Patent Number: 
Section: claims

1. An extreme ultraviolet light generation system, comprising:a laser device configured to emit pulse laser light;an EUV light concentrating mirror configured to reflect and concentrate extreme ultraviolet light generated by irradiating a target with the pulse laser light; anda processor configured to receive a first energy parameter of the extreme ultraviolet light and control an irradiation frequency of the pulse laser light with which the target is irradiated so that change in a second energy parameter related to energy per unit time of the extreme ultraviolet light reflected by the EUV light concentrating mirror is suppressed,wherein the first energy parameter includes a combination of one of EUV pulse energy and EUV power and one of EUV light concentration size and EUV emission size, and the second energy parameter includes one of EUV power, EUV power density, and EUV radiation brightness. 2. The extreme ultraviolet light generation system according to claim 1,wherein the processor is connected to an EUV light utilization apparatus that receives the extreme ultraviolet light generated in the extreme ultraviolet light generation system and is configured to receive the first energy parameter from the EUV light utilization apparatus. 3. The extreme ultraviolet light generation system according to claim 1,wherein the processor calculates the second energy parameter based on the first energy parameter. 4. The extreme ultraviolet light generation system according to claim 1,wherein the processor receives the second energy parameter as the first energy parameter. 5. The extreme ultraviolet light generation system according to claim 1,wherein the processor increases the irradiation frequency by increasing an emission frequency of the pulse laser light from the laser device. 6. The extreme ultraviolet light generation system according to claim 1,further comprising a target supply unit configured to sequentially generate and supply a plurality of droplets as the target to an optical path of the pulse laser light,wherein the processor increases the irradiation frequency by increasing both a generation frequency of the plurality of droplets from the target supply unit and the emission frequency of the pulse laser light from the laser device. 7. The extreme ultraviolet light generation system according to claim 1,wherein the target includes a plurality of droplets that are sequentially generated and supplied to an optical path of the pulse laser light,the plurality of droplets includes a droplet not to be irradiated with the pulse laser light and a droplet to be irradiated with the pulse laser light, andthe processor increases the irradiation frequency by increasing a ratio of the number of the droplets to be irradiated with the pulse laser light to the number of the plurality of droplets. 8. The extreme ultraviolet light generation system according to claim 1,further comprising a target supply unit configured to sequentially generate and supply a plurality of droplets as the target to an optical path of the pulse laser light,wherein the processor controls the irradiation frequency by setting relationship between a generation frequency FD of the plurality of droplets from the target supply unit and an emission frequency FL of the pulse laser light from the laser device to FL=FD/N1, where N1 is an integer of 2 or larger, and thereafter, increases the irradiation frequency by setting the relationship to FL=FD/N2, where N2 is an integer of 1 or larger and smaller than N1. 9. The extreme ultraviolet light generation system according to claim 1,wherein the processor increases the irradiation frequency when the second energy parameter is lower than a threshold value. 10. The extreme ultraviolet light generation system according to claim 1,wherein the processor increases the irradiation frequency when operation time of the extreme ultraviolet light generation system reaches a predetermined value. 11. The extreme ultraviolet light generation system according to claim 1,wherein the processor increases the irradiation frequency when the number of output pulses of the extreme ultraviolet light reaches a predetermined value. 12. An extreme ultraviolet light generation system, comprising:a laser device configured to emit pulse laser light;an EUV light concentrating mirror configured to reflect and concentrate extreme ultraviolet light generated by irradiating a target with the pulse laser light; anda processor configured to receive a first energy parameter of the extreme ultraviolet light and control an irradiation frequency of the pulse laser light with which the target is irradiated so that change in a second energy parameter related to energy per unit time of the extreme ultraviolet light reflected by the EUV light concentrating mirror is suppressed,wherein the processor performs first processing of controlling pulse energy of the pulse laser light so as to suppress change in the second energy parameter and second processing of increasing the irradiation frequency and decreasing the pulse energy of the pulse laser light. 13. The extreme ultraviolet light generation system according to claim 12,wherein, in the first processing, the processor increases target pulse energy of the pulse laser light when the second energy parameter is lower than a target value. 14. The extreme ultraviolet light generation system according to claim 12,wherein the processor performs the second processing when target pulse energy of the pulse laser light is higher than a threshold value. 15. The extreme ultraviolet light generation system according to claim 12,wherein the target includes a plurality of droplets that are sequentially generated and supplied to an optical path of the pulse laser light,the plurality of droplets includes a droplet not to be irradiated with the pulse laser light and a droplet to be irradiated with the pulse laser light, andin the second processing, the processor increases the irradiation frequency by increasing a ratio of the number of the droplets to be irradiated with the pulse laser light to the number of the plurality of droplets. 16. The extreme ultraviolet light generation system according to claim 12,further comprising a target supply unit configured to sequentially generate and supply a plurality of droplets as the target to an optical path of the pulse laser light,wherein the processor controls the irradiation frequency by setting relationship between a generation frequency FD of the plurality of droplets from the target supply unit and an emission frequency FL of the pulse laser light from the laser device to FL=FD/N1, where N1 is an integer of 2 or larger, and thereafter in the second processing, increases the irradiation frequency by setting the relationship to FL=FD/N2, where N2 is an integer of 1 or larger and smaller than N1. 17. An electronic device manufacturing method, comprising:generating extreme laser light in an extreme ultraviolet light generation system;emitting the extreme ultraviolet light to an exposure apparatus; andexposing a photosensitive substrate to the extreme ultraviolet light in the exposure apparatus to manufacture an electronic device,the extreme ultraviolet light generation system including a laser device configured to emit pulse laser light, an EUV light concentrating mirror configured to reflect and concentrate the extreme ultraviolet light generated by irradiating a target with the pulse laser light, and a processor configured to receive a first energy parameter of the extreme ultraviolet light and control an irradiation frequency of the pulse laser light with which the target is irradiated so that change in a second energy parameter related to energy per unit time of the extreme ultraviolet light reflected by the EUV light concentrating mirror is suppressed,wherein the first energy parameter includes a combination of one of EUV pulse energy and EUV power and one of EUV light concentration size and EUV emission size, and the second energy parameter includes one of EUV power, EUV power density, and EUV radiation brightness. 18. A method of manufacturing an electronic device, comprising:inspecting a defect of a mask by irradiating the mask with extreme ultraviolet light generated in an extreme ultraviolet light generation system;selecting a mask using a result of the inspection; andexposing and transferring a pattern formed on the selected mask onto a photosensitive substrate,the extreme ultraviolet light generation system including a laser device configured to emit pulse laser light, an EUV light concentrating mirror configured to reflect and concentrate the extreme ultraviolet light generated by irradiating a target with the pulse laser light, and a processor configured to receive a first energy parameter of the extreme ultraviolet light and control an irradiation frequency of the pulse laser light with which the target is irradiated so that change in a second energy parameter related to energy per unit time of the extreme ultraviolet light reflected by the EUV light concentrating mirror is suppressed,wherein the first energy parameter includes a combination of one of EUV pulse energy and EUV power and one of EUV light concentration size and EUV emission size, and the second energy parameter includes one of EUV power, EUV power density, and EUV radiation brightness.