Compatibility of iridium thin films with the silicon pore optics technology for Athena

The development of high-quality thin film coatings for the Athena X-ray optics is progressing, following the commissioning of an industrial scale coating facility. The assembly of silicon pore optics into mirror modules for the Athena telescope requires wet-chemical exposure of coated mirror plates to prepare bonding areas for stacking, as well as an annealing step to improve bond strength. It is therefore critical to evaluate how these post-coating processes could affect the mirror coating performance and stability. We present X-ray reflectometry characterization of iridium thin films deposited on photoresist patterned Silicon Pore Optics plates to investigate the compatibility with the stacking process steps for the manufacturing of the Athena optics.