Fluorine incorporation into the HfO 2 gate dielectrics by post CF 4 plasma treatment in an inductively coupled plasma chamber was proposed to improve gate leakage current and modify surface property for low-temperature fabrication. During the whole process, the temperature is controlled below 150°C. The low-leakage HfO 2 dielectric treated by CF 4 plasma was characterized and then utilized in pentacene-based OTFTs. After CF 4 plasma treatment, the gate leakage and field effect mobility were effectively improved. By integrating high-k HfO 2 by CF 4 plasma treatment and HMDS evaporation treatment, a low operating voltage (-4V), low threshold voltage (-1.12V), a low subthreshold swing (266 mV/decade), a field-effect mobility (0.029cm 2/Vs) and an on/off current ratio (>10 4) were obtained.