Abstract: The infrared spectrum of the reaotively E. F. sputtered SiO₂ film ig studied in the present work and it has been discovered that the reaction of Si with oxygen during the sputtering is not complete. This might canse higher density of interfaoial states between Si and the sputtered SiO₂. In order to improve the characteristics of the interface, the SiO₂ film sputtered on the Si wafer is oxidized and annealed in an ambient of nitrogen contained CCl₄ at 950℃. As a result, the characteristics of the interface are greatly improved and the interface state density is reduced to 5.3×10¹⁰/cm². v for the ntype silicon wafer with (100) orientation. MOS transistors can be made using this kind of SiO₂ film as the gate.