Correlation of interface roughness for ion beam sputter deposited W/Si multilayers

Abstract

W/Si multilayers having 5, 7, 9, 13, 17, and 25 layers have been deposited on c-Si substrates by Ion Beam Sputtering technique and have been characterized by specular and diffused grazing incidence X-ray reflectivity measurements. Information regarding the density, thickness and interface widths of individual layers of the multilayer stacks have been obtained from the theoretical fitting of the specular reflectivity spectra while fitting of the diffused X-ray reflectivity have yielded information regarding roughness and diffusivity at the individual interfaces along with the in-plane correlation lengths of roughness of the individual layers and the vertical correlation length of the whole multilayer structure. Investigations have been carried out on the different behavior of W-on-Si and Si-on-W interfaces and on the variation of the above parameters with the increase in number of layers in the multilayer structures.