Radiation source apparatus and method for using the same

1. A method, comprising:

assembling a first droplet generator onto a port of a vessel;

ejecting a target droplet from the first droplet generator to a zone of excitation in front of a collector at an end of the vessel;

emitting a laser toward the zone of excitation, such that the target droplet is heated by the laser to generate extreme ultraviolet (EUV) radiation;

stopping the ejection of the target droplet;

after stopping the ejection of the target droplet, disassembling the first droplet generator from the port of the vessel;

after disassembling the first droplet generator from the port of the vessel, inserting a cleaning device into the vessel through the port; and

cleaning the collector by using the cleaning device.

2. The method of claim 1 , wherein cleaning the collector comprises:

moving a front end of the cleaning device from a first position in the vessel to a second position in the vessel.

3. The method of claim 1 , wherein cleaning the collector comprises:

rotating a first portion of the cleaning device with respect to a second portion of the cleaning device connected with the first portion of the cleaning device.

4. The method of claim 1 , wherein cleaning the collector comprising:

providing a vacuuming suction force to a surface of the collector.

5. The method of claim 1 , wherein inserting the cleaning device into the vessel comprises:

inserting a robot arm into the vessel through the port, wherein the robot arm holds an extraction tube of the cleaning device.

6. The method of claim 5 , further comprising:

detecting a tin contaminant on a cone structure at a top portion of the vessel by a detector, wherein the detector is mounted on the robot arm.

7. The method of claim 1 , wherein cleaning the collector is performed when the collector is supported by a supporting structure below the vessel.

8. The method of claim 1 , further comprising:

assembling a second droplet generator onto the port of the vessel after cleaning the collector.

9. The method of claim 1 , wherein inserting the cleaning device into the vessel is performed such that the cleaning device extends beyond a shroud below the port of the vessel.

10. The method of claim 1 , wherein assembling the first droplet generator onto the port of the vessel is performed such that the first droplet generator is held by a bellow assembly connected to the vessel, the method further comprising:

reducing a length of the bellow assembly prior to inserting the cleaning device into the vessel through the port.

11. A method, comprising:

assembling a first droplet generator onto a port of a vessel;

ejecting a target droplet into the vessel by the first droplet generator;

producing extreme ultraviolet (EUV) radiation by emitting a laser onto the target droplet;

turning off the first droplet generator;

disassembling the first droplet generator from the port of the vessel;

inserting a robot arm into the vessel through the port, wherein the robot arm holds a detector; and

detecting a tin contaminant on a cone structure at a top portion of the vessel by the detector.

12. The method of claim 11 , further comprising:

moving a front end of the robot arm from a first position in the vessel to a second position in the vessel after inserting the robot arm into the vessel.

13. The method of claim 11 , wherein the detector is an image detector, and detecting the tin contaminant on the cone structure comprises:

capturing a first image at a first position; and

capturing a second image at a second position.

14. The method of claim 11 , further comprising:

rotating a first portion of the robot arm with respect to a second portion of the robot arm connected with the first portion of the robot arm after inserting the robot arm into the vessel.

15. The method of claim 11 , wherein detecting the tin contaminant of the cone structure is performed when a collector is supported by a supporting structure below the vessel.

16. The method of claim 11 , further comprising:

assembling a second droplet generator onto the port of the vessel after detecting the tin contaminant on the cone structure.

17. An apparatus, comprising:

a vessel;

a collector at an end of the vessel;

a droplet generator detachably mounted on the vessel;

a first robot arm;

a first robot controller controlling the first robot arm to move the droplet generator away from the vessel;

a cleaning device;

a second robot arm; and

a second robot controller controlling the second robot arm to move the cleaning device into the vessel and clean the collector, in response to the droplet generator being moved away from the vessel.

18. The apparatus of claim 17 , wherein the cleaning device comprises a vacuum tube.

19. The apparatus of claim 17 , wherein the second robot arm comprises a first arm segment and a second arm segment, the second arm segment has a first end connected to the first arm segment, and the second robot controller further controls a second end of the second arm segment to rotate with respect to the first end of the second arm segment.

20. The apparatus of claim 17 , further comprising:

an image detector, wherein the second robot controller further controls the second robot arm to move the image detector into the vessel.