WO2009083476A1

WO2009083476A1 - Optical device comprising a spring device with a range of constant spring force

Info

Publication number: WO2009083476A1
Application number: PCT/EP2008/067891
Authority: WO
Inventors: Martin Vogt
Original assignee: Carl Zeiss Smt Ag
Priority date: 2007-12-27
Filing date: 2008-12-18
Publication date: 2009-07-09
Also published as: DE102007063305A1

Abstract

The present invention relates to an optical device in particular for microlithography, comprising an optically used arrangement (83; 110), a supporting structure (82; 103) and a spring device (1, 21, 41, 61). The spring device (1, 21, 41, 61) comprises at least one spring element (4, 24, 44, 64). In at least one operating state of the optical device, the spring device (1, 21, 41, 61) is connected to the supporting structure (82; 103) and the optically used arrangement (83; 110). In the at least one operating state, the spring device (1, 21, 41, 61) exerts a spring force in a spring direction on the optically used arrangements (83; 110). In order to provide an optical device in which precise adjustment is readily possible, or braking of mobile optically used arrangements is ensured even with short maximum spring deflections, the at least one spring element (4, 24, 44, 64) is designed and arranged in the manner of a kink spring.

Description

Optical Device comprising a Spring Device with a Range of Constant Spring Force

BACKGROUND OF THE INVENTION

The present invention relates to an optical device In particular for microlithography, comprising an optically used arrangement, a supporting structure and a spring device with at least one spring element. In at least one operating state of the optical device, the spring device is connected to the supporting structure and the optically used arrangement In tre at least one operating state, the spring device exerts a spring force in a spring direction on the optically used arrangement The invention furthermore relates to an optical imaging device in particular for microlithography, comprising an illumination device with a first optical element group, a mask device with a mobile mask stage for receiving a mask comprising a projection pattern, a projection device with a second optical element group and a substrate device with a mobile substrate stage for receiving a substrate. The llumlnatJon device is designed for Bkiminating the projection pattern by using the first optical element group, while the second optical element group is designed for imaging the projection pattern on the substrate. At least the illumination device, the mask device, the projection device or the substrate device comprises an optically used arrangement, a supporting structure and a spring device. The spring device comprises a spring element In at least one operating state of the imaging device, the spring device is connected to the supporting structure and the optically used arrangement In the at least one operating state, the spring device exerts a spring force in a spring direction on the optically used arrangement. The invention also relates to a method for exerting a force on an optically used arrangement. In this case, a spring force is exerted In a spring direction on the optically used arrangement by means of a spring device with at least one spring element

Particularly in the field of miαoflthography, despite the use of parts configured with the highest possible precision, inter alia it is necessary for the position and geometry of optical modules of the imaging device, I.e. for example the modules with optical elements such as lenses, minors or gratings, but also the masks and substrates being used, to be adjusted as precisely as possible during operation according to predetermined setpoint values or for such parts to be kept in a position once they have been adjusted, in order to achieve a correspondingly high imaging quality (in the context of the present invention, the term optical module is intended to refer both to optical elements on their own and to modules comprising such optical elements and further parts, for example frame pieces etc.).

In the field of microlithography, the accuracy requirementsin the microscopic range are of the order of a few nanometres or less. They are not least due to the constant need to increase the resolution of the optical systems used for producing microelectronic circuits, In order to progress the miniaturisation of the microelectronic circuits to be produced. Particularly in modem lithography systems, which work with a high numerical aperture in order to Increase the resolution, operation is carried out with WgNy polarised UV light in order to be able to fully utilise the advantages of the high numerical aperture. Preserving the polarisation of the light when it passes through the optical system is thus particularly important A particular problem encountered in this case is the stress* induced birefringence, which is due to the stresses in the optical elements and makes a substantial contribution to the polarisation loss in the system.

in order to keep an adjusted part, for example an optical element, in a position once it has been adjusted, two different concepts are conventionally used. On the one hand, material-fit connections between the optical element and Its supporting structure are employed. These, however, have the disadvantage that besides the sometimes insufficient long term stabiity of the connection under the effect of UV light, production of the material-fit connection sometimes entails the creation of parasitic forces (for example due to shrinkage of the adhesive being used, etc.), which lead to undesirable stresses in the optical element a polarisation loss and therefore a degradation of the Image quality.

As an alternative (particularly in ilumination systems), force-fit connections between the optical element and the supporting structure are often selected, for example clamp connections, since these are particularly easy to produce and inter alia also present no problems In respect of long term stability under the effect of UV light The holding force is generally provided by means of a restoring force of a spring device with an elastically deforming spring dement

A disadvantage with these clamp connections, however, is that a predetermined holding force cannot be adjusted exactly enough when mounting optical elements. This is due inter alia to the restoring forces of the spring elements being used, with increasing deformation thereof. TNs relationship is conventionally represented by so-called spring characteristic curves . In general, the damp connections comprise characteristic curves with an approximately linear rise in the spring or restoring force as a function of the spring deflection. The spring deflection describee, for example, how far the spring has been deflected or how the length of the spring has been changed owing to the deformation. A lnear profile of the spring force as a function of the spring deflection is also referred to as Hooke's law and its gradient as the spring constant

When mounting a clamp device, a desired prestress is adjusted. It Is therefore necessary to create a particular spring deflection in order to obtain the desired spring or restoring force. Yet since the spring deflection can never entirely be adjusted exactly, the resultant holding force of a clamp connection always deviates somewhat from the predetermined setpoint value. The deviation becomes commensurately greater as the spring characteristic curve of the clamp connection becomes steeper for a given spring deflection or given restoring force. Particularly in mJcroltthography, the space available for the clamp connections is very limited in many cases owing to the design situation. It is therefore possible to use only damp connections with spring devices which comprise short maximum spring deflections. Flexion springs are typically used for this. In order to be able to ensure high holding forces in spite of this, It is essential to use spring devices with very steep spring characteristic curves overall. Owing to the relationship described above, however, this means that sizeable inaccuracies when mounting the clamp connections are unavoidable.

One problem, particularly in the field of inicrolithography, is that even slightly excessive holding forces can lead to undesirable stress peaks in optical elements held by the clamp connections. This leads to stress-induced birefringence, so that a polarisation loss and therefore a degradation of the image quality are finally entailed.

Another problem is that unintentional deadjustment of a held object must generally be prevented. In microlithography, even the most minor deadjustments of optical elements greatly compromise the imaging accuracies. If the desired hoklng force for an optical element is not achieved when mounting the clamp connection, mechanical or thermal loads even within the tolerance range will lead to deadjustment

Spring devices which comprise a degressive spring characteristic curve are known in practice. These then comprise, for example, individual disc springs or stacks of disc springs. However, the gradient of the force profile as a function of the spring deflection for such spring devices does not decrease significantly until dose to the maximum spring deflection, so that their use scarcely allows safety margins.

Comparatively largely constructed spring devices with so-called equiforce behaviour, In which the spring force varies only weakrywKh the deflection, are furthermore known for example from vehicle manufacture (see for example A. Geisel, K. Künzli, Tod der Hooke'schen Gerade" [death of Hooke's Iaw) KEM - Informationsvorsprung für Konstrukteure, Volume 02/2001, page 42, Konradin Vertag. 70771 Leinfeldern-Echterdlngen, DE).

In some applications such as microlithography, the problem also arises that mobile parts, for example carriages of a mobfle carrier device, must be braked In a defined way on so-called end stops so that impermissibly high vibrations and resultant damage to the overall apparatus are avoided, even though only very limited installation space is avalabie for the end stop.

In conventional end stops, the majority of the kinetic energy of the part to be braked is often absorbed only shortly before the maximum spring deflection of the spring device being used. This entals the risk that the kinetic energy may not be fully absorbed by the spring device and that the mobile part wiβ transmit vibrations to the apparatus despite the end stop. Particularly in microlHhography, this can lead to considerable problems.

BRIEF SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide an optical device in which precise adjustment of the restoring or holding forces acting on the optically used arrangements is rββdiy possible, or braking of mobβe optically used arrangements is ensured even with short maximum spring deflections.

The present invention is based on the discovery that the use of a spring element in the manner of a kink spring in optical devices allows deliberate adaptation of the respective spring characteristic curve in a way which combines optimal functionality with a minimal installation size of the optical device. To this end, the invention uses the fact that on the one hand the active force of the spring element at the force engagement point comprises a normal force component and a transverse force component, which respectively extend parallel and perpendicular to a tangent to a spring midline, and that with a suitable configuration of the spring device, the ratio of the two force components changes in a desired way with increasing deflection of the spring element As a result, a bending load can thus be applied onto the spring element which causes a rising bending moment with increasing deflection of the spring element, which compensates for the likewise increasing elastic restoring force.

According to one aspect, the present invention therefore relates to an optical device in particular for microlithography, comprising an optically used arrangement, a supporting structure and a spring device. The spring device comprises at least one spring element In at least one operating state of the optical device, the spring device is connected to the supporting structure and the optically used arrangement and exerts a spring force In a spring direction on the optically used arrangement The at least one spring element is in this case designed and arranged in the manner of a kink spring.

The present invention is furthermore based on the discovery that the relationships described above can be used especially positively in particular optical imaging devices which comprise an lumination device, a mask device, a projection device and a substrate device, an optically used arrangement being resiliently connected to a supporting structure in at least one of these devices.

Accoroing to another aspect, the present invention therefore relates to an optical imaging device in particular for microlithography, comprising an illumination device with a first optical element group, a mask device with a mobile mask stage for receiving a mask comprising a projection pattern, a projection device with a second optical element group and a substrate device with a mobie substrate stage for recervfng a substrate. The illumination device is designed for luminating the projection pattern by using the first optical element group, while the second optical element group is designed for imaging the projection pattern on the substrate. At least the llumination device, the mask device, the projection device or the substrate device comprises an optically used arrangement, a supporting structure and also a spring device. The spring device In turn comprises at least one spring element and is connected to the supporting structure and the optically used arrangement In at least one operating state of the Imaging device. In the at least one operating state, the spring device exerts a spring force in a spring direction on the optically used arrangement The at least one spring element is in this case designed and arranged in the manner of a kink spring.

The present invention is also based on the discovery that by using a spring element in the manner of a kink spring, forces can be exerted very deliberately on an optically used arrangement and while complying with even the smallest of tolerances.

According to another aspect, the present invention therefore relates to a method for exerting a force on an optically used arrangement In this case, a spring force is exerted in a spring direction on the optically used arrangement by means of a spring device with at least one spring element The at least one spring element is a spring element designed in the manner of a kink spring, which is loaded wtth a kink force when exerting the spring force.

Other preferred configurations of the invention may be found in the dependent claims or the following description of preferred exemplary embodiments, which refers to the appended drawings. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic detailed representation of a first preferred exemplary embodiment of the optical device according to the invention;

Figure 2 is the optical device according to Figure 1 with a smaller deflection in a further simplified representation;

Figure 3 is the optical device according to Figure 2 with larger deflection;

Figure 4 is a schematic representation of a spring characterise optical device according to Figure 1 in comparison with a Hookian spring characteristic curve;

Figure 5 is a second preferred embodiment of the optical device according to the invention in a detailed representation according to Figure 2;

Figure 6 is a variant of the optical device according to Figure 5;

Figure 7 is a variant of the optical device according to Figure 6;

Figure 8 is a schematic representation of a third exemplary embodiment of an optical device according to the invention in the unloaded state;

Figure 9 is the optical device according to Figure 8 in a loaded state;

Figure 10 is a schematic representation of a fourth exemplary embodiment of an optical device according to the invention in the unloaded state; Figure 11 is a schematic representation of a fifth exemplary embodiment of an optical device according to the invention;

Figure 12 is a schematic representation of a sixth preferred exemplary embodiment of an optical device according to the invention;

Figure 13 is an exemplary embodiment of an optical imaging device according to the invention for microlithography.

DETAILED DESCRIPTION OF THE INVENTION

Figure 13 shows a schematic representation of an embodiment of an optical imaging device in the form of a microlithography device 201 , which operates using light in the UV range with a wavelength of 193 nm.

The microlithography device 201 comprises an illumination system 202, a mask device in the form of a mask stage 203, an optical projection system in the form of an objective 204 with an optical axis 204.1 and a substrate device in the form of a wafer stage 205. The lluminatJon system 102 illuminates a mask 203.1 arranged on the mask stage 203 using a projection light beam (not represented in detal) with a wavelength of 193 nm. On the mask 203.1, there is a projection pattern which is projected by the projection light beam via the optical elements arranged in the objective 204 onto a substrate in the form of a wafer 205.1, which is arranged on the wafer stage 205.

Besides a light source (not represented), the illumination system 202 comprises a first group 206 of optically active parts which comprises inter alia a rod-ehaped optical element 206.1. Owing to the operating wavelength of 193 nm, the optical element 206.1 is a refractive optical element The objective 204 comprises a second group 207 of optically active parts which comprises Inter alia a series of optical elements, for example the optical element 207.1. The optically active parts of the second group 207 are held in a housing 2042 of the objective 204. Owing to the operating wavelength of 193 nm, the optical element 207.1 is a refractive optical element for example a lens or the like. It is however to be understood that any other desired optical elements, for example reflective or diffractrve optical elements, may also be employed in other variants of the invention. Naturally, any desired combinations of such optical elements may likewise be employed.

At least the illumination device 202, the mask device 203, the projection device 204 and/or the substrate device 205 comprise an optically used arrangement and a supporting structure, which are connected to one another by means of a spring device (not represented in detail but further described in Figures 1 to 12) in at least one operating state. In the at least one operating state, the spring device exerts a spring force on the optically used arrangement and to this end it comprises a spring element, which is designed and arranged in the manner of a kink spring.

Figure 1 purely schematically shows such a spring device 1 as a detal of an optical arrangement (not further specified) which may for example be the microlithography device 201 In Figure 13. Of the optically used arrangement, only the part 2 is represented, while merely the part 3 of the supporting structure is represented. The way in which the optically used arrangement is designed in detail comprises only a secondary role for the configuration of the spring device.

In the exemplary embodiment represented in Figure 1, the supporting structure and the optically used arrangement are connected to one another by means of a spring element 4 in each operating state. To this end, the spring element 4 comprises outer connecting sections 5, β, which are connected to the parts 2, 3 by means of connecting positions 7, 8 in the capacity of force engagement points. At the connecting petitions 7, 8, so to speak, a force is induced in the spring element 4 which results in a deflection of the spring element 4.

The spring element 4 is a kind of kink spring, In which a kink load acts on the spring element 4 at least at one of the comectiιig positions7, 8 in the defelected state. This kink load is distinguished in that a significant force component therefore acts tangentially to a spring midline. The term spring midline is intended to mean the so-called neutral fibre of the spring element 4. There, on the one hand the bending stress is equal to zero in the deflected state of the spring element 4 and, on the other hand, the length is independent of the deflection of the spring element 4. Along the spring midline or the neutral fibre, which extends at least between the two connecting positions, the length of the spring element 4 is therefore constant regardless of the respective operating state. The kink load is finally a normal force component In the direction of the tangent to the spring midline at the force engagement point, which Is represented by the positions 7, 8 connecting the spring element 4 to the parts 2, 3.

Besides the kink load, another force component perpendicular to the kink load also acts on the spring element 4 in the deflected state of the spring element 4. This force component acts as a bending load perpendicular to the tangent to the spring midline at least at one of the connecting positions 7, 8. With an increasing deflection of the spring element 4, the bending load generated by the further force component increases and thus causes an increasing bending moment With an increasing deflection of the spring element 4, the bending moment finally counteracts likewise the Increasing elastic restoring force.

The parts 2, 3 of the spring device 1 are arranged displaceably relative to one another, specificaly only in the vertical direction in the exemplary emboolment represented. This is achieved by the guides 9. 10 which establish the direction in which the two parts 2, 3 can be displaced relative to one another and therefore the spring direction. In the exemplary embodiment represented, the guides 9, 10 are glide feces on the two parts 2, 3. The guides 9, 10 in the exemplary embodiment represented in Figure 1 also establish the direction in which a force can be induced In the spring element 4. The spring element 4 is consequently received with its connecting sections δ, β in corresponding recesses of the two parts 2, 3, such that the spring direction in relation to at least one connecting position 7, 8 comprises one component partially extending normally to the tangent to the spring midline of the spring element 4 and one component aligned perpendicularly thereto.

In the exemplary embodiment of Figure 1 , this is achieved in that the spring element 4 already comprises a certain curve 11 in the unloaded state. If the spring element 4 is additionally loaded, then this curve 11 increases owing to the bending load acting perpendiculariy to the tangent to the spring midline at the force Induction point In other words, loading the spring element 4 leads to a bending moment about a bending axis 12.

The first exemplary embodiment is represented in a further simplified way in Figures 2 and 3 In two drfferent operating states, respectively with a different deflection of the spring element 4. In Figure 2, a smaler force F acts on the spring element 4 and leads to a small deflection s of the spring element 4, whle in Figure 3 not only the force F but also the deflection s is greater. The force F acting on the spring element 4 corresponds as In all spring elements to the spring force which acts as a restoring force on the two parts 2, 3 connected to one another. The spring force finally in an active force on trie parts 2, 3, this active force comprising two components as already discussed above for the force F acting on the spring element 4. At a force induction point or a connecting position 7, 8, one of the components of the active force points in the direction of a tangent to the spring midline at this force induction point This force component may be described as a normal force component or as- a compressive force component The other force component of the active force, which may be referred to as a transverse force component, is perpendicular thereto and therefore to the tangent to the spring midline respectively at the same force Induction point

Compared with the position of the spring device 1 1n Figure 2, in the position represented in Figure 3 not only the force F overall but also the ratio between the transverse force component and the normal force component is greater. In the exemplary embodiment shown, the spring element 4 is bent more strongly about the bending axis 12 with increasing proximity of the parts 2, 3 or increasing deflection of the spring element 4, which is obtained with the aid of the increasing distance x between the bending axis 12 and a connecting line between the connecting positions 7, 8 and the increasing curve 11 of the spring element 4 in a central section. This increasing curve 11 also affects the profile of the spring midline in the region of the connecting positions 7, 8, so that the transverse force component increases in relation to the normal force component with the deflection of the spring element 4.

The ratio between the transverse force component and the normal force component of the active force may be influenced according to the specific requirements by the connection between the parts 2, 3 and the spring element 4. This is illustrated by Figures 5 to 7, which show a spring element 21 of an optical device (not represented in detail). The spring device 21 comprises two parts 22, 23, which can be moved relative to one another and are connected to one another by means of a spring element 24. For the connection, the spring element 24 comprises outer connecting regions 25, 26 where connecting positions 27, 28 are formed as force induction points. There are differences between Figures 5 to 7 merely in respect of the connecting regions 25, 26 of the spring element 24. For better comprehension, the same references are used for essentially identical parts in Figures 5 to 7. In the exemplary embodiment shown in Figure 5, two grooves 29 are provided in the two pails 22, 23. into which the spring element 24 is Inserted with its connecting regions 25, 26. For the given curve, a very large angle α is thus obtained between the spring midline and the force F which acts parallel to a connecting line between the connecting positions 27, 28 (spring direction). There is consequently a large ratio between the transverse force component end the normal force component, respectively, of the active force of the spring device 21. The same applies in Figure 6 for the lower part 23. The connecting region 25 of the spring element 24 is, however, rigidly connected to the upper part 22. The active force on the upper part 22 therefore comprises a higher proportion which acts as a normal force component

The parts 22, 23 may If necessary also be designed rotatabry as represented In Figure 7. An angle β is then created between the spring midline of the spring element 24 and the direction of the active force in the connecting positions 27, 28.

The extent to which the parts 22, 23 are rotated relative to a resting position in the respective operating state may depend on the respective deflection of the spring element 24 in the corresponding operating state and this may therefore be introduced as a further parameter into the ratio between the transverse force component and the normal force component

As revealed overall by Figures 5 to 7, the ratios between the transverse force component and the normal force component in different operating states, and therefore deflections of the spring element 24, may be adjusted by a suitable design of the spring device 21. Moreover, the active force per se may also be adjusted as a function of the deflection of the spring element 24. The transverse force perpendicular to the tangent to the.spring midline at the connecting position 27, 28 acts as a bending load about a bending axis 30. Depending on the configuration of the spring device 21 and the deflection of the spring element 24, moreover, the normal force or compressive load parallel to the tangent to the spring midline at the connecting position 27, 28 may act as a bending load in relation to the same bending axis 30 and/or another bending axis. Since the bending moment or moments depends/depend not only on the bending load but also on the effective lever arm, and the lever arm can be shortened or lengthened according to the curve 31 of the spring element 24 as a function of the deflection, the active force is adjustable and adaptable to the respective requirements of the spring device 21.

This Is represented for example In Figure 4. Figure 4 shows a spring characteristic curve 13, which has been adapted to special requirements in the manner described above. A useful deflection range is specified for the spring device of an optical device, which is delimited by the initial deflection s_A and the final deflection SE. In this useful deflection range, the spring characteristic curve should now have a flat profile. On the other hand, the spring force level in the useful deflection range should be relatively high. In other words, a steep rise in the spring force with the deflection is required in a short transition region s₁. Furthermore, neither a maximum spring force F_max nor a maximum deflection s_max should be exceeded. Through the configuration of the spring device in respect of the active force per se and the ratios between the normal and transverse force components of the active force, as well as the use of suitable materials and dimensions of the parts, the person skilled In the art can comply with the said requirements and provide an optical device with the spring characteristic curve 13 as represented.

In the exemplary embodiment of Figure 4, the deviation between the greatest and least spring force in the useful deflection range is less than 15%, preferably even less than 2%. Furthermore, the useful deflection range of the spring device extends over at least 25% of the maximum deflection of the spring device.

Figures β to 10 represent further exemplary embodiments of optical devices at least In respect of the spring devices 41 and 61 shown. Figures 8 and 9 represent the same exemplary embodiment of a spring device 41 in two different operating states with different deflections, in both operating states, an upper part 42 and a lower part 43 are connected to one another by means of a spring element 44. The connection is respectively designed in an articulated fashion at the connecting positions 47, 48. Furthermore, corresponding glide faces 49, 50 are provided which permit relative movement of the two parts 42, 43 and simultaneously define a spring direction. In relation to this spring device, the connecting positions 47, 48 are arranged offset in contrast to the exemplary embodiment shown in Figures 5 to 7. One glide face 50 in the exemplary embodiment represented is provided with an additional part 53, which positions the upper part 42.

In the operating state of the optical device as shown in Figure 8, the spring device 41 is unloaded and the spring element 44 extends in a straight line. Nevertheless, the active force comprises a normal force component and a transverse force component as soon as the spring device is loaded since the spring mkline in any event extends obliquely to the spring direction and therefore to the load.

As revealed by Figure 9, the spring element 44 comprises an increasing curve 51 with rising deflection, the bending axis 52 of the spring element being separated increasingly from the plane of the spring element 44 In the unloaded state. At the same time, owing to the articulated connection between the spring element 44, the angle between the tangent to the spring midline at the connecting positions 47, 48 and the spring direction also changes and therefore so does the ratio between the transverse force component and the normal force component of the active force.

Figure 10 shows the spring device 81 of another exemplary embodiment of an optical device, likewise in an unloaded operating state. The two parts 62, 83 are at a maximum oistance from one another and are connected to one another by means of the spring element 84, the spring element 84 being hinged in an articulated fashion to the two parts 82, 83 at the connecting positions 87, 88. The positioning and guiding of the parts 62, 63 in the event of a deflection is ensured by the guide means 69, 70 In the form of cooperating glide faces.

The spring element 64 is prestressed, so that the spring element 64 comprises a curve 71 and a bending axis 72. The prestress is achieved by providing stop means 74 on the upper part 62 and on an additional part 73. In the exemplary embodiment represented, one of the guide means 70 is also provided on the additional part 73. The guide means 70 may, however, also be provided on the lower part 63 If necessary.

Figure 8 represents a clamp apparatus 80 with a spring device 81 of the type described above. The clamp apparatus 80 comprises a supporting structure, which is designed as a frame 82 to receive an optical module 83. The optical module 83 is, for example, an optical element such as a mirror, a lens or the like. The optical module 83 is retained In the frame by a damp device 84. The clamp device 84 comprises a clamp element 85 extending beyond the edge of the optical module 83 in the form of an arm, as well as a pin 87 that engages through an opening 86 in the frame 82 and carries a mounting plate 88 on its lower end. The clamp apparatus 80 is mounted resilient ly this mounting plate 88 relative to the frame 82 via two spring elements 89, the spring elements 89 being bent to opposite sides and respectively being inserted into two recesses 90 or grooves in the clamp device 81 and the frame 82.

If the mounting plate 88, together with the pin 87 engaging through the opening 86 In the frame 82 is displaced upward against the spring forces of the spring elements 89, then the arm 85 releases the object 83. In the operating state represented in Figure 10, active forces of the spring elements 89 act on the clamp device 81 and the frame 82. This results in a holding force H, which fixes the optical module 83 in the frame 82 at the end of the arm 85. A recess, In which the mounting plate 88 is movably arranged, Is provided in the frame 82. The mounting plate 88 Is guided parallel to the spring direction, so that the recess and the mounting plate 88 comprise corresponding contact feces 91 directed toward one another in the capacity of guide means.

Figure 12 shows another optical device, specificaly in the form of a retardation device 100 which likewise comprises a spring device 101 of the type described above. The retardation device 100 comprises a plunger 102, which is mounted In a supporting structure in the form of a bearing 103 in the spring drection. The plunger 102 is connected to the bearing 103 by means of two spring dements 104. The spring elements may be prestressed, in order to be able to absorb more energy with a limited spring deflection. In the unloaded state, the plunger 102 is arranged in a right-hand resting position. The head 105 of the plunger 102 protrudes relative to the bearing 103, in particular relative to means for centring the plunger 102. If necessary, these means may be designed as guide means 106, 107 and comprise glide faces In the region of the base 108 of the plunger 102 and/or the head 105 of the plunger 102.

The head 105 of the plunger 102 comprises a bearing face 109 for a mobile element in the form of a carriage 110. If the carriage 110 is moved with a stop face against the bearing face 109, then the plunger 102 is moved from its resting position against the restoring force of the spring device 101 and the kinetic energy of the carriage 110 is reduced by the spring elements 104 being deflected. As a result, the carriage is slowed. If the spring device 101 comprises a spring characteristic curve 13 as shown in Figure 4, then the curve profle of the spring characteristic curve may be adjusted so that the energy absorbed by the spring elements 104 is sufficient for the retardation device 100 with ndnimaJ deflection and therefore minimal space requirement.

Claims

1. Optical device in particular for microUthography, comprising an optically used arrangement (83; 110), a supporting structure (82; 103) and a spring device (1 , 21 , 41 , 61 ) comprising at least one spring element

(4, 24, 44, 64), the spring device (1, 21, 41, 61) being connected to the supporting structure (82; 103) and the optically used arrangement (83; 110) in at least one operating state of the optical device, and exerting a spring force in a spring direction on the optically used arrangement (83; 110) in the at least one operating state, characterized in that the at least one spring element (4, 24, 44, 64) is designed and arranged in the manner of a kink spring.

2. Optical device according to Claim 1, characterized in that the spring device (1, 21, 41, 61) comprises two parts (2, 3; 22, 23; 42. 43: 42, 63), - the peits (2, 3; 22, 23; 42. 43; 42, 63) being arrenged displaceably relative to one another in the spring direction, the at least one spring element (4, 24, 44, 64) being connected by opposite connecting sections (5, 6; 25, 26; 45, 46; 65, 66) via connecting positions (7, 8; 27, 28; 67, 68) to the parts (2, 3; 22, 23; 42. 43; 42, 63), the at least one spring element (4, 24, 44, 64) defining a spring mkΛnβ extending between the two connecting positions (7. 8; 27, 28; 67, 68) in the spring element (4, 24, 44, 64) and the at least one spring element (4, 24, 44, 64) being arranged such that the a^ve force on one of the connecting positions (7, 8; 27, 28; 67, 68), resulting from the spring force, comprises a normal force component in the direction of the tangent to the spring midline and a transverse force component perpendicular to the tangent to the spring midline.

Optical device according to Claim 2, characterized in that the spring element (4, 24, 44, 64) is arranged and designed so that the ratio of the transverse force component to the normal force component increases with increasing proximity of the two parts (2, 3; 22, 23; 42, 43; 42, 63) in the spring direction.

Optical device according to Claim 2 or 3, characterized in that the connecting positions (7, 8; 27, 28; 67, 68) are arranged mutually offset transversely to the spring direction.

Optical device according to Claim 2 or 3, characterized in that the connecting positions (7, 8; 27, 28; 67, 68) are arranged mutually flush in the spring direction.

Optical device according to any one of Claims 2 to 5, characterized in that the spring element (4, 24.44, 64) is rigidly connected to the associated part (2, 3; 22, 23; 42, 43; 42, 63) in the region of at least one connecting position (7, 8; 27, 28; 67, 68), and/or - the spring element (4, 24, 44, 64) is connected In an articulated fashion to the associated part (2, 3; 22, 23; 42, 43; 42, 63) In the region of at least one connecting position (7, 8; 27, 28; 67, 68).

Optical device according to any one of Claims 1 to β, characterized in that guide means (9, 10) are provided for guiding one of the two parts (2, 3; 22, 23; 42, 43; 42, 63) relative to the other of the two pats (2, 3; 22, 23; 42, 43; 42, 63).

8. Optical device according to any one of Claims 1 to 7, characterized In that the at least one spring element (4, 24. 44, 64) is formed at least in sections as a rod spring element and/or leaf spring element

9. Optical device according to any one of Claims 1 to 8, characterized In that the at least one spring element (4, 24, 44, 64) defines a spring midline extending between the two connecting positions (7, 8; 27, 28;

67, 68) (n the spring element (4, 24, 44, 64). the spring element (4, 24, 44, 64) being extended In a straight line in an unloaded state of the spring element (4, 24, 44, 64).

10. Optical device according to any one of Claims 1 to 9, characterized in that the spring element (4, 24, 44, 64) is prestressed in an operating state of the optical device, in which the spring element (4, 24, 44, 64) exerts no spring force on the optically used arrangement (83; 110).

11. Optical device according to any one of Claim* 1 to 10, characterized in that the spring device (1, 21, 41, 61) comprises a maximum deflection In the spring direction and a useful deflection range between a first deflection in the spring direction and a second deflection in the spring direction and - the spring device (1, 21, 41, 61) exerts a first spring force with the first deflection In the spring direction and exerts a second spring force with the second deflection in the spring direction, the useful deflection range being at least 25% of the maximum deflection and the spring device (1, 21, 41, 61) being designed such that the maximum deviation of the spring force from the first spring force over the entire useful deflection range is less than 15% of the first spring force.

12. Optical device according to Claim 11 , characterized in that the maximum deviation of the spring force from the first spring force is less than 2% of the first spring force.

13. Optical device according to any one of Claims i to 12, characterized In that the optically used arrangement comprises an optical module (83), the supporting structure comprises a frame (82) for receiving the optical module (83) and a clamp device (84) comprising the spring device (81) is provided for firmly clamping the optical module (83) ln theframe(82), the spring force of the spring device (81) being formed at least some of the clamping force for firmly clamping the optical module (83) In the frame (82).

14. Optical device according to Claim 13, characterized in that the optical module (83) comprises an optical element

15. Optical device according to Claim 13 or 14, characterized in that the clamp device (84) comprises a damp element (85) and a guide means (91), the clamp element (85) being connected to the spring device (81) and designed for contacting the optical module (83) and the guide means (81) being connected to the frame (82) and guiding the clamp element (85) relative to the frame (82) parallel to the spring direction.

16. Optical device according to any one of Claims 1 to 12, characterized in that the optically used arrangement comprises an element (110) mobile in the spring direction relative to the supporting structure (103) and - a retardation device (100) comprising the spring device (101) is provided for slowing the mobile element (110), the spring force of the spring device (81) forming at least some of the retardation force for slowing the mobile element(110).

17. Optical device according to Claim 16, characterized in that the retardation device (100) comprises a plunger (102) connected to the spring device (101) and displaceable in the spring direction, with a bearing face (109) and a stop face contacting the bearing face (109) during retardation of the mobile element (110), - the plunger (102) being connected to the supporting structure (103) and the stop face being connected to the mobile element (110) and/or the plunger (102) being connected to the mobile element (110) and the stop face being connected to the supporting structure (103).

18. Optical device according to claim 17, characterized in that the mobile element (110) is a carriage guided in a guide.

19. Optical imaging device in particular for mlcrolHhograpriy, comprising - an illumination device with a first optical element group, a mask device with a mobile mask stage for receiving a mask comprising a projection pattern, a projection device with a second optical element group and a substrate device with a mobile substrate stage for receiving a substrate, the illumination device being designed for Illuminating the projection pattern by using the first optical element group and the second optical element group being designed for imaging the projection pattern on the substrate, - at least one of the lumination device, the mask device, the projection device and the substrate device comprising an optically used arrangement (83; 110), a supporting structure (82; 103) and a spring device (1, 21, 41, 61) with at least one spring element (4, 24, 44, 64), the spring device (1, 21, 41, 61) being connected to the supporting structure (82; 103) and the optically used arrangement (83; 110) in at least one operating state of the imaging device and exerting a spring force in a spring direction on the optically used arrangement (83; 110) in the at least one operating state, characterized in that • the at least one spring element (4, 24, 44, 64) is designed and arranged in the manner of a kink spring.

Method for exerting a force on an optically used arrangement (83; 110), in which - a spring force is exerted In a spring direction on the optically used arrangement (83; 110) by means of a spring device (1,

21, 41, 61) with at least one spring element (4, 24, 44, 64), characterized in that the at least one spring element (4, 24, 44, 64) is designed In the manner of a kink spring and is loaded with a kink force when exerting the spring force.

Method according to Claim 20, characterized in that the optically used arrangement comprises an optical module (83), and at least some of a clamping force for firmly clamping the optical module (83) In a frame (82) is applied by the βpring force of the spring device (81).

22. Method according to Claim 20, characterized In that the optically used arrangement comprises an element (110) mobile In the spring d-rβctton and at least some of a retardation force for slowing the mobile element (110) is applied by the spring force of the spring device (81 ).