Improved NiSi salicide process using presilicide N/sub 2//sup +/ implant for MOSFETs

An improved Ni salicide process has been developed by incorporating nitrogen (N/sub 2//sup +/) implant prior to Ni deposition to widen the salicide processing temperature window. Salicided poly-Si gate and active regions of different linewidths show improved thermal stability with low sheet resistance up to a salicidation temperature of 700 and 750/spl deg/C, respectively. Nitrogen was found to be confined within the NiSi layer and reduced agglomeration of the silicide. Phase transformation to the undesirable high resistivity NiSi/sub 2/ phase was delayed, likely due to a change in the interfacial energy. The electrical results of N/sub 2//sup +/ implanted Ni-salicided PMOSFETs show higher drive current and lower junction leakage as compared to devices with no N/sub 2//sup +/ implant.