Determination of Ir consumption during thermal oxidation and PbZrxTi1−xO3 processing using Bragg-peak fringe analysis

Abstract

Thickness interference fringes can be seen around the Bragg peaks of a variety of polycrystalline thin (10–20 nm) films using standard x-ray diffraction techniques in a conventional Bragg–Brentano geometry. In this article, thickness fringe analysis is used to investigate oxidation and roughening in thin Ir films with and without overlayers of the ferroelectric PbZrxTi1−xO3 (PZT). Changes in fringe spacing were used to determine the Ir thickness consumed by oxidation. Fringe contrast degradation (indicating roughening) was observed both after oxidation anneals (which formed a surface layer of IrO2) and after subsequent reduction anneals (which converted the IrO2 back to Ir). Film overlayers were found to have a protective effect against oxidation and roughening, as evidenced by comparison of postoxidation fringe patterns for bare and PZT-coated Ir films. Overall, our results demonstrate that thickness fringe analysis can be used as a simple, quantitative probe of processing-induced thin film thickness and morphology changes.