Impact of post deposition annealing in N₂ ambient on structural properties of nanocrystalline hafnium oxide thin film

HfO₂ thin films (100 nm) has been deposited by sputtering technique and further annealed at various temperatures ranges from 400 to 1000 °C with increment of 200 °C in N₂ ambient for 10 min. The samples have been characterized using XRD, FTIR, EDX, AFM and Laser Ellipsometry. Structural properties of thin film such as crystallite size, phase, orientation and stress have significantly influenced by process parameters viz., annealing temperature as well as by ambient conditions. The electrical properties of thin films have strong dependence on the arrangement of atoms. AFM data shows the size of nanoparticles increase with annealing temperature i.e. 38–53 nm. Due to post deposition annealing treatment in N₂ ambient, the structural properties i.e. crystal size as well as stress and the electrical properties viz., refractive index at 632 nm wavelength, roughness are highly influenced. For better quality of thin film, it is desired to have a close match of interplanar spacing with standard International Centre for Diffraction Data so that film can deposit without lattice mismatch. Due to close match of interplanar spacing in N₂ ambient in comparison to O₂ ambient, it is concluded that HfO₂ thin film annealed in N₂ ambient shows better structural properties as well as electrical properties.