Thermally stable W/Silicide/Si contact

A thermal stability of the W/WSix/Si, W/TiSix/ Si, W/TiN/TiS2/Si contact structures has been investigated under annealing conditions up to 900°C. Thermal reactions in the W/WSix/Si and W/ TiSix/Si contact structures were strongly affected by a metal-silicon ratio, X, and a material of metal silicide. The silicide layers with precisely controlled X values were formed by the novel co-sputter method. The thermally stable W/WSi2/Si contact structure was obtained, while the W/TiSi2/ Si contact structure changed into a WSi2/TiSi2/Si contact structure after annealing. At the TiSi2/Si interface, a segregation of oxygen did not occur after 900°C annealing. A thermally stable and low resistance W/Silicide/Si contact structure up to the 900°C process was successfully realized by the W/TiN/TiSi2/Si contact structure. The TiN was formed by a rapid thermal nitridation of the TiSi2layer. The contact resistivity of the value of 5 × 10^-6Ω.cm²was obtained even after 800°C annealing.