Method for correcting a lithography projection objective, and such a projection objective

Abstract

A method for correcting at least one image defect of a projection objective of a lithography projection exposure machine, the projection objective comprising an optical arrangement composed of a plurality of lenses and at least one mirror, the at least one mirror having an optically operative surface that can be defective and is thus responsible for the at least one image defect, comprises the steps of: at least approximately determining a ratio VM of principal ray height h M H to marginal ray height h M R at the optically operative surface of the at least one mirror, at least approximately determining at least one optically operative lens surface among the lens surfaces of the lenses, at which the magnitude of a ratio VL of principal ray height h L H to marginal ray height h L R comes at least closest to the ratio VM, and selecting the at least one determined lens surface for the correction of the image defect.

1 . A method for correcting at least one image defect of a projection objective of a lithography projection exposure machine, said projection objective comprising an optical arrangement composed of a plurality of lenses and at least one mirror, said at least one mirror having an optically operative surface that can be defective and is thus responsible for said at least one image defect, comprising the steps of: 
 at least approximately determining a ratio VM of principal ray height h M H to marginal ray height h M R at said optically operative surface of said at least one mirror,    at least approximately determining at least one optically operative lens surface among lens surfaces of said lenses, at which the magnitude of a ratio VL of principal ray height h L H to marginal ray height h L R comes at least closest to said ratio VM, and    selecting said at least one determined lens surface for said correction of said image defect.    
     
     
         2 . The method of  claim 1 , wherein said ratio VL has a same sign as said ratio VM at said at least one selected lens surface.  
     
     
         3 . The method of  claim 2 , wherein said at least one mirror is arranged in vicinity of a field plane.  
     
     
         4 . The method of  claim 1 , wherein said optical arrangement has at least one mirror that is arranged in vicinity of a pupil plane of said projection objective, and wherein at least one lens surface that is arranged in vicinity of a pupil plane of said projection objective is selected for said correction.  
     
     
         5 . The method of  claim 1 , wherein said optical arrangement has at least two mirrors that are arranged in vicinity of at least one field plane of said projection objective, and at which said ratios VM 1  and VM 2  have different signs, and wherein at least two lens surfaces that are arranged in vicinity of at least one field plane of said projection objective and at which said ratios VL 1  and VL 2  have different signs are selected for said correction.  
     
     
         6 . The method of  claim 1 , wherein said optical arrangement has at least two mirrors that are arranged in vicinity of at least one field plane of said projection objective, and at which said ratios VM 1  and VM 2  have identical signs, and wherein at least one lens surface that is arranged in vicinity of a field plane of said projection objective and at which the ratio VL has the same sign as said ratios VM 1  and VM 2  is selected for the correction.  
     
     
         7 . The method of  claim 1 , wherein said ratio VL deviates from said ratio VM by less than 20%.  
     
     
         8 . The method of  claim 1 , wherein said at least one selected lens surface is provided with an aspherization for correcting said at least one image defect.  
     
     
         9 . The method of  claim 1 , wherein said at least one lens that has said at least one selected lens surface is assigned an actuator, and wherein the image defect is corrected by at least one of a positional adjustment and a deformation of said at least one lens by means of said actuator.  
     
     
         10 . A projection objective of a lithography projection exposure machine, comprising an optical arrangement composed of a plurality of lenses and at least one mirror, wherein said at least one mirror has an optically operative surface that can cause at least one image defect of said optical arrangement, and wherein for a correction of said image defect at least one optically operative lens surface among lens surfaces of said lenses is selected, at which a magnitude of a ratio VL of principal ray height h L H to marginal ray height h R L comes at least closest to a ratio VM of principal ray height h M H to marginal ray height h M R at said optically operative surface of said at least one mirror.  
     
     
         11 . The projection objective of  claim 10 , wherein said ratio VL has the same sign as said ratio VM at said at least one selected lens surface.  
     
     
         12 . The projection objective of  claim 10 , wherein said optical arrangement has at least one mirror that is arranged in vicinity of a pupil plane of said projection objective, and wherein at least one lens surface that is arranged in vicinity of a pupil plane of said projection objective is selected for said correction.  
     
     
         13 . The projection objective of  claim 10 , wherein said optical arrangement has at least two mirrors that are arranged in vicinity of at least one field plane of said projection objective, and at which said ratios VM 1  and VM 2  have different signs, and wherein at least two lens surfaces that are arranged in vicinity of at least one field plane of said projection objective and at which said ratios VL 1  and VL 2  have different signs are selected for said correction.  
     
     
         14 . The projection objective of  claim 10 , wherein said optical arrangement has at least two mirrors that are arranged in vicinity of at least one field plane of said projection objective, and at which said ratios VM 1  and VM 2  have identical signs, and wherein at least one lens surface that is arranged in vicinity of a field plane of said projection objective and at which said ratio VL has the same sign as said ratios VM 1  and VM 2  is selected for said correction.  
     
     
         15 . The projection objective of any one of  claim 10 , wherein said ratio VL deviates from the ratio VM by less than 20%.  
     
     
         16 . The projection objective of  claim 10 , wherein said at least one selected lens surface is provided with an aspherization.  
     
     
         17 . The projection objective of  claim 10 , wherein said at least one lens that has said at least one selected lens surface is assigned an actuator for at least one of a positional adjustment and deformation of said lens.  
     
     
         18 . The projection objective of  claim 10 , comprising the following sequence of optically operative subassemblies in the sense of light passage: 
 a first, dioptric part that images an object plane onto a first intermediate image via a first pupil plane,    a second, catoptric part that images said first intermediate image onto a second intermediate image via a second pupil plane, and which includes a first and a second respectively near-field concave mirror and upstream and downstream of said second pupil plane, respectively,    a third, dioptric part that images said second intermediate image onto an image plane via a third pupil plane,    wherein at least one of the following is met:    a near-field correction lens, provided for correcting said first concave mirror, is arranged upstream of said first pupil plane,    a near-field correction lens, provided for correcting said first concave mirror, is arranged downstream of said second intermediate image and upstream of said third pupil plane,    a near-field correction lens, provided for correcting said second concave mirror is arranged downstream of said first pupil plane and upstream of said first intermediate image,    a near-field correction lens, provided for correcting said second concave mirror is arranged downsteam of said third pupil plane.    
     
     
         19 . The projection objective of  claim 10 , comprising the following sequence of optically operative subassemblies in the sense of light passage: 
 a first, catadioptric part that images an object plane onto an intermediate image via a first pupil plane, and which includes an even number of at least two mirrors of which at least one first mirror is near-pupil,    a second, catadioptric part that images said intermediate image onto an image via a second pupil plane and includes a second, near-field mirror, wherein at least one of the following is met:    a near-pupil correction lens provided for correcting said first mirror is provided in vicinity of said first pupil plane,    a near-pupil correction lens, provided for correcting said first mirror, is provided in vicinity of said second pupil plane,    a near-field correction lens, provided for correcting said second mirror is provided upstream of said first pupil plane.    
     
     
         20 . The projection objective of  claim 10 , comprising the following sequence of optically operative subassemblies in the sense of light passage: 
 a first, catadioptric part that images an object plane onto a first intermediate image via a first pupil plane and which includes a first, near-field mirror downstream of said first pupil plane,    a second, catadioptric part that images said first intermediate image onto a second intermediate image via a second pupil plane and which includes a second, near-pupil mirror,    a third, catadioptric part that images said second intermediate image onto an image via a third pupil plane and which includes a third, near-field mirror upstream of said third pupil plane,    wherein at least one of the following is met:    a near-field correction lens, provided for correcting said first mirror, is provided downstream of said first pupil plane and upstream of said first intermediate image,    a near-field correction lens, provided for correcting said first mirror, is provided downstream of said third pupil plane,    a near-field correction lens, provided for correcting said third mirror, is provided upstream of said first pupil plane,    a near-field correction lens, provided for correcting said third mirror, is provided downstream of the second intermediate image and upstream of said third pupil plane, and    a near-pupil correction lens, provided for correcting said second mirror, is provided in vicinity of said first pupil plane,    a near-pupil correction lens, provided for correcting said second mirror, is provided in vicinity of said second pupil plane,    a near-pupil correction lens, provided for correcting said second mirror, is provided in vicinity of said third pupil plane.    
     
     
         21 . The projection objective of  claim 10 , comprising the following sequence of optically operative subassemblies in the sense of light passage: 
 a first catadioptric part that images an object plane onto a first intermediate image via a first pupil plane, and which includes a first, near-pupil mirror and a second, near-field mirror, the latter being arranged downstream of said first pupil plane,    a second, dioptric part that images said intermediate image onto an image via a second pupil plane,    wherein at least one of the following is met:    a near-pupil correction lens, provided for correcting said first mirror, is provided in vicinity of said first pupil plane,    a near-pupil correction lens, provided for correcting said first mirror, is provided in vicinity of said second pupil plane,    a near-field correction lens, provided for correcting said second mirror, is provided downstream of said first pupil plane and upstream of said intermediate image.    
     
     
         22 . The projection objective of  claim 10 , comprising the following sequence of optically operative subassemblies in the sense of light passage: 
 a first, dioptric part that images an object plane onto a first intermediate image via a first pupil plane,    a second, catadioptric part that images said first intermediate image onto a second intermediate image via a second pupil plane and which includes a first, near-field mirror upstream of said second pupil plane, and a second, near-pupil mirror,    a third, catadioptric part that images said second intermediate image onto a third intermediate image via a third pupil plane and which includes a third, near-pupil mirror,    a fourth, catadioptric part that images said third intermediate image onto an image via a fourth pupil plane and which includes a fourth, near-field mirror upstream of the fourth pupil plane,    wherein at least one of the following is met:    a near-field correction lens, provided for correcting said first and fourth mirrors is provided upstream of said first pupil plane,    a near-field correction lens provided for correcting said first and fourth mirrors, is provided downstream of said first intermediate image and upstream of said second pupil plane,    a near-field correction lens, provided for correcting said first and fourth mirrors, is provided downstream of said second intermediate image and upstream of said third pupil plane,    a near-pupil correction lens, provided for correcting said second and third mirrors, is provided in vicinity of the first pupil plane,    a near-pupil correction lens, provided for correcting said second and third mirrors, is provided in vicinity of said second pupil plane,    a near-pupil correction lens, provided for correcting said second and third mirrors, is provided in vicinity of said third pupil plane,    a near-pupil correction lens, provided for correcting said second and third mirrors, is provided in vicinity of said fourth pupil plane.    
     
     
         23 . The projection objective of  claim 10 , comprising the following sequence of optically operative subassemblies in the sense of light passage: 
 a first, catadioptric part that images an object plane onto a first intermediate image via a first pupil plane and which includes a first, near-pupil mirror and includes at least one second, near-field mirror, the latter being arranged downstream of said first pupil plane,    a second, catoptric part that images said first intermediate image onto a second intermediate image via a second pupil plane and which includes a third, near-field mirror upstream of said second pupil plane, and a fourth, near-pupil mirror,    a third, dioptric part that images said second intermediate image onto an image via a third pupil plane,    wherein at least one of the following is met:    a near-field correction lens, provided for correcting said second mirror, is arranged downstream of said third pupil plane,    a near-field correction lens, provided for correcting said third mirror, is provided upstream of said first pupil plane,    a near-field correction lens, provided for correcting said third mirror, is provided downstream of said second intermediate image and upstream of said third pupil plane, and    a near-pupil correction lens, provided for correcting said mirrors, is provided in vicinity of said first pupil plane,    a near-pupil correction lens, provided for correcting the mirrors, is provided in vicinity of said third pupil plane.    
     
     
         24 . The projection objective of  claim 10 , comprising the following sequence of optically operative subassemblies in the sense of light passage: 
 a first, dioptric part that images an object plane onto a first intermediate image via a first pupil plane,    a second, catadioptric part that images said first intermediate image onto a second intermediate image via a second pupil plane and which includes a first near-field mirror upstream of the second pupil plane, as well as a near-pupil mirror,    a third, catadioptric part that images said second intermediate image onto an image via a third pupil plane and which includes a second near-field mirror upstream of said third pupil plane,    wherein at least one of the following is met:    a near field correction lens provided for correcting said first and third mirrors, is provided upstream of said first pupil plane,    a near-field correction lens, provided for correcting said first and third mirrors, is provided downstream of said second intermediate image and upstream of said third pupil plane,    a near-pupil correction lens, provided for correcting said second mirror, is provided in vicinity of said first pupil plane,    a near-pupil correction lens, provided for correcting said second mirror, is provided in vicinity of said second pupil plane,    a near-pupil correction lens, provided for correcting said second mirror, is provided in vicinity of said third pupil plane.