Projection objective of a microlithographic projection exposure apparatus designed for EUV and a method of optically adjusting a projection objective

Abstract

The invention concerns a projection objective of a microlithographic projection exposure apparatus designed for EUV, for imaging an object plane illuminated in operation of the projection exposure apparatus into an image plane, wherein the projection objective has at least one mirror segment arrangement ( 160, 260, 280, 310, 410, 500 ) comprising a plurality of separate mirror segments ( 161 - 163; 261 - 266, 281 - 284; 311, 312; 411, 412; 510 - 540 ); and wherein associated with the mirror segments of the same mirror segment arrangement are partial beam paths which are different from each other and which respectively provide for imaging of the object plane (OP) into the image plane (IP), wherein said partial beam paths are superposed in the image plane (IP) and wherein at least two partial beams which are superposed in the same point in the image plane (IP) were reflected by different mirror segments of the same mirror segment arrangement.

1 .- 24 . (canceled) 
     
     
         25 . A projection objective configured to image an object plane into an image plane, the projection objective comprising:
 a first mirror segment arrangement comprising a first plurality of separate mirror segments,   wherein during use of the projection objective:
 partial beam paths which are different from each other are associated with the first mirror segments; 
 the partial beams image the object plane into the image plane; 
 the partial beam paths are superposed in the image plane; and 
 at least two partial beams are reflected from different mirror segments and are superposed on the same point in the image plane; and 
   wherein the projection objective is an EUV microlithographic projection objective.   
     
     
         26 . The projection objective of  claim 25 , wherein, along a path of a partial beam from the object plane to the image plane, the first mirror segment arrangement is a last reflecting arrangement of the projection objective. 
     
     
         27 . The projection objective of  claim 25 , wherein the first mirror segment arrangement is a reflecting arrangement of the projection objective having a maximum of total optically effective surface size. 
     
     
         28 . The projection objective of  claim 25 , wherein the first plurality of mirror segments comprises at least three mirror segments. 
     
     
         29 . The projection objective of  claim 25 , wherein the first plurality of mirror segments respectively form with each other a continuous reflecting surface interrupted only by transitional regions which are optionally present between adjacent mirror segments. 
     
     
         30 . The projection objective of  claim 25 , wherein the first plurality of mirror segments respectively form with each other a reflecting surface interrupted only by transitional regions between adjacent mirror segments. 
     
     
         31 . The projection objective of  claim 25 , further comprising a second mirror segment arrangement comprising a second plurality of mirror segments, wherein during use of the projection objective:
 beam paths which are different from each other are associated with the mirror segments of the same mirror segment arrangement;   the beam paths image the object plane into the image plane; and   the beam paths are superposed in the image plane.   
     
     
         32 . The projection objective of  claim 31 , wherein, during use of the projection objective, a mirror segment of the first plurality of mirror segments is associated with a mirror segment of the second plurality of mirror segments in a pair-wise relationship with respect to one of the partial beam paths. 
     
     
         33 . The projection objective of  claim 25 , further comprising a shutter arrangement configured so that during use of the projection objective illumination of the first mirror segment arrangement is selectively limited to different mirror segments of the first plurality of mirror segments. 
     
     
         34 . The projection objective of  claim 25 , wherein at least two mirror segments of the first mirror segment arrangement are movable relative to each other. 
     
     
         35 . The projection objective of  claim 25 , further comprising a shutter arrangement configured so that a space between mirror segments of the first plurality of mirror segments is at least partially arranged in a shadow of said obscuration shutter arrangement. 
     
     
         36 . A projection objective configured to image an object plane into an image plane, the projection objective comprising:
 a plurality of mirrors including a mirror having a maximum size, the mirror having the maximum size comprising a mirror segment arrangement comprising a plurality of separate mirror segments,   wherein the projection objective is an EUV microlithographic projection objective.   
     
     
         37 . A projection objective configured to image an object plane into an image plane, the projection objective comprising:
 a mirror segment arrangement comprising a plurality of separate mirror segments; and   a shutter arrangement configured so that, during use of the projection objective, a space between mirror segments of the mirror segment arrangement is at least partially arranged in a shadow of the shutter arrangement.   
     
     
         38 . The projection objective of  claim 37 , wherein the space is rotationally symmetric. 
     
     
         39 . The projection objective of  claim 37 , wherein the shutter arrangement is rotationally symmetric. 
     
     
         40 . The projection objective of  claim 37 , wherein the shutter arrangement is a plane of the projection objective in which a parameter P(M) which is defined as: 
       
         
           
             
               
                 
                   P 
                    
                   
                     ( 
                     M 
                     ) 
                   
                 
                 = 
                 
                   
                     D 
                      
                     
                       ( 
                       SA 
                       ) 
                     
                   
                   
                     
                       D 
                        
                       
                         ( 
                         SA 
                         ) 
                       
                     
                     + 
                     
                       D 
                        
                       
                         ( 
                         CR 
                         ) 
                       
                     
                   
                 
               
               , 
             
           
         
         and wherein P(M) is at least 0.8, D(SA) is a subaperture diameter, and D(CR) is a maximum principal ray spacing defined over all field points of the optically used field on an optical surface M in the plane. 
       
     
     
         41 . The projection objective of  claim 37 , wherein the projection objective has an optical axis, the shutter arrangement is of n-fold symmetry with respect to the optical axis, and n is a natural number greater than zero. 
     
     
         42 . A method of producing a projection objective of an EUV microlithographic projection exposure apparatus configured to image an object plane into an image plane, the projection objective comprising a plurality of mirrors, at least one of the plurality of mirrors comprising a plurality of separate mirror segments, the plurality of separate mirror segments comprising a first mirror segment and a second mirror segment which is different from the first mirror segment, the method comprising:
 reflecting a first partial beam from the first mirror segment;   reflecting a second partial beam from the second mirror segment; and   superposing the first and second partial beams in the image plane.   
     
     
         43 . A method of optically adjusting a projection objective of a microlithographic projection exposure apparatus, the projection objective comprising a plurality of mirrors, the projection objective comprising a mirror segment arrangement comprising a plurality of separate mirror segments, the method comprising:
 adjusting an orientation of the mirror segments in a first orientation in which a first subset of mirror segments image an object plane of the projection objective into an image plane of the projection objective; and   adjusting an orientation of the mirror segments in a first orientation in which a second subset of mirror segments image an object plane of the projection objective into an image plane of the projection objective,   wherein the first subset of mirror segments is not identical to the second subject of mirror segments.   
     
     
         44 . An arrangement configured to optically adjust a microlithographic projection objective comprising a plurality of mirrors, the projection objective comprising a mirror segment arrangement comprising a plurality of separate mirror segments, the arrangement comprising:
 a variable shutter arrangement configured to selectively illuminate one or more of the mirror segments during use of the arrangement.