Suppression of substrate oxidation during ozone based atomic layer deposition of Al_2O_3: Effect of ozone flow rate

摘要

We demonstrate that interfacial SiO_2, usually formed during high-k oxide growth on silicon using ozone (O_3), is suppressed during Al_2O_3 atomic layer deposition (ALD) by decreasing the O_3 flow rate. First-principles calculations indicate that oxygen introduced by the first low-dose O_3 exposure is inserted into the surface nucleation layer rather than the Si lattice. Subsequent Al_2O_3 deposition further passivates the surface against substrate oxidation. Aluminum methoxy [-Al(OCH_3)_2] and surface Al-O-A1 linkages formed after O_3 pulses are suggested as the reaction sites for trimethylaluminum during ALD of Al_2O_3.