Micropatterning of non-crystalline methylsilsesquioxane-titania hybrid films based on their structural changes with UV irradiation

Non-crystalline, transparent methylsilsesquioxane–titania hybrid films for application in micropatterning were prepared from methyltriethoxysilane and titanium tetrabutoxide by the sol–gel method. The hybrid films were heat-treated at 100 8C for 1 h and then irradiated with UV light using an ultrahighpressure mercury lamp. The refractive index of the film increased as the amount of incorporated TiO2 increased. No changes in hardness were observed for the films lacking TiO2 during UV irradiation, whereas adding a small amount of TiO2 caused the hardness to increase significantly following UV irradiation. These changes in the physical properties of the films with UV irradiation were caused by the cleavage of Si–C bonds in the films induced by the photocatalytic effect of TiO2. On the basis of the changes in surface profiles, and optical, chemical, and mechanical properties induced by UV irradiation, it is concluded that the methylsilsesquioxane–titania films are promising for micropatterning by photolithography.