Abstract: The invention is directed to a method for at least partially removing a contamination layer (15) from an optical surface (14a) of an EUV-reflective optical element (14) by bringing a cleaning gas into contact with the contamination layer. In the method, a jet (20) of cleaning gas is directed to the contamination layer (15) for removing material from the contamination layer (15). The contamination layer (15) is monitored for generating a signal indicative of the thickness of the contamination layer (15) and the jet (20) of cleaning gas is controlled by moving the jet (20) of cleaning gas relative to the optical surface (14a) using this signal as a feedback signal. A cleaning arrangement (19 to 24) for carrying out the method is also disclosed. The invention also relates to a method for generating a jet (20) of cleaning gas and to a corresponding cleaning gas generation arrangement.

Abstract: A lithographic apparatus includes a projection system constructed and arranged to project a beam of radiation onto a target portion of a substrate, an internal sensor having a sensing surface, and a mini-reactor movable with respect to the sensor. The mini-reactor includes an inlet for a hydrogen containing gas, a hydrogen radical generator, and an outlet for a hydrogen radical containing gas. The mini-reactor is constructed and arranged to create a local mini-environment comprising hydrogen radicals to treat the sensing surface.

Abstract: An optical arrangement, e.g. a projection exposure apparatus (1) for EUV lithography, includes: a housing (2) enclosing an interior space (15); at least one, preferably reflective optical element (4-10, 12, 14.1-14.6) arranged in the housing (2); at least one vacuum generating unit (3) for the interior space (15) of the housing (2); and at least one vacuum housing (18, 18.1-18.10) arranged in the interior space (15) and enclosing at least the optical surface (17, 17.1, 17.2) of the optical element (4-10, 12, 14.1-14.5). A contamination reduction unit is associated with the vacuum housing (18.1-18.10) and reduces the partial pressure of contaminating substances, in particular of water and/or hydrocarbons, at least in close proximity to the optical surface (17, 17.1, 17.2) in relation to the partial pressure of the contaminating substances in the interior space (15).

Abstract: An optical element includes first regions which reflect or transmit the light falling on the optical element. The optical element also includes second regions which are in each instance separated by a distance from a first region and which at least partially surround a first region. The second regions are designed to be at least in part electrically conductive and are electrically insulated from the first regions. The optical element includes a carrier element and at least two first regions in the form of mirror facets which are arranged on the carrier element. The second regions are arranged with a separation from the mirror facets on the carrier element and are electrically insulated against the carrier element as well as against the mirror facet. At least one mirror facet is surrounded by an electrically conductive second region.

Abstract: The invention is directed to a method for at least partially removing a contamination layer (15) from an optical surface (14a) of an EUV-reflective optical element (14) by bringing a cleaning gas into contact with the contamination layer. In the method, a jet (20) of cleaning gas is directed to the contamination layer (15) for removing material from the contamination layer (15). The contamination layer (15) is monitored for generating a signal indicative of the thickness of the contamination layer (15) and the jet (20) of cleaning gas is controlled by moving the jet (20) of cleaning gas relative to the optical surface (14a) using this signal as a feedback signal. A cleaning arrangement (19 to 24) for carrying out the method is also disclosed. The invention also relates to a method for generating a jet (20) of cleaning gas and to a corresponding cleaning gas generation arrangement.

Abstract: An optical arrangement, e.g. a projection exposure apparatus (1) for EUV lithography, includes: a housing (2) enclosing an interior space (15); at least one, preferably reflective optical element (4-10, 12, 14.1-14.6) arranged in the housing (2); at least one vacuum generating unit (3) for the interior space (15) of the housing (2); and at least one vacuum housing (18, 18.1-18.10) arranged in the interior space (15) and enclosing at least the optical surface (17, 17.1, 17.2) of the optical element (4-10, 12, 14.1-14.5). A contamination reduction unit is associated with the vacuum housing (18.1-18.10) and reduces the partial pressure of contaminating substances, in particular of water and/or hydrocarbons, at least in close proximity to the optical surface (17, 17.1, 17.2) in relation to the partial pressure of the contaminating substances in the interior space (15).

Abstract: A method and an optical arrangement for removing contamination on optical surfaces (26), which are arranged in a vacuum environment in an optical arrangement, preferably in a projection exposure apparatus (1) for EUV lithography. The method includes generating a residual gas atmosphere containing molecular hydrogen (18) and at least one inert gas (17) in the vacuum environment, generating inert gas ions (21) by ionization of the inert gas (17), preferably with EUV radiation (20), and generating atomic hydrogen (27) by acceleration of the inert gas ions (21) in the residual gas atmosphere, to remove the contamination.

Abstract: An optical arrangement, in particular a projection system, illumination system or beam shaping system for EUV lithography, including at least one optical element that is arranged in a beam path of the optical arrangement and that reflects radiation in the soft X-ray- or EUV wavelength range, wherein at least during operation of the optical arrangement at least one of, preferably each of, the reflective optical elements in the beam path, at least at the optical surface, has an operating temperature of approximately 30° C. or more, preferably of approximately 100° C. or more, particularly preferably of approximately 150° C. or more, and even more preferably of approximately 250° C. or more, and wherein the optical design of the at least one reflective optical element is selected such that its optical characteristics are optimised for operation at the operating temperature. Also presented is a method for providing a reflective optical element with such an optical design.

Abstract: An optical apparatus includes an illumination system configured to form a pulsed radiation beam, an optical element with a surface on which the radiation beam is incident in operation, and a gas source arranged to supply a mixture of a first type of gas and a second type of gas to a space adjacent the surface. Particles of the first and second types of gas are capable of reacting with the surface, when activated by the radiation beam. The gas source is configured to generate a combination of surface occupation numbers of molecules of the first and second types of gas on the surface under operating conditions, at least prior to pulses of the radiation beam, the combination of surface occupation numbers lying in a range in which reactions of particles with the surface during pulses of the radiation beam are in majority reversed.

Abstract: A lithographic apparatus configured to project a patterned beam of radiation onto a target portion of a substrate is disclosed. The apparatus includes a first radiation dose detector and a second radiation dose detector, each detector comprising a secondary electron emission surface configured to receive a radiation flux and to emit secondary electrons due to the receipt of the radiation flux, the first radiation dose detector located upstream with respect to the second radiation dose detector viewed with respect to a direction of radiation transmission, and a meter, connected to each detector, to detect a current or voltage resulting from the secondary electron emission from the respective electron emission surface.

Abstract: A lithographic apparatus includes a projection system constructed and arranged to project a beam of radiation onto a target portion of a substrate, an internal sensor having a sensing surface, and a mini-reactor movable with respect to the sensor. The mini-reactor includes an inlet for a hydrogen containing gas, a hydrogen radical generator, and an outlet for a hydrogen radical containing gas. The mini-reactor is constructed and arranged to create a local mini-environment comprising hydrogen radicals to treat the sensing surface.

Abstract: The invention is directed to a method for at least partially removing a contamination layer (15) from an optical surface (14a) of an EUV-reflective optical element (14) by bringing a cleaning gas into contact with the contamination layer. In the method, a jet (20) of cleaning gas is directed to the contamination layer (15) for removing material from the contamination layer (15). The contamination layer (15) is monitored for generating a signal indicative of the thickness of the contamination layer (15) and the jet (20) of cleaning gas is controlled by moving the jet (20) of cleaning gas relative to the optical surface (14a) using this signal as a feedback signal. A cleaning arrangement (19 to 24) for carrying out the method is also disclosed. The invention also relates to a method for generating a jet (20) of cleaning gas and to a corresponding cleaning gas generation arrangement.

Abstract: A cleaning arrangement is configured to clean an EUV optic of an EUV lithographic apparatus. The partial radical pressure ranges between 0.1-10 Pa. The cleaning arrangement can be configured inside a cleaning cocoon of the lithographic apparatus for offline cleaning. It can also be configured at particular positions inside the apparatus to clean nearby optics during production. In the pressure range of 0.1-10 Pa the penetration of atomic hydrogen into the optical devices is high, while the recombination to molecular hydrogen and hydrogen consumption is limited.

Abstract: An optical element includes first regions which reflect or transmit the light falling on the optical element. The optical element also includes second regions which are in each instance separated by a distance from a first region and which at least partially surround a first region. The second regions are designed to be at least in part electrically conductive and are electrically insulated from the first regions. The optical element includes a carrier element and at least two first regions in the form of mirror facets which are arranged on the carrier element. The second regions are arranged with a separation from the mirror facets on the carrier element and are electrically insulated against the carrier element as well as against the mirror facet. At least one mirror facet is surrounded by an electrically conductive second region.

Abstract: An optical system for radiation in the EUV wavelength range, in particular a projection exposure apparatus, having at least one vacuum vessel, including: at least one EUV-reflective optical element arranged in an optical path, and a holder which includes at least one sample element, the sample element having an optical surface which is exposed to incident EUV-radiation outside of the optical path, the sample element being sensitive to chemical alterations under influence of the incident EUV-radiation which also affect the optical element. The optical system further includes at least one detection unit for online detection of the contamination status of the sample element during exposure of the sample element to the incident EUV-radiation.

Abstract: A lithographic apparatus is configured to project a pattern from a patterning device onto a substrate. The apparatus includes a gas purged sealing aperture extending between at least two different zones of the apparatus, and a gas supplier configured to supply the sealing aperture one or more gases selected from a group including hydrogen, deuterium, heavy hydrogen, deuterated hydrogen, and a mixture of argon and hydrogen.

Abstract: A method to clean optical elements of an apparatus, the apparatus being configured to project a beam of radiation onto a target portion of a substrate, the apparatus comprising a plurality of optical elements arranged in sequence in the path of the radiation beam, wherein the cleaning method comprises: cleaning one or more second optical elements of the sequence, which receive one or more relatively low second radiation doses during operation of the apparatus, utilizing cumulatively shorter cleaning periods than one or more first optical elements of the sequence that receive one or more first radiation doses during operation of the apparatus, a second radiation dose being lower than each relatively high first radiation dose.

Abstract: A method and an optical arrangement for removing contamination on optical surfaces (26), which are arranged in a vacuum environment in an optical arrangement, preferably in a projection exposure apparatus (1) for EUV lithography. The method includes generating a residual gas atmosphere containing molecular hydrogen (18) and at least one inert gas (17) in the vacuum environment, generating inert gas ions (21) by ionization of the inert gas (17), preferably with EUV radiation (20), and generating atomic hydrogen (27) by acceleration of the inert gas ions (21) in the residual gas atmosphere, to remove the contamination.

Abstract: A lithographic apparatus configured to project a patterned beam of radiation onto a target portion of a substrate is disclosed. The apparatus includes a first radiation dose detector and a second radiation dose detector, each detector comprising a secondary electron emission surface configured to receive a radiation flux and to emit secondary electrons due to the receipt of the radiation flux, the first radiation dose detector located upstream with respect to the second radiation dose detector viewed with respect to a direction of radiation transmission, and a meter, connected to each detector, to detect a current or voltage resulting from the secondary electron emission from the respective electron emission surface.

Abstract: An optical arrangement, in particular a projection exposure apparatus (1) for EUV lithography, includes: a housing (2) that encloses an interior space (15); at least one, in particular reflective, optical element (4 to 10, 12, 14.1 to 14.6) that is arranged in the housing (2); at least one vacuum generating unit (3) for generating a vacuum in the interior space (15) of the housing (2); and at least one vacuum housing (18, 18.1 to 18.10) that is arranged in the interior space (15) of the housing (2) and that encloses at least the optical surface (17, 17.1, 17.2) of the optical element (4 to 10, 12, 14.1 to 14.5), wherein a contamination reduction unit is associated with the vacuum housing (18.1 to 18.10), which contamination reduction unit reduces the partial pressure of contaminating substances, in particular of water and/or hydrocarbons, at least in close proximity to the optical surface (17, 17.1, 17.2) in relation to the partial pressure of the contaminating substances in the interior space (15).