Role of surface intermediates in enhanced, uniform growth rates of TiO2 atomic layer deposition thin films using titanium tetraisopropoxide and ozone

Atomic layer deposition (ALD) growth of TiO2 thin films from titanium tetraisopropoxide (TTIP) and ozone has been studied as a function of dose and purge recipes. A novel dosing scheme was designed to introduce the TTIP precursor into the reaction chamber in multiple "mu pulses" with or without delay times for desorption of surface product species, analogous to conventional ALD purge cycles. Larger doses led to significantly higher growth rates while maintaining excellent uniformity across 100 mm wafers, effects which underscore the importance of surface residence times in rather complex surface reaction pathways. The production of H2O/OH surface species during the TTIP half-cycle is intrinsic to the reaction, leading to secondary reaction mechanisms and believed responsible for the enhanced growth rates and accompanying high uniformity. (C) 2012 American Vacuum Society. [DOI: 10.1116/1.3669522]