Thermal stability enhancement of Ni-based silicides, germano-silicides and germanides using W and F implantation for 3D CMOS sequential integration

This paper deals with the thermal and morphological stabilization of nickel-based silicides and germanides using tungsten and fluorine implantation for 3D monolithic CMOS applications. The incorporation of few % of W and/or F at various steps of the salicide process can successfully address two major issues: the morphological degradation (agglomeration) of NiSi and NiGe layers on one side and the Ge diffusion outside the active regions on the other side. The paper highlights cumulative effects of Pt alloying together with the incorporation of F and W for delaying at higher temperatures the agglomeration phenomenon. It also deals with the strong reduction of Ge diffusion using W and F implantation. Implantation conditions (dose, energy) and schemes (implantations prior metal deposition, after metal deposition, into the silicide) are discussed.