Method for operating an optical system of a lithography projection exposure system

Abstract

For the operation of an optical system of a lithography projection exposure system with an illumination optic and a projection optic with at least one pupil-near or field-near component, a target illumination angle distribution for the illumination of an object field with illumination light is specified (25). At least two mutually perpendicular illumination angle distribution symmetry planes, with respect to which the target illumination angle distribution is mirror-symmetric, are determined (26). Starting from the specified target illumination angle distribution, an actual illumination angle distribution is specified (29). This is done such that the actual intensity of the at least one pupil-near or field-near optical component is mirror-symmetric with respect to two component symmetry planes within specified tolerance limits.The illumination light is transferred from the illumination angle distribution symmetry planes to the component symmetry planes. This results in optimized object illumination that can be achieved with such a projection exposure system.

Description

[0001] The invention relates to a method for operating an optical system of a lithography projection exposure system. Furthermore, the invention relates to an optical system operated by means of such a method, a projection exposure system with such an optical system, a method for producing a micro- or nanostructured component by means of such a projection exposure system, and a micro- or nanostructured component produced by means of such a manufacturing method.

[0002] A projection exposure system for microlithography is known, for example, from US 9,411,239 B2. Exposure methods are also known from US 8,415,077 B2, US 8,910,091 B2, US 7,523,439 B2, US 7,759,253 B2, and US 10,996,567 B2. An illumination optic comprising a transmission optic and at least one downstream illumination preset facet mirror is known from WO 2015 / 036226 A1, WO 2010 / 099807 A1, and US 2006 / 0132747 A1.

[0003] It is an object of the present invention to optimize object exposure that can be carried out with such a projection exposure system.

[0004] This problem is solved according to the invention by a multiple exposure method with the features specified in claim 1.

[0005] According to the invention, it has been recognized that the actual intensity applied to at least one pupil-near or field-near optical component of a projection optic in a lithography projection exposure system is a critical parameter for achieving an exposure result that meets the highest requirements. By symmetrizing the actual intensity applied to the at least one pupil-near or field-near optical component, thermally induced drift errors due to heating of the optical component from residual absorption of the imaging light during exposure, or thermally induced drift errors due to cooling of the optical component during at least one exposure interval, can be reduced or even completely avoided.

[0006] The optical component of the projection optics is close to the pupil when the subapertures of spaced-apart field points strongly overlap on the optical component. This is parameterized by a parameter P, which is defined in WO 2009 / 024 164 A1. An optical component of the projection optics is close to the pupil when: P ≥ 0.6, in particular P ≥ 0.65, P ≥ 0.7, P ≥ 0.75 or also P ≥ 0.8.

[0007] The optical component of the projection optics is considered near the field if the subapertures of spaced-apart field points on the optical component are at least predominantly separated from one another. An optical component of the projection optics is considered near the field if, again using the definition from WO 2009 / 024 164 A1, the following applies: P ≤ 0.4, in particular P ≤ 0.35, P ≤ 0.3, P ≤ 0.25 or also P ≤ 0.2.

[0008] A symmetrical actual intensity distribution of an optical component near the pupil is particularly advantageous when using a multi-pole illumination setup. A symmetrization of the actual illumination angle distribution of an optical component near the field is particularly advantageous when undesired asymmetries arise due to diffraction effects of the object being imaged, which can be corrected using this method.

[0009] Within the specified tolerance limits, the actual intensity applied to at least one optical component near the pupil or field is mirror-symmetric with respect to the two component symmetry planes. For example, the deviation from a perfectly mirror-symmetric intensity can be no more than 5%, no more than 3%, no more than 2%, no more than 1%, or even no more than 0.5%. Even smaller tolerance limits are possible. Typically, the tolerance limit is greater than 1 x 10⁻⁶. -4 .

[0010] Specifying the actual illumination angle distribution by simulation according to claim 2 and / or by measurement according to claim 3 has proven effective in practice.

[0011] The advantages of an optical system according to claim 4 correspond to those already explained above with reference to the operating method.

[0012] A projection optic according to claim 5 can be used in particular in connection with an EUV projection exposure system.

[0013] This applies accordingly to an illumination optic according to claim 6. As an alternative to an illumination optic with a field facet mirror and a pupil facet mirror, an illumination optic designed as a specular reflector can also be used.

[0014] By means of a measuring device according to claim 7, the measuring step of the method according to claim 3 can be carried out within the optical system.

[0015] The measuring device according to claim 8 can alternatively or additionally be used to directly measure the actual illumination angle distribution.

[0016] The advantages of a projection exposure system according to claim 9, a manufacturing process according to claim 10, and a micro- or nanostructured component according to claim 11 correspond to those already explained above with reference to the operating method and the optical system. The component may be a microchip, in particular a memory chip.

[0017] The light source of the projection exposure system can be an EUV light source or a DUV light source.

[0018] At least one embodiment of the invention is described below with reference to the drawing. The drawing shows: Fig. 1 schematically in meridional section a projection exposure system for EUV projection lithography; Fig. 2 a top view of a field facet mirror of an illumination optic of the projection exposure system, which represents a first facet mirror and is arranged in a field plane in an illumination light far field; Fig. 3 a top view of a second faceted mirror of the illumination optics, which may be designed as a pupil faceted mirror arranged in a pupil plane of the illumination optics or as a specular faceted mirror arranged at a distance on the one hand from a field plane and on the other hand from a pupil plane of the illumination optics; Fig. 4 a flow diagram of an operating procedure of an optical system of the projection exposure system, which includes the illumination optics for guiding illumination light along an illumination light beam path to an object field in which an object to be illuminated can be arranged, and a projection optics for imaging the object field along an imaging beam path into an image field in which a substrate to be structured can be arranged; Fig. 5 a raw-actual intensity application of a pupil-near optical component of the projection optics in the form of a mirror, represented as an x / y intensity distribution on a rectangular mirror section; Fig. 6 in one to Fig. 5. Similar representation: an actual intensity input of the pupil-near optical component, which, as a result of the operating procedure, is mirror-symmetric with respect to the component symmetry planes within specified tolerance limits, wherein the component symmetry planes correspond to illumination angle distribution symmetry planes of a specified target illumination angle distribution according to the guidance of the illumination light; and Fig. Figure 7 in a diagram shows the temporal dependence of an overlay error during the operation of the projection exposure system, on the one hand when the optical component near the pupil is exposed to the raw actual intensity exposure according to Fig. 5 and, on the other hand, when the optical component near the pupil is subjected to the symmetrical actual intensity subjection according to Fig. 6.

[0019] The following will first refer to the Fig. 1. The essential components of a projection exposure system 1 for microlithography are described as an example. The description of the basic structure of the projection exposure system 1 and its components is not to be understood as restrictive.

[0020] One embodiment of a lighting system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, a lighting optic 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the lighting system. In this case, the lighting system does not include the light source 3.

[0021] An object arranged in the object field 5 is exposed, using a reticulum 7 as an example. The reticulum 7 is held by a reticulum or object holder 8. The reticulum holder 8 can be moved, particularly in one scanning direction, via a reticulum or object displacement drive 9.

[0022] In the Fig. Figure 1 shows a Cartesian xyz coordinate system for illustrative purposes. The x-direction runs perpendicular to the plane of the drawing. The y-direction runs horizontally, and the z-direction runs vertically. The scan direction runs in the Fig. 1 along the y-direction. The z-direction runs perpendicular to the object plane. 6.

[0023] The projection exposure system 1 comprises a projection optic 10. The projection optic 10 serves as an imaging optic for imaging the object field 5 into an image field 11 in an image plane 12. The image plane 12 is parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

[0024] A structure on the reticulum 7 is imaged onto a photosensitive layer of a wafer 13 located in the image plane 12 within the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be moved, particularly along the y-direction, via a wafer transfer drive 15. The movement of the reticulum 7 via the reticulum transfer drive 9 and of the wafer 13 via the wafer transfer drive 15 can be synchronized.

[0025] Radiation source 3 is an EUV radiation source. Radiation source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. If the illumination light 16 is guided by the projection optics 10, it is also referred to as imaging light. The useful radiation has a wavelength in the range between 5 nm and 30 nm. Radiation source 3 can be a plasma source, for example, an LPP source (laser-produced plasma) or a DPP source (gas-discharged produced plasma). It can also be a synchrotron-based radiation source. Radiation source 3 can be a free-electron laser (FEL).

[0026] The illumination radiation 16 emanating from the radiation source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and / or hyperboloid reflective surfaces. The at least one reflective surface of the collector 17 can be illuminated with the illumination radiation 16 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 17 can be structured and / or coated to optimize its reflectivity for the useful radiation and to suppress stray light.

[0027] After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the radiation source 3 and the collector 17, and the illumination optics 4.

[0028] The lighting optics 4 comprise a deflecting mirror 19 and, downstream in the beam path, a first faceted mirror 20, which is located in the Fig. 2 is shown in a top view. The deflecting mirror 19 can be a planar deflecting mirror or, alternatively, a mirror with an effect that influences the beam beyond the mere deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first faceted mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugate to the object plane 6 as a field plane, it is also referred to as a field faceted mirror. The first faceted mirror 20 comprises a plurality of individual first facets 21, which are also referred to as field facets in the following. Of these facets 21, the Fig. 1 only some examples are shown.

[0029] The first facets of 21 can, as in the Fig. Figure 2 illustrates that the facets can be executed as macroscopic facets, in particular as rectangular facets or also as facets with an arcuate or semicircular edge contour. The first facets 21 can be executed as planar facets or alternatively as convexly or concavely curved facets.

[0030] As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 can themselves each be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 20 can in particular be designed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1.

[0031] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction.

[0032] In the beam path of the lighting optics 4, a second faceted mirror 22 is arranged downstream of the first faceted mirror 20, which is located in the Fig. Figure 3 is shown in a schematic top view. If the second faceted mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil faceted mirror. The second faceted mirror 22 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first faceted mirror 20 and the second faceted mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1 614 008 B1, and US 6,573,978.

[0033] 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.

[0034] The second facets 23 can also be macroscopic facets, which may, for example, have round, rectangular, or hexagonal edges, or alternatively, facets composed of micromirrors. Reference is also made to DE 10 2008 009 600 A1 in this regard.

[0035] The second facets 23 can have planar or alternatively convex or concave curved reflective surfaces.

[0036] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (Fly's Eye Integrator).

[0037] It can be advantageous not to arrange the second faceted mirror 22 exactly in a plane that is optically conjugate to a pupil plane of the projection optics 10. In particular, the pupil faceted mirror 22 can be arranged tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 10 2017 220 586 A1.

[0038] With the aid of the second faceted mirror 22, the individual first facets 21 are imaged into the object field 5. The second faceted mirror 22 is the last beam-shaping, or indeed the last, mirror for the illumination radiation 16 in the beam path before the object field 5.

[0039] In another embodiment of the illumination optics 4, not shown, a transmission optic can be arranged in the beam path between the second facet mirror 22 and the object field 5, which contributes in particular to imaging the first facets 21 into the object field 5. The transmission optic can have exactly one mirror, or alternatively two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. 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).

[0040] The lighting optics 4, in the version shown in the Fig. Figure 1 shows exactly three mirrors after the collector 17, namely the deflecting mirror 19, the field facet mirror 20 and the pupil facet mirror 22.

[0041] In a further embodiment of the lighting optics 4, the deflecting mirror 19 can also be omitted, so that the lighting optics 4 after the collector 17 can then have exactly two mirrors, namely the first faceted mirror 20 and the second faceted mirror 22.

[0042] The mapping of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optic into the object plane 6 is regularly only an approximate mapping.

[0043] The projection optics 10 comprise a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0044] Mirror M3 of the projection optics 10 is a pupil-adjacent mirror. The plane of arrangement of mirror M3 is therefore close to a pupil plane of the optical system of the projection exposure unit 1.

[0045] The following applies to the pupillary mirror M3: P(M3)≥0.6

[0046] Regarding the definition of the parameter P characterizing pupil proximity, reference is made to WO 2009 / 024 164 A1.

[0047] In the Fig. In the example shown, the projection optics 10 comprise six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or any other number of mirrors Mi are also possible. The projection optics 10 is a doubly obscured optic. The penultimate mirror M5 and the last mirror M6 each have an aperture for the illumination radiation 16. The projection optics 10 has an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0048] The reflective surfaces of the mirrors Mi can be designed as freeform surfaces without an axis of rotational symmetry. Alternatively, the reflective surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflective surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0049] The projection optics 10 has a large object-image offset in the y-direction between a y-coordinate of a center of the object field 5 and a y-coordinate of the center of the image field 11. This object-image offset in the y-direction can be approximately as large as a z-distance between the object plane 6 and the image plane 12.

[0050] The projection optics 10 can be, in particular, anamorphic. They exhibit, in particular, different magnification ratios β. x , β y in the x and y directions. The two image scales β x , β y of the projection optics 10 are preferably located at (β x , β y ) = (+ / - 0.25, / +- 0.125). A positive magnification β indicates a transformation without image inversion. A negative sign for the magnification β indicates a transformation with image inversion.

[0051] The projection optics 10 thus lead to a reduction in the x-direction, that is, in the direction perpendicular to the scan direction, in a ratio of 4:1.

[0052] The projection optics 10 lead to a reduction of 8:1 in the y-direction, that is, in the scan direction.

[0053] Other magnification ratios are also possible. Magnification ratios with the same sign and absolute values ​​in the x and y directions, for example with absolute values ​​of 0.125 or 0.25, are also possible.

[0054] The number of intermediate image planes in the x- and y-directions in the beam path between the object field 5 and the image field 11 can be the same or, depending on the design of the projection optics 10, different. Examples of projection optics with different numbers of such intermediate images in the x- and y-directions are known from US 2018 / 0074303 A1.

[0055] Each pupil facet 23 is assigned to exactly one of the field facets 21 to form an illumination channel for illuminating the object field 5. This can result, in particular, in illumination according to Köhler's principle. The far field is divided into a multitude of object fields 5 by means of the field facets 21. The field facets 21 generate a plurality of images of the intermediate focus on the pupil facets 23 assigned to each of them.

[0056] The field facets 21 are each superimposed on the reticulum 7 by an associated pupil facet 23 to illuminate the object field 5. The illumination of the object field 5 is particularly homogeneous. It preferably exhibits a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0057] The illumination of the entrance pupil of the projection optics 10 can be geometrically defined by arranging the pupil facets 23 illuminated by the illuminating light 16. By selecting the illumination channels, in particular the subset of pupil facets that guide light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting or illumination pupil filling.

[0058] Another preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by a redistribution of the illumination channels.

[0059] Further aspects and details of the illumination of the object field 5 and, in particular, the entrance pupil of the projection optics 10 are described below.

[0060] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0061] The entrance pupil of the projection optics 10 cannot always be illuminated exactly by the pupil facet mirror 22. When the projection optics 10 image the center of the pupil facet mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found where the pairwise determined separation of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in real space. In particular, this surface exhibits a finite curvature.

[0062] The projection optics 10 may have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second faceted mirror 22 and the reticle 7. This optical element can accommodate the different positions of the tangential and sagittal entrance pupils.

[0063] During the Fig. In the arrangement of the components of the illumination optics 4 shown in Figure 1, the pupil facet mirror 22 is arranged in a plane conjugate to the entrance pupil of the projection optics 10. The field facet mirror 20 is arranged tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the deflecting mirror 19.

[0064] The first faceted mirror 20 is arranged at an angle to an arrangement plane defined by the second faceted mirror 22.

[0065] In the production of a micro- or nanostructured component using the projection exposure system 1, an operating procedure of an optical system comprising illumination optics 4 and the projection optics 10 of the projection exposure system 1 is used, which is described below based on the Fig. 4 to 7 will be explained.

[0066] In a predefined step 25 (see Fig. 4) Within this operating procedure, a target illumination angle distribution for the illumination of the object field 5 with the illumination light 16 is first specified. This target illumination angle distribution can be a y-dipole setting, i.e., a setting in which the illumination pupil of the optical system is illuminated by the illumination light 16 in the area of ​​two pole regions spaced apart along the y-direction. Other illumination settings are also possible, for example, an annular illumination setting, an x-dipole setting, or another dipole or multipole illumination setting. Examples of such illumination settings can be found, among others, in WO 2017 / 046 136 A1, WO 2012 / 028 303 A1, and DE 10 2008 021 833 A1.

[0067] In a subsequent step 26, at least two mutually perpendicular illumination angle distribution symmetry planes are determined, with respect to which the target illumination angle distribution is mirror-symmetric. In the case of a y-dipole setting, these are the illumination angle distribution symmetry planes xz on the one hand and yz on the other.

[0068] Additionally, in a fundamentally optional measurement step 27, the measurement of a raw actual intensity exposure 28 (see Fig. 5) on an optical component near the pupil.

[0069] Fig. Figure 5 shows a measurement result for such a raw-actual intensity exposure 28, shown via a section of the mirror M3 of the projection optics 10, which is arranged near the pupil. At the edge, in the Fig. Figure 5 provides an intensity legend that assigns relative intensity values ​​to the hatching patterns, which represent a distribution of the raw-actual intensity exposure 28. The raw-actual intensity exposure 28 exhibits a lower pole 281 with lower intensity (smaller absolute y-values) and a higher pole 282 with higher intensity (larger absolute y-values). This measured raw-actual intensity exposure 28 can be compared, either during measurement step 27 or in a subsequent step of the operating procedure, with a target intensity exposure of the pupil-near optical component M3, which depends on the specified target illumination angle distribution. In the case of a specified y-dipole setting as the target illumination angle distribution, the target intensity of the pupil-near optical component M3 is shaped accordingly.

[0070] This target intensity application is defined with respect to two component symmetry planes KS1 and KS2 (see Fig. 5) Mirror-symmetric within specified tolerance limits. These specified tolerance limits could, for example, be a deviation from a perfectly mirror-symmetric intensity application of no more than 3%, no more than 2%, no more than 1%, or even no more than 0.5%. Even smaller tolerance limits are possible.

[0071] In a further specification step 29 of the operating procedure, depending on the target illumination angle distribution specified in step 25, an actual illumination angle distribution is specified such that an actual intensity exposure 30 (cf. Fig. 6) The resulting optical component M3 near the pupil is mirror-symmetric with respect to the two component symmetry planes KS1 and KS2 within specified tolerance limits. The tolerance limits used here are the same as those explained above in connection with the tolerance limits in measurement step 27.

[0072] Fig. Figure 6 shows such a symmetrical actual intensity application 30 of the mirror M3. The illumination light 16 is transferred from the illumination angle distribution symmetry planes to the component symmetry planes xz, yz during the guidance process, starting from the illumination pupil, in which the target illumination angle distribution is specified in the specification step 25.

[0073] Fig. Figure 7 illustrates the effect of symmetrizing the actual intensity output 30 on the mirror M3 during the operating procedure. This is shown in the Fig. 7. A time progression of an overlay error (OV), specified in arbitrary units. Dashed lines indicate... Fig. 7. The temporal evolution of a raw overlay error (OV). R The image shows the result of applying the raw-actual intensity 28 to the near-pupil mirror M3. This raw-overlay error OV has a sawtooth-like pattern. R The values ​​between approximately 0.1 and 0.4 in the steady state result from an interplay of thermal expansion of the optical material of the components of the optical system during exposure to the illumination or imaging light 16 (each falling edge of the time course of the raw overlay error OV). R ) and a cooling of the optical components during the switch between successive exposure sequences (jump from "bottom" to "top" in the temporal course of the raw overlay error OV). R ).

[0074] It is consistently implemented in the Fig. Figure 7 shows the overlay error OV during the symmetrical actual intensity application 30 of the near-pupil mirror M3. Both the maximum value of this overlay error OV, which is in the range of 0.1, and the amplitude of a time course of the overlay error OV in the steady state, which is initially less than 0.05 and decreases further over time, are significantly smaller than the time course of the raw overlay error OV. R , as can be seen from a comparison of the solid overlay error curve OV with the dashed raw overlay error curve OV R in Fig. 7 results.

[0075] Alternatively or additionally to measurement step 27, the actual illumination angle distribution in specification step 29 can also be determined based on a simulation of the guidance of the illumination light 16 through the illumination optics 4, starting from the specified target illumination angle distribution, and / or based on a simulation of the guidance of the imaging light 16 through the projection optics 10. Such a simulation can be performed using known ray tracing programs.

[0076] The operating procedure for symmetrizing the actual intensity application was explained above using the example of an optical component near the pupil, namely the example of mirror M3.

[0077] Similarly, the operating procedure can also be used to symmetrize the actual intensity applied to a near-field optical component. This near-field optical component could, for example, be mirror M2 or mirror M4 of the imaging optics 10.

[0078] An initially asymmetric raw-actual intensity response of such a near-field optical component can arise, for example, due to a diffraction effect at reticle 7. This initially asymmetric raw-actual intensity response is also transformed, as explained above, into a mirror-symmetric actual intensity response within predefined tolerance limits when the operating procedure is carried out.

[0079] To perform measurement step 27, the optical system of the projection exposure system 1 includes a measuring device 31 for measuring the actual intensity exposure 28 or 30 of the at least one optical component near the pupil, for example, the mirror M3. The measuring device 31 can be designed as a thermal imaging camera.

[0080] The measuring device 31, or an additional measuring device of the optical system, can be configured alternatively or additionally for measuring the actual illumination angle distribution on the reticle 7 and / or on the wafer 13. For this purpose, the measuring device can be configured as a pinhole camera with a pinhole aperture arranged in the object plane 6 and / or the image plane 12 and with a CCD or CMOS array arranged in the subsequent beam path of the illumination or imaging light 16.

[0081] To produce a micro- or nanostructured component, the projection exposure system 1 is used as follows: First, the reflection mask 7 or the reticule and the substrate or wafer 13 are provided. Using the operating procedure described above, the projection exposure system 1 is used as follows: Fig. As explained in sections 4 to 7, the actual intensity of the light applied to at least one pupil-adjacent optical component of the projection optics 10 is symmetrized, as illustrated above using the example of mirror M3. Subsequently, a structure on the reticulum 7 is projected onto a photosensitive layer of the wafer 13 using the projection exposure system 1. Development of the photosensitive layer then creates a micro- or nanostructure on the wafer 13, thus generating the microstructured component. This process can be used to fabricate a semiconductor microchip, in particular a memory chip. 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] US 9,411,239 B2

[0002] US 8,415,077 B2

[0002] US 8,910,091 B2

[0002] US 7,523,439 B2

[0002] US 7,759,253 B2

[0002] US 10,996,567 B2

[0002] WO 2015 / 036226 A1

[0002] WO 2010 / 099807 A1

[0002] US 2006 / 0132747 A1 [0002, 0032] WO 2009 / 024 164 A1 [0006, 0007, 0046] DE 10 2008 009 600 A1 [0030, 0034] EP 1 614 008 B1

[0032] US 6,573,978

[0032] DE 10 2017 220 586 A1

[0037] US 2018 / 0074303 A1

[0054] WO 2017 / 046 136 A1

[0066] WO 2012 / 028 303 A1

[0066] DE 10 2008 021 833 A1

[0066]

Claims

[1] Method for operating an optical system (4, 10) of a lithography projection exposure apparatus (1), - with an illumination optics (4) for guiding illumination light (16) along an illumination light beam path to an object field (5) in which an object (7) to be illuminated can be arranged, - with a projection optics (10) for imaging the object field (5) along an imaging light beam path into an image field (11) in which a substrate (13) to be structured can be arranged, wherein the projection optics (10) has at least one near-pupil or near-field optical component (M3) for guiding the imaging light (16), with the following steps - specifying (25) a desired illumination angle distribution of an illumination of the object field (5) with the illumination light (16), - determining (26) at least two mutually perpendicular illumination angle distribution symmetry planes (xz, yz) with respect to which the desired illumination angle distribution is mirror-symmetrical, - starting from the predetermined target illumination angle distribution: specifying (29) an actual illumination angle distribution such that an actual intensity exposure (30) of the at least one near-pupil or near-field optical component (M3) is mirror-symmetrical with respect to two component symmetry planes (KS1, KS2) within predetermined tolerance limits, wherein the illumination light (16) is transferred from the illumination angle distribution symmetry planes (xz, yz) into the component symmetry planes (KS1, KS2). [2] Method according to claim 1, characterized bythat the specification (29) of the actual illumination angle distribution is carried out depending on a simulation of the guidance of the illumination light (16) through the illumination optics (4) based on the specified target illumination angle distribution and / or on the basis of a simulation of the guidance of the imaging light (16) through the projection optics (10). [3] Method according to claim 1 or 2, characterized by that the specification (29) of the actual illumination angle distribution is carried out as a function of a measurement (27) of a raw actual intensity application (28) on the near-pupil or near-field optical component (M3), which is compared with a target intensity application of the at least one near-pupil or near-field optical component (M3), which is dependent on the specified target illumination angle distribution and which is mirror-symmetrical with respect to the two component symmetry planes (KS1, KS2) within specified tolerance limits. [4] An optical system operated by a method according to any one of claims 1 to 3. [5] Optical system according to claim 4, characterized by a projection optics (10), in which the at least one optical component near the pupil or near the field is designed as a mirror (M3). [6] Optical system according to claim 4 or 5, characterized by an illumination optics (4) with a field facet mirror (20) and with a pupil facet mirror (22) for specifying the actual illumination angle distribution. [7] Optical system according to one of claims 4 to 6, characterized by a measuring device (31) for measuring the actual intensity exposure (28, 30) of the at least one near-pupil or near-field optical component (M3). [8] Optical system according to one of claims 4 to 7, characterized by a measuring device for measuring the actual illumination angle distribution. [9] Projection exposure system with an optical system according to one of claims 4 to 8 and with a light source (3) for the illumination light (16). [10] Method for producing a structured component by means of a projection exposure apparatus according to claim 9 using an operating method according to one of claims 1 to 3. [11] Component manufactured by a method according to claim 10.

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