System and method for generating extreme ultra violet light

Abstract

A system for generating extreme ultraviolet light, in which a target material inside a chamber is irradiated with a laser beam to be turned into plasma, includes a first laser apparatus configured to output a first laser beam, a second laser apparatus configured to output a pedestal and a second laser beam, and a controller connected to the first and second laser apparatuses and configured to cause the first laser beam to be outputted first, the pedestal to be outputted after the first laser beam, and the second laser beam having higher energy than the pedestal to be outputted after the pedestal.

What is claimed is: 
     
         1 . A system for generating extreme ultraviolet light in which a target material inside a chamber is irradiated with a laser beam to be turned into plasma, the system comprising:
 a first laser apparatus configured to output a first laser beam;   a second laser apparatus configured to output a pedestal and a second laser beam; and   a controller connected to the first and second laser apparatuses and configured to cause the first laser beam to be outputted first, the pedestal to be outputted after the first laser beam, and the second laser beam having higher energy than the pedestal to be outputted after the pedestal.   
     
     
         2 . The system according to  claim 1 , further comprising a pedestal control device configured to control energy of the pedestal. 
     
     
         3 . The system according to  claim 2 , wherein the pedestal control device is configured to control an energy ratio of the pedestal to energy of the second laser beam. 
     
     
         4 . The system according to  claim 2 , wherein the pedestal control device is configured to control energy of the pedestal such that the energy ratio falls within a range of 1% to 10%. 
     
     
         5 . The system according to  claim 2 , wherein the pedestal control device is configured to control energy of the pedestal such that the energy of the pedestal falls within a range of 1 mJ to 10 mJ. 
     
     
         6 . The system according to  claim 2 , wherein the pedestal control device is arranged in a beam path in the second laser apparatus and includes one or more optical shutters configured to vary transmittance thereof in accordance with an applied voltage value. 
     
     
         7 . The system according of  claim 2 , wherein the pedestal control device is arranged in a beam path in the second laser apparatus and includes one or more saturable absorber devices containing a saturable absorber gas. 
     
     
         8 . The system according to  claim 6 , wherein the one or more optical shutters include:
 one or more optical elements configured to change a polarization direction of an incident laser beam in accordance with an applied voltage value; and   a polarization optical element configured to reflect a predetermined polarization component of a laser beam transmitted through the one or more optical elements and transmit the other polarization component.   
     
     
         9 . The system according to  claim 2 , further comprising a waveform detection device configured to detect pulse waveforms of the pedestal and the second laser beam,
 wherein the controller is configured to control the pedestal control device based on the pulse waveforms detected by the waveform detection device.   
     
     
         10 . The system according to  claim 9 , wherein the controller is configured to:
 calculate the energy ratio or the energy of the pedestal from the pulse waveforms detected by the waveform detection device, and   control the pedestal control device based on the calculated energy ratio or the energy of the pedestal.   
     
     
         11 . The system according to  claim 2 , further comprising an energy detector configured to detect energy of extreme ultraviolet light,
 wherein the controller is configured to control the pedestal control device based on the energy of the extreme ultraviolet light detected by the energy detector.   
     
     
         12 . The system according to  claim 2 , further comprising:
 a waveform detection device configured to detect pulse waveforms of the pedestal and the second laser beam; and   an energy detector configured to detect energy of extreme ultraviolet light,   wherein the controller is configured to:   calculate energy conversion efficiency into the extreme ultraviolet light based on the pulse waveforms detected by the waveform detection device and the energy detected by the energy detector, and   control the pedestal control device based on the calculated energy conversion efficiency.   
     
     
         13 . The system according to  claim 12 , wherein the controller is configured to:
 calculate the energy ratio or the energy of the pedestal from the pulse waveforms detected by the waveform detection device to thereby control the pedestal control device, and   calculate energy conversion efficiency into the extreme ultraviolet light corresponding to the energy ratio or the energy of the pedestal at a plurality of points within a first range where the energy ratio or the energy of the pedestal serves as a parameter to thereby control the pedestal control device such that the energy ratio or the energy of the pedestal falls within a second range where the calculated energy conversion efficiency is equal to or higher than predetermined energy conversion efficiency.   
     
     
         14 . A method for generating extreme ultraviolet light in which a target material inside a chamber is irradiated with a laser beam to be turned into plasma, the method comprising:
 irradiating a target material with a first laser beam, a second laser beam, and a third laser beam having energy higher than the second laser beam.   
     
     
         15 . The method according to  claim 14 , further comprising:
 detecting pulse waveforms of the second laser beam and the third laser beam; and   controlling energy of the second laser beam based on the detected pulse waveforms.   
     
     
         16 . The method according to  claim 14 , further comprising:
 detecting energy of the extreme ultraviolet light; and   controlling energy of the second laser beam based on the detected energy of the extreme ultraviolet light.   
     
     
         17 . The system according to  claim 2 , wherein the pedestal control device is configured to control an energy ratio of the pedestal to energy of the second laser beam. 
     
     
         18 . The system according to  claim 3 , wherein the pedestal control device is configured to control energy of the pedestal such that the energy ratio falls within a range of 1% to 10%. 
     
     
         19 . The system according to  claim 3 , wherein the pedestal control device is configured to control energy of the pedestal such that the energy of the pedestal falls within a range of 1 mJ to 10 mJ. 
     
     
         20 . The system according to  claim 3 , wherein the pedestal control device is arranged in a beam path in the second laser apparatus and includes one or more optical shutters configured to vary transmittance thereof in accordance with an applied voltage value. 
     
     
         21 . The system according to  claim 4 , wherein the pedestal control device is arranged in a beam path in the second laser apparatus and includes one or more optical shutters configured to vary transmittance thereof in accordance with an applied voltage value. 
     
     
         22 . The system according to  claim 5 , wherein the pedestal control device is arranged in a beam path in the second laser apparatus and includes one or more optical shutters configured to vary transmittance thereof in accordance with an applied voltage value. 
     
     
         23 . The system according of  claim 3 , wherein the pedestal control device is arranged in a beam path in the second laser apparatus and includes one or more saturable absorber devices containing a saturable absorber gas. 
     
     
         24 . The system according of  claim 4 , wherein the pedestal control device is arranged in a beam path in the second laser apparatus and includes one or more saturable absorber devices containing a saturable absorber gas. 
     
     
         25 . The system according of  claim 5 , wherein the pedestal control device is arranged in a beam path in the second laser apparatus and includes one or more saturable absorber devices containing a saturable absorber gas. 
     
     
         26 . The system according to  claim 3 , further comprising a waveform detection device configured to detect pulse waveforms of the pedestal and the second laser beam, wherein the controller is configured to control the pedestal control device based on the pulse waveforms detected by the waveform detection device. 
     
     
         27 . The system according to  claim 4 , further comprising a waveform detection device configured to detect pulse waveforms of the pedestal and the second laser beam, wherein the controller is configured to control the pedestal control device based on the pulse waveforms detected by the waveform detection device. 
     
     
         28 . The system according to  claim 5 , further comprising a waveform detection device configured to detect pulse waveforms of the pedestal and the second laser beam, wherein the controller is configured to control the pedestal control device based on the pulse waveforms detected by the waveform detection device. 
     
     
         29 . The system according to  claim 3 , further comprising an energy detector configured to detect energy of extreme ultraviolet light,
 wherein the controller is configured to control the pedestal control device based on the energy of the extreme ultraviolet light detected by the energy detector.   
     
     
         30 . The system according to  claim 4 , further comprising an energy detector configured to detect energy of extreme ultraviolet light,
 wherein the controller is configured to control the pedestal control device based on the energy of the extreme ultraviolet light detected by the energy detector.   
     
     
         31 . The system according to  claim 5 , further comprising an energy detector configured to detect energy of extreme ultraviolet light,
 wherein the controller is configured to control the pedestal control device based on the energy of the extreme ultraviolet light detected by the energy detector.   
     
     
         32 . The system according to  claim 3 , further comprising:
 a waveform detection device configured to detect pulse waveforms of the pedestal and the second laser beam; and   an energy detector configured to detect energy of extreme ultraviolet light,   wherein the controller is configured to:   calculate energy conversion efficiency into the extreme ultraviolet light based on the pulse waveforms detected by the waveform detection device and the energy detected by the energy detector, and   control the pedestal control device based on the calculated energy conversion efficiency.   
     
     
         33 . The system according to  claim 4 , further comprising:
 a waveform detection device configured to detect pulse waveforms of the pedestal and the second laser beam; and   an energy detector configured to detect energy of extreme ultraviolet light,   wherein the controller is configured to:   calculate energy conversion efficiency into the extreme ultraviolet light based on the pulse waveforms detected by the waveform detection device and the energy detected by the energy detector, and   control the pedestal control device based on the calculated energy conversion efficiency.   
     
     
         34 . The system according to  claim 5 , further comprising:
 a waveform detection device configured to detect pulse waveforms of the pedestal and the second laser beam; and   an energy detector configured to detect energy of extreme ultraviolet light,   wherein the controller is configured to:   calculate energy conversion efficiency into the extreme ultraviolet light based on the pulse waveforms detected by the waveform detection device and the energy detected by the energy detector, and   control the pedestal control device based on the calculated energy conversion efficiency.