Reduction of oxide and interface charge density of reactive sputtered HfO2 thin films by rapid thermal annealing

Abstract

Hafnium oxide ceramic thin films were deposited on silicon substrates by RF magnetron reactive sputtering at room temperature. Post-deposition rapid thermal annealing of the sputtered HfO2 films was carried out with the variation in process duration in oxygen ambient. The structural properties were studied by X-ray diffraction technique, where an enhancement in the crystallinity of HfO2 (111) orientation was observed with annealing durations. The capacitance–voltage (C–V) and current density–voltage (J–V) characteristics of the annealed ceramic films were investigated using Al/HfO2/Si metal oxide semiconductor capacitor structure. The flatband voltage (Vfb) and oxide charge density (Qox) were extracted from the high frequency (1 MHz) C–V curve. The interface charge density (Dit) and leakage current density were found to be minimum for RTA treatment at 600 °C for 135 sec, which is due to the decrease in dangling bonds at the HfO2/Si interface.