Al2O3 growth optimisation using aluminium dimethylisopropoxyde as precursor as a function of reaction conditions and reacting gases

Aluminum oxide films were grown in a hot-wall low-pressure metal organic chemical vapor deposition (MOCVD) system using aluminum dimethylisopropoxide as precursor. Experimental reaction conditions and the reacting gas (O2, H2O, N2O) have been systematically varied with the aim to decrease the deposition temperature and obtain transparent, dense and carbon-free films. Changes in the gas phase composition were studied by FT-IR spectroscopy using an in-line cell. The reactor temperature ranged fiom 230°C to 380°C. The microstructure of the films was investigated by X-ray Diffraction, while the surface chemical composition was studied by X-ray Photoelectron Spectroscopy. Atomic Force Microscopy was employed to analyze the surface morphology of the films as a function of reaction conditions and reacting gases. The best performances have been obtained using dry oxygen at 1000 Pa and oxygen mixed with water vapor at 100 Pa. High growth rates such as 140 nm min-1 have been obtained at 270 OC in the latter case. Different reaction mechanisms have been proposed in the two cases.