The properties of the Y2O3 films exposed at elevated temperature

Yttrium trioxide (Y2O3) thin films have been deposited on silicon (1 1 1) substrates by RF magnetron sputtering. The influences of thermal exposure at high temperature in air on the structure, the surface morphology, roughness, and the refractive index of the Y2O3 thin film were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscopy (AFM), and spectroscopic ellipsometry (SE). The results indicate that chemical composition of the as-deposited Y2O3 film is apparently close to the stoichiometric ratio, and it has a cubic polycrystalline structure but the crystallinity is poor. The monoclinic and cubic phases can coexist in the Y2O3 film after thermal exposure to 900 °C, and the monoclinic phase disappears completely after 300 s exposure to 950 °C. The changes of the surface morphology, roughness, and the refractive index of the Y2O3 film are closely related to the crystal structure, the internal stress, and various defects influenced by thermal exposure temperature and time.