Anomalous first-phase formation in rapidly thermal annealed, thin-layered Si/Ni/Si films
- 4 August 1986
- journal article
- Published by AIP Publishing in Applied Physics Letters
- Vol. 49 (5) , 257-259
- https://doi.org/10.1063/1.97188
Abstract
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.Keywords
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