Characterization of HfO xN y gate dielectrics using a hafnium oxide as target

Hafnium oxynitride (HfO xN y) gate dielectric has been deposited on Si (1 0 0) by means of radio frequency (rf) reactive sputtering using directly a HfO2 target in N2/Ar ambient. The thermal stability and microstructural characteristics for the HfO xN y films have been investigated. XPS results confirmed that nitrogen was successfully incorporated into the HfO2 films. XRD analyses showed that the HfO xN y films remain amorphous after 800 deg. C annealing in N2 ambient. Meanwhile the HfO xN y films can also effectively suppress oxygen diffusion during high temperature annealing and prevent interface layer from forming between HfO xN y films and Si substrates. AFM measurements demonstrated that surface roughness of the HfO xN y films increase slightly as compared to those pure HfO2 films after post deposition annealing. By virtue of building reasonable model structure, the optical properties of the HfO xN y films have been discussed in detail