A laterally uniform formation of NiSi2 at low temperature had been reported for the SiaNi/Sic system. In this work, the interfacial structure of NiSi2 is studied by the high-resolution electron microscopy. We observe an amorphous layer (5–10 nm in thickness) between Sic and NiSi2 in a Sia(300nm)/Ni(5Onm)/Sic sample after annealing at 450°C. The NiSi2 phase in this sample has a polycrystalline structure. We also find that a contaminated amorphous-Si film can not promote a reaction with Ni. A SIMS depth profile shows that this amorphous-Si layer is high in oxygen and carbon. In this case, the silicide formation is similar to the Ni/Sic system.