Kinetic study of alcohol-assisted supercritical fluid deposition of TiO2

Abstract The kinetics of TiO 2 thin-film deposition in a supercritical CO 2 /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 TiO 2 were examined at deposition temperatures of 150–300 °C. Methanol was the most effective of the three alcohols evaluated; it enhanced the TiO 2 -SCFD deposition rate 2–3-fold and decreased the activation energy from 49 ± 4 to 28 ± 3 kJ/mol. Conformal deposition of TiO 2 on a deep trench (aspect ratio of 30) was demonstrated at a growth rate of > 2 nm/min.