Crystallization investigation of NiSi₂ thin films

Recrystallizations of ion-irradiated single crystalline and polycrystalline NiSi2 films are investigated. In the single crystalline case, the irradiated surface portion of the NiSi2 film reorders epitaxially in a layer-by-layer manner, initiating from the remaining undamaged single crystalline NiSi2 seed near the NiSi2/Si interface. The irradiated polycrystal-line NiSi2 layer recrystallizes via growth from a fixed number of existing nuclei in the layer. In both cases, the recrystallization occurs with a relatively high velocity at very low temperatures (~ 100C) and the activation energy of the growth rate is similar (1.2 to 1.4 eV). These results reflect the metallic bonding nature of NiSi2 and the fact that nucleation and mass transport are not required for growth from an amorphous mixture with a stoichiometric atomic composition and existing nuclei.