The superior characteristics of fluorinated HfO2 gate dielectrics were investigated. Fluorine was incorporated into HfO2 thin film by postdeposition CF4 plasma treatment to form fluorinated HfO2 gate dielectrics. Secondary-ion mass spectroscopy results showed that there was a significant incorporation of fluorine atoms at the TaN HfO2 and HfO2 Si interface. Improvement of the gate leakage current, breakdown voltage, capacitance-voltage hysteresis, and charge trapping characteristics was observed in the fluorinated HfO2 gate dielectrics, with no increase of interfacial layer thickness. A physical model is presented to explain the improvement of hysteresis and the elimination of charge trapping. These results indicate that the fluorinated HfO2 gate dielectrics appear to be useful technology for future ultrathin gate dielectrics.