Abstract

Deposition of a thin (200–500-nm) metal film on a polished metal substrate changes its optical scatter characteristics.¹ The light scatter due to high spatial frequency structure is reduced by as much as a factor of ten, and total integrated scatter is reduced by up to a factor of four. This effect is strongly influenced by the deposition technique employed, initial surface roughness, and film thickness. We have examined the scatter characteristics of Cu, Ag, and AI films deposited using evaporation, magnetron sputtering, and ion assisted deposition (IAD), and the scatter reduction is most apparent in the case of films deposited using IAD (300 eV Ar⁺). The reduction in optical scatter is presumably due to a reduction in the microstructure of the surface (i.e., a smoothing effect). However, when the samples are characterized using a profilometer (Talystep), the smoothing effect is not observed. An attempt to resolve this apparent discrepancy is discussed; a comparison of the spatial frequency bandwidths of the two measurement systems will be presented.

© 1985 Optical Society of America