Apparatus, holding device, arrangement, system and method for holding an optical element; lithograpy system

Abstract

The invention relates to an apparatus (1) for holding an optical element (2), in particular an optical element of a lithography system, having a holding point (5) for connection to the optical element (2). The holding point (5) is connected to a support (3). According to the invention, it is provided that the support (3) comprises at least two rod legs (3a) and a connection piece (15), wherein the connection piece (15) is arranged between the holding point (5) and an upper end (9a) of the rod legs (3a) and connects the rod legs (3a) to one another. The rod legs (3a) converge towards one another at an acute angle (6) in the direction of the holding point (5), wherein the acute angle (6) between the rod legs (3a) is less than 30°, and wherein a virtual point of intersection (7) in the extension of the rod legs (3a) lies on the far side of the holding point (5).

Description

[0001] Apparatus, holding device, arrangement, system and method for holding an optical element; lithography system

[0002] The present application claims the priority of the German patent application no. 10 2024 203 031.7, the content of which is fully incorporated herein by reference.

[0003] The invention relates to an apparatus for holding an optical element, in particular an optical element of a lithography system.

[0004] The invention also relates to a holding device for holding an optical element, in particular an optical element of a lithography system, at least comprising a first and a second apparatus with a common holding point for connection to the optical element.

[0005] The invention additionally relates to an arrangement for holding an optical element, in particular an optical element of a lithography system, at least comprising six apparatuses according to the invention or three holding devices according to the invention.

[0006] The invention furthermore relates to a system comprising an optical element, in particular an optical element of a lithography system, and at least comprising six apparatuses according to the invention or three holding devices according to the invention for holding the optical element.

[0007] The invention moreover relates to a method for holding and in particular for positioning and / or aligning an optical element, in particular an optical element of a lithography system.

[0008] The invention further relates to a lithography system, in particular a projection exposure apparatus for semiconductor lithography, having an illumination system with a radiation source and an optical unit which comprises at least one optical element.

[0009] Optical elements require a suitable holder for fixing or holding or mounting them in an optical system and in order to be able to selectively move and / or tilt them, if appropriate. Already during installation, for example assembly or contact surfaces, manufacturing tolerances, angular or positional errors or differences in thermal expansion between the optical element and its surroundings can have an effect on the holder or the optical element. Differences in thermal expansion between the optical element and its surroundings can, during operation, also be caused by light absorption. If positioning and / or aligning is necessary or desired, use is made of actuators which exert additional forces. During installation, during operation, and when positioning and / or aligning is taking place, also transferred to the optical element are undesired forces and moments that lead to deformations of the optical element and / or of an optical surface of the optical element. These deformations can adversely affect the functionality of the optical element, in particular if high precision in the beam path and / or in the beam profile is necessary, such as for an imaging quality which is as high as possible and imaging aberrations that are as small as possible in the semiconductor lithography. For many applications, in particular in high-performance optics, optical elements should be able to be moved at least in translation in a lateral and axial direction and in rotation about the radial, tangential and axial axes. Deformations of the optical elements or optical faces or optical surfaces can occur in the process. Generally speaking, such deformations are caused by parasitic forces and / or moments or parasitic loads, which arise as an undesired or passive side effect of the envisaged active positioning and / or alignment of the optical element. This is in particular because positioning mechanisms for moving the optical elements are formed by spring joints, which cause deformation forces and deformation torques when they move in articulation and thus when the positioning mechanism is moving. Such parasitic loads are at least partially absorbed or taken up by the optical element and can therefore unintentionally change the shape of the optical element. In particular introduced radial moments and tangential moments are of particular importance here.

[0010] Besides the positioning and / or alignment of the optical element, the holder also has a basic holding function. In this respect, also of decisive importance are oscillations, which are generally undesirable and, like deformations of the optical element, should be minimized in order to achieve as good as possible an imaging quality and to prevent optical artefacts.

[0011] A variety of apparatuses for holding or mounting, positioning and / or aligning optical elements are known from the prior art. Also known are such apparatuses that are designed to partially reduce undesired deformations of the optical element.

[0012] In a basic form, for this an apparatus for holding, positioning and / or aligning optical elements may have a deformation decoupling means, which mechanically decouples two parts of the holder.

[0013] For example, EP 1 028 342 A1 discloses an apparatus for tilting an object about at least one axis, in particular an optical element, such as a lens element, the object being supported by an inner ring and connected to a mount or an outer ring via at least three mounting points. Provided here are couplings, in particular support couplings which may be in the form of flexures, which decouple the object or the inner ring from its mount or the outer ring in terms of deformation.

[0014] Similar to this, WO 2006 / 000352 A1 discloses a positioning unit for an optical element in a projection exposure apparatus for microlithography comprising an inner ring and comprising an outer mount, which has movable intermediate elements or intermediate parts preferably designed as flexures in the form of leafspring-like levers or leaf springs.

[0015] US 5 986 827 A discloses an optics apparatus in the case of which the optical element is supported at three holding points by a respective bending mechanism, or bipod, which has two supports or bending legs arranged in a V shape. The ends of the bending legs have joints, or blade flexures, in order to avoid excessive restriction and thus deformation of the mounted optical unit. The adjustability is ensured by separate levers. The joints are intended to make the bending legs flexible with respect to translational and tilting movements, in order that the legs mainly transfer forces in their longitudinal direction to the optical element. This can in some cases avoid parasitic radial torques. However, deformations ofthe joints caused, among other things, by coupling stiffnesses are at least partially also transferred to the optical element, which unintentionally deforms as a result. The disadvantageous deformation mechanisms include primarily, but not exclusively, tangential torques while the holding point is being transversely displaced perpendicular to the longitudinal axis. These disadvantages also affect other solutions with bipod holders according to the prior art. With regard to US 5986827 A, in particular the requirement for increased structural space owing to the additional lever for the adjustment is also a disadvantage.

[0016] What the solutions already mentioned have in common is that they comprise two-part holders with an inner ring and an outer ring. In this respect, however, especially the weight, unfavourable eigenfrequencies, high resonance amplitudes, and the dual-mass oscillator structure with multiple inertia elements have proven to be disadvantageous.

[0017] DE 10 2018 200 181 A1 discloses a kinematic mechanism for guided movement of a component of a projection exposure apparatus, the optical element being fastened directly on the adjustment units, or bipods, in order to avoid the aforementioned problems of oscillation dynamics. The influence of the parasitic forces and torques acting on the optical element when the bipods are being adjusted is reduced by the origin of the main axis system of the stiffness matrix of the kinematic mechanism, or the bipods, coinciding with the holding points on the optical component. This is achieved by a crossed arrangement of bipod legs and reduces the parasitic loads on the mirror.

[0018] Although this solution reduces parasitic tangential torques and the resulting deformations, the kinematic mechanism of DE 10 2018 200 181 A1 needs a relatively large amount of structural space below, above and to the sides ofthe holding point and projections for attachment to the kinematic mechanism are required on the optical element. Moreover, the indirect conduction of forces, or the tortuous flow of forces, means that only a relatively low stiffness can be obtained. Added to this is the fact that the relatively soft attachment can lead to problems in terms of oscillation dynamics.

[0019] The present invention is based on the object of providing an apparatus for holding an optical element which is improved over the prior art and in particular minimizes undesired deformations of the optical element.

[0020] According to the invention, this object is achieved by an apparatus having the features specified in Claim 1.

[0021] The present invention is also based on the object of providing a holding device for holding an optical element which is improved over the prior art and in particular minimizes undesired deformations of the optical element. According to the invention, this object is achieved by a holding device having the features specified in Claim 19.

[0022] The present invention is additionally based on the object of providing an arrangement for holding an optical element which is improved over the prior art and in particular minimizes undesired deformations of the optical element.

[0023] According to the invention, this object is achieved by an arrangement having the features specified in Claim 23.

[0024] The present invention is furthermore based on the object of providing a system having an optical element, this system being improved over the prior art and in particular making it possible to hold the optical element in a better way and / or minimizing undesired deformations of the optical element.

[0025] According to the invention, this object is achieved by a system having the features specified in Claim 25.

[0026] The present invention is moreover based on the object of providing a method for holding and in particular positioning and / or aligning an optical element which is improved over the prior art and in particular minimizes undesired deformations of the optical element.

[0027] According to the invention, this object is achieved by a method having the features specified in Claim 27.

[0028] The present invention is further based on the object of providing a lithography system which comprises optical elements held in a way that avoids the disadvantages of the prior art, in particular in a way that minimizes undesired deformations of the optical element.

[0029] According to the invention, this object is achieved by a lithography system having the features specified in claim 28.

[0030] The apparatus according to the invention for holding, or mounting, an optical element, in particular an optical element of a lithography system, has a holding point for connection to the optical element. The holding point is connected to a support. According to the invention, it is provided that the support comprises at least two rod legs and a connection piece, wherein the connection piece is arranged between the holding point and an upper end, next to the holding point, of the rod legs and connects the rod legs to one another. Furthermore, according to the invention the rod legs converge towards one another at an acute angle in the direction of the holding point, wherein the acute angle between the rod legs is less than 30°, and wherein a virtual point of intersection in the extension of the rod legs lies on the far side of the holding point. The apparatus according to the invention is advantageously suitable for holding, or mounting, optical elements with minimum parasitic loads. The internal movability of the apparatus can passively compensate for, for example, angular or positional errors or differences in thermal expansion between the optical element and its surroundings, or the holder. By contrast to the prior art, therefore, scarcely any deformations of the optical element occur, in particular considerably smaller deformations owing to tangential torques when the holding point is being transversely displaced perpendicular to a longitudinal axis of the rod legs occur. Further advantages are, among other things, a direct conduction of ferees, a high stiffness, or low flexibility, in the longitudinal direction, low coupling stiffnesses, and a low tendency to oscillate and resonate. In the context of lithography systems, this leads to a considerably improved imaging quality, because an optical element held, or mounted, with reduced deformation in this way experiences few or no imaging aberrations caused by external influences. An additional advantage over solutions according to the prior art which have a tendency to worse deformation reduction is the comparatively small amount of structural space required for the apparatus according to the invention.

[0031] The apparatus may in particular also be designed to align and / or position, or guidedly move, the optical element. For this, the rod legs may for example be movable. The present invention can therefore achieve the object of providing an apparatus for positioning and / or aligning an optical element, the apparatus minimizing undesired deformations of the optical element.

[0032] The holding point at least partially supports the optical element. The optical element is fastened to the holding point. The holding point may in particular be in the form of a holder, or a holding device. The optical element and the apparatus, or the support, can be connected by the holding point. The connection may in particular also be formed by further elements between the support, or the connection piece, and the holding point.

[0033] The relative positions of the rod legs, which are coupled to one another preferably by the connection piece and the positions of which therefore depend on one another, can be varied relative to one another. Further elements may be arranged between the rod legs and the connection piece. In particular, the support may comprise further elements.

[0034] The plane of the acute angle between adjacent rod legs can, depending on the desired direction of action of the apparatus, be aligned in particular tangentially or radially in relation to the optical element, or to an optical face or optical surface of the optical element. Within the context of the invention, the optical surface may in particular be the centre plane of a lens element or the surface, or mirror face, or a mirror. The plane of the acute angle may, however, also be aligned in any desired other way, or as desired in spatial terms.

[0035] The wording "on the far side of the holding point" refers to a position of the virtual point of intersection on an opposite optical-element side to the rod legs. In particular, the rod legs converge towards one another in the direction of the holding point at the optical element such that, at the holding point, or at the level of the holding point, a distance remains between the rod legs or the virtual extensions of the rod legs, since according to the invention the virtual point of intersection lies on the far side of the holding point. Within the meaning of the invention, the holding point is not a point at which the rod legs converge or in which the rod legs intersect, but rather the holding point has such an extent that the rod legs can converge towards the holding point and preferably are fastened thereto, but do not intersect in the holding point.

[0036] The virtual point of intersection is also the current centre of rotation of the rod legs and / or of the connecting piece during a relative movement of the rod legs with respect to one another.

[0037] The advantages of the apparatus according to the invention largely result from the fact that, due to the arrangement of at least two rod legs which are movable relative to one another and are not mutually parallel, the apparatus can compensate for parasitic forces and / or moments that would otherwise be taken up by the optical element and deform the latter, by means of rotating or counter-tilting or pivoting the connecting piece about the virtual point of intersection, or current centre of rotation.

[0038] Usually, multiple apparatuses according to the invention are used together to hold the optical element. In particular, two apparatuses according to the invention together can form a bipod, or a holding device. The two apparatuses may form the legs of the bipod. By contrast to the prior art, a central part of the leg is not formed by a compact and substantially immovable piece, or is not formed as one rod, but rather is intrinsically movable, as described above. With preference, use is made of three such bipods, or holding devices, or six individual apparatuses for the positioning and / or alignment of an optical element. It is possible to provide in particular multiple holding points, to which the optical element is fastened and which together support the optical element.

[0039] Such a configuration of the invention in which a head joint device is provided, wherein the head joint device is arranged between the connection piece and the holding point, has proven to be particularly suitable.

[0040] The head joint device can connect the support, or the connection piece, to the holding point.

[0041] The head joint device also preferably makes the apparatus tiltable at the holding point.

[0042] The support may have a support foot, wherein the support foot is arranged at a lower end, remote from the holding point, of the rod legs and connects the rod legs to one another.

[0043] The support foot at least partially supports the support.

[0044] The support foot preferably lies on a longitudinal axis of the apparatus. Further elements may be arranged between the support foot and the lower end of the rod legs.

[0045] Instead of being connected by the support foot, it is also possible for the lower end of the rod legs, or the elements fastened thereto, to be connected by a common contact surface in the surroundings, or in each case directly to the fixed world.

[0046] With preference, the support can be moved by an actuator for selective positioning and / or alignment of the optical element, wherein the rod legs of the support can be moved by the actuator jointly, preferably at least along a longitudinal axis of the apparatus.

[0047] This also advantageously makes the apparatus suitable for positioning and / or aligning, or guidedly moving, optical elements with minimum parasitic loads.

[0048] It has proven advantageous in this respect if the rod legs can be moved in any desired directions, preferably at least along a longitudinal axis of the apparatus. With further preference, the rod legs can also be moved jointly in a second direction.

[0049] The support can, if appropriate, also have a respective actuator per rod leg, these actuators being arranged and designed such that the rod legs can be moved synchronously, or jointly.

[0050] During a joint movement of the rod legs, or of the entire support, by the actuator, the rod legs of the apparatus can move at the same time in an at least approximately identical direction. The relative positions of the rod legs, as already described, can vary relative to one another.

[0051] For the positioning and / or alignment of the optical element by means of at least one actuator, the rod legs may in particular have a fixed length or a variable length.

[0052] The actuator may be connected, or operatively connected, to the support foot and / or be formed in one piece with the support foot.

[0053] In particular, the actuator may be force-fitted with, form-fitted with and / or integrally bonded to the support foot.

[0054] The actuator is preferably designed to move, or displace, the support foot and / or the support. With further preference, the actuator can be moved, or displaced, in multiple spatial directions.

[0055] In a preferred configuration of the invention, the support has a compensation element, wherein the compensation element is arranged and designed such that the position of the rod legs relative to one another can be varied to reduce deformations of the optical element by means of interaction between the rod legs, the compensation element and the connection piece, in order to counteract a tilting of the holding point relative to the optical element.

[0056] The compensation element may be part of the support.

[0057] The head joint device may, together with the rod legs, the compensation element and the connection piece, contribute to the tiltability of the apparatus for reducing deformations of the optical element.

[0058] In particular, the kinematic mechanism made up ofthe rod legs, the connection piece and the compensation element, or the rod kinematic mechanism, should be able to act, or be movable, perpendicular to a longitudinal axis of the apparatus. Along the longitudinal axis of the apparatus, the kinematic mechanism should preferably have a high stiffness.

[0059] The virtual point of intersection, or current centre of rotation, of the rod legs, or of the connection piece, is also the current centre of rotation of the rod kinematic mechanism.

[0060] Deformations of the optical element can be reduced by the at least partial compensation of forces and / or moments acting unintentionally on the holding point. In particular, deformations of the optical element can be reduced by at least partially compensating for parasitic torques that act on the holding point and can be induced by forces exerted perpendicular to a longitudinal axis of the apparatus for a transverse displacement of the holding point. An interaction between the rod legs, the compensation element and the connection piece counteracts a tilting of the holding point relative to the optical element. The head joint device can also contribute to this, if appropriate, in particular owing to its tiltability.

[0061] With preference, the following equation (1), which describes the relationship between the stiffnesses of the rod legs, of the compensation element and of the head joint device, should be satisfied to the best possible extent:

[0062] 0 = nszB{ k[ft,rot,nsin2fis+ CS rot q(l + cos2ft)] [ ft)] +sm^ LUt>PP~SZs)[cs,n ,q+ ft2Qsin2ft]] + 2CB rotqCSnzPsin2ft, + CS q2zs- zPsin2ft)}

[0063] Here, zB< 0 is the z position ofthe head joint device, zs< 0 is the z position of the rod legs, in particular the point of main axial stiffness of a rod leg, at which no coupling stiffnesses arise and which lies in the point of intersection of the planes of symmetry in the case of a completely symmetrical rod leg, zPis the z position of the virtual point of intersection of the rod legs, or the current centre of rotation of the rod kinematic mechanism, nsis the number of rod legs of the rod kinematic mechanism, ft is the angle formed by the rod legs with the longitudinal axis of the rod kinematic mechanism, CBrot qis the tilting stiffness of the head joint device, CSnis the normal stiffness of a rod leg including any possibly present compensation element, CS qis the transverse stiffness of a rod leg including any possibly present compensation element, CSirotinis the torsional stiffness of a rod leg including any possibly present compensation element, and CSrot qis the tilting stiffness of a rod leg including any possibly present compensation element.

[0064] The angle formed by the rod legs with the longitudinal axis of the rod kinematic mechanism (fis) is preferably half the acute angle formed between the rod legs, so the rod legs are symmetrical about the longitudinal axis of the rod kinematic mechanism.

[0065] It can be advantageous if the compensation element is in the form of an upper joint device, which is arranged on the upper end of the rod legs and articulatedly connects the rod legs to the connection piece, and / or the compensation element is in the form of a lower joint device, which is arranged on the lower end of the rod legs and articulatedly connects the rod legs to the support foot of the apparatus and / or to the actuator.

[0066] The rod legs are coupled to one another, preferably by the connection piece, so the positions of the rod legs depend on one another.

[0067] A tilting of the holding point relative to the optical element can be compensated for by a counter-tilting of the rod kinematic mechanism, it also being possible for the position of the rod legs relative to one another to vary. The upper joint device and / or the lower joint device is preferably designed to permit a compensation movement of the rod legs relative to one another. In particular, the upper joint device can interact with the connection piece and / or the head joint device.

[0068] It should be noted that the articulated connection of the rod legs to the connection piece is configured in such a way that the virtual point of intersection in the extension of the rod legs lies, according to the invention, on the far side of the holding point. In particular, at the connection piece, or at the holding point, a distance remains between the rod legs or the virtual extensions of the rod legs. The distance between the rod legs at the lower end of the rod legs, or at the support foot, is also in particular greater than the distance at the upper end of the rod legs, or at the connection piece, or at the holding point.

[0069] The upper joint device and / or the lower joint device may each have at least one joint.

[0070] With preference, the at least one joint is a leaf spring, or a leaf-spring joint. The advantages of leaf-spring joints are a relatively high stiffness in the rod direction or longitudinal direction of the apparatus, the absence of mounting play and a negligibly low movement hysteresis in the region of the elastic deformation. The joint can, however, also be a wire joint or another joint. A wire joint can be advantageous for a flexibility of the joint about multiple axes at the same time.

[0071] It may be advantageous if the rod legs are rigid, in particular in the axial direction. The rod legs are at least partially rigid, or rigid at least in certain portions.

[0072] In particular in combination with an upper joint device, it has been found to be particularly suitable if the rod legs are stiff, or rigid, in the axial direction.

[0073] The rod legs may for example consist of steel, in particular corrosion-resistant or stainless steel, other metals or ceramics.

[0074] It may also be advantageous if the rod legs are flexible, in particular in the radial, or transverse, direction.

[0075] The rod legs are at least partially flexible, or flexible at least in certain portions.

[0076] In particular, it may also be advantageous if some portions of the rod legs are rigid and others are flexible. In particular, the flexible portions can establish a movability similar to the upper joint device and / or lower joint device.

[0077] It may be provided that the apparatus has two, three or four rod legs, the rod legs having a conical arrangement.

[0078] It may optionally also be possible to provide more than two, in particular more than four, rod legs, a design of the apparatus in which exactly two, three or four rod legs are provided having been found to be especially suitable.

[0079] With preference, adjacent rod legs converge towards one another at an acute angle. Lower ends of the rod legs are preferably uniformly distributed around a circle.

[0080] With preference, the extensions of all the rod legs of the apparatus meet in a common virtual point of intersection. The virtual point of intersection of the rod legs can be interpreted as the vertex of the cone formed by the rod legs.

[0081] It is, however, also possible for only two of the rod legs, which are mirror-symmetrical with respect to the longitudinal axis of the apparatus, to converge towards one another in a common virtual point of intersection. Further rod legs can be mirror-symmetrical with respect to the longitudinal axis of the apparatus in particular in a plane perpendicular to the plane spanned by the first two rod legs, and converge towards one another in a second common virtual point of intersection.

[0082] If the rod legs are provided with an upper and a lower joint device, it may be provided to form the virtual point of intersection by extending the straight connecting lines between the lower and the upper joint device, it being possible for the orientation of the connection elements between the lower and the upper joint device to deviate from this straight connecting line. It may also be provided to use a straight connecting line between the lower and the upper end of the rod legs to determine the extension of the rod legs that determines the virtual point of intersection, in particular if the rod legs are not linear.

[0083] It has also been found to be especially suitable if the head joint device is arranged directly at the holding point.

[0084] In particular, the head joint device can preferably be arranged as close as possible to the holding point, so no other elements lie in between.

[0085] It is particularly advantageous if the upper joint device and / or the lower joint device has a plurality of joints.

[0086] The head joint device may furthermore also have a plurality of joints.

[0087] If the upper joint device, the lower joint device and / or the head joint device has a plurality of joints, it is advantageous in particular if the joints are in the form of leaf springs, or leaf-spring joints.

[0088] The joints may be located in various planes as viewed in the axial direction of the rod legs, or along the longitudinal axis of the apparatus. The joints may be arranged and designed in particular such that the joint or the joints located in a first plane enable a deflection in a first direction and the joint or the joints located in a second plane enable a deflection in a second direction orthogonal thereto, the two directions running in a surface area and the surface area, or plane, running preferably orthogonally to the longitudinal axis of the apparatus. Respective intermediate elements may be provided between the planes.

[0089] With preference, first joints of the upper joint device are fastened to the connection piece and are connected to the respective upper end of one of the rod legs or to a respective intermediate element of the upper joint device.

[0090] There may be multiple first joints. In addition to this, it is optionally also possible for multiple intermediate elements to be provided. With preference, however, two or four first joints and accordingly two or four first intermediate elements are provided.

[0091] The first joints may in particular then advantageously be connected to the upper end of one of the rod legs, if the apparatus has exactly two rod legs. The upper joint device preferably has two first joints. However, it is also possible to provide four first joints, in particular whenever the apparatus has exactly four rod legs. It has proven to be especially suitable if two or more intermediate elements are provided.

[0092] With further preference, respective second joints of the upper joint device are fastened to the intermediate elements and are connected to the respective upper end of one of the rod legs. This configuration of the invention is suitable in particular whenever the apparatus has exactly four rod legs.

[0093] The upper joint device preferably has four second joints.

[0094] Similarly to the above-described configurations of the upper joint device for an apparatus with exactly two rod legs, in particular comprising two first joints, or with exactly four rod legs, in particular comprising two or four first joints, two or four intermediate elements and four second joints, upper joint devices for more than four rod legs can also be formed. Furthermore, it is also possible to combine other numbers of first joints, intermediate elements, second joints and rod legs.

[0095] It has also been found to be particularly suitable if, as viewed in the axial direction of the rod legs, at least two adjacent joints of the upper joint device have been rotated by 90° relative to one another, the joints being in particular the first joints and the second joints.

[0096] Joints on the same plane of the upper joint device, in particular the first joints relative to one another and the second joints relative to one another, are preferably uniformly oriented, or not rotated relative to one another.

[0097] Similarly, it can be advantageous if the head joint device has at least two joints on different planes rotated by 90° relative to one another.

[0098] It should be noted that, in the case of the aforementioned variants or combinations of the aforementioned variants, at least one joint of the head joint device has been rotated by 90° relative to the first joints and / or to the second joints, but they may also have the same orientation.

[0099] The lower joint device can be provided both in addition to and independently of the upper joint device.

[0100] The lower joint device may be formed similarly to one of the above-described configurations of the upper joint device.

[0101] With preference, the joints of the lower joint device are in the form of leaf springs or leaf-spring joints.

[0102] First joints of the lower joint device may be fastened between the support foot or the actuator and the respective lower end of one of the rod legs or a respective intermediate element of the lower joint device, it being possible to fasten second joints of the lower joint device to the intermediate element of the lower joint device that are connected to the respective lower end of one of the rod legs.

[0103] The first joints ofthe lower joint device can preferably have been rotated by 90° relative to the second joints of the lower joint device. The compensation element may be at least partially formed by the lower joint device.

[0104] As an alternative or in addition to the upper joint device and / or the lower joint device, it may be provided that the compensation element is at least partially formed by the rod leg, it being possible for the rod leg to consist of a flexible material. In this context, the virtual point of intersection may refer to the point of intersection of straight lines through the respective upper end and lower end of the rod legs.

[0105] The head joint device, the connection piece, the upper joint device, the rod legs, the lower joint device and / or the support foot may be at least partially monolithic.

[0106] It may be advantageous if the cross section of the rod legs is square or rectangular.

[0107] This results in optimal utilization of the cross section of the apparatus, in particular if the apparatus has exactly four rod legs. Moreover, this yields a high stiffness in the rod direction or in the longitudinal direction of the apparatus, and that has an advantageous effect on the holding characteristics of the apparatus.

[0108] It has proven to be advantageous if the acute angle between the rod legs is less than 15°, preferably less than 5° and particularly preferably less than 2°.

[0109] It may be especially advantageous if the virtual point of intersection in the extension of the rod legs lies at least half as far, preferably at least twice as far and particularly preferably at least four times as far beyond the holding point as the rod legs are long.

[0110] In a preferred configuration, the rod legs are between 50 mm and 300 mm, particularly preferably between 100 mm and 150 mm long.

[0111] It should be noted that the dimension of the acute angle, the distance between the virtual point of intersection and the holding point, and the length of the rod legs depend on one another, or preferably are selected for mutual compatibility.

[0112] The present invention also relates to a holding device for holding an optical element, in particular an optical element of a lithography system, at least comprising a first apparatus according to the invention and a second apparatus according to the invention, the first apparatus and the second apparatus converging towards one another on the direction of a common holding point at the optical element.

[0113] The first apparatus and the second apparatus are in particular apparatuses having one or more features according to the description above. The advantages similarly arise from the already-described advantages.

[0114] The present invention also relates to a holding device for holding an optical element, in particular an optical element of a lithography system, at least comprising a first apparatus and a second apparatus having a common holding point for connection to the optical element, wherein the common holding point is connected to a support of the first apparatus and to a support of the second apparatus. According to the invention, it is provided that the supports each comprise at least two rod legs and a connection piece, wherein the respective connection piece is arranged between the common holding point and an upper end, next to the common holding point, of the respective rod legs and connects the respective rod legs to one another, wherein the respective rod legs converge towards one another at an acute angle in the direction of the common holding point, and wherein a virtual point of intersection in the extension of the respective rod legs lies on the far side of the common holding point. It is provided that the first apparatus and the second apparatus converge towards one another in the direction of the common holding point at the optical element.

[0115] The holding device may in particular also be a bipod or referred to as a bipod.

[0116] The first apparatus and the second apparatus may preferably be apparatuses having one or more features according to the description above. The advantages similarly arise from the already-described advantages.

[0117] It can be particularly advantageous if the acute angle between the respective rod legs of the first apparatus, and / or the respective rod legs of the second apparatus, is less than 30°, preferably less than 15°, more preferably less than 5° and particularly preferably less than 2°.

[0118] The first apparatus and the second apparatus converge towards one another in particular in a V shape, at an angle, in the direction of the optical element.

[0119] At the level of the common holding point, a distance may remain between the first apparatus and the second apparatus, or virtual extensions of the first apparatus and of the second apparatus. The common holding point may in particular be in the form of a common holder, or holding device.

[0120] It may be advantageous if the first apparatus and the second apparatus at least approximately form a right angle with one another. This ensures the maximum possible stability of the holding device, or of the bipod. Moreover, the right angle means that feedback between the apparatuses during a movement, for example during a displacement actively performed by the actuator, of at least one of the two apparatuses is avoided.

[0121] An approximately right angle may in particular be an angle between 80° and 100°, preferably an angle between 85° and 95°, more preferably an angle between 88° and 92° and particularly preferably an angle of exactly 90°.

[0122] The plane, formed by the V shape of the first apparatus and the second apparatus converging towards one another at an angle, of the holding device is preferably perpendicular to the optical element, or the optical surface of the optical element. The plane ofthe holding device may, however, also be configured differently. In an advantageous further development of the invention, it may be provided that an actuator of the first apparatus for selective positioning and / or alignment of the optical element is arranged and designed in such a way as to displace a first support foot of the first apparatus, and / or an actuator of the second apparatus for selective positioning and / or alignment of the optical element is arranged and designed in such a way as to displace a second support foot of the second apparatus, in each case preferably at least along a longitudinal axis of the first apparatus and the second apparatus, respectively, in particular on the plane defined by the longitudinal axes of the first apparatus and the second apparatus.

[0123] In this further development, at least one of the two apparatuses has an actuator, so the rod legs of the respective apparatus can be jointly moved. In particular, the first apparatus and / or the second apparatus may have an actuator. With preference, both the first support foot and the second support foot are displaceable.

[0124] It can be advantageous if the respective support foot is displaceable in exactly two or in exactly three spatial directions.

[0125] In particular, the actuator of the first apparatus may be arranged and designed in such a way as to displace the first support foot along the longitudinal axis of the first apparatus and / or in the direction of the second support foot, and / or the actuator of the second apparatus may be arranged and designed in such a way as to displace the second support foot along the longitudinal axis of the second apparatus and / or in the direction of the first support foot.

[0126] The expression "in the direction of the first and the second support foot, respectively" encompasses both a displacement towards the first or second support foot, respectively, and away from the first or second support foot, respectively.

[0127] The holding device, or the bipod, can be adjusted using at least one actuator for example in accordance with the applicant's application DE 10 2018 200 178 A1 .

[0128] The present invention also relates to an arrangement for holding an optical element, in particular an optical element of a lithography system, at least comprising six apparatuses according to the invention or three holding devices according to the invention.

[0129] The arrangement according to the invention may in particular also be suitable for positioning and / or aligning the optical element.

[0130] The apparatuses or the holding devices are in particular apparatuses or holding devices having one or more features according to the description above. The advantages similarly arise from the already-described advantages. With preference, the arrangement has exactly six apparatuses according to the invention or exactly three holding devices according to the invention. Generally speaking, therefore, in particular all the degrees of freedom for positioning and / or aligning an optical element are sufficiently determined, if this is intended in addition to the holding function.

[0131] Mixtures of apparatuses and holding devices, in particular such that overall preferably exactly six apparatuses are present, it also being possible for two respective apparatuses to form a holding device, are possible.

[0132] According to the invention, it may in particular also be provided that the arrangement has for example four apparatuses according to the invention and a holding device according to the invention, with the holding device comprising two of the overall six apparatuses provided. Further combinations are similarly possible.

[0133] It should be noted that, if there are more than six apparatuses, it is also possible for the apparatuses to form more than three holding devices.

[0134] The combination of at least six apparatuses, or three holding devices, ensures a stable support for the optical element and at the same time the exploitation of the degrees of freedom for optionally positioning and / or aligning the optical element. The combination of exactly six apparatuses, or exactly three holding devices, to form a hexapod has proven to be particularly advantageous.

[0135] It may be advantageous if the apparatuses and / or the holding devices are at least approximately uniformly distributed around an outer peripheral region of the optical element. This increases the stability of the arrangement.

[0136] The apparatuses and / or the holding devices are to be regarded as at least approximately uniformly distributed around the outer peripheral region of the optical element in particular also if the respective position of the apparatuses and / or of the holding devices deviates from the position thereof in a completely uniform distribution by no more than 10%, preferably no more than 5% and more preferably no more than 2%.

[0137] The holding devices may in particular be aligned such that the V-shaped plane formed respectively by the first apparatus and the second apparatus, which converge towards one another at an angle, is tangential to a periphery of the optical element. The planes of the holding devices may, however, also be configured differently.

[0138] The invention also relates to a system comprising an optical element, in particular an optical element of a lithography system, and at least comprising six apparatuses according to the invention or three holding devices according to the invention for holding the optical element.

[0139] The positioning and / or alignment of the optical element may in particular also be provided. The apparatuses or the holding devices are in particular apparatuses or holding devices having one or more features according to the description above. The advantages similarly arise from the already-described advantages.

[0140] The number and the arrangement of the apparatuses according to the invention or of the holding devices according to the invention within the context of the system can be selected preferably as was already described with regard to the arrangement according to the invention. It may in particular be suitable if the system according to the invention comprises six apparatuses or three holding devices. Two respective apparatuses may possibly also form a holding device.

[0141] It may be provided that the optical element is a mirror or a lens element. In particular, it can be a mirror or a lens element of a lithographic system.

[0142] The present invention also relates to a method for holding and in particular for positioning and / or aligning an optical element, in particular an optical element of a lithography system, wherein the optical element is held and in particular positioned and / or aligned by means of at least one apparatus according to the invention and / or one holding device according to the invention or an arrangement according to the invention.

[0143] The apparatuses or the holding devices or the arrangement are in particular apparatuses or holding devices or an arrangement having one or more features according to the description above. The advantages similarly arise from the already-described advantages.

[0144] The present invention further relates to a lithography system, in particular a projection exposure apparatus for semiconductor lithography, comprising an illumination system with a radiation source and an optical unit which has at least one optical element, wherein the optical element is held by at least one apparatus according to the invention and / or one holding device according to the invention or an arrangement according to the invention.

[0145] The optical element can in particular also be positioned and / or aligned by at least one apparatus according to the invention and / or one holding device according to the invention or an arrangement according to the invention.

[0146] The apparatuses or the holding devices or the arrangement are in particular apparatuses or holding devices or an arrangement having one or more features according to the description above. The advantages similarly arise from the already-described advantages.

[0147] Lithography systems can in particular be projection exposure apparatuses for semiconductor lithography using EUV (extreme ultraviolet) light and / or DUV (deep ultraviolet) light. In these and related fields of use, it is especially important for the holding to be stable, or non-shaking, and possibly for the positioning to be stable, or non-shaking, and for optical elements to be exactly aligned, and at the same time for deformations of the optical elements to be avoided, in order to achieve a high imaging quality without imaging aberrations and thus be able to produce high-quality structures, in particular semiconductor structures.

[0148] Features described in conjunction with one of the subjects of the invention, specifically given by the apparatus according to the invention, the holding device according to the invention, the arrangement according to the invention, the system according to the invention, the method according to the invention or the lithography system according to the invention, can also advantageously be implemented for the other subjects of the invention. Likewise, advantages specified in conjunction with one of the subjects of the invention can also be understood in relation to the other subjects of the invention.

[0149] Additionally, it should be noted that terms such as "comprising", "having", or "with" do not exclude other features or steps. Furthermore, terms such as "a(n)" or "the" which indicate single steps or features do not exclude a plurality of features or steps - and vice versa.

[0150] However, in a puristic embodiment of the invention, provision may also be made for the features introduced in the invention using the terms "comprising", "having", or "with" to be an exhaustive enumeration. Accordingly, one or more enumerations of features can be considered to be exhaustive within the scope of the invention, for example respectively considered for each claim. For example, the invention can consist exclusively of the features specified in Claim 1.

[0151] It should be noted that designations such as "first" or "second", etc. are used predominantly to be able to distinguish between respective apparatus or method features and are not necessarily intended to indicate that features require one another or are related to one another.

[0152] Exemplary embodiments of the invention will be described in detail hereinbelow with reference to the drawing.

[0153] The figures each show preferred exemplary embodiments in which individual features of the present invention are illustrated in combination with one another. Features of an exemplary embodiment are also implementable independently of the other features of the same exemplary embodiment, and may readily be combined accordingly by a person skilled in the art to form further viable combinations and sub-combinations with features of other exemplary embodiments.

[0154] In the figures, functionally identical elements are given the same reference signs.

[0155] In the figures: Figure 1 shows a meridional section of an EUV projection exposure apparatus;

[0156] Figure 2 shows a DUV projection exposure apparatus;

[0157] Figure 3 shows a basic view of one embodiment of the apparatus according to the invention for holding an optical element;

[0158] Figure 4 shows a further basic view of the embodiment shown in Figure 3 of the apparatus according to the invention for holding an optical element;

[0159] Figure 5 shows a basic view of one embodiment of the holding device according to the invention for holding an optical element;

[0160] Figure 6 shows a basic view of one embodiment of the arrangement according to the invention and of the optical system according to the invention for holding an optical element;

[0161] Figure 7 shows a basic view of a further embodiment of the holding device according to the invention for holding an optical element;

[0162] Figure 8 shows a basic view of a further embodiment of the holding device according to the invention for holding an optical element;

[0163] Figure 9 shows a basic view of a further embodiment of the holding device according to the invention for holding an optical element; and

[0164] Figure 10 shows a basic view of a further embodiment of the holding device according to the invention for holding an optical element.

[0165] With reference to figure 1 , the essential components of a microlithographic EUV projection exposure apparatus 100 as an example of a lithography system are initially described below in exemplary fashion. The description of the basic structure of the EUV projection exposure apparatus 100 and of the component parts thereof should not be interpreted restrictively here.

[0166] An illumination system 101 of the EUV projection exposure apparatus 100 comprises, besides a radiation source 102, an illumination optical unit 103 for the illumination of an object field 104 in an object plane 105. In this case, a reticle 106 arranged in the object field 104 is exposed. The reticle 106 is held by a reticle holder 107. The reticle holder 107 is displaceable by way of a reticle displacement drive 108, in particular in a scanning direction. Figure 1 depicts a Cartesian xyz-coordinate system for illustrative purposes. The x-direction runs perpendicularly into the plane of the drawing. The y-direction runs horizontally, and the z-direction runs vertically. In Figure 1 , the scanning direction runs in the y-direction. The z-direction runs perpendicularly to the object plane 105.

[0167] The EUV projection exposure apparatus 100 comprises a projection optical unit 109. The projection optical unit 109 serves for imaging the object field 104 into an image field 110 in an image plane 111. The image plane 111 extends parallel to the object plane 105. As an alternative, an angle between the object plane 105 and the image plane 1 11 that differs from 0° is also possible.

[0168] A structure on the reticle 106 is imaged onto a light-sensitive layer of a wafer 112 arranged in the region of the image field 110 in the image plane 111. The wafer 112 is held by a wafer holder 113. The wafer holder 113 is displaceable by way of a wafer displacement drive 1 14, in particular along the y-direction. The displacement on the one hand of the reticle 106 by way of the reticle displacement drive 108 and on the other hand of the wafer 112 by way of the wafer displacement drive 1 14 may take place in such a way as to be synchronized with one another.

[0169] The radiation source 102 is an EUV radiation source. The radiation source 102 emits in particular EUV radiation 115, which in the following text is also referred to as used radiation or illumination radiation. The used radiation 115 has in particular a wavelength in the range between 5 nm and 30 nm. The radiation source 102 can be a plasma source, for example an LPP source ("laser produced plasma") or a GDPP source ("gas discharged produced plasma"). It can also be a synchrotron-based radiation source. The radiation source 102 can be a free electron laser (FEL).

[0170] The illumination radiation 115 emanating from the radiation source 102 is focused by a collector 116. The collector 116 may be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 116 can be impinged upon by the illumination radiation 115 with grazing incidence (Gl), i.e. with angles of incidence greater than 45°, or with normal incidence (Nl), i.e. with angles of incidence less than 45°. The collector 116 can be structured and / or coated, firstly to optimize its reflectivity for the used radiation 115 and secondly to suppress extraneous light.

[0171] Downstream of the collector 116, the illumination radiation 115 propagates through an intermediate focus in an intermediate focal plane 117. The intermediate focal plane 117 can constitute a separation between a radiation source module, comprising the radiation source 102 and the collector 116, and the illumination optical unit 103.

[0172] The illumination optical unit 103 comprises a deflection mirror 118 and, disposed downstream thereof in the beam path, a first facet mirror 119. The deflection mirror 118 can be a plane deflection mirror or, alternatively, a mirror with a beam-influencing effect that goes beyond the purely deflecting effect. Alternatively or additionally, the deflection mirror 118 may be in the form of a spectral filter, which separates a used light wavelength of the illumination radiation 115 from extraneous light of a different wavelength. If the first facet mirror 119 is arranged in a plane of the illumination optical unit 103 that is optically conjugate to the object plane 105 as a field plane, it is also referred to as a field facet mirror. The first facet mirror 119 comprises a multiplicity of individual first facets 120, which are also referred to below as field facets. Only a few of these facets 120 are illustrated in Figure 1 by way of example.

[0173] The first facets 120 may take the form of macroscopic facets, in particular rectangular facets or facets with an arc-shaped edge contour or part-circle-shaped edge contour. The first facets 120 may be in the form of plane facets or alternatively as convexly or concavely curved facets.

[0174] As is known for example from DE 10 2008 009 600 A1 , the first facets 120 themselves may each also be composed of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. In particular, the first facet mirror 119 can be in the form of a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1 .

[0175] The illumination radiation 1 15 travels horizontally, i.e. in the y-direction, between the collector 116 and the deflection mirror 118.

[0176] In the beam path of the illumination optical unit 103, a second facet mirror 121 is disposed downstream of the first facet mirror 119. If the second facet mirror 121 is arranged in a pupil plane of the illumination optical unit 103, it is also referred to as a pupil facet mirror. The second facet mirror 121 may also be arranged at a distance from a pupil plane of the illumination optical unit 103. In this case, the combination of the first facet mirror 119 and the second facet mirror 121 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.

[0177] The second facet mirror 121 comprises a plurality of second facets 122. In the case of a pupil facet mirror, the second facets 122 are also referred to as pupil facets.

[0178] The second facets 122 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 .

[0179] The second facets 122 may have plane or, alternatively, convexly or concavely curved reflection surfaces.

[0180] The illumination optical unit 103 thus forms a doubly faceted system. This basic principle is also referred to as fly's eye integrator.

[0181] It may be advantageous to arrange the second facet mirror 121 not exactly in a plane that is optically conjugate to a pupil plane of the projection optical unit 109. With the aid of the second facet mirror 121 , the individual first facets 120 are imaged into the object field 104. The second facet mirror 121 is the last beam-shaping mirror or actually the last mirror for the illumination radiation 115 in the beam path upstream of the object field 104.

[0182] In a further embodiment, which is not illustrated, of the illumination optical unit 103, a transfer optical unit may be arranged in the beam path between the second facet mirror 121 and the object field 104 and contributes in particular to the imaging of the first facets 120 into the object field 104. The transfer optical unit can have exactly one mirror or, alternatively, two or more mirrors, which are arranged in succession in the beam path of the illumination optical unit 103. In particular, the transfer optical unit can comprise one or two normal incidence mirrors (Nl mirrors) and / or one or two grazing incidence mirrors (Gl mirrors).

[0183] In the embodiment shown in Figure 1 , the illumination optical unit 103 comprises exactly three mirrors downstream of the collector 116, specifically the deflection mirror 118, the field facet mirror 119 and the pupil facet mirror 121 .

[0184] In a further embodiment of the illumination optical unit 103, the deflection mirror 118 may also be omitted, and so the illumination optical unit 103 may then have exactly two mirrors downstream of the collector 116, specifically the first facet mirror 119 and the second facet mirror 121 .

[0185] The imaging of the first facets 120 into the object plane 105 by means of the second facets 122, or using the second facets 122, and a transfer optical unit is generally only an approximate imaging.

[0186] The projection optical unit 109 comprises a plurality of mirrors Mi, which are numbered in accordance with their arrangement in the beam path of the EUV projection exposure apparatus 100.

[0187] In the example illustrated in Figure 1 , the projection optical unit 109 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 115. The projection optical unit 109 is a doubly obscured optical unit. The projection optical unit 109 has an imageside numerical aperture which is greater than 0.5 and which can also be greater than 0.6 and, for example, can be 0.7 or 0.75.

[0188] Reflection surfaces of the mirrors Mi may be in the form of free-form surfaces without an axis of rotational symmetry. Alternatively, 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 optical unit 103, the mirrors Mi may have highly reflective coatings for the illumination radiation 115. These coatings may take the form of multilayer coatings, in particular with alternating layers of molybdenum and silicon. The projection optical unit 109 has a large object-image shift in the y-direction between a y-coordinate of a centre of the object field 104 and a y-coordinate of the centre of the image field 110. This object-image offset in the y-direction can be of approximately the same magnitude as a z-distance between the object plane 105 and the image plane 111.

[0189] The number of intermediate image planes in the x-direction and in the y-direction in the beam path between the object field 104 and the image field 110 can be the same or can, depending on the embodiment of the projection optical unit 109, be different. Examples of projection optical units with different numbers of such intermediate images in the x- and y-directions are known from US 2018 / 0074303 A1.

[0190] A respective one of the pupil facets 122 is assigned to exactly one of the field facets 120, in each case to form an illumination channel for illuminating the object field 104. This may in particular result in illumination according to the Kohler principle. The far field is deconstructed into a multiplicity of object fields 104 by means of the field facets 120. The field facets 120 create a plurality of images of the intermediate focus on the pupil facets 122 in each case assigned thereto.

[0191] The field facets 120 are each imaged by an assigned pupil facet 122 onto the reticle 106 in a manner overlaid on one another in order to illuminate the object field 104. The illumination of the object field 104 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.

[0192] The illumination of the entrance pupil of the projection optical unit 109 may be defined geometrically by way of an arrangement of the pupil facets. The intensity distribution in the entrance pupil of the projection optical unit 109 can be set by selecting the illumination channels, in particular the subset of the pupil facets that guide light. This intensity distribution is also referred to as illumination setting.

[0193] A likewise preferred pupil uniformity in the region of portions of an illumination pupil of the illumination optical unit 103 that are illuminated in a defined way can be achieved by a redistribution of the illumination channels.

[0194] Further aspects and details of the illumination of the object field 104 and in particular of the entrance pupil of the projection optical unit 109 are described below.

[0195] The projection optical unit 109 can have in particular a homocentric entrance pupil. The latter may be accessible. It may also be inaccessible.

[0196] The entrance pupil of the projection optical unit 109 generally cannot be illuminated exactly by means of the pupil facet mirror 121. The aperture rays often do not intersect at a single point when the imaging by the projection optical unit 109 telecentrically images the centre of the pupil facet mirror 121 onto the wafer 112. 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.

[0197] It may be the case that the projection optical unit 109 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 optical unit, should be provided between the second facet mirror 121 and the reticle 106. With the aid of this optical component, it is possible to take account of the different pose of the tangential entrance pupil and the sagittal entrance pupil.

[0198] In the arrangement of the components of the illumination optical unit 103 illustrated in Figure 1 , the pupil facet mirror 121 is arranged in an area conjugate to the entrance pupil of the projection optical unit 109. The first field facet mirror 119 is tilted in relation to the object plane 105. The first facet mirror 119 is tilted in relation to an arrangement plane defined by the deflection mirror 118.

[0199] The first facet mirror 1 19 is tilted in relation to an arrangement plane defined by the second facet mirror 121.

[0200] Figure 2 shows an exemplary DUV projection exposure apparatus 200. The DUV projection exposure apparatus 200 comprises an illumination system 201 , a device known as a reticle stage 202 for receiving and exactly positioning a reticle 203 by which the later structures on a wafer 204 are determined, a wafer holder 205 for holding, moving, and exactly positioning the wafer 204, and an imaging device, specifically a projection optical unit 206, with a plurality of optical elements, in particular lens elements 207, which are held by way of mounts 208 in a lens housing 209 of the projection optical unit 206.

[0201] As an alternative or in addition to the lens elements 207 illustrated, provision can be made of various refractive, diffractive, and / or reflective optical elements, inter alia also mirrors, prisms, terminating plates, and the like.

[0202] The basic functional principle of the DUV projection exposure apparatus 200 makes provision for the structures introduced into the reticle 203 to be imaged onto the wafer 204.

[0203] The illumination system 201 provides a projection beam 210 in the form of electromagnetic radiation, which is required for the imaging of the reticle 203 onto the wafer 204. The source used for this radiation may be a laser, a plasma source, or the like. The radiation is shaped in the illumination system 201 by means of optical elements such that the projection beam 210 has the desired properties with regard to diameter, polarization, shape of the wavefront, and the like when it is incident on the reticle 203.

[0204] By means of the projection beam 210, an image of the reticle 203 is created and transferred from the projection optical unit 206 onto the wafer 204 in an appropriately reduced form. In this case, the reticle 203 and the wafer 204 can be moved synchronously, so that regions of the reticle 203 are imaged onto corresponding regions of the wafer 204 virtually continuously during what is called a scanning operation.

[0205] An air gap between the last lens element 207 and the wafer 204 can optionally be replaced by a liquid medium which has a refractive index of greater than 1.0. The liquid medium can be, for example, high- purity water. Such a set-up is also referred to as immersion lithography and has an increased photolithographic resolution.

[0206] The use of the invention is not restricted to use in projection exposure apparatuses 100, 200, in particular also not with the described set-up. The invention is suitable for any desired lithography systems or microlithography systems, but in particular for projection exposure apparatuses having the described set-up. The invention is also suitable for EUV projection exposure apparatuses which have a smaller image-side numerical aperture than those described in the context of Figure 1 , and have no obscured mirror M5 and / or M6. In particular, the invention is also suitable for EUV projection exposure apparatuses which have an image-side numerical aperture from 0.25 to 0.5, preferably 0.3 to 0.4, particularly preferably 0.33. The invention and the following exemplary embodiments should also not be understood as being restricted to a specific design.

[0207] The figures that follow illustrate the invention merely by way of example and in highly schematized form.

[0208] Figure 3 shows a basic view of one embodiment of the apparatus 1 according to the invention for holding an optical element 2, which is not shown in Figure 3. The apparatus 1 has a holding point 5 for connection to the optical element 2, the holding point 5 being connected to a support 3. Within the context of the invention, it is provided that the support 3 has at least two rod legs 3a and a connection piece 15, which is arranged between the holding point 5 and an upper end 9a, next to the holding point 5, of the rod legs 3a. The rod legs 3a converge towards one another at an acute angle 6 in the direction of the holding point 5, wherein the acute angle 6 between the rod legs 3a is less than 30°, and wherein a virtual point of intersection 7 in the extension of the rod legs 3a lies on the far side of the holding point 5.

[0209] In the exemplary embodiments, as presented in more detail below, the support 3 or the rod legs 3a of the apparatus 1 are preferably connected to the holding point 5. The connection may in particular be formed by the connection piece 15 of the rod legs 3a and optionally further elements in between.

[0210] At the level of the holding point 5, which at least partially supports the optical element 2 when used as intended, a distance remains between the virtual extensions (dashed lines) of the rod legs 3a. That is to say, the rod legs 3a, or the virtual extensions of the rod legs 3a, do not intersect in the holding point 5, or do not have a common point of intersection in the holding point 5. The rod legs 3a also do not have a common point of intersection at the level of the connection piece 15. It has proven to be advantageous if a head joint device 16 arranged between the connection piece 15 and the holding point 5 is provided. This at least partially establishes the connection between the support 3 and the holding point 5. Moreover, the head joint device 16 preferably makes the apparatus 1 tiltable with respect to the holding point 5.

[0211] The support 3 may have a support foot 11 , wherein the support foot 11 is arranged at a lower end 9b, remote from the holding point 5, of the rod legs 3a and connects the rod legs 3a to one another.

[0212] The support 3 can be movable by an actuator 4 for selective positioning and / or alignment of the optical element 2, preferably at least along a longitudinal axis 14 of the apparatus 1 . The rod legs 3a of the support 3 can be moved by the actuator 4 jointly, in particular at the same time in an at least approximately identical direction. This allows the apparatus 1 to, in addition to its holding function, also advantageously position and / or align the optical element 2 with reduced deformation.

[0213] The actuator 4 can be connected to the support foot 11 . The actuator 4 can, however, also be formed in one piece with the support foot 11 .

[0214] The support 3 may have a compensation element 8a, 8b, which is arranged and designed such that the position of the rod legs 3a relative to one another can be varied. This makes it possible to reduce deformations of the optical element 2 that can be caused for example by differences in thermal expansion of the components and / or by a movement of the rod legs 3a, by means of interaction between the rod legs 3a, the compensation element 8a, 8b and the connection piece 15, by counteracting a tilting of the holding point 5 relative to the optical element 2.

[0215] The kinematic mechanism of the rod legs 3a, the connection piece 15 and the compensation element 8a, 8b, or the rod kinematic mechanism, can act preferably perpendicularly to a longitudinal axis 14 of the apparatus 1 or of the rod kinematic mechanism, in particular by the rod kinematic mechanism being movable perpendicular to the longitudinal axis 14, or pivotable about the virtual point of intersection 7. The head joint device 16 can also contribute to this, or this can be enabled at least partially by the tiltability of the head joint device 16.

[0216] With preference, the rod kinematic mechanism can perform a compensation movement, or a counter-tilting that counters a parasitic torque, about the current centre of rotation, or virtual point of intersection 7. This makes it possible to at least partially compensate for a parasitic torque, which can be unintentionally caused, for example, by a transverse force, exerted on the holding point 5 perpendicularly to the longitudinal axis 14, for an intended transverse displacement. Otherwise, the parasitic torque would be taken up by the optical element 2 in that the holding point 5 would tilt, and possibly lead to an unintentional deformation of the optical element 2. In particular, the compensation element 8a, 8b of the rod kinematic mechanism, possibly assisted by the connection piece 15 and / or the head joint device 16, can tilt instead of the holding point 5 within the scope ofthe invention. The relative position of the rod legs 3a depends on the tilting of the compensation element 8a, 8b, and so the relative position of the rod legs 3a relative to one another is displaced during the compensation movement. For further illustration, reference is also made to Figure 4.

[0217] Figure 3 also schematically indicates the z-positions of the head joint device 16 (zB), of the rod legs 3a (zs) and of the virtual point of intersection 7 of the rod legs 3a, or the current centre of rotation of the rod kinematic mechanism (zB), and also the angle formed by the rod legs 3a with the longitudinal axis 14 ofthe apparatus 1 or of the rod kinematic mechanism (ps), which should satisfy equation (1) together with other variables, which include various stiffness values. The freely selected origin of the coordinate system in Figure 3 lies such that it coincides with the holding point 5.

[0218] The compensation element is preferably in the form of an upper joint device 8a, which is arranged on the upper end 9a of the rod legs 3a. The upper joint device 8a articulatedly connects the rod legs 3a to the connection piece 15, the upper joint device 8a together with the connection piece 15 forming an operative connection between the rod legs 3a. As an alternative or in addition, the compensation element may also be in the form of a lower joint device 8b, which is arranged on the lower end 9b of the rod legs 3a. The lower joint device 8b can articulatedly connect the rod legs 3a to the support foot 11 of the apparatus 1 and / or to the actuator 4.

[0219] The rod legs 3a may preferably be rigid, in particular in the axial direction. The rod legs 3a may, however, also be flexible, in particular in the radial, or transverse, direction.

[0220] The embodiment shown in Figure 3 of the apparatus 1 has two rod legs 3a. The apparatus 1 can preferably also have three or four rod legs 3a, the rod legs 3a being in a conical arrangement relative to one another, in particular at acute angles 6 analogously to Figure 3.

[0221] The head joint device 16 is preferably arranged directly on the holding point 5.

[0222] The upper joint device 8a and / or the lower joint device 8b may have a plurality of joints. The head joint device 16 may also have a plurality of joints.

[0223] The one or more joints of the upper joint device 8a, of the lower joint device 8b and / or of the head joint device 16 may be wire joints or leaf-spring joints, but also other types of joints.

[0224] The cross section of the rod legs 3a may preferably be square, but may also be round or have another shape, in particular a rectangular shape. With preference, the acute angle 6 between the rod legs 3a is less than 15°, preferably less than 5° and particularly preferably less than 2°. The angle 6 is shown on a larger scale in Figure 3 for illustrative purposes.

[0225] It is also preferred if the virtual point of intersection 7 in the extension of the rod legs 3a lies at least half as far, preferably at least twice as far and particularly preferably at least four times as far beyond the holding point 5 as the rod legs 3a are long. Figure 3 illustrates the distance between the virtual point of intersection 7 and the holding point 5 on a smaller scale for illustrative purposes and as an adaptation to the angle 6 shown on a larger scale.

[0226] Figure 4 shows a further basic view of the embodiment shown in Figure 3 of the apparatus 1 according to the invention for holding an optical element 2. To illustrate the functional principle, the apparatus 1 is, in addition to the positioning in the base position (solid lines) already shown in Figure 3, also shown alter a transverse displacement, or deflection, ofthe holding point 5 perpendicularly to a longitudinal axis 14 of the apparatus 1 (dashed lines).

[0227] In particular, Figure 4 shows that the holding point 5 is not tilted relative to the optical element 2, or in comparison with the base position, because an unintentional, or parasitic, torque acting at the same time as the transverse force is compensated for by the joints ofthe upper joint device 8a, ofthe lower joint device 8b and of the head joint device 16, and by the connection piece 15 and the rod legs 3a, the positions of which relative to one another are changed after the deflection. This makes it possible to reduce or prevent deformations ofthe optical element 2, which is fastened to the holding point 5. This effect is achieved mainly by the position ofthe virtual point of intersection 7 on the farside ofthe holding point s, or the corresponding arrangement of at least two rod legs 3a, which are coupled by the connection piece 15, at an acute angle 6 to one another.

[0228] Figure 5 shows a basic view of one embodiment of the holding device 10 according to the invention for holding an optical element 2. The holding device 10 has a first apparatus 1a and a second apparatus 1 b, which preferably both having the features of an apparatus 1 according to the invention and which have a common holding point 5 for connection to the optical element 2. The first apparatus 1 a and the second apparatus 1 b converge towards one another in the direction of the common holding point 5 at the optical element 2.

[0229] The common holding point 5 is connected to the support 3 of the first apparatus 1a and a support 3 of the second apparatus 1 b. The supports 3 each comprise at least two rod legs 3a and a connection piece 15, wherein the respective connection piece 15 is arranged between the common holding point 5 and an upper end 9a, next to the common holding point 5, of the respective rod legs 3a and connects the respective rod legs 3a to one another, wherein the respective rod legs 3a, i.e. the rod legs 3a of the first apparatus 1 a and the rod legs 3a of the second apparatus 1 b, converge towards one another at an acute angle 6 in the direction of the common holding point 5, and wherein a virtual point of intersection 7 in the extension ofthe respective rod legs 3a lies on the far side of the common holding point 5. With preference, the acute angle 6 between the respective rod legs 3a may be less than 30°.

[0230] It should be noted that the first apparatus 1 a and the second apparatus 1 b each correspond to an apparatus 1 and in principle can be exchanged, since the designations of "first" and "second" are used primarily to be able to distinguish between them. In particular, the first apparatus 1a and the second apparatus 1 b may be apparatuses 1 according to Figures 3 and 4.

[0231] The first apparatus 1 a and the second apparatus 1 b of the holding device 10 according to Figure 5 preferably form at least approximately a right angle with one another. They may, however, also form another angle with one another.

[0232] The acute angle 6 between the rod legs 3a of the first apparatus 1 a and of the second apparatus 1 b can be spatially aligned as desired relative to the optical element 2 and with respect to the angle between the first apparatus 1 a and the second apparatus 1 b, depending on the desired direction of action of the apparatus 1 , 1 a, 1 b of the holding device 10.

[0233] An actuator 4 of the first apparatus 1a can, for selective positioning and / or alignment of the optical element 2, be arranged and designed to displace a first support foot 11 a of the first apparatus 1 a. As an alternative or in addition, an actuator 4 of the second apparatus 1 b can, for selective positioning and / or alignment of the optical element 2, be arranged and designed to displace a second support foot 11 b of the second apparatus 1 b. The respective displacement by the actuator 4 of the first apparatus 1 a and / or the second apparatus 1 b can take place preferably at least along a longitudinal axis 14 of the first apparatus 1 a and / or the second apparatus 1 b, in particular on the plane defined by the longitudinal axes 14 of the first apparatus 1 a and the second apparatus 1 b.

[0234] In particular, in Figure 5 arrows are used to also indicate that the actuator 4 of the first apparatus 1a can be arranged and designed to displace the first support foot 11 a along the longitudinal axis 14 of the first apparatus 1 a and / or in the direction of the second support foot 11 b. As an alternative or in addition, it may also be provided that the actuator 4 of the second apparatus 1 b is arranged and designed to displace the second support foot 11 b along the longitudinal axis 14 of the second apparatus 1 b and / or in the direction of the first support foot 11a.

[0235] Figure 6 shows a basic view of one embodiment of the arrangement 12 according to the invention and of the optical system 13 according to the invention for holding an optical element 2. The arrangement 12 has at least six apparatuses 1 according to the invention, preferably two respective apparatuses 1 being able to form a holding device 10 according to the invention, or has at least three holding devices 10 according to the invention. In particular, each of the holding devices 10 has two apparatuses 1. Instead of the arrangement in pairs of apparatuses 1 in the form of holding devices 10, the apparatuses 1 could, however, also be arranged individually. With preference, exactly six apparatuses 1 are provided for the arrangement 12 according to the invention, or the system 13 according to the invention. The apparatuses 1 can be used individually or in pairs, to form a respective holding device 10, in order to hold the optical element 2. With preference, three holding devices 10 are provided.

[0236] The holding devices 10 are preferably in the form of bipods. The two legs of a bipod can each be formed by an apparatus 1 according to the invention, each of these apparatuses having at least two rod legs 3a.

[0237] With preference, the apparatuses 1 and / or the holding devices 10 are at least approximately uniformly distributed around an outer peripheral region of the optical element 2.

[0238] The V-shaped holding devices 10 can be arranged preferably tangentially to the periphery of the optical element 2. The holding devices 10 are preferably aligned perpendicularly to the optical element 2, or an optical surface 2a of the optical element 2. The holding devices 10 may, however, also be arranged and / or aligned differently.

[0239] In a preferred configuration of the invention, the holding devices 10 are also intended to position and / or align the optical element 2.

[0240] When the embodiment shown of the arrangement 12 of apparatuses 1 , or holding devices 10, is considered together with the optical element 2, a system 13 according to the invention is obtained. The system 13 thus comprises the optical element 2, at least six apparatuses 1 according to the invention, two respective apparatuses 1 being able to form a holding device 10 according to the invention, or has at least three holding devices 10 according to the invention for holding the optical element 2. The optical element 2 can in particular be a mirror or a lens element.

[0241] Figures 7 to 9 each show a basic view of a further embodiment of the holding device 10 according to the invention for holding an optical element 2. By contrast to the embodiment according to Figure 5, the apparatuses 1 , or 1a, 1 b, each have four rod legs 3a with a square cross section. This makes optimum use of the cross section of the respective apparatus 1 , or 1 a, 1 b, and yields a high stiffness in the rod direction.

[0242] The compensation element is preferably in the form of an upper joint device 8a and / or a lower joint device 8b analogously to the description above. The upper joint device 8a and / or the lower joint device 8b may in particular have a plurality of joints. The joints of the upper joint device 8a and / or of the lower joint device 8b may be arranged in different planes as viewed in the axial direction of the rod legs 3a, or along the longitudinal axis 14 of the apparatus 1. The joints may be arranged and designed in particular such that the joint or the joints located in a first plane enable a deflection in a first direction and the joint or the joints located in a second plane enable a deflection in a second direction orthogonal thereto, the two directions running in a surface area and the surface area, or plane, running preferably orthogonally to the longitudinal axis 14 of the apparatus 1 . Similarly, the head joint device 16 may also be formed by a plurality of joints, which may be arranged in different planes and preferably can be deflected in mutually orthogonal directions.

[0243] Figures 8 and 9 show in particular various arrangements of joints, which are preferably in the form of leafspring joints, for forming the compensation element or the upper joint device 8a and / or the lower joint device 8b. In the two embodiments, a head joint device 16, which can be formed in different planes by joints that have been rotated by 90° relative to one another, is fastened between the holding point 5 and the connection piece 15.

[0244] First joints 8c of the upper joint device 8a are fastened to the connection piece 15 and are connected to a respective intermediate element 8d of the upper joint device 8a. In particular, the exemplary embodiment according to Figure 8 has four first joints 8c, or four intermediate elements 8d. The exemplary embodiment according to Figure 9 has two first joints 8c, or two intermediate elements 8d.

[0245] Respective second joints 8e of the upper joint device 8a may be fastened to the intermediate elements 8d and are connected to the respective upper end 9a of one of the rod legs 3a. The exemplary embodiments according to Figures 8 and 9 have in particular four second joints 8e for the four rod legs 3a.

[0246] The first joints 8c may alternatively also be connected in each case to the upper end 9a of one of the rod legs 3a, with no intermediate elements 8d and no second joints 8e being provided.

[0247] It may be advantageous if, as viewed in the axial direction of the rod legs 3a, at least two adjacent joints of the upper joint device 8a and / or of the lower joint device 8b have been rotated by 90° relative to one another, the joints being in particular the first joints 8c and the second joints 8e. Figures 8 and 9 show this by way of example, the first joints 8c being rotated by 90° relative to the second joints 8e.

[0248] The lower joint device 8b can have a similar construction to the upper joint device 8a. In the exemplary embodiment according to Figure 8, in sequence starting from the support foot 11 or the actuator 4, in particular four first joints, four intermediate elements and four second joints are provided for the lower joint device 8b. In the exemplary embodiment according to Figure 9, similarly two first joints, two intermediate elements and four second joints are provided for the lower joint device 8b. The first joints are each fastened to the support foot 11 or the actuator 4 and the second joints are each connected to the lower end 9b of one of the rod legs 3a.

[0249] The actuators 4 in the exemplary embodiments according to Figures 7 to 9 may preferably be arranged and designed such that the assigned support foot 11a and 11 b can be displaced in the axial direction of the assigned rod leg 3a, or along the longitudinal axis 14, which corresponds to the axial direction, and / or in the direction of the support foot 11 a or 11 b of the respective other apparatus 1a, 1 b. The exemplary embodiments according to Figures 7 to 9 are also to be understood as only one apparatus 1 according to the invention in each case for the purposes of disclosure.

[0250] Not illustrated in the exemplary embodiment, but possible in principle, is for three respective apparatuses 1 according to the invention to be assembled to form a common device, these apparatuses converging towards one another at a common holding point 5, the rod legs 3a of the apparatuses 1 also each converging towards one another. With preference, in that case two such devices are provided in order to hold an optical element 2.

[0251] Figure 10 shows a basic view of a further embodiment of the holding device 10 according to the invention for holding an optical element 2. The main arrangement of the components is similar to that according to Figures 5, 7, 8 and 9. In the embodiment according to Figure 10, the apparatuses 1 , 1 a, 1 b each have two rod legs 3a with a square cross section. The respective joints of the head joint device 16, of the upper joint device 8a and / or of the lower joint device 8b are preferably formed by leaf-spring joints. The respective support 3, in particular the head joint device 16, the connection piece 15, the upper joint device 8a, the rod legs 3a, the lower joint device 8b and / or the support foot 11 , 11 a, 11 b may be at least partially monolithic.

[0252] In this embodiment, the apparatuses 1 , 1 a, 1 b, or the rod kinematic mechanisms, act in particular in the radial direction of the optical element 2 when the holding device 10, similarly to Figure 6, is arranged tangentially around the outer peripheral region, or periphery, of the optical element 2. The embodiment of Figure 10 is preferably combined in order that the actuator 4 is arranged and designed such that the support foot 11a and / or 11 b of the apparatus 1 a and / or 1 b is displaceable in the direction of the respective other support foot 11 b or 11 a, respectively.

[0253] Figures 3 to 10 also serve to disclose a method according to the invention for holding and in particular for positioning and / or aligning an optical element 2, wherein the optical element 2 is held and in particular positioned and / or aligned by means of at least one apparatus 1 according to the invention and / or one holding device 10 according to the invention or an arrangement 12 according to the invention.

[0254] The exemplary embodiments according to Figures 3 to 10 of the apparatus 1 according to the invention, the holding apparatus 10 according to the invention, the arrangement 12 according to the invention, the system 13 according to the invention and the method according to the invention are especially suitable for holding, and optionally for positioning and / or aligning, an optical element 2 of a lithography system. The optical element 2 may be in particular an optical element 116, 118, 119, 120, 121 , 122, Mi, 207 of a projection exposure apparatus 100, 200 for semiconductor lithography, comprising an illumination system 101 , 201 with a radiation source 102 and an optical unit 103, 109, 206, according to Figures 1 and 2. According to the invention, at least one of the optical elements 116, 118, 119, 120, 121 , 122, Mi, 207 is held, and optionally positioned and / or aligned, by at least one apparatus 1 according to the invention and / or one holding device 10 according to the invention or an arrangement 12 according to the invention. List of reference signs

[0255] 1 Apparatus

[0256] 1a First apparatus

[0257] 1b Second apparatus

[0258] 2 Optical element

[0259] 2a Optical surface

[0260] 3 Support

[0261] 3a Rod leg

[0262] 4 Actuator

[0263] 5 Holding point

[0264] 6 Acute angle

[0265] 7 Virtual point of intersection

[0266] 8a Compensation element, upper joint device

[0267] 8b Compensation element, lower joint device

[0268] 8c First joint

[0269] 8d Intermediate element

[0270] 8e Second joint

[0271] 9a Upper end (of the rod leg 3)

[0272] 9b Lower end (of the rod leg 3)

[0273] 10 Holding device

[0274] 11 Support foot (of the apparatus 1)

[0275] 11a First support foot (of the first apparatus 1 a)

[0276] 11 b Second support foot (of the second apparatus 1 b)

[0277] 12 Arrangement

[0278] 13 System

[0279] 14 Longitudinal axis (of the apparatus 1)

[0280] 15 Connection piece

[0281] 16 Head joint device

[0282] 100 EUV projection exposure apparatus

[0283] 101 Illumination system

[0284] 102 Radiation source

[0285] 103 Illumination optical unit

[0286] 104 Object field

[0287] 105 Object plane

[0288] 106 Reticle

[0289] 107 Reticle holder

[0290] 108 Reticle displacement drive

[0291] 109 Projection optical unit 110 Image field

[0292] 111 Image plane

[0293] 112 Wafer

[0294] 113 Wafer holder

[0295] 114 Wafer displacement drive

[0296] 115 EUV / used / illumination radiation

[0297] 116 Collector

[0298] 117 Intermediate focal plane

[0299] 118 Deflection mirror

[0300] 119 First facet mirror / field facet mirror

[0301] 120 First facets / field facets

[0302] 121 Second facet mirror / pupil facet mirror

[0303] 122 Second facets / pupil facets

[0304] 200 DUV projection exposure apparatus

[0305] 201 Illumination system

[0306] 202 Reticle stage

[0307] 203 Reticle

[0308] 204 Wafer

[0309] 205 Wafer holder

[0310] 206 Projection optical unit

[0311] 207 Lens

[0312] 208 Mount

[0313] 209 Lens housing

[0314] 210 Projection beam

[0315] Mi Mirrors

Claims

Claims:

1. Apparatus (1) for holding an optical element (2), in particular an optical element of a lithography system, having a holding point (5) for connection to the optical element (2), the holding point (5) being connected to a support (3), characterized in that the support (3) comprises at least two rod legs (3a) and a connection piece (15), wherein the connection piece (15) is arranged between the holding point (5) and an upper end (9a), next to the holding point (5), of the rod legs (3a) and connects the rod legs (3a) to one another, wherein the rod legs (3a) converge towards one another at an acute angle (6) in the direction of the holding point (5), wherein the acute angle (6) between the rod legs (3a) is less than 30°, and wherein a virtual point of intersection (7) in the extension of the rod legs (3a) lies on the far side of the holding point (5).

2. Apparatus (1) according to Claim 1 , characterized in that a head joint device (16) is provided, wherein the head joint device (16) is arranged between the connection piece (15) and the holding point (5).

3. Apparatus (1) according to Claim 1 or 2, characterized in that the support (3) has a support foot (1 1), wherein the support foot (11) is arranged at a lower end (9b), remote from the holding point (5), of the rod legs (3a) and connects the rod legs (3a) to one another.

4. Apparatus (1) according to Claim 1 , 2 or 3, characterized in that the support (3) can be moved by an actuator (4) for selective positioning and / or alignment of the optical element (2), wherein the rod legs (3a) of the support (3) can be moved by the actuator (4) jointly, preferably at least along a longitudinal axis (14) of the apparatus (1).

5. Apparatus (1) according to Claim 4, characterized in that the actuator (4) is operatively connected to the support foot (11) and / or is formed in one piece with the support foot (11).

6. Apparatus (1) according to one of Claims 1 to 5, characterized in that the support (3) has a compensation element (8a, 8b), wherein the compensation element (8a, 8b) is arranged and designed such that the position of the rod legs (3a) relative to one another can bevaried to reduce deformations of the optical element (2) by means of interaction between the rod legs (3a), the compensation element (8a, 8b) and the connection piece (15), in order to counteract a tilting of the holding point (5) relative to the optical element (2).

7. Apparatus (1) according to Claim 6, characterized in that the compensation element is in the form of an upper joint device (8a), which is arranged on the upper end (9a) of the rod legs (3a) and articulatedly connects the rod legs (3a) to the connection piece (15), and / or the compensation element is in the form of a lower joint device (8b), which is arranged on the lower end (9b) of the rod legs (3a) and articulatedly connects the rod legs (3a) to the support foot (11) of the apparatus (1) and / or to the actuator (4).

8. Apparatus according to one of Claims 1 to 7, characterized in that the rod legs (3a) are rigid, in particular in the axial direction.

9. Apparatus according to one of Claims 1 to 7, characterized in that the rod legs (3a) are flexible, in particular in the radial direction.

10. Apparatus (1) according to one of Claims 1 to 9, characterized in that the apparatus has two, three or four rod legs (3a), the rod legs (3a) having a conical arrangement.11 . Apparatus (1) according to one of Claims 2 to 10, characterized in that the head joint device (16) is arranged directly on the holding point (5).

12. Apparatus (1) according to one of Claims 7 to 11 , characterized in that the upper joint device (8a) and / or the lower joint device (8b) has a plurality of joints.

13. Apparatus (1) according to one of Claims 7 to 12, characterized in that first joints (8c) of the upper joint device (8a) are fastened to the connection piece (15) and are connected to the respective upper end (9a) of one of the rod legs (3a) or to a respective intermediate element (8d) of the upper joint device (8a).

14. Apparatus according to Claim 13, characterized in thatrespective second joints (8e) of the upper joint device (8a) are fastened to the intermediate elements (8d) and are connected to the respective upper end (9a) of one of the rod legs (3a).

15. Apparatus (1) according to one of Claims 12 to 14, characterized in that as viewed in the axial direction of the rod legs (3a), at least two adjacent joints of the upper joint device (8a) have been rotated by 90° relative to one another, the joints being in particular the first joints (8c) and the second joints (8e).

16. Apparatus (1) according to one of Claims 1 to 15, characterized in that the cross section of the rod legs (3a) is square or rectangular.

17. Apparatus (1) according to one of Claims 1 to 16, characterized in that the acute angle (6) between the rod legs (3a) is less than 15°, preferably less than 5° and particularly preferably less than 2°.

18. Apparatus (1) according to one of Claims 1 to 17, characterized in that the virtual point of intersection (7) in the extension of the rod legs (3a) lies at least half as far, preferably at least twice as far and particularly preferably at least four times as far beyond the holding point (5) as the rod legs (3a) are long.

19. Holding device (10) for holding an optical element (2), in particular an optical element of a lithography system, at least comprising a first apparatus (1 a) and a second apparatus (1 b), preferably both according to one of Claims 1 to 18, having a common holding point (5) for connection to the optical element (2), wherein the common holding point (5) is connected to a support (3) of the first apparatus (1a) and to a support (3) of the second apparatus (1 b), characterized in that the supports (3) each comprise at least two rod legs (3a) and a connection piece (15), wherein the respective connection piece (15) is arranged between the common holding point (5) and an upper end (9a), next to the common holding point (5), of the respective rod legs (3a) and connects the respective rod legs (3a) to one another, wherein the respective rod legs (3a) converge towards one another at an acute angle (6) in the direction of the common holding point (5), wherein a virtual point of intersection (7) in the extension of the respective rod legs (3a) lies on the far side of the common holding point (5), and wherein the first apparatus (1a) and the second apparatus (1 b) converge towards one another in the direction of the common holding point (5) at the optical element (2).

20. Holding device (10) according to Claim 19, characterized in that the first apparatus (1 a) and the second apparatus (1 b) at least approximately form a right angle with one another.21 . Holding device (10) according to Claim 19 or 20, characterized in that an actuator (4) of the first apparatus (1 a) for selective positioning and / or alignment of the optical element (2) is arranged and designed in such a way as to displace a first support foot (11 a) of the first apparatus (1a), and / or an actuator (4) of the second apparatus (1 b) for selective positioning and / or alignment of the optical element (2) is arranged and designed in such a way as to displace a second support foot (1 1 b) of the second apparatus (1 b), in each case preferably at least along a longitudinal axis (14) of the first apparatus (1a) and the second apparatus (1 b), respectively, in particular on the plane defined by the longitudinal axes (14) of the first apparatus (1 a) and the second apparatus (1 b).

22. Holding device (10) according to Claim 21 , characterized in that the actuator (4) of the first apparatus (1a) is arranged and designed in such a way as to displace the first support foot (11 a) along the longitudinal axis (14) of the first apparatus (1 a) and / or in the direction of the second support foot (11 b), and / or the actuator (4) of the second apparatus (1 b) is arranged and designed in such a way as to displace the second support foot (11 b) along the longitudinal axis (14) of the second apparatus (1 b) and / or in the direction of the first support foot (11 a).

23. Arrangement (12) for holding an optical element (2), in particular an optical element of a lithography system, at least comprising six apparatuses (1) according to one of Claims 1 to 18 or three holding devices (10) according to one of Claims 19 to 22.

24. Arrangement (12) according to Claim 23, characterized in that the apparatuses (1) and / or the holding devices (10) are at least approximately uniformly distributed around an outer peripheral region of the optical element (2).

25. System (13) comprising an optical element (2), in particular an optical element of a lithography system, and at least comprising six apparatuses (1) according to one of Claims 1 to 18 or three holding devices (10) according to one of Claims 19 to 22 for holding the optical element (2).

26. System (13) according to Claim 25, characterized in that the optical element (2) is a mirror or a lens element.

27. Method for holding and in particular for positioning and / or aligning an optical element (2), in particular an optical element of a lithography system, characterized in that the optical element (2) is held and in particular positioned and / or aligned by means of at least one apparatus (1) according to one of Claims 1 to 18 and / or a holding device (10) according to one of Claims 19 to 22 or an arrangement (12) according to Claim 23 or 24.

28. Lithography system, in particular projection exposure apparatus (100, 200) for semiconductor li- thography, having an illumination system (101 , 201) with a radiation source (102) and an optical unit (103, 109, 206) which comprises at least one optical element (116, 118, 119, 120, 121 , 122, Mi, 207), characterized in that the optical element (1 16, 118, 119, 120, 121 , 122, Mi, 207) is held by at least one apparatus (1) according to one of Claims 1 to 18 and / or a holding device (10) according to one of Claims 19 to22 or an arrangement (12) according to Claim 23 or 24.

Images