Trimethyl-aluminum and ozone interactions with graphite in atomic layer deposition of Al2O3

A study of the chemical interactions between the atomic layer deposition (ALD) Al2O3 precursors trimethlyaluminum (TMA) and ozone (TMA/O3) and sp2 carbon surfaces is presented. In-situ x-ray photoelectron spectroscopy is used to study these interactions, while ex-situ atomic force microscopy (AFM) is used to monitor the surface morphology. Ozone functionalization of the sp2 carbon surface is discussed and the dependence of TMA/O3 reactions over a range of ALD process conditions is examined. The utilization of a 6-cycle room temperature TMA/O3 ALD seed layer to nucleate the conformal growth of Al2O3 by TMA/H2O at 200 °C as well as the quality of such films is discussed. Two stages of ozone reactions are observed: first the ozone appears to remove adsorbed species from the graphite surface before reacting with the surface. The deposition of Al2O3 is found to be strongly dependant on the N2 purge time as well as the precursor pulse sequence. It is shown that the quality of these low temperature deposited films can easily be improved by removal of carbon containing species through an 300 °C anneal.