Method of mounting an optical system

Abstract

The present invention relates to a method for mounting an optical system (104), in particular a lithography system (100A, 100B), comprising the steps of: a) measuring components K1-KN of the optical system (104) to provide measurement data (MEM, OEM), where N>1 (S700, S702); and b) virtualizing the components K1-KN using the provided measurement data (MEM, OEM) (S704) and generating an actual mounted model (IMM) from the virtualized components K1-KN (S708), where the actual mounted model (IMM) represents the virtual actual positions (P) of the virtualized components K1-KN in the virtual mounted state. actual , P actual_KN-1 , P actual_K2 ) and c) a step (S710) of determining a corrective measure according to an actual mounting model (IMM) and a target mounting model (SMM), wherein the target mounting model (SMM) determines one or more virtual target positions (P target d) mounting the components K1 to KN using corrective measures to form the optical system (104) (S712).

Description

Technical Field

[0001] The present 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 German priority application No. 10 2019 218 925.3 is incorporated herein by reference.

Background Art

[0003] Microlithography is used, for example, in the manufacture of fine-structure components such as integrated circuits. The microlithography process is performed using a lithography apparatus having an illumination system and a projection system. In this case, an image of a mask (reticle) illuminated by the illumination system is projected by the projection system onto a substrate, such as a silicon wafer, coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection system, so as to transfer the mask structure to the photosensitive coating of the substrate.

[0004] For the configuration of an optical system such as a projection system (also referred to as a projection lens or a projection optical box, POB), it is necessary to accurately position optical surfaces and other functional surfaces (such as diaphragms or end stops) in all six degrees of freedom on the order of micrometers. In doing so, it is often impossible to directly measure the position of the functional surface in the installed state.

[0005] Another problem arises because the required installation accuracy of the functional surface is significantly lower than the manufacturing accuracy of the components or individual parts, or because it would require a large amount of expense to manufacture the functional surface very precisely with respect to the contact surface and the reference surface. Therefore, it is common to insert adjustable spacers at the interfaces between individual parts, for example, at the contact surface or the screw connection. If the initially installed spacer set does not lead to the required positional accuracy of the functional surface, this set is replaced with a new spacer set or adjusted individually, in particular ground or polished. Generally, multiple adjustment loops occur due to the continuous adjustment of six degrees of freedom. Further adjustment loops occur due to the situation where the effective directions of the spacers are not orthogonal to each other, that is, are separated from each other. This increases the time required for manufacturing the optical system and thus also the cost. This is particularly true when the spacers have to be adjusted individually, that is, manufactured to a given dimension.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Based on the above, the object of the present invention is to provide an improved method.

Means for Solving the Problems

[0007] Therefore, a first aspect is a method of assembling an optical system, in particular a lithographic apparatus, comprising: a) measuring individual parts K1 to KN of the optical system for the purpose of providing measurement data, where N > 1; b) virtualizing the individual parts K1 to KN using the provided measurement data and generating an actual assembly model from the virtualized individual parts K1 to KN, the actual assembly model including the virtual actual positions of the virtualized individual parts K1 to KN in a virtual assembled state; c) determining a corrective measure based on the actual assembly model and a target assembly model, the target assembly model including one or more virtual target positions of the virtualized individual parts K1 to KN in a virtual assembled state. d) forming an optical system by assembling the individual parts K1 to KN using correction measures A method including this is proposed.

[0008] As a result, the above-mentioned adjustment loop is generally avoided. Furthermore, correction can be performed at only one position or only a few positions, and the above correction results in a desired target position of a functional surface (of one of the individual parts K1 to KN). Thus, it is not necessary to manufacture all the individual parts very precisely. Furthermore, this also enables very precise adjustment of the relative positions of functional surfaces that are inaccessible by measurement means after assembly. In particular, as a result, this makes it possible to relax the tolerances of the relevant components or individual parts and the assembly process, and thus it is possible to reduce development costs (e.g., development of precision tools) and manufacturing costs (lead time, defective products, individual part costs).

[0009] The optical system can be a lithographic apparatus or a part thereof, such as an illumination system or a projection system.

[0010] The measurement according to step a) can in particular include measurement of the mechanical properties (in particular, metrics, dimensions, tolerances, etc.), optical properties (reflectivity, etc.), and / or thermal properties of each individual part. The measurement can in particular be carried out mechanically or optically.

[0011] In this case, "data" refers to electronic data.

[0012] "Virtualizing the individual parts K1 to KN" refers to the generation of data describing the individual parts K1 to K1. These data can describe the individual parts K1 to KN by points, surfaces, coordinate systems, or three-dimensional bodies.

[0013] "Generating an actual assembly model" means that additional data is added to the electronic data describing the individual parts K1 to KN, and the additional data describes the relationships of the virtualized individual parts K1 to KN such that their virtual actual positions in the virtual assembly state of the virtualized individual parts K1 to KN occur. Such additional data can be configuration data derived from a CAD (computer-aided design) model. The CAD model can include geometric, mechanical, optical, and / or thermal characteristics, parameters, and / or interfaces (between individual parts).

[0014] As an example, an actual assembly model is generated by geometrically connecting a plurality of virtualized individual parts K1 to KN.

[0015] In an embodiment, the actual assembly model includes, for example, the mechanical relationships between the virtualized individual parts K1 to KN in addition to the virtual actual positions of the virtualized individual parts K1 to KN in the virtual assembly state.

[0016] The target assembly model can include data derived from or derived from a CAD model. The target assembly model includes at least the (ideal or required) positions of one or more functional surfaces of one or more individual parts, but can also describe the positions of other individual parts (without functional surfaces).

[0017] As far as the one or more actual and / or target positions of the virtualized individual parts K1 to KN are concerned for the time being, this means the actual and / or target positions of one or more points, surfaces, and / or three-dimensional bodies (e.g., tetrahedral meshes) of the one or more virtualized individual parts K1 to KN.

[0018] The determined corrective measures are preferably designed to act on the geometric and / or mechanical relationships of at least two of the individual parts K1 to KN with respect to each other. That is, the corrective measures affect, for example, the relative positions and / or alignments of at least two individual parts.

[0019] The assembly includes the mutual connection, in particular the joining, of the individual parts K1 to KN, especially by meshing, press fitting, and / or agglomeration. In this case, "connection" is to be understood as referring to meshing, press fitting, or integral adhesive connection, or a combination thereof. A meshing connection is obtained by at least two mating partners engaging with each other in a nested or successive manner. A press fit connection, for example a screw connection, presupposes a normal force on the surfaces to be interconnected. A press fit connection can be obtained by frictional engagement. As long as the reaction force generated by static friction is not exceeded, the mutual displacement of the surfaces is prevented. A press fit connection can also exist as a magnetic force locking engagement. In an agglomeration connection, the mating partners are joined by atomic or molecular forces. An agglomeration connection is a non-detachable connection that can only be separated by the destruction of the connecting means. An agglomeration connection enables, for example, adhesive bonding, soldering, welding, or vulcanization connection.

[0020] N is an integer greater than 1.

[0021] According to one embodiment, the method comprises generating an actual assembly model by geometrically connecting the virtualized individual parts K1 to KN, determining a corrective measure in step c) based on a comparison between the virtual actual position of the virtualized individual part KN and the virtual target position of the virtualized individual part KN and including.

[0022] This represents what is known as virtual contact assembly. According to a variant of virtual contact assembly, the location where the functional surfaces are arranged when all the individual parts are installed according to their geometric measurement data is determined. It is also possible to include, for example, a margin taking into account the deformation of the individual parts. The deformation can result from different mounts and different masses of the individual parts or the assembly. As an example, when constructing a projection lens, the force frame is first attached and modules are sequentially loaded onto it, so the force frame deforms under the change of load.

[0023] According to yet another embodiment, the method comprises Generating an actual assembly model by fixing the virtualized individual components K1 to KN at their target positions from the target assembly model; Geometrically connecting the virtualized individual components K2 to KN-1 to K1 and / or KN; Determining a corrective measure in step c) based on the virtual actual positions of at least two virtualized individual components K2 to KN-1; and including.

[0024] This represents virtual target point assembly. Within the scope of virtual target point assembly, it is preferred that remaining gaps occur directly between (two or more) individual components that do not come into contact at the end of the connection process (among the individual components K2 to KN).

[0025] According to yet another embodiment, the corrective measure in step d) is applied to the individual component KN-1 or to the region between the individual components KN-1 and KN, particularly to the gap.

[0026] Advantageously, the correction is performed adjacent to the individual component KN (particularly having a functional surface). There is a high probability that the tolerances are mutually compensated up to the individual component KN-1.

[0027] According to yet another embodiment, the individual component KN includes an optical element, particularly a mirror, a lens element, an optical grating, and / or a wave plate, a diaphragm, a sensor, and / or an end stop.

[0028] These show examples of individual components KN having functional surfaces.

[0029] Alternatively, the individual component KN can be a mechanical component, a mechatronics component, particularly an actuator, and / or a bearing.

[0030] According to yet another embodiment, the individual component KN-1 includes a mechanical component, a mechatronics component, particularly an actuator, and / or a bearing.

[0031] Advantageously, defect correction is carried out on the above components because it can be easily achieved, for example, by adjusting the operating range of the actuator. In this case, the "mechanical component" particularly includes mechanical reference surfaces or fits, such as alignment pins or alignment holes. In this case, the "bearing" particularly includes mechanical bearings and / or magnetic bearings, such as weight compensation devices for optical elements.

[0032] According to yet another embodiment, the corrective measures particularly include inserting a spacer between two of the individual parts K1 to KN, adjusting the play of the fixing means that particularly fix two of the individual parts K1 to KN to each other, and / or adjusting the operating point of the actuator as a constituent part of a mechatronics component, particularly of one of the individual parts K1 to KN.

[0033] According to yet another embodiment, the corrective measure in step c) is determined based on the possible actuator movement amount of the actuator.

[0034] According to yet another embodiment, N > 5 or 10.

[0035] According to yet another embodiment, in step c), the gap between two of the individual parts K1 to KN is determined, and in step d), a spacer is inserted into the gap.

[0036] The spacer is preferably a spacer means, a shim, etc. made of metal or ceramic. As an alternative or in addition, the spacer can be adjustable with respect to the space defined thereby, particularly with respect to its thickness, and can be provided, for example, in the form of a setting screw or mutually displaceable wedges. In an embodiment, the spacer can be removed again after assembly, i.e., particularly after step d).

[0037] According to yet another embodiment, the corrective measure according to step c) relates to at least the first and second degrees of freedom.

[0038] According to yet another embodiment, the corrective measure is applied, in step d), to the first part of the individual parts K1 to KN or between the first pair of the individual parts K1 to KN with respect to the first degree of freedom, and to the second part of the individual parts K1 to KN or between the second pair of the individual parts K1 to KN with respect to the second degree of freedom.

[0039] As a result of the corrective measure being split between different individual parts, this can be determined more easily (the situation where the corrective measures affect each other is avoided or reduced).

[0040] According to yet another embodiment, the method comprises measuring the assembled optical system in order to provide assembly measurement data, determining yet another corrective measure based on a comparison between the assembly measurement data and the target assembly model, and aligning one or more of the individual parts K1 to KN based on the determined yet another corrective measure.

[0041] At this point, further correction is made by comparing the assembled optical system with the target assembly model.

[0042] According to yet another embodiment, the actual assembly model is required to be determined using analytical geometry, in particular homogeneous coordinates and / or Euler angles.

[0043] This can be easily implemented, in particular, by a computer device such as a microprocessor.

[0044] A second aspect is a method of operating an optical system, in particular a lithographic apparatus, comprising: a) measuring the individual parts K1 to KN of the optical system in order to provide measurement data, where N > 1; b) virtualizing the individual parts K1 to KN using the provided measurement data and generating an actual assembly model from the virtualized individual parts K1 to KN, the actual assembly model including the virtual actual positions of the virtualized individual parts K1 to KN in a virtual assembled state.​ c) determining a corrective measure based on the actual assembly model and the target assembly model, wherein the target assembly model includes one or more virtual target positions of the virtualized individual parts K1 to KN in a virtual assembly state; d) assembling the individual parts K1 to KN using the corrective measure to form an optical system and operating the optical system; A method including the above steps is proposed.

[0045] Operating the optical system refers to its use for its intended purpose. In particular, operating the optical system means performing an exposure process using the optical system, for example, exposing a wafer for manufacturing a microchip. Advantageously, by using appropriate adjustment of the controller of the optical system, manufacturing defects (tolerances) are corrected here. As an example, movement of the actuator or an operating point during operation can be given so as to obtain correction.

[0046] The method according to the second aspect can be combined with the method according to the first aspect, so that the corrective measure is first determined during assembly and operation, and subsequently applied during assembly or operation. Therefore, according to the third aspect, the following is provided.

[0047] A method of assembling and / or operating an optical system, in particular a lithographic apparatus, comprising: a) measuring the individual parts K1 to KN of the optical system for the purpose of providing measurement data, where N > 1; b) virtualizing the individual parts K1 to KN using the provided measurement data and generating an actual assembly model from the virtualized individual parts K1 to KN, wherein the actual assembly model includes the virtual actual positions of the virtualized individual parts K1 to KN in a virtual assembly state; c) determining a corrective measure based on the actual assembly model and the target assembly model, wherein the target assembly model includes one or more virtual target positions of the virtualized individual parts K1 to KN in a virtual assembly state; d) assembling the K1 to KN individual parts using the corrective measure to form an optical system and / or operating the optical system using the corrective measure; A method including

[0048] A fourth aspect is a data processing device, a virtualization unit that virtualizes individual components K1 to KN of an optical system using provided measurement data and generates an actual assembly model from the virtualized individual components K1 to KN, the actual assembly model including virtual actual positions of the virtualized individual components K1 to KN in a virtual assembly state, and a determination unit that determines correction measures to be applied during assembly of the optical system from the individual components K1 to KN or during operation of the optical system assembled from the individual components K1 to KN based on the actual assembly model and a target assembly model, the target assembly model including one or more virtual target positions of the virtualized individual components K1 to KN in a virtual assembly state, and proposes a data processing device including

[0049] Each device or unit, such as a measurement 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 implementation, each unit can be embodied as a device or part of a device, for example, as a computer or a microprocessor. In the case of a software implementation, each device or unit can be embodied as a computer program product, as a function, as a routine, as a part of program code, or as an executable object.

[0050] A fifth aspect is a computer program product, with at least one program-controlled device, a step of virtualizing individual components K1 to KN of an optical system using provided measurement data and generating an actual assembly model from the virtualized individual components K1 to KN, the actual assembly model including virtual actual positions of the virtualized individual components K1 to KN in a virtual assembly state, and A step of determining a correction measure to be applied during the assembly of the optical system from the individual parts K1 to KN or during the operation of the optical system assembled from the individual parts K1 to KN based on the actual assembly model and the target assembly model, wherein the target assembly model includes one or more virtual target positions of the virtualized individual parts K1 to KN in the virtual assembly state, and proposes a computer program product for instructing the implementation of.

[0051] For example, a computer program product such as computer program means can be provided or supplied as a storage medium, for example, a memory card, a USB stick, a CD-ROM, a DVD, etc., or in the form of a file downloadable from a server on a network. As an example, this can be done by transferring an appropriate file having the computer program product in a wireless communication network.

[0052] In this case, "one" should not necessarily be understood as limiting to exactly one element. Rather, for example, two, three, or more elements can also be provided. Any other numbers used here should not be understood as limiting to the exact number of elements described. Rather, unless otherwise indicated, numerical deviations above and below are possible. The notation of method steps such as a), b), etc. should not be construed as a limitation to a specific order. The steps can also be re-written, for example, step b) becomes step f), especially for the purpose of inserting a previous or subsequent step or an intermediate step.

[0053] The embodiments and features described for the method according to the first aspect are applicable mutatis mutandis to the method proposals, data processing apparatuses, and computer program products according to the second and third aspects, and vice versa.

[0054] Further possible embodiments of the present invention also include any combination of features or embodiments not explicitly mentioned above or below with respect to the exemplary embodiments. In this case, those skilled in the art may add individual aspects to each basic form of the present invention as improvements or supplements.

[0055] Further advantageous improvements and aspects of the present invention are the subject of the dependent claims and also of the subject of the exemplary embodiments of the present invention described hereinafter. In the following text, the present invention will be described in more detail based on the preferred embodiments with reference to the accompanying drawings.

Brief Description of the Drawings

[0056]

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0057] Unless otherwise indicated, the same or functionally equivalent elements are denoted by the same reference numerals in the figures. It should also be noted that the illustrations are not necessarily to scale.

[0058] Figure 1A shows a schematic diagram of an EUV lithography apparatus 100A including a beam shaping / illuminating system 102 and a projection system 104. In this case, EUV means "extreme ultraviolet" and indicates the wavelength of the light used in the range of 0.1 nm to 30 nm. The beam shaping / illuminating system 102 and the projection system 104 are each provided within a vacuum housing (not shown), and each vacuum housing is evacuated using an evacuation device (not shown). The vacuum housing is surrounded by a machine room (not shown) provided with a drive device for mechanical movement or setting of the optical elements. Further, an electric controller or the like may also be provided in the machine room.

[0059] The EUV lithography apparatus 100A has an EUV light source 106A. A plasma source (or synchrotron) that emits radiation 108A in the EUV region (extreme ultraviolet region), that is, for example, in the wavelength range of 5 nm to 20 nm, can be provided as the EUV light source 106A, for example. In the beam shaping / illuminating system 102, the EUV radiation 108A is focused and the desired operating wavelength is filtered from the EUV radiation 108A. Since the EUV radiation 108A generated by the EUV light source 106A has a relatively low transmittance in air, the beam guiding spaces in the beam shaping / illuminating system 102 and the projection system 104 are evacuated.

[0060] The beam shaping / illuminating system 102 shown in Figure 1A has five mirrors 110, 112, 114, 116, 118. After passing through the beam shaping / illuminating system 102, the EUV radiation 108A is directed towards a photomask (reticle) 120. The photomask 120 is also in the form of a reflective optical element and can be arranged outside the systems 102, 104. Further, the EUV radiation 108A can be directed towards the photomask 120 by a mirror 122. The photomask 120 has a structure that is reduced by the projection system 104 and imaged onto a wafer 124 or the like.

[0061] 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, the individual mirrors M1 to M6 of the projection system 104 can be arranged symmetrically with respect to 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 in the figure. A larger or smaller number of mirrors M1 to M6 can also be provided. Furthermore, the mirrors M1 to M6 are generally curved on the front side for beam shaping.

[0062] Figure 1B shows a schematic diagram of a DUV lithography apparatus 100B equipped with a beam shaping / illumination system 102 and a projection system 104. In this case, DUV means "deep ultraviolet" and indicates the wavelength of the light used, which is from 30 nm to 250 nm. As already described with reference to Figure 1A, the beam shaping / illumination system 102 and the projection system 104 can each be provided within a vacuum housing and / or surrounded by a machine chamber having corresponding drive devices.

[0063] The DUV lithography apparatus 100B has a DUV light source 106B. As an example, an ArF excimer laser that emits radiation 108B in the DUV range of, for example, 193 nm can be provided as the DUV light source 106B.

[0064] The beam shaping / illumination system 102 shown in Figure 1B guides the DUV radiation 108B to the photomask 120. The photomask 120 is formed as a transmissive optical element and can be arranged outside the systems 102 and 104. The photomask 120 has a structure that is reduced by the projection system 104 and imaged onto the wafer 124 and the like.

[0065] 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 with respect to the optical axis 126 of the projection system 104. Note that the number of lens elements 128 and mirrors 130 of the DUV lithography apparatus 100B is not limited to the numbers shown in the figure. A larger or smaller number of lens elements 128 and / or mirrors 130 can also be provided. Furthermore, the mirror 130 is generally curved on the front side for beam shaping.

[0066] The air gap between the lens element 128 and the wafer 124 can be replaced with a liquid medium 132 having a refractive index greater than 1. The liquid medium 132 can be, for example, high-purity water. Such a structure is also referred to as immersion lithography and has a high photolithography resolution. The medium 132 can also be referred to as the immersion liquid.

[0067] FIG. 2 shows a data processing apparatus 200 used in a method of assembling and operating a projection system or projection lens 104 (specifically shown in FIG. 1A or FIG. 1B) or any other optical system. The flowchart of this method is shown in FIG. 7.

[0068] The data processing apparatus 200 is, for example, in the form of a computer device including a microprocessor and associated memory means, such as 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 both hardware-wise and / or software-wise, i.e., in the form of program code.

[0069] Mechanical measurement data MEM and any optical measurement data OEM are provided to the virtualization unit 202. Furthermore, additional measurement data, such as thermal measurement data, can also be provided to the virtualization unit 202.

[0070] The mechanical measurement data describes at least the geometric shape of each individual part K1 to KN. The individual parts K1 to KN are exemplarily shown in an unassembled state in FIG. 2 and are assembled to form the projection lens 104 (see FIGS. 1A, 1B, 3, and 4) in the assembly steps described in more detail below. The individual parts K1 to KN can be individual parts or assemblies (consisting of a plurality of interconnected individual parts).

[0071] The optical measurement data OEM describes one or more optical properties of the individual parts K1 to KN. Here, by way of example, the following are mentioned: the relative position of the optical axis or optical surface, the reflectivity (optionally spatially resolved), the transmittance (likewise optionally spatially resolved).

[0072] The mechanical measurement data MEM may in particular be acquired (at S700 in FIG. 7) and provided by a measurement device 206, for example a coordinate measuring machine (CMM), which mechanically measures the individual parts K1 to KN for this purpose. The optical measurement data OEM may likewise be acquired (at step S702) and provided by a measurement device 208, for example an interferometer, which optically measures the individual parts K1 to KN.

[0073] The virtualization unit 202 generates virtualized individual parts K1 to KN from the provided measurement data MEM, OEM (at S704 in FIG. 7). This is to be understood as meaning a mathematical, in particular geometric, description of the (real) individual parts K1 to KN, for example in the form of a matrix, stored in the data memory.

[0074] Furthermore, configuration data ABD is provided to the virtualization unit 202. The configuration data ABD describes at least the geometric and possibly mechanical connections, interfaces, and contact surfaces between the virtual individual parts K1 to KN in a virtual actual assembly model IMM that has not yet been created. In this case, the geometric connection or geometric interface reproduces the real connection or interface, for example the fixing means between the individual parts K1 to KN to be assembled.

[0075] The component data ABD can be provided from a CAD (Computer Aided Design) program and / or an optical design program (S706 in FIG. 7). As an example, this software can be executed on the computer device 210.

[0076] The virtualization unit 202 generates a (virtual) actual assembly model IMM from the virtualized individual components K1 to KN and the component data ABD (step S708 in FIG. 7). The individual components K1 to KN are virtually assembled with each other in the actual assembly model IMM, and the relationship between the individual components K1 to KN, particularly the geometric arrangement, is defined by the component data ABD, particularly by the contact surfaces and boundary surface information described therein.

[0077] The actual assembly model IMM can be generated in various ways, and subsequently the determined corrective measure KOM is adapted to the corresponding model. In principle, the corrective measure KOM is determined from the actual assembly model IMM and the target assembly model SMM, particularly by comparing the two models IMM and SMM.

[0078] The target assembly model SMM describes one or more virtual target positions of the virtualized individual components K1 to KN in the virtual assembly state. In this case, the target assembly model SMM assumes ideal individual components K1 to KN, that is, individual components K1 to KN that exactly correspond to, for example, a CAD model. In this case, the ideal individual components K1 to KN are connected to each other by the component data ABD, particularly geometrically. The target assembly model SMM can likewise be provided from a CAD (Computer Aided Design) program and / or an optical design program, that is, using, for example, the computer device 210. The corrective measure KOM is provided in the form of data particularly to the CNC (Computer Numerical Control) milling device 212. Depending on the corrective measure or appropriate data, the CNC milling device 212 automatically machines an appropriate spacer 304 (see the following description) or other compensation elements.

[0079] In the following, the contact assembly model will first be described with reference to FIG. 3, and then the target point assembly model will be described with reference to FIG. 4.

[0080] According to the contact assembly model, the virtualized individual parts K1 to KN are geometrically connected by being stacked on top of each other in an exemplary embodiment. In this case, for example, the base 300 is selected for the individual part K1. The subsequent individual parts K2 to KN are stacked on top of each other while taking into account the configuration data ABD, that is, K2 is placed on K1, K3 is placed on K2, and KN is placed on KN-1.

[0081] As an example, the individual part KN is selected to be a component having what is known as a functional surface. This means a surface that is important for the function of the lithographic apparatus, such as an optical surface or an end stop, that is, a stop that limits the maximum movement of the optical element. Thus, the individual part KN is in particular an optical element, such as a mirror, a lens element, an optical grating, or a wave plate. In an exemplary embodiment, the individual part KN is a mirror having an optically effective surface 302 (optical footprint).

[0082] Here, by stacking the individual parts K1 to KN on top of each other, the individual part KN or its functional surface (optically effective surface 302) is placed at the actual position P actual is arranged. In FIG. 3, the individual part KN is shown at this position using a dashed line.

[0083] The determination unit 204 (see FIG. 2) compares the actual position P actual with the target position P target from the target assembly model SMM. FIG. 3 shows the target position P target of the individual part KN using a solid line. In this case, between P actual and P target there is a deviation in the form of an offset or gap V in the x direction (that is, for example, in the plane of the main extension plane of the optically effective surface 302) and in the z direction, for example, the vertical direction, that is, a direction particularly perpendicular to the main extension plane of the optically effective surface 302. Thus, as a corrective measure, in step S710 (FIG. 7), the determination unit 204 determines the insertion of one or more spacers 304, which can be in the form of spacer means, shims, etc., made particularly of metal and / or ceramic.

[0084] The spacer 304 is preferably inserted between the individual part KN and the individual part KN-1 thereunder. In this case, N is preferably 6 or more and less than 10. As a further alternative, the corrective measure can be carried out on the individual part KN itself, for example by appropriate material ablation therefrom.

[0085] More preferably, the individual part KN-1 is a mechatronics component, in particular an actuator, and / or a bearing. In particular, the actuator is advantageous because it can be set to provide a corrective measure. As an example, in the case of the exemplary embodiment of FIG. 3, the actuator KN-1 can be set with respect to its operating range or operating point so as to compensate for the offset or gap V. However, the (maximum) possible actuator movement of the actuator should be taken into account at that time. Thus, in this case (when the actuator movement is insufficient), the spacer 304 is not necessary (although this will probably be an exception). Rather, the actuator KN-1 is appropriately actuated during operation of the lithographic apparatus (100A, 100B) (step S716 in FIG. 7). In this case, as shown by the dashed connecting line in FIG. 7, steps S712 and S714 are optionally omitted and the projection lens 104 is assembled without applying a corrective measure.

[0086] As an example, the same applies to the bearing KN-1. As an example, the bearing can include screw means and can be easily adjusted using this. Also in the case of fixing means, for example a screw connection, a corresponding procedure can be carried out. As an example, the screw is tightened with low torque to compensate for the offset or gap V. As a further alternative, a sensor can monitor or confirm the corrective measure.

[0087] The determined corrective measure described above can optionally be verified in the virtual actual assembly model IMM. For this purpose, the actual assembly model IMM is regenerated by applying the determined corrective measure and step S710 is repeated.

[0088] Subsequently, the determined corrective measures are applied such that the projection lens 104 is assembled from the individual parts K1 to KN (S712 in FIG. 7). In particular, the corrective measures are carried out during the assembly of the projection lens 104, i.e., the spacer 304 is manufactured and inserted into the gap V (FIG. 3) during the assembly of the individual parts K1 to KN. Alternatively or additionally, these are applied, for example, during the operation of the lithographic apparatuses 100A, 100B having the projection lens 104, as described above for the actuator. In any step S714, the assembled projection lens 104 is (actually) measured and the obtained assembly measurement data is used for the determination of further corrective measures, such as the insertion of spacers. In particular, this can be carried out by comparing the assembly measurement data with the target assembly model SMM.

[0089] Furthermore, FIG. 3 shows that each or all of the individual parts K1 to KN can be in the form of an assembly. As an example, the individual parts K1 and K2 each include a force frame 306 to which, for example, one or more optical elements 308, such as mirror or lens elements, are fixed.

[0090] The above target point assembly model will be described below with reference to FIG. 4. Here, the virtualized individual parts K1 to KN are fixed to their target positions P from the target assembly model SMM target . Subsequently, the individual parts K2, K3 (not shown), etc. are stacked on top of the individual part K1, and the individual parts KN-X,..., KN-1 (not shown) are stacked under the individual part KN. In this case, X is a number determined from the design. Thus, in an exemplary embodiment, the actual position P actual_KN-1 (shown by the dashed line in FIG. 4) of the individual part KN-1 and the actual position P actual_K2 of the individual part K2 occur. The determination unit 204 then subsequently determines the actual positions P actual_KN-1 and P actual_K2Determine the offset or gap V between them, and as a corrective measure, determine the insertion of the spacer 304 between the individual parts KN and KN-1 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 configuration data ABD. The new position of the resulting individual part KN-1 is shown by the solid line in FIG. 4.

[0091] Otherwise, the features shown in FIG. 3 shall apply mutatis mutandis to FIG. 4.

[0092] In the exemplary embodiments shown in FIGS. 3 and 4, the corrective measures relate to only two degrees of freedom, specifically the translational directions X and Z. Of course, the corrective measures can relate to each of the six (three rotational and three translational) degrees of freedom, and can also relate to some of these degrees of freedom simultaneously.

[0093] FIG. 5 shows, for example, the insertion of the spacer 304 for the purpose of correcting each offset or gap V in the x-direction, y-direction, and z-direction. In this case, the corrective measures for the correction of the three spatial directions in one individual part KN-1 are shown on the left side. In contrast, the corrective measures shown on the right side relate to different spatial directions x and z, and are carried out by at least two different individual parts, specifically the actuator KN-1' (x-direction) and the fixing means KN-2' (z-direction) for fixing the actuator KN-1' to the support KN-3'. After the assembly of the spacer 304, the optical element KN and the actuators KN-1, KN-1' are assembled to form the projection lens 104. Then, the optical surface 302 is at its desired target position P target is located.

[0094] As shown below in FIG. 6, the above-described actual assembly model IMM can be determined using homogeneous coordinates and / or Euler angles.

[0095] The components K1, K2 (corresponding to KN-1), and K3 (corresponding to KN-1) are arranged offset from their respective target positions (hereinafter also referred to as "design" or "target pose") due to manufacturing tolerances.

[0096] Therefore, the problem is to determine the thicknesses that the positioning elements Sp1, Sp2, and Sp3 (in particular corresponding to spacer 304) should have such that the functional surface CS_F_actual is at the target position CS_F_target with respect to the base CS_B, i.e., more precisely than the sum of the manufacturing tolerances, and usually even more precisely than any individual manufacturing tolerance.

[0097] The coordinate system CS_K represents (virtualizes) the body K and is defined by CS.orig = origin, CS.ex = X-axis, CS.ey = Y-axis, and CS.ez = Z-axis, and (CS_K)^B refers to the coordinates of CS_K in CS_B.

[0098] The following calculation example shows this.

[0099] Target position given in CS_B: (CS_F_target)^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:

[0010] ez: [-0.2419 0 0.9703]

[0100] Three spacer reference points and effective directions: 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]

[0101] When measuring CS_K3 with CS_B: (CS_K3_actual)^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]

[0102] When measuring CS_F with CS_K3_actual: (CS_F_actual)^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]

[0103] For example, the calculation of the actual posture or actual position of CS_F in CS_B by coordinate transformation from CS_K3 to CS_B in homogeneous coordinates: (CS_F_actual)^B = K3_2_B * (CS_F_actual)^K3 JPEG0007712926000001.jpg31127 Using the 4x4 transformation matrix K3_2_B CS_F_achtual = name: 'CS_F' base: 'CS_Base' Original: [90.0542 208.6420 294.7950] Example: [ 0.9780 0.0137 0.2082] Eye: [-0.0163 0.9998 0.0109] Ez: [-0.2080 -0.0140 0.9780]

[0104] Offset from CS_F_target to CS_F_actual in CS_B coordinates (IS_abs) and CS_F target coordinates (IS_rel), and evaluation of the actual pose or actual position (compared with specification Tol_rel) Pose CS_F with respect to CS_Base: [mm, mrad] Tx Ty Tz Rx Ry Rz Target: 95.000 200.000 305.000 -0.000 -244.346 -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

[0105] Calculation of the actuator movement amount in CS_B, where Sp.ez is the unit vector of the effective direction of the positioning element (for example, the effective direction is the thickness that brings about the displacement of K3 to the target position), Sp.orig is the target position of K3 at the reference point (the K3 side support base of the positioning element), and sp_actual is the actual position of K3 at the reference point: sp_delta = dot(sp_is, Sp.ez) Where sp_is = sp.orig - sp_actual = Spacer point displacement from actual to target Change [mm] Sp1 5.04 Sp2 11.83 Sp3 -6.29

[0106] The present invention has been described based on exemplary embodiments, but can be modified in various ways.

Explanation of Reference Numerals

[0107] 100A EUV lithography apparatus 100B DUV lithography apparatus 104 Beam shaping and illumination system 104 Projection system 106A EUV light source 106B DUV light source 108A EUV radiation 108B DUV radiation 110 Mirror 112 Mirror 114 Mirror 116 Mirror 118 Mirror 120 Photomask 122 Mirror 124 Wafer 126 Optical axis 128 Lens element 130 Mirror 132 Medium 200 Data processing device 202 Virtualization unit 204 Decision unit 206 Measuring device 208 Measuring device 210 Computer device 212 CNC milling device 300 Base 302 Optically effective surface 304 Spacer 306 Force frame 308 Optical element ABD Configuration data IMM Actual Assembly Model KOM Corrective Measures K1 - KN Individual Parts P target Target Position P actual Actual Position P actual_KN-1 Actual Position P actual_K2 Actual Position MEM Mechanical Measurement Data M1 Mirror M2 Mirror M3 Mirror M4 Mirror M5 Mirror M6 Mirror OEM Optical Measurement Data SMM Target Assembly Model S700 - S716 Method Steps V Gap

Claims

1. A method of assembling an optical system (104), comprising: a) measuring individual components K1 to KN of the optical system (104) for the purpose of providing measurement data including at least mechanical measurement data (steps S700, S702), where N > 1; b) virtualizing the individual parts K1 to KN using the provided measurement data (S704), and generating an actual assembly model (IMM) from the virtualized individual parts K1 to KN by bringing the plurality of virtualized individual parts K1 to KN into contact with each other (S708), the actual assembly model (IMM) being the virtual actual positions (P ａｃｔｕａｌ , P ａｃｔｕａｌ＿ＫＮ－１ , P ａｃｔｕａｌ＿Ｋ２ ) of the virtualized individual parts K1 to KN in a virtual assembled state, and c) A step (S710) of determining a corrective measure based on the actual assembly model (IMM) and the target assembly model (SMM), wherein the target assembly model (SMM) is one or more virtual target positions (P ｔａｒｇｅｔ ) of the virtualized individual parts K1 to KN in a virtual assembly state, and the determination of the corrective measure is executed based on a comparison between the virtual actual position (Pactual, Pactual_KN-1, Pactual_K2) and the virtual target position (Ptarget); d) assembling the individual components K1 to KN using the correction measures to form the optical system (104) (step S712); and a method including the above steps.

2. The method according to claim 1, wherein the correction measures in step d) are applied to the individual component KN-1 or to the region between the individual components KN-1 and KN.

3. The method according to claim 1 or 2, wherein the individual component KN includes an optical element, a diaphragm, a sensor, and / or an end stop, and / or the individual component KN-1 includes a mechanical component, a mechatronics component, and / or a bearing.

4. The method according to any one of claims 1 to 3, wherein the correction measures include inserting a spacer (304) between two of the individual components K1 to KN, adjusting the play of fixing means for fixing two of the individual components K1 to KN to each other, and / or adjusting the operating point of an actuator as one of the components of the individual components K1 to KN of a mechatronics component.

5. The method according to claim 3 or 4, wherein the correction measures in step c) are determined based on the possible actuator movement amount of the actuator.

6. The method according to any one of claims 1 to 5, wherein N > 5.

7. The method according to any one of claims 1 to 6, wherein in step c), a gap (V) between two of the individual components K1 to KN is determined, and in step d), a spacer is inserted into the gap.

8. The method according to any one of claims 1 to 7, wherein the correction measures according to step c) relate to at least two degrees of freedom including a first degree of freedom and a second degree of freedom.

9. In the method according to claim 8, the corrective measure is applied, in step d), to the first part of the individual parts K1 to KN or between the first pair of the individual parts K1 to KN with respect to the first degree of freedom (x), and to the second part of the individual parts K1 to KN or between the second pair of the individual parts K1 to KN with respect to the second degree of freedom (z).

10. In the method according to any one of claims 1 to 9, a step (S714) of measuring the assembled optical system (104) for providing assembly measurement data; a step of determining a further corrective measure based on a comparison between the assembly measurement data and the target assembly model (SMM); a step of aligning one or more of the individual parts K1 to KN based on the determined further corrective measure and further comprising a method.

11. A method of operating an optical system (104), comprising: a) steps (S700, S702) of measuring individual parts K1 to KN of the optical system (104) for the purpose of providing measurement data including at least mechanical measurement data, where N > 1; b) virtualizing the individual parts K1 to KN using the provided measurement data (S704), and generating an actual assembly model (IMM) from the virtualized individual parts K1 to KN by bringing the plurality of virtualized individual parts K1 to KN into contact with each other (S708), wherein the actual assembly model (IMM) is the virtual actual positions (P ａｃｔｕａｌ , P ａｃｔｕａｌ＿ＫＮ－１ , P ａｃｔｕａｌ＿Ｋ２ ) of the virtualized individual parts K1 to KN in a virtual assembled state, and c) A step (S710) of determining a corrective measure based on the actual assembly model (IMM) and the target assembly model (SMM), wherein the target assembly model (SMM) is one or more virtual target positions (P of the virtualized individual parts K1 to KN in the virtual assembly state ｔａｒｇｅｔ ) is included, and the determination of the corrective measure is executed based on a comparison between the virtual actual position (Pactual) and the virtual target position (Ptarget); d) a step of assembling the individual parts K1 to KN using the corrective measure to form the optical system (104) (S712) and operating the optical system (104). and a method comprising.

12. A data processing device (200), A virtualization unit (202) that virtualizes the individual components K1 to KN of the optical system (104) using measurement data including at least mechanical measurement data provided by measuring the individual components K1 to KN of the optical system, and generates an actual assembly model (IMM) from the virtualized individual components K1 to KN by bringing the plurality of virtualized individual components K1 to KN into contact with each other, wherein the actual assembly model (IMM) has virtual actual positions (P ａｃｔｕａｌ , P ａｃｔｕａｌ＿ＫＮ－１ , P ａｃｔｕａｌ＿Ｋ２ ) of the virtualized individual components K1 to KN in a virtual assembled state, and the virtualization unit (202) including the virtualized individual components K1 to KN A determination unit (204) that determines a correction measure to be applied during the assembly of the optical system (104) from the individual parts K1 to KN or during the operation of the optical system (104) assembled from the individual parts K1 to KN, based on the actual assembly model (IMM) and the target assembly model (SMM), wherein the target assembly model (SMM) includes one or more virtual target positions (P ｔａｒｇｅｔ ) of the virtualized individual parts K1 to KN in a virtual assembled state, and the determination of the correction measure is performed by the determination unit (204) based on a comparison between the virtual actual position (Pactual) and the virtual target position (Ptarget) a data processing device provided with.

13. A computer program product, comprising at least one program-controlled device, Using measurement data including at least mechanical measurement data provided by measuring the individual components K1 to KN of the optical system, the individual components K1 to KN of the optical system (104) are virtualized (S704), and by bringing the plurality of virtualized individual components K1 to KN into contact with each other, generating an actual assembly model (IMM) from the virtualized individual components K1 to KN, wherein the actual assembly model (IMM) is the virtual actual position (P ａｃｔｕａｌ , P ａｃｔｕａｌ＿ＫＮ－１ , P ａｃｔｕａｌ＿Ｋ２ ) including steps and Step (S710) of determining a corrective measure to be applied during the assembly of the optical system (104) from the individual parts K1 to KN or during the operation of the optical system (104) assembled from the individual parts K1 to KN based on the actual assembly model (IMM) and the target assembly model (SMM), wherein the target assembly model (SMM) includes one or more virtual target positions (P ｔａｒｇｅｔ ) of the virtualized individual parts K1 to KN in a virtual assembled state, and the determination of the corrective measure is performed based on a comparison between the virtual actual position (Pactual) and the virtual target position (Ptarget), and a computer program product for instructing the implementation of.

Images