The influence of UV irradiation on the deposition of titania from titanium tetra-isopropoxide (TTIP) under reduced pressure was studied. It was found that UV irradiation accelerates the titania growth rate by a factor of 2-3 in the temperature range of 573 to 623 K. The coverage quality of micron-size trenches in the cases with and without UV irradiation indicates the role of the photo-enhanced surface reaction. The threshold wavelength of 380 nm which is equivalent to the energy gap of anatase indicates strongly that band-to-band excitation is responsible for the photo-enhanced surface reaction.