Ultrasonic atomization of titanium isopropoxide at room temperature for TiO2 atomic layer deposition

Room temperature evaporation of titanium isopropoxide [Ti[OCH(CH3)2]4, TTIP] precursor was performed using ultrasonic atomization for TiO2 atomic layer deposition (ALD). Quartz crystal microbalance data show comparable results between room temperature TTIP ultrasonic atomization and conventional thermal evaporation. The TiO2 ALD saturation window is established for room temperature atomized TTIP exposure time and reactor temperatures. Room temperature atomized TTIP grown TiO2 films show smooth surface morphology before/after the annealing treatment. Two-dimensional TiO2 film thickness mappings on a 150 mm diameter Si(100) wafer were performed by spectroscopic ellipsometry. The thickness variation of TiO2 films by the room temperature atomized TTIP is less uniform than that of TiO2 films by thermally evaporated TTIP, probably due to the incomplete evaporation of the TTIP liquid droplets, which is more difficult to transport than its vapor.