A projection lens of an EUV-lithographic projection exposure system with at least two reflective optical elements each comprising a body and a reflective surface for projecting an object field on a reticle onto an image field on a substrate if the projection lens is exposed with an exposure power of EUV light, wherein the bodies of at least two reflective optical elements comprise a material with a temperature dependent coefficient of thermal expansion which is zero at respective zero cross temperatures, and wherein the absolute value of the difference between the zero cross temperatures is more than 6K.

A method of manufacture of an extreme ultraviolet reflective element includes: providing a substrate; forming a multilayer stack on the substrate, the multilayer stack includes a plurality of reflective layer pairs having a first reflective layer and a second reflective layer for forming a Bragg reflector; and forming a capping layer on and over the multilayer stack, the capping layer formed from titanium oxide, ruthenium oxide, niobium oxide, ruthenium tungsten, ruthenium molybdenum, or ruthenium niobium, and the capping layer for protecting the multilayer stack by reducing oxidation and mechanical erosion.

The disclosure relates to a microlithographic projection exposure apparatus, such as are used for the production of large-scale integrated electrical circuits and other microstructured components. The disclosure relates in particular to coatings of optical elements in order to increase or reduce the reflectivity.

A method aleviating blistering, cracking and chipping in topmost layers of a multilayer system exposed to reactive hydrogen, when producing a reflective optical element (50) having a maximum reflectivity at an operating wavelength of 5 nm to 20 nm. A multilayer system (51) composed of 30-60 stacks (53) is applied to a substrate (52). Each stack has a layer (54) of thickness d.sub.MLs composed of a high refractive index material and a layer (55) of thickness d.sub.MLa composed of a low refractive index material. The thickness ratio is d.sub.MLa/(d.sub.MLa+d.sub.MLs)=Γ.sub.ML. Two to five further stacks (56) are applied to the multilayer system. at least one further stack having a layer (54) of thickness d.sub.s composed of a high refractive index material and a layer (55) of thickness d.sub.a composed of a low refractive index material, wherein the thickness ratio is d.sub.a/(d.sub.a+d.sub.s)=Γ and wherein Γ≠Γ.sub.ML.

An EUV reflective structure includes a substrate and multiple pairs of a Si layer and a Mo layer. The Si layer includes a plurality of cavities.

A pellicle having a metal oxysilicide layer. A pellicle having a molybdenum layer, a ruthenium layer and a silicon oxynitride layer, wherein the molybdenum layer is disposed between the ruthenium layer and the silicon oxynitride layer. A method of manufacturing a pellicle for a lithographic apparatus, the method including providing a metal oxysilicide layer. A lithographic assembly including a pellicle having a metal oxysilicide layer. The use of a pellicle having a metal oxysilicide layer in a lithographic apparatus.

A mirror, in particular for a microlithographic projection exposure apparatus, has an optically effective surface (10a), a mirror substrate (11) and a reflection layer stack (12) configured to reflect electromagnetic radiation that is incident on the optically effective surface. A metallic diffusion barrier layer (13) is arranged on that side of the reflection layer stack which faces toward the optically effective surface, and a stabilization layer (14) is arranged on the side of the diffusion barrier layer that faces toward the optically effective surface (10a). The stabilization layer reduces deformation of the diffusion barrier layer compared to an analogous structure without such a stabilization layer upon irradiation of the optically effective surface with electromagnetic radiation. The stabilization layer has a porosity, a relative density of which is no more than 80%, where the relative density is defined as the ratio between geometric density and true density.

An optical assembly includes: an optical element, which is transmissive or reflective to radiation at a used wavelength and has an optically used region; and a thermally conductive component, which is arranged outside the optically used region of the optical element. The thermally conductive component can include a material having a thermal conductivity of more than 500 W m.sup.−1 K.sup.−1. Additionally or alternatively, the product of the thickness of the thermally conductive component in millimeters and the thermal conductivity of the material of the thermally conductive component is at least 1 W mm m.sup.−1 K.sup.−1.

A bottom lens for an immersion exposure tool includes a hydrophobic coating on the sidewalls of the bottom lens. A bottom portion of the bottom lens is not coated with the hydrophobic coating to maintain the optical performance of the bottom lens and to not distort a pattern that is to be transferred to a substrate. The hydrophobic coating may reduce the thermal instability of the bottom lens. This may reduce overlay variation during operation of the immersion exposure tool, which may increase manufacturing yield, decrease device failures, and/or decrease rework and repairs.

An extreme ultraviolet light concentrating mirror may include a substrate, a multilayer reflection film provided on the substrate and configured to reflect extreme ultraviolet light, and a protective film provided on the multilayer reflection film. Here, the protective film may include a mixed film in which a network-forming oxide is mixed with an amorphous titanium oxide, or a mixed film in which two or more amorphous titanium oxide layers and two or more network-forming oxide layers are each alternately laminated.