Wavefront splitting element for EUV light and phase measuring apparatus using the same

Abstract

A wavefront splitting element includes a diffraction grating for splitting light into multiple beams including transmitting light and reflected light.

1 . A wavefront splitting element comprising a diffraction grating for splitting light into transmitting light and reflected light.  
     
     
         2 . A wavefront splitting element according to  claim 1 , wherein said light is extreme ultraviolet light.  
     
     
         3 . A wavefront splitting element according to  claim 1 , wherein said wavefront splitting element uses a diffraction effect obtainable by a repetitive pattern comprised of a transmission part and a reflection part.  
     
     
         4 . A phase measuring apparatus comprising an interferometer having a wavefront splitting element, said element including a diffraction grating for splitting the EUV light into transmitting light and reflected light.  
     
     
         5 . A phase measuring apparatus that measures phase information dependent on an angle incident on a film applied onto an object to be tested based on the interference information, said phase measuring apparatus comprising: 
 a beam splitter using a diffraction grating to split a beam from a light source into multiple beams including transmitting light and reflected light;    a reflecting mechanism for condensing one beam that has been split by said beam splitter, and introduces the beam to the object as well as introducing detection light reflected from the object into said beam splitter;    a reference plate for reflecting another beam that has been split by said beam splitter, and brings it into said beam splitter as reference light;    an imaging system for forming, on a predetermined surface, interference light obtained when the detection light and the reference light are superimposed by said beam splitter; and    a detector for detecting the interference information on the predetermined surface.    
     
     
         6 . A phase measuring apparatus that measures phase information dependent on an angle incident on a film applied onto an object to be tested based on the interference information, said phase measuring apparatus comprising: 
 a beam splitter using a diffraction grating to split a beam from a light source into multiple beams including transmitting light and reflected light;    a reflecting mechanism for condensing one beam that has been split by said beam splitter, and introduces the beam to the object as well as introducing detection light reflected from the object into said beam splitter; and    a detector, including another diffraction grating, for detecting the interference information from the detection light via said beam splitter.    
     
     
         7 . An exposure apparatus comprising an optical element measured by using a phase measuring apparatus, said apparatus comprising an interferometer having a wavefront splitting element, said element including a diffraction grating for splitting light into transmitting light and reflected light.  
     
     
         8 . An exposure apparatus comprising an optical element measured by using a phase measuring apparatus that measures phase information dependent on an angle incident on a film applied onto the optical element based on the interference information, 
 wherein said phase measuring apparatus comprises:    a beam splitter using a diffraction grating to split a beam from a light source into multiple beams including transmitting light and reflected light;    a reflecting mechanism for condensing one beam that has been split by said beam splitter, and introduces the beam to the optical element as well as introducing detection light reflected from the optical element into said beam splitter;    a reference plate for reflecting another beam that has been split by said beam splitter, and brings it into said beam splitter as reference light;    an imaging system for forming, on a predetermined surface, interference light obtained when the detection light and the reference light are superimposed by said beam splitter; and    a detector for detecting the interference information on the predetermined surface.    
     
     
         9 . An exposure apparatus comprising an optical element measured by using a phase measuring apparatus that measures phase information dependent on an angle incident on a film applied onto the optical element based on the interference information, 
 wherein said phase measuring apparatus comprises:    a beam splitter using a diffraction grating to split a beam from a light source into multiple beams including transmitting light and reflected light;    a reflecting mechanism for condensing one beam that has been split by said beam splitter, and introduces the beam to the optical element as well as introducing detection light reflected from the optical element into said beam splitter; and    a detector, including another diffraction grating, for detecting the interference information from the detection light via said beam splitter.    
     
     
         10 . A device fabrication method comprising the steps of: 
 exposing onto a target by using an exposure apparatus comprising an optical element measured by using a phase measuring apparatus that splits an optical path of a beam incident onto the optical element from a beam reflected from the optical element by using a wavefront splitting element a diffraction grating for splitting light into transmitting light and reflected light; and    developing the exposed target.    
     
     
         11 . A device fabrication method comprising the steps of: 
 exposing onto a target by using an exposure apparatus comprising an optical element measured by using a phase measuring apparatus that measures phase information dependent on an angle incident on a film applied onto the optical element based on the interference information, wherein said phase measuring apparatus comprises a beam splitter using a diffraction grating to split a beam from a light source into multiple beams including transmitting light and reflected light, a reflecting mechanism for condensing one beam that has been split by said beam splitter, and introduces the beam to the optical element as well as introducing detection light reflected from the optical element into said beam splitter, a reference plate for reflecting another beam that has been split by said beam splitter, and brings it into said beam splitter as reference light, an imaging system for forming, on a predetermined surface, interference light obtained when the detection light and the reference light are superimposed by said beam splitter, and a detector for detecting the interference information on the predetermined surface; and    developing the exposed target.    
     
     
         12 . A device fabrication method comprising the steps of: 
 exposing onto a target by using an exposure apparatus comprising an optical element measured by using a phase measuring apparatus that measures phase information dependent on an angle incident on a film applied onto the optical element based on the interference information, wherein said phase measuring apparatus comprises a beam splitter using a diffraction grating to split a beam from a light source into multiple beams including transmitting light and reflected light, a reflecting mechanism for condensing one beam that has been split by said beam splitter, and introduces the beam to the optical element as well as introducing detection light reflected from the optical element into said beam splitter, and a detector, including another diffraction grating, for detecting the interference information from the detection light via said beam splitter; and    developing the exposed target.