DE102024208858A1 - Damper for dissipating mechanical vibration energy, damping arrangement and system for semiconductor technology - Google Patents

Abstract

The invention relates to a damper (30, 40, 50) for a semiconductor technology system (1, 101), comprising at least one damping element (31, 41, 51) and two adjacent components (43.1, 43.2, 53.1, 53.2). The damping element (31, 41, 51) comprises a shape memory material with at least one main damping direction, and the damping element (31, 41, 51) is connected to the components (43.1, 43.2, 53.1, 53.2) such that tensile and compressive forces can be transmitted at least in the main damping direction. The damper (30, 40, 50) is characterized in that the damper (30, 40, 50) comprises an elastic element (42, 52.1, 52.2) for generating a mechanical restoring force in the direction of the main damping direction.
The invention further relates to a damping arrangement (60) comprising a damper (30, 40, 50) according to one of the explained embodiments. The invention further relates to a system for semiconductor lithography (1, 101) comprising a damper (30, 40, 50) according to one of the explained embodiments and/or a damping arrangement (60) according to one of the explained embodiments.

Description

The invention relates to a damper for dissipating mechanical vibration energy, a damping arrangement, in particular a tuned mass damper, for damping components exposed to parasitic vibrations, and a system for semiconductor lithography, in particular a projection exposure system, which is equipped with a damper and/or a damping arrangement.

In many technical disciplines, it is necessary to prevent or effectively dampen vibrations of individual elements within higher-level systems. For example, in construction, vibrations of tall buildings or bridges are reduced by equipping the structures with a damping mass, such as a heavy pendulum. This absorbs part of the kinetic energy generated when the structure is vibrated, for example, by wind, thus reducing the vibration of the structure itself.

Vibration dampers are also used in vehicle construction, for example in combustion engines, to reduce inertial forces.

The vibration damper typically has a damping mass, which is mechanically coupled to the object to be damped via a damping spring. Additional damping elements may be present to dampen the vibration or dissipate the vibration energy. The properties of these components—the damping mass, the damping spring, and, if applicable, the damping element—determine the natural frequency of the vibration damper. The frequency of the system to be damped that is most effectively damped by the vibration damper depends on the natural frequency of the vibration damper. A damped vibration damper tuned to a natural frequency in this way is also referred to as a tuned mass damper.

Dampers and damping arrangements, particularly tuned mass dampers, are also used in projection exposure systems for semiconductor lithography, which feature highly precisely manufactured and positioned optical components. It goes without saying that any form of vibration or shock, whether during transport of such a system or during its operation, for example due to seismic events, has a significantly negative impact on the imaging quality of the system and thus on its overall performance. Conventional mounting technology for optical components alone is generally not sufficient to dampen introduced vibrations sufficiently quickly, as it is designed more for precise and stable mounting than for vibration damping. In the past, various approaches have been taken to either effectively prevent vibrations, particularly of optical components in projection exposure systems, or - if they do occur - to dampen them to an acceptable level within a reasonable time.

The German patent application DE 10 2016 202 127 A1 discloses a damping arrangement comprising a damping element comprising a magnetic shape memory alloy and means suitable for exposing the damping element to a magnetic field. The damping arrangement is designed, for example, as a vibration damper, with the damping element being used as a damper spring. The damping effect is based on the pseudoplastic behavior of the magnetic shape memory alloys.

Pseudoplastic is defined by the fact that the material can be plastically deformed within certain limits by an external force. The plastic deformation of the component is reversible by applying an opposing external force. Thus, the geometry of the component is maintained or identical before and after the pseudoplastic deformation due to the opposing external forces compared to plastic deformation. This also applies to thermal shape memory alloys, which also exhibit a pseudoplastic region.

In the case of magnetic shape memory alloys, the pseudoplastic effect can be explained by a reorientation of tetragonal, body-centered cells present in the martensite phase of the material, which exhibit a preferred magnetic direction. The reorientation from one direction to a second direction leads to the shape change, which, however, is based only on a shifting or folding of the cells, meaning that the crystal structure is retained during the shape change. In the case of a damping element and/or a damping spring, the shape change predominantly takes the form of stretching or compression.

As can be seen in a force-displacement diagram of a magnetic shape memory alloy, the stretching and compression are characterized by strong hysteresis, which is an expression of energy dissipation, thus causing damping by the material. The hysteresis is also based on the effect of reorientation, as explained above for pseudoplastic deformation.

The material can only be used as described in the German patent application DE 10 2016 202 127 A1 disclosed, can be used as a damper spring with a spring stiffness when an external restoring force acts on the shape memory material, causing the damper spring to return to its previous shape. In the case of the DE 10 2016 202 127 A1 the means suitable for exposing the damping element to a magnetic field.

Alternatively, the damping element also exhibits a damping effect without an external restoring force, where the movement is caused, for example, by a vibration of a component connected to the damping element. Due to the non-resilient (elastic) property, when the external force is reduced to zero, the deformation (stretching/compression) is frozen according to the principle of pseudoplasticity, i.e., the deformed shape is retained. This can result in an asymmetric damping effect due to a displacement of the connection point of the damping element from a central position within the pseudoplastic range, as shown in the figure description ( 3 ) is explained in detail. This can lead to limited damping in one direction.

The external force for resetting the damping element can be applied by a corresponding magnetic field, as explained. Alternatively, the external force can also be applied by a mechanical force applied perpendicular to the damping effect, such as by means of a spring, as described in the German patent application DE 10 2017 200 638 A1 is revealed.

The reorientation of the cells can be achieved by applying heat energy instead of an external mechanical force, or in the case of magnetic shape memory alloys, by an external magnetic field, or by applying heat energy in the case of thermal shape memory alloys. In contrast to magnetic shape memory alloys, the principle of recovery through heat input is based on a transition from martensite to austenite, which in turn transforms into martensite upon cooling, while retaining its shape during cooling.

The use of a magnetic field to generate the external force has the disadvantage that the permanent magnets or electromagnets commonly used for this purpose require installation space and the magnetic fields can have a detrimental, parasitic effect on other components. This applies in particular to components made of ferromagnetic material or actuators that draw their energy from a magnetic field, such as Lorentz motors. The attachment of a mechanical spring to generate the external force perpendicular to the damping direction has the disadvantage that when the damping elements are stretched or compressed, friction occurs between the mechanical spring and the damping elements. This can, for example, generate particles, which should be avoided, especially in projection exposure systems. Furthermore, stick-slip effects due to friction lead to highly nonlinear damping effects.

The object of the present invention is to provide a damper which eliminates the disadvantages of the prior art explained above.

This object is achieved by a device having the features of independent claim 1. The subclaims relate to advantageous developments and variants of the invention.

A damper according to the invention for a semiconductor technology system comprises at least one damping element and two adjacent components, wherein the damping element comprises a shape-memory material with at least one main damping direction. Furthermore, the damping element is connected to the components in such a way that tensile and compressive forces can be transmitted at least in the main damping direction. According to the invention, the damper has an elastic element for generating a mechanical restoring force in the direction of the main damping direction. This enables the damping element to restore its position after a pseudoplastic deformation, whereby the application of the force in the damping direction prevents friction from occurring between the point of application of the mechanical restoring force and the damping element.

In one embodiment of the invention, the elastic element can be designed as a solid-state spring. This has the advantage that the spring can be optimized for the given installation space. Alternatively, and given the available installation space, simple coil springs, leaf springs, or any other suitable type of elastic element can also be used.

In particular, the mechanical restoring force can be designed such that, without any external force acting on the damper, the damping element is in the middle of its pseudoplastic range due to the restoring force. This has the advantage that, after the external force acting on the damper is removed, the damper exhibits a symmetrical damping path. The travel available for damping is therefore the same regardless of the direction of the previous external force acting on the damping element and regardless of the direction of the subsequent external force. The elastic element imparts dynamic stiffness to the damping element, allowing the damper to be used as a highly damping elastic element.

In a further embodiment, at least one of the components can have at least one interface to at least one component and/or mass to be damped. The interface can, for example, be a connecting surface for bonding, welding, soldering, or another material-to-material and/or form-fitting and/or force-fitting connection technology.

In particular, the components can be designed as the base and cover of the damper. The damper can thus be configured as a standalone functional unit, which can be connected to one or, in the case of multiple interfaces, to multiple components, or, in the case of a tuned mass damper, to a component to be damped and a mass. The damper can thus be used, for example, as a replacement for elastomers frequently used in tuned mass dampers, some of which may no longer be used due to a future ban on per- and polyfluorinated chemicals (PFAS).

In a further embodiment, the damping element and the mechanical restoring force can be configured such that the damper has a predetermined natural frequency. The damper can thus be adjusted to a frequency to be damped of a component connected to the damper, which frequency has been determined on the component. Adjusting to a predetermined natural frequency of the damper can be used both in the case of a tuned mass damper and in the case of a decoupling damper between two components.

In a further embodiment, the damping element may comprise a magnetic shape memory alloy.

In particular, the magnetic shape memory alloy can contain nickel, manganese, and gallium, such as Ni2MnGa. Magnetic shape memory alloys have the advantage that their base materials do not interact with substances present in projection exposure systems, particularly in the area of the optical elements, such as hydrogen, especially hydrogen radicals.

In a further embodiment, the damping element may comprise a thermal shape memory alloy.

In particular, the thermal shape memory alloy can be designed in such a way that it exhibits its pseudoelastic properties in the range of the temperature prevailing during the damper's operation. In the pseudoelastic range, the damping element exhibits elastic properties, thus it can function both as a damping element and as an elastic element. In this case, the mechanical (and magnetic or thermal) restoring force can be dispensed with.

Furthermore, the thermal shape memory alloy can contain nickel and titanium. Due to the interaction of titanium with hydrogen or hydrogen radicals, the so-called hydrogen embrittlement of titanium, this embodiment can only be used without further measures in areas of a projection exposure system where there is no hydrogen, i.e. predominantly outside the volume in which the optical elements are arranged. For all other semiconductor technology systems, which often do not contain hydrogen, its use can be advantageous, particularly if the material exhibits its pseudo-elastic range around the operating temperature of the system. Alternatively, the shape memory alloy can be protected from hydrogen with a suitable coating or encapsulation, which also enables the alloy to be used in areas with hydrogen.

The idea of using a thermal shape memory material in a damping element of a damper for a semiconductor lithography system with pseudoelastic properties in the range of an operating temperature prevailing during use of the damper can, from the inventor's point of view, be regarded as an independent invention, even if it does not fall under claim 1 underlying this patent application.

In particular, the thermal shape memory alloy can comprise one of the following alloys: FeMnSi (iron-manganese-silicon), CuZn (copper-zinc), CuZnAl (copper-zinc-aluminum), CuAlNi (copper-aluminum-nickel), FeNiAl (iron-nickel-aluminum), or ZnAuCu (zinc-gold-copper). Thus, in addition to the alloys that are usually less suitable due to hydrogen embrittlement, other possible alloys are also conceivable.

A damping arrangement according to the invention comprises a damper according to one of the embodiments explained above. The damping arrangement can further comprise the components and/or masses explained above, which are connected to one another by the damper and whose relative movement to one another is damped by the damper.

In particular, the damping arrangement can comprise a mass and a component to be damped, with the damper arranged between the mass and the component to be damped. This damping arrangement corresponds to a tuned mass damper as explained above.

A system according to the invention for semiconductor lithography comprises a damper according to one of the embodiments explained above and/or a damping arrangement according to one of the embodiments explained above.

In particular, the system for semiconductor lithography can be designed as a projection exposure system.

• 1 schematisch im Meridionalschnitt eine Projektionsbelichtungsanlage für die EUV-Projektionslithografie,
• 2 schematisch im Meridionalschnitt eine Projektionsbelichtungsanlage für die DUV-Projektionslithografie,
• 3 ein Detail der Erfindung zur Erläuterung der Dämpfungswirkung,
• 4 eine schematische Darstellung der Erfindung, und
• 5 ein Ausführungsbeispiel der Erfindung.

In the following, embodiments and variants of the invention are explained in more detail with reference to the drawings.

• 1 schematic meridional section of a projection exposure system for EUV projection lithography,
• 2 schematic meridional section of a projection exposure system for DUV projection lithography,
• 3 a detail of the invention to explain the damping effect,
• 4 a schematic representation of the invention, and
• 5 an embodiment of the invention.

In the following, with reference to the 1 The essential components of a projection exposure system 1 for microlithography are described by way of example. The description of the basic structure of the projection exposure system 1 and its components is not intended to be limiting.

One embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a radiation source 3, an illumination optics 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system. In this case, the illumination system does not include the light source 3.

A reticle 7 arranged in the object field 5 is illuminated. The reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced, in particular in a scanning direction, via a reticle displacement drive 9.

In the 1 For explanation, a Cartesian xyz coordinate system is shown. The x-direction is perpendicular to the drawing plane. The y-direction is horizontal and the z-direction is vertical. The scanning direction is in the 1 along the y-direction. The z-direction runs perpendicular to the object plane 6.

The projection exposure system 1 comprises a projection optics 10. The projection optics 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 runs parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the image plane 12 in the region of the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, in particular along the y-direction, via a wafer displacement drive 15. The displacement of the reticle 7, on the one hand, via the reticle displacement drive 9, and the displacement of the wafer 13, on the other hand, via the wafer displacement drive 15, can be synchronized with each other.

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

The illumination radiation 16 emanating from the radiation source 3 is bundled by a collector 17. The collector 17 may be a collector with one or more ellipsoidal and/or hyperboloidal reflection surfaces The at least one reflection surface of the collector 17 can be exposed to the illumination radiation 16 at grazing incidence (GI), i.e., at angles of incidence greater than 45° relative to the normal direction of the mirror surface, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector 17 can be structured and/or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light.

After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the radiation source 3 and the collector 17, and the illumination optics 4.

The illumination optics 4 comprises a deflecting mirror 19 and, downstream of this in the beam path, a first facet mirror 20. The deflecting mirror 19 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first facet mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugated to the object plane 6 as the field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, which are also referred to below as field facets. Of these facets 21, 1 only a few examples are shown.

The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partially circular edge contour. The first facets 21 can be designed as flat facets or, alternatively, as convexly or concavely curved facets.

As for example from the DE 10 2008 009 600 A1 As is known, the first facets 21 themselves can also be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 20 can in particular be designed as a microelectromechanical system (MEMS system). For details, please refer to DE 10 2008 009 600 A1 referred to.

Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction.

In the beam path of the illumination optics 4, a second facet mirror 22 is arranged downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006/0132747 A1 , the EP 1 614 008 B1 and the US$6,573,978 .

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

The second facets 23 can also be macroscopic facets, which can be round, rectangular or hexagonal, or alternatively facets composed of micromirrors. In this regard, reference is also made to the DE 10 2008 009 600 A1 referred to.

The second facets 23 can have planar or alternatively convex or concave curved reflection surfaces.

The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (fly's eye integrator).

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

With the help of the second facet mirror 22, the individual first facets 21 are imaged into the object field 5. The second facet mirror 22 is the last beam-forming mirror or actually the last mirror for the illumination radiation 16 in the beam path before the object field 5.

In a further embodiment of the illumination optics 4 (not shown), in the beam path between the second facet mirror 22 and the object field 5, a transmission optics system can be arranged, which contributes in particular to the imaging of the first facets 21 into the object field 5. The transmission optics can have exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optics can in particular comprise one or two mirrors for normal incidence (NI mirrors, normal incidence mirrors) and/or one or two mirrors for grazing incidence (GI mirrors, grazing incidence mirrors).

The illumination optics 4 has in the version shown in the 1 As shown, after the collector 17 there are exactly three mirrors, namely the deflection mirror 19, the field facet mirror 20 and the pupil facet mirror 22.

In a further embodiment of the illumination optics 4, the deflection mirror 19 can also be omitted, so that the illumination optics 4 can then have exactly two mirrors after the collector 17, namely the first facet mirror 20 and the second facet mirror 22.

The imaging of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optics into the object plane 6 is usually only an approximate imaging.

The projection optics 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

In the 1 In the example shown, the projection optics 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or a different number of mirrors M1 are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics 10 are doubly obscured optics. The projection optics 10 has an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6, for example, 0.7 or 0.75.

Reflection surfaces of the mirrors Mi can be designed as freeform surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one rotational symmetry axis of the reflection surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

The projection optics 10 has a large object-image offset in the y-direction between a y-coordinate of a center of the object field 5 and a y-coordinate of the center of the image field 11. This object-image offset in the y-direction can be approximately as large as a z-distance between the object plane 6 and the image plane 12.

The projection optics 10 can, in particular, be anamorphic. It has, in particular, different magnifications βx, βy in the x- and y-directions. The two magnifications βx, βy of the projection optics 10 are preferably (βx, βy) = (+/- 0.25, +/- 0.125). A positive magnification β means imaging without image inversion. A negative sign for the magnification β means imaging with image inversion.

The projection optics 10 thus leads to a reduction in the ratio 4:1 in the x-direction, i.e. in the direction perpendicular to the scanning direction.

The projection optics 10 results in a reduction of 8:1 in the y-direction, i.e. in the scanning direction.

Other magnifications are also possible. Magnifications with the same sign and absolutely identical in the x and y directions, for example, with absolute values of 0.125 or 0.25, are also possible.

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

Each of the pupil facets 23 is assigned to exactly one of the field facets 21 to form a respective illumination channel for illuminating the object field 5. This can, in particular, result in illumination according to the Köhler principle. The far field is divided into a plurality of object fields 5 using the field facets 21. The field facets 21 generate a plurality of images of the intermediate focus on the pupil facets 23 assigned to them.

The field facets 21 are each imaged onto the reticle 7 by an associated pupil facet 23, superimposed on one another, to illuminate the object field 5. The illumination of the object In particular, the field 5 is as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

By arranging the pupil facets, the illumination of the entrance pupil of the projection optics 10 can be geometrically defined. By selecting the illumination channels, in particular the subset of the pupil facets that guide light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting.

A likewise preferred pupil uniformity in the area of defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by redistributing the illumination channels.

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

The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

The entrance pupil of the projection optics 10 cannot usually be precisely illuminated with the pupil facet mirror 22. When the projection optics 10 images the center of the pupil facet mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found in which the pairwise determined distance of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in spatial space. In particular, this surface exhibits a finite curvature.

It is possible that the projection optics 10 have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second facet mirror 22 and the reticle 7. With the help of this optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

In the 1 In the illustrated arrangement of the components of the illumination optics 4, the pupil facet mirror 22 is arranged in a surface conjugated to the entrance pupil of the projection optics 10. The field facet mirror 20 is arranged tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the deflection mirror 19.

The first facet mirror 20 is arranged tilted to an arrangement plane which is defined by the second facet mirror 22.

2 shows schematically in meridional section a further projection exposure system 101 for DUV projection lithography, in which the invention can also be used.

The structure of the projection exposure system 101 and the principle of imaging is comparable to that in 1 described structure and procedure. Identical components are available with a 100% difference 1 raised reference symbols, the reference symbols in 2 So start with 101.

In contrast to a 1 Due to the longer wavelength of the DUV radiation 116 used as useful light in the range from 100 nm to 300 nm, in particular from 193 nm, in the EUV projection exposure system 101 described, refractive, diffractive and/or reflective optical elements 117, such as lenses, mirrors, prisms, cover plates and the like, can be used for imaging or illumination in the DUV projection exposure system 101. The projection exposure system 101 essentially comprises an illumination system 102, a reticle holder 108 for receiving and precisely positioning a reticle 107 provided with a structure, by means of which the later structures on a wafer 113 are determined, a wafer holder 114 for holding, moving and precisely positioning this wafer 113 and a projection lens 110 with a plurality of optical elements 117, which are held via mounts 118 in a lens housing 119 of the projection lens 110.

The illumination system 102 provides DUV radiation 116 required for imaging the reticle 107 on the wafer 113. A laser, a plasma source, or the like can be used as the source for this radiation 116. The radiation 116 is shaped in the illumination system 102 via optical elements such that the DUV radiation 116, upon impinging on the reticle 107, exhibits the desired properties with regard to diameter, polarization, wavefront shape, and the like.

The structure of the subsequent projection optics 101 with the lens housing 119 differs Apart from the additional use of refractive optical elements 117 such as lenses, prisms, end plates, it is in principle not different from the 1 described structure and is therefore not described further.

3 shows a detail of a damper 30, in which only the damping element 31 is shown. The damping element 31 is made of a shape memory alloy. As explained above (introduction), both magnetic and thermal shape memory alloys can be used. Shape memory alloys are characterized, as explained, by a so-called pseudoplastic region and can be used within this region as a damping element 31 for an externally acting force. The externally acting force can, for example, be a mechanical force caused by parasitic vibrations.

In the case of a damping arrangement designed as a tuned mass damper, the damper 30 is arranged between the mass (not shown) and a component to be damped (not shown) and is connected to the mass and the component in such a way that both tensile and compressive forces can be transmitted. As a result, an external force causes both compression and expansion of the damping element 31 in a direction referred to as the main damping direction, which is 3 represented by a double arrow.

Due to the parasitic vibrations, constantly changing external forces acting in opposite directions act on the damping element 31, so that the movement of the damping element 31 is damped by the deflection in the range of pseudoplastic properties referred to as the damping range D _max , whereby the movement of the tuned absorber mass is damped. Due to the lack of elastic stiffness in the pseudoplastic range of the damping element 31, the operating point P _Ao , P _Au of the damping element 31 can deviate within the available damping range D _max from a 3 shift the middle operating point designated as P _Am in the middle of the damping range D _max towards a lower P _D1 and an upper end point P _D2 of the damping range D _max .

The operating point P _Ao , P _Au is defined by the deflection of the damping element 31, which the damping element 31 assumes without an externally acting force, for example when an external force acts on the damping element 31 in the form of a sine oscillation at 0° and 180°.

If the operating point P _Ao , P _Au , as in the 3 represented by the points P _Ao and P _Au as an example, displaced from the center P _Am , the damping effect is smaller in the case of an external force acting in the direction of the displacement of the operating point P _Au , P _Au than in the case of an external force acting opposite to the direction of the displacement of the operating point P _Ao , P _Au , because the possible deflection is greater.

An additional continuous restoring force (see 4 The external force acting on the damping element 31 can be used to adjust the operating point P _Am , thereby ensuring a symmetrical damping deflection independent of the temporary parasitic force last acting on the damping element 31. Furthermore, the geometry of the damping element 31 and the external mechanical restoring force can be used to adjust the stiffness of the damper 30 and, in coordination with the connected mass or component mass, a frequency to be damped.

As an alternative to the additional restoring force, when using a thermal shape memory alloy, the material of the shape memory alloy can be adjusted such that the temperature prevailing during use of the damper 30 lies in a temperature range between the austenite finish temperature and the critical martensite temperature of the material. In this temperature range, a thermal shape memory material, and thus the damping element 31, behaves pseudo-elastically. This means that in this temperature range, a deformation of the damping element 31 caused by an external mechanical force reverses after the external mechanical force is removed without the need for an opposing external mechanical force or thermal heat input. The material therefore behaves like an elastic material in this temperature range, with the pseudo-elasticity formally following the elasticity of the material and forming a plateau in the force-displacement diagram. The temperature range defined by the austenite finish temperature and the critical martensite temperature can be reduced by a suitable alloy, for example, to room temperature or to a temperature that is reached during operation of a 1 The temperature or temperature range used in the projection exposure system 1 described above can be adjusted. The stiffness of the damping element, which in this case acts as a spring, can be adjusted, for example, by the geometry of the damping element 31.

4 shows a schematic system diagram of a damper 40 with a spring 42 arranged parallel to the damping element 41 formed elastic element for generating an external restoring force. Both the damping element 41 and the spring 42 are connected via connections 44.1, 44.2, 45.1, 45.2 to a component of the damper 40 formed as a base 43.1 and a cover 43.2 in such a way that both tensile forces and compressive forces can be exerted on the damping element 41 and the spring 42. The base 43.1 and the cover 43.2 each have an interface 46.1, 46.2 for connecting the damper 40 to a damper mass or a component (both in the 4 not shown). Depending on the design of the damping element 41 and the spring 42, the 3 explained mean operating point P _Am for the damper 40 can be set corresponding to previously defined requirements.

5 shows an embodiment of a damping arrangement 60 with a damping mass 57 and a component 58 to be damped, which due to the exemplary embodiment for a damping arrangement 60 both in the 5 are shown in dashed lines and a damper 50, which has an elastic element arranged parallel to the damping element 51 and designed as a spring 52 for generating an external restoring force. The spring 52 is designed as several solid-state springs 52.1, 52.2, wherein in the 5 In the illustrated embodiment, two solid-state springs 52.1, 52.2 are formed between a component of the damper 50 designed as a base 53.1 and a cover 53.2. Both the solid-state springs 52.1, 52.2 and the damping element 51 are connected via connections 55.11, 55.12, 55.21, 55.22, 54.1, 54.2, respectively to the base 53.1 and the cover 53.2 of the damper 50 in such a way that both tensile and compressive forces can be exerted on the damping element 51 and the spring 52. The base 53.1 and the cover 53.2 each have an interface 56.1, 56.2 for connecting the damper 50 to the absorber mass 57 or to the component 58 to be damped. Depending on the design of the damping element 51 and the springs 52.1, 52.2, the 3 explained mean operating point P _Am for the damper 50 can be set corresponding to the previously defined requirements.

The connection of the base 56.1 and the cover 56.2 to the damping element 52 can be achieved, for example, by welding, gluing, or soldering, whereby compressive and tensile forces can be exerted on the damping element 51 and the springs 52.1, 52.2. Due to the flat connection and the resulting lack of possibility of transverse contraction during expansion or compression, the material of the damping element 51 in the area of the connection surfaces 54.1, 54.2 does not contribute to damping, thus acting as a passive dead zone. However, this is negligible compared to the overall effect of the damping arrangement.

The elastic stiffness of the damping arrangement 50 is predominantly determined by the stiffness of the springs 52.1, 52.2. The stiffness of the damping element 51 is nonlinear and depends on the current position in the hysteresis curve. The gradient in the hysteresis curve corresponds to the stiffness of the material; thus, the stiffness is high at the beginning of a deformation (large gradient) and then decreases upon reaching the region typical for hysteresis with a comparatively low gradient or a plateau (flat gradient). For successful return, the ratio of the stiffnesses between the springs 52.1, 52.2 and the damping element 51 must be designed such that the force generated by the springs 52.1, 52.2 is greater than the hysteresis width of the damping element 31. When designing the damper 50, the springs 52.1, 52.2 are designed in particular such that the non-linear effects caused by the hysteresis are as small as possible in relation to the linear behavior of the springs 52.1, 52.2, which also advantageously makes the system easier to model.

Magnetic shape memory alloys for use in a damping element 31, 41, 51 typically have an elongation in the pseudoplastic range of up to 6%.

The damper 30, 40, 50 is preferably used in locations where it is not part of a control system, since the control becomes comparatively complex due to the strong hysteresis of the damper 30, 40, 50. The damper 30, 40, 50 can therefore be used in particular as a tuned mass damper, as an end stop, and wherever passive damping is required.

In particular, due to the materials used, the high elongation and the strong damping effect, the damper 30, 40, 50 can be used as a replacement for the elastomers containing per- and polyfluorinated chemicals (PFAS), which will be banned in the future.

Furthermore, shape memory alloys can also be manufactured in such a way that, in addition to the damping in the tension-compression direction, a damping effect, i.e. a reorientation of the cells (initiation), can be achieved when the damping element is subjected to bending and/or shearing and/or torsion loading.

List of reference symbols

1

Projection exposure system

2

lighting system

3

Radiation source

4

Lighting optics

5

Object field

6

Object level

7

Reticle

8

Reticle holder

9

Reticle displacement drive

10

Projection optics

11

Image field

12

Image plane

13

wafers

14

Wafer holder

15

Wafer relocation drive

16

EUV radiation

17

collector

18

Intermediate focal plane

19

Deflecting mirror

20

Faceted mirror

21

facets

22

Faceted mirror

23

facets

30

mute

31

Damping element (shape memory alloy)

40

mute

41

Damping element

42

Solid spring

43.1,43.2

base, lid

44.1,44.2

Connection surface damping element to floor/cover

45.1,45.2

Connection surface spring to base/lid

46.1,46.2

Mass/component interface(s)

50

mute

51

Damping element (shape memory alloy)

52.1,52.2

Feather

53.1,53.2

base, lid

54.1,54.2

Connection damping element

55.1x,55.2x

Spring connection

56.1,56.2

Mass/component interface(s)

57

absorber mass

58

component

60

Damping arrangement

101

Projection exposure system

102

lighting system

107

Reticle

108

Reticle holder

110

Projection optics

113

wafers

114

Wafer holder

116

DUV radiation

117

optical element

118

Versions

119

lens housing

M1-M6

Mirror

PD1, PD2

Lower/Upper limit damping range

PAm, PAo, PAu

Middle/upward/downward shifted operating point

Dmax

Damping range

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10 2016 202 127 A1 [0006, 0010]
• DE 10 2017 200 638 A1 [0012]
• DE 10 2008 009 600 A1 [0046, 0050]
• US 2006/0132747 A1 [0048]
• EP 1 614 008 B1 [0048]
• US 6,573,978 [0048]
• DE 10 2017 220 586 A1 [0053]
• US 2018/0074303 A1 [0067]

Claims (16)

Damper (30,40,50) for a semiconductor technology system (1,101) with at least one damping element (31,41,51) and two adjacent components (43.1,43.2,53.1,53.2), wherein the damping element (31,41,51) has a shape memory material with at least one main damping direction and wherein the damping element (31,41,51) is connected to the components (43.1,43.2,53.1,53.2) in such a way that tensile forces and compressive forces can be transmitted at least in the main damping direction, characterized in that the damper (30,40,50) has an elastic element (42,52.1,52.2) for generating a mechanical restoring force in the direction of the main damping direction. Damper (30,40,50) after Claim 1 , characterized in that the elastic element is designed as a solid spring (42,52.1,52.2). Damper (30,40,50) after Claim 1 or 2 , characterized in that the mechanical restoring force is designed such that the damping element (31,41,51) is located in the middle of its pseudoplastic region D _max without external force due to the restoring force. Damper (30, 40, 50) according to one of the preceding claims, characterized in that at least one of the components (43.1, 43.2, 53.1, 53.2) has at least one interface (46.1, 46.2, 56.1, 56.2) to at least one component and/or mass (57, 58) to be damped. Damper (30,40,50) according to one of the preceding claims, characterized in that the components are designed as a base (43.1,53.1) and cover (43.2,53.2) of the damper (30,40,50). Damper (30,40,50) according to one of the preceding claims, characterized in that the damping element (31,41,51) and the mechanical restoring force are designed such that the damper (30,40,50) has a predetermined (damped) natural frequency. Damper (30,40,50) according to one of the preceding claims, characterized in that the damping element (31,41,51) comprises a magnetic shape memory alloy. Damper (30,40,50) after Claim 7 , characterized in that the magnetic shape memory alloy comprises nickel, manganese and gallium. Damper (30,40,50) according to one of the Claims 1 until 6 , characterized in that the damping element (31,41,51) comprises a thermal shape memory alloy. Damper (30,40,50) after Claim 9 , characterized in that the thermal shape memory alloy is designed in such a way that it has pseudoelastic properties in the range of the temperature prevailing during operation of the damper (30, 40, 50). Damper (30,40,50) according to one of the Claims 9 or 10 , characterized in that the thermal shape memory alloy comprises nickel and titanium. Damper (30,40,50) according to one of the Claims 9 or 10 , characterized in that the thermal shape memory alloy comprises one of the following alloys: FeMnSi (iron-manganese-silicon), CuZn (copper-zinc), CuZnAl (copper-zinc-aluminium), CuAINi (copper-aluminium-nickel), FeNiAl (iron-nickel-aluminium), ZnAuCu (zinc-gold-copper) Damping arrangement (60) with a damper (30,40,50) according to one of the Claims 1 until 12 . Damping arrangement according to Claim 13 , characterized in that the damping arrangement (60) has a mass (57) and a component to be damped (58), wherein the damper (30, 40, 50) is arranged between the mass (57) and the component to be damped (58). Apparatus (1,101) for semiconductor lithography with a damper (30,40,50) according to one of the Claims 1 until 12 and/or a damping arrangement (60) according to one of the Claims 13 or 14 . Semiconductor lithography system according to Claim 15 , characterized in that the system is designed as a projection exposure system (1,101).