The structure of Mo/Si multilayers prepared in the conditions of ionic assistance

Abstract

The influence of a negative substrate-applied bias potential on the structure of periodic Mo/Si multilayer compositions has been investigated by means of cross-sectional electron microscopy, small-angle X-ray reflectivity, X-ray diffraction and by modeling the small-angle spectra. It is known that the crystalline structure of molybdenum layers is the main source of interface roughness. In the absence of a bias potential application, the interface roughness tends to develop from the substrate towards the surface of a Mo/Si multilayer composition. A negative bias potential (up to -200 V) applied to a substrate during silicon layer deposition leads to smoother interfaces and improves the layer morphology. After increasing the bias potential over -200 V a considerable growth of an amorphous interlayer transition zone can be observed at Si-on-Mo interfaces. By raising the bias potential during the deposition of Mo layers a development of roughness at Mo-on-Si interfaces as well as growing interlayer thicknesses were found.