Characterization of Ru and RuO2 thin films prepared by pulsed metal organic chemical vapor deposition

Ultra‐thin ruthenium (Ru) layers were fabricated by pulsed metal organic chemical vapor deposition in an Aixtron Tricent reactor using a metal‐organic Ru precursor. Layer deposition was performed on different metal barrier combinations and on Al2O3 dielectric layers used in the fabrication of advanced Metal‐Insulator‐Metal (MIM) capacitor structures and on thermal SiO2 as reference structure. Ru layers with a thickness of 10 nm were characterized by Spectroscopic Ellipsometry (SE) and additional reference methods such as Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), and X‐Ray Reflectometry (XRR). As deposited and in situ annealed Ru layers were characterized by SE applying Drude‐Lorentz‐ and Effective Medium Approximation (EMA) models. It was shown that the deposited layers consist of a Ru‐RuO2 bilayer structure. By in situ annealing, the RuO2 layer thickness is reduced and highly pure Ru films are obtained. On the metal barriers the formation of a metal oxide interface, which is related to the deposition process, was determined. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)