Novel Titanium Compounds for Metal−Organic Chemical Vapor Deposition of Titanium Dioxide Films with an Ultrahigh Deposition Rate

A new titanium diolate compound Ti(mpd)(mdop)2 (1) containing a β-ketoester and a dimeric derivative [Ti(mpd)(mdop)(μ-OMe)]2 [2; mpd = 2-methyl-2,4-pentanediolate, mdop = (CH3)3CC(O)C-HCOOCH3] have been synthesized
and characterized by FT-IR, 1H NMR, 13C NMR, mass spectroscopy, and elemental analysis. Complex 2 was
further characterized by X-ray structural analysis. Both 1 and 2 are fairly stable in air and in solvents such as
tetrahydrofuran and toluene. They are also thermally stable and do not leave any residue during flash evaporation
at around 280 °C. The new titanium complexes were used as precursors for the deposition of TiO2 thin films by
liquid-source metal−organic chemical vapor deposition. Compared with commercial Ti precursors, such as Ti(mpd)(tmhd)2 (tmhd = 2,2,6,6-tetramethylheptanedionate) and Ti(OPri)2(tmhd)2, the new titanium complexes
demonstrated a much higher deposition rate of TiO2 film growth (3−6 times) at 400−475 °C. The deposited TiO2
film from complex 2 was found to be in a crystalline anatase phase with a smooth surface morphology and low
carbon content. Crystal data for 2:  233(2) K, a = 12.570(4) Å, b = 13.817(4) Å, c = 11.157(3) Å, β = 101.059(5)°, monoclinic, space group P21/c, Z = 2.