Kinetics of Ni thin film synthesis by supercritical fluid chemical deposition

Ni was deposited on TiN films by supercritical fluid chemical deposition (SFCD) through hydrogen reduction of the precursor Ni(hfac)2 3H2O. In this context, the kinetics and reaction mechanism of Ni thin film deposition were studied by using a SFCD flow-type reaction system. The results indicated that the Ni growth rate increased with precursor concentration and then saturated. Based on the Arrhenius plots, the apparent activation energy decreased with increasing H2 concentration, yielding values ranging from 0.90 to 0.61 eV. A kinetics and reaction scheme using the Langmuir-Hinshelwood model, with the surface reaction constituting the rate-determining step, generated a zero-order reaction with respect to precursor concentration. On other hand, the equilibrium constants for the adsorption of precursor and hydrogen in the reaction scheme of Ni thin film deposition decreased with increasing temperature, which indicated that the reaction was exothermic.