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

Abstract

IrO 2 and Ir thin films have been deposited by dc sputtering in Ar/O 2 -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 IrO 2 films with different textures could be deposited. Stress analyses showed that the stress of the Ir films can be varied from about Ϫ3.5 GPa for a deposition temperature of 100°C to nearly zero stress if deposited at 500°C. However, IrO 2 films generally exhibited a large compressive stress of about Ϫ1.5 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 generally possible to optimize reactive IrO 2 sputter deposition by a detailed study of plasma and deposition conditions via recording generic curves for the sputtering system used. At optimized conditions these fine grained IrO 2 films exhibit very high thermal phase stability to at least 800°C for several hours and a very low roughness. The aim of these investigations is to optimize stability of IrO 2 films under high temperature conditions for oxygen barrier application in dynamic random access memory and nonvolatile Fe random access memory cells.

Electrochromic nickel oxide films and their compatibility with potassium hydroxide and lithium perchlorate in propylene carbonate: Optical, electrochemical and stress-related properties

“…1 that some small fraction of unoxidized Ir can remain in the sputter deposited films, which is not unexpected considering its inertness. Results similar to ours have been reported in other work on Ir oxide films made by reactive sputter deposition [30][31][32][33], reactive pulsed laser deposition [34] and atomic layer deposition [35], especially if the oxygen content was limited. RBS was used to record the elemental compositions of the Ir oxide films as a function of O 2 /Ar gas flow ratio during sputter deposition.…”

Growth and characterization of vertically aligned self-assembled IrO2 nanotubes on oxide substrates

“…Conductive IrO 2 exhibits high thermal and chemical stability, making their films valuable as durable electrodes for oxygen evolution [10,11] and memory devices [12][13][14][15]. In recent reports, IrO 2 have also been studied as high performance and robust field emitters owing to its low work function, low resistivity and excellent stability against oxygen [16][17][18].…”

Amorphous and crystalline IrO2 thin films as potential stimulation electrode coatings

“…this material injects charge using a reversible charge injection reaction which is governed by a valence-change within the layer of the material. Iridium oxide thin films have also found considerable research interest for applications such as oxygen diffusion barrier materials in random access memory devices [12,13]. Iridium oxide (IrO 2 ) layers can be formed by anodic electrochemical activation of iridium metal (AIROF) [10,11,14,15], electrodeposition (EIROF) [16,17] onto a bulk material, thermal decomposition of an iridium salt (TIROF) [18], and by reactive sputtering using an iridium target (SIROF) [1,19,20].…”