| Abstract
| - The atomic layer deposition (ALD) of TiO2 from TiCl4 and D2O at 150−400 °C was studiedin situ with a quadrupole mass spectrometer (QMS) and a quartz crystal microbalance (QCM).The ALD growth proceeds via exchange reactions on the film surface. In the first step, TiCl4is introduced on a surface covered with −OD groups which then become replaced with −O−TiClx species, and DCl is released as a volatile byproduct. In the second step, the incomingD2O reacts with the surface −Cl atoms replacing them with −OD groups and, again, DCl isreleased. When the temperature is increased from 150 to 250 °C, the number of −Cl ligandsreleased during the TiCl4 pulse decreases from about two to one. At temperatures higherthan 250 °C, less than one −Cl ligand is released, indicating molecular adsorption of TiCl4.
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