Illumination system

Abstract

A system and method are used to substantially homogenize and remove at least some coherence from a beam of radiation.

1 . An optical apparatus, comprising: 
 a coherence remover having a plurality of channels; and    a homogenizer that converts a beam of radiation into a plurality of beams of radiation, such that each respective ones of the plurality of beams of radiation passes through a respective one of the plurality of channels of the coherence remover.    
   
   
       2 . The optical apparatus of  claim 1 , further comprising: 
 an optical element located between the homogenizer and the coherence remover, the optical element being arranged to couple the plurality of beams of radiation output from the homogenizer into the respective channels of the coherence remover.    
   
   
       3 . The optical apparatus of  claim 1 , wherein the coherence remover comprises: 
 a plurality of transmissive optical elements, the optical elements having different path lengths, such that respective ones of the plurality of radiation beams that are initially coherent with one another when they enter the coherence remover are no longer coherent with one another when they exit the coherence remover.    
   
   
       4 . The optical apparatus of  claim 3 , wherein the transmissive optical elements are arranged in a stepped series.  
   
   
       5 . The optical apparatus of  claim 3 , wherein the transmissive optical elements are arranged in a two dimensional array.  
   
   
       6 . The optical apparatus of  claim 1 , further comprising: 
 a convex lens arranged to focus the beams of radiation, such that the beams of radiation are combined with one another to form a single beam of radiation.    
   
   
       7 . The optical apparatus of  claim 6 , wherein: 
 the optical apparatus forms part of a lithographic apparatus;    the lithographic apparatus comprises a patterning array that comprises an array of individually controllable elements; and    the single beam or a plurality of beams generated from the single beam is directed to the patterning array.    
   
   
       8 . The optical apparatus of  claim 1 , wherein: 
 the optical apparatus forms part of a lithographic apparatus; and    the lithographic apparatus comprises a patterning array that comprises an array of individually controllable elements.    
   
   
       9 . The optical apparatus of  claim 1 , wherein the homogenizer comprises at least one homogenizer plate.  
   
   
       10 . The optical apparatus of  claim 1 , wherein the homogenizer comprises a pair of parallel homogenizer plates.  
   
   
       11 . The optical apparatus of  claim 1 , wherein the homogenizer comprises a pair of homogenizer plates which are angled relative to one another.  
   
   
       12 . The optical apparatus of  claim 11 , wherein the homogenizer plates are rotatably mounted such that the angular orientation of the homogenizer plates is adjustable.  
   
   
       13 . An optical apparatus, comprising: 
 a homogenizer; and    a coherence remover that converts a beam of radiation into a plurality of beams of radiation, such that each respective ones of the plurality of beams of radiation passes through the homogenizer.    
   
   
       14 . A lithographic apparatus, comprising: 
 an illumination system that conditions a radiation beam and comprises a coherence remover;    an array of individually controllable elements that modulate the radiation beam; and    a projection system that projects the modulated beam onto a target portion of a substrate.    
   
   
       15 . The lithographic apparatus of  claim 14 , wherein the illumination system forms a plurality of the beams and the coherence remover comprises: 
 a plurality of channels configured to receive respective ones of the plurality of beams.    
   
   
       16 . The lithographic apparatus of  claim 14 , wherein the coherence remover comprises: 
 a plurality of transmissive optical elements having different optical path lengths.    
   
   
       17 . The lithographic apparatus of  claim 16 , wherein the transmissive optical elements are arranged in a stepped series.  
   
   
       18 . The lithographic apparatus of  claim 16 , wherein the transmissive optical elements are arranged in a two dimensional array.  
   
   
       19 . The lithographic apparatus of  claim 15 , wherein the lithographic apparatus further comprises: 
 a homogenizer that converts the radiation beam into a plurality of radiation beams;    wherein the coherence remover comprises a plurality of channels that pass respective ones of the plurality of beams of radiation.    
   
   
       20 . The lithographic apparatus of  claim 14 , wherein the lithographic apparatus further comprises a homogenizer.  
   
   
       21 . The lithographic apparatus of  claim 20 , wherein the coherence remover is configured to convert the radiation beam into a plurality of radiation beams, such that each respective ones of the plurality of beams of radiation passes through the homogenizer.  
   
   
       22 . The lithographic apparatus of  claim 20 , wherein the homogenizer comprises at least one homogenizer plate.  
   
   
       23 . The lithographic apparatus of  claim 20 , wherein the homogenizer comprises a pair of parallel homogenizer plates.  
   
   
       24 . The lithographic apparatus of  claim 20 , wherein the homogenizer comprises a pair of homogenizer plates which are angled relative to one another.  
   
   
       25 . The optical apparatus of  claim 24 , wherein the homogenizer plates are rotatably mounted such that the angular orientation of the homogenizer plates is adjustable.  
   
   
       26 . The lithographic apparatus according to  claim 14 , wherein the projection system comprises: 
 an array of lenses that are arranged to direct individual beams of radiation onto the substrate.    
   
   
       27 . A lithographic apparatus for manufacturing flat panel displays, comprising: 
 an illumination system that conditions a radiation beam and comprises a coherence remover;    a mask or an array of individually controllable elements capable of modulating the radiation beam; and    a projection system configured to project the modulated radiation beam onto a target portion of a substrate.    
   
   
       28 . The lithographic apparatus of  claim 27 , wherein the coherence remover comprises a plurality of transmissive optical elements having different optical path lengths.  
   
   
       29 . The lithographic apparatus of  claim 28 , wherein the transmissive optical elements are arranged in a stepped series.  
   
   
       30 . The lithographic apparatus of  claim 28 , wherein the transmissive optical elements are arranged in a two dimensional array.  
   
   
       31 . A homogenizer, comprising: 
 first and second homogenizer plates that are angled relative to one another.    
   
   
       32 . The homogenizer of  claim 31 , wherein the homogenizer plates are rotatably mounted, such that the angular orientation of the homogenizer plates is adjustable.