Patent Number: 
Section: claims

1. An extreme ultraviolet light source device comprising:a chamber; anda target generating unit configured to supply the target material into the chamber, the target material being irradiated with a laser beam in the chamber to generate an extreme ultraviolet light, whereinthe target generating unit has a region that comes into contact with the target material in a molten state, the region having a surface roughness Ra of 1 μm or less, and wherein the region includes a first region that is formed on a surface part and a second region that is formed on a surface part having concavity and convexity. 2. The extreme ultraviolet light source device according to claim 1, wherein the region is coated with a material. 3. The extreme ultraviolet light source device according to claim 1, wherein the target generating unit has a substrate formed of a material, and the region on the substrate is formed of the same material as that of the substrate. 4. The extreme ultraviolet light source device according to claim 2, wherein the material with which the region is coated contains at least one of a metal nitride, a metal oxide, metal carbide, molybdenum, tungsten, ceramics, titanium, a diamond, a carbon graphite, and quartz. 5. The extreme ultraviolet light source device according to claim 3, wherein the material of the substrate contains at least one of a crystal that consists chiefly of molybdenum, a crystal that consists chiefly of titanium, a crystal that consists chiefly of tantalum, a crystal that consists chiefly of diamond, a crystal that consists chiefly of a carbon steel, and a crystal that consists chiefly of alumina. 6. The extreme ultraviolet light source device according to claim 1, wherein:the target material chiefly comprises tin, andthe region is in contact with tin in a molten state. 7. The extreme ultraviolet light source device according to claim 2, further comprising a target collecting device configured to collect an unused target material which is supplied from the target generating unit into the chamber, but not irradiated with the laser beam, whereinthe target collecting device has a region that comes into contact with the unused target material in a molten state, the region of the target collecting device is formed of a material which is the same as the material with which the region of the target generating unit is coated. 8. The extreme ultraviolet light source device according to claim 1, further comprising a target supply device configured to supply the target material to the target generating unit, whereinthe target supply device has a region that comes into contact with the target material in a molten state, the region having a surface roughness Ra of 1 μm or less. 9. The extreme ultraviolet light source device according to claim 3, further comprising a target collecting device configured to collect an unused target material which is supplied from the target generating unit into the chamber, but not irradiated with the laser beam, whereinthe target collecting device has a region that comes into contact with the unused target material in a molten state, the region of the target collecting device is formed of a material which is the same as that of the substrate of the target generating unit. 10. The extreme ultraviolet light source device according to claim 1, wherein the region has a polished surface by any one of a chemical polishing, an electrolytic polishing, a barrel polishing, a magnetic polishing, and a physical polishing, or a combination thereof. 11. The extreme ultraviolet light source device according to claim 1, wherein the target generating unit comprises a nozzle, a tank, and a filter between the nozzle and tank. 12. The extreme ultraviolet light source device according to claim 11, wherein the filter is formed of any of alumina, silica, silicon carbide, molybdenum, titanium, tantalum, and a carbon fiber. 13. The extreme ultraviolet light source device according to claim 11, wherein the filter comprises a stainless steel substrate, a surface of which is coated with any of a metal nitride, a metal oxide, metal carbide, molybdenum, tungsten, and ceramics.