Preparation and properties of dc-sputtered IrO2 and Ir thin films for oxygen barrier applications in advanced memory technology

IrO2 and Ir thin films have been deposited by dc sputtering in Ar/O2- and pure Ar atmospheres, respectively. The microstructural characterization of the films was done by x-ray diffraction and transmission electron microscopy and showed that (nano-)crystalline Ir and IrO2 films with different textures could be deposited. Stress analyses showed that the stress of the Ir films can be varied from about −3.5 GPa for a deposition temperature of 100 °C to nearly zero stress if deposited at 500 °C. However, IrO2 films generally exhibited a large compressive stress of about −1.5 GPa, which is nearly independent of substrate temperature, but changed with texture and stoichiometry of the films. Surface and roughness analyses of the cumulatively annealed samples were performed by various analysis methods, and stoichiometry was examined by Rutherford backscattering spectrometry. In situ stress measurements were used to investigate the stress relaxation behavior of the films up to 900 °C. We demonstrate that it is gen...