Reactive sputtering process and properties of Ba(ZrxTi1−x)O3 films for high frequency applications

Ba(Zr_xTi_1-x)O₃ (BZT) thin films with different Zr contents were deposited on (100)MgO and Pt/(100)MgO substrates by RF-magnetron reactive sputtering using metal targets. Coplanar and parallel plate capacitor structure with Pt/Au electrode based on BZT/MgO and BZT/Pt/MgO layer was fabricated by sputtering, photolithography, and etching processes. 500-nm-thick BZT thin films for high frequency performance showed a single perovskite phase and a high crystallinity on the MgO substrate with only a (001)/(100) orientation at an optimum deposition conditions. The BZT films had a stoichiometric Ba/Ti ratio and epitaxially grew on the MgO substrate. They showed a dense microstructure without cracks or voids. Dielectric properties of BZT thin films on (100)MgO substrates with different Zr contents (0 <; × <; 0.92) showed little dispersion at 1-40 GHz. Moreover, tunability of BZT thin film (x = 0.3) with parallel plate capacitor showed up to 43 % under 600 kV/cm. These results indicated that we succeeded in depositing high-quality and potentially tunable ferroelectric BZT films for high-frequency applications by RF-magnetron reactive sputtering using metal targets.