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

J Kwon, M Dai, Mathew D Halls, YJ Chabal
Applied Physics Letters 97, 162903 (2010)

We demonstrate that interfacial SiO₂, usually formed during high-k 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 [–Al₂OCH₃)₂] and surface Al–O–Al linkages formed after O₃ pulses are suggested as the reaction sites for trimethylaluminum during ALD of Al₂O₃.