Real-time optical studies in the UV range of the annealing of zirconium-oxide thin films in vacuum

A multichannel spectroscopic ellipsometer is developed for real-time studies of thin films in a vacuum in the UV range. This system is mounted on a vacuum chamber to study the crystallization process of zirconium-oxide (ZrO2) thin film. The optical spectra of ZrO2 thin film are collected during the elevation of temperature. From the trend in the spectrum, we find that a threshold temperature for crystallization exists. Moreover, the crystallization occurs gradually over a certain range of temperatures between the threshold temperature and a critical temperature for full crystallization. The evolution of the dielectric function shows the development of critical peaks around 6.2 eV and 7.3 eV along with a shift of the absorption edge. To the best of our knowledge, this is the first in-situ study performed by using real-time vacuum UV spectroscopic ellipsometry, and we describe the system in detail.