Suppression of substrate oxidation during ozone based atomic layer deposition of Al2O3: Effect of ozone flow rate

We demonstrate that interfacial SiO2, usually formed during high-κ oxide growth on silicon using ozone (O3), is suppressed during Al2O3 atomic layer deposition (ALD) by decreasing the O3 flow rate. First-principles calculations indicate that oxygen introduced by the first low-dose O3 exposure is inserted into the surface nucleation layer rather than the Si lattice. Subsequent Al2O3 deposition further passivates the surface against substrate oxidation. Aluminum methoxy [–Al(OCH3)2] and surface Al–O–Al linkages formed after O3 pulses are suggested as the reaction sites for trimethylaluminum during ALD of Al2O3.