Method for replacing optical elements in a semiconductor technology system

Abstract

The invention relates to methods for replacing optical elements (25) of a semiconductor technology system, wherein the optical elements are designed for a production wavelength and at least part of the product beam path (40) in the system passes through an area with an artificially generated atmosphere (90), comprising the steps: a) Replacement of at least one optical element (25, 25') of the semiconductor technology system; b) Positioning and aligning at least the optical element (25') replaced in the previous step; c) Performing a wavefront measurement along a beam path (140) comprising at least one replaced optical element (25') without an artificially generated atmosphere (90) in the area provided for this purpose with a predetermined wavelength which differs from the productive wavelength; d) if the wavefront measurement reveals a wavefront error: adjust the positioning and alignment of at least the replaced optical element (25') and repeat step (c); and e) if the wavefront measurement does not reveal any error: Production of the artificially generated atmosphere (90) in the area designated for this purpose.

Description

[0001] The invention relates to a method for replacing optical elements of a system for semiconductor technology.

[0002] In the prior art, semiconductor technology equipment refers to equipment used for the production or testing of microstructured devices or the components required for their manufacture. An example of such equipment is a projection exposure system for photolithography.

[0003] Photolithography is used to manufacture microstructured components, such as integrated circuits. The projection exposure system used comprises an illumination system and a projection system. The image of a mask (also called a reticulum) illuminated by the illumination system is projected in a reduced size onto a substrate, such as a silicon wafer, coated with a photosensitive layer and positioned in the image plane of the projection system. This transfers the mask structure onto the photosensitive coating of the substrate.

[0004] Both illumination and projection systems, particularly projection exposure systems designed for the EUV range (i.e., for exposure wavelengths from 5 nm to 30 nm), typically employ multiple optical elements, especially mirrors, to achieve the desired image of the mask onto the substrate. Due to the required accuracy, it is essential, especially in projection systems, to ensure that the individual optical elements are positioned with high precision relative to each other, as well as to the mask and the substrate, during operation of the projection exposure system.

[0005] Particularly in EUV projection exposure systems, some of the optical elements can be adjusted in position using actuators. This allows for the compensation of deviations from the ideal position of each optical element, such as those caused by heat input, even during operation. For this purpose, a measuring device tuned to the exposure wavelength can be integrated into the projection exposure system. This device can detect any wavefront errors along the beam path used for exposure. If a wavefront error is detected, a suitable control system can attempt to correct it by selectively changing the position of the individual adjustable optical elements.

[0006] If an optical element needs to be replaced, for example due to damage or degradation of the reflective surface, the projection exposure system must be opened to allow for the replacement. When inserting the new optical element, care must be taken to ensure that it is positioned with sufficient accuracy relative to the other optical elements. This is because wavefront errors resulting from inaccurate positioning can only be compensated to a certain extent by the adjustability of the projection exposure system's optical elements. This applies regardless of whether the optical element being replaced is itself adjustable within the projection exposure system. If the initial positional accuracy of a replaced optical element is insufficient, its position must be appropriately corrected, e.g., by adjusting the position.by arranging suitable spacers in the area where the optical element is attached.

[0007] In known projection exposure systems, especially those for EUV applications, the optical elements are located in a largely evacuated area of ​​the system to prevent the radiation used for exposure from being absorbed by dust particles or gas molecules along the beam path. For the actual replacement of an optical element in this evacuated area, the area must be regularly pressurized to ambient pressure. However, to check the wavefront after the mirror has been replaced using the measuring equipment in the projection exposure system, the area must then be evacuated again just as regularly.

[0008] In particular, the evacuation of the area in question, required after replacement, is time-consuming and energy-intensive. If, after evacuation, a wavefront error determined by the measuring device integrated into the projection exposure system reveals that the position of the replaced component does not meet the accuracy requirements, the area in question must be brought back to ambient pressure to adjust the position of the replaced optical element before the area is evacuated again. In this case especially, replacing an optical component is associated with considerable time and energy expenditure.

[0009] The object of the present invention is to provide a method for replacing an optical element of a projection exposure system for photolithography, in which the disadvantages known from the prior art no longer occur or only occur to a reduced extent.

[0010] This problem is solved by a method according to claim 1. Advantageous further developments are the subject of the dependent claims.

[0011] Accordingly, the invention relates to a method for replacing optical elements of a system for semiconductor technology, wherein the optical elements are designed for a production wavelength and at least part of the product beam path in the system passes through an area with an artificially generated atmosphere, comprising the steps: a) Replacement of at least one optical element of the semiconductor technology system; b) Positioning and aligning at least the optical element replaced in the previous step; c) Performing a wavefront measurement along a beam path comprising at least one replaced optical element without an artificially generated atmosphere in the designated area with a predetermined wavelength that differs from the productive wavelength; d) if wavefront measurement reveals a wavefront error: adjust the positioning and orientation of at least the replaced optical element and repeat step (c); and e) if wavefront measurement reveals no error: Production of the artificially generated atmosphere in the designated area.

[0012] First, some terms used in connection with the invention will be explained.

[0013] In the context of the present invention, the term "semiconductor technology equipment" refers to any equipment that can be used for the fabrication or inspection of microstructured devices or the components required for their production. In addition to projection exposure systems for photolithography, this includes, in particular, inspection systems and metrology systems. For example, in inspection systems for masks or wafers, the variability of the illumination can be increased using one or more MEMS micromirror units, resulting in higher-contrast or entirely new image representations of the surface of a mask or wafer, which can be advantageous for mask or wafer inspection.The same applies to metrology systems that can be used to measure masks, wafers or other optical elements, such as mirrors in particular, where increased variability in illumination can improve the measurement results.

[0014] The "optical elements" of a semiconductor technology system, such as a projection exposure system, particularly its illumination system and / or projection system, are primarily beam-modifying elements, including mirrors and lenses. "Optical element to be replaced" according to step a) means an optical element that is removed from the system. "Optical element replaced" according to step b) means an optical element that is newly inserted into the system in exchange for the optical element to be replaced or removed. "Positioning and aligning at least the optical element replaced in the previous step" means, in other words, "positioning and aligning at least one optical element replaced for the optical element to be replaced in the previous step."

[0015] The "productive wavelength" refers to the wavelength used in the proper operation of a semiconductor manufacturing system for its intended purpose. The system's optical elements are generally designed for this wavelength, although they can, of course, also transform radiation of other wavelengths. The productive wavelength can also refer to a wavelength range. If the semiconductor manufacturing system is a projection exposure system for photolithography, the productive wavelength corresponds to the exposure wavelength used to image a reticulum onto a specially designed radiation-sensitive layer in order to trigger chemical reactions within that layer. Common exposure wavelengths include, for example, 193 nm or 13.5 nm.

[0016] The production radiation, with the production wavelength, is generated by a radiation source and transformed and / or deflected by suitable optical elements to achieve the desired effect for the respective system, e.g., to project a mask located in an object plane onto an image plane. The path that the production radiation takes from the radiation source is called the "production beam path." In the case of a projection exposure system used for semiconductor technology, the production beam path typically runs from a radiation source through optical elements of an exposure system, the reticles, and optical elements of a projection system to a substrate coated with a photosensitive layer.

[0017] If the production radiation would be absorbed too strongly in an atmospheric environment to achieve the desired effect, it is known to route the production beam path, at least partially, through one or more areas with an artificially generated atmosphere within the semiconductor technology system. Often, the entire production beam path runs through an area with an artificially generated atmosphere within the semiconductor technology system, in which case all components relevant to the production beam path, such as optical elements, are also located in this area. The artificially generated atmosphere can be characterized, in particular, by a very low pressure practically equivalent to a vacuum, preferably with a residual amount of hydrogen, and / or by a hydrogen plasma. In other applications, the artificially generated atmosphere can also be a nitrogen atmosphere.

[0018] The invention recognizes that, when replacing an optical element in a semiconductor technology system, if a pre-existing artificial atmosphere (such as a vacuum) must be disturbed, verifying the correct positioning of the replaced optical element with a predetermined accuracy is disadvantageous if the artificial atmosphere must first be re-established – particularly if it turns out that the position of the replaced optical element needs to be corrected, for which the artificial atmosphere then has to be temporarily disturbed again. To verify the correct position of a replaced element in semiconductor industry systems, it is state of the art to perform a wavefront measurement along the production beam path.The restoration of the artificial atmosphere is regularly necessary because, according to the state of the art, radiation in the productive wavelength is generally used for wavefront measurement.

[0019] The invention differs fundamentally from the prior art. Instead of performing a wavefront measurement with the production wavelength over the entire production beam path, the invention provides for performing the wavefront measurement with a wavelength different from the production wavelength. Considering the optical properties of the optical elements of the semiconductor technology system, a wavelength can be selected that does not require a special artificial atmosphere for the wavefront measurement, but is, for example, not absorbed by air or only absorbed to a negligible extent. Furthermore, the wavefront measurement does not need to be performed over the entire production beam path. Although this is of course possible, according to the invention it is sufficient if the wavefront measurement is performed along a beam path encompassing at least one replaced optical element.In the inventive method, the beam path for wavefront measurement often largely coincides with at least one section of the production beam path and / or includes the optical elements arranged along the production beam path in front of and behind a replaced optical element; however, this is not absolutely necessary.

[0020] If the optical elements involved in the beam path for the wavefront measurement performed according to the inventive method are adjustable – whether replaced or not – by means of adjustment units, the adjustable optical elements are adjusted appropriately for the beam path. In other words, the adjustable optical elements should be adjusted so that the desired and necessary beam path for the wavefront measurement is actually achieved. Optical elements adjustable, for example, with regard to their position and / or orientation by means of adjustment units, can be provided in semiconductor technology systems to compensate for changes in position and / or orientation that occur during the use of the system.In order to check the positioning and alignment of a replaced optical element, it is necessary or at least expedient to move the adjustable optical elements involved in the intended beam path into a position and / or alignment typical or fundamental for the subsequent use of the system for semiconductor technology.

[0021] It is particularly preferred if, during wavefront measurement, the adjustable optical elements are repositioned within predefined limits by a control device, depending on the currently determined wavefront error, to reduce any detected wavefront error. Assuming that the required accuracy cannot be achieved, or at least not permanently maintained, with static positioning and alignment of the optical elements, e.g., to achieve a desired image quality, and considering that adjustment units already present in semiconductor industry systems are used to adjust the position and alignment of optical elements to reduce otherwise occurring wavefront errors, this functionality can also be used to reduce wavefront errors during the method according to the invention. However, limits are preferably defined, e.g.,specified for the adjustment of the individual optical elements, which, even after reduction of the wavefront error during the present procedure, still leave sufficient scope to compensate for wavefront errors detected or occurring during the actual operation of the semiconductor technology system.

[0022] Since a semiconductor technology system may not have the radiation source and / or wavefront sensor required for the wavefront measurement according to the invention, it is preferred to arrange a radiation source for the specified wavelength and / or a wavefront sensor in or on the semiconductor technology system before the wavefront measurement is carried out. A correspondingly mounted radiation source and / or wavefront sensor is preferably at least partially removed from the designated area before the artificially generated atmosphere is created, which concludes the present method. The radiation source and / or wavefront sensor is preferably dynamically and stably mounted on the semiconductor technology system.

[0023] Regardless of whether the radiation source used for wavefront measurement is part of the semiconductor technology system or is temporarily located in or on the system, it is preferred if the radiation source is tunable and adjustable to the specified wavelength.

[0024] The wavefront sensor or wavefront measuring device can be of an interferometric type, for example, designed as a lateral shear interferometer, or of a Shack-Hartmann type. The wavefront sensor preferably comprises a 2D image acquisition sensor and a lens mask arranged at a distance in front of it, preferably a perforated disk or a microlens array. The determination of wavefronts or wavefront errors with corresponding sensors, i.e., in particular with Hartmann or perforated disk sensors and Shack-Hartmann sensors, is known to those skilled in the art.

[0025] If an optical element along the beam path intended for wavefront measurement is a reticle, it is preferred if the reticle is specifically designed for wavefront measurement. If, for example, the system for semiconductor technology is designed for reticles that are generally reflective away from the structure to be imaged, a completely reflective reticle without any structure is preferably provided for wavefront measurement.

[0026] It is also possible to provide a self-illuminating reticulum, which can then serve as a radiation source.

[0027] The system for semiconductor technology is preferably a projection exposure system for photolithography. The artificial atmosphere required along the production beam path for the final use of the projection exposure system can be a vacuum.

[0028] The invention will now be described by way of example using an advantageous embodiment with reference to the accompanying drawings. These show: Fig. 1: a schematic representation of a projection exposure system for photolithography; and Fig. 2: a schematic representation of the implementation of the method according to the invention on the projection exposure system according to Fig. 1.

[0029] In Fig. Figure 1 shows a projection exposure system 1 for photolithography as an example of a system for semiconductor technology in a schematic meridional section. The projection exposure system 1 comprises an illumination system 10 and a projection system 20.

[0030] The illumination system 10 illuminates an object field 11 in an object plane or reticulum plane 12. The illumination system 10 comprises an illumination radiation source 13, which, in the illustrated embodiment, emits illumination radiation comprising at least useful light in the EUV range, i.e., in particular with a wavelength between 5 nm and 30 nm. The illumination radiation source 13 can be a plasma source, for example, an LPP source (laser-produced plasma) or a DPP source (gas-discharge-produced plasma). It can also be a synchrotron-based radiation source. The illumination radiation source 13 can also be a free-electron laser (FEL).

[0031] The illumination radiation emanating from the light source 13 is first focused in a collector 14. The collector 14 can be a collector with one or more ellipsoidal and / or hyperboloid reflective surfaces. The at least one reflective surface of the collector 14 can be illuminated at grazing incidence (GI), i.e., with angles of incidence greater than 45°, or at normal incidence (NI), i.e., with angles of incidence less than 45°. The collector 14 can be structured and / or coated to optimize its reflectivity for the useful radiation and to suppress stray light.

[0032] After the collector 14, the illumination radiation propagates through an intermediate focus in an intermediate focal plane 15. If the illumination system 10 is to be constructed in a modular manner, the intermediate focal plane 15 can, in principle, be used for the separation – including structural separation – of the illumination system 10 into a radiation source module, comprising the exposure radiation source 13 and the collector 14, and the illumination optics 16 described below. With such a separation, the radiation source module and the illumination optics 16 then together form a modularly constructed illumination system 10.

[0033] The illumination optics 16 include a deflecting mirror 17. The deflecting mirror 17 can be a flat deflecting mirror or, alternatively, a mirror with an effect that influences the beam shape beyond the mere deflection effect. Alternatively or additionally, the deflecting mirror 17 can be designed as a spectral filter that separates a useful wavelength of the illumination radiation from stray light of a different wavelength.

[0034] The deflecting mirror 17 deflects the radiation from the illumination radiation source 13 onto a first faceted mirror 18. If the first faceted mirror 18 is arranged – as in the present case – in a plane of the illumination optics 16 that is optically conjugate to the reticular plane 12 as a field plane, it is also referred to as a field faceted mirror.

[0035] The first faceted mirror 18 comprises a plurality of micromirrors 18', each individually pivotable about two mutually perpendicular axes, for the controllable formation of facets. Each micromirror is equipped with an orientation sensor (not shown) for determining its orientation. The first faceted mirror 18 is therefore a microelectromechanical system (MEMS system), as described, for example, in DE 10 2008 009 600 A1.

[0036] In the beam path of the illumination optics 16, a second faceted mirror 19 is arranged downstream of the first faceted mirror 18, resulting in a double-faceted system, the basic principle of which is also known as a honeycomb condenser (fly's eye integrator). If the second faceted mirror 19 is arranged in a pupil plane of the illumination optics 16 – as in the illustrated embodiment – ​​it is also referred to as a pupil faceted mirror. However, the second faceted mirror 19 can also be arranged at a distance from a pupil plane of the illumination optics 16, in which case the combination of the first and second faceted mirrors 18, 19 results in a specular reflector, as described, for example, in US 2006 / 0132747 A1, EP 1 614 008 B1, and US 6,573,978.

[0037] The second faceted mirror 19 need not be constructed from pivotable micromirrors, but can instead comprise individual facets formed from one or a manageable number of mirrors that are significantly larger than micromirrors, and which are either fixed or tiltable only between two defined end positions. However, as shown, it is also possible to provide the second faceted mirror 19 with a microelectromechanical system comprising a plurality of micromirrors 19' that are individually pivotable about two axes perpendicular to each other, each preferably including an orientation sensor.

[0038] With the aid of the second faceted mirror 19, the individual facets of the first faceted mirror 18 are projected onto the object field 11, although this is regularly only an approximate projection. The second faceted mirror 19 can be the last beam-shaping or even the last mirror for the illumination radiation in the beam path before the object field 11.

[0039] Each of the facets of the second faceted mirror 19 is assigned to exactly one of the facets of the first faceted mirror 18 to form an illumination channel for illuminating the object field 11. This can result in illumination according to Köhler's principle.

[0040] The facets of the first faceted mirror 18 are each superimposed by a corresponding facet of the second faceted mirror 19 to illuminate the object field 11. The illumination of the object field 11 is as homogeneous as possible. It preferably exhibits a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0041] By selecting the illumination channels ultimately used, which is easily achieved by appropriately adjusting the micromirrors 18' of the first faceted mirror 18, the intensity distribution in the entrance pupil of the projection system 20 described below can also be adjusted. This intensity distribution is also referred to as the illumination setting. Furthermore, it can be advantageous not to arrange the second faceted mirror 19 exactly in a plane that is optically conjugate to a pupil plane of the projection system 20. In particular, the pupil faceted mirror 19 can be tilted relative to a pupil plane of the projection system 20, as described, for example, in DE 10 2017 220 586 A1.

[0042] During the Fig. In the arrangement of the components of the illumination optics 16 shown in Figure 1, the second faceted mirror 19 is arranged in a surface conjugate to the entrance pupil of the projection system 20. Deflection mirror 17 and the two faceted mirrors 18, 19 are arranged at an angle both to the object plane 12 and to each other.

[0043] In an alternative embodiment of the illumination optics 16, not shown, a transmission optic comprising one or more mirrors can be provided in the beam path between the second faceted mirror 19 and the object field 11. The transmission optic can, in particular, comprise one or two mirrors for normal incidence (NI mirrors) and / or one or two mirrors for grazing incidence (GI mirrors). With an additional transmission optic, different positions of the entrance pupil for the tangential and sagittal beam paths of the projection system 20 described below can be accommodated.

[0044] Alternatively, it is possible that on the in Fig. The deflecting mirror 17 shown in Figure 1 is dispensed with, for which the faceted mirrors 18, 19 are then to be arranged appropriately opposite the radiation source 13 and the collector 14.

[0045] Using the projection system 20, the object field 11 in the reticulum plane 12 is transferred to the image field 21 in the image plane 22.

[0046] The projection system 20 comprises a plurality of mirrors M. i , which are numbered according to their arrangement in the beam path of the projection exposure system 1. Regarding the mirrors M i These are optical elements 25.

[0047] In the Fig. In the example shown, the projection system 20 comprises six mirrors M1 to M6 as optical elements 25. Alternatives with four, eight, ten, twelve or another number of mirrors M iare also possible. The penultimate mirror M5 and the last mirror M6 each have a passage for the illumination radiation, making the depicted projection system 20 a doubly obscured optic. The projection system 20 has an image-side numerical aperture that is greater than 0.3 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0048] Mirrors M1 to M4 and M6 are each arranged on an adjustment unit 26, which allows the optical elements 25 to be adjusted in their position and / or orientation within a certain range. A control unit (in Fig. (1 not shown) the adjustment units 26 are controlled during the operation of the projection exposure system 1 to ensure the most optimal possible imaging of the reticulum 30 onto the wafer 35.

[0049] The reflective surfaces of the mirrors M ican be designed as freeform surfaces without an axis of rotational symmetry. Alternatively, the reflective surfaces of the mirrors M can be i but can also be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflecting surface shape. The mirrors M i Like the mirrors of the lighting optics 16, they can have highly reflective coatings for the illumination radiation. These reflective coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0050] The projection system 20 has a large object-image offset in the y-direction between a y-coordinate of the center of the object field 11 and a y-coordinate of the center of the image field 21. This object-image offset in the y-direction can be approximately as large as a z-distance between the object plane 12 and the image plane 22.

[0051] The projection system 20 can in particular be anamorphic, i.e. it has in particular different image scales β x , β y in the x and y directions. The two image scales β x , β y of the projection system 20 are preferably located at (β x , β y ) = (+ / - 0.25, / +- 0.125). A magnification β of 0.25 corresponds to a reduction in the ratio of 4:1, while a magnification β of 0.125 results in a reduction in the ratio of 8:1. A positive sign for the magnification β indicates a magnification without image inversion, a negative sign indicates a magnification with image inversion.

[0052] Other magnification ratios are also possible. Magnification ratios with the same sign and those with the same absolute value β are also possible. x , β y In the x and y directions, adjustments are possible.

[0053] The number of intermediate image planes in the x- and y-directions in the beam path between the object field 11 and the image field 21 can be the same or different, depending on the design of the projection system 20. Examples of projection systems 20 with different numbers of such intermediate images in the x- and y-directions are known from US 2018 / 0074303 A1.

[0054] Projection system 20 can, in particular, have a homocentric entrance pupil. This may be accessible. However, it may also be inaccessible.

[0055] A reticle 30 (also called a mask) arranged in the object field 11 is exposed by the lighting system 10 and transferred to the image plane 21 by the projection system 20. The reticle 30 is held by a reticle holder 31. The reticle holder 31 can be moved, particularly in a scanning direction, by means of a reticle displacement drive 32. In the illustrated embodiment, the scanning direction is in the y-direction.

[0056] The reticle 30 can have an aspect ratio between 1:1 and 1:3, preferably between 1:1 and 1:2, and particularly preferably 1:1 or 1:2. The reticle 30 can be substantially rectangular and is preferably 5 to 7 inches (12.70 to 17.78 cm) long and wide, more preferably 6 inches (15.24 cm) long and wide. Alternatively, the reticle 30 can be 5 to 7 inches (12.70 to 17.78 cm) long and 10 to 14 inches (25.40 to 35.56 cm) wide, and is preferably 6 inches (15.24 cm) long and 12 inches (30.48 cm) wide.

[0057] A structure on the reticulum 30 is imaged onto a photosensitive layer of a wafer 35 located in the image plane 22 within the image field 21. The wafer 35 is held by a wafer holder 36. The wafer holder 36 can be displaced, particularly along the y-direction, via a wafer transfer drive 37. The displacement of the reticulum 30 via the reticulum transfer drive 32 and of the wafer 35 via the wafer transfer drive 37 can be synchronized.

[0058] The in Fig. The projection exposure system 1 shown in Figure 1, or its illumination system 10, the description of which essentially reflects known prior art, is characterized in that the entire production beam path 40, shown by dotted lines, runs from the exposure radiation source 13 to the wafer 35 in a vacuum as an artificial atmosphere 90. This ensures that the production wavelength in the EUV range, here 13.5 nm, actually reaches the wafer 35 from the exposure radiation source 13 and is not absorbed by an atmosphere. To ensure that the production beam path runs exclusively through the artificial atmosphere 90 or the vacuum, all components of the projection exposure system 1 shown are arranged in the evacuable space in which the artificial atmosphere 90 or the vacuum can be created. The space has a corresponding volume, which is why, among other things,creating the artificial atmosphere 90 in the room involves considerable time and energy expenditure.

[0059] In Fig. Figure 2 illustrates the execution of the method according to the invention.

[0060] This shows Fig. 2 the projection exposure system 1 in the state after the first two process steps, namely the replacement of at least one optical element 25 and the initial positioning and alignment of the replaced optical element 25', have already been completed: In the example shown, the mirror M4 has been replaced (see reference numeral 25', M4') and has been arranged on the associated adjustment unit 26 using fastening elements and spacers to establish the basic production beam path 40.

[0061] In order to actually replace the optical element 25, M4, the artificial atmosphere 90 required for the use of the projection exposure system 1, namely the vacuum, must first be removed, and the material in Fig. The situation shown in Figure 2 has not yet been restored. The optical elements 25, 25' are therefore exposed to the atmosphere surrounding the projection exposure system 1, in this case the filtered air of the cleanroom in which the projection exposure system 1 is located.

[0062] After the artificial atmosphere 90 was removed and before or after the replacement of the mirror M4, a wavefront measurement arrangement 100 is temporarily installed in the projection exposure system 1. The arrangement 100 comprises, in addition to a control device 110, the operation of which will be discussed later, a radiation source 120 and a wavefront sensor 130.

[0063] In the present embodiment, the radiation source 120 largely has the external shape of a reticle 30 (cf. Fig. 1) so that the radiation source 120 can be mounted on the reticule holder 31 and, if necessary, even positioned with high precision using the reticule displacement drive 32. In the illustrated embodiment, the radiation source 120 is self-illuminating and comprises a planar light-emitting diode that emits radiation at a wavelength visible to the human eye and thus different from the productive wavelength in the EUV range. The radiation source 120 of the illustrated embodiment is not tunable, although this may be preferable in principle.

[0064] The wavefront sensor 130 exhibits – comparable to the radiation source 120 – the external shape of a wafer 35 to a large extent (cf. Fig. 1) that it can be attached to the wafer holder 36 in place of a wafer 35 and finely positioned via the wafer transfer drive 37. The wavefront sensor 130 is designed for the wavelength of the radiation source 120 and, in the present embodiment, is configured as a Shack-Hartmann sensor. The wavefront sensor 130 thus comprises a 2D image acquisition sensor 131 with a lens mask 132 in the form of a microlens array arranged at a distance in front of it. The operation of the wavefront sensor 130 and the evaluation of the images acquired by the 2D image acquisition sensor 131 to determine any wavefront errors are known to those skilled in the art and require no further explanation here.

[0065] The control unit 110 is connected to both the radiation source 120 and the wavefront sensor 130. Furthermore, the control unit 110 is connected to the various adjustment units 26 for the optical elements 25, 25' and the reticle and wafer transfer drives 32, 37. The control unit 110 can be a separate component that, together with the other components of the arrangement 100, i.e., the radiation source 120 and the wavefront sensor 130, is integrated into the projection exposure system 1. In this case, the control unit 110 is then either directly connected to the adjustment units 26 and the transfer drives 32, 37, or to an interface of the control system of the projection exposure system 1, so that the control unit 110 can actually control the aforementioned components. Alternatively, the control unit 110 can, for example,in the form of a computer program product, represented in the control system of the projection exposure unit 1. In this case, radiation source 120 and wavefront sensor 130 must be connected to the control system of the projection exposure unit 1 so that they can be controlled by the control device 110.

[0066] To perform a wavefront measurement, after the radiation source 120 and wavefront sensor 130 have been positioned with sufficient accuracy using the displacement drives 32, 37, the optical elements 25, 25' are first brought into a position and orientation by the control unit 110 using the adjustment units 26, which is generally intended for the production beam path 40 via these optical elements 25, 25' (see figure). Fig. 1) is suitable. The beam path 140, which basically results after switching on the radiation source 120 by the control unit 110 and leads to the wavefront sensor 130, is in Fig. 2 shown as dashed lines.

[0067] The wavefront (or the dot pattern depicting the wavefront) determined by the wavefront sensor 130 is then examined for wavefront errors by the control unit 110.

[0068] If a wavefront error is detected, the control unit 110 systematically and precisely controls the adjustment units 26 in order to reduce the wavefront error as much as possible. The control strategies to be pursued by the control unit 110 are generally known to the specialist or can at least be determined for the respective configuration of the projection exposure system 1 with manageable effort.

[0069] The adjustment of the optical elements 25, 25' by the control unit 110 is carried out while the wavefront continues to be measured, in order to directly monitor the effect of the adjustment on the wavefront error. The adjustment of the individual optical elements 25, 25' is performed exclusively within predefined limits, which are generally narrower than the adjustment ranges generally available for the individual adjustment units 26. This ensures that sufficient adjustment ranges remain available at each of the adjustment units 26 during subsequent operation of the projection exposure system 1 to allow for any necessary adjustments to the position and / or alignment of individual optical elements 25, 25' during operation 1.

[0070] If a detected wavefront error cannot be reduced, or cannot be sufficiently reduced, within the specified limits using the control unit 110 and the adjustment units 26, the position and orientation of the replaced optical element 25' must be adjusted manually. In the present embodiment, this would involve detaching the mirror M4' from the adjustment unit 26 and reattaching it using modified mounting elements and / or spacers. The wavefront measurement results from the control unit 110 can provide guidance as to which mounting elements and / or spacers should be used.

[0071] Once the positioning and / or alignment of the replaced optical element 25' has been adjusted, the described wavefront measurement is performed again to check whether an uncompensable wavefront error still exists.

[0072] If no wavefront error is detectable, or if an existing wavefront error can be compensated for by the adjustment units 26, the arrangement 100 is at least partially removed from the projection exposure system 1; that is, at least the radiation source 120 and the wavefront sensor 130 are removed. Whether the control unit 110 can or must be removed depends on the individual case. If the control unit 110 is represented purely in software within the control system of the projection exposure system 1, it only needs to be deactivated, for example, but not completely removed.

[0073] If the arrangement is 100 meters away, the artificial atmosphere can be 90 degrees away (see below). Fig.1) or the vacuum is produced and the projection exposure system 1 can be used properly again. Due to the method according to the invention, the time- and energy-intensive production of the artificial atmosphere 90 only takes place if it is ensured that the projection exposure system can be operated with the required accuracy despite the replacement of an optical component 25'. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2008 009 600 A1

[0035] US 2006 / 0132747 A1

[0036] EP 1 614 008 B1

[0036] US 6,573,978

[0036] DE 10 2017 220 586 A1

[0041] US 2018 / 0074303 A1

[0053]

Claims

[1] Method for replacing optical elements (25) of a semiconductor technology system, wherein the optical elements (25) are designed for a production wavelength and at least part of the product beam path (40) in the system passes through an area with an artificially generated atmosphere (90), comprising the steps: a) Replacement of at least one optical element (25) of the semiconductor technology system; b) Positioning and aligning at least one optical element exchanged in the previous step (25') ; c) Performing a wavefront measurement along a beam path (140) comprising at least one replaced optical element (25') without an artificially generated atmosphere (90) in the area provided for this purpose with a predetermined wavelength which differs from the productive wavelength; d) if the wavefront measurement reveals a wavefront error: adjust the positioning and orientation of at least the replaced optical element (25') and repeat step (c); and e) if the wavefront measurement does not reveal any error: Production of the artificially generated atmosphere (90) in the area designated for this purpose. [2] Method according to claim 1, characterized by , that at least part of the optical elements (25, 25') along the beam path (140) provided for wavefront measurement are adjustable by means of adjustment units (60) and are adjusted appropriately for the beam path (140). [3] Method according to claim 2, characterized by, that the adjustable optical elements (25, 25') are adjusted during the wavefront measurement, preferably within predetermined limits, by a control device (110) to reduce any wavefront error that may be detected, depending on the wavefront error currently determined. [4] Method according to any one of the preceding claims, characterized by , that for the wavefront measurement a radiation source (120) for the specified wavelength and / or a wavefront sensor (130) is arranged in or on the semiconductor technology system before the wavefront measurement is carried out and / or is at least partially removed in the area provided for this purpose before the artificially generated atmosphere (90) is produced. [5] Method according to any one of the preceding claims, characterized by , that the radiation source (120) is tunable and adjustable to the specified wavelength. [6] Method according to any one of the preceding claims, characterized by , that the wavefront sensor (130) comprises a 2-D image acquisition sensor (131) and a lens mask (132) arranged at a distance in front of it, preferably a perforated sheet or a microlens array. [7] Method according to any one of the preceding claims, characterized by , that at least one optical element (25, 25') along the beam path intended for wavefront measurement is a reticle designed for this purpose. [8] Method according to any one of the preceding claims, characterized by , that the facility for semiconductor technology is a projection exposure system (1) for semiconductor lithography.

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