Abstract:
A lens has at least one aspheric lens surface, an objective with at least one aspheric lens surface, and a projection exposure device for microlithography and a method for the production of microstructured components with an objective having at least one aspheric lens surface. The object of the invention is to provide a method by which new designs with aspheric lens surfaces can be generated without consultation with manufacturing, with this object attained by the measure of describing the aspheric lens surfaces by Zernike polynomials, which makes it is possible to undertake a classification of aspheric lens surfaces such that the respective aspheric lens surface can be polished and tested at a justifiable cost when at least two of three, or all three, of certain conditions are present.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This Patent Application is a Continuation-In-Part of International Patent Application PCT/EP01/14314 filed Dec. 6, 2001, with a priority date of 22 Dec. 2000. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a lens with at least one aspheric lens surface, to an objective with at least one aspheric lens surface, and to a projection exposure device for microlithography and a method for the production of microstructured components with an objective having at least one aspheric lens surface. 
     Lenses with aspheric lens surfaces are increasingly used, particularly in projection objection objectives for microlithography, for improving imaging quality. For example, such projection objectives are known from German Patent Documents DE 198 18 444 A1, DE 199 42 281, U.S. Pat. Nos. 5,990,926, 4,948,328, and European Patent Document EP 332 201 B1. 
     Aspheric lenses are increasingly used in projection objection objectives for microlithography, for improving imaging quality. However, in order to attain the desired quality improvement by the use of lenses with aspheric lens surfaces, it is necessary that the actual shape of the aspheric lens surfaces does not deviate more than a predetermined amount form the reference data of the lens surface. The permissible deviations between the reference surface and the actual surface are very small in microlithography, because of the finer and finer structures to be imaged. For testing whether a present aspheric lens surface corresponds to the required lens surface within the range of measurement accuracy, a special test optics is required. The quality of the aspheric lens surface is tested with this test optics. 
     The complexity of such test optics depends definitively on the surface shape of the aspheric lens surface. In particular, the use is desirable of aspheric lenses whose aspheric lens surface can be tested by test optics which can be provided at a justifiable cost and which preferably consists of a small number of spherical lenses. 
     It can also be necessary in the production of aspheric lens surfaces for the aspheric lens surface to have to be tested and reworked repeatedly during the production process. 
     Due to polishing also, an undesired and non-uniform change of the surface shape can arise in dependence on the surface because of polishing removal, resulting in an impermissible change in the aspheric lens surface. 
     Furthermore, it can also happen with aspheric lenses of high asphericity, that is, with a large deviation from a spherical surface, and with a strong variation of the local curvature, that these surfaces can be polished only with very small polishing tools, with a very large polishing cost, or it is nearly impossible to polish the aspheric surface. Just in the process of designing objectives, it is not comfortable if the designer can only find out, by multiple consultations with the polishing specialist and with the specialist responsible for preparing the test optics, whether a design he has developed can be manufactured, or whether he has to change the design, so that a design exists which is also acceptable from manufacturing standpoints. Particularly when manufacture and development are spatially separated from one another, discussion and agreement between design and manufacturing entails a considerable cost in time. 
     SUMMARY OF THE INVENTION 
     The invention has as its object to provide a method by which new designs with aspheric lens surfaces can be generated without consultation with manufacturing. 
     The object of the invention is attained by the following features: By the measure of describing the aspheric lens surfaces by Zernike polynomials, it is possible to undertake a classification of aspheric lens surfaces such that the respective aspheric lens surface can be polished and tested at a justifiable cost when at least two of the three conditions (a)-(c) according to the following conditions are present:                P        (   h   )       =                h   2       R   (     1   +         1   -       h   2       R   2         )             +   K0   +     K4   *   Z4     +     K9   *   Z9     +     K10   *   Z16     +                            K25   *   Z25     +     K36   *   Z36     +     K49   *   Z49     +     K64   *   Z64                                    
     with 
     Z 4 =(2×h2−1) 
     Z 9 =(6h4−6h2+1) 
     Z 16 =(20h6−30h4+23h2−1) 
     Z 25 =(70h8−140h6+90h4−20 h2+1) 
     Z 36 =(252h10−630h8+560h6−210h 4+30 h2−1) 
     Z 49 =(924h12−27.72h 10+h3150h8−1680h6+h420h4−42h2+1) 
     Z 64 =(3432h14−12012h12+16632h110−h11550h8+4200h6−756h4+56h2−1) 
     where P is the sagitta as a function of the normed radial distance h from the optical axis  7 :        h   =         distance                 from                 the                 optical                 axis         1   2          (     lens                 diameter                 of                 the                 aspheric     )         =     normed                 radius               0   &lt;   h   ≤   1                          
      and wherein at least two of the following conditions is fulfilled:                     K16   K9          &lt;   0.7           (   a   )                      K25   K9          &lt;   0.1           (   b   )                      K36   K9          &lt;   0.02           (   c   )                                
      the radius of the aspheric lens surface being fixed so that K4=0. 
     The object of the invention is also achieved when all of the above conditions (a through c) are fulfilled. 
     Thus it is possible for the designer, without consultation with manufacturing, to be able to make a statement about whether his design can be tested and produced. The designer can limit himself to producing designs which can be tested and manufactured. 
     In particular, the presence of condition (c) has an advantageous effect on the manufacturability of aspheric lens surfaces. By the measure that the proportions resulting from the Zernike polynomial, relative to the normal radius, do not exceed the following contributions, a class of aspheric lens surface is created which are outstanding for easy manufacturability and testability. Those contributions are: 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Zernike polynomial Z9, 
                 ≦300 
                 μm 
               
               
                   
                 Zernike polynomial Z16, 
                 ≦35 
                 μm 
               
               
                   
                 Zernike polynomial Z25, 
                 ≦5 
                 μm 
               
               
                   
                 Zernike polynomial Z36, 
                 ≦1 
                 μm 
               
               
                   
                 Zernike polynomial Z49, 
                 ≦0.02 
                 μm, 
               
               
                   
                   
               
             
          
         
       
     
     By analogy to a vibrating air column or vibrating string, the coefficients Z 16 , Z 25 , Z 49 , Z 64 , etc. could be described as the overtones of the aspheric object. The poorer in overtones, i.e., the faster the decay of the amplitudes of the components from the Zernike polynomials Z 16  and greater, the easier it is to manufacture an aspheric. Furthermore, a compensation optics having lenses, or a computer-generated hologram, for testing the aspheric thereby becomes substantially insensitive as regards tolerances. In addition, rapid decay of the amplitudes makes it possible to find an isoplanatic compensation optics. The natural decay of the amplitudes of the Zernike contributions is decisive for the quality of matching of the test optics to the aspheric lens surface (residual RMS value of the wavefront). This is clear from the example put forward, with a particularly harmonic decay of the higher Zenike amplitudes. It would also be undesirable to unnaturally decrease an individual higher Zernike term in its amplitude. A compensation optics of spherical lenses with a technically reasonable sin-i loading generates quite by itself a gently decaying amplitude pattern of higher Zernike terms. 
     It has furthermore been found to be advantageous to provide the aspheric lens surface on a convex lens surface. This has an advantageous effect on the polishing process. 
     It has been found to be advantageous to provide in an objective only aspheric lens surfaces which according to the characterization by Zernike polynomials are easily produced with the required accuracy. 
     It has been found to be advantageous, in order to further improve the effect of these aspheric lens surfaces, to arrange a spherical lens surface respectively neighboring the aspheric lens surface and having a radius which deviates at most by 30% from the radius of the aspheric lens surface. By this measure, a nearly equidistant air gap is formed between the aspheric lens surface and the adjacently arranged spherical lens surface. The designer is thereby freer in the curvature of the aspheric, which represents an additional important degree of freedom of the aspheric, without thereby making it difficult to manufacture the aspheric. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     Further advantageous measures are described in detail in further dependent claims using the embodiment examples. 
     FIG. 1 shows a projection exposure device; 
     FIG. 2 shows a lens arrangement of a projection objective, designed for the wavelength 351 nm; 
     FIG. 3 shows a lens arrangement of a projection objective, designed for the wavelength 193 nm; and 
     FIG. 4 shows a test arrangement for the aspheric lens used in FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The structure of a projection exposure device is first described in principle with reference to FIG.  1 . The projection exposure device has an exposure device  3  and a projection objective  5 . The projection objective  5  includes a lens arrangement  19  with an aperture diaphragm AP, an optical axis  7  being defined by the lens arrangement  19 . A mask  9  is arranged between the exposure device  3  and projection objective  5 , and is held in the beam path by a mask holder  11 . Such masks  9  used in microlithography have a micrometer to nanometer structure which is imaged on an image plane  13  by means of the projection objective  5  with a reduction by a factor of up to 10, preferably a factor of 4. A substrate or a wafer  15  positioned by a substrate holder  17  is retained in the image plane  13 . The minimum structures which can still be resolved depend on the wavelength λ of the light used for the exposure and also on the aperture of the projection objective  5 ; the maximum attainable resolution of the projection exposure device increases with decreasing wavelength of the exposure device  3  and with increasing aperture of the projection objective  5 . 
     The lens arrangement  19  of a projection objective  5  for microlithography shown in FIG. 2 includes 31 lenses, which can be divided into six lens groups G 1 -G 6 . This lens arrangement is designed for the wavelength 351 nm. 
     The first lens group begins with a negative lens L 1 , followed by four positive lenses L 2 -L 5 . This first lens group has positive refractive power. 
     The second lens group G 2  begins with a thick meniscus lens L 6  of negative refractive power, with convex curvature toward the object. This negative lens is followed by two further negative lenses L 7  and L 8 . The lens L 9  following these is a meniscus lens of positive refractive power, which has a convex lens surface on the object side and is thus curved toward the object. As the last lens of the second lens group, a meniscus lens of negative refractive power is provided, curved toward the image, and is aspherized on the convex lens surface arranged on the image side. A correction of image errors in the region between the image field zone and image field edge is in particular possible by means of this aspheric lens surface in the second lens group G 2 . In particular, the image errors of higher order, which become evident on observing sagittal sections, are corrected. Since these image errors, visible in sagittal section, are particularly difficult to correct, this is a particularly valuable contribution. 
     The aspheric lens surface is mathematically described by the following equation with the Zernike polynomials Z 9 , Z 16 , Z 25 , Z 49  and Z 64 . For the aspheric lens surface, there holds:                P        (   h   )       =                h   2       R   (     1   +         1   -       h   2       R   2         )             +   K0   +     K4   *   Z4     +     K9   *   Z9     +     K10   *   Z16     +                            K25   *   Z25     +     K36   *   Z36     +     K49   *   Z49     +     K64   *   Z64                                    
     with: 
     Z 4 =(2×h 2 −1) 
     Z 9 =(6h 4 −6h 2 +1) 
     Z 16 =(20h 6 −30h 4 +23h 2 −1) 
     Z 25 =(70h 8 −140h 6 +90h 4 −20h 2 +1) 
     Z 36 =(252h 10 −630h 8 +560h 6 −210h 4 +30h 2 −1) 
     Z 49 =(924h 12 −27.72h 10 +3150h 8 −1680h 6 +h420h 4 −42h 2 +1) 
     Z 64 =(3432h 14 −12012h 12 +16632h 10 −11550h 8 +4200h 6 −756h 4 +56h 2 −1) 
     where P is the sagitta as a function of the normed radial distance h from the optical axis  7 :        h   =         distance                 from                 the                 optical                 axis         1   2          (     lens                 diameter                 of                 the                 aspheric     )         =     normed                 radius               0   &lt;   h   ≤   1                          
     The coefficients allocated to the Zernike polynomial and the radius are likewise given in the Tables, for describing the aspheric lens surface. The radius of the aspheric lens surface is fixed so that the following holds: 
     
       
           K   4 *Z 4 =0≧R 
       
     
     Other Zenike coefficients result with the selection of a differing radius. In particular, the Zernike polynomials of lower order would be changed. By selecting K 4 =0 or nearly 0, statements about manufacturability and testability of the aspherics can be particularly easily derived from the Zernike coefficients. The component resulting from the Zernike polynomial Z 9  contributes to spherical aberration of the third order. The portions resulting from the Zernike polynomial Z 16  contribute to the correction of the fifth order spherical aberration. The contributions from the Zernike polynomial Z 25  contribute to the correction of the seventh order spherical aberration, and the portions from the Zernike polynomial Z 36  contribute to the correction of the ninth order spherical aberration. 
     The third lens group G 3  is formed by the following five lenses L 11 -L 15 . Two thick positive lenses are arranged in the middle of the third lens group; their surfaces facing toward each other are strongly curved. A very thin positive lens L 13  is arranged between these two thick positive lenses, and has practically no refractive power. This lens is of little importance, so that this lens can be dispensed with if required, with slight modifications of the objective structure. This third lens group has positive refractive power. 
     The fourth lens group G 4  is formed by three negative lenses L 16 -L 18  and thus has negative refractive power. 
     The fifth lens group is formed by lenses L 19 -L 27 . The diaphragm is arranged after the first three positive lenses L 19 -L 21 . Two thick positive lenses are arranged after the diaphragm, and their mutually facing surfaces have a strong curvature. This arrangement of the lenses L 22  and L 23  has an advantageous effect on the spherical aberration. Account is taken by means of this arrangement of the lenses L 22  and L 23  of the principle of “lens of best shape”, i.e., strongly curved surfaces are situated in a ray path of approximately parallel rays. At the same time, specific contributions to the undercorrection of the oblique spherical aberration are provided and, in combination with the two following meniscuses L 24  and L 25 , which have an overcorrecting action on oblique spherical aberration, make possible an outstanding overall correction. The focal lengths of these lenses are f 12 =465.405 mm and f 34 =448.462 mm. 
     The sixth lens group G 6  principally has a negative lens L 28 , followed by two thick lenses. Differing from the example described, it can be advantageous for reducing compaction to use quartz glass for the last two lenses of this lens group. 
     This length of this objective, from the object plane  0  to the image plane  0 ′, is 1,000 mm. The image field is 8×26 mm. The numerical aperture of this objective is 0.75. A bandwidth of about 2.5 pm is permissible with this objective. The exact lens data can be gathered from Table 1. 
     
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 M1440a 
               
             
          
           
               
                   
                   
                   
                   
                 ½ Lens 
                 Refractive 
               
               
                   
                   
                 Thick- 
                   
                 Diam- 
                 index at 
               
               
                 Lens 
                 Radius 
                 ness 
                 Glasses 
                 eter 
                 351 nm 
               
               
                   
               
             
          
           
               
                 0 
                 Infinity 
                 35.0240 
                 L710 
                 60.887 
                 .999982 
               
               
                 L 1 
                 −908.93348 
                 7.0000 
                 FK5 
                 61.083 
                 1.506235 
               
               
                   
                 284.32550 
                 6.4165 
                 L710 
                 63.625 
                 .999982 
               
               
                 L 2 
                 968.84099 
                 23.7611 
                 FK5 
                 64.139 
                 1.506235 
               
               
                   
                 −212.21935 
                 .7000 
                 L710 
                 66.550 
                 .999982 
               
               
                 L 3 
                 413.73094 
                 17.2081 
                 FK5 
                 69.428 
                 1.506235 
               
               
                   
                 −424.88479 
                 18.8724 
                 L710 
                 69.711 
                 .999982 
               
               
                 L 4 
                 591.81336 
                 19.7102 
                 FK5 
                 69.490 
                 1.506235 
               
               
                   
                 −250.67222 
                 .7000 
                 L710 
                 69.228 
                 .999982 
               
               
                 L 5 
                 −2772.23751 
                 12.8582 
                 FK5 
                 67.060 
                 1.506235 
               
               
                   
                 −255.60433 
                 .7000 
                 L710 
                 66.381 
                 .999982 
               
               
                 L 6 
                 4699.63023 
                 9.0382 
                 FK5 
                 62.603 
                 1.506235 
               
               
                   
                 120.65688 
                 26.0302 
                 L710 
                 56.905 
                 .999982 
               
               
                 L 7 
                 −182.28783 
                 6.0000 
                 FK5 
                 56.589 
                 1.506235 
               
               
                   
                 302.39827 
                 20.1533 
                 L710 
                 57.318 
                 .999982 
               
               
                 L 8 
                 −140.55154 
                 6.0000 
                 FK5 
                 57.674 
                 1.506235 
               
               
                   
                 205.78996 
                 .7000 
                 L710 
                 64.913 
                 .999982 
               
               
                 L 9 
                 197.09815 
                 10.0000 
                 FK5 
                 66.049 
                 1.506235 
               
               
                   
                 223.79756 
                 27.0961 
                 L710 
                 68.261 
                 .999982 
               
               
                 L 10 
                 −191.72586 
                 8.0000 
                 FK5 
                 70.299 
                 1.506235 
               
               
                   
                 340.27531 A 
                 2.2458 
                 L710 
                 77.287 
                 .999982 
               
               
                 L 11 
                 −292.95078 
                 19.3593 
                 FK5 
                 77.813 
                 1.506235 
               
               
                   
                 −143.32621 
                 .7000 
                 L710 
                 80.683 
                 .999982 
               
               
                 L 12 
                 1440.49435 
                 47.0689 
                 FK5 
                 95.650 
                 1.506235 
               
               
                   
                 −155.30867 
                 .7000 
                 L710 
                 98.253 
                 .999982 
               
               
                 L 13 
                 −2647.76343 
                 13.8320 
                 FK5 
                 100.272 
                 1.506235 
               
               
                   
                 −483.82832 
                 .7000 
                 L710 
                 100.543 
                 .999982 
               
               
                 L 14 
                 169.62760 
                 45.9417 
                 FK5 
                 99.308 
                 1.506235 
               
               
                   
                 −1090.68864 
                 3.2649 
                 L710 
                 96.950 
                 .999982 
               
               
                 L 15 
                 102.07790 
                 10.0000 
                 FK5 
                 77.455 
                 1.505235 
               
               
                   
                 100.38160 
                 40.1873 
                 L710 
                 73.370 
                 .999982 
               
               
                 L 16 
                 −504.79995 
                 6.0000 
                 FK5 
                 71.843 
                 1.506235 
               
               
                   
                 130.61081 
                 34.6867 
                 L710 
                 64.992 
                 .999982 
               
               
                 L 17 
                 −153.51955 
                 6.0000 
                 FK5 
                 64.734 
                 1.506235 
               
               
                   
                 284.44035 
                 34.2788 
                 L710 
                 67.573 
                 .999982 
               
               
                 L 18 
                 −114.12583 
                 8.2925 
                 FK5 
                 68.531 
                 1.506235 
               
               
                   
                 731.33965 
                 20.4412 
                 L710 
                 84.132 
                 .999982 
               
               
                 L 19 
                 −291.19603 
                 24.2439 
                 FK5 
                 86.387 
                 1.506235 
               
               
                   
                 −173.68634 
                 .7000 
                 L710 
                 93.185 
                 .999982 
               
               
                 L 20 
                 −10453.06716 
                 28.2387 
                 FK5 
                 111.655 
                 1.506235 
               
               
                   
                 −304.21017 
                 .7000 
                 L710 
                 114.315 
                 .999982 
               
               
                 L 21 
                 −2954.65846 
                 30.7877 
                 FK5 
                 122.647 
                 1.506235 
               
               
                   
                 −312.03660 
                 7.0000 
                 L710 
                 124.667 
                 .999982 
               
               
                 Dia- 
                 Infinity 
                 .0000 
                   
                 131.182 
                 .999982 
               
               
                 phragm 
                 Diaphragm 
                 .0000 
                   
                 131.182 
               
               
                 L 22 
                 1325.30512 
                 52.2352 
                 FK5 
                 133.384 
                 1.506235 
               
               
                   
                 −282.76663 
                 .7000 
                 L710 
                 135.295 
                 .999982 
               
               
                 L 23 
                 276.96510 
                 52.6385 
                 FK5 
                 134.809 
                 1.506235 
               
               
                   
                 −1179.05517 
                 25.2703 
                 L710 
                 132.935 
                 .999982 
               
               
                 L 24 
                 −311.05526 
                 10.0000 
                 FK5 
                 131.670 
                 1.506235 
               
               
                   
                 −587.25843 
                 10.5026 
                 L710 
                 130.474 
                 .999982 
               
               
                 L 25 
                 −374.19522 
                 15.0000 
                 FK5 
                 130.116 
                 1.506235 
               
               
                   
                 −293.45628 
                 .7000 
                 L710 
                 130.127 
                 .999982 
               
               
                 L 26 
                 198.19004 
                 29.6167 
                 FK5 
                 111.971 
                 1.506235 
               
               
                   
                 535.50347 
                 .7000 
                 L710 
                 109.450 
                 .999982 
               
               
                 L 27 
                 132.82366 
                 34.0368 
                 FK5 
                 94.581 
                 1.506235 
               
               
                   
                 361.69797 
                 12.8838 
                 L710 
                 90.620 
                 .999982 
               
               
                 L 28 
                 7006.77771 
                 9.7505 
                 FK5 
                 88.792 
                 1.506235 
               
               
                   
                 349.77435 
                 1.0142 
                 L710 
                 79.218 
                 .999982 
               
               
                 L 29 
                 174.38688 
                 38.8434 
                 FK5 
                 73.443 
                 1.506235 
               
               
                   
                 55.37159 
                 4.9107 
                 L710 
                 45.042 
                 .999982 
               
               
                 L 30 
                 55.08813 
                 42.8799 
                 FK5 
                 43.842 
                 1.506235 
               
               
                   
                 807.41351 
                 1.9795 
                 L710 
                 30.725 
                 .999982 
               
               
                   
                 Infinity 
                 3.0000 
                 FK5 
                 29.123 
                 1.506235 
               
               
                   
                 Infinity 
                 12.0000 
                   
                 27.388 
                 .999982 
               
               
                   
               
               
                 K4 = 0  
               
               
                 K9 = 66445.43 nm  
               
               
                 K16 = 33200.31 nm  
               
               
                 K25 = 4553.78 nm  
               
               
                 K36 = 843.85 nm  
               
               
                 K49 = 172.24 nm  
               
               
                 K64 = 30.49 nm  
               
               
                 K0 = −37097.62 nm = offset  
               
             
          
         
       
     
     A lens arrangement is shown in FIG. 3, designed for the wavelength 193 nm and including 31 lenses. These 31 lenses can be divided into six lens groups G 1 -G 6 . 
     The first lens group includes the lenses L 101 -L 105  and has positive refractive power overall. 
     The second lens group G 2  includes the lenses L 106 -L 110 . This lens group has overall negative refractive power, and a waist is formed by this lens group. The first three lenses L 106 -L 108  have negative refractive power, the lens L 109  being a meniscus lens curved away from the reticle and having positive refractive power. The lens L 110  is a meniscus lens curved toward the wafer and provided on the image-side lens surface with an aspheric AS 1 . A nearly equidistant air gap, which comprises a thickness of at least 10 mm, is formed by this aspheric lens surface AS 1  and the following spherical lens surface S 2  of the lens L 111 . 
     The lens L 111  already belongs to the lens group L 3 , which includes the lenses of positive refractive power L 111 -L 115 . This lens group G 3  has positive refractive power overall. 
     The fourth lens group G 4  is formed by the lenses L 116 -L 118  and has negative refractive power. 
     The fifth lens group is formed by the lenses L 119 -L 127  and has positive refractive power. A diaphragm is arranged between the lenses L 121  and L 122 . The sixth lens group G 6  is formed by the lenses L 128 -L 131 , and has positive refractive power. 
     In the third lens group, the lens L 111  is made of CaF 2 . The use of CaF 2  at this point contributes to reducing the transverse chromatic error. 
     Furthermore, the positive lenses around the diaphragm, i.e., two positive lenses before the diaphragm and the two positive lenses L 122  and L 123  after the diaphragm, are made of CaF 2 . Since the longitudinal chromatic error depends both on the ray diameter and also on the refractive power, the chromatic errors can be compensated well in the region of the diaphragm, since the ray diameter is greatest there and the refractive powers of the lenses are relatively high. In contrast to the CaF 2  lens L 111  in the third lens group G 3 , these CaF 2  lenses L 120 -L 123  have a certain amount of inhomogeneities, which can be compensated by a specific surface deformation on the respective lens. This is possible since only small variation of the ray inclinations occurs here. 
     A further CaF 2  lens L 130  is provided in the last lens group L 6 . With this lens L 130 , a lens is concerned with a particularly strong radiation loading, so that the use of the material CaF 2  contributes to minimizing compaction and lens heating, since the material CaF 2  shows smaller compaction effects than does quartz glass. 
     With this objective, a very well corrected objective is concerned, in which the deviation from the ideal wavefront ≦7.5 mλ with λ=193 nm. The distance between the object plane  0  and the image plane  0 ′ is 1,000 mm and an image field of 8*26 mm 2  can be exposed. The numerical aperture is 0.76. The exact lens data can be gathered from Table 2. 
     
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 M1649a 
               
             
          
           
               
                   
                   
                   
                   
                 Refractive Index 
                 ½ Free 
               
               
                 Surface 
                 Radius 
                 Thickness 
                 Glasses 
                 193.304 nm 
                 Diameter 
               
               
                   
               
             
          
           
               
                 0 
                 Infinity 
                 32.000000000 
                 L710 
                 0.99998200 
                 54.410 
               
               
                 1 
                 Infinity 
                 14.179159189 
                 L710 
                 0.99998200 
                 60.478 
               
               
                 2 
                 −164.408664394 
                 6.500000000 
                 SIO2 
                 1.56028900 
                 60.946 
               
               
                 3 
                 477.741339202 
                 7.790005801 
                 HE 
                 0.99971200 
                 66.970 
               
               
                 4 
                 2371.284181560 
                 17.748516367 
                 SIO2 
                 1.56028900 
                 69.245 
               
               
                 5 
                 −223.822058173 
                 0.700000000 
                 HE 
                 0.99971200 
                 70.887 
               
               
                 6 
                 1195.174516496 
                 16.908813880 
                 SIO2 
                 1.56028900 
                 75.328 
               
               
                 7 
                 −310.690220530 
                 0.700000000 
                 HE 
                 0.99971200 
                 76.162 
               
               
                 8 
                 485.562118998 
                 17.669364706 
                 SIO2 
                 1.56028900 
                 78.088 
               
               
                 9 
                 −493.961769975 
                 0.700000000 
                 HE 
                 0.99971200 
                 78.165 
               
               
                 10 
                 283.324079929 
                 21.403504698 
                 SIO2 
                 1.56028900 
                 76.991 
               
               
                 11 
                 −575.651259941 
                 0.700000000 
                 HE 
                 0.99971200 
                 76.178 
               
               
                 12 
                 219.789049573 
                 25.467779640 
                 SIO2 
                 1.56028900 
                 70.691 
               
               
                 13 
                 103.024318785 
                 22.996372410 
                 HE 
                 0.99971200 
                 59.994 
               
               
                 14 
                 −1410.580832137 
                 6.300000000 
                 SIO2 
                 1.56028900 
                 59.678 
               
               
                 15 
                 138.332121536 
                 22.459549851 
                 HE 
                 0.99971200 
                 58.321 
               
               
                 16 
                 −258.063359303 
                 6.300000000 
                 SIO2 
                 1.56028900 
                 58.777 
               
               
                 17 
                 211.150408840 
                 4.720624389 
                 HE 
                 0.99971200 
                 63.072 
               
               
                 18 
                 285.055583047 
                 10.000000000 
                 SIO2 
                 1.56028900 
                 64.494 
               
               
                 19 
                 341.327971403 
                 25.082030664 
                 HE 
                 0.99971200 
                 66.580 
               
               
                 20 
                 −155.970649922 
                 8.215676832 
                 SIO2 
                 1.56028900 
                 68.121 
               
               
                 21 
                 −340.915621 A 
                 13.915549894 
                 HE 
                 0.99971200 
                 76.026 
               
               
                 22 
                 −239.610088127 
                 17.154283278 
                 CAF2HL 
                 1.50143600 
                 81.795 
               
               
                 23 
                 −158.430656481 
                 0.700000000 
                 HE 
                 0.99971200 
                 85.540 
               
               
                 24 
                 2921.942532737 
                 36.745821475 
                 SIO2 
                 1.56028900 
                 100.629 
               
               
                 25 
                 −199.180375968 
                 0.700000000 
                 HE 
                 0.99971200 
                 102.642 
               
               
                 26 
                 581.258911671 
                 38.708808511 
                 SIO2 
                 1.56028900 
                 108.907 
               
               
                 27 
                 −317.375895135 
                 0.700000000 
                 HE 
                 0.99971200 
                 109.183 
               
               
                 28 
                 166.493530930 
                 41.501871919 
                 SIO2 
                 1.56028900 
                 100.340 
               
               
                 29 
                 Infinity 
                 4.685571876 
                 HE 
                 0.99971200 
                 97.519 
               
               
                 30 
                 189.438503324 
                 15.000000000 
                 SIO2 
                 1.56028900 
                 82.804 
               
               
                 31 
                 129.565379485 
                 27.721937943 
                 HE 
                 0.99971200 
                 72.481 
               
               
                 32 
                 −827.552674490 
                 6.300000000 
                 SIO2 
                 1.56028900 
                 71.203 
               
               
                 33 
                 193.630934593 
                 25.802720751 
                 HE 
                 0.99971200 
                 65.619 
               
               
                 34 
                 −188.509323766 
                 6.300000000 
                 SIO2 
                 1.56028900 
                 65.012 
               
               
                 35 
                 190.247434306 
                 36.481919216 
                 HE 
                 0.99971200 
                 65.037 
               
               
                 36 
                 −110.072588070 
                 6.300000000 
                 SIO2 
                 1.56028900 
                 65.743 
               
               
                 37 
                 827.067219258 
                 19.846860784 
                 HE 
                 0.99971200 
                 78.180 
               
               
                 38 
                 −240.277331422 
                 13.611987588 
                 SIO2 
                 1.56028900 
                 80.133 
               
               
                 39 
                 −184.012276263 
                 0.700000000 
                 HE 
                 0.99971200 
                 84.422 
               
               
                 40 
                 −8088.819259729 
                 34.993850995 
                 CAF2HL 
                 1.50143600 
                 98.673 
               
               
                 41 
                 −208.055465305 
                 0.700000000 
                 HE 
                 0.99971200 
                 102.289 
               
               
                 42 
                 1182.181885936 
                 40.462877050 
                 CAF2HL 
                 1.50143600 
                 113.699 
               
               
                 43 
                 −275.059004135 
                 0.000000000 
                 HE 
                 0.99971200 
                 115.480 
               
               
                 44 
                 Infinity 
                 4.499000000 
                 HE 
                 0.99971200 
                 115.366 
               
               
                 45 
                 1047.795255328 
                 31.392914078 
                 CAF2HL 
                 1.50143600 
                 117.911 
               
               
                 46 
                 −395.614261534 
                 0.700000000 
                 HE 
                 0.99971200 
                 117.992 
               
               
                 47 
                 284.811208676 
                 40.095643635 
                 CAF2HL 
                 1.50143600 
                 114.217 
               
               
                 48 
                 −822.040097050 
                 25.559296680 
                 HE 
                 0.99971200 
                 112.963 
               
               
                 49 
                 −230.468653441 
                 12.000000000 
                 SIO2 
                 1.56028900 
                 111.553 
               
               
                 50 
                 −1740.772555558 
                 16.496567642 
                 HE 
                 0.99971200 
                 112.486 
               
               
                 51 
                 −384.661514825 
                 35.655800394 
                 SIO2 
                 1.56028900 
                 112.495 
               
               
                 52 
                 −216.196472563 
                 0.700000000 
                 HE 
                 0.99971200 
                 114.658 
               
               
                 53 
                 166.072770698 
                 31.752863257 
                 SIO2 
                 1.56028900 
                 101.831 
               
               
                 54 
                 515.781794736 
                 0.700000000 
                 HE 
                 0.99971200 
                 99.354 
               
               
                 55 
                 136.216120952 
                 28.320295414 
                 SIO2 
                 1.56028900 
                 87.888 
               
               
                 56 
                 324.185504117 
                 12.445936974 
                 HE 
                 0.99971200 
                 83.547 
               
               
                 57 
                 2205.751425211 
                 12.000000000 
                 SIO2 
                 1.56028900 
                 80.947 
               
               
                 58 
                 315.974328907 
                 0.700000000 
                 HE 
                 0.99971200 
                 71.831 
               
               
                 59 
                 128.655046396 
                 35.172368748 
                 SIO2 
                 1.56028900 
                 65.168 
               
               
                 60 
                 57.302742004 
                 1.258423244 
                 HE 
                 0.99971200 
                 42.354 
               
               
                 61 
                 54.304405296 
                 34.782435109 
                 CAF2HL 
                 1.50143600 
                 41.547 
               
               
                 62 
                 328.210777698 
                 3.191995120 
                 HE 
                 0.99971200 
                 30.793 
               
               
                 63 
                 Infinity 
                 3.000000000 
                 SIO2 
                 1.56028900 
                 28.819 
               
               
                 64 
                 Infinity 
                 12.000000000 
                 L710 
                 0.99998200 
                 27.177 
               
               
                 65 
                   
                   
                   
                   
                 13.603 
               
               
                   
               
             
          
         
       
     
     L 710  is air at 950 mbar. 
     Aspheric Constants 
     Zernike component of the aspheric surface No. 21 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 ZER9 = 
                 246.393 μm 
               
               
                   
                 ZER16 = 
                 7.96520 μm 
               
               
                   
                 ZER25 = 
                 1.39532 μm 
               
               
                   
                 ZER36 = 
                 0.117584 μm 
               
               
                   
                 ZER49 = 
                 −0.0032066 m 
               
               
                   
                   
               
             
          
         
       
     
     relative to a half free diameter of 76.026 mm. 
     Aspheric Coefficients 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 K0 = 
                 −31597.65 nm 
               
               
                   
                 K4 = 
                 0 
               
               
                   
                 K9 = 
                 57834.73 nm 
               
               
                   
                 K16 = 
                 29505.91 nm 
               
               
                   
                 K25 = 
                 3835.77 nm 
               
               
                   
                 K36 = 
                 655.93 nm 
               
               
                   
                 K49 = 
                 133.64 nm 
               
               
                   
                 K64 = 
                 23.24 nm 
               
               
                   
                   
               
             
          
         
       
     
     A possible construction of a test optics suitable for testing the optical properties of the aspheric lens surfaces contained in FIGS. 2 and 3 is shown in FIG.  4 . This test optics comprises 4 spherical lenses T 1 -T 4  of quartz glass. The length of this test structure is 480 mm. The working distance, i.e., the distance between the last lens of the test optics and the aspheric lens surface to be tested, is 20 mm. A test object of up to a maximum diameter of 155.4 mm can be tested with this test optics. The input diameter of the test optics is 192.107. The maximum diameter of this test optics is 193.874 mm. The deviation from the ideal wavefront is 0.384 with a test wavelength of 632.8 nm. This residual error can be computer compensated. 
     This test optics is distinguished in that it is isoplanatic. The isoplanatic correction of the K-optics is valuable, since it contains the imaging scale with imaging of the aspheric lens surface from the middle to the edge on the interference image which arises. A constant lateral resolution is thereby obtained in testing aspherics. Because of the interference pattern which results on irradiation with a plane wavefront, the surface shape of the aspheric lens surface is determined by means of the interference pattern which appears. 
     The exact lens data of the test optics can be gathered from Table 3. 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 Lens 
                 Radius 
                 Thickness 
                 Material 
                 Diameter 
                 sin i 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 P1 
                 1695.617 
                 30.807 
                 SIO2 
                 192.11 
                 0.057 
               
               
                   
                 −263.187 
                 34.771 
                   
                 191.75 
                 0.555 
               
               
                 P2 
                 213.537 
                 10.000 
                 SIO2 
                 161.68 
                 0.172 
               
               
                   
                 97.451 
                 308.777 
                   
                 146.57 
                 0.800 
               
               
                 P3 
                 154.172 
                 36.663 
                 SIO2 
                 193.87 
                 0.686 
               
               
                   
                 595.848 
                 45.306 
                   
                 190.04 
                 0.043 
               
               
                 P4 
                 −246.667 
                 13.677 
                 SIO2 
                 181.65 
                 0.548 
               
               
                   
                 −206.476 
                 20.000 
                   
                 181.48 
                 0.652 
               
               
                   
               
             
          
         
       
     
     LIST OF REFERENCE NUMERALS 
       1  Projection exposure device 
       2  Illumination device 
       5  Projection objective 
       7  Optical axis 
       9  Mask 
       11  Mask holder 
       13  Image plane 
       15  Wafer, substrate 
       17  Substrate holder 
       19  Lens arrangement 
     AP Aperture diaphragm