Applied Physics Letters · 1986 · 34 citations · 6 references
Natural SciencesMaterials EngineeringMaterials ScienceMaterials ChemistrySemiconductor MaterialsThin FilmsAmorphous MaterialsAmorphous SolidsSemiconductor InterfacesSemiconductor SurfacesSemiconductor Thin FilmsThin Film AnnealingAnnealing EffectsAnnealing Temperature EffectsAnnealing Time EffectsCrystal Nucleation KineticsNucleation KineticsPhase FormationSubstrate Temperature EffectsThermal Annealing
The initial stages of silicide formation in very thin-layered Si/Ni/Si films reacted by rapid (pulsed) annealings were investigated using the rapid thermal annealing/transmission electron microscopy technique. At least four phases, NiSi, δNi2Si, θNi2Si, and Ni31Si12, are shown to form first after 1 s annealings in the 175-300 °C temperature regime; the actual phase and its nucleation kinetics depend on the Si:Ni ratio and on substrate deposition temperature. An amorphous (Ni+Si) mixture is shown to exist as a precursor to θNi2Si and NiSi. The multiplicity of ‘‘first’’ phases and the dependence on the Si:Ni ratio contradict various ‘‘first-phase’’ rules and steady-state annealing data obtained on thicker films and in metal-Si wafer reactions. A simple model that accounts for the stoichiometry and substrate-temperature dependences is suggested.
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