Microstructure and Electrical Properties of Tantalum Oxide Thin Film Prepared by Electron Cyclotron Resonance Plasma-Enhanced Chemical Vapor Deposition

High-quality tantalum oxide thin film was prepared by electron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR PECVD) for high-density memory devices. The tantalum oxide film deposited at 205°C showed excellent electrical properties: E bd = 4.4 MV/cm, ε (Ta 2 O 5 )=25 and J < 1×10 -9 A/cm 2 at 2.5 V. The deposited film was annealed at various temperatures in an oxygen ambient. The microstructure and the composition of the annealed tantalum oxide film were examined and they were related to the electrical properties of the film. The growth of the interfacial silicon oxide layer was observed by using a high-resolution transmission electron microscope (TEM) and its effects on the electrical properties of the dielectric film were also studied. The electrical properties of the film could not be improved by annealing in an oxygen ambient at high temperatures due to the crystallization of the tantalum oxide film and the growth of the interfacial silicon oxide layer.