Effect of post-deposition annealing on the structural and electrical properties of RF sputtered hafnium oxide thin films

Hafnium oxide films were deposited on silicon substrates by RF sputtering at room temperature. Post-deposition rapid thermal annealing of the sputtered HfO₂ films was carried out in the temperature range of 400°C to 800°C in oxygen ambient. The structural properties ware studied by X-ray diffraction (XRD), where the enhancement in the crystallinity of HfO₂ (1¯11) orientation was observed. The Capacitance —Voltage (C-V) and Current density —Voltage (J-V) characteristics of the annealed dielectric film were investigated employing Al/HfO₂/Si Metal Oxide Semiconductor (MOS) capacitor structure. The flatband voltage (V_fb) and oxide charge density (Q_ox) were extracted from the high frequency (1 MHz) C-V curve. Leakage current was found to be minimum for the annealing temperature of 600°C. (paper)