Abstract:
This invention relates to a projection lens system used for transferring circuit or other patterns from masks, etc. on which the circuit patterns are drawn onto semiconductor wafers by projection photolithography, and provides a projection lens system which makes high resolving power of the order of a few micrometers and wide exposure coverages compatible with each other. 
     This projection lens system includes at least two sets of lens groups, each built up of lenses having concave surfaces located opposite to each other, and includes at least one lens surface of positive refractive power between said two sets of lens groups, said two sets of lens groups all satisfying the following conditions: 
     
       1/L&lt;|φ.sub.1 &lt;20/L                            (1) 
     
     
       1/L&lt;|φ.sub.2 &lt;20/L                            (2) 
     
     wherein φ 1  and φ 2  stand for the respective negative refractive powers of said oppositely located concave surfaces, and L is the distance between object and image.

Description:
This is a division of application Ser. No. 07/780,339, filed Oct. 22, 1991, U.S. Pat. No. 5,260,832. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a projection lens system used for transferring circuit or other patterns onto semiconductor wafers through masks, etc.--on which the circuit patterns are drawn--by projection photolithography. 
     So far, transfer of desired patterns onto integrated circuits such as ICs and LSIs or flat displays built up of liquid crystals has been achieved by non-contact photolithography called the proximity technique or reflecting photolithography called the aligner technique. 
     Of these, the proximity technique is designed to locate a mask in close proximity to a semiconductor wafer and transfer a circuit pattern drawn on the mask onto the wafer, as set forth in Japanese Provisional Patent Publication No. 50(1975)-115774. In this technique, it is a slight space between the mask and the substrate onto which the pattern is to be transferred that determines transfer resolving power; this space must be very narrow when transfer is to be carried out with high resolving power. However, when the mask is located in too close proximity to or in contact with the substrate, the circuit pattern transferred onto the substrate would be impaired. 
     In the aligner technique, on the other hand, pattern resolving powers are determined by imagewise numerical aperture, because masks are adapted to be projected onto wafers through a reflecting optical system, as disclosed in Japanese Provisional Patent Publication No. 63(1988)-184328. However, this technique again offers a problem in that no high resolving power can be obtained, because it is impossible to increase the imagewise numerical aperture for the reason that the reflecting optical system is usually an equimultiple one. As the region to be exposed to light, i.e., the image surface increases in area, there is an increase in the expansion of a semiconductor substrate due to the heat of projected light; transfer must be carried out after the alignment of the circuit pattern size by fine adjustment of projecting magnification. However, a major problem with the aligner technique is that a pattern of large size cannot be projected at one time, because it is in principle difficult to vary the projecting magnification in alignment with the expansion of the substrate. In order to solve these problems, the step-and-repeat photolithographic technique with demagnification has been mainly used in recent years. As set forth in Japanese Provisional Patent Publication No. 60( 1985)-195509 and other literature, this technique is designed to project masks onto wafers with suitable demagnification (on the scale of ca. 1 to 2, 3, . . . ) for pattern transfer. This technique enables projecting magnifications to be arbitrarily varied by fine adjustment of a distance between the mask on which a circuit pattern is drawn and the projected image (substrate) and makes it easy to enhance resolving powers by affording a large value for the imagewise numerical aperture of a projection lens, and so will be increasingly used from now on. 
     However, conventional projection lens systems available with this technique have been found to fall to satisfy both high resolving power (i.e., large numerical aperture) and wide exposure coverages (image heights). 
     SUMMARY OF THE INVENTION 
     A principal object of this invention is to provide a projection lens system which makes high resolving power on the order of a few micrometers and wide exposure coverages compatible with each other. 
     The projection lens system according to this invention is characterized by including at least two sets of lens groups, each built up of lenses whose concave surfaces are opposite to each other, and including at least one lens surface having positive refractive power between the two sets of lens groups. 
     Referring more specifically to this invention, the curvature of field need be almost completely corrected so as to achieve high resolving power and wide exposure coverages concurrently. As well known in the art, the curvature of field has close relations to the Petzval&#39;s sum; the smaller the Petzval&#39;s sum the smaller the curvature of field, thus achieving wide exposure coverages. Although it is known that lens arrays having concave surfaces located in opposition to each other may be used as means for correcting the Petzval&#39;s sum, difficulty would be encountered in correcting the Petzval&#39;s sum with one such array of lenses. The reason is that it may be possible to decrease the Petzval&#39;s sum by increasing the negative refractive powers of the oppositely located concave surfaces; however, when the concave surfaces have too high powers, comae occurring thereon are too large to make corrections by other surfaces. 
     Now, the use of two sets of lens groups, each having concave surfaces located opposite to each other, is envisaged. A problem with such an arrangement, however, is that only the lens group having its concave surfaces giving out divergent bundles of rays are so locally positioned on part of the lens system that there can be no choice but to diminish the negative refractive powers of such concave surfaces so as to allow the refractive power of the overall lens system to get a given value. More exactly, the oppositely located concave surfaces act to decrease the Petzval&#39;s sum increase in number, but it is nonetheless impossible to decrease the Petzval&#39;s sum because the respective concave surfaces are less capable of making corrections. 
     According to this invention accomplished with the foregoing in mind, at least one lens surface having positive refractive power is positioned between two sets of lens groups, each having concave surfaces located opposite to each other, thereby making an effective contribution to correcting the Petzval&#39;s sum. With this arrangement wherein the two sets of lens groups, each having concave surfaces located opposite to each other, are coaxially positioned with the lens surface having positive refractive power disposed therebetween, the respective concave surfaces of each lens group are allowed to have suitable refractive powers with respect to the Petzval&#39;s sum and comae. The &#34;suitable refractive powers&#34; referred to in this disclosure satisfy the following conditions: 
     
         1/L&lt;|φ.sub.1 |&lt;20/L                  (1) 
    
     
         1/L&lt;|φ.sub.2 |&lt;20/L                  (2) 
    
     wherein φ 1  and φ 2  stand for the respective negative refractive powers of the concave surfaces located opposite to each other, and L is the distance between object and image. 
     At above the upper limits of these conditions, the negative refractive powers of the concave surfaces are too low to make sufficient corrections on the Petzval&#39;s sum, leaving behind some curvature of field and so rendering it possible to obtain wide exposure coverages. At below the lower limits, the negative refractive powers are so increased that the Petzval&#39;s sum can be corrected, but difficulty is involved in making corrections by other surfaces due to the occurrence of excessive comas. 
     In order to prevent partial image distortions which may otherwise occur depending upon the flatness of the substrate, it is desired to set up a so-called telecentric system wherein the imagewise exit pupil is designed to lie in the vicinity of the infinite point. According to this invention, a positive lens group is disposed on the image surface of the two sets of lens groups, each built up of concave surfaces located opposite to each other, so as to allow the imagewise exit pupil to lie in the vicinity of the infinite point. This is to focus the exit pupil in the lens system on the infinite point. 
     Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification. 
     The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 to 9 are sectional views showing lens arrangements of the first to ninth embodiments of this invention, and 
     FIGS. 10A to 10F through 18A to 18F are aberration curve diagrams of the 1st to 9th embodiments. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Some embodiments of the projection lens system according to this Invention will now be explained at great length with reference to the drawings. 
     FIG. 1 is a sectional view showing the lens arrangement of the 1st embodiment, wherein the second and fifth surfaces R2 and R5 and the 16th and 17th surfaces R16 and R17 define oppositely located concave surfaces (shown by φ 1  and φ 2  in the drawing). The 2nd and 5th surfaces R2 and R5 are shown to include a lens of moderate power therebetween, but according to this invention there may be included a lens component of simple structure between the &#34;lens groups, each having concave surfaces located opposite to each other&#34;. This lens system is a projection lens with demagnification on a one-to-two scale. 
     FIG. 2 is a sectional view showing a lens arrangement of the 2nd embodiment, wherein the 5th and 8th surfaces R5 and R8 and the 17th and 18th surfaces R17 and R18 define oppositely disposed concave surfaces. This lens system is again a projection lens with demagnification on a one-to-two scale. 
     FIG. 3 is a sectional view showing a lens arrangement of the 3rd embodiment, wherein the 5th and 8th surfaces R5 and R8 and the 17th and 20th surfaces R17 and R20 define oppositely disposed concave surfaces. This lens system is an equimultiple projection lens. 
     All these embodiments are characterized by including a lens group of positive refractive power, built up of at least two lens of positive refract ire powers, between two sets of lens groups, each built up of oppositely disposed concave surfaces, and by meeting the following condition: 
     
         f&lt;L/4                                                      (3) 
    
     wherein f is the composite focal length and L is the distance between object and image. This condition implies that unless the lens group of positive refractive power has a certain or higher refractive power, some difficulty is encountered in making satisfactory aberration corrections. Since the respective lens groups, each built up of oppositely disposed concave surfaces, have increased negative refractive powers, the lens group of positive refractive power sandwiched therebetween are located at a position at which marginal rays stand high. The higher the position of a lens where marginal rays stand high, the more it is likely to have an influence on the focal length of the overall lens system, thus allowing the refractive power of the overall system to be born by this lens group of positive refractive power. For that reason, when the positive refractive power of the lens group having positive refractive power diminishes out of condition, it is impossible to increase the refractive powers of the oppositely disposed concave surfaces of the two sets of lens groups; it is impossible to decrease the Petzval&#39;s sum. 
     In each of these embodiments, the imagewise lens group of the lens groups, each built up of oppositely disposed concave surfaces, includes at least three lenses of positive refractive powers and at least one lens of negative refractive power so as to achieve a telecentric system on the image side. Such positive and negative lenses are needed to make satisfactory corrections on spherical aberrations when the pupil in the lens system is focused on the infinite point. For instance, when this group comprises one single lens, the angle of inclination of exit rays is made large by image heights because the spherical aberration of the pupil cannot be well corrected. Thus, when image surfaces are moving to-and-fro in the focal depth, image distortions vary seriously. 
     FIG. 4 is a sectional view showing a lens arrangement of the 4th embodiment, wherein the 7th and 8th surfaces R7 and R8 and the 13th and 14th surfaces R13 and 14 define oppositely disposed concave surfaces. 
     FIG. 5 is a sectional view showing a lens arrangement of the 5th embodiment, wherein the 10th and 11th surfaces R10 and R11 and the 16th and 17th surfaces R16 and 17 define oppositely disposed concave surfaces. 
     FIG. 6 is a sectional view showing a lens arrangement of the 6th embodiment, wherein the 13th and 16th surfaces R13 and R16 and the 19th and 20th surfaces R19 and R20 define oppositely disposed concave surfaces. 
     FIG. 7 is a sectional view showing a lens arrangement of the 7th embodiment, wherein the 14th and 15th surfaces R14 and R15 and the 24th and 25th surfaces R24 and R25 define oppositely disposed concave surfaces. 
     FIG. 8 is a sectional view showing a lens arrangement of the 8th embodiment, wherein the 14th and 15th surfaces R14 and R15 and the 24th and 25th surfaces R24 and R25 define oppositely disposed concave surfaces. 
     FIG. 9 is a sectional view showing a lens arrangement of the 9th embodiment, wherein the 10th and 11th surfaces R10 and R11, the 16th and 17th surfaces R16 and R17 and the 26th and 27th surfaces R26 and 27 define oppositely disposed concave surfaces. 
     The 4th-9th embodiments are all directed to projection lenses with demagnification on a one-to-five scale. In the lens systems with demagnification on a one-to-five scale, the imagewise principal points of the lenses are closer to images than those in the 1st to 3rd embodiments. In other words, when a positive lens group of positive refractive power that constitutes a major power is located between two sets of lens groups, each comprising oppositely disposed concave surfaces, there is no space for providing a positive lens group to achieve a telecentric construction on the image side. This is because, in each of these embodiments, the two sets of lens groups, each built up of oppositely disposed concave surfaces, are located on the object side of the above-mentioned positive lens group that constitutes a major power of the lens system. 
     In order to obtain an imagewise numerical aperture (NA) of 0.4 or more, the above-mentioned positive lens group that constitutes a major power is built up of at least four lenses having positive refractive powers, whereby the amount of spherical aberrations caused by the positive lens group that constitutes a major power can be corrected by other lenses. 
     In order to correct the Petzval&#39;s sum more satisfactorily, a lens which has negative refractive power and the concave surface of which faces the image side is provided on the image side of the two sets of lens groups, each built up of oppositely disposed concave surfaces. Making the Petzval&#39;s sum good enough and obtaining wide exposure coverages are then achieved by satisfying the following condition: 
     
         1/L&lt;|φ.sub.3 |&lt;20/L                  (4) 
    
     wherein φ 3  is the negative refractive power of the additional lens and L is the distance between object and image. The same as referred to in connection with Condition (1) again holds for the upper and lower limits of Condition (4). In order to afford pertinent values for the refractive powers of the two sets of lens groups, each built up of oppositely disposed concave surfaces, and make the amount of comae correctable by other lenses, a lens group built up of at least two lenses of positive refractive powers is disposed on the object side of the above-mentioned sets of lens groups. This lens group having positive refractive power makes it possible to lower the height of off-axial rays when they are incident on the oppositely disposed concave surfaces on the object side. When the incident rays are at a low height, comae are less likely to occur, because even though the oppositely disposed concave surfaces are increased in refractive power by decreasing their radii of curvature, there is a little, if any, difference in the angle of incidence upon the concave surfaces between the upper and lower components of off-axial dependent rays. 
     Referring to the 10th embodiment, the Petzval&#39;s sum is further decreased by using three sets of lens groups, each having concave surfaces disposed opposite to each other. 
     It is noted that the 7th to 9th embodiments are designed to be used with monochromatic light sources having a very close range of wavelengths, like laser, and are formed of a single glass material. 
     In each of these embodiments, an imagewise numerical aperture (NA) of 0.45 or more is obtained by disposing an additional lens group comprising at least one lens of negative refractive power on the object side of the lens group comprising at least two lenses of positive refractive powers, which has been disposed on the object side of the two sets of lens groups, each built up of oppositely disposed concave surfaces. This is to correct coma flares occurring on the lens group comprising at least two lenses of positive refractive powers, located on the above-mentioned object side. In addition, the positive refractive power of the lens group located between the two sets of lens groups, each built up of oppositely disposed concave surfaces, is increased to impart proper refractive powers to the oppositely disposed concave surfaces. 
     The 9th embodiment is constructed as a projection lens system made telecentric on both its sides, wherein the entrance pupil is set at the infinite point. 
     In the following examples, detailed data will be given. 
     
         ______________________________________Example 1f = 211.48  NA = 0.2  IH = 37.5  L = 1000OB = 363.015  SK = 18.185  λ = 436 nm______________________________________R1 = 290.079   D1 = 17.500  N1 = 1.69299R2 = 138.498   D2 = 8.846R3 = 507.317   D3 = 17.500  N2 = 1.71756R4 = ∞   D4 = 21.215R5 = -129.056  D5 = 41.301  N3 = 1.59953R6 = 239.801   D6 = 39.464  N4 = 1.52613R7 = -201.485  D7 = 12.896R8 = ∞   D8 = 22.500  N5 = 1.52613R9 = -394.840  D9 = 1.250R10 = 292.481  D10 = 25.000 N6 = 1.52613R11 = -610.192 D11 = 1.250R12 = 250.061  D12 = 27.500 N7 = 1.52613R13 = -746.631 D13 =  35.913R14 = 165.337  D14 = 39.178 N8 = 1.52613R15 = -178.430 D15 = 13.750 N9 = 1.59953R16 = 103.371  D16 = 99.911R17 = -97.752  D17 = 10.000 N10 = 1.54529R18 = 343.137  D18 = 13.691R19 = -341.327 D19 = 18.750 N11 = 1.71221R20 = -155.958 D20 = 35.863R21 = 132.625  D21 = 27.500 N12 = 1.52613R22 = ∞  D22 = 1.250R23 = 239. 402 D23 = 20.000 N13 = 1.61529R24 = ∞  D24 = 1.250R25 = 219.047  D25 = 48.519 N14 = 1.61529R26 = ∞  D26 = 7.014R27 = -234.923 D27 = 10.000 N15 = 1.71756R28 = 259.518______________________________________φ.sub.1 (R2) = -0.005, φ.sub.2 (R5) = -0.0046φ.sub.1 (R16) = -0.0058, φ.sub.2 (R17) = -0.0056______________________________________Example 2f = 215.03  NA = 0.18  IH = 50  L = 1000OB = 336.094  SK = 15.000  λ = 436 nm______________________________________R1 = 427.197   D1 = 15.000  N1 = 1.57082R2 = 147.578   D2 = 19.888  N2 = 1.62364R3 = ∞   D3 = 3.750R4 = 156.400   D4 = 15.000  N3 = 1.62364R5 = 95.679    D5 = 23.118R6 = -103.846  D6 = 15.000  N4 = 1.61529R7 = -90.413   D7 = 9.643R8 = -83.274   D8 = 27.219  N5 = 1.59953R9 = 426.489   D9 = 43.157  N6 = 1.52613R10 = -159.199 D10 = 44.347R11 = 825. 646 D11 = 22.442 N7 = 1.63619R12 = -282.360 D12 = 1.250R13 = 227.045  D13 = 31.218 N8 = 1.61529R14 = -749.008 D14 = 43.166R15 = 184.718  D15 = 30.140 N9 = 1.52613R16 = -227.718 D16 = 15.000 N10 = 1.66362R17 = 133.563  D17 = 121.146R18 = -101.157 D18 = 15.000 N11 = 1.58406R19 = 875.000  D19 = 8.592R20 = -475.291 D20 = 20.000 N12 = 1.71221R21 = -214.958 D21 = 1.250R22 = 167.754  D22 = 33.383 N13 = 1.54529R23 = -449.144 D23 = 1.250R24 = 490.443  D24 = 21.250 N14 = 1.71221R25 = -847.568 D25 = 1.250R26 = 269.443  D26 = 20.000 N15 = 1.71221R27 = ∞  D27 = 7.338R28 = -386.590 D28 = 15.000 N16 = 1.52613R29 = 875.000  D29 =  11.610R30 = -208.684 D30 = 12.500 N17 = 1.52613R31 = ∞______________________________________φ.sub.1 (R5) = -0.0065, φ.sub.2 (R8) = -0.0072,φ.sub.1 (R17) = -0.005, φ.sub.2 (R18) = -0.0058______________________________________Example 3f = 310. 93  NA = 0.1  IH = 88  L = 1000OB = 280.813  SK = 15.00  A = 436 nm______________________________________R1 = 292.620   D1 = 18.811  N1 = 1.57082R2 = -159.166  D2 = 15.000  N2 = 1.62364R3 = -1869.713 D3 = 1.250R4 = 114.734   D4 = 15.000  N3 = 1.62364R5 = 81.531    D5 = 19.319R6 = -89.379   D6 = 28.913  N4 = 1.61529R7 = -87.779   D7 = 14.214R8 = -79.176   D8 = 15.006  N5 = 1.59953R9 = -87.304   D9 = 21.379  N6 = 1.52613R10 = -150.014 D10 = 33.438R11 = 712.082  D11 = 24.950 N7 = 1.63619R12 = -289.529 D12 = 1.946R13 = 321.409  D13 = 31.266 N8 = 1.61529R14 = -318.064 D14 = 26.097R15 = 194.500  D15 = 39.408 N9 = 1.52613R16 = -161.670 D16 = 15.251 N10 = 1.66362R17 = 133.903  D17 = 131.310R18 = -113.561 D18 = 15.000 N11 = 1.58406R19 = -175.912 D19 = 35.716R20 = -122.171 D20 = 15.000 N12 = 1.71221R21 = -232.823 D21 = 42.036R22 = 778.470  D22 = 31.449 N13 = 1.54529R23 = -356.749 D23 = 1.250R24 = 1086.864 D24 = 27.302 N14 = 1.71221R25 =  -450.133          D25 = 1.250R26 = 489.065  D26 = 30.751 N15 = 1.71221R27 = -488.224 D27 = 4.415R28 = -402.456 D28 = 15.000 N16 = 1.52613R29 = 486.544  D29 = 19.965R30 = -461.652 D30 = 12.500 N17 = 1.52613R31 = ∞______________________________________φ.sub.1 (R5) = -0.0076, φ.sub.2 (R8) = -0.0076,φ.sub.1 (R17) = -0.00495, φ.sub.2 (R20) = -0.0058______________________________________Example 4f = 131.35  NA = 0.42  IH = 17.6  L = 1000OB = 233.494  SK = 19.762  A = 365 nm______________________________________R1 = ∞   D1 = 25.014  N1 = 1.66650R2 = -540.172  D2 = 0.502R3 = 314.013   D3 = 23.561  N2 = 1.53607R4 =  -1052.536          D4 = 0.500R5 = 141.696   D5 = 28.894  N3 = 1.66650R6 = 250.725   D6 = 16.200  N4 = 1.62747R7 = 82.055    D7 = 23.237R8 = -248.492  D8 = 9.743   N5 = 1.53607R9 = 155.078   D9 = 42.165R10 = 1411.311 D10 = 43.265 N6 = 1.53607R11 = -197.016 D11 = 0.720R12 = 1887.223 D12 = 9.992  N7 = 1.53607R13 = 128.923  D13 = 26.295R14 = -83.854  D14 = 29.985 N8 = 1.63595R15 = 179.127  D15 = 52.329 N9 = 1.53607R16 = -153.936 D16 = 12.067R17 = -405.392 D17 = 21.223 N10 = 1.53607R18 = -236.191 D18 = 0.166R19 = 487.323  D19 = 26.099 N11 = 1.53607R20 = -468.313 D20 = 39.652R21 = 304.311  D21 = 33.362 N12 = 1.53607R22 = -716.692 D22 = 0.627R23 = 230.393  D23 = 30.350 N13 = 1.53607R24 = -1013.566          D24 = 2.491R25 = 129.171  D25 = 45.421 N14 = 1.53607R26 = -265.302 D26 = 10.087 N15 = 1.61936R27 = 80.350   D27 = 46.038R28 = -127.941 D28 = 9.788  N16 = 1.62757R29 = 151.523  D29 = 5.853R30 = 409.679  D30 = 32.322 N17 = 1.53607R31 = -196.968 D31 = 3.703R32 = 87.936   D32 = 49.116 N18 = 1.53607R33 = -552.433 D33 = 0.642R34 = 88.909   D34 = 31.195 N19 = 1.53607R35 = ∞  D35 = 3.982R36 = -171.383 D36 = 10.117 N20 = 1.66651R37 = ∞______________________________________φ.sub.1 (R7) = -0.0077, φ.sub.2 (R8) = -0.0022,φ.sub.1 (R13) = -0.0042, φ.sub.2 (R14) = -0.0080,φ.sub.1 &#39;(R27) = -0.0077______________________________________Example 5f = 125.51  NA = 0.55  IH = 17.8  L = 1000OB = 209.791  SK = 15.000  λ = 365 nm______________________________________R1 = -160.871  D1 = 12.500  N1 = 1.53577R2 = -3042.237 D2 = 37.543  N2 = 1.68816R3 = -276.972  D3 = 1.250R4 = 924.249   D4 = 26.108  N3 = 1.70826R5 = -517.336  D5 = 1.250R6 = 360.906   D6 = 27.247  N4 = 1.70826R7 = -1284.981 D7 = 1.250R8 = 291.736   D8 = 51.175  N5 = 1.64177R9 = -123.660  D9 = 22.935  N6 = 1.64035R10 =  75. 015 D10 = 31.102R11 = -136.141 D11 = 12.500 N7 = 1.53577R12 = 198.932  D12 = 1.250R13 = 156.713  D13 = 75.896 N8 = 1.69377R14 = -135.199 D14 = 4.396R15 = -108.356 D15 = 12.500 N9 = 1.55881R16 = 174.685  D16 = 33.885R17 = -80.542  D17 = 12.500 N10 = 1.66640R18 = 1057.599 D18 = 43.876 N11 = 1.53577R19 = -136.636 D19 = 1.250R20 = -350.875 D20 = 26.069 N12 = 1.65599R21 = -195.286 D21 = 1.250R22 = 1984.422 D22 = 38.999 N13 = 1.60189R23 = -258.154 D23 = 1.250R24 = 361.244  D24 = 34.469 N14 = 1.67717R25 = -1057.393          D25 = 1.250R26 = 196.491  D26 = 35.213 N15 = 1.60763R27 =  1206.640          D27 = 1.250R28 = 137.471  D28 = 54.194 N16 = 1.53577R29 = -609.635 D29 = 12.500 N17 = 1.67508R30 = 90.424   D30 = 18.571R31 = 11044.575          D31 = 12.500 N18 = 1.66640R32 = 98.328   D32 = 12.241R33 = 592.755  D33 = 17.335 N19 = 1.70826R34 = -435.824 D34 = 1.250R35 = 95.932   D35 = 73.213 N20 = 1.62930R36 = 124.190  D36 = 1.250R37 = 58.297   D37 = 21.991 N21 = 1.57066R38 = ∞______________________________________φ.sub.1 (R10) = -0.0085, φ.sub.2 (R11) = -0.0039,φ.sub.1 (R16) = -0.0032, φ.sub.2 (R17) = -0.0081,φ.sub.3 (R30) = -0.0075______________________________________Example 6f = 125.49  NA = 0.45  IH = 20.8   L = 1000OB = 49.834  SK = 6.644  λ= 365 nm______________________________________R1 = 168.112   D1 = 65.605  N1 = 1.62743R2 = 887.936   D2 = 3.384R3 = 1461.620  D3 = 13.289  N2 = 1.64868R4 = 137.202   D4 = 32.228R5 = -467.702  D5 = 13.289  N3 = 1.58675R6 = 314.339   D6 = 38.655R7 = 564.420   D7 = 29.068  N4 = 1.66640R8 = -333.913  D8 = 0.166R9 = 290.824   D9 = 25.751  N5 = 1.66640R10 = -1710.394          D10 = 0.166R11 = 144.337  D11 = 26.999 N6 = 1.66640R12 = 424.669  D12 = 13.289 N7 = 1.62743R13 = 80.696   D13 = 25.985R14 = -1722.441          D14 = 13.289 N8 = 1.53577R15 = 278.635  D15 = 27.968R16 = - 202.476          D16 = 30.050 N9 = 1.53577R17 = -140.629 D17 = 0.532R18 = -363.277 D18 = 13.289 N10 = 1.62743R19 = 218.903  D19 = 29.504R20 = -83.243  D20 = 13.289 N11 = 1.66640R21 = 283.775  D21 = 54.746 N12 = 1.53577R22 = -148.014 D22 = 0.238R23 = -1124.876          D23 = 22.658 N13 = 1.53577R24 = -318.918 D24 = 0.166R25 = -1458.495          D25 = 24.222 N14 = 1.53577R26 = -330.471 D26 = 0.166R27 = 755.829  D27 = 36.611 N15 = 1.62743R28 = -278.914 D28 = 0.166R29 = 255.070  D29 = 29.666 N16 = 1.62743R30 = 5559.544 D30 = 0.252R31 = 142.643  D31 = 73.127 N17 = 1.53577R32 = -338.766 D32 = 13.289 N18 = 1.63609R33 = 83.174   D33 = 19.323R34 = -230.675 D34 = 13.289 N19 = 1.63609R35 = 165.095  D35 = 6.212R36 = 966.343  D36 = 46.467 N20 = 1.66645R37 = -306.352 D37 = 0.166R38 = 153.907  D38 = 90.916 N21 = 1.62743R39 = 384.718  D39 = 0.166R40 = 95.792   D40 = 26.859 N22 = 1.53577R41 = ∞  D41 = 0.166R42 = 98.954   D42 = 51.658 N23 = 1.61935R43 = 926.333  D43 = 3.877R44 = -272.350 D44 = 13.289 N24 = 1.66640R45 = ∞______________________________________φ.sub.1 (R13) = -0.0078, φ.sub.2 (R16) = -0.0027,φ.sub.1 (R19) = -0.0029, φ.sub.2 (R20) = -0.0080,φ.sub.3 (R33) = -0.0077______________________________________Example 7f = 92.56  NA = 0.48  IH = 18.1  L = 1000OB = 150.000  SK = 15.046  λ = 248 nm______________________________________R1 = 1439.092  D1 = 13.876  N1 = 1.50838R2 = -960.360  D2 = 0.125R3 = 666.083   D3 = 12.500  N2 = 1.50838R4 = 182.084   D4 = 14.112R5 = 1896.200  D5 = 12.500  N3 = 1.50838R6 = 212.178   D6 = 66.696R7 = 383.213   D7 = 26.225  N4 = 1.50838R8 = -405.603  D8 = 0.125R9 = 278.896   D9 = 25.759  N5 = 1.50838R10 = -671.954 D10 = 0.125R11 = 212.136  D11 = 33.976 N6 = 1.50838R12 = -543.385 D12 = 0.125R13 = 2010.730 D13 = 12.500 N7 = 1.50838R14 = 84.549   D14 = 33.039R15 =  -124.255          D15 = 12.500 N8 = 1.50838R16 = 152.113  D16 = 19.745R17 = 1275.450 D17 = 13.050 N9 = 1.50838R18 = -627.003 D18 = 15.823R19 = 732.677  D19 = 17.262 N10 = 1.50838R20 = -393.765 D20 = 0.125R21 = 449.220  D21 = 26.819 N11 = 1.50838R22 = -178.779 D22 = 53.499R23 = 365.033  D23 = 12.500 N12 = 1.50838R24 = 118.635  D24 = 25.300R25 = -99.983  D25 = 38.782 N13 = 1.50838R26 = 1359.503 D26 = 37.528R27 = -922.878 D27 = 40.110 N14 = 1.50838R28 = -201.836 D28 = 0.125R29 = 1275.499 D29 = 29.638 N15 = 1.50838R30 = -257.024 D30 = 0.125R31 = 326.989  D31 = 30.482 N16 = 1.50838R32 = -661.938 D32 = 0.125R33 = 177.265  D33 = 26.480 N17 = 1.50838R34 = 500.907  D34 = 0.125R35 = 121.991  D35 = 61.152 N18 = 1.50838R36 = 70.628   D36 = 26.894R37 = -1299.508          D37 = 12.500 N19 = 1.50838R38 = 2084.322 D38 = 0.125R39 = 60.854   D39 = 14.152 N20 = 1.50838R40 = 62.437   D40 = 11.022R41 = 134.373  D41 = 27.397 N21 = 1.50838R42 = 133.048  D42 = 0.125R43 = 68.073   D43 = 16.337 N22 = 1.50838R44 = 356.069  D44 = 3.427R45 = -286.670 D45 = 10.000 N23 = 1.50838R46 = 7501.444______________________________________φ.sub.1 (R14) = -0.0060, φ.sub.2 (R15) = -0.0041,φ.sub.1 (R24) = -0.0043, φ.sub.2 (R25) = -0.0051,φ.sub.3 (R36) = -0.0072______________________________________Example 8f = 91.09  NA = 0.48  IH = 18.1  L = 1000OB = 136.341  SK = 14.812  λ = 248 nm______________________________________R1 = 1332.715  D1 = 19.816  N1 = 1.50838R2 = -565.036  D2 = 0.125R3 = 1213.556  D3 = 12.500  N2 = 1.50838R4 = 178.094   D4 = 17.614R5 = 1737.407  D5 = 12.500  N3 = 1.50838R6 = 217.577   D6 = 68.375R7 = 398.868   D7 = 27.700  N4 = 1.50838R8 = -414.411  D8 = 0.125R9 = 273.365   D9 = 24.060  N5 = 1.50838R10 = -694.657 D10 = 0.125R11 = 214.700  D11 = 32.882 N6 = 1.50838R12 = -521.898 D12 = 1.060R13 = 3636.652 D13 = 12.500 N7 =  1.50838R14 = 85.823   D14 = 31.825R15 = -124.767 D15 = 12.500 N8 = 1.50838R16 = 151.401  D16 = 19.805R17 = 1233.963 D17 = 13.092 N9 = 1.50838R18 = -631.567 D18 = 15.843R19 = 703.428  D19 = 17.030 N10 = 1.50838R20 = -402.530 D20 = 0.125R21 = 442.276  D21 = 29.028 N11 = 1.50838R22 = -180.319 D22 = 52.693R23 = 362.711  D23 = 12.500 N12 = 1.50838R24 = 118.168  D24 = 25.749R25 = -100.287 D25 = 38.227 N13 = 1.50838R26 = 1003.801 D26 = 37.669R27 = -1240.566          D27 = 40.379 N14 = 1.50838R28 = -203.209 D28 = 0.404R29 = 1276.499 D29 = 30.364 N15 = 1.50838R30 = -257.384 D30 = 0.125R31 = 321.056  D31 = 29.361 N16 = 1.50838R32 = -691.355 D32 = 0.125R33 = 172.662  D33 = 30.058 N17 = 1.50838R34 = 466.284  D34 = 0.125R35 = 119.054  D35 = 55.556 N18 = 1.50838R36 = 70.157   D36 = 26.680R37 = -1400.393          D37 = 12.500 N19 = 1.50838R38 = 1663.520 D38 = 0.125R39 = 60.955   D39 = 14.621 N20 = 1.50838R40 = 62.656   D40 = 11.601R41 = 137.312  D41 = 28.753 N21 = 1.50838R42 = 131.425  D42 = 0.125R43 = 68.465   D43 = 18.479 N22 = 1.50838R44 = 434.028  D44 = 2.997R45 = -244.457 D45 = 10.000 N23 = 1.50838R46 = -4672.849______________________________________φ.sub.1 (R14) = -0.0059, φ.sub.2 (R15) = -0.0041,φ.sub.1 (R24) =  -0.0043, φ.sub.2 (R25) = -0.0051,φ.sub.3 (R36) = -0.0073______________________________________Example 9f = 1301.98  NA = 0.48  IH = 14.5  L = 1000OB = 163.364  SK = 12.420  λ = 248 nm______________________________________R1 = 785.237   D1 = 10.000  N1 = 1.50838R2 = 226.496   D2 = 35.207R3 = 338.103   D3 = 33.119  N2 = 1.50838R4 = -427.697  D4 = 0.100R5 = 220.682   D5 = 32.878  N3 = 1.50838R6 = -1689.440 D6 = 0.100R7 = 538.565   D7 = 16.636  N4 = 1.50838R8 = -2998.116 D8 = 42.310R9 = 1798.948  D9 = 43.869  N5 = 1.50838R10 = 86.594   D10 = 28.437R11 = -191.459 D11 = 10.000 N6 = 1.50838R12 =  -365.426          D12 = 6.206R13 = 205.426  D13 = 21.847 N7 = 1.50838R14 = -235.078 D14 = 0.100R15 = 140.249  D15 = 29.042 N8 = 1.50838R16 = 71.962   D16 = 23.223R17 = -103.352 D17 = 10.000 N9 = 1.50838R18 = 291.836  D18 = 21.563R19 = -169.640 D19 = 13.859 N10 = 1.50838R20 = -146.345 D20 = 1.260R21 = 548.483  D21 = 14.130 N11 = 1.50838R22 = -286.748 D22 = 0.100R23 = 370.410  D23 = 17.795 N12 = 1.50838R24 = -192.733 D24 = 0.100R25 = 289.711  D25 = 46.190 N13 = 1.50838R26 = 98.118   D26 = 23.251R27 = -93.137  D27 = 27.168 N14 = 1.50838R28 = 696.410  D28 = 35.100R29 = -2198.585          D29 = 41.200 N15 = 1.50838R30 = -183.512 D30 = 5.455R31 = 960.840  D31 = 28.000 N16 = 1.50838R32 = -248.042 D32 = 0.100R33 = 283.931  D33 = 29.471 N17 = 1.50838R34 = -582.356 D34 = 0.100R35 = 149.928  D35 = 37.042 N18 = 1.50838R36 = 467.490  D36 = 0.481R37 = 97.951   D37 = 50.000 N19 = 1.50838R38 = 62.066   D38 = 20.697R39 = 8857.666 D39 = 10.000 N20 = 1.50838R40 = 239.275  D40 = 0.100R41 = 86.347   D41 = 11.242 N21 = 1.50838R42 = 117.960  D42 = 0.100R43 = 96.904   D43 = 19.741 N22 = 1.50838R44 = 79.928   D44 = 1.583R45 = 61.664   D45 = 14.024 N23 = 1.50838R46 = 2778.127 D46 = 2.290R47 = -193.684 D47 =  9.000 N24 = 1.50838R48 = 543.831______________________________________φ.sub.1 (R10) = -0.0058, φ.sub.2 (R11) = -0.0027,φ.sub.1 (R16) = -0.0036, φ.sub.2 (R17) = -0.0071,φ.sub.1 (R26) = -0.0052, φ.sub.2 (R27) = -0.0055,φ.sub.3 (R38) = -0.0082______________________________________ 
    
     The abbreviations referred to in the examples stand for: R: curvature of each surface, D: surface separation, N: refractive index, f: focal length of the overall lens system, NA: imagewise numerical aperture, L: distance between object and image, OB: object position, SK: image position, λ: reference wavelength, and φ(R): refractive power of that surface. 
     How aberrations are corrected in the 1st to 9th embodiments is illustrated in FIGS. 10A to 10F through 18A to 18F. 
     As explained above, the present invention can successfully provide a projection lens system having wide exposure coverage and resolving power that is high in a sense of being corrected to substantially aplanatic conditions.