Abstract
The effects of different film thickness and annealing time on the formation of nickel silicides in nickel thin film on silicon have been investigated.NiSi and epitaxial NiSi2 were found to form in Ni (30 nm) / (001) Si samples after annealing at 700 ℃ for 60 sec. Although the surface coverage of silicides (NiSi and epitaxial NiSi2) on silicon was almost 100%, pinholes, 0.1 - 0.5 μm in size, were observed. The pinholes were found to distribute mostly in the NiSi regions. After 750 - 850 ℃ annealing, epitaxial NiSi2 with {111} facets was the only silicide phase present. Almost full surface coverage of epitaxial NiSi2 was found. Pinholes were seldom observed.NiSi and epitaxial NiSi2 were found to form in Ni (30 nm) / (001) Si samples after annealing at 700 ℃ for 5 sec. Pinholes, 0.1 - 0.3 μm in size, were observed. The pinholes were found to distribute mostly in the NiSi2 regions. After 750 - 850 ℃ annealing, epitaxial NiSi2 was the only silicide phase present. Pinholes were seldom observed.Only epitaxial NiSi2 was found to form in Ni (5 nm) / (001) Si samples after annealing at 700 ℃ for 5 sec. Pinholes, about 0.1 μm in size, were observed. Pinholes, 0.1 - 0.3 μm, were also observed in 750 ℃ annealed samples. After 700 - 850 ℃ annealing, epitaxial NiSi2 was the only silicide phase present. Almost full surface coverage of epitaxial NiSi2 was found. Pinholes were seldom observedPossible mechanisms for the formation of pinholes are discussed. Partial transformation of epitaxial NiSi2 with lower density and higher thermal expansion compared with those of NiSi in the silicide film was found to cause significantly rougher surface with the occurrence of pinholes.