Kinetic study of alcohol-assisted supercritical fluid deposition of TiO2

Abstract

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±3kJ/mol. Conformal deposition of TiO2 on a deep trench (aspect ratio of 30) was demonstrated at a growth rate of >2nm/min.