STRUCTURAL AND OPTICAL PROPERTIES OF IRIDIUM FILMS ANNEALED IN AIR

The present paper describes the changes in the structural and optical properties of the sputter deposited iridium films annealed in air and slow cooled from 673K-1073K. Glancing Angle Xray Diffraction (GAXRD) and X-ray Reflectivity (XRR) measurements were used for the structural investigations of the films. GAXRD and X-ray reflectivity measurements showed growth of ~4nm IrO2 over-layer by annealing at 873K. Increased annealing temperatures lead to the formation of oxidation of the iridium under-layer, with the film comprising iridium-oxide (major) and iridium (minor) phases. Increased surface roughness associated with the films annealed at 873K and 1073K was attributed to the growth of a crystalline IrO2 layer. Variable Angle Spectroscopic Ellipsometric (VASE) measurements in the wavelength range 300-1200nm, are presented for the as deposited iridium films and film annealed in air at 1073K. Estimated thickness of as-deposited iridium metal film was consistent with XRR results. The ellipsometry data for the annealed film was modeled using Lorentz oscillator layer. The results indicated the presence of conducting layer of Iridium oxide. INRODUCTION