Dielectric properties of rf-sputtered Y2O3 thin films

Yttrium oxide (Y2O3) thin films were deposited on indium-tin-oxide(ITO)-coated glass substrates by the radio-frequency-sputtering method using an Y2O3-sintered target. The relative dielectric constant εr and the dielectric strength EBD of the Y2O3 films were studied. It was found that εr and EBD have a maximum value and a minimum value, respectively, at 1.3 Pa when the pressure of the sputtering gas, Ar+10% O2, is varied from 0.67 to 9.3 Pa. The x-ray diffraction study showed that the Y2O3 films deposited at 1.3 Pa are predominantly oriented along the 〈332〉 direction and their grain size is the smallest. Ion mass analysis showed impurity diffusion from ITO in the films deposited at 1.3 Pa. Furthermore, the dielectric properties of the Y2O3 films deposited at 1.3 Pa are related to the structural properties, such as the 〈332〉 orientation, grain size, and impurity diffusion.