Adsorption and Self-limiting Mechanisms of Trimethylaluminum and Water on Aluminum Oxide Surface

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The adsorption processes of (CH3) 3Al (TMA) and H2O on γ-Al2O3 have been studied to obtain the basic data on the self-limiting mechanism in the atomic layer epitaxy (ALE). The reactant species, TMA and H2O, were transported onto heated Al2O3 surface with the hydrogen carrier gas. The adsorption rate, as a function of the surface coverage of aluminum or oxygen, was estimated from the reactant exposure-time dependence of the deposition thickness of γ-Al2O3. The aluminum and oxygen coverage dependence of the adsorption rate suggested that the TMA and H2O were adsorbed by a precursor-mediated mechanism. The ALE of γ-Al2O3 was investigated on the basis of the adsorption data. The self-limiting mechanism, which automatically stopped the growth at just one monolayer of γ-Al2O3 (001), was observed in the TMA and H2O exposure-duration dependences. A growth model of the γ-Al2O3 ALE successfully explained the growth rate.
2010-09-30