Kinetic study of alcohol-assisted supercritical fluid deposition of TiO2

The kinetics of TiO2 thin-film deposition in a supercritical CO2/alcohol environment was studied using titanium di(isopropoxide)bis(tetramethylhexanedionate) [Ti(O-i-Pr)2(tmhd)2] as the precursor. The solvent effects of methanol, ethanol, and isopropanol on the supercritical fluid deposition (SCFD) of TiO2 were examined at deposition temperatures of 150-300 °C. Methanol was the most effective of the three alcohols evaluated; it enhanced the TiO2-SCFD deposition rate 2-3-fold and decreased the activation energy from 49 ± 4 to 28 ± 3 kJ/mol. Conformal deposition of TiO2 on a deep trench (aspect ratio of 30) was demonstrated at a growth rate of > 2 nm/min.