In Situ Ellipsometry Analysis on Formation Process of Al2O3-Ta2O5 Films in Ion Beam Sputter Deposition

Al2O3-Ta2O5 thin films are known as highly corrosion-resistant materials for coatings. Here the formation process of Al2O3-Ta2O5 films was analyzed by in situ ellipsometry during deposition by ion beam sputtering. Composite targets composed of Al2O3 and Ta2O5 plates were used for sputter deposition. During deposition, the formation process of thin films was monitored by a single-wavelength rotating analyzer ellipsometer attached to the sputtering system. The composition, the chemical binding states of constituent elements, and the depth profile of the elements of the films were analyzed by inductively coupled plasma-atomic emission spectroscopy, X-ray photoelectron spectroscopy (XPS), and auger-electron spectroscopy (AES), respectively. Ellipsometric analysis showed that the thickness of the film increased linearly with time after short induction periods. The refractive index of the films increases with increasing tantalum cationic fraction. The extinction coefficient of the films was larger than those of single Al2O3 and Ta2O5 films. The XPS analysis showed that the preferential deposition of the Ta2O5 component occurred in the induction period and the codeposition of Ta2O5 and Al2O3 in the linear growth stage. The AES analysis showed that the content of constituent elements was homogeneous from the top to the bottom of the films in the linear growth stage. [Example substrates: Fe, Pt].