Dynamic in situ spectroscopic ellipsometric study in inhomogeneous TiO2 thin-film growth

Abstract

We investigate the film-growth process of the inhomogeneous sputtered TiO2 thin films by the in situ real-time spectroscopic ellipsometer. The growth process of the film is analyzed by both the uniform and the island film growth models. Based on the analyses from the Ψ-Δ trajectories, the initial thin-film growth corresponds to the island film growth model for a single-layer film. As the film grows, the microstructural phase changes cause the transition from the single-to the double-layer physical model, because of the development of the inhomogeneity in the TiO2 thin film. The dynamic fits with the double-layer physical model and the Cody–Lorentz optical model indicate three different stages of the film growth: the nucleation stage, the coalescence stage, and the continuous-layer stage. Although our presented model works well for most of the experimental data, the determination of the refractive index at the ultrathin thickness may be problematic.