Alumina thin films prepared by direct liquid injection chemical vapor deposition of dimethylaluminum isopropoxide: a process-structure investigation
The development of a new process to obtain amorphous alumina thin films is presented. We show for the first time the direct liquid injection chemical vapor deposition (DLI CVD) of alumina thin films using dimethylaluminum isopropoxide (DMAI) precursor in two oxidizing atmospheres. At high process temperature (500-700 °C), the film growth takes place in the presence of O2 whereas at low temperature (150-300 °C) H2O vapor is used. The materials characteristics, such as the surface morphology and roughness (SEM and AFM), crystal structure (XRD), composition (EPMA) and chemistry (XPS) are discussed in detail. Very smooth films, with typical roughness values lower than 2.0 nm are obtained. The thin films are all composed of an amorphous material with varying composition. Supported by both EPMA and XPS results, film composition evolves from a partial oxyhydroxide to a stoichiometric oxide at low deposition temperature (150-300 °C) in the presence of H2O. At higher growth temperature (500-700 °C) in the presence of O2, the composition changes from that of a stoichiometric oxide to a mixture of an oxide with aluminum carbide. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)