An extreme ultra violet (EUV) light source apparatus includes a metal droplet generator, a collector mirror, an excitation laser inlet port for receiving an excitation laser, a first mirror configured to reflect the excitation laser that passes through a zone of excitation, and a second mirror configured to reflect the excitation laser reflected by the first mirror.

There is provided a reflective image-forming optical system which is applicable to an exposure apparatus using, for example, EUV light and which is capable of increasing numerical aperture while enabling optical path separation of light fluxes. In a reflective imaging optical system (6) forming an image of a first plane (4) onto a second plane (7), the numerical aperture on a side of the second plane with respect to a first direction (X direction) on the second plane is greater than 1.1 times a numerical aperture on the side of the second plane with respect to a second direction (Y direction) crossing the first direction on the second plane. The reflecting imaging optical system has an aperture stop (AS) defining the numerical aperture on the side of the second plane, and the aperture stop has an elliptic-shaped opening of which size in a major axis direction (X direction) is greater than 1.1 times that in a minor axis direction (Y direction).

A metrology system serves for examining objects with EUV measurement light. An illumination optical unit serves for guiding the EUV measurement light towards the object to be examined. The illumination optical unit has an illumination optical unit stop for prescribing a measurement light intensity distribution in an illumination pupil in a pupil plane of the illumination optical unit. An output coupling mirror serves for coupling a part of the measurement light out of an illumination beam path of the illumination optical unit. The output coupling mirror has a mirror surface which is used to couple out measurement light and has an aspect ratio of a greatest mirror surface extent A longitudinally with respect to a mirror surface longitudinal dimension (x) to a smallest mirror surface extent B longitudinally with respect to a mirror surface transverse dimension (y) perpendicular to the mirror surface longitudinal dimension (x). The aspect ratio A/B is greater than 1.1. The result is a metrology system in which a measurement light throughput is optimized even in the simulation or emulation of an imaging optical unit of a projection exposure apparatus having an image-side numerical aperture of greater than 0.5 and in particular in the simulation or emulation of an anamorphic imaging optical unit.

Embodiments described herein provide a lithographic system having two or more lithographic tools connected to a radiation source using two or more variable attenuation units. In some embodiments, the variable attenuation unit reflects a portion of the received light beam to the lithographic tool attached thereto and transmits a remaining portion of the received light beam to the lithographic tools downstream. In some embodiments, the radiation source includes two or more laser sources to provide laser beams with an enhanced power level and which can prevent operation interruption due to laser source maintenances and repair.

A microlithographic projection exposure mirror has a mirror substrate (12, 32), a reflection layer system (21, 41) for reflecting electromagnetic radiation that is incident on the mirror's optical effective surface, and at least one piezoelectric layer (16, 36), which is arranged between the mirror substrate and the reflection layer system and to which an electric field for producing a locally variable deformation is applied by a first electrode arrangement situated on the side of the piezoelectric layer facing the reflection layer system, and by a second electrode arrangement situated on the side of the piezoelectric layer facing the mirror substrate. One of the electrode arrangements is assigned a mediator layer (17, 37, 51, 52, 53, 71) for setting an at least regionally continuous profile of the electrical potential along the respective electrode arrangement. The mediator layer has at least two mutually electrically insulated regions (17a, 17b, 17c, . . . ; 37a, 37b, 37c, . . . ).

An optical element for reflecting radiation comprises: a substrate having first and second partial bodies put together at an interface; a reflective coating applied to a surface of the first partial body; a plurality of cooling channels running in the substrate in the region of the interface below the surface to which the reflective coating; a distributor in the substrate for connecting a coolant inlet to the plurality of cooling channels; and a collector in the substrate for connecting the plurality of cooling channels to a coolant outlet. The distributor and/or the collector extend, proceeding from the interface, further into the second partial body of the substrate than into the first partial body of the substrate. An optical arrangement, for example in an EUV lithography system, comprises: at least one such optical element; and a cooling device designed for flowing a coolant through the plurality of cooling channels.

A method includes: depositing a mask layer over a substrate; directing radiation reflected from a collector of a lithography system toward the mask layer according to a pattern; blocking a portion of the radiation by a blocking structure, the blocking structure being attached to a reflector of the lithography system; forming openings in the mask layer by removing regions of the mask layer exposed to the radiation; and removing material of a layer underlying the mask layer exposed by the openings.

An optical apparatus, which illuminates a first area with light from a light source while the first area is longer in a second direction intersecting a first direction than in the first direction, includes a collector optical member which is arranged in an optical path between the light source and the first area, and condenses the light from the light source to form a second area in a predetermined plane, the second area being longer in a fourth direction intersecting a third direction than in the third direction; and a first fly's eye optical member which is provided within the predetermined plane including the second area, and has a plurality of first optical elements guiding the light of the collector optical member to the first area.

An imaging optical unit for EUV microlithography is configured so that, when used in an optical system for EUV microlithography, relatively high EUV throughput and high imaging quality can achieved.

A pellicle membrane for a lithographic apparatus, the membrane including uncapped carbon nanotubes. A method of regenerating a pellicle membrane, the method including decomposing a precursor compound and depositing at least some of the products of decomposition onto the pellicle membrane. A method of reducing the etch rate of a pellicle membrane, the method including providing an electric field in the region of the pellicle membrane to redirect ions from the pellicle, or heating elements to desorb radicals from the pellicle, preferably wherein the pellicle membrane is a carbon nanotube pellicle membrane. An assembly for a lithographic apparatus, the assembly including a biased electrode near or including the pellicle membrane or heating means for the pellicle membrane.