Thin tunneling oxides grown on a CF 4 pretreated silicon substrate were prepared and investigated for the first time. The tunneling current of the CF 4 -treated oxide is about three orders of magnitude higher than that of thermal oxide; furthermore, the stressinduced anomalous current and low electric field leakage current were greatly suppressed. The improvement was attributed to the incorporation of fluorine in the oxide region. Both control and CF 4 -treated devices exhibited comparable channel mobility. However, pretreatment with CF 4 markedly improved the reliability of the insulator. This oxide is highly promising for fabricating low-voltage electrically erasable and programmable read-only memories ͑EEPROMs͒ without increasing the complexity of the process.