Study of reaction kinetics for titanium disilicide formation by evaporated titanium on silicon

Abstract

A study of evaporated titanium films on silicon forming titanium disilicide has been made. Two types of configuration consisting of titanium/n-silicon/titanium/ native oxide/silicon and titanium and silicon respectively were used. Both nitrogen and vacuum annealing methods were employed for silicidation. The vacuum annealing method yielded titanium disilicide with the lowest sheet resistance of 0.8 Ω per square and was successfully implemented in a salicide process. The film surface as revealed by scanning electron microscopy was quite smooth. It was also possible to vary the transition temperature by the heating rate. The nitrogen anneal method produced films with higher sheet resistance (1.2 Ω per square) as the top surface developed a titanium nitride layer during annealing. X-ray diffraction and Auger electron spectroscopy techniques revealed the formation of a metal-rich monosilicide in the beginning which ultimately transformed to titanium disilicide after passing through the titanium monosilicide phase.