Paper TF+AS+EM+NS+SS-ThM12
TiO₂ Film Crystallization by Post-Deposition Annealing

Thursday, October 31, 2013, 11:40 am, Room 104 A

Optical and electrical properties of TiO₂ thin films are largely effected by film morphology. TiO₂ usually crystallizes into anatase or rutile phase. The rutile phase is generally stable while the anatase phase is difficult to produce in pure form through annealing. TiO₂ thin films were grown by atomic layer deposition (ALD) on Si (100) surfaces using tetrakis(dimethylamino) titanium (TDMAT) and H₂O. Films were grown at every 50°C increment from 100 to 300°C approximately 100 nm thick, determined by nominal growth rates derived from spectroscopic ellipsometry (SE) measurements. The growth rate varied from 0.4Å/cycle at the ALD optimal temperature of 200°C to 1.2Å/cycle at 300°C. Films were annealed post-deposition at temperatures of 500°C, 700°C and 900°C for 3, 5 and 10 minutes in an argon environment using a rapid thermal annealer. Characterization was completed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). FTIR measurements indicate that the as-deposited films have an amorphous structure. Annealed films exhibit various crystallization to rutile phase, anatase phase, or a mixture of the two phases, depending on the deposition and post-deposition annealing conditions, as confirmed by XRD. Specifically, TiO₂ films grown at 100°C and annealed for 10 minutes at 900°C exhibit only amorphous and anatase phase TiO₂. It is shown that TiO₂ crystallinity can be tuned between amorphous, anatase and rutile phases by controlling the deposition temperature and post-deposition annealing parameters.