Improvement of thermal stability of nickel silicide using N2ion implantation prior to nickel film deposition

Nitrogen ion implantation (N₂ I.I.) prior to Ni film deposition successfully suppresses the agglomeration of nickel silicide (NiSi) formed on arsenic doped silicon substrate in NMOS region, and drastically improves the thermal stability of its resistivity at narrow lines. Using this technique, lower sheet resistance of NiSi narrow line can be kept at high annealing temperature of 650degC for 30 sec. Comparing with argon ion implantation (Ar I.I.), only the N2 I.I. can suppress the agglomeration of NiSi. These results suggest that the implanted N₂ ions form Ni-N or Si-N bonds in NiSi, and as a result, these bonds suppress the excess diffusion of Ni and Si atoms during thermal process