Abstract: Novel HfSiON thin films were prepared on p-type Si substrates by using radio-frequency magnetron sputtering deposition.Composition and structure of the films is determined by means of XPS and XRD respectively.High resolution scanning electron microscope(HRSEM) and atomic force microscope(AFM) have been empoled to observe the cross-section and the surface morphology of the thin films.XRD analyses show that the films are amorphous even after annealed at 900℃.The results of HRSEM and AFM present that the films have very flat surface,indicating a good thermal stability.HfSiON films have excellent dielectric properties with high dielectric constant k of about 18.9 and low leakage current of 2.5×10^-7 A/cm² at V_g of +1.5V. All the characteristics show that HfSiON films will be a promising candidate for SiO₂ gate dielectric and it also indicates that radio frequency magnetron sputtering is a good way to deposit HfSiON high-k thin films as dielectric.