Novel titanium compounds for metal-organic chemical vapor deposition of titanium dioxide films with an ultrahigh deposition rate

Abstract

A new titanium diolate compound Ti(mpd)(mdop)(2) (1) containing a beta-ketoester and a dimeric derivative [Ti(mpd)(mdop)(mu-OMe)](2) [2; mpd = 2-methyl-2,4-pentanediolate, mdop = (CH3)(3)CC(O)C-HCOOCH3] have been synthesized and characterized by FT-IR, H-1 NMR, C-13 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 280degreesC. 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(OPr')(2)(tmhd)(2), the new titanium complexes demonstrated a much higher deposition rate of TiO2 film growth (3-6 times) at 400-475degreesC. 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) Angstrom, b = 13.817(4) Angstrom, c = 11.157(3) Angstrom, beta = 101.059-(5)degrees, monoclinic, space group P2(1)/c, Z = 2.