Metallorganic Chemical Vapor Deposition of TaOx N y as a High-Dielectric-Constant Material for Next-Generation Devices

Abstract

Tantalum oxynitride films were deposited by metallorganic chemical vapor deposition. Pentaethoxytantalum the most widely used source gas for depositing was used as the source gas and as the reaction gas. The activation energy of the surface reaction was estimated to be 1.1 eV for a single-source deposition deposition), and to decrease to ca. 0.37 eV with the addition of over 50 sccm Deposition rate at the surface-reaction-controlled regime increased to 2.6 nm/min with 100 sccm but decreased upon adding more than 100 sccm of The overall deposition rate of the surface-reaction-controlled regime was as predicted by the Langmuir-Hinshelwood model. With an increase in both deposition temperature and flow rate, the TaON phase predominated over The dielectric constants of the as-deposited and -annealed films were 51 and 146, respectively. It is believed that films are attractive high-dielectric-constant materials for the next generation of gigabit dynamic random access memory devices. However, films exhibit relatively high current leakage densities of to at 1.0 MV/cm. A porous film microstructure was observed by transmission electron microscopy, and this seemed to be responsible for these high leakage currents. Further systematic optimization of the deposition and annealing processes is needed to produce a dense microstructure with a low leakage current level. © 2002 The Electrochemical Society. All rights reserved.