What is claimed is:
1. An apparatus for generating extreme ultraviolet light by irradiating a target material with a laser beam to turn the target material into a plasma, the apparatus comprising:
a reference member;
a chamber mounted on the reference member;
a target supply unit mounted on the chamber and configured to supply the target material into the chamber;
a laser beam introduction optical system mounted on the reference member and configured to introduce the laser beam into the chamber;
a laser beam focusing optical system mounted on a first holder and configured to focus the laser beam onto the target material, the first holder being mounted on the reference member; and
a collector mirror mounted on a second holder and configured to collect the extreme ultraviolet light emitted from the target material, the second holder being mounted on the reference member, wherein
the chamber has a first opening, the chamber is mounted on an upper surface of the reference member, a seal is provided between a periphery of the first opening of the chamber and the upper surface of the reference member, and
the second holder is mounted on the upper surface of the reference member, thereby connecting the collector mirror and the reference member through the first opening.
2. The apparatus according to claim 1 , wherein the laser beam focusing optical system is mounted on a downstream side of the laser beam introduction optical system on a beam path of the laser beam.
3. The apparatus according to claim 2 , wherein the laser beam focusing optical system is mounted on the beam path between the laser beam introduction optical system and the collector mirror.
4. The apparatus according to claim 3 , wherein the collector mirror has a through-hole at a center of the collector mirror, through which the laser beam travels.
5. The apparatus according to claim 4 , wherein the reference member has a housing shape.
6. The apparatus according to claim 5 , wherein the reference member including:
a second opening configured to introduce the laser beam; and
a third opening configured to introduce the laser beam to the chamber.
7. The apparatus according to claim 1 , wherein the laser beam focusing optical system is mounted on a beam path of the laser beam between the laser beam introduction optical system and the collector mirror.
8. The apparatus according to claim 1 , wherein the collector mirror has a through-hole at a center of the collector mirror, through which the laser beam travels.
9. The apparatus according to claim 1 , wherein the reference member has a housing shape.
10. The apparatus according to claim 1 , wherein the reference member including:
a second opening configured to introduce the laser beam, and
a third opening configured to introduce the laser beam to the chamber.
11. The apparatus according to claim 2 , further comprising a window mounted on the reference member and configured to keep the pressure inside the chamber.
12. The apparatus according to claim 11 , wherein the window is disposed on a beam path of the laser beam between the laser beam introduction optical system and the laser beam focusing optical system.
13. The apparatus according to claim 12 , further comprising a measuring device mounted on the reference member, on a beam path of the laser beam between the window and the laser beam introduction optical system.
14. The apparatus according to claim 1 , further comprising a measuring device mounted on the reference member and configured to measure the laser beam.
15. The apparatus according to claim 14 , wherein the measuring device has at least one beam profiler.
16. The apparatus according to claim 15 , wherein the measuring device has a plurality of beam profilers.
17. The apparatus according to claim 1 , further comprising a moving mechanism configured to move the reference member.
18. The apparatus according to claim 17 , wherein the moving mechanism has a plurality of rails.
19. The apparatus according to claim 17 , further comprising a positioning device configured to prevent the reference member from moving.
20. The apparatus according to claim 1 , further comprising a positioning device configured to prevent the reference member from moving.
21. The apparatus according to claim 20 , wherein the positioning device positions the reference member at least three points.
22. The apparatus according to claim 1 , wherein the collector mirror is mounted on the second holder at a back surface of the collector mirror, the back surface being substantially perpendicular to a travel direction of the laser beam.