The thermal stability and interfacial structure characteristics for HfO2 dielectrics formed on Si substrates by plasma oxidation of sputtered metallic Hf films were investigated. The sputtered Hf metallic films were annealed under oxygen and nitrogen atmospheres. The structural characteristics and surface morphology of the Hf/HfO2 layers at varies of postannealing temperatures (from 600degreesC to 900degreesC) were examined by X-ray diffraction and scanning electron microscopy. The structure of the formed HfO2 films undergo a transformation of tetragonal to monoclinic phase with increase of the annealing temperature and demonstrated a polycrystalline structure at high temperature annealing. The growth and properties of the interfacial SiO2 layers formed at the HfO2/Si interface were observed by using fourier transform infrared spectroscopy. It has been found that formation of the interfacial layer depends on the postdeposition annealing temperature. N-2-annealed HfO2 films will lead to the decomposition of interfacial SiO2 layer and bring about the slight shift of Si-O-Si bonds vibration peak position toward lower wave numbers. (C) 2004 Elsevier B.V. All rights reserved.