High-Resolution Transmission Electron Microscopy of Interfaces between thin Nickel Layers on Si(001) After Nickel Silicide Formation under Various Annealing Conditions

Abstract

Local structures of nickel silicide formed by heat treatment of a nickel layer sputtered on silicon (100) substrate were observed by high-resolution transmission electron microscopy. In the specimen as-sputtered and after heat treatment at 498K, a thin layer was found at the interface between Ni (Ni2Si) and the Si substrate. The layer was an initial phase of silicidation and seems to be non-fluorite type NiSi2. When annealed around 600K, the NiSi2 phase disappeared and a NiSi phase grew dominantly. At the interface of NiSi/Si, the crystal lattices appeared smooth, because the lattice mismatch between NiSi and Si was absorbed by lattice distortion within a few atomic layers of the interface. The Ni3Si2 and Ni2Si phases remaining in the grown NiSi layer were also identified by Fourier analysis of the lattice fringe