Nitridation of hafnium oxide by reactive sputtering

Hafnium oxide films were RF sputtered from HfO2 target in Ar/O2 or Ar/N2 ambient on silicon substrates. The composition of the deposited films was analyzed by X-ray photoelectron spectroscopy (XPS). For samples sputtered in Ar/N2, it was observed that nitrogen was incorporated in the bulk of hafnium oxide films in the form of HfON, and SiON layer was formed at the silicon–insulator interface. After annealing the hafnium oxide films at 600–700 °C, MOS structures were fabricated and used for electrical characterization. The effects of nitridation of hafnium oxide on both the capacitance–voltage and current–voltage characteristics of the MOS capacitors were discussed.