Optical assembly comprising a monitoring apparatus for monitoring an EUV collector of a projection exposure system

Abstract

The invention relates to a monitoring apparatus (46) of an optical assembly which is used to monitor an EUV collector of a projection exposure system. A detector device (38) of the monitoring apparatus (46) has at least one stray light detector (47i) for detecting stray light radiation (20) having a stray light wavelength which differs by at least 10% from a useful light wavelength of useful light (3) generated by an EUV light source (2), the stray light radiation (20), which originates from a component of the EUV light source, being reflected off a collector surface of the EUV collector. A detection component (37; 32) of the detector device (38) can be placed in an illumination optics positioning plane (40), which is optically conjugate to a collector positioning plane of the EUV collector. The optical assembly has an illumination optics mirror (FF), which is arranged in the illumination optics positioning plane (40) and has a plurality of tiltable individual detector mirrors (32) as detection components of the monitoring apparatus (46). The individual detector mirrors (32) can be tilted between a useful tilted position for guiding EUV useful light (3) and a measuring tilted position. The measuring tilted position is used to guide the stray light radiation (20) to at least one stray light detector (471). The monitoring results in increased collector efficiency.

Description

[0001] Optical assembly with a monitoring device for monitoring an EUV collector of a projection exposure system

[0002] The content of the German patent application DE 10 2024 207 726.7 is incorporated herein by reference.

[0003] The invention relates to an optical assembly with a monitoring device for monitoring an EUV collector of a projection exposure system. Furthermore, the invention relates to a projection exposure system with such an optical assembly, a method for monitoring an EUV collector of a projection exposure system using such an optical assembly, a manufacturing method for producing a micro- or nano-structured component, and a micro- or nano-structured component produced by this method.

[0004] An EUV collector of the type mentioned above is known from WO 2017 / 174423 Al, US 2013 / 0335816 Al and US 7 084412 B2. DE 10 2011 081 914 Al discloses an illumination optic for illuminating a structured object that can be arranged in an object field. DE 10 2013 211 269 Al discloses an illumination optic and a metrology system for examining a structured object. Monitoring devices are known from DE 10 2019 200 852 Al, DE 10 2019 200 855 Al, DE 10 2017 204 104 Al and WO 2019 / 063 254 AE. DE 10 2020 200 158 Al discloses an illumination optic for EUV projection lithography. US 2007 / 0008509 Al discloses a projection exposure system. WO 2015 / 161 948 Al discloses a projection exposure system and a component manufacturing method. An object of the present invention is to enable an improvement in the collector efficiency of an EUV collector.

[0005] This problem is solved according to the invention by an optical assembly with a monitoring device having the features specified in claim 1.

[0006] According to the invention, it has been discovered that a state of an EUV collector, characterizing its collector efficiency, can be monitored using at least one stray light detector. The stray light detector can detect the stray light suppression efficiency of the collector surface during the gathering of useful light through the EUV collector. This measurable suppression efficiency can represent a measure of collector degradation, which can be monitored and detected by the monitoring device. The detection component of the monitoring device can, for example, be arranged in the area of ​​a support structure for a field facet mirror and / or for a MEMS mirror of an illumination optic of the projection exposure system. The monitoring device can ensure that the projection exposure system is only operated as long as useful light is guided by the EUV collector within predefined efficiency tolerance limits.

[0007] In particular, degradation of the EUV collector due to debris deposits on the collector surface can be detected using the monitoring device. The stray light radiation can be IR (infrared) radiation. The stray light detector can be an IR detector. Alternatively or additionally, the stray light detector can also detect stray light radiation, for example, in the EUV wavelength range (wavelength greater than 100 nm) and / or in the UV wavelength range and / or in the VIS wavelength range. Detection of out-of-band EUV stray light is also possible, i.e., when using EUV useful light in the 13.5 nm range, the detection of EUV wavelengths in the range between 1 nm and 12 nm or in the range between 15 nm and 50 nm.

[0008] The use of the monitoring device is particularly advantageous in connection with an EUV plasma light source.

[0009] The monitoring device can, in particular, detect the temporal profile of a parasitic stray light radiation component, especially an IR radiation component. If it is determined that this stray light radiation component is increasing, which can be done using the at least one stray light detector of the monitoring device's detector assembly, this allows a conclusion to be drawn about a corresponding change in the state or degradation of the EUV collector.

[0010] The illumination optics mirror can be a field faceted mirror or a micromirror array, such as a MEMS mirror. The illumination optics mirror can be part of a honeycomb condenser and / or a specular reflector. The optical assembly can also include the EUV collector. The illumination optics mirror incorporates multiple tiltable detector mirrors as detection components of the monitoring device. These detector mirrors can be tilted between a functional position for guiding the EUV target light and a measurement position for guiding stray light radiation towards the at least one stray light detector.

[0011] This type of monitoring device allows for stray light radiation measurement via a mirror surface of the illumination optics mirror that is actually used for the EUV useful light. Part of this useful mirror surface, or even the entire surface, can be equipped with corresponding individual mirrors that simultaneously guide the EUV useful light in the tilted position and guide stray light radiation in the tilted position for measurement. These tiltable detector mirrors can be faceted and / or micromirrors.

[0012] If, according to claim 2, the detection component itself is configured as the at least one stray light detector, a compact detector assembly can be implemented. Alternatively, the detection component can be configured as a guide component for the stray light radiation, directing at least a portion of the stray light radiation to the at least one stray light detector of the detector assembly. In this case, a compact guide component can be used, for example, a gold mirror or a stray light diffraction component, particularly an IR diffraction component, in particular in the form of a diffraction grating. The guide component can also be a component that serves to guide EUV useful light, for example, a facet and / or a micromirror of an illumination optic of the projection exposure system.By means of a plurality of, in particular spatially distributed, stray light detectors according to claim 3, a spatially resolved measurement of the intensity or energy distribution of stray light radiation across the illumination optics arrangement plane is possible. Since the illumination optics arrangement plane is conjugate to the collector arrangement plane, this spatially resolved measurement result can be converted into a corresponding spatially resolved measurement of the stray light suppression efficiency of the EUV collector. Collector degradation can then be monitored spatially across the collector area.

[0013] If multiple stray light detectors are used, they can be designed to detect the same or different stray light wavelength components. At least one of the majority of stray light detectors can, for example, be an IR detector. At least one other stray light detector can be an EUV detector, a UV detector, a VIS detector, or an out-of-band EUV detector. By using stray light detectors that can detect different stray light wavelength components, the condition of the EUV collector being monitored can be precisely determined. If multiple stray light detectors are used, they can be calibrated relative to each other beforehand.

[0014] An alternative embodiment according to claim 4 with exactly one stray light detector enables a simple design of the monitoring device, whereby, in particular, total stray light suppression by the EUV collector can be monitored. The exactly one stray light detector can be an IR detector. A detector arrangement according to claim 5 avoids unwanted shadowing of useful light by the stray light detectors. The individual mirrors can be faceted and / or micromirrors. The illumination optics mirror can be designed as a faceted mirror and / or as a MEMS mirror. The at least one stray light detector can be arranged between adjacent individual mirrors of the illumination optics mirror or also in the vicinity of a total individual mirror arrangement of the illumination optics mirror.

[0015] A recess according to claim 7 can, for example, be located in a central region of a single-mirror arrangement of the illumination optics mirror and can, in particular, be conjugated to a central collector through-opening, which, for example, can be provided for pump light. This recess in the illumination optics mirror, which in particular does not serve the EUV useful light guidance, can then be advantageously used for stray light detection purposes.

[0016] In an optical assembly according to claim 9, fine-tuning between the monitoring device and the EUV collector can already take place during the assembly phase of the monitoring device.

[0017] The advantages of an optical assembly according to claims 10 or 11 correspond to those already explained above. This also applies to a projection exposure system according to claim 12.

[0018] The illumination optics and / or projection optics can be components of the projection exposure system. The projection exposure system can include an EUV light source with an IR pump light source. In this case, the monitoring device, in its version with at least one IR detector, is particularly effective. An alternatively designed EUV light source, in which stray light radiation, especially IR radiation, is used or generated during EUV generation, can also be monitored using the monitoring device.

[0019] The advantages of a monitoring method according to claim 13 correspond in particular to those already explained above in connection with the monitoring device with a plurality of tiltable detector mirrors. The monitoring method is particularly advantageous when operating an EUV light source using an IR pump light source and an optical assembly with a monitoring device comprising at least one IR detector.

[0020] The measured proportion of stray light radiation may then be IR radiation from the IR pump light source.

[0021] The monitoring method according to claim 14 enables the comparability of measurements at different times and / or when using different EUV collectors by standardizing the monitoring result "false light emission distribution". This can be particularly useful in the search for systematic causes of degradation.

[0022] The advantages of a manufacturing process according to claim 15 and of a micro- or nano-structured component produced therein according to claim 16 correspond to those already explained above. Particularly good projection exposure results can be achieved by monitoring the collector during operation of the projection exposure system. Monitoring the EUV collector during operation of the projection exposure system can be carried out using one of the monitoring methods discussed above.

[0023] The projection exposure system can be used to manufacture, in particular, a semiconductor component, for example a memory chip.

[0024] Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. This drawing shows:

[0025] Fig. 1 schematically shows a projection exposure system for EUV microlithography;

[0026] Fig. 2 Details of a light source of the projection exposure system in the vicinity of an EUV collector for guiding EUV useful light from a plasma source area to a field facet mirror of an illumination optic of the projection exposure system, wherein the EUV collector is shown in a meridional section;

[0027] Fig. 3 shows a top view of an embodiment of the field facet mirror as an example of an illumination optics mirror, illustrating exemplary arrangement positions of IR detectors of a monitoring device for monitoring the EUV collector in an illumination optics arrangement plane that simultaneously represents the field facet arrangement plane; Fig. 4 shows, in a top view similar to Fig. 3, another embodiment of an illumination optics mirror that can be used instead of the field facet mirror according to Fig. 3, also illustrating arrangement positions for IR detectors of another embodiment of the monitoring device; and

[0028] Fig. 5 schematically and perspectivally shows the main components for guiding an EUV useful light beam path between an intermediate focus and a pupil facet mirror of an embodiment of the illumination optics, wherein a field facet of a field facet mirror of the illumination optics, which in turn represents an illumination optics mirror, is illustrated in a measuring tilt position for guiding IR radiation to an IR detector of a further embodiment of the monitoring device.

[0029] A projection exposure system 1 for microlithography has a light source 2 for illumination light or imaging light 3, which will be explained in more detail below. The light source 2 is an EUV light source that generates light in a wavelength range, for example, between 5 nm and 30 nm, and in particular between 5 nm and 15 nm. The illumination or imaging light 3 is also referred to below as EUV working light.

[0030] The light source 2 can be, in particular, a light source with a wavelength of 13.5 nm or a light source with a wavelength of 6.9 nm. Other EUV wavelengths are also possible. A beam path of the illumination light 3 is shown in a highly schematic way in Fig. 1. If EUV useful light with a wavelength of 13.5 nm is to be used within the projection exposure system 1, a wavelength component in the range of 6.9 nm is an out-of-band false-light wavelength component.

[0031] To guide the illumination light 3 from the light source 2 to an object field 4 in an object plane 5, an illumination optic 6 is used. The latter comprises, as illumination optic mirrors, a field facet mirror FF (shown highly schematically in Fig. 1) and a pupil facet mirror PF (also shown highly schematically) located downstream in the beam path of the illumination light 3. Between the pupil facet mirror PF, which is arranged in a pupil plane 6a of the illumination optic, and the object field 4, a field-shaping mirror 6b for grazing incidence (Gl mirror, grazing incidence mirror) is arranged in the beam path of the illumination light 3. Such a Gl mirror 6b is not strictly necessary.

[0032] The pupil facets of the pupil facet mirror PF (not shown in detail) are part of a transmission optic that superimposes the field facets of the field facet mirror FF (also not shown) onto the object field 4 and, in particular, images them. An embodiment known from the prior art can be used for the field facet mirror FF on the one hand and the pupil facet mirror PF on the other. Such an illumination optic is known, for example, from DE 10 2009 045 096 AL.

[0033] Using a projection optic or imaging optic 7, the object field 4 is projected onto an image field 8 in an image plane 9 at a predetermined reduction scale. Projection optics suitable for this purpose are known, for example, from DE 10 2012 202 675 AL. To facilitate the description of the projection exposure system 1, a Cartesian xyz coordinate system is shown in the drawing, from which the respective positional relationship of the components shown in the figures can be derived. In Fig. 1, the x-direction runs perpendicular to the drawing plane and into it. The y-direction runs to the left in Fig. 1, and the z-direction runs upwards in Fig. 1. The object plane 5 runs parallel to the xy-plane.

[0034] Object field 4 and image field 8 are rectangular. Alternatively, object field 4 and image field 8 can also be curved, specifically partially ring-shaped. Object field 4 and image field 8 have an xy aspect ratio greater than 1. This means that object field 4 has a longer object field dimension in the x-direction and a shorter object field dimension in the y-direction. These object field dimensions run along the field coordinates x and y.

[0035] For the projection optics 7, one of the embodiments known from the prior art can be used. Here, a section of a lithographic mask in the form of a reflection mask 10, also referred to as a reticulum, is projected, coinciding with the object field 4. The reticulum 10 is supported by a reticulum holder 10a. The reticulum holder 10a is moved by a reticulum displacement drive 10b.

[0036] The projection optics 7 project an image onto the surface of a substrate 11 in the form of a wafer, which is supported by a substrate holder 12. The substrate holder 12 is moved by a wafer or substrate transfer drive 12a. Figure 1 schematically shows a beam 13 of the illumination light 3 entering the projection optics 7 between the reticle 10 and the projection optics 7, and a beam 14 of the illumination light 3 exiting the projection optics 7 between the projection optics 7 and the substrate 11. The image-side numerical aperture (NA) of the projection optics 7 is not shown to scale in Figure 1.

[0037] Projection exposure system 1 is of the scanner type. Both the reticulum 10 and the substrate 11 are scanned in the y-direction during operation of projection exposure system 1. A stepper type of projection exposure system 1 is also possible, in which the reticulum 10 and the substrate 11 are moved stepwise in the y-direction between individual exposures of the substrate 11. These movements are synchronized with each other by appropriate control of the movement drives 10b and 12a.

[0038] Fig. 2 shows details of light source 2.

[0039] Light source 2 is an LPP source (laser-produced plasma). For plasma generation, tin droplets 15 are produced as a continuous droplet sequence by a tin droplet generator 16. The trajectory of the tin droplets 15 runs perpendicular to a main beam direction 17 of the EUV useful light 3. The tin droplets 15 fly freely between the tin droplet generator 16 and a tin collector 18, passing through a plasma source region 19. The EUV useful light 3 is emitted from the plasma source region 19. In the plasma source region 19, the arriving tin droplet 15 is stimulated by pump light 20 from a pump light source 21. The pump light source 21 can be an infrared laser source, for example, a CCE laser. Another IR laser source is also possible, in particular a solid-state laser, for example an Nd:YAG laser.

[0040] The pump light 20 can have an IR wavelength in the range between 10.1 pm and 10.7 pm. Depending on the design of the pump light source 21, the pump light 20 can alternatively or additionally also have a wavelength in the range of 1 pm, for example, 1.064 pm.

[0041] Another pump light wavelength, which then represents a false light wavelength, in the IR, NIR, VIS, UV or DU V wavelength range is also possible.

[0042] In addition to the EUV useful light 3, other, undesired stray light wavelength components are also emitted from the plasma source area 19 in the form of stray light radiation. This stray light radiation has a stray light wavelength that differs from the useful light wavelength of the EUV useful light 3 by at least 10%. The stray light wavelength can be the pump light 20. Alternatively or additionally, the stray light wavelength can be an EUV wavelength, a DU V wavelength, a UV wavelength, a VIS wavelength, a NIR wavelength, or an out-of-band EUV wavelength.

[0043] The pump light 20 is directed into the plasma source area 19 via a mirror 22, which can be a controllably tiltable mirror, and a focusing lens 23. The pump light causes the tin droplet 15 arriving in the plasma source area 19 to be transformed into a plasma emitting the EUV useful light 3. A beam path of the EUV useful light 3 is shown in Fig. 2 between the plasma source area 19 and the field facet mirror FF, insofar as the EUV useful light is reflected by a collector mirror 24, which is hereinafter also referred to as the EUV collector 24. The EUV collector 24 has a central aperture 25 for the pump light 20, which is focused towards the plasma source area 19 via the focusing lens 23.The collector 24 is designed as an ellipsoidal mirror and transfers the EUV useful light 3 emitted by the plasma source area 19, which is arranged in one ellipsoidal focal point, to an intermediate focus 26 of the EUV useful light 3, which is arranged in the other ellipsoidal focal point of the collector 24.

[0044] The base body of the EUV collector 24 can be made of SiSiC or aluminum. Alternative materials for this base body are copper, alloys containing copper and / or aluminum, or powder metallurgy alloys of copper and aluminum oxide.

[0045] The EUV collector 24 has a collector area designed such that, in a desired target state, the suppression of the pump light 20 reaching the intermediate focus 26 is better than 1 x 10'. 4 and especially in the range of lx 10' 5Local degradation of this pump light guide structure can negatively affect this suppression ratio, which is monitored by the monitoring device. Such degradation can occur, for example, through the deposition of plasma debris on the collector surface. Alternatively or additionally, such degradation can occur due to local damage to a collector grid structure caused by the operation of the light source 2. A monitoring device serves to monitor a condition, in particular the IR reflectivity across a collector surface of the EUV collector 24. Implementations of the monitoring device are explained in more detail below with reference to Fig. 3 ff.

[0046] The field facet mirror FF is arranged in the beam path of the EUV useful light 3 after the intermediate focus 26 in the area of ​​a femfield of the EUV useful light 3.

[0047] The EUV collector 24 and other components of the light source 2, which may include the tin droplet generator 16, the tin collector 18, and the focusing lens 23, are arranged in a vacuum housing 27. The vacuum housing 27 has a through-opening 28 in the region of the intermediate focus 26. In the region of the entry of the pump light 20 into the vacuum housing 27, the latter has a pump light entry window 29.

[0048] Fig. 3 shows an embodiment of the field facet mirror FF. This has a field facet module 30 with a total of five column-wise arranged field facet bars 3 h to 3 U. Each of the field facet bars 3 L comprises a plurality of field facets 32. Several of the adjacent field facets 32 of one of the field facet bars 3 L are grouped together to form a field facet block 33.

[0049] Between adjacent field facet blocks 33 within each of the field facet bars 3L, there is a free space along the y-coordinate. Between adjacent field facet bars 3L, there is a free space along the x-coordinate. The field facet bars 3L are mounted on a facet support body 34 of the field facet mirror FF. A round outer edge 35 of the facet support body 34, as shown, projects beyond the overall contour of the field facet bars 31, so that there is a further free space between the outermost field facets 32 and this outer edge 35.

[0050] The x-spaces between adjacent field facet bars 3 E, the yZ-spaces between adjacent field facet blocks 33, and the edge area 36 can be used to arrange detection components of a detector device 38 of a monitoring device 39 designed as false-light detectors 37, in particular as IR detectors, which serves to monitor a condition, for example a false-light reflectivity distribution, in particular an IR reflectivity distribution, over the collector area of ​​the EUV collector 24.

[0051] The stray light detectors 37 can be sensitive to at least one of the following stray light wavelength ranges: IR, NIR, VIS, UV, DUV, EUV (out-of-band). Several such stray light detectors 37 can be used. If several stray light detectors are used, they can be pre-calibrated. Such calibration can be repeated at predetermined intervals, for example, daily, weekly, or monthly. Stray light detectors are explained in more detail below using IR detectors as an example.

[0052] Fig. 3 illustrates various possible arrangements for the IR detectors 37i. The IR detectors 37i, 372, and 37s are arranged in the edge region 36. The IR detector 374 is arranged between the field facet bars 3U and 3h. The IR detector 375 is arranged between the field facet bars 313 and 314. The IR detector 37e is arranged between two adjacent field facet blocks 33 of the field facet bar 3h.

[0053] The IR detectors 37i can be designed as pyroelectric detectors.

[0054] The IR detectors 37i are all arranged in an arrangement plane 40 of the field facet mirror FF. This arrangement plane 40 represents an illumination optics arrangement plane that is optically conjugated to a collector arrangement plane 41 of the EUV collector 24. A spatially resolved measurement, in particular of useful light or pump light parameters, in the illumination optics arrangement plane 40 accordingly enables a spatially resolved inference about a state of the EUV collector 24 that is responsible for this measured parameter. Both the illumination optics arrangement plane 40 and the collector arrangement plane 41 can be a field plane of the illumination optics 6.

[0055] Using the IR detectors 37i, a network of measurement positions of IR reflectivities on the collector surface of the EUV collector 24 can be measured. Interpolation then allows conclusions to be drawn about the entire IR reflectivity distribution across the collector surface of the EUV collector 24. In an alternative embodiment of the monitoring device 39, the detection components arranged in the illumination optics assembly plane 40 are not designed as IR detectors, but as IR guide components that direct at least a portion of the IR light to be measured towards an IR detector of the detector assembly 38. Such an IR guide component can be designed as a mirror, in particular as a gold mirror.

[0056] Insofar as, in such an alternative design, a false light guiding component is placed upstream of the respective false light detector in the beam path of the false light, a calibration of the respective false light detector including the associated false light guiding component can be carried out when using several false light detectors, as already explained above.

[0057] Fig. 4 illustrates a further embodiment of an arrangement of IR detectors 37i for another embodiment of an illumination optics mirror 42, which can be used instead of the field facet mirror FF in the illumination optics 6. The illumination optics mirror 42 has a densely packed arrangement of individual mirrors 43, which can be designed as micromirrors and, in particular, as MEMS mirrors. A MEMS system with at least one such MEMS mirror is known from DE 10 2023 204 477 AE.

[0058] Figure 4 shows an example of a regular xy grid or array of square-bordered individual mirrors 43. Other grid patterns are also possible, as is a block arrangement of several individual mirror units, each of which can have, for example, sixteen, twenty-five, thirty-six, forty-nine, sixty-four, eighty-one, one hundred, or even more individual mirrors 43. Such blocks of individual mirrors can, in turn, be arranged in an array, with one row and one column direction of this block array arrangement running at an angle to the x and y coordinates, for example, at an angle of 37° or 45°.

[0059] The arrangement of the individual mirrors 43 has a central recess 44 in which no individual mirrors are present.

[0060] Fig. 4 again illustrates the arrangement positions of IR detectors 37i of another embodiment of the monitoring device. A total of eight IR detectors 37i to 37s are arranged equidistantly around a complete arrangement of individual mirrors 43. In the exemplary representation shown in Fig. 4, this arrangement of individual mirrors 43 has a round border, but it can also have a different border shape, for example rectangular, oval, elliptical, hexagonal, or other polygonal shapes.

[0061] Another of the IR detectors 37i, namely the IR detector 37, is arranged in the central recess 44 of the single-mirror arrangement.

[0062] In the embodiment according to Fig. 4, the IR detectors 37i can be arranged on a support structure 45 of the illumination optics mirror 42, which is only indicated in Fig. 4 and can be designed in the manner of the faceted support body 34 of the field faceted mirror FF according to Fig. 3.

[0063] The IR detectors 37i can in turn be part of a monitoring device of the type of monitoring device 39. With reference to Fig. 5, a further embodiment of a monitoring device 46 is described below, which can be used alternatively or additionally to the monitoring device 39 for monitoring the EUV collector 24. Components and functions corresponding to those already explained above with reference to Figs. 1 to 4 bear the same reference numerals and are not discussed in detail again below.

[0064] In the embodiment shown in Fig. 5, the field facets 32 of a field facet mirror FF of an illumination optic 6 are configured as individual detector mirrors and thus as detection components of the monitoring device 46 in the form of guide components for the pump light 20. The individual detector mirrors 32 are tiltable between a functional tilting position for guiding the EUV functional light 3 and a measuring tilting position for guiding the IR radiation, i.e., for example, the pump light 20, towards at least one IR detector 47i of the monitoring device 46. The field facets 32 as individual detector mirrors constitute detection components of the monitoring device 46 in the form of pump light guide components that guide a portion of the pump light 20 incident on the field facet mirror FF to at least one of the IR detectors 47i.

[0065] Fig. 5 shows exactly one of the detector mirrors 32, namely the field facet 32M, in the measuring tilt position, in which a partial beam of the pump light 20 incident on this field facet 32M, highlighted in Fig. 5, is directed towards the IR detector 47i. In the embodiment according to Fig. 5, exactly two IR detectors 47i and 472 are present. The IR detectors 47i are located in an arrangement plane of the pupil facet mirror PF adjacent to a pupil arrangement of the pupil facet mirror PF with pupil facets 48. The number of IR detectors 37i and 47i can range from one to several hundred. Depending on the coverage of the illumination optics arrangement plane, a more accurate picture of a spatially resolved state of the collector surface of the EUV collector is obtained, in particular a picture of its IR reflectivity over the collector surface.

[0066] Together with the respective version of the monitoring device 39 or 46, the illumination optics mirror FF or 42 is part of an optical assembly.

[0067] The following procedure is used to monitor the EUV collector 24 of the projection exposure system 1 using the monitoring device 46: During operation of the EUV light source 2 using the IR pump light source 21, at least one of the detector mirrors 32 is tilted between the operating tilt position and the measuring tilt position. A measurement component of the IR radiation 20 from the pump light source 21, carried along with the detector mirror 32M tilted into the measuring tilt position, is detected by the associated IR detector 47i, and this measurement component of the IR radiation 20 is assigned to a position of this detector mirror 32 tilted into the measuring tilt position in the arrangement plane, i.e., to the xy coordinates of the detector mirror 32M within an entire field facet arrangement.

[0068] These procedural steps of “tilting” and “capturing” are then repeated for selected or all detector individual mirrors, i.e., for example, all field facets 32. From the captured and assigned xy-coordinates of the measurement components of the IR radiation 20, an IR emission distribution of the pump light 20 can then be determined via the corresponding x- and y-coordinates of the collector area of ​​the EUV collector 24.

[0069] A two-dimensional IR emission distribution, and consequently a two-dimensional IR reflectivity of the EUV collector surface, can then be derived. In particular, disturbances in an IR light guiding structure applied to the collector surface, such as a diffraction structure, can be determined with spatial resolution in this way. This diffraction structure is designed such that the pump light 20 is deflected into an area spaced away from the intermediate focus 26. A pump light trap can be arranged there, particularly in an annular region around the intermediate focus.

[0070] Depending on this measurement result, an illumination correction can then be carried out, or countermeasures, in particular maintenance or repair measures, can be implemented. Specifically, illumination channels that are guided via individual mirrors or field facets, in which a high and undesirable pump light load exists due to a correspondingly measured measurement light component, can be selectively deactivated within the illumination optics 6. For this purpose, the field facets 32 or the individual mirrors 43 can be selectively moved into a neutral tilt position, in which the light component guided via these individual mirrors or field facets is selectively directed to a light trap. To prepare for the countermeasures or the maintenance or repair, the monitoring procedure identifies the position of collector surface sections whose IR suppression is worse than a predefined tolerance value.

[0071] To produce a micro- or nanostructured component, the projection exposure system 1 is used as follows: First, the reflection mask 10 or the reticle and the substrate or wafer 11 are provided. Then, a structure on the reticle 10 is projected onto a photosensitive layer of the wafer 11 using the projection exposure system 1. Developing the photosensitive layer then creates a micro- or nanostructure on the wafer 11, thus producing the microstructured component.

[0072] During operation of the projection exposure system 1, the condition of the EUV collector 24, in particular its local distribution of IR reflectivity across the collector surface, is monitored using at least one of the monitoring device versions described above. If the monitoring reveals a degradation of the EUV collector 24 beyond a predetermined tolerance value, especially for IR suppression, either the illumination optics 6 can be reconfigured or the projection exposure system 1 can be shut down for maintenance or repair. In particular, the EUV collector 24 can then be replaced.

Claims

Patent claims 1. Optical assembly with a monitoring device (39; 46) for monitoring an EUV collector (24) of a projection exposure system (1), — with a detector device (38) having at least one false-light detector (37i; 47i) for detecting false-light radiation (20) with a false-light wavelength that differs from a useful light wavelength of useful light (3) generated by an EUV light source (2) by at least 10%, wherein the false-light radiation (20) emanating from a component (21) of the EUV light source (2) is reflected at a collector surface of the EUV collector (24), — wherein a detection component (37; 32) of the detector device (38) is located in an illumination optics arrangement plane (40) can be arranged to form a collector arrangement plane (41) of the EUV collector (24) is optically conjugated to an illumination optics mirror (FF; 42) arranged in the illumination optics arrangement plane (40), wherein the illumination optics mirror (FF) comprises a plurality of tiltable detector mirrors (32) as detection components of the monitoring device (46), wherein the detector mirrors (32) are tiltable between — a useful tilting position for guiding EUV useful light (3) and — a measuring tilt position for guiding the false light radiation (20) towards at least one false light detector (470).

2. Optical assembly according to claim 1, characterized in that the detection component of the monitoring device is designed as the at least one false light detector (37i).

3. Optical assembly according to claim 1 or 2, characterized by a plurality of false light detectors (37i; 470.

4. Optical assembly according to claim 1 or 2, characterized by exactly one false light detector (37; 47).

5. Optical assembly according to one of claims 1 to 4, characterized in that the illumination optics mirror (FF; 42) has a plurality of individual mirrors (32; 43), wherein the at least one false light detector (37i) is arranged on a support structure (34; 45) for the individual mirrors (32; 43).

6. Optical assembly according to claim 5, characterized in that the individual mirrors are facets and / or micromirrors.

7. Optical assembly according to one of claims 1 to 6, characterized in that the illumination optics mirror (42) has a recess (44) within a single mirror arrangement in which at least one false light detector (37) of the monitoring device (39) is arranged.

8. Optical assembly according to one of claims 1 to 7, characterized in that a part of a useful mirror surface of the illumination optics mirror, which is used to guide the useful light (3), or that the entire usable mirror surface is equipped with the tiltable individual detector mirrors.

9. Optical assembly according to one of claims 1 to 8, comprising the EUV collector (24) to be monitored.

10. Optical assembly according to one of claims 1 to 9, characterized by an illumination optic (6) for illuminating an object field (4) in which an object (10) to be imaged can be arranged, with EUV useful light (3).

11. Optical assembly according to claim 10, characterized by a projection optic (7) for imaging the object field (4) into an image field (8) in which a substrate (11) can be arranged, onto which a section of the object (10) to be imaged is to be imaged.

12. Projection exposure system (1) with an optical assembly according to claim 11 and with an EUV light source (2).

13. Method for monitoring an EUV collector (24) of a projection exposure system (1) using an optical assembly according to one of claims 1 to 11, comprising the following steps: Operating the EUV light source (2) of the projection exposure system (1), Tilting each of the detector mirrors (32) between the useful tilting position and the measuring tilting position, Detecting a measurement component of false light radiation (20) carried along with the detector single mirror (32) tilted into the measuring tilt position and assigning the measurement component to the position of the detector single mirror (32) tilted into the measuring tilt position in the illumination optics arrangement plane (40), repeating the “tilting” and “capturing” steps for selected or all detector single mirrors (32).

14. Method according to claim 13, characterized by determining a false light emission distribution over a collector area of ​​the EUV collector (24) from the detected and assigned measurement components of the false light radiation (20).

15. Method for manufacturing a structured component comprising the following process steps: Providing a reticulum (10) and a wafer (11), projecting a structure on the reticulum (10) onto a photosensitive layer of the wafer (11) using the projection exposure system according to claim 12, Generating a micro- and / or nanostructure on the wafer (11), wherein an EUV collector (24) is monitored during the operation of the projection exposure system.

16. Structured component, manufactured according to a method according to claim 15.

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