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Fabrication of multilayer laminar grating with high efficiency for extreme ultraviolet

The main goal for investigations on multilayer laminar gratings working at the EUV region is to enhance their efficiency. In this article, we demonstrate a routine to fabricate multilayer laminar gratings with high efficiency. This routine comprises three steps: first, preparing grating substrates with ideal groove profile and low roughness by holographic recording and ion beam etching process; second, optimizing fabricating techniques to obtain multilayer coatings with high reflectivity; third, strictly controlling errors of multilayer grating parameters to ensure the coinciding of the optical performance with the expectation. Results demonstrate that this routine is feasible. The measured peak efficiency of -1 order at 12.8nm was 14.3%. Some related issues about efficiency curves such as wavelength separation and suppression of zero order are discussed.