Catadioptric projection system for 157 nm lithography

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of International Application Serial No. PCT/EP01/13851, filed Nov. 28, 2001 and published in English on Jun. 6, 2002, which is still pending, and which claims priority from U.S. Provisional Patent Application Serial No. 60/253,508, filed Nov. 28, 2000 and from U.S. Provisional Patent Application Serial No. 60/250,996, filed Dec. 4, 2000, all of which are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to projection systems for photolithography, and particularly to catadioptric systems including first and second optical imaging groups for 157 nm lithography.

[0004] 2. Discussion of the Related Art

[0005] Extending DUV lithography to sub 100-nm linewidths requires a projection system with a high numerical aperture, e.g., 0.65-0.75 or larger, at a wavelength of 157 nm. As optical lithography is extended into the vacuum ultraviolet (VUV), issues surrounding the laser linewidth and material availability could cause substantive delays to the development of a commercial 157 nm step/repeat or step/scan tool. Therefore, it is desired to investigate optical configurations that minimize the consumption of calcium fluoride.

[0006] Microlithographic reduction projection catadioptric objectives, such as that shown and described with respect to FIG. 3 of European patent application no. EP 0 779 528 A2, which is hereby incorporated by reference, may be understood as variants of pure catoptric objectives. FIG. 3 of the '528 application shows a system having six minors and three lenses. The optical surfaces are generally symmetric to a common axis, and the object plane and the image plane are situated on this same axis upstream and downstream of the objective, respectively. As described in the '528 application, the system of FIG. 2 therein has a numerical aperture of only 0.55 and that of FIG. 3 therein only 0.6. In addition, all but one of the six mirrors shown at FIG. 3 are cut off sections of a bodies of revolution, yielding mounting and adjustment face difficulties. Also, the lenses shown in FIG. 3 serve only as correcting elements having minor effect. In addition, the most imageward (or optically closest to the image plane) mirror described in the '528 application is concave. It is desired to have an objective with a higher numerical aperture, and which is constructed for easier mounting and adjustment.

[0007] A similar objective to that described in the '528 application (above) is disclosed at U.S. Pat. No. 4,701,035, which is hereby incorporated by reference. The objective shown at FIG. 12 of the '035 patent, for example, has nine mirrors, two lenses and two intermediate images. The object plane and image plane are situated within the envelope of the objective. The objective described in the '035 application also exhibits a low numerical aperture and offers similar mounting and adjustment difficulties as described above with respect to the '528 application. In both the '528 and '035 applications, the image field is an off-axis ring sector.

[0008] An axially symmetric type of catadioptric objective is disclosed in German patent document DE 196 39 586 A (see also U.S. patent application Ser. No. 09/263,788), each application of which is hereby incorporated by reference. The '586 application discloses an objective having two opposing concave mirrors, an image field centered at the common axis and a central obscuration of the aperture. It is recognized herein that it is desired to have an axially symmetric objective having an unobscured aperture. Another type of catadioptric objective for microlithographic reduction projection has only one concave mirror and a folding mirror, as is described at U.S. Pat. No. 5,052,763 and European patent application no. EP 0 869 383 A, which are each hereby incorporated by reference.

[0009] It is recognized herein that catadioptric optical systems have several advantages, especially in a step and scan configuration, and that it is desired to develop such systems for wavelengths below 365 nm. One catadioptric system concept relates to a Dyson-type arrangement used in conjunction with a beam splitter to provide ray clearance and unfold the system to provide for parallel scanning (see, e.g., U.S. Pat. Nos. 5,537,260, 5,742,436 and 5,805,357, which are incorporated by reference). However, these systems have a serious drawback since the size of this beam splitting element becomes quite large as the numerical aperture is increased up to and beyond 0.65 to 0.70, malting the procurement of bulk optical material with sufficient quality (in three-dimensions) a high risk endeavor. This problem is exacerbated as wavelengths are driven below 193 nm because the selection of material that can be manufactured to lithographic quality is severely limited.

[0010] To circumvent this problem, it is recognized herein that it is desired to develop systems without beamsplitters. However, it is difficult to achieve an adequately high numerical aperture (e.g., U.S. Pat. Nos. 4,685,777, 5,323,263, 5,515,207 and 5,815,310, which are incorporated by reference), or to achieve a fully coaxial configuration, instead of relying on the use of folding mirrors to achieve parallel scanning (e.g., U.S. Pat. No. 5,835,275 and EP 0 816 892, which are incorporated by reference) and thereby complicating the aligmnent and structural dynamics of the system. In addition, it is desired to have an optical design that generally does not utilize too many lens elements, which can greatly increase the mass of the optical system.

[0011] WO 01/51 979 A (U.S. ser. Nos. 60/176,190 and 09/761,5762) and WO 01/55767 A (U.S. ser. No. 60/176,190 and 09/759,806—all commonly owned and published after the priority date of this application—show similar coaxial catadioptric objectives with 4 mirrors or more.

[0012] EP 1 069 448 A1 published after the priority date of this application shows a coaxial catadioptric objective with two curved mirrors and a real, intermediate image located besides the primary mirror.

[0013] All cited publications are incorporated herein by reference in their entirety. It is desired to develop a compact, coaxial, catadioptric projection system for deep ultraviolet and/or vacuum ultraviolet lithography that uses no beamsplitters or fold mirrors in is optical path.

[0014] It is an object of the invention to provide an objective for microlithographic projection reduction having high chromatic correction of typical bandwidths of excimer laser light sources, which permits a high image-side numerical aperture, and which reduces complexity with respect to mounting and adjusting.

SUMMARY OF THE INVENTION

[0015] In view of the above, a photolithography reduction projection catadioptric objective is provided including a first optical group including an even number of at least four mirrors, and a second at least substantially dioptric optical group more imageward than the first optical group including a number of lenses for providing image reduction. The first optical group provides compensative axial color correction for the second optical group according to claim 1. Other variations and preferred embodiments are subject of claims 2 to 26.

[0016] A preferred embodiment according to claim 11 is a photolithographic reduction projection catadioptric objective including a first optical group including an even number of at least six mirrors, and a second at least substantially dioptric optical group more imageward than the first optical group including a number of lenses for providing image reduction. This increased number of mirrors gives more degrees of freedom to the correction and simplifies the design for stressed qualities.

BRIEF DESCRIPTION OF THE DRAWING

[0017]FIG. 1 shows the lens section of a projection objective for 157 nm photolithography according to a first preferred embodiment.

[0018]FIG. 2 shows the lens section of a second preferred embodiment.

INCORPORATION BY REFERENCE

[0019] What follows is a cite list of references which are, in addition to the references cited above in the background section, hereby incorporated by reference into the detailed description of the preferred embodiment, as disclosing alternative embodiments of elements or features of the preferred embodiment not otherwise set forth in detail herein with reference to FIG. 1 or FIG. 2. A single one or a combination of two or more of these references may be consulted to obtain a variation of the preferred embodiment described above. Further patent, patent application and non-patent references, and discussion thereof, cited in the background and/or elsewhere herein are also incorporated by reference into the detailed description of the preferred embodiment with the same effect as just described with respect to the following references:

[0020] U.S. Pat. Nos. 5,323,263, 5,515,207, 5,052,763, 5,537,260, 4,685,777, 5,071,240, 5,815,310, 5,401,934, 4,595,295, 4,232,969, 5,742,436, 5,805,357, 5,835,275, 4,171,871, 5,241,423, 5,089,913, 5,159,172, 5,608,526, 5,212,588, 5,686,728, 5,220,590, 5,153,898, 5,353,322, 5,315,629, 5,063,586, 5,410,434, 5,956,192, 5,071,240, 5,078,502, 6,014,252, 5,805,365, 6,033,079, 4,701,035 and 6,142,641; and German patent no. DE 196 39 586 A; and U.S. patent applications Nos. 09/263,788 and 09/761,562; and European patent applications no. EP 0 816 892 A1, EP 0 779 528 A2 and EP 0 869 383 A; and

[0021] “Design of Reflective Relay for Soft X-Ray Lithography”, J. M. Rodgers, T. E. Jewell, International Lens Design Conference, 1990;

[0022] “Optical System Design Issues in Development of Projection Camera for EUV Lithography”, T. E. Jewell, SPIE Volume 2437, pages 340-347;

[0023] “Ring-Field EUVL Camera with Large Etendu”, W. C. Sweatt, OSA TOPS on Extreme Ultraviolet Lithography, 1996;

[0024] “Phase Shifting Diffraction Interferometry for Measuring Extreme Ultraviolet Optics”, G. E. Sornargren, OSA TOPS on Extreme Ultraviolet Lithography, 1996; and

[0025] “EUV Optical Design for a 100 nm CD Imaging System”, D. W. Sweeney, R Hudyma, H. N. Chapman, and D. Shafer, SPIE Volume 3331, pages 2-10

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] A catadioptric projection system according to a preferred embodiment herein is schematically shown at FIG. 1 and includes two distinct optical groups G<b>1</b> and G<b>2</b>. Group G<b>1</b> is a catadioptric group including mirrors M<b>1</b>-M<b>6</b> and lenses E<b>1</b>-E<b>3</b>, as shown in FIG. 1. An object or mask plane Ob is disposed to the left of group G<b>1</b> in FIG. 1 or optically before group G<b>1</b>. Group G<b>2</b> is disposed optically after group G<b>1</b> and to the right of group G<b>1</b> in FIG. 1. An image or wafer plane Im is disposed optically after group G<b>2</b> and to the right of group G<b>2</b> in FIG. 1.

[0027] Group G<b>1</b> functions by correcting field aberrations and providing a conjugate stop position for correction of axial chromatic aberration. Group G<b>2</b> is a dioptric group including lens elements E<b>4</b>-E<b>13</b>, as also shown in FIG. 1. Group G<b>2</b> lies aft of G<b>1</b>, or optically nearer the image plane of the system, enabling the system to achieve numerical apertures in excess of 0.65, 0.70 and even 0.75. This catadioptric system achieves a high numerical aperture preferably using no beamsplitters nor fold mirrors. The description herein examines the performance of the preferred system of FIG. 1.

[0028] As mentioned, the system of FIG. 1 is separated into two optical groups, i.e., group G<b>1</b> including 6 mirrors and 3 lens elements and group G<b>2</b> including 10 individual lens elements. The design is purely coaxial with a single common centerline (axis of symmetry) using an off-axis field to achieve the necessary ray clearance so that the mask and wafer planes are parallel, Group G<b>1</b> forms a virtual image V<b>1</b> located behind mirror M<b>6</b> at a reduction of ˜0.8×. Group G<b>2</b> takes this virtual image and forms a usable real image at the wafer. Group G<b>2</b> takes this virtual image and forms a usable real image at the wafer. Group G<b>2</b> operates at a reduction of about 0.25×, allowing the system to achieve a desired reduction of 0.20×. A complete optical prescription is found in Table 2, below, describing the optical surfaces in Code V format.

[0029] Referring to FIG. 1, how the preferred design achieves the performance listed in Table 1 is now explained. To correct chromatic aberration, the aperture stop AS that lies in group G<b>2</b> has a conjugate position located within group G<b>1</b> preferably at, and alternatively near, mirror M<b>2</b>. At M<b>2</b>, strong negative lenses E<b>2</b>/B<b>3</b> are used in a double-pass configuration for inducing overcorrected (positive) axial chromatic aberration used to balance or correct an undercorrected (negative) axial chromatic aberration created by the strong positive optical power of group G<b>2</b>. With regard to lateral chromatic aberration, FIG. 1 shows an aperture stop AS in group G<b>2</b> placed in a quasi-symmetric manner, allowing the Lateral chromatic aberration to be at least nearly self-corrected within group G<b>2</b> itself. In practice, lateral chromatic aberration of a few parts per million (ppm) may be within tolerance within group G<b>2</b> and can be corrected using slight asymmetry of the chief ray near the conjugate stop position at mirror M<b>2</b>.

[0030] By balancing aberration correction between G<b>1</b> and G<b>2</b>, the monochromatic aberrations are corrected in such a way to leave the lens elements within G<b>2</b> “unstressed.” The term “unstressed” is used to signify the fact that no steep ray bendings are used within G<b>2</b> to promote high-order aberration correction. Both the chief and marginal rays exhibit this behavior. The fact that group G<b>2</b> is “unstressed” is advantageous when manufacturing and assembly tolerances are considered in detail.

[0031] Overall, the system of FIG. 1 includes 6 mirrors and 13 lens elements in a coaxial configuration all coaxial to axis A. The design utilizes an off-axis field to enable ray clearance and allow the mask and wafer planes to be parallel. Lens element E<b>1</b> of group G<b>1</b> is used to make the chief ray telecentric at the mask plane. Group G<b>1</b> forms a virtual image behind mirror M<b>6</b>, which is relayed by the dioptric group G<b>2</b> to form a final image at the wafer plane. <tables id="TABLE-US-00001" num="1"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="217PT" align="center" /><thead><row><entry namest="1" nameend="1" align="center">TABLE 1</entry></row></thead><tbody valign="top"><row><entry /></row><row><entry namest="1" nameend="1" align="center" rowsep="1" /></row><row><entry>System of FIG. 1 Performance Summary</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="98PT" align="left" /><colspec colname="2" colwidth="91PT" align="left" /><tbody valign="top"><row><entry /><entry>Parameter</entry><entry>Performance</entry></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row><row><entry /><entry>Wavelength (nm)</entry><entry> 157</entry></row><row><entry /><entry>Spectral band (pm)</entry><entry>  0.5</entry></row><row><entry /><entry>Reduction ratio (R)</entry><entry>  0.20</entry></row><row><entry /><entry>Field size (mm)</entry><entry>22 × 7 rectangular</entry></row><row><entry /><entry>Numerical aperture</entry><entry>  0.75</entry></row><row><entry /><entry>(NA)</entry></row><row><entry /><entry>RMS wavefront error</entry><entry>  0.013 λ</entry></row><row><entry /><entry>(waves)</entry></row><row><entry /><entry>Distortion (nm)</entry><entry>&lt;1 nm</entry></row><row><entry /><entry>PAC (ppm)</entry><entry> 39.0 ppm</entry></row><row><entry /><entry>PLC (ppm)</entry><entry>  0.0 ppm</entry></row><row><entry /><entry>Total track (mm)</entry><entry>1250</entry></row><row><entry /><entry>distance Ob - Im</entry></row><row><entry /><entry>Front working</entry><entry> 25.0</entry></row><row><entry /><entry>distance (mm)</entry></row><row><entry /><entry>Back working distance</entry><entry> 10.0</entry></row><row><entry /><entry>(mm)</entry></row><row><entry /><entry>Blank mass (kg,</entry><entry> 39.0</entry></row><row><entry /><entry>estimated)</entry></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

[0032] Table 1 shows that the monochromatic RMS wavefront error, distortion, and chromatic aberrations PAC—paraxial axial color aberration and PLC—paraxial local color aberration are reduced small residual values as desired for precision lithographic projection systems. Further, the system of FIG. 1 may be confined within a volume that is similar to or smaller than conventional systems, meaning that the footprint of legacy tools can be maintained, if desired. <tables id="TABLE-US-00002" num="2"><table frame="none" colsep="0" rowsep="0" pgwide="1"><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="266PT" align="center" /><thead><row><entry namest="1" nameend="1" align="center">TABLE 2</entry></row></thead><tbody valign="top"><row><entry /></row><row><entry namest="1" nameend="1" align="center" rowsep="1" /></row><row><entry>Optical Design Prescription for the System of FIG. 1</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="OFFSET" colwidth="42PT" align="left" /><colspec colname="1" colwidth="21PT" align="left" /><colspec colname="2" colwidth="21PT" align="left" /><colspec colname="3" colwidth="21PT" align="left" /><colspec colname="4" colwidth="161PT" align="left" /><tbody valign="top"><row><entry /><entry>RDY</entry><entry>THI</entry><entry>RMD</entry><entry>GLA</entry></row><row><entry /><entry namest="OFFSET" nameend="4" align="center" rowsep="1" /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>OBJ:</entry><entry>INFINITY</entry><entry>25.000000</entry><entry /></row><row><entry> 1:</entry><entry>INFINITY</entry><entry> 0.000000</entry></row><row><entry> 2:</entry><entry>INFINITY</entry><entry> 0.000000</entry></row><row><entry> 3:</entry><entry>329.41693</entry><entry>30.000000</entry><entry>‘cafl_vuv’</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 0.722126</entry></row><row><entry /><entry>A :0.000000E + 00 B :−.225942E − 11 C :0.167998E − 15 D :−.128550E − 20</entry></row><row><entry /><entry>E :−.233823E − 24 F :0.685735E − 29 G :0.000000E + 00 H :0.000000E − 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry> 4:</entry><entry> 502.56918</entry><entry> 59.208438</entry></row><row><entry> 5:</entry><entry>INFINITY</entry><entry> 347.586957</entry></row><row><entry> 6:</entry><entry>−1183.47149</entry><entry>−347.586957 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 14.816567</entry></row><row><entry /><entry>A :−.127089E − 08 B :0.812330E − 14 C :−.123118E − 18 D :0.894383E − 23</entry></row><row><entry /><entry>E :−.276494E − 27 F :0.402755E − 32 C :0.000000E + 00 H :0.000000E + 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry> 7:</entry><entry> 279.62176</entry><entry>−7.500000</entry><entry>‘cafl_vuv’</entry></row><row><entry> 8:</entry><entry> 745.02111</entry><entry>−5.835889</entry></row><row><entry> 9:</entry><entry> 350.74458</entry><entry>−7.500000</entry><entry>‘cafl_vuv’</entry></row><row><entry>10:</entry><entry>1226.35940</entry><entry>−8.372549</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>11:</entry><entry>324.93068</entry><entry> 8.372549 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 0.069031</entry></row><row><entry /><entry>A :−.551054E − 09 B :−.166403E − 13 C :−.307699E − 18 D :0.277748E − 22</entry></row><row><entry /><entry>E :−.680019E − 26 F :0.506026E − 30 G :0.000000E + 00 H :0.000000E + 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>12:</entry><entry>1226.35940</entry><entry>  7.500000</entry><entry>‘cafl_vuv’</entry></row><row><entry>13:</entry><entry> 350.74458</entry><entry>  5.835889</entry></row><row><entry>14:</entry><entry> 745.02111</entry><entry>  7.500000</entry><entry>‘cafl_vuv’</entry></row><row><entry>15:</entry><entry> 279.62176</entry><entry> 304.397688</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>16:</entry><entry> 490.28038</entry><entry>−244.852865 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : −1.803201</entry></row><row><entry /><entry>A :−.482804E − 08 B :−.128400E − 12 C :0.242635E − 17 D :−.680221E − 22</entry></row><row><entry /><entry>B :0.237919E − 26 F :−.315262E − 31 G :0.000000E + 00 H :0.000000E + 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>17:</entry><entry>667.70113</entry><entry>565.726496 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : −0.118347</entry></row><row><entry /><entry>A :−.275181E − 09 B :−.327224E − 14 C :0.200875E − 19 D :−.620470E − 24</entry></row><row><entry /><entry>B :0.627048E − 29 F :−.394543E − 34 G :0.000000E + 00 H :0.000000E + 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>18:</entry><entry>INFINITY</entry><entry>25.997938</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>SLB: “Intermediate image”</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>19:</entry><entry>−1126.18103</entry><entry>−178.682300 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 7.738777</entry></row><row><entry /><entry>A :−.668802E − 08 B :0.253685E − 12 C :−.548789E − 17 D :0.625386E − 22</entry></row><row><entry /><entry>E :−.276305E − 27 F :−.120188E − 33 G :0.000000E + 00 H :0.000000E + 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>20:</entry><entry>−1002.36339</entry><entry>178.682300 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 50.616566</entry></row><row><entry /><entry>A :−.973184E − 08 B :0.308396E − 12 C :−.511443E − 16 D :0.428520E − 20</entry></row><row><entry /><entry>E :−.217208E − 24 F :0.51841SE − 29 G :0.000000E + 00 H :0.000000E + 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>21:</entry><entry>INFINITY</entry><entry>−324.644232</entry></row><row><entry>22:</entry><entry>INFINITY</entry><entry> 324.644232</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>SLB: “Virtual image”</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>23:</entry><entry>INFINITY</entry><entry>139.926509</entry><entry /></row><row><entry>24:</entry><entry>532.50558</entry><entry> 30.000000</entry><entry>‘cafl_vuv’</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : −28.969955</entry></row><row><entry /><entry>A :0.000000E + 00 B :−.109172E − 11 C :0.625819E − 16 D :−.274325E − 20</entry></row><row><entry /><entry>E :0.634878E − 25 F :0.581549E − 29 G :0.000000E + 00 H :0.000000E + 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>25:</entry><entry> −584.92060</entry><entry> 2.500000</entry><entry /></row><row><entry>26:</entry><entry> 1292.88867</entry><entry>13.668481</entry><entry>‘cafl_vuv’</entry></row><row><entry>27:</entry><entry>−1383.77341</entry><entry> 2.500000</entry></row><row><entry>28:</entry><entry> 760.97648</entry><entry>15.674455</entry><entry>‘cafl_vuv’</entry></row><row><entry>29:</entry><entry>−1077.75076</entry><entry>11.001421</entry></row><row><entry>30:</entry><entry> −250.22566</entry><entry>10.000000</entry><entry>‘cafl_vuv’</entry></row><row><entry>31:</entry><entry> −500.99843</entry><entry>11.138638</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>STO:</entry><entry>INFINITY</entry><entry>22.619203</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>SLB: “stop”</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>33:</entry><entry>−298.09900</entry><entry>18.822972</entry><entry>‘cafl_vuv’</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 6.689541</entry></row><row><entry /><entry>A :0.000000E + 00 B :0.346206E − 12 C :−.498302E − 17 D :0.272385E − 20</entry></row><row><entry /><entry>E :−.106617E − 24 F :0.175645E − 28 G :0.000000E + 00 H :0.000000E + 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>34:</entry><entry>−1073.42340</entry><entry> 0.500000</entry><entry /></row><row><entry>35:</entry><entry> 267.47103</entry><entry>50.000000</entry><entry>‘cafl_vuv’</entry></row><row><entry>36:</entry><entry> −607.58973</entry><entry> 0.592125</entry></row><row><entry>37:</entry><entry> 258.51826</entry><entry>27.182889</entry><entry>‘cafl_vuv’</entry></row><row><entry>38:</entry><entry>−8945.70709</entry><entry> 0.500000</entry></row><row><entry>39:</entry><entry> 159.70628</entry><entry>39.768717</entry><entry>‘cafl_vuv’</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : −1.214880</entry></row><row><entry /><entry>A :0.000000E + 00 B :−.252828E − 11 C :−.632030E − 16 D :−.765024E − 21</entry></row><row><entry /><entry>E :0.477017E − 24 F :−.163970E − 28 G :0.000000E + 00 H :0.000000E + 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>40:</entry><entry>−746.03878</entry><entry> 0.500000</entry><entry /></row><row><entry>41:</entry><entry> 122.36092</entry><entry>43.154424</entry><entry>‘cafl_vuv’</entry></row><row><entry>42:</entry><entry> 95.77143</entry><entry>4.340799</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 1.012065</entry></row><row><entry /><entry>A :0.000000E + 00 B :0.214891E − 12 C :−.187071E − 14 D :−.681922E − 18</entry></row><row><entry /><entry>E :0.313376E − 22 F :0.000000E + 00 G :0.000000E + 00 H :0.000000E + 00</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>43:</entry><entry> 115.81595</entry><entry>30.082531</entry><entry>cafl_vuv</entry></row><row><entry>44:</entry><entry>−1828.47137</entry><entry> 9.930603</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>IMG:</entry><entry>INFINITY</entry><entry> 0.000000</entry></row><row><entry namest="1" nameend="3" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

[0033] The catadioptric projection system according to a second preferred embodiment herein is schematically shown at FIG. 2 and includes two distinct optical groups G<b>1</b>′ and G<b>2</b>′. Group G<b>1</b>′ is a catadioptric group including mirrors M<b>1</b>′-M<b>6</b>′ and lenses E<b>1</b>′-E<b>3</b>′, as shown in FIG. 2. An object or mask plane Ob′ is disposed to the left of group G<b>1</b>′ in FIG. 2 or optically before Group G<b>1</b>′. Group G<b>2</b>′ is disposed optically after group G<b>1</b>′ and to the right of G<b>1</b>′ in FIG. 2. An image or wafer plane Im′ is disposed optically after group G<b>2</b>′ and to the right of group G<b>2</b>′ in FIG. 2.

[0034] Group G<b>1</b>′ functions by correcting field aberrations and providing a conjugate stop CS′ position for correction of axial chromatic aberration. Group G<b>2</b>′ is a dioptric group including lens elements E<b>4</b>′-E<b>13</b>′, as also shown in FIG. 2. Group G<b>2</b>′ lies aft of G<b>1</b>′, or optically nearer the image plane Im′ of the system, enabling the system to achieve numerical apertures in excess of 0.65, 0.70 and even 0.75. This catadioptric system achieves a high numerical aperture preferably using no beamsplitters nor fold mirrors. The description herein examines the performance of the second preferred embodiment of FIG. 2.

[0035] The first embodiment of FIG. 1 features independent correction of lateral chromatic aberration in the individual imaging groups. This feature influenced the optical construction in terms of stop position(s), element powers and element shapes. In the present second embodiment, the independent lateral color correction feature is not included and a balance of lateral color is struck between the fore and aft groups.

[0036] Group G<b>1</b>′ is a catadioptric group that functions by correcting field aberrations and providing a conjugate stop position to correct axial chromatic aberration. Group G<b>2</b>′ is a dioptric group that lies aft of G<b>1</b>′ enabling the system to achieve numerical apertures (NA) in excess of 0.65, and preferably at least 0.70, or 0.75, or even 0.80 or higher. For example, a system in accord with the preferred embodiment may be configured to exhibit a NA of 0.79 while advantageously having a RMS wavefront error of only 0.0115λ. That is, the system may be configured with a NA above 0.75, while maintaining the RMS wavefront error below 0.02λ, and even below 0.015λ.

[0037] The system shown in FIG. 2 has two distinct groups, as mentioned above. Group G<b>1</b>′ includes an even number of at least four mirrors, and preferably has six mirrors M<b>1</b>′-M<b>6</b>′. Group G<b>1</b>′ further preferably includes three lens elements E<b>1</b>′-E<b>3</b>′. Group G<b>2</b>′ includes a lens barrel of ten individual lens elements E<b>4</b>′-E<b>13</b>′, as shown in FIG. 2. The design is coaxial having a single common centerline, respectively, of the system of two optical groups G<b>1</b>′ and G<b>2</b>′ shown in FIG. 2. The design uses an off-axis field to achieve ray clearances in group G<b>1</b>′ Since Group G<b>2</b>′ is dioptric, ray clearance problems are eliminated enabling a system with a high numerical aperture. The concept also provides for unlimited scanning of the mask and wafer in a parallel configuration.

[0038] Group G<b>1</b>′ of FIG. 2 forms a minified, virtual image V<b>1</b>′ located behind mirror M<b>6</b>′ at a reduction of ˜0.8×. Group G<b>2</b>′ relays this virtual image V<b>1</b>′ to form a usable real image Im at the wafer. Group G<b>2</b>′ operates at a reduction of about 0.25×. allowing the system to achieve a reduction of 0.20×. A complete optical prescription is found in Table 5 below, describing the optical surfaces in Code V format.

[0039] To correct chromatic aberration, the aperture stop AS′ that lies in group G<b>2</b>′ has a conjugate stop CS′ position in group G<b>1</b>′ between mirror M<b>1</b>′ and M<b>2</b>′. This allows a negative chief ray height at elements E<b>2</b>′ and E<b>3</b>′ (for positive field height at the reticle (Ob′)). This chief ray height, when combined with the sign of the marginal ray and the negative power of the E<b>2</b>′/E<b>3</b>′ pair, provides for a lateral chromatic aberration contribution that substantially cancels the lateral color contribution from group G<b>2</b>′. Assuming a spectral bandwidth of 0.5 μm, this specific embodiment has a paraxial lateral color contribution from E<b>2</b>′/E<b>3</b>′ of ˜35 ppm, whereas the paraxial lateral color contribution from Group G<b>2</b>′ is ˜35 ppm, resulting in an advantageous sum total of approximately 0 ppm. The principle result is that the power distribution and shapes of the lenses in group G<b>2</b>′ take on a very advantageous form.

[0040]FIG. 2 also specifically shows raytrace layout of the preferred embodiment. The system shown includes six mirrors M<b>1</b>′-M<b>6</b>′ and thirteen lens elements E<b>1</b>′-E<b>3</b>′ in a coaxial configuration. The design utilizes an off-axis field (ring field, rectangular slit field or the like) to enable ray clearance and allow the mask and wafer planes Ob′, Im′ to be parallel. Element E<b>1</b> is preferably used advantageously to make the chief ray telecentric at the mask plane Ob′, as described in more detail below. Group G<b>1</b>′ forms a virtual image V<b>1</b>′ behind mirror M<b>6</b>′, which is relayed by dioptric group G<b>2</b>′ to form the final image at the wafer plane Im′. A real intermediate image Im′ is also formed between mirrors M<b>4</b>′ and M<b>5</b>′ of group G<b>1</b>′, as shown in FIG. 2.

[0041] At mirror M<b>2</b>′, negative lenses E<b>2</b>′/E<b>3</b>′ are used in a double-pass configuration to induce overcorrected (positive) axial chromatic aberration used to correct undercorrected (negative) axial chromatic aberration created by the strong positive optical power of group G<b>2</b>′. The monochromatic aberrations are corrected via a balance between groups G<b>1</b>′ and G<b>2</b>′. In addition, this is done in such a manner as to leave the lens elements E<b>4</b>′-E<b>13</b>′ in group G<b>2</b>′ “unstressed” as in the first embodiment.

[0042] Lens element E<b>1</b>′ provides for the telecentric condition at the plane Ob′ of the mask. It is advantageous to have positive optical power near the mask to reduce the chief ray height on mirror M<b>1</b>′. Lens element E<b>1</b>′ appears to lie in conflict with the substrate of mirror M<b>2</b>′. To achieve this concept, it is preferred that only a small off-axis section of E<b>1</b>′ be used. This means that pieces of a complete E<b>1</b>′ could be sectioned to yield pieces for multiple projection systems, further reducing the required blank mass of a single system.

[0043] Another option to resolve the apparent conflict between lens E<b>1</b>′ and the substrate of mirror M<b>2</b>′ is to place lens E<b>1</b>′ between mirrors M<b>1</b>′ and M<b>2</b>′, such as somewhere close to the group of lens elements E<b>2</b>′/E<b>3</b>′. In this Manner, the complete lens would be used. <tables id="TABLE-US-00003" num="3"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="217PT" align="center" /><thead><row><entry namest="1" nameend="1" align="center">TABLE 3</entry></row></thead><tbody valign="top"><row><entry /></row><row><entry namest="1" nameend="1" align="center" rowsep="1" /></row><row><entry>Performance Summary of System of FIG. 2</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="35PT" align="left" /><colspec colname="1" colwidth="105PT" align="left" /><colspec colname="2" colwidth="77PT" align="left" /><tbody valign="top"><row><entry /><entry>Parameter</entry><entry>Performance</entry></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row><row><entry /><entry>Wavelength (nm)</entry><entry> 157</entry></row><row><entry /><entry>Spectral band (pm)</entry><entry>  0.5</entry></row><row><entry /><entry>Reduction Ratio (R)</entry><entry>  0.20</entry></row><row><entry /><entry>Field size (mm)</entry><entry>22 × 7</entry></row><row><entry /><entry>Numerical aperture</entry><entry>  0.75</entry></row><row><entry /><entry>(NA)</entry></row><row><entry /><entry>RMS wavefront error</entry><entry>  0.006 λ</entry></row><row><entry /><entry>(waves)</entry></row><row><entry /><entry>Distortion (nm)</entry><entry>&lt;2 nm</entry></row><row><entry /><entry>PAC (ppm)</entry><entry> 42.0 ppm</entry></row><row><entry /><entry>PLC (ppm)</entry><entry>  0.7 ppm</entry></row><row><entry /><entry>Total track (mm)</entry><entry>1064</entry></row><row><entry /><entry>Front working</entry><entry> 28.0</entry></row><row><entry /><entry>distance (mm)</entry></row><row><entry /><entry>Back working distance</entry><entry>  8.7</entry></row><row><entry /><entry>(mn)</entry></row><row><entry /><entry>Blank mass (kg,</entry><entry> 34.4</entry></row><row><entry /><entry>estimated)</entry></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

[0044] Table 3 summarizes design performance of the system of the preferred embodiment. The system has a composite RMS wavefront error of 0.006λ, with NA=0.75, evaluated monochromatically over the field. The distortion is less than 2 nm at all field points, and the lateral color PLC is corrected to better than 1 nm. The axial color PAC is also small and could be reduced further if desired and as understood by those spilled in the art. This design approaches an advantageous “zero aberration” condition. <tables id="TABLE-US-00004" num="4"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="217PT" align="center" /><thead><row><entry namest="1" nameend="1" align="center">TABLE 4</entry></row></thead><tbody valign="top"><row><entry /></row><row><entry namest="1" nameend="1" align="center" rowsep="1" /></row><row><entry>Composite RMS wavefront error vs. NA</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="42PT" align="left" /><colspec colname="1" colwidth="21PT" align="center" /><colspec colname="2" colwidth="154PT" align="center" /><tbody valign="top"><row><entry /><entry>NA</entry><entry>RMS wavefront error</entry></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="42PT" align="left" /><colspec colname="1" colwidth="21PT" align="char" char="." /><colspec colname="2" colwidth="154PT" align="center" /><tbody valign="top"><row><entry /><entry>0.75</entry><entry>0.0058 λ</entry></row><row><entry /><entry>0.76</entry><entry>0.0061 λ</entry></row><row><entry /><entry>0.77</entry><entry>0.0064 λ</entry></row><row><entry /><entry>0.78</entry><entry>0.0075 λ</entry></row><row><entry /><entry>0.79</entry><entry>0.0115 λ</entry></row><row><entry /><entry>0.80</entry><entry>0.0207 λ</entry></row><row><entry /><entry>0.81</entry><entry>0.0383 λ</entry></row><row><entry /><entry>0.82</entry><entry>0.0680 λ</entry></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

[0045] As desired dimensional specifications of IC manufactures shrink, the numerical aperture may be advantageously scaled in accord with the preferred embodiment. Table 3 illustrates how the design of FIG. 1 may be scaled as the numerical aperture is increased. A local minimum that does not scale well with aperture is preferably avoided, since otherwise to achieve increased numerical aperture would involve additional redesign. The aperture scaling of the preferred embodiment illustrated at FIG. 1 is presented in Table 3, above. From a qualitative standpoint, the table reveals that the preferred embodiment herein scales well with numerical aperture. For example, the composite RMS only grows by 0.005λ from 0.0058λ to 0.0115λ as the NA is scaled from 0.75 to 0.79. The results indicate that the system of the preferred embodiment my be scaled to a numerical aperture larger than 0.80. <tables id="TABLE-US-00005" num="5"><table frame="none" colsep="0" rowsep="0" pgwide="1"><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="266PT" align="center" /><thead><row><entry namest="1" nameend="1" align="center">TABLE 5</entry></row></thead><tbody valign="top"><row><entry /></row><row><entry namest="1" nameend="1" align="center" rowsep="1" /></row><row><entry>Optical Design Prescription of System of FIG. 2</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="OFFSET" colwidth="42PT" align="left" /><colspec colname="1" colwidth="21PT" align="left" /><colspec colname="2" colwidth="21PT" align="left" /><colspec colname="3" colwidth="21PT" align="left" /><colspec colname="4" colwidth="161PT" align="left" /><tbody valign="top"><row><entry /><entry>RDY</entry><entry>THI</entry><entry>RMD</entry><entry>GLA</entry></row><row><entry /><entry namest="OFFSET" nameend="4" align="center" rowsep="1" /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>OBJ:</entry><entry>INFINITY</entry><entry> 28.000000</entry><entry /></row><row><entry> 1:</entry><entry>INFINITY</entry><entry>  0.000000</entry></row><row><entry> 2:</entry><entry>INFINITY</entry><entry>  0.000000</entry></row><row><entry> 3:</entry><entry> 256.21415</entry><entry> 19.957583</entry><entry>‘cafl_vuv’</entry></row><row><entry> 4:</entry><entry> 461.83199</entry><entry> 42.954933</entry></row><row><entry> 5:</entry><entry>INFINITY</entry><entry> 329.408468</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry> 6:</entry><entry>−947.39721</entry><entry>−329.408468 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 10.217685</entry></row><row><entry /><entry>A :−.271423E − 08 B :0.413774E − 13 C :0.119957E − 17 D :0.566939E − 22</entry></row><row><entry /><entry>E :−.201485E − 26</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry> 7:</entry><entry> 235.67059</entry><entry> −5.250000</entry><entry>‘cafl_vuv’</entry></row><row><entry> 8:</entry><entry>1202.79595</entry><entry>−18.801014</entry></row><row><entry> 9:</entry><entry> 199.92931</entry><entry> −5.250000</entry><entry>‘cafl_vuv’</entry></row><row><entry>10:</entry><entry> 471.74620</entry><entry>−10.153919</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>11:</entry><entry> 245.63551</entry><entry> 10.153919 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 0.060091</entry></row><row><entry /><entry>A :0.624853E − 09 B :0.113020E − 13 C :−.515404E − 18 D :0.170604E − 21</entry></row><row><entry /><entry>E :−.159226E − 25 F :0.105279E − 29</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>12:</entry><entry> 471.74620</entry><entry>  5.250000</entry><entry>‘cafl_vuv’</entry></row><row><entry>13:</entry><entry> 199.92931</entry><entry> 18.801014</entry></row><row><entry>14:</entry><entry>1202.79595</entry><entry>  5.250000</entry><entry>‘cafl_vuv’</entry></row><row><entry>15:</entry><entry> 235.67059</entry><entry> 298.515259</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>16:</entry><entry> 490.36196</entry><entry>−227.868676 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 0.133019</entry></row><row><entry /><entry>A :−.401120E − 08 B :−.925737E − 13 C :−.236166E − 17 D :0.108790E − 21</entry></row><row><entry /><entry>B :−.551175E − 26 F :0.127289E − 30</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>17:</entry><entry> 611.66355</entry><entry> 331.489215 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : −0.837736</entry></row><row><entry /><entry>A :0.918739E − 11 B :−.476080E − 14 C :0.346155E − 19 D :−.225369E − 23</entry></row><row><entry /><entry>E :0.307373E − 28 F :−.248704E − 33</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>18:</entry><entry>INFINITY</entry><entry> 126.863525</entry></row><row><entry>19:</entry><entry>−561.20466</entry><entry>−126.090855 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 2.976905</entry></row><row><entry /><entry>A :−.154058E − 09 B :0.12575413 − 13 C :0.64783513 − 19 D :0.68438013 − 23</entry></row><row><entry /><entry>E :−.112193E − 27 F :0.122096E − 32</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>20:</entry><entry>−278.57130</entry><entry>126.090855 REFL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 8.694109</entry></row><row><entry /><entry>A :−.172648E − 07 B: 0.129115E − 12 C: −.101751E − 15 D :0.402887E − 19</entry></row><row><entry /><entry>E :−.610026E − 23 F :0.531569E − 27</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>21:</entry><entry>INFINITY</entry><entry>−226.338582</entry><entry /></row><row><entry>22:</entry><entry>INFINITY</entry><entry> 226.338582</entry></row><row><entry>23:</entry><entry>INFINITY</entry><entry> 52.284606</entry></row><row><entry>24:</entry><entry>729.88242</entry><entry> 21.000000</entry><entry>‘cafl_vuv’</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : −31.969685</entry></row><row><entry /><entry>A :0.000000E + 00 B :0.562441E − 11 C :0.152848E − 16 D :−.915976E − 20</entry></row><row><entry /><entry>E :0.259148E − 24 F :0.238241E − 28</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>25:</entry><entry> 158.15364</entry><entry>17.296741</entry><entry /></row><row><entry>26:</entry><entry>1355.83270</entry><entry>24.560562</entry><entry>‘cafl_vuv’</entry></row><row><entry>27:</entry><entry>−210.48464</entry><entry> 0.700000</entry></row><row><entry>28:</entry><entry> 376.45149</entry><entry>23.959662</entry><entry>‘cafl_vuv’</entry></row><row><entry>29:</entry><entry>−356.27423</entry><entry>15.713419</entry></row><row><entry>30:</entry><entry>−132.60708</entry><entry>38.500000</entry><entry>‘cafl_vuv’</entry></row><row><entry>31:</entry><entry>−152.06343</entry><entry> 0.700000</entry></row><row><entry>STO:</entry><entry>INFINITY</entry><entry>12.628192</entry><entry /></row><row><entry>33:</entry><entry>−273.21370</entry><entry>38.500000</entry><entry>‘cafl_vuv’</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 5.588882</entry></row><row><entry /><entry>A :0.000000E + 00 B :0.113851E − 11 C :0.272852E − 16 D :0.288236E − 20</entry></row><row><entry /><entry>B :0.101289E − 24 F :0.171576E − 28</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>34:</entry><entry> −276.08617</entry><entry> 0.700000</entry><entry /></row><row><entry>35:</entry><entry>  240.81764</entry><entry>38.500000</entry><entry>‘cafl_vuv’</entry></row><row><entry>36:</entry><entry>−48844.10806</entry><entry>11.186318</entry></row><row><entry>37:</entry><entry>  164.33601</entry><entry>38.500000</entry><entry>‘cafl_vuv’</entry></row><row><entry>38:</entry><entry> −2168.86405</entry><entry> 2.528995</entry></row><row><entry>39:</entry><entry>  157.43497</entry><entry>38.500000</entry><entry>‘cafl_vuv’</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : −1.250301</entry></row><row><entry /><entry>A :0.000000E + 00 B :−.532791E − 11 C :−.258778E − 15 D :−.139880E − 19</entry></row><row><entry /><entry>E :0.252524E − 23 F :−.138502E − 28</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>40:</entry><entry>29770.37524</entry><entry> 2.727081</entry><entry /></row><row><entry>41:</entry><entry> 130.31599</entry><entry>33.479292</entry><entry>‘cafl_vuv’</entry></row><row><entry>42:</entry><entry>  84.66735</entry><entry> 3.097821</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ASP:</entry></row><row><entry /><entry>K : 0.179565</entry></row><row><entry /><entry>A :0.000000E + 00 B :0.129145E − 11 C :−.283430E − 14 D :−.650118E − 17</entry></row><row><entry /><entry>E :0.238362E − 20</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="42PT" align="left" /><colspec colname="4" colwidth="147PT" align="left" /><tbody valign="top"><row><entry>43:</entry><entry>108.48722</entry><entry>20.284450</entry><entry>‘cafl_vuv’</entry></row><row><entry>44:</entry><entry>INFINITY</entry><entry> 8.741020</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="49PT" align="left" /><colspec colname="3" colwidth="189PT" align="left" /><tbody valign="top"><row><entry>IMG:</entry><entry>INFINITY</entry><entry> 0.000000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="266PT" align="left" /><tbody valign="top"><row><entry>SPECIFICATION DATA</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="7"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="28PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="35PT" align="left" /><colspec colname="5" colwidth="35PT" align="left" /><colspec colname="6" colwidth="84PT" align="left" /><tbody valign="top"><row><entry /><entry>NAO</entry><entry> 0.15000</entry><entry /><entry /><entry /><entry /></row><row><entry /><entry>TEL</entry></row><row><entry /><entry>DIM</entry><entry>MM</entry></row><row><entry /><entry>WL</entry><entry>157.63</entry><entry>157.63</entry><entry>157.63</entry></row><row><entry /><entry>REF</entry><entry> 2</entry></row><row><entry /><entry>WTW</entry><entry> 1</entry><entry>1 </entry><entry>1</entry></row><row><entry /><entry>XOB</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry></row><row><entry /><entry>YOB</entry><entry> 66.50000</entry><entry> 75.25000</entry><entry> 84.00000</entry><entry> 92.75000</entry><entry>101.50000</entry></row><row><entry /><entry>WTF</entry><entry> 1.00000</entry><entry> 1.00000</entry><entry> 1.00000</entry><entry> 1.00000</entry><entry> 1.00000</entry></row><row><entry /><entry>VUY</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry></row><row><entry /><entry>VLY</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="266PT" align="left" /><tbody valign="top"><row><entry>REFRACTIVE INDICES</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="98PT" align="left" /><colspec colname="2" colwidth="154PT" align="left" /><tbody valign="top"><row><entry /><entry>GLASS CODE</entry><entry>157.63</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="63PT" align="left" /><colspec colname="2" colwidth="189PT" align="left" /><tbody valign="top"><row><entry /><entry>‘cafl_vuv’</entry><entry>1.559288</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="266PT" align="left" /><tbody valign="top"><row><entry>No solves defined in system</entry></row><row><entry>INFINITE CONJUGATES</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="217PT" align="left" /><tbody valign="top"><row><entry /><entry>EFL</entry><entry>−21643.8522</entry></row><row><entry /><entry>BFL</entry><entry> −4320.0292</entry></row><row><entry /><entry>FFL</entry><entry>0.1082E + 06</entry></row><row><entry /><entry>FNO</entry><entry>   0.0000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="266PT" align="left" /><tbody valign="top"><row><entry>AT USED CONJUGATES</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="217PT" align="left" /><tbody valign="top"><row><entry /><entry>RED</entry><entry> −0.2000</entry></row><row><entry /><entry>FNO</entry><entry> −0.6667</entry></row><row><entry /><entry>OBJ DIS</entry><entry> 28.0000</entry></row><row><entry /><entry>TT</entry><entry>1064.0000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="21PT" align="left" /><colspec colname="1" colwidth="42PT" align="left" /><colspec colname="2" colwidth="203PT" align="left" /><tbody valign="top"><row><entry /><entry>IMG DIS</entry><entry>  8.7410</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="217PT" align="left" /><tbody valign="top"><row><entry /><entry>OAL</entry><entry> 1027.2590</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>PARAXIAL IMAGE</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="21PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="210PT" align="left" /><tbody valign="top"><row><entry /><entry>HT</entry><entry>20.3000</entry></row><row><entry /><entry>THI</entry><entry> 8.7412</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="42PT" align="left" /><colspec colname="2" colwidth="210PT" align="left" /><tbody valign="top"><row><entry /><entry>ANG</entry><entry> 0.0000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>ENTRANCE PUPIL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="21PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="210PT" align="left" /><tbody valign="top"><row><entry /><entry>DIA</entry><entry>0.3034E + 10</entry></row><row><entry /><entry>THI</entry><entry>0.1000E + 11</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>EXIT PUPIL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="21PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="210PT" align="left" /><tbody valign="top"><row><entry /><entry>DIA</entry><entry> 6567.5310</entry></row><row><entry /><entry>THI</entry><entry>−4320.0760</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="266PT" align="left" /><tbody valign="top"><row><entry>SPECIFICATION DATA</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="217PT" align="left" /><tbody valign="top"><row><entry /><entry>NAO</entry><entry> 0.15000</entry></row><row><entry /><entry>TEL</entry></row><row><entry /><entry>DIM</entry><entry>MM</entry></row><row><entry /><entry>WL</entry><entry> 157.63</entry></row><row><entry /><entry>REF</entry><entry> 1</entry></row><row><entry /><entry>WTW</entry><entry>  1</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="7"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="28PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="35PT" align="left" /><colspec colname="5" colwidth="35PT" align="left" /><colspec colname="6" colwidth="84PT" align="left" /><tbody valign="top"><row><entry /><entry>XOB</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="133PT" align="left" /><tbody valign="top"><row><entry /><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="7"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="28PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="35PT" align="left" /><colspec colname="5" colwidth="35PT" align="left" /><colspec colname="6" colwidth="84PT" align="left" /><tbody valign="top"><row><entry /><entry>YOB</entry><entry>100.00000</entry><entry>107.50000</entry><entry>115.00000</entry><entry>122.50000</entry><entry>130.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="133PT" align="left" /><tbody valign="top"><row><entry /><entry>105.00000</entry><entry>110.00000</entry><entry>120.00000</entry><entry>125.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="7"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="28PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="35PT" align="left" /><colspec colname="5" colwidth="35PT" align="left" /><colspec colname="6" colwidth="84PT" align="left" /><tbody valign="top"><row><entry /><entry>WTF</entry><entry> 1.00000</entry><entry> 1.00000</entry><entry> 1.00000</entry><entry> 1.00000</entry><entry> 1.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="133PT" align="left" /><tbody valign="top"><row><entry /><entry> 1.00000</entry><entry> 1.00000</entry><entry> 1.00000</entry><entry> 1.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="7"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="28PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="35PT" align="left" /><colspec colname="5" colwidth="35PT" align="left" /><colspec colname="6" colwidth="84PT" align="left" /><tbody valign="top"><row><entry /><entry>VUY</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="133PT" align="left" /><tbody valign="top"><row><entry /><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="7"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="28PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="35PT" align="left" /><colspec colname="5" colwidth="35PT" align="left" /><colspec colname="6" colwidth="84PT" align="left" /><tbody valign="top"><row><entry /><entry>VLY</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="35PT" align="left" /><colspec colname="3" colwidth="35PT" align="left" /><colspec colname="4" colwidth="133PT" align="left" /><tbody valign="top"><row><entry /><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry><entry> 0.00000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="266PT" align="left" /><tbody valign="top"><row><entry>REFRACTIVE INDICES</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="84PT" align="left" /><colspec colname="2" colwidth="168PT" align="left" /><tbody valign="top"><row><entry /><entry>GLASS CODE</entry><entry>157.63</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="63PT" align="left" /><colspec colname="2" colwidth="189PT" align="left" /><tbody valign="top"><row><entry /><entry>‘cafl_vuv’</entry><entry>1.559288</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="266PT" align="left" /><tbody valign="top"><row><entry>No solves defined in system</entry></row><row><entry>INFINITE CONJUGATES</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="217PT" align="left" /><tbody valign="top"><row><entry /><entry>EFL</entry><entry>−521.5384</entry></row><row><entry /><entry>BFL</entry><entry> −94.3531</entry></row><row><entry /><entry>FFL</entry><entry>2582.5092</entry></row><row><entry /><entry>FNO</entry><entry>  0.0000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="266PT" align="left" /><tbody valign="top"><row><entry>AT USED CONJUGATES</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="217PT" align="left" /><tbody valign="top"><row><entry /><entry>RED</entry><entry> −0.2000</entry></row><row><entry /><entry>FNO</entry><entry> −0.6667</entry></row><row><entry /><entry>OBJ DIS</entry><entry> 25.0000</entry></row><row><entry /><entry>TT</entry><entry>1249.8815</entry></row><row><entry /><entry>IMG DIS</entry><entry>  9.9306</entry></row><row><entry /><entry>OAL</entry><entry>1214.9509</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>PARAXIAL IMAGE</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="28PT" align="left" /><colspec colname="2" colwidth="210PT" align="left" /><tbody valign="top"><row><entry /><entry>HT</entry><entry>25.0018</entry></row><row><entry /><entry>THI</entry><entry> 9.9619</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="42PT" align="left" /><colspec colname="2" colwidth="210PT" align="left" /><tbody valign="top"><row><entry /><entry>ANG</entry><entry> 0.0000</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="238PT" align="left" /><tbody valign="top"><row><entry /><entry>ENTRANCE PUPIL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="28PT" align="left" /><colspec colname="2" colwidth="210PT" align="left" /><tbody valign="top"><row><entry /><entry>DIA</entry><entry>0.3034E + 10</entry></row><row><entry /><entry>THI</entry><entry>0.1000E + 11</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="2"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="252PT" align="left" /><tbody valign="top"><row><entry /><entry>EXIT PUPIL</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="28PT" align="left" /><colspec colname="1" colwidth="28PT" align="left" /><colspec colname="2" colwidth="210PT" align="left" /><tbody valign="top"><row><entry /><entry>DIA</entry><entry>158.2520</entry></row><row><entry /><entry>THI</entry><entry>−94.3531</entry></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

[0046] The optical design description provided herein demonstrates an advantageous catadioptric projection system for DUV or VUV photolithography. While the preferred embodiment has been designed for use in an 157 nm tool, the basic concept has no wavelength limitations, either shorter or longer, providing a suitable refractive material exists. Some features of the preferred system herein are summarized below.

Configuration

[0047] The preferred optical system is catadioptric and includes two optical groups, group G<b>1</b> and group G<b>2</b>, configured such that group G<b>1</b> presents a reduced, virtual image to group G<b>2</b>. The function of group G<b>2</b> is to relay this virtual image to a real image located at the plane of the wafer. Group G<b>1</b> preferably includes an even number of at least four and preferably 4 or 6 mirrors in combination with lens elements whose primary function is to provide telecentricity at the mask and enable correction of axial chromatic aberration. In the preferred embodiment, an image of the aperture stop is located in close proximity to mirror M<b>2</b>.

[0048] Group G<b>2</b> is preferably entirely dioptric providing most of the system reduction and a corresponding high numerical aperture (in excess of 0.65, 0.70 and even 0.75) at the image. This group G<b>2</b> also makes the final image telecentric in image space. Group G<b>1</b> functions to correct high-order field aberrations, advantageously allowing a substantial relaxation of the lens elements found in group G<b>2</b>. Both group G<b>1</b> and group G<b>2</b> make use of aspheric surfaces as set forth in the Table 2. The same holds for the second preferred embodiment.

Symmetry

[0049] The preferred optical design herein is co-axial, wherein each of the optical elements is rotationally symmetric about a common centerline. The preferred system advantageously does not utilize fold mirrors, prisms, or beamsplitters to fold the opto-mechanical axis. This enables a compact configuration and eliminates substantial bulk refractive material that may be difficult to procure in a timely manner.

Parallel Scanning

[0050] The preferred optical system herein achieves mask and wafer planes that are parallel, enabling unlimited scanning in a step/scan lithographic configuration.

Correction of Chromatic Aberration

[0051] Correction of chromatic aberration is achieved preferably using a single optical material in the catadioptric configuration described herein. Lateral chromatic aberration is at least substantially self-corrected within group G<b>2</b>, using a balance of optical power on either side of a primary aperture stop located within group G<b>2</b>. Correction of axial chromatic aberration is enabled using a negative lens group E<b>2</b>/E<b>3</b> located at mirror M<b>2</b> in group G<b>1</b>, providing an axial chromatic aberration contribution that is nearly equal in magnitude and opposite in sign to the chromatic aberration generated by G<b>2</b>. This high level of axial chromatic aberration correction relaxes the need for a high spectral purity laser exposure source with linewidths on the order of 0.1 to 0.2 μm.

[0052] Some additional features of the preferred system herein are set forth below. The preferred system is an imaging system for photolithographic applications using 157 nm, 193 nm or 248 nm or other exposure radiation including first and second optical groups, or groups G<b>1</b> and G<b>2</b>. The first optical group, i.e., group G<b>1</b>, is either a catoptric or catadioptric group including preferably six mirrors. Group G<b>1</b> preferably also includes one or more lens elements, e.g., to make the chief ray telecentric at a mask plane and to correct axial chromatic aberration.

[0053] The second optical group, or Group G<b>2</b>, is a dioptric group of several lens elements for reducing and projecting an image to a wafer plane. Group G<b>2</b> is preferably a relaxed group such that optical paths of projected rays are smoothly redirected at each lens element, e.g., less than 45° and preferably less than 30°, and still more preferably less than 20°, as shown in FIG. 1. This preferred system is contradistinct form a Dyson-type system which has one reflective component performing reduction of the image. In contrast to the Dyson-type system, the preferred system has a dioptric second group (group G<b>2</b>) performing reduction, while the catoptric or catadioptric first group (group G<b>1</b>) forms a virtual image for reduction by Group G<b>2</b> and provides aberration compensation for group G<b>2</b>.

[0054] The first and second groups, or groups G<b>1</b> and G<b>2</b>, respectively, of the preferred imaging system herein enable parallel scanning and a symmetric, coaxial optical design. Stops are located preferably at or near the second mirror M<b>2</b> of Group G<b>1</b> and within Group G<b>2</b>. The first stop may be alternatively moved off of the second mirror to enhance aberration correction.

[0055] Group G<b>2</b> is preferably independently corrected for lateral color, while the refractive components of the first group compensate those of the second group far longitudinal color. Advantageously, 15 or fewer total lens elements are preferably included in the system, group G<b>2</b> preferably having 10 or fewer lens elements. For example, the system of FIG. 1 shows ten lens elements E<b>4</b>-E<b>13</b> in group G<b>2</b> and three additional lens elements in group G<b>1</b>.

[0056] The sixth or final mirror in group G<b>1</b> may be preferably a convex mirror and preferably a virtual image is formed behind the sixth mirror. Group G<b>2</b> forms a real image at the wafer plane.

[0057] When used with 157 nm exposure radiation, all of the refractive elements of the imaging system. e.g., lens elements E<b>1</b>-E<b>13</b> of the preferred system of FIG. 1, are preferably made from a VUV transparent material such as CaF2. Alternatively, such materials as BaF2, SrF2, MgF2 or LiF may be used.

[0058] While exemplary drawings and specific embodiments of the present invention have been described and illustrated, it is to be understood that the scope of the present invention is not to be limited to the particular embodiments discussed. Thus, the embodiments shall be regarded as illustrative rather than restrictive, and it should be understood that variations may be made in those embodiments by workers skilled in the arts without departing form the scope of the present invention as set forth in the claims that follow, and equivalents thereof. In addition, the features of different claims set forth below may be combined in various ways in further accordance with the present invention.