Optical system and lithographic apparatus

Abstract

A feedback control of the actuators has not been possible to date or only with an economically unacceptable effort.SOLUTION: The optical system comprises a mirror 210 and an actuator device 220. The actuator device comprises an electrostrictive actuator element 222 for generating a mechanical stress in the mirror body 212 for deforming the mirror surface 214 in response to an electrical drive voltage VS, and an electrostrictive sensor element for outputting a sensor signal SS in response to a deformation of the sensor element 224. The sensor component is arranged directly adjacent to the actuator component and / or at least partially in such a way that it is configured for transmitting mechanical stresses generated by the actuator component to the mirror body.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an optical system and a lithographic apparatus comprising such an optical system.

[0002] The contents of the priority application German Patent Application No. 10 2020 201 724.7 are hereby incorporated by reference. No. 6,239,999, filed on Oct. 1, 2003, which is incorporated by [Background technology]

[0003] Microlithography is a method for producing microstructured components, e.g., integrated circuits. The microlithography process is a lithography process that uses an illumination system and a projection system. This is done using a photolithography system, where a mask (reticle) is illuminated using an illumination system. ) is imaged using a projection system onto a surface coated with a photosensitive layer (photoresist) and positioned in the image plane of the projection system. The mask structure is projected onto a substrate, e.g., a silicon wafer, placed on the substrate, and the mask structure is transferred to the photosensitive layer of the substrate. Transfer the image to the drawing.

[0004] By using appropriately positioned actuators, the mirror surface can be deformed as desired. Mirrors are known that can correct or compensate for optical imaging errors, also known as aberrations. Aberrations can have different causes. Temperature fluctuations in particular can affect the position of the optical element holder. and / or may lead to mechanical stresses that can distort the optical element itself. As a result, the optical properties of the optical element may change. In astronomy, the concept of adaptive optics is well established. In this case, the mirror surface is measured. The deviation from the ideal shape is determined by scanning with constant light. It is possible to build a closed-loop control circuit that drives the corresponding actuator. This causes the mirror surface to approximate its ideal shape.

[0005] Mirrors whose surfaces can be deformed by actuators are also used in lithography equipment. However, many components, such as active or passive components, are used. Since many functional units must be arranged in a small volume, known lithography apparatus The installation space for the is very small. Therefore, in order to scan the mirror surface as described above, It is not practical to place an additional optical metrology system in the lithography apparatus. Feedback control of actuators has to date been impractical or economically unacceptable. This can only be done with an incredible amount of effort. Summary of the Invention [Problem to be solved by the invention]

[0006] Against this background, it is an object of the present invention to make available an improved optical system. [Means for solving the problem]

[0007] According to a first aspect, an optical system is proposed, comprising at least one mirror, the mirror comprising: A mirror body and a mirror surface are coupled to the mirror body to deform the mirror surface. At least one actuator device is provided. Mechanical stress is generated in the mirror body to deform the mirror surface in response to the electrical driving voltage. At least one electrostrictive actuator element and at least one electrostrictive sensor element At least one electrostrictive sensor that outputs a sensor signal in response to deformation of the sensor element. At least one sensor element is directly adjacent to the actuator element. and / or at least an actuator is provided on the side opposite to the mirror surface of the mirror body. and / or at least a part of the mirror body is separated from the mirror body by a photodetector element. Specifically, to transmit the mechanical stress generated by the actuator element to the mirror body. The arrangement is such that the

[0008] This optical system does not directly scan the mirror surface, but uses actuator elements to This has the advantage that the effects within the mirror body caused by the reflection can be detected. In this case, the change occurs within the physical domain, either mechanically or electrically, i.e., in response to an externally applied electric field. Within the coupling between the polarization of the material, which is shape-dependent, i.e., the actuator and the sensor Deformation detection and actuation are possible without relying on a different physical mechanism. It is possible that this is done with the help of the same mechanism of action, for example electromechanically via the piezoelectric effect. This allows the effects that occur to be uniformly described and treated. This keeps the complexity of the optical system low. The actuator and sensor elements are made of the same material class. This allows the optical system to be manufactured using a reduced number of different process steps. Furthermore, the optical system is, for this reason, very robust and relatively cheap to manufacture. It is easy to manufacture and has few breakdowns.

[0009] The optical system is especially designed as a projection optical unit for a lithographic apparatus. The optical system may be part of the beam forming and illumination system of a lithography apparatus. The system is used in applications where high precision beam guidance is necessary or desired, such as astronomy, scientific instruments, and military optics. In comparison with known adaptive optics units, this Optical systems are often used when a robust system is required and installation space is limited. This is particularly advantageous when cost and / or availability play a significant role.

[0010] The optical system includes at least one mirror. The optical system may include, in addition to the mirror, further mirrors. The optical element may comprise a lens element, a grating, an aperture, a filter, a cavity, etc. However, the optical system can also consist of mirrors with actuator devices. Additionally, the optical system may include a plurality of mirrors, each having an actuator device. Further optically effective elements of the optical system may be additional or other elements such as electric heaters, coolers, etc. The actuator may be provided.

[0011] The mirror surface of at least one mirror may have any geometric shape, e.g., a flat, convex, or concave surface. The mirror can have a shape or can be partially changed. The sections can be arranged at different positions in the beam path, in particular in the region of the pupil or hatch. Depending on the position in the beam path, various imaging errors or aberrations are compensated for by deformations of the mirror surfaces. Deformation is understood to mean in particular deviations from the basic shape of the mirror surface. For example, when the mirror is placed in the holder and orientation intended for its operation without stress, the mirror will retain its basic shape. In this case, the basic shape may deviate from the ideal shape due to, for example, the mirror's own weight. However, the ideal shape is restored by deformation of the mirror surface. The deformation of the mirror surface is the deformation of the mirror when there is no charge, current, or voltage on the actuator element. This is understood as a deviation from the shape of the surface.

[0012] The actuator device comprises at least an actuator element and a sensor element Preferably, the actuator device includes a driving circuit for driving the actuator element with a driving voltage. The drive voltage is controlled by, for example, a control unit, depending on the mechanical stress to be achieved. The mechanical stress directly determines the deformation of the mirror surface. The functional relationship between mechanical stress and deformation depends on, for example, the material parameters of the mirror body, and It depends on boundary conditions such as geometric factors. Alternatively, the control computer can determine the desired results to be achieved. The drive unit itself determines the required drive voltage for this. Check the pressure.

[0013] The actuator device is configured such that the mirror surface moves in response to an electrical drive voltage applied to the actuator element. It is deformably coupled to the mirror body of the mirror.

[0014] The drive unit comprises, for example, a voltage source or a current source. The device can be operated with closed-loop controlled voltage or closed-loop controlled charge. Especially in dynamic applications where the position of the actuator element is changed frequently, It is advantageous to operate it with loop-controlled charging.

[0015] The actuator elements and sensor elements comprise electrostrictive materials, such as piezoelectric materials. Electrostrictive materials are understood to include materials that are electrically insulated from the magnetic field. The interaction can produce mechanical stresses or forces in the material that manifest as deformation of the material. Conversely, deformation of the material leads to a change in the polarization of the material. It is possible to measure the deformation amplitude and thus draw conclusions about it.

[0016] It is pointed out that the terms force, mechanical stress, or deformation can be used interchangeably.

[0017] Examples of electrostrictive materials are lead magnesium niobate (PMN) or lead zirconate titanate (P ZT) are ceramic compounds containing elements. These preferably have improved mechanical properties. It is alloyed with platinum to reduce the dielectric properties, especially the maximum polarization. Therefore, alloys are materials that can be characterized by an alloying factor x. It has the composition: PMN x -P t1- x or PZT x P t1-x is.

[0018] In a preferred embodiment of the optical system, the electrostrictive material has a Curie temperature in the range of 0 to 40°C. At the Curie temperature, the first crystal structure that predominates below the Curie temperature changes to the second crystal structure that predominates above the Curie temperature. A phase transition to a second predominant crystal structure occurs at the top.

[0019] The actuator element preferably comprises an active area, for example a layer made of an electrostrictive material. This region is placed between two electrodes, an anode and a cathode. By applying a driving voltage between the gates, an electric field is created in the active area, which This leads to mechanical stress.

[0020] The actuator element is mechanically coupled to the mirror body. The mechanical stress of the mirror element is transferred to the mirror body. The degree of deformation achieved at a particular force is expressed as a function of the mirror surface. -Depends on the strength of the material of the body.

[0021] The sensor element is preferably also made of an electrostrictive material, for example a layer, arranged between two electrodes. However, the sensor element and the actuator are not necessarily connected to the active area. The elements may differ, for example, in their geometric dimensions and / or material composition.

[0022] The sensor element preferably has a measurement current applied between the cathode and the anode of the sensor element. The assigned measuring unit checks the polarization of the active area of ​​the sensor element using a current voltage. The sensor signal output by the sensor element is in particular The deformation of the active area of ​​the sensor element can be derived therefrom. In particular, the measured AC voltage is subject to a significant mechanical stress in the active area. The measuring unit is an independent unit of the actuator device. The measuring unit and the sensor element can be assigned to each other. In the following description, the term sensor element refers to the entire sensor element or the sensor element This refers only to the active area of ​​the

[0023] The sensor element detects the deformation of the actuator element and / or the deformation of the mirror body. When the actuator element is pressed against the substrate, it is deformed by a mechanical stress applied by the actuator element, for example. The actuator element and / or the mirror body are mechanically coupled to the actuator element and / or the mirror body so as to

[0024] In a preferred embodiment, the sensor element is positioned directly adjacent to the actuator element. Directly adjacent means, for example, that there is no intermediate layer or layer between the actuator element and the sensor element. It is understood to mean that there is no additional material. It can also be said that the child is in contact.

[0025] In a further preferred embodiment, the sensor element is located on the side of the mirror body opposite the mirror surface. The actuator element is preferably arranged so as to be separated from the mirror body by at least one of the actuator elements. The sensor element is disposed directly behind the actuator element. The back side is the side that points away from the mirror body. There may be additional layers between.

[0026] In a further preferred embodiment, the sensor element is at least partly an actuator The sensor element is positioned to transmit mechanical stress generated by the element to the mirror body. The actuator element transmits force from the actuator element to the mirror body, or the actuator element and the mirror body It can be said that the sensor element forms an operational connection with the mirror body. Alternatively, the sensor element may be disposed between the actuator element and the mirror body. In this case, the sensor element, the actuator, and the The mechanical bond between the actuator element and the matrix material allows mechanical stress to , the matrix and the sensor element at least substantially uninterrupted transitions. In this case, the matrix including the sensor element and the actuator element is It can be said that the Trix appears to be a substantially homogeneous body when viewed from the outside.

[0027] This arrangement allows for a strong force between the sensor element, the mirror body, and the actuator element. This ensures a good mechanical connection, which is why high measurement accuracy can be achieved.

[0028] The mechanical coupling between the actuator element, the sensor element and the mirror body is in particular of the form The interlocking connection is preferably a material-bonding joint such as an adhesive joint. This is done by concentrating connections.

[0029] Preferably, the calibration measurements are performed before the optical system is put into operation. In this case: The mirror surface is irradiated with measurement light and the actuator device deforms the mirror surface. The deformation of the mirror surface achieved by the electromotive voltage can be determined by the measurement light. Additionally, simultaneous detection of the sensor signals allows the deformation of the mirror surface and A correlation between the sensor signal and the voltage is also established. Therefore, no hysteresis occurs. In contrast, the dielectric properties of the actuator element may change during operation. Therefore, there is a relationship between the driving voltage and the deformation achieved in the calibration measurement. Accurate control based on the correlation of sensor signals is almost impossible. It can be checked during operation whether the deformation achieved corresponds to the desired deformation. .

[0030] According to one embodiment of the optical system, the optical system is configured such that a predetermined mechanical stress is achieved in the mirror body. Thus, the actuator element is driven in response to the sensor signal output by the sensor element. It has a closed-loop control unit that controls the drive voltage.

[0031] The closed loop control unit advantageously controls the sensor signal output by the sensor element. This is because the closed loop control unit is configured to control the drive voltage by, for example, an evaluation unit for evaluating the input sensor signals and deriving therefrom the achieved mechanical stress; Alternatively, this step can be performed by the control computer. The closed-loop control unit can be combined with a drive unit, for example. This can be done.

[0032] The closed-loop control unit may be implemented in the form of hardware and / or software. When implemented in hardware form, the closed loop control unit can be, for example, It can be designed as a computer or microprocessor. When implemented in this manner, the closed-loop control unit may be implemented as a computer program product with the function as a routine, as part of program code, or as an executable object It can be designed as a

[0033] Therefore, by using an actuator device, the mirror surface can be moved in a closed loop manner. The actuator element can be controlled to precisely deform. directly to the actuator element and / or behind the actuator element and / or By placing the actuator element in the direct motion or force path to the mirror body, This ensures high accuracy of the closed-loop control.

[0034] According to a further embodiment of the optical system, at least one actuator element and at least Each sensor element is fabricated monolithically.

[0035] This is especially true when the actuator element and the sensor element are made from materials of the same material class. This means that the same manufacturing techniques are used to fabricate both elements. Lithic means that the actuator and sensor are based on the same mechanism of action. Preferably, the two elements are manufactured together, i.e., in the same process. , the exact same technology is used for the actuator and sensor elements. The advantage is that it keeps the complexity of the optical system low.

[0036] In particular, actuator-cells in which actuation is performed, for example, electrically, but measurement is performed optically. The sensor arrangement is not monolithic. Similarly, actuation is done electrically using a magnetic field, but While the measurement is done electrically, e.g. by capacitance measurement, the monolithic It's not ku.

[0037] According to a further embodiment of the optical system, at least one actuator element and at least Each sensor element is a layer disposed on the mirror on the side opposite the mirror surface of the mirror body. is integrated into

[0038] This embodiment provides individual actuator elements and individual sensor elements on the mirror body. There is no need to place and mount the actuator and sensor elements inside. The advantage is that a layer with a uniform thickness is produced, which is then applied to the rear side of the mirror, i.e. The layer is attached in its entirety to the side of the body opposite the mirror surface. Alternatively, a plurality of two-dimensional planar elements may be formed from this layer, They can also be arranged side by side on the back side of the mirror. At least one actuator element and The fact that the actuator and at least one sensor element are integrated into the layer means that, in particular, The active area of ​​the data element (the area where mechanical stress occurs) and the sensor element (the area where the polarization is detected) It is understood that the area (the area where the sensor element is exposed) is integrated into the layer. No other units are integrated into the layer.

[0039] The layer is preferably made entirely of electrostrictive material. Active area, i.e., actuator The sub-regions of the material and the sub-regions of the sensor are formed by disposing electrodes. The remaining portion can be referred to as the matrix material or passive material.

[0040] According to a further embodiment of the optical system, at least one sensor element is at least partially , along the surface normal of the mirror surface between at least one actuator element and the mirror body. are placed in the direction.

[0041] The actuator and sensor elements may be partially or completely overlapping. This arrangement allows the sensor elements to be closer to the mirror body than the actuator elements. This allows the sensor element to be positioned closer to the mirror surface. The shape or mechanical stress is extremely high, resulting in deformation of the mirror body and therefore the mirror surface. This is the reason for the correlation, which makes the closed loop control more accurate.

[0042] According to a further embodiment of the optical system, at least one actuator element and at least Each of the single sensor elements includes at least one layer of electrostrictive material.

[0043] Here, the layers preferably have a thickness to extent, i.e., length or width, aspect ratio of at least 1 / 2 mm. at least 1:5, preferably at least 1:10, preferably at least 1:100, preferably is understood to mean a shape that is up to 1:1000, in which case the length and width are approximately the same. For example, the layers are assumed to be between 10 μm and 500 μm thick and have lengths and The size and width of the tube are 0.5-5 cm, or the tube is circular with a diameter of 0.5-5 cm. do.

[0044] The layer is then subjected to a process to determine the effect to be achieved, i.e. the mechanical stress achieved at a particular driving voltage in the plane of the layer. or deformation is greater than the effect occurring in the direction perpendicular to it by a factor of the aspect ratio When the material expands in the first direction due to the electrostrictive effect, it is incompressible. This always involves shrinkage in a second direction different from the first direction due to the

[0045] Very thin layers also have the advantage that high deformations or forces can be achieved with low driving voltages. It has points.

[0046] According to a further embodiment of the optical system, at least one actuator element is made of an electrostrictive material Each layer of the plurality of layers has an assigned cathode and an assigned Each of the electrodes has an anode and can be driven by a respective driving voltage.

[0047] This multilayer structure increases the force or mechanical stress achievable in the actuator element compared to a single layer. This has the advantage that the total force achieved by the individual layers can be significantly increased compared to the Therefore, larger deformation is possible. Therefore, it is possible to effectively correct aberrations. The area expands.

[0048] In an optical system embodiment, a cathode enclosed between two layers is a common cathode of the adjacent layers. An anode enclosed between two layers forms a common anode for the adjacent layers. Complete.

[0049] In this case, the electric field has opposite directions in adjacent layers. No insulating separation layer is required between the two cathodes or anodes, and the cathode material or anode The amount of active material is also minimized, allowing for a smaller ratio of active material in the actuator element. It is something that can be maximized.

[0050] In this embodiment, the electric fields have opposite directions in adjacent layers. An electrostrictive material is chosen in which the mechanical strain is proportional to the square of the polarization. The direction of the electric field is opposite to the direction of the force. This is to avoid any impact.

[0051] According to a further embodiment of the optical system, at least one actuator element and at least Each sensor element forms a layer stack comprising at least two layers.

[0052] In this case, the sensor layer may be directly connected to the actuator layer, for example, by providing a common electrode therebetween. This allows for a particularly compact design. The mechanical coupling between the sensor element and the actuator element is also maximized. This allows the drive voltage of the actuator element to be adjusted very precisely. This is why it can be subjected to efficient closed-loop control.

[0053] According to a further embodiment of the optical system, the actuator device comprises at least two cells. At least two of the sensor elements have different electrostrictive materials with different material compositions. Each of the two sensor elements is configured to output a sensor signal.

[0054] For example, temperature fluctuations can affect the polarization of the active material, leading to measurement errors. This embodiment is advantageous because layers with different compositions are affected differently by temperature fluctuations. Therefore, the influence of temperature can be removed by calculation, which improves reliability and measurement accuracy. In this case, the thickness of the layer stack consisting of the two sensor elements is so small that e.g. , it can be assumed that both sensor elements have the same temperature.

[0055] According to a further embodiment of the optical system, the sensor signals output by at least two sensor elements are A confirmation unit is provided that is configured to confirm the temperature within the mirror body in response to the sensor signal. can be.

[0056] By comparing two sensor signals of sensor elements with different compositions, the underlying The effects of mechanical stress and temperature are evaluated by corresponding physical models that describe the This means that optimal cooling of the mirror body is not possible in the required areas. or where cooling is only possible with great effort. The mechanical stress on the mirror body caused by temperature fluctuations or local temperature differences is can be taken into account when checking the current shape of the controller surface and / or Advantageously, this can be achieved without additional systems. It is possible.

[0057] In this case, the temperature that can be ascertained is related to the temperature of the mirror body in the area of ​​the two sensor elements. It is related to the temperature and therefore the local temperature in particular.

[0058] According to a further embodiment of the optical system, the measuring unit measures the AC voltage in at least two The frequency of the AC voltage to be measured is provided to be applied to the sensor element to generate a sensor signal. is different for different sensor elements.

[0059] This includes the crosstalk between different conductor tracks to the sensor element, which is measured during the evaluation. It has the advantage that it does not lead to errors. Frequency division multiplexing can also be mentioned. The measuring unit may in particular be part of a closed-loop control unit or an actuator device. However, they can also form independent units.

[0060] According to a further embodiment of the optical system, the actuator device comprises a plurality of M actuators. The actuator comprises an actuator element and a plurality of sensor elements, M and N being integers. The eta elements and sensor elements are arranged alternately.

[0061] Preferably, N>M, in particular N=M+1, so that in each case one sensor element For example, N=2 and M=1, and two sensor elements are actuators. The elements form a sandwich structure, where it is advantageous to identify the two-dimensional deformation function. Therefore, the actual deformation at a portion slightly away from the actuator element can be calculated. can be more accurately confirmed or predicted, which improves the accuracy of closed-loop control. It can also be said that more precise closed-loop control is possible due to the multi-layered decision making.

[0062] According to a further embodiment of the optical system, the actuator device comprises at least one sensor The sensor signal output from the sensor element is calculated based on the calibration measurement. The closed-loop control unit includes an allocation unit configured to allocate the deformation to be achieved. The unit controls the driving voltage according to the assigned value and the predetermined deformation of the mirror surface. It is configured as follows.

[0063] In an embodiment, the allocation unit determines whether the value of the sensor signal corresponds to the achieved deformation of the mirror surface. This embodiment is particularly simple. Intermediate values, i.e., sensors not stored in the LUT, are used. The value for the transformation in the case of a signal value is determined from the two closest values, e.g., by linear interpolation. It can be recognized.

[0064] According to a further embodiment of the optical system, the plurality of actuator devices comprises at least one Each of the plurality of actuator devices is individually controllable.

[0065] Preferably, the mirror is covered with actuator devices, for example on the entire surface. By appropriately driving the actuator device, the mirror surface can be freely changed in various ways. Each actuator device is advantageously equipped with a closed-loop control unit. Therefore, each actuator device can be closed independently from other actuator devices. In particular, when actuator devices are adjacent, the mechanical stress can be controlled by the loop. Since the force propagates throughout the mirror body, the deformation at the location of the first actuator device is 2 This may lead to slight deformations at the actuator device location. , which is detected by the sensor element of the second actuator device. If desired, appropriate closed-loop control of the actuator elements to suppress deformation. is also possible.

[0066] According to a second aspect, a lithography system having an optical system according to one of the first aspects or embodiments is provided. A laffy device is proposed.

[0067] The lithography apparatus includes a closed-loop control circuit that controls each of the actuator elements. This has the advantage that, if there is an imaging error, it can be corrected or compensated for. This allows for much more accurate correction of aberrations than would be possible without such a closed-loop control circuit. In a lithography apparatus, the optical units used operate in a vacuum, for example, so the installation space is limited. The source is so small that conventional solutions in adaptive optics cannot be used.

[0068] The optical system preferably constitutes a beam forming and illumination system or a projection system of a lithographic apparatus. , or part of such a system.

[0069] According to a third aspect, use in an optical system of a mirror coupled to an actuator device The actuator device includes a mirror body and a mirror surface. generates mechanical stress in the mirror body to deform the mirror surface in response to an electrical driving voltage. At least one electrostrictive actuator element and at least one electrostrictive sensor element At least one electrostrictive sensor element is provided, which outputs a sensor signal in response to deformation of the sensor element. and a sensor element. At least one sensor element is directly adjacent to the actuator element. and / or have at least one active element on the side of the mirror body opposite the mirror surface. and / or at least also partially transmits the mechanical stress generated by the actuator element to the mirror body. The actuator device is configured to electrically drive the mirror surface. The mirror body is coupled to the mirror body so as to be deformed in response to a voltage.

[0070] According to a fourth aspect, a method for operating an optical system is proposed. The optical system comprises a mirror body and a mirror having a mirror surface and an actuator coupled to the mirror body for deforming the mirror surface; In the first step, the power supply of the actuator device is turned on. The strain-type actuator element is driven by an electrical driving voltage. As a result, a mechanical force is applied to the mirror body. A force is generated, causing the mirror surface to deform. In a second step, the actuator device By using at least one electrostrictive sensor element, a sensor signal is generated in response to the deformation of the sensor element. At least one sensor element is disposed immediately adjacent to the actuator element. and / or at least an actuator element on the side of the mirror body opposite to the mirror surface. Separated from the mirror body by a child and / or at least partially , configured to transmit mechanical stress generated by the actuator element to the mirror body. The components are arranged so that the

[0071] In embodiments, the optical systems described above and below perform the aforementioned methods or It is configured to operate in accordance with the law.

[0072] According to a further aspect, the effect of the mirror surface of the optical system according to one of the first aspect or embodiments is A method for detecting deformations is proposed. In the first step, at least one act The actuator element is driven by a driving voltage corresponding to a predetermined deformation of the mirror surface. The control computer detects deviations of the mirror surface from the actual target shape in the current state of the optical system. Check the ideal shape of the surface and, accordingly, check the drive voltage required for the actuator element. In the second step, at least A single sensor element outputs a sensor signal. This is especially true when the measured AC voltage is applied to the sensor element. From the complex impedance of the sensor element, The dielectric susceptibility and therefore the polarization of the active region can be inferred. The deformation of the sensor element is confirmed according to the output sensor signal. The polarization of the active area of ​​the sensor element determines the deformation of the surface. This shows the deformation of the mirror surface using a mechanical model of the mirror. Preferably, the deformation of the mirror surface in response to the deformation of the sensor element is measured by a calibration. This is checked in advance during the measurement and stored in the LUT.

[0073] In an advantageous embodiment of the method, the driving voltage is adjusted so that a predetermined deformation of the mirror surface is achieved. is controlled by closed-loop control.

[0074] The embodiments and features described for the optical system are correspondingly applicable to the proposed method. do.

[0075] In this specification, the indefinite article and the number "A(n)" do not necessarily mean exactly one. The number of elements should not be understood to be limited to, for example, two, three, or more. Multiple elements such as these may be provided. Other numbers used herein may also be used interchangeably. This should not be understood to mean that there is a strict limit to the number of elements used. Unless otherwise indicated, deviations in the values ​​above and below are possible.

[0076] Further possible implementations of the invention are described above or below with respect to exemplary embodiments. Combinations of features or embodiments not expressly mentioned are also included. Individual aspects may be added as improvements or supplements to each basic form of the present invention. can.

[0077] Further advantageous configurations and aspects of the invention are the subject of the dependent claims and are described below. The invention is also the subject of examples of the invention. The invention will now be described in detail with reference to the accompanying drawings, in which: and are described in more detail below. [Brief explanation of the drawings]

[0078] [Figure 1] 1 is a schematic diagram of a first exemplary embodiment of an optical system. [Figure 2] 1 is a schematic diagram of a first exemplary embodiment of an arrangement of mirrors with actuator devices; [Figure 3] 10 is a schematic diagram of a second exemplary embodiment of an arrangement of mirrors with actuator devices; [Figure 4] 10 is a schematic diagram of a third exemplary embodiment of an arrangement of mirrors with actuator devices; [Figure 5] 10 is a schematic diagram of a fourth exemplary embodiment of an arrangement of mirrors with actuator devices; [Figure 6]FIG. 10 is a schematic diagram of a fifth exemplary embodiment of an arrangement of mirrors with actuator devices. [Figure 7] FIG. 10 is a schematic diagram of a sixth exemplary embodiment of an arrangement of mirrors with actuator devices. [Figure 8] FIG. 10 is a schematic diagram of a seventh exemplary embodiment of an arrangement of mirrors with actuator devices. [Figure 9] 1 is a schematic diagram of an exemplary embodiment of the structure of an actuator element; [Figure 10] 1 is a schematic diagram of an exemplary embodiment of driving multiple actuator elements and sensor elements in an actuator device; [Figure 11] 1 is a graph of three behaviors of physical variables as a function of driving voltage. [Figure 12] 1 is a graph showing multiple curves of dielectric susceptibility as a function of driving voltage. [Figure 13] FIG. 2 is a schematic block diagram of an exemplary embodiment of a closed-loop control circuit. [Figure 14A] 1 is a schematic diagram of an exemplary embodiment of an EUV lithography apparatus; [Figure 14B] 1 is a schematic diagram of an exemplary embodiment of a DUV lithography apparatus; [Figure 15] 1 is a schematic block diagram of an exemplary embodiment of a method for correcting aberrations in an optical system; DETAILED DESCRIPTION OF THE INVENTION

[0079] Unless otherwise specified, identical or functionally identical elements are designated by the same references in the figures. Please note that the drawings are not necessarily to scale. I want to be done that.

[0080] 1 shows a schematic diagram of a first embodiment of an optical system 200. The optical system 200 here includes a light source LS, a lens element 128 that collimates the light coming from the light source LS, and two mirrors 1 10, 210 and a further lens element 128, and the light from the further lens element 128 is focused. and a wafer 124 or objective slide to be scanned. For example, the optical system 200 may be a microscope or or illumination systems of lithographic apparatuses 100A and 100B (see FIGS. 14A and 14B).

[0081] The second mirror 210 of the optical system 200 is made up of a mirror body 212. The mirror surface 214 is disposed on the front side. The actuator device is disposed on the back side of the mirror body 212. The actuator device 220 applies mechanical stress to the mirror body 2 12 to deform the mirror surface 214. Without limiting the scope of the invention, in this specification and in the following drawings, each element may be referred to as an element. Only the actuator device 220 is shown. However, it goes without saying that the mirror A plurality of such actuator devices 220 may be arranged on the mirror surface 210 to with high spatial resolution and / or global deformation of the mirror 210. can be achieved.

[0082] The fact that the mirror surface 214 of the mirror 210 can be deformed allows for aberrations, i.e. In this case, the imaging error can be compensated for, in particular, in the optical system 200 and and / or the operating conditions of further optical systems coupled with the optical system 200. The temperature difference and / or temperature fluctuation over time is 20. Therefore, the state is compensated for by the closed loop control with respect to the reference state. It can also be referred to as an adaptive optics system 200 that is subjected to or kept constant. The actuator device 220 is a closed loop control circuit that regulates the actuator element 222. (See Figures 2 to 8, 10, 13, 14A, or 14B).

[0083] The exact mode of operation of the actuator device 220 will be described in more detail with reference to the following figures: I will explain in detail.

[0084] 2 to 7 each show an example of an arrangement of a mirror 210 with an actuator device 220. 2 shows a schematic diagram of an exemplary embodiment of an actuator device 220 and a 1, 14A, and 14B, and the particular placement of the mirror 210. can be used in optical system 200 as shown in FIG. 14B.

[0085] FIG. 2 shows an actuator disposed between the mirror body 212 and the mirror carrier 216. The mirror carrier 216 forms a mechanical fixing point, i.e. The actuator device 220 is rigid and fixed. 22 and a sensor element 224. In this case, the sensor element 224 is 2. The actuator element 222 is supported on the mirror carrier 216. Further, a driving unit 222 provides a driving voltage VS for driving the actuator element 222. In this embodiment, the drive unit 226 drives the sensor element 224. Preferably, the drive unit 226 is a closed loop control unit. or a control unit that adjusts the drive voltage VS depending on the sensor signal SS. Equipped with.

[0086] In this arrangement, the actuation direction 223 is parallel to the surface normal of the mirror surface 214. The motor element 222 stretches or expands in an actuation direction 223 when a drive voltage Vs is applied. Since the mirror carrier 216 is fixed, the actuator element 222 extends. When the actuator device 220 is moved, the mirror surface 214 expands or displaces. Here, the mirror body 212 is connected to one or more fixed connecting elements (not shown). The mirror can be supported on the mirror carrier 216 at multiple points. The connecting element is arranged at a position where, for example, the mirror body 212 and the mirror carrier 216 are connected. Fix the spacing.

[0087] FIG. 3 shows an actuator disposed between the mirror body 212 and the mirror carrier 216. 2 shows an alternative embodiment of the device 220, in which the sensor element 224 is directly attached to the side In this arrangement, the sensor element 224 is Any deformation, in particular extension or compression, of the actuator element 222 along the actuation direction 223 , accurately follows. Therefore, the actual deformation of the actuator element 222 can be calculated by the sensor signal It can be determined very accurately from the SS.

[0088] 4 to 7 each show a different integration form of the actuator device 220. 2 and 3, the operation in the lateral direction, i.e. in the plane of the mirror body 212, 4 and 5, the actuator device 220 is - is glued to the backside of the body 212 or is securely connected thereto in a similar manner. In this case, the sensor element 224 is disposed between the actuator element 222 and the mirror body 212. 4), or on the back side of the actuator element 222 (FIG. 5). In the arrangement shown in FIG. 1, the sensor element 224 detects the voltage generated by the actuator element 222. In particular, the sensor element 224 transmits any mechanical stresses to the mirror body 212. The area of ​​the mirror body 212 that is in direct contact with the actuator element 222 and also with the sensor element 224. The actuator element 222 can be expanded or contracted. The lateral actuation 223 generates mechanical stresses in the mirror body 212. As a result, the mirror surface 214 undergoes a corresponding deformation.

[0089] In the exemplary embodiment of FIGS. 6 and 7, the actuator element 222 and the sensor element 224 is embedded in a matrix MX, which in particular contains the actuators The sensor element 224 is preferably made of an electrostrictive ceramic material of the same material class as the element 222. Advantageously, the actuator element 222, the sensor element 224, and The matrix MX forms a substantially homogeneous material layer 221. This material layer 221 is The actuator 212 is fixed to the rear side of the main body 212 in a two-dimensional plane, preferably over the entire surface. The active areas of the capacitor elements 222 and the sensor elements 224 are connected to the electrodes in the matrix MX. In these embodiments, the mirror of the actuator element 222 This provides a particularly strong mechanical bond with the mirror surface 214. It has a beneficial effect on large deformation.

[0090] The exemplary embodiments shown in Figures 2-7 may be combined with one another as desired. .

[0091] FIG. 8 shows a fourth exemplary embodiment of an arrangement of a mirror 210 with an actuator device 220. 8 shows a schematic diagram of an embodiment. The basic arrangement corresponds to the arrangement shown in FIG. 7. The actuator device 220 here surrounds the actuator element 222 in a sandwich-like manner. It has two sensor elements 224. Advantageously, the two sensor elements 224 have different chemical compositions. As such, they have different dependencies on temperature and deformation. From the two sensor signals SS, not only the deformation but also the temperature of each sensor element 224 can be confirmed. In this case, this is done by a verification unit 230 specially designed for this purpose. This is done accordingly.

[0092] FIG. 9 shows the structure of an actuator element 222, here consisting of a plurality of individual layers L1 to Ln. 1 shows a schematic diagram of an exemplary embodiment of the electrode A1 disposed on the top layer L1. Here, the uppermost layer L1 acts as an anode, for example. Between the layer L2 and the layer L3 there is arranged a further electrode K1 which here acts as a cathode. The anode A1 and cathode K1 may be said to surround the top layer L1 in a sandwich fashion. A driving voltage VS (Figs. 2 to 8 or 10 to 12) is applied between the anode A1 and the cathode K1. 13) creates an electric field in the layer L1. The anode A1 and cathode K1 also serve as Also, the embodiment can be reversed, in which case the direction of the electric field is reversed.

[0093] Between the second layer L2 from above and the third layer L3 from above, the electrode A2 is again disposed. The electrode A2 acts as an anode, while the cathode K1 is connected to the adjacent layers L1 and It can be seen that the anode A2 also forms a common cathode for the adjacent layer L2. Form a common anode for L2 and L3.

[0094] In this embodiment, this layering continues until the desired number of layers is reached. The terminal electrode Kn is disposed below the cathode in this embodiment. In this alternating structure with common electrodes A1 to An, K1 to Kn, the electrostrictive material In particular, the mechanical strain is proportional to the square of the polarization, so that the electric field direction is different. Regardless of the deformation, the layers L1 to Ln are deformed in the same direction.

[0095] In other embodiments where an electrostrictive material is used in which the mechanical strain is proportional to the polarization, electrodes A1 to An The layers K1 to Kn are arranged so that the electric fields in all layers L1 to Ln are directed in the same direction. Otherwise, the layers L1 to Ln will operate inversely to each other.

[0096] The thickness of each of the layers L1 to Ln may be different. The layer thicknesses of L1 to Ln are substantially the same and are selected from the range of 10 μm to 500 μm. In this case, the material composition can also be varied between layers L1 to L2, for example, to achieve different electrostrictive properties. n can be selected to be different for each

[0097] In a further embodiment, the sensor element 224 is shown for the actuator element 222. 9. In this case, in particular, for the different layers L1 to Ln The use of different chemical compositions allows the comparison of the sensor signals SS of the individual layers L1 to Ln. In addition to the mechanical stress, further influencing variables, in particular the temperatures of layers L1 to Ln, can be derived and determined. This has the advantage that it can be

[0098] FIG. 10 shows a plurality of actuator elements 222, a plurality of sensor elements 224, and a drive unit. 2 shows a schematic diagram of an exemplary embodiment of an actuator device 220 comprising: In this case, three sensor elements 224 and two actuator elements form a stack. Here, the actuator elements 222 are each made of, for example, an electrostrictive material. The laminated body 10 includes three layers L1 to L3.

[0099] Two of the sensor elements 224 sandwich the entire stack. The sensor element 224 divides the stack down the middle. In this case, each passive region has a sensor element 224 and the actuator element 222. In an embodiment in which the electrode disposed between the actuator element 222 constitutes a common electrode, It can be omitted. In this case, it is preferable that the common electrode is grounded. , advantageously because it operates without a bias voltage.

[0100] The drive unit 226 here provides a drive voltage Vs for the actuator element 222. Each sensor measures the AC voltage VM using a voltage source that is subject to closed-loop control to provide three measurement units configured to generate a sensor signal SS of the element 224; The measuring AC voltage VM is preferably in this case at different frequencies to avoid mutual interference. In a further embodiment, the actuator elements 222 are driven by different drive voltages. It can also be run in VS.

[0101] FIG. 11 shows the behavior of physical variables, namely, mechanical stress σ, drive The slope ∂e / ∂VS of the deflection e achieved with respect to voltage VS, as a function of the driving voltage This exemplary electrostrictive layer is shown in three diagrams of the dielectric constant χ of the actuator element 222 (Fig. 2-10 or 13) or sensor element 224 (see Figs. 2-8, 10 or 13 ) where the variables σ, e, and χ are in arbitrary units. The unit of volt is chosen as the scale for VS. The electrostrictive material is, in particular, of the composition PMN x P t1- The curves shown are for the mechanically free state of the layer, i.e., It refers to the state in which there is no mechanical prestress and the layer is not embedded in a rigid material system.

[0102] The figure above shows the mechanical stress σ( Unit: N / m 2 or Pa). When the driving voltage VS=0, the layer is not subjected to any mechanical stress. Similarly, a small driving voltage VS results in only a small mechanical stress σ. When the driving voltage VS is small, the generated mechanical stress σ is, for example, For example, it is proportional to the square of the drive voltage VS.

[0103] The central figure shows the gradient of the deflection e achieved as a function of the driving voltage Vs. are shown as numbers.

[0104] The figure below shows the dielectric constant χ as a function of the driving voltage VS. The dielectric constant χ is given by: It can be seen that it has a maximum value at 0.

[0105] As shown in FIG. 12, the dielectric constant χ when the driving voltage VS=0 is In addition, it has a very high sensitivity. In FIG. 12, the dielectric constant χ as a function of the driving voltage VS A number of curves are shown in one diagram. The five curves 1 to 5 shown in this diagram are the layers For example, curve 3 shows the deformation of the Curves 1 and 2 correspond, for example, to layer elongation in the ppm range, e.g. 10 ppm for curve 1 and 5 ppm for curve 2. Curves 4 and 5 are For example, this corresponds to a layer compression in the ppm range, e.g., 5 ppm for curve 4, and For 5 it is 10 ppm. For this sensitivity maximum of the dielectric constant χ, this physical variable is , as measurement variables for determining the deformation of the layer, in particular the deformation of the layer at the sensor element 224, The dielectric constant χ is particularly well suited for this purpose. This can be determined by the regulations.

[0106] FIG. 13 illustrates an exemplary implementation of a closed-loop control circuit in the actuator device 220. In this case, the drive unit 226 is a closed-loop control unit. The closed-loop control unit 226 is designed as a control computer. The actuator device 220 drives the actuator element 222 via a motor (not shown). A predetermined mechanical target stress σ to be supplied or generated using s Then, a closed loop control The control unit 226 drives the actuator element 222 with a drive voltage V. S is preferably a mechanical target that is known, for example from measuring the properties of the actuator element 222. Stress σ s The driving voltage Vs is selected to accurately achieve the above under favorable conditions. However, due to hysteresis or various environmental influences, the actuator element 222 Mechanical target stress σ s There is a possibility that the measurement may be slightly off.

[0107] The sensor element 224 is deformed by the actuator element 222. The degree of deformation is as described above. This is represented in this case by the sensor signal SS. The signal SS is in particular a function of the deformation of the sensor element 224 and thus the magnitude of the deformation of the sensor element 224. The sensor element 224 is directly connected to the actuator element 222. By coupling to the actuator element 224, the mechanical stress σ in the sensor element 224 222. The sensor signal SS therefore corresponds substantially to the mechanical stress σ at the closed loop. Therefore, the closed-loop control unit 226 is suitable for the sensor signal The drive voltage VS of the actuator element 222 is readjusted based on the SS.

[0108] In this case, the closed-loop control cycle is, for example, 10 Hz to 1 kHz. It can last from 1ms to 100ms depending on the frequency.

[0109] FIG. 14A shows a schematic diagram of an EUV lithography apparatus 100A. The apparatus 100A includes a beam forming and illumination system 102 and an optical system 203, here designed as a projection system. 00. In this case, EUV stands for "extreme ultraviolet" and 0. The working light wavelength is between 1 nm and 30 nm. The projection system 200 and the projection system 200 are each provided in a vacuum housing (not shown). The vacuum housing is placed in a machine room (not shown). The machine room is equipped with a drive unit for mechanically moving or setting the optical elements. Furthermore, an electrical control unit may be provided in the machine room.

[0110] The EUV lithography apparatus 100A includes an EUV light source 106A. For example, A is the EUV region (extreme ultraviolet region) in the wavelength range of 5 nm to 20 nm. A plasma source (or synchrotron) can be provided that emits radiation 108A. In the beam forming and illumination system 102, the EUV radiation beam 108A is focused and irradiated to a desired position. wavelengths are filtered out of the EUV radiation beam 108A by the EUV light source 106A. The generated EUV radiation 108A has a relatively low transmittance in air. The beam guide spaces in the beam formation and illumination system 102 and the projection system 200 are evacuated.

[0111] The beam forming and illumination system 102 shown in FIG. 14A includes five mirrors 110, 112, 114, After passing through the beam forming and illumination system 102, the EUV radiation 1 08A is guided to a photomask (reticle) 120. The photomask 120 also It can be designed as a reflective optical element and placed outside the systems 102, 104. The EUV radiation beam 108A can be directed to a photomask 120 using a mirror 122. The photomask 120 can be reduced and shaped onto a wafer 124 or the like using a projection system 200. It has the structure to be imaged.

[0112] A projection system 200 (also called a projection lens) focuses the photomask 120 onto the wafer 124. In this case, the individual mirrors M1 to M5 of the projection system 200 M5 may be positioned symmetrically with respect to the optical axis 126 of the projection system 200. It should be noted that the number of mirrors M1 to M5 of the imaging device 100A is not limited to the number shown in the figure. The number of mirrors provided can be increased or decreased. Usually the front side is curved to form a beam.

[0113] The projection system 200 further comprises a further mirror 210. Behind it are a number of active 2-8, 10, or 13. Each actuator device 220 can be designed as shown. The drive unit includes an actuator element 222 assigned to it and a sensor element 224 assigned to it. The unit 226 controls the actuator elements 222 to generate each of the sensor signals SS. is driven by a drive voltage VS, and a measurement AC voltage VM is applied to the sensor element 224. For clarity, the actuator element 222 and the sensor element 223 are Only one drive unit 226 is shown, which drives all 24. The front side of the mirror 210 is , which can be deformed by driving the actuator device 220 in a targeted manner. This allows for correction of optical aberrations and increases the resolution of the lithography process. can.

[0114] In an advantageous embodiment, the sensor element 224 actually detects the desired deformation. , and therefore the drive voltage Vs can be adjusted by evaluating the sensor signal Ss. Therefore, the actuator element 222 operates under closed-loop control. The control is performed individually for each actuator device 220. , only one actuator device 220, only one driving voltage VS, and one measurement The AC voltage VM and one sensor signal SS are shown.

[0115] The projection system 200 or the beam forming and illumination system 102 may also be driven by the assigned actuator device. A further mirror 210 with a vice 220 may be provided.

[0116] FIG. 14B shows a schematic diagram of a DUV lithography apparatus 100B. The apparatus 100B includes a beam forming and illumination system 102 and an optical system 2, here designed as a projection system. 00, where DUV stands for "deep ultraviolet" and 3 14A. As already explained with reference to FIG. 14A, the wavelength of the working light is between 0 nm and 250 nm. Additionally, the beam forming and illumination system 102 and the projection system 200 may be disposed within a vacuum housing. and / or may be enclosed by a machine room with corresponding drives. do.

[0117] The DUV lithography apparatus 100B includes a DUV light source 106B. For example, ArF excimer laser emitting radiation 108B in the DUV region at 193 nm is used as B. A laser may be provided.

[0118] The beam forming and illumination system 102 shown in FIG. 14B converts the DUV radiation beam 108B into a photomatrix. The photomask 120 is formed as a transmissive optical element, and the system 102, The photomask 120 can be projected onto the wafer using a projection system 200. The structure to be imaged is on a wafer such as wafer 124 .

[0119] Projection system 200 includes a plurality of lens elements 110 that image photomask 120 onto wafer 124. 28 and / or mirror 130. In this case, the individual lens elements of projection system 104 128 and / or mirror 130 may be arranged symmetrically with respect to the optical axis 126 of the projection system 200. The lens element 128 and the mirror 13 of the DUV lithography apparatus 100B can be It should be noted that the number of 0's is not limited to the number shown. The number of mirrors 130 may be increased or decreased. , the front side is curved to form a beam.

[0120] The gap between the final lens element 128 and the wafer 124 is a liquid medium having a refractive index >1. The liquid medium 132 can be, for example, high purity water. Such a structure is also called immersion lithography and provides high photolithographic resolution. The medium 132 may also be referred to as an immersion liquid.

[0121] The projection system 200 further comprises a further mirror 210, behind which an actuator The actuator device 220 is disposed in the 3. Without limiting the generality, Only one actuator device 220 is shown. However, preferably multiple actuators are used. There are actuator devices 220, each of which can be controlled in open loop and / or closed loop. It goes without saying that the actuator devices 220 can be individually controlled by group control. , including assigned actuator elements 222 and assigned sensor elements 224. The drive unit 226 drives an actuator to generate each of the sensor signals SS. The element 222 is driven by a driving voltage VS, and a measurement AC voltage VM is applied to the sensor element 224. It is set as follows.

[0122] 14B also shows a predetermined mechanical action to be achieved by the actuator element 222. Target stress σ s It has been shown that the mechanical target stress σ is specified externally. s For example, , ascertained by the control computer based on the target deformation to be achieved of the mirror 210. The front side of the mirror 210 is deformed in a targeted manner to allow the lithography process to proceed. To increase the resolution, optical aberrations can be corrected.

[0123] In an advantageous embodiment, the sensor element actually detects the desired deformation and Therefore, the drive voltage VS can be adjusted by evaluating the sensor signal SS. Thus, the actuator element 222 is operated under closed-loop control. Control is performed individually for each actuator device 220. Only one actuator device 220, only one driving voltage VS, and only one measuring AC The voltage VM and one sensor signal are shown.

[0124] The projection system 200 or the beam forming and illumination system 102 may also be driven by the assigned actuator device. A further mirror 210 with a vice 220 may be provided.

[0125] FIG. 15 shows the mirror 210 (see FIGS. 1 to 8, or 14A and 14B) of the optical system 200. By deforming the mirror surface 214 (see FIGS. 1-8) as desired, for example, 1 is a schematic diagram of an exemplary embodiment of a method for correcting aberrations in an optical system 200. A block diagram is shown.

[0126] In a first step S1, at least one actuator element 222 (see FIGS. 2 to 8) is or 13) to a particular deformation of the mirror surface 214 (see Figs. 2-8 or 10-13) As a result, the drive voltage VS (see FIGS. 2 to 8 or 10 to 13) is used. This generates mechanical stress in the actuator element 222. This mechanical stress The force is transmitted to the mirror body 212 (see FIGS. 1-8) and causes local deformation of the mirror surface 214. Glass.

[0127] In the second step S2, the sensor signal SS (see Figs. 2 to 8 or 13) is The output is provided by one sensor element 224 (see FIGS. 2 to 8 or 13). To do this, a measurement AC voltage VM is applied to the sensor element 224 as described above.

[0128] In a third step S3, the deformation of the sensor element 224 is detected in response to the detected sensor signal SS. From this, it can be determined that the deformation of the mirror surface 214 has been achieved. do.

[0129] In an optional fourth step S4, the mirror surface 214 is adjusted so that a predetermined deformation is achieved. For this purpose, for example, a predetermined deformation is achieved by controlling the driving voltage VS in a closed loop. This allows us to determine that the driving voltage VS must be higher to achieve a given deformation. Indicates whether it needs to be higher or lower.

[0130] Although the present invention has been described with reference to exemplary embodiments, it can be varied in many ways. In particular, many of the physical variables described are interchangeable with other variables. Instead of mechanical stress, it can also refer to force or mechanical strain or deformation. The signal is a series of dielectric constants and impedances that can be converted into each other if the material parameters are known. It can be said that this depends on the impedance, polarization, capacitance, etc.

[0131] In particular, according to the present invention, for an actuator element in an actuator device , a large number of possible placements of the sensor elements are given, where different positions are suitable for a particular application. Furthermore, it is possible to combine different arrangements in one actuator element. By combining these, detection accuracy can be improved.

[0132] Furthermore, the closed loop control circuit for controlling the drive voltage does not limit the invention from being implemented in any particular manner. The present invention can be implemented or realized in various ways without being limited to the above. [Explanation of symbols]

[0133] 1 Function curve 2 Function curves 3 Function curves 4 Function curves 5 Function curves 100A EUV lithography equipment 100B DUV lithography equipment 102 Beam forming and lighting system 106A EUV light source 106B DUV light source 108A EUV radiation beam 108B DUV radiation beam 110 Mirror 112 Mirror 114 Mirror 116 Mirror 118 Mirror 120 Photomask 122 Mirror 124 wafers 126 Optical axis 128 lens elements 130 Mirror 132 Medium 200 Optical system 210 Mirror 212 Mirror body 214 Mirror Surface 216 Mirror carrier 220 Actuator Device 221 layers 222 Actuator element 223 Operating direction 224 Sensor Element 226 Drive Unit 230 Confirmation Unit A1 Anode A2 anode A3 Anode An anode K1 cathode K2 cathode K3 cathode Kn cathode L1 layer L2 layer L3 layer Ln layer LS light source MX Matrix M1 mirror M2 mirror M3 mirror M4 mirror M5 mirror S1 Method Steps S2 Method Steps S3 Method Steps S4 Method Steps SS sensor signal VM measurement AC voltage VS driving voltage χ dielectric constant σ mechanical stress σ s Mechanical stress

Claims

1. An optical system (200) comprising a mirror body (212) and a mirror surface (214). At least one mirror (210) and a mirror surface (214) for deforming the mirror surface (214). At least one actuator device (220) coupled to the mirror body (212) In an optical system (200) having the actuator device (220), The mirror surface (214) is deformed in response to an electrical driving voltage (Vs). - at least one electrostrictive actuator element for generating mechanical stress in the body (212); (222) and At least one electrostrictive sensor element (224), The at least one sensor element (224) outputs a sensor signal (SS) in response to deformation. is disposed directly adjacent to said actuator element (222) and / or in front of said actuator element (222). At least the active element is provided on the side of the mirror body (212) opposite to the mirror surface (214). a capacitor element (222) separated from the mirror body (212); and / or generated at least in part by said actuator element (222) The mirror body (212) is configured to transmit the mechanical stress applied thereto. and at least one electrostrictive sensor element (224) disposed on the sensor; The actuator device (220) is configured such that the mirror surface (214) is The drive element (222) is deformable in response to the electrical drive voltage (Vs). An optical system (200) coupled to the mirror body (212).

2. 2. The optical system of claim 1, wherein the mirror body (212) is configured to receive a predetermined mechanical stress. The sensor signal (SS) output by the sensor element (224) is a control circuit for controlling the drive voltage (VS) for the actuator element (222) in response to The optical system further comprises a loop control unit.

3. 3. The optical system according to claim 1, wherein the at least one actuator element (222) and said at least one sensor element (224) are monolithically manufactured. Optical system.

4. 4. The optical system according to claim 1, wherein the at least one actuator The data element (222) and the at least one sensor element (224) are A body (212) is disposed on the mirror (210) on the side opposite the mirror surface (214). The optical system is integrated into the layer (221).

5. 5. The optical system according to claim 1, wherein the at least one sensor element (224) at least partially controls said at least one actuator element (222) ) and the mirror body (212) in a direction along the surface normal of the mirror surface (214). The optical system is placed.

6. 6. The optical system according to claim 1, wherein the at least one actuator The data element (222) and the at least one sensor element (224) are each made of an electrostrictive material 1. An optical system comprising at least one layer (L1, . . . , Ln) made of

7. 7. The optical system according to claim 6, wherein the at least one actuator element (222) ) comprises a plurality of layers (L1, ..., Ln) made of an electrostrictive material, and each layer (L1, ... , Ln) are assigned cathodes (K1 to Kn) and assigned anodes (A 1 to An), and can be driven by each driving voltage (VS).

8. 8. The optical system according to claim 6 or 7, wherein the at least one actuator element (222) and said at least one sensor element (224) are made up of at least two layers ( , Ln) (L1, ..., Ln).

9. 9. The optical system according to claim 1, wherein the actuator device (2 20) comprises at least two sensor elements (224), The material compositions of the electrostrictive materials of the at least two sensor elements (224) are different, ) each configured to output a sensor signal (SS).

10. 10. The optical system according to claim 9, wherein the at least two sensor elements (224) The temperature inside the mirror body (212) is confirmed according to the sensor signal (SS) output by the The optical system is provided with a verification unit (230).

11. 11. The optical system according to claim 9 or 10, wherein the measurement unit measures AC voltage (V) to the at least two sensor elements (224) to generate the sensor signal (SS). The frequency of the measuring AC voltage (VM) is set to be different from that of the different sensor elements (22 4) Different optical system.

12. The optical system according to any one of claims 1 to 11, wherein the actuator device ( 220) includes a plurality of M actuator elements (222) and a plurality of N sensor elements (224), wherein N and M are integers, and said actuator elements (222) and The sensor elements (224) are arranged alternately.

13. The optical system according to any one of claims 2 to 12, wherein the actuator device ( 220) outputs a sensor signal (S) from the at least one sensor element (224). S) based on the calibration measurements to determine the achieved change in the mirror surface (214). an allocation unit configured to allocate a shape to the closed-loop control unit; , the drive voltage ( VS).

14. 14. The optical system according to claim 1, wherein a plurality of actuator devices are provided. (220) is disposed on the at least one mirror (210), and the plurality of actuators Each of the data devices (220) is individually controllable.

15. A lithographic apparatus (1) comprising an optical system (200) according to any one of claims 1 to 13. 10A、100B)。

16. An optical system (200) of a mirror (210) coupled to an actuator device (220) The mirror (210) comprises a mirror body (212) and a mirror surface (214), wherein the actuator device (220) comprises: The mirror surface (214) is deformed in response to an electrical driving voltage (Vs). - at least one electrostrictive actuator element for generating mechanical stress in the body (212); (222) and At least one electrostrictive sensor element (224), The at least one sensor element (224) outputs a sensor signal (SS) in response to deformation. is disposed directly adjacent to said actuator element (222) and / or in front of said actuator element (222). At least the active element is provided on the side of the mirror body (212) opposite to the mirror surface (214). a capacitor element (222) separated from the mirror body (212); and / or generated at least in part by said actuator element (222) The mirror body (212) is configured to transmit the mechanical stress applied thereto. and at least one electrostrictive sensor element (224) disposed on the sensor; The actuator device (220) is configured to allow the mirror surface (214) to be electrically driven. Use, coupled to said mirror body (212) so as to be deformed in response to a voltage (VS).

17. A method of operating an optical system (200), the optical system (200) comprising: a mirror (210) having a mirror surface (212) and a mirror surface (214); an actuator device (212) coupled to the mirror body (212) for deforming the mirror body (212); 220), The electrostrictive actuator element (222) of the actuator device (220) is electrically a step of driving the mirror body (212) with a constant driving voltage (VS), a mechanical stress is generated in the mirror surface (214) to deform the mirror surface (214); At least one electrostrictive sensor element (224) of said actuator device (220) ) to detect a sensor signal (SS) according to the deformation of the sensor element (224). wherein the at least one sensor element (224) is connected to the actuator element and / or the mirror body (212) is disposed directly adjacent to the mirror body (222). At least the actuator element (222) on the side opposite to the mirror surface (214) Therefore, it is arranged separately from the mirror body (212) and / or at least and partially before the mechanical stress generated by the actuator element (222). configured and arranged to transmit to the mirror body (212); The deformation of the mirror surface (214) is confirmed in response to the detected sensor signal (SS). The method includes the steps of:

Images