Al2O3 thin films from aluminum dimethylisopropoxide by metal-organic chemical vapour deposition

This paper focuses on the use of aluminium dimethylisopropoxide as a novel precursor for the chemical vapour deposition of alumina thin films. The fragmentation pattern of this compound was studied by mass spectrometry, while its volatility and decomposition route were analysed by in-line FT-IR spectroscopy. Aluminium oxide films were grown in the temperature range 540±600°C at a total pressure of 100 Pa in a nitrogen±oxygen atmosphere. A kinetic model was developed which includes an overall heterogeneous reaction and a parasitic one in the gas phase with apparent activation energies of 130 kJxmol-1 and 209 kJxmol-1 respectively. The microstructure, composition and morphology of the obtained layers were analysed respectively by X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy. The aluminium oxide films obtained were transparent, amorphous, stoichiometric, carbon-free and smooth. An island growth was proposed. Uniform growth rates along the reactor of 16, 32 and 57 nm min-1 are found at deposition temperatures in the range of 560±570°C, at precursor evaporation temperatures of 15, 25 and 35°C respectively.