Reflective optical element for EUV lithography

A reflective optical element for extreme ultraviolet (EUV) lithography, comprising:

• a substrate and a reflective coating configured to reflect radiation in a wavelength range of 5 nm to 20 nm;
• a functional layer that reduces a concentration of hydrogen in atom % at a side of the substrate facing the reflective coating by at least a factor of 2, wherein the functional layer comprises at least one of:
• tin, silver, molybdenum, ruthenium, iridium, iron, cobalt, aluminum, platinum, manganese, lead, gold, palladium, tungsten, tantalum, and alloys, oxides, borides, and nitrides or carbides thereof;
• and
• a microstructured layer arranged between the reflective coating and the substrate,
• wherein the functional layer is arranged between the reflective coating and the microstructured layer.