Suppression of NiSi-to-NiSi2 Transition Using Very Short-time RTA Silicidation

AbstractThermal stability of NiSi is a major concern for its application in sub-0.1 μm CMOS devices, due to the transition of NiSi to the high-resistivity disilicide (NiSi2) at elevated temperatures. In this study, we have investigated the effect of RTA silicidation duration on NiSito-NiSi2 transition during Ni-silicidation reaction of Ni film (20-25 nm thick) on (100)Si. It was found that the NiSi-NiSi2 transition temperature was increased remarkably from 700 to > 800 °C by reducing the RTA time from 60 to 1 s. Agglomeration of silicides films was also found to besuppressed by short-time annealing. A temperature-time transformation (TTT) diagram has been constructed, which demonstrates the time-dependency of NiSi-NiSi2 transition. Based on the classical theory on phase transformation kinetics, a concept of induction time was employed to elucidate the key roles of transformation time and film thickness in determining the NiSi-NiSi2 transition temperature.