Characterization of zirconia films deposited by r.f. magnetron sputtering

Abstract

Thin films of zirconium oxide were prepared by r.f. magnetron sputtering from a ZrO 2 target. A systematic study has been made on the influence of the sputtering parameters (total pressure, oxygen partial pressure and r.f. power) on the film composition and on their structural and optical properties. The zirconia films crystallize either in the cubic or in the monoclinic phases depending on the sputtering gas. The crystallinity and the compactness of the films were found to increase with the kinetic energy of the sputtered particles. The stresses are compressive and become very important in thick films deposited at a high power density. Films are generally substoichiometric and their O/Zr atomic ratio was found to increase with the oxygen partial pressure. On the contrary, films deposited at high sputtering pressures (more than 5 Pa) contain an oxygen excess. This overstoichiometry results, as it was revealed by F. T. I. R. analyses, from the incorporation of water and hydroxyl groups into the ZrO 2 structure. The optical constants (refractive index and extinction coefficient) vary also in a wide range with the deposition conditions. These variations were correlated mainly to structural properties.