EUV collector

Abstract

Provides EUV collector. An EUV collector (34) is used to collect EUV working light (10) emitted from a light source area (21). A diffraction grating (24) for the EUV working light (10) is mounted on the reflecting surfaces (30, 31, 35) of the collector (34). The EUV working light (10) emitted from the light source area (21) is diffracted by the diffraction grating (24) toward the collecting area (25). The reflecting surfaces (30, 31, 35) are at least partially designed as planar reflecting surfaces (30), parabolic reflecting surfaces, rotationally symmetric truncated conical reflecting surfaces (35), or hollow cylindrical reflecting surfaces (31). A reflecting surface design including an elliptical reflecting surface portion with a first focus at the light source area (21) and a second focus (59, 60) spaced apart from each other and from the collecting area (25) is also feasible. This results in an EUV collector that allows for an effective separation between the EUV used light that is collected with the aid of the collector and extraneous light that has a wavelength different from the used light wavelength.

Description

[Technical Field]

[0001] This patent application claims priority from German patent application DE 102022213822.8, the contents of which are incorporated herein by reference.

[0002] The present invention relates to an EUV collector. Furthermore, the invention relates to a source-collector module comprising such an EUV collector, to an illumination optical unit for an EUV projection exposure apparatus comprising such an EUV collector, to a projection exposure apparatus comprising such an illumination optical unit, to a method for producing microstructured or nanostructured components with the aid of such a projection exposure apparatus, and to components produced using such a method. [Background technology]

[0003] EUV collectors are known from WO 2022 / 002566 A1, from U.S. Pat. No. 9,541,685, from U.S. Pat. No. 7,084,412, and from DE 10 2017 204 312 A1. Further variations in the design of EUV collectors are known from U.S. Pat. Nos. 9,612,370, DE 10 2013 002 064 A1 and DE 10 2010 063 530 A1, and from U.S. Patent Application Publication No. 2009 / 0289205. Summary of the Invention

[0004] The object of the present invention is to develop an EUV collector in such a way that it is possible to achieve an effective separation between the EUV used light collected with the aid of the collector and extraneous light having a wavelength different from that of the used light at reasonable production costs.

[0005] According to the invention, this object is achieved by an EUV collector having the features specified in claim 1.

[0006] According to the present invention, it is recognized that an EUV collector, with which the diameter of the external light beam is greater than twice the diameter of the used light in the collection area, has the effect of reducing the thermal load on components exposed to the external light, in particular on external light traps caused by the incidence of the external light, thereby reducing the requirements on such components exposed to the external light, in particular on the external light traps, as well as, if applicable, reducing the thermal effects on components adjacent to the components exposed to the external light, in particular on components adjacent to the external light traps. After reflection at the reflective surface, the beam cross section of the external light beam along the external light beam path is greater than twice the diameter of the beam of EUV used light in the collection area. After the source area, the beam cross section of the external light beam along the entire external light beam path can be greater than twice the diameter of the beam of EUV used light in the collection area. The beam cross section of the external light beam, after reflection of the external light at the reflective surface, at the location of the component in the beam path exposed to the external light after the source area, particularly at the location of the external light trap, can be 20, 30, or even 50 times larger than the diameter of the beam of EUV-based light in the collection area. In particular, it has been recognized that the diffraction grating of such an EUV collector can be designed to ensure that the diffracted transfer of the EUV-based light to the collection area can be largely independent of the morphology of the reflective surface or reflective surface portion of the EUV collector. Therefore, the grating period of the diffraction grating on the reflective surface or reflective surface portion often depends on the location of the diffraction grating on the reflective surface or reflective surface portion. This dependence on a given geometric shape of the arrangement of the source area relative to the reflective surface and on a given target position for the collection area is crucial, and accordingly, solutions exist for this location dependence of the grating period.

[0007] The diffraction grating may be designed as a blazed diffraction grating to aid in the diffraction effect for EUV light.

[0008] At least a portion of the reflective surface portion may be designed such that extraneous light emitted from the source area is reflected back to the source area after reflection on the reflective surface portion, which may improve the energy efficiency of the EUV radiation source.

[0009] The extraneous light trap claimed in claim 2 may be designed to be absorptive, reflective and / or scattering.

[0010] An EUV collector as claimed in claim 3 having a reflective surface that is at least partially planar, parabolic, rotationally symmetrically frustoconical or hollow cylindrical can be produced at reasonable cost for this reflective surface.

[0011] In the case of a design using at least a partial parabolic reflecting surface, the parabolic focus of the parabolic reflecting surface may be located at the source area. The parabolic surface of the corresponding parabolic reflecting surface may have a vertical circle. This vertical circle may define a plane on which the source area is located. When a plasma EUV radiation source is used, this allows multiple guidance of the excitation light through the source area, in particular, for example, once directly and once after double reflection at the parabolic reflecting surface.

[0012] Two adjacent reflective surface portions of the EUV collector can be joined together via a transition edge region. Such a transition edge region can be realized in the form of an edge, i.e., a discontinuous transition, or in the form of a rounded edge, i.e., a continuous transition. Alternatively, there can be a further gap between adjacent reflective surface portions, which can be used, for example, to flush the reflective surface portions with a flushing or cleaning gas.

[0013] The rotational symmetry of the reflecting surface or reflecting surface portion claimed in claim 4 allows the reflecting surface base body of the collector to be produced by machining, so that the diffraction grating can be mounted on this base body.

[0014] The reflective surface portions claimed in claim 5 enable the construction of a compact EUV collector. The smallest angle between the reflective surface portions may be 90°, 45°, or 30°. The reflective surface portions may be seamlessly integrated with each other.

[0015] At least one of the reflective surface portions is planar. There may be multiple planar reflective surface portions, and all of the reflective surface portions may be designed to be planar.

[0016] A collector as claimed in claim 6, having at least two planar reflective surface portions, has corresponding advantages. The collector may have at least three planar reflective surface portions which form a minimum angle with respect to each other of greater than 7°.

[0017] The number of reflective surface portions may be even more than 3. As a rule, this number is less than 20.

[0018] The orientation of the symmetry axis claimed in claim 7 is adapted to the symmetry of the corresponding reflecting surface portion.

[0019] The arrangement claimed in claim 8 can be produced at relatively low cost. It is also feasible to provide a plurality of planar reflective panels, each of which may have a through opening for the excitation light.

[0020] The configurational variant claimed in claim 9 has proven to be particularly suitable depending on the structural requirements as well as the reflection and diffraction requirements.

[0021] The advantages of locating the light source area at the focus of at least one parabolic reflecting surface portion and / or at least one ellipsoidal reflecting surface portion as claimed in claim 10 have already been discussed above.

[0022] According to the present invention, the initially stated object is further achieved by an EUV collector having the features specified in claim 11 .

[0023] The present invention recognizes that EUV collectors having at least partially planar, parabolic, rotationally symmetric, frustoconical, or hollow cylindrical reflecting surfaces can be produced at reasonable cost relative to the reflecting surfaces. In particular, it is recognized that the diffraction gratings of such EUV collectors can be designed to ensure that the diffractive transfer of EUV light to the collection area is largely independent of the shape of the reflecting surface or reflecting surface portion of the EUV collector. Therefore, the grating period of a diffraction grating on a reflecting surface or reflecting surface portion often depends on the location of the diffraction grating on the reflecting surface or reflecting surface portion. This dependence on a given geometry of the source area relative to the reflecting surface and on a given target position for the collection area is critical, and accordingly, solutions exist for this location dependence of the grating period.

[0024] The diffraction grating may be designed as a blazed diffraction grating to support the diffraction effect on the EUV radiation used. When a design is made using at least a partial parabolic reflecting surface, the parabolic focus of this parabolic reflecting surface may be at the source area. The parabolic surface of the corresponding parabolic reflecting surface may have a vertical circle. This vertical circle may define a plane on which the source area is located. When a plasma EUV radiation source is used, this allows multiple guidance of the excitation light through the source area, in particular, for example, once directly and once after double reflection at the parabolic reflecting surface.

[0025] According to the present invention, the initially stated object is further achieved by an EUV collector having the features specified in claim 12 .

[0026] Alternatively, the EUV collector claimed in claim 12 may have two elliptical reflecting surface portions, one of which has a focal point in each case in the light source area and the other of which is in each case located away from the collection area, these further focal points being further away from each other. This allows for the reflection of extraneous light, i.e., light emitted from the light source area having a wavelength that deviates from the wavelength of the EUV light used, to be guided towards the further focal point of the elliptical reflecting surface portion away from the collection area. The elliptical reflecting surface portions may be seamlessly integrated into one another via a transition area. The transition area may be continuous, i.e., without edges.

[0027] Two adjacent reflective surface portions of the EUV collector can be joined together via a transition edge region. Such a transition edge region can be realized in the form of an edge, i.e., a discontinuous transition, or in the form of a rounded edge, i.e., a continuous transition. Alternatively, there can be a further gap between adjacent reflective surface portions, which can be used, for example, to flush the reflective surface portions with a flushing or cleaning gas.

[0028] The advantages of the source-collector module claimed in claim 13 correspond to those already described above in connection with the EUV collector. The EUV light source may be a plasma generating source, in particular an infrared excitation laser. The EUV light source may be a tin-based or xenon-based EUV light source. The diffraction grating of the EUV collector is preferably designed so that the wavelength range of the excitation light is not diffracted by the diffraction grating. Therefore, the excitation light is extraneous light that should not be diffracted by the diffraction grating.

[0029] Compared to collectors in which extraneous light of higher wavelengths is diffracted, the diffraction structures of the diffraction grating of the collector according to the invention that diffracts the EUV light have a shallower structure depth, which results in a shorter etching time in the etching generation process. The EUV light can be effectively separated from extraneous light so that lithography masks without a protective film, in particular without a pellicle, can be used during projection exposure, which can further reduce reflection losses.

[0030] The advantages of the illumination optical unit as claimed in claim 14, the projection exposure apparatus as claimed in claim 15, the production method for a microstructured or nanostructured component as claimed in claim 16, and the component produced by such a method as claimed in claim 17 correspond to the advantages already explained above with reference to the EUV collector or source-collector module. The produced component may be a microchip, in particular a memory chip.

[0031] According to an embodiment, the EUV collector may be an EUV collector for a mask inspection apparatus and / or for a mask metrology apparatus.In principle, mask inspection systems are known from US 10,042,248, DE 10220815 A1 and WO 2012 / 101269 A1.

[0032] According to an embodiment, the illumination optical unit may be an illumination optical unit for a mask inspection tool and / or for a mask metrology tool.

[0033] In this case, a mask inspection and / or mask metrology apparatus for mask inspection and / or mask metrology may comprise an EUV light source, an illumination optical unit, and a projection or imaging optical unit according to one of the exemplary embodiments described herein, which projection or imaging optical unit may in this case in particular project a magnified image from an object plane onto an image plane.

[0034] Exemplary embodiments of the invention are described in more detail below with reference to the drawings. [Brief explanation of the drawings]

[0035] [Figure 1] 1 shows a schematic representation of a projection exposure apparatus for EUV projection lithography in meridian section; [Figure 2] 1 shows the collector design of a projection exposure apparatus in meridional section, with the beam paths of the EUV light used on the one hand and of the external light, represented by a single ray in each case, on the other hand; [Figure 3] 3A-3C show further designs of the collector of the projection exposure apparatus in each case in meridian section; [Figure 4] 3A-3C show further designs of the collector of the projection exposure apparatus in each case in meridian section; [Figure 5] 3A-3C show further designs of the collector of the projection exposure apparatus in each case in meridian section; [Figure 6] 3A-3C show further designs of the collector of the projection exposure apparatus in each case in meridian section; [Figure 7] 3A-3C show further designs of the collector of the projection exposure apparatus in each case in meridian section; [Figure 8] 1 shows a perspective view of a further design of a collector for a projection exposure apparatus; [Figure 9] 3A-3C show further designs of the collector of the projection exposure apparatus in each case in meridian section; [Figure 10] 3A-3C show further designs of the collector of the projection exposure apparatus in each case in meridian section; [Figure 11] 3A-3C show further designs of the collector of the projection exposure apparatus in each case in meridian section; [Figure 12] FIG. 10 is a diagram illustrating schematically parameters that can be used to determine the geometry of the diffractive structures of the diffraction grating of each collector. [Figure 13] 3A-3C show schematic half-representations of further designs of the collector of a projection exposure apparatus in each case in meridian section; [Figure 14]3A-3C show schematic half-representations of further designs of the collector of a projection exposure apparatus in each case in meridian section; [Figure 15] 3A-3C show schematic half-representations of further designs of the collector of a projection exposure apparatus in each case in meridian section; [Figure 16] 3A-3C show schematic half-representations of further designs of the collector of a projection exposure apparatus in each case in meridian section; DETAILED DESCRIPTION OF THE INVENTION

[0036] First, the general structure of a microlithographic projection exposure apparatus 1 is described.

[0037] For the purposes of this description, a Cartesian xyz coordinate system is used: in Figure 1, the x-axis is oriented perpendicular to and into the plane of the drawing.

[0038] The y-axis is oriented to the right. The z-axis is oriented downwards. In the following FIG. 2, a local Cartesian xyz coordinate system is arranged such that the x-axis of the local coordinate system is parallel to the x-axis of the global coordinate system according to FIG. 1, the x and y axes in each case extending in the principal plane adjacent to the respective optical surface and used in connection with the description of the individual components.

[0039] Figure 1 shows a schematic representation of a microlithography projection exposure apparatus 1 in a meridional section. The illumination system 2 of the projection exposure apparatus 1 comprises not only a radiation source 3 but also an illumination optical unit 4 for exposing an object field 5 in an object plane 6. In this case, a reticle 6a, which is arranged in the object field 5 and held by a reticle holder 6b, is to be exposed. A projection optical unit 7 is used to project an image of the object field 5 onto an image field 8 in an image plane 9. An image of the structures on the reticle is projected onto a photosensitive layer of a wafer 9a, which is arranged in the region of the image field 8 in the image plane 9 and held by a wafer holder 9b.

[0040] The reticle holder 6b is driven by a reticle displacement drive 9c, and the wafer holder 9b is driven by a wafer displacement drive 9d. The drives provided by the two displacement drives 9c, 9d are performed in a synchronized manner with respect to each other along the y direction.

[0041] The radiation source 3 is an EUV radiation source emitting radiation in the range of 5 nm to 30 nm. It can be a plasma source, for example a GDPP (gas discharge produced plasma) source or an LPP (laser-produced plasma) source. For example, tin can be excited to form a plasma by a carbon dioxide laser operating at a wavelength of 10.6 μm, i.e. in the infrared range. A synchrotron-based radiation source may also be used as the radiation source 3. Those skilled in the art can find information about such radiation sources in, for example, U.S. Pat. No. 6,859,515.

[0042] EUV radiation 10 emitted by radiation source 3 is focused by collector 11, which will be described in more detail below and is shown only diagrammatically in Figure 1. Downstream from collector 11, EUV radiation 10 propagates through an intermediate focal plane 12 before being incident on a field facet mirror 13 having a number of field facets 13a. Field facet mirror 13 is arranged in a plane of illumination optical unit 4 that is optically conjugate to object plane 6.

[0043] The EUV radiation 10 is further referred to hereinafter as illumination light or imaging light. The EUV radiation 10 that is actually used for projection exposure in the projection exposure apparatus 1 is further referred to hereinafter as EUV working light. Light or radiation components that have a wavelength different from the EUV working light 10 are further referred to hereinafter as extraneous light. The working light wavelength may be 13.5 nm.

[0044] After the field facet mirror 13, the EUV radiation 10 is reflected by a pupil facet mirror 14 having a number of pupil facets 14a. The pupil facet mirror 14 is arranged in a pupil plane of the illumination optical unit 4, which is optically conjugate with the pupil plane of the projection optical unit 7. With the aid of the pupil facet mirror 14 and an imaging optical assembly in the form of a transfer optical unit 15 comprising mirrors 16, 17 and 18 (shown in this order in the beam path) for directing the EUV radiation 10, the images of the field facets 13a of the field facet mirror 13 are projected onto the object field 5, superimposed on one another. The last mirror 18 of the transfer optical unit 15 is a grazing incidence (GI) mirror. Depending on the design of the illumination optical unit 4, the transfer optical unit 15 may further be completely or partially omitted.

[0045] 2 shows the design of the collector 11 in meridional section. The collector 11 has a reflective surface 20 aligned with a source area 21 of the radiation source 3 from which radiation comprising the EUV radiation 10 emanates. The reflective surface 20 is designed as a generally planar, flat reflective surface. The reflective surface 20 has a through opening 22 through which excitation light 23 passes to generate a plasma in the source area 21. The excitation light 23 may have an excitation light wavelength in the infrared wavelength range, for example in the range of 10.6 μm.

[0046] The reflective surface 20 is designed as a planar reflective panel.

[0047] A diffraction grating 24 for the EUV working light 10 is mounted on the reflecting surface 20. The diffraction grating 24 is designed so that the EUV working light 10 emitted from the light source area 21 is diffracted by the diffraction grating 24 toward the collecting area 25. The collecting area 25 is located in the intermediate focal plane 12. The reflecting surface 20 can extend parallel to the intermediate focal plane 12.

[0048] The reflecting surface 20 with the diffraction grating 24 may be designed in the manner of a Fresnel mirror.

[0049] A connecting line 26 between the center of the light source area 21 and the center of the light collection area 25 is perpendicular to the plane of arrangement of the reflecting surface 20. The excitation light 23 is emitted through the through opening 22 and reaches the light source area 21 along this connecting line 26.

[0050] The reflecting surface 20 may be designed symmetrically about the connecting line 26 , which represents the axis of symmetry of the reflecting surface 20 and also of the entire collector 11 .

[0051] The connecting line 26 may be the optical axis of the collector 11 .

[0052] The diffraction grating 24 is structured, eg, blazed, such that reflections off the diffractive structures of the diffraction grating 24 assist in diffracting the EUV radiation in the direction of the collection area 25 .

[0053] Light or radiation components 27, which are emitted from the source area 21 and have wavelengths different from the working wavelength of the EUV working light 10, and which may also be referred to as extraneous light, are not diffracted by the reflecting surface 20 of the collector 11, but are reflected according to the extent of the planar configuration of the reflecting surface 20. This is illustrated by the example of a single ray of extraneous light 27 in FIG.

[0054] EUV light used wavelength λ N and the wavelength λ of external light 27 F The wavelength difference between satisfies the following relation:

number

[0055] This wavelength difference (the left side of the above equation) may be greater than 10%, greater than 20%, greater than 25%, greater than 30%, greater than 40%, greater than 50%, greater than 90%, greater than 95%, and greater than 99%.

[0056] The angle of incidence of the external light 27 on the plane 20 a of the reflecting surface 20 is equal to the angle of reflection of the external light 27 reflected by the reflecting surface 20 .

[0057] The collector 11 according to FIG. 2 provides a good spatial separation between the EUV utilized light 10 and the extraneous light 27 .

[0058] The extraneous light 27 reflected by the reflective surface 20 can then be transferred to the extraneous light trap 28, which is shown schematically in Figure 2 as the illustrated single ray of extraneous light 27. The reflective surface 20 is in this case designed to reflect the extraneous light 27 along an extraneous light beam path into an extraneous light beam, the beam cross section of which along the entire extraneous light beam path between the light source area 21 and the extraneous light trap is more than twice the diameter of the beam of EUV-utilizing light 10 in the collection area 25. This will be explained in more detail further below in connection with some exemplary embodiments.

[0059] Figure 3 shows a further design of a collector 29, which can be used in the projection exposure apparatus 1 instead of the collector 11. Components and features corresponding to those described above with reference to the collector 11 according to Figures 1 and 2 have the same reference numerals and will not be described in detail again.

[0060] The collector 29 has two reflective surface portions 30,31.

[0061] The reflective surface portion 30 of the collector 29 is designed as a planar reflective panel of the same type as the reflective surface 20 of the collector 11. The reflective surface portion 30 has a through opening 22 for the excitation light 23.

[0062] The reflective surface portion 30 is adjoined by a further reflective surface portion 31 of the collector 29, which is designed as a hollow cylindrical reflective surface portion, the inner wall 32 of which is used for diffraction and reflection.

[0063] Both the reflective surface portion 30 and the reflective surface portion 31 have a diffraction grating 24 for the diffraction of the EUV use light 10, as already explained above with reference to the design according to FIG.

[0064] 3 shows, on the one hand, the beam path of a single ray of EUV-embedded light 10, in which the EUV-embedded light 10 is diffracted from the source area 21 towards the collection area 25, and, on the other hand, the beam path of a single ray of extraneous light 27, in which the diffractive structure of the diffraction grating 24 remains ineffective, in which extraneous light 27 is reflected by the reflective surface portions 31, 30. In this case, the extraneous light 27 may be reflected multiple times by the reflective surface portions 30, 31, as shown in FIG. 3. At the point where the extraneous light 27 leaves the beam path of the EUV-embedded light 10 in the region of the collector 29, an extraneous light trap of the same type as extraneous light trap 28 may then be arranged.

[0065] In the meridian cross section according to FIG. 3, the reflecting portions 30, 31 in each case take a minimum angle α of 90° relative to one another in the transition area 33.

[0066] The connecting line 26 represents the axis of rotational symmetry for the hollow cylindrical reflecting surface portion 31 .

[0067] The light source area 21 is within the volume occupied by the hollow cylindrical reflective surface portion 31 .

[0068] Figure 4 shows a further design of collector 34, which can be used in the projection exposure apparatus 1 instead of collector 11. Components and features corresponding to those described above with reference to Figures 1 to 3 have the same reference numerals and will not be described in detail again.

[0069] In addition to the planar reflecting surface portion 30 and the hollow cylindrical reflecting surface portion 31 of the same type as the collector 29, the collector 34 has a rotationally symmetrical frustoconical reflecting surface portion 35, also called a hollow conical reflecting surface portion, in the transition area 33. In the case of the hollow conical reflecting surface portion 35, its inner wall is also used for diffraction and reflection. Furthermore, the hollow conical reflecting surface portion 35 has a diffraction grating 24 on the inside for diffracting the EUV used light 10, but is used reflectively for the external light 27, so that the diffraction grating 24 remains ineffective. This effect of the hollow conical reflecting surface portion 35 is shown in FIG. 4 by two single light rays in each case: one for the EUV used light 10 and the other for the external light 27.

[0070] The reflective surface portions 30, 31, and 35 of the collector 34 reflect the extraneous light 27 along an extraneous light beam path into an extraneous light beam, the beam cross section of which at the intermediate focal plane 12 is indicated by the extent of the surface of the extraneous light trap 35a. The beam cross section of the extraneous light 27 along the entire extraneous light beam path between the light source area 21 and the extraneous light trap 35a is larger than twice the diameter of the EUV used light 10 at the collection area 25. Therefore, the extraneous light 27 is particularly expanded at the intermediate focal plane 12 so that it can be sufficiently removed and separated from the used light 10, for example by absorption in the extraneous light trap 35a, and the used light 10 passes through the through-opening 35b in the extraneous light trap 35a and enters the collection area 25 through the through-opening 35b.

[0071] In the transition area 33, the planar reflective surface portion 30 and the hollow conical reflective surface portion 35 merge into one another at a minimum angle β of 45°. The hollow conical reflective surface portion 35 and the cylindrical reflective surface portion 31 also merge into one another at a minimum angle γ of 45°.

[0072] Figure 5 shows a further design of collector 36, which can be used in the projection exposure apparatus 1 instead of collector 11. Components and features corresponding to those described above with reference to Figures 1 to 4 have the same reference numerals and will not be described in detail again.

[0073] Collector 36 has a reflective surface comprising a first, inner hollow conical reflective surface portion 37 having opening 22 therethrough and a second, outer hollow conical reflective surface portion 38 adjacent to inner reflective surface portion 37 via transition area 33. The minimum angle δ between the two inner reflective surface portions 37, 38 in transition area 33 is approximately 30°.

[0074] The transition area 33 may be designed as a transition edge area, which has a rounded continuous transition between the reflective surface portions 37, 38, which merge with each other via the transition area 33.

[0075] The reflective surface portions 37, 38 have a diffraction grating 24 for diffracting the EUV light 10. The extraneous light 27 is reflected by the reflective surface portions 37, 38 without the diffraction grating 24 having any effect in this case.

[0076] Figure 6 shows a further design of collector 39, which can be used in the projection exposure apparatus 1 instead of collector 11. Components and features corresponding to those described above with reference to Figures 1 to 5 have the same reference numerals and will not be described in detail again.

[0077] The collector 39 has a hollow conical reflecting surface portion 40 which in the meridian section according to Figure 6 makes an angle ε of approximately 45° to the connecting line 26, which represents the axis of rotational symmetry of the reflecting surface portion 40. The reflecting surface portion 40 has a through opening 22 for the excitation light 23.

[0078] Figure 7 shows a further design of collector 41, which can be used in the projection exposure apparatus 1 instead of collector 11. Components and features corresponding to those described above with reference to Figures 1 to 6 have the same reference numerals and will not be described in detail again.

[0079] 3 and 4, the collector 41 has two further planar reflector panels 42, 43 whose panel openings 44, 45 have diameters that increase in an increasing manner and at increasing distances from the reflector panel 30 along a connecting line 26, which represents an axis of rotational symmetry for all three reflector panels 30, 42, 43. Depending on the design of the collector 41, the number of reflector panels may also be two, four, five, or even more. Often the number of reflector panels is less than 20.

[0080] The reflecting panels 30, 42, 43 have a diffraction grating 24 for diffraction of the EUV light 10. The extraneous light 27 is reflected by the reflecting panels 30, 42, 43 without the diffraction grating 24 having an effect in this case.

[0081] Figure 8 shows a further design of a collector 46, which can be used in the projection exposure apparatus 1 instead of the collector 11. Components and features that correspond to those described above with reference to Figures 1 to 7 have the same reference numerals and will not be described in detail again.

[0082] The collector 46 is shown in perspective in FIG. 8, with the viewing direction being substantially opposite to the direction in which the beam of excitation light 23 passes through the through opening 22 .

[0083] In meridional cross section, collector 46 corresponds to collector 29 according to Fig. 3. Instead of cylindrical reflecting surface portion 31 as in collector 29, collector 46 has a total of four planar reflecting surface portions 47, 48, 49, 50 in addition to reflecting surface portion 30. These five planar reflecting surface portions 30 and 47-50 result in collector 46 having a box-shaped or cubic basic form with a free opening towards the viewer in Fig. 8.

[0084] The inner walls of the reflective surface portions 47 to 50 and the reflective surface portion 30 have diffraction gratings 24 for diffracting the EUV light used. The EUV external light is reflected by these inner walls without the respective diffraction gratings 24 having an effect in this case.

[0085] Figure 9 shows a further design of collector 51, which can be used in the projection exposure apparatus 1 instead of collector 11. Components and features corresponding to those described above with reference to Figures 1 to 8 have the same reference numerals and will not be described in detail again.

[0086] The collector 51 has a parabolic reflecting surface 52 in the form of a paraboloid with a vertical circle 53, in whose circular plane 54 there is the light source area 21. The connecting line 26 is perpendicular to the circular plane 54.

[0087] This parabolic shaped reflective surface 52 of the collector 51 has the effect that, after two reflections at the parabolic reflective surface 52, excitation light propagating from the source area 21 in the direction of the reflective surface 52 is reflected back to the source area 21 again, as shown in FIG. 9 with two excitation or foreign light single rays 27. In this way, the excitation light 23 interacts with the source area 21 at least twice, thereby increasing the excitation efficiency of the EUV radiation source 3. Foreign light 27 that is not reflected from the source area 21 in the direction of the reflective surface 52 can be removed by a frustoconical foreign light trap 55. Such a foreign light trap is described in WO 2022 / 002566 A1 (see FIG. 2 therein).

[0088] The path taken by the used light 10 between the light source area 21, the reflecting surface 52 having a diffractive effect for the used light 10, and the collecting area 25 is shown in FIG. 9 by two single rays.

[0089] The reflective surface 52 is designed to reflect the external light 27 along the external light beam path into an external light beam, and the beam cross section of the external light beam along the entire external light beam path between the light source area 21 and the external light trap 55 is larger than twice the diameter of the beam of EUV light 10 in the collection area 25.

[0090] Figure 10 shows a further design of a collector 56, which can be used in the projection exposure apparatus 1 instead of the collector 11. Components and features corresponding to those described above with reference to Figures 1 to 9 have the same reference numerals and will not be described in detail again.

[0091] The collector 56 has an elliptical reflecting surface consisting of two elliptical reflecting surface portions 57, 58. In each case, the first foci of these two elliptical reflecting surface portions 57, 58 are at the source area 21.

[0092] A second focal point 59 of the ellipsoidal reflecting surface portion 57 is at a distance from the light collection area 25 above the connecting line 26 in FIG.

[0093] A second focal point 60 of the second ellipsoidal reflective surface portion 58 is similarly located a fixed distance from the light collection area 25 below the connecting line 26 in FIG.

[0094] The two second foci 59, 60 of the ellipsoidal reflecting surface portions 57, 58 are mirror-symmetric with respect to one another with respect to a plane in which the connecting line 26 lies, which is oriented perpendicular to the plane of the drawing of Figure 10. The collector is rotationally symmetric with respect to this connecting line 26.

[0095] The two ellipsoidal reflective surface portions 57, 58 merge into one another via a transition area 33. At the location of this transition area 33 there may be a through opening corresponding to the through opening 22 for the excitation light 23 in the embodiment described above.

[0096] The transition angle between the two reflective surface portions 57, 58 in the transition area 33 is such that the reflective surface of the collector 56 with the two reflective surface portions 57, 58 is designed as a globally concave surface.

[0097] The two ellipsoidal reflecting surface portions 57, 58 have a diffraction grating 24 for diffracting the used light 10 emanating from the source area 21 onto the collection area 25, as already explained above in connection with the design according to figures 2 to 9. This beam path of the used light 10 is shown in figure 10 by two single rays.

[0098] The diffraction grating 24 has no effect on the extraneous light, and the extraneous light 27 is shifted to two second foci 59, 60 depending on whether it is reflected by the reflective surface portion 57 or 58. These second foci 59, 60 may be assigned to extraneous light traps, as shown in FIG. 10 by a portion of the extraneous light trap 60a. The beam paths of two selected single rays of extraneous light 27 between the light source area 21 and the extraneous light trap 60a are shown by the example in FIG. 10. These extraneous light single rays 27 are shown by dashed lines between the reflective surface portion 57 and the extraneous light trap 60a. The reflective surface portions 57, 58 are designed to reflect the extraneous light 27 into an extraneous light beam along the extraneous light beam path, and the beam cross section of the extraneous light beam along the entire extraneous light beam path between the light source area 21 and the extraneous light trap 60a is greater than twice the beam diameter of the EUV light 10 in the focusing area 25.

[0099] Figure 11 shows a further design of collector 61, which can be used in the projection exposure apparatus 1 instead of collector 11. Components and features that correspond to components and features described above with reference to Figures 1 to 10, and in particular with reference to Figure 10, have the same reference numerals and will not be described in detail again.

[0100] Furthermore, the collector 61 according to Fig. 11 has two ellipsoidal reflecting surface portions 62, 63 which are comparable to the collector 56 according to Fig. 10. In the case of the collector 61, the second focus 59 of the ellipsoidal reflecting surface portion 62 is below the connecting line 26, and the second focus 60 of the further ellipsoidal reflecting surface portion 63 is above the connecting line 26.

[0101] The ellipsoids describing the two ellipsoidal reflecting surface portions 62, 63 of collector 61 on the one hand and the two reflecting surface portions 57, 58 of collector 56 on the other hand are identical in each case and therefore have major and minor axes of the same length and also foci at the same position.

[0102] By reversing the allocation of the second foci to the reflective surface portions, a reflective surface with a partially convex design is obtained in the transition area 33 of the collector 61, in which a through opening for the passage of the excitation light may be arranged, as explained above in connection with the designs of Figures 1 to 9. The reflective surface of the ellipsoidal reflective surface portion is rotationally symmetric about the connecting line 26.

[0103] Using the following considerations, the grating structure of each diffraction grating 24 can be defined using a coordinate system including the coordinates x and z, which is particularly shown in Figures 2, 8, and 9. Figure 12 shows a schematic representation of the parameters used in this discussion.

[0104] The realizable collector reflecting surface portion K is considered to be rotationally symmetric, continuous and bijective, and can therefore be expressed by:

number

number

number

number

[0105] The beam emitted or reflected by the plasma is

number

number

[0106] The diffraction angle α is approximately given by:

number

number

[0107] The equation for a diffraction grating is:

number

number

number

[0108] Equation (6) combines the specific design parameters of the collector surface in k(x) with the location-dependent periodicity T, which allows the location-dependent period to be calculated, thereby defining the structure of the diffraction grating 24 for each collector design.

[0109] In the case of a planar reflecting surface 20 of a collector 11 according to FIG. 2, k(x)=−a applies, where a is the distance between the center of the source area 21 , ie the coordinate origin, and the reflecting surface 20 .

[0110] In the case of the parabolic collector 51 according to FIG. 9, the collector surface is

number

[0111] In the case of collectors 56 and 61 according to FIGS. 10 and 11, the reflecting surface can be described by the following formula:

number

[0112] Depending on the collector design, the smallest angle that two reflective surface portions of the collector's reflective surface that merge with each other through a transition area can make with respect to each other may be greater than 7°.

[0113] Figure 13 shows a further design of a collector 64, which can be used in the projection exposure apparatus 1 instead of the collector 11. Components and features corresponding to those described above with reference to Figures 1 to 12 have the same reference numerals and will not be described in detail again.

[0114] The reflecting surface 65 of the collector 64 consists of an inner spherical reflecting surface portion 66 radially surrounding the connecting line 26 between the source area 21 and the collection area 25, and an outer parabolic reflecting surface portion 67 adjacent to the inner portion. These two reflecting surface portions 66 and 67 are in each case rotationally symmetrical with respect to the connecting line 26. The minimum angle between the two reflecting surface portions 66, 67 in the transition area 33 is approximately 15°.

[0115] Figure 14 shows a further design of a collector 68, which can be used in the projection exposure apparatus 1 instead of the collector 11. Components and features that correspond to those described above with reference to Figures 1 to 13 have the same reference numerals and will not be described in detail again.

[0116] 14, the reflecting surface 69 of the collector 68 is also divided into two reflecting surface portions, in particular an inner reflecting surface portion 70 in the radial region around the connecting line 26 up to the transition area 33, which is designed as an ellipsoidal portion, and a frustoconical reflecting surface portion 71 immediately adjacent to it via the transition area 33. The two reflecting surface portions 70 and 71 are rotationally symmetric about the connecting line 26. The smallest angle between the two reflecting surface portions 70, 71 in the transition area 33 is approximately 30°.

[0117] Figure 15 shows a further design of collector 72, which can be used in the projection exposure apparatus 1 instead of collector 11. Components and features corresponding to those described above with reference to Figures 1 to 14 have the same reference numerals and will not be described in detail again.

[0118] The collector 72 has a reflecting surface 73 which is designed as a whole paraboloid, with rotational symmetry about the connecting line 26. The reflecting surface 73 on which the diffraction grating 24 is mounted is convex.

[0119] Figure 16 shows a further design of a collector 74, which can be used in the projection exposure apparatus 1 instead of the collector 11. Components and features corresponding to those described above with reference to Figures 1 to 15 have the same reference numerals and will not be described in detail again.

[0120] In the case of the collector 74, the entire reflecting surface 75 on which the diffraction grating 24 is mounted is designed as a conical surface that is rotationally symmetric about the connecting line 26. Unlike, for example, the case of the frustoconical reflecting surface 40, the conical surface is not curved about the light source area 21, but in its projection onto the connecting line 26, the cone apex 76 of the reflecting surface 75 is closest to the light source area 21. Instead of the cone apex 76, a truncated cone may also be provided on the collector 74. No point on the reflecting surface 75 is closer to the light source area 21 than the intersection with the connecting line 26 that passes through the reflecting surface 75. In the case of a design of the reflecting surface 75 with a cone apex 76, the cone apex 76 coincides with this intersection point.

[0121] For all of the above-described collector designs 11, 29, 34, 36, 39, 41, 46, 51, 64, 68, 72, and 74, the reflective surfaces or reflective surface portions thereof reflect the external light 27 into an external light beam along the external light beam path, such that the beam cross section of the external light beam along the entire external light beam path after the source area 21 is larger than twice the diameter of the beam of the EUV-based light 10 at the collection area 25. This condition that the beam cross section of the external light beam is larger than twice the diameter of the beam of the EUV-based light 10 at the collection area 25 can be satisfied along the entire external light beam path, for example, between the source area 21 and the respective external light traps (see 35a in FIG. 4 , 55 in FIG. 9 , and 60a in FIG. 10 ).

[0122] Generally, the relationship between the reflectance R of the EUV light 10 on each reflective surface or each reflective surface portion and the angle of incidence is such that the reflectance is greatest at a small angle of incidence close to normal incidence and decreases as the angle of incidence increases.

[0123] The collector designs 29, 34, 36, 56, 61, 64, and 69 described above are examples of composite reflective surfaces in optical structures such that the EUV light reflectivity of these reflective surfaces is greater than if only one type of reflective surface were used, i.e., without the transition area 33.

[0124] With the aid of the projection exposure apparatus 1, an image of at least a part of a reticle in the object field 5 is projected onto an area of ​​a photosensitive layer on a wafer in the image field 8 for the lithographic production of microstructured or nanostructured components, in particular semiconductor components, e.g. microchips. Depending on the design of the projection exposure apparatus 1 as a scanner or stepper, the reticle and the wafer are moved in the y-direction in a time-synchronized manner, either continuously in a scanner operation or stepwise in a stepper operation.

Claims

1. an EUV collector (11; 29; 34; 36; 39; 41; 46; 51; 64; 68; 72; 74) for collecting EUV use light (10) emitted from a light source area (21), Reflective surfaces (20; 30, 31; 30, 31, 35; 37, 38; 40; 30, 42, 43; 30, 47-50; 52; 65; 69; 73; 75), The reflecting surface (20; 30, 31; 30, 31, 35; 37, 38; 40; 30, 42, 43; 30, 47-50; 52; 65; 69; 73; 75), a diffraction grating (24) for the EUV use light (10) is installed, which is designed so that the EUV use light (10) emitted from the source area (21) is diffracted by the diffraction grating (24) towards a collection area (25), The reflecting surfaces (20; 30, 31; 30, 31, 35; 37, 38; 40; 30, 42, 43; 30, 47 to 50; 52; 65; 69; 73; 75) are reflective to the wavelength (λ N ) with a different wavelength (λ F ) into an external light beam along an external light beam path, and after reflection of the external light (27) at the reflective surfaces (20; 30, 31; 30, 31, 35; 37, 38; 40; 30, 42, 43; 30, 47-50; 52; 65; 69; 73; 75), a beam cross section of the external light beam along the external light beam path is greater than twice the diameter of the beam of EUV used light (10) in the collection area (25).

2. An EUV collector (11; 29; 34; 36; 39; 41; 46; 51; 64; 68; 72; 74) as described in claim 1, characterized in that the beam cross section of the extraneous light beam along the entire extraneous light beam path between the light source area (21) and the extraneous light trap (35a; 55; 60a) is larger than twice the diameter of the beam of the EUV used light (10) in the collection area (25).

3. The reflective surface (20; 30, 31; 30, 31, 35; 37, 38; 40; 30, 42, 43; 30, 47-50; 52; 65; 69) is at least partially As a planar reflecting surface (20; 30; 30, 42, 43; 30, 47 to 50), As a parabolic reflecting surface (52; 67), as a rotationally symmetrical frustoconical reflecting surface (35; 37, 38; 40; 71), or As a hollow cylindrical reflecting surface (31) 3. The EUV collector according to claim 1, characterized in that it is designed.

4. 4. EUV collector according to claim 1, characterized in that the reflecting surfaces (20; 30, 31; 30, 31, 35; 37, 38; 40; 30, 42, 43; 52) are designed to be rotationally symmetric about an axis of symmetry (z).

5. 5. EUV collector according to claim 1, characterized in that the reflective surface has at least two reflective surface portions (30, 35; 30, 31, 31; 37, 38; 30, 47-50) which make a minimum angle (α, β, γ, δ, ε) with respect to one another that is greater than 7°.

6. 6. EUV collector according to claim 5, characterized in that the reflecting surface has at least two planar reflecting surface portions (30, 31, 35) which make a minimum angle (β, γ) with respect to each other that is greater than 7°.

7. 7. An EUV collector according to claim 4, wherein the axis of symmetry (z) is oriented perpendicular to the planar reflecting surface (20) or to the planar reflecting surface portion (30; 30, 42, 43), or the axis of symmetry is oriented parallel to the orientation of the reflecting surface portion (31).

8. 8. The EUV collector according to claim 1, wherein the planar reflecting surface (20) or at least planar reflecting surface portions (30, 42, 43) are designed as planar reflecting panels with through openings (22) for excitation light (23).

9. At least one hollow cylindrical reflecting section (31), the inner wall (32) of which is used for reflection and diffraction and which has said diffraction grating (24), and / or 9. The EUV collector according to claim 1, characterized in that at least one hollow conical reflective surface portion (35; 37, 38; 40) has an inner wall used for reflection and diffraction and has said diffraction grating (24).

10. 10. An EUV collector according to any one of claims 1 to 9, comprising the reflecting surface aligned with the source area (21), characterized in that the source area (21) is at the focus of the parabolic reflecting surface portion (52) and / or at the focus of at least one of the ellipsoidal reflecting surface portions (57, 58; 62, 63).

11. an EUV collector (11; 29; 34; 36; 39; 41; 46; 51; 64; 68) for collecting EUV use light (10) emitted from a light source area (21), Reflective surfaces (20; 30, 31; ３０，３１，３５；３７，３８；４０；３０，４２，４３；３０，４７～５０；５２；６５； 69), The reflecting surface (20; 30, 31; ３０，３１，３５；３７，３８；４０； ３０，４２，４３；３０，４７～５０； 52:65;69) is mounted a diffraction grating (24) for the EUV used light (10) that is designed so that the EUV used light (10) emitted from the source area (21) is diffracted by the diffraction grating (24) toward a collection area (25), The reflecting surface (20; 30, 31; 30, 31, 35; 37, 38; 40; 30, 42, 43; 30, 47-50; 52; 65; 69), at least in part, As a planar reflecting surface (20; 30; 30, 42, 43; 30, 47 to 50), As a parabolic reflecting surface (52; 67), as a rotationally symmetrical frustoconical reflecting surface (35; 37, 38; 40; 71), or As a hollow cylindrical reflecting surface (31) Designed, EUV collector (11; 29; 34; 36; 39; 41; 46; 51; 64; 68).

12. an EUV collector (56; 61) for collecting EUV use light (10) emitted from the source area (21), having reflective surfaces (57, 58; 62, 63) that can be aligned with the light source area (21); a diffraction grating (24) for the EUV use light (10) is mounted on the reflecting surfaces (57, 58; 62, 63) so that the EUV use light (10) emitted from the light source area (21) is diffracted by the diffraction grating (24) toward a collecting area (25); The reflecting surfaces (57, 58; 62, 63) a first ellipsoidal reflecting surface portion (57; 62) having a first focal point at said light source area (21) and a further second focal point (60; 59); a second ellipsoidal reflecting surface portion (58; 63) having a first focal point at the light source area (21) and a further second focal point (59; 60); and An EUV collector (56; 61), wherein the two further foci (59, 60) of the two ellipsoidal reflecting surface portions (57, 58; 62, 63) are spaced apart from each other and from the collection area (25).

13. A source-collector module comprising an EUV source (3) according to any one of claims 1 to 12 and an EUV collector (11).

14. An illumination optical unit (4) for an EUV projection exposure apparatus (1) comprising an EUV collector (11) according to any one of claims 1 to 12.

15. 15. A projection exposure apparatus for EUV projection lithography, comprising an EUV light source (3) and an illumination optical unit according to claim 14 for transferring illumination light (10) from the EUV light source (3) to a field (5), and a projection optical unit (7) for projecting an image of the field (5) into an image field (8), wherein a reticle (6 a) having a structure to be projected as an image may be arranged in the field (5).

16. 1. A method for producing microstructured or nanostructured components, comprising: providing a substrate (9a) on which a layer of photosensitive material is at least partially applied; Providing a reticle (6a) having a structure to be projected as an image; - projecting at least a part of the reticle (6a) onto an area of ​​the photosensitive layer of the substrate (9a) with the aid of the projection exposure apparatus according to claim 15; A method comprising:

17. 17. A component produced by the method of claim 16.

Images