Formation of Ni silicide from atomic layer deposited Ni

The silicidation of Ni deposited by plasma-enhanced atomic layer deposition with NH₃ plasma and thermal atomic layer deposition using NH₃ gas were comparatively studied. A SiN_x interlayer was formed between the Ni deposited by plasma-enhanced atomic layer deposition and the Si substrate due to the direct exposure of the substrate to plasma, while no interlayer was observed when using thermal atomic layer deposition. In the plasma-enhanced atomic layer deposition, the diffusion of Ni was suppressed by the SiN_x interlayer, so no Ni₂Si phase was formed and its formation temperature increased. Ni formed by thermal atomic layer deposition showed sequential phase transformations to Ni₂Si, NiSi, and NiSi₂ with increased annealing temperatures. In the nanosized contact holes, a large amount of NiSi₂ was formed due to the limited supply of Ni. These results provide important information for the fabrication of silicide in nanoscale 3D devices.