CVD of Tantalum Oxide Dielectric Thin Films for Nanoscale Device Applications

Abstract

A metallorganic chemical vapor deposition (MOCVD) process has been developed for the growth of films from the reaction of tantalum penta-ethoxide and oxygen in a 200 mm wafer tool platform. An optimized process was identified by performing a systematic study of the reaction-rate-limiting steps as a function of substrate temperature, partial pressure, and partial pressure. Subsequent chemical and microstructural analyses showed that as-deposited films were stoichiometric, amorphous, pure, and exhibited a smooth surface morphology. Carbon contamination was below the detection limits of the analytical techniques employed (<1 atom %). Typical as-deposited film dielectric constant and leakage current density were measured to be 27 and (at 1 V), respectively. Annealing at 650°C for 30 min in decreased both the dielectric constant and leakage current, while a similar anneal in Ar resulted in increased dielectric constant and associated decrease in leakage current. It was determined that Schottky emission was the dominant leakage current conduction mechanism in the MOCVD films. © 2004 The Electrochemical Society. All rights reserved.