Catadioptric projection objective with pupil correction

Abstract

A catadioptric projection objective includes a plurality of optical elements arranged to image an off-axis object field arranged in an object surface onto an off-axis image field arranged in an image surface of the projection objective. The optical elements form: a first, refractive objective part that can generate a first intermediate image from radiation coming from the object surface and including a first pupil surface; a second objective part including at least one concave mirror that can image the first intermediate image into a second intermediate image and including a second pupil surface optically conjugated to the first pupil surface; and a third objective part that can image the second intermediate image onto the image surface and including a third pupil surface optically conjugated to the first and second pupil surface. The optical elements are arranged between the object surface and the first pupil surface form a Fourier lens group which includes a negative lens group arranged optically close to the first pupil surface.

1 . A projection objective having an optical axis, the projection objective comprising:
 a plurality of optical elements arranged to image an object field arranged in an object surface of the projection objective onto an image field arranged in an image surface of the projection objective, the object field being entirely outside the optical axis of the projection objective, the image field being entirely outside the optical axis of the projection objective, and the optical elements forming:
 a first, refractive objective part configured to generate a first intermediate image from radiation coming from the object surface, the first, refractive objective part including a first pupil surface; 
 a second objective part comprising at least one concave mirror configured to image the first intermediate image into a second intermediate image, the second objective part including a second pupil surface optically conjugated to the first pupil surface; and 
 a third objective part configured to image the second intermediate image onto the image surface, the third object part including a third pupil surface optically conjugated to the first and second pupil surfaces; and 
   a correcting element,   wherein:
 optical elements arranged between the object surface and the first pupil surface form a Fourier lens group that comprises a negative lens group arranged optically close to the first pupil surface; 
 the correcting element is in a space at or optically close to the first pupil surface, or the correcting element can be inserted into the space at or optically close to the first pupil surface; and 
 the projection objective is a catadioptric projection objective. 
   
     
     
         2 . The projection objective according to  claim 1 , wherein the projection objective is configured to be used in a microlithography projection-exposure system. 
     
     
         3 . The projection objective according to  claim 1 , wherein the correcting element is a plane plate having at least one aspheric surface. 
     
     
         4 . The projection objective according to  claim 1 , wherein:
 the projection objective is configured to be used in a microlithography projection-exposure system; and   when the projection objective is in the microlithography projection-exposure system, the correcting element can be exchanged with another correcting element having a different shape without removing the projection objective from the microlithography projection-exposure system.   
     
     
         5 . The projection objective according to  claim 1 , wherein the correcting element is configured to be moved or tilted relative to a nearest pupil position. 
     
     
         6 . The projection objective according to  claim 1 , wherein the negative lens group comprises a biconcave negative lens immediately upstream of the first pupil surface along a direction that the radiation propagates through the projection objective. 
     
     
         7 . The projection objective according to  claim 1 , wherein the negative lens group is a single biconcave negative lens arranged immediately upstream of the first pupil surface along a direction that the radiation propagates through the projection objective so that no positive lens is arranged between the biconcave negative lens and the first pupil surface. 
     
     
         8 . The projection objective according to  claim 1 , wherein the Fourier lens group consists of:
 a first positive lens group immediately down-stream of the object surface along a direction that the radiation propagates through the projection objective;   a first negative lens group immediately following the first positive lens group along the direction that the radiation propagates through the projection objective;   a second positive lens group immediately following the first negative lens group along a direction that the radiation propagates through the projection objective; and   a second negative lens group immediately following the second positive lens group along the direction that the radiation propagates through the projection objective, the second negative lens group being arranged optically close to the first pupil surface.   
     
     
         9 . The projection objective according to  claim 8 , wherein the first negative lens group is arranged optically close to the object surface in a region where the condition |RHR|>0.5 holds, and RHR is a ray height ratio. 
     
     
         10 . The projection objective according to  claim 8 , wherein the first negative lens group comprises a negative meniscus lens having a concave surface facing the object surface. 
     
     
         11 . The projection objective according to  claim 1 , further comprising an aperture stop positioned at the first pupil surface. 
     
     
         12 . The projection objective according to  claim 1 , wherein the third objective part comprises between the third pupil surface and the image surface in this order along a direction that the radiation propagates through the projection objective:
 a front positive lens group;   a zone lens having negative refractive power at least in a peripheral zone around the optical axis of the projection objective; and   a rear positive lens group comprising a last optical element of the projection objective immediately upstream of the image surface along the light propagation direction of the projection objective.   
     
     
         13 . A projection objective having an optical axis, the projection objective comprising:
 a plurality of optical elements arranged to image an object field arranged in an object surface of the projection objective onto an image field arranged in an image surface of the projection objective, the object field being entirely outside the optical axis of the projection objective, the image field being entirely outside the optical axis of the projection objective, and the optical elements forming:
 a first, refractive objective part configured to generate a first intermediate image from radiation coming from the object surface, the first, refractive objective part including a first pupil surface; 
 a second objective part comprising at least one concave mirror configured to image the first intermediate image into a second intermediate image, the second objective part including a second pupil surface optically conjugated to the first pupil surface; and 
 a third objective part configured to image the second intermediate image onto the image surface, the third object part including a third pupil surface optically conjugated to the first and second pupil surfaces, 
   wherein:
 optical elements arranged between the object surface and the first pupil surface form a Fourier lens group that comprises a negative lens group arranged optically close to the first pupil surface; 
 the Fourier lens group is configured such that a Petzval radius R P  at the first pupil surface satisfies the condition: |R P |>150 mm; and
 the projection objective is a catadioptric projection objective. 
 
   
     
     
         14 . The projection objective according to  claim 13 , wherein the projection objective is configured to be used in a microlithography projection-exposure system. 
     
     
         15 . The projection objective according to  claim 13 , wherein the negative lens group comprises a biconcave negative lens immediately upstream of the first pupil surface along a direction that the radiation propagates through the projection objective. 
     
     
         16 . The projection objective according to  claim 13 , wherein the negative lens group is a single biconcave negative lens arranged immediately upstream of the first pupil surface along a direction that the radiation propagates through the projection objective so that no positive lens is arranged between the biconcave negative lens and the first pupil surface. 
     
     
         17 . The projection objective according to  claim 13 , wherein the Fourier lens group consists of:
 a first positive lens group immediately down-stream of the object surface along a direction that the radiation propagates through the projection objective;   a first negative lens group immediately following the first positive lens group along the direction that the radiation propagates through the projection objective;   a second positive lens group immediately following the first negative lens group along a direction that the radiation propagates through the projection objective; and   a second negative lens group immediately following the second positive lens group along the direction that the radiation propagates through the projection objective, the second negative lens group being arranged optically close to the first pupil surface.   
     
     
         18 . The projection objective according to  claim 13 , further comprising an aperture stop positioned at the first pupil surface. 
     
     
         19 . The projection objective according to  claim 13 , wherein the third objective part comprises between the third pupil surface and the image surface in this order along a direction that the radiation propagates through the projection objective:
 a front positive lens group;   a zone lens having negative refractive power at least in a peripheral zone around the optical axis of the projection objective; and   a rear positive lens group comprising a last optical element of the projection objective immediately upstream of the image surface along the light propagation direction of the projection objective.   
     
     
         20 . A system, comprising:
 an illumination system; and   a projection objective according to  claim 1 ,   wherein the system is a microlithography projection-exposure system.