Optical system for a projection exposure system and method for specifying an illumination pupil

Abstract

An optical system for a projection exposure system comprises an illumination optic for guiding illumination and imaging light (3) from a light source to an object field in which an object to be imaged can be arranged, and an imaging optic for imaging the object field into an image field in which a substrate to be exposed can be arranged. The imaging optic has an exit pupil (36) with at least one obscuration exit pupil area (38) located within an outer pupil margin (37). The illumination optic is designed such that an illumination angle distribution of the object field with the illumination and imaging light (3) results, which can be described by an illumination pupil (12a) whose illumination pupil area (I) exposed to illumination light is adapted to the obscuration exit pupil area (38) of the imaging optic.The obscuration exit pupil area (38) of the imaging optics can have a non-central geometric center of gravity (GC). In one variant of the optical system, the illumination optics are designed such that an illumination angle distribution results in the object field which can be described via an illumination pupil (12a) with an obscuration illumination pupil area (31) whose envelope deviates from a circular shape in pupil coordinates (x, y) normalized to the outer pupil margin (37) and / or in absolute pupil coordinates (x, y). To specify the illumination pupil (12a), a diffraction behavior of at least one object structure of the object to be imaged is analyzed, a position of the obscuration exit pupil area (38) in the exit pupil (36) is determined, and the illumination pupil (12a) is adjusted so that at least one of the variants of the optical system results.This results in an optical system with improved resolution.

Description

The invention relates to an optical system for a projection exposure apparatus. The invention further relates to a projection exposure apparatus having an optical system of this type, to a method for presetting an illumination pupil of an illumination optical system having an adapted illumination pupil, with the result that an optical system of this type results, to a method for producing a micro- or nanostructured component with the aid of an optical system of this type, and to a micro- or nanostructured component produced by the method.An optical system of the type mentioned at the beginning is known from WO 2012 / 028303 A1, U.S. Pat. No. 10,139,734 B2, U.S. Pat. No. 10,254,653 B2, DE 10 2021 200 114 A1 and U.S. Pat. No. 9,720,329 B2. Details of imaging optics which may be suitable for use in lithographic production exposure apparatus are known from the article by Levinson et al., "Lithographic pattern formation in the presence of aberrations in anamorphic optical systems", Proc. of SPIE Vol. 11323 1132230A-1, 2020 from the technical article de Winter et al., "Extreme ultraviolet scanner with high numerical aperture: observation and wavefront description", J. Micro / Nanopattern. Mater. Metrol. 023801-2, 2022 from the technical article by de Winter et al. "High NA EUV scanner: observation and wavefront description", Proc. of SPIE Vol. 11517 1151715-1, 2020 from the technical article by van Setten et al., "High NA EUV lithography: Next step in EUV imaging", Proc. of SPIE Vol. 10957 1095709-01, 2019, from the technical article by Peng et al., "Physical dose modeling and throughput optimization in EUV computational lithography", Proc. of SPIE Vol. 12494 124940C-1, 2023, from the technical article by Maguire et al., "Defining Tian-Zernike polynomials for use in a lithography simulator", Proc. Of SPIE Vol. 12494 124940P-1, 2023, from the technical article by Zhao et al., "Computational lithography solutions to support EUV high-NA patterning", Proc. Of SPIE Vol. 12495 124950R-1, 2023, from the technical article by van Schoot et al., "High-NA EUV lithography exposure tool: program progress", Proc. Of SPIE Vol. 11323 1132307-1, 2023, from the technical article by Schweimier et al., "High-NA EUV lithography optics results reality", Proc. Of SPIE Vol. 11323 1132308-1, 2020 from the technical article by van Schoot et al., "High-NA EUV lithography exposure tool: advances and program progress", Proc. Of SPIE Vol. 11517 1151712-1, 2020 from the technical article by Gao et al., "Computational evaluation of critical logical metal layers of pitch 20-24 nm and the aberration sensitivity in high NA EUV single patterning", Proc. Of SPIE Vol. 12495 1249509-1, 2023.It is an object of the present invention to improve a resolution capability of an optical system of the type mentioned at the beginning.The object is achieved according to the invention by an optical system having the features specified in claim 1 and by an optical system having the features specified in claim 2.According to the invention, it has been recognized that an adaptation of an illumination pupil of the illumination optics of the optical system to an exit pupil of the imaging optics of the optical system provides the possibility of a further improvement of an imaging behavior of the optical system and thus of an improvement of its resolution capability.Accordingly, the possibility arises of imaging the object to be imaged in each case onto a substrate, in particular in the form of a wafer, with improved resolution by means of the projection exposure apparatus.It has been found in particular that the adaptation of the illumination pupil to an obscuration exit pupil region of the imaging optical unit is of particular use. The illumination light is provided by adapting the illumination pupil to the obscuration exit pupil region where it can be effectively used for high-resolution imaging.In this case, in particular, an obscuation illumination pupil region with a noncentre geometric center of gravity can also be provided.The illumination pupil can have at least one illumination pole. The illumination pupil can have at least two illumination poles. The illumination pupil can have exactly one, can have exactly two, can have exactly three, can have exactly four, can have exactly five, can have exactly six, can have exactly seven, can have exactly eight, can have exactly nine or can also have exactly ten illumination poles. A larger number of illumination poles within the illumination pupil is also possible.An illumination pole is a pupil region of the illumination pupil, which region is delimited in a writable manner by an envelope and illuminated with the illumination light. The illumination pole can be illuminated with the illumination light without gaps overall, or a distribution of locations of incidence of illumination channels can be present within the illumination pole, which are predefined via the illumination optics.When adapting to an obscuation exit pupil region with a noncentre geometric center of gravity according to claim 1, corresponding advantages are particularly important. The adaptation is effected via a corresponding specification of the illumination pupil taking into account in particular those illumination pupil regions which interact with the obscuration exit pupil region of the imaging optical unit. In this case, in particular, a diffraction of the illumination pupil at structures of the object to be imaged can be taken into account.An obscured illumination pupil region according to claim 2 allows additional degrees of freedom in matching the illumination pupil to an obscured exit pupil of the imaging optics.The exit pupil to be adapted can have an outer boundary and / or a boundary of the obscuration exit pupil region which has a circular shape in normalized and / or in absolute pupil coordinates or alternatively deviates from a circular shape and has, for example, an ellipsoidal shape.Accordingly, the illumination pupil adapted thereto can also have an outer boundary and / or a boundary of an obscuation illumination pupil region which has a circular shape in normalized and / or in absolute pupil coordinates or alternatively deviates from a circular shape and has, for example, an elliptical shape. In particular in the case of imaging optics embodied anamorphically, an obscuration exit pupil region of the imaging optics can have a circular shape, whereas an obscuration illumination pupil region has an envelope which deviates from a circular shape.An illumination pupil according to claim 3 takes into account the obscured exit pupil region such that zeroth order illumination light is not unnecessarily blocked at obscured imaging optics. A correspondingly increased light throughput results.An illumination pupil according to claim 4 takes into account that diffracted imaging light within the exit pupil is not undesirably diffracted into the obscuation exit pupil region. Depending on an orientation of object structures to be imaged, a corresponding diffraction direction can be taken into account. A plurality of diffraction directions can also be taken into account in the design of the illumination pupil adapted to the exit pupil.In an illumination pupil according to claim 5, the illumination pupil is in any case regionally illuminated adjacent to an illumination pupil region adapted to an obscuration exit pupil region. Illumination pupils with an integrally high light throughput can then be provided. Diffraction effects in at least one diffraction direction can also be taken into account when presetting such illumination pupils. The illumination pupil can be predefined, for example, such that diffracted illumination light is not undesirably blocked at the obscured exit pupil region.By means of an illumination pupil according to claim 6, it is possible in any case to provide a portion of a dark field illumination in which illumination light of zeroth order of diffraction does not reach the image field, but rather is blocked at an obscuration and / or at an outer edge of the exit pupil. In addition to such a dark field illumination component, the illumination pupil can also provide further illumination components in which even illumination light of zeroth order of diffraction reaches the image field.An illumination pupil according to claim 7 can be used to provide an over-irradiated illumination which, in addition to the dark-field illumination, also includes an illumination component in an illumination pupil region in which imaging light of zeroth order of diffraction reaches the image field.An illumination pupil with illumination pupil environment not exposed to illumination light according to claim 8 yields an illumination pupil which takes into account tolerances of a position of the obscuation exit pupil region, in particular drift tolerances or also field dependence tolerances. Slight pupil displacements do not lead to an illumination pupil region which, before the displacement, is within an obscuration exit pupil region, not emerging from this region in an undesirable manner and vice versa. Tolerances of the imaging optical unit, in particular tolerances in the obscured exit pupil region, and tolerances of the illumination optical unit, in particular tolerances in the obscured illumination pupil region, can be taken into account. Tolerances of the guidance of the illumination light, i.e. of an illumination light beam path, and tolerances of an imaging beam path can generally be taken into account.An extent of the illumination pupil environment along a coordinate perpendicular to a respective edge section of the edge of the obscuation exit pupil region, i.e. a distance between regions of the adapted illumination pupil exposed to the illumination light, can lie in the range between 0.1% and 5% of an overall pupil extent.With an illumination pupil according to claim 9, a dark field illumination can be provided overall, which offers particular resolution advantages for specific imaging tasks.By means of an adapted illumination pupil according to claim 10, diffraction effects and / or field dependence effects of the exit pupil can be taken into account in particular if the illumination pupil itself is not designed field-dependent.A field dependent illumination pupil according to claim 11 provides particular flexibility advantages. The field dependence of the illumination pupil can be used to ensure an adaptation of a correspondingly field-dependent exit pupil. Alternatively or additionally, the field dependence of the illumination pupil can also be used, however, for adaptation to a field-dependently varying diffraction behavior of structures of the object to be imaged.The illumination pupil according to claim 12 has corresponding advantages.Edge contour parameters according to claim 13 result in a particularly effective adaptation of the illumination pupil. The decentration of the edge contour of the obscuation exit pupil region can lie in the range between 0.004 and 0.02, in the range between 0.005 and 0.01 and, for example, in the range between 0.006 and 0.007. A mean deviation of the edge contour of the obscuation exit pupil region from a circular shape can lie in the range between 0.125 and 0.275, in particular in the range between 0.15 and 0.275.The illumination optics can be equipped with a field facet mirror and a pupil facet mirror according to claim 14, which has proven to be effective in practice. Alternatively, the illumination optics can have, for example, a field facet mirror and a further facet mirror which is arranged at a distance from a pupil plane of the illumination optics. Such a concept is known as a specular reflector in the prior art.The illumination optics according to claim 15 can be equipped with facet mirrors which provide a plurality of groups of transmission individual mirrors and / or groups of illumination individual mirrors for presetting the respective illumination channels. Such facet mirrors can be designed as MEMS mirrors.The light source of the optical system according to claim 16 can be an EUV light source or else a DUV light source. EUV illumination light can have a wavelength in the range between 5 nm and 30 nm, for example in the range of 13.5 nm. DUV illumination light can have a wavelength of 193 nm or else a longer wavelength.The advantages of a projection exposure apparatus according to claim 17 correspond to those already explained above with reference to the optical system according to the invention.Another object of the present invention is to provide an illumination pupil adjustment method that enables improvement of a resolving power of the optical system.This object is achieved according to the invention by a specification method with the method steps mentioned in claim 18.In the specification method, both an object diffraction behavior and a function of an obscuration exit pupil region are taken into account. A correspondingly optimized illumination is the result.The method according to claim 19 takes into account a field dependence of an exit pupil of the imaging optics and / or a field dependence of object diffraction, which may result in additional resolution advantages in illumination and / or illumination / imaging light throughput advantages within the optical system.The advantages of a production method according to claim 20 and of a microfabricated component according to claim 21 correspond to those already explained above with reference to the illumination optics. The component produced can be a semiconductor element, in particular a microchip, in particular a memory chip.Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. In these show: FIG. 1 shows a highly schematic meridional section of a projection exposure apparatus for EUV microlithography with a light source, an illumination optical unit and a projection optical unit, wherein a plan view of an object field of the projection exposure apparatus is illustrated in an insert; FIG. 2 shows schematically and likewise in meridional section a beam path of selected individual beams of illumination light within the illumination optics according to FIG. 1, starting from an intermediate focus up to a reticle or object arranged in the object plane of the projection optics in the region of the illumination or object field; FIG. 3 shows a plan view of a first facet mirror of the illumination optical unit, which is arranged in a field plane of the illumination optical unit and in an illumination far field of the light source and is also referred to as a field facet mirror, wherein an array arrangement of individual mirror units, which are each formed from a sub-array of individual mirrors of the first facet mirror, which sub-array is not visible in FIG. 1, is illustrated; FIG. 4 is an enlarged view, by way of example and more in detail, but still schematically, of one of the individual mirror units in comparison with FIG. 3 embodied as a sub-array of the individual mirrors; FIG. 5 shows a plan view of an illumination-specification facet mirror of the illumination optical unit, which is arranged at a distance from a pupil plane of the illumination optical unit and is also referred to as a second facet mirror; FIG. 6 again schematically shows an embodiment of the illumination optics of the projection exposure apparatus having two facet mirrors, embodied as a MEMS mirror having a multiplicity of individual mirrors, wherein the second facet mirror, which in turn serves as an illumination-specification facet mirror, is arranged at a distance from a pupil plane of the illumination optics, and wherein, by way of example, two illumination channels of the illumination optics for the superimposed illumination of the reticle with a defined illumination angle distribution are emphasized, and wherein additionally selected individual beams for object field illumination from three different directions (two pupil marginal beams and one main beam) are illustrated; FIG. 7 shows an illumination pupil region of an illumination pupil of the illumination optical unit, which region is adapted to an illumination exit pupil region of the projection optical unit of the projection exposure apparatus, wherein an illumination of the illumination pupil within the illumination pupil region with illumination light is illustrated via a plurality of the illumination channels indicated in FIG. 7 via corresponding illumination light intensity isolines; FIG. 8 shows, in a representation similar to FIG. 7, an embodiment of an adapted illumination pupil of the illumination optical unit having an inner illumination pupil region which is in turn adapted to an illumination exit pupil region of the projection optical unit, and an outer illumination pupil region surrounding this illumination pupil region, wherein illumination light is not applied between the illumination pupil region and the outer illumination pupil region, again illustrated by individual illumination channels, to an illumination pupil environment to which an associated region of the exit pupil of the projection optical unit adjacent to an edge of an illumination exit pupil region belongs; FIG. 9A / 9B schematically shows two variants of an adapted illumination pupil with dark field illumination, in which illumination light is therefore radiated onto the reticle from angles which do not lie within an exit pupil of the projection optical unit; FIGS. 10 to 12 show embodiments of an adapted illumination pupil in which an illumination pupil region corresponding to an illumination exit pupil region of the projection optical unit is not impinged upon by illumination light; FIG. 13 shows an illumination pupil in which an obscuration illumination pupil region, which is matched to the obscuration exit pupil region of the imaging optical unit, is completely illuminated, resulting in dark-field illumination in accordance with FIG. 9A ; FIG. 14 shows, in a representation similar to FIG. 13, an adapted illumination optical unit in which, in addition, the illumination pupil in an illumination pupil coordinate region of a cross-diffraction pupil coordinate perpendicular to a diffraction pupil coordinate is not acted upon by illumination light which corresponds to the extent of the obscuration exit pupil region along this cross-diffraction pupil coordinate, but beyond this illumination pupil coordinate region the cross-diffraction pupil coordinate is already incident on four illumination pupil regions of the illumination pupil outside the obscuration illumination pupil region; FIG. 15 shows, in a representation similar to FIG. 13, an embodiment of the adapted illumination pupil with a fully irradiated obscured illumination pupil region; FIG. 16 is a view similar to FIG. 15 of an adjusted illumination pupil, the illumination pupil region of which is not exposed to illumination light in an illumination pupil environment corresponding to a region of the exit pupil adjacent to an edge of the obscured exit pupil region, similar to FIG. 8 ; FIG. 17 shows, in a representation similar to FIGS. 10 to 16, an embodiment of an illumination pupil region of an adapted illumination pupil, wherein the illumination light is applied to the illumination pupil region in such a way that, where a section of a diffraction pupil region outside the exit pupil arises in the exit pupil, no illumination takes place in the illumination pupil region of the obscuation; FIG. 18 shows, in a representation similar to FIG. 17, a variant of an illumination of the illumination pupil region of the object in such a way that no illumination takes place within the illumination pupil region of the object where an overlap with pupil regions of the diffraction results in the exit pupil; FIGS. 19 to 21 show an adapted dark field illumination pupil similar to that according to FIG. 13, but with outer envelopes of the obscuration illumination pupil region deviating from an ellipse, wherein the dark field illumination pupil is shown for three different field heights, namely at a smallest field height coordinate (FIG. 19 ), at a central field height coordinate (FIG. 20 ) and at a largest field height coordinate (FIG. 21 ), wherein an illumination field dependence of the dark field illumination pupil follows an exit pupil field dependence of an exit pupil; FIGS. 22 to 24 show, in a representation similar to FIGS. 19 to 21, an illumination pupil region lying within an obscurcation exit pupil region of a further embodiment of an illumination pupil region adapted to the obscurcation exit pupil region, wherein in this case an illumination angle distribution of the adapted illumination pupil is not field-dependent, but an exit pupil of the projection optical unit is already on the contrary; FIG. 25 shows, in a representation similar to FIG. 13, an embodiment of an adapted illumination pupil set as a distribution of illumination channels via an illumination optical unit, in which the first facet mirror is embodied as a field facet mirror and the second facet mirror is embodied as a pupil facet mirror, represented in normalized pupil coordinates, which represent a measure for a maximum illumination angle possible in each case within the pupil in the radial direction; FIG. 26 shows the illumination pupil according to FIG. 25, illustrated in absolute, nonnormalized pupil coordinates, which represent a measure of the actual illumination angle; FIG. 27 shows, in a representation similar to FIG. 25, an adjusted illumination pupil corresponding to the pupil region of FIG. 11 with centered obscuration illumination, again set via the illumination optics with the field facet mirror and the pupil facet mirror; FIG. 28 shows the illumination pupil according to FIG. 27 in an absolute pupil coordinate representation corresponding to FIG. 26 ; FIG. 29 shows, in a representation corresponding to FIG. 25, an embodiment of an adapted illumination pupil with an illumination pupil region adapted to the obscuration exit pupil region, which illumination pupil is illuminated only in a pupil region adjacent to the edge of the obscuration exit pupil region; FIG. 30 shows the illumination pupil according to FIG. 29 in an absolute pupil coordinate representation corresponding to FIG. 26 ; FIG. 31 shows, in a representation similar to FIG. 25, an adapted illumination pupil in the manner of that of FIG. 16, again set via the illumination optics with the field facet mirror and the pupil facet mirror; FIG. 32 shows the illumination pupil according to FIG. 31 in an absolute pupil coordinate representation corresponding to FIG. 26 ; FIG. 33 shows, in a representation similar to FIG. 25, an embodiment of an adapted illumination pupil which represents a superposition of the pupil according to FIG. 25 with an x-dipole illumination pupil with two pupil strips completely illuminated via the pupil along the cross-diffraction pupil coordinate; FIG. 34 shows the illumination pupil according to FIG. 33 in an absolute pupil coordinate representation corresponding to FIG. 26 ; FIG. 35 shows an embodiment of the illumination pupil according to FIG. 14, adjusted via the illumination optics with the field facet mirror and the pupil facet mirror; FIG. 36 shows the illumination pupil according to FIG. 35 in an absolute pupil coordinate representation corresponding to FIG. 26 ; FIG. 37 shows, in a representation similar to FIG. 35, an embodiment of an adapted illumination pupil, again with an illuminated obscuration illumination pupil region, corresponding to an obscuration exit pupil region, and with further illumination pupil regions in the form of four illumination poles, wherein the illumination pupil is not acted upon by illumination light in an illumination pupil coordinate region along the diffraction pupil coordinate, wherein this non-acted upon illumination pupil coordinate region corresponds to the extent of the obscuration exit pupil region along the diffraction pupil coordinate according to FIG. 14 ; FIG. 38 shows the illumination pupil according to FIG. 37 in an absolute pupil coordinate representation corresponding to FIG. 26 ; FIG. 39 shows, in a representation similar to FIGS. 33 to 38, a further embodiment of an adjusted illumination pupil, adjustable via the illumination optics with the field facet mirror and the pupil facet mirror, wherein this illumination pupil represents a superposition of an illuminated obscuration illumination pupil region, corresponding to an obscuration exit pupil region, with a quadrupole illumination pupil; FIG. 40 shows the illumination pupil according to FIG. 39 in an absolute pupil coordinate representation corresponding to FIG. 26 ; FIG. 41 shows, in a representation similar to FIG. 39, an adjusted illumination pupil again with an illuminated illumination pupil region, adjusted to an illumination exit pupil region of the projection optical unit, with a total of eight illuminated illumination pupil regions separated from one another in the form of illumination poles outside the illumination pupil region; FIG. 42 shows the illumination pupil according to FIG. 41 in an absolute pupil coordinate representation corresponding to FIG. 26 ; FIG. 43 shows an adjusted desired illumination pupil in the manner of FIG. 29 with a stadione-shaped obscuation illumination pupil region and homogeneous illumination between an inner and an outer boundary; FIG. 44 shows an actual illumination pupil corresponding to FIG. 43, adjusted via a specular reflector design of the illumination optical unit according to FIG. 6 ; FIG. 45 is a schematic plan view of an embodiment of a reticle to be illuminated with regions of fine reticle structures and regions of coarse reticle structures; FIG. 46 shows an embodiment of an adjusted illumination pupil corresponding to that according to FIG. 10 for the finer reticle structures of the reticle according to FIG. 45; FIG. 47 shows, in a representation similar to FIG. 46, an embodiment of the adapted illumination pupil for the coarser reticle structures according to FIG. 45 and for reticle structure transition regions between the finer and the coarser reticle structures; FIG. 48 shows a total of four variants of an edge contour of an adapted obscuration illumination pupil region adapted to a given shape of an obscuration exit pupil region of the projection optical unit; and FIG. 49 shows, in a representation similar to FIG. 48, again four variants of an edge contour of an adapted obscured illumination pupil region, adapted to a further variant of a shape of an obscured exit pupil region of the projection optical unit.A projection exposure apparatus 1 for microlithography, which is illustrated in a highly schematic manner in FIG. 1 and in a meridional section, has a light source 2 for illumination and imaging light 3. This can be an LPP (laser produced plasma) light source, a DPP (discharge produced plasma) light source or a synchrotron radiation-based light source, for example a free electron laser (FEL).A transmission optics 4 is used for guiding the illumination light 3, starting from the light source 2, and this optics have a collector 5, which is illustrated in FIG. 1 only with regard to its reflecting effect, and a transmission facet mirror 6, which is described in more detail below and is also referred to as a first facet mirror or as a field facet mirror. Between the collector 5 and the transmission facet mirror 6, an intermediate focus 5 aof the illumination light 3 is arranged. A numerical aperture of the illumination light 3 in the region of the intermediate focus 5 ais, for example, NA=0.182. Arranged downstream of the transfer facet mirror 6 and thus of the transfer optics 4 is an illumination-specification facet mirror 7, which is also referred to as a second or further facet mirror and is likewise explained in more detail below. The optical components 5 to 7 are components of an illumination optical unit 11 of the projection exposure apparatus 1.In one embodiment of the illumination optics 11, the transfer facet mirror 6 is arranged in a field plane of the illumination optics 11. The first facet mirror 6 is designed for arrangement in a useful region of a far field of the light source 2.In one embodiment of the illumination optical unit 11, the illumination-specification facet mirror 7 of the illumination optical unit 11 is arranged at a distance from pupil planes of the illumination optical unit 11. Such an arrangement is also referred to as a specular reflector. Alternatively, the illumination specification facet mirror 7 can also be arranged in the region of a pupil plane of the illumination optical unit 11 and is then referred to as a pupil facet mirror.Arranged downstream of the illumination specification facet mirror 7 in the beam path of the illumination light 3 is a reticle 12 which is arranged in an object plane 9 of a downstream projection optical unit 10 of the projection exposure apparatus 1. The projection optical unit 10 is a projection objective. The projection optical unit 10 is also referred to below as imaging optical unit.With the illumination optics 11, an object field 8 on the reticle 12 is illuminated in a defined manner in the object plane 9. The object field 8 simultaneously represents an illumination field of the illumination optical unit 11. In general, the illumination field is designed such that the object field 8 can be arranged in the illumination field.The illumination-specification facet mirror 7 is, like the transmission facet mirror 6, part of a pupil illumination unit of the illumination optical unit and serves for illuminating an entry pupil 12 ain a pupil plane 12 bof the projection optical unit 10 with the illumination light 3 having a predefined pupil intensity distribution. The entrance coil 12 acontinues an illumination pupil of the illumination optical unit 11 at the same time. The entrance pupil 12 aof the projection optical unit 10 can be arranged in the illumination beam path upstream of the object field 8 or else downstream of the object field 8.In the embodiment according to FIG. 1, the illumination optical unit 11 has exactly two mirrors guiding the illumination light 3, namely the two facet mirrors 6 and 7, downstream of the collector 5, Depending on the embodiment of the illumination optical unit 11, further mirrors for guiding the illumination light 3 between the collector 5 and the object field 8 can be provided in addition to these two mirrors 6, 7, e.g. at least one deflection mirror between the collector 5 and the first facet mirror 6 and / or at least one deflection mirror between the two facet mirrors 6 and 7 and / or at least one deflection mirror between the second facet mirror 7 and the object field 8.FIG. 1 shows the case in which the entry pupil 12 ais arranged in the illumination beam path downstream of the object field 8. A pupil distance PA of the second facet mirror 7 from the pupil plane 12 bis obtained in this case as the sum of a z-distance PA 1 of the second facet mirror 7 from the object plane 9 and the z-distance PA 2 of the object plane 9 from the pupil plane 12 b. Thus, PA=PA1+PA2 applies. The pupil distance PA can alternatively also be measured in the beam direction.An illumination pupil region of the illumination pupil 12 athat is impinged upon by the illumination light 3 is adapted to an exit pupil of the projection optical unit 10, as will be explained in greater detail below.To facilitate the representation of positional relationships, a Cartesian xyz-coordinate system is used below. The x-direction extends in FIG. 1 perpendicularly to the plane of the drawing into the latter. The y-direction extends to the right in FIG. 1. The z-direction runs downward in FIG. 1. Coordinate systems used in the drawing each have x-axes running parallel to one another. The course of a z-axis of these coordinate systems follows a respective main direction of the illumination light 3 within the respectively observed figure.The object field 8 has an arcuate or partially circular shape and is bounded by two circular arcs parallel to one another and two straight side edges which run 0 in the y direction with a length y and are at a distance x 0 to one another in the x direction. The aspect ratio x 0 / y 0 is 13 to 1. an insert of FIG. 1 shows a top view, not to scale, of the object field 8. In an alternative and likewise possible object field 8, its boundary shape is rectangular, likewise with aspect ratio x 0 / y 0.During a projection exposure, the reticle 12 is displaced along an object displacement direction y through the object field 8.The projection optical unit 10 is indicated only partially and strongly schematically in FIG. 1. An object field-side numerical aperture 13 and an image field-side numerical aperture 14 of the projection optical unit 10 are illustrated. The image field-side numerical aperture 14 can lie in the range between 0.2 and 0.7 and can be, for example, 0.3, 0.33, 0.4, 0.45, 0.5, 0.55 or else 0.6. Between indicated optical components 15, 16 of the projection optical unit 10, which can be designed, for example, as mirrors reflecting for the EUV illumination light 3, there are further optical components of the projection optical unit 10, not shown in FIG. 1, for guiding the illumination light 3 between these optical components 15, 16. The projection optical unit 10 has a last mirror in the beam path of the illumination and imaging light 3 with a passage opening for the illumination and imaging light 3. An exit pupil of the projection optical unit 10 correspondingly has an obscuation exit pupil region. An edge contour of the obscuration exit pupil region of the projection optical unit 10 can be predefined for the illumination and imaging light 3 via an obscuration aperture in the beam path of the projection optical unit 10.The projection optical unit 10 images the object field 8 into an image field 17 in an image plane 18 on a wafer 19 which, like the reticle 12, is carried by a holder, not shown in detail. Both the reticle holder and the wafer holder can be displaced both in the x direction and in the y direction by means of corresponding displacement drives. A structural space requirement of the wafer holder is illustrated in FIG. 1 at 20 as a rectangular box. The installation space requirement 20 is cuboidal with an extent in the x-, y- and z-directions which is dependent on the components to be accommodated therein. The installation space requirement 20 extends, for example, from the center of the image field 17, in the x-direction and in the y-direction by 1 m. The installation space requirement 20 extends, for example, from the image plane 18 in the z-direction too by 1 m. The illumination light 3 must be guided in the illumination optical unit 11 and the projection optical unit 10 in such a way that it is guided past the installation space requirement 20, respectively.The transfer facet mirror 6 has a plurality of transfer facets 21, also referred to as first facets. The transfer facet mirror 6 can be embodied as a MEMS mirror. The transmission facets 21 each have a plurality of individual mirrors ES switchable by at least two tilting positions (cf. also FIGS. 4 and 6 ) which are designed as micromirrors. The individual mirrors ES can be designed as tiltable micromirrors driven about two mutually perpendicular axes of rotation.Of the transfer facets 21, a line with a total of nine transfer facets 21 is schematically shown in the yz section according to FIG. 2, which are indexed from left to right by 21 1 to 21 9 in FIG. 2. In fact, the transfer facet mirror 6 has a substantially larger plurality of the transfer facets 21. The single mirrors ES of the transfer facet mirror 6 are grouped into a plurality of the transfer facets 21. These transfer facets 21 are also referred to as single mirror groups, virtual field facets and virtual facet groups, respectively. A single mirror group is a group of the single mirrors ES of the first facet mirror 6, which is imaged into the object field 8 by the same second facet 25.Each of the transmission facets 21 guides a portion of the illumination light 3, which is also referred to as illumination light sub-bundle, via an illumination channel for partial or complete illumination of the object field 8. In principle, each of the illumination specification facets 25 can in turn be constructed from a plurality of individual mirrors. The illumination specification facets 25 are also referred to below as second facets. If the second facet mirror 7 is arranged in the region of a pupil plane of the illumination optical unit 11, the illumination specification facets 25 are also referred to as pupil facets.For further details of possible embodiments of the transfer facet mirror 6 and of the projection optical unit 10, reference is made to WO 2010 / 099 807 A.At least some of the illumination specification facets 25 illuminate only a sub-region or sub-field of the object field 8. These sub-fields are shaped very individually and also depend on the desired illumination direction distribution (pupil shape) in the object field 8, i.e. the illumination setting. The illumination specification facets 25 are therefore illuminated by virtual field facets of very different shapes, the shape of which corresponds precisely to the shape of the respective sub-field to be illuminated. Each illumination specification facet 25 also contributes to different regions of the pupil depending on the location in the object field 8.The illumination specification facet mirror 7 can be designed as a MEMS mirror in particular when each of the illumination specification facets 25 is constructed from a plurality of individual mirrors ES (cf. FIG. 6 ). The illumination specification facets 25 are micromirrors switchable between at least two tilt positions. The illumination specification facets 25 are designed as micromirrors which can be tilted continuously and independently driven about two mutually perpendicular tilting axes, that is to say can be set into a multiplicity of different tilting positions.An example of a predefined assignment of individual transfer facets 21 to the illumination specification facets 25 is illustrated in FIG. 2. The illumination specification facets 25 assigned to the transmission facets 21 1 to 21 9 in each case are indexed in accordance with this assignment. The illumination specification facets 25 are illuminated from left to right on the basis of this assignment in the order 25 6, 258, 253, 254, 251, 257, 255, 252 and 25 9.Indices 6, 8 and 3 of facets 21, 25 include three illumination channels VI, VIII and III, which illuminate three object field points OF 1, OF 2, OF 3, which are numbered from left to right in FIG. 2, from a first illumination direction. The indices 4, 1 and 7 of the facets 21, 25 belong to three further illumination channels IV, I, VII, which illuminate the three object field points OF 1 to OF 3 from a second illumination direction. The indices 5, 2 and 9 of the facets 21, 25 belong to three further illumination channels V, II, IX, which illuminate the three object field points OF 1 to OF 3 from a third illumination direction. Corresponding illumination light sub-beams 3 1 to 3 9 are assigned to the illumination channels I to IX.The illumination directions,the illumination channels VI, VIII, III,the illumination channels IV, I, VII andthe illumination channels V, II, IXThe respective components are assigned to them, are identical. The assignment of the transmission facets 21 to the illumination specification facets 25 is therefore such that telecentric illumination of the object field 8 results in the illumination example illustrated in the figure.The illumination of the object field 8 via the transmission facet mirror 6 and the illumination-specification facet mirror 7 can take place in the manner of a specular reflector. The principle of the specular reflector is known from US 2006 / 0132747 A1.FIG. 3 shows a plan view of the first facet mirror 6, which has a regular array arrangement of individual mirror units 26 which are bounded squarely in FIG. 3. Each of the individual mirror units 26 is designed as a sub-array of N x M of the individual mirrors ES (cf. FIG. 4 ). This sub-array has a plurality of array lines extending along a line direction corresponding to a bisector of the xy-coordinate system. Some of the mutually adjacent array lines are offset with respect to one another by a part of an extent of one of the individual mirror units 26, in particular by half of this extent of the respective individual mirror unit 26 along the array line. Depending on the embodiment of the facet mirror 6, such an offset can be completely omitted, resulting in an array arrangement composed completely of rows and columns. Alternatively, all array lines may be offset from each other. Different amounts of offset between different, adjacent array parts are also possible depending on the design of the facet mirror 6 and depending on the requirements placed on positioning the individual mirror units 26.Figure 4 shows one of the single mirror units 26 still schematically, but more in detail. The illustration shows a subdivision of the single mirror unit 26 into the sub-array of, in this case, 6 x 6 of the single mirrors ES. Each of the individual mirror units 26 thus has 36 the individual mirrors ES in the embodiment shown. In the example according to FIG. 4, N=6 and M=6. N and M can be the same, can be different and can each lie in the range between 2 and 64, for example at 4, 8, 16, 32 or 64. Values other than powers of two are also possible for N and M, for example 25 or 50.In the embodiment shown in FIG. 3, the first facet mirror 6 has an arrangement of the individual mirror units 26 within a circular envelope. Alternatively, the first facet mirror 6 can also have the individual mirror units 26 within an elliptical, rectangular or else polygonally bordered envelope.In each case one of the individual mirror units 26 can contain a plurality of complete or partial individual mirror groups which guide the illumination light 3 to different second facets 25 and are imaged in the object field 8 in a manner overlapping one another. The single mirror groups may extend over a plurality of the single mirror units 26.FIG. 5 again shows the second facet mirror 7 in a plan view.The second facets 25 of the second facet mirror 7 are embodied in a circular-edged manner and are present in the form of a hexagonally densest packing. Alternatively to circularly bordered second facets 25, rectangular or polygonal, in particular hexagonal, bordered second facets 25 can also be present. The second facets 25 can in turn be embodied as individual mirror units in the manner of the individual mirror units of the first facet mirror 6 and in this case be divided into a plurality of individual mirrors in the manner of the individual mirrors ES. In principle, a structure of the second facet mirror 7, as far as the subdivision into individual mirrors and individual mirror units is concerned, can correspond to the structure of the first facet mirror 6.In the embodiment according to FIG. 5, each of the second facets 25 can also be embodied as a monolithic facet.The second facets 25 are arranged in the case of the second facet mirror 7 within an elliptically bordered envelope. Alternatively, other envelope shapes are also possible here, for example a circular envelope, a rectangular envelope and also a polygonally bordered envelope.FIG. 6 again schematically shows an embodiment of the illumination optical unit 11, in which the first facet mirror 6 is arranged in the region of a field plane of the illumination optical unit 11 and the second facet mirror 7 is arranged at a distance from a pupil plane of the illumination optical unit 11, in particular at a distance from the pupil plane 12 b(cf. also FIG. 1 ).The two facet mirrors 6 and 7 are designed as MEMS mirrors and have a multiplicity of the individual mirrors ES.FIG. 6 shows a beam path of selected individual beams between the intermediate focus 5 aand the entry pupil 12 a. In particular, FIG. 6 illustrates, by way of example, a profile of two illumination channels 27 1, 272, which are each guided via a transmission facet 21 1, 212 of the first facet mirror 6 and an illumination specification facet 25 1, 252 of the second facet mirror 7. Each of the transmission facets 21 i is constructed as a 7x14 array of the individual mirrors ES, wherein a longer extension of this array, adapted to the aspect ratio of the object field 8, runs along the x direction and a shorter extension of the array runs along the y direction.For the purpose of illustration, in the illustration according to FIG. 6, the two facet mirrors 6, 7 are illustrated rotated through 90° about the x-axis, such that they can be seen in an xy-plan view, whereas further components, for example the reticle 12 and the entry pupil 12 a, are shown in an xz meridional section.The illumination specification facet 25 i of the respective illumination channel 27 i is designed as a 2x2 array of the individual mirrors ES of the illumination specification facet mirror 7.In addition to the course of the two illumination channels 27 i between the intermediate focus 5 aand the entrance pupil 12 a, FIG. 6 also illustrates the course of selected individual beams which are assigned to different illumination angles. Main beams 28 are shown, each of which runs through a center of the entry pupil 12 aand boundary edge or coma beams 29 and 30 bounding the entry pupil 12 ain the direction of the x-coordinate on the one hand and on the other hand.The illumination channel 27 1 is bounded on the one hand by one of the main beams 28 and on the other hand by one of the edge beams 30, thus covers a part of an entire entrance pupil 12 ailluminated via the illumination pupil 11 in the setting assignment shown.The illumination channel 27 2 is on the one hand bounded in turn by one of the main beams 28 and on the other hand bounded by one of the marginal beams 29, thus covering a supplementary illumination angle range within the entry pupil 12 a.Both illumination channels 27 1, 272 illuminate the entire object field 8.Alternatively, i illumination channels 27 are also possible, in which not the entire object field 8, but only a sub-field is illuminated, and / or in which not only a part of the entry pupil 12 ais illuminated, but rather the entire entry pupil 12 a.FIG. 7 illustrates an illumination pupil region 31 in the interior of an embodiment of the illumination pupil 12 a, which is not illustrated in the edge region in FIG. 7. An envelope 32 of the obscured illumination pupil region 31 is adapted, as regards its edge contour, to an edge contour of the embodiment of the projection optical unit 10 corresponding to the obscured exit pupil region. The envelope 32 specifies a core section of the illumination pupil 12 a, in which locations of incidence 33 i of the illumination channels 27 iof the channel-by-channel mixed illumination, which are predefined by the facet mirrors 6, 7 of the illumination optical unit 11, are situated. These locations of incidence 33 i are also referred to as spots. The incidence locations 33 i have an illumination light intensity distribution, which is illustrated in FIG. 7 by isolines. The illumination intensity becomes higher inward within the locations of incidence 33 i wherein a maximum of the illumination intensity is not in the center of the respective location of incidence 33 i but rather regularly decentrated. The locations of incidence 33 i are generally elliptical in shape or else circular in shape. Another, more irregular shape is also possible. Outside the locations of incidence 33 i the illumination light 3 is not, or not appreciably, incident on the obscuation illumination pupil region 31 even within the envelope 32. The distribution of regions of the respective illumination pupil 12 athat are exposed to the illumination light 3 is also referred to as illumination setting.Tilt angles of the individual mirrors ES of the first facets 21 i, which belong to the illumination channels 27 i and the locations of incidence 33 i are set for presetting the illumination pupil 12 awith the obscured illumination pupil region 31 according to FIG. 7 in such a way that the locations of incidence 33 i are distributed as uniformly as possible within the envelopes 32 and fill the entire obscured illumination pupil region 31.The envelope 32 has, in turn, an elliptical shape in absolute pupil coordinates ρ x, ρ y, which represent a measure for a respective absolute illumination angle, i.e. deviates from a circular shape. The envelope 32 can also deviate from the circular shape in another way.FIG. 8 illustrates a further embodiment of an illumination pupil 12 a, in which incidence locations 33 are arranged in a distributed manner in i within an outer envelope 34 of an outer illumination pupil region 35 of the illumination pupil 12 a. The outer envelope 34 is circular in the absolute pupil coordinates ρ x, ρ y, which represent a measure of the illumination angle on associated object field points of the object field 8. The outer illumination pupil region 35 lies between the envelope 32 of the obscuation pupil region 31 on the one hand and the outer envelope 34 on the other hand.The envelope 32 of the illumination pupil region 31 lies within the circular outer envelope 34, which is adapted to the illumination exit pupil region of the projection optical unit 10 as in the case of the illumination pupil 12 ain accordance with FIG. 7. The locations of incidence 33 i of the illumination channels 27 i are arranged distributed within the outer envelope 34 such that all locations of incidence 33 i have a minimum distance Δ from the envelope 32 of the illumination pupil region 31 for observation. This minimum distance Δ can be in the range from 0.1% to 5% of a typical diameter of the obscuation pupil region 31 in relative pupil coordinates σ x, σ y normalized to the respective maximum illumination angle.As a result, both the inner illumination pupil region 31 and the outer illumination pupil region 35 are not exposed to the illumination light 3 in an illumination pupil environment around the envelope 32, that is to say in an illumination pupil environment which corresponds to a region of the exit pupil of the projection optical unit 10 adjacent to an edge of the illumination exit pupil region.Between the outer envelope 34 and an outer edge of the entire illumination pupil 12 a, which is not illustrated in FIG. 8, the illumination pupil 12 ais not acted upon by the illumination light 3. In an alternative illumination pupil 12 aaccording to FIG. 8, the outer envelope 34 and the outer edge of the entire illumination pupil 12 acoincide.With reference to FIGS. 9A and 9B, different variants of a dark field illumination are explained below, which can be set by means of the illumination optics 11 by corresponding selection of the illumination channels 27 in i via corresponding tilts of the individual mirrors ES of the facet mirrors 6 and 7.FIG. 9A shows a pupil of the projection exposure apparatus 1, which can be understood on the one hand as the illumination pupil 12 aand on the other hand as an exit pupil 36 of the projection optical unit 10. This pupil 12 a, 36 has an outer pupil boundary 37 which specifies a numerical aperture of the corresponding optical unit 11, 10 of the projection exposure apparatus 1. In the case of the illumination pupil 12 aof the illumination optical unit 11, the outer pupil edge 37 specifies an illumination angle for the object field 8 that is possible at most in the direction of a respective pupil radius. In the case of the exit pupil 36 of the projection optical unit 10, the outer pupil edge 37 specifies the image field-side numerical aperture. This outer pupil edge 37 is regularly predefined by an aperture diaphragm of the projection exposure apparatus 1. The outer pupil edge 37 is circular in the pupil 12 a, 36 according to FIG. 9A, but can also be bounded in another shape, for example elliptical or else in another manner deviating from the circular shape.The exit pupil 36 also has an obscuration exit pupil region 38; the latter is regularly predefined by an obscuration aperture of the projection exposure apparatus 1, with the result that, in particular, a passage opening in the last mirror of the projection optical unit 10 is not acted upon in a defined manner by the illumination and imaging light 3. The obscuation exit pupil region 38 is elliptically bounded. This boundary corresponds in its arrangement and shape to the envelope 32 of the illumination pupil region 31 according to FIGS. 7 and 8.FIG. 9A illustrates an illumination light incidence location 33 z in the center of the illumination pupil 12 a, which is represented in normalized pupil coordinates σ x, σ y. This central point of incidence 33 z is at the same time situated in the center of the obscuration exit pupil region 38.The illumination of the object field 8 and of the structured reticle 12 with the illumination channel 27 z from the direction of the point of incidence 33 z of the illumination pupil 12a generates diffraction orders B+ and B- in the exit pupil 36, B passes both the obscuration aperture and the aperture aperture of the projection optical unit 10 and reaches the image field 17 for imaging the respective structure of the reticle 12 on the wafer 19.The structures on the reticle 12 lead to a diffraction of the imaging light 3 downstream of the reticle 12 along the pupil coordinate σ x, which is also referred to below as the diffraction pupil coordinate of the exit pupil 36. A diffraction path d, i.e. a distance between the diffraction orders B+ and B- on the one hand to the point of incidence 33 z of the zeroth diffraction order, runs along this diffraction pupil coordinate σ x.FIG. 9B illustrates another variant of dark field illumination. In this case, an incidence location 33 0 of a zeroth order of diffraction of the imaging light 3 on structures of the reticle 12 lies outside the outer pupil edge 37 of the exit pupil 36, i.e. is blocked by the aperture stop of the projection optical unit 10. Along the diffraction pupil coordinate σ x, spaced apart from one another by the diffraction path d in each case, diffraction orders B 1 and B 2 of the imaging light 3 diffracted at the structures of the reticle 12 are produced within the outer pupil edge 37 of the exit pupil 36, which diffraction orders can then reach the image field 17 for imaging the corresponding structure of the reticle 12 on the wafer 19. The exit pupil 36 according to FIG. 9B can be a non-obscured exit pupil or else an obscured exit pupil, which is not illustrated in detail in FIG. 9B.Corresponding dark field illuminations, as described above in connection with FIGS. 9A and 9B, can in principle be combined with the illumination setting variants explained here overall by corresponding setting of the individual mirrors ES of the facet mirrors 6 and 7 of the illumination optical unit 11. In the case of dark-field illumination according to FIG. 9B, 0 individual mirrors ES on the illumination-specification facet mirror 7, which belong to illumination angles outside an outer pupil edge 37 of the exit pupil 36, are used for specifying the location of incidence 33.FIG. 10 shows a further embodiment of applying the illumination light 3 to an adapted illumination pupil 12 a, components and functions which have already been explained above with reference to FIGS. 1 to 9 and in particular with reference to FIGS. 7 to 9 are denoted by the same reference numerals and will not be discussed in detail again.The illumination pupil 12 ain accordance with FIG. 10 is not acted upon by the illumination light 3 within the envelope 32 of the illumination pupil region 31. Illumination pupil 12 aaccording to FIG. 10 is therefore not exposed to illumination light 3 in the illumination pupil regions which correspond to the obscuration exit pupil region (cf. 38 in FIG. 9A ) of projection optical unit 10. The envelope 32 is elliptical in the illustration according to FIG. 10 and centered with respect to the outer pupil edge 37 of the illumination pupil 12 a.The illumination pupil 12 aaccording to FIG. 10 is exposed to the illumination light 3 in four strip-shaped pupil regions I 1, I 2, I 3 and I 4 which are each located in one of the four quadrants Q 1, Q 2, Q 3 and Q 4 of the illumination pupil 12 a. In principle, the illumination pupil 12 aaccording to FIG. 10 therefore represents a quadrupole illumination setting with four illumination poles I i to I 4. The illumination pupil 12 aaccording to FIG. 10 is not impinged on by the illumination light 3 in an illumination pupil coordinate range Δσ y of a cross-diffraction pupil coordinate σ y perpendicular to the diffraction pupil coordinate σ x. This illumination pupil coordinate range Δσ y corresponds to an extension of the obscuation aperture range 38 along this cross-diffraction pupil coordinate σ y, as illustrated in FIG. 10. In this illumination pupil coordinate range Δσ y an illumination strip formed by the illumination poles I 2, I 3 on the one hand and I 1, I 4 on the other hand is each interrupted.This arrangement of the illumination poles I 1 to I 4 of the illumination setting 12 aaccording to FIG. 10 ensures that diffraction orders which are diffracted along the diffraction pupil coordinate σ x in the exit pupil 36 do not enter the obscuation aperture region 38 and then undesirably do not contribute to the imaging of corresponding structures of the reticle 12 at a superposition.Within the illumination poles I 1 to I 4 there can again be a distribution of incidence locations 33 i of illumination channels 27 i as already explained above together with FIGS. 7 and 8.With reference to FIG. 11, a further embodiment of the illumination pupil 12 a, which is adapted to the associated exit pupil of the projection optical unit 10, is explained below. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 10 and in particular with reference to FIGS. 7 to 10 are given the same reference numerals and will not be discussed in detail again.In the illumination setting 12 aaccording to FIG. 11, an obscuration illumination pupil region 31 is present, the position and boundary of which within the illumination pupil 12 ais adapted to an associated obscuration exit pupil region 38. The envelope 32 of the obscuration illumination pupil region 31 corresponds in its shape to the shape of the envelope of the obscuration exit pupil region 38. The envelope 32 deviates from a circular shape.The obscuration illumination pupil region 31 and the associated obscuration exit pupil region 38 have a noncentre geometric center of gravity SP. This center of gravity SP is spaced apart, i.e. decentrated, from a center of the entry pupil 12 aand of the exit pupil 36, respectively, by a distance Δz. Δz may be in the range between 0.5% and 45% of a typical diameter of the entrance pupil 12 a. In FIG. 11, this decentration Δz is exaggerated.The illumination light 3 is applied to the entrance pupil 12 ain accordance with FIG. 11 exclusively between the envelope 32 of the obscured illumination pupil region 31 and the outer pupil edge 37. In this impingement region between the envelope 32 and the outer pupil edge 37, impingement locations 33 i of the illumination channels 27 i can again be uniformly distributed and arranged in a sealed manner.In the case of the illumination setting 12 aaccording to FIG. 11, pupil illumination takes place directly adjacent to the envelope 32. Alternatively, a distance Δ can again be present between the envelope 32 and such points of incidence 33 i, as already explained above in connection with FIG. 8.With reference to FIG. 12, a further embodiment of the illumination pupil 12 a, which is adapted to the associated exit pupil of the projection optical unit 10, is explained below. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 11 and in particular with reference to FIGS. 7 to 11 are given the same reference numerals and will not be discussed in detail again.In the case of the illumination pupil 12 aaccording to FIG. 12, the envelope 32 of the illumination pupil region 31 adapted to the obscuration exit pupil region 38 is in turn completely omitted. Illumination takes place outside these envelopes 32 in a central illumination pole I which has an approximately biconvex lens shape. The illumination pole I may have a boundary shape referred to as "leaf-shape" (leaf shape). The illumination pole I of the illumination pupil 12 aaccording to FIG. 12 is extended such that the illumination pupil 12 ais illuminated on both sides of the envelope 32 along the cross-diffraction pupil coordinate σ y.In addition to the illumination pole I, the position of which in the illumination pupil 12 acorresponds to the position of a zeroth order of diffraction of the imaging light 3 in the exit pupil 36, the orders of diffraction B+, B- within the exit pupil 36 are also illustrated in FIG. 12. A boundary of the illumination pole I is such that the diffraction orders B+, B- are still completely within the outer pupil boundary 37. A "lens curvature" of the edge contour of the illumination pole I corresponds to a curvature of the outer pupil edge 37.With reference to FIG. 13, a further embodiment of the illumination pupil 12 a, which is adapted to the associated exit pupil of the projection optical unit 10, is explained below. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 12 and in particular with reference to FIGS. 7 to 12 are given the same reference numerals and will not be discussed in detail again.The entrance pupil 12 aaccording to FIG. 13 is a variant of dark field illumination. Illumination of the entrance pupil 12 aaccording to FIG. 13 takes place exclusively within the envelope 32, that is to say in the illumination pupil region 31 which is in turn adapted to the illumination exit pupils 38 of the projection optical unit 10. The envelope 32 is elliptical in the normalized pupil coordinates σ x, σ y with a longer half axis of this ellipse running along the σ x- coordinate. Between the envelope 32 and the outer pupil boundary 37, the entrance pupil 12 ais not impinged on by the illumination light 3.With reference to FIG. 14, a further embodiment of the illumination pupil 12 a, which is adapted to the associated exit pupil of the projection optical unit 10, is explained below. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 13 and in particular with reference to FIGS. 7 to 13 are given the same reference numerals and will not be discussed in detail again.The illumination pupil 12 aaccording to FIG. 14 can be understood as the superposition of the illumination pupils 12 aaccording to FIGS. 10 and 13. Therefore, on the one hand, the illumination pupil region 31 is illuminated and, on the other hand, the four illumination poles I 1, I 2, I 3 and I 4. are illuminated.With reference to FIG. 15, a further embodiment of the illumination pupil 12 a, which is adapted to the associated exit pupil of the projection optical unit 10, is explained below. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 14 and in particular with reference to FIGS. 7 to 14 are given the same reference numerals and will not be discussed in detail again.The illumination pupil 12 aaccording to FIG. 15 corresponds in principle to that according to FIG. 8, wherein uniform illumination of the entry pupil 12 awith the illumination light 3 takes place within the outer envelope 34. Insofar as this uniform illumination within the outer envelope 34 takes place by means of distributed locations of incidence 33 i of illumination channels 27 i in accordance with what was explained above in connection with FIGS. 7 and 8, in an alternative variant of the entrance pupil 12 a, locations of incidence 33 i can also lie on the envelope 32 of the illumination pupil region 31 for the observation.With reference to FIG. 16, a further embodiment of the illumination pupil 12 a, which is adapted to the associated exit pupil of the projection optical unit 10, is explained below. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 15 and in particular with reference to FIGS. 7 to 15 are given the same reference numerals and will not be discussed in detail again.The entrance pupil 12 aaccording to FIG. 16 is a variant of the entrance pupil 12 aaccording to FIG. 15, wherein, within the illumination of the outer envelope 34 with the illumination light 3, care is taken at the entrance pupil 12 aaccording to FIG. 16 to not impinge the illumination light 3 on the entrance pupil 12 ain the vicinity of the envelope 32, in particular at a distance Δ from the latter. Between illumination light 3 within the envelope 32 on the one hand and illumination light 3 outside the envelope 32 on the other hand, there is therefore a distance of at least 2 Δ in the entry pupil 12 a. In this respect, the entrance pupil 12a according to FIG. 16 corresponds to that according to FIG. 8.With reference to FIG. 17, a further embodiment of the illumination pupil 12 a, which is adapted to the associated exit pupil of the projection optical unit 10, is explained below. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 16 and in particular with reference to FIGS. 7 to 16 are given the same reference numerals and will not be discussed in detail again.The illumination setting 12 aaccording to FIG. 17 represents a variant of dark-field illumination. Not the entire obscured illumination pupil region 31 within the envelope 32 is illuminated, but a partial region 39 around a central point of incidence 33 z. A σ x- extension of the partial region 39 around the central point of incidence 33 z, i.e. around the center of the obscured illumination pupil region 31, is smaller than the σ x- extension of the entire obscured illumination pupil region 31, so that, in FIG. 17, free regions 40, 41 not exposed to the illumination light 3 remain on the right and left of the partial region 39 within the obscured illumination pupil region 31.Also shown in FIG. 17, comparable to the representation according to FIGS. 9A and 12, is a diffraction order B- in the exit pupil 36, diffracted at corresponding structures of the reticle 12. This illuminated partial region 39 simultaneously represents a zeroth order of diffraction within the exit pupil 36.The edge contour of the subregion 39 is adapted to the diffraction path d such that the diffracted subregion 39 lies completely within the outer pupil edge 37 of the exit pupil 36 in the diffraction order B-. A projection 42 of the order of diffraction B- beyond the outer pupil edge 37 corresponds in terms of shape and size to the right-hand free region 41 within the envelope 32 in FIG. 17.With reference to FIG. 18, a further embodiment of the illumination pupil 12 a, which is adapted to the associated exit pupil 36 of the projection optical unit 10, is explained below. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 17 and in particular with reference to FIGS. 7 to 17 are given the same reference numerals and will not be discussed in detail again.FIG. 18 also illustrates a variant of an illumination pupil 12 awith which dark-field illumination can take place.Again, not the entire illumination pupil region is illuminated, but only a partial region 39, so that free regions 40, 41 on the right and left are not impinged on by illumination light 3 by partial regions 39 within the envelope 32 of the illumination pupil region 31. These free regions 40, 41 correspond in terms of shape and size to overlap regions of the obscuration illumination pupil region 31 with the two diffraction orders B-, B+ of the exit pupil 36, in turn diffracted at structures of the reticle 12, this time with a diffraction path or diffraction distance d along the diffraction pupil coordinate σ x-, which is smaller than the diffraction distance d of the embodiment according to FIG. 17 in relation to the diameter of the exit pupil 36. Due to the smaller relative diffraction distance d, the diffraction orders B- and B+ in the free regions 40, 41 overlap with the obscuration illumination pupil region 31, which corresponds in position and shape to the zeroth diffraction order within the exit pupil 36.In the following, a further embodiment of an illumination pupil 12a, which in this case is dependent on the location on the object field 8, and which is adapted to an exit pupil 36 dependent on the object field in the same way, is described with reference to FIGS. 19 to 21. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 18 and in particular with reference to FIGS. 7 to 18 are given the same reference numerals and will not be discussed in detail again.FIGS. 19 to 21 show the pupils 12 aand 36 corresponding to one another for three different x-positions of the object field 8, which are also referred to as field heights. FIG. 19 shows the entrance pupil 12 aand the exit pupil 36 corresponding thereto at a field height x=-13 mm, i.e. at a left x-field edge of the object field 8. FIG. 20 shows the illumination pupil 12 aand the exit pupil 36 corresponding thereto in an x-field center (x=0 mm) of the object field 8. FIG. 21 shows the entrance pupil 12 aand the exit pupil 36 corresponding thereto at a right x-field edge (x=+13 mm) of the object field 8.At the field height x=0 mm (FIG. 20 ), dark field illumination is present comparable to that according to FIG. 13, but with an irregular envelope 32 of the obscured illumination pupil region 31 in the manner of FIGS. 11 and 12. The obscuation illumination pupil region 31 of the illumination pupil 12a according to FIG. 20 is centered at the field height x=0 within the outer pupil edge 37.At the left object field edge (field height x=-13 mm, cf. FIG. 19 ), the illumination pupil 12 aappears, adapted to the exit pupil 36 at this field height x=-13 mm, on the one hand displaced in the direction of the negative cross-diffraction pupil coordinate σ x-, i.e. downwards in FIG. 19, and tilted slightly counter-clockwise by a σ z- coordinate.At the right object field edge (field height x=+13 mm, cf. FIG. 21 ), there is a corresponding -σ y- displacement of the obscuration illumination pupil region 31, adapted to the exit pupil 36, at this field height x=13 mm, but in this case slightly tilted counter to one another in the positive clockwise direction about the pupil coordinate σ z.Alternative field-dependent illumination pupils 12 a, which are in particular adapted to corresponding field dependencies of the exit pupil 36, can also be present in the case of the other illumination settings described here, in particular in the case of the illumination settings having an obscuation illumination pupil region 31 deviating from the circular shape, e.g. in the case of the illumination pupils 12 awith elliptical envelopes 32 or else in the case of the illumination pupils 12 awith irregular envelopes 32 (cf. e.g. FIGS. 11 and 12 ).A variant of a design of the illumination pupil 12a is explained with reference to FIGS. 22 to 24, with which an adaptation to a field-dependent exit pupil 36 is made possible. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 21, particularly with reference to FIGS. 7 to 21 and specifically with reference to FIGS. 19 to 21 are given the same reference numerals and will not be discussed in detail again.In the pupil adaptation according to FIGS. 22 to 24, the respective illumination pupil 12 ais not field-dependent, that is to say independently of the field height (x=-13 mm, FIG. 22; x=0 mm, FIG. 23; x=+13 mm, FIG. 24 ) has the same positioning, shape and envelope 32 of the obscuration illumination pupil region 31 within the outer pupil edge 37. the exit pupil 36 in the embodiment according to FIGS. 22 to 24 is, on the other hand, field-dependent in the manner of the field dependence of FIGS. 19 to 21, FIG. 22 ) is shifted in the -σ y- direction and slightly tilted counter-clockwise and is shifted again in the negative σ y- direction at the right field edge (x=+13 mm, cf. FIG. 24 ) and slightly tilted clockwise about the pupil coordinate σ z. In the field-independent illumination pupil 12a according to FIGS. 22 to 24, the obscured illumination pupil region 31 is smaller than the obscured exit pupil region 38 by such an amount that the obscured illumination pupil region 31 is always completely within the obscured exit pupil region 38, regardless of the field dependence of the position and orientation of the obscured exit pupil region 38, as illustrated in FIGS. 22 to 24.In accordance with what was explained above in particular in connection with FIGS. 19 to 24 for an x-dependence of the illumination pupil 12 aand / or of the exit pupil 36, an adaptation of the illumination pupil 12 ato a y-field dependence of the exit pupil 36 or to a combined x / y-field dependence of the exit pupil 36 can also take place.With reference to FIGS. 25 and 26, a further embodiment of the illumination pupil 12 a, which is adapted to the associated exit pupil 36 of the projection optical unit 10, is explained below. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 24 and in particular with reference to FIGS. 7 to 24 are given the same reference numerals and will not be discussed in detail again.The illumination pupil 12 aaccording to FIGS. 25 and 26 is generated with the aid of an illumination optical unit 11 of the projection exposure apparatus 1, in which the first facet mirror 6 is arranged in a field plane of the illumination optical unit 11 and the second facet mirror 7 is arranged in a pupil plane of the illumination optical unit 11.The illumination pupil 12 ain accordance with FIGS. 25 and 26 is shown there in differently scaled pupil coordinate systems.FIG. 25 shows a representation of the illumination pupil 12 aselected in normalized pupil coordinates σ x, σ y in which the outer pupil edge 37 has the same σ x / σ y- value in each case at the location of the maximum possible object field illumination angle. The pupil coordinates σ x, σ y are thus normalized in FIG. 25 such that a circular outer pupil edge 37 inevitably results in absolute pupil coordinates independently of its actual shape. The pupil representations in FIGS. 9 to 24 are also effected in normalized pupil coordinates σ x, σ y. of this type.FIG. 26 shows the illumination pupil 12 aaccording to FIG. 25 in absolute pupil coordinates ρ x, ρ y, that is to say in coordinates which represent a measure of the actual illumination angle on the object field. Such absolute pupil coordinates ρ x, ρ y are, for example, coordinates which represent a measure of a sine of the angle of incidence of the illumination light 3 on the object field 8. In these actual, absolute pupil coordinates ρ x, ρ y the illumination pupil 12 ais overall elliptical with a longer half axis along the pupil coordinate ρ x. In addition, the illumination pupil 12 ain the absolute pupil coordinates has an elliptical obscuation illumination pupil region 31 with a likewise elliptical envelope 32 with a longer half axis along the pupil coordinate ρ x. Indicated in FIGS. 25 and 26 are sites of incidence 33 i of corresponding illumination channels 27 i, which are arranged distributed in the obscuration illumination pupil region 31 and each lead over a field facet 21 and a pupil facet 25.A half-axis ratio of the envelopes 32 can differ from the half-axis ratio of the outer pupil edge 37, so that although a circular outer pupil edge 37 results in the representation in normalized pupil coordinates according to FIG. 25, no circular envelope 32 of the obscuation illumination pupil region 31 results.In the illumination pupils 12 a, which are explained below with reference to FIGS. 27 to 42 and are respectively adapted to the corresponding exit pupil 36, the pupil is respectively shown in normalized pupil coordinates σ x, σ y according to FIG. 25 in a first figure and in absolute pupil coordinates ρ x, ρ y according to FIG. 26 in a subsequent figure.The illumination pupils according to FIGS. 27 to 42 are also produced by means of an illumination optical unit 11 in the manner of a so-called honeycomb condenser, in which the first facet mirror 6 is arranged in a pupil plane of the illumination optical unit 11 and the second facet mirror 7 is arranged in a pupil plane of the illumination optical unit 11.With reference to FIGS. 27 and 28, a further pupil embodiment is described below, which can be used instead of the illumination pupils explained above, each adapted to an exit pupil. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 26, particularly with reference to FIGS. 7 to 26 and in particular with reference to FIGS. 25 and 26, bear in particular the same reference numerals and are not discussed in detail again.In the illumination optical unit 12 aaccording to FIGS. 27 and 28, the illumination light 3 is not applied to the illumination pupil region 31 within the envelope 32. Between the envelope 32 and the outer pupil edge 37, sites of incidence 33 i of the illumination channels 27 i set via the tilt angles of the facets 21, 25 of the illumination optical unit 11 are present in a distributed arrangement, so that a homogeneous illumination intensity within predefined tolerances is present per area proportion of the illumination pupil 12 abetween the envelope 32 and the outer pupil edge 37. In this respect, the illumination setting 12 aaccording to FIGS. 27 and 28 is comparable to that according to FIG. 11. In contrast to this, the obscuation illumination pupil region 31 is centered at the illumination pupil 12 aaccording to FIGS. 27 and 28 and the envelope 32 has an approximately elliptical shape in the absolute pupil coordinates ρ x, ρ y( cf. FIG. 28 ) and an approximately stadione-shaped shape in the normalized pupil coordinates σ x, σ y( cf. FIG. 27 ).With reference to FIGS. 29 and 30, a further pupil embodiment is described below, which can be used instead of the illumination pupils explained above, each adapted to an exit pupil. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 28, particularly with reference to FIGS. 7 to 28 and in particular with reference to FIGS. 25 and 28, bear in particular the same reference numerals and are not discussed in detail again.In the case of the illumination pupil 12 aaccording to FIGS. 29 and 30, illumination with the illumination light 3 takes place between the envelope 32 of the obscuration illumination pupil region 31 on the one hand and the outer envelope 34 of the outer illumination pupil region 35 on the other hand. Apart from the fact that pupil illumination does not take place within the illumination pupil region 31 in the case of the illumination pupil 12 a, the illumination pupil 12 aaccording to FIGS. 29 and 30 is comparable in this respect to that according to FIG. 8.Illumination pupil illumination does not take place either within the envelope 32 or between the outer envelope 34 and the outer pupil edge 37 in the case of the illumination pupil 12 aaccording to FIGS. 29 and 30.As for the boundary shape of the envelope 32, the illumination pupil 12a of Figs. 29 and 30 is comparable to that of Figs. 27 and 28.In the representation according to FIG. 29, the outer envelope 34 has a circular shape in normalized pupil coordinates and is again elliptical with a longer half axis along the pupil coordinate ρ x. in absolute pupil coordinates (cf. FIG. 30 ).With reference to FIGS. 31 and 32, a further pupil embodiment is described below, which can be used instead of the illumination pupils explained above, each adapted to an exit pupil. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 30, particularly with reference to FIGS. 7 to 30 and in particular with reference to FIGS. 25 and 30 bear in particular the same reference numerals and are not discussed in detail again.In the case of the illumination pupil 12 aaccording to FIGS. 31 and 32, the obscuation illumination pupil region 31 and the outer illumination pupil region 35 between the envelope 32 and the outer envelope 34 are illuminated in i with the illumination light 3 via corresponding points of incidence 33. In an illumination pupil environment around the envelope 32, which in turn corresponds to a region of the exit pupil 36 adjacent to an edge of the associated obscured exit pupil region 38, the illumination pupil 12 ais not impinged on by the illumination light 3. In this respect, the illumination pupil 12 aaccording to FIGS. 31 and 32 corresponds to that according to FIG. 16.Also shown in FIG. 32 is a minimum distance 2 Δ between points of incidence 33 i of the illumination light 3, on the one hand within the envelope 32 and, on the other hand, outside the envelope 32.With reference to FIGS. 33 and 34, a further pupil embodiment is described below, which can be used instead of the illumination pupils explained above, each adapted to an exit pupil. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 32, particularly with reference to FIGS. 7 to 32 and in particular with reference to FIGS. 25 and 32, bear in particular the same reference numerals and are not discussed in detail again.The illumination pupil 12 aaccording to FIGS. 33 and 34 is a superposition on the one hand of a dark-field illumination pupil according to the type of FIG. 25 and on the other hand of an x-dipole illumination pupil with poles I 1, I 2, which represent an illumination in two σ x / ρ x- pupil coordinate regions in the form of pupil strips running along the pupil coordinate σ y / ρ y. In comparison with the illumination pupil 12 aaccording to FIG. 14, the illumination poles I 1, I 2 are implemented continuously, that is to say have no interruption at the location of the σ y / ρ y- pupil coordinates of the obscured illumination pupil region 31.With reference to FIGS. 35 and 36, a further pupil embodiment is described below, which can be used instead of the illumination pupils explained above, each adapted to an exit pupil. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 34, particularly with reference to FIGS. 7 to 34 and in particular with reference to FIGS. 25 and 34, bear in particular the same reference numerals and are not discussed in detail again.The illumination pupil 12 aaccording to FIGS. 35 and 36 corresponds to that according to FIG. 14, except for the boundary shape of the envelope 32 and of the outer pupil boundary 37, which is elliptical in absolute pupil coordinates (cf. FIG. 36 ) in each case, and for the fact that the illumination pupil 12 aaccording to FIGS. 35 and 36 is produced with a second facet mirror 7 arranged in a pupil plane of the illumination optical unit 11.The four illumination poles I 1 to I 4 of the illumination pupil 12 aaccording to FIGS. 35 and 36 can be understood as dipole illumination setting according to FIGS. 33 and 34 with Δσ y / Δp y- interruption of the σ y / p y- illumination strips along the pupil coordinates σ y / ρ y of the obscurating illumination pupil region 31.With reference to FIGS. 37 and 38, a further pupil embodiment is described below, which can be used instead of the illumination pupils explained above, each adapted to an exit pupil. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 36, particularly with reference to FIGS. 7 to 36 and in particular with reference to FIGS. 25 and 36, bear in particular the same reference numerals and are not discussed in detail again.Comparable to the illumination optics 12 aaccording to FIGS. 35 and 36, the illumination pupil 12 aaccording to FIGS. 37 and 38 is a superposition of a dark-field illumination pupil according to FIGS. 25 and 26 and a quadrupole illumination setting with four illumination poles I 1 to I 4.Unlike the illumination pupil 12 aaccording to FIGS. 35 and 36, the four poles I 1 to I 4 of the quadrupole illumination setting portion of the illumination pupil 12 aaccording to FIGS. 37 and 38 are formed within two pupil strips in predefined σ y / p x- regions which each extend along the σ x / ρ x- pupil coordinate and are interrupted in Δ σ x / Δ ρ x- pupil coordinate regions, which correspond to the σ x / ρ x- pupil coordinates of the obscuation illumination pupil region 31.Unlike explained in the case of the above-described illumination pupils 12 a, for example the illumination pupils 12 aaccording to FIGS. 9A / 9B, 10, 12, 17 and 18, the illumination pupil 12 aaccording to FIGS. 37 and 38 takes into account a diffraction of the illumination light 3 at structures of the reticle 12 along the pupil coordinate σ y / ρ y, which then represents the diffraction pupil coordinate. The illumination light recesses between the poles I 1 and I 2 on the one hand and the poles I 3 and I 4 on the other hand ensure that imaging light 3 diffracted along the pupil coordinate σ y / ρ y into the exit pupil 36 is not undesirably diffracted into the obscuation illumination pupil region 31.With reference to FIGS. 39 and 40, a further pupil embodiment is described below, which can be used instead of the illumination pupils explained above, each adapted to an exit pupil. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 38, particularly with reference to FIGS. 7 to 38 and in particular with reference to FIGS. 25 and 38, bear in particular the same reference numerals and are not discussed in detail again.In the case of the illumination pupil 12 aaccording to FIGS. 39 and 40, central dark-field illumination is again present within the obscuration illumination pupil region 31, corresponding to the illumination pupil 12 aaccording to FIGS. 25 and 26, in the negative σ x / ρ x- direction (I 3) and in the negative σ y / ρ y- direction (I 4). Unlike the illumination pupils 12 ahaving four illumination poles I 1 to I 4 already described above, the four illumination poles I 1 to I 4 are therefore not present within the four quadrants Q 1 to Q 4 during the illumination setting according to FIGS. 39 and 40, but rather in the direction of the pupil coordinates + / -σ x and + / -σ y. The illumination poles I 1 to I 4 are each arranged close to the outer pupil edge 37, i.e. lead to illumination of the object field 8 with comparatively large illumination angles. In the range of normalized pupil coordinates, the illumination poles I 1 to I 4 i.e. at a σ-coordinate radius between 0.8 and 1, are arranged.With reference to FIGS. 41 and 42, a further pupil embodiment is described below, which can be used instead of the illumination pupils explained above, each adapted to an exit pupil. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 40, particularly with reference to FIGS. 7 to 40 and in particular with reference to FIGS. 25 and 40, bear in particular the same reference numerals and are not discussed in detail again.The illumination pupil 12 aaccording to FIGS. 41 and 42 again contains an illumination of the obscured illumination pupil region 31 as in the case of the illumination pupil 12 aaccording to FIGS. 25 and 26, that is to say a dark-field illumination portion. In addition, in the illumination pupil 12 aaccording to FIGS. 41 and 42, there are eight further illumination poles I 1 to I 8 present.The illumination poles I 1 to I 4 are arranged in the manner of the illumination poles I 1 to I 4 of the illumination pupil 12 aaccording to FIGS. 39 and 40.The additional illumination poles I 5 to I 8 are arranged in the four quadrants of the illumination pupil 12 aaccording to FIGS. 41 and 42 in the region of medium illumination angles, that is to say in the region of normalized pupil coordinates σ x, σ y with a radius of about 0.5.With reference to FIGS. 43 and 44, a further illumination pupil 12 ais described below, which is adapted to a corresponding exit pupil 36. Components and functions which have already been explained above with reference to FIGS. 1 to 42 and in particular with reference to FIGS. 7 to 42 have the same reference numerals and are not discussed in detail again.FIG. 43 shows a setpoint illumination pupil 45 which can be the result of a simulation calculation for optimizing the illumination of a reticle 12 structured in a specific manner. The target illumination pupil has an intensity distribution of the illumination light 3 basically corresponding to that of the illumination pupil 12 ain FIG. 29. The illumination light 3 is intended to illuminate the desired illumination pupil 45 in a region between the envelope 32 of the obscuration illumination pupil region 31, which in turn is adapted to the obscuration exit pupil region of the exit pupil 36, and the outer envelope 34 of the outer illumination pupil region 35.The envelope 32 of the obscuation illumination pupil region 31 has, in the case of the desired illumination pupil 45, an edge shape in the form of an approximately split-line, having two straight lines which run along the σ x- pupil straight line and two curves connecting these two straight lines. The outer envelope 34 has a circular shape in pupil coordinates. Between the inner envelope 32 and the outer envelope 34, a homogeneous and constant intensity distribution with the illumination light 3 is present at the desired illumination pupil 45.The illumination pupil 12 aaccording to FIG. 44 is illustrated as a so-called x-field means. Illumination pupil 12 ais therefore shown averaged over all field heights x of object field 8.The desired illumination pupil 45 according to FIG. 43 can be specified in the form shown in normalized pupil coordinates, for example according to FIG. 25, or else in absolute pupil coordinates, for example in the manner of FIG. 26. For example, the outer pupil edge 37 can be circular in normalized pupil coordinates, as shown in FIG. 43, but can also be circular in absolute pupil coordinates.FIG. 44 shows an illumination pupil 12 awhich represents an actual illumination pupil which is approximated to the setpoint illumination pupil 45 according to FIG. 43 and which was generated with the illumination optical unit 11 with the second facet mirror 7 at a distance from a pupil plane of the illumination optical unit 11 (cf. the exemplary illumination optical unit 11 according to FIG. 6 ). Due to the flexibility of the assignment and adjustment options of the individual mirrors ES and in particular of the grouping options of these individual mirrors ES of the two facet mirrors 6, 7 to the transmission facet groups 21 and to the illumination specification facet groups 25, the desired illumination pupil 45 according to FIG. 43 can be reproduced practically perfectly in the x-field average with the actual illumination pupil 12 aaccording to FIG. 44. In particular, in the x-field means, i.e. in addition to the y-field coordinate, integrated via the x-field coordinate, a homogeneous and constant illumination within the envelopes 32 and 34 or optionally also an approximation to a desired intensity distribution can be achieved.With reference to FIGS. 45 to 46, a sequential and / or parallel, field-dependent use of various of the above-described illumination pupils 12a in the imaging of various regions of an exemplary reticle 12 is explained. Components and functions corresponding to those already described above with reference to FIGS. 1 to 44 are given the same reference numerals and will not be discussed in detail again.The reticle 12 according to FIG. 45 has fine structure regions 46, which require a particularly high resolution of the projection exposure by means of the projection exposure apparatus 1. The fine structures 46 can be, for example, very closely spaced lines along the y-direction, that is to say vertical lines in FIG. 45.In addition, in an x-field height range, the reticle 12 has coarse structures 47 with a typical structure extension which is greater than that of the fine structures 46.Between the field height regions with the fine structures 46 and the field height regions with the coarse structures 47, transition regions 48 are also present on the reticle 12. Fine structures 46 can likewise be present on the reticle 12 in the transition regions 48. The transition regions 48 are spatially adjacent to the regions with the coarse structures 47.FIG. 46 shows, by way of example, an adapted illumination pupil 12 afor the fine structures 46.The illumination pupil 12a according to FIG. 46 is used for the x-field heights of the reticle in which the fine structures 46 are present. Between the illumination poles I 1 and I 2 on the one hand and the illumination poles I 3 and I 4 on the other hand, a diffraction offset or diffraction distance d is present along the pupil coordinate σ x on account of the diffraction of the illumination light 3 at the fine structures 46, which diffraction offset or diffraction distance d corresponds to the σ y- distance of these two poles I 1, I 2 on the one hand and I 3, I 4 on the other hand.The illumination optical unit 11 is also adjusted such that an illumination setting 12 adifferent from the illumination setting 12 aaccording to FIG. 46, which corresponds to the illumination setting 12 aaccording to FIG. 14, is adjusted at the x-field heights of the coarse structures 47 and the transition regions 48. The coarse structures 47 and also the structures of the reticle in the transition region 48 are therefore illuminated with the illumination setting 12 aaccording to FIG. 47, including dark-field illumination within the obscuration illumination pupil region 31. Since only fine structures of the reticle 46 are also present in the transition region 48, the illumination light radiated into the obscuration illumination pupil region 31 is diffracted at the latter in accordance with the diffraction offset d toward pupil regions B+, B- outside the outer pupil edge 37, which are blocked by the aperture stop of the projection optical unit 10 and therefore do not arrive on the wafer 19 in an undesirable manner.With reference to FIGS. 48 and 49, different edge contours of an obscured exit pupil region 38 are explained below, to which a corresponding illumination pupil 12 a, in particular an obscured illumination pupil region, can be adapted with the aid of the techniques described above. Components and functions corresponding to those already explained above with reference to FIGS. 1 to 47 are given the same reference numerals and will not be discussed in detail again.FIG. 48 shows variants of edge contours 49 i of the obscuration exit pupil region 38. these edge contours 49 i can be used in parametrized fashion in their shape to specify corresponding envelopes 32 of the obscuration illumination pupil region 31 of the respective illumination pupil 12 ain the context of a method for calculating corresponding controls of the individual mirrors ES or of the facets 21, 25 of the illumination optical unit 11.FIG. 48 shows edge contours 49 i of the obscuration exit pupil region 38 which are assigned to a first design of the projection optical unit 10 of the projection exposure apparatus 1.The edge contour 49 1 of the obscuation exit pupil region 38 has the shape of a vertical ellipse with a long half axis along the pupil coordinate σ y.The edge contour 49 2 has an approximate drop shape with a straight contour section lying at the bottom in FIG. 48. This edge contour 49 2 represents a variant of a parameterization of an actual edge contour of the obscuration exit pupil region 38 of the first design of the projection optical unit 10 that is not rotationally symmetrical and also not rotationally symmetrical several times.The edge contour 49 3 represents a circular shape into which the edge contour 49 1 is inscribed, i.e. represents the smallest circular diameter which completely accommodates the edge contour 49 1.The edge contour 49 4 represents the smallest rectangle which holds the edge contour 49 1 therein, i.e. along both the σ x- coordinate and the σ y- coordinate has edge lengths which correspond to the corresponding dimensions of the edge contour 49 1.The edge contour 49 5 represents a circular shape, the surface area of which is just as large as that of the edge contour 49 1.With the edge contours 49 1 to 49 5 it is possible to approach an actual edge contour of the obscuration exit pupil region 38 of the projection optical unit 10 in a parameterized manner such that these edge contours 49 1 to 49 5 can be used to specify the envelope 32 of the obscuration illumination pupil region of an illumination pupil 12 aadjusted to this exit pupil 36.FIG. 49 shows corresponding approximations of edge contours 50 1 to 50 5 to an actual edge contour of an obscuration exit pupil region 38 of a further design embodiment of the projection optical unit 10 of the projection exposure apparatus 1.The edge contour 50 1 has approximately the shape of a lying ellipse with a greater extent along the pupil coordinate σ x.The edge contour 50 2 again represents an asymmetric edge contour parameterization, which has approximately the shape of a spherical triangle.The edge contour 50 3 again represents a circular shape into which the edge contour 50 1 is inscribed.The edge contour 50 4 represents a rectangle into which the edge contour 50 1 is inscribed.The edge contour 50 5 represents a circular shape having an area equal to that of the edge contour 50 1.As far as the parameterization boundary conditions are concerned, the edge contours 50 1 to 50 5 i.e. the edge contours 49 1 to 49 5, now correspond to the further design of the projection optical unit 10, i.e. to an alternative edge contour design of the actual obscuration exit pupil region 38.The following boundary conditions can apply for possible edge contour shapes of the envelope 32 of the obscuration illumination pupil region 31, which can be used to adapt to an arrangement, orientation and shape of an edge contour of the obscuration exit pupil region 38:An average radius of the envelope 32, expressed in normalized pupil coordinates σ x, σ y can be in the range between 0.1 and 0.3 and in particular between 0.2 and 0.22.A variation of the mean radius of the envelope 32 along the x-field height can be effected within a tolerance of at most 10%, of at most 5%, of at most 2% or else of at most 1%. This variation of the mean radius represents a field dependence of the obscuation illumination pupil region 31.A σ x- decentration and / or σ y- decentration can lie in normalized pupil coordinates in the range between -0.2 and +0.2, in particular in the range between -0.1 and +0.1 and, for example, in the range between -0.05 and +0.05 or also in the range between -0.005 and +0.005. This decentration of the envelope 32 can be field height dependent, as explained above, for example, in connection with FIGS. 19 to 21.A deviation of the envelope 32 from an ideal circular shape, described for example by the ratio of ellipse half-axis lengths, can lie in the range between 0.5 (ratio of the half-axis lengths 1:2) and 2 (ratio of the half-axis lengths 2:1).In general, an edge contour of the obscuation exit pupil region 38 and / or an edge contour of the envelope 32 of the obscuation illumination pupil region 31 can be parameterized as follows using the example of the envelope 32, e.g. in the normalized pupil coordinates σ x, σ y r(φ) is the radius of the envelope 32, measured from a center of the entry pupil 12 a, for example from a centroid of the outer pupil edge 37 in the direction of the respective azimuth angle φ; r 0 is a mean radius of the envelope 32; s n and c n are coefficients of the respective Fourier contributions of the order n. s 1 ensures, for example, decentration of the envelope 32.c 2 describes, for example, for small values an approximately elliptical deviation of the shape of the envelope from an ideal circular shape.In order to prepare for the production of a microstructured component, it is first checked which structure distribution and in particular which structure size distribution and structure orientation distribution is present on the reticle 12. In addition, the exit pupil 36 and in particular the shape of an envelope of the obscuation exit pupil region 38 is parameterized, as explained above. On the basis of the result of the reticle examination and the parameterization of the exit pupil 36, a setpoint illumination pupil, for example one of the variants explained above, is then specified and set as illumination pupil 12 awith the aid of the illumination optics 11 of the projection exposure apparatus 1.In order to produce the microstructured component, in particular a highly integrated semiconductor component, for example a memory chip, with the aid of the projection exposure apparatus 1, the reticle 12 and the wafer 19 are then provided. The structures on the reticle 12 are then illuminated with the illumination light 3 using the correspondingly set illumination optics 11 and projected onto a light-sensitive layer on the wafer 19 using the projection optics of the projection exposure apparatus 1. By developing the light-sensitive layer, a microstructure is then produced on the wafer 19 and the micro- or nanostructured component is produced therefrom.The component produced can be a microchip, in particular a memory chip.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedWO 2012 / 028303 A1

[0002] U.S. Pat. No. 10,139,734 B2

[0002] U.S. Pat. No. 10,254,653 B2

[0002] DE 10 2021 200 114 A1

[0002] U.S. Pat. No. 9,720,329 B2

[0002] WO 2010 / 099 807

[0055] US 2006 / 0132747 A1

[0061] Cited Non-Patent LiteratureLevinson et al., "Lithographic pattern formation in the presence of aberrations in anamorphic optical systems", Proc. of SPIE Vol. 11323 1132230A-1, 2020

[0002] Technical article de Winter et al., "Extreme ultraviolet scanner with high numerical aperture: observation and wavefront description", J. Micro / Nanopattern. Mater. Metrol. 023801-2, 2022

[0002] The method of the present invention is described in detail in the paper by de Winter et al., "High NA EUV scanner: observation and wavefront description", Proc. of SPIE Vol. 11517 1151715-1, 2020

[0002] Van Setten et al., "High NA EUV lithography: Next step in EUV imaging", Proc. of SPIE Vol. 10957 1095709-01, 2019

[0002] Peng et al., "Physical dose modeling and throughput optimization in EUV computational lithography", Proc. of SPIE Vol. 12494 124940C-1, 2023

[0002] Maguire et al., "Defining Tian-Zero polynomials for use in a lithography simulator", Proc. Of SPIE Vol. 12494 124940P-1, 2023

[0002] Zhao et al., "Computational lithography solutions to support EUV high-NA patterning", Proc. Of SPIE Vol. 12495 124950R-1, 2023

[0002] Van Schoot et al., "High-NA EUV lithography exposure tool: program progress", Proc. Of SPIE Vol. 11323 11321132307-1, 2023

[0002] Schweimier et al., "High-NA EUV lithography optics become reality", Proc. Of SPIE Vol. 11323 1132308-1, 2020

[0002] Van Schoot et al., "High-NA EUV lithography exposure tool: advances and program progress", Proc. Of SPIE Vol. 11517 1151712-1, 2020

[0002] Gao et al., "Computational evaluation of critical logical metal layers of pitch 20-24 nm and the aberration sensitivity in high NA EUV single patterning", Proc. Of SPIE Vol. 12495 1249509-1, 2023

[0002]

Claims

Optical system for a projection exposure apparatus (1) - having an illumination optical unit (11) for guiding illumination and imaging light (3) from a light source (2) to an object field (8), in which an object (12) to be imaged can be arranged, - having an imaging optical unit (10) for imaging the object field (8) into an image field (17), in which a substrate (19) to be exposed can be arranged, wherein the imaging optical unit (10) has an exit pupil (36) having at least one obscured exit pupil region (38) lying within an outer pupil edge (37), - wherein the illumination optical unit (11) is designed such that an illumination angle distribution of an illumination of the object field (8) with the illumination and imaging light (3) results, which can be written via an illumination pupil (12a), the illumination pupil region (31; I i; 35) of which, to which illumination light is applied, is adapted to the obscuation exit pupil region (38) of the imaging optical unit (10), - wherein the obscuation exit pupil region (38) of the imaging optical unit (10) has a noncentre geometric centre of gravity (SP).Optical system for a projection exposure apparatus (1) - having an illumination optical unit (11) for guiding illumination and imaging light (3) from a light source (2) to an object field (8), in which an object (12) to be imaged can be arranged, - having an imaging optical unit (10) for imaging the object field (8) into an image field (17), in which a substrate (19) to be exposed can be arranged, wherein the imaging optical unit (10) has an exit pupil (36) having at least one obscured exit pupil region (38) lying within an outer pupil edge (37), - wherein the illumination optical unit (11) is designed such that an illumination angle distribution of an illumination of the object field (8) with the illumination and imaging light (3) results, which can be written via an illumination pupil (12a), the illumination pupil region (31; I i; of which is exposed to illumination light; 35) adapted to the obscuration exit pupil region (38) of the imaging optics (10), - wherein the illumination optics (11) are designed such that the object field (8) results in an illumination angle distribution which can be written via an illumination pupil (12a) with an obscuration illumination pupil region (31), the envelope (32) of which deviates from a circular shape in pupil coordinates (σ x, σ y), which are normalized to the outer pupil edge (37), and / or in absolute pupil coordinates (ρ x, ρ y).Optical system according to Claim 1 or 2, characterized bya configuration such that the illumination pupil (12a) is not acted upon by the illumination light (3) in at least one illumination pupil region (31) which corresponds to the obscuration exit pupil region (38).Optical system according to one of Claims 1 to 3, designed for illuminating an object structure of the object (12) which leads to diffraction of the imaging light (3) after the object (12) along a diffraction pupil coordinate (σ x, σ y) of the exit pupil (36), the illumination pupil (12a) not being acted upon by the illumination light (3) in an illumination pupil coordinate range (Δσ y) of a cross-diffraction pupil coordinate (σ y) perpendicular to the diffraction pupil coordinate (σ x), which corresponds to the extent of the obscuation exit pupil region (38) along this cross-diffraction pupil coordinate (σ y).Optical system according to one of Claims 1 to 4, characterized in that the illumination pupil (12a) has an illumination pupil region (31), in which the illumination pupil (12a) is not acted upon by the illumination light (3), wherein illumination angles which are assigned to the illumination pupil region (31) correspond at least partially overlapping to imaging beam angles of zeroth order of diffraction of the illumination exit pupil region (38), and wherein illumination pupil regions (35 i, I), in which the illumination pupil (12a) is acted upon by the illumination light (3), are arranged directly adjacent to the illumination pupil region (31).Optical system according to one of Claims 1, 2, 4 or 5, characterized bya configuration such that the illumination pupil (12a) is acted upon by the illumination light (3) with an obscuration illumination pupil region (31), which corresponds to the obscuration exit pupil region (38).Optical system according to Claim 6, characterized bya configuration such that the illumination pupil (12a) is impinged on by the illumination light (3) in an illumination pupil region (35) which contains the illumination pupil region (31).Optical system according to Claim 7, characterized in that the illumination pupil region (31, 35) is not acted upon by the illumination light (3) in an illumination pupil environment (Δ) which corresponds to a region of the exit pupil adjacent to an edge of the obscured exit pupil region (38).Optical system according to Claim 6, characterized bya configuration such that the illumination pupil (12a) is exposed to the illumination light (3) exclusively in an obscuration illumination pupil region (31) which corresponds to the obscuration exit pupil region (38).Optical system according to Claim 9, characterized in that at least one subsection (40, 41) is present in the obscuation exit pupil region (38), in which subsection the illumination light (3) is not applied to the obscuation illumination pupil region (31).Optical system according to one of Claims 1 to 10, characterized bya field-dependent illumination pupil (12a) via the object field (8).Optical system according to one of Claims 1 to 10, characterized in that the imaging optical unit (10) is designed in such a way that the exit pupil (36) of the imaging optical unit (10) is field-dependent over the object field (8), wherein the illumination optical unit (11) is designed in such a way that the illumination pupil (12a) has a field dependence which corresponds to that of the exit pupil (36).Optical system according to one of Claims 1 to 12, wherein an outer edge contour (49 i, 50i) of the obscuation exit pupil region (38) has a shape which can be described by means of at least one of the following parameters: - average radius of the edge contour (49 i, 50i) in the range between 0.1 and 0.3 of a normalized pupil coordinate radius, - decentration of the edge contour (49 i, 50i) in the range between 0.0025 and 0.05 of the normalized pupil coordinate radius, - average deviation of the edge contour (49 i, 50_ner21_) of a circular shape in the range between 0.01 and 0.2 of the normalized pupil coordinate radius.Optical system according to one of Claims 1 to 13, characterized in that the illumination optical unit (11) has: - a field facet mirror (6) arranged in a field plane of the illumination optical unit (11), and - a pupil facet mirror (7) arranged in a pupil plane of the illumination optical unit (11).Illumination optical unit according to one of Claims 1 to 14, characterized in that transmission facets of a transmission facet mirror of the illumination optical unit and / or illumination specification facets of an illumination specification facet mirror of the illumination optical unit are divided into a plurality of individual mirrors (ES) which can be tilted independently in order to specify the illumination pupil (12a).Optical system according to one of Claims 1 to 15, characterized bya light source (2) for the illumination and imaging light (3).Projection exposure apparatus having an optical system according to one of Claims 1 to 16.Method for presetting an illumination pupil (12a) of an illumination optical unit (11) for illuminating an object field (8), in which an object (12) to be imaged can be arranged, with illumination light (3), having the following steps: - analyzing a diffraction behavior of at least one object structure (46, 47) of the object (12), - detecting a position of an obscuation exit pupil region (38) in an exit pupil (36) of an imaging optical unit (10) for imaging the object (12), - adapting the illumination pupil (12a) such that an optical system according to one of Claims 1 to 15 results.Method according to Claim 18, characterized in that a field dependence of the illumination pupil (12a) adapted to the exit pupil (36) and / or to the object structure (46, 47) results.Method for producing a microstructured component, having the following method steps: - carrying out the method according to Claims 16 or 17, - providing the object (12) having the analyzed diffraction behavior in the form of a reticle (12), - providing a wafer (19) having a coating sensitive to the illumination light (3), - projecting at least one section of the reticle (12) onto the wafer (19) with the aid of the projection exposure apparatus (1) according to Claim 17 using the optical system having a correspondingly adapted illumination pupil (12a), - developing the light-sensitive layer exposed to the illumination light (3) on the wafer (19).Component produced by a method according to Claim 20.

Images