Development of a Dynamic Imaging Spectroscopic Ellipsometer Equipped with a CCD Image Sensor

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A dynamic imaging spectroscopic ellipsometer (DISE) has been constructed using a two-dimensional CCD sensor and a variable wavelength light source. The ellipsometer has been applied to the real-time analysis of growth and dissolution processes of CVD oxide thin films, and also to the analysis of spatial variations in thickness and spectroscopic properties of passive films on stainless steels and crabon steels. The principal findings of this study are summarized as follows :1. The DISE equipment developed enables to be applied to both real-time spectroscopic ellipsometric (RTSE) and imaging ellipsometric (IE) measurements. Spectra with 512 wavelength points could be measured within 100ms by the RTSE mode and images with a 25mm resolution could be obtained within 5s by the IE mode.2. The growth process of ZrO_2 thin films, deposited by MOCVD, was analyzed using RTSE.It was found that the growth of the films proceeds in three consecutive stages ; cluster nucleation, bulk layer growth and surface roughness evolution. It was also demonstrated that the selective dissolution of a Fe_2O_3 component occurs during reductive dissolution of Fe_2O_3-Cr_2O_3 thin films, formed by MOCVD, while that of a Cr_2O_3 component does during oxidative dissolution of the films.3. The changes in spatial distribution of thickness and optical constants of passive films on 18-8 stainless steel were examined in 0.1M-NaCl. It was found that in the incubation period of pitting, the spatial variation in film thickness occurs and the pit tends to initiate at a site where the variation is large. The results of the analysis of spatial distributions of the thickness and optical spectra of passive films on carbon steel (0.12%C) showed that the films formed on a ferrite structure is about 10% thicker than those formed on a pearlite structure.