Atomic layer deposition of titanium dioxide from TiCl4 and H2O: investigation of growth mechanism

Atomic layer deposition (ALD) of titanium dioxide from TiCl4 and H2O was studied at substrate temperatures of 100± 4008C. Using a real-time quartz crystal microbalance method, it was demonstrated that although the surface reactions were self-limited, the growth rate depended on the temperature and development of the thin ®lm structure. Relatively low growth rate which was obtained in the TiCl4/H2O ALD process, was found to be a result of a signi®cant chlorine amount adsorbed during the TiCl4 pulse. Surface intermediates formed in the initial stage of TiCl4 adsorption were unstable and weakly bonded to the surface. Desorption and decomposition of these species additionally in¯uenced the deposition rate and, especially, its dependence on the precursor pulse times. # 2001 Elsevier Science B.V. All rights reserved