Patent Number: 
Section: claims

1. A laser produced plasma type extreme ultraviolet light source apparatus for generating extreme ultraviolet light by applying a laser beam to a target material, said apparatus comprising:a chamber in which extreme ultraviolet light is generated;target supply means for supplying a target material to a predetermined position within said chamber;a laser beam focusing optics for focusing a laser beam from a driver laser using a laser gas containing a carbon dioxide gas as a laser medium, for applying a laser beam to the target material supplied by said target supply means to generate plasma;a collector mirror for collecting the extreme ultraviolet light radiated from the plasma to output the extreme ultraviolet light;a spectrum purity filter provided in an optical path of the extreme ultraviolet light from said collector mirror, for transmitting the extreme ultraviolet light and reflecting the laser beam, said spectrum purity filter including a mesh having electrical conductivity; anda holder for holding a circumference of said mesh, said holder being formed with a channel for passing, along with the circumference of said mesh, a medium for cooling or heating said holder. 2. The extreme ultraviolet light source apparatus according to claim 1, wherein said mesh has a square-lattice form. 3. The extreme ultraviolet light source apparatus according to claim 1, wherein said mesh has a honeycomb form. 4. The extreme ultraviolet light source apparatus according to claim 1, wherein said spectrum purity filter includes a mesh coated with a material having electrical conductivity on at least a surface thereof. 5. The extreme ultraviolet light source apparatus according to claim 4, wherein said spectrum purity filter includes a mesh coated with a material having electrical conductivity on at least a light incident surface thereof. 6. The extreme ultraviolet light source apparatus according to claim 5, wherein said mesh contains one of diamond, diamond-like carbon, silicon carbide, and silicon. 7. The extreme ultraviolet light source apparatus according to claim 5, wherein said material having electrical conductivity contains one of gold and molybdenum. 8. The extreme ultraviolet light source apparatus according to claim 4, wherein said mesh contains one of diamond, diamond-like carbon, silicon carbide, and silicon. 9. The extreme ultraviolet light source apparatus according to claim 4, wherein said material having electrical conductivity contains one of gold and molybdenum. 10. The extreme ultraviolet light source apparatus according to claim 1, wherein said holder holds said mesh such that a surface of said mesh is flat. 11. The extreme ultraviolet light source apparatus according to claim 1, further comprising:a mechanism for rotating or vibrating said holder. 12. The extreme ultraviolet light source apparatus according to claim 1, wherein said chamber is configured to introduce an etchant gas, said etchant gas contains at least selected one from a hydrogen gas, halogen gas, hydrogen halide and argon gas.