Provided for herein are methods for producing reflective optical elements for the EUV wavelength range which have grating structures or which include structures that can serve as phase shifters. The methods may include the following operations: applying a structurable layer to a substrate, applying a reflective coating to the substrate that has been provided with the structurable layer, and locally irradiating the structurable layer. The structurable layer may be irradiated before or after application of the reflective coating.

A multilayer stack in the form of a Bragg reflector comprising a graded interfacial layer and a method of manufacturing are disclosed. The graded interfacial layer eliminates the formation of low-reflectivity interfaces in a multilayer stack and reduces roughness of interfaces in a multilayer stack.

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.

Membranes for EUV lithography are disclosed. In one arrangement, a membrane has a stack having layers in the following order: a first capping layer including an oxide of a first metal; a base layer including a compound having a second metal and an additional element selected from the group consisting of Si, B, C and N; and a second capping layer including an oxide of a third metal, wherein the first metal is different from the second metal and the third metal is the same as or different from the first metal.

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.

The disclosure relates to an optical element, including: a substrate, a first coating, which is disposed on a first side of the substrate and is configured for reflecting radiation having a used wavelength (λ.sub.EUV) in the EUV wavelength range, and a second coating, which is disposed on a second side of the substrate, for influencing heating radiation that is incident on the second side of the substrate. The disclosure also relates to an optical arrangement having at least one such optical element.

Methods and apparatus for detecting ultraviolet light are provided herein. For example, an ultraviolet (UV) process chamber includes a vacuum window or a transparent showerhead; a UV light source disposed above one of the vacuum window or the transparent showerhead and configured to generate and transmit UV light into a process volume of the UV process chamber; and a first UV sensor configured to measure at least one of emissivity from the UV light source or irradiance of the UV light transmitted into the process volume and to transmit a signal corresponding to a measured at least one of emissivity from the UV light source or irradiance of the UV light to a controller coupled to the UV process chamber during operation.

In situ dynamic protection of an optical element surface against degradation includes disposing the optical element in an interior of an optical assembly for the FUV/VUV wavelength range and supplying at least one volatile fluorine-containing compound (A, B) to the interior for dynamic deposition of a fluorine-containing protective layer on the surface. The protective layer (7) is deposited on the surface layer by layer via a molecular layer deposition process. The compound includes a fluorine-containing reactant (A) supplied to the interior in a pulsed manner. A further reactant (B) is supplied to the interior also in a pulsed manner. An associated optical assembly includes an interior in which a surface is disposed, and at least one metering apparatus (123) that supplies a reactant to the interior. The metering apparatus provides a pulsed supply of the compound as a reactant (A, B) for layer by layer molecular layer deposition.

A method for figure correction of an optical element includes forming a masking layer on a surface of the optical element. The optical element has thinning regions and non-thinning regions. The masking layer is patterned to form masking regions and non-masking regions, and the masking layer is positioned relative to the optical element in such a manner that the masking regions corresponds to the non-thinning regions of the optical element and the non-masking regions corresponds to the thinning regions of the optical element. The method further includes performing reactive ion etching on the optical element provided with the masking layer so as to etch the thinning regions of the optical element to reduce a thickness of the thinning region.

The present invention provides a fluid purging system (100) for an optical element (120), comprising a fluid guiding unit arranged to guide a fluid, provided by a fluid supply system, over at least a curved portion of an optical surface (122) of the optical element. The fluid guiding unit comprises a fluid inlet and a first nozzle unit (110) for providing a fluid to the optical surface. The fluid guiding unit being formed by at least a first wall portion (102) and at least a second wall portion (104), wherein the second wall portion being configured to face the optical surface and to follow a contour of the optical surface. The second wall portion comprises a second nozzle unit (112).