Synthesis and structural characteristics of ion‐beam sputtered multilayer Ag/Al thin films

Abstract

Multilayers of Ag/Al with layer thickness ratio of 1.7:1.0 have been deposited on Si and glass substrates using ion‐beam sputtering with composition modulation wavelengths λ ranging from 13.5 to 213 Å. Spatial distribution and angular dependence of deposition rates were determined by analysis of x‐ray diffraction scans which showed several orders of distinct satellite peaks and well defined small angle peaks. At high modulation wavelengths (λ≳35 Å), the multilayer film showed (111) preferred orientation normal to film plane. For short modulation wavelengths (λ<35 Å), other orientations appeared and peaks corresponding to Ag2Al intermetallic phase were also observed. One satellite peak corresponding to Ag2Al(100) peak was observed and gave the same modulation wavelength as the parent Ag/Al multilayer. The computer simulation analysis using square wave model is in good agreement with the observed satellite peak positions for high modulation wavelengths. The average lattice parameter of the Ag/Al multilayer reduces by 1.1% as the modulation wavelengths drops below 35 Å, which may be partially attributed to the presence of a significant proportion of Ag2Al interphase layers at the interface.