Method for mounting an optical system

Abstract

The invention relates to a method for mounting an optical system (104), in particular a lithographic apparatus (100A, 100B), comprising the following steps: a) measuring (S700, S702) components K1-KN of the optical system (104) in order to provide measurement data (MEM, OEM), wherein N>1, b) virtualizing (S704) the components K1-KN with the aid of the provided measurement data (MEM, OEM) and generating (S708) an actual mounting model (IMM) based on the virtualized components K1-KN, the actual mounting model (IMM) containing virtual actual positions (P) of the virtualized components K1-KN in a virtual mounted state. actual 、P actual_KN‑1 、P actual_K2 ), c) determining (S710) a corrective measure based on the actual installation model (IMM) and the target installation model (SMM), wherein the target installation model (SMM) includes one or more virtual target positions (P target ), and d) installing (S712) the components K1-KN using the corrective measures to form the optical system (104).

Description

Technical Field

[0001] The invention relates to a method for assembling an optical system, a method for operating an optical system, a data processing device and a computer program product.

[0002] The entire content of the priority application DE 10 2019 218 925.3 is incorporated herein by reference. Background Art

[0003] Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithographic process is performed using a lithographic apparatus having an illumination system and a projection system. An image of a mask (reticle) illuminated by the illumination system is projected by the projection system onto a substrate (e.g., a silicon wafer) coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection system, thereby transferring the mask structure to the photosensitive coating of the substrate.

[0004] The construction of optical systems, such as projection systems (also called projection lenses or projection optics boxes – POBs), requires precise positioning of optical surfaces and other functional surfaces (e.g., at stops or end stops) in all six degrees of freedom, down to the micrometer range. Direct measurement of the position of the functional surfaces in the installed state is often not possible in this process.

[0005] A further difficulty arises from the fact that the required mounting accuracy of the functional surfaces is significantly lower than the manufacturing accuracy of the components or individual parts, or that a great deal of effort is required to manufacture the functional surfaces in relation to the contact bodies and the reference surfaces very accurately. It is therefore common practice to insert adjustable spacers at the interfaces of the individual parts, for example at the contact surfaces or threaded connections. If the initially installed set of spacers does not achieve the required positional accuracy of the functional surfaces, this set is replaced by a new set of spacers or is individually adjusted, in particular ground or polished. Typically, the six degrees of freedom are adjusted in sequence, resulting in a plurality of adjustment loops. The additional adjustment loops result from the fact that the effective directions of the spacers are generally not orthogonal to one another, i.e. not decoupled from one another. This increases the time required for manufacturing the optical system and thus increases the costs. This applies in particular if the spacers have to be adjusted individually, i.e. have to be manufactured to predetermined dimensions. Summary of the Invention

[0006] Against this background, it was an object of the present invention to provide an improved method.

[0007] Therefore, a first aspect proposes a method for assembling an optical system, in particular a lithographic apparatus, comprising the following steps:

[0008] a) measuring individual parts K1–KN of the optical system to provide measurement data, where N>1,

[0009] b) virtualizing the individual parts K1 - KN with the aid of the provided measurement data and generating a real assembly model based on the virtualized individual parts K1 - KN, which contains the virtual real positions of the virtualized individual parts K1 - KN in the virtual assembled state,

[0010] c) determining a corrective measure based on the actual assembly model and a target assembly model, the target assembly model comprising one or more virtual target positions of the virtualized individual parts K1–KN in a virtual assembly state, and

[0011] d) Assembling the individual parts K1–KN using the corrective measures to form the optical system.

[0012] The adjustment loop described at the outset is thus largely avoided. Furthermore, corrections can be made at only one or a few locations, which then result in the desired target position of the functional surface (on one of the individual parts K1-KN). Consequently, it is not necessary to manufacture all individual parts with high precision. Furthermore, this allows for highly accurate adjustment of the relative positions of functional surfaces that are no longer accessible to the metering element after assembly. In particular, this allows for greater tolerances in the components or individual parts involved, as well as in the assembly process, thereby reducing both development costs (e.g., development of precision tools) and manufacturing costs (throughput time, defective products, and individual part costs).

[0013] The optical system may be a lithographic apparatus or a part thereof, such as an illumination system or a projection system.

[0014] The measurement according to step a) may comprise measurement of in particular mechanical properties (in particular dimensions, sizes, tolerances, etc.), optical properties (reflectivity, etc.) and / or thermal properties of the individual parts. In particular, the measurement may be carried out mechanically or optically.

[0015] In this context, “data” refers to electronic data.

[0016] “Virtualizing the individual parts K1–KN” means generating data describing the individual parts K1–KN. These data can describe the individual parts K1–KN by points, surfaces, coordinate systems, or three-dimensional bodies.

[0017] Generating a realistic assembly model refers to adding additional data to the electronic data describing the individual parts K1–KN. This additional data describes the relationships of the virtualized individual parts K1–KN, so that the virtual, realistic positions of the virtualized individual parts K1–KN in their virtual assembled state appear. This additional data can be construction data derived from a CAD (Computer-Aided Design) model. The CAD model can include geometric, mechanical, optical, and / or thermal properties, parameters, and / or interfaces (between the individual parts).

[0018] As an example, the actual assembly model is generated by geometrically stringing together a plurality of virtualized individual parts K1 -KN.

[0019] In an embodiment, the actual assembly model further includes, for example, the mechanical relationships between the virtualized individual parts K1 -KN, and the virtual actual positions of the virtualized individual parts K1 -KN in the virtual assembly state.

[0020] The target assembly model may contain data derived from or derived from a CAD model. The target assembly model contains at least the (ideal or desired) positions of one or more functional surfaces of one or more individual parts, but may also describe the positions of other individual parts (without functional surfaces).

[0021] As far as reference is currently made to the actual position and / or target position of one or more of the virtualized individual parts K1-KN, this means the actual target and / or target position (e.g., a tetrahedral mesh) of one or more points, surfaces and / or three-dimensional bodies of one or more virtualized individual parts K1-KN.

[0022] The determined corrective measure is preferably designed such that it acts on the geometric and / or mechanical relationship of at least two of the individual parts K1 -KN relative to one another. That is, the corrective measure influences, for example, the relative position and / or alignment of at least two individual parts.

[0023] The assembly comprises connecting the individual parts K1-KN to each other, in particular joining them, in particular in an interlocking, press-fit and / or adhesive manner. In the present example, "connection" is understood to mean an interlocking, press-fit or integrally joined connection, or a combination thereof. An interlocking connection is obtained by joining at least two connecting parts one inside the other or one behind the other. A press-fit connection, such as a threaded connection, presupposes a normal force on the surfaces to be connected to each other. A press-fit connection can be obtained by frictional engagement. As long as the reaction forces generated by static friction are not exceeded, mutual displacement of the surfaces can be prevented. A force-locked connection can also exist as a magnetically locked engagement. In a cohesive connection, the connecting parts are held together by atomic or molecular forces. A cohesive connection is a non-releasable connection that can only be separated by destroying the connecting member. A cohesive connection can be connected, for example, by adhesive bonding, soldering, welding or vulcanization.

[0024] N is an integer greater than 1.

[0025] According to one embodiment, the method comprises:

[0026] Generate the actual assembly model by geometrically stringing together the virtualized individual parts K1–KN, and

[0027] Based on the comparison between the virtual actual position of the virtualized individual part KN and the virtual target position of the virtualized individual part KN, the corrective measure in step c) is determined.

[0028] This describes a so-called virtual contact assembly. According to a variant of this virtual contact assembly, the positions in which the functional surfaces will be arranged are determined when all individual parts are mounted according to their geometric measurements. Allowances can also be included, for example to account for shape variations of the individual parts. Shape variations can be caused by different mountings and varying masses of the individual parts or assemblies. For example, when constructing a projection lens, the force frame is first installed. This is then filled with modules and, as a result, experiences load variations and, consequently, shape changes.

[0029] According to other embodiments, the method includes:

[0030] The actual assembly model is generated by fixing the virtualized individual parts K1 and KN in their target positions from the target assembly model,

[0031] geometrically concatenate the virtualized individual parts K2–KN-1 with K1 and / or KN, and

[0032] The corrective measure in step c) is determined based on the virtual actual positions of the at least two virtualized individual parts K2 -KN- 1 .

[0033] This describes the virtual target point assembly. Within the scope of the latter, the remaining gap preferably occurs directly, specifically between those (two or more) individual parts (of individual parts K2-KN), which do not contact when the process is connected together.

[0034] According to other embodiments, the corrective measure in step d) is applied to the individual portion KN- 1 or to the region between the individual portions KN- 1 and KN, in particular the gap.

[0035] Advantageously, the correction is carried out adjacent to the individual part KN, which in particular has the functional surface. As far as the individual part KN-1, the probability of tolerance errors already compensating for one another increases.

[0036] According to further embodiments, the individual parts KN comprise optical elements, in particular mirrors, lens elements, gratings and / or wave plates, stops, sensors and / or end stops.

[0037] These specify examples of individual parts KN with functional surfaces.

[0038] Alternatively, the separate part KN can be a mechanical component, an electromechanical component, in particular an actuator and / or a carrier.

[0039] According to other embodiments, the separate part KN- 1 comprises a mechanical component, an electromechanical component, in particular an actuator and / or a carrier.

[0040] Advantageously, defect correction is performed on such components, as it is easily achieved—for example, by adjusting the operating range of the actuator. In this context, "mechanical components" particularly include mechanical reference surfaces or mating elements, such as alignment pins or alignment holes. In this context, "supports" particularly include mechanical and / or magnetic supports, such as weight compensators for optical elements.

[0041] According to other embodiments, the corrective measures include: inserting a spacer, in particular between two of the separate parts K1-KN, adjusting the play of a fastening device, in particular fastening two of the separate parts K1-KN to each other, and / or adjusting the operating point of an electromechanical component, in particular an operating point of an actuator that is a component of one of the separate parts K1-KN.

[0042] According to other embodiments, the corrective measure in step c) is determined based on the available actuator travel of the actuator.

[0043] According to other embodiments, N>5 or 10.

[0044] According to other embodiments, a gap between two of the individual parts K1 -KN is determined in step c) and a spacer is inserted into the gap in step d).

[0045] The spacer is preferably a spacer element, a washer, or the like, in particular made of metal or ceramic. Alternatively or additionally, the spacer can be adjustable relative to the space defined thereby (in particular its thickness), for example, it can be provided in the form of a set screw or a wedge that can be displaced relative to one another. In an embodiment, the spacer can be removed again after assembly (that is, in particular after step d)).

[0046] According to other embodiments, the corrective measures according to step c) involve at least the first and the second degree of freedom.

[0047] According to other embodiments, in step d), the correction measure is applied between a first pair of individual parts K1 -KN for a first of the individual parts K1 -KN or a first degree of freedom and between a second pair of individual parts K1 -KN for a second of the individual parts K1 -KN or a second degree of freedom.

[0048] Since the corrective measures are divided between different individual parts, the former can be determined more easily (avoiding or reducing mutual influence of corrective measures).

[0049] According to other embodiments, the method includes:

[0050] Measuring assembled optical systems to provide assembly measurement data,

[0051] determining additional corrective measures based on a comparison between the assembly measurement data and the target assembly model, and

[0052] One or more of the individual parts K1 - KN are aligned based on the determined further corrective measures.

[0053] At this point, there is an additional correction by comparing the assembled optical system to the target assembly model.

[0054] According to other embodiments, the actual assembly model is determined with the aid of analytical geometry, in particular homogeneous coordinates and / or Euler angles.

[0055] This is particularly easy to implement on computer devices such as microprocessors.

[0056] A second aspect proposes a method for operating an optical system, in particular a lithographic apparatus, comprising the following steps:

[0057] a) measuring individual parts K1–KN of the optical system to provide measurement data, where N>1,

[0058] b) virtualizing the individual parts K1 - KN with the aid of the provided measurement data and generating a real assembly model based on the virtualized individual parts K1 - KN, the real assembly model containing the virtual real positions of the virtualized individual parts K1 - KN in the virtual assembled state,

[0059] c) determining corrective measures based on the actual assembly model and a target assembly model, the target assembly model comprising virtual target positions of one or more of the virtualized individual parts K1-KN in a virtual assembled state, and

[0060] d) Assembling the individual parts K1–KN using the corrective measures to form the optical system and operating the optical system.

[0061] Operating an optical system means using it for its intended purpose. In particular, operating an optical system means using it to carry out an exposure process, such as exposing a wafer for manufacturing microchips. Advantageously, manufacturing defects (tolerances) are corrected, in particular by appropriate adjustments to the optical system's controller. For example, the travel or operating point of an actuator during operation can be provided to achieve this correction.

[0062] The method according to the second aspect can be combined with the method of the first aspect so that the corrective measures initially determined during assembly and during operation are then applied during assembly or during operation. Thus, according to a third aspect, the following is provided:

[0063] A method for assembling and / or operating an optical system, in particular a lithographic apparatus, comprising the following steps:

[0064] a) measuring individual parts K1–KN of the optical system to provide measurement data, where N>1,

[0065] b) virtualizing the individual parts K1 - KN with the aid of the provided measurement data and generating a real assembly model based on the virtualized individual parts K1 - KN, the real assembly model containing the virtual real positions of the virtualized individual parts K1 - KN in the virtual assembled state,

[0066] c) determining a corrective measure based on the actual assembly model and a target assembly model, the target assembly model comprising one or more virtual target positions of the virtualized individual parts K1–KN in a virtual assembly state, and

[0067] d) Assembling the individual parts K1–KN to form an optical system using the corrective measures and / or operating the optical system using the corrective measures.

[0068] A fourth aspect provides a data processing device, the data processing device comprising:

[0069] a virtualization unit for virtualizing the individual parts K1-KN of the optical system with the aid of the provided measurement data and generating a real assembly model based on the virtualized individual parts K1-KN, the real assembly model containing the virtual real positions of the virtualized individual parts K1-KN in the virtual assembly state, and

[0070] A determination unit is configured to determine a correction measure for application during assembly of the optical system from the individual parts K1-KN or during operation of the optical system assembled from the individual parts K1-KN based on the actual assembly model and a target assembly model, the target assembly model containing virtual target positions of one or more virtualized individual parts K1-KN in a virtual assembled state.

[0071] The corresponding means or units, such as a measuring device, a computer device, a virtualization unit, or a determination unit, can be implemented in hardware and / or software. In the case of a hardware-based embodiment, the corresponding unit can be implemented as a device or a component of a device, such as a computer or a microprocessor. In the case of a software-based embodiment, the corresponding means or units can be implemented as a computer program product, a function, a routine, a part of a program code, or an executable object.

[0072] A fifth aspect provides a computer program product, which enables at least one program-controlled device to implement the following steps:

[0073] virtualizing the individual parts K1-KN of the optical system with the aid of the provided measurement data and generating a real assembly model from the virtualized individual parts K1-KN, the real assembly model containing the virtual real positions of the virtualized individual parts K1-KN in the virtual assembly state, and

[0074] Corrective measures are determined based on the actual assembly model and a target assembly model, which is used to apply during assembly of the optical system from the individual parts K1-KN or during operation of the optical system assembled from the individual parts K1-KN, the target assembly model containing virtual target positions of one or more virtualized individual parts K1-KN in a virtual assembly state.

[0075] The computer program product, e.g., a computer program component, can be provided or supplied as, for example, a storage medium, such as a memory card, a USB memory stick, a CD-ROM, a DVD, or in the form of a file that can be downloaded from a server in a network. As an example, in a wireless communication network, this can be achieved by transmitting a suitable file with the computer program product.

[0076] In the present case, "a" or "an" should not necessarily be understood as limiting to exactly one element. Of course, multiple elements can also be provided, for example, two, three, or more. Any other numerical values ​​used herein should not be understood as limiting to the precisely stated number of elements. On the contrary, upward and downward numerical deviations are possible unless otherwise indicated. Labeling method steps with "a", "b"), etc. should not be interpreted as limiting to a specific order. Steps can also be relabeled, for example, step b) becoming step f), in particular to insert preceding or subsequent steps or intermediate steps.

[0077] The embodiments and features described for the method according to the first aspect apply correspondingly to the methods, data processing devices and computer program products proposed according to the second and third aspects, and vice versa.

[0078] Other possible implementations of the present invention also include the combination not clearly mentioned above or below about any feature or embodiment described in relation to the exemplary embodiment. In this case, those skilled in the art will also add various aspects as improvements or supplements to the corresponding basic form of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Further advantageous developments and aspects of the invention are the subject matter of the dependent claims and are also the subject matter of the exemplary embodiments of the invention described below.In the following, the invention will be explained in more detail based on preferred embodiments with reference to the accompanying drawings.

[0080] Figure 1A shows a schematic view of an embodiment of an EUV lithography apparatus;

[0081] Figure 1B shows a schematic view of an embodiment of a DUV lithography apparatus;

[0082] Figure 2 A data processing apparatus is shown for use in a method of assembling and operating an optical system;

[0083] Figure 3 An embodiment of a contact assembly model is shown;

[0084] Figure 4 An embodiment of a target point assembly model is shown;

[0085] Figure 5 shows a spacer inserted in one embodiment to correct for different degrees of freedom in an optical system;

[0086] Figure 6 shows exemplary displacements and rotations of individual parts using homogeneous coordinates; and

[0087] Figure 7 A flow chart of a method for assembling and optionally operating an optical system according to one embodiment is shown. DETAILED DESCRIPTION

[0088] Unless otherwise indicated, identical or functionally identical elements are provided with the same reference numerals in the figures. It should also be noted that the illustrations in the figures are not necessarily to scale.

[0089] Figure 1A A schematic diagram of an EUV lithography apparatus 100A is shown, comprising a beam shaping and illumination system 102 and a projection system 104. In this context, EUV stands for "extreme ultraviolet" and refers to a wavelength of operating light between 0.1 and 30 nm. The beam shaping and illumination system 102 and the projection system 104 are each housed in a vacuum housing (not shown), each of which is evacuated by means of an exhaust device (not shown). The vacuum housing is surrounded by a mechanical chamber (not shown), in which drive devices for mechanically moving or setting optical elements are provided. Furthermore, an electrical controller and the like may also be provided in the mechanical chamber.

[0090] The EUV lithography apparatus 100A includes an EUV light source 106A. For example, a plasma source (or a synchrotron) can be provided as the EUV light source 106A, which emits radiation 108A in the EUV range (extreme ultraviolet range), that is, for example, in the wavelength range of 5 nm to 20 nm. In the beam shaping and illumination system 102, the EUV radiation 108A is focused and the desired operating wavelength is filtered out of the EUV radiation 108A. The EUV radiation 108A generated by the EUV light source 106A has a relatively low transmittance through air, so the beam guiding space in the beam shaping and illumination system 102 and in the projection system is evacuated.

[0091] Figure 1A The beam shaping and illumination system 102 shown in FIG. 1 has five mirrors 110, 112, 114, 116, and 118. After passing through the beam shaping and illumination system 102, the EUV radiation 108A is directed onto a photomask (reticle) 120. The photomask 120 is also implemented as a reflective optical element and can be arranged outside the systems 102 and 104. Furthermore, the EUV radiation 108A can be directed onto the photomask 120 by means of a mirror 122. The photomask 120 has a structure that is imaged in a reduced manner onto a wafer 124 or the like by the projection system 104.

[0092] The projection system 104 (also referred to as a projection lens) has six mirrors M1 to M6 for imaging the photomask 120 onto a wafer 124. In this case, the individual mirrors M1 to M6 of the projection system 104 can be arranged symmetrically about the 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 limited to the number shown. A greater or lesser number of mirrors M1 to M6 can also be provided. In addition, the mirrors M1 to M6 are typically curved on their front sides for beam shaping.

[0093] Figure 1B A schematic view of a DUV lithography apparatus 100B is shown, comprising a beam shaping and illumination system 102 and a projection system 104. In this case, DUV stands for "deep ultraviolet" and refers to a wavelength of working light between 30 nm and 250 nm. Figure 1A As already described, the beam shaping and illumination system 102 and the projection system 104 may be arranged in a vacuum housing and / or surrounded by a mechanical room with corresponding drive devices.

[0094] The DUV lithography apparatus 100B has a DUV light source 106B. As an example, an ArF excimer laser emitting radiation 108B in the DUV range of 193 nm may be provided as the DUV light source 106B.

[0095] exist Figure 1B The beam shaping and illumination system 102 shown in FIG directs DUV radiation 108B onto a photomask 120. The photomask 120 is formed as a transmissive optical element and may be arranged external to the systems 102, 104. The photomask 120 has a structure that is imaged in a reduced manner by the projection system 104 onto a wafer 124 or the like.

[0096] 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, the individual lens elements 128 and / or mirrors 130 of the projection system 104 can be arranged symmetrically about the 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 limited to the number shown. A greater or lesser number of lens elements 128 and / or mirrors 130 can also be provided. In addition, the mirrors 130 are typically curved on their front sides for beam shaping.

[0097] The air gap between the last lens element 128 and the wafer 124 can be replaced by a liquid medium 132 having a refractive index greater than 1. Liquid medium 132 can be, for example, high-purity water. Such a configuration is also known as immersion lithography and has enhanced lithographic resolution. Medium 132 can also be referred to as an immersion liquid.

[0098] Figure 2 104 (particularly according to the Figure 1A or 1B) or any other optical system in a data processing device 200. The flowchart of the method is in Figure 7 Shown.

[0099] The data processing device 200 is, for example, in the form of a computer device comprising a microprocessor and associated memory components, such as RAM, ROM, etc. The data processing device 200 comprises a virtualization unit 202 and a determination unit 204. The units 202, 204 can be implemented in hardware and / or software, i.e. in the form of program code.

[0100] Mechanical measurement data MEM and optionally optical measurement data OEM are provided to the virtualization unit 202. Furthermore, it can also be provided with other measurement data, such as thermal measurement data.

[0101] The mechanical measurement data describe at least the geometry of the individual parts K1 to KN. Figure 2 104 is shown in an exemplary manner in an unassembled state and is assembled in an assembly step which will be described in more detail below to form the projection lens 104 (see Figure 1A 、 1B, 3 and 4). The individual parts K1 to KN may be single parts or assemblies (composed of a plurality of corresponding single parts that have been interconnected).

[0102] The optical measurement data OEM describe the optical properties of one or more of the individual parts K1 to KN. The following should be mentioned here as examples: relative positions of optical axes or optical surfaces, (optionally spatially resolved) reflectivity, (optionally also spatially resolved) transmittance.

[0103] The mechanical measurement data MEM may have been acquired in particular by a measuring device 206, such as a coordinate measuring machine (CMM). Figure 7 The optical measurement data OEM may also have been acquired (step S702) and provided by a measuring device 208 (e.g., an interferometer) which (in practice) optically measures the individual parts K1 to KN.

[0104] The virtualization unit 202 generates virtualized individual parts K1-KN ( Figure 7 This should be understood to mean a mathematical description, in particular a geometric description, of the (real) individual parts K1 -KN, for example in the form of a matrix, which is stored in a data memory.

[0105] Furthermore, the construction data ABD is provided to the virtualization unit 202. The construction data ABD describes at least the geometric and possibly mechanical connections, interfaces, and contact surfaces between the individual parts K1 to KN virtualized in the virtual real assembly model IMM to be created. In this case, the geometric connections or interfaces reproduce real connections or interfaces, such as fastening elements between the individual parts K1 to KN to be assembled.

[0106] Can be from a CAD (Computer Aided Design) program and / or from an optical design program ( Figure 7 S706 in ) provides construction data ABD. As an example, the software can be run on the computer device 210.

[0107] The virtualization unit 202 generates a (virtual) actual assembly model IMM ( Figure 7 In the actual assembly model IMM, the individual parts K1 to KN are virtually assembled to one another, wherein the relationships, in particular the geometrical arrangement, of the individual parts K1 to KN relative to one another are defined by the construction data ABD, in particular by the contact surfaces and interface information described therein.

[0108] The actual assembly model IMM can be generated in different ways, wherein the subsequently determined correction measures KOM are then adapted to the corresponding model. In principle, the correction measures KOM are determined from the actual assembly model IMM and the target assembly model SMM, in particular by comparing the two models IMM, SMM.

[0109] The target assembly model SMM describes the virtual target position of one or more of the virtualized individual parts K1-KN in a virtual assembly state. In this case, the target assembly model SMM assumes idealized individual parts K1-KN, that is, for example, parts that completely correspond to the CAD model. In this case, the idealized individual parts K1 to KN are associated with each other through construction data ABD, in particular geometrically associated. The target assembly model SMM can also be provided from a CAD (computer-aided design) program and / or from an optical design program, that is, for example, with the aid of a computer device 210. The correction measures KOM can be provided in the form of data, in particular to a CNC (computer numerical control) milling device 212. Depending on the correction measures or appropriate data, the CNC milling device 212 mills suitable spacers 304 (see explanation below) or other compensation elements in an automated manner.

[0110] Below, initially combined Figure 3 Explain the contact assembly model and refer to Figure 4 Describe the target point assembly model.

[0111] According to the contact assembly model, the virtualized individual parts K1 to KN are geometrically connected in series and, in the exemplary embodiment, stacked one on top of another. In this case, for example, substrate 300 is selected for individual part K1. Taking into account the construction data ABD, the following individual parts K2 to KN are stacked one on top of another: K2 is placed on K1, K3 on K2, ..., and KN on KN-1.

[0112] By way of example, the individual component KN is selected such that it is a component having a so-called functional surface. This means a surface that is crucial for the function of the lithographic apparatus, such as an optical surface or an end stop, i.e., a stop that limits the maximum movement of an optical element. Thus, the individual component KN is, in particular, an optical element, such as a mirror, a lens element, a grating, or a wave plate. In the exemplary embodiment, the individual component KN is a mirror having an optically active surface 302 (optical footprint).

[0113] By stacking the individual parts K1 to KN on top of one another, the result is that the individual part KN or its functional surface (optically active surface 302 ) is arranged at the actual position P actual At. Figure 3 In FIG, the individual parts KN are depicted using dashed lines in this position.

[0114] Determining unit 204 (see Figure 2 ) The actual position P actual and the target position P from the target assembly model SMM target Make a comparison. Figure 3 The target position P of the individual parts KN is shown using a solid line. target In this example, P actual and P target The existing deviations are in the form of offsets or gaps V in the x-direction (i.e., for example, in the plane of the maximum extent of the optically active surface 302) and in the z-direction (e.g., in the vertical direction, i.e., in particular perpendicular to the maximum extent of the optically active surface 302). Therefore, as a corrective measure, the determination unit 204 in step S710 ( Figure 7 ) is determined to insert one or more spacers 304, which can be in the form of spacer members, gaskets, etc., in particular made of metal and / or ceramic.

[0115] The spacer 304 is preferably inserted between the individual part KN and the underlying individual part KN-1. In this case, N is preferably greater than 5 or greater than 10. Alternatively, the corrective measure can be carried out on the individual part KN itself, for example by ablating appropriate material therefrom.

[0116] It is further preferred that the individual parts KN-1 are electromechanical components, in particular actuators and / or carriers. Actuators are particularly advantageous because they can be configured such that they provide corrective measures. As an example, in Figure 3 In the case of the exemplary embodiment of the present invention, the actuator KN-1 can be set in such a way that it compensates for the offset or gap V in view of its operating range or operating point. However, the (maximum) available actuator stroke of the actuator should be taken into account in this process. In this case (in the case of insufficient actuator stroke), the spacer 304 is therefore not required (but this may tend to be an exception). Instead, the actuator KN-1 is used in the operation ( Figure 7 In this case, steps S712 and S714 are optionally omitted. Figure 7 Indicated by the dashed connecting line, the projection lens 104 is assembled without applying any correction measures.

[0117] As an example, this also applies to carrier KN-1. As an example, the carriers can include threaded elements, by means of which they are easily adjustable. A corresponding process can also be implemented with fastening elements (e.g., threaded connections). As an example, screws can be tightened with a low torque to compensate for offset or play V. Alternatively, sensors can monitor or verify corrective measures.

[0118] The corrective measures determined above can optionally be verified in the virtual actual assembly model IMM. To this end, the actual assembly model IMM is generated again—with the determined corrective measures applied—and step S710 is repeated.

[0119] Subsequently, the projection lens 104 is assembled from the individual parts K1 to KN, applying defined correction measures. Figure 7 In particular, the corrective measure is implemented during the assembly of the projection lens 104, that is, the above-mentioned spacer 304 is manufactured when the individual parts K1-KN are put together and inserted into the gap V ( Figure 3 ). Alternatively or additionally, these are applied during operation of, for example, a lithographic apparatus 100A, 100B having a projection lens 104, for example as explained above for the actuator. In optional step S714, the assembled projection lens 104 is (actually) measured, wherein the determined assembly measurement data are used to determine further corrective measures, such as the insertion of spacers. In particular, this can be achieved by comparing the assembly measurement data with a target assembly model SMM.

[0120] also, Figure 3 One or all of the illustrated individual parts K1 -KN may be in the form of an assembly. For example, the individual parts K1 and K2 each include a force frame 306 to which one or more optical elements 308 , such as mirrors or lens elements, are fixed.

[0121] The following is based on Figure 4 Explain the above target point assembly model. In it, the virtualized individual parts K1 and KN are fixed at their target positions P from the target assembly model SMM. target Subsequently, individual parts K2, K3 (not shown here), etc. are stacked on individual part K1, and individual parts KN-X, ..., KN-1 (not shown here) are stacked below individual part KN. In this case, X is a number determined according to the design. Therefore, in the exemplary embodiment, the actual position P of individual part KN-1 occurs actual_KN-1 ( Figure 4 The actual position P of the individual part K2 is shown in dashed lines) actual_K2 Then, the determination unit 204 determines the actual position P actual_KN-1 With the actual position P actual_K2 The offset or gap V between the individual parts KN and KN-1 is determined and the insertion of a spacer 304 between the individual parts KN and KN-1 is determined as a corrective measure, so that the offset or gap V is eliminated and the individual parts KN-1 and K2 are arranged relative to each other in the arrangement defined by the construction data ABD. The new position of the individual part KN-1 thus produced is Figure 4 Depicted by a solid line.

[0122] in addition, Figure 3 The features described in the Figure 4 .

[0123] In accordance with Figure 3 and Figure 4 In the exemplary embodiment of , the correction measures concern only two degrees of freedom, specifically the translation directions x and z. Naturally, the correction measures can be associated with each of the six (three rotational and three translational) degrees of freedom, and also with several of these degrees of freedom simultaneously.

[0124] therefore, Figure 5 For example, the insertion of a spacer 304 is shown for the purpose of correcting the corresponding offsets or gaps V in the x, y and z directions. In this case, the corrective measures relating to the correction in the three spatial directions on one individual part KN-1 are shown on the left. In contrast, the corrective measures relating to the different spatial directions x, z shown on the right are implemented in at least two different individual parts, specifically the actuator KN-1' (in the x-direction) and the fastening device KN-2' (in the z-direction), which fixes the actuator KN-1' to the support KN-3'. After the spacer 304 is assembled, the optical element KN and the actuators KN-1, KN-1' are brought together to form the projection lens 104. The optical surface 302 is then located in its desired target position P. target Place.

[0125] The actual assembly model IMM can be determined by means of homogeneous coordinates and / or Euler angles as follows Figure 6 shown.

[0126] Components K1 , K2 (corresponding to KN- 1 ) and K3 (corresponding to KN- 1 ) are arranged in a manner deviating from respective target positions (hereinafter also referred to as “design” or “target posture”) due to manufacturing tolerances.

[0127] The problem therefore arises of determining the thickness that the positioning elements Sp1, Sp2 and Sp3 (corresponding in particular to the spacers 304) should have so that the functional surface CS_F_actual is in the target position CS_F_target relative to the substrate CS_B, and precisely more accurately than the sum of the manufacturing tolerances, typically even more accurately than any individual manufacturing tolerance.

[0128] The coordinate system CS_K represents the body K (virtualization) and is defined as: CS.orig = origin, CS.ex = X axis, CS.ey = Y axis, CS.ez = Z axis, where (CS_K)^B refers to the coordinates of CS_K in CS_B.

[0129] The following calculation example should illustrate this:

[0130] Given the target position in CS_B:

[0131]

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

[0133]

[0134] Let CS_K3 be measured in CS_B:

[0135]

[0136] Let CS_F be measured in CS_K3_actual:

[0137]

[0138] Calculation of the actual pose or actual position of CS_F in CS_B by means of a coordinate transformation from CS_K3 to CS_B (e.g. in homogeneous coordinates):

[0139]

[0140] The 4x4 transformation matrix K3_2_B

[0141]

[0142]

[0143] The offset CS_F_actual from CS_F_target in CS_B coordinates (IS_abs) and CS_F_target coordinates (IS_rel), and an estimate of the actual pose or actual position (compared to the canonical Tol_rel):

[0144]

[0145] Actuator travel calculation in CS_B, where Sp.ez is the unit vector in the effective direction of the positioning element (e.g., the thickness of the effective direction is the displacement it should cause K3 to the target position), Sp.orig is the target position of K3 at the reference point (the K3 side of the positioning element is at rest), and sp_actual is the actual position of K3 at the reference point:

[0146] sp_delta=dot(sp_is,Sp.ez)

[0147] Where sp_is = Sp.orig – sp_actual

[0148] = Displacement from actual to target interval point

[0149] Change [mm]

[0150] Sp1 5.04

[0151] Sp2 11.83

[0152] Sp3 -6.29

[0153] Although the present invention has been described based on exemplary embodiments, the present invention can be modified in various ways.

[0154] Reference Signs List

[0155] 100A EUV lithography equipment

[0156] 100B DUV lithography equipment

[0157] 104 Beam Shaping and Illumination Systems

[0158] 104 Projection System

[0159] 106A EUV light source

[0160] 106B DUV light source

[0161] 108A EUV radiation

[0162] 108B DUV radiation

[0163] 110 reflector

[0164] 112 Reflector

[0165] 114 Reflector

[0166] 116 Reflector

[0167] 118 Reflector

[0168] 120 Photomask

[0169] 122 Reflector

[0170] 124 chips

[0171] 126 optical axis

[0172] 128 lens elements

[0173] 130 reflector

[0174] 132 Medium

[0175] 200 Data processing equipment

[0176] 202 Virtualization Unit

[0177] 204 Determine Unit

[0178] 206 Measuring device

[0179] 208 Measuring device

[0180] 210 Computer Devices

[0181] 212 CNC milling device

[0182] 300 base

[0183] 302 optically effective surface

[0184] 304 spacer

[0185] 306 Force Frame

[0186] 308 optical components

[0187] ABD construction data

[0188] IMM actual assembly model

[0189] KOM Corrective Actions

[0190] K1-KN separate parts

[0191] P target Target location

[0192] P actual Actual location

[0193] P actual_KN-1 Actual location

[0194] P actual_K2 Physical location

[0195] MEM Mechanical Measurement Data

[0196] M1 reflector

[0197] M2 reflector

[0198] M3 reflector

[0199] M4 reflector

[0200] M5 reflector

[0201] M6 reflector

[0202] OEM optical measurement data

[0203] SMM target assembly model

[0204] S700-S716 Method Steps

[0205] V gap

Claims

1. A method for assembling an optical system (104), comprising the steps of: a) measuring (S700, S702) individual parts K1-KN of the optical system (104) for the purpose of providing measurement data (MEM, OEM), where N>1, b) virtualizing (S704) the individual parts K1-KN with the aid of the provided measurement data (MEM, OEM) and generating (S708) an actual assembly model (IMM) from the virtualized individual parts K1-KN by geometrically stringing together a plurality of virtualized individual parts K1-KN, the actual assembly model (IMM) containing the virtual actual positions (P) of the virtualized individual parts K1-KN in the virtual assembled state; actual 、P actual_KN-1 、P actual_K2 ), c) determining (S710) corrective measures based on the actual assembly model (IMM) and a target assembly model (SMM), the target assembly model (SMM) comprising one or more virtual target positions (P) of the virtualized individual parts K1-KN in the virtual assembly state; target ),as well as d) Assembling (S712) the individual parts K1-KN using the corrective measures to form the optical system (104).

2. The method according to claim 1, further comprising: Generating the actual assembly model (IMM) by geometrically stringing together the virtualized individual parts K1-KN, and Based on the virtual actual position (P actual ) and the virtual target position (P target ) determine the corrective measure in step c).

3. The method according to claim 1, further comprising: By fixing the virtualized individual parts K1 and KN in their target positions (P target ) to generate the actual assembly model (IMM), geometrically concatenate the virtualized individual parts K2–KN-1 with K1 and / or KN, and Based on the virtual actual position (P actual_KN-1 、P actual_K2 ) to determine the corrective measures in step c).

4. The method according to any one of claims 1 to 3, wherein The corrective measures in step d) are applied to the individual portion KN-1 or to the area between the individual portions KN-1 and KN.

5. The method according to any one of claims 1 to 3, in, The separate parts KN include: optical elements, or stops, sensors and / or end stops, and / or The separate part KN-1 includes mechanical components, electromechanical components, and / or bearings.

6. The method according to any one of claims 1 to 3, wherein The corrective measures include inserting a spacer (304), adjusting the play of fastening means fastening two of the individual parts K1-KN to each other, and / or adjusting the operating point of the electromechanical component.

7. The method according to claim 5, wherein: Said corrective measure in step c) is determined based on the available actuator travel of the actuator.

8. The method according to any one of claims 1 to 3, wherein N>5 or 10.

9. The method according to any one of claims 1 to 3, wherein In step c) a gap (V) is determined between two of the individual parts K1 -KN, and in step d) a spacer is inserted into the gap.

10. The method according to any one of claims 1 to 3, wherein: Said corrective measures according to step c) relate at least to the first and the second degree of freedom (x, y, z).

11. The method according to claim 10, wherein: In step d), the correction measure is applied to a first of the individual parts K1-KN or between a first pair of individual parts K1-KN for the first degree of freedom (x), and to a second of the individual parts K1-KN or between a second pair of individual parts K1-KN for the second degree of freedom (z).

12. The method according to any one of claims 1 to 3, further comprising: measuring (S714) the assembled optical system (104) to provide assembly measurement data, determining further corrective measures based on a comparison between the assembly measurement data and the target assembly model (SMM), and One or more of the individual parts K1 - KN are aligned based on the determined further corrective measure.

13. A method for operating an optical system (104), comprising the steps of: a) measuring (S700, S702) individual parts K1-KN of the optical system (104) for the purpose of providing measurement data (MEM, OEM), where N>1, b) virtualizing (S704) the individual parts K1-KN with the aid of the provided measurement data (MEM, OEM) and generating (S708) an actual assembly model (IMM) from the virtualized individual parts K1-KN by geometrically stringing together a plurality of virtualized individual parts K1-KN, the actual assembly model (IMM) containing the virtual actual positions (P) of the virtualized individual parts K1-KN in the virtual assembled state; actual 、P actual_KN-1 、P actual_K2 ), c) determining (S710) corrective measures based on the actual assembly model (IMM) and a target assembly model (SMM), the target assembly model (SMM) comprising one or more virtual target positions (P) of the virtualized individual parts K1-KN in the virtual assembly state; target ),as well as d) Assembling (S712) the individual parts K1-KN using the corrective measures to form the optical system (104) and operating the optical system (104).

14. A data processing device (200), comprising: A virtualization unit (202) is used to virtualize individual parts K1-KN of an optical system (104) by means of provided measurement data (MEM, OEM) and to generate an actual assembly model (IMM) from the virtualized individual parts K1-KN by geometrically stringing together a plurality of virtualized individual parts K1-KN, the actual assembly model (IMM) containing the virtual actual positions (P) of the virtualized individual parts K1-KN in a virtual assembled state. actual 、P actual_KN-1 、P actual_K2 ),as well as a determination unit (204) for determining, based on the actual assembly model (IMM) and a target assembly model (SMM), a correction measure for application during assembly of the optical system (104) from the individual parts K1-KN or during operation of the optical system (104) assembled from the individual parts K1-KN, the target assembly model (SMM) containing one or more virtual target positions (P) of the virtualized individual parts K1-KN in the virtual assembly state; target ).

15. A computer program product causing at least one program-controlled device to carry out the following steps: Using provided measurement data (MEM, OEM), individual parts K1-KN of an optical system (104) are virtualized (S704) and a real assembly model (IMM) is generated (S708) from the virtualized individual parts K1-KN by geometrically stringing together a plurality of virtualized individual parts K1-KN, the real assembly model (IMM) containing the virtual real positions (P) of the virtualized individual parts K1-KN in the virtual assembled state. actual 、P actual_KN-1 、P actual_K2 );as well as for determining (S710) corrective measures based on the actual assembly model (IMM) and a target assembly model (SMM), the corrective measures being applied during assembly of the optical system (104) from the individual parts K1-KN or during operation of the optical system (104) assembled from the individual parts K1-KN, the target assembly model (SMM) comprising virtual target positions (P) of one or more of the virtualized individual parts K1-KN in the virtual assembled state; target ).

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