Deposition of thin films in supercritical carbon dioxide

INOR 352

Theodosia Gougousi, gougousi@umbc.edu, Department of Physics, UMBC, 1000 Hilltop Circle, Baltimore, MD 21250
Metal oxide thin films have been deposited through a low- temperature synthetic avenue that is based on the reaction of metal organic precursors with organic and inorganic peroxides in supercritical carbon dioxide. The enhanced solvent ability of supercritical carbon dioxide is utilized for the delivery of large concentrations of reagents to the surface, and removal of the reaction by-products. Thin films deposited include: Y2O3, Al2O3, ZrO2 and TiO2 from Al(acac)3, Y(tmhd)3, OTi(tmhd)2, and Zr(acac)4 precursors and tert-butyl peroxide, di-tert-amyl peroxide and a 30% aqueous solution of hydrogen peroxide oxidizers. Thin film deposition rate and composition depends on the precursor, oxidizer and the process temperature (80-140 °C) and pressure (2100 to 3900 psi). Carbonate type impurities desorb after mild anneals. AFM shows smooth surface (rms roughness ~3% of film thickness) that improves upon inert anneals at 400°C. The low process temperature makes the technique attractive for depositions on temperature sensitive substrates.