Imaging EUV optical unit for imaging the object field into the image field.

Abstract

We provide an imaging EUV optical unit for imaging the object field into the image field. [Solution] The imaging EUV optical unit (10) plays the role of imaging the object field (5) into the image field (11). The imaging optical unit (10) has a plurality of mirrors (M1~M5) for guiding EUV imaging light (16) with a wavelength shorter than 30 nm along the imaging beam path. The imaging EUV optical unit (10) has an image-side numerical aperture of at least 0.3. The total transmittance of the plurality of mirrors (M1~M5) is greater than 10%. The total mirror surface, which corresponds to the sum of all used mirror surfaces of the plurality of mirrors (M1~M5), is 1.5 m 2 It is less than [a certain value]. This results in an imaging EUV optical unit with improved usability for EUV projection exposure systems.

Description

[Technical Field]

[0001] This patent application claims priority to German patent application DE102023203223.6, the contents of which are incorporated herein by reference.

[0002] The present invention relates to an imaging EUV optical unit for imaging an object field into an image field. Furthermore, the present invention relates to an optical system having such an imaging optical unit, a projection exposure apparatus having such an optical system, a method for manufacturing micro or nanostructure components using such a projection exposure apparatus, and micro or nanostructure components manufactured by the method. [Background technology]

[0003] The type of projection optical unit mentioned at the beginning is, Known from WO2018 / 010960A1, DE102015221984A1, DE102015209827A1, DE102012212753A1, U.S. Patent Application Publication No. 2010 / 0149509, and U.S. Patent No. 4,964,706. [Overview of the Initiative]

[0004] The object of the present invention is to develop the imaging EUV optical unit of the type described at the beginning so that its usability in an EUV projection exposure apparatus is improved.

[0005] According to the present invention, this objective is achieved by an imaging EUV optical unit having the features specified in claim 1.

[0006] According to the present invention, the total mirror surface of an imaging EUV optical unit can be conveniently reduced, specifically to 1.5 m, while maintaining other necessary boundary conditions imposed on the imaging EUV optical unit, particularly in projection exposure apparatuses for lithography. 2It has been recognized that it is possible to keep it smaller, which reduces the cost of manufacturing the mirror. Furthermore, the required installation space can be reduced. The image-side numerical aperture may be greater than 0.3, for example, it may be 0.33. The image-side numerical aperture is typically 0.6 or less. The total transmittance of the imaging EUV optical unit may be greater than 10.5%, may be greater than 11%, may be greater than 11.5%, may be greater than 12%, may be greater than 12.5%, may be greater than 13%, and may also be greater than 13.3%. Due to the number of mirrors and the individual EUV transmittance of the mirrors that typically guide the imaging light, which is 80% or less, the total transmittance is typically less than 15%.

[0007] 1.5m 2 The total mirror surface of all the mirrors in the imaging EUV optical unit that is less than is 1.25m 2 or less, 1.0m 2 or less, 0.9m 2 or less, and 0.8m 2 or less and may be. The total mirror surface may be less than 0.8m 2 and may be less than 0.75m 2 and may be less than 0.7m 2 and may be less than 0.65m 2 and may be less than 0.6m 2 and may be less than 0.55m 2 and may be less than 0.5m 2 and may be less than, and also 0.48m 2 and may be even less than. This total mirror surface is typically greater than 0.4m 2 The image field may be a ring region. The imaging EUV optical unit may be provided with an entrance pupil that can be reached as a whole to specify the distribution of the illumination angle of the object field. The entrance pupil of the imaging EUV optical unit can be located upstream of the object field in the imaging beam path.

[0008] Considering the polished overrun edge in the area corresponding to the total mirror surface according to claim 2, an EUV optical unit with particular advantages in terms of manufacturing and use can be obtained. The mirror surface used may protrude beyond the reflective mirror surface by more than 10 mm, and may be at least 15 mm or at least 20 mm.

[0009] The field-of-view extents according to claims 3 and 4 have proven particularly favorable. The scanning range of the field of view may be 2.5 mm along the scanning region extension direction, i.e., along the scanning direction of the projection exposure apparatus, which may use an imaging EUV optical unit inside and is designed as a scanner in that case. On the image plane, the field of view may have a maximum extent of 30 mm, 35 mm, 40 mm, 45 mm, and 50 mm. The maximum extent may even be on the order of 52 mm.

[0010] The wavefront aberration according to claim 5 has been found to be particularly suitable for use in an imaging EUV optical unit with a projection exposure apparatus for lithography. The RMS wavefront aberration may be less than 25 mλ, less than 20 mλ, less than 15 mλ, less than 10 mλ, and less than 8 mλ. The RMS wavefront aberration is typically greater than 3 mλ.

[0011] The maximum total polarization rotation according to claim 6 also enables imaging of linearly polarized imaging light by an imaging EUV optical unit without interference required for imaging, between different orders of diffraction guided in the imaging beam path, which causes an undesirable loss of contrast. The total polarization rotation of the imaging EUV optical unit typically varies for each field point and also typically varies within the pupil of the imaging EUV optical unit. To determine the maximum total polarization rotation, the respective polarization rotations are determined over all field points and all pupil positions. The maximum total polarization rotation can be less than 10°, can be less than 8°, can be less than 7°, can be less than 6°, can be less than 5°, and can also be less than 4.5°. Even smaller maximum total polarization rotations are possible. The maximum total polarization rotation is typically greater than 0.1°. The total polarization rotation represents the cumulative polarization rotation effect of all the mirrors within the imaging EUV optical unit.

[0012] In an embodiment according to claim 7, the imaging EUV optical unit does not have an intermediate image in at least one cross-section, i.e., for example, in the sagittal plane. Thus, there is choristikonal-type imaging in the sense of U.S. Patent No. 10,656,400. For example, in that case, there is image inversion in the sagittal plane perpendicular to the meridian plane. This cross-section without an intermediate image can be the meridian plane and / or the sagittal plane. In particular, an intermediate image in the form of the morphology of the intermediate field region, for example, the form of a caustic, can exist in the other cross-section.

[0013] The number of mirrors according to claims 8 to 10 has been found to be particularly suitable for this optical design.

[0014] The imaging EUV optical unit can be provided with an accessible entrance pupil at a distance in the range of 1 m to 4 m in front of the object field, upstream of the object field in the beam path of the imaging light. In any case, the orientation of such an entrance pupil can be substantially the same in the meridian plane and the sagittal plane perpendicular thereto.

[0015] The imaging EUV optical unit may have a pupil plane between the object field and the image field in the beam path. The pupil plane or aperture plane may be located on one of the mirrors of the imaging EUV optical unit, particularly the NI mirror.

[0016] The advantages of the optical system according to claim 11, the projection exposure apparatus according to claim 12, the manufacturing method according to claim 13, and the microstructure or nanostructure component according to claim 14 correspond to the advantages already described above with respect to the projection optical unit according to the present invention.

[0017] The EUV light source of the projection exposure apparatus may be designed to produce usable wavelengths of 13.5 nm or less, less than 13.5 nm, less than 10 nm, less than 8 nm, less than 7 nm, for example, 6.7 nm or 6.9 nm. Usable wavelengths of less than 6.7 nm, especially on the order of 6 nm, are also possible.

[0018] In more detail, this projection lithography apparatus can be used to manufacture semiconductor components, such as memory chips.

[0019] Below, at least one exemplary embodiment of the present invention will be described with reference to the drawings. [Brief explanation of the drawing]

[0020] [Figure 1] This diagram schematically shows a meridian cross-section of a projection exposure apparatus for EUV projection lithography. [Figure 2] Figure 1 shows an embodiment of the imaging optical unit used as a projection lens in the projection exposure apparatus, with each case represented as a meridian cross-sectional view, illustrating the imaging beam paths of the principal rays, upper coma rays, and lower coma rays of three selected field of view points. [Figure 3] Figure 1 shows an embodiment of the imaging optical unit used as a projection lens in the projection exposure apparatus, with each case represented as a meridian cross-sectional view, illustrating the imaging beam paths of the principal rays, upper coma rays, and lower coma rays of three selected field of view points. [Figure 4]Figure 1 shows an embodiment of the imaging optical unit used as a projection lens in the projection exposure apparatus, with each case represented as a meridian cross-sectional view, illustrating the imaging beam paths of the principal rays, upper coma rays, and lower coma rays of three selected field of view points. [Figure 5] Figure 1 shows an embodiment of the imaging optical unit used as a projection lens in the projection exposure apparatus, with each case represented as a meridian cross-sectional view, illustrating the imaging beam paths of the principal rays, upper coma rays, and lower coma rays of three selected field of view points. [Figure 6] Figure 1 shows an embodiment of the imaging optical unit used as a projection lens in the projection exposure apparatus, with each case represented as a meridian cross-sectional view, illustrating the imaging beam paths of the principal rays, upper coma rays, and lower coma rays of three selected field of view points. [Figure 7] Figure 1 shows an embodiment of the imaging optical unit used as a projection lens in the projection exposure apparatus, with each case represented as a meridian cross-sectional view, illustrating the imaging beam paths of the principal rays, upper coma rays, and lower coma rays of three selected field of view points. [Figure 8] Figure 1 shows an embodiment of the imaging optical unit used as a projection lens in the projection exposure apparatus, with each case represented as a meridian cross-sectional view, illustrating the imaging beam paths of the principal rays, upper coma rays, and lower coma rays of three selected field of view points. [Figure 9] Figure 1 shows an embodiment of the imaging optical unit used as a projection lens in the projection exposure apparatus, with each case represented as a meridian cross-sectional view, illustrating the imaging beam paths of the principal rays, upper coma rays, and lower coma rays of three selected field of view points. [Figure 10] Figure 1 shows an embodiment of the imaging optical unit used as a projection lens in the projection exposure apparatus, with each case represented as a meridian cross-sectional view, illustrating the imaging beam paths of the principal rays, upper coma rays, and lower coma rays of three selected field of view points. [Modes for carrying out the invention]

[0021] In the following description, the basic components of the microlithograph projection exposure apparatus 1 are first explained as an example with reference to Figure 1. The description of the basic structure of the projection exposure apparatus 1 and its components should not be interpreted as restrictive.

[0022] One embodiment of the illumination system 2 of the projection exposure apparatus 1 includes, in addition to a light source or radiation source 3, an illumination optical unit 4 for illuminating the object field 5 within the object surface 6. In an alternative embodiment, the light source 3 may be provided as a module separate from the rest of the illumination system. In that case, the illumination system does not include the light source 3.

[0023] A reticle 7 positioned in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 is displaceable, particularly in the scanning direction, by a reticle displacement drive mechanism 9.

[0024] For explanatory purposes, the Cartesian xyz coordinate system is shown in Figure 1. The x-direction extends perpendicular to the plane of the drawing and toward the back of the drawing. The y-direction extends horizontally, and the z-direction extends vertically. In Figure 1, the scanning direction extends in the y-direction. The z-direction extends perpendicular to the object plane 6.

[0025] The projection exposure apparatus 1 includes a projection optical unit or an imaging optical unit 10. The projection optical unit 10 plays the role of imaging the object field 5 onto the image field 11 of the image plane 12. The image plane 12 extends parallel to the object field 6. Alternatively, an angle other than 0° between the object field 6 and the image plane 12 is also possible.

[0026] The structure on the reticle 7 is imaged onto the photosensitive layer of the wafer 13, which is positioned in the image field 11 region of the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable, particularly in the y direction, by a wafer displacement drive mechanism 15. This y-displacement direction is also referred to as the scanning direction when the projection exposure apparatus 1 is implemented as a scanner. Firstly, the displacement of the reticle 7 by the reticle displacement drive mechanism 9 and secondly, the displacement of the wafer 13 by the wafer displacement drive mechanism 15 can be performed in synchronization with each other.

[0027] Radiation source 3 is an EUV radiation source. Radiation source 3 emits EUV radiation 16 in particular, which will hereafter be referred to as the working radiation, illumination radiation, imaging radiation, illumination light, or imaging light. In detail, the working radiation has a wavelength in the range of 5 nm to 30 nm. Radiation source 3 may be a plasma source, such as an LPP (laser-generated plasma) source or a GDPP (gas discharge-generated plasma) source. It may also be a synchrotron-based radiation source. Radiation source 3 may be a free electron laser (FEL).

[0028] Illumination radiation 16 emitted from radiation source 3 is focused by a focuser 17. The focuser 17 may be a focuser having one or more ellipsoidal and / or hyperboloid reflective surfaces. Illumination radiation 16 may be incident on at least one reflective surface of the focuser 17 by grazing incidence (GI), i.e., at an incidence angle greater than 45°, or by normal incidence (NI), i.e., at an incidence angle less than 45°. The focuser 17 may be structured and / or coated in order to optimize its reflectivity to the radiation used, on the one hand, and to suppress stray light, on the other hand.

[0029] The illumination radiation 16 propagates downstream of the concentrator 17, through the intermediate focal point of the intermediate focal plane 18. The intermediate focal plane 18 can correspond to the boundary between the radiation source module, which includes the radiation source 3 and the concentrator 17, and the illumination optical unit 4.

[0030] The illumination optical unit 4 includes a first facet mirror 19. When the first facet mirror 19 is positioned on a surface of the illumination optical unit 4 that is optically conjugate to the object surface 6, this facet mirror is also called a field-of-view facet mirror. The first facet mirror 19 comprises a number of individual first facets 20, which are hereinafter also referred to as field-of-view facets. Only a few of these facets are illustrated illustratively in Figure 1.

[0031] The first facet 20 may be embodied as a macroscopic facet, particularly as a rectangular facet, or as a facet having an arched edge contour or a partially circular edge contour. The first facet 20 may be embodied as a planar facet, or alternatively as a facet having a convex or concave curvature.

[0032] For example, as known from DE102008009600A1, the first facet 20 itself may, in each case, consist of a number of individual mirrors, in particular a number of micromirrors. The first facet mirror 19 may be formed in particular as a micro-electromechanical system (MEMS system). For further details, see DE102008009600A1.

[0033] The deflection mirror US is located between the intermediate focal point of the intermediate focal plane 18 in the beam path of the illumination optical unit 4 and the first facet mirror 19. This deflection mirror US may be implemented as a planar mirror, but may also have a beam shaping effect.

[0034] Within the beam path of the illumination optical unit 4, the second facet mirror 21 is positioned downstream of the first facet mirror 19. When the second facet mirror 21 is positioned on the pupil plane of the illumination optical unit 4, it is also called a pupil facet mirror. The second facet mirror 21 may also be positioned at a distance from the pupil plane of the illumination optical unit 4. In that case, the combination of the first facet mirror 19 and the second facet mirror 21 is also called a specular reflector. Specular reflectors are known from U.S. Patent Application Publication No. 2006 / 0132747, EP1614008B1, and U.S. Patent No. 6,573,978.

[0035] The second faceted mirror 21 comprises multiple second facets 22. In the case of a pupil faceted mirror, the second facets 22 are also called pupil facets.

[0036] The second facet 22 may also be a macroscopic facet, which may have, for example, a circular, rectangular, or hexagonal boundary, or alternatively, a facet composed of micromirrors. In this regard, DE102008009600A1 is similarly referenced.

[0037] The second facet 22 may have a planar reflective surface, or alternatively, a curved reflective surface that is convex or concave.

[0038] As a result, the illumination optical unit 4 forms a dual-faceted system. This basic principle is also known as a fly's eye integrator.

[0039] In some cases, it may be advantageous not to position the second facet mirror 21 precisely on a plane that is optically conjugate to the pupil plane of the projection optical unit 10. More specifically, the pupil facet mirror 22 may be positioned at an angle to the pupil plane of the projection optical unit 10, as described, for example, in DE102017220586A1.

[0040] Each first facet 20 is imaged onto the object field 5 using a second facet mirror 21, and optionally using an imaging optical assembly in the form of a transmission optical unit, which is not shown in Figure 1.

[0041] The transmission optics unit may have exactly one mirror, or alternatively, two or more mirrors, which are arranged in a row within the beam path of the illumination optics unit 4. The transmission optics unit may, in particular, comprise one or two direct incidence mirrors (NI mirrors) and / or one or two oblique incidence mirrors (GI mirrors). In the embodiment shown in Figure 1, the illumination optics unit 4 has exactly three mirrors, namely, downstream of the concentrator 17, a deflection mirror US, a first faceted mirror 19, and a second faceted mirror 21.

[0042] The second facet mirror 21 is either the last beam-shaping mirror or the actual last mirror for the illumination radiation 16 in the beam path upstream of the object field 5, to the extent that no further transmission optics units downstream of the second facet mirror 21 are required. An example of an illumination optics unit 4 without a transmission optics unit is disclosed in Figure 2 of WO2019 / 096654A1.

[0043] The imaging of the first facet 20 onto the object surface 6 using the second facet 22, or using the second facet 22 and the transmission optics unit, is mostly only an approximate image.

[0044] The projection optical unit 10 is equipped with multiple mirrors, namely five mirrors M1 to M5 (see Figure 2), which are numbered sequentially according to their order within the beam path of the projection exposure apparatus 1.

[0045] In the example shown in Figure 2, the projection optics unit 10 comprises five mirrors M1 to M5. Alternative configurations having four, six, or any other number of mirrors Mi are equally possible, as will become apparent from the description of further exemplary embodiments below.

[0046] The projection optics unit 10 is a non-obscured optics unit. None of the mirrors M1 to M5 contain a through aperture for the illumination radiation 16.

[0047] The projection optical unit 10 has an image-side numerical aperture of 0.33. Depending on the embodiment of the projection optical unit 10, the image-side numerical aperture may be in the range of, for example, 0.25 to 0.4. Depending on the embodiment, the image-side numerical aperture of the projection optical unit 10 may also be a different value.

[0048] Mirror M i The reflective surface is realized as a free-form surface without a rotational symmetry axis. Alternatively, the reflective surface of mirror Mi may be designed as an aspherical surface having exactly one rotational symmetry axis of the reflective surface shape. Similar to the mirrors of illumination optical unit 4, mirror Mi may have a high-reflectivity coating for illumination radiation 16. These coatings may be designed as multilayer coatings having, for example, alternating layers of molybdenum and silicon. Ruthenium coatings are also possible, particularly for grazing incidence mirrors (GI mirrors).

[0049] The projection optics unit 10 results in a size reduction of the image with a ratio of 4:1 (β = 4.00). The imaging scale β is positive, and therefore, the projection optics unit 10 does not cause image inversion within the imaging range. Alternatively, the projection optics unit 10 could be designed to cause image inversion.

[0050] In the following, the sign of the imaging scale β is defined as follows: when the imaging scale between object field 5 and image field 11 is negative, there are no intermediate images of the fire surface morphology, whereas when the imaging scale is positive, intermediate images that may be of the fire surface morphology actually exist.

[0051] In yet another alternative design of the projection optics unit 10, the latter can result in image inversion, for example, in the x-direction, i.e., perpendicular to the scanning direction y. Thus, the imaging scale βx in the x-direction is -4.00 in that case. In that case, this embodiment of the projection optics unit results in a 4:1 size reduction in the scanning direction y, but without image inversion (β y (=+4.00).

[0052] In further embodiments, the projection optics unit 10 may have an anamorphic design. In that case, different imaging scales β are used in the x and y directions. x , β y The projection optical unit 10 has two imaging scales βx and βy, preferably (βx, βy) = (+ / -4, + / -8).

[0053] Other imaging scales are also possible. Imaging scales with the same sign in the x and y directions are also possible.

[0054] The image field 11 has an x-direction extent of 26 mm and a y-direction extent of 2.5 mm.

[0055] The image field may have a partially ring-shaped embodiment.

[0056] Alternatively, the image field may also have a rectangular embodiment.

[0057] In each case, one of the pupil facets 22 is assigned to exactly one of the field of view facets 20 in order to form each illumination channel that illuminates the object field 5. More specifically, this can produce illumination according to Köhler's principle. The far field of view is decomposed into multiple object fields 5 using the field of view facets 20. The field of view facets 20 generate multiple intermediate focal images in the pupil facets 22 each assigned to it.

[0058] Due to the assigned pupil facets 22, the field of view facets 20 are imaged onto the reticle 7 in each case so as to superimpose with one another for the purpose of illuminating the object field 5. The illumination of the object field 5 is particularly uniform as possible, preferably with a uniformity error of less than 2%. Field of view uniformity can be achieved by superimposing different illumination channels.

[0059] The illumination of the entrance pupil of the projection optical unit 10 can be geometrically defined by the arrangement of the pupil facets. The intensity distribution of the entrance pupil of the projection optical unit 10 can be set by selecting the illumination channels, particularly the subset of pupil facets that guide the light. This intensity distribution is also referred to as the illumination setting or illumination pupil filling.

[0060] The uniformity of the pupil, which is illuminated as defined, across multiple compartments of the illumination pupil of the illumination optical unit 4, can be achieved by redistributing the illumination channels.

[0061] Further aspects and details of the illumination of the object field 5, particularly the entrance pupil of the projection optical unit 10, are described below.

[0062] The projection optical unit 10 may have a concentric entrance pupil, which may be reachable.

[0063] In the x-direction, the projection optics unit 10 is approximately telecentric on the object side. In the x-direction, the entrance pupil is at a distance greater than 7 m from the object plane 6. In the y-direction, the entrance pupil EP is located approximately 750 mm upstream of the object field 5 in the beam path.

[0064] In one modification, the projection optics unit has an entrance pupil EP (see Figure 1), which is located in the range of 1500 mm to 2000 mm upstream of the object field 5 in the beam path in both the x and y directions, and in particular in the range of 1800 mm to 2200 mm. The arrangement plane of this entrance pupil is shown in EP in Figure 1. Thus, if the pupil facet mirror 21 is located approximately 2 m upstream of the object field 5 in the beam path of the illumination light or imaging light 16, the pupil facet mirror 21 satisfies the positional condition of "arrangement within the region of the entrance pupil of the projection optics unit".

[0065] If the entrance pupil is inaccessible, the mounting surface of the pupil facet mirror 21 can be imaged onto the entrance pupil using other components of the illumination optical unit 4.

[0066] The entrance pupil of the projection optical unit 10 cannot typically be precisely illuminated using the pupil facet mirror 21. When the projection optical unit 10 images the center of the pupil facet mirror 21 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, it is possible to find an area where the distance between the paired aperture rays is minimized. This area corresponds to the entrance pupil or its conjugate area in real space. More specifically, this area has a finite curvature.

[0067] The projection optics unit 10 may have entrance pupils with different orientations for the tangential beam path and the sagittal beam path. In this case, the imaging element, particularly the optical component of the transmission optics unit, must be provided between the second facet mirror 21 and the reticle 7. This optical element can be used to take into account the different orientations of the entrance pupil in the tangential and sagittal directions.

[0068] In the arrangement of the components of the illumination optical unit 4 shown in Figure 1, the pupil facet mirror 21 is positioned at an angle with respect to the object surface 5. The second facet mirror 21 is further positioned at an angle with respect to the arrangement plane defined by the first facet mirror 19.

[0069] Further details regarding the projection optical unit 10 are described later in this specification based on Figure 2.

[0070] The projection optics unit 10 has four NI mirrors (direct incidence mirrors), namely the first mirror M1 and three last mirrors M3, M4, and M5 in the imaging beam path of the projection optics unit 10. The imaging light 16 is irradiated onto these NI mirrors M1, M3, M4, and M5 at an incidence angle of less than 45°. The maximum incidence angle of the imaging light 16 incident on each NI mirror may be less than 40°, less than 35°, less than 30°, less than 25°, less than 20°, less than 15°, and less than 10°.

[0071] The last remaining mirror M2 of the projection optics unit 10 is a GI mirror (gray incidence mirror). This mirror M2 has an incidence angle of illumination light 16 to the mirror that is greater than 45° in each case. The minimum incidence angle incident on each GI mirror may be greater than 50°, greater than 55°, greater than 60°, greater than 65°, greater than 70°, greater than 75°, and greater than 80°.

[0072] Depending on the embodiment of the projection optical unit 10, there may be three or more GI mirrors.

[0073] Information regarding reflection in GI mirrors (oblique incidence mirrors) can be found in WO2012 / 126867A. Further information regarding the reflectivity of NI mirrors (direct incidence mirrors) can be found in DE10155711A.

[0074] None of the mirrors M1 to M5 have through apertures, and in each case, the mirrors are used in a reflective manner within a continuous, gapless region.

[0075] Figure 2 shows the calculated reflective surfaces of mirrors M1 to M5. The reflective surfaces of mirrors M1 to M5 are supported by the mirror body (not shown) in a known manner. The actual reflective surfaces of mirrors M1 to M5 include the reflective surface actually used to reflect the imaging light 16 and a polished overrun edge PR (see inset in Figure 2) having an inner edging RS and an outer edging RS. Thus, the polished overrun edge surrounding the reflective mirror surface actually used for reflection is incorporated into the reflective mirror surface of mirrors M1 to M5 and, at the edge, protrudes at least 10 mm beyond this reflective mirror surface along the entire circumference of the reflective surface. Thus, an overhang in the form of a polished overrun edge of at least 10 mm exists between the reflective mirror surface and the area of ​​the mirror surface that has not been further polished.

[0076] The object plane 6 and the image plane 12 extend parallel to each other with good approximation.

[0077] The projection optics unit 10 has an intermediate image 23 in the form of an intermediate field of view region between the object field 5 and the image field 11, which may have the form of a fire surface. In the yz section, the intermediate image 23 is located between mirrors M3 and M4 in the imaging beam path of the imaging light 16. No intermediate image is present in the xz section.

[0078] The distance Z between the object plane 6 and the image plane 12 is 1976.14 mm in the z-direction.

[0079] Object-image offset d OIS The object-image offset d is 966.26 mm. OIS This object-image offset d is measured between the central field of view point of the object field 5 and the central field of view point of the image field 11, perpendicular to the perpendicular N of the object plane 6. OIS This is smaller than the distance Z, and therefore smaller than the spatial distance between the object field 5 and the image field 11.

[0080] The two mirrors M3 and M4, and the two mirrors M4 and M5, have a subtractive deflection effect on the principal rays of the central object's field point. Thus, the principal rays of the central object's field point are guided in a zigzag pattern through the beam path between mirrors M3 and M5.

[0081] The total transmittance of the projection optical unit 10, which is expressed as the product of the EUV reflectances of each mirror M1 to M5 with respect to the illumination light 16 along the imaging beam path passing through the projection optical unit 10, is 13.39% in the projection optical unit 10 shown in Figure 2. Therefore, on average, each of the mirrors M1 to M5 has a reflectance of 67%.

[0082] Therefore, the total transmittance of mirrors M1 to M5, i.e., the total transmittance of the projection optical unit 10, is greater than 10%.

[0083] Downstream of the intermediate image in the yz section 23, the projection optics unit 10 has a pupil plane in the region of reflection at the second-to-last mirror M4. In the case of the projection optics unit 10, the aperture can be restricted by an aperture diaphragm, which restricts the imaging beam path, particularly at the edge, and may be attached to the mirror M4. If necessary, an internal obscuration may be defined at the mirror M4 using an appropriate diaphragm portion.

[0084] The z-direction distance between mirror M5 and image field 11 is 75 mm.

[0085] The entire projection optical unit 10 can be housed in a cube with edge lengths of 489 mm, 1152 mm, and 1544 mm in the x, y, and z directions.

[0086] Between the object field 5 and the image field 11, the imaging beam path of the projection optics unit 10 does not include an intersection region where two sections of the imaging beam path intersect. Overall, the imaging beam path extends in a zigzag pattern between the object field 5 and the image field 11.

[0087] The projection optical unit 10 is telecentric on the image side.

[0088] Mirrors M1-M5 are coated to optimize their reflectivity to the imaging light 16. In particular, for GI mirrors, this may be a lanthanum coating, a boron coating, a boron coating with a lanthanum top layer, or a ruthenium coating. Other coating materials, especially lanthanum nitride and / or B4C, may also be used. For grazing incidence mirror M2, for example, a coating containing a single layer of boron or lanthanum can be used. The high-reflectivity layers of mirrors M1, M3, M4, and M5, especially for direct incidence, can be constructed as multilayers, with consecutive layers made from different materials. Alternating material layers are also usable. A typical multilayer can have 50 double layers, each made from a boron layer and a lanthanum layer. Layers containing lanthanum nitride and / or boron, especially B4C, may also be used.

[0089] Table 1 below summarizes the parameters of the projection optics unit 10. In addition to the data already described above, Table 1 also specifies the angle of the principal ray of the central field of view point relative to the z axis (6.04°), as well as the usable etendue and mean wavefront aberration RMS values ​​of the projection optics unit. The mean wavefront aberration RMS for the projection optics unit 10 is 10.3 mλ. Thus, this mean wavefront aberration is less than 50 mλ, less than 25 mλ, less than 2 mλ, and especially less than 15 mλ across the entire image field 11 used.

[0090] [Table 1]

[0091] Tables 2a and 2b below summarize the parameters of the mirrors M1 to M5 of the projection optical unit 10: "maximum incident angle," "spread of the reflective surface in the x-direction," "spread of the reflective surface in the y-direction," and "maximum mirror diameter."

[0092] [Table 2]

[0093] [Table 3]

[0094] The GI mirror M2 has a minimum incident angle of 70.9° for imaging light and a maximum incident angle of 76.2°. The NI mirrors M1 and M3-M5 have a minimum incident angle of 4.1° and a maximum incident angle of 26.9°. The maximum incident angle is 12.0° for the last mirror, M5.

[0095] The M5 mirror has the largest reflective surface area.

[0096] Mirror M4, approximately 400mm in size, has the smallest reflective surface spread in the x-direction. Mirror M5, approximately 490mm in size, has the largest reflective surface spread in the x-direction. Mirror M3, approximately 108mm in size, has the smallest reflective surface spread in the y-direction. The final mirror, M5, approximately 466mm in size, also has the largest reflective surface spread in the y-direction.

[0097] The total mirror surface area, equivalent to the sum of the mirror surfaces used for mirrors M1 to M5, is 1.5 m². 2 It is less than . This total mirror surface includes a polished overrun edge with a 20 mm edge width. This total mirror surface is 0.63 m in the projection optical unit 10 as shown in Figure 2. 2 That is the case.

[0098] Table 2c below shows the surface dimensions of individual mirrors M1 to M5, including the polished overrun edge.

[0099] [Table 4]

[0100] The total number of mirrors M1 to M5, when linearly polarized imaging light 16 is used, has a total polarization rotation of 10° or less along the imaging beam path. This total polarization rotation may be less than 7°, less than 6°, less than 5°, or less than 4°.

[0101] The maximum total polarization rotation of the linearly polarized imaging light 16 in the imaging beam path of the projection optics unit 10 between the object field 5 and the image field 11 is 3.13°.

[0102] Mirrors M1-M5 are realized as free surfaces that cannot be described by rotational symmetry functions. Other embodiments of the projection optical unit 10 are also possible in which at least one of the mirrors M1-M5 is realized as a rotationally symmetric aspherical surface. It is also possible that all of the mirrors M1-M5 are realized as such aspherical surfaces.

[0103] A free surface can be described by the following free surface equation (Equation 1).

number

[0104] The following applies to the parameters of equation (1).

[0105] Z is the sagittal height of the freeform surface at point x,y, and x 2 +y 2 =r 2 Here, r is the distance from the reference axis (x=0; y=0) of the free surface equation.

[0106] In equation (1) for the free surface, C1, C2, C3... represent the coefficients of the free surface series expansion as powers of x and y.

[0107] In the case of a cone-shaped base region, c x , c y c is a constant corresponding to the vertex curvature of the corresponding aspherical surface. Therefore, c x = 1 / R x (1 / RDX) and c y = 1 / Ry (1 / RDY) is the relevant value. x and k y (CCX,CCY) correspond to the cone constants of the corresponding aspherical surfaces. Therefore, equation (1) describes a free surface of a biconical shape.

[0108] Alternative freeform surfaces can be generated from rotationally symmetric reference surfaces. Such freeform surfaces for the reflective surfaces of mirrors in the projection optics unit of a microlithography projection exposure apparatus are known from U.S. Patent Application Publication No. 20070058269.

[0109] Alternatively, a free surface can be described by the following free surface equation (Equation 2).

number

number

[0110] In this case, Z is a point expressed in polar coordinates.

number

number

[0111]

number

[0112]

number

number

[0113] For descriptions of Forbes free surfaces and Forbes polynomials, DE102018214437A1 and the references cited herein are further referenced.

[0114] The mirror coordinates are specified with respect to a coordinate system defined such that the origin of the xyz coordinate system is located at the center of the image field on the wafer, the z axis of this coordinate system is perpendicular to the image plane and points from the center of the image field toward the mirror that limits the final aperture of the imaging optical unit, and the y axis of the coordinate system is oriented such that the reticle is located in the positive y coordinate.

[0115] Alternatively, freeform surfaces can also be described using two-dimensional spline surfaces. Examples include Bézier curves or non-uniform rational basis splines (NURBS). For example, a two-dimensional spline surface can be described by a grid of points on the xy plane and their associated z values, or by these points and their associated gradients. Depending on the type of spline surface, the completed surface can be obtained by interpolation between grid points, for example, using polynomials or functions that have specific properties with respect to their continuity and differentiability. An example of this is an analytical function.

[0116] The optical design data for the reflective surfaces of mirrors M1 to M5 of the projection optical unit 10 can be obtained from the other tables below.

[0117] Table 3 (Table 3a) specifies the coordinates of the surface origin of each mirror surface and one area of ​​the object field 5 with respect to the xyz coordinate system of the image field 11.

[0118] The first column specifies the distance of each mirror or object field 5 from the coordinate origin at the center of the image field 11 in the x-direction (first column), y-direction (second column), and z-direction (third column).

[0119] The other columns in Table 3 (Table 3b) further specify the inclination values ​​of the respective surfaces or object fields 5 of mirrors M1 to M5 with respect to the x, y, and z axes. In the embodiment shown in Figure 2, the object field 5 and the image field 11 extend parallel to each other.

[0120] Table 4 (Tables 4a / 4b...) shows, for each mirror M1 to M5, the parameters RDX, RDY, CCX, CCY, and the values ​​of the coefficients C1, C2, C3... of the series expansion of the free surface according to equation (1) above, arranged according to the powers of x and y.

[0121] Table 5 shows the reflectance of mirrors M1 to M5 and the total transmittance of the projection optical unit 10, which is 13.4%.

[0122] [Table 5]

[0123] [Table 6]

[0124] [Table 7] TIFF2026512035000017.tif222153 TIFF2026512035000018.tif111153

[0125] [Table 8] TIFF2026512035000020.tif222153 TIFF2026512035000021.tif111153

[0126] [Table 9]

[0127] A Miller with values ​​RDX and RDY having different signs is a saddle point type or minimax basic shape.

[0128] Figure 3 shows a further embodiment of the projection optical unit or imaging optical unit 27, which may be used in the projection exposure apparatus 1 instead of the projection optical unit 10 in the embodiment according to Figure 2. With respect to Figures 1 and 2, and in particular with respect to Figure 2, components and functions corresponding to those already described above are indicated by the same reference numerals and are not described in detail.

[0129] The projection optics unit 27 has a total of six mirrors M1 to M6 between the object field 5 and the image field 11 in the imaging beam path. Mirrors M1, M4, M5, and M6 are NI mirrors, and mirrors M2 and M3 are GI mirrors.

[0130] The two GI mirrors M2 and M3 have a subtractive deflection effect on the principal ray of the central object's field point.

[0131] The two NI mirrors M4 and M5 have their deflection effects added together with respect to the principal rays of the central object field point. Then, the two final mirrors M5 and M6 have a subtractive deflection effect with respect to the principal rays of the central object field point. In particular, the deflection effects of the other mirrors M1 to M3, as well as these deflection effects of mirrors M4 to M6, lead to the imaging beam path after reflection from mirror M1 being guided around the back side of the final mirror M6, resulting in the component imaging beam passing through mirror M6 on the side farther from mirror M1 between mirrors M4 and M5.

[0132] The number of intermediate image planes in the x and y directions within the beam path between the object field 5 and the image field 11 differs for the projection optics unit 27. The imaging scale β in the yz plane is different. y When = +4.00, the projection optical unit 27 has an intermediate image 23, which may have a fire surface shape in particular, as shown by the meridian cross section in Figure 2. x When the value is -4.00, the projection optical unit 10 does not have an intermediate image in the imaging direction perpendicular to it. The intermediate image 23 is located in the meridional plane of the projection optical unit 27, that is, in the plane containing the principal ray of the central field of view point of the projection optical unit 27.

[0133] Examples of projection optical units in which the number of such intermediate images differs in the x and y directions, or in imaging planes perpendicular to each other, are known from U.S. Patent No. 1,656,400. Alternatively, the projection optical unit 27 may be designed to have no intermediate images, or to have the same number of intermediate images in the x and y directions.

[0134] The image plane 12 is the first field of view after the object plane 6 in the xz principal plane (sagittal plane) of the projection optical unit 27 perpendicular to the meridian plane, that is, in the imaging beam path of the projection optical unit 27 perpendicular to the yz meridian plane. Therefore, the projection optical unit 27 does not have an intermediate image perpendicular to the meridian plane. Thus, there is an image inversion perpendicular to the meridian plane.

[0135] In the projection optical unit 27, the principal ray angle of the central field of view point with respect to the perpendicular N of the object surface 6 extends in the exact opposite direction compared to the case of the projection optical unit 10, and is 6.13° in the projection optical unit 27. The possible paths of the input coupled illumination beam 16 of the illumination optical unit 4 are also shown in Figure 3.

[0136] The following tables summarize the parameters and optical design of the projection optics unit 27. Regarding its structure, these tables correspond to those already described above with respect to Figure 2.

[0137] [Table 10]

[0138] [Table 11]

[0139] [Table 12]

[0140] [Table 13]

[0141] [Table 14]

[0142] [Table 15] TIFF2026512035000029.tif228153

[0143] [Table 16] TIFF2026512035000031.tif228153

[0144] [Table 17]

[0145] In the projection optical unit 27, none of the mirrors M1 to M6 have an x-direction spread greater than 420 mm. Therefore, the x-direction spread is less than 500 mm, less than 450 mm, and less than 425 mm for all the mirrors in the projection optical unit 27.

[0146] None of the mirrors in the projection optical unit 27 have a y-direction spread greater than 600 mm. Except for the GI mirror M3, none of the other mirrors have a y-direction spread greater than 350 mm.

[0147] Five of the six mirrors in the projection optical unit 27, specifically mirrors M1, M2, M4, M5, and M6, have a maximum mirror diameter of less than 420 mm.

[0148] In the projection optical unit 27 shown in Figure 3, the total mirror area, including a 20 mm polishing overrun, is 0.70 m². 2 That is the case.

[0149] The total polarization rotation of the linearly polarized imaging light 16 in the imaging beam path of the projection optics unit 27 between the object field 5 and the image field 11 is 3.16° or less.

[0150] In the projection optics unit 27, the image-side pupil plane is located between mirrors M5 and M6 in the imaging beam path.

[0151] Figure 4 shows a further embodiment of the projection optical unit or imaging optical unit 28, which may be used in the projection exposure apparatus 1 instead of the projection optical unit 10 in the embodiment according to Figure 2. With respect to Figures 1 to 3, and especially with respect to Figures 2 and 3, components and functions corresponding to those already described above are indicated by the same reference numerals and a detailed description is omitted.

[0152] Regarding the basic design, the projection optical unit 28 shown in Figure 4 is the same as the projection optical unit 10 shown in Figure 2, except for the representation which is a mirror image centered on the xz plane. The essential difference is that the projection optical unit 28 has a total of six mirrors, two of which are GI mirrors, specifically the first GI mirror M2 between NI mirrors M1 and M3, and the second GI mirror M4 between NI mirrors M3 and M5.

[0153] Mirrors M4, M5, and M6 each have a subtractive deflection effect on the principal ray of the central object's field point, resulting in the imaging beam path being guided in a zigzag pattern through these mirrors M4-M6.

[0154] The following tables summarize the parameters and optical design of the projection optics unit 28. Regarding its structure, these tables correspond to those already described above with respect to Figure 2. Table 4 (Tables 4a / 4b) describes the free surfaces of mirrors M1 to M6 based on Forbes' free surface equation (2) mentioned above.

[0155] [Table 18]

[0156] [Table 19]

[0157] [Table 20]

[0158] [Table 21]

[0159] [Table 22]

[0160] [Table 23] TIFF2026512035000039.tif189153

[0161] [Table 24] TIFF2026512035000041.tif189153

[0162] [Table 25]

[0163] In the case of the projection optics unit 28, an intermediate image 23 exists in the meridional plane near the reflection at mirror 4 between mirrors M3 and M4 in the imaging beam path, which allows for a relatively small y-direction spread of this GI mirror M4.

[0164] In each case, all mirrors in the projection optical unit 28 have an extension of less than 500 mm in both the x-axis direction and the y-axis direction.

[0165] With the exception of mirror M6, which defines the image-side numerical aperture, all other mirrors M1 to M5 of the projection optical unit 28 have a spread of less than 320 mm in the y-direction.

[0166] In the projection optical unit 28 shown in Figure 4, the total mirror area, including a 20 mm polishing overrun, is 0.58 m². 2 That is the case.

[0167] The maximum total polarization rotation of the linearly polarized imaging light 16 in the imaging beam path of the projection optics unit 28 between the object field 5 and the image field 11 is 6.0°.

[0168] In the projection optics unit 28, the image-side pupil plane is located between mirrors M5 and M6 in the imaging beam path.

[0169] Figure 5 shows a further embodiment of the projection optical unit or imaging optical unit 29, which may be used in the projection exposure apparatus 1 instead of the projection optical unit 10 in the embodiment according to Figure 2. With respect to Figures 1 to 4, and especially with respect to Figures 2 to 4, components and functions corresponding to those already described above are indicated by the same reference numerals and a detailed description is omitted.

[0170] Regarding the basic structure, the projection optical unit 29 shown in Figure 5 is the same as the projection optical unit 28 shown in Figure 4.

[0171] The following tables summarize the parameters and optical design of the projection optics unit 29. Regarding its structure, these tables correspond to those already described above with respect to Figures 2 and 4.

[0172] [Table 26]

[0173] [Table 27]

[0174] [Table 28]

[0175] [Table 29]

[0176] [Table 30]

[0177] [Table 31] TIFF2026512035000049.tif234153 TIFF2026512035000050.tif84153

[0178] [Table 32] TIFF2026512035000052.tif234153 TIFF2026512035000053.tif84153

[0179] [Table 33]

[0180] In the projection optical unit 29 shown in Figure 5, the total mirror area, including a 20 mm polishing overrun, is 0.59 m². 2 That is the case.

[0181] The maximum total polarization rotation of the linearly polarized imaging light 16 in the imaging beam path of the projection optics unit 29 between the object field 5 and the image field 11 is 5.97°.

[0182] Figure 6 shows a further embodiment of the projection optical unit or imaging optical unit 30, which may be used in the projection exposure apparatus 1 instead of the projection optical unit 10 in the embodiment shown in Figure 2. With respect to Figures 1 to 5, and especially with respect to Figures 2 to 5, components and functions corresponding to those already described above are indicated by the same reference numerals and a detailed description is omitted.

[0183] Regarding the basic structure, the projection optical unit 30 shown in Figure 6 is similar to the projection optical unit 27 shown in Figure 3. The essential difference is that in the projection optical unit 30, mirrors M4, M5, and M6 each have a subtractive deflection effect on the principal ray of the central object field point, and as a result, the beam path of the imaging light 16 is guided in a zigzag pattern in the region of mirrors M3 to M6. In detail, as a result, the component beam path between mirrors M4 and M5 is located between mirrors M1 and M6 in the projection optical unit 30.

[0184] In the projection optics unit 30, the intermediate image 23 in the yz plane is located between mirrors M4 and M5 in the imaging beam path, near the reflection at mirror M4. This leads to a small y-direction spread of mirror M4.

[0185] The following tables summarize the parameters and optical design of the projection optics unit 30. Regarding its structure, these tables correspond to those already described above with respect to Figure 2.

[0186] [Table 34]

[0187] [Table 35]

[0188] [Table 36]

[0189] [Table 37]

[0190] [Table 38]

[0191] [Table 39] TIFF2026512035000061.tif222153 TIFF2026512035000062.tif61153

[0192] [Table 40] TIFF2026512035000064.tif222153 TIFF2026512035000065.tif61153

[0193] [Table 41]

[0194] In the projection optical unit 30 according to FIG. 6, the total mirror area including a polishing overrun of 20 mm is 0.64 m 2 is.

[0195] The maximum total polarization rotation of the linearly polarized imaging light 16 in the imaging beam path of the projection optical unit 30 between the object field 5 and the image field 11 is 5.38°.

[0196] FIG. 7 shows a further embodiment of the projection optical unit or imaging optical unit 31, which can be used in the projection exposure apparatus 1 in place of the projection optical unit 10 of the embodiment according to FIG. 2. With respect to FIGS. 1 to 6, particularly with respect to FIGS. 2 to 6, components and functions corresponding to those already described above are denoted by the same reference numerals, and detailed description thereof is omitted.

[0197] Regarding the basic structure, the projection optical unit 31 according to FIG. 7 is the same as the projection optical units 28 and 29 according to FIGS. 4 and 5.

[0198] The following table is a summary of the parameters and optical design of the projection optical unit 31. Regarding its structure, these tables correspond to those already described above with respect to FIG. 2. Table 4 (Table 4a / 4b) describes the free-form surfaces of the mirrors M1 to M6 based on the free-form surface type (2) of Forbes described above.

[0199] [Table 42]

[0200] [Table 43]

[0201] [Table 44]

[0202] [Table 45]

[0203] [Table 46]

[0204] [Table 47] TIFF2026512035000073.tif234153 TIFF2026512035000074.tif84153

[0205] [Table 48] TIFF2026512035000076.tif234153 TIFF2026512035000077.tif84153

[0206] [Table 49]

[0207] In the projection optical unit 31 shown in Figure 7, the total mirror area, including a 20 mm polishing overrun, is 0.56 m². 2 That is the case.

[0208] The maximum total polarization rotation of the linearly polarized imaging light 16 in the imaging beam path of the projection optics unit 31 between the object field 5 and the image field 11 is 6.04°.

[0209] FIG. 8 shows a further embodiment of the projection optical unit or imaging optical unit 32, which can be used in the projection exposure apparatus 1 in place of the projection optical unit 10 of the embodiment according to FIG. 2. With respect to FIGS. 1 to 3, in particular with respect to FIGS. 2 and 3, the components and functions corresponding to those already described above are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0210] Regarding the basic structure, the projection optical unit 32 according to FIG. 8 is the same as the projection optical units 28, 29, and 31 according to FIGS. 4, 5, and 7.

[0211] The following table is a summary of the parameters and optical design of the projection optical unit 32. Regarding its structure, these tables correspond to those already described above with respect to FIGS. 2 and 4.

[0212]

Table 50

[0213]

Table 51

[0214]

Table 52

[0215]

Table 53

[0216]

Table 54

[0217]

Table 55

[0218] [Table 56] TIFF2026512035000088.tif234153 TIFF2026512035000089.tif84153

[0219] [Table 57]

[0220] In the projection optical unit 32 shown in Figure 8, the total mirror area, including a 20 mm polishing overrun, is 0.48 m². 2 That is the case.

[0221] The maximum total polarization rotation of the linearly polarized imaging light 16 in the imaging beam path of the projection optics unit 32 between the object field 5 and the image field 11 is 6.04°.

[0222] Figure 9 shows a further embodiment of the projection optical unit or imaging optical unit 33, which may be used in the projection exposure apparatus 1 instead of the projection optical unit 10 in the embodiment shown in Figure 2. With respect to Figures 1 to 8, and in particular with respect to Figures 2 to 8, components and functions corresponding to those already described above are indicated by the same reference numerals and a detailed description is omitted.

[0223] With regard to the guidance of the imaging beam path around the last mirror M6, the embodiment of the projection optical unit 33 shown in Figure 9 is similar to the embodiment of the projection optical unit 27 shown in Figure 3.

[0224] In the projection optics unit 33, mirrors M3 and M4 are realized as GI mirrors. The deflection effects of these mirrors M3 and M4 are added together with respect to the principal rays of the central object's field point.

[0225] The subsequent mirrors M5 and M6 also have their deflection effects added to the principal rays of the central object field point, resulting in the intersection of two component imaging beam paths: firstly, the component imaging beam path between mirrors M4 and M5, and secondly, the component imaging beam path between mirror M6 and the image field 11. Mirror M4 on one side and M5 on the other side are on opposite sides of the final component imaging beam path between mirror M6 and the image field 11.

[0226] The two NI mirrors M1 and M2 have a subtractive deflection effect on the principal ray at the central field of view, where it is guided in a zigzag pattern.

[0227] In the projection optics unit 33, the yz intermediate image 23 exists near the reflections from the two GI mirrors M3 and M4 in the imaging beam path. This results in a small y-direction spread, especially for mirror M4.

[0228] The following tables summarize the parameters and optical design of the projection optics unit 33. Regarding its structure, these tables correspond to those already described above with respect to Figure 2.

[0229] [Table 58]

[0230] [Table 59]

[0231] [Table 60]

[0232] [Table 61]

[0233] [Table 62]

[0234] [Table 63] TIFF2026512035000097.tif228153

[0235] [Table 64] TIFF2026512035000099.tif228153

[0236] [Table 65]

[0237] In the projection optical unit 33 shown in Figure 9, the total mirror area, including a 20 mm polishing overrun, is 0.77 m². 2 That is the case.

[0238] The maximum total polarization rotation of the linearly polarized imaging light 16 in the imaging beam path of the projection optics unit 33 between the object field 5 and the image field 11 is 4.80°.

[0239] Figure 10 shows a further embodiment of the projection optical unit or imaging optical unit 34, which may be used in the projection exposure apparatus 1 instead of the projection optical unit 10 in the embodiment shown in Figure 2. With respect to Figures 1 to 9, and in particular with respect to Figures 2 to 9, components and functions corresponding to those already described above are indicated by the same reference numerals and a detailed description is omitted.

[0240] Regarding the basic structure, the projection optical unit 34 shown in Figure 10 is the same as the projection optical unit 30 shown in Figure 6.

[0241] Compared to projection optical unit 30, projection optical unit 34 has a larger distance Z between the object plane 6 and the image plane 12. More specifically, the surfaces of mirrors M5 and M6 are significantly smaller in the case of projection optical unit 34 than in the case of projection optical unit 30.

[0242] The following tables summarize the parameters and optical design of the projection optics unit 34. Regarding its structure, these tables correspond to those already described above with respect to Figure 2.

[0243] In the case of the projection optical unit 34 shown in Figure 10, both the entrance pupil position in the meridional plane and the sagittal plane perpendicular thereto are located at approximately the same distance upstream from the object field in the imaging light beam path. In this case, the distance of this common entrance pupil position is approximately 2.4 m upstream of the object field 5. There, within the illumination optical unit 4, an reachable pupil can be created. In detail, a pupil facet mirror 21 can be placed there. Then, there is no need to place any further components of the illumination optical unit to guide the illumination light 16 between the last facet mirror of the illumination optical unit 4 and the object field 5, which avoids attenuation of the available illumination light due to reflection losses. For example, the arrangement shown in Figure 1 is possible, where the illumination light 16 reflected by the pupil facet 22 of the pupil facet mirror 21 is guided directly to the object field 5.

[0244] [Table 66]

[0245] [Table 67]

[0246] [Table 68]

[0247] [Table 69]

[0248] [Table 70]

[0249] [Table 71] TIFF2026512035000107.tif222153 TIFF2026512035000108.tif61153

[0250] [Table 72] TIFF2026512035000110.tif222153 TIFF2026512035000111.tif61153

[0251] [Table 73]

[0252] In the projection optical unit 34 shown in Figure 10, the total mirror area, including a 20 mm polishing overrun, is 0.73 m². 2 That is the case.

[0253] The maximum total polarization rotation of the linearly polarized imaging light 16 in the imaging beam path of the projection optics unit 34 between the object field 5 and the image field 11 is 5.05°.

[0254] Each of the projection optical units 10 and 27-34 described above has an image-side numerical aperture of at least 0.3. Each of these described projection optical units has an image-side numerical aperture of less than 0.5, and in particular less than 0.4.

[0255] Depending on the embodiment of the projection optics unit described above, the projection optics unit may have a different number of NI mirrors and / or GI mirrors, for example, exactly one GI mirror or exactly three GI mirrors. Three or fewer or five or more NI mirrors are also possible, for example, two, three, or five NI mirrors.

[0256] To manufacture microstructures or nanostructure components, the projection exposure apparatus 1 is used as follows: First, a reflective mask 7 or reticle and a substrate or wafer 13 are provided. Then, the structure on the reticle 7 is projected onto the photosensitive layer of the wafer 13 using the projection exposure apparatus 1. Subsequently, the microstructure or nanostructure on the wafer 13, and thus the microstructure component, is manufactured by developing the photosensitive layer.

Claims

1. An imaging EUV optical unit (10;27;28;29;30;31;32;33;34) for imaging the object field (5) onto the image field (11), - A plurality of mirrors (M1-M5; M1-M6) are provided to guide EUV imaging light (16) with a wavelength shorter than 30 nm along the imaging beam path from the object field (5) to the image field (11), - Equipped with at least 0.3 image-side numerical aperture, - The total transmittance of the plurality of mirrors (M1-M5; M1-M6) is greater than 10%, - The total mirror surface area, which corresponds to the sum of all the mirror surfaces used by the aforementioned plurality of mirrors (M1 to M5; M1 to M6), is 1.5 m 2 The imaging EUV optical units are less than (10; 27; 28; 29; 30; 31; 32; 33; 34).

2. The imaging EUV optical unit according to claim 1, characterized in that a polished overrun edge (PR) surrounding the reflective mirror surface (RS) actually used for reflection is incorporated into the mirror surface (NS) of the mirrors (M1 to M5; M1 to M6), and at the edge, it protrudes at least 10 mm beyond the reflective mirror surface along the entire circumference of the reflective surface.

3. The imaging EUV optical unit according to claim 1 or 2, characterized by a maximum extent of at least 26 mm of the image field (11) along the maximum area extension direction (x).

4. The imaging EUV optical unit according to any one of claims 1 to 3, characterized by a scanning range of the image field (11) of at least 2 mm along the scanning region extending direction (y).

5. The imaging EUV optical unit according to any one of claims 1 to 4, characterized by a wavefront aberration RMS of less than 50 mλ across the entire image field (11).

6. The imaging EUV optical unit according to any one of claims 1 to 5, characterized in that when linearly polarized EUV imaging light (16) is used, the total number of mirrors (M1 to M5; M1 to M6) results in a maximum total polarization rotation of 10° or less along the imaging beam path.

7. The imaging EUV optical unit according to any one of claims 1 to 6, characterized in that the image field (11) corresponds to the first field of view region in the imaging beam path downstream of the object field (5) with respect to at least one cross section (xz).

8. An imaging EUV optical unit according to any one of claims 1 to 7, comprising at least five mirrors (M1 to M5; M1 to M6).

9. An imaging EUV optical unit according to any one of claims 1 to 8, comprising at least one GI mirror (M2; M2, M3; M2, M4; M3, M4).

10. An imaging EUV optical unit according to any one of claims 1 to 9, characterized by precisely four NI mirrors (M1, M3, M4, M5; M1, M4, M5, M6; M1, M3, M5, M6; M1, M2, M5, M6).

11. - An illumination optical unit (4) for illuminating the object field (5) with imaging light (16), - An imaging optical unit (10) according to any one of claims 1 to 10 and An optical system equipped with

12. A projection exposure apparatus comprising the optical system described in claim 11 and an EUV light source (3).

13. - A method step of providing a reticle (7) and a wafer (13), - A method of projecting a structure on the reticle (7) onto the photosensitive layer of the wafer (13) using the projection exposure apparatus described in claim 12, - A method for generating microstructures and / or nanostructures on the wafer (13) A method for manufacturing structural components, including [a specific component].

14. A structural component manufactured according to the method of claim 13.

Images