Optical assembly, method for integrating optical assembly, and projection exposure apparatus

Abstract

The invention relates to an optical assembly (50, 70, 120) having an optical element (51, 121) that is connected to a support structure (53) via at least one actuator (56, 731, 73.2, 95.1, 95.2, 125.1, 125.2, 143), the actuator (56, 73.1, 73.2, 95.1, 95.2, 125.1, 125.2, 143) having at least one effective direction for deflecting the optical element (51, 121). The optical assembly (50, 70, 120) is distinguished in that the actuator takes the form of a planar Lorentz actuator (56, 73.1, 73.2, 95.1, 95.2, 125.1, 125.2, 143). The invention also relates to a projection exposure apparatus (1, 101) having an optical assembly (50, 70, 120) according to any of the exemplified embodiments. The invention also relates to a method for integrating an optical assembly (50, 70, 120) having an optical element (51, 121), a support structure (53) and an independent actuator unit (52, 70, 93, 123, 140), the actuator unit (52, 70, 93, 123, 140) having a moving part (49.1, 49.2, 76, 146) and a stationary part (48.1, 38.2, 68, 71, 141), comprising the following method steps: - mounting the moving part (49.1, 49.2, 76, 146) of the actuator unit (52, 70, 93, 123, 140) with the optical element (51, 121) and the stationary part (48.1, 38.2, 68, 71, 141) of the actuator unit (52, 70, 93, 123, 140) with a support structure (53), - joining the optical element (51, 121) and the support structure (53), with the moving part (49.1, 49.2, 76, 146) and the stationary part (48.1, 38.2, 68, 71, 141) of the actuator unit (52, 70, 93, 123, 140) being connected to one another by way of a decoupling element (57, 77, 94, 124, 147).

Description

[0001] Optical assembly, method for integrating optical assembly, and projection exposure apparatus

[0002] The present application claims the priority of the German patent application DE 10 2024 204 660.4, filed on 21 May 2024, the content of which is fully incorporated by reference herein.

[0003] The invention relates to an optical assembly, in particular for semiconductor lithography, to a method for integrating the optical assembly, and to a projection exposure apparatus having such an assembly.

[0004] Projection exposure apparatuses for semiconductor lithography are used for producing extremely fine structures, in particular on semiconductor components or other microstructured components. The functional principle of said apparatuses is based on the production of extremely fine structures down to the nanometre range by way of generally reducing imaging of structures on a mask, with a so-called reticle, on an element to be structured, such as, for example, a wafer, that is provided with photosensitive material. The minimum dimensions of the structures produced are directly dependent on the wavelength of the light used for imaging, the so-called used light. In a range of emission wavelengths referred to as the DUV range, the light sources used have wavelengths of 100 nm to 300 nm, while light sources with an emission wavelength of the order of a few nanometres, for example between 1 nm and 120 nm, in particular of the order of 13.5 nm, have increasingly been used in recent times. The described wavelength range is also referred to as the EUV range.

[0005] In view of deviations of the optical effective surface, i.e. the surface impinged upon by used radiation - i.e. radiation used for imaging and exposure - during the normal operation of the associated apparatus, the optical elements that for example include lens elements or - in the case of EUV lithography - mirrors only and that are used for imaging structures exhibit a significant influence on the imaging quality. The deviations of the optical effective surface in terms of position and pose vis-a-vis its predetermined target position and target pose are compensated for by manipulators. Each degree of freedom required for the compensation needs at least one actuation de- gree of freedom, and so a manipulator may comprise up to six actuation degrees of freedom. In this context, the actuation degrees of freedom are defined by way of an effective axis along which the actuator is able to apply a force in a positive and negative direction and which is thus referred to as effective direction of the actuator. The superposition of the effective axes of the actuators allows an optical element to be deflected along an axis or in a plane or be rotated about one or more axes, for example. The possible directions of movement of the optical element depend on the arrangement and number of actuators. Two or more actuators and a weight compensator are frequently combined to form an actuator unit, wherein the weight compensator serves to compensate for the component of the weight acting on the respective actuator unit.

[0006] In this case, the optical elements are connected, either directly or by way of a mount or holder, with the actuator unit that comprises at least one decoupling element such as a leaf spring or a pin that is stiff in at least one direction and elastic in the other directions. In what is known as the zero position, the stiff direction of the decoupling element is aligned exact with the direction of the weight such that there are no lateral force components, i.e. force components deviating from the direction of the weight.

[0007] However, if the optical element is deflected from this zero position, the stiff direction of the decoupling element deviates from the direction of the weight, and the lever effect of the decoupling element that arises as a result leads to an unwanted force known as a pendulum force that acts in the lateral direction in the event of small deflections.

[0008] The restoring forces brought about by way of the stiffness of the decoupling elements and the deflection are insufficient to compensate for the pendulum forces on account of the advantageously very low stiffness levels of said elements in the direction of the deflection.

[0009] Hence, once a predetermined position has been reached, the pendulum forces of all decoupling elements that were deflected on account of the positioning are compensated for by the actuator forces that are applied to other actuator units, and so the resultant force acting on the optical element equals zero. However, a disadvant- age of this is that the power flow for compensating the pendulum forces runs through the optical element and, as a result, may bring about deformations in the optical effective surface that may be significant in terms of imaging quality.

[0010] In the case of a distance between the connection point of the actuator unit and a neutral plane of the optical element, the pendulum forces and a lever defined by the distance may additionally introduce parasitic moments into the optical element. The neutral plane is the plane in which a force acting in the plane does not create any moment in the optical element. In addition, the deflection of the elastic decoupling elements causes a further moment which is transferred to the optical element via the actuator units. These moments are disadvantageous in that they cannot be compensated for by the actuator forces created at the actuator units and cause a deformation of the optical element and optical effective surface as a result, and this may have a negative effect on the imaging quality of the projection exposure apparatus.

[0011] The problem addressed by the present invention is that of providing a device that removes the above-described disadvantages of the prior art.

[0012] This problem is solved by a device having the features of the independent claim. The dependent claims relate to advantageous developments and variants of the invention.

[0013] An optical assembly according to the invention comprises an optical element that is connected to a support structure via at least one actuator, the actuator having at least one effective direction for deflecting the optical element, and is distinguished in that the actuator takes the form of a planar Lorentz actuator. A planar Lorentz actuator comprises a coil that has a lower height in one spatial direction when compared with the other two spatial directions and may have an elongate form in particular. This is advantageous in that the movement of the coil in the direction of the long side of the plane does not cause a shift in the point of application of force by the planar Lorentz actuator, whereby parasitic moments on the optical element can be reduced or prevented entirely. The Lorentz force acts perpendicular to the long side in the flat plane of the Lorentz actuator. A further advantage of the planar Lorentz actuator is the comparatively small installation volume, whereby the integration into an actuator unit of the optical assembly may be facilitated.

[0014] In particular, the optical assembly may take the form of an optical module of a projection exposure apparatus.

[0015] In a further embodiment, the optical assembly may comprise a second actuator with an effective direction that differs from that of the first actuator, whereby the two actuators may enable a deflection of the optical element in the plane that is spanned by the effective directions of the actuators. As a result, the so-called pendulum forces that are caused by the deflection of decoupling elements of the actuator unit in the plane split by the two actuators may advantageously be compensated for at the location of creation, i.e. in the causative actuator unit. This prevents a flow of power or moment through the optical element between the generally three actuator units of the optical assembly, whereby a possible deformation of the optical effective surface may advantageously be avoided.

[0016] In particular, the effective direction of the second actuator may be perpendicular to the effective direction of the first actuator.

[0017] Furthermore, the two effective directions of the actuators may be in a lateral plane of the optical assembly. The lateral plane of the optical assembly is defined by an alignment perpendicular to the gravitational force, whereby the direction of the gravitational force is referred to as vertical direction hereinbelow.

[0018] In a further embodiment, the two effective directions of the actuators may be in a lateral direction and in a vertical direction of the optical assembly.

[0019] Furthermore, the effective direction of the second actuator may be translational, whereby the two actuators are thus able to move the optical element in a lateral or in a vertical plane as described above, depending on the arrangement of the actuators.

[0020] In an alternative, the effective direction of the second actuator may be rotational. This is advantageous in that the moments caused by the pendulum forces, which were already explained above, or by other parasitic forces may be compensated for at the location of creation, i.e. in the actuator unit. In a further embodiment, a virtual point of application of force by at least one actuator may be arranged in a neutral plane of the optical element. Especially under the action of two actuators, a virtual point of application of force is defined by the point of intersection of the force action lines of the actuators and may differ in space from the location of the mechanical connection of the actuator to a component, in particular the optical element. The arrangement of the virtual point of application of force in a neutral plane of the optical element is advantageous in that, on account of a lack of a lever, no parasitic moments can be introduced into the optical element.

[0021] In a further embodiment of the invention, the optical assembly may comprise a weight compensator. As explained further above, the latter is formed in the vertical direction, i.e. in the direction of the gravitational force, and compensates for the weight of the optical element. In the case of the conventional three actuator units, the weight compensators that are in each case arranged in the actuator units in each case compensate for the component of the weight of the optical element acting on the actuator unit.

[0022] Furthermore, the optical assembly may comprise a third actuator with an effective direction acting in the direction of weight. In the case of three actuator units, each with an actuator with an effective direction acting in the direction of weight and a planar Lorentz actuator acting laterally, the optical element may be positioned in all six degrees of freedom as a result.

[0023] In particular, the third actuator may take the form of an active actuator of the at least one weight compensator. As a result, a particularly compact actuator unit, which thus saves installation space, can be formed.

[0024] Furthermore, the at least one actuator and the at least one weight compensator may have the same point of application of force on the optical element, wherein said point of application of force may advantageously be arranged in the neutral plane of the optical element, as already explained above.

[0025] In a further embodiment, the optical assembly may comprise at least one inertial actuator. Inertial actuators are used to dampen the reaction path of the actuator forces and are only effective over a limited frequency range. For example, this advantage- ously allows damping of frequencies that are excited by parasitic forces and / or moments and that cannot be compensated for by the position control, without this leading to the introduction of reaction forces into the optical assembly or into a holder of the optical assembly.

[0026] In particular, at least one inertial actuator may have the same point of application of force on the optical element as at least one actuator. For example, this may be realized by integrating the inertial actuator into the actuator unit of the optical assembly.

[0027] Furthermore, at least one inertial actuator may act in the lateral direction and at least one inertial actuator may act in the vertical direction, whereby the inertial actuators are able to act in the direction of the position actuators in an actuator unit.

[0028] In a further embodiment, a decoupling element with a decoupling effect in at least one direction may be arranged between the optical element and the weight compensator.

[0029] In particular, the decoupling element may take the form of a pin. The pin decouples all lateral and rotational degrees of freedom, and so it is only the vertical force of the weight compensator acting in the direction of longitudinal extent of the pin that is transferred. This advantageously allows parasitic forces, for example due to tolerances in the assembly and / or alignment of the effective direction of the weight compensator, to be minimized.

[0030] In a further embodiment, at least two actuators with effective directions aligned perpendicular to one another and a weight compensator may be combined to form an independent actuator unit. For example, three such actuator units may find use for positioning an optical element of an optical assembly in a projection exposure apparatus for semiconductor lithography. In a first embodiment, the two actuators may have an effective direction in a lateral and in a vertical direction, and the weight compensator may have a passive embodiment. In a second embodiment, both actuators may have an effective direction in a lateral direction, wherein, as already explained above, the weight compensator comprises an active actuator acting in the vertical direction. Furthermore, the actuator unit may comprise at least one inertial actuator, the mode of action of which has already been explained above.

[0031] In a further embodiment of the invention, the optical assembly may comprise a control for determining a compensation force and / or a compensation moment on the basis of the deflection of the optical element. The compensation forces and moments ascertained thus may be transmitted to the actuators already explained above, whereby the introduction of parasitic forces or moments during the deflection of the optical element are advantageously minimized or even prevented entirely.

[0032] A projection exposure apparatus according to the invention comprises an optical assembly according to any of the embodiments explained above.

[0033] A method according to the invention for integrating an optical assembly having an optical element, a support structure and an independent actuator unit, the actuator unit having a moving part and a stationary part, comprises the following method steps:

[0034] - mounting the moving part of the actuator unit with the optical element and the stationary part of the actuator unit with the support structure.

[0035] - joining the optical element and the support structure, with the moving part and the stationary part of the actuator unit being connected to one another by way of a decoupling element.

[0036] In particular, the method differs from integration methods known from the prior art because the optical element and the actuator unit are only still mechanically connected at one point. This advantageously reduces parasitic forces and moments that are caused on account of manufacturing and assembly tolerances.

[0037] In particular, the decoupling element may take the form of a pin, whereby possible tolerances in all relevant degrees of freedom may be decoupled. A further reduction in the constraining forces during assembly may be implemented by aligning the actuator units with respect to the connection points of the optical element, which are acquired by way of a measurement for example. Exemplary embodiments and variants of the invention are explained in detail below on the basis of the drawing. In the drawing:

[0038] Figure 1 schematically shows a meridional section of a projection exposure apparatus for EUV projection lithography,

[0039] Figure 2 schematically shows a meridional section of a projection exposure apparatus for DUV projection lithography,

[0040] Figure 3 shows a schematic illustration of a detail of an optical assembly known from the prior art,

[0041] Figure 4 shows a schematic illustration of a detail of a first embodiment of an optical assembly according to the invention,

[0042] Figure 5 shows a detail of an optical assembly according to the invention,

[0043] Figure 6 shows a further detail of the invention, and

[0044] Figures 7a, 7b show further embodiments of an optical assembly according to the invention.

[0045] In the following text, the essential constituent parts of a microlithographic projection exposure apparatus 1 are described in exemplary fashion, initially with reference to Figure 1 . The description of the basic structure of the projection exposure apparatus 1 and of its constituent parts are to be understood as non-limiting.

[0046] One embodiment of an illumination system 2 of the projection exposure apparatus 1 has, in addition to a radiation source 3, an illumination optics unit 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 may also be provided as a module separate from the rest of the illumination system. In this case, the illumination system does not comprise the light source 3. A reticle 7 arranged in the object field 5 is illuminated. The reticle 7 is held by a reticle holder 8. The reticle holder 8 is displaceable in particular in a scanning direction using a reticle displacement drive 9.

[0047] In Figure 1 , a Cartesian xyz-coordinate system is drawn in for elucidation. The x-dir- ection runs perpendicularly to the plane of the drawing into the latter. The y-direction runs horizontally, and the z-direction runs vertically. The scanning direction runs in the y-direction in Figure 1 . The z-direction runs perpendicularly to the object plane 6.

[0048] The projection exposure apparatus 1 comprises a projection optics unit 10. The projection optics unit 10 serves for imaging the object field 5 into an image field 11 in an image plane 12. The image plane 12 extends parallel to the object plane 6. In an alternative, an angle that differs from 0° is also possible between the object plane 6 and the image plane 12.

[0049] A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable in particular in the y-direc- tion using a wafer displacement drive 15. The displacement, firstly, of the reticle 7 by way of the reticle displacement drive 9 and, secondly, of the wafer 13 by way of the wafer displacement drive 15 may be synchronized with one another.

[0050] The radiation source 3 is an EUV radiation source. The radiation source 3 emits in particular EUV radiation 16, which is also referred to below as used radiation, illumination radiation or illumination light. The used radiation has in particular a wavelength in the range of between 5 nm and 30 nm. The radiation source 3 may be a plasma source, for example a laser-produced plasma (LPP) source or a gas discharge-produced plasma (GDPP) source. It may also be a synchrotron-based radiation source. The radiation source 3 may be a free electron laser (FEL).

[0051] The illumination radiation 16 emanating from the radiation source 3 is focused by a collector 17. The collector 17 may be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The illumination radiation 16 may be incident on the at least one reflection surface of the collector 17 with grazing incidence (Gl), i.e. at angles of incidence of greater than 45° relative to the direction of the normal to the mirror surface, or with normal incidence (Nl), i.e. at angles of incidence of less than 45°. The collector 17 may be structured and / or coated, firstly to optimize its reflectivity for the used radiation and secondly to suppress extraneous light.

[0052] Downstream of the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can constitute a separation between a radiation source module, comprising the radiation source 3 and the collector 17, and the illumination optics unit 4.

[0053] The illumination optics unit 4 comprises a deflection mirror 19 and, disposed downstream thereof in the beam path, a first facet mirror 20. The deflection mirror 19 may be a plane deflection mirror or, in an alternative to that, a mirror with a beam-influencing effect going beyond the pure deflection effect. In an alternative to that or in addition, the deflection mirror 19 may be in the form of a spectral filter that separates a used light wavelength of the illumination radiation 16 from extraneous light at a different wavelength. Should the first facet mirror 20 be arranged in a plane of the illumination optics unit 4 which is optically conjugate to the object plane 6 as a field plane, this facet mirror is also referred to as a field facet mirror. The first facet mirror 20 comprises a multiplicity of individual first facets 21 , which are also referred to below as field facets. Figure 1 illustrates only some of these facets 21 by way of example.

[0054] The first facets 21 may take the form of macroscopic facets, in particular rectangular facets or facets with an arc-shaped edge contour or an edge contour of part of a circle. The first facets 21 may take the form of plane facets or, in an alternative to that, convexly or concavely curved facets.

[0055] As is known for example from DE 10 2008 009 600 A1 , the first facets 21 themselves may each also be composed of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. The first facet mirror 20 may take the form of a microelectromechanical system (MEMS system) in particular. For details, reference is made to DE 10 2008 009 600 A1.

[0056] The illumination radiation 16 travels horizontally, i.e. in the y-direction, between the collector 17 and the deflection mirror 19. In the beam path of the illumination optics unit 4, a second facet mirror 22 is disposed downstream of the first facet mirror 20. Should the second facet mirror 22 be arranged in a pupil plane of the illumination optics unit 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 may also be spaced apart from a pupil plane of the illumination optics unit 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1 , EP 1 614 008 B1 , and US 6,573,978.

[0057] The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

[0058] The second facets 23 may likewise be macroscopic facets, which may for example have a round, rectangular or else hexagonal boundary, or alternatively may be facets composed of micromirrors. For details, reference is likewise made to DE 10 2008 009 600 A1 .

[0059] The second facets 23 may have plane reflection surfaces or, in an alternative to that, convexly or concavely curved reflection surfaces.

[0060] The illumination optics unit 4 thus forms a doubly faceted system. This basic principle is also referred to as a fly's eye condenser (fly's eye integrator).

[0061] It might be advantageous to arrange the second facet mirror 22 not exactly in a plane that is optically conjugate to a pupil plane of the projection optics unit 10. In particular, the pupil facet mirror 22 may be arranged so as to be tilted relative to a pupil plane of the projection optics unit 10, as described for example in DE 10 2017 220 586 A1 .

[0062] The second facet mirror 22 is used to image the individual first facets 21 into the object field 5. The second facet mirror 22 is the last beam-shaping mirror or also actually the last mirror for the illumination radiation 16 in the beam path upstream of the object field 5.

[0063] In a further embodiment (not illustrated) of the illumination optics unit 4, a transfer optics unit contributing in particular to the imaging of the first facets 21 into the object field 5 may be arranged in the beam path between the second facet mirror 22 and the object field 5. The transfer optics unit may have exactly one mirror or, in an alternative to that, two or more mirrors, which are arranged one behind another in the beam path of the illumination optics unit 4. The transfer optics unit may in particular comprise one or two normal-incidence mirrors (Nl mirrors) and / or one or two grazingincidence mirrors (Gl mirrors).

[0064] In the embodiment shown in Fig. 1 , the illumination optics unit 4 has exactly three mirrors downstream of the collector 17, specifically the deflection mirror 19, the field facet mirror 20 and the pupil facet mirror 22.

[0065] The deflection mirror 19 may also be omitted in a further embodiment of the illumination optics unit 4, and so the illumination optics unit 4 may then have exactly two mirrors downstream of the collector 17, specifically the first facet mirror 20 and the second facet mirror 22.

[0066] The imaging of the first facets 21 into the object plane 6 by means of the second facets 23 or using the second facets 23 and a transfer optics unit is, as a rule, only approximate imaging.

[0067] The projection optics unit 10 comprises a plurality of mirrors Mi, which are consecutively numbered in accordance with their arrangement in the beam path of the projection exposure apparatus 1 .

[0068] In the example illustrated in Figure 1 , the projection optics unit 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve or a different number of mirrors Mi are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics unit 10 is a twice-obscured optics unit. The projection optics unit 10 has an image-side numerical aperture which is greater than 0.5 and may also be greater than 0.6 and might be for example 0.7 or 0.75.

[0069] Reflection surfaces of the mirrors Mi may take the form of free-form surfaces without an axis of rotational symmetry. In an alternative to that, the reflection surfaces of the mirrors Mi may take the form of aspherical surfaces with exactly one axis of rotational symmetry of the reflection surface shape. Just like the mirrors of the illumination optics unit 4, the mirrors Mi may have highly reflective coatings for the illumination radiation 16. These coatings may be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0070] The projection optics unit 10 has a large object-image shift in the y-direction between a y-coordinate of a centre of the object field 5 and a y-coordinate of the centre of the image field 11 . In the y-direction, this object-image shift may be of approximately the same size as a z-distance between the object plane 6 and the image plane 12.

[0071] In particular, the projection optics unit 10 may have an anamorphic design. In particular, it has different imaging scales |3x, |3y in the x- and y-directions. The two imaging scales |3x, |3y of the projection optics unit 10 are preferably (|3x, |3y) = (+ / -0.25, + / - 0.125). A positive imaging scale [3 means imaging without image inversion. A negative sign for the imaging scale [3 means imaging with image inversion.

[0072] The projection optics unit 10 consequently leads to a reduction in size with a ratio of 4:1 in the x-direction, i.e. in a direction perpendicular to the scanning direction.

[0073] The projection optics unit 10 leads to a reduction in size of 8:1 in the y-direction, i.e. in the scanning direction.

[0074] Other imaging scales are likewise possible. Imaging scales with the same signs and the same absolute values in the x- and y-directions, for example with absolute values of 0.125 or 0.25, are also possible.

[0075] The number of intermediate image planes in the x-direction and in the y-direction in the beam path between the object field 5 and the image field 11 may be the same or may be different, depending on the embodiment of the projection optics unit 10. Examples of projection optics units with different numbers of such intermediate images in the x- and y-directions are known from US 2018 / 0074303 A1 .

[0076] In each case, one of the pupil facets 23 is assigned to exactly one of the field facets 21 for the purpose of forming a respective illumination channel for illuminating the object field 5. This may in particular result in illumination according to the Kohler principle. The far field is decomposed into a multiplicity of object fields 5 with the aid of the field facets 21 . The field facets 21 create a plurality of images of the intermediate focus on the pupil facets 23 in each case assigned thereto.

[0077] The field facets 21 are each imaged by an assigned pupil facet 23 onto the reticle 7 in a manner overlaid on one another in order to illuminate the object field 5. The illumination of the object field 5 is in particular as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity may be achieved by overlaying different illumination channels.

[0078] The illumination of the entrance pupil of the projection optics unit 10 may be defined geometrically by way of an arrangement of the pupil facets. The intensity distribution in the entrance pupil of the projection optics unit 10 may be set by selecting the illumination channels, in particular the subset of the pupil facets which guide light. This intensity distribution is also referred to as illumination setting.

[0079] A likewise preferred pupil uniformity in the region of portions of an illumination pupil of the illumination optics unit 4 that are illuminated in a defined way can be achieved by a redistribution of the illumination channels.

[0080] Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optics unit 10 are described below.

[0081] The projection optics unit 10 may have in particular a homocentric entrance pupil.

[0082] The latter may be accessible. It may also be inaccessible.

[0083] The entrance pupil of the projection optics unit 10 generally cannot be illuminated exactly by means of the pupil facet mirror 22. The aperture rays often do not intersect at a single point in the event of imaging by the projection optics unit 10 that telecentric- ally images the centre of the pupil facet mirror 22 onto the wafer 13. However, it is possible to find an area in which the spacing of the aperture rays, which is determined in pairs, becomes minimal. This area represents the entrance pupil or an area conjugate thereto in real space. In particular, this area exhibits a finite curvature.

[0084] It may be the case that the projection optics unit 10 has different positions of the entrance pupil for the tangential beam path and for the sagittal beam path. In this case, an imaging element, in particular an optical structural element, of the transfer optics unit, should be provided between the second facet mirror 22 and the reticle 7. With the aid of this optical element, the different pose of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

[0085] In the arrangement of the components of the illumination optics unit 4 illustrated in Figure 1 , the pupil facet mirror 22 is arranged in an area conjugate to the entrance pupil of the projection optics unit 10. The field facet mirror 20 is arranged so as to be tilted with respect to the object plane 6. The first facet mirror 20 is arranged so as to be tilted with respect to an arrangement plane defined by the deflection mirror 19.

[0086] The first facet mirror 20 is arranged so as to be tilted with respect to an arrangement plane defined by the second facet mirror 22.

[0087] Figure 2 schematically shows a meridional section through a further projection exposure apparatus 101 for DUV projection lithography, in which the invention can likewise be used.

[0088] The structure of the projection exposure apparatus 101 and the principle of the imaging are comparable with the structure and procedure described in Figure 1 . Identical component parts are denoted by a reference sign increased by 100 with respect to Figure 1 , i.e. the reference signs in Figure 2 start at 101 .

[0089] By contrast to an EUV projection exposure apparatus 1 as described in Figure 1 , refractive, diffractive and / or reflective optical elements 117, such as lens elements, mirrors, prisms, terminating plates, and the like, can be used for imaging or for illumination in the DUV projection exposure apparatus 101 on account of the greater wavelength of the DUV radiation 116, employed as used light, in the range from 100 nm to 300 nm, in particular in the region of 193 nm. The projection exposure apparatus 101 in this case essentially comprises an illumination system 102, a reticle holder 108 for receiving and exactly positioning a reticle 107 which is provided with a structure and determines the later structures on a wafer 113, a wafer holder 114 for holding, moving, and exactly positioning this very wafer 113, and a projection lens 110, with multiple optical elements 117 held by way of mounts 118 in a lens housing 119 of the projection lens 110. The illumination system 102 provides DUV radiation 116 required for the imaging of the reticle 107 on the wafer 113. A laser, a plasma source or the like may be used as the source of this radiation 116. The radiation 116 is shaped in the illumination system 102 by means of optical elements such that the DUV radiation 116 has the desired properties with regard to diameter, polarization, shape of the wavefront and the like when it is incident on the reticle 107.

[0090] Apart from the additional use of refractive optical elements 117, such as lens elements, prisms, terminating plates, the structure of the downstream projection optics unit 101 with the lens housing 119 does not differ in principle from the structure described in Figure 1 and is therefore not described in further detail.

[0091] Figure 3 shows a schematic illustration of a detail of an optical assembly that is known from the prior art and takes the form of a mirror assembly 30. The latter comprises an optical element that takes the form of the mirror 31 and is connected to a support structure 33 by way of actuator units 32, with only one of the conventionally three actuator units 32 of the optical assembly 30 being depicted in the detail depicted in Figure 3.

[0092] In the embodiment depicted in Figure 3, the mirror 31 comprises an optical effective surface 34, i.e. the surface of the mirror 31 , on which used light is incident for the purpose of imaging the structures on the mask onto the wafer and the position, alignment and geometry of which has a significant influence on the imaging quality of the projection exposure apparatus 1 , 101 (Figure 1 , Figure 2).

[0093] The actuator unit 32 takes the form of a bipod ("two legs") and comprises a weight compensator 35 and two actuators 36.1 , 36.2, the effective directions of which are in each case represented by double-headed arrows in Figure 3.

[0094] The actuators 36.1 , 36.2 are aligned relative to one another in such a way that these enable a deflection of the mirror 31 in the plane of the drawing, which is referred to as yz-plane. The actuators 36.1 , 36.2 each comprise a stationary portion 48.1 , 48.2, which is directly connected to the support structure 33, and a movable portion 49.1 , 49.2, which is integrated in a receptacle 47 and explained in detail in Figure 5. The receptacle 47 is part of a connection element that takes the form of a socket 38, which is represented as a dashed box in Figure 4. The latter is arranged in a cutout 40 formed in the underside of the mirror 31 that is opposite to the optical effective surface 34 and is securely connected to the mirror 31 . Thus, the socket 38 ensures a direct connection between the movable portion 49.1 , 49.2 of the actuator unit 32 and the mirror 31 . For example, the actuators 36.1 , 36.2 may take the form of Lorentz actuators.

[0095] The weight compensator 35 is connected to the receptacle 47 via a decoupling element in the form of a pin 37. In this case, the pin 37 comprises a joint 39.1 , 39.2 on both sides, whereby a tilt is rendered possible about each axis that is perpendicular to the longitudinal axis of the pin 37. The weight compensator 35 has a passive embodiment and compensates the component of the weight of the mirror 31 that acts on the actuator unit 32.

[0096] The point of intersection defined by the effective axes of the actuators 36.1 , 36.2 and of the weight compensator 35, which are represented by dash-dotted lines, is referred to as virtual point of application of force 41 and is located at the lower edge of the mirror 31 in the example depicted in Figure 3. As a result, parasitic forces 42 that act there may cause a moment 43 in the mirror 31 , and this may contribute to a deformation of the optical effective surface 34. The moment 43 is determined by the force 42 and a lever formed perpendicular to the force 42, said lever extending from the point of application of force 41 to the point of intersection with the neutral plane 44 of the mirror 31 . The point of intersection is therefore also referred to as neutral point of application of force 45 since forces acting there do not cause any moment. For example, the parasitic forces 42 are pendulum forces caused by the deflection of the pin 37.

[0097] Furthermore, the joints 39.1 , 39.2 of the pin 37 cause parasitic moments 46.1 , 46.2 in the event of a deflection of the mirror 31 in the lateral xy-plane that is perpendicular to the z-direction. Said moments are transferred to the mirror 31 via the socket 38 and may also cause a deformation of the optical effective surface 34. The actuator unit 32 is only able to compensate parasitic forces 42 and moments 43, 46.1 , 46.2, which are introduced into the mirror 31 , in the y-direction and, if necessary, in the z- direction on account of the alignment of the actuators 36.1 , 36.2. The remaining forces 42 and moments 43, 46.1 , 46.2 thus extend through the mirror 31 until they are absorbed by the two further actuator units (not depicted here). The forces 42 and moments 43 extending through the mirror may cause deformations of the optical effective surface 34, and this may have a negative effect on the imaging quality of the projection exposure apparatus.

[0098] Figure 4 shows a schematic illustration of a detail of a first embodiment of an optical assembly 50 according to the invention. In principle, this is identical to the assembly 30 described in Figure 3, with elements with a meaningful correspondence being denoted by reference signs which have been increased by 20 in relation to Figure 3. The differences arise in particular in the structure of the actuator unit 52 and the connection thereof to the mirror 51.

[0099] The structure of the actuator unit 52 comprises an active weight compensator 55 that is able to create a dynamic force, which is capable of deflecting the mirror 51 in the z- direction, in addition to the static compensation of the component of the weight of the mirror 51 acting on the actuator unit 52. In Figure 4, the weight compensator 55 is only depicted schematically by way of arrows, wherein for example the passive part can be realized by an arrangement of permanent magnets and the active part can be realized by a Lorentz actuator. In turn, the weight compensator 55 is connected to a receptacle 67 of the socket 58 via a pin 57, with the pin 57 comprising joints 59.1 , 59.2 arranged on both sides. With the exception of the receptacle 67, the socket 58 is represented by a dashed box in Figure 4, as already in Figure 3.

[0100] Furthermore, the structure of the actuator unit 52 comprises an actuator that takes the form of a planar Lorentz actuator 56 and creates a force in the y-direction, i.e. perpendicular to the weight compensator 55. Thus, the actuator unit 52 fulfils the same function as the actuator unit 32 in Figure 3 and is able to deflect the mirror 51 in the plane of the drawing (yz-plane). The force required to deflect the mirror 51 in the y-direction is comparatively small since there is no need to compensate for any weight components. On account of its design, the planar Lorentz actuator 56 already has a small extent in at least one spatial direction, and this can be minimized further on account of the relatively small forces that need to be created. The design of the planar Lorentz actuator 56 is explained in detail in Figure 5. On account of the small installation size, the Lorentz actuator 56 can be arranged in such a way that the virtual point of application of force 61 of the Lorentz actuator 56 is located at the neutral point of application of force 65 of the mirror 51 . An advantage thereof is that the parasitic forces 62 also act at the virtual point of application of force 61 , and as a result no longer cause a parasitic moment 63. The virtual point of application of force 61 of the active weight compensator 55 is identical to that of the Lorentz actuator 56.

[0101] Figure 5a shows an actuator unit 140 of an optical assembly 50 according to the invention, said actuator unit comprising an active weight compensator 142, which is merely represented by a double-headed arrow, and a planar Lorentz actuator 143 that acts in the y-direction. The actuator unit 140 is depicted in a state prior to the assembly of the mirror 51 using a support structure 53 (Figure 4) not depicted here, and this serves to explain the integration that has been much simplified by the planar Lorentz actuator 143.

[0102] In this case, the coil 144 of the Lorentz actuator 143 is already connected to the stationary portion 141 of the actuator unit 140, with the actuator unit 140 in turn already having been securely connected to the support structure 53 (Figure 4), which is not depicted here.

[0103] By contrast, the permanent magnets 145.1 , 145.2 of the Lorentz actuator 143 are already mounted in a cutout 149 of the socket 146, which is connected to the mirror 51 of the optical assembly 50. The socket 146 with the permanent magnets 145.1 , 145.2 corresponds to the moving portion of the actuator unit 140 in the embodiment depicted in Figure 5a.

[0104] When joining the optical element 51 to the support structure, the coil 144 is simply inserted from below to between the permanent magnets 145.1 , 145.2 that are arranged in the socket 146 and do not cause any parasitic mechanical forces on the optical element 51 or on the support structure 53 (Figure 4) on account of the contactless principle of the Lorentz actuator 143. In Figure 5a, the integration movement is indicated by two arrows. Thereafter, the pin 147 is mechanically connected to the socket 146, whereby the optical element 51 and the support structure 53 (Figure 4) are connected to one another by way of the actuator unit 143 that is assembled as a result.

[0105] Thus, in a method according to the invention, the socket 146 with the permanent magnets 149.1 , 149.2, i.e. the movable part of the actuator 143, may be initially assembled in advance and subsequently connected to the mirror 51 .

[0106] In parallel, the stationary portion 141 of the actuator unit 140 may already be mounted on the support structure 53 (Figure 4). When the mirror 51 is assembled on the support structure 53 (Figure 4), the actuator unit 140 is constructed from the two portions 141 , 146, with only one mechanical connection between the pin 147 and the socket 146 needing to be established in the process. This advantageously avoids parasitic forces as a result of two or more connection points within the actuator unit 140 or between actuator unit and the mirror 51 or the support structure 53 (Figure 4). The dynamic force for moving the optical element 51 in the z-direction is created by an active actuator (not depicted here), wherein the active actuator and the weight compensator 142 form an assembly, i.e. are integrated in one another, or are formed independently of one another.

[0107] Figure 5b shows an already assembled optical assembly 50, wherein the actuator unit 140 is also brought together by way of the connection of pin 147 and socket 146. The connection point of pin 147 and socket 146 is formed in the neutral point of application of force 148 of the optical element 51. As explained in relation to Figure 4, this advantageously avoids parasitic moments on the optical element 51 that are caused by pendulum forces.

[0108] Figure 6 shows a further embodiment of an actuator unit 70 of an optical assembly 50 according to the invention, said actuator unit comprising an active weight compensator 72, which is merely represented by a double-headed arrow, and two planar Lorentz actuators 73.1 , 73.2 that act perpendicular to one another in the xy-plane.

[0109] In this case, the coils 74.1 , 74.2 of the Lorentz actuators 73.1 , 73.2 are connected to the stationary portion 71 of the actuator unit 70, the latter in turn having been securely connected to the support structure 53 (Figure 4), which is not depicted here. The permanent magnets 75.1 , 75.2, 75.3, 75.4 of the Lorentz actuators 73.1 , 73.2 are arranged in cutouts 79.1 , 79.2 in the socket 76 which - as explained in Figure 4 - is connected to the mirror 51 of the optical assembly 50, which has not been illustrated for reasons of clarity either. The socket 76 corresponds to the moving portion of the actuator unit 70 in the embodiment depicted in Figure 6.

[0110] The additional actuator 73.2 brings about the advantage that the pendulum forces caused by the deflection of the mirror 51 in the xy-plane can be compensated for independently of their direction at the location of the creation, i.e. in the actuator unit 70. This means that no parasitic forces are introduced into the mirror 51 of an optical assembly 50 (Figure 4) with three actuator units 70, with the parasitic forces caused on account of tolerances being neglected. This also removes the parasitic moments caused by the parasitic force, as explained in relation to Figure 3 and Figure 4, with this being independent of the arrangement of the virtual point of application of force 78 of the actuator unit 70. Nevertheless, the embodiment depicted in Figure 6 has a point of application of force 78 that is arranged in the neutral plane (not depicted here). This preferred arrangement ensures that even a parasitic force that is present in reality on account of mechanical tolerances and deviations of the pendulum forces, which are determined by way of a model, cannot create any moment on account of the lack of a lever.

[0111] The pendulum forces are usually ascertained from the known deflection of the mirror 31 from a zero position and hence the known deflection of the pin 37, whereby the forces required to compensate for the parasitic forces can be ascertained and can be transmitted to the actuators 73.1 , 73.2.

[0112] The compact structure of the actuator unit 70 with the planar Lorentz actuators 73.1 , 73.2, which was already explained above, also allows the integration of additional functionalities; this will be explained in detail in relation to Figures 8a and 8b.

[0113] Figures 7a to 7c show a coil arrangement 80 of a planar Lorentz actuator in three views.

[0114] Figure 7a shows a plan view of a first coil 81 of the coil arrangement 80 with a longitudinal axis 83 and a winding extending in circular fashion, wherein the coil 81 has an oval shape. The latter lengthens the vertical range of the coil 81 that, should current flow in the coil 81 in the event of an arrangement in a permanent magnetic field extending perpendicular to the winding, i.e. into or out of the plane of the drawing, creates a force 82 that acts perpendicular to the current flow and to the magnetic field and that is depicted as an arrow in Figure 6a and acts in the y-direction.

[0115] Figure 7b shows the coil arrangement 80 when rotated through 180° about its longitudinal axis 83, with the result that a second coil 84 of the coil arrangement 80 is visible. In the embodiment depicted in Figure 6b, it has a winding in the form of a figure of eight. As a result, forces 86.1 , 86.2 that act in the opposite directions are created in the upper 85.1 and lower 85.2 portions with a circular embodiment. As a result, the coil 84 creates a moment 87 about a virtual connection point 88 of the coil arrangement 80, for example on the mirror 51 in Figure 4. This is advantageous in that in the event of a deflection of the mirror 51 in the xy-plane, parasitic restoring moments that are caused by the pin 57 can be compensated for at the location of creation, i.e. in the actuator unit 52. Should use be made of an actuator unit 52 with coil arrangements 80, as explained in Figure 4, it is possible to compensate both the parasitic forces and the parasitic moments in the actuator unit 70 on account of the two actuators 73.1 , 73.2 that are arranged perpendicular to one another. This is advantageous in that no, or virtually no, forces or moments are still introduced into the mirror 51 .

[0116] Figure 7c shows a sectional illustration of the coil arrangement 80 in a side view. The thickening 89 that in the event of the figure-of-eight-shaped embodiment of the winding of the second coil 84 arises at the intersection thereof is arranged in such a way in this case such that it projects into the space enclosed by the winding of the first coil 81 , whereby the installation height of the two coils 81 , 84 can be reduced. This is advantageous in that the air gap between the permanent magnets can be kept small, whereby a smaller magnetic force is required for the creation of the necessary magnetic field. This has a positive effect on the installation space required by the actuator.

[0117] In an alternative, the moment may also be created by two separately controllable circular coils that are arranged above one another, rather than being created by the fig- ure-of-eight-shaped second coil 84. Furthermore, the creation of the lateral force and of the moment may take place in two mutually independent actuators.

[0118] The pendulum forces and the moments caused by the deflection in the joints 59.1 , 59.2 (Figure 4) of the pin 57 are usually determined from the known deflection of the mirror 31 from a zero position and hence the known deflection of the pin 37, whereby the forces required to compensate for the parasitic forces and moments can be ascertained and can be transmitted to the actuators 73.1 , 73.2.

[0119] Figure 8a shows a sectional illustration of a further embodiment of an optical assembly according to the invention, which is designed as a mirror assembly 90, in a plan view from above. The structure is substantially identical to that of the optical assembly 50 depicted in Figure 4, wherein the actuator unit 52 (Figure 4) is embodied in accordance with the actuator unit 70 from Figure 6. The actuator unit 93 is arranged in the cutout 92 of the mirror 91 and, by way of the socket 98, connected to the mirror 91 via an end-face interface that is not visible in the sectional illustration (cf. Figure 4). The actuator unit 93 comprises an additional inertial actuator 96 in addition to the Lorentz actuators 95.1 , 95.2 (73.1 , 73.2 in Figure 6 incl. the coil arrangement 80 from Figures 7a to 7c) already known from the actuator unit 70. It is arranged such that above a predetermined frequency it decouples the reaction path of the first planar Lorentz actuator 95.1 , which acts in the lateral effective direction 99 of the actuator unit 93, by virtue of the inertial actuator 96 rather than the Lorentz actuator 95.1 creating the actuating forces above the predetermined frequency. Thus the Lorentz actuator 95.1 no longer creates forces above this frequency. This is advantageous in that the positioning accuracy of the mirror 91 may advantageously be improved. The second planar Lorentz actuator 95.2 serves only to compensate the parasitic forces which are caused by the actuator unit 93 and which act as quasistatic forces. In this case, an inertial actuator would not develop any effect since the latter is only able to decouple the reaction forces and thus achieve improvement above a comparatively high frequency. As explained above in relation to Figure 5, the actuator unit 93 also comprises an active weight compensator that is connected to the socket 98 via a pin 94. In the view depicted in Figure 7a, the cut pin 94 can be identified in a hole 100 formed in the socket 98. Like the Lorentz actuators 95.1 , 95.2, the weight compensator acts on the virtual point of application of force 97.

[0120] Figure 8b shows a sectional illustration of a further embodiment of an optical assembly according to the invention, designed as a mirror assembly 120, in a plan view. The mirror assembly 120 has a substantially identical structure to the mirror assembly 90 explained in relation to Figure 8a, with elements with a meaningful correspondence being denoted by reference signs which have been increased by 30 in relation to Figure 8a. In addition to the inertial actuator 96 (126 in Figure 8b) already present in the mirror assembly 90, the mirror assembly 120 comprises a further inertial actuator 132 that acts in the vertical effective direction 131 of the actuator unit 123, i.e. in the direction of the active weight compensator. The effect of the inertial actuator 123 is the same as already explained in relation to Figure 8a.

[0121] A deviating actuator arrangement may be chosen alternatively. Instead of the inertial actuators 96, 126, 132, it is possible to use separate actuators for compensating the parasitic moments. In that case, the actuators 125.1 , 125.2 would create only forces and no more moments. This is advantageous in that this requires a smaller air gap and hence a smaller magnetic field as a result of the thinner coils in all four actuators. This has a positive effect on the installation space required for the respective actuators. It is thus possible to further reduce the size of the actuator units 93, 123, especially in the case in which the inertial actuators 126, 132 are arranged outside of the actuator unit 93, 123.

[0122] List of reference signs

[0123] 1 Projection exposure apparatus

[0124] 2 Illumination system

[0125] 3 Radiation source

[0126] 4 Illumination optics unit

[0127] 5 Object field

[0128] 6 Object plane

[0129] 7 Reticle

[0130] 8 Reticle holder

[0131] 9 Reticle displacement drive

[0132] 10 Projection optics unit

[0133] 11 Image field

[0134] 12 Image plane

[0135] 13 Wafer

[0136] 14 Wafer holder

[0137] 15 Wafer displacement drive

[0138] 16 EUV radiation

[0139] 17 Collector

[0140] 18 Intermediate focal plane

[0141] 19 Deflection mirror

[0142] 20 Facet mirror

[0143] 21 Facets

[0144] 22 Facet mirror

[0145] 23 Facets

[0146] 30 Mirror assembly

[0147] 31 Mirror

[0148] 32 Actuator unit

[0149] 33 Support structure

[0150] 34 Optical effective surface

[0151] 35 Weight compensator Actuators

[0152] Pin

[0153] Socket

[0154] Pin joints

[0155] Cutout

[0156] Virtual point of application of force

[0157] Parasitic forces

[0158] Parasitic moment

[0159] Neutral plane

[0160] Neutral point of application of force Joint moments

[0161] Receptacle

[0162] Stationary part of the actuator unit Moving portion of the actuator unit Mirror assembly

[0163] Mirror

[0164] Actuator unit

[0165] Support structure

[0166] Optical effective surface

[0167] Weight compensator

[0168] Planar Lorentz actuator

[0169] Pin

[0170] Socket

[0171] Pin joints

[0172] Cutout

[0173] Virtual point of application of force

[0174] Parasitic forces

[0175] Parasitic moment

[0176] Neutral plane

[0177] Neutral point of application of force Joint moments Receptacle

[0178] Stationary portion of the actuator unit

[0179] Actuator unit

[0180] Stationary portion of the actuator unit

[0181] Weight compensator

[0182] Planar Lorentz actuator

[0183] Coil

[0184] Magnet

[0185] Socket

[0186] Pin

[0187] Neutral point of application of force

[0188] Cutouts in the socket

[0189] Coil arrangement

[0190] First coil

[0191] Force of the first coil

[0192] Longitudinal axis

[0193] Second coil

[0194] Portion of the second coil

[0195] Forces from portions of the second coil

[0196] Moment of the coil

[0197] Virtual connection point

[0198] Thickening

[0199] Mirror assembly

[0200] Mirror

[0201] Cutout

[0202] Actuator unit

[0203] Pin

[0204] Planar Lorentz actuator

[0205] Inertial actuator

[0206] Virtual point of application of force

[0207] Socket Lateral effective direction of the actuator unit

[0208] Hole in the socket

[0209] Projection exposure apparatus

[0210] Illumination system

[0211] Reticle

[0212] Reticle holder

[0213] Projection optics unit

[0214] Wafer

[0215] Wafer holder

[0216] DUV radiation

[0217] Optical element

[0218] Mounts

[0219] Lens housing

[0220] Mirror assembly

[0221] Mirror

[0222] Cutout

[0223] Actuator unit

[0224] Pin Planar Lorentz actuator

[0225] Inertial actuator

[0226] Virtual point of application of force

[0227] Socket

[0228] Lateral effective direction of the actuator unit

[0229] Hole in the socket

[0230] Vertical effective direction of the actuator unit

[0231] Vertical inertial actuator

[0232] Actuator unit

[0233] Stationary portion of the actuator

[0234] Weight compensator

[0235] Actuator

[0236] Coil 145.1 , 145.2 Magnet

[0237] 146 Socket

[0238] 147 Pin

[0239] 148 Neutral point of application of force

[0240] 149 Cutout

[0241] M1-M6 Mirrors

Claims

Claims1. Optical assembly (50, 70, 120) having an optical element (51 , 121 ) that is connected to a support structure (53) via at least one actuator (56, 73.1 , 73.2,95.1 , 95.2, 125.1 , 125.2, 143), the actuator (56, 73.1 , 73.2, 95.1 , 95.2, 125.1 ,125.2, 143) having at least one effective direction for deflecting the optical element (51 , 121 ), characterized in that the actuator takes the form of a planar Lorentz actuator (56, 73.1 , 73.2, 95.1 ,95.2, 125.1 , 125.2, 143), and the optical assembly (50, 70, 120) comprises a weight compensator (55, 72, 142).

2. Optical assembly (50, 70, 120) according to Claim 1 , characterized in that the optical assembly (50, 70, 120) takes the form of an optical module of a projection exposure apparatus (1 , 101 ).

3. Optical assembly (50, 70, 120) according to either of Claims 1 and 2, characterized in that the optical assembly (50, 70, 120) comprises a second actuator (73.2, 95.2, 125.2) with a different effective direction to that of the first actuator (73.1 , 95.1 , 125.1 ).

4. Optical assembly (50, 70, 120) according to Claim 3, characterized in that the effective direction of the second actuator (73.2, 95.2, 125.2) is perpendicular to the effective direction of the first actuator (73.1 , 95.1 , 125.1 ).

5. Optical assembly (50, 70, 120) according to either of Claims 3 and 4, characterized in thatthe two effective directions of the actuators (73.1 , 73.2, 95.1 , 95.2, 125.1 , 125.2) are in a lateral plane of the optical assembly (50, 70, 120).

6. Optical assembly (50, 70, 120) according to either of Claims 3 and 4, characterized in that the two effective directions of the actuators (73.1 , 73.2, 95.1 , 95.2, 125.1 , 125.2) are in a lateral direction and in a vertical direction of the optical assembly (50, 70, 120).

7. Optical assembly (50, 70, 120) according to any of Claims 3 to 6, characterized in that the effective direction of the second actuator (73.2, 95.2, 125.2) is translational.

8. Optical assembly (50, 70, 120) according to any of Claims 3 to 7, characterized in that the effective direction of the second actuator (73.2, 95.2, 125.2) is rotational.

9. Optical assembly (50, 70, 120) according to any of the preceding claims, characterized in that a virtual point of application of force (41 , 61 , 97, 127) by at least one actuator (56, 73.1 , 73.2, 95.1 , 95.2, 125.1 , 125.2, 143) is arranged in a neutral plane (64) of the optical element.

10. Optical assembly (50, 70, 120) according to any of the preceding claims, characterized in that the optical assembly comprises a third actuator with an effective direction acting in the direction of weight.

11. Optical assembly (50, 70, 120) according to Claim 10, characterized in that the third actuator takes the form of an active actuator of the at least one weight compensator (55, 72, 142).

12. Optical assembly (50, 70, 120) according to any of the preceding claims, characterized in that the at least one actuator (56, 73.1 , 73.2, 95.1 , 95.2, 125.1 , 125.2, 143) and the at least one weight compensator (55, 72, 142) have the same point of application of force (41 , 61 , 78, 97, 127, 148) on the optical element (51 , 121 ).

13. Optical assembly (50, 70, 120) according to any of the preceding claims, characterized in that the optical assembly (50, 70, 120) comprises at least one inertial actuator (96, 126, 132).

14. Optical assembly (50, 70, 120) according to Claim 13, characterized in that at least one inertial actuator (96, 126, 132) has the same point of application of force (41 , 61 , 78, 97, 127, 143) on the optical element (51 , 121 ) as at least one actuator (56, 73.1 , 73.2, 95.1 , 95.2, 125.1 , 125.2, 143).

15. Optical assembly (50, 70, 120) according to either of Claims 13 and 14, characterized in that at least one inertial actuator (96, 126) acts in the lateral direction, and at least one inertial actuator (132) acts in the vertical direction.

16. Optical assembly (50, 70, 120) according to any of the preceding claims, characterized in that a decoupling element (57, 77, 94, 124, 147) with a decoupling effect in at least one direction is arranged between the optical element (51 , 121 ) and the weight compensator (55, 72, 142).

17. Optical assembly (50, 70, 120) according to Claim 16, characterized in that the decoupling element takes the form of a pin (57, 77, 94, 124, 147).

18. Optical assembly (50, 70, 120) according to any of the preceding claims, characterized in that at least two actuators (56, 73.1 , 73.2, 95.1 , 95.2, 125.1 , 125.2, 143) with effective directions aligned perpendicular to one another and a weight compensator (55, 72, 142) are combined to form an independent actuator unit (52, 70, 93, 123, 140).

19. Optical assembly (50, 70, 120) according to Claim 18, characterized in that the actuator unit (52, 70, 93, 123, 140) comprises at least one inertial actuator (96, 126, 132).

20. Optical assembly (50, 70, 120) according to any of the preceding claims, characterized in that the optical assembly (50, 70, 120) comprises a control for determining a compensation force and / or a compensation moment on the basis of the deflection of the optical element (51 , 121 ).

21. Projection exposure apparatus (1 , 101 ) having an optical assembly (50, 70, 120) according to any of the preceding claims.

22. Method for integrating an optical assembly (50, 70, 120) having an optical element (51 , 121 ), a support structure (53) and an independent actuator unit (52, 70, 93, 123, 140), the actuator unit (52, 70, 93, 123, 140) having a moving part (49.1 , 49.2, 76, 146) and a stationary part (48.1 , 38.2, 68, 71 , 141 ), comprising the following method steps:- mounting the moving part (49.1 , 49.2, 76, 146) of the actuator unit (52, 70, 93, 123, 140) with the optical element (51 , 121 ) and the stationary part (48.1 , 38.2, 68, 71 , 141 ) of the actuator unit (52, 70, 93, 123, 140) with a support structure (53),- joining the optical element (51 , 121 ) and the support structure (53), with the moving part (49.1 , 49.2, 76, 146) and the stationary part (48.1 , 38.2, 68, 71 ,by way of a decoupling element (57, 77, 94, 124, 147).

23. Method according to Claim 22, characterized in that the decoupling element takes the form of a pin (57, 77, 94, 124, 147).

Images