Projection optical unit for microlithography and method for producing a structured component

Abstract

The invention relates to a projection optical unit for microlithography and a method for producing a structured component. The projection optical unit for microlithography comprises a plurality of mirrors for guiding imaging light (301, 510, 601, 701, 801) along an imaging beam path from an object field (5) located on an object plane (OP) to an image field (9) located on an image plane (IP), wherein the numerical aperture (NA) has a value greater than 0.5, wherein the plurality of mirrors comprises at least three mirrors for grazing incidence (GI mirrors) which deflect the chief ray of a central object field point at an angle of incidence greater than 45°, wherein the beam from the object field to the image field passes through the projection optical unit (7, 300, 500, 801) in operation. 600, 700, 800) are rotated by different rotation angles in their polarization directions due to geometric polarization rotation, wherein the projection optical unit comprises a first group of reflectors (A) and a second group of reflectors (B), the second group of reflectors being composed of the last two reflectors (Mn‑1, Mn) of the plurality of reflectors on the image side, wherein the linear part in the pupil dependence of the total geometric polarization rotation (|Z3A+Z3B|) of the projection optical unit is less than 20% of the linear part in the pupil dependence of the geometric polarization rotation (|Z3B|) of the second group of reflectors.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from German patent application DE 10 2019 208 961.5 filed on June 19, 2019. The contents of that application are incorporated herein by reference. Technical Field

[0003] The invention relates to a projection optical unit for microlithography and a method for producing a structured component. Background Art

[0004] Microlithography projection exposure systems are used to produce microstructured components, such as integrated circuits or liquid crystal displays (LCDs). Such projection exposure systems comprise an illumination device (illumination optics) and a projection lens (projection optics). During the microlithography process, an image of a mask (reticle) illuminated by the illumination device is projected via the projection lens onto a substrate (e.g., a silicon wafer) coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection lens, thereby transferring the mask structure to the substrate's photosensitive coating.

[0005] To optimize imaging contrast, various methods are known for specifically setting or correcting the polarization distribution in illumination devices or projection lenses. In particular, setting a tangential polarization distribution for high-contrast imaging is known in both illumination devices and projection lenses. "Tangential polarization" (or "TE polarization") is understood to mean a polarization distribution in which the vibration plane of the electric field intensity vector of individual linearly polarized light rays is oriented approximately perpendicular to the radius of the center of the guide pupil. For example, in high-aperture imaging processes, a preferred polarization distribution configuration is one in which the diffraction orders are tangentially polarized in the wafer plane to avoid contrast loss due to so-called vector effects. The term "vector effect," which occurs in high-aperture imaging processes, describes the situation in which, even with the same polarization state, the electric field vector has different directions for different diffraction orders in the image region. This is due to the fact that the p-polarization components (TM components) of the electric field vector are no longer parallel to each other, resulting in polarization-dependent imaging contrast.

[0006] A problem that arises during the operation of projection exposure apparatuses for microlithography is that optical retardations occur in the optical system for various reasons. These retardations can vary depending on the position in the pupil plane and can lead to a loss of contrast and an associated reduction in the performance of the optical system. "Retardation" refers to the difference in the optical path lengths of the orthogonal polarization eigenstates of the Jones pupil, which characterizes the optical system.

[0007] One possible reason for such undesirable optical delays in optical systems is a geometric effect also known as "spin-redirection phase" or "Berry phase." This effect can be traced back to the fact that, in an optical system, the coordinate system for a given polarization state is rotated for skewed beams (i.e., beams that leave the meridian plane from the entry region to the exit region of the optical system). As a result of this rotation of the coordinate system, polarized beams are still rotated about their preferred polarization direction, even if the system lacks an optical rotator and if there is no polarization rotation due to S / P splitting or by a polarizer.

[0008] A quantitative value for the geometric rotation associated with a ray path in an optical system is obtained by projecting the ray path's k vector onto a unit sphere of orientation and computing the solid angle enclosed by the contour (see Tavrov et al., "Method to Evaluate the Geometrical Spin-redirection Phase for a Nonplanar Ray," J. Opt. Soc. Am., 1999, A 16(4), pp. 919-921). In general, the input and output rays of an imaging optical system are not parallel to each other and the contours are not closed. However, Tavrov implicitly links the input and output rays to geodesic lines on the unit sphere of orientation. For imaging systems with parallel image and object planes and non-uniform magnification, it is more appropriate to include the normal to the image plane as an additional point on the direction sphere, thereby linking the input and output rays with two additional geodesics via the image normal. This definition will be used below, also for evaluating systems with small deviations from exact parallelism of the image and object planes, and for evaluating ray paths in optical subsystems that include the image plane.

[0009] As a result of the previously discussed polarization rotation, the initially adjusted preferred polarization distribution (e.g., tangential polarization) is no longer maintained throughout the projection optical unit, resulting in a loss of contrast and an accompanying reduction in the performance of the optical system. This problem is particularly pronounced in optical systems with relatively high numerical apertures (NA) due to the increased angle of incidence of the light beam on the mirrors of the projection optical unit.

[0010] With regard to the prior art, reference is made to WO 2019 / 057803 A1 merely by way of example. Summary of the Invention

[0011] The object of the present invention is to provide a projection optical unit for microlithography and a method for producing a structured component which reduce undesired contrast losses and the attendant performance degradation of the optical system.

[0012] This object is achieved according to the features of the independent claims.

[0013] A projection optical unit for microlithography according to the invention comprises:

[0014] a plurality of mirrors for directing imaging light along an imaging beam path from an object field located in the object plane to an image field located in the image plane, wherein the numerical aperture has a value greater than 0.5;

[0015] wherein the plurality of mirrors comprises at least three mirrors for grazing incidence (GI mirrors) which deflect the chief ray of the central object field point at an angle of incidence greater than 45°;

[0016] wherein light beams of different polarizations passing through the projection optical unit in operation from the object field to the image field are rotated by different rotation angles in their polarization directions due to geometric polarization rotation;

[0017] The projection optical unit comprises a first group of reflectors and a second group of reflectors, the second group of reflectors being composed of the last two reflectors of the plurality of reflectors on the image side, and the linear part in the pupil dependence of the total geometric polarization rotation (|Z3A+Z3B|) of the projection optical unit being less than 20% of the linear part in the pupil dependence of the geometric polarization rotation (|Z3B|) of the second group of reflectors.

[0018] Furthermore, the present invention particularly comprises the concept of configuring a projection optical unit in which, due to a relatively high value of the numerical aperture, the deflected light beam leaving the meridian plane passes through the optical system at a relatively large value of the angle of incidence on the mirror in a specifically targeted manner so that the "first-order part" or "linear part" which increases linearly from the center to the edge of the exit pupil of the above-mentioned rotation of the polarization state due to a geometric effect called "spin reorientation phase" or "Berry phase" is almost eliminated.

[0019] Furthermore, the present invention is based on the following consideration: while the specific design of the last two mirrors on the image side, designated here and hereinafter as the "second group of mirrors (Mn-1, Mn)" or "part B", is essentially predetermined by optical requirements, in particular regarding the numerical aperture (NA) (with regard to the position, orientation and curvature of the mirrors), the design freedom is limited by the remaining mirrors, designated here and hereinafter as the "first group of mirrors (M1 ... Mn-2)" or "part A". Proceeding from this consideration, the present invention particularly includes the concept of configuring the first group of mirrors (M1 ... Mn-2) (i.e., part A) in such a way that the resulting geometric polarization rotation substantially compensates for the geometric polarization rotation in the second group of mirrors (Mn-1, Mn) (i.e., part B). In other words, the "part A" in the projection optical unit is designed (regarding the position, orientation and curvature of its mirrors) so that the resulting linear part in the pupil dependence of the geometric polarization rotation Z3A has substantially equal magnitude but opposite sign as compared to the resulting linear part in the pupil dependence of the geometric polarization rotation Z3B in the "part B" in the second group of mirrors (Mn-1, Mn).

[0020] In the context of the present invention, the order of geometric polarization rotation can be conveniently defined by Zernike polynomials as a function of pupil coordinates x and y in the exit pupil. The first few Zernike polynomials are defined as Z1 = constant, Z2 = y, Z3 = x, Z4 = 2x 2 +2y 2 -1, Z5 = y 2 -x 2 、Z6=2xy、Z7=(3x 2 +3y 2 =-2)*x, etc. Since Z4 and Z5 vanish for symmetry reasons, the at least partial elimination of the "first-order portion" or "linear portion" (i.e., the Z3 term) as described above leaves the Z6 term as the dominant Zernike polynomial. The linear portion of the pupil dependence for the geometric polarization rotation for the first group of mirrors M1 ... Mn-2 (i.e., portion A) mentioned above will be Z3A, while the linear portion of the pupil dependence for the geometric polarization rotation for the second group of mirrors (Mn-1, Mn) (i.e., portion B) will be Z3B. The above criterion can then be written as |Z3A+Z3B|<0.2*|Z3B|.

[0021] According to an embodiment, the linear part of the pupil dependence of the geometric polarization rotation (|Z3A+Z3B|) of the entire projection optical unit is less than 15%, in particular 5%, of the linear part of the pupil dependence of the geometric polarization rotation (|Z3B|) of the second group of mirrors (Mn-1, Mn).

[0022] According to an embodiment, for all beams imaging the center of the object field to the center of the image field, the rotation angle is less than 35°*NA 4.5 By requiring an NA-dependent upper limit for the rotation angle, this criterion takes into account the fact that with higher values ​​of the numerical aperture (NA), the effect of the geometric polarization rotation increases mainly due to the larger angles of incidence of the light beam on the mirrors of the projection optics.

[0023] The invention also relates to a projection optical unit for microlithography, comprising:

[0024] a plurality of mirrors for directing imaging light along an imaging beam path from an object field located in the object plane to an image field located in the image plane, wherein the numerical aperture (NA) has a value greater than 0.5;

[0025] wherein the plurality of mirrors comprises at least three mirrors for grazing incidence (GI mirrors) which deflect the chief ray of the central object field point at an angle of incidence greater than 45°;

[0026] wherein light beams of different polarizations passing through the projection optical unit in operation from the object field to the image field are rotated by different rotation angles in their polarization directions due to geometric polarization rotation;

[0027] For all beams that image the center of the object field to the center of the image field, the rotation angle is less than 35°*NA 4.5 .

[0028] According to an embodiment, for all beams imaging the center of the object field to the center of the image field, the rotation angle is less than 30°*NA 4.5 , more specifically less than 25°*NA 4.5 .

[0029] According to an embodiment, the image-side numerical aperture (NA) has a value greater than 0.6, in particular greater than 0.7.

[0030] According to an embodiment, for all light beams imaging the center of the object field into the center of the image field, the rotation angle is smaller than 7°, in particular smaller than 5°, more particularly smaller than 3°.

[0031] According to an embodiment, the imaging beam path from the center of the object field through a position of a pupil plane having relative pupil coordinates (-1,0) or (1,0) in the exit pupil, corresponding to the intersection of the x-axis with the edge of the pupil, to the center of the image field has a NA of less than 5°* 4.5 The geometric polarization rotation.

[0032] According to an embodiment, the geometric polarization rotation averaged over all imaging beam paths in the pupil plane within the dipole at 20% pupil filling rate is less than 5°*NA4.5 .

[0033] According to an embodiment, the circumferential distribution of the rotation angles in a pupil plane of the projection optical unit exhibits at least four zero crossings of the rotation angles.

[0034] In the context of the previously described embodiments, the present invention is also based on the consideration that a rotation of the polarization state (i.e., the amount by which a polarized light beam is rotated about its preferred polarization direction) is generally acceptable (and does not lead to a degradation of the performance of the optical system) as long as relatively low values ​​of polarization rotation are provided in those pupil regions that are actually optically used in the polarized illumination setup. Since commonly used polarized illumination setups (such as dipole or quadrupole setups) may include relatively small illumination poles, in particular in relatively outer regions of the illumination pupil plane, the aforementioned consideration means that relatively high values ​​of polarization rotation are acceptable in regions that do not belong to said illumination poles.

[0035] Figure 9 a to Figure 9 c shows an exemplary embodiment where the desired polarized illumination setting is a horizontal dipole illumination setting 910 with y polarization ( Figure 9 a) Vertical dipole illumination with x-polarization set 920 ( Figure 9 b), or a quadrupole illumination setup 930 with a quasi-tangential polarization distribution ( Figure 9 c), namely having a polarization distribution in which the oscillation direction of the electric field vector is at least approximately perpendicular to a radius extending at the optical system axis (which extends in the z direction with respect to the drawn coordinate system).

[0036] Starting from the considerations mentioned previously, the invention comprises in particular the concept of configuring a projection optical unit in which, due to a relatively high value of the numerical aperture, the deflected light beam leaving the meridian plane passes through the optical system at a relatively large value of the angle of incidence on the mirror in a specifically targeted manner so that the "linear part" (which may also be indicated as "first-order part") that increases linearly from the center to the edge of the pupil plane of the rotation of the polarization state mentioned above due to a geometric effect referred to as "spin reorientation phase" or "Berry phase" is almost eliminated.

[0037] By at least partially eliminating the linear portion of the polarization rotation described previously, the present invention specifically takes into account the fact that since in such a polarization illumination setting only those regions of the pupil which are located at the outer edge of the pupil and in which the rotation angle of the polarization direction is relatively high are optically used in the operation of the projection optical unit, it is only this linear or first-order portion of the polarization rotation (i.e. the portion which increases linearly across the pupil) which is particularly harmful or unfavorable for achieving the maximum extent for general polarization illumination settings (such as dipole settings or quadrupole settings).

[0038] As a further consequence of the (at least partial) elimination of the linear or first-order portion of the polarization state rotation mentioned above, only the higher-order portion of the geometric rotation of the polarization state remains. Besides the linear terms, the two lowest-order terms are Z5 and Z6, with Z5 being absent at the center of the object field due to the symmetry of the system. Following the elimination of the linear terms, Z6 becomes dominant.

[0039] For general lighting settings (such as dipole or quadrupole settings, see Figure 9 a to Figure 9 c) The polarization rotation is particularly small only in the region of the illumination pole in the illumination pupil, while the relatively high values ​​of polarization rotation present in other regions of the illumination pupil are not optically used and can only be ignored.

[0040] In other words, the present invention comprises in particular the concept of at least partially eliminating the first order part of the geometric polarization rotation (increasing linearly across the pupil) and thereby leaving only the higher order part of the polarization rotation, which is particularly advantageous for general polarized illumination settings by providing only relatively small rotation angles in the relevant illuminated (=optically used) pupil region.

[0041] The concepts described above are not limited to Figure 9 a to Figure 9 c). In other words, for any other illumination setting, the projection optical unit can also be configured so that the amount of polarization rotation is only particularly small in the optically used area. Furthermore, the concepts described above are not limited to polarized illumination settings. In other words, for unpolarized illumination settings, eliminating or reducing geometric polarization rotation is also generally desirable and can be advantageously achieved according to the present invention.

[0042] The invention also relates to a projection optical unit for microlithography, comprising:

[0043] a plurality of mirrors for directing imaging light along an imaging beam path from an object field located in an object plane that creates an image field located in an image plane, wherein the numerical aperture (NA) has a value greater than 0.5;

[0044] wherein the plurality of mirrors comprises at least three mirrors for grazing incidence (GI mirrors) which deflect the chief ray of the central object field point at an angle of incidence greater than 45°;

[0045] wherein light beams of different polarizations passing through the projection optical unit in operation from the object field to the image field are rotated by different rotation angles in their polarization directions due to geometric polarization rotation;

[0046] Therein, a circumferential distribution of the rotation angle in a pupil plane of the projection optical unit exhibits at least four zero crossings of the value of the rotation angle.

[0047] According to an embodiment, the circumferential distribution of the rotation angles in the exit pupil of the projection optical unit exhibits a zero crossing within 30° of each of the positive and negative x-axis.

[0048] According to an embodiment, the circumferential distribution of the rotation angles in the exit pupil of the projection optical unit exhibits a zero crossing within 10° of each of the positive and negative y-axis.

[0049] Furthermore, the present invention relates to an optical system comprising the imaging optical unit as described above; and an illumination optical unit for illuminating an illumination field in which an object field is arranged.

[0050] Furthermore, the present invention relates to a projection exposure apparatus comprising the optical system as described above and an EUV light source for producing imaging light.

[0051] Furthermore, the present invention relates to a method for producing a structured component, comprising the following method steps:

[0052] Provide reticle masters and wafers;

[0053] Projecting the structure on the reticle onto the photosensitive layer of the wafer with the aid of a projection exposure apparatus as described above; and

[0054] Structured components are produced by fabricating microstructures or nanostructures on wafers.

[0055] Further embodiments of the invention can be inferred from the description and the dependent claims.

[0056] The invention is explained in more detail hereinafter based on exemplary embodiments depicted in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In the figure:

[0058] Figure 1 A schematic diagram showing a projection exposure apparatus for EUV microlithography;

[0059] Figure 2a Display can be based on Figure 1 Schematic side view of a projection optical unit for use in an exposure apparatus of , wherein for the purpose of illustrating the imaging beam path between the object field and the image field, the mirror body is illustrated without a holder and with zero thickness;

[0060] Figure 2b The display depends on the relative pupil coordinates. Figure 2a Distribution of rotation angles of polarization directions of polarized light of a projection optical unit;

[0061] Figure 3a Display can be based on Figure 1A schematic side view of a further embodiment of a projection optical unit for use in a projection exposure apparatus;

[0062] Figure 3b against Figure 3a , showing the distribution of rotation angles due to geometric polarization rotation;

[0063] Figures 4a to 8b side views showing further embodiments of the projection optical unit or respectively the distribution of the rotation angles due to the geometric polarization rotation; and

[0064] Figure 9 a to Figure 9 cDisplay Figure 1 Typical exemplary polarized illumination settings used in projection exposure apparatuses of FIG. DETAILED DESCRIPTION

[0065] in accordance with Figure 1 The microlithography projection exposure device 1 has a light source 2 for illumination light or imaging light 3. The light source 2 is an EUV light source, which produces light in a wavelength range of, for example, between 5 nm and 30 nm, in particular between 5 nm and 15 nm. The light source 2 may be a plasma-based light source (laser-produced plasma (LPP), gas-discharge produced plasma (GDP)), or a synchrotron-based light source, such as a free electron laser (FEL). In particular, the light source 2 may be a light source with a wavelength of 13.5 nm or a light source with a wavelength of 6.9 nm. Other EUV wavelengths are also possible. In general, for the illumination light 3 guided in the projection exposure device 1, even arbitrary wavelengths are possible, such as visible light wavelengths or other wavelengths that may be used in microlithography (e.g. DUV, deep ultraviolet light), and suitable laser light sources and / or light-emitting diode (LED) light sources (e.g. 365 nm, 248 nm, 193 nm, 157 nm, 129 nm, 109 nm) may be used. The beam path of the illumination light 3 is in Figure 1 Very schematically depicted.

[0066] The illumination optics 4 serves to guide the illumination light 3 from the light source 2 to an object field 5 in an object plane OP. Using the projection or imaging optics 7, the object field 5 is imaged with a predetermined reduction ratio into an image field 9 in an image plane IP.

[0067] In order to facilitate the description of various embodiments of the projection exposure apparatus 1 and the projection optical unit 7, a Cartesian xyz coordinate system is indicated in the figures, from which the respective positional relationships of the components illustrated in the figures are apparent. Figure 1 , the x-direction extends perpendicularly to the plane of the figure into the figure. The y-direction extends towards the right, while the z-direction extends downwards. In the projection optical unit 7, the object field 5 and the image field 9 may have a bent or curved embodiment, and in particular, an embodiment shaped like a partial ring. The basic form of the marginal contour of the object field 5 or the image field 9 has a corresponding bend. Alternatively, the object field 5 and the image field 9 may be implemented in a rectangular shape. The object field 5 and the image field 9 have an x / y aspect ratio greater than 1. Therefore, the object field 5 has a longer object field dimension in the x-direction and a shorter object field dimension in the y-direction.

[0068] In accordance with Figure 1 In the embodiment of the projection optical unit 7, the image plane IP is arranged parallel to the object plane OP. In this case, the object being imaged is a portion of a reflection mask 13, also called a reticle, which coincides with the object field 5. The reticle 13 is carried by a reticle holder 14. The reticle holder 14 is displaced relative to the object field 5. Imaging by the projection optical unit 7 is performed onto the surface of a substrate in the form of a wafer 15 carried by a wafer holder 16. The wafer holder 16 is displaced relative to the image field 9.

[0069] Figure 1 Schematic illustration of a ray beam 8 of the illumination light 3 entering the projection optical unit 7 between the reticle 13 and the projection optical unit 7, and a ray beam 8 of the illumination light 3 emerging from the projection optical unit 7 between the projection optical unit 7 and the wafer 15. The numerical aperture (NA) of the projection optical unit 7 on the image field side is Figure 1 Not reproduced to scale.

[0070] The projection exposure apparatus 1 is of the scanner type. Both the reticle 13 and the wafer 15 are scanned in the y-direction during operation of the projection exposure apparatus 1. A stepper type of projection exposure apparatus 1 is also possible, in which the reticle 13 and the wafer 15 are shifted stepwise in the y-direction between individual exposures of the wafer 15. These shifts are performed by appropriate actuation of respective shift drives (not shown).

[0071] Figure 2a A projection optics unit 200 according to a first embodiment of the invention is shown in a side view. Figure 2a The plane of the diagram is parallel to the plane corresponding to Figure 1 The beam path of imaging light 201 includes a principal ray 202 at the central object field point, and further individual rays 203 and 204, aperture or coma rays, which define the edge of the beam path in the yz plane, also known as the meridian plane. The extent of the imaging beam path of imaging light 201 between the object field in object plane OP and the image field in image plane IP is illustrated. Furthermore, the approximate position of pupil plane PP is illustrated.

[0072] in accordance with Figure 2a The projection optical unit 200 has a total of eleven mirrors, which are sequentially numbered from “ M1 ” to “ M11 ” in the order of the beam path of the imaging light 201 proceeding from the object field. Figure 2a The mirror bodies of the mirrors M1 to M11 are illustrated in a cross-section through the projection optical unit 200. These mirror bodies carry mirror reflective surfaces for reflecting the imaging light 201. Starting from the object field in the object plane OP, the chief ray 202 comprises a chief ray angle of 5.5° with respect to the normal to the object plane OP. Other such chief ray angles, for example, in the range between 3° and 8° are also possible.

[0073] in accordance with Figure 2a The projection optical unit 200 has an image side numerical aperture (NA) of 0.75. For example, other image side numerical apertures in the range of 0.4 to 0.9 are also possible.

[0074] In accordance with Figure 2a In the case of a projection optical unit 200 of FIG. 1 , the mirrors M1 , M10 and M11 are implemented as NI (= “normal incidence”) mirrors, i.e. as mirrors on which the imaging light 201 is incident at an angle of incidence of less than 45°. Figure 2a The projection optical unit 200 therefore has three N1 mirrors M1 , M10 and M11 .

[0075] The mirrors M2 to M9 are GI (grazing incidence) mirrors, i.e. mirrors on which the illumination light 201 is incident at an angle of incidence greater than 45°, in particular greater than 60°. The typical angle of incidence of the individual rays 203, 204 of the imaging light 201 on the mirrors M2 to M9 for grazing incidence may be in the range of 80°. In general, according to Figure 2a The projection optical unit 200 has exactly eight mirrors M2 to M9 for grazing incidence. The mirrors M2 to M8 reflect the imaging light 201 in such a way that the reflection angles of the individual rays at the corresponding mirrors M2 to M8 add up. Therefore, in addition to the effects which influence the imaging properties of the projection optical unit 200, the mirrors M2 to M8 all have the same direction of the mirror deflection effect, and the deflection effect with respect to the chief ray 202 is added up for each mirror M2 to M8. These mirrors M2 to M8 can also be designated as "basic GI mirrors". With regard to the deflection effect of the basic GI mirrors M2 to M8, the mirror M9 is arranged such that its deflection effect with respect to the chief ray 202 acts in a subtractive manner. The projection optical unit 200 has exactly one such mirror M9 which acts in a subtractive manner, which is the last GI mirror in the imaging beam path of the projection optical unit 200 upstream of the image field.

[0076] Each of the mirrors M2 to M9 for grazing incidence has a relatively large absolute value for its radius, i.e., it has a relatively small deviation from a planar surface. Each of these mirrors M2 to M9 for grazing incidence has a relatively weak refractive power, i.e., a lower beam-forming effect than a mirror with a generally concave or convex shape. The mirrors M2 to M9 contribute to the correction of specific imaging aberrations, and in particular to the correction of local imaging aberrations. The mirrors M1 to M11 carry a coating that optimizes the reflectivity of the mirrors M1 to M11 for the imaging light 201. This can be a single-layer ruthenium coating or a multilayer coating, in which the uppermost layer in each case is made of, for example, ruthenium. Coatings comprising, for example, a molybdenum or ruthenium layer can be used in the case of the GI mirrors M2 to M9. The highly reflective layers of the mirrors M1, M10, and M11 for normal incidence can be configured as a multilayer, in which successive layers can be made of different materials. Layers of alternative materials can also be used. A typical multilayer coating can have fifty double layers, each made of a molybdenum layer and a silicon layer. These may contain additional separating layers made of, for example, carbon (C), boron carbide (B4C) and may be terminated by a protective layer or protective layer system towards the vacuum.

[0077] Figure 2a The reflector of the projection optical unit 200 is implemented as a free-form surface, which cannot be described by a rotationally symmetric function but is described by the following free-form surface equation:

[0078]

[0079] Z is the sag of the free-form surface at point x, y, where x 2 +y 2 =r 2 Here, r is the distance from the reference axis (x=0, y=0) of the free surface equation. In the free surface equation (1), C1, C2, C3... denote the coefficients of the x and y powers of the free surface series expansion. In the case of a conical base area, c x 、c y is a constant corresponding to the vertex curvature of the corresponding aspheric surface. Therefore, c x =1 / Rx and c y =1 / Ry applies. x and k y Each corresponds to the conic constant of the corresponding aspheric surface. Therefore, equation (1) describes a biconical freeform surface.

[0080] exist Figure 2a In the projection optical unit 200, the optical design data of the reflective surfaces of the reflectors M1 to M11 can be obtained from Tables 1 to 5. Table 1 provides several basic data of the design data of the projection optical unit 200. Table 2 indicates the vertex radius (Radius) of the optical surface of the optical component. x、Radius y ) and refractive power value (Power x 、Power y Negative radius values ​​indicate that the curve is concave towards the incident illumination at the intersection of the corresponding surface and the considered plane (xz plane, yz plane) (which is spanned by the surface normal at the vertex with the corresponding curvature (x, y) direction). x 、Radius y May have distinct signs. Each vertex at the optical surface is defined as the vertex along the symmetry plane x = 0 (i.e. Figure 2a The refractive power at the vertex is the point of incidence of the guided ray traveling from the center of the object field to the image field. x 、Power y Defined as:

[0081]

[0082]

[0083] Here, AOI indicates the angle of incidence of the guided ray with respect to the surface normal.

[0084] Table 3 shows the decentring (position and angle) of the corresponding mirror surfaces and the object field, aperture stop, and image field relative to the surface normal to the object field in the object plane OP, the surface normal being at the center of the object plane OP. Table 4 shows the free form coefficients of the surfaces. Table 5 shows the coordinates of the aperture stop edge.

[0085] As already discussed in the introduction to the present application, for a deflected beam leaving the meridian plane and passing through the projection optical unit from the entry region to the exit region due to the geometric effect of "spin reorientation phase" or "Berry phase", the undesired optical delay is Figure 2a occurs in the projection optical unit 200, resulting in that if no appropriate countermeasures are taken, the initially adjusted polarization distribution (such as the tangential polarization distribution) will not be maintained before the image plane or the wafer plane and the relative losses lead to a degradation of the optical performance of the projection exposure equipment.

[0086] Figure 2b represents the image displayed across the exit pupil (defined as the aperture stop at the image field side of the optical system) and in the Figure 2a A diagram showing the values ​​of the rotation angle due to this geometric polarization rotation in relative pupil coordinates obtained for an embodiment of the invention. For the relative pupil coordinate (1,0), a rotation angle for this geometric polarization rotation with a value of 16.45° is obtained. Furthermore, the circumferential distribution of the rotation angle in the pupil plane of the projection optical unit exhibits four zero crossings of the values ​​of the rotation angle.

[0087] Figure 3a An embodiment of a projection optical unit 300 according to the invention is shown, which can be used to replace Figure 1 The projection optical unit 7 in the projection exposure apparatus 1 of FIG. The principle design of the projection optical unit 300 is similar to Figure 2a The projection optical unit 200 is similar to the projection optical unit 200, in particular with respect to the number of GI or NI mirrors, respectively. Figure 2a Components already explained are denoted by the same reference numerals and are not discussed again in detail.

[0088] exist Figure 3a In the projection optical unit 300, the optical design data of the reflective surface of the reflector can be obtained from Tables 6 to 10. Figure 3a In the projection optical unit 300, the optical design data of the reflective surfaces of the reflectors M1 to M11 can be obtained from Tables 6 to 10. Table 6 provides several basic data of the design data of the projection optical unit 300. Table 7 indicates the vertex radius (Radius) of the optical surface of the optical component. x 、Radius y ) and refractive power value (Power x 、Power y Table 8 shows the decentering (position and angle) of the corresponding mirror surfaces and the object field, aperture stop, and image field relative to the surface normal to the object field in the object plane OP, the surface normal being at the center of the object plane OP. Table 9 shows the free form coefficients of the surfaces. Table 10 shows the coordinates of the aperture stop edge.

[0089] Figure 3b Represents a display spanning the exit pupil and in relative pupil coordinates (the aforementioned coordinates are 0 at the center of the exit pupil and 1 at the outer edge of the exit pupil) due to the Figure 3a A diagram shows the distribution of the rotation angles resulting from the geometric polarization rotation from the entry region to the exit region of the projection optical unit 300 according to an embodiment of the present invention. For the relative pupil coordinate (1,0), a rotation angle with a value of 0.95° is achieved. Tables summarizing the rotation angles and the corresponding values ​​for the criterion |Z3A+Z3B|<0.2*|Z3B| discussed above are provided at the end of the description as Tables 36 and 37, respectively.

[0090] Furthermore, the circumferential distribution of the rotation angle in the pupil plane of the projection optical unit exhibits four zero crossings of the value of the rotation angle. More specifically, the circumferential distribution of the rotation angle in the pupil plane of the projection optical unit 300 exhibits zero crossings on both the positive and negative x-axes, and on both the positive and negative y-axes.

[0091] Available from Figure 3bThe values ​​of the rotation angle are particularly low for the relative pupil coordinates (-1,0) and (1,0) (i.e. in the "three o'clock" and "nine o'clock" regions of the exit pupil), whereas relatively high values ​​of about 6° of rotation angle are obtained for other regions (i.e. at half past one and half past ten of the exit pupil). However, considering Figure 1 The typical polarized illumination setup used in projection exposure equipment looks like Figure 9 a to Figure 9 As schematically shown in c, it can be seen that the undesired polarization rotation achieved is kept low only for the optically used area of ​​the pupil (i.e. the illumination pole), while the relatively large values ​​of the rotation angles obtained for other areas of the pupil correspond to unused areas and therefore have no negative impact on the optical performance of the system.

[0092] Figure 4a A further embodiment of a projection optical unit 400 according to the present invention is shown, which can be used to replace Figure 1 The projection optical unit 7 in the projection exposure apparatus 1. Figure 4a The optical design data of the reflective surface of the reflector in the projection optical unit 400 can be obtained from Tables 11 to 15. Table 11 provides several basic data of the design data of the projection optical unit 400. Table 12 indicates the vertex radius (Radius) of the optical surface of the optical component. x 、Radius y ) and refractive power value (Power x 、Power y Table 13 shows the decentering (position and angle) of the corresponding mirror surfaces and the object field, aperture stop, and image field relative to the surface normal to the object field in the object plane OP, the surface normal being at the center of the object plane OP. Table 14 shows the free form coefficients of the surfaces. Table 15 shows the coordinates of the aperture stop edge.

[0093] in accordance with Figure 4a The projection optical unit 400 has a total of eight mirrors, which are numbered sequentially from M1 to M8 in the order of the beam path of the imaging light proceeding from the object field. Figure 4a In the case of the projection optical unit 400, the mirrors M1, M4, M7 and M8 are implemented as normal incidence mirrors as defined above. Figure 4a The projection optical unit 400 thus has four normal incidence mirrors M1, M4, M7 and M8. The mirrors M2, M3, M5 and M6 are mirrors for grazing incidence of the illumination light as defined above. The typical angle of incidence of the individual rays of the imaging light 401 on the mirrors for grazing incidence may be in the range of 80°. Overall, according to Figure 4a The projection optical unit 400 has exactly four mirrors M2, M3, M5 and M6 for grazing incidence.

[0094] Figure 4b Represents a display spanning the exit pupil and in relative pupil coordinates (the coordinates are 0 at the center of the exit pupil and 1 at the outer edge of the exit pupil) due to Figure 4a Graph showing the distribution of the rotation angle resulting from the geometric polarization rotation from the entry region to the exit region of the projection optical unit 400. For the relative pupil coordinate (1,0), a rotation angle with a value of 7.03° is achieved. Furthermore, the circumferential distribution of the rotation angle in the pupil plane of the projection optical unit exhibits four zero crossings of the rotation angle value.

[0095] Figure 5a A further embodiment of a projection optical unit 500 according to the invention is shown, which can be used to replace Figure 1 The projection optical unit 7 in the projection exposure apparatus 1 corresponds to the above Figure 4a Components already explained are denoted by the same reference numerals and are not discussed again in detail.

[0096] Principle design of projection optical unit 500 and Figure 4a The projection optical unit 400 is similar, in particular with regard to the number of GI or NI mirrors, respectively. Figure 5a The optical design data of the reflective surface of the reflector in the projection optical unit 500 can be obtained from Tables 16 to 20. Table 16 provides several basic data of the design data of the projection optical unit 500. Table 17 indicates the vertex radius (Radius) of the optical surface of the optical component. x 、Radius y ) and refractive power value (Power x 、Power y Table 18 shows the decentering (position and angle) of the corresponding mirror surfaces and the object field, aperture stop, and image field relative to the surface normal to the object field in the object plane OP, with the surface normal being at the center of the object plane. Table 19 shows the free form coefficients of the surfaces. Table 20 shows the coordinates of the aperture stop edge.

[0097] Figure 5b Represents a display spanning the exit pupil and in relative pupil coordinates (the coordinates are 0 at the center of the exit pupil and 1 at the outer edge of the exit pupil) due to Figure 5a Graph showing the distribution of the rotation angles resulting from the geometric polarization rotation from the entry region to the exit region of the projection optical unit 500 according to an embodiment of the present invention. For the relative pupil coordinate (1,0), a rotation angle with a value of 1.55° is achieved. Furthermore, Figure 5b The diagram of shows that the values ​​of the rotation angle are particularly low for the relative pupil coordinates (−1,0) and (1,0), ie in the “three o’clock” and “nine o’clock” regions of the exit pupil.

[0098] The circumferential distribution of the rotation angle in the pupil plane of the projection optical unit exhibits four zero crossings of the value of the rotation angle. More specifically, the circumferential distribution of the rotation angle in the pupil plane of the projection optical unit 500 exhibits zero crossings close to (i.e., within 10°) the circumference of the positive and negative x-axes, and also exhibits zero crossings on the positive and negative y-axes.

[0099] Comparatively, higher values ​​of about (4-6)° rotation angle are obtained for the other regions (i.e., 1:30 and 10:30 of the pupil). However, as discussed above, considering Figure 1 The typical polarized illumination setup used in projection exposure equipment looks like Figure 9 a to Figure 9 As schematically shown in c, it can be seen that the undesired polarization rotation achieved is kept low only for the optically used area of ​​the pupil (i.e. the illumination pole), while the relatively large values ​​of the rotation angles obtained for other areas of the pupil correspond to unused areas and therefore have no negative impact on the optical performance of the system.

[0100] FIG6 shows a further embodiment of a projection optical unit 600. Figure 6a The optical design data of the reflective surface of the reflector in the projection optical unit can be obtained from Tables 21 to 25. Table 21 provides several basic data of the design data of the projection optical unit 600. Table 22 indicates the vertex radius (Radius) of the optical surface of the optical component. x 、Radius y ) and refractive power value (Power x 、Power y Table 23 shows the decentering (position and angle) of the corresponding mirror surfaces and the object field, aperture stop, and image field relative to the surface normal to the object field in the object plane OP, with the surface normal being at the center of the object plane. Table 24 shows the free form coefficients of the surfaces. Table 25 shows the coordinates of the aperture stop edge.

[0101] in accordance with Figure 6a The projection optical unit 600 has a total of nine mirrors, which are numbered sequentially from M1 to M9 in the order of the beam path of the imaging light proceeding from the object field. Figure 6a In the case of a projection optical unit, the mirrors M1, M8 and M9 are implemented as normal incidence mirrors, that is, mirrors on which the imaging light 601 is incident at an incident angle of less than 45°. Figure 6a The projection optical unit 600 thus has three normal incidence mirrors M1, M8 and M9. The mirrors M2 to M7 are mirrors for grazing incidence of the illumination light as defined above. The general angle of incidence of the individual rays of the imaging light 601 on the mirrors M2 to M7 for grazing incidence is in the range of 80°. Overall, according to Figure 6a The projection optical unit 600 has exactly six mirrors M2 to M7 for grazing incidence.

[0102] Figure 6b Represents a display spanning the exit pupil and in relative pupil coordinates (the coordinates are 0 at the center of the exit pupil and 1 at the outer edge of the exit pupil) due to Figure 6a Graph of the distribution of the rotation angle caused by the geometric polarization rotation from the entry region to the exit region of the projection optical unit 600. For the relative pupil coordinate (1,0), a rotation angle with a value of 2.76° is achieved.

[0103] Furthermore, the circumferential distribution of the rotation angle in the pupil plane of the projection optical unit exhibits four zero crossings of the value of the rotation angle. More specifically, the circumferential distribution of the rotation angle in the pupil plane of the projection optical unit 600 exhibits zero crossings within 30° of the positive and negative x-axes, and within 10° of the positive and negative y-axes, respectively.

[0104] Figure 7a A further embodiment of the projection optical unit 700 is shown. Figure 7a The optical design data of the reflective surface of the reflector in the projection optical unit can be obtained from Tables 26 to 30. Table 26 provides several basic data of the design data of the projection optical unit 700. Table 27 indicates the vertex radius (Radius) of the optical surface of the optical component. x 、Radius y ) and refractive power value (Power x 、Power y Table 28 shows the decentering (position and angle) of the corresponding mirror surfaces and the object field, aperture stop, and image field relative to the surface normal to the object field in the object plane OP, with the surface normal being at the center of the object plane. Table 29 shows the free form coefficients of the surfaces. Table 30 shows the coordinates of the aperture stop edge.

[0105] In accordance with Figure 7a In the case of the projection optical unit 700, the mirrors M1, M9 and M10 are implemented as NI mirrors as defined above. Figure 7a The projection optical unit 700 thus has three NI mirrors M1, M9 and M10. The mirrors M2 to M8 are GI mirrors as defined above. Figure 7a The projection optical unit 700 has exactly seven mirrors M2 to M8 for grazing incidence.

[0106] Figure 7b Represents a display spanning the exit pupil and in relative pupil coordinates (the coordinates are 0 at the center of the exit pupil and 1 at the outer edge of the exit pupil) due to Figure 7a A diagram of the distribution of the rotation angles resulting from the geometric polarization rotation from the entry region to the exit region of the projection optical unit 700 is provided. A rotation angle having a value of less than 0.01° is achieved relative to the pupil coordinate (1,0). Furthermore, the circumferential distribution of the rotation angles in the pupil plane of the projection optical unit exhibits four zero crossings of the values ​​of the rotation angles. More specifically, the circumferential distribution of the rotation angles in the pupil plane of the projection optical unit 700 exhibits zero crossings within 30° on the positive and negative x-axis, respectively, and also within 10° on the positive and negative y-axis, respectively.

[0107] Figure 8a A further embodiment of the projection optical unit 800 is shown. Figure 8a The optical design data of the reflective surface of the reflector in the projection optical unit can be obtained from Tables 31 to 35. Table 31 provides several basic data of the design data of the projection optical unit 800. Table 32 indicates the vertex radius (Radius) of the optical surface of the optical component. x 、Radius y ) and refractive power value (Power x 、Power y Table 33 shows the decentering (position and angle) of the corresponding mirror surfaces and the object field, aperture stop, and image field relative to the surface normal to the object field in the object plane OP, with the surface normal being at the center of the object plane. Table 34 shows the free form coefficients of the surfaces. Table 35 shows the coordinates of the aperture stop edge.

[0108] Principle design of projection optical unit 800 and Figure 4a The projection optical unit 400 or Figure 5a The projection optical unit 800 is similar to the projection optical unit 500, in particular with regard to the number of GI or NI mirrors, respectively. However, the projection optical unit 800 has a numerical aperture of NA=0.55.

[0109] Figure 8b Represents a display spanning the exit pupil and in relative pupil coordinates (the coordinates are 0 at the center of the exit pupil and 1 at the outer edge of the exit pupil) due to Figure 8a A diagram of the distribution of the rotation angles resulting from the geometric polarization rotation from the entry region to the exit region of the projection optical unit 800 according to an embodiment of the present invention. A rotation angle having a value of less than 0.01° is achieved relative to the pupil coordinate (1,0). Furthermore, the circumferential distribution of the rotation angles in the pupil plane of the projection optical unit exhibits four zero crossings of the values ​​of the rotation angles. More specifically, the circumferential distribution of the rotation angles in the pupil plane of the projection optical unit 800 exhibits zero crossings on both the positive and negative x-axis, as well as on both the positive and negative y-axis.

[0110] Table 36

[0111]

[0112] As can be seen from Table 36, the criterion |Z3A+Z3B|<0.2*|Z3B| for Figure 3a 、 Figure 5a 、 Figure 6a 、 Figure 7a and Figure 8a As already discussed before, this means that the resulting geometric polarization rotation in the first part A (the first group comprising mirrors (M1 ... Mn-2)) will substantially compensate for the geometric polarization rotation in the part B (the second group comprising mirrors (Mn-1, Mn)). Furthermore, even in Figure 2a and Figure 4a In the embodiment of , a significant improvement with respect to this compensation is achieved compared to the prior art according to WO 2019 / 057803 A1.

[0113] Table 37

[0114]

[0115] Even though the present invention has been described based on specific embodiments, numerous variations and alternative embodiments will be apparent to those skilled in the art, for example, by combining and / or replacing features of individual embodiments. Therefore, it is obvious to those skilled in the art that such variations and alternative embodiments are also encompassed by the present invention, and the scope of the present invention is limited only by the scope of the appended patent claims and their equivalents.

[0116] Figure 2a Design data

[0117] Table 1 for Figure 2a Projection optical unit 200:

[0118]

[0119]

[0120] Table 2 for Figure 2a Projection optical unit 200:

[0121] Surface radius

[0122]

[0123] Table 3 for Figure 2a Projection optical unit 200:

[0124] Surface eccentricity (position, angle)

[0125]

[0126]

[0127]

[0128] Table 4 for Figure 2a Projection optical unit 200:

[0129] Free form coefficient of the surface

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146] Table 5 for Figure 2a Projection optical unit 200:

[0147] Coordinates of the aperture edge

[0148]

[0149]

[0150]

[0151] Figure 3a Design data

[0152] Table 6 for Figure 3a Projection optics unit 300:

[0153] Numerical aperture 0.75 Magnification in the x-direction 0.233 Magnification in the y direction 0.125 Chief ray angle 5.50° wavelength 13.5nm Image field size in the x-direction 26.0mm Image field size in the y direction 1.0mm Average wavelength-RMS 7.88mλ

[0154] Table 7 for Figure 3a Projection optics unit 300:

[0155] Surface radius

[0156]

[0157] Table 8 for Figure 3a Projection optics unit 300:

[0158] Surface eccentricity (position, angle)

[0159]

[0160]

[0161]

[0162] Table 9 for Figure 3a Projection optics unit 300:

[0163] Free form coefficient of the surface

[0164]

[0165]

[0166]

[0167]

[0168]

[0169]

[0170]

[0171]

[0172]

[0173]

[0174]

[0175]

[0176]

[0177] Table 10 for Figure 3a Projection optics unit 300:

[0178] Coordinates of the aperture edge

[0179]

[0180]

[0181]

[0182]

[0183]

[0184]

[0185] Figure 4a Design data

[0186] Table 11 for Figure 4a Projection Optics Unit 400:

[0187] Numerical aperture 0.75 Magnification in the x-direction 0.250 Magnification in the y direction 0.125 Chief ray angle 5.50° wavelength 13.5nm Image field size in the x-direction 26mm Image field size in the y direction 1mm Average wavelength-RMS 6.87mλ

[0188] Table 12 for Figure 4a Projection Optics Unit 400:

[0189] Surface radius

[0190]

[0191] Table 13 for Figure 4a Projection Optics Unit 400:

[0192] Surface eccentricity (position, angle)

[0193]

[0194]

[0195] Table 14 for Figure 4a Projection Optics Unit 400:

[0196] Free form coefficient of the surface

[0197]

[0198]

[0199]

[0200]

[0201]

[0202]

[0203]

[0204]

[0205]

[0206]

[0207]

[0208]

[0209]

[0210]

[0211]

[0212] Table 15 for Figure 4a Projection Optics Unit 400:

[0213] Coordinates of the aperture edge

[0214]

[0215]

[0216]

[0217] Figure 5a Design data

[0218] Table 16 for Figure 5a Projection optical unit 500:

[0219] Numerical aperture 0.75 Magnification in the x-direction 0.250 Magnification in the y direction 0.125 Chief ray angle 5.50° wavelength 13.5nm Image field size in the x-direction 26.0mm Image field size in the y direction 1.0mm Average wavelength-RMS 9.30mλ

[0220] Table 17 for Figure 5a Projection optical unit 500:

[0221] Radius of the surface

[0222]

[0223]

[0224] Table 18 for Figure 5a Projection optical unit 500:

[0225] Surface eccentricity (position, angle)

[0226]

[0227]

[0228]

[0229] Table 19 for Figure 5a Projection optical unit 500:

[0230] Free form coefficient of the surface

[0231]

[0232]

[0233]

[0234]

[0235]

[0236]

[0237]

[0238]

[0239]

[0240]

[0241]

[0242]

[0243] Table 20 for Figure 5a Projection optical unit 500:

[0244] Coordinates of the aperture edge

[0245]

[0246]

[0247]

[0248]

[0249]

[0250]

[0251] Figure 6a Design data

[0252] Table 21 for Figure 6a Projection Optics Unit 600:

[0253] Numerical aperture 0.75 Magnification in the x-direction 0.250 Magnification in the y direction 0.125 Chief ray angle 5.50° wavelength 13.5nm Image field size in the x-direction 26.0mm Image field size in the y direction 1.0mm Average wavelength-RMS 6.44mλ

[0254] Table 22 for Figure 6a Projection optical unit 600: Surface radius

[0255]

[0256]

[0257] Table 23 for Figure 6a Projection Optics Unit 600:

[0258] Surface eccentricity (position, angle)

[0259]

[0260]

[0261]

[0262] Table 24 for Figure 6a Projection Optics Unit 600:

[0263] Free form coefficient of the surface

[0264]

[0265]

[0266]

[0267]

[0268]

[0269]

[0270]

[0271]

[0272]

[0273]

[0274]

[0275]

[0276]

[0277]

[0278]

[0279]

[0280]

[0281]

[0282]

[0283]

[0284] Table 25 for Figure 6a Projection Optics Unit 600:

[0285] Coordinates of the aperture edge

[0286]

[0287]

[0288]

[0289] Figure 7a Design data

[0290] Table 26 for Figure 7a Projection optical unit 700:

[0291] Numerical aperture 0.55 Magnification in the x-direction 0.250 Magnification in the y direction 0.125 Chief ray angle 5.11° wavelength 13.5nm Image field size in the x-direction 26.0mm Image field size in the y direction 1.2mm Average wavelength-RMS 6.22mλ

[0292] Table 27 for Figure 7a Projection optical unit 700: Surface radius

[0293]

[0294] Table 28 for Figure 7a Projection optical unit 700: eccentricity of the surface (position, angle)

[0295]

[0296]

[0297]

[0298] Table 29 for Figure 7a Projection optics unit 700:

[0299] Coefficient of freedom of the surface

[0300]

[0301]

[0302]

[0303]

[0304]

[0305]

[0306]

[0307]

[0308]

[0309]

[0310]

[0311] Table 30 for Figure 7a Projection optics unit 700:

[0312] Coordinates of the aperture edge

[0313]

[0314]

[0315]

[0316]

[0317] Figure 8a Design data

[0318] Table 31 for Figure 8a Projection optics unit 800:

[0319]

[0320]

[0321] Table 32 for Figure 8a Projection optics unit 800:

[0322] Surface radius

[0323]

[0324] Table 33 for Figure 8a Projection optics unit 800:

[0325] Surface eccentricity (position, angle)

[0326]

[0327]

[0328]

[0329] Table 34 for Figure 8a Projection optics unit 800:

[0330] Coefficient of freedom of the surface

[0331]

[0332]

[0333]

[0334]

[0335]

[0336]

[0337]

[0338]

[0339]

[0340] Table 35 for Figure 8a Projection optics unit 800:

[0341] Coordinates of the aperture edge

[0342]

[0343]

[0344]

Claims

1. A projection optical unit for microlithography, comprising a plurality of mirrors for guiding imaging light (301, 501, 601, 701, 801) along an imaging beam path from an object field (5) located in an object plane (OP) to an image field (9) located in an image plane (IP), wherein the numerical aperture (NA) has a value greater than 0.5; wherein the plurality of mirrors comprises at least three mirrors for grazing incidence (GI mirrors) which deflect the chief ray of the central object field point at an angle of incidence greater than 45°; wherein light beams of different polarizations passing through the operating projection optical unit (7, 300, 500, 600, 700, 800) from the object field (5) to the image field (9) are rotated by different rotation angles in their polarization directions due to geometric polarization rotation; wherein the projection optical unit (7, 300, 500, 600, 700, 800) comprises a first group (A) of reflectors and a second group (B) of reflectors, the second group (B) of reflectors consisting of the last two reflectors (Mn-1, Mn) of the plurality of reflectors on the image side, wherein the linear part of the pupil dependence of the total geometric polarization rotation (|Z3A+Z3B|) of the projection optical unit is less than 20% of the linear part of the pupil dependence of the geometric polarization rotation (|Z3B|) of the second group (B) of reflectors; For all light beams imaging the center of the object field (5) to the center of the image field (9), the rotation angle is less than 35°*NA 4.5 .

2. The projection optical unit according to claim 1, wherein The linear part of the pupil dependence of the geometric polarization rotation (|Z3A+Z3B|) of the entire projection optical unit (7, 300, 600, 700, 800) is less than 15% of the linear part of the pupil dependence of the geometric polarization rotation (|Z3B|) of the second group (B) of the reflectors.

3. The projection optical unit according to claim 1, wherein The linear part of the pupil dependence of the geometric polarization rotation (|Z3A+Z3B|) of the entire projection optical unit (7, 300, 600, 700, 800) is less than 5% of the linear part of the pupil dependence of the geometric polarization rotation (|Z3B|) of the second group (B) of the reflectors.

4. A projection optical unit for microlithography, comprising a plurality of mirrors for guiding imaging light (301, 401, 501, 601, 701, 801) along an imaging beam path from an object field (5) located in an object plane (OP) to an image field (9) located in an image plane (IP), wherein the numerical aperture (NA) has a value greater than 0.5; wherein the plurality of mirrors comprises at least three mirrors for grazing incidence (GI mirrors) which deflect the chief ray of the central object field point at an angle of incidence greater than 45°; wherein light beams of different polarizations passing through the projection optical unit (7, 300, 400, 500, 600, 700, 800) in operation from the object field (5) to the image field (9) are rotated by different rotation angles in their polarization directions due to geometric polarization rotation; For all light beams imaging the center of the object field (5) to the center of the image field (9), the rotation angle is less than 35°*NA 4.5 .

5. The projection optical unit according to any one of claims 1 to 4, characterized in that For all light beams that image the center of the object field (5) to the center of the image field (9), the rotation angle is less than 30°*NA 4.5 .

6. The projection optical unit according to claim 5, wherein: The rotation angle is less than 25°*NA 4.5 .

7. The projection optical unit according to any one of claims 1 to 6, characterized in that The image side numerical aperture (NA) has a value greater than 0.

6.

8. The projection optical unit according to claim 7, wherein: The value is greater than 0.

7.

9. The projection optical unit according to claim 1, characterized in that For all light beams that image the center of the object field (5) to the center of the image field (9), the rotation angle is less than 7°.

10. The projection optical unit according to claim 9, wherein: The rotation angle is less than 5°.

11. The projection optical unit according to claim 9, wherein: The rotation angle is less than 3°.

12. The projection optical unit as claimed in claim 1, characterized in that The imaging beam path from the center of the object field (5) through a position of a pupil plane having relative pupil coordinates (-1,0) or (1,0) in the exit pupil to the center of the image field (9) has an NA of less than 5°* 4.5 The geometric polarization rotation.

13. The projection optical unit as claimed in claim 1, characterized in that The geometric polarization rotation averaged over all imaging beam paths in the pupil plane within a dipole at 20% pupil filling factor is less than 5°*NA 4.5 .

14. The projection optical unit as claimed in claim 1, characterized in that The circumferential distribution of the rotation angle in the pupil plane of the projection optical unit (7, 300, 500, 600, 700, 800) exhibits at least four zero crossings of the value of the rotation angle.

15. A projection optical unit for microlithography, comprising a plurality of mirrors for guiding imaging light (201, 301, 401, 501, 601, 701, 801) along an imaging beam path from an object field located in an object plane (OP) to an image field located in an image plane (IP), wherein the numerical aperture (NA) has a value greater than 0.5; wherein the plurality of mirrors comprises at least three mirrors for grazing incidence (GI mirrors) which deflect the chief ray of the central object field point at an angle of incidence greater than 45°; wherein light beams of different polarizations passing through the projection optical unit (7, 200, 300, 400, 500, 600, 700, 800) in operation from the object field (5) to the image field (9) are rotated by different rotation angles in their polarization directions due to geometric polarization rotation; and Therein, a circumferential distribution of the rotation angle in a pupil plane of the projection optical unit exhibits at least four zero crossings of the value of the rotation angle.

16. The projection optical unit according to claim 14 or 15, characterized in that The circumferential distribution of the rotation angle in the exit pupil of the projection optical unit (7, 200, 300, 400, 500, 600, 700, 800) exhibits a zero crossing within 30° of each of the positive and negative x-axes.

17. The projection optical unit according to any one of claims 14 to 16, characterized in that The circumferential distribution of the rotation angle in the exit pupil of the projection optical unit (7, 200, 300, 400, 500, 600, 700, 800) exhibits a zero crossing within 10° of each of the positive and negative y-axes.

18. The projection optical unit as claimed in claim 1, characterized in that The projection optical unit is an anamorphic projection optical unit.

19. The projection optical unit as claimed in claim 1, characterized in that The last reflector in the imaging beam path of the projection optical unit (7, 200, 300, 400, 500, 600, 700, 800) contains a passage opening for the imaging light.

20. An optical system comprising The projection optical unit (7, 200, 300, 400, 500, 600, 700, 800) according to any of the preceding claims; and An illumination optical unit (4) for illuminating an illumination field in which an object field (5) is arranged.

21. A projection exposure apparatus comprising the optical system according to claim 20; and an extreme ultraviolet light source (2) for producing the imaging light (201, 301, 401, 501, 601, 701, 801).

22. A method for producing a structured component, comprising the following method steps: Providing a mask master (13) and a wafer (15); projecting the structure on the reticle (13) onto the photosensitive layer of the wafer (15) by means of a projection exposure apparatus (1) according to claim 21; and Structured components are produced by producing microstructures or nanostructures on the wafer (15).

Images