Determination of processing damage in thin polycrystalline Ir films using Bragg-peak fringe analysis

Abstract

We present an analysis of Bragg-Brentano diffraction spectra from blanket thin (10-20 nm) films of polycrystalline Ir, sputter deposited on thermally oxidized Si wafers. We observed that postdeposition annealing sharpened the Ir diffraction peaks, produced enhanced texture, and resulted in the formation of well-defined thickness fringes that were symmetric around the 111 Ir reflection. Scanning electron microscopy confirmed that the fringes were caused by the increased coherence lengths of the annealed grains. Annealed samples subsequently subjected to reactive ion etching exhibited asymmetric fringe patterns, with lower intensity fringes on the high angle side of the 111 Ir peak. Reannealing these samples restored the symmetric fringes. Analysis of the fringe patterns using simple equations and modeling programs in the public domain yielded valuable structural information about the film and the changes caused by processing. These results were verified by x-ray reflectivity measurements and modeling. We conclude that thickness fringe analysis using standard x-ray systems and simple programs can provide cost-effective process diagnostics for high atomic number thin film structures. © 2001 American Institute of Physics.