In this paper the supercritical carbon dioxide (SCCO2) fluid technology is employed to improve the quality of E-gun evaporation deposited silicon oxide (SiOx) film at 150 degrees C. After the treatment of SCCO2 fluid mixed with ethyl alcohol and pure H2O, the oxygen content of SiOx film increases and the traps within SiOx are terminated by forming Si-O-Si feature bonds. The leakage current density reduces from 10(-2) to 3x10(-8) A/cm(2) at an electric field of 3 MV/cm due to the passivation of traps, and the hysteresis effect in the capacitance-voltage curve is eliminated.