X-ray characterization of annealed iridium films
Journal of Applied Physics
The changes in the mechanical and structural properties of sputter-deposited iridium films are described as a function of annealing temperature from 673 to 1073 K. Glancing angle x-ray diffraction and x-ray reflectivity measurements indicated the growth of an IrO 2 overlayer by annealing at 873 K. An increased annealing temperature of 1073 K led to the oxidation of the underlying iridium layer yielding a film comprising IrO 2 ͑major͒ and Ir ͑minor͒ phases. Annealing the films at 873 and 1073 K
... lso led to an increased surface roughness of the films. As-deposited as well as films annealed at 673 and 873 K exhibited tensile stresses along the normal to the plane in consideration. Annealing at 673 K and cooling within a tube furnace relaxed normal and shear stress present in as-deposited 20 nm Ir metal films. Slow cooling, formation of oxygen-iridium bonding, and increased roughness caused the preferential relaxation of the shear stresses for the film annealed at 873 K. The oscillations observed in the strain-sin 2 curve for the films annealed at 1073 K could be due to texture in the film and/or stress gradient across the thickness of the film. The residual stress has, therefore, not been evaluated for these films. X-ray photoelectron spectroscopic measurements on the iridium film annealed at 1073 K show that the film is oxygen rich at the surface and oxygen deficient near the substrate.