Critical nickel thickness to form silicide transrotational structures on [001] silicon

The effect of the sputtered Ni layer thickness (7-14 nm) on the silicide phase transition was studied at 260 degrees C. In 7-nm-thick layers, the complete mixing of Ni and Si occurring during deposition produces stable Ni2Si transrotational structures which further evolve into similar NiSi domains within 50 min of annealing. In 14-nm-thick layers, the residual unmixed Ni atoms diffuse towards the interface and speed up the transition from Ni2Si to NiSi (25 min) by promoting the nucleation of polycrystaline NiSi grains. A competition between NiSi trans- and poly-structures occurs, and the resulting layer morphology depends on the reaction temperature. (c) 2006 American Institute of Physics.