EP1442329A2

EP1442329A2 - Optical element with an optical axis

Info

Publication number: EP1442329A2
Application number: EP02782948A
Authority: EP
Inventors: Thomas Petasch; Hartmut Muenker; Bernhard Gellrich
Original assignee: Carl Zeiss SMT GmbH
Current assignee: Carl Zeiss SMT GmbH
Priority date: 2001-10-20
Filing date: 2002-10-18
Publication date: 2004-08-04
Also published as: US7295331B2; US20040257683A1; WO2003036359A2; WO2003036359A3; DE10151919A1; JP2005506574A; DE10151919B4

Abstract

The invention concerns an optical element (1) with an optical axis (3), designed in particular for an exposure lens used in semiconductor lithography. Said optical element comprises at least an extension (2, 2') in the direction of the optical axis (3). A device (11) enables to induce a two-wave or multiple wave deformation in said optical element (1). At least a system (12) mounted in the extension zone (2, 2') is designed to apply a force in said extension (2, 2').

Description

Optical element with an optical axis

The invention relates to an optical element with an optical axis and a device for introducing a two- or multi-wave deformation into this optical element.

In particular, the invention relates to an optical element which, in its preferred embodiment, is designed as a mirror for use in an exposure lens for semiconductor lithography.

From DE 198 27 603 AI an optical system is known which contains a so-called "active optical element". This active optical element can be influenced by actuators, which act on the optical element at least approximately perpendicular to the optical axis, in such a way that bending and non-rotationally symmetrical forces and / or moments on the optical element are generated on the optical element. Such a system can be used to introduce deformations into the optical element, which can serve, for example, to compensate for astigmatism or the like.

Furthermore, the prior art knows from DE 198 12 021 AI active mirrors which are equipped with a mirrored membrane. The surface shape of the membrane is influenced by one or more actuators in such a way that the mirror surface is manipulated and thus the image generated by the mirror can be influenced.

Comparable structures which likewise influence the optical imaging quality by deforming a surface of a mirror are described, for example, in WO 93/25929 or US Pat. No. 5,210,653. wrote.

In addition, from DE 196 28 672 AI an adaptive mirror is known, which has a deformable mirror plate held on the edge. This mirror plate is acted upon on the back by an adjusting mechanism which allows the mirror plate to be deformed. A corresponding adaptation of the mirror plate can be achieved here, but the possibilities of the introducible deformations are comparatively limited. '

In addition to the need to deform an optical element, for example a mirror, in the manner mentioned above, in the area of high-precision optics, as is used, for example, in semiconductor lithiography systems, there is the need for very high accuracy possible deformations.

The optical elements that are to be deformed must therefore only react to the deformation. Undesirable side effects and undesirable deformations should not occur if possible. With the predominantly required deformation, namely the correction of astigmatisms or multi-wave, for example three- or four-wave errors, such a targeted deformation is very difficult since the optical element, in addition to the deformation, reacts by changing its surface shape and / or thickness in the multi-wave range can.

In addition, the abovementioned structures mostly have a very large space requirement, which is disadvantageous in particular when used in imaging systems which allow very dense packaging, or the like.

It is therefore the object of the invention to provide an optical element which has the above-mentioned disadvantages of the prior art avoids technology and is very well suited for introducing two- or multi-shaft deformations.

It is also an object of the invention to provide a device for introducing two- or multi-wave deformations into such an optical element.

According to the invention, this object is achieved in that the optical element has at least one extension in the direction of the optical axis.

The at least one extension makes it possible to introduce forces into the optical element in order to deform it accordingly. This deformation can be useful and / or desired in order to compensate for imaging errors or to minimize their impact.

The extension is understood to mean either a discrete component or a projection attached to the optical element, which protrudes beyond the actual surface of the optical element in the direction parallel to the optical axis. The extension can have any shape, for example the shape of a rod or the like.

In a very convenient manner may thereby in said at least one projection at different positions, depending on the design of the extension, for example in two diametrically opposite regions of targets may be arranged, which for the input line ^'serve forces. The two points of attack serve to introduce a corresponding force, which can be introduced into the optical element in a very targeted and precise manner via the extensions as levers. Basically, of course, the introduction of a moment is also conceivable, with a moment in any case into the optically appropriate if the forces on the extension or the extensions are used accordingly. see item is initiated.

In a particularly favorable embodiment of the invention, the extension is designed as an at least approximately tubular one-piece extension of the optical element.

With this tubular extension a kind of mirror or. Lens pot. By introducing the forces into the area of the tubular extension of the optical element, for example a mirror, a lens, an end plate or the like, a very uniform response of the optical element itself to the forces or moments introduced can be achieved. Because of the circumferential tubular extension, the forces or tensions that are introduced are transmitted very uniformly to the optical element itself. Thus, depending on the diameter, length and wall thickness of the tubular extension, a moment can be introduced with very few discrete forces on one side of the tubular extension facing away from the optical element. Due to the tubular extension, this moment will bring about a continuous moment on the other side, ie the side of the tubular extension facing the optical element.

The structure of the invention according to the exemplary embodiment shown here thus makes it possible, in a particularly advantageous manner, to generate a continuous torque curve with few discrete forces via the tubular extension.

In addition, there is the possibility that if a corresponding mechanism for introducing the force is used, this can be applied regardless of the angle, since the extension is designed in the manner of a tube all the way round. Contrary to the individual extensions already mentioned above, for example two or four, depending on the desired ripple of the deformations to be introduced, the result is here Possibility that the desired deformations can be adapted to the optical element with regard to their waviness and their angular position, without the need for a corresponding optical element specially designed for the intended use.

This version offers enormous advantages, in particular in the case of a mirror, since all the elements for introducing deformations or the like can be accommodated in this “pot”, so that a very compact structure is formed which has its mechanics and / or its actuators integrated.

A solution according to the invention for a device for introducing a two- or multi-wave deformation into such an optical element is described in claim 9.

By introducing the forces into the extension, they can be passed on in a very targeted manner to the surface or area of the optical element used for the optical imaging via the geometric design of the extension.

Particularly when it is designed as a mirror, the surface of the mirror used can be designed with the same rigidity, so that, according to the principle of the plate of the same thickness, no higher-wave errors are introduced during the deformation. In addition, there is the possibility that with a corresponding rotationally symmetrical design of the tubular extension, the initiation of the two- or multi-wave deformations, for example an astigmatism in each axis, can take place perpendicular to the optical axis, that is, the axis of the deformation introduced, as already above mentioned, is freely selectable.

Further advantageous refinements of the invention result from the remaining subclaims and from the subsequent following exemplary embodiments shown with reference to the drawings.

It shows:

Figure 1 is a schematic representation of an embodiment of the optical element;

FIG. 2 shows a view according to arrow II in FIG. 1 with a possible embodiment of an actuator;

Figure 3a shows a basic representation of the balance of forces in a two-wave deformation (astigmatism);

FIG. 3b shows a basic representation of the balance of forces in the case of a three-wave deformation (astigmatism);

Figure 4 shows an alternative embodiment of the optical element;

5 shows a section through the optical element along the line V-V in Figure 4;

FIG. 6 the optical element according to FIG. 4 with a device for introducing a two-wave deformation;

FIG. 7 shows the optical element according to FIG. 4 with a device for introducing a two-wave deformation in a three-dimensional representation;

Figure 8 is a schematic diagram of the possibility of actuation an electromagnetically active actuator for introducing deformations into the optical element;

FIG. 9 shows a possible embodiment of such an electromagnetic actuator;

FIG. 10 shows a possible alternative embodiment of such an electromagnetic actuator;

FIG. 11 shows a view of the optical element with actuators for introducing two- or multi-wave deformations in an alternative embodiment; and

FIG. 12 shows a view of the optical element with actuators for introducing two- or multi-wave deformations in a further alternative embodiment.

FIG. 1 shows a highly schematic representation of an optical element 1, which, to simplify the representation, was only indicated as a plane-parallel plate. On the optical element 1 there are four extensions 2 which, starting from the optical element 1, run parallel to its optical axis 3.

In a particularly favorable manner, the optical element 1 is formed in one piece with its extensions 2, so that forces acting on the extensions 2 are ideally transmitted to the optical element 1 via the extensions 2, so that deformation of the optical element is specifically possible. Basically, two of the extensions 2 are sufficient to achieve simple deformations of the optical element. The number of four extensions 2 shown here is particularly useful for initiating astigmatism. FIG. 2 shows a view according to arrow II in FIG. 1 with a possible embodiment of an actuator 4, which here is intended in particular to initiate a two-wave deformation, ie an astigmatism. The single actuator 4 is connected via two transmission elements 5, each with two articulation points 6a, which are coupled to two of the extensions 2 via spring elements 7. Articulated rods 8 run from the two articulation points 6a to two further articulation points 6b, which are likewise connected to the two other extensions 2 via spring elements 7.

This structure makes it possible to generate the desired force introduction into the extensions 2 with the single actuator 4 by expanding or contracting the actuator 4, and thus a corresponding movement of the transmission elements 5.

If the actuator 4 is shortened in length in the illustration according to FIG. 2, then it or the transmission elements 5 will pull at the two articulation points 6a. A force is thus introduced into the two extensions 2, which are connected to the two articulation points 6 a by means of the spring elements 7, the force direction of which is directed in the direction of the optical axis 3. At the same time, the two articulation points 6b are pushed away from one another via the articulated rods 8, so that a force is introduced into the area of the appendages 2 corresponding to the articulation points 6b via the spring elements 7, which force extends from the optical axis 3 in the direction of the appendages 2.

In Figure 3a, these forces are again shown in principle according to the description just made. It can be clearly seen that there is an overall equilibrium of forces on the optical element 1, so that this cannot be adhered to very precisely, particularly for the preferred use in the field of lithography lenses Position will move.

FIG. 3b characterizes this requirement of the equilibrium of forces for a further application, here the initiation of a three-wave deformation. Of course, the presence of six of the extensions 2 would be necessary for such a three-wave deformation if the optical element 1 is to be constructed in accordance with the exemplary embodiment described so far, since two points of attack are required for each ripple of the deformation.

Of course, the actuator 4 according to FIG. 2 can also be moved in the other direction, so that the two pivot points 6a are pressed apart. Accordingly, the articulation points 6b are moved towards the optical axis 3, the mode of operation described above is thus reversed.

It should be clear that a construction, as described under FIG. 2, is only possible with an optical element 1, which is designed as a mirror, since otherwise the actuator 4, the transmission elements 5 and possibly also the articulated rods 8 are in the imaging area of the optical element 1 would protrude.

When using differently designed actuators 4, however, a corresponding optical element 1 can also be designed as a lens, as a plane-parallel plate or the like, which would then be comparable via corresponding actuators 4 with regard to the deformation to be initiated.

FIG. 4 shows an embodiment of the optical element 1 as a mirror, to which, as can be seen particularly clearly in the sectional view according to FIG. 5, a tubular extension 2 'is connected. The optical element 1 forms with its integrally formed with it tubular extension 2 'thus a kind of mirror pot 9. This has holding elements 10 which are not relevant for the present invention and which are also not described in more detail below.

The tubular extension 2 'of the mirror pot 9 can either be cylindrical, which can be particularly useful in terms of the forces to be introduced and the connection between the optical element 1 and the tubular extension 2' in its one-piece design.

In addition to this cylindrical design, however, a frustoconical design of the tubular extension 2 ', not shown here, is also conceivable. This can be particularly useful when used in the case of transparent optical elements 1, since a frustoconical, tubular extension 2 ″ opening on the side facing away from the optical element 1 offers the possibility of actuators 4 outside the region of the optical element which is of interest for transmission 1 to arrange.

On the other hand, when using a mirror, for example a frustoconical tubular extension 2 'tapering in the direction of the side facing away from the optical element 1, it may be expedient since the forces introduced into the optical element 1 can be varied here and a certain space saving compared to that cylindrical tubular extension 2 'shown here would be conceivable.

Basically, it should be noted, of course, that the frustoconical design of the tubular extension 2 'can produce force components in the direction of the optical axis. Although this allows a greater range of variation when using the required forces, it is also necessary to pay attention to the balance of forces here, so that the optical element does not move out of its predetermined target position emotional .

The illustration in FIG. 6 and the corresponding three-dimensional illustration in FIG. 7 show the mirror pot 9 with a device 11 for introducing a two-wave deformation into the optical element 1, ie a device 11 for initiating an astigmatism.

The device 11 accordingly has a number of devices 12 for introducing the force into the area of the tubular extension 2 ′ that is double the ripple of the deformation to be introduced, each of the devices 12 each having at least one actuator 13 which is not explicitly recognizable here. The actuators 13 arranged in the devices 12 can be designed in the conventional manner as piezo actuators, hydraulic or pneumatic actuators, electromechanical or electromagnetic actuators or the like. Two devices 12 are arranged on an axis 14 and have pressure elements 15, which in turn are each provided with the spring elements 7. The two pressure elements 15 are intended to introduce pressure forces, which are predominantly perpendicular to the optical axis 3, into the extension 2 'by mechanical contact with the extension 2'.

The two other devices 12 are arranged on an axis 16 oriented in the present case of astigmatism at a fixed angle of 90 ° to the axis 14. The two devices 12 are each provided with traction devices 17. In the exemplary embodiment shown here, the pulling devices 17 comprise the tubular extension 2 'due to their hook-like design and are thus able to pull the tubular extension 2 "in the direction of the optical axis 3.

The entire assembly of the four at a fixed angle other devices 12 can be rotated about the optical axis 3, for which purpose a drive device 18 indicated here in principle is provided. For the case shown here, the two-wave, ie astigmatistic, deformation can be introduced into the optical element 1 or the mirror pot 9 in any angular position in the plane perpendicular to the optical axis 3.

Fundamentally, the structure with the devices 12 can also be enlarged with regard to the number of devices 12, for example to six devices 12, wherein according to FIG 3 must effect. In addition to such a three-wave deformation caused by six of the devices 12, however, higher-wave deformations, for example four-, five- or six-wave deformations, can also be introduced into the mirror pot 9.

Several devices 11 of this type can also be combined with one another so that, for example, the corresponding devices 12 for inducing an astigmatism and in a plane parallel to them corresponding devices 12 for initiating a three-wave deformation can be arranged. Since both devices 11 can be rotated independently of one another in a particularly favorable manner, there is thus the possibility of introducing the two-shaft or multi-shaft deformations into the mirror pot 9 practically almost arbitrarily by superimposing the effect of the two, or possibly also other devices 11 without excessive effort in terms of the required actuators.

Of course, it also applies to the embodiments of the device 11 described here and not explicitly shown that they each have a balance of forces, that is, in an arrangement analogous to the illustration selected in FIG. 3a and FIG. 3b must be operated in order to avoid corresponding forces on the area of the holding elements 10, which could cause further undesired deformations in the mirror pot 10, which is particularly the case with the high-precision imaging properties, which are required for .Semiconductor lithography systems would not be acceptable.

In addition to the way illustrated here of mechanically introducing the forces for generating the desired deformation into the tubular extension 2 ', there is of course also the possibility of introducing the forces via magnetic elements 19 so that the force can be applied without mechanical contact, that is to say without contact. The use of magnetic elements 19 makes it possible to dispense with direct mechanical contact between the device 11 and the tubular extension 2 '. As a result, non-reproducible conditions, which result from friction or very difficult to control setting effects due to surface pressure, roughness, etc., can be avoided. The accuracy to be achieved, in particular with regard to the reproducibility of the introduction of the desired deformations, can thus be increased considerably.

It is particularly advantageous to vary the distance between two elements in magnetic contact or in magnetic effect with one another via the corresponding actuators 13 in the devices 12. By changing the distance, the magnetic forces also change and the corresponding counter element is attracted or repelled more strongly.

FIG. 8 shows a basic illustration of this, part of the mirror pot 9 being visible. This part of the mirror pot 9 is in the region of its tubular extension

2 'provided with the magnetic element 19. This magnetic see element 19 corresponds to a magnetic device 20 or an electromagnetic drive 20, which is fixed relative to the magnetic element 19. In the schematic diagram shown here, the electromagnetic drive 20 is connected to a base plate 22 via a holding element 21. The magnetic element 19 of the tubular extension 2 'works in a contactless manner with the electromagnetic drive 20. According to the schematic diagram in FIG. 8, forces can be generated in both directions, that is to say in the direction of the optical axis 3 and away from the optical axis between the two electromagnetic drives, as is shown in principle by the arrow 23.

Several solutions for deformation by means of electromagnetic and / or magnetic drives or elements can thus be implemented. As already mentioned above, the simplest possibility is to vary a distance between two elements that are in magnetic contact or in magnetic effect to one another. This structure will be discussed in more detail below. First, however, the second solution variant is to be presented, in which the drive principle is based on the contact between the magnetic element 19 and an electromagnetic drive 20, which has also already been mentioned.

Figure 9 shows a possible solution. A magnet 19 ', with the polarity shown in FIG. 9, is inserted as a magnetic element 19 in the area of the extension 2'. As shown here, this magnet 19 'can be connected as a discrete magnet 19' to the tubular extension 2 '. However, this requires a correspondingly high number of magnets 19 'and, moreover, only permits the discrete setting of the angular position for the deformation to be introduced in accordance with this number or the angular spacing of the magnets 19'. In addition, it is also conceivable that the magnetic element 19 is designed in the region of the tubular extension 2 'as a magnetic coating 19'', so that the tubular extension 2' has a continuous magnetic coating 19 '' at least on its side facing the optical axis 3. having. This enables any adjustment of the angular position for the intended deformation. This coating 19 ″ is shown in more detail in the following figures.

In FIG. 9, which is shown here by way of example with a discrete magnet, the magnet 19 'corresponds to an electromagnet 20' as an electromagnetic drive device 20. If the electromagnet 20 ', which is shown here in terms of its polarity, is such that repulsion occurs during operation between the magnetic element 19 and the electromagnetic drive means 20 can be influenced via a coil 24 on the one hand with regard to its polarity, so that either attraction or repulsion will take place between the magnetic element 19 and the electromagnetic drive means 20, and on the other hand can be by the current flowing through the coil 24, the magnetic field induced thereby can be changed with regard to the amount of the attraction or repulsion forces. With such a construction of the device 11 according to FIG. 9, a highly flexible construction is obtained which allows the forces which are introduced into the tubular extension 2 'of the optical element 1 to be varied almost arbitrarily with regard to their direction and strength ,

Due to the non-contact function, no frictional forces are caused when the device 11 is rotated about the optical axis 3, which could lead to corresponding deformations and stresses in the sub-μm range, as already indicated above, and which due to the friction generated heat further negative inputs could have flows on the imaging quality of the optical element 1.

The embodiment according to FIG. 10 shows a similar structure, with the electromagnetic drive device 20 and the magnetic element 19 being interchanged here. This means that the electromagnetic drive device 20, which is designed here as a moving coil 25, is arranged on the tubular extension 2 '. The moving coil 25 corresponds to the magnetic element 19, which is embodied here in a corresponding geometrical configuration, so that these elements can easily correspond to one another. In a manner known per se, depending on the voltage U which is applied to the plunger 25, the desired force between the magnetic element 19 and the electromagnetic drive 20 results, which can be varied in terms of direction and amount.

This embodiment has only the disadvantage that it is very difficult to adjust the angle about the optical axis 3. Accordingly, a structure can be selected which has several discrete angular positions. This can mean, for example, that a larger number of plunger coils 25, for example twelve, are arranged around the circumference of the mirror pot 9, so that here too the possibility of introducing multi-wave deformation into various, but discretely predetermined, angular positions can take place. The structure according to FIG. 10 with the plunger coil 25 is predestined for a combination with the structure of the optical element 1 according to FIG. 1, that is to say with individual discrete extensions 2.

Such a structure is shown in principle in FIG. 11, but with a different actuation principle. The structure according to FIG. 11 shows the mirror pot 9 in a view facing away from the mirrored surface. page. Twelve discrete devices 12 for introducing the force into the tubular extension 2 'can be seen in the mirror pot 9. Each of the devices 12 here has two magnets 26, 27, which are each supported by a variable-length actuator 28 on the base plate 22 arranged here in the interior of the mirror pot 9. The two magnets 26, 27 are poled so that one magnet 26 can repel itself and the magnetic element 19, which is designed here as a magnetic coating or layer 19 ″. The distance between the respective magnet 26, 27 and the magnetic layer 19 ″ can be changed by the respective actuator 28. Depending on the distance, the magnetic layer 19 ″ and thus the tubular extension 2 ′ connected to it is attracted or repelled by the magnets 26, 27 more or less.

As already mentioned above, instead of the magnetic layer 19 ″, a number of individual magnets 19 ′ can also be integrated into the tubular extension 2 ′, which means that only discrete angular positions can be taken into account when initiating the deformation. The rotation of the base plate 22 and devices 12, which is also possible fundamentally in the structure according to FIG. 11, could thus possibly be omitted. Although the above-mentioned variation with regard to the angle is partially lost, a variation of the angle in twelve different positions may be sufficient for corresponding applications, and the structure can thus become more stable.

The magnetic layer 19 ″ can consist of a material that is magnetic per se, that is to say it can be a type of vapor-deposited or sputtered-on permanent magnet. As an alternative to this, however, a layer 19 ″ made of a magnetic material, for example iron or the like, would also suffice, which interacts with the magnets 26, 27, for example designed as permanent magnets. FIG. 12 shows a comparable structure, in which case the tubular extension 2 ′ is provided with the magnetic layer 19 ″ both on its side facing the optical axis 3 and on its side facing away from the optical axis 3. Only one of the actuators 28, which carries the one magnet 26, is then arranged on the side of the tubular extension 2 ′ facing the optical axis 3. The magnet 27 is arranged with the second actuator 28 on the side of the tubular extension 2 'facing away from the optical axis 3.

The possibility of varying the deformation to be initiated is comparable here, but corresponding advantages with regard to the structural design can result.

In principle, all of the embodiments shown here can of course also be combined with one another, in particular it is also conceivable to arrange the devices 12 with their structure according to FIG. 11 only on the side of the tubular extension 2 'facing away from the optical axis 3, so that the optical Element 1 can also be designed as a transparent optical element 1, for example as a lens.

For all configurations of the devices 12, with the exception of the plunger coil 25, the rotation about the optical axis 3 in a plane perpendicular to this optical axis 3 can be useful, which in turn can be limited in its variation by integrating discrete magnets or the like , With a correspondingly high number of discrete magnets and / or fixed devices 12, however, this can be of secondary importance.

This results in an astigmatism and high Herwell, especially three-wave deformation optical element 1 to be influenced very well in a simple, reliable and compact structure, which can be easily integrated into an imaging system, for example in a lens for semiconductor lithography, with regard to its space requirement and its control options.

In order to introduce the forces, essentially all known arrangements can be used in all arrangements, that is to say both the actuator 4 according to the illustration in FIG. 2 and the actuators 13 of FIGS. 6 and 7 integrated in the respective devices 12 and the actuators 28 of FIGS Actuators are used. It is conceivable for the actuation of the actuators 4, 13, 28, the use of spring forces, pneumatic or hydraulic cylinders as well as the particularly cheap and advantageous use of piezoelectric ducks, in particular as piezo stacks.

The use of magnetic or electromagnetically active devices 12 results in further favorable properties. Due to the electromagnetic structure, the forces can be introduced and switched on very evenly, so that there are no additional displacements or deformations of the structure due to the support of the reaction forces, since all of the forces that cancel each other out can be applied evenly and simultaneously , In addition, the combination of the introduction of several ^• different undulations, which, as already mentioned above in Figures 6 and 7, is possible fundamentally always considerably simplified in electromagnetic devices 11, as for example, in assemblies with discrete angular positions as shown in FIG 11 or 12 no additional elements are necessary. All electromagnetic drive elements can impress both tensile and compressive forces on the optical element 1, only the polarity of the magnets and / or the introduction of the corresponding voltage direction and / or current direction is decisive.

Since the desired deformations to be introduced, in particular when the optical element 1 is a mirror, are very small and are only in the sub-μm range or nanometer range, miniaturized electromagnetic drives can be used for this. In addition to the structural advantages, this also leads to lower power consumption with a correspondingly reduced heat development. The heat generated nevertheless can be dissipated, for example, by direct water cooling or the like. This heat dissipation can be integrated in the base plate 22, for example.

The preferred application for a device 11, as has been described here, is in the area of optical elements 1, which are used for imaging devices in projection exposure systems in microlithography.

Claims

claims

1. Optical element with an optical axis, in particular for an exposure lens in semiconductor lithography, characterized by at least one extension (2,2 ') in the direction of the optical axis (3).

2. Optical element according to claim 1, characterized by at least four extensions (2) distributed at a uniform distance over the circumference of the optical element (1).

3. Optical element according to claim 1 or 2, characterized by its one-piece design with the extensions

(2).

Optical element according to claim 1, characterized in that the at least one extension (2,2 ') is designed as exactly one at least approximately tubular extension (2').

Optical element according to claim 4, characterized by its one-piece construction with the tubular extension (2 ').

6. Optical element according to claim 4 or 5, characterized in that the tubular extension (2 ') is designed in the manner of a cylindrical tube section.

7. Optical element according to claim 4 or 5, characterized in that the tubular extension (2 ') is designed in the manner of a frustoconical tube section.

8. Optical element according to one of claims 1 to 7, characterized by its design as a mirror.

9. Device for initiating a two- or multi-wave deformation in an optical element according to one of claims 1 to 8, characterized in that at least one device (12) for introducing a force into the extension (2,2 ') in the region of each Extensions (2) or the extension (2 ') is arranged.

10. The device according to claim 9, characterized in that the sum of the forces introduced disappears.

11. The device according to claim 9 or 10, characterized in that a double compared to the ripple of the deformation to be initiated number of devices (12) for introducing the force in the region of each of the extensions (2) or the extension (2 ¹ ) are arranged.

12. The apparatus of claim 9, 10 or 11, characterized in that by an actuator (4,13,28) a force which pushes the extension (2,2 ') away from the optical axis (3) or to the optical axis (3) pulls on the extension (2,2 ') can be stamped.

13. Device according to one of claims 9 to 12, characterized in that the at least one device (12) for introducing the force comprises a magnetic device (20) which is contactless with at least one magnetic element (19) in the region of the extension (2nd , 2 ') corresponds.

14. The apparatus according to claim 13, characterized in that a distance between the magnetic device (20) and the at least one magnetic element (19) by means of the actuator (28) for influencing the force introduced is variable.

15. The apparatus of claim 13 or 14, characterized in that the at least one magnetic element (19) consists of a plurality of discrete magnets (19 ') integrated in the extension (2,2').

16. The apparatus according to claim 13 or 14, characterized in that the at least one magnetic element (19) consists of at least one magnetic coating (19 '') of the extension (2,2 ').

17. The apparatus according to claim 13, characterized in that the at least one magnetic element (19) and / or the magnetic device (20) are designed electromagnetically, the applied force being changeable by influencing the magnetic strength (coil 24).

18. Device according to one of claims 9 to 12, characterized in that the at least one device (12) for introducing the force has the at least one actuator (13) which, at least in the event of the application of the force, has a direct or indirect mechanical contact with the extension (2,2 ').

19. The apparatus according to claim 18, characterized in that between the actuator (13) and the extension spring elements

(7) are arranged.

20. Device according to one of claims 9 to 19, characterized in that the at least one device (12) for introducing the force, in particular when used together with a tubular extension (2 '), is rotatably arranged about the optical axis (3) ,

21. The apparatus according to claim 17, characterized in that the at least one magnetic device (20) from we- at least one plunger coil (25) fixedly connected to the extension (2,2 ').

22. The apparatus according to claim 9 or 10, characterized in that in the case of a two-shaft deformation (astigmatic deformation) on the extension (2 ') or the extensions (2) four fastening points (6a, 6b) at an angular distance of about 90 ° around the circumference of the optical element (1), two of the adjacent fastening points (6a, 6b) being connected to one another via articulated rods (8), and exactly between two opposite fastening points (6a, 6b) variable-length actuator (4) is arranged.

23. Optical element with an optical axis for an exposure lens in semiconductor lithography, characterized by at least one extension (2,2 ') in the direction of the optical axis (3).

24. Optical element according to claim 23, characterized by training as a mirror.

25. Use of a device according to one of claims 1 to 24, for introducing multi-wave deformation into the optical element (1), which is used in an imaging device, the imaging device being part of a projection exposure system for microlithography.