The thin silicon oxide (SiOx) films were deposited by using the facing target sputtering(FTS) apparatus for the thin film passivation application of OLEDs. The deposition system was investigated under various process conditions such as the array of cathode magnets, oxygen concentration[O-2/(Ar + O-2)] during deposition, distance between two targets, and working pressure. The optimum conditions for FTS apparatus for the deposition of thin silicon oxide films are as follows: distances between target and substrate (T-S) as well as two targets (T-T) are 90mm and 120mm, respectively. Dense structured SiOx film with maximum deposition rate is obtained under a gas pressure of 2 mTorr with an oxygen concentration of 3.3%. Under the optimum conditions, SiOx thin films were grown with deposition rate of 25nm/min by rf-power of 4.5 W/cm(2), which was remarkably enhanced as compared with a deposition rate(3-4nm/min) of conventional sputtering system. The SiOx thin film showed a very low water vapor transmission rate(WVTR) less than 3 x 10(-2) g/m(2)/day compared to the conventional sputtering system.