Electrical characterization of the hafnium oxide prepared by direct sputtering of Hf in oxygen with rapid thermal annealing

Electrical characterization of the hafnium oxide (HfO₂) gate dielectric films prepared by Hf sputtering in oxygen was conducted. By measuring the current–voltage (I–V) characteristics at temperature ranging from 300 to 500 K, several abnormalities in the I–V characteristics are recorded. For temperatures below 400 K, the current–voltage characteristics in high field region can be plotted with the Fowler–Nordheim law but a stronger temperature dependence was observed. Large flatband voltage shifts in the Al/HfO₂/Si capacitor were observed. The capacitance–voltage characteristics and flatband shifts are found to depend strongly on the post-deposition annealing temperature and duration. To study the reliability against high electric field, constant voltage stressing on the samples was conducted. We found that the trap energy levels are shallow and the oxide traps can be readily filled and detrapped at a low bias voltage.