The structural and interfacial properties of HfO 2/Si by the plasma oxidation of sputtered metallic Hf thin films

Abstract

The thermal stability and interfacial structure characteristics for HfO 2 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/HfO 2 layers at varies of postannealing temperatures (from 600°C to 900°C) were examined by X-ray diffraction and scanning electron microscopy. The structure of the formed HfO 2 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 SiO 2 layers formed at the HfO 2/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 HfO 2 films will lead to the decomposition of interfacial SiO 2 layer and bring about the slight shift of Si–O–Si bonds vibration peak position toward lower wave numbers.