Aging effect of optical properties on SiO2films grown on Si substrates by ion beam sputtering

Abstract

SiO 2 is a very important low refractive index material and usually used in combination with high refractive index material to manufacture the coatings with low optical loss. In this paper, SiO 2 films were deposited on Si substrates by an ion beam sputtering (IBS) technique and SiO2 target with purity of 99.99% was used as SiO 2 thin films forming material. The thickness of SiO 2 films grown onto Si substrates are about 900 nm. Aging optical properties of SiO 2 films were investigated as a function of time placed in the air. Spectroscopic ellipsometry was used to measure optical constants of SiO 2 films. The refractive index of SiO 2 films change with the increase of placed time. When the placed time reaches more than 200 days, the value of refractive index tends to be constant and the corresponding variation rate is about 0.5%. As the placed time increases, the physical thickness and optical thickness also drive to be stabilization. It can be seen that optical properties of SiO 2 films prepared by IBS technique under some process parameters are very stability.