Surface Reaction Mechanisms during Plasma-Assisted Atomic Layer Deposition of Titanium Dioxide

We have investigated the surface reaction mechanisms during the O 2 -plasma-assisted atomic layer deposition (ALD) of TiO 2 from titanium tetraisopropoxide using in situ attenuated total reflection Fourier transform infrared spectroscopy. We show that the reaction mechanism involves a combination of O 3 - and H 2 O-based ALD chemistries, where both metal carbonates and surface hydroxyl groups are the reactive site for chemisorption of the metal precursor. The TiO 2 films have anatase crystal structure at 150 °C with a growth per cycle of ∼0.83 Å, which is much higher than that for amorphous films.