Deposition of high transparent and hard optical coating by tetraethylorthosilicate plasma polymerization

This study aims at synthesizing highly transparent and hard fluorine doped silicon oxide films by tetraethylorthosilicate-oxygen-tetrafluoromethane plasma polymerization. The films were deposited by plasma enhanced chemical vapor deposition method at low temperature. Mechanical properties such as hardness, reduced elastic modulus and plasticity index were studied by nanoindentation analysis. Optical properties of the films such as transmittance, absorbance, reflectance, refractive index, and extinction coefficient were characterized by spectroscopic ellipsometry. Moreover, transparency of the films was studied by normal incidence ultraviolet-visible spectroscopy. It was found that the optical and mechanical properties of the deposited films were affected by changing carbon bonds in the films chemical structure such as C-2, CF2, and C2F2. It was also shown that decreasing the power applied could result in an increase in the carbon content of the fluorinated silicon oxide film without using additional carbon precursor, conditioned on using an organosilicon precursor and tetrafluoromethane. It can improve the mechanical properties of the film.