DE102022204015A1 - Actuator and deformation mirror - Google Patents

Abstract

The invention relates to an actuator (100) for adjusting an optical element (300) in a lithography device, having an electrostatic actuator (101) which has an electrode pair (102) made up of two electrodes (103, 104) which are at least temporarily spaced apart from one another. One of the electrodes (103, 104) is connected to a mechanical translator (105) which can be coupled to the optical element (300) and which comprises a lever (106) which is set up to be actuated by the electrostatic force of the electrodes (103) in such a way that that the force of the electrostatic actuator (101) is converted by means of the mechanical translator (105) into a mechanical actuation force that is greater than the electrostatic force for adjusting the optical element (300).The invention also relates to a deformation mirror.

Description

The invention relates to an actuator for adjusting an optical element in a lithography device, with an electrostatic actuator which has a pair of electrodes made up of two electrodes that are at least temporarily spaced apart from one another. The invention also relates to a deformation mirror.

Projection exposure systems are used to create the finest structures, especially on semiconductor components or other microstructured components. The functional principle of the systems mentioned is based on producing the finest structures down to the nanometer range by means of a generally reducing image of structures on a mask, a so-called reticle, on an element to be structured with photosensitive material, a so-called wafer. The minimum dimensions of the structures created depend directly on the wavelength of the light used. This is formed in lighting optics for optimal illumination of the reticle. Recently, light sources with an emission wavelength in the range of a few nanometers, for example between 1 nm and 120 nm, in particular in the range of 13.5 nm, have increasingly been used. The wavelength range described is also referred to as the EUV range.

In addition to systems operating in the EUV range, the microstructured components are also manufactured with the DUV systems established on the market with a wavelength between 100 nm and 300 nm, in particular 193 nm. With the requirement to be able to produce ever smaller structures, the requirements for optical correction in the systems have also increased further. With each new generation of projection exposure systems in the EUV range or DUV range, the throughput is increased to increase economic efficiency, which typically leads to greater thermal load and thus to increasing thermally caused imaging errors.

To correct the imaging errors, so-called manipulators can be assigned to the individual or all optical assemblies of the projection optics, which change the position and orientation of the optical elements or influence the imaging properties of the optical elements, in particular mirrors, by deforming the optical effective surface. An optical effective surface is understood to mean that surface of an optical element to which useful light is applied during operation of the associated system. Useful light refers to electromagnetic radiation that is used to image the structures.

In order to be able to adjust, i.e. manipulate, an optical element, actuators, in particular solid-state actuators, preferably piezostrictive or magnetostrictive actuators, are usually used. The term “adjustment” of the optical element includes both a translational and/or rotational movement or displacement of the (entire) optical element caused by the actuator as well as a deformation of the optical element, at least in some areas, caused by the actuator. In order to be able to control an actual adjustment of the optical element - sometimes also a deformation of the optical element - this must be recorded continuously. However, the use of sensors with sufficiently high measurement accuracy is not always possible, especially within lithography devices. For this reason, the known actuator systems are often operated in an open control chain (“feed-forward”). To achieve this, comprehensive system modeling/system calibration is required to achieve sufficient accuracy, which requires a deep system understanding of the influence of the individual actuators on the optical element. The measurement quality of the sensors used has a limiting effect on system calibration. However, in order to achieve sufficient measurement quality, a correspondingly high amount of effort must be made. However, the actuator behavior also depends on unmeasurable and unknown variables. This results in inaccuracies in the positioning and control of the actuator due to a failure to take the unknown variables into account or due to an incorrect consideration of the known and/or measurable variables. Solid-state actuators also have intrinsic effects such as hysteresis or creep, which are difficult to predict and also lead to errors in the positioning of the actuator.

One of the largest disturbance variables is the change in temperature. The temperature of an optical element within a projection exposure system can change in a range between 20°C and 60°C. Further problems in system modeling relate to intrinsic non-reproducibility of the actuators, such as creep, hysteresis, thermal hysteresis, variation in behavior and/or variation in thermal expansion coefficients.

The problem of the material-intrinsic non-reproducibility of the actuator (e.g. hysteresis and creep) and the strong temperature dependence can be circumvented by electrically rostatically acting actuators are used. The force effect of electrostatic actuators is based on the force of an electric field that acts between two adjacent electrodes. However, a problem with the adjustment - sometimes also the deformation - of optical elements using electrostatic actuators is the comparatively limited force effect compared to solid-state actuators and the limited adjustment path.

It is therefore the object of the present invention to provide an actuator and a deformation mirror which enable the optical element to be adjusted with high precision and high force.

The task relating to the actuator is solved by an actuator with the features of claim 1. The task relating to the deformation mirror is solved by a deformation mirror with the features of claim 12. Advantageous refinements with useful further developments are specified in the subclaims.

The actuator is characterized in particular in that one of the electrodes is connected to a mechanical translator which can be coupled to the optical element and which comprises a lever which is set up to be actuated by the electrostatic force of the electrodes in such a way that the force of the electrostatic actuator is converted by means of the mechanical translator into a mechanical actuation force for adjusting the optical element that is greater than the electrostatic force. The electrode spacing of the electrodes, which are at least temporarily spaced apart from one another, is generally smaller than 500 μm, preferably smaller than 100 μm, particularly preferably smaller than 30 μm, in particular between 0.1 μm and 10 μm.

Using the actuator according to the invention, it is possible to reduce non-reproducibility such as hysteresis or creep compared to solid-state actuators. Likewise, using the electrostatic actuator with the mechanical translator reduces the temperature dependence compared to using solid-state actuators. In contrast to the electrostatic actuators known from the prior art, the combination of the electrostatic actuator and the mechanical translator comprising the lever enables the force generated by the electrostatic actuator to actuate the lever, the lever - according to the lever law - controlling the electrostatic force converted into a larger mechanical actuation force for adjusting the optical element. In addition, the actuator according to the invention is free of transverse contraction or at least reduced in transverse contraction compared to a solid-state actuator.

The pairs of electrodes can be formed as capacitors, that is, as plates, or as interlocking electrode combs. The electrodes can be formed in one piece or in several parts. Flat electrodes are preferably provided, for example in the form of a plate, a film or a vapor-deposited layer. The thickness of an individual electrode can be, for example, 0.01 μm to 500 μm, preferably 0.01 μm to 100 μm, particularly preferably 0.01 μm to 10 μm. In this context, it is particularly preferred if one of the electrodes is applied to the mechanical translator at least in sections.

In one embodiment, only one mechanical translator is present, which is connected to one of the electrodes, for example via an additional connecting member.

The electrodes can each be formed in one piece or in several parts. The nominal electrode spacing of an electrode pair is generally smaller than 500 μm, preferably smaller than 100 μm, particularly preferably smaller than 30 μm, in particular between 0.1 μm and 10 μm. In one embodiment, the surface of the mechanical translator can form the electrode, so that a coating step can be dispensed with. The electrodes can be provided with coatings. This is particularly preferred to protect the electrodes from environmental influences such as oxygen, hydrogen, reactive gases and moisture. Furthermore, coatings can serve to provide electrical insulation, reduce leakage currents and limit the damage caused by possible electrical breakdowns. Coatings can also be particularly preferred from an actuator perspective. Particularly preferred coatings include SiO ₂ and Al ₂ O ₃

The thickness of a mechanical translator is usually less than 10mm, preferably less than 5mm, particularly preferably less than 2mm.

The actuator is preferably encapsulated, that is, it is surrounded by a housing in order to protect the actuator from contamination, in particular dust. Since there is a risk of short circuits caused by particles or the like due to the small distance between the electrode pairs, encapsulation is a particularly preferred embodiment. The encapsulation can be implemented with or without pressure compensation to the environment. Both represent preferred embodiments. The evacuated encapsulation of the actuator is particularly preferred.

The actuator is well suited to be used for nanopositioning (short travel, but comparatively precise positioning), particularly preferred for controlled systems and/or time ranges. The actuator can be advantageously combined with other actuators and actuator types, for example to increase the total travel distance.

To increase the mechanical actuation force for adjusting the optical element, it is preferred if a plurality of mechanical translators are present and if each mechanical translator is connected to at least one electrode. By arranging the plurality of mechanical translators parallel to one another, i.e. next to one another, an increase in force is achieved with the actuator according to the invention. Alternatively, it is also possible to arrange the mechanical translators in a row, which means that the majority of the mechanical translators are arranged stacked along the adjustment axis. This allows the total travel of the actuator to be increased.

In order to form an actuator that is as compact as possible, it is preferred if at least one of the mechanical translators, in particular all non-edge, i.e. centrally arranged, mechanical translators, are each mechanically connected to two electrodes or two electrodes are applied to it. It is preferred if the electrodes are arranged on opposite sides of the mechanical translator and are mechanically connected to it or applied to it.

To simplify production, it is advantageous if a first mechanical translator is formed as a hollow body in which a second mechanical translator is accommodated, that a gap is formed between the mechanical translators and that the mutually facing surfaces of the first mechanical translator and the second mechanical translator are each connected at least in sections to an electrode or the electrodes are applied to the surfaces. The hollow body can have any polygonal base area, in particular hexagonal or octagonal. However, the hollow body is particularly preferably formed as a hollow cylinder. The base area of the second mechanical translator is preferably adapted to the base area of the first mechanical translator. Naturally, the second mechanical translator can also be formed as a hollow body, in which a further mechanical translator formed as a hollow body or body is accommodated, with a gap being formed between the second translator and the further translator and the surfaces of the mechanical translators facing each other at least are connected in sections to an electrode. The mechanical translators therefore form shells, preferably cylindrical shells. This embodiment is characterized in particular by the fact that the actuator is rotationally symmetrical with respect to its adjustment axis. This allows the stiffness of the actuator to be approximately the same perpendicular to the adjustment axis. In order to reduce the high radial rigidity of the shells and to increase the adjustment path and increase the force effect that can be achieved in the actuator, it is preferred if the mechanical translators, in particular the hollow bodies/body/body shells, are designed to be slotted. Alternatively, the mechanical translators can also be arranged mirror-symmetrically with respect to the adjustment axis, for example as a body or hollow body with an octagonal or hexagonal base area.

The mechanical translator, i.e. in particular the lever, is particularly preferably formed as a plate. A plurality of such plates can be arranged next to one another and preferably mirror-symmetrically with respect to the adjustment axis.

In order to enable a two-axis actuation of the optical element, it is preferred if the mechanical translators and thus also the electrodes connected to them are arranged rotationally symmetrically or mirror-symmetrically with respect to an axis aligned perpendicular to an adjustment axis.

Alternatively, a two- or multi-axis actuation of the optical element can also be carried out by combining and correspondingly arranging several uniaxially adjustable actuators.

Within the scope of the invention, it is advantageous if the lever has a first articulated connection and a further articulated connection for coupling to the optical element and/or to a force-conducting component, for example a force-conducting intermediate component or a back plate. The lever is preferably connected directly or indirectly to the optical element, for example a mirror or a lens, in particular to its rear side, by means of the first articulated connections. The lever is preferably connected directly or indirectly to a back plate of the optical element by means of the further articulated connection. Alternatively, the lever can also be connected to a force-conducting intermediate component by means of the first articulated connection and to a further force-conducting intermediate component by means of the further articulated connection. The first articulated connection and the further one Articulated connection are preferably arranged at the end of the lever.

Alternatively, it is preferred if the lever is formed as a toggle lever which has two lever arms which are coupled to one another by means of a further articulated connection, and that the first of the lever arms has a first articulated connection and the second lever arm has a second articulated connection for coupling the optical element and/or with a force-conducting component. The lever arms can be of the same length or of different lengths. The distance between the first articulated connection and the further articulated connection preferably corresponds to the distance between the second articulated connection and the further articulated connection. The first articulated connection and the second articulated connection are preferably formed at the end or in a terminal area on the toggle lever, i.e. on the lever arms, and connect the toggle lever to the optical element at two different connection points, in particular to a rear side of the optical element and to one Backplate. Alternatively, the first and second articulated connections are also coupled to two force-conducting components, which in turn are connected to the back of the optical element. The articulated connections can also be formed at any point on the lever arms. In a further alternative embodiment, the actuator according to the invention has a mechanical translator designed as a toggle lever, which is connected to one electrode of the pair of electrodes, while the other of the electrodes is fixed, i.e. immovable, connected to, for example, a plate, the plate being firmly connected to the optical Element or a force-conducting component is connected. The electrode can also be designed monolithically with the plate.

Within the scope of the invention, it is also possible for the mechanical translator to comprise a combination of a lever and a toggle lever, or for one of the mechanical translators to be formed as a lever and another of the mechanical translators of the actuator as a toggle lever.

Furthermore, it is advantageous if the articulated connection is formed as a notch or as a solid joint, preferably as a leaf spring. The solid-state joints are preferably manufactured monolithically with the mechanical translator, i.e. manufactured by defined material removal.

The actuator can be set up for a monodirectional adjustment along or parallel to an adjustment axis or for a bidirectional adjustment along or parallel to an adjustment axis. A bidirectional actuation, i.e. an adjustment of the actuator in two opposite directions along or parallel to the adjustment axis, can be achieved in one embodiment by an electronic control in such a way that an electrical voltage is applied to the electrostatic actuator in a mechanical zero position, so that an adjustment of the optical element in a first direction parallel to the adjustment axis by increasing the voltage and in a second direction opposite to the first direction parallel to the adjustment axis by reducing the voltage. The disadvantage of using such an electrical bias voltage is that the actuator cannot maintain the mechanical zero position itself without applying the voltage.

It is therefore preferred if two of the mechanical translators form a first sub-actuator which is set up to adjust the optical element in a first direction parallel to an adjustment axis and/or that two of the mechanical translators form a second sub-actuator which is set up to adjust the optical element to move parallel to the adjustment axis in a second direction opposite to the first direction.

If the mechanical translator comprises a toggle lever with a first lever arm, which is connected to a second lever arm by means of an articulated connection, the lever arms each having further articulated connections, then in a mechanical zero position the lever arms are aligned in an angular position such that the distance between the first articulated connections (and also between the second articulated connections) of the two mechanical translators is greater than the distance between the further articulated connections of the first subactuator. An electrostatic attraction of the two electrodes consequently leads to a reduction in the distance between the further articulated connections, which creates a moment which leads to an adjustment of the subactuator in a first direction parallel to the adjustment axis. In the second subactuators, the lever arms are arranged in an angular position such that the distance between the first articulated connections (and also between the second articulated connections) of the two mechanical translators is smaller than the distance between the further articulated connections. An electrostatic attraction of the two electrodes consequently also leads to a reduction in the distance between the further articulated connections, which creates a moment which leads to an adjustment of the second sub-actuator in a second direction opposite to the first direction, parallel to the adjustment axis leads. This applies analogously in the case that the mechanical translator includes a lever. Conversely, an electrostatic repulsion between the electrodes would lead to an increase in the distance between the further articulated connections such that the first sub-actuator is adjusted in the second direction parallel to the adjustment axis, while the second sub-actuator is adjusted in the first direction parallel to the adjustment axis.

In order to form a compact actuator, it is preferred if first sub-actuators are arranged adjacent to second sub-actuators. However, the first subactuators and the second subactuators can also be arranged anywhere within the actuator in any number and order. Furthermore, it is preferred if two (adjacent) subactuators share a mechanical translator, so that two subactuators are preferably formed not from a total of four but only from three mechanical translators.

In other words, the second mechanical translator of one of the subactuators forms the first mechanical translator of the other (adjacent) subactuator.

Depending on the combination of the features described above, the actuator can therefore be set up to be actuated in a single-axis monodirectional, single-axis bidirectional, two-axis monodirectional, two-axis bidirectional, multi-axis monodirectional or multi-axis bidirectional manner.

The deformation mirror according to the invention for a lithography arrangement, with a mirror body which has a reflective surface and a play back opposite the reflective surface, comprises at least one actuator described above, the at least one mechanical translator of which is directly or indirectly connected to the back of the mirror or is inserted into the back of the mirror. This enables the deformation of the mirror surface by the actuator to be more temperature-independent and deterministic. By replacing the solid-state actuators with the actuators according to the invention and due to the combination of an electrostatic actuator and a mechanical translator comprising a lever, the electrostatic force of the electrostatic actuator is increased, so that a greater deformation effect is possible. The embodiments and advantages described with regard to the actuator can also be applied to the deformation mirror.

Furthermore, it is preferred if a plurality of actuators are connected directly or indirectly to the back of the mirror by means of the mechanical translator or are inserted into the back of the mirror. In particular, the actuators can be arranged at a regular distance, in an actuator network, in particular in an array or in a matrix.

If the actuators are attached to the back of the mirror in such a way that actuation acts parallel to the surface, it is advantageous if the majority of actuators form an actuator surface composite. Adjacent actuators are therefore directly connected to one another. The actuators can be made monolithically from a plate and rigidly connected to the adjacent surfaces.

Within the scope of the invention it is provided that an impedance meter is assigned to the at least one actuator. This enables precise position determination and the precise acquisition of data regarding deflection (electrode distance), stiffness and force. This means that changing stiffness within the actuator network can be compensated for.

If the deformation mirror is connected to a plurality of actuators that form an actuator composite, it is preferred if the actuators in the actuator composite are arranged relative to one another in such a way that the rigidity along a first axis of the actuator composite differs from the rigidity along an axis deviating from the first axis extending second axis of the actuator composite differs by less than 60%, preferably by less than 50%, most preferably by less than 30% and most preferably by less than 10%. The first axis is preferably aligned orthogonally to the second axis. This arrangement is particularly advantageous when actuators are used that are not rotationally symmetrical with respect to the adjustment axis or with respect to an axis that runs perpendicular to the adjustment axis. These actuators have anisotropic stiffness behavior. The actuator consequently has a first stiffness axis, which has a stiffness that deviates from a second stiffness axis. Adjacent actuators are then preferably arranged relative to one another in such a way that their first stiffness axes form an angle between 50° and 110°, preferably between 60° and 100° and particularly preferably 60° or 90°. The first stiffness axis is preferably aligned orthogonally to the second stiffness axis.

Furthermore, with regard to the improved determination of the actuator, it is advantageous if the actuator and in particular the at least one mechanical translator are made of the same material. is made of the same material as the mirror body, i.e. preferably made of optical glass in order to minimize thermal stresses. Furthermore, it is preferred if the material has a low coefficient of thermal expansion, which is generally less than 10*10 ^-6 K ^-1 , preferably less than 5*10 ^-6 K ^-1 , particularly preferably 2*10 ^-6 K ^{- 1} , in particular the thermal expansion coefficient can be 0 K ^-1 to 1*10 ^-7 K ^-1 . Materials that have a zero crossing temperature and are operated at or close to this are particularly advantageous.

The actuator, in particular the mechanical translators, preferably has the same thermal expansion transverse to the direction of action as the optical element or the component to which it is joined. The actuator particularly preferably has thermal expansion, so that the temperature-related deformation and/or displacement of a defined interface surface is minimized. In the case of mirrors, this is particularly the optical surface. In the case of nanopositioning systems, this is particularly the point of contact with the component to be positioned. The actuator preferably has a thermal expansion in the effective direction of zero or close to zero at operating temperature.

The actuator, in particular the mechanical translators, preferably has a thermal expansion transverse to the effective direction of zero or close to zero at operating temperature. The material of the actuator, in particular the mechanical translator, can be selected such that effects of thermal expansion of the electrodes, electrode coatings or similar are compensated for in the effective direction.
The material of the actuator, in particular the mechanical translator, can be chosen such that effects of thermal expansion of the electrodes, electrode coatings on the position and deformation of the interface (mirror surface or contact with the body to be positioned) are compensated.

In a further particularly preferred embodiment variant, the actuators, in particular the mechanical translators, can be made of electrically conductive materials. The use of metals is particularly preferred because of their good ductility properties as solid-state joints and their good manufacturability by eroding. Materials such as silicon are also of interest because of their easy manufacturability. The electrodes can be electrically isolated by the mechanical translator. SiO ₂ coatings or Al ₂ O ₃ coatings, along with other inorganic ones, are particularly suitable for this. In a further particularly preferred embodiment, the surface of the electrically conductive mechanical translator itself can form the electrode, so that a coating process step can be saved.

• 1a eine schematische Darstellung einer für den Betrieb in EUV ausgelegten mikrolithographischen Projektionsbelichtungsanlage,
• 1 b eine schematische Darstellung einer für den Betrieb im DUV ausgelegten mikrolithographischen Projektionsbelichtungsanlage,
• 2 ein erstes Ausführungsbeispiel eines einachsig wirkenden monodirektional aktuierbaren Aktuators mit einem Kniehebel,
• 3 ein zweites Ausführungsbeispiel eines monoaxial wirkenden bidirektional aktuierbaren Aktuators mit mehreren Kniehebeln,
• 4 ein drittes Ausführungsbeispiel eines monoaxial wirkenden bidirektional aktuierbaren Aktuators mit Blattfedern,
• 5 der Schnitt IV-IV aus 4 mit als Platten gebildeten mechanischen Übersetzern
• 6 ein viertes Ausführungsbeispiel mit als Zylinderschalen gebildeten mechanischen Übersetzern,
• 7 ein fünftes Ausführungsbeispiel mit als geschlitzte Zylinderschalen gebildeten mechanischen Übersetzern,
• 8 ein sechstes Ausführungsbeispiel eines Aktuators mit hexagonaler Grundfläche,
• 9 ein siebtes Ausführungsbeispiel eines bidirektional aktuierbaren, einachsig wirkenden Aktuators mit tangential wirkenden elektrostatischen Kräften,
• 10 ein Schnitt VIII-VIII aus 9,
• 11 ein achtes Ausführungsbeispiel eines zweiachsig wirkenden bidirektional verstellbaren Aktuators,
• 12 der Schnitt X-X aus 11,
• 13 der Schnitt XI-XI aus 11,
• 14 ein flächennormal aktuierbarer Deformationsspiegel,
• 15 eine schematische Anordnung eines Aktuatorverbunds aus einer Mehrzahl von Aktuatoren,
• 16 ein flächenparallel aktuierbarer Deformationsspiegel,
• 17 das Detail A aus 16,
• 18 ein Aktuatorflächenverbund, und
• 19 eine schematische Darstellung der elektrischen Ansteuerung eines erfindungsgemäßen Aktuators.

Further features, properties and advantages of the present invention are described in more detail below using embodiment variants with reference to the attached figures. All features described so far and below are advantageous both individually and in any combination with one another. The embodiment variants described below merely represent examples, which, however, do not limit the subject matter of the invention. Show:

• 1a a schematic representation of a microlithographic projection exposure system designed for operation in EUV,
• 1 b a schematic representation of a microlithographic projection exposure system designed for operation in the DUV,
• 2 a first exemplary embodiment of a uniaxially acting, monodirectionally actuated actuator with a toggle lever,
• 3 a second exemplary embodiment of a monoaxially acting, bidirectionally actuated actuator with several toggle levers,
• 4 a third exemplary embodiment of a monoaxially acting, bidirectionally actuated actuator with leaf springs,
• 5 section IV-IV 4 with mechanical translators formed as plates
• 6 a fourth exemplary embodiment with mechanical translators formed as cylindrical shells,
• 7 a fifth exemplary embodiment with mechanical translators formed as slotted cylindrical shells,
• 8th a sixth embodiment of an actuator with a hexagonal base,
• 9 a seventh embodiment of a bidirectionally actuable, uniaxially acting actuator with tangentially acting electrostatic forces,
• 10 a section VIII-VIII 9 ,
• 11 an eighth embodiment of a two-axis, bidirectionally adjustable actuator,
• 12 the cut XX 11 ,
• 13 the section XI-XI 11 ,
• 14 a deformation mirror that can be actuated normally,
• 15 a schematic arrangement of an actuator assembly consisting of a plurality of actuators,
• 16 a deformation mirror that can be actuated parallel to the surface,
• 17 the detail A 16 ,
• 18 an actuator surface composite, and
• 19 a schematic representation of the electrical control of an actuator according to the invention.

1a shows a schematic representation of an exemplary projection exposure system 600 designed for operation in EUV, in which the present invention can be implemented, that is, in which the actuator 100 according to the invention can be used. However, the invention can also be used in other nanopositioning systems.

According to 1a an illumination device in a projection exposure system 600 designed for EUV has a field facet mirror 603 and a pupil facet mirror 604. The light from a light source unit, which includes a plasma light source 601 and a collector mirror 602, is directed onto the field facet mirror 603. A first telescope mirror 605 and a second telescope mirror 606 are arranged in the light path after the pupil facet mirror 604. A deflecting mirror 607 is arranged next in the light path and directs the radiation hitting it onto an object field in the object plane of a projection lens comprising six mirrors 651-656. At the location of the object field, a reflective structure-bearing mask 621 is arranged on a mask table 620, which is imaged with the help of the projection lens into an image plane in which a substrate 661 coated with a light-sensitive layer (photoresist) is located on a wafer table 660.

The invention can also be used in a DUV system, as in 1b shown. A DUV system is basically like the EUV system described above 1a constructed, whereby mirrors and lenses can be used as optical elements in a DUV system and the light source of a DUV system emits useful radiation in a wavelength range of 100 nm to 300 nm.

In the 1b DUV lithography system 700 shown has a DUV light source 701. An ArF excimer laser, for example, can be provided as the DUV light source 701, which emits radiation 702 in the DUV range at, for example, 193 nm. A beam shaping and illumination system 703 directs the DUV radiation 702 onto a photomask 704. The photomask 704 is designed as a transmissive optical element and can be arranged outside the systems 703. The photomask 704 has a structure which is imaged in a reduced size onto a wafer 706 or the like by means of the projection system 705. The projection system 705 has several lenses 707 and/or mirrors 708 for imaging the photomask 704 onto the wafer 706. Individual lenses 707 and/or mirrors 708 of the projection system 705 can be arranged symmetrically to the optical axis 709 of the projection system 705. It should be noted that the number of lenses 707 and mirrors 708 of the DUV lithography system 700 is not limited to the number shown. More or fewer lenses 707 and/or mirrors 708 can also be provided. In particular, the beam shaping and illumination system 703 of the DUV lithography system 700 has a plurality of lenses 707 and/or mirrors 708. Furthermore, the mirrors are usually curved on their front to shape the beam. An air gap 710 between the last lens 707 and the wafer 706 can be replaced by a liquid medium which has a refractive index > 1. The liquid medium can be, for example, highly pure water. Such a setup is also known as immersion lithography and has increased photolithographic resolution. The actuators according to the invention can be used to adjust the lenses 707 and/or mirrors 708 and/or to deform them in the DUV lithography system 700, in particular in its projection system 705.

2 shows an actuator 100 for adjusting an optical element 300 in a lithography device, with an electrostatic actuator 101 which has an electrode pair 102 made up of two electrodes 103, 104 that are at least temporarily spaced apart from one another. The electrodes 103, 104 are connected to a mechanical translator 105 that can be coupled to the optical element 300. In the present case, the electrodes are applied to the mutually facing surfaces of the mechanical translator 105, with the first electrode 103 and the second electrode 104 each being formed in several parts. However, the electrodes can also be formed in one piece and only partially connected to the mechanical translator 105 or applied/vapor-deposited onto it. The mechanical translator 105 includes a lever 106, in this case a toggle lever 111, which is set up to be actuated by the electrostatic force of the electrodes 103, 104 in such a way that the force of the electrostatic actuator 101 by means of the mechanical translator 105 is converted into a mechanical force that is greater than the electrostatic force Actuating force for adjusting the optical element 300 is converted.

In the present case, the lever 106 of the mechanical translator 105 is formed as a toggle lever 111, which has lever arms 112 which are coupled to one another by means of a further articulated connection 110. The first of the lever arms 112a has a first articulated connection 109a at the end and the second lever arm 112b has a second articulated connection 109b at the end. In the present case, the first lever arm 112a is connected to the optical element 300 by means of the first articulated connection 109a and the second lever arm 112b is connected to a force-conducting component 304, for example a back plate 305 of the optical element 300, by means of the second articulated connection 109b. The articulated connections 109, 110 are formed as notches or preferably as solid-state joints, in particular as leaf springs. By applying an electrical voltage between the electrodes 103, 104, which leads to an electrostatic attraction of the two electrodes 103, 104, the distance between the two further articulated connections 110 is reduced, which creates a moment that leads to an adjustment of the optical element 300 along a first direction 115 parallel to the adjustment axis 108. The first direction 115 is indicated by the white arrows in the 2 shown.

3 shows a uniaxially acting, bidirectionally adjustable actuator 100, with two of the mechanical translators 105 forming a first sub-actuator 113, which is set up to adjust the optical element 300 in the first direction 115 (negative z-direction) parallel to the adjustment axis 108. Furthermore, two more of the mechanical translators 105 form a second sub-actuator 114, which is set up to move the optical element parallel to the adjustment axis 108 in a second direction 116 (positive z-direction) that is opposite to the first direction 115. The first sub-actuators 113 are arranged adjacent to the second sub-actuators 114, wherein the sub-actuators 113, 114 can be arranged in any order. In order to enable the actuator 100 to be as compact as possible, the second mechanical translator 105b of the first sub-actuator 113 forms the first mechanical translator 105a of the second sub-actuator 114.

The two lever arms 112 of the toggle lever 111 of the sub-actuator 113 are aligned in a mechanical zero position in an angular position such that the distance between the first articulated connections 109a (and also between the second articulated connections 109b) of the two mechanical translators 105a, 105b is larger, as the distance between the further articulated connections 110 of the first sub-actuator 113. An electrostatic attraction of the two electrodes 103, 104 consequently leads to a reduction in the distance between the further articulated connections 110, which creates a moment which leads to an adjustment of the first sub-actuator 113 into one first direction 115 leads parallel to the adjustment axis 108. In the second sub-actuator 114, the lever arms 112 are arranged in an angular position such that the distance between the first articulated connections 109a (and also between the second articulated connections 109b) of the two mechanical translators 105b, 105a is smaller than the distance between the further articulated ones Connections 110. An electrostatic attraction of the two electrodes 103, 104 consequently also leads to a reduction in the distance between the further articulated connections 110, which creates a moment which leads to an adjustment of the second sub-actuator 114 in a second direction 116 opposite to the first direction 115, parallel to the second direction 116 Adjustment axis 108 leads. This applies analogously in the case that the mechanical translator 105a includes a lever - that is, only one lever arm 112. Conversely, an electrostatic repulsion between the electrodes 103, 104 would lead to an increase in the distance between the further articulated connections 110 such that the first sub-actuator 113 is adjusted in the second direction 116 parallel to the adjustment axis 108, while the second sub-actuator 114 is adjusted in the first direction 115 adjusted parallel to the adjustment axis 108.

The actuator 100 according to 3 comprises a plurality of mechanical translators 105, which are joined together or on a base plate, for example on a back plate 305, or on a separate base plate, in particular at a distance from one another. The joining can be done using bonding, direct bonding, reactive bonding, frit bonding or adhesive bonding using a joining material. The joining material can also be electrically conductive. Likewise, the base plate/back plate can also be made of an electrically conductive material. If the joint has only a comparatively small thickness, individual or all mechanical translators 105 can have at least one projection, not shown, on one side or on the opposite sides. By means of the projections, in the assembled state of the mechanical translators 105, sufficiently large distances between the electrodes 102, 103 are formed between adjacent mechanical translators 105.

4 shows one to 3 analog acting actuator 100, wherein the mechanical translators 105 are arranged mirror-symmetrically or rotationally symmetrically with respect to the adjustment axis 108. The articulated connections 109, 110 can be formed as notches, solid-state joints, in particular leaf springs. The in 5 Section IV-IV shown 4 shows an execution form, in which the mechanical translators 105 of the actuator 100 are formed as plates on which the electrodes 103,104 are applied or which are connected to the electrodes 103,104.

The in 6 Actuator 100 shown in a section shows an embodiment of the actuator 100, in which the mechanical translators 105 are formed as shells, in particular as cylindrical shells, which are housed in one another and arranged nested. The electrodes 103, 104 are connected to or applied to the mutually facing surfaces of adjacent shells/mechanical translators 105a, 105b. The mechanical translators 105 are arranged rotationally symmetrically with respect to the adjustment axis 108.

The exemplary embodiments of the 6 and 7 show actuators 100 with mechanical translators 105 designed as cylindrical shells. In contrast, this shows 8th that other polygonal body shapes for the actuator 100, for example a hollow body with a hexagonal or octagonal base area, i.e. a base area that is mirror-symmetrical to the adjustment axis, are also possible.

In particular, an embodiment that is rotationally symmetrical to the adjustment axis 108 is preferred in order to enable homogeneous rigidity perpendicular to the adjustment axis 108. In order to increase the possible total travel and to reduce the rigidity, it is preferred if the actuator 100, in particular the mechanical translator 105, is slotted, i.e. segmented, with one or more slots 120, as in the 7 and 8th shown.

The embodiment according to the 9 and 10 show a bidirectionally actuable, uniaxially acting actuator 100 with tangentially acting electrostatic forces. The application of a potential difference to the electrode pairs 102 of the actuator 100 leads to a reduction in the size of the slot 120, which leads to an adjustment of the optical element 300. The first mechanical translators 105a can be designed in such a way that a reduction in the size of the slot 120 caused by the electrostatic attraction of the electrodes 103, 104 enables the optical element 300 to be adjusted in a first direction 115 (negative z-direction), while the second mechanical translators 105b are designed in such a way that a reduction in the size of the slot 120 caused by the electrostatic attraction of the electrodes 103, 104 enables the optical element 300 to be adjusted in the second direction 116 (positive z-direction). The first mechanical translators 105a differ from the second mechanical translators 105b in the arrangement and direction of action of their articulated connections 109,110.

The exemplary embodiment according to the 11 until 13 shows a two-axis, bidirectionally actuated actuator 100, wherein the plurality of mechanical translators 105 are arranged rotationally symmetrically with respect to an axis aligned perpendicular to the adjustment axes - in this case the x and y axes. The bidirectional adjustment is analogous to that in 3 described embodiment, whereby the rotationally symmetrical alignment of the mechanical translator 105 enables adjustment along the x-axis and along the y-axis. The toggle lever 111 has a first articulated connection 109a and a second articulated connection 109b, as well as two further articulated connections 110, i.e. a total of four articulated connections 109, 110, in order to enable a rotationally symmetrical design with respect to the axis aligned perpendicular to the adjustment axes. Alternatively, it would also be possible to form just one further articulated connection 110 in the middle between the two articulated connections 109. Alternatively and not shown, the plurality of mechanical translators 105 can also be arranged mirror-symmetrically - for example with an octagonal or hexagonal base - with respect to the axis aligned perpendicular to the adjustment axes 108. Analogous to the single-axis actuators 100, the two-axis actuators 100 can also be designed to be slotted.

14 shows a first exemplary embodiment of a deformation mirror 300 for a lithography device with a surface-normal operating principle of the actuators 100. The deformation mirror 300 has a mirror body 301 made of optical glass, which has a reflecting surface 302 and a play back 303 opposite the reflecting surface 302. A plurality of the previously described uniaxially acting, monodirectionally or bidirectionally actuated actuators 100 are arranged directly or indirectly on the rear side of the mirror 303 and are connected to it. The mechanical translators 105 of the actuators 100, not shown in more detail, are directly or indirectly connected at one end to the back of the mirror 303 and at the other end to a back plate 305. By adjusting at least one of the actuators 100 parallel to the adjustment axis 108, a bending moment is introduced into the mirror body 301, whereby the mirror 300 is deformed at least in sections. The deformation mirror 300 can be provided with a frame (not shown in detail) (“forceframe”) or frameless, ie “forceframe-free”. The actuators 100 are preferably regular Distance from each other and arranged orthogonally to the back of the mirror 303.

Due to their structure, the actuators 100 for the deformation mirror 300 can, in particular if they are not rotationally symmetrical with respect to the adjustment axis, such as the embodiment according to 5 , have anisotropic stiffness behavior. The actuators 100 then have a first stiffness axis 122, which has a different stiffness than a second stiffness axis 123. A plurality of actuators form an actuator network 121, as in 15 shown, it is advantageous if the actuators 100 in the actuator assembly 121 are arranged relative to one another in such a way that the rigidity along a first axis 118 of the actuator assembly differs from the rigidity along a second axis 119 of the actuator assembly 121 which runs deviating from the first axis 118 less than 60%, preferably less than 50%, most preferably less than 30% and most preferably less than 10%. The first axis 118 is preferably aligned orthogonally to the second axis 119. Preferably, the first stiffness axes 122 of adjacent actuators 100 form an angle between 50° and 110°, preferably between 60° and 100° and particularly preferably 60° or 90°. This enables an at least approximately isotropic stiffness behavior of the actuator composite 121. The first stiffness axis 122 is preferably orthogonal to the second stiffness axis 123.

The exemplary embodiment according to the 16 until 18 shows a deformation mirror 300 for a lithography arrangement with a surface-parallel operating principle of the actuators 100. This has the advantage that the deformation mirror 300 is formed without a backplate. The mirror back 303 is preferably connected to a plurality of the previously described biaxially acting, monodirectionally or bidirectionally adjustable actuators 100 according to the invention. As shown in the detailed view A of the 17 As can be seen, the mechanical translators 105 of the actuator 100 are attached to the back of the mirror 303 by means of a force-transmitting intermediate element 304. Alternatively, the at least one actuator 100 can also be accommodated in a pocket (not shown) inserted into the mirror body 301 on the mirror back 303. Like from the 17 and the 18 As becomes clear, a plurality of actuators 100 form an actuator surface composite 117. Adjacent actuators 100 thus directly adjoin one another. The actuators 100 can be manufactured monolithically from a plate and rigidly connected to the surfaces adjacent to one another.

An electrostatic force acting through the electrostatic actuator of the actuator 100 drives the lever 106/toggle lever 111 (not shown) of the mechanical translator 105, which results in a compression or expansion of the actuator 100, which introduces a bending moment into the mirror body 301, whereby the mirror body 301 and thus the reflective surface 302 is deformed at least in sections.

The surface-parallel adjustable deformation mirror 300 can also alternatively be operated with a plurality of previously described uniaxially acting actuators 100, with a first group of the uniaxially acting actuators 100 being adjustable parallel to a first axis (x-axis) and a second group of the uniaxially acting actuators 100 is adjustable parallel to a second axis (y-axis) which is orthogonal to the first axis. The groups can be stacked in layers, for example alternately. Here too, adjacent actuators 100 can be arranged relative to one another in such a way that an at least approximately isotropic stiffness behavior of the actuator surface composite 117 is achieved. The actuation can also take place with only one of the groups and the actuator 100 can also only have one group. Furthermore, monodirectionally adjustable actuators 100 can also be used for the surface-parallel deformation mirror 300, although bidirectional actuation is still possible using a bias voltage.

Based on 19 The various connection options for the actuator 100 can be illustrated. The various mechanical translators 105 are marked with letters from A to H. The first electrodes 103 are in the 19 always the electrodes 103 arranged on the right side of the mechanical translator 105 and the second electrodes 104 are in the 19 always the electrodes 104 arranged on the left side of the mechanical translator.

On the one hand, it is possible to control all electrodes 103, 104 separately or to control all electrodes 103, 104 of an electrode pair 102 of a mechanical translator 105 together. The latter offers the advantage that only one contact is necessary per mechanical translator 105. The electrodes 103,104 of different mechanical translators 105 are electrically insulated from each other. For example, if the electrodes 103,104 of the mechanical translators A and B, C and D, and E and F are at the same potential, there is no electrostatic force effect between the respective electrodes 103,104 of the mechanical translators A and B, C and D and E and F .Since the electrodes 103, 104 of mechanical translators B and C, D and E, as well as F and G are at different potentials, the resulting electrostatic force enables the lever 111, 112 to be actuated and thus an adjustment in the positive z direction. By switching over, an adjustment in the negative z direction can be made possible.

In order to be able to dispense with reconnection, it is advantageous if one of the electrodes 103, 104 of the electrode pair 102 is used as a control electrode and the other of the electrodes 103, 104 of the electrode pair 102 is at a predetermined potential (for example designed as common ground). Those of the control electrodes 102, 103 that effect an adjustment in a first direction (negative z-direction) parallel to the adjustment axis can be contacted together (and thus controlled). These can be, for example, the first electrodes 103 of the mechanical translator B, D, F and H. Those of the electrodes 102, 103 that effect an adjustment in a second direction (positive z-direction) parallel to the adjustment axis can also be contacted together (and thus controlled). These can be, for example, the second electrodes 104 of the mechanical translators C, E and G. Likewise, the electrodes 103, 104 of the common ground (i.e. the first electrodes 103 of the mechanical translators A, C, E, G, as well as the second electrodes 104 of the mechanical translators B, D and F) can also be contacted together. Of course, separate contacting of all electrodes is also possible. By supplying the respective control electrodes with a control voltage, a bidirectionally actuable actuator 100 can consequently be provided.

Alternatively, it is also possible to realize actuation in the first and second directions parallel to the adjustment axis using the same control line. A first electrode 103 of a first electrode pair 124 (e.g. the first electrode of the mechanical translator A) is supplied with, for example, a positive constant voltage and a second electrode 104 of a second electrode pair 125 (e.g. the second electrode of the mechanical translator C) is supplied with a negative constant voltage. Of course, the first electrode 103 of the first pair of electrodes 124 can also be supplied with a negative constant voltage and the second electrode 104 of the second pair of electrodes 125 can be supplied with a positive constant voltage, the magnitude of the constant voltages preferably matching one another. The second electrode 104 of the first pair of electrodes 124 (second electrode 104 on mechanical translator B) and the first electrode 103 of the second pair of electrodes 125 (first electrode 103 on mechanical translator B) are electrically connected and are controlled together. The voltage range is preferably between that of the constant voltages. If there is a voltage between the second electrode 104 of the first pair of electrodes 124 (second electrode 104 of the mechanical translator B) and the first electrode 103 of the second pair of electrodes 125 (first electrode 103 of the mechanical translator B) that lies exactly between the individual constant voltages, then Assuming the same electrode spacing, there is no adjustment, since the potential differences between the first pair of electrodes 124 (first electrode 103 of the mechanical translator A and second electrode 104 of the mechanical translator B), and the second pair of electrodes 125 (second electrode 104 of the mechanical translator B and first electrode 103 of the mechanical translator C) are the same. The between the second electrode 104 of the first pair of electrodes 124 (first electrode 103 of the mechanical translator A and second electrode 104 of the mechanical translator B) and the first electrode 103 of the second pair of electrodes 125 (second electrode 104 of the mechanical translator B and first electrode 103 of the mechanical The control voltage applied to the translator C) can be selected in such a way that there are different potential differences between the electrode pairs 124, 135. Depending on the choice of voltage, this enables the optical element 300 to be adjusted in a positive z-direction or in a negative z-direction.

The connection approaches described above can also be transferred to actuators 100 that act on two axes.

REFERENCE SYMBOL LIST

100

actuator

101

electrostatic actuator

102

pair of electrodes

103

first electrode (of the electrode pair)

104

second electrode (of the electrode pair)

105

mechanical translator

105a

first mechanical translator

105b

second mechanical translator

106

lever

107

gap

108

Adjustment axis

109

fixed camp

110

Floating bearing

111

Knee lever

112

Lever arm

112a

first lever arm

112b

second lever arm

113

first subactuator

114

second subactuator

115

first direction

116

second direction

117

Actuator surface composite

118

first axis

119

second axis

120

slot

121

Actuator composite

122

first axis of stiffness

123

second axis of stiffness

124

first pair of electrodes

125

second pair of electrodes

300

optical element, deformation mirror

301

Mirror body

302

reflective surface

303

Mirror back

304

force-conducting component

305

Backplate

600

Projection exposure system

601

Plasma light source

602

Collector mirror

603

Field facet mirror

604

Pupillary facet mirror

605

first telescope mirror

606

second telescope mirror

607

Deflecting mirror

620

Mask table

621

mask

651

Mirror (projection lens)

652

Mirror (projection lens)

653

Mirror (projection lens)

654

Mirror (projection lens)

655

Mirror (projection lens)

656

Mirror (projection lens)

660

Wafer table

661

coated substrate

700

DUV lithography system

701

DUV light source

702

DUV radiation/beam path

703

Beam Forming and Illumination System (DUV)

704

Photomask

705

Projection system

706

wafers

707

lens

708

Mirror

709

optical axis

Claims (19)

Actuator (100) for adjusting an optical element (300) in a lithography device, with an electrostatic actuator (101) which has an electrode pair (102) made up of two electrodes (103,104) that are at least temporarily spaced apart, characterized in that one of the electrodes (103,104 ) is connected to a mechanical translator (105) which can be coupled to the optical element (300), which comprises a lever (106) which is set up to be actuated by the electrostatic force of the electrodes (103) in such a way that the force of the electrostatic Actuator (101) is converted by means of the mechanical translator (105) into a mechanical actuation force that is larger than the electrostatic force for adjusting the optical element (300). Actuator (100) after Claim 1 , characterized in that at least one of the electrodes (103,104) is applied at least in sections to the mechanical translator (105). Actuator (100) after Claim 1 or 2 , characterized in that a plurality of mechanical translators (105) are present, and that each of the mechanical translators (105) is connected to at least one electrode (103,104). Actuator (100) after Claim 3 , characterized in that at least one of the mechanical translators (105) is connected to two electrodes (103,104), and that the electrodes (103,104) are arranged on the opposite sides of the mechanical translator (105). Actuator (100) after Claim 3 or 4 that a first mechanical translator (105a) is formed as a hollow body in which a second mechanical translator (105b) is accommodated, that between the mechanical translators (105a, 105b) a gap (107) is formed, and that the mutually facing surfaces of the first mechanical translator (105a) and the second mechanical translator (105b) are each connected at least in sections to an electrode (103,104). Actuator (100) according to one of the Claims 1 until 5 , characterized in that the mechanical translator (105) is formed as a plate. Actuator (100) according to one of the Claims 3 until 5 , characterized in that the mechanical translators (105) are arranged rotationally symmetrically or mirror-symmetrically with respect to the adjustment axis (108). Actuator (100) according to one of the Claims 3 until 5 , characterized in that the mechanical translators (105) are arranged rotationally symmetrically or mirror-symmetrically with respect to an axis aligned perpendicular to an adjustment axis (108). Actuator (100) according to one of the Claims 1 until 8th , characterized in that the lever (106) has a first articulated connection (109) and a further articulated connection (110) for coupling to the optical element (300) and / or a force-conducting component (304). Actuator (100) according to one of the Claims 1 until 8th , characterized in that the lever (106) is formed as a toggle lever (111) which has two lever arms (112, 112a, 112b) which are coupled by means of a further articulated connection (110), and that the first lever arm (112a ) a first articulated connection (109a) and the second lever arm (112b) has a second articulated connection (109b) for coupling to the optical element (300) and / or to a force-conducting component (304). Actuator (100) after Claim 9 or 10 , characterized in that the articulated connection (109, 110) is formed as a notch or as a solid joint, preferably as a leaf spring. Actuator (100) according to one of the Claims 1 until 10 , characterized in that two of the mechanical translators (105) form a first sub-actuator (113), which is set up to adjust the optical element (300) in a first direction (115) parallel to an adjustment axis (108) and / or that two of the mechanical translators (105) form a second sub-actuator (114), which is set up to adjust the optical element (300) in a second direction (116), which is opposite to the first direction (115), parallel to the adjustment axis (108). Actuator (100) after Claim 12 , characterized in that adjacently arranged subactuators (113,114) share a mechanical translator. Deformation mirror (300) for a lithography arrangement, with a mirror body (301) which has a reflecting surface (302) and a mirror back (303) opposite the reflecting surface (302), and with at least one actuator (100) according to one of Claims 1 until 13 , whose at least one mechanical translator (105) is connected directly or indirectly to the back of the mirror (303) or is inserted into the back of the mirror (303). Deformation mirror (300). Claim 14 , characterized in that a plurality of actuators (100) are connected directly or indirectly to the back of the mirror (303) by means of the mechanical translator (105) or are introduced into the back of the mirror (303). Deformation mirror (300). Claim 15 , characterized in that the plurality of actuators (100) are arranged to form an actuator surface composite (117). Deformation mirror (300). Claim 15 , characterized in that a plurality of actuators (100) are arranged to form an actuator assembly (121), and that the actuators (100) in the actuator assembly (121) are arranged relative to one another in such a way that the rigidity is along a first axis (118) of the Actuator composite depends on the stiffness along a second axis (119) of the actuator composite (121) which deviates from the first axis (118) by less than 60%, preferably by less than 50% and most preferably by less than 30% and very particularly preferably by less than 10% different. Deformation mirror (300). Claim 17 , characterized in that adjacent actuators (100), which have a different stiffness along a first stiffness axis (122) compared to a second stiffness axis (123), are arranged to one another in such a way that their first stiffness axes (122) have an angle between 50 ° and 110°, preferably between 60° and 100° and particularly preferably 60° or 90°. Deformation mirror (300) according to one of the Claims 14 until 18 , characterized in that the at least one mechanical translator (105) is made of the same material as the mirror body (301).

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