高周波スパッタによる高配向Ta_2O_5圧電薄膜の作製

摘要

酸素ラジカル源を搭載した高周波スパッタ装置を用いて，溶融石炎上にX軸配向Ta_2O_5薄膜を作製し，その配向性とレイリー型弾性表面波伝搬特性を評価した結果について述べている．酸素ラジカルの導入によって，（200）面のX緑回折ピークが顕著に現れること，電気機械結合係数が増加すること，表面粗さが低減することを明らかにした．基板温度700℃で成膜された規格化膜厚0．135のX軸配向膜では，0．23％の電気機械結合係数が得られた．%Highly X-axis-oriented tantalum pentoxide (Ta_2O_5) piezoelectric thin films were deposited on a fused quartz substrate using an RF-magnetron sputtering system with a metal tantalum target and an O_2-radical source. The degree of orientation and the Rayleigh-type surface acoustic wave properties were evaluated. It was found that supplying the RF power to the O_2-radical source markedly activated the orientation of the film, increased the coupling factor, and reduced the surface roughness. When the substrate temperature was 700℃ and the atmosphere gas flow ratio Ar:Ar:O_2 for the two cathodes with/without the target and radical source was 30:3:10 ccm, the coupling factor of the oriented Ta_2O_5 thin film with the normalized thickness h/λ of 0.135 was measured to be 0.23%.