Effect of thermal treatment on the band offsets and interfacial properties of HfOxNy gate dielectrics

Band offsets and interfacial properties of HfOxNy films grown on Si(100) through radio-frequency reactive magnetron sputtering were investigated by x-ray photoelectron spectroscopy. The changes in the conduction band offset, the valence band offset, as well as in the interfacial properties were obtained as a function of the annealing temperature. The interfacial layer is unavoidably formed for the deposited films and the composition of the interfacial layer is most likely Hf-silicate and SiOx. With the increase in the annealing temperature, it is confirmed that the reaction between SiOx and HfOxNy films formed more Hf-silicate interfacial layer. The valence band offset (Delta E-v) shifts upwards gradually with the increase in annealing temperature due to the decrease in N elements. After thermal treatment, the obtained conduction band offset (Delta E-c) increased from 1.20 eV at 500 degrees C to 1.25 eV at 800 degrees C.