Initial silicide formation process of Mo/(100) Si system prepared using an ultrahigh-vacuum sputtering system

In order to investigate the effect of the vacuum conditions on the process of initial formation of Mo silicides, Mo/Si systems were subjected to heat treatment under high vacuum and clean ultrahigh vacuum, after which we compared and analyzed the behavior of interfacial solid-phase reactions by means of X-ray analysis, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. Results of investigation suggest that the temperature at which the initial silicide formation takes place in the ultrahigh vacuum is lower than that in the high vacuum. However, no differences in the formation phase were found under the different vacuum conditions. It was established that the initial formation processes under both high vacuum and ultrahigh vacuum conditions involve multiphase silicides consisting of Mo3Si, Mo5Si3, and MoSi2, and the film growth continues also as the multiphase silicides. During this time, the main phase is MoSi2, but since the dominant diffusing species are different for various vacuum conditions, during the sputtering under high vacuum the dominant diffusing species is Si, while under the ultrahigh vacuum, Si diffusion begins at a lower temperature simultaneously with Mo.