Abstract: An undulator for a free electron laser includes a pipe for an electron beam and one or more periodic magnetic structures extending axially along the pipe. Each periodic magnetic structure includes a plurality of magnets and a plurality of passive ferromagnetic elements, the plurality of magnets being arranged alternately with the plurality of passive ferromagnetic elements in a line extending in an axial direction. Each of the plurality of magnets is spatially separated from the pipe, and each of the passive ferromagnetic elements extends radially from an adjacent magnet towards the pipe. A spacer element may be provided between the magnets and the pipe to provide radiation shielding for the magnets and/or cooling for the pipe.

Abstract: A method of patterning lithographic substrates, the method comprising using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates, wherein the method further comprises reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly.

Abstract: A radiation sensor apparatus for determining a position and/or power of a radiation beam, the radiation sensor apparatus including a chamber to contain a gas, one or more sensors, and a processor. The chamber has a first opening and a second opening such that a radiation beam can enter the chamber through the first opening, propagate through the chamber generally along an axis, and exit the chamber through the second opening. Each of the one or more sensors is arranged to receive and detect radiation emitted from a region of the chamber around the axis. The processor is operable to use the radiation detected by the one or more sensors to determine a position and/or power of the radiation beam.

Abstract: A radiation alteration device includes a continuously undulating reflective surface, wherein the shape of the continuously undulating reflective surface follows a substantially periodic pattern.

Abstract: Disclosed is component for a radiation source, said radiation source being operable to generate radiation from a fuel, said component having a surface comprising a plurality of first regions that have a high wettability by said fuel, separated by second regions which have a low wettability by said fuel. Said component may comprise a screening element for a droplet generator or contamination trap, for example.

Abstract: A method of patterning lithographic substrates that includes using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates. The method further includes reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly, and applying variable attenuation to EUV radiation that has been output by the free electron laser in order to further control the power of EUV radiation delivered to the lithographic apparatus.

Abstract: An undulator for a free electron laser includes a pipe for an electron beam and one or more periodic magnetic structures extending axially along the pipe. Each periodic magnetic structure includes a plurality of magnets and a plurality of passive ferromagnetic elements, the plurality of magnets being arranged alternately with the plurality of passive ferromagnetic elements in a line extending in an axial direction. Each of the plurality of magnets is spatially separated from the pipe, and each of the passive ferromagnetic elements extends radially from an adjacent magnet towards the pipe. A spacer element may be provided between the magnets and the pipe to provide radiation shielding for the magnets and/or cooling for the pipe.

Abstract: There is disclosed a lithographic apparatus provided with a spectral purity filter which may be provided in one or more of the following locations: (a) in the illumination system, (b) adjacent the patterning device, either a static location in the radiation beam or fixed for movement with the patterning device, (c) in the projection system, and (d) adjacent the substrate table. The spectral purity filter is preferably a membrane formed of polysilicon, a multilayer material, a carbon nanotube material or graphene. The membrane may be provided with a protective capping layer, and/or a thin metal transparent layer.

Abstract: Disclosed is component for a radiation source, said radiation source being operable to generate radiation from a fuel, said component having a surface comprising a plurality of first regions that have a high wettability by said fuel, separated by second regions which have a low wettability by said fuel. Said component may comprise a screening element for a droplet generator or contamination trap, for example.

Abstract: A lithographic apparatus injects gas between a reticle (MA) and reticle blades (REB-X, REB-Y) to protect the reticle from contamination. The gas may be injected either into the space defined between the reticle and the closest pair of reticle blades, or into the space defined between the two pairs of reticle blades.

Abstract: A delivery system for use within a lithographic system. The beam delivery system comprises optical elements arranged to receive a radiation beam from a radiation source and to reflect portions of radiation along one or more directions to form a one or more branch radiation beams for provision to one or more tools.

Abstract: A method of patterning lithographic substrates that includes using a free electron laser to generate EUV radiation and delivering the EUV radiation to a lithographic apparatus which projects the EUV radiation onto lithographic substrates. The method further includes reducing fluctuations in the power of EUV radiation delivered to the lithographic substrates by using a feedback-based control loop to monitor the free electron laser and adjust operation of the free electron laser accordingly, and applying variable attenuation to EUV radiation that has been output by the free electron laser in order to further control the power of EUV radiation delivered to the lithographic apparatus.

Abstract: Disclosed is a substrate support for an apparatus of the type which projects a beam of EUV radiation onto a target portion of a substrate (400). The substrate support comprises a substrate table constructed to hold the substrate, a support block (420) for supporting the substrate table, and a cover plate (450?) disposed around the substrate table. The top surface of the cover plate and the top surface of a substrate mounted on the substrate table are all substantially at the same level. At least one sensor unit (430) is located on the substrate support and its top surface is also at the same level as that of the cover plate and substrate. Also disclosed is an EUV lithographic apparatus comprising such a substrate support.

Abstract: There is disclosed a lithographic apparatus provided with a spectral purity filter which may be provided in one or more of the following locations: (a) in the illumination system, (b) adjacent the patterning device, either a static location in the radiation beam or fixed for movement with the patterning device, (c) in the projection system, and (d) adjacent the substrate table. The spectral purity filter is preferably a membrane formed of polysilicon, a multilayer material, a carbon nanotube material or graphene. The membrane may be provided with a protective capping layer, and/or a thin metal transparent layer.

Abstract: A lithographic apparatus includes a substrate table constructed to hold a substrate, and a projection system configured to project a patterned radiation beam onto a target portion of the substrate. A surface of a component of the lithographic apparatus that is in a vacuum environment in use is provided with a repeating structure configured to increase the effective thermal accommodation coefficient of the surface.

Abstract: A lithographic apparatus injects gas between a reticle (MA) and reticle blades (REB-X, REB-Y) to protect the reticle from contamination. The gas may be injected either into the space defined between the reticle and the closest pair of reticle blades, or into the space defined between the two pairs of reticle blades.

Abstract: A lithographic apparatus includes a projection system that includes a plurality of reflective optics. One of the reflective optics is provided with an opening which passes through the reflective optic. The opening is closed by a covering layer that is substantially transparent to EUV radiation. The covering layer prevents contamination from entering the projection system, while allowing patterned EUV radiation to pass from the projection system onto a substrate.

Abstract: A lithographic apparatus includes a substrate table constructed to hold a substrate, a projection system configured to project a patterned radiation beam through an opening and onto a target portion of the substrate, and a conduit having an outlet in the opening. The conduit is configured to deliver gas to the opening. The lithographic apparatus further includes a cooling apparatus controlled by a control system. The cooling apparatus is configured to cool the gas such that gas which travels from the opening to the substrate has a predetermined temperature when the gas is incident upon the substrate.

Abstract: A lithographic apparatus includes a substrate table constructed to hold a substrate, a projection system configured to project a patterned radiation beam through an opening and onto a target portion of the substrate, and a conduit having an outlet in the opening. The conduit is configured to deliver gas to the opening. The lithographic apparatus further includes a cooling apparatus controlled by a control system. The cooling apparatus is configured to cool the gas such that gas which travels from the opening to the substrate has a predetermined temperature when the gas is incident upon the substrate.

Abstract: A lithographic apparatus includes a projection system configured to project a patterned beam of radiation onto a substrate. The projection system being provided with an opening through which the patterned beam of radiation may pass. At least part of the opening comprises a sloped surface of a wall of the projection system and a sloped surface of a mirror of the projection system.