Method for operating a projection exposure apparatus with correction of imaging aberrations induced by the mask

Abstract

The disclosure relates to a method for adapting a projection exposure apparatus for microlithography to a mask having structures with different pitches and/or different structure widths in different structure directions. Wavefront aberrations induced by the mask are reduced by a manipulator of the projection exposure apparatus for microlithography.

1 - 20 . (canceled) 
     
     
         21 . An illumination system, comprising:
 an optical element configured so that, during use of the illumination system, the optical element directs light from a light source to an object plane;   a manipulator; and   a control unit,   wherein:   during use of the illumination system when a mask is present in the object plane, light transmitted through the mask is diffracted by structures on the mask, and   the control unit is configured so that, during use of the control unit, the control unit drives the manipulator to manipulate the optical element and/or a wavefront of light transmitting through the optical element based on information about the mask, the information about the mask comprises information about a pitch of the structures on the mask.   
     
     
         22 . The illumination system of  claim 21 , wherein the control unit is configured so that during use of the illumination system when the mask is present in the object plane, the control unit is configured to drive the manipulator so that pitch-dependent aberrations of wavefront of the light diffracted by the mask is corrected. 
     
     
         23 . The illumination system of  claim 22 , wherein the pitch-dependent aberrations comprise astigmatism. 
     
     
         24 . The illumination system of  claim 21 , wherein the manipulator is configured to set an illumination setting of the illumination system. 
     
     
         25 . The illumination system of  claim 24 , wherein the manipulator is configured to set a freeform illumination. 
     
     
         26 . The illumination system of  claim 21 , wherein the optical element comprises a lens and the manipulator is configured to displace the lens and/or bend the lens. 
     
     
         27 . The illumination system of  claim 21 , wherein the optical element comprises a lens and the manipulator is configured to heat and/or cool the lens. 
     
     
         28 . The illumination system of  claim 21 , wherein the manipulator comprises a multimirror array configured to set a freeform illumination. 
     
     
         29 . The illumination system of  claim 21 , wherein the manipulator comprises diffractive optical elements. 
     
     
         30 . A projection objective, comprising:
 an optical element configured to receive light transmitted through a mask arranged in an object plane of the projection objective to an image plane of the projection objective;   a manipulator; and   a control unit,   wherein:   during use of the projection objective when a mask is present in the object plane, light transmitted through the mask is diffracted by structures on the mask, and the control unit is configured so that, during use of the control unit, the control unit drives the manipulator based on information about the mask to manipulate the optical element and/or a wavefront of light transmitting through the optical element, the information about the mask comprises information about a pitch of the structures on the mask.   
     
     
         31 . A system, comprising the projection objective of  claim 30 , and an immersion medium disposed between the projection objective and the image plane. 
     
     
         32 . The projection objective of  claim 30 , wherein the optical element comprises a lens, and the manipulator is configured to displace and/or bend the lens. 
     
     
         33 . The projection objective of  claim 30 , wherein the optical element comprises a lens, and the manipulator is configured to heat and/or cool the lens. 
     
     
         34 . The projection objective of  claim 30 , wherein the manipulator is configured to provide different manipulator deflections to manipulate a wavefront of light imaged onto the image plane. 
     
     
         35 . The projection objective of  claim 30 , wherein the optical element comprises a mirror and the manipulator is configured to manipulate a mirror in the projection objective. 
     
     
         36 . The projection objective of  claim 30 , wherein the manipulator is configured to exchange a first planar plate in the projection objective for a second planar plate that is aspherized. 
     
     
         37 . The projection objective of  claim 30 , wherein the manipulator is configured to locally heat a planar plate. 
     
     
         38 . The projection objective of  claim 30 , wherein the manipulator is spatially resolving and the optical element is in a pupil plane of the projection objective. 
     
     
         39 . The projection objective of  claim 30 , wherein:
 the information of the mask comprises a first structure direction of the mask, and two different pitches P 1  and P 2  along the first structure direction of the mask, or two different structure widths S 1  and S 2  along the first structure direction of mask;   the control unit is configured to determine a wavefront aberration induced by the different pitches P 1  and P 2  or the different structure widths S 1  and S 2 ; and   the manipulator is set to a first manipulator deflection M 1  which reduces the wavefront aberration induced by the pitch P 1  or the structure width S 1 .   
     
     
         40 . The projection objective of  claim 39 , wherein:
 the wavefront aberration induced by the pitches P 1  and P 2  or the structure widths S 1  and S 2  is different,   the manipulator is configured to be set to a second manipulator deflection M 2  which reduces a wavefront aberration induced by the pitch P 2  or the structure width S 2 , and   the manipulator is set so that αM 1 +(1−α)M 2  where a is a relative weighting of the pitch P 1  with respect to the pitch P 2  or of the structure width S 1  with respect to the structure width S 2 , and where αε[0,1].