Metalorganic chemical vapor deposition of aluminum oxide on silicon nitride

Thin films of aluminum oxide were deposited on silicon nitride thin films using trimethylaluminum and oxygen at 0.5 Torr and 300 degreesC. Fourier transform infrared (FTIR) and x-ray photoelectron spectroscopic (XPS) analyses of these films showed no aluminum silicate phase at the film-substrate interface. The O/Al ratio in the deposited film was found to be higher than that in stoichiometric Al2O3 indicating the presence of excess oxygen. FTIR spectroscopy and XPS of the annealed samples did not show any formation of silicon oxide, oxynitride or silicate at the aluminum oxide/silicon nitride interface. In contrast to aluminum oxide on clean silicon substrates, using ultrathin silicon nitride as a barrier layer could prevent excess Oxygen migration towards the Si substrate and formation of any interfacial layers.