We have studied metalorganic chemical vapor deposition of $TiO_2$ thin films using titanium tetra-isopropoxide (TTIP) with pyridine and ammonia as a catalyst at deposition temperatures from 250 to 365℃. The $TiO_2$ films deposited by thermal decomposition of TTIP have anatase structure and the activation energy of the $TiO_2$ film growth rate is 152 kJ/mol. The pyridine and ammonia catalysts enhance the $TiO_2$ film growth rate because they reduce the activation energy of the film growth rate to 55 kJ/mol when the deposition temperature is below 310℃. The crystal structure of the $TiO_2$ films deposited using TTIP with pyridine catalyst is anatase structure, but the films deposited at the deposition temperature below 300℃ using TTIP with ammonia catalyst at has amorphous structure with fine TiO crystalline and with 11 at.% N impurity in the film. As the deposition temperature increases, the amount of N impurity decreases and the amount of anatase $TiO_2$ crystalline in the film increases. The as-deposited anatase $TiO_2$ films remain the anatase structure after performing a post-deposition anneal in oxygen ambient for 30 min at 750℃. However, the amorphous $TiO_2$ film with N impurity deposited at 270℃ using TTIP and ammonia catalyst transforms to pure rutile $TiO_2$ structure with very smooth surface roughness after performing the post-deposition anneal. A Pt/$TiO_2$/Si capacitor composed by the rutile $TiO_2$ film has a high dielectric constant of 82 and low leakage current, so that useful for capacitor of electrical devices.
