HfO 2 is considered a promising gate dielectric material for sub-45 nm CMOS technology. It has been reported that incorporate Al into HfO 2 forming Hf aluminates in order to increase the crystallization temperature. However, the growth of the low-k interfacial layer at high-k/Si interface during high-k dielectric deposition would result in reliability degradation. Recently, incorporating nitrogen into HfAlO x gate dielectrics has beneficial effect on reliability performance. In addition, fluorine incorporation into high-k dielectrics also could have several improvements. In this study, dual plasma (CF 4 pre-treatment and N 2 post-treatment) was performed on HfAlO x MIS capacitor in order to improve interface quality and the reliability properties. According to our experimental results, dual plasma treatment could improve interface quality and enhance reliability properties of HfAlO x thin films.