The purpose of this work was to compare the structural and electrical properties of magnetron sputtered hafnium oxide (HfOx) and hafnium oxynitride (HfOxNy) thin films. A careful analysis of the influence of deposition process parameters, among them: pressure in the reactor chamber, Ar and O-2 flow rate, power applied to the reactor chamber and deposition time, on electro-physical properties of HfOx and HfOxNy layers has been performed. In the course of this work we performed number of experiments by means of Taguchi's orthogonal arrays approach. Such a method allowed for the determination of dielectric layers properties depending on process parameters with relatively low amount of experiments. Moreover, the effects of post-deposition annealing on electrical characteristics of metal-insulator-semiconductor (MIS) structures with HfOx or HfOxNy gate dielectric and its structural properties have also been reported. Investigated hafnia thin films were characterized by means of spectroscopic ellipsometry (SE), electrical characteristics measurements, atomic force microscopy (AFM), X-ray diffraction spectroscopy (XRD) and Rutherford backscattering spectrometry (RBS). (C) 2014 Elsevier B.V. All rights reserved.