Patent Number: 
Section: claims

1. An extreme ultraviolet (EUV) light source comprising:a solid state laser configured to produce pulses of radiation, the pulses of radiation produced by the solid state laser comprising at least a first pulse of radiation;a second optical source configured to produce pulses of radiation, the pulses of radiation produced by the second optical source comprising at least a second pulse of radiation, the second pulse of radiation having a greater intensity than the first pulse of radiation;a vacuum chamber configured to receive a target material in an interior of the vacuum chamber, the target material comprising a material that emits EUV light when converted to plasma; andan optical element configured to direct the first pulse of radiation and the second pulse of radiation toward the interior of the vacuum chamber to, respectively, a first location in the interior of the vacuum chamber and a second, different location in the interior of the vacuum chamber, the first and second locations in the interior of the vacuum chamber being along a direction that is different from a direction of propagation of the first pulse of radiation and the second pulse of radiation in the interior of the vacuum chamber. 2. The EUV light source of claim 1, wherein the first pulse of radiation produced by the solid state laser has a first wavelength, and the second pulse of radiation produced by the second optical source has a second wavelength, the first and second wavelengths being different. 3. The EUV light source of claim 2, wherein the first pulse of radiation has a wavelength of 1.06 microns (μm), and the second pulse of radiation has a wavelength of 10.6 μm. 4. The EUV light source of claim 1, wherein the first pulse of radiation has a temporal duration of 5-20 picoseconds (ps). 5. The EUV light source of claim 1, wherein the first pulse of radiation has a temporal duration of 150 ps or less. 6. An extreme ultraviolet (EUV) light source comprising:a vacuum chamber configured to receive a target material in an interior of the vacuum chamber, the target material comprising a material that emits EUV light when converted to plasma;a solid state laser configured to produce pulses of radiation, the pulses of radiation produced by the solid state laser comprising at least a first pulse of radiation, the first pulse of radiation propagating on a first beam path to a first location in the interior of the vacuum chamber; anda second optical source configured to produce pulses of radiation, the pulses of radiation produced by the second optical source comprising at least a second pulse of radiation, the second pulse of radiation having a greater intensity than the first pulse of radiation, and the second pulse of radiation propagating on a second beam path to a second location in the interior of the vacuum chamber, the first and second locations in the interior of the vacuum chamber being different locations along a direction that is different from a direction of propagation of the first pulse of radiation and the second pulse of radiation in the interior of the vacuum chamber. 7. The EUV light source of claim 6, further comprising an optical element placed on the first beam path and the second beam path, the optical element positioned to receive the first pulse of radiation and the second pulse of radiation and to direct the first pulse of radiation to the first location and the second pulse of radiation to the second location. 8. The EUV light source of claim 7, wherein the optical element comprises a surface that is at least partially reflective. 9. The EUV light source of claim 7, wherein the optical element transmits one of the first pulse of radiation and the second pulse of radiation, and reflects the other of the first pulse of radiation and the second pulse of radiation. 10. The EUV light source of claim 7, wherein the wavelength of the first pulse of radiation is different from the wavelength of the second pulse, and the optical element comprises a dichroic mirror. 11. The EUV light source of claim 7, wherein the wavelength of the first pulse of radiation is different from the wavelength of the second pulse, and the optical element comprises a wedge-shaped optical element that directs the first pulse and the second pulse toward the interior of the vacuum chamber at different angles relative to the optical element. 12. The EUV light source of claim 6, further comprising a first optical element on the first beam path, wherein the first optical element directs the first pulse of radiation toward the first location in the interior of the vacuum chamber. 13. The EUV light source of claim 6, further comprising a first optical element on the first beam path, and a second optical element on the second beam path, wherein the first optical element directs the first pulse of radiation toward the first location in the interior of the vacuum chamber, and the second optical element directs the second pulse of radiation toward the second location in the interior of the vacuum chamber. 14. The EUV light source of claim 13, wherein the first optical element comprises one or more optical fibers. 15. The EUV light source of claim 6, wherein the first pulse of radiation has a wavelength of 1.06 microns (μm), and the second pulse of radiation has a wavelength of 10.6 μm. 16. The EUV light source of claim 6, wherein the first pulse of radiation has a temporal duration of 5-20 picoseconds (ps). 17. The EUV light source of claim 6, wherein the first pulse of radiation has a temporal duration of 150 ps or less. 18. The EUV light source of claim 6, wherein the target material comprises a target material droplet, and the EUV light source further comprises a target material delivery system coupled to the vacuum chamber, the target material delivery system configured to provide the target material droplet to the interior of the vacuum chamber. 19. The EUV light source of claim 18, wherein the target material delivery system releases the target material droplet onto a trajectory in the interior of the vacuum chamber, and the first and second locations are on the trajectory. 20. The EUV light source of claim 19, wherein the target material droplet comprises tin. 21. A photolithography system comprising:a lithography tool configured to process wafers; andan extreme ultraviolet (EUV) light source comprising:a vacuum chamber configured to receive a target material in an interior of the vacuum chamber, the target material comprising a material that emits EUV light when converted to plasma;an optical element in the interior of the vacuum chamber, the optical element positioned to direct EUV light to the lithography tool;a first optical source configured to produce pulses of radiation, the pulses of radiation produced by the first optical source comprising at least a first pulse of radiation, the first pulse of radiation propagating on a first beam path to a first location in the interior of the vacuum chamber; anda second optical source configured to produce pulses of radiation, the pulses of radiation produced by the second optical source comprising at least a second pulse of radiation, the second pulse of radiation having a greater intensity than the first pulse of radiation, and the second pulse of radiation propagating on a second beam path to a second location in the interior of the vacuum chamber, the first and second locations in the interior of the vacuum chamber being different locations along a direction that is different from a direction of propagation of the first pulse of radiation and the second pulse of radiation in the interior of the vacuum chamber. 22. The photolithography system of claim 21, wherein the first optical source comprises a solid state laser. 23. A method comprising:directing a first pulse of radiation toward a first location in a vacuum chamber of an extreme ultraviolet (EUV) source, the first location at least partially coinciding with a target material droplet comprising target material that emits EUV light when converted to plasma, and the first pulse of radiation comprising an intensity sufficient to transform the target material droplet into a geometric distribution of target material, the geometric distribution of target material occupying a larger volume than a volume occupied by the target material droplet; anddirecting second pulse of radiation toward a second location in the vacuum chamber, whereinthe second location is a different location than the first location,the second location at least partially coincides with the geometric distribution of target material,the second pulse of radiation has a greater intensity than the first pulse of radiation. 24. The method of claim 23, wherein the density of the geometric distribution increases along a direction of propagation of the second pulse of radiation. 25. The method of claim 23, wherein the first pulse of radiation propagates along a first beam path, and the second pulse of radiation propagates along a second beam path. 26. The method of claim 23, wherein the first pulse of radiation has a duration of 150 ps or less.