Improved NiSi salicide process using presilicide N2+ implant for MOSFETs

Abstract

An improved Ni salicide process has been developed by incorporating nitrogen (N2+) 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 °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 NiSi2 phase was delayed, likely due to a change in the interfacial energy. The electrical results of N2+ implanted Ni-salicided PMOSFETs show higher drive current and lower junction leakage as compared to devices with no N2+ implant.