METHOD FOR MOUNTING AN OPTICAL SYSTEM

Abstract

A method includes: a) measuring individual parts K1-KN of an optical system to provide measurement data, N being greater than one; b) using the measurement data to virtualize the individual parts K1-KN and using the virtualized individual parts K1-KN to generate an actual assembly model by geometrically stringing together a plurality of the virtualized individual parts K1-KN, the actual assembly model comprising virtual actual positions of the virtualized individual parts K1-KN in a virtually assembled state; c) using the actual assembly model and a target assembly model to determine a correction measure, the target assembly model comprising virtual target positions of one or more of the virtualized individual parts K1-KN in the virtually assembled state; and d) using the correction measure, assembling the individual parts K1-KN to form the optical system.

Claims

1. A method, comprising: a) measuring individual parts K1-KN of an optical system to provide measurement data, N being greater than one; b) using the measurement data to virtualize the individual parts K1-KN and using the virtualized individual parts K1-KN to generate an actual assembly model by geometrically stringing together a plurality of the virtualized individual parts K1-KN, the actual assembly model comprising virtual actual positions of the virtualized individual parts K1-KN in a virtually assembled state; c) using the actual assembly model and a target assembly model to determine a correction measure, the target assembly model comprising virtual target positions of one or more of the virtualized individual parts K1-KN in the virtually assembled state; and d) using the correction measure, assembling the individual parts K1-KN to form the optical system.

2. The method of claim 1, further comprising: geometrically stringing together the virtualized individual parts K1-KN to generate the actual assembly model; and comparing the virtual actual position of a virtualized individual part KN and the virtual target position of the virtualized individual part KN to determine the correction measure.

3. The method of claim 1, further comprising: fixing the virtualized individual parts K1 and KN at their target positions from the target assembly model to generate the actual assembly model; geometrically stringing together the virtualized individual parts K2-KN-1 with K1 and/or KN; and determining the correction measure based on virtual actual positions of at least two virtualized individual parts K2-KN-1.

4. The method of claim 1, wherein d comprises applying the correction measure to the individual part KN-1 or to a region between the individual parts KN-1 and KN.

5. The method of claim 1, wherein d) comprises applying the correction measure to the individual part KN-1 or to a gap between the individual parts KN-1 and KN.

6. The method of claim 1, wherein at least one of the following holds: the individual part KN comprises an optical element; and the individual part KN-1 comprises a member selected from the group consisting of a mechanical component, a mechatronic component and a bearing.

7. The method of claim 1, wherein at least one of the following holds: the individual part KN comprises a member selected from the group consisting of a mirror, a lens element, an optical grating, a waveplate, a stop and a sensor; and the individual part KN-1 comprises a member selected from the group consisting of a mechanical component, a mechatronic component and a bearing.

8. The method of claim 1, wherein determining the correction measure comprises: inserting a spacer between two of the individual parts K1-KN; and adjusting a play of a fastening mechanism which fastens two of the individual parts K1-KN to one another, and/or adjusting an operating point of a mechatronic component as constituent part of one of the individual parts K1-KN.

9. The method of claim 8, wherein the mechatronic component comprises an actuator, and determining the correction measure is determined based on an available actuator travel of the actuator.

10. The method of claim 1, wherein N>5 or 10.

11. The method of claim 1, wherein c) comprises determining a gap between two of the individual parts K1-KN, and d) comprises inserting a spacer into the gap.

12. The method of claim 1, wherein the correction measure relates to at least a first degree of freedom and a second degree of freedom which is different from the first degree of freedom.

13. The method of claim 12, wherein d) comprises applying the correction measure to: to a first individual part K1-KN; between a first pair of individual parts K1-KN for the first degree of freedom and a second of the individual parts K1-KN; or between a second pair of individual parts K1-KN for the second degree of freedom.

14. The method of claim 1, further comprising: measuring the assembled optical system to provide assembly measurement data; comparing the assembly measurement data and the target assembly model to determine a further correction measure; and based on the further correction measure, aligning one or more of the individual parts K1-KN.

15. The method of claim 1, further comprising, after assembling the optical system, operating the optical system.

16. The method of claim 15, wherein the optical system comprises a lithography apparatus.

17. The method of claim 1, wherein the optical system comprises a lithography apparatus.

18. The method of claim 17, further comprising: geometrically stringing together the virtualized individual parts K1-KN to generate the actual assembly model; and comparing the virtual actual position of the virtualized individual part KN and the virtual target position of the virtualized individual part KN to determine the correction measure.

19. One or more machine-readable hardware storage devices comprising instructions that are executable by one or more processing devices to perform operations comprising the method of claim 1.

20. A system, comprising: one or more processing devices; and one or more machine-readable hardware storage devices comprising instructions that are executable by the one or more processing devices to perform operations comprising the method of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0080] In the text that follows, the disclosure will be explained in more detail on the basis of embodiments with reference to the accompanying figures, in which:

[0081] FIG. 1A shows a schematic view of an embodiment of an EUV lithography apparatus;

[0082] FIG. 1B shows a schematic view of an embodiment of a DUV lithography apparatus;

[0083] FIG. 2 shows a data processing apparatus for use in a method for assembling and for operating an optical system;

[0084] FIG. 3 shows an embodiment of a contact assembly model;

[0085] FIG. 4 shows an embodiment of a target point assembly model;

[0086] FIG. 5 shows the insertion of spacers for correcting different degrees of freedom in an optical system in one embodiment;

[0087] FIG. 6 shows an exemplary displacement and rotation of individual parts using homogenous coordinates; and

[0088] FIG. 7 shows a flowchart of a method for assembling and optionally operating an optical system according to one embodiment.

DETAILED DESCRIPTION

[0089] Unless indicated to the contrary, elements that are the same or functionally the same have been provided with the same reference signs in the figures. It should also be noted that the illustrations in the figures are not necessarily true to scale.

[0090] FIG. 1A shows a schematic view of an EUV lithography apparatus 100A comprising a beam-shaping and illumination system 102 and a projection system 104. In this case, EUV stands for “extreme ultraviolet” and denotes a wavelength of the working light of between 0.1 nm and 30 nm. The beam-shaping and illumination system 102 and the projection system 104 are respectively provided in a vacuum housing (not shown), wherein each vacuum housing is evacuated with the aid of an evacuation apparatus (not shown). The vacuum housings are surrounded by a machine room (not shown), in which drive apparatuses for mechanically moving or setting optical elements are provided. Furthermore, electrical controllers and the like may also be provided in the machine room.

[0091] The EUV lithography apparatus 100A has an EUV light source 106A. A plasma source (or a synchrotron), which emits radiation 108A in the EUV range (extreme ultraviolet range), that is to say for example in the wavelength range of 5 nm to 20 nm, can for example be provided as the EUV light source 106A. In the beam-shaping and illumination system 102, the EUV radiation 108A is focused and the desired operating wavelength is filtered out from the EUV radiation 108A. The EUV radiation 108A generated by the EUV light source 106A has a relatively low transmissivity through air, for which reason the beam-guiding spaces in the beam-shaping and illumination system 102 and in the projection system 104 are evacuated.

[0092] The beam-shaping and illumination system 102 illustrated in FIG. 1A has five mirrors 110, 112, 114, 116, 118. After passing through the beam-shaping and illumination system 102, the EUV radiation 108A is guided onto a photomask (reticle) 120. The photomask 120 is likewise embodied as a reflective optical element and can be arranged outside the systems 102, 104. Furthermore, the EUV radiation 108A may be directed onto the photomask 120 via a mirror 122. The photomask 120 has a structure which is imaged onto a wafer 124 or the like in a reduced fashion via the projection system 104.

[0093] The projection system 104 (also referred to as a projection lens) has six mirrors M1 to M6 for imaging the photomask 120 onto the wafer 124. In this case, individual mirrors M1 to M6 of the projection system 104 may be arranged symmetrically in relation to an optical axis 126 of the projection system 104. It should be noted that the number of mirrors M1 to M6 of the EUV lithography apparatus 100A is not restricted to the number shown. A greater or lesser number of mirrors M1 to M6 may also be provided. Furthermore, the mirrors M1 to M6 are generally curved on their front sides for beam shaping.

[0094] FIG. 1B shows a schematic view of a DUV lithography apparatus 100B, which comprises a beam-shaping and illumination system 102 and a projection system 104. In this case, DUV stands for “deep ultraviolet” and denotes a wavelength of the working light of between 30 nm and 250 nm. As has already been described with reference to FIG. 1A, the beam-shaping and illumination system 102 and the projection system 104 may be arranged in a vacuum housing and/or be surrounded by a machine room with corresponding drive apparatuses.

[0095] The DUV lithography apparatus 100B has a DUV light source 106B. By way of example, an ArF excimer laser that emits radiation 108B in the DUV range at 193 nm, for example, can be provided as the DUV light source 106B.

[0096] The beam-shaping and illumination system 102 illustrated in FIG. 1B guides the DUV radiation 108B onto a photomask 120. The photomask 120 is formed as a transmissive optical element and may be arranged outside the systems 102, 104. The photomask 120 has a structure which is imaged onto a wafer 124 or the like in a reduced fashion via the projection system 104.

[0097] The projection system 104 has a plurality of lens elements 128 and/or mirrors 130 for imaging the photomask 120 onto the wafer 124. In this case, individual lens elements 128 and/or mirrors 130 of the projection system 104 may be arranged symmetrically in relation to an optical axis 126 of the projection system 104. It should be noted that the number of lens elements 128 and mirrors 130 of the DUV lithography apparatus 100B is not restricted to the number shown. A greater or lesser number of lens elements 128 and/or mirrors 130 can also be provided. Furthermore, the mirrors 130 are generally curved on their front sides for beam shaping.

[0098] An air gap between the last lens element 128 and the wafer 124 can be replaced by a liquid medium 132 having a refractive index>1. The liquid medium 132 may be for example high-purity water. Such a structure is also referred to as immersion lithography and has an increased photolithographic resolution. The medium 132 can also be referred to as an immersion liquid.

[0099] FIG. 2 shows a data processing apparatus 200 for use in a method for assembling and operating a projection system or projection lens 104 (for example according to FIG. 1A or 1B) or any other optical system. A flowchart for the method is shown in FIG. 7.

[0100] The data processing apparatus 200 is for example in the form of a computer device including a microprocessor and associated memory, for instance RAM, ROM, etc. The data processing apparatus 200 comprises a virtualization unit 202 and a determination unit 204. The units 202, 204 can be implemented in terms of hardware and/or software, i.e., in the form of program code.

[0101] Mechanical measurement data MEM and optional optical measurement data OEM are provided for the virtualization unit 202. Additionally, it may also be provided with further measurement data, for instance thermal measurement data.

[0102] The mechanical measurement data describe at least the geometry of a respective individual part K1 to KN. The individual parts K1 to KN are shown in exemplary fashion in a not yet assembled state in FIG. 2 and are assembled to form the projection lens 104 (see FIGS. 1A, 1B, 3 and 4) in an assembly step that will still be described in more detail below. The individual parts K1 to KN can be single parts or assemblies (composed of a plurality of respective single parts that have been interconnected).

[0103] The optical measurement data OEM describe optical properties of one or more of the individual parts K1 to KN. The following should be mentioned here as examples: a relative position of the optical axis or optical face, an (optionally spatially resolved) reflectivity, an (optionally also spatially resolved) transmission.

[0104] The mechanical measurement data MEM may have been acquired (S700 in FIG. 7) and provided, for example, by a measuring device 206, for instance a coordinate measuring machine (CMM), the latter (in actual fact) mechanically measuring the individual parts K1 to KN to this end. The optical measurement data OEM may likewise have been acquired (step S702) and provided by a measuring device 208, for instance an interferometer, the latter (in actual fact) optically measuring the individual parts K1 to KN.

[0105] The virtualization unit 202 generates virtualized individual parts K1-KN (S704 in FIG. 7) from the provided measurement data MEM, OEM. This should be understood to mean a mathematical, for example geometric description of the (real) individual parts K1-KN, for example in the form of matrices, which is stored in a data memory.

[0106] Furthermore, construction data ABD are provided for the virtualization unit 202. The construction data ABD describe at least geometric and possibly mechanical connections, interfaces and contact faces between the virtualized individual parts K1 to KN in the yet to be created virtual actual assembly model IMM. In this case, the geometric connections or geometric interfaces reproduce real connections or interfaces, for example a fastening mechanism between the individual parts K1-KN to be assembled.

[0107] The construction data ABD may be provided from a CAD (computer aided design) program and/or from an optics design program (S706 in FIG. 7). By way of example, this software may be operated on a computer device 210.

[0108] The virtualization unit 202 generates a (virtual) actual assembly model IMM (S708 in FIG. 7) from the virtualized individual parts K1 to KN and the construction data ABD. The individual parts K1 to KN are virtually assembled on one another in the actual assembly model IMM, with the relationships, for example geometric arrangement, of the individual parts K1 to KN with respect to one another being defined by the construction data ABD, for example via the contact face and interface information described therein.

[0109] The actual assembly model IMM can be generated in different ways, with the subsequently determined correction measure KOM then being geared to the corresponding model. As a matter of principle, the correction measure KOM is determined from the actual assembly model IMM and a target assembly model SMM, for example by a comparison of the two models IMM, SMM.

[0110] The target assembly model SMM describes virtual target positions of one or more of the virtualized individual parts K1-KN in the virtually assembled state. In this case, the target assembly model SMM assumes idealized individual parts K1-KN, that is to say those which for example exactly correspond to the CAD model. In this case, the idealized individual parts K1 to KN are linked, for example geometrically linked, to one another via the construction data ABD. The target assembly model SMM can likewise be provided from the CAD (computer aided design) program and/or from an optics design program, that is to say, for example, with the aid of the computer device 210. The correction measures KOM may be provided in the form of data for example to a CNC (computer numerical controlled) milling device 212. Depending on the correction measure or the appropriate data, the CNC milling device 212 mills suitable spacers 304 (see the explanations below) or other compensation elements in automated fashion.

[0111] Below, a contact assembly model is initially explained in conjunction with FIG. 3, after which a target point assembly model is described with reference to FIG. 4.

[0112] According to the contact assembly model, the virtualized individual parts K1 to KN are geometrically strung together, stacked on one another in the exemplary embodiment. In this case, a base 300 is chosen, for example for the individual part K1. The following individual parts K2 to KN are stacked on one another while taking account of the construction data ABD, that is to say K2 is placed on K1, K3 is placed on K2, . . . , KN is placed on KN-1.

[0113] By way of example, the individual part KN is chosen in such a way that it is such a component that has what is known as a functional face. This means faces critical to the function of the lithography apparatus, for example optical faces or end stops, that is to say stops that limit the maximum movement of optical elements. Therefore, the individual part KN is for example an optical element, for example a mirror, a lens element, an optical grating or a waveplate. In the exemplary embodiment, the individual part KN is a mirror with an optically effective face 302 (optical footprint).

[0114] What now arises by way of stacking the individual parts K1 to KN on one another is that the individual part KN or its functional face (optically effective face 302) is arranged at an actual position P.sub.actual. In FIG. 3, the individual part KN is depicted in this position using dashed lines.

[0115] The determination unit 204 (see FIG. 2) compares the actual position P.sub.actual with a target position P.sub.target from the target assembly model SMM. FIG. 3 shows the target position P.sub.target of the individual part KN using a solid line. In the present case there is a deviation between P.sub.actual and P.sub.target in the form of an offset or gap V in the x-direction (that is to say, for example, in the plane of the plane of maximum extent of the optically effective face 302) and z-direction, for example the vertical direction, that is to say for example perpendicular to the plane of maximum extent of the optically effective face 302. Accordingly, as a correction measure, the determination unit 204 determines the insertion of one or more spacers 304, which may be in the form of spacer mechanisms, shims, etc., for example made of metal and/or ceramics, in a step S710 (FIG. 7).

[0116] The spacers 304 can be inserted between the individual part KN and the underlying individual part KN-1. In this case, N can be greater than 5 or greater than 10. Further alternatively, the correction measure can be carried out on the individual part KN itself, for example by way of appropriate material ablation therefrom.

[0117] Further optionally, the individual part KN-1 is a mechatronic component, for example an actuator, and/or a bearing. Actuators for example can be set in such a way that they provide the correction measure. By way of example, in the case of the exemplary embodiment of FIG. 3, an actuator KN-1 can be set in view of its operating range or operating point so that it compensates the offset or gap V. However, the (maximum) available actuator travel of the actuator should be taken into account in the process. In this case (should the actuator travel be insufficient) the spacers 304 are therefore not required (although this would probably tend to be the exception). Rather, the actuator KN-1 is actuated accordingly during the operation (step S716 in FIG. 7) of the lithography apparatus (100A, 100B). In this case, steps 5712 and 5714 are optionally dispensed with, as indicated in FIG. 7 by the dashed connection line; the projection lens 104 is assembled without the application of correction measures.

[0118] By way of example, the same also applies to a bearing KN-1. By way of example, bearings may include a screwing mechanism, with the aid of which they are easily adjustable. A corresponding procedure may also be implemented in the case of a fastening mechanism, for instance a screwed connection. By way of example, a screw is tightened with less torque in order to compensate the offset or gap V. Further alternatively, a sensor can monitor or verify the correction measure.

[0119] The above-described, determined correction measures can optionally be verified in the virtual actual assembly model IMM. To this end, the actual assembly model IMM is generated again—with application of the determined correction measure—and step S710 is repeated.

[0120] Subsequently, the projection lens 104 is assembled from the individual parts K1 to KN (S712 in FIG. 7), with the determined correction measures being applied. For example, the latter are implemented during the assembly of the projection lens 104, that is to say the above-described spacers 304 are manufactured and inserted into the gap V (FIG. 3) when putting together the individual parts K1-KN. Alternatively or in addition, these are applied during the operation of, for example, the lithography apparatus 100A, 100B with the projection lens 104, for instance as explained above for the actuator. In an optional step S714, the assembled projection lens 104 is measured (in actual fact), with the determined assembly measurement data being used for determining further correction measures, for example an insertion of spacers. For example, this can be implemented by comparing the assembly measurement data with the target assembly model SMM.

[0121] Furthermore, FIG. 3 illustrates that individual or all of the individual parts K1-KN can be in the form of assemblies. By way of example, the individual parts K1 and K2 each comprise a force frame 306, to which for example one or more optical elements 308, for example mirrors or lens elements, are fastened.

[0122] The aforementioned target point assembly model is explained below on the basis of FIG. 4. Therein, the virtualized individual parts K1 and KN are fixed at their target positions P.sub.target from the target assembly model SMM. Subsequently, the individual parts K2, K3 (not depicted here), etc. are stacked on the individual part K1, and the individual parts KN-X, . . . , KN-1 (not depicted here) are stacked under the individual part KN. In this case, X is a number to be determined from the design. Hence, actual positions P.sub.actual_KN-1 (depicted using dashed lines in FIG. 4) for the individual part KN-1 and P.sub.actual_K2 for the individual part K2 arise in the exemplary embodiment. The determination unit 204 then determines the offset or gap V between the actual positions P.sub.actual_KN-1 and P.sub.actual_K2 and determines as a correction measure the insertion of the spacers 304 between the individual parts KN and KN-1 such that the offset or gap V is canceled and the individual parts KN-1 and K2 are arranged to one another in the arrangement defined by the construction data ABD. The new position of the individual part KN-1 arising as a result is depicted by a solid line in FIG. 4.

[0123] Otherwise, the features described in FIG. 3 apply accordingly to FIG. 4.

[0124] In the exemplary embodiments according to FIGS. 3 and 4, the correction measures only relate to two degrees of freedom, specifically the translational directions x and z. Naturally, the correction measure may relate to each of the six (three rotational and three translational) degrees of freedom, and may also relate to several of these degrees of freedom at the same time.

[0125] Thus, FIG. 5 for example shows the insertion of spacers 304 for the purposes of correcting a respective offset or gap V in the x-, y- and z-direction. In this case, a correction measure relating to the correction in three spatial directions on one individual part KN-1 is shown to the left. By contrast, correction measures, shown to the right, relating to different spatial directions x, z are carried out in at least two different individual parts, specifically the actuator KN-1′ (in the x-direction) and the fastening mechanism KN-2′ (in the z-direction), which fixes the actuator KN-1′ to a support KN-3′. Following the assembly of the spacers 304, the optical element KN and the actuators KN-1, KN-1′ are put together to form the projection lens 104. Then, the optical face 302 is situated at its desired target position P.sub.target.

[0126] The above-described actual assembly models IMM can be determined with the aid of homogenous coordinates and/or Euler angles, as illustrated below in FIG. 6.

[0127] The components K1, K2 (corresponds to KN-1) and K3 (corresponds to KN-1) are arranged in a manner deviating from respective target positions (also referred to as “design” or “target pose” below) on account of manufacturing tolerances.

[0128] Hence, the problem arising is that of determining the thicknesses that the positioning elements Sp1, Sp2 and Sp3 (corresponding to the spacers 304 for example) should have so that the functional face CS_F_actual is at the target position CS_F_target in relation to the base CS_B, and to be precise more accurately than the summation of the manufacturing tolerances, usually even more accurately than any individual manufacturing tolerance.

[0129] The coordinate system CS_K represents the body K (virtualization) and is defined by: CS.orig=origin, CS.ex=X-axis, CS.ey=Y-axis and CS.ez=Z-axis, where (CS_K){circumflex over ( )}B refers to the coordinates of CS_K in CS_B.

[0130] The following calculation example should illustrate this:

[0131] Target positions given in CS_B:

TABLE-US-00001 (CS_F_target){circumflex over ( )}B = [95, 200, 305] mm, Ry = −14° CS_F_target = name: ‘CS_F’  base: ‘CS_Base’  orig: [95 200 305]   ex: [ 0.9703 0 0.2419]   ey: [ 0 1 0 ]   ez: [−0.2419 0 0.9703]

[0132] 3 Spacer-reference points and effective directions:

TABLE-US-00002 Sp1 = name: ‘Spc1’ Sp2 = name: ‘Spc2’ Sp3 = name: ‘Spc3’ base: ‘CS_Base’ base: ‘CS_Base’ base: ‘CS_Base’ orig: [150 300 190] orig: [340 300 250] orig: [410 300 320] ez: [−1 0 2]/sqrt(5) ez: [−1 0 2]/sqrt(5) ez: [−1 0 0]

[0133] Let CS_K3 be measured in CS_B:

TABLE-US-00003 (CS_K3_actual){circumflex over ( )}B = [103 210 167], Ry = −17°, Rz = 182° CS_K3_actual = name: ‘CS_K3’  base: ‘CS_Base’  orig: [103 210 167]   ex: [−0.9557 −0.0298 −0.2928]   ey: [ 0.0334 −0.9994 −0.0072]   ez: [−0.2924 −0.0167 0.9562]

[0134] Let CS_F be measured in CS_K3_actual:

TABLE-US-00004 (CS_F_actual){circumflex over ( )}K3 = [−25 0 126] mm, Ry = −5°, Rz = 179° CS_F_actual_K3 = name: ‘CS_F’  base: ‘CS_K3’  orig: [−25 0 126]   ex: [−0.9960 0.0175 −0.0871]   ey: [−0.0174 −0.9998 −0.0015]   ez: [−0.0872 0 0.9962]

[0135] Calculation of the actual pose or actual position of CS_F in CS_B by way of a coordinate transformation from CS_K3 to CS_B, e.g., in homogenous coordinates:

TABLE-US-00005 (CS_F_actual){circumflex over ( )}B = K3_2_B * (CS_F_actual){circumflex over ( )}K3 K3_2_B = −0.9557 0.0334 −0.2924 103.0000 −0.0298 −0.9994 −0.0167 210.0000 −0.2928 −0.0072 0.9562 167.0000 0 0 0 1.0000

[0136] with the 4×4 transformation matrix K3_2_B

TABLE-US-00006 CS_F_actual = name: ‘CS_F’ base: ‘CS_Base’ orig: [90.0542 208.6420 294.7950]  ex: [ 0.9780 0.0137 0.2082]  ey: [−0.0163 0.9998 0.0109]  ez: [−0.2080 −0.0140 0.9780]

[0137] Offset CS_F_actual from CS_F target in CS_B coordinates (IS_abs) and CS_F target coordinates (IS_rel), and assessment of the actual pose or actual position (comparison with the specification Tol_rel):

TABLE-US-00007 Pose CS_F wrt CS_Base: [mm, mrad] Tx Ty Tz Rx Ry Rz Target: 95.000 200.000 305.000 −0.000 −244.34 −0.000 Actual: 90.054 208.642 294.795 14.344 −209.491 16.674 I-S_abs: −4.946 8.642 −10.205 14.344 34.855 16.674 I-S_rel: −7.268 8.642 −8.705 14.039 34.830 13.202 Tol_rel: 2.000 2.000 1.000 5.000 5.000 2.000

[0138] Actuator travel calculation in CS_B, where Sp.ez is the unit vector in the effective direction of the positioning element (for example, the effective direction is the thickness in which it should bring about the displacement of K3 into the target position), Sp.orig is the target position of K3 at the reference point (K3-side rest of the positioning element), and sp_actual is the actual position of K3 at the reference point:

TABLE-US-00008 sp_delta = dot(sp_is, Sp.ez) where sp_is = Sp.orig − sp_actual  = spacer point displacement from the actual to the target   Change [mm]   Sp1  5.04   Sp2 11.83   Sp3 −6.29

[0139] Although the present disclosure has been described on the basis of exemplary embodiments, it can be modified in various ways.

LIST OF REFERENCE SIGNS

[0140] 100A EUV lithography apparatus [0141] 100B DUV lithography apparatus [0142] 104 Beam-shaping and illumination system [0143] 104 Projection system [0144] 106A EUV light source [0145] 106B DUV light source [0146] 108A EUV radiation [0147] 108B DUV radiation [0148] 110 Mirror [0149] 112 Mirror [0150] 114 Mirror [0151] 116 Mirror [0152] 118 Mirror [0153] 120 Photomask [0154] 122 Mirror [0155] 124 Wafer [0156] 126 Optical axis [0157] 128 Lens element [0158] 130 Mirror [0159] 132 Medium [0160] 200 Data processing apparatus [0161] 202 Virtualization unit [0162] 204 Determination unit [0163] 206 Measuring device [0164] 208 Measuring device [0165] 210 Computer device [0166] 212 CNC milling device [0167] 300 Base [0168] 302 Optically effective face [0169] 304 Spacer [0170] 306 Force frame [0171] 308 Optical element [0172] ABD Construction data [0173] IMM Actual assembly model [0174] KOM Correction measure [0175] K1-KN Individual parts [0176] P.sub.target Target position [0177] P.sub.actualActual position [0178] P.sub.actual_KN-1 Actual position [0179] P.sub.actual_K2 Actual position [0180] MEM Mechanical measurement data [0181] M1 Mirror [0182] M2 Mirror [0183] M3 Mirror [0184] M4 Mirror [0185] M5 Mirror [0186] M6 Mirror [0187] OEM Optical measurement data [0188] SMM Target assembly model [0189] S700-S716 Method steps [0190] V Gap