Abstract: Proposed for cleaning optical elements for the ultraviolet wavelength range having at least one metal-containing layer on a surface is a process that includes: —supplying activated hydrogen to the surface having the metal-containing layer; subsequently supplying inert gas having an H2O volume fraction of below 5 ppm, preferably below 1 ppm, particularly preferably below 0.2 ppm. To this end, an optical system (1) includes a housing (122), a supply line (161) of activated hydrogen, a supply line (162) of inert gas having an H2O volume fraction of below 5 ppm and a discharge line (163) for pumping gas out of the housing.

Abstract: A projection exposure apparatus (400) for semiconductor lithography contains at least one partial volume (4) that is closed off from the surroundings. The partial volume (4) contains a gas, from which a plasma can be produced. Conditioning elements (20, 21, 22, 23, 24, 25) for conditioning the plasma, in particular for neutralizing the plasma, are present in the partial volume. An associated method for operating a projection exposure apparatus is also disclosed.

Abstract: An optical element (50), comprising: a substrate (52), an EUV radiation reflecting multilayer system (51) applied to the substrate, and a protective layer system (60) applied to the multilayer system and having at least a first and a second layer (57, 58). The first layer (57) is arranged closer to the multilayer system (51) than is the second layer (58) and serves as a diffusion barrier for hydrogen. This first layer (57) has a lower solubility for hydrogen than does the second layer (58), which serves for absorbing hydrogen. Also disclosed are an optical system for EUV lithography with at least one such optical element, and a method for treating an optical element in order to remove hydrogen incorporated in at least one layer (57, 58, 59) of the protective layer system and/or in at least one layer (53, 54) of the multilayer system (51).

Abstract: In order to prevent delamination of a reflective coating from the substrate under the influence of reactive hydrogen, a reflective optical element (50) for EUV lithography is provided, which has a substrate (51) and a reflective coating (54) for reflecting radiation in the wavelength range of 5 nm to 20 nm. A functional layer (60) is arranged between the reflective coating (54) and the substrate (51). With the functional layer, the concentration of hydrogen in atom % at the side of the substrate facing the reflective coating is reduced by at least a factor of 2.

Abstract: The invention relates to a method for determining the thickness of a contaminating layer and/or the type of a contaminating material on a surface (7) in an optical system, in particular on a surface (7) in an EUV lithography system, comprising: irradiating the surface (7) on which plasmonic nanoparticles (8a,b) are formed with measurement radiation (10), detecting the measurement radiation (10a) scattered at the plasmonic nanoparticles (8a,b), and determining the thickness of the contaminating layer and/or the type of the contaminating material on the basis of the detected measurement radiation (10a). The invention also relates to an optical element (1) for reflecting EUV radiation (4), and to an EUV lithography system.

Abstract: Proposed for cleaning optical elements for the ultraviolet wavelength range having at least one metal-containing layer on a surface is a process that includes: —supplying activated hydrogen to the surface having the metal-containing layer; subsequently supplying inert gas having an H2O volume fraction of below 5 ppm, preferably below 1 ppm, particularly preferably below 0.2 ppm. To this end, an optical system (1) includes a housing (122), a supply line (161) of activated hydrogen, a supply line (162) of inert gas having an H2O volume fraction of below 5 ppm and a discharge line (163) for pumping gas out of the housing.

Abstract: A projection exposure apparatus (400) for semiconductor lithography contains at least one partial volume (4) that is closed off from the surroundings. The partial volume (4) contains a gas, from which a plasma can be produced. Conditioning elements (20, 21, 22, 23, 24, 25) for conditioning the plasma, in particular for neutralizing the plasma, are present in the partial volume. An associated method for operating a projection exposure apparatus is also disclosed.

Abstract: In order to prevent delamination of a reflective coating from the substrate under the influence of reactive hydrogen, a reflective optical element (50) for EUV lithography is provided, which has a substrate (51) and a reflective coating (54) for reflecting radiation in the wavelength range of 5 nm to 20 nm. A functional layer (60) is arranged between the reflective coating (54) and the substrate (51). With the functional layer, the concentration of hydrogen in atom % at the side of the substrate facing the reflective coating is reduced by at least a factor of 2.

Abstract: A reflective optical element, in particular for a microlithographic projection exposure apparatus has a substrate (101), a reflection layer system (110) and a defect structure (120) of channel-shaped defects (121) which extend inward from the optical effective surface (100a), or from an interface oriented toward the substrate as far as the reflection layer system, and permit egress of hydrogen from the reflection layer system. The channel-shaped defects (121) increase a diffusion coefficient that is characteristic for the egress of the hydrogen from the reflection layer system (110) by at least 20%, in comparison to a similar layer construction without these channel-shaped defects.

Abstract: The invention relates to a method for determining the thickness of a contaminating layer and/or the type of a contaminating material on a surface (7) in an optical system, in particular on a surface (7) in an EUV lithography system, comprising: irradiating the surface (7) on which plasmonic nanoparticles (8a,b) are formed with measurement radiation (10), detecting the measurement radiation (10a) scattered at the plasmonic nanoparticles (8a,b), and determining the thickness of the contaminating layer and/or the type of the contaminating material on the basis of the detected measurement radiation (10a). The invention also relates to an optical element (1) for reflecting EUV radiation (4), and to an EUV lithography system.

Abstract: A reflective optical element, in particular for a microlithographic projection exposure apparatus has a substrate (101), a reflection layer system (110) and a defect structure (120) of channel-shaped defects (121) which extend inward from the optical effective surface (100a), or from an interface oriented toward the substrate as far as the reflection layer system, and permit egress of hydrogen from the reflection layer system. The channel-shaped defects (121) increase a diffusion coefficient that is characteristic for the egress of the hydrogen from the reflection layer system (110) by at least 20%, in comparison to a similar layer construction without these channel-shaped defects.

Abstract: An optical element (50), comprising: a substrate (52), an EUV radiation reflecting multilayer system (51) applied to the substrate, and a protective layer system (60) applied to the multilayer system and having at least a first and a second layer (57, 58). The first layer (57) is arranged closer to the multilayer system (51) than is the second layer (58) and serves as a diffusion barrier for hydrogen. This first layer (57) has a lower solubility for hydrogen than does the second layer (58), which serves for absorbing hydrogen. Also disclosed are an optical system for EUV lithography with at least one such optical element, and a method for treating an optical element in order to remove hydrogen incorporated in at least one layer (57, 58, 59) of the protective layer system and/or in at least one layer (53, 54) of the multilayer system (51).