Abstract

Most conventionally-deposited optical thin films have columnar microstructure since they are deposited under a thermal nonequilibrium condition. The columnar microstructure evokes many undesirable optical effects, such as lower packing density and refractive index, vacuum-to-air spectral shift of optical spectrum, and anisotropy in index. Ion beam assisted deposition(IBAD) has been used widely as a technique to produce denser films than conventional films. It is known that zirconia films have negative inhomogeneity in refractive index as they grow and the optical inhomogeneity was related to the crystalline inhomogeneity^[1]. It suggests that the columnar microstructure may be contracting as the thickness increases from the substrate^[2]. It is reported that IBAD produces denser ZrO₂ films than conventional films and induces crystallization of ZrO₂ films into cubic phase at room temperature^[3]. However, the relationship between inhomogeneity and microstructure of IBAD ZrO₂ films has not been studied much. The purpose of this paper is to study the effects of Ar ion bombardment on the the inhomogeneity and microstructure of ZrO₂ films and their optical and mechanical properties are presented in terms of normalized ion momentum.

© 1995 Optical Society of America