Microstructural study of annealed Cr/Si system using cross-sectional TEM combined with nano-analysis

Among the various characterization methods generally used in the study of silicidation mechanisms, particularly interfaces structure, the cross-sectional transmission electron microscopy (XTEM) combined with nano-analysis were not much used. This work dealt with the study, by mean of this method, of interfacial atomic diffusion phenomena in thin Cr/Si system in dependence on heat treatment conditions. The chromium film of 850 Å thickness was electron gun deposited onto (111) oriented phosphorus implanted Si substrate. The XTEM observations of samples annealed at 475 °C during 60 and 120 min showed that the chromium was partially consumed in opposite to the case where the Si substrate was not implanted. The thickness of formed chromium silicide was practically the same for 60 and 120 min. Nano-analysis revealed the presence of Si atoms at the surface and Cr atoms into the substrate leading to the formation of a crystalline Cr–Si alloy. However, after 500 °C during 5 min the obtained results showed that no reaction occurred between Si and Cr and Si atoms were present in the Cr film. This indicated that Si diffused towards the surface before silicidation.