Method for replacing a first module with a second module of a lithography apparatus

Abstract

A method for replacing a first module (102) with a second module (102') of a lithography apparatus (1), including the steps of: a) measuring (S5) a first actual position (P1IST) of a reference body (200) with the aid of a measuring device (300), b) measuring (S6) an actual position (PIST) of the first module (102) with the aid of the measuring device (300), disassembling (S7) the first module (102) and assembling (S8) the second module (102') on the basis of the measured actual position (PIST) of the first module (102), c) measuring (S9) a second actual position (P2IST) of the reference body (200) with the aid of the measuring device (300), and d) ascertaining (S10) whether the measured second actual position (P2IST) deviates from the measured first actual position (P1IST) of the reference body (200).

Description

[0001] Carl Zeiss SMT GmbH

[0002] 1

[0003] METHOD FOR REPLACING A FIRST MODULE WITH A SECOND MODULE OF A LITHOGRAPHY APPARATUS

[0004] The present invention relates to a method for replacing a first module with a sec¬ ond module of a lithography apparatus.

[0005] The content of the priority application DE 10 2025 103 499.0 is incorporated by reference in its entirety (incorporation by reference).

[0006] Microlithography is used to produce microstructured components, for example integrated circuits. The microlithography process is carried out using a lithography apparatus having an illumination system and a projection system. The image of a mask (reticle) illuminated by means of the illumination system is projected here by means of the projection system onto a substrate, for example a silicon wafer, which is coated with a light-sensitive layer (photoresist) and is arranged in the image plane of the projection system, in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0007] Driven by the desire for ever smaller structures in the production of integrated circuits, EUV lithography apparatuses that use light at a wavelength in the range of 0.1 nm to 30 nm, in particular 13.5 nm, are currently under develop¬ ment. Since most materials absorb light at this wavelength, such EUV lithography apparatuses require the use of reflective optical units, i.e. mirrors, instead of refractive optical units, i.e. lens elements, as used previously.

[0008] The projection system (also referred to as projection optics unit or projection lens) of the lithography apparatus comprises multiple mirrors and / or lens elements. These optical elements must sometimes be replaced. For example, the lithogra¬ phy apparatus may lose optical alignment capability after a certain number of operating hours. Optics modules, comprising a holding frame and the optical ele¬ ment held therein, are generally replaced as one. The optics modules can be handled easily, in contrast with the very sensitive optical elements.

[0009] Especially in connection with non-actuated optical elements, the problem that arises when an optics module is replaced is that the positioning of the new optically effective surface must be as identical as possible to that of the old optically effective surface. Unlike in the case of actuated optical elements, which are regularly adjustable in up to six degrees of freedom, the new optical element cannot be corrected retrospectively after its installation.Carl Zeiss SMT GmbH

[0010] 2

[0011] A further problem is that highly accurate measuring instruments for checking and optionally correcting the position of the new optically effective surface are seldom available at the operating site of the lithography apparatus. For example, integrated circuits are manufactured using the lithography apparatus at the operating site. Coordinate measuring machines, in particular, are high accurate measuring instruments.

[0012] Moreover, appropriate measurement surfaces of the projection system (projection lens) for measuring the optically effective surface cannot be approached or accessed by appropriate measuring instruments (such as coordinate measuring ma¬ chines) in the assembled state of the lithography apparatus as found during operation.

[0013] Against this background, a problem addressed by the present invention is that of providing an improved method for replacing a first module with a second module of a lithography apparatus,

[0014] Accordingly, a method for replacing a first module with a second module of a lithography apparatus is proposed. The method includes the steps of:

[0015] a) measuring a first actual position of a reference body with the aid of a measuring device,

[0016] b) measuring an actual position of the first module with the aid of the meas¬ uring device, disassembling the first module and assembling the second module on the basis of the measured actual position of the first module,

[0017] c) measuring a second actual position of the reference body with the aid of the measuring device, and

[0018] d) ascertaining whether the measured second actual position deviates from the measured first actual position of the reference body.

[0019] The method can be used to check a reliability (e.g. measurement stability) of the measuring device used for calibration purposes when the first module is replaced with the second module. In particular, a target position for the second module is determined in step b) on the basis of the actual position of the first module detected with the aid of the measuring device. Since the first actual position of the reference body before the modules are swapped and the second actual position of the reference body after the modules are swapped are also measured by using the same measuring device, the reliability (e.g. measurement stability) of the measuring de¬ vice can be checked on the basis of the reference body as an absolute reference.Carl Zeiss SMT GmbH

[0020] 3

[0021] This stability check is based on the fact that it is not possible for the reference body to have changed while the modules are being swapped. Consequently, the first actual position of the reference body before the swap and the second actual position of the reference body after the swap must also correspond to each other within the limits of measurement accuracy. A deviation of the second actual position from the first actual position of the reference body indicates a measurement instability of the measuring device and hence indicates an undesired influence on the measure¬ ment in step b).

[0022] Steps a), b) and c) are performed using one and the same measuring device in particular.

[0023] The proposed stability check can be performed using a comparatively simple measurement technique, which in particular can also be used at a production fa¬ cility, for instance a semiconductor factory.

[0024] In particular, steps a) to d) can be performed at an operating site of the lithography apparatus, e.g. at a production site and / or in a semiconductor factory.

[0025] The method can be used to easily identify unreliability (e.g. insufficient measure¬ ment stability) of the measuring device immediately after the modules have been swapped. In particular, this is an advantage over the prior art (e.g. in DE 10 2021 201 026 A1), in which such unreliability (e.g. insufficient measurement stability) of the measuring device is only identified once the lithography apparatus has been put back into operation. Hence, the proposed method allows a position of the assembled second module to be corrected should unreliability of the measuring device have been ascertained with the aid of the reference body. In particular, the position of the second module can be corrected in this case before the lithography apparatus is put back into operation. Much time and effort is saved in comparison with the conventional method - should unreliability (e.g. insufficient measurement stabil¬ ity) of the measuring device be present.

[0026] For example, the lithography apparatus is an EUV or a DUV lithography apparatus. EUV stands for "extreme ultraviolet" and refers to a wavelength of the op¬ erating light in the range from 0.1 nm to 30 nm, in particular 13.5 nm. Furthermore, DUV stands for "deep ultraviolet" and refers to a wavelength of the operating light between 30 nm and 250 nm.

[0027] The EUV or DUV lithography apparatus comprises an illumination system and a projection system. In particular, using the EUV or DUV lithography apparatus,Carl Zeiss SMT GmbH

[0028] 4

[0029] the image of a mask (reticle) illuminated by means of the illumination system is projected by means of the projection system onto a substrate, for example a wafer (e.g. silicon wafer), which is coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection system, in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0030] For example, the first module and the second module are respective modules in the projection system of the lithography apparatus. However, the first module and the second module can also be e.g. respective modules in the illumination system of the lithography apparatus.

[0031] For example, the first module and the second module are respective optics mod¬ ules (optical modules). However, the first module and the second module can for example also be a (e.g. purely) mechanical module. Hereinafter, the first module and the second module are usually described by way of example as first and second optics modules. However, this does not represent any limitation to a respective optics module. Rather - even if not explicitly stated - the first module and the second module may also be respective mechanical modules.

[0032] A respective optics module (i.e. the first optics module and the second optics mod¬ ule) preferably comprises a holding frame and an optical element held therein. For example, the optical element is a mirror, a lens element, a waveplate, an optical grating or any other optical element. In the simplest case, the optics module could also comprise the optical element on its own without a holding frame. In particular, the corresponding optical element comprises an optically effective surface and an optical axis.

[0033] For example, the optical element in the first optics module and the second optics module is a respective non-actuatable (i.e. non-actuated) optical element. The position of an actuatable (i.e. actuated) optical element (in particular the position of its optically effective surface) can be changed with the aid of actuators (e.g. adjustable in up to six degrees of freedom) even after said element has been assembled in the lithography apparatus. By contrast, the position of a non-actuatable optical element (in particular the position of its optically effective surface) can no longer be corrected retrospectively (without changing the assembly position) after said element has been assembled in the lithography apparatus. In other examples, the first module and the second module may also be respective non-actuatable mechanical modules - rather than non-actuatable optics modules.Carl Zeiss SMT GmbH

[0034] 5

[0035] In this respect, the first optics module and the second optics module are similar to each other in that they are configured to cause the same optical effect within the lithography apparatus (e.g. within the projection system). Should the first module and the second module accordingly be a first mechanical module and a second mechanical module, then the first mechanical module and the second me¬ chanical module are for example similar to each other inasmuch as they are configured to cause the same functional (e.g. mechanical) effect within the lithogra¬ phy apparatus (e.g. within the projection system).

[0036] In step b), the first (old) module is replaced with the second (new) module. The first module may also be referred to as module to be replaced and / or as swap-out module. Furthermore, the second module may also be referred to as module to be installed and / or as swap -in module. Moreover, the actual position of the first module measured in step b) may be referred to as pre-swap position. Furthermore, an actual position of the second module after the second module has been installed may be referred to as post-swap position.

[0037] For example, a first optics module is replaced with a second optics module in such a way in step b) that the optically effective surface and / or the optical axis of the second optics module (i.e. of its optical element) is / are arranged in the same position or identically aligned as was the case in the first optics module.

[0038] Should the first module and the second module accordingly be a first mechanical module and a second mechanical module, then the first module is replaced with the second module e.g. in such a way in step b) that a functional element (e.g. a punctiform, linear and / or areal functional element) of the second mechanical module is arranged in the same position or identically aligned as was the case in the first mechanical module.

[0039] In particular, a target position of the second module is ascertained on the basis of the measured actual position of the first module when the second module is as¬ sembled on the basis of the measured actual position of the first module. There¬ upon, the second module is assembled in accordance with the ascertained target position.

[0040] In particular, the reference body is a mechanical component. In particular, the reference body is not an optical component. For example, the reference body is a block, e.g. a hollow block, monolithic block and / or solid block. The reference body is made e.g. of aluminium purely by way of example. However, the reference body may also be made of a material other than aluminium.Carl Zeiss SMT GmbH

[0041] 6

[0042] In particular, the reference body is not part of the lithography apparatus. Instead, the reference body is only used for absolute adjustment purposes when the modules are swapped.

[0043] In particular, the reference body has an external shape which imitates, i.e. corre¬ sponds to, an external shape of at least a part of the lithography apparatus, e.g. at least a part of the projection system in the lithography apparatus (e.g. at least a part of the first module). Herein, the external shape means a geometric external shape. In the present case, to imitate means that the external shape of the reference body corresponds to the external shape of at least a part of the lithography apparatus.

[0044] For example, the reference body has an external shape that imitates an external shape of the first module, at least in relation to multiple measurement surfaces of the first module, and / or an external shape of a sensor frame, at least in relation to multiple further measurement surfaces of the sensor frame.

[0045] The first position of the reference body is measured with the aid of the measuring device in step a). A position and / or pose of a first coordinate system of the reference body can also be said to be measured relative to a second coordinate system of the reference body with the aid of the measuring device in step a).

[0046] Moreover, the actual position of the first module is measured with the aid of the measuring device in step b). A position and / or pose of a first coordinate system of the lithography apparatus (in particular of a coordinate system of the first module) can also be said to be measured relative to a second coordinate system of the lithography apparatus (e.g. of a coordinate system of a sensor frame in the lithography apparatus) in step b).

[0047] Subsequently, the second position of the reference body is measured with the aid of the measuring device in step c). In particular, a position and / or pose of the first coordinate system of the reference body is measured relative to the second coordi¬ nate system of the reference body with the aid of the measuring device in step c). In the case of a reliable or stable measuring device, the same position of the reference body as in step a) should be measured in step c). A deviation from the position of the reference body measured in step a) can be measured in step c) in the case of an unreliable or unstable measuring device.

[0048] In particular, one and the same measuring device is used in steps a), b) and c).Carl Zeiss SMT GmbH

[0049] 7

[0050] The measuring device comprises e.g. multiple sensors. Purely by way of example, the measuring device comprises six sensors or twelve sensors. For example, the sensors are sensors for measuring distance and / or for measuring length. For example, the sensors are configured to measure a distance between a respective sensor and the respective measurement object (e.g. on a corresponding measure¬ ment surface of the measurement object). In the present case, the respective measurement object is the reference body in steps a) and c) and the first module in step b). For example, the sensors comprise tactile sensors and / or contactless sensors. For example, the contactless sensors comprise capacitive sensors, induc¬ tive sensors, optical sensors and / or interferometers.

[0051] For example, whether the measured second actual position deviates from the measured first actual position of the reference body by more than a threshold value ascertained in advance is ascertained in step d). For example, the threshold value ascertained in advance is ascertained on the basis of a measurement accuracy of the measuring device.

[0052] According to an embodiment:

[0053] a position of measurement reference surfaces of the reference body relative to further measurement reference surfaces of the reference body is measured with the aid of the measuring device in step a) as the first actual position of the reference body,

[0054] a position of measurement surfaces of the first module relative to further measurement surfaces of the lithography apparatus (e.g. of a sensor frame in the lithography apparatus) is measured with the aid of the measuring device in step b) as the actual position of the first module, and / or

[0055] a position of the measurement reference surfaces of the reference body rela¬ tive to the further measurement reference surfaces of the reference body is meas¬ ured with the aid of the measuring device in step c) as the second actual position of the reference body.

[0056] In particular, the measurement reference surfaces of the reference body span a first coordinate system of the reference body. Moreover, the further measurement reference surfaces of the reference body span a second coordinate system of the reference body. Moreover, a position and / or pose of the first coordinate system of the reference body is ascertained relative to the second coordinate system of the reference body in each of steps a) and c).Carl Zeiss SMT GmbH

[0057] 8

[0058] Moreover, the measurement surfaces of the first module span a first coordinate system of the lithography apparatus. Additionally, the further measurement surfaces of the lithography apparatus span a second coordinate system of the lithography apparatus. Furthermore, a position and / or pose of the first coordinate system of the lithography apparatus is ascertained relative to the second coordinate system of the lithography apparatus in step b).

[0059] According to a further embodiment, the method includes the following steps should the measured second actual position be ascertained in step d) as deviating from the measured first actual position of the reference body:

[0060] ascertaining a deviation of the measured second actual position from the measured first actual position of the reference body, and

[0061] correcting a position of the second module on the basis of the ascertained de¬ viation.

[0062] In this way, the position of the second module can be corrected on the basis of the repeated measurement of the reference body. In particular, a second target position of the second module is reconstructed and / or ascertained on the basis of the ascertained deviation. In that case, the second module is newly assembled and / or the existing assembly is corrected in accordance with the second target position. Consequently the reference body allows provision of an absolute adjustment for the case where the relative adjustment with the aid of the measuring device is incorrect.

[0063] In particular, the deviation of the measured second actual position from the measured first actual position of the reference body corresponds to a measure¬ ment error of the measuring device. An adjustment concept can be ascertained therewith. Hence the second (corrected) target position of the second module can be ascertained on the basis of the adjustment concept.

[0064] According to a further embodiment:

[0065] the measuring device is secured to the reference body in step a) before the first actual position of the reference body is measured with the aid of the measuring device,

[0066] the measuring device is secured to the lithography apparatus, in particular to a sensor frame of the lithography apparatus, in step b) before the actual position of the first module is measured, and / or

[0067] the measuring device is secured to the reference body in step c) before the second actual position of the reference body is measured with the aid of the measuring device.Carl Zeiss SMT GmbH

[0068] 9

[0069] The measuring device is secured, in particular in releasable fashion, to the lithog¬ raphy apparatus, e.g. the sensor frame of the lithography apparatus, or to the reference body in steps a) to c). Moreover, the measuring device is released from the reference body for example after step a) and / or after step c). Furthermore, the measuring device is released from the lithography apparatus, e.g. the sensor frame, for example after step b).

[0070] In the present case, secured in releasable fashion comprises being screwed on, for example, or any other manner of securing in redetachable fashion.

[0071] The sensor frame of the lithography apparatus is e.g. a sensor frame of the pro¬ jection system in the lithography apparatus. The sensor frame usually comprises a sensor device for measuring a current position of one or more (e.g. optical) components of the lithography apparatus relative to the sensor frame. The sensor frame is for example mounted so as to be vibration-decoupled from a force frame of the lithography apparatus. The sensor device comprises e.g. one or more sensors, for example interferometers and / or other measuring equipment for detect¬ ing a position of optical components in the lithography apparatus, e.g. in the projection system of the lithography apparatus. The optical components may for example comprise reflector elements for reflecting a light (e.g. laser light) transmit¬ ted by the sensors of the sensor frame. For example, the one or more sensors serve to detect a position of each of the optical components in six degrees of freedom.

[0072] To the extent that the present application relates to six degrees of freedom, this refers to degrees of freedom in relation to a movement in space. The six degrees of freedom comprise three translational degrees of freedom and three rotational degrees of freedom. The three translational degrees of freedom are degrees of freedom in relation to three spatial directions which span a three-dimensional space. The three translational degrees of freedom are for example degrees of free¬ dom in relation to three mutually perpendicular spatial directions. The three ro¬ tational degrees of freedom relate accordingly to a rotation about the three spatial directions.

[0073] According to a further embodiment, the reference body is provided adjacent to the lithography apparatus before step a) and / or is removed again from the region of the lithography apparatus after step c).Carl Zeiss SMT GmbH

[0074] 10

[0075] For example, the reference body is arranged adjacent to the lithography apparatus, e.g. adjacent to a projection system in the lithography apparatus, before step a). For example, the reference body is arranged at a predetermined location adjacent to the lithography apparatus before step a) and remains at this predetermined location during steps a) to c) or a) to d). For example, the reference body may be provided adjacent to the lithography apparatus for the process of swapping the modules (e.g. optics modules) only.

[0076] According to a further embodiment, the first module comprises multiple measure¬ ment surfaces which are measured with the aid of the measuring device in step b). Moreover, the reference body has an external shape which imitates an external shape of the first module at least in relation to the multiple measurement surfaces such that the reference body has multiple measurement reference surfaces which correspond to the multiple measurement surfaces of the first module. Furthermore, the multiple measurement reference surfaces of the reference body are measured with the aid of the measuring device in each of steps a) and c).

[0077] That is to say, the reference body is designed in such a way in relation to its external shape that it reproduces the pose of the measurement surfaces of the first module (e.g. the pose of the measurement surfaces of the first module relative to one another). For example, the reference body has a corresponding measurement reference surface assigned to each measurement surface of the first module.

[0078] Apart from the measurement reference surfaces which correspond to the meas¬ urement surfaces of the first module (and optional further measurement reference surfaces which are described below and correspond to measurement surfaces of a sensor frame of the lithography apparatus), the external shape of the reference body may be as desired.

[0079] According to a further embodiment, in step b), the measuring device is secured to a sensor frame of the lithography apparatus, the sensor frame has multiple further measurement surfaces, and the actual position of the first module is meas¬ ured relative to an actual position of the sensor frame.

[0080] In this embodiment, the measuring device for example comprises twelve sensors, six of which serve to measure the first module in six degrees of freedom and six of which serve to measure the sensor frame in six degrees of freedom.

[0081] In other embodiments, stops for arranging the measuring device on the lithogra¬ phy apparatus may also be provided on the lithography apparatus. In particular,Carl Zeiss SMT GmbH

[0082] 11

[0083] the stops may be configured such that they provide accurate positioning of the measuring device on the lithography apparatus in six degrees of freedom. In this case, it may be sufficient for the measuring device to only comprise a total of six sensors for measuring the first module in six degrees of freedom.

[0084] According to a further embodiment, the external shape of the reference body imitates the external shape of the first module, at least in relation to the multiple measurement surfaces, and an external shape of the sensor frame, at least in re¬ lation to the multiple further measurement surfaces, such that the reference body has the multiple measurement reference surfaces which correspond to the multiple measurement surfaces of the first module and multiple further meas¬ urement reference surfaces which correspond to the multiple further measure¬ ment surfaces of the sensor frame. Moreover, the multiple measurement reference surfaces and the multiple further measurement reference surfaces of the ref¬ erence body are measured with the aid of the measuring device in each of steps a) and c).

[0085] Therewith, a pose of the measurement reference surfaces of the reference body can be detected relative to a pose of the further measurement reference surfaces of the reference body in both step a) and step c). Moreover, a pose of the measurement surfaces of the first module is detected relative to a pose of the further measurement surfaces of the sensor frame in step b). This allows provision of a comparable relative measurement, once of the reference body and once of the first module. For this reason, tolerances due to a reassembly and / or movement of the measuring device from the reference body to the lithography apparatus, e.g. to the first module, and back to the reference body again play no role.

[0086] According to a further embodiment, the reference body has multiple measure¬ ment reference surfaces which correspond to measurement surfaces of the first module and / or multiple further measurement reference surfaces which corre¬ spond to further measurement surfaces of a sensor frame of the lithography ap¬ paratus. Furthermore, measurement reference data relating to the multiple measurement reference surfaces and / or further measurement reference data re¬ lating to the multiple further measurement reference surfaces of the reference body are provided before step a). Then, a potential deviation of the measured second actual position from the measured first actual position of the reference body is ascertained in step d) on the basis of the measurement reference data and / or the further measurement reference data.Carl Zeiss SMT GmbH

[0087] 12

[0088] That is to say, the reference body is inherently measured prior to its use when the modules are swapped. For example, the reference body is measured with the aid of a coordinate measuring machine. The measurement reference data relating to the multiple measurement reference surfaces in particular include a position of the multiple measurement reference surfaces with respect to one another. Moreover, the further measurement reference data relating to the multiple further measurement reference surfaces in particular include a position of the multiple further measurement reference surfaces with respect to one another.

[0089] According to a further embodiment, the first module and the second module correspondingly comprise a first optics module and a second optics module. Moreo¬ ver, the first optics module and the second optics module each comprise a holding frame and, assembled thereon, an optical element with an optical axis. Furthermore, in step b), the actual position of the holding frame of the first optics module is measured with the aid of the measuring device, and the second optics module is assembled on the basis of the measured actual position of the holding frame of the first optics module.

[0090] The measurement on the holding frame is simple and can make use of measure¬ ment surfaces already available for measuring the optically effective surface (so-called figure measurement) of the optical element.

[0091] According to a further embodiment, measurement data relating to a pose of the optical axis relative to the holding frame respectively in the first optics module and in the second optics module are provided. Moreover, the second optics module is assembled in step b) on the basis of the measured actual position of the holding frame of the first optics module, with the aid of the measuring device and on the basis of the measurement data relating to the pose of the optical axis in the first and second optics modules.

[0092] The data set is expanded and hence the positioning and alignment of the second optical module becomes more precise with the aid of the measurement data relating to the pose of the optical axis relative to the holding frame of the first optics module and relating to the pose of the optical axis relative to the holding frame of the second optics module.

[0093] In embodiments, the position of the second optics module, e.g. the actual position of the holding frame of the second optics module, is measured with the aid of the measuring device in step b) when assembling the second optics module.Carl Zeiss SMT GmbH

[0094] 13

[0095] Furthermore, the second optics module is assembled on the basis of the measured actual positions of the first optics module and the second optics module.

[0096] According to a further embodiment, the actual position of the first module is measured in six degrees of freedom in step b). Furthermore, the assembly of the second module in step b) comprises aligning the second module in six degrees of freedom on the basis of the actual position of the first module determined in six degrees of freedom.

[0097] According to a further embodiment, the first actual position and the second ac¬ tual position of the reference body are each measured in six degrees of freedom with the aid of the measuring device in steps a) and c). Moreover, the ascertainment of the deviation of the measured second actual position from the measured first actual position of the reference body comprises ascertaining a deviation in relation to the six degrees of freedom. Moreover, the position of the second mod¬ ule is corrected on the basis of the ascertained deviation in six degrees of free¬ dom.

[0098] According to a further embodiment, the assembly of the second module in step b) and / or the correction of the position of the second module on the basis of the as¬ certained deviation comprises aligning the second module using spacers.

[0099] The spacers comprise e.g. shims, plates or other suitable spacers. The spacers are made e.g. of metal and / or ceramic.

[0100] According to a further embodiment, the first module and the second module each comprise a mirror, and / or the first module and the second module are each as¬ sembled on an external side of the lithography apparatus and / or the projection optics unit thereof.

[0101] According to a further embodiment, the method includes the following steps be¬ fore step a):

[0102] assembling the first module on the lithography apparatus,

[0103] operating the lithography apparatus, in particular for exposing wafers, and ascertaining that replacing the first module with the second module is re¬ quired.

[0104] According to a further aspect, a controller is proposed, the latter being configured to carry out at least a part of the method. The controller for example comprises a first ascertainment unit for ascertaining a first target position of the secondCarl Zeiss SMT GmbH

[0105] 14

[0106] module on the basis of the measured actual position of the first module. The controller for example comprises a second ascertainment unit for ascertaining whether the measured second actual position of the reference body deviates from the measured first actual position of the reference body. The second ascertainment unit may also be configured to ascertain a deviation of the second actual position of the reference body from the first actual position of the reference body. The second ascertainment unit may also be configured to ascertain a second target position of the second module on the basis of the ascertained deviation.

[0107] The features and properties described for the method apply correspondingly, mutatis mutandis, to the controller.

[0108] " A(n) / one" should not necessarily be understood as a restriction to exactly one ele¬ ment in the present case. Rather, multiple elements, for example two, three or more, may also be provided. Any other numeral used here should also not be understood as a restriction to exactly the stated number of elements. Rather, unless indicated otherwise, numerical deviations upward and downward are possible.

[0109] Further possible implementations of the invention also comprise combinations, not explicitly mentioned, of features or embodiments described hereinabove or hereinafter with regard to the exemplary embodiments. A person skilled in the art will also add individual aspects as improvements or supplementations to the respective basic form of the invention.

[0110] Further advantageous configurations and aspects of the invention are the subject of the dependent claims and of the exemplary embodiments of the invention that are described hereinafter. The invention will be explained in more detail hereinafter on the basis of preferred embodiments with reference to the appended fig¬ ures.

[0111] Fig. 1 shows a schematic meridional section of a projection exposure apparatus for EUV projection lithography according to one embodiment;

[0112] Fig. 2 shows a part of an optical system of the projection exposure apparatus from Fig. 1 according to one embodiment;

[0113] Fig. 3 shows a flowchart of a method for replacing a first optics module with a second optics module in the optical system from Fig. 2 according to one embodi¬ ment; andCarl Zeiss SMT GmbH

[0114] 15

[0115] Fig. 4 shows a reference body according to one embodiment for performing an ab¬ solute adjustment in the method from Fig. 3.

[0116] In the figures, identical or functionally identical elements have been provided with the same reference signs, unless indicated otherwise. It should also be noted that the illustrations in the figures are not necessarily true to scale.

[0117] Fig. 1 shows an embodiment of a projection exposure apparatus 1 (lithography apparatus), in particular an EUV lithography apparatus. An embodiment of an illumination system 2 of the projection exposure apparatus 1 has, in addition to a light or radiation source 3, an illumination optics unit 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 may also be provided as a module separate from the rest of the illumination system 2. In this case, the illumination system 2 does not comprise the light source 3.

[0118] A reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reti¬ cle holder 8. The reticle holder 8 is displaceable by way of a reticle displacement drive 9, in particular in a scanning direction.

[0119] Fig. 1 depicts, by way of elucidation, a Cartesian coordinate system with an x-di-rection x, a ydirection y and a z-direction z. The x-direction x runs perpendicularly into the plane of the drawing. The ydirection y runs horizontally, and the z-direction z runs vertically. The scanning direction runs in the ydirection y in Fig. 1. The z-direction z runs perpendicularly to the object plane 6.

[0120] The projection exposure apparatus 1 comprises a projection optics unit 10. The projection optics unit 10 is used to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 extends parallel to the object plane 6. Alternatively, an angle between the object plane 6 and the image plane 12 that differs from 0° is also possible.

[0121] A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable by way of a wafer displacement drive 15, in particular in the ydirection y. The displacement, firstly, of the reticle 7 by way of the reticle displacement drive 9 and, secondly, of the wafer 13 by way of the wafer displacement drive 15 may be mutually synchronized.Carl Zeiss SMT GmbH

[0122] 16

[0123] The light source 3 is an EUV radiation source. The light source 3 emits in partic¬ ular EUV radiation 16, which is also referred to below as used radiation, illumination radiation or illumination light. The used radiation 16 has in particular a wavelength in the range between 5 nm and 30 nm. The light source 3 may be a plasma source, for example an LPP (laser produced plasma) source or a GDPP (gas discharge produced plasma) source. It may also be a synchrotron-based radiation source. The light source 3 may be a free electron laser (FEL).

[0124] The illumination radiation 16 emanating from the light source 3 is focused by a collector 17. The collector 17 may be a collector having one or more ellipsoidal and / or hyperboloidal reflection surfaces. The illumination radiation 16 may be incident on the at least one reflection surface of the collector 17 with grazing inci¬ dence (Gl), i.e. at angles of incidence of greater than 45°, or with normal inci¬ dence (Nl), i.e. at angles of incidence of less than 45°. The collector 17 may be structured and / or coated, firstly to optimize its reflectivity for the used radiation and secondly to suppress extraneous light.

[0125] Downstream of the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 may represent a separation between a radiation source module, having the light source 3 and the collector 17, and the illumination optics unit 4.

[0126] The illumination optics unit 4 comprises a deflection mirror 19 and, arranged downstream thereof in the beam path, a first facet mirror 20. The deflection mirror 19 may be a planar deflection mirror or alternatively a mirror with a beaminfluencing effect that goes beyond the pure deflection effect. In addition to that or in an alternative, the deflection mirror 19 may be embodied as a spectral filter that separates a used light wavelength of the illumination radiation 16 from extraneous light of a wavelength deviating therefrom. If the first facet mirror 20 is arranged in a plane of the illumination optics unit 4 that is optically conjugate to the object plane 6 as a field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a multiplicity of individual first facets 21, which can also be referred to as field facets. Only some of these first facets 21 are illustrated in Fig. 1 by way of example.

[0127] The first facets 21 may be embodied as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partly circular edge contour. The first facets 21 may take the form of planar facets or alternatively convexly or concavely curved facets.Carl Zeiss SMT GmbH

[0128] 17

[0129] As is known from DE 102008009600 Al, for example, the first facets 21 themselves may each also be composed of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. The first facet mirror 20 may in particular take the form of a microelectromechanical system (MEMS system). For details, reference is made to DE 102008009600 Al.

[0130] The illumination radiation 16 travels horizontally, i.e. in the ydirection y, be¬ tween the collector 17 and the deflection mirror 19.

[0131] In the beam path of the illumination optics unit 4, a second facet mirror 22 is arranged downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optics unit 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged at a dis¬ tance from a pupil plane of the illumination optics unit 4. In this case, the combi¬ nation of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 Al, EP 1614008 Bl and US 6,573,978.

[0132] The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

[0133] The second facets 23 may likewise be macroscopic facets, which can for example have a round, rectangular or else hexagonal boundary, or can alternatively be facets composed of micromirrors. In this regard, reference is likewise made to DE 10 2008009600 Al.

[0134] The second facets 23 may have planar or alternatively convexly or concavely curved reflection surfaces.

[0135] The illumination optics unit 4 thus forms a doubly faceted system. This funda¬ mental principle is also referred to as a fly's eye integrator.

[0136] It may be advantageous to arrange the second facet mirror 22 not exactly in a plane that is optically conjugate to a pupil plane of the projection optics unit 10. In particular, the second facet mirror 22 may be arranged so as to be tilted in re¬ lation to a pupil plane of the projection optics unit 10, as described for example in DE 102017220586 Al.

[0137] The second facet mirror 22 is used to image the individual first facets 21 into the object field 5. The second facet mirror 22 is the last beam-shaping mirror or elseCarl Zeiss SMT GmbH

[0138] 18

[0139] actually the last mirror for the illumination radiation 16 in the beam path upstream of the object field 5.

[0140] In a further embodiment (not illustrated) of the illumination optics unit 4, a transfer optics unit contributing in particular to the imaging of the first facets 21 into the object field 5 may be arranged in the beam path between the second facet mirror 22 and the object field 5. The transfer optics unit may comprise exactly one mirror, or alternatively two or more mirrors arranged one behind another in the beam path of the illumination optics unit 4. The transfer optics unit may in particular comprise one or two normal-incidence mirrors (NI mirrors) and / or one or two grazing-incidence mirrors (GI mirrors).

[0141] In the embodiment shown in Fig. 1, the illumination optics unit 4 has exactly three mirrors downstream of the collector 17, specifically the deflection mirror 19, the first facet mirror 20 and the second facet mirror 22.

[0142] In another embodiment of the illumination optics unit 4, the deflection mirror 19 may also be omitted, and so the illumination optics unit 4 can then have exactly two mirrors downstream of the collector 17, specifically the first facet mirror 20 and the second facet mirror 22.

[0143] The imaging of the first facets 21 into the object plane 6 by means of the second facets 23, or using the second facets 23 and a transfer optics unit, is generally only approximate imaging.

[0144] The projection optics unit 10 comprises a plurality of mirrors Mi, which are consecutively numbered in accordance with their arrangement in the beam path of the projection exposure apparatus 1.

[0145] In the example illustrated in Fig. 1, the projection optics unit 10 comprises six mirrors Ml to M6. Alternatives with four, eight, ten, twelve or any other number of mirrors Mi are likewise possible. The projection optics unit 10 is a doubly ob¬ scured optical unit. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics unit 10 has an image-side numerical aperture that is greater than 0.5 and may also be greater than 0.6 and may be, for example, 0.7 or 0.75.

[0146] Reflection surfaces of the mirrors Mi may take the form of free-form surfaces without an axis of rotational symmetry. Alternatively, the reflection surfaces of the mirrors Mi may be designed as aspherical surfaces with exactly one axis ofCarl Zeiss SMT GmbH

[0147] 19

[0148] rotational symmetry of the reflection surface shape. Just like the mirrors of the illumination optics unit 4, the mirrors Mi may have highly reflective coatings for the illumination radiation 16. These coatings may be designed as multilayer coat¬ ings, in particular with alternating layers of molybdenum and silicon.

[0149] The projection optics unit 10 has a large object-image shift in the ydirection y between a ycoordinate of a centre of the object field 5 and a ycoordinate of the centre of the image field 11. This object-image offset in the ydirection y can be of ap¬ proximately the same magnitude as a z-distance between the object plane 6 and the image plane 12.

[0150] The projection optics unit 10 may in particular have an anamorphic form. In particular, it has different imaging scales Bx, By in the x-direction x and ydirection y. The two imaging scales Bx, By of the projection optics unit 10 are preferably (Bx, By) = (+ / -0.25, + / -0.125). A positive imaging scale B means imaging without image inversion. A negative sign for the imaging scale B means imaging with image inversion.

[0151] The projection optics unit 10 consequently leads to a reduction in size with a ratio of 4'1 in the x-direction x, i.e. in a direction perpendicular to the scanning direc¬ tion.

[0152] The projection optics unit 10 leads to a reduction in size of 8H in the ydirection y, i.e. in the scanning direction.

[0153] Other imaging scales are likewise possible. Imaging scales with the same sign and the same absolute value in the x-direction x and ydirection y are also possible, for example with absolute values of 0.125 or of 0.25.

[0154] The number of intermediate image planes in the x-direction x and in the ydirec¬ tion y in the beam path between the object field 5 and the image field 11 may be the same or may differ, depending on the design of the projection optics unit 10. Examples of projection optics units with different numbers of such intermediate images in the x-direction x and the ydirection y are known from US 2018 / 0074303 Al.

[0155] In each case, one of the second facets 23 is assigned to exactly one of the first facets 21 in order to form a respective illumination channel for illuminating the ob¬ ject field 5. This may in particular produce illumination according to the Kohler principle. The far field is decomposed into a multiplicity of object fields 5 usingCarl Zeiss SMT GmbH

[0156] 20

[0157] the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 respectively assigned to them.

[0158] The first facets 21 are each imaged onto the reticle 7 by an assigned second facet 23 with images overlaid over one another for the purpose of illuminating the ob¬ ject field 5. The illumination of the object field 5 is in particular as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by overlaying different illumination channels.

[0159] An arrangement of the second facets 23 may geometrically define the illumina¬ tion of the entrance pupil of the projection optics unit 10. The intensity distribution in the entrance pupil of the projection optics unit 10 may be set by selecting the illumination channels, in particular the subset of the second facets 23 that guide light. This intensity distribution is also referred to as illumination setting or illumination pupil filling.

[0160] A likewise preferred pupil uniformity in the region of portions of an illumination pupil of the illumination optics unit 4 that are illuminated in a defined manner can be achieved by a redistribution of the illumination channels.

[0161] Further aspects and details of the illumination of the object field 5 and in partic¬ ular of the entrance pupil of the projection optics unit 10 are described below.

[0162] The projection optics unit 10 may have in particular a homocentric entrance pupil. The latter may be accessible. It may also be inaccessible.

[0163] The entrance pupil of the projection optics unit 10 regularly cannot be exactly il¬ luminated with the second facet mirror 22. In the case of imaging by the projec¬ tion optics unit 10 that telecentrically images the centre of the second facet mirror 22 onto the wafer 13, the aperture rays often do not intersect at a single point. However, it is possible to find an area in which the spacing of the aperture rays that is determined in pairs becomes minimal. This area is the entrance pupil or an area conjugate thereto in real space. In particular, this area exhibits a finite curvature.

[0164] It may be the case that the projection optics unit 10 has different poses of the entrance pupil for the tangential beam path and for the sagittal beam path. In this case, an imaging element, in particular an optical component of the transfer optics unit, should be provided between the second facet mirror 22 and the reticle 7.Carl Zeiss SMT GmbH

[0165] 21

[0166] With the aid of this optical element, the different poses of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

[0167] In the arrangement of the components of the illumination optics unit 4 illus¬ trated in Fig. 1, the second facet mirror 22 is arranged in an area conjugate to the entrance pupil of the projection optics unit 10. The first facet mirror 20 is arranged so as to be tilted with respect to the object plane 6. The first facet mirror 20 is arranged so as to be tilted with respect to an arrangement plane defined by the deflection mirror 19. The first facet mirror 20 is arranged so as to be tilted with respect to an arrangement plane defined by the second facet mirror 22.

[0168] Fig. 2 schematically shows a part of an optical system 100 according to an embodiment in a vertical section. For example, the optical system 100 is the projection optics unit 10 from Fig. 1. The optical system 100 comprises at least one optical component 102. By way of example, the optical component is described below as a mirror module 102 with the mirror M5 of the projection optics unit 10 from Fig. 1. However, the embodiments described below and the method described be¬ low may also be applied to one or more other optical components of an optical system in a lithography apparatus. Moreover, the embodiments described below and the method described below may also be applied to one or more mechanical components of the optical system 100 in the lithography apparatus 1 - rather than optical components 102 - in other examples.

[0169] The example in Fig. 2 shows a region of the optical system 100, i.e. of the projec¬ tion optics unit 10 from Fig. 1, said region comprising the mirror module 102 with the mirror M5. The mirror module 102 also comprises a holding frame 104, in which the mirror M5 is held. The holding frame 104 secures the mirror M5 to a mechanical component 106, e.g. a sensor frame 108, of the optical system 100 (e.g. the projection optics unit 10).

[0170] Although not shown in Fig. 2, provision may also be made of a force frame, to which further optical components of the optical system 100 (e.g. the mirrors Ml to M4 and M6 in Fig. 1) are secured.

[0171] As shown in Fig. 2, the mirror M5 has an optically effective surface 110 and an optical axis 112.

[0172] In particular, the mirror M5 is provided in non-actuatable fashion. For example, this is in contrast to one or more of the other mirrors (e.g. the mirrors Ml to M4 and M6 in Fig. 1) in the optical system 100. The mirror M5 being provided inCarl Zeiss SMT GmbH

[0173] 22

[0174] non-actuatable fashion means, in particular, that the position of its optically effective surface 110, and hence of its optical axis 112, can no longer be adjusted with the aid of actuators, e.g. Lorenz actuators, after the optics module 102 has been installed in the optical system 100 (e.g. in the projection optics unit 10, Fig. 1).

[0175] For example, the optics module 102 is installed with the aid of screws (not shown), by means of which the optics module 102 is screwed to the mechanical component 106. In this case, spacers 114, e.g. shims, may be placed underneath in order to obtain a predefined target position of the optical axis 112 of the mirror M5.

[0176] For example in contrast to other mirrors in the optical system 100 (e.g. mirrors Ml to M4 and M6 in Fig. 1), the mirror M5 moreover is installed such that it is accessible from outside the optical system 100 (e.g. the projection optics unit 10). Hence the mirror M5 may be swapped if necessary. Such necessity arises, for example, if the mirror M5 loses optical alignment capability and / or has run through a predefined number of exposures or operating hours.

[0177] Replacing the old optics module 102 (the first optics module 102) with a new optics module 102' (a second optics module 102') is indicated by a double-headed arrow in Fig. 2. The second optics module 102' comprises a second holding frame 104', which holds a second optical element M5' (e.g. a second mirror M5'). The second mirror M5' has an optically effective surface 110' and an optical axis 112'.

[0178] When replacing the first optics module 102 with the second optics module 102', lack of actuatability of the mirror M5 means that it is necessary to ensure that, in the installed state of the mirror M5', the optical axis 112' of the new mirror M5' is positioned and aligned identically or virtually identically to the optical axis 112 of the old mirror M5 in the previously installed state of the mirror M5.

[0179] A method for replacing a first optics module 102 with a second optics module 102' in a lithography apparatus 1 is described below with reference to Fig. 3.

[0180] In a first step Si of the method, the first optics module 102 (Fig. 2) is measured (measurement data A) prior to the first assembly in the optical system 100 (e.g. prior to the first assembly of the optical system 100 itself). In particular, the pose of the optical axis 112 relative to the holding frame 104 is ascertained in the pro¬ cess, e.g. in six degrees of freedom. In particular, the six degrees of freedom comprise three translational degrees of freedom in the directions x, y, z and threeCarl Zeiss SMT GmbH

[0181] 23

[0182] rotational degrees of freedom Rx, Ry, Rzin relation to a rotation correspondingly about the directions x, y, z. For example, in step Si, the first optics module 102 is measured with the aid of a coordinate measuring machine (also referred to as CMM measurement) or else any other suitable piece of equipment.

[0183] For example, the first optics module 102, e.g. the holding frame 104 and / or a sub¬ strate of the mirror M5, comprises measurement surfaces 116. The pose of the op¬ tical axis 112 relative to the measurement surfaces 116 may thus be ascertained in step Si. In Fig. 2, two measurement surfaces 116 are shown by way of example and provided with a reference sign. However, the holding frame 104 and / or a sub¬ strate of the mirror M5 may also comprise more than two measurement surfaces 116, e.g. six measurement surfaces 116.

[0184] In a second step S2 of the method, the first optics module 102 is aligned with re¬ spect to and secured on the mechanical component 106, e.g. the sensor frame 108.

[0185] The alignment is performed in such a way that the optical axis 112 adopts a target position which was calculated and defined in advance so that the mirror M5 interacts suitably with the other mirrors (e.g. M1-M4 and M6, Fig. 1) in the opti¬ cal system 100. The alignment is implemented on the basis of the pose of the opti¬ cal axis 112 in relation to the holding frame 104 or in relation to the measure¬ ment surfaces 116 (Fig. 2) that is measured in step Si. Moreover, the pose of the measurement surfaces 116 of the first optics module 102 is measured relative to measurement surfaces 118 of the sensor frame 108. The sensor frame 108 is a frame which is mechanically decoupled from a force frame (not shown) of the li¬ thography apparatus 1. The sensor frame 108 carries sensors (not shown) used to measure the pose of one or more optical components of the lithography apparatus. The sensor frame 108 forms the spatial reference system of the optical sys¬ tem 100 (e.g. of the projection optics unit 10, Fig. 1).

[0186] Thus, the actual position of the optical axis 112 can be measured relative to the sensor frame 108 and can be compared with the target position of the optical axis 112. In order to match the target position and actual position of the optical axis 112, the position of the first optics module 102 is corrected with the aid of spacers 114.

[0187] As shown in Fig. 2, the first optics module 102 is for example assembled on an external side 120 of the lithography apparatus 1, e.g. of the optical system 100 (e.g. of the projection optics unit 10).Carl Zeiss SMT GmbH

[0188] 24

[0189] The lithography apparatus 1, including the optical system 100 (e.g. the projection optics unit 10), is put into operation in a third step S3 of the method. For example, semiconductor components are produced. After a certain number of expo¬ sures and / or operating hours, the mirror M5 has reached its end of life (EOL) and must be replaced by a new mirror M5'. For example, replacing the first optics module 102 having the mirror M5 with a second optics module 102' is ascertained as necessary in step S3.

[0190] In a fourth step S4 of the method - prior to the actual swap of the optics modules 102, 102' - a reference body 200 (Fig. 4) is provided and a self-measurement is performed.

[0191] For example, the reference body 200 is a block, e.g. a solid block or a hollow block. The reference body 200 has an external shape FR which imitates an external shape Fo of at least a part of the first optics module 102. In particular, the reference body 200 has an external shape FR which imitates the external shape Fo of the first optics module 102, at least in relation to the multiple measurement surfaces 116 of the first optics module 102. That is to say, the reference body 200 comprises multiple measurement reference surface 204 (two of which are shown in Fig. 4) which correspond to the multiple measurement surfaces 116 of the first optics mod¬ ule 102. For example, the first optics module 102 comprises six measurement surfaces 116, and the reference body 200 comprises six measurement reference surfaces 204 which, in relation to a position with respect to one another, correspond to the six measurement surfaces 116.

[0192] In addition, the reference body 200 may also have an external shape FR which imitates an external shape Fs of the sensor frame 108, at least in relation to the multiple further measurement surfaces 118. In particular, the reference body 200 may have multiple (e.g. six) further measurement reference surfaces 206 which corre¬ spond to the multiple (e.g. six) further measurement surfaces 118 of the sensor frame 108.

[0193] The position of the multiple measurement reference surfaces 204 relative to one another is measured in step S4, e.g. with the aid of a coordinate measuring ma¬ chine (ascertaining measurement reference data C). In the process, it is possible to ascertain whether the positions of the measurement reference surface 204 relative to one another correspond to target positions for the measurement reference surfaces 204. Should a deviation be ascertained here, the latter may be taken into account in steps S10, Sil.Carl Zeiss SMT GmbH

[0194] 25

[0195] The position of the multiple further measurement reference surfaces 206 relative to one another may also be measured in step S4, e.g. with the aid of a coordinate measuring machine (ascertaining measurement reference data D). In the process, it is possible to ascertain whether the positions of the measurement reference surfaces 204 relative to the positions of the further measurement reference surface 206 correspond to target positions for the measurement reference surfaces 204 and for the further measurement reference surfaces 206. A deviation ascertained in the process may also be taken into account in steps S10, Sil.

[0196] A first actual position PIIST of the reference body 200 is measured with the aid of a measuring device 300, as illustrated in Fig. 4, in a fifth step S5 of the method.

[0197] To this end, the reference body 200 is initially provided adjacent to the lithography apparatus 1, e.g. adjacent to the optical system 100. For example, the reference body 200 is provided at a predetermined location 202, where it remains e.g. during the subsequent steps S6 to S9 or S6 to S12.

[0198] Moreover, the measuring device 300 is provided in step S5. For example, the meas¬ uring device 300 is releasably secured to the reference body 200, as shown in Fig. 4. Purely by way of example, the measuring device 300 is screwed to the reference body 200 (screw 302).

[0199] Moreover, the multiple measurement reference surfaces 204 of the reference body 200 are measured with the aid of the measurement device 300 in step S5, e.g. in six degrees of freedom. Furthermore, the multiple further measurement reference surfaces 206 may also be measured with the aid of the measuring device 300, e.g. in six degrees of freedom. In particular, the measurement reference surfaces 204 span a first coordinate system of the reference body 200, and the further measurement reference surfaces 206 span a second coordinate system of the reference body 200. Furthermore, e.g. a pose of the first coordinate system is as¬ certained relative to the second coordinate system of the reference body 200 in step S5.

[0200] The actual position PIST of the first optics module 102 is measured with the aid of the measuring device 300 in a sixth step S6 of the method. To this end, the meas¬ uring device 300 used in step S5 for measuring the reference body 200 is provided on the lithography apparatus 1. For example, the measuring device 300 is se¬ cured to the lithography apparatus 1, e.g. to the sensor frame 108, as shown in Fig. 2.Carl Zeiss SMT GmbH

[0201] 26

[0202] The actual position PIST of the first optics module 102 is thereupon measured with the aid of the measuring device 300. For example, the actual position PIST of the first optics module 102 is measured in six degrees of freedom. In particular, this includes measuring a distance between the measuring device 300 and the first optics module 102 in the z-direction. For example, the z-direction substantially corresponds to a direction perpendicular to a main plane of extent of the optically effective surface 110 of the mirror M5 and / or to a vertical direction, i.e. op¬ posite to an acceleration of gravity. In a horizontal plane, the measuring device 300 measures the distance in the x-direction (shown in Fig. 2) and in the ydirec- tion (perpendicular to the plane of the drawing! not shown in Fig. 2). In particular, the actual position PIST of the first optics module 102 is measured by measuring the multiple measurement surfaces 116 with the aid of the measuring device 300.

[0203] The measuring device 300 can also measure the multiple further measurement surfaces 118 of the sensor frame 108. In that case, it is possible to measure the actual position PIST of the first optics module 102 relative to an actual position Ps, IST of the sensor frame 108. It can also be said that the measurement surfaces 116 span a first coordinate system of the lithography apparatus 1, and the further measurement surfaces 118 span a second coordinate system of the lithography apparatus 1. Furthermore, a pose of the first coordinate system is ascertained relative to the second coordinate system of the lithography apparatus 1 in step S6.

[0204] In a seventh step S7 of the method, the first optics module 102 is disassembled from the mechanical component 106, e.g. the sensor frame 108. However, the measuring device 300 remains in situ as it is used to measure the second optics module 102'.

[0205] The second optics module 102' is assembled in an eighth step S8 of the method. To this end, the second optics module 102' is initially provided (Fig. 2). In the pro¬ cess, measurement data B with respect to a pose of the optical axis 112' relative to the holding frame 104' of the second optics module 102' are also provided.

[0206] These measurement data B for the second optics module 102' are provided in a manner similar to the measurement data A for the first optics module 102.

[0207] Then, the second optics module 102' is assembled on the mechanical component 106, e.g. the sensor frame 108, on the basis of the measured actual position PIST of the first optics module 102. In particular, a target position PSOLL of the second optics module 102' is ascertained on the basis of the measured actual positionCarl Zeiss SMT GmbH

[0208] 27

[0209] PIST of the holding frame 104 of the first optics module 102 relative to the meas¬ uring device 300, the measurement data A relating to the pose of the optical axis 112 in the first optics module 102 and the measurement data B relating to the pose of the optical axis 112' in the second optics module 102'. Then, the second op¬ tics module 102' is assembled in accordance with the ascertained target position PSOLL. In particular, the measurement data A define the pose of the optical axis 112 of the first optics module 102 relative to the holding frame 104 of the first op¬ tics module 102. Furthermore, the measurement data B in particular define the pose of the optical axis 112' of the second optics module 102' relative to the holding frame 104' of the second optics module 102'.

[0210] Optionally, the position of the second optics module 102' in the installed state, e.g. the actual position of the holding frame 104' of the second optics module 102', may also be measured with the aid of the measuring device 300 in step S8. In particular, the second optics module 102' - like the first optics module 102 - comprises multi¬ ple measurement surfaces 116' (e.g. six measurement surfaces 116'), which are measured by the measuring device 300. In this case, the second optics module 102' is furthermore assembled on the basis of the measured actual positions of the first optics module and the second optics module 102, 102'.

[0211] The reference body 200 is measured again with the aid of the measuring device 300 (Fig. 4) in a ninth step S9 of the method. To this end, the measuring device 300 is provided on the reference body 200. For example, the measuring device is secured to the reference body 300, as shown in Fig. 4. Then, a second actual posi¬ tion P2IST of the reference body 200 is measured with the aid of the measuring device 300. The procedure is similar to step S5. In particular, a pose of the first coordinate system of the reference body 200 is also measured relative to the second coordinate system of the reference body 200 with the aid of the measuring device 300 in step S9. In the case of a reliable or stable measuring device 300, the same position P2IST of the reference body 200 as in step S5 should be measured in step S9. A deviation A from the position PIIST of the reference body 200 measured in step S5 can be measured in step S9 in the case of an unreliable or unstable measuring device 300.

[0212] Whether the second actual position P2IST of the reference body 200 deviates from the first actual position PIIST of the reference body 200 is ascertained in a tenth step S10 of the method.

[0213] Should the second actual position P2IST of the reference body 200 be ascertained as not deviating (e.g. within the scope of a measurement accuracy of theCarl Zeiss SMT GmbH

[0214] 28

[0215] measuring device 300) from the first actual position PIIST of the reference body 200 in step S10, then this confirms the reliability (e.g. measurement stability) of the measuring device 300. The second (new) optics module 102' is ascertained as having been assembled in the correct position PSOLL in this case.

[0216] A deviation A of the second actual position P2IST of the reference body 200 measured in step S9 from the first actual position PIIST of the reference body 200 measured in step S5 is ascertained, e.g. in six degrees of freedom, in an eleventh step Sil of the method. Further, the measurement reference data C, D relating to the reference body 200, provided in step S4, are for example taken into account in step Sil.

[0217] In particular, step Sil is carried out when the second actual position P2IST of the reference body 200 is ascertained as deviating from the first actual position PIIST of the reference body 200 (e.g. taking into account a measurement accuracy of the measuring device 300) in step S10. Since the reference body 200 cannot have changed, the ascertainment of the deviation A indicates an instability (e.g. measurement unreliability) of the measuring device 300. Since this measuring device 300 was also used when ascertaining the assembly position PSOLL for the second optics module 102', the assumption that can be made in this case is that the target position PSOLL for the assembly of the second optics module 102' has been ascertained incorrectly.

[0218] A position of the installed second optics module 102' is corrected, e.g. in six de¬ grees of freedom, on the basis of the deviation A ascertained in step Sil in a twelfth step S12 of the method. In particular, a second corrected target position PSOLL, K is ascertained on the basis of the deviation A in this step.

[0219] The reference body 200 and / or the measuring device 300 may be removed again from the region of the lithography apparatus 1, e.g. of the optical system 100, after any of steps S9, S10, Sil, S12.

[0220] If no deviation A is ascertained during the absolute adjustment with the aid of the reference body 200 in step S10, then an operation of the lithography apparatus 1 can be resumed with the new optics module 102' after step S10. If a deviation A is ascertained during the absolute adjustment with the aid of the reference body 200 in step S10, then the position of the new optics module 102' is initially corrected in S12. Subsequently, an operation of the lithography apparatus 1 can be resumed with the new optics module 102' after step S12.Carl Zeiss SMT GmbH

[0221] 29

[0222] Although the present invention has been described on the basis of exemplary embodiments, it may be modified in a variety of ways.Carl Zeiss SMT GmbH

[0223] 30 LIST OF REFERENCE SIGNS

[0224] 1 Projection exposure apparatus 2 Illumination system

[0225] 3 Light source

[0226] 4 Illumination optics unit

[0227] 5 Object field

[0228] 6 Object plane

[0229] 7 Reticle

[0230] 8 Reticle holder

[0231] 9 Reticle displacement drive

[0232] 10 Projection optics unit

[0233] 11 Image field

[0234] 12 Image plane

[0235] 13 Wafer

[0236] 14 Wafer holder

[0237] 15 Wafer displacement drive

[0238] 16 Illumination radiation

[0239] 17 Collector

[0240] 18 Intermediate focal plane

[0241] 19 Deflection mirror

[0242] 20 First facet mirror

[0243] 21 First facet

[0244] 22 Second facet mirror

[0245] 23 Second facet

[0246] 100 Optical system

[0247] 102, 102' Optics module

[0248] 104, 104' Holding frame

[0249] 106 Mechanical component

[0250] 108 Sensor frame

[0251] 110, 110' Optically effective surface 112, 112’ Optical axis

[0252] 114 Spacer

[0253] 116, 116' Measurement surface

[0254] 118 Measurement surface

[0255] 120 External side

[0256] 200 Reference body

[0257] 202 Location

[0258] 204 Measurement reference surface 206 Measurement reference surfaceCarl Zeiss SMT GmbH

[0259] 300 Measuring device

[0260] 302 Screw

[0261] A, B Measurement data

[0262] C, D Measurement reference dataΔ Deviation

[0263] Fo, FR, FS Shape

[0264] M1-M6, M5' Mirror

[0265] PlST Actual position

[0266] Ps, IST Actual position

[0267] PsOLL Target position

[0268] PsOLL, K Second corrected target position P1IST First actual position

[0269] P2IST Second actual position

[0270] S1-S12 Method step

[0271] x, y, z Direction

[0272] Rx, Ry, Rz Direction of rotation

Claims

Carl Zeiss SMT GmbH32CLAIMS1. Method for replacing a first module (102) with a second module (102') of a lithography apparatus (1), including the steps of:a) measuring (S5) a first actual position (P1IST) of a reference body (200) with the aid of a measuring device (300),b) measuring (S6) an actual position (PIST) of the first module (102) with the aid of the measuring device (300), disassembling (S7) the first module (102) and assembling (S8) the second module (102') on the basis of the measured actual position (PIST) of the first module (102),c) measuring (S9) a second actual position (P2IST) of the reference body (200) with the aid of the measuring device (300), andd) ascertaining (S10) whether the measured second actual position (P2IST) deviates from the measured first actual position (P1IST) of the reference body (200).

2. Method according to Claim 1, whereina position of measurement reference surfaces (204) of the reference body (200) relative to further measurement reference surfaces (206) of the reference body (200) is measured with the aid of the measuring device (300) in step a) as the first actual position (P1IST) of the reference body (200),a position of measurement surfaces (116) of the first module (102) relative to further measurement surfaces (118) of the lithography apparatus (1) is measured with the aid of the measuring device (300) in step b) as the actual position (PIST) of the first module (102), and / ora position of the measurement reference surfaces (204) of the reference body (200) relative to the further measurement reference surfaces (206) of the reference body (200) is measured with the aid of the measuring device (300) in step c) as the second actual position (P2IST) of the reference body (200).

3. Method according to Claim 1 or 2, wherein the method includes the follow¬ ing steps should the measured second actual position (P2IST) be ascertained in step d) as deviating from the measured first actual position (P1IST) of the reference body (200):ascertaining (S11) a deviation (Δ) of the measured second actual position (P2IST) from the measured first actual position (P1IST) of the reference body (200), andcorrecting (S12) a position of the second module (102') on the basis of the ascertained deviation (Δ).Carl Zeiss SMT GmbH334. Method according to any of Claims 1 to 3, whereinthe measuring device (300) is secured to the reference body (200) in step a) before the first actual position (P1IST) of the reference body (200) is measured with the aid of the measuring device (300),the measuring device (300) is secured to the lithography apparatus (1), in particular to a sensor frame (108) of the lithography apparatus (1), in step b) before the actual position (PIST) of the first module (102) is measured, and / or the measuring device (300) is secured to the reference body (200) in step c) before the second actual position (P2IST) of the reference body (200) is measured with the aid of the measuring device (300).

5. Method according to any of Claims 1 to 4, wherein the reference body (200) is provided adjacent to the lithography apparatus (1) before step a) and / or is removed again from the region of the lithography apparatus (1) after step c).

6. Method according to any of Claims 1 to 5, whereinthe first module (102) comprises multiple measurement surfaces (116) which are measured with the aid of the measuring device (300) in step b),the reference body (200) has an external shape (FR) which imitates an external shape (Fo) of the first module (102) at least in relation to the multiple measurement surfaces (116) such that the reference body (200) has multiple measure¬ ment reference surfaces (204) which correspond to the multiple measurement surfaces (116) of the first module (102), andthe multiple measurement reference surfaces (204) of the reference body (200) are measured with the aid of the measuring device (300) in each of steps a) and c).

7. Method according to any of Claims 1 to 6, wherein, in step b), the measuring device (300) is secured to a sensor frame (108) of the lithography apparatus (1), the sensor frame (108) has multiple further measurement surfaces (118), and the actual position (PIST) of the first module (102) is measured relative to an actual position (PS. IST) of the sensor frame (108).

8. Method according to Claim 6 and 7, whereinthe external shape (FR) of the reference body (200) imitates the external shape (Fo) of the first module (102), at least in relation to the multiple measurement surfaces (116), and an external shape (Fs) of the sensor frame (108), at least in relation to the multiple further measurement surfaces (118), such that the ref¬ erence body (200) has the multiple measurement reference surfaces (204) which correspond to the multiple measurement surfaces (116) of the first module (102)Carl Zeiss SMT GmbH34and multiple further measurement reference surfaces (206) which correspond to the multiple further measurement surfaces (118) of the sensor frame (108), and the multiple measurement reference surfaces (204) and the multiple further measurement reference surfaces (206) of the reference body (200) are each meas¬ ured with the aid of the measuring device (300) in steps a) and c).

9. Method according to any of Claims 1 to 8, whereinthe reference body (200) has multiple measurement reference surfaces (204) which correspond to measurement surfaces (116) of the first module (102) and / or multiple further measurement reference surfaces (206) which correspond to further measurement surfaces (118) of a sensor frame (108) of the lithography appa¬ ratus (1),measurement reference data (C) relating to the multiple measurement ref¬ erence surfaces and / or further measurement reference data (D) relating to the multiple further measurement reference surfaces of the reference body (200) are provided before step a), anda potential deviation of the measured second actual position (P2IST) from the measured first actual position (PIIST) of the reference body (200) is ascertained in step d) on the basis of the measurement reference data (C) and / or the further measurement reference data (D).

10. Method according to any of Claims 1 to 9, whereinthe first module and the second module (102, 102') correspondingly comprise a first optics module and a second optics module (102, 102'),the first optics module and the second optics module (102, 102') each comprise a holding frame (104, 104') and, assembled thereon, an optical element (M5, M5') with an optical axis (112, 112'), andin step b), the actual position (PIST) of the holding frame (104) of the first optics module (102) is measured with the aid of the measuring device (300), and the second optics module (102') is assembled on the basis of the measured actual position (PIST) of the holding frame (104) of the first optics module (102).

11. Method according to Claim 10, whereinmeasurement data (A, B) relating to a pose of the optical axis (112, 112') relative to the holding frame (104, 104') respectively in the first optics module (102) and in the second optics module (102') are provided, andthe second optics module (102') is assembled in step b) on the basis of the measured actual position (PIST) of the holding frame (104) of the first optics module (102), with the aid of the measuring device (300) and on the basis of theCarl Zeiss SMT GmbH35measurement data (A, B) relating to the pose of the optical axis (112, 112') in the first and second optics modules (102, 102').

12. Method according to any of Claims 1 to 11, whereinthe actual position (PIST) of the first module (102) is measured in six degrees of freedom (x, y, z, Rx, Ry, Rz) in step b), andthe assembly of the second module (102') in step b) comprises aligning the second module (102') in six degrees of freedom (x, y, z, Rx, Ry, Rz) on the basis of the actual position (PIST) of the first module (102) determined in six degrees of freedom (x, y, z, Rx, Ry, Rz).

13. Method according to any of Claims 1 to 12 and Claim 3, whereinthe first actual position and the second actual position (P1IST, P2IST) of the reference body (200) are each measured in six degrees of freedom (x, y, z, Rx, Ry, Rz) with the aid of the measuring device (300) in steps a) and c),the ascertainment of the deviation (Δ) of the measured second actual position (P2IST) from the measured first actual position (P1IST) of the reference body (200) includes ascertaining the deviation (Δ) in relation to the six degrees of free¬ dom (x, y, z, Rx, Ry, Rz), andthe position of the second module (102') is corrected on the basis of the as¬ certained deviation (Δ) in six degrees of freedom (x, y, z, Rx, Ry, Rz).

14. Method according to any of Claims 1 to 13, wherein the assembly of the sec¬ ond module (102') in step b) and / or the correction of the position of the second module (102') on the basis of the ascertained deviation (A) comprises aligning the second module (102') using spacers (114).

15. Method according to any of Claims 1 to 14, wherein the first module and the second module (102, 102') eachcomprise a mirror (M5, M5') and / orare assembled on an external side (120) of the lithography apparatus (1) and / or the projection optics unit (10) thereof.

16. Method according to any of Claims 1 to 15, wherein the method includes the following steps before step a):assembling (S2) the first module (102) on the lithography apparatus (1), operating (S3) the lithography apparatus (1), in particular for exposing wafers (13), andascertaining that replacing the first module (102) with the second module (102') is required.

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