Changes in thin film morphology and their underlying processes can prove important for the performance of future extreme ultraviolet (EUV) optics. A ruthenium coated diffraction grating was...Show moreChanges in thin film morphology and their underlying processes can prove important for the performance of future extreme ultraviolet (EUV) optics. A ruthenium coated diffraction grating was inspected using atomic force microscopy (AFM) prior to and after exposure to high intensity EUV light under a grazing incident angle, in order to determine whether such change occurs due to EUV irradiation. AFM images show signs of structural change, most noticeable at the bottom of the grating, possibly caused by heating through absorption of the EUV radiation. Closer study of the top grating section showed signs of a change in thin film morphology as well. We used statistical and dynamic scaling analysis of multiple AFM images to verify this hypothesis, but it could not confirm this change beyond doubt, nor dismiss the claims outright. Possible explanations for a change in thin film morphology were proposed, such as thermally assisted diffusion causing roughening and coarsening, as well as oxidation of the layer.Show less
