In many technologies a means of characterizing the surfaces of vacuum-deposited metal films would be desirable. Following the first part of this work, which dealt with light scattering, we have assessed ellipsometry as a possible tool. For surfaces with a root-mean-square roughness smaller than 40 nm the influence of roughness on ellipsometric parameters ψ and Δ was observed to be very small (<0.02°/nm) at a wavelength of 632.8 nm. These surfaces however had a different morphology as shown by a scanning electron microscope. Rougher surfaces showed a dominant decrease in ψ and a relatively smaller decrease in Δ with increasing roughness. Besides the influence of surface roughness, the particular morphology of the surface and the constitution of the residual gas atmosphere during evaporation of the Al thin film were shown to be also of significance. For this reason, together with the inability to discriminate between roughness values in the 0–40-nm range, ellipsometry at 632.8 nm wavelength is less suitable for measuring surface roughness of vacuumdeposited films.
© 1986 Optical Society of America
Ivo J. M. M. Raayjmakers and Maarten J. Verkerk, "Characterization of the topography of vacuum-deposited films. 2: Ellipsometry," Appl. Opt. 25, 3610-3615 (1986)