Thin tunneling oxides grown on a CF4 pretreated silicon substrate were prepared and investigated for the first time. The tunneling current of the CF4-treated oxide is about three orders of magnitude higher than that of thermal oxide; furthermore, the stress-induced 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 CF4-treated devices exhibited comparable channel mobility. However, pretreatment with CF4 markedly improved the reliability of the insulator. This oxide is highly promising for fabricating low-voltage electrically erasable and programmable read-only memories (EEPROMs) without increasing the complexity of the process.