Reflective Optical Element for the EUV Wavelength Range, Method for Producing and for Correcting Such an Element, Projection Lens for Microlithography Comprising Such an Element, and Projection Exposure Apparatus for Microlithography Comprising Such a Projection Lens

摘要

A reflective optical element 39 for EUV wavelengths having a layer arrangement on the surface of a substrate, wherein the layer arrangement includes at least one layer subsystem 37 consisting of a periodic sequence of at least one period of individual layers. The period includes two individual layers having different refractive indices in the EUV wavelength range. The substrate has a variation of the density of more than 1% by volume at least along an imaginary surface 30 at a fixed distance of between 0 μm and 100 μm from the surface. Also, the substrate is protected against long-term aging or densification by EUV radiation either with a protective layer, with a protective layer subsystem of the layer arrangement, or with a correspondingly densified surface region 35 of the substrate.

主权项

1. Reflective optical element for the extreme ultraviolet (EUV) wavelength range comprising a layer arrangement applied on a surface of a substrate,
wherein the layer arrangement comprises at least one layer subsystem consisting of a periodic sequence of at least one period of individual layers, wherein the period comprises two individual layers having different refractive indices in the EUV wavelength range, wherein the substrate in a surface region adjoining the layer arrangement and extending into the substrate up to a distance of 5 μm from the surface has an average density which is higher by more than 1% by volume than an average density of a region of the substrate extending into the substrate a distance of 1 mm from the surface, and wherein the substrate has a variation of the density of more than 1% by volume at least along an imaginary surface at a fixed distance of between 1 μm and 100 μm from the surface.