Lithium niobate ($LiNbO_3$) thin films were fabricated using the sol-gel spin coating method. The effects of variables in the sol-gel processing, such as refluxing time, reaction temperature and substrate, were investigated on the crystallinity and the epitaxy of the thin film. The film made of the solution refluxed for 5 hrs and deposited on sapphire (012) substrate showed preferred orientation at the reaction temperature of 500℃. The film had homogeneous and pore-free microstructure. The film fabricated from the solution refluxed for 1 hr had less crystallinity and porous microstructure at the same processing condition. The thin films deposited on MgO (100) and Si (111) substrates were polycrystalline. the reaction temperature and the film thickness significantly affected on the crystallinity and the epitaxy of the film. The surface microstructures of the films were observed. The optical and the electrical properties of the thin films fabricated on different substrates were measured.
