Projection objective for microlithography

Abstract

A projection objective for microlithography for imaging a pattern arranged in the object plane of the projection objective into the image plane of the projection objective has at least one polarization splitter device that is operated only once in transmission or reflection. By using this device, polarization-dependent differences in the intensity and response of the light passing through the objective, which lead to a worsening of the imaging quality of the projection objective, can largely be avoided.

1 . A microlithography projection objective for imaging a pattern 
 arranged in an object plane of the projection objective onto an image plane of the projection objective, the projection objective comprising:    a transparent optical element arranged in a vicinity of the image plane;    the transparent optical element comprising a polarization splitter structure operated only once in transmission as rays of a light beam travel from the object plane to the image plane;    wherein the polarization splitter structure transmits substantially only one direction of polarization.    
     
     
         2 . The projection objective according to  claim 1 , wherein the polarization splitter structure is disposed in a location at which light rays incident thereon are convergent and planes of incidence of the convergent light rays are rotationally symmetric to an optical axis of the projection objective, 
 and wherein substantially all the light transmitted by the polarization splitter structure has the same direction of polarization with respect to the plane of incidence of the light on the polarization splitter structure, such that the polarization directions of light transmitted by the polarization splitter structure are substantially rotationally symmetric with respect to the optical axis.    
     
     
         3 . The projection objective according to  claim 2 , wherein the polarization splitter structure transmits only light rays polarized parallel to their planes of incidence, such that radially polarized light is incident on the image plane.  
     
     
         4 . The projection objective according to  claim 1 , wherein the transparent optical element is the final optical element of the projection objective in the beam direction.  
     
     
         5 . The projection objective according to  claim 4 , wherein the transparent optical element is a plane-parallel plate.  
     
     
         6 . The projection objective according to  claim 1 , 
 wherein the transparent optical element is a terminating plate of the projection objective immediately adjacent to the image plane, and    wherein the projection objective further comprises a dielectric multi-layer system disposed on an entry surface of the terminating plate, the multilayer system forming the polarization splitter structure.    
     
     
         7 . The projection objective according to  claim 1 , wherein the polarization splitter structure comprises a polarization-selective dielectric multilayer system.  
     
     
         8 . The projection objective according to  claim 1 , wherein the transparent optical element is interchangeable.  
     
     
         9 . The projection objective according to  claim 1 , wherein the projection objective is configured to generate tangential polarization in the image plane.  
     
     
         10 . The projection objective according to  claim 1 , wherein the projection objective is a catadioptric projection objective comprising at least one concave mirror.  
     
     
         11 . The projection objective according to  claim 1 , further comprising: 
 a catadioptric first objective part comprising a concave mirror and a beam deflection device, and,    disposed behind the beam deflection device, a dioptric second objective part.    
     
     
         12 . The projection objective according to  claim 11 , wherein the beam deflection device comprises: 
 a first mirror surface for deflecting radiation from the object plane toward the concave mirror, and    a second mirror surface for deflecting radiation from the concave mirror toward the second objective part.    
     
     
         13 . A microlithography projection objective for imaging a pattern arranged in an object plane of the projection objective into an image plane of the projection objective, the projection objective comprising: 
 at least one optical element comprising a polarization splitter structure through which light passes only once between the object plane and the image plane, and which transmits only one direction of polarization;    wherein the projection objective is configured to generate tangential polarization in the image plane.    
     
     
         14 . The projection objective according to  claim 13 , wherein the projection objective is a catadioptric projection objective comprising at least one concave mirror.  
     
     
         15 . The projection objective according to  claim 13 , further comprising: 
 a catadioptric first objective part comprising a concave mirror and a beam deflection device, and,    disposed behind the beam deflection device, a dioptric second objective part.    
     
     
         16 . The projection objective according to  claim 15 , wherein the beam deflection device comprises 
 a first mirror surface for deflecting radiation from the object plane toward the concave mirror, and    a second mirror surface for deflecting radiation from the concave mirror toward the second objective part.