectricity of ScAlN films have attracted much attention as FBAR material. However, negative ion generation at Sc metal target induces degradation of the crystallinity due to the ion bombardment on ScAlN films during the sputtering growth. Large amount of O^{- and CN- ions generation at sputtering target were observed. In this study, we compared the energy distributions of negative ions of arc-melted and sintered ScAl alloy targets which have different oxygen and carbon concentration. The c-axis orientation and electromechanical coupling coefficient kt2 of ScAlN films fabricated with these different targets were also compared. As a result, the kt2 of two targets was larger than our previous report. There were the large differences in amount of O- and CN- ions generation in the two targets. However, it does not significantly affect the results of the crystallization and kt2 of the ScAlN films.}