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

Gas-phase FT-IR spectroscopy has been employed to study the thermal decompo sition of dialkylacetylacetonate aluminium (alkyl = metyl, ethyl and iso-bu thyl) in a hot-wall LP-MOCVD (tow-pressure metal organic chemical vapour de position) system. On the basis of such preliminary data, growths of alumina have been carried out using methyl- and ethyl derivatives in a sg,read ran ge of experimental conditions: reactor temperature 400-520 degrees C and to tal pressure 100-400 Pa. Aluminium oxide films have been grown in a nitroge n atmosphere either in the presence of oxygen or water vapour. In both case s die obtained films are amorphous, smooth and well adherent, but they are black in the first case, transparent and slightly yellowish in the second o ne. A simple theoretical kinetic model was applied to analyse and rationali se the experimental data related to the diethylacetylacetonate aluminium pr ecursor. The model well predicts the deposition rates attributed to the rat e determining step of the heterogeneous process with an activation energy o f 97 kJ mol(-1) in the presence of oxygen, and 49 kJ mol(-1) in the presenc e of water vapour.