In this study the nucleation and growth of Ni silicide(NiSi and $NiSi_2$) grown by evaporation and furnace annealing has been investigated by TME (Transmission Electron Microscopy). Ni(99.9%) was deposited by thermal evaporation on B-doped(1-3 Ωcm) (001) Si substrate. Prior to the evaporation, wafer was cleaned chemically to remove impurities on Si wafer. 2 nm of native oxide layer was remained after chemical cleaning. About 8 nm of films were deposited on (001) Si wafer. The films are $Ni_2Si$ phase and intermixed amorphous layer between $NiSi_2$ and native oxide layer.
Furnace annealing was carried out in 1×$10^{-6}$ Torr vacuum to prevent oxygen adsorption in Ni. Annealing temperature was 800℃ to produce $NiSi_2$, and 600℃ to produce NiSi.
The shape of $NiSi_2$ nucleus was inverted pyramid consisted of {111} faces, and has grown to Si substrate with epitaxial orientation relationship between $NiSi_2$ and Si substrate i.e. $[001]_{NiSi_2}$//$[001]_{Si}$ and $(001)_{NiSi_2}$//$(001)_{Si}$. {100} $NiSi_2$ interfaces were also observed at the initial stage of nucleation. But, as the nucleus grow, {100} interfaces disappeared and the interfaces of nucleus became only {111} planes because {111} planes are lowestenergy planes. Ni silicide grows into Si substrate due to Ni diffusion. But the nucleus partly grows into the evaporated film due to Si diffusion. After 40 h annealing at 800℃, continuous $NiSi_2$ film was grown and inverted pyramid shape of $NiSi_2$ continued nucleation at the interface between $NiSi_2$ film and Si substrate. After 40 h annealing at 800℃, $NiSi_2$ nucleus that has $[001]_{Si}$//$[112]_{NiSi_2}$ orientation relationship was observed. It has grown in <110> and <111> directions and has sharp interfaces perpendicular to <111> directions. After 4h annealing at 600℃, NiSi was nucleated from $Ni_2Si$ and formed islands on the native oxide. $Ni_2Si$ had had no reaction with Si substrate and produced NiSi islands and Ni phase. Instead of Ni diffusion, $Ni_2Si$ decomposition was held according to the reaction $Ni_2Si$ → NiSi + Ni.
