Abstract: Zirconium oxide thin films as high-k gate dielectrics were deposited in vacuum cathodic arc method under different positively biased voltage.The phase structure and surface morphology were studied by means of X-ray diffraction (XRD) and atomic force microscope (AFM) , the hardness and modulus were determined by means of nanoindentation, and the influence of annealing on the thin films was also studied.The results show that the morphology of ZrO₂ was characterized by microcrystalline or amorphous under different positively biased voltage, the roughness of the films decreased with positively biased voltage increased, the maxima value of their hardness and modulus are 16.1 GPa and 210 GPa respectively in the case of the positively biased voltage 100V.