Effect of N2O ratio on the crystallization temperature of ZrO2 film deposited on Si by reactive sputtering in Ar/O2/N2O plasma

Abstract

The effect of nitrous oxide ratios in the Ar/ O2/ N2O plasma on the ZrO2 films deposited on Si using dc magnetron reactive system is studied by differential scanning calorimetry (DSC) where the Ar:O2 ratio is fixed at 4:1. Further, grazing angle x-ray reflectivity (GIXRR), grazing angle x-ray diffraction (GIXRD) and atomic force microscopy (AFM) techniques are also employed to characterize the films. The DSC study shows an anomalous variation of the glass temperature when the N2O ratio in the Ar/O2/N2O plasma changes from 0.25 to 2 with respect to the control ZrO2 sample deposited without N2O. An increase in glass temperature by ∼70 °C is observed for the N2O ratio at 1. A further rise in N2O ratio results in the reduction of the glass temperature. The GIXRR study indicates that the thickness of the samples decreases with the increase in N2O ratios beyond 0.8. Further, increasing N2O ratio results in an increase in surface and interface roughness for the as-deposited samples. But both the roughnesses decrease upon annealing the samples above their respective crystallization temperatures. The AFM results also corroborates the observation. Moreover, the GIXRD study indicates the formation of Γ-Zr2ON2 along with the monoclinic and tetragonal ZrO2 at the highest ratio of N2O in the Ar:O2:N2O plasma.