Thermally stable W/Silicide/Si contact

A thermal stability of the W/WSi
x
/Si, W/TiSi
x
/ Si, W/TiN/TiS
2
/Si contact structures has been investigated under annealing conditions up to 900°C. Thermal reactions in the W/WSi
x
/Si and W/ TiSi
x
/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/WSi
2
/Si contact structure was obtained, while the W/TiSi
2
/ Si contact structure changed into a WSi
2
/TiSi
2
/Si contact structure after annealing. At the TiSi
2
/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/TiSi
2
/Si contact structure. The TiN was formed by a rapid thermal nitridation of the TiSi
2
layer. The contact resistivity of the value of 5 × 10
^-6
Ω.cm
²
was obtained even after 800°C annealing.