Optical element and euv lithography system

An optical element for reflecting extreme ultraviolet (EUV) radiation, comprising:

• a substrate,
• a reflective coating configured to reflect the EUV radiation,
• an etchable material contained in an intermediate layer between the reflective coating and the substrate and covered by the reflective coating, wherein the etchable material is removed on contact with an etching medium,
• wherein the reflective coating is under a mechanical prestress causing the reflective coating to curve toward the substrate when the etchable material is removed by the etching medium and the reflective coating is damaged, and
• wherein the reflective coating is under compressive stress at least in a coating portion facing away from the substrate and is under tensile stress at least in a further coating portion facing toward the substrate, and
• wherein the etchable material is selected from the group consisting essentially of:
• amorphous silicon, silicon, SiO2 Si-containing glasses, Ge, GeO, B and BO.