Sputtering Deposition of Lead-free Piezoelectric (K, Na)NbO3 Thin Films

We fabricated composition gradient sodium potassium niobate [(K,Na)NbO₃, KNN] thin films on (111)Pt/Ti/SiO₂/Si by multi-target RF magnetron sputtering to optimize KNN film composition by combinatorial method. We successfully obtained c-axis oriented KNN thin films with perovskite structure on 6-inch Si wafers. The KNN film composition was measured by energy dispersive x-ray spectroscopy (EDX) and we confirmed composition gradient of K/(K+Na) ratio of the KNN thin film on Si wafer along with the line between KNbO₃ and NaNbO₃ targets. This result indicates that the combinatorial sputtering is useful for precise optimization of the deposition condition and film composition of the lead-free KNN thin films.