C-Ni multilayer reflectors: an AFM roughness study

Abstract

Amorphous C-Ni superlattice films designed as normal-incidence reflector for 5 nm have been grown on quartz substrates by magnetron sputter deposition in Ar discharge. An extended set of characterization techniques has been applied: Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) in order to characterize the growth conditions. ThM measurements revealed information about the evolution of smoothness and the uniformity of the multilayer structure function of the distance to the substrate. A new DSP-controlled AFM system has been involved in investigating the surface topography of the final surface of the multilayer structure as well as the substrate. A detailed analysis of AFM topographic images is presented. Special attention has been paid to an important parameter for such niirrors, the surface roughness, for nanometric and micrometric areas, involving AFM tips with different radius of curvatute. Roughness analysis as well as the implication of the different radius curvature tips used in AFM-contact experiments are presented together with the power spectral density function calculation.