Gas-phase FT-IR analysis and growth kinetics of Al₂O₃ in a LP-MOCVD reactor using new dialkylacetylacetonate precursors

Abstract
Gas-phase FT-IR spectroscopy has been employed to study the thermal decomposition of dialkylacetylacetonate aluminium (alkyl = metyl, ethyl and iso-buthyl) in a hot-wall LP-MOCVD (low-pressure metal organic chemical vapour deposition) system. On the basis of such preliminary data, growths of alumina have been carried out using methyl- and ethyl derivatives in a spread range of experimental conditions : reactor temperature 400-520 °C and total pressure 100-400 Pa. Aluminium oxide films have been grown in a nitrogen atmosphere either in the presence of oxygen or water vapour. In both cases the obtained films are amorphous, smooth and well adherent, but they are black in the first case, transparent and slightly yellowish in the second one. A simple theoretical kinetic model was applied to analyse and rationalise the experimental data related to the diethylacetylacetonate aluminium precursor. The model well predicts the deposition rates attributed to the rate determining step of the heterogeneous process with an activation energy of 97 kJ mol^-1 in the presence of oxygen, and 49 kJ mol^-1 in the presence of water vapour.