Abstract: A patterning device comprising a reflective marker, wherein the marker comprises: a plurality of reflective regions configured to preferentially reflect radiation having a given wavelength; and a plurality of absorbing regions configured to preferentially absorb radiation having the given wavelength; wherein the absorbing and reflective regions are arranged to form a patterned radiation beam reflected from the marker when illuminated with radiation, and wherein the reflective regions comprise a roughened reflective surface, the roughened reflective surface being configured to diffuse radiation reflected from the reflective regions, and wherein the roughened reflective surface has a root mean squared roughness of about an eighth of the given wavelength or more.

Abstract: A patterning device comprising a reflective marker, wherein the marker comprises: a plurality of reflective regions configured to preferentially reflect radiation having a given wavelength; and a plurality of absorbing regions configured to preferentially absorb radiation having the given wavelength; wherein the absorbing and reflective regions are arranged to form a patterned radiation beam reflected from the marker when illuminated with radiation, and wherein the reflective regions comprise a roughened reflective surface, the roughened reflective surface being configured to diffuse radiation reflected from the reflective regions, and wherein the roughened reflective surface has a root mean squared roughness of about an eighth of the given wavelength or more.

Abstract: A patterning device comprising a reflective marker, wherein the marker comprises: a plurality of reflective regions configured to preferentially reflect radiation having a given wavelength; and a plurality of absorbing regions configured to preferentially absorb radiation having the given wavelength; wherein the absorbing and reflective regions are arranged to form a patterned radiation beam reflected from the marker when illuminated with radiation, and wherein the reflective regions comprise a roughened reflective surface, the roughened reflective surface being configured to diffuse radiation reflected from the reflective regions, and wherein the roughened reflective surface has a root mean squared roughness of about an eighth of the given wavelength or more.

Abstract: A patterning device comprising a reflective marker, wherein the marker comprises: a plurality of reflective regions configured to preferentially reflect radiation having a given wavelength; and a plurality of absorbing regions configured to preferentially absorb radiation having the given wavelength; wherein the absorbing and reflective regions are arranged to form a patterned radiation beam reflected from the marker when illuminated with radiation, and wherein the reflective regions comprise a roughened reflective surface, the roughened reflective surface being configured to diffuse radiation reflected from the reflective regions, and wherein the roughened reflective surface has a root mean squared roughness of about an eighth of the given wavelength or more.

Abstract: A metal component (262M, 300M) is designed for use in an EUV lithography apparatus, for example as a spectral purity filter (260) or a heating element (300) in a hydrogen radical generator. An exposed surface of the metal is treated (262P, 300P) to inhibit the formation of an oxide of said metal in an air environment prior to operation. This prevents contamination of optical components by subsequent evaporation of the oxide during operation of the component at elevated temperatures.

Abstract: A method of reducing contamination generated by a hydrogen radical generator and deposited on an optical element of a lithographic apparatus includes passing molecular hydrogen over a first part of a metal filament of the hydrogen radical generator, the first part including a metal-oxide, when the temperature of the first part of the metal filament is at a reduction temperature less than or equal to an evaporation temperature of the metal-oxide.