System and method for generating extreme ultraviolet light

1. A system comprising:

a laser system configured to generate a pre-pulse laser beam with a pulse duration of less than 1 ns, and a main pulse laser beam;

a target supply unit configured to supply a target material to be irradiated with the pre-pulse laser beam and the main pulse laser beam for generating extreme ultraviolet light; and

a laser controller configured to control the laser system such that a fluence of the pre-pulse laser beam is lower than a fluence of the main pulse laser beam and a beam intensity of the pre-pulse laser beam is higher than a beam intensity of the main pulse laser beam.

2. The system according to claim 1 , wherein the controller is configured to control the laser system such that a pulse energy of the pre-pulse laser beam is 0.25 mJ or higher and 2 mJ or lower.

3. The system according to claim 1 , wherein the controller is configured to control the laser system such that a delay time from irradiation of the target material with the pre-pulse laser beam to irradiation of the target material with the main pulse laser beam is 0.5 μs or longer and 1.8 μs or shorter.

4. The system according to claim 1 , wherein the controller is configured to control the laser system such that a delay time from irradiation of the target material with the pre-pulse laser beam to irradiation of the target material with the main pulse laser beam is 0.7 μs or longer and 1.6 μs or shorter.

5. The system according to claim 1 , wherein the controller is configured to control the laser system such that a delay time from irradiation of the target material with the pre-pulse laser beam to irradiation of the target material with the main pulse laser beam is 1.0 μs or longer and 1.4 μs or shorter.

6. The system according to claim 1 , wherein the controller is configured to control the laser system such that a fluence of the pre-pulse laser beam is 2.6 J/cm 2 or higher and 6.5 J/cm 2 or lower.

7. The system according to claim 1 , wherein the controller is configured to control the laser system such that a beam intensity of the pre-pulse laser beam is 2.6×10 11 W/cm 2 or higher and 5.6×10 11 W/cm 2 or lower.

8. The system according to claim 1 , wherein the controller is configured to control the laser system such that a pulse energy of the main pulse laser beam is 135 mJ or higher and 170 mJ or lower.

9. The system according to claim 1 , wherein the controller is configured to control the laser system such that a fluence of the main pulse laser beam is 150 J/cm 2 or higher and 300 J/cm 2 or lower.

10. The system according to claim 1 , wherein the controller is configured to control the laser system such that a fluence of the main pulse laser beam is 191 J/cm 2 or higher and 241 J/cm 2 or lower.

11. The system according to claim 1 , wherein the controller is configured to control the laser system such that a beam intensity of the main pulse laser beam is 1.00×10 10 W/cm 2 or higher and 2.00×10 10 W/cm 2 or lower.

12. The system according to claim 1 , wherein the controller is configured to control the laser system such that a beam intensity of the main pulse laser beam is 1.27×10 10 W/cm 2 or higher and 1.60×10 10 W/cm 2 or lower.

13. The system according to claim 1 , wherein the controller is configured to control the laser system such that a pulse energy of the pre-pulse laser beam is lower than a pulse energy of the main pulse laser beam.

14. The system according to claim 1 , wherein

a spot size of the main pulse laser beam is larger than a spot size of the pre-pulse laser beam, and

the spot size of the pre-pulse laser beam is larger than a diameter of a target including the target material.

15. The system according to claim 1 , wherein the laser system includes a plurality of laser apparatuses.