Electrical Properties of HfO₂Thin Insulating Film Prepared by Anodic Oxidation

Abstract

Polycrystalline HfO2 thin film capacitors were prepared by anodizing sputter-deposited Hf films, and their capacitor and leakage current properties were studied. Electrical measurements were performed for the parallel-plate Hf anodized capacitors with an Al–HfO2–Hf (metal–insulator–metal) structure, and high capacitance density (0.6 µF/cm2) and low dielectric loss (0.0095) were obtained for a very thin-oxide capacitor anodized at 10 V. In addition, the leakage current density of this capacitor was about 5 ×10-9 A/cm2 at an applied voltage of 5 V. The leakage current density (J) of HfO2 capacitors as a function of applied electric field (E) was investigated for several capacitors with different oxide thicknesses, by plotting ln (J) vs E1/2 curves. As a result, it was revealed that the conduction mechanism is due to Schottky emission, irrespective of the oxide thickness.