Optical assembly

Abstract

An optical assembly (17) has a primary optical bar (28) for guiding illumination light (4) along an illumination-light beam path from a light source to a target field. A following optical bar (29) of the optical assembly (17) is arranged in the illumination-light beam path between the primary bar (28) and the target field. An intermediate-image-generating optical unit (30) is arranged between the primary bar (28) and the following bar (29). The intermediate-image-generating optical unit generates an intermediate image between the primary bar (28) and the following bar (29) along exactly one imaging dimension (y) transversely to the illumination-light beam path. This results in an optical assembly in the case of which the illumination light has a defined polarization state after passing through the optical assembly. The optical assembly can be part of an illumination optical unit and can be, in particular, part of an optical system of a projection exposure system, said optical system containing such an illumination optical unit.

Description

[0001] Optical assembly

[0002] The content of the German patent application DE 10 2024 207 296.6 is incorporated herein by reference.

[0003] The invention relates to an optical assembly. Furthermore, the invention relates to an illumination optic with such an optical assembly, an optical system with such an illumination optic, a projection exposure system with such an optical system, a method for producing a micro- or nano-structured component with such a projection exposure system, and a structured component produced by such a method.

[0004] An optical assembly as part of an illumination optic for projection lithography is known from WO 2005 / 015 310 A2, DE 10 2004 059 493 Al, and WO 2016 / 188 739 AE. DE 10 2016 106 518 Al discloses an optical system for an endoscope. DE 695 09 638 T2 discloses a system for minimizing the depolarization of a laser beam caused by thermally induced birefringence. DE 10 2022 205 273 B3 discloses an illumination system, a projection exposure system, and a projection exposure method.

[0005] It is an object of the present invention to further develop an optical assembly of the type mentioned at the outset in such a way that the illumination light, after passing through the optical assembly, has a defined polarization state, in particular that the polarization state of the illumination light, which it has before entering the optical assembly, is retained. This object is achieved according to the invention by an optical assembly with the features specified in claim 1.

[0006] According to the invention, it has been recognized that an undesirable polarization effect on the illumination light as it passes through an optical rod used for light mixing can be sufficiently compensated by the use of the optical assembly with two optical rods and an intermediate image-generating optic. In particular, an undesirable accumulation of a geometric phase resulting from internal reflections of the illumination light at the rod cladding walls, and its polarization-influencing effect, can thereby be avoided or reduced.

[0007] The intermediate image is generated along exactly one imaging dimension, perpendicular to the path of the illumination light. This results in individual rays of the illumination light passing through the intermediate beam with a geometric phase accumulation that is subtractive compared to the primary beam.

[0008] The rods of the optical assembly can have entry and exit surfaces with square, rectangular, round, or hexagonal edge contours. The edge contour of the primary rod can differ in shape and / or orientation from the edge contour of the secondary rod.

[0009] Such an optical assembly with a defined polarization state of the transmitted illumination light can be used as part of the illumination optics of a projection exposure system for the lithographic fabrication of micro- or nanostructured components. The light mixing by the primary and secondary beams of the optical assembly leads to a desired homogenization of both the intensity distribution across the illuminated area and the distribution of illumination directions. These homogenized intensity and illumination angle distributions can be further modified, for example, by additional components of the illumination optics, allowing them to be adjusted to a desired target distribution.As an alternative to use in a projection exposure system, such an optical assembly can also be used as part of a polarization DIC (Differential Interference Contrast) microscope. Such a polarization DIC microscope is described in the article by Murphy, D.: Differential interference contrast (DIC) microscopy and modulation contrast microscopy, in Fundamentals of Light Microscopy and Digital Imaging, Wiley-Liss, New York, pp. 153-168 (2001). Further references on polarization DIC microscopy can be found in the Wikipedia article “Differential interference contrast microscopy”, accessed on April 12, 2024.

[0010] When the optical assembly is used in an illumination optic of a projection exposure system for lithography, in particular a tangential polarization can be maintained to the desired extent in an annular illumination setting or in a dipole illumination setting.

[0011] In a polarization DIC microscope, for example, a constant linear polarization can be maintained to the desired extent.

[0012] An intermediate image generation optic according to claim 2 can be arranged, in particular, symmetrically with respect to a mirror plane between the two rods, i.e., between the primary rod and the secondary rod. An embodiment of the imaging components of the intermediate image generation optic according to claim 3 can, in particular, lead to a compact intermediate image generation optic. The respective imaging component can be formed onto the respective rod by machining an end face of the respective rod. Alternatively, this can be achieved by blasting the imaging component onto the end face of the respective rod or by bonding the imaging component to the rod end face. Alternatively, the imaging component can also be mechanically clamped to the respective end face of the rod.

[0013] An embodiment of the imaging component according to claim 4, comprising exactly one cylindrical optic, is a comparatively simple embodiment of the imaging component to manufacture, in which the exactly one cylindrical optic can then act on an entire beam of illumination passing through the rod. The cylindrical optic can also be parabolic-cylindrical. The cylindrical optic can be a cylindrical lens, a cylindrical mirror, or a Grin lens.

[0014] In general, the intermediate image generation optics can be designed such that translational invariance exists along one axis. Optical surfaces of the intermediate image generation optics can be designed differently along the axis orthogonal to this axis, the only requirement being that a corresponding Id-Z intermediate image, i.e., an intermediate image along exactly one imaging dimension, is realized.

[0015] An embodiment of the imaging component of the intermediate image generation optics according to claim 5, as a cylindrical optics array, can be configured as an ID array, i.e., as a row of cylindrical optics, or as a 2D array, i.e., as a grid of cylindrical optics. The respective cylindrical optics then guide either a layer of the entire beam of illumination light or a channel of the entire beam of illumination light.

[0016] A rod design according to claim 6 has proven effective in practice. Depending on the design of the optical assembly, the entry and exit surfaces for the illumination light of the primary and secondary rods can each be configured with an edge contour having an aspect ratio other than 1. The edge contour of the rod can, for example, be hexagonal.

[0017] An imaging dimension according to claim 7 can be realized by tilting the intermediate image-generating optics relative to a boundary contour coordinate system of the rods such that the desired tilting of the imaging dimension results. The angle between the imaging dimension and the coordinates that define the boundary contour of the entry and exit surfaces of the rods can be 45°. Other angles between 10° and 80°, in particular between 30° and 60°, are also possible. If the primary rod and the secondary rod have rectangular and, in particular, square entry and exit surfaces, the imaging dimension angle to the rod coordinates can be 45°. In an embodiment tilted with respect to the imaging dimension according to claim 7, a primary rod and / or a secondary rod with an aspect ratio of exactly 1 can also be used.

[0018] Such a tilted imaging dimension allows for the compensation of retardation effects in the illumination light passing through the optical assembly. Undesired retardation effects, i.e., phase splitting between the s- and p-type intrinsic polarizations of the illumination light during total internal reflection at the cladding of the rods, can be at least partially compensated for by the tilt.

[0019] A coating according to claim 8 can, for example, be used to suppress retardation. The coating can be in the form of a gradient-index coating.

[0020] This applies in particular to a coating according to claim 9.

[0021] A delay optic according to claim 10 can also be used for retardation suppression.

[0022] The at least one delay optic can be arranged between the rods of the optical assembly and / or after the follower rod in the illumination light beam path.

[0023] The advantages of an illumination optic according to claim 11, an optical system according to claim 12, a projection exposure system according to claim 13, a manufacturing method according to claim 14, and a micro- or nanostructured component according to claim 15 correspond to those already explained above with reference to the optical assembly. A light source for the illumination light can be part of the illumination optic. The light source of the illumination system can be a mercury vapor lamp, an excimer laser, or an LED light source.

[0024] A structured component, in particular a microchip, for example a memory chip, can be manufactured.

[0025] Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. This drawing shows:

[0026] Fig. 1 shows a meridional section of the main optical groups of a projection exposure system for microlithography;

[0027] Fig. 2 schematically shows an optical assembly of a projection exposure system along an illumination light beam path with excessively large distances, comprising two optical bars and an intermediate refractive intermediate image generation optic comprising two cylindrical lenses, wherein in the area after an exit surface of the respective bar a top view of this exit surface is shown with a projected path of a selected single illumination light beam, the 3D path of which is also shown in the associated perspective views of the optical bars; Fig. 3 shows a phase space mapping in one spatial dimension for the illumination light guided by the optical assembly in a path of the illumination light beam path through the optical assembly according to Fig. 2, wherein the2. An exemplary single beam is shown with respect to its phase / position relationship highlighted by a point, and the evolution of an elliptical radiance during propagation through the two optical rods of the optical assembly is shown by way of example in the area of ​​an entry surface and an exit surface of the respective rod;

[0028] Fig. 4 shows another embodiment of an optical assembly that can be used instead of the optical assembly according to Fig. 2, with a variant of the intermediate image generation optics, designed as an array of cylindrical optics;

[0029] Figs. 5 and 6 in two mutually perpendicular meridional sections show another variant of an intermediate image generation optic, which can be used either instead of the intermediate image generation optic according to Fig. 2 or instead of a channel of the cylindrical optic array according to Fig. 4, implemented as a 2f optic in a yz plane and as a 4f optic in an xz plane;

[0030] Fig. 7 shows another embodiment of an intermediate image generation optic that can be used instead of the intermediate image generation optics shown above, designed as a reflective intermediate image generation optic;

[0031] Fig. 8 shows another embodiment of an intermediate image generation optic that can be used instead of the intermediate image generation optics shown above, designed as a diffractive intermediate image generation optic;

[0032] Fig. 9 shows another embodiment of an intermediate image generating optic that can be used instead of the intermediate image generating optics shown above, designed as a Grin lens optic;

[0033] Fig. 10 shows a further representation similar to Fig. 2.

[0034] Design of the optical assembly, wherein one imaging dimension of an intermediate image generating optic is tilted, namely runs at a 45" angle to x / y coordinates, which span a rectangular boundary of the entry and exit surfaces of the two optical rods of the optical assembly;

[0035] Fig. 11 shows a grayscale retardation pupil of the primary optical rod of the optical assembly according to Fig. 10, which leads in the illumination light beam path; and Fig. 12 shows a retardation pupil of the follower optical rod of the intermediate image generation optics of the optical assembly according to Fig. 10, which follows in the illumination light beam path.

[0036] A projection exposure system 1, with regard to its main optical groups, is shown in meridional section in Fig. 1.

[0037] To facilitate the representation of spatial relationships, an xyz coordinate system is used below. In Fig. 1, the x-axis runs perpendicular to the plane of the drawing and extends outwards from it. The y-axis runs to the left in Fig. 1. The z-axis runs downwards in Fig. 1.

[0038] In Fig. 1, an optical axis 2 is indicated by a dashed line, running through the entire optical system of the projection exposure unit 1, originating from a light source 3. In the embodiment of the projection exposure unit 1 shown in Fig. 1, this optical axis 2 is folded multiple times by 90°. Such folds can also be designed differently or may even be omitted entirely.

[0039] The light or radiation source 3 of the projection exposure system 1 generates useful light in the form of an illumination or imaging beam 4, which is illustrated in Fig. 1 by marginal rays. The useful light 4 is also referred to as illumination light or imaging light. The useful light 4 has a wavelength in the deep ultraviolet (DUV) range, for example, in the range between 100 nm and 200 nm, or in the ultraviolet (UV) range between 200 nm and 400 nm. Alternatively, the useful light 4 can also have a wavelength in the extreme ultraviolet (EUV) range, in particular between 5 nm and 30 nm. Exemplary wavelengths of the radiation source 3 are 365 nm, 248 nm, and 193 nm. Depending on the radiation source 3 used, the useful wavelength spectrum is narrowband, but can also be broadband, for example, when using a mercury discharge lamp.

[0040] A lighting optic 5 of the projection exposure system 1 directs the useful light 4 from the radiation source 3 to an object plane 6 of the projection exposure system 1. Together with the light source 3, the lighting optic 5 forms a lighting system of the projection exposure system. An object to be imaged by the projection exposure system 1, in the form of a reticle 7, is arranged in the object plane 6. The reticle 7 is shown with dashed lines in Fig. 1. The reticle 7 is supported by a holding device (not shown) that allows for controlled scan displacement or stepwise displacement. As illustrated in Fig. 1, a transmissive reticle can be used, but depending on the design of the projection exposure system 1, a reflective reticle can also be used. The reticle 7 is arranged in an object field 6a in the object plane 6.

[0041] A collector 8 in the form of an ellipsoidal mirror directs the illumination light 4 emanating from a source area of ​​the light source 3 into an intermediate focus 9. A shutter is located there to control the release of the illumination light 4 to the components of the optical system along the optical axis 2. A safety shutter 10 is positioned in the beam path of the illumination light 4 upstream of this intermediate focus shutter. Downstream of the intermediate focus 9 in the beam path of the illumination light 4 is a pupil-shaping optic 11 of the illumination optic 5. The pupil-shaping optic 11 serves to generate a defined intensity distribution of the illumination light 4 in a downstream pupil plane of the illumination system. The pupil-shaping optic 11 also serves as an adjustment device for specifying different illumination settings with varying maximum object field illumination angles.The pupil-forming optics 11 image the light source at the intermediate focus 9 onto a pupil plane 12 of the illumination optics 5. The pupil-forming optics 11 includes an interference filter 13 and, downstream of this, an axicon module 14 with two axicon elements 15, 16. The axicon module 14 allows a maximum object field illumination angle for illuminating the object field 6a to be set within a specified illumination angle range.

[0042] A pupil radius 090 serves as a measure for the maximum object field illumination angle set via the pupil-shaping optics 11. For a specific pupil illumination of the pupil plane 12 or a subsequent pupil plane of the illumination optics 5, this radius specifies the area within which 90% of the illumination energy incident on that pupil plane is located. 090 is given in relative pupil coordinates. The value "090 = 1" indicates that the limit of a maximally illuminated pupil of the illumination system has been reached.

[0043] Downstream of the pupil plane 12 is an optical assembly 17, designed as an illumination-light mixing unit and shown schematically in Fig. 1, for which exemplary embodiments are explained below in connection with Figures 2ff. An entry plane of the illumination-light mixing unit 17 can coincide with the pupil plane 12.

[0044] In the area of ​​the lighting light mixing unit 17, a lighting light beam path is deflected by 90° by means of a folding mirror 18, so that the optical axis 2 no longer runs along the z-direction, but along the y-direction of the xyz coordinate system of Fig. 1. A 90° deflecting prism can also be used instead of the folding mirror 18.

[0045] In the embodiment according to Fig. 1, the lighting-light mixing unit 17 has a first optical rod assembly 17a in front of the folding mirror 18 and a second optical rod assembly 17b in the beam path after the folding mirror 18. Each of these rod assemblies 17a, 17b can be designed according to the type of optical assemblies described below with reference to Fig. 2ff.

[0046] At the exit point of the illumination light 4 from the illumination light mixing unit 17, there is an intermediate field plane 19 of the illumination optics 5. In this intermediate field plane 19 is an aperture 20 for defining a boundary of the object field 6a. The aperture 20 is also referred to as a REMA aperture (Reticle Masking System for stopping down the reticle 7).

[0047] The intermediate field plane 19 is imaged onto the object plane 6 by an imaging optic 21, also known as a REMA lens. The imaging optic 21 includes a 90° folding mirror 21a, so that the optical axis 2, which until then ran along the y-direction, now runs in the z-direction. A further pupil plane 22 lies between the field planes 19 and 6.

[0048] The object field 6a is projected onto an image field 24 in an image plane 25 by means of a projection optic 23. A wafer 26 is arranged in the image plane 25 in the area of ​​the image field 24. This wafer is supported by a holding device (not shown) which enables controlled scan displacement of the wafer 26 or stepwise displacement of the wafer 26.

[0049] Between the object plane 6 and the image plane 25 lies a pupil plane 27 of the projection optics 23. In this pupil plane 27, an aperture diaphragm can be arranged to define a pupil of the projection optics 23 at the edge.

[0050] Fig. 2 illustrates the optical assembly 17, which can be used, for example, instead of the rod assembly 17a and / or instead of the rod assembly 17b or, if the folding via the falling mirror 18 is omitted, instead of the entire lighting-light mixing unit 17.

[0051] An illumination light beam path through the optical assembly 17 according to Fig. 2 runs from left to right in the opposite direction to the z-direction in Fig. 2.

[0052] The optical assembly 17 has a primary optical rod 28 for guiding the illumination light 4, of which a single beam 4i is highlighted in Fig. 2, along the illumination light beam path from the light source 3 to a target field in the form of the object field 6a. Furthermore, the optical assembly 17 has a follower optical rod 29, which is arranged in the illumination light beam path between the primary rod 28 and the target field 6a.

[0053] The entry and exit surfaces of the primary rod 28 and the subsequent rod 29 each have a rectangular boundary. This boundary can, for example, be square or can have an x / y aspect ratio in the range between 1:5 and 5:1, for example in the range between 1:1.5 and 1.5:1.

[0054] Between the primary beam 28 and the follower beam 29, the optical assembly 17 has an intermediate image-generating optic 30 in the illumination light beam path. The intermediate image-generating optic 30 generates an intermediate image between the primary beam 28 and the follower beam 29 along an imaging dimension y transverse to the z-direction of the illumination light beam path. No such intermediate image generation occurs in the xz-imaging plane perpendicular to this dimension. The z-distances between the primary beam 28 and the intermediate image-generating optic 30 on the one hand, and between the intermediate image-generating optic 30 and the follower beam on the other, are exaggeratedly large in Fig. 2.

[0055] The intermediate image-generating optics 30 has a primary imaging component 31 in the form of a cylindrical lens, which is associated with the primary rod 28. Furthermore, the intermediate image-generating optics 30 has a secondary imaging component 32 in the form of another cylindrical lens, which is associated with the secondary rod 29. The cylindrical lenses 31 and 32 represent examples of a primary and secondary imaging component, respectively, being implemented as cylindrical optics.

[0056] The intermediate image generation optic 30 can be designed as a 2f optic.

[0057] The primary imaging component 31 can be integrally formed on the primary rod 28, particularly on its exit surface. Similarly, the secondary imaging component 32 can be integrally formed on the secondary rod 29, particularly on its entry surface. This can be achieved by machining the exit surface of the primary rod 28 or the entry surface of the secondary rod 29, so that the imaging components 31 and 32 can be integral parts of the rods 28 and 29. Alternatively, the imaging components 31 and 32 can also be blasted onto or bonded to the corresponding entry and exit surfaces of the rods 28 and 29, for example, by gluing. Mechanical clamping of the imaging components 31 and 32 to the respective entry and exit surfaces of the rods 28 and 29 is also possible.

[0058] Fig. 2 also illustrates the path of the single beam 4i through the optical assembly 17. This path is spatially represented in the perspective views of the two rods 28, 29 and is also shown in the respective top-down projections of the exit surfaces, which are arranged downstream of the rods 28, 29 in Fig. 2. In the projection onto the exit surface of the primary rod 28, the resulting direction of rotation of the single beam 4i is counterclockwise, and in the top-down projection onto the exit surface of the secondary rod 29, the direction of rotation of the single beam 4i is clockwise, i.e., opposite to the direction of rotation of the primary rod 28. Fig. 2 also shows a polarization vector 4p of the linearly polarized single beam 4i. Due to total internal reflections of the single beam 4i at the lateral surfaces of the rods 28, 29, the linear polarization state of the single beam 4i is influenced as follows:

[0059] Firstly, total internal reflection has a retarding effect, leading to a phase difference in s- and p-polarization and thus generally to an elliptical polarization state. This retarding effect is neglected in Fig. 2 and is the subject of Fig. 10 and claim 7.

[0060] On the other hand, due to reflections from all longitudinal sides of the rod, the output polarization is rotated relative to the input polarization by a so-called "geometric phase" or "spin redirection phase". This rotation of the polarization vector is illustrated in Fig. 3 using a single beam 4i: The polarization state shown with a dashed line is parallel to the input state, but tilted relative to the output state by a non-zero geometric phase. (Details 33 in Fig. 2).

[0061] The geometric phase of a single beam can be determined from its holomy in the k-sphere; for this, reference is made to specialist literature such as C. Cisowski et al. “Geometry phases of light: insights from fibre bundle theory”, Rev. Mod. Phys. 94, (2022) [2202.04356 (arxiv.org)]. According to the invention, the images of the beam paths within the two rods 28, 29 in the k-sphere are almost identical, but with inverse direction of rotation, thus exhibiting inverse geometric phases.

[0062] Fig. 3 illustrates the field homogenization by the two mixing rods in the (y,k_y) section of the phase space according to Rausch, Herkommer: “Phase space approach to the use of integrator rods and optical arrays in illumination systems”, Adv. Opt. Techn. Vol 1 (2012). k_y here denotes the pupil coordinate conjugate to the y-coordinate; in particular, it is proportional to the y-component of the beam direction. The depicted ellipses, or their intersection as a result of reflections on the longitudinal surfaces, illustrate here, as in the above reference, an exemplary distribution of a radiance (also called radiance) in the (y,k_y) section of the phase space at the four rod ends A, B, C, D: The radiance at the exit (D) of the secondary rod 29 results from the shear (B), point reflection (C), and second shear (D) of the elliptical radiance distribution at the beginning A of the primary rod 28, plus intersection analogous to Fig. B'.Because the shear forces of both rods 28, 29 add up independently of the intermediate image, the superimposed fields (number of elliptical fragments) also add up. The mixing rods thus continue to fulfill their actual field-homogenizing function independently of the intermediate image.

[0063] The intermediate image generation optics 30 are refractive.

[0064] Fig. 4 shows another embodiment of an optical assembly 34, which can be used instead of the optical assembly 17 according to Fig. 2. Components and functions corresponding to those already explained above with reference to Figures 1 to 3 bear the same reference numerals and are not discussed again in detail.

[0065] An intermediate image generation optic 35 is implemented in the optical assembly 34 as an array of two cylindrical optics 36, 37, each with cylindrical lenses 38. The cylindrical optics 36, 37 can be integrally formed with the rods 28, 29 of the optical assembly 34, as already explained above in connection with the imaging components 31, 32 of the optical assembly 17. The cylindrical optics 36, 37 can be configured as an ID array with cylindrical lenses 38 extending along the x-coordinate, each acting for a y-layer of the entire beam of illumination 4, or as a 2D array with cylindrical lenses 38 arranged in a grid pattern across the exit surface of the primary rod 28 and across the entrance surface of the secondary rod 29, each acting for a channel of the entire beam of illumination 4.

[0066] By means of the intermediate image generation optics 35, layer-wise or channel-wise intermediate imaging is carried out along the imaging dimension y in accordance with what was explained above in connection with the intermediate image generation optics 30 for an entire rod aperture.

[0067] The intermediate image generation optics 34 are refractive.

[0068] With reference to Figures 5 and 6, a further embodiment of an intermediate image generating optic 40 is described below, which can be used instead of the intermediate image generating optics 30 and 34 described above. Components and functions corresponding to those already explained above with reference to Figures 1 to 4 bear the same reference numerals and are not discussed again in detail.

[0069] Fig. 5 shows a yz meridional section through the intermediate image-generating optics 40. Fig. 6 shows an xz meridional section of the intermediate image-generating optics 40. The intermediate image-generating optics 40 has a primary imaging component 41, which is associated with the primary rod 28. The primary imaging component 41 can be a cylindrical lens comparable to the cylindrical lens 31, but with different finite focal lengths in the yz imaging plane and the xz imaging plane. Alternatively, the primary imaging component can be a cylindrical lens, similar to the cylindrical lens 38 shown in Fig. 4, which carries a partial channel of the total illumination light 4.

[0070] Furthermore, the intermediate image-generating optics 40 has a follower imaging component 42, which is assigned to the follower rod 29 and whose focal lengths correspond, on the one hand in the yz-imaging plane and, on the other hand, in the xz-imaging plane, to those of the primary imaging component 41. Depending on the design of the intermediate image-generating optics, the follower imaging component 42 is configured to guide either the entire beam of the illumination light 4 or a partial channel, as described above in connection with the primary imaging component.

[0071] Between the primary imaging component 41 and the subsequent imaging component 42, the intermediate image generation optics 40 has two further imaging components 43, 44, which are lenses, again with different focal lengths in the yz imaging plane on the one hand and in the xz imaging plane on the other.

[0072] In the yz imaging plane, the intermediate image generation optics 40 are designed as a 2f imaging system. The distance between the primary imaging component 41 and the secondary imaging component 42 corresponds to twice the focal lengths of these two imaging components 41, 42 in the yz imaging plane.

[0073] In the xz-imaging plane, the intermediate image-generating optics 40 are designed as a 4f imaging system. The distance between the primary imaging component 41 and the adjacent imaging component 43 is twice the focal lengths of these components in the xz-imaging plane. Similarly, the distance between the further imaging component 44 and the adjacent subsequent imaging component 42 is twice the focal lengths of these two imaging components 44 and 42 in the xz-imaging plane.

[0074] Accordingly, the intermediate image generation optics 40 produces an image in the yz image plane with a scale of -1 and in the xz image plane with a scale of +1. The intermediate image generation optics 40 thus also generates an image inversion along exactly one image dimension y perpendicular to the ray path of the illumination light 4 running along the z-coordinate.

[0075] The intermediate image generation optic 40 is refractive.

[0076] Fig. 7 shows another embodiment of an intermediate image generating optic 45, which can be used in place of the intermediate image generating optics described above in the optical assemblies 17 or 34. Components and functions corresponding to those already explained above with reference to Figures 1 to 6 bear the same reference numerals and are not discussed again in detail. Between the primary bar 28 and the secondary bar 29, the intermediate image generating optic 45 is designed as a pair of cylindrical mirrors 46, 47, the y-spacing of which corresponds to twice the focal length of these cylindrical mirrors 46, 47. This again results in an intermediate image in the yz-plane and thus an image inversion along the imaging dimension y perpendicular to the illumination light beam path.In addition, the intermediate image generation optics 45 leads to a 180° folding of the illumination light beam path, which, for example, enters the primary rod 28 in a positive z-direction and exits the secondary rod 29 in a negative z-direction.

[0077] The intermediate image generation optics 45 are designed to be reflective.

[0078] No such intermediate image generation occurs in the xz-image plane perpendicular to this.

[0079] With reference to Fig. 8, a further embodiment of an intermediate image generation optic 48, in this case implemented diffractively, is explained below. Components and functions corresponding to those already explained above with reference to Figures 1 to 7 bear the same reference numbers and are not discussed again in detail.

[0080] The intermediate image generation optics 48 comprise a primary DOE 49 (diffractive optical element) and a secondary DOE 50. The primary DOE is located on the exit surface of the primary rod 28, and the secondary DOE is located on the entrance surface of the secondary rod 29. The two DOEs 49 and 50 are spaced z apart by a distance equal to twice their focal length in the yz-imaging plane. In this yz-imaging plane, an intermediate image is generated along the y-imaging dimension, perpendicular to the illumination beam path. No such intermediate image generation occurs in the xz-imaging plane, which is perpendicular to the yz-imaging plane.

[0081] With reference to Fig. 9, a further embodiment of an intermediate image generating optic 51 is described below, which can be used in place of the intermediate image generating optics described above in the optical assemblies 17 and 34. Components and functions corresponding to those already explained above with reference to Figures 1 to 8 bear the same reference numerals and are not discussed again in detail.

[0082] The intermediate image generation optics 51 have a primary Grin (gradient index) lens 52 and a secondary Grin lens 53. The primary Grin lens 52 is associated with the primary optical bar 28, and the secondary Grin lens 53 is associated with the secondary bar 29, as explained above, for example, in connection with the imaging components 31 and 32 of the embodiment according to Fig. 2 and 36 and 37 of the embodiment according to Fig. 4. The z-distance between the two Grin lenses 52, 53, on the one hand, and the focal lengths of these Grin lenses 52, 53 in the yz-imaging plane, on the other hand, are coordinated such that an intermediate image is again formed in the yz-imaging plane centrally between the two Grin lenses 52, 53. In the y-dimensional transformation dimension, this results in an image inversion, whereas in the x-dimensional transformation dimension, no image inversion occurs.

[0083] With reference to Fig. 10, a further embodiment of an optical assembly 54 is described below, which can be used instead of the optical assemblies 17 and 34 explained above. Components and functions corresponding to those already explained above with reference to Figures 1 to 9 and in particular with reference to Fig. 2 bear the same reference numerals and are not discussed again in detail.

[0084] The primary optical rod 28 of the optical assembly 54 has a rectangular cross-section with a y / x aspect ratio of approximately 1.5:1. In comparison, the secondary optical rod 29 of the optical assembly 54 has a rectangular cross-section rotated by 90° with an x / y aspect ratio of 1.5:1.

[0085] An intermediate image generating optic, for example of the type of intermediate image generating optic 30 according to Fig. 2, is arranged tilted about an optical axis of the illumination light beam path such that an imaging dimension img is arranged at an angle in the range between 0° and 90° to the coordinates x and y spanning the rectangular boundary of the cross-sections of the rods 28, 29. An angle between the imaging dimension img and the y-axis can, for example, be in the range between 1° and 89°, in the range between 5° and 85°, in the range between 25° and 65°, and can, for example, be at 30°, at 45°, or at 60°.

[0086] Regarding the compensation of a geometric phase of the polarization that accumulates due to reflections at the respective rods 28, 29, the effect of the tilted intermediate image-generating optics 30 in the optical assembly 54 corresponds to that explained above in connection with Fig. 2 for the untilted intermediate image-generating optics. Additionally, the tilted intermediate image-generating optics 30, as shown in Fig. 10, compensates for a retardation, i.e., a phase splitting between s- and p-intrinsic polarizations during the total internal reflection of the individual beams 4i of the illumination light 4 at one of the four cladding walls of the rods 28, 29. This retardation generally leads to a change in the ellipticity of the input polarizations of the illumination light 4. The respective s- or p-p-Eigenpolarization is defined in relation to the respective surface area of ​​the rod 28, 29, at which total reflection takes place.

[0087] For the phase splitting ret, the following proportionality relationship holds in the first order of |k|: ret oc N x \k x - N y \k y \

[0088] (1)

[0089] N x and N y The numbers of reflections of the respective single beam 4i at the xz and yz cladding walls of the respective rod are 28, 29. k x and k y describe the pupil coordinate, i.e., the x and y components of the direction vector of the single beam 4i in the x and y coordinates.

[0090] Figures 11 and 12 illustrate the retardation compensation achieved in the optical assembly 54.

[0091] Fig. 11 shows a view of the entrance surface of the primary optical rod 28, and Fig. 12 shows a top view of the entrance surface of the secondary optical rod 29. In grayscale, the retardation amplitude |ret| is of first order k for exactly one reflection according to the formula (1) above. The white double arrows in Figures 11 and 12 correspond to the s-polarization with respect to the respective lateral surface.

[0092] A closed reflection path with N is illustrated in black. x = 3, N y = 1 in the primary rod 28; the retardation effect according to formula (1) is given by the gray level of the connecting line between two pupil points emerging from each other by reflection multiplied by the number of its passes (number of reflections) and the sign 1 for k x or (-1) for k y .

[0093] In the follower rod 29, the retardation is therefore inverse to that in the primary rod 28, because formula (1) for the follower rod 29 is derived from that for the primary rod 28 by exchanging x and y in the beam data k x <-»k y , Nx^Ny.

[0094] This means that the intermediate image, which is generated by the tilted intermediate image generation optics 30 of the optical assembly 54, also compensates for the retardation. This method is the preferred solution for all rods whose input fields have x- and y-mirror symmetry, including not only rectangular but also hexagonal or circular rods.

[0095] As an alternative to a rectangular rod cross-section, rods with a hexagonal or circular cross-section can also be used in the optical assemblies described above. The only requirement for the cross-sectional shape is that it exhibits x-mirror symmetry and y-mirror symmetry. To suppress retardation, a retardation-suppressing coating can also be applied to the four lateral surfaces of the primary rod 28 and / or the follower rod 29.

[0096] Using the projection exposure system 1, at least a portion of the reticulum 7 is imaged onto an area of ​​a photosensitive layer on the wafer 26 for the lithographic fabrication of a micro- or nanostructured component. Depending on whether the projection exposure system 1 is configured as a scanner or a stepper, the reticulum 7 and the wafer 26 are moved continuously in the y-direction in scanner mode or stepwise in stepper mode, synchronized over time.

Claims

Patent claims 1. Optical assembly (17; 34; 54) with a primary optical rod (28) for guiding and mixing illumination light (4) along an illumination light beam path from a light source (3) to a target field (6a), with a follower optical rod (29) for guiding and mixing the illumination light (4), which is arranged in the illumination light beam path between the primary rod (28) and the target field (6a), wherein an intermediate image generating optic (30; 35; 40; 45; 48; 51) is arranged between the primary rod (28) and the follower rod (29), which generates an intermediate image along exactly one imaging dimension (y; img) transverse to the illumination light beam path.

2. Optical assembly according to claim 1, characterized in that the intermediate image generating optics (30; 35; 40; 45; 48; 51) has at least one primary imaging component (31; 36; 41; 46; 49; 52) which is assigned to the primary rod (28) and has at least one follower imaging component (32; 37; 42; 47; 50; 53) which is assigned to the follower rod (29).

3. Optical assembly according to claim 2, characterized in that the primary imaging component (31; 36; 41; 49; 52) is integrally formed on the primary rod (28) and / or that the secondary imaging component (32; 37; 42; 47; 50; 53) is integrally formed on the secondary rod (29).

4. Optical assembly according to claim 2 or 3, characterized in that the primary imaging component (31; 36; 41; 46; 49; 52) and / or the secondary imaging component (32; 37; 42; 47; 50; 53) is designed as exactly one cylindrical optic.

5. Optical assembly according to claim 2 or 3, characterized in that the primary imaging component (36) and / or the secondary imaging component (37) is designed as an array of cylindrical optics (38).

6. Optical assembly according to one of claims 1 to 5, characterized in that the primary rod (28) and the secondary rod (29) have entry and exit surfaces for the illumination light (4) each with a rectangular edge contour.

7. Optical assembly according to claim 6, characterized in that the imaging dimension (y; img) of the intermediate image generating optics (30; 35; 40; 45; 48; 51) runs at an angle other than 0° and 90° to the coordinates (x, y) that define the boundary contour of the entry and exit surfaces of the primary rod (28) and the follower rod (29).

8. Optical assembly according to one of claims 1 to 7, characterized in that the lateral surfaces of the primary rod (28) and / or the follower rod (29) have a coating which is designed to suppress a retardation effect of total reflection on the lateral surfaces.

9. Optical assembly according to claim 8, characterized in that the coating has an effective refractive index gradient for different polarization states of the illumination light (4).

10. Illumination optics (5) with an optical assembly (17; 34; 54) according to one of claims 1 to 9 for guiding the illumination light (4) from the light source (3) to the target field (6a) in the form of an object field in which an object (7) to be imaged can be arranged.

11. Optical system comprising an illumination optic according to claim 10 and an imaging optic (21) for imaging the object field (6a) into an image field (24) in which a section of a substrate (26) can be arranged.

12. Projection exposure system with an optical system according to claim 11 and with a light source (3) for the illumination light (4).

13. Method for manufacturing structured components comprising the following steps: Providing a wafer (26) on which at least a layer of a photosensitive material is applied, providing a reticulum (7) which has structures to be imaged, Providing a projection exposure system (1) according to claim 12, Projecting at least part of the reticulum (7) onto an area of ​​the wafer layer (26) using the projection exposure system (1).

14. Structured component manufactured according to a method according to claim 13.

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