Chemical diffusion and agglomeration at the interfaces of thin Ru, Mo, Si and B4C layers were studied using X-ray photo-electron spectroscopy, cross-sectional electron energy-loss spectroscopy, high-angle annular dark-field scanning transmission electron microscopy and energy-dispersive X-ray methods to observe Ru-on-B4C capped Mo/Si multilayers. Silicides and borides, notably RuSix and MoBx, were formed at the Si/Mo interface front. The interface appeared to act as a precursor to further chemical diffusion and to the agglomeration of B, Ru and other d-metals. It was noted that so-called reversed substrate-on-adlayer interfaces could yield entirely suppressed reactivity and diffusion. This reflected the influence of surface free energy and the supply of atoms to the interface via segregation during thin-layer growth.

Chemically Mediated Diffusion of d-Metals and B through Si and Agglomeration at Si-on-Mo Interfaces. T.Tsarfati, E.Zoethout, R.van de Kruijs, F.Bijkerk: Journal of Applied Physics, 2009, 105[10], 104305