Electrical characteristics of anodic tantalum pentoxide thin films under thermal stress

In this work, we report on electrical characteristics of tantalum oxide films fabricated by anodic oxidation of tantalum nitride and tantalum silicide with thicknesses ranging from 100 to 4500 Angstrom. These films exhibit greatly improved leakage currents, breakdown voltage and a very low defect density, thus allowing the fabrication of large area capacitors. Leakage currents in the insulator under thermal stress have been carefully studied in order to determine the nature and physical origin of the dominant conduction mechanisms in the insulator. We have found noticeable differences in the dominant conduction mechanisms for thin and thick anodic tantalum pentoxide films. These differences are explained in terms of the thickness dependence of the insulator layer structure. (C) 2000 Elsevier Science Ltd. All rights reserved.