Patent Number: 
Section: claims

1. A source-collector device constructed and arranged to generate a radiation beam, the device comprising:a target unit constructed and arranged to present a target surface of plasma-forming material;a laser unit constructed and arranged to generate a beam of radiation directed onto the target surface so as to form a plasma from said plasma-forming material;a contaminant trap constructed and arranged to reduce propagation of particulate contaminants generated by the plasma;a radiation collector comprising a plurality of grazing-incidence reflectors arranged to collect radiation emitted by the plasma and form a beam therefrom; anda filter constructed and arranged to attenuate at least one wavelength range of the beam,wherein the target unit is located within a resonant cavity of the laser unit. 2. A source-collector device constructed and arranged to generate a radiation beam, the device comprising:a target unit constructed and arranged to present a target surface of plasma-forming material;a laser unit constructed and arranged to generate a beam of radiation directed onto the target surface so as to form a plasma from said plasma-forming material;a contaminant trap constructed and arranged to reduce propagation of particulate contaminants generated by the plasma;a radiation collector comprising a plurality of grazing-incidence reflectors arranged to collect radiation emitted by the plasma and form a beam therefrom; anda filter constructed and arranged to attenuate at least one wavelength range of the beam wherein the filter comprises a grazing-incidence reflector having a diffraction grating formed thereon. 3. A source-collector device constructed and arranged to generate a radiation beam, the device comprising:a target unit constructed and arranged to present a target surface of plasma-forming material;a laser unit constructed and arranged to generate a beam of radiation directed onto the target surface so as to form a plasma from said plasma-forming material;a contaminant trap constructed and arranged to reduce propagation of particulate contaminants generated by the plasma;a radiation collector comprising a plurality of grazing-incidence reflectors arranged to collect radiation emitted by the plasma and form a beam therefrom; anda filter constructed and arranged to attenuate at least one wavelength range of the beam wherein the filter comprises a diffraction grating formed on the grazing incidence reflectors of the radiation collector. 4. A device manufacturing method, comprising:directing a laser beam onto a target surface having a plasma-forming material thereon to form a plasma;trapping particulate contaminants emitted by the plasma;collecting radiation emitted by the plasma and forming the radiation into a beam;filtering the beam to attenuate at least one range of wavelengths;patterning the beam of radiation with a pattern in its cross-section; andprojecting the patterned beam of radiation onto a target portion of a substrate. 5. A lithographic apparatus, comprising:a source-collector device constructed and arranged to generate a radiation beam, the device comprisinga target unit constructed and arranged to present a target surface on which a plasma-forming material is present;a laser unit constructed and arranged to generate a beam of radiation directed onto the target surface so as to form a plasma from said plasma-forming material;a contaminant trap constructed and arranged to reduce propagation of particulate contaminants generated by the plasma;a radiation collector comprising a plurality of grazing-incidence reflectors arranged to collect radiation emitted by the plasma and form a beam therefrom; anda filter constructed and arranged to attenuate at least one wavelength range of the beam;a support configured to support a patterning device, the patterning device being configured to impart the beam of radiation with a pattern in its cross-section;a substrate table configured to hold a substrate; anda projection system configured to project the patterned beam onto a target portion of the substrate. 6. A radiation collector comprising a plurality of grazing-incidence reflectors arranged to collect radiation emitted by a plasma and form a beam therefrom; anda filter constructed and arranged to attenuate at least one wavelength range of the beam, the filter comprising a diffraction grating formed on the grazing incidence reflectors of the collector with grooves oriented parallel to an optical axis of the radiation collector. 7. A radiation source comprising:a bath constructed and arranged to contain a fuel for use as a plasma-forming material; anda wheel constructed an arranged to be at least partially immersed in, and rotatable within, said fuel, such that a rim of the wheel may be immersed, in use, in the fuel, the wheel being constructed and arranged to present a surface of the rim as a target for a radiation beam;wherein a surface of the rim is curved across a width of the rim. 8. A source-collector device constructed and arranged to generate a radiation beam, comprising:a first chamber and a second chamber, wherein gas, in use, is allowed to pass from one of the first chamber and second chamber to the other of the first chamber and second chamber;the first chamber housing a plasma formation location and having a gas inlet for introducing gas into the first chamber and a gas outlet for removing gas from the first chamber and configured and arranged to produce a flow rate of gas through the first chamber between 15 slm and 200 slm;the second chamber housing a grazing incidence radiation collector arranged to collect radiation generated, in use, at the plasma formation location, and to form a beam therefrom;the source-collector device further comprising a contaminant trap constructed and arranged to reduce propagation of particulate contaminants generated at the plasma formation location to the grazing incidence radiation collector, the contaminant trap being located in-between the plasma formation location and the grazing incidence radiation collector;the first chamber being arranged, in use, to contain gas at a first pressure, and the second chamber being arranged, in use, to contain gas at a second pressure, lower than the first pressure.