Physical characterization of thin ALD–Al2O3 films

Aluminum oxide was deposited using atomic layer deposition on either a silicon oxide or a silicon nitride interface. Water vapor or ozone were used as oxidation precursors. The structural properties of these films were investigated by time-of-flight secondary-ion-mass-spectroscopy (ToF-SIMS), X-ray photoelectron spectroscopy (XPS) and elastic recoil detection (ERD). Special attention was given to contamination issues of the film and the interface, bonding conditions and temperature influence on diffusion. The results suggest that the silicon most likely diffused along grain boundaries of polycrystalline Al2O3. Carbon and hydrogen were located at the interface and furthermore hydrogen diffused out of the film to some extent due to anneal. Carbon content in the layer was reduced when using O3 as an oxidant. The formation of metallic aluminum clusters was not observed for any of the investigated process conditions.