Interfacial roughness in multilayer films may be random or correlated, i.e., replicated from layer to layer. It is shown that these can be separated and quantified using x-ray diffraction rocking curves and a straightforward analysis. The lateral correlation length along the interfaces can additionally be determined. A quantitative evaluation for W/C multilayers shows that correlated roughness contributes significantly to the total roughness, even at length scales that are surprisingly short, of the order 2–6 nm.

A series of W/C multilayer films sputter deposited on Si( 100) substrates with total thickness ranging from 400 to 6400 A and bilayer period from 20 to 160 A were examined to explore the variation of inter-facial roughness and interfacial roughness correlation with film thickness and period. The films were characterized with x-ray diffractometry. Average inter-facial roughness is obtained from conventional ((328) scans, while information on roughness correlation is extracted from rocking-curve (transverse-profile) analysis. The magnitude of the roughness is found to depend more on bilayer period than on total film thickness. The observations suggest that interfaces retard the evolution of surface roughness and that thin "restarting" layers may be used to control the growth morphology of thin films. 3283