Kinetics of Deposition of Cu Thin Films in Supercritical Carbon Dioxide Solutions from a F-Free Copper(II) ␤-Diketone Complex

Abstract

Kinetics of deposition of Cu thin films in supercritical carbon dioxide solutions from copper bis͑di-isobutyrylmethanate͒ ͕Cu͓͑CH 3 ͒ 2 CH͑CO͒CH͑CO͒CH͑CH 3 ͒ 2 ͔ 2 ͖, Cu͑dibm͒ 2 ͒, a F-free copper͑II͒ complex, via hydrogen reduction were studied. A flow-type reaction system was employed to control each deposition parameter independently and at a constant value. Apparent activation energies for Cu growth were determined for a temperature range of 200-260°C as a function of hydrogen concentration. The determined values varied from 0.35 to 0.63 eV and decreased as hydrogen concentration increased. At a deposition temperature of 200°C, growth rate followed a Langmuir-type dependence against Cu͑dibm͒ 2 and hydrogen concentrations, showing first-order dependence at lower concentrations and zero-order dependence at higher concentrations. At a higher deposition temperature of 240°C, no saturation in the growth rate was observed. A Langmuir-Hinshelwood-type growth mechanism was discussed, and a rate equation for growth was proposed, taking into account the temperature dependence of both the rate constant of the rate-determining reaction and adsorption equilibrium constants. The hydrogen concentration dependence of the apparent activation energy for Cu growth was discussed with this rate equation

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