Effects of annealing on quality and stoichiometry of HfO2 thin films grown by RF magnetron sputtering

In this paper, the effects of annealing temperature on HfO2 thin films prepared by RF sputtering have been investigated. Thin films of hafnium oxide were deposited using sputtering onto p-type Si substrates and the pristine films were annealed at different temperatures in air atmosphere to obtain crystallinity. The Raman and XRD results of the as-deposited films show amorphous nature, whereas the annealed films at 600 °C results in crystallization. AFM was used to study the surface morphology of the films and to estimate the skewness, kurtosis and the roughness values. The core level orbitals of Hf 4f spectra of as-deposited films not only reveal the formation of hafnium rich hafnium oxide but also nearly stoichiometric composition of HfO2 and exhibit a shift in binding energy with annealing. Electrical measurements of the films suggest that the leakage current is increased for crystalline films as compared to the as-deposited ones. The effects of annealing temperature on quality and stoichiometry of hafnia thin films and their possible applications are reported.