Effect of sputtering condition on the surface properties of silicon oxide thin films prepared for liquid crystal alignment layers

SiO_x thin films are widely used for the LC alignment layer for LCoS devices due to the thermal and photochemical stability of SiO_x. In this work, the relationship between the sputtering condition and the LC alignment properties of SiO_x thin films was studied. The physical and chemical properties of SiO_x thin films were closely related with the RF power and the working pressure of RF-magnetron sputtering. The surface energy of SiO_x thin films was mainly connected with the chemical composition of the SiO_x thin films and the behavior of LC molecules on the SiO_x thin films was dominantly affected by the surface energy. The azimuthal anchoring energy and the pretilt angle of LC molecules were changed by modifying the amount of oxygen atom in the SiO_x thin films. By controlling the sputtering condition of SiO_x thin films, it was possible to control the orientation of LC molecules on the SiO_x thin films.