Optical assembly, method for deforming optical elements, and projection exposure system

Abstract

The invention relates to an optical assembly (1) comprising an optical element (2) for influencing a beam path of a projection exposure apparatus (100, 200) and an actuator device (6) for deforming the optical element (2). The actuator device (6) comprises at least one photostrictive component (7) and at least one light source (8). To deform the optical element (2), the photostrictive component (7) is mechanically coupled to the optical element (2) for transmitting a tensile and / or compressive force. The light source (8) is configured for targeted illumination of the photostrictive component (7) for inducing a tensile and / or compressive force in the photostrictive component (7).

Description

Technical Field

[0001] This application claims the priority of German Patent Application No. 10 2021 201 689.8, the content of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to various deformation forms of an optical assembly including an optical element that affects the beam path of a projection exposure apparatus and an actuator device that deforms the optical element.

[0003] The present invention further relates to various deformation forms of a method for deforming an optical element of a projection exposure apparatus and a computer program product having program code means for executing the method.

[0004] The present invention further relates to a microlithography projection exposure apparatus including an illumination system having a radiation source, an illumination optical unit, and a projection optical unit.

Background Art

[0005] A projection exposure apparatus or a lithography apparatus is used for manufacturing high-precision integrated circuits. At this time, light from a radiation source is directed toward a wafer to be exposed by an optical element such as a mirror and / or a lens element. The arrangement, position, and shape of the optical element contribute decisively to the quality of the exposure in this case.

[0006] Due to the progress of miniaturization of semiconductor circuits, the requirements imposed on both the resolution and accuracy of projection exposure apparatuses are becoming increasingly stringent. Correspondingly, particularly strict requirements are imposed on the optical elements and the operation of the optical elements.

[0007] EUV ("extreme ultraviolet") projection lithography systems have been used for many years, particularly to achieve high resolution. Because almost all media absorb EUV radiation highly, EUV optical units must typically be pure mirror systems and placed in a vacuum. However, in practice, ideal reflection of EUV radiation cannot be achieved, and especially at high radiation output levels, a significant amount of energy accumulates in the mirror optical unit, which can cause heating and deformation. This ultimately leads to optical aberrations or imaging errors.

[0008] To improve the imaging accuracy of projection lithography systems, experience has shown that the imaging errors within the system can be corrected by using movable components to deform the optical elements to the desired shape. For this purpose, piezoelectric elements are generally fixed to the optical elements. In principle, the operation of the piezoelectric element can set the profile of the optical elements, such as a mirror, and consequently correct the entire optical system.

[0009] Typically, the piezoelectric element must be bonded to the back of the mirror to be deformed. However, this has the drawback that the deformation caused by the piezoelectric element is relatively far from the optically active front side of the mirror, mainly because the mirror must have a certain thickness to be sufficiently thermally and mechanically stable.

[0010] Another drawback is that power supply lines or control lines must be incorporated into the optical assembly, and in some cases even into the optical element itself, for the piezoelectric element to operate.

[0011] General Patent Document 1 proposes using polymer materials to deform a mirror, and if necessary, by laser irradiation, with the intention of transmitting this deformation to the reflective surface of an optical element. In this way, non-contact deformation should be possible. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] U.S. Patent Application Publication No. 2019 / 137755 [Overview of the project] [Problems that the invention aims to solve]

[0013] In view of known prior art, a primary object of the present invention is to provide a particularly advantageous optical assembly that facilitates the deformation of optical elements in a projection exposure apparatus with high precision and preferably a simple technical design.

[0014] The present invention also has the primary objective of providing a particularly advantageous alternative deformation form for a method of deforming an optical element in a projection exposure apparatus, enabling deformation of the optical element with high precision and preferably with a simple technical design. Finally, an objective of the present invention is also to provide an advantageous computer program product for carrying out the above method.

[0015] Furthermore, an object of the present invention is to provide a microlithography projection exposure apparatus comprising at least one optical assembly having a highly deformable optical element for correcting imaging errors. [Means for solving the problem]

[0016] This objective is achieved by each independent claim with respect to optical assemblies, alternative modifications of deformation methods, computer program products, and projection exposure apparatus. Dependent claims and the features described below relate to advantageous embodiments and modifications of the present invention.

[0017] An optical assembly is provided, comprising an optical element that affects the beam path of a projection exposure apparatus, and one or more actuator devices that deform the optical element.

[0018] As a result of the actuator device, the optical element may be elastically deformable or at least substantially reversibly deformable. It is preferable that the deformation of the optical element be carried out without hysteresis. “Deformation” should be understood to specifically mean deformation of the material of the optical element that may cause, for example, a change in the length of each part of the material of the optical element or a surface deformation of each part of the material of the optical element.

[0019] The optical element is preferably a mirror. The mirror may have a substantially flat or planar mirror surface, but it may also have a fully or partially curved surface, particularly a convex or concave surface. However, in principle, the optical element may be any element suitable for influencing the beam path, such as a lens element or reticle, possibly an entire assembly such as a projection optical unit, or a structure such as a mounting frame or wafer holder.

[0020] For the sake of perfection, it should be noted that, in principle, it is possible to provide multiple actuator devices for deforming the optical elements.

[0021] Using the deformation of an optical element according to the present invention, imaging errors caused, for example, by inaccuracies or tolerances in the manufacture of the optical element, or by undesirable deformation of the optical element, can be corrected. For example, an optical element may be heated during operation and consequently deformed. However, heating is not the only possible cause of undesirable deformation. For example, mechanical stress in the reflective layer or body of the optical element may also be involved. Mechanical stress in the body of the optical element may occur, for example, when the body is compressed by an electron beam for smoothing ("ICET"). It is advantageous that the aforementioned inaccuracies and / or deformations can be corrected or at least reduced by the deformation of the optical element according to the present invention. In principle, any imaging error of any optical element can be corrected by the deformation according to the present invention.

[0022] According to the present invention, in order to deform an optical element, the actuator device has at least one optical strain component mechanically coupled to the optical element to transmit tensile and / or compressive forces.

[0023] When exposed to light in a specific wavelength range, a photoelastic material or component deforms. This phenomenon is referred to as "photoelasticity". Photoelasticity should be distinguished from normal thermal deformation and is a combination of the photoelectric effect and the piezoelectric effect.

[0024] According to the present invention, an actuator device has at least one light source configured to illuminate a photoelastic component as intended in order to induce or evoke a tensile force and / or a compressive force in the photoelastic component.

[0025] It is advantageous that non-contact deformation can be initiated with an optical element by excitation of the photoelastic component according to the present invention by the light source. It is also not necessary to provide electrical wires for controlling the actuator device.

[0026] The inventors have found that, surprisingly, an actuator amplitude of an order suitable for deformation of an optical element of a projection exposure apparatus can be achieved by the solution according to the present invention.

[0027] According to the present invention, an optical element shall have an optically active front side with a reflective layer for influencing the beam path from a radiation source and a back side opposite to the front side.

[0028] Similarly, the back side of the optical element can also be designed to be optically active in some cases. However, it is preferred that the back side is not optically active or is not used at least for influencing the beam path from the radiation source.

[0029] The back side of the optical element can extend in a plane parallel or at least substantially parallel to the front side, especially in the non-deformed basic state of the optical element. The front side and / or the back side can also be curved, especially concave or convex.

[0030] The optically active front side of the optical element is preferably designed as a mirror surface that reflects or influences the beam path of DUV ("deep ultraviolet") radiation, and more preferably influences the beam path of EUV radiation.

[0031] The front side preferably has a reflective layer that affects the beam path from the radiation source. The reflective layer may be a metallic layer that reflects EUV radiation in particular. The reflective layer is preferably materially bonded to the front side of the optical element and can be bonded to the optical element by, for example, adhesion, vapor deposition, additional coating, or some other method. However, in principle, the optical element may consist entirely of a reflective layer.

[0032] As part of the overall concept of the present invention, various alternative configurations of the arrangement of optical distortion components and light sources are proposed below, which have surprisingly proven to be alternatives to known prior art particularly well suited to enabling deformation of optical elements with high precision and preferably with a simple technical design. In this regard, the various independent patent claims represent alternative solutions to the unified problem of the present invention.

[0033] According to a first variant of the present invention, at least one of the optical distortion components is positioned adjacent to the reflective layer on the front side of the optical element and / or mechanically connected to the back side of the optical element.

[0034] According to a second variant of the present invention, at least one light source is fixed to the back of the optical element, and / or at least one optical distortion component is positioned on the optical element between the reflective layer and the back of the optical element, and at least one light source is positioned on the optical element between the optical distortion component and the back of the optical element.

[0035] According to a third variant of the present invention, at least one optical distortion component is illuminated using a plurality of independently controllable light sources.

[0036] According to an advanced version of the present invention, the optical element may have a body that extends from the back side of the optical element to the reflective layer.

[0037] The main body is preferably made of a material that is transparent to light from a light source, or at least partially transparent, or sufficiently transparent to the operation of the actuator device. For example, the main body may be made of glass.

[0038] In particular, if the main body is made of a material that is transparent to light from the light source, the operation of the optical distortion component or the illumination of the optical distortion component can be made especially simple, and the placement of the optical distortion component on or within the optical element can be done with a great degree of freedom.

[0039] However, in principle, the main body may be formed from a material that is not transparent to light from a light source.

[0040] At this point, it should be noted that in special cases, the reflective layer can also be made transparent to light from the light source (however, this is generally not the case).

[0041] According to an advanced version of the present invention, at least one of the optical distortion components may be positioned on the optical element between the reflective layer and the back side of the optical element.

[0042] The placement of optical distortion components in an optical element, particularly between the reflective layer and the back side of the optical element, and especially preferably directly adjacent to the reflective layer, can lead to particularly advantageous target deformations of the optical element. By placing the actuator device directly adjacent, it can particularly directly affect the optically active front side of the optical element. In this case, the body is preferably made of a material that is transparent to light from a light source, as already proposed above.

[0043] In principle, the optical distortion component can also be placed on or within the optical element at other locations, either as an alternative or as an addition.

[0044] In an advanced form of the present invention, for example, at least one of the optical distortion components may be arranged on the front side of the optical element, preferably adjacent to the reflective layer.

[0045] Therefore, the optical distortion component can be placed in a region of the optically active front side of the optical element that is not related to influencing the beam path. Consequently, the function of the optical element that affects the beam path from the light source is not affected by the actuator device.

[0046] While deformation can also be introduced into optical elements in this way, it is less specific and affects longer wavelengths than directly influencing them by placing an optical distortion component behind the reflective layer.

[0047] Note that if this region of the reflective layer is in a part of the optical element that is not used by the beam path, or if the behavior of the optical distortion component to radiation from the radiation source is passive, for example, transparent, the optical distortion component may also be placed on the reflective layer on the front side of the optical element.

[0048] In one configuration of the present invention, at least one of the optical distortion components may be arranged on one or more sides of the optical element, either as an alternative or as an addition.

[0049] Placing optical distortion components on the sides and / or sides of the front of an optical element can be advantageous, for example, to counteract excessive deformation of the edges of the optical element. Naturally, the edges of a mirror deform more when heated than the center of the mirror, which can lead to particularly significant imaging errors, especially when the peripheral region of the optical element is used to influence the beam path. The arrangement according to the present invention can counteract this.

[0050] In an advanced form of the present invention, at least one light source may be positioned on the optical element between the optical distortion component and the back side of the optical element.

[0051] The light source can be placed, for example, in a corresponding recess of the optical element or in the body of the optical element. However, the light source may be manufactured with a common layer structure with the optical element or the body of the optical element. It is preferable to ensure that the light source is sufficiently accessible to contact the back side of the optical element.

[0052] The arrangement of light sources in an optical element may be particularly advantageous when at least one optical distortion component is located between the reflective layer and the back of the optical element, on the front of the optical element, and / or on the side of the optical element.

[0053] In an advantageous development of the present invention, at least one of the optical distortion components may be mechanically connected to the back side of the optical element.

[0054] The arrangement of optical distortion components on the back side of an optical element may be advantageous, for example, when introducing longer wavelength deformations, such as global modes, into the optical element. In this case, the optical element or the body of the optical element can act on mechanical deformation, like a mechanical low-pass filter.

[0055] In this case, it is preferable that the optical strain component be directly attached to the back of the optical element. However, as an alternative, for example, when longer wavelength mechanical deformation is applied, the optical strain component may be indirectly connected to the optical element via an intermediate element attached to the back of the optical element. Thus, the intermediate element can act as a compensating plate. Consequently, deformation of the actuator device may first directly affect the intermediate element and then be transmitted to the optical element via the intermediate element.

[0056] Depending on the application, those skilled in the art may or may not provide an intermediate element, and may also change the thickness and elasticity or material properties of the body of the intermediate element and / or optical element as needed.

[0057] Furthermore, the intermediate element itself can be attached to the optical element only indirectly via spacer elements or spacer struts distributed along the back side of the optical element. The influence of the optical distortion component on the optical element via the intermediate element can, in some cases, be further optimized by using spacer elements or spacer struts, for example, by changing their geometric shape and / or material properties.

[0058] Similarly, in some cases, the optical distortion component may be positioned between the back of the optical element and a reference body spaced apart from the optical element, with one side mechanically coupled to the back of the optical element and the other side to the reference body. The reference body may be, in particular, a mount for the optical element, a mounting frame for the optical element (e.g., a mounting frame for an optical unit or test stand), or a housing component for the optical element. Typically, the reference body is statically coupled to the surrounding components.

[0059] The reference body may be attached to the optical element or intermediate element via support units or support struts distributed along the back side of the optical element. In this case, the optical distortion components may be positioned between the individual support units or support struts.

[0060] The optical strain component is preferably materially bonded to the optical element, particularly to the back side of the optical element (and / or to the intermediate element and / or reference body). In principle, the optical strain component can be connected to the optical element, intermediate element, and / or reference body by any desired method, for example, by friction fitting or gimbal fitting. However, material bonding by means of adhesion or vapor deposition has been found to be particularly suitable. The optical strain component can also be integrally formed with the optical element, intermediate body, and / or reference body by, for example, additive manufacturing techniques.

[0061] In an advanced form of the present invention, at least one of the light sources may be fixed to the back side of the optical element.

[0062] In a preferred configuration of the present invention, at least one of the light sources may be positioned on the back side of the optical element and aligned with the front side of the optical element to illuminate the optical distortion component. This configuration is particularly advantageous because the light source can be positioned at virtually any desired distance from the optical element. Thus, the existing optical system is virtually unaffected by the actuator device. Furthermore, in this case, control of the light source and, optionally, heat dissipation can be performed in a particularly simple manner.

[0063] In an advantageous development of the present invention, at least one optical distortion component may be aligned parallel to the optical element, for example, parallel to the back and / or front side of the optical element.

[0064] However, in principle, it is also possible to arrange optical distortion components with parallel spread deviations. However, parallel spread has been found to be particularly appropriate and can be implemented relatively easily from a technical standpoint.

[0065] In an advanced form of the present invention, the actuator device may have exactly one of the aforementioned optical strain components designed as a continuous layer of material.

[0066] The target deformation of an optical element can be achieved by illuminating individual parts or regions of the optical distortion component.

[0067] It is preferable that a uniform material layer is provided. In this case, the technical design of the actuator device may be particularly simple.

[0068] However, in an advanced form of the present invention, multiple optical distortion components can be selectively distributed along an optical element.

[0069] This method also makes it easy to set different deformation profiles. Furthermore, selective distribution of optical distortion components allows for the excitation or introduction of deformation into optical elements using a light source with low focusing power.

[0070] In this way, different thicknesses or layer thicknesses can be given to the optical strain component to specify locally different scaling of the deformation amplitude. For example, the deformation in the peripheral region of the optical element can be greater or smaller than that in the central region of the optical element. Therefore, it is preferable that the thickness of the optical strain component placed in the peripheral region be greater than that in the central region.

[0071] In an advantageous development of the present invention, at least one of the optical strain components may be designed as a thin layer with a thickness of, for example, 1 nm to 500 μm, preferably 500 nm to 100 μm.

[0072] An advantage of the optical strain component is that its expansion coefficient can be specified by changing the layer thickness.

[0073] For example, the optical strain component can have a layer thickness of 20 nm to 36 nm. This may already be sufficient to cause the optical strain component to expand or compress without compromising the deformation of the optical element.

[0074] For example, a stroke or actuator amplitude of 1 nm to 5 nm may be sufficient to produce a satisfactory deformation. However, in principle, the given deformation amplitude can be made larger or smaller.

[0075] In an advantageous development of the present invention, at least one of the optical strain components may be made of BiFeO3 ("bismuth ferrite") or PbTiO3 ("lead titanate").

[0076] The reaction time of the aforementioned materials can be made sufficiently short. In particular, the inventors have found that the two aforementioned materials can already produce a sufficient deformation amplitude in sufficiently thin layers, for example, layers of 600 nm to 90 μm, and are therefore suitable for use in projection exposure equipment. In the case of a crystal made of BiFeO3, the coefficient of thermal expansion can be, for example, 0.003%, which corresponds to 326 W / m² when illuminated with light at a wavelength of 365 nm. 2 This means that with this power, a layer approximately 90 μm thick can already achieve a deformation amplitude of 2.7 nm. A thin film made of BiFeO3 exhibits an even significantly higher photodistortion effect with a thermal expansion coefficient of 0.46%, and can already produce a deformation amplitude of 2.7 nm at a layer thickness of 600 nm, because its roughly two-dimensional geometric shape allows for further physical processes to occur in the thin film.

[0077] To further utilize the high effect of the thin or thin film of the optical strain component, in an advantageous embodiment of the present invention, multiple thin layers of the optical strain component may be laminated, preferably separated by each insulating layer. Thus, each individual layer can absorb a portion of the light from the light source, while the remainder can activate the layer below it. In this way, an even larger deformation amplitude can be achieved.

[0078] In principle, optical strain occurs in many different material classes, each potentially suitable for forming at least one optical strain component. To achieve significant, and therefore particularly advantageous, effects within the scope of the present invention, suitable ferroelectric materials (such as ferroelectric ceramics like SbSl crystals or PLZT), chalcogenide glasses (e.g., As2Se3), and / or organic polymers can be provided. These can be designed as thick or thin layers, respectively.

[0079] In one configuration of the present invention, the optical element or at least the body of the optical element may be formed (completely or partially) from an optical distortion component.

[0080] Therefore, the effort required to add or connect optical distortion components to optical elements can be eliminated. One possibility for achieving the aforementioned configuration is, for example, to dope the optical element or body with another component (or some other mixture) to generate the optical distortion component as a whole. This can be done, for example, directly during the manufacture of the optical element (e.g., glass manufacturing).

[0081] In an advanced form of the present invention, at least one of the light sources may be designed as a laser.

[0082] The light source is preferably configured to emit monochromatic light.

[0083] According to an advanced version of the present invention, at least one of the light sources may be configured to emit light having a wavelength of 100 nm to 1000 nm, preferably 200 nm to 800 nm, and particularly preferably 350 nm to 700 nm, for example, 365 nm. However, in principle, it is also possible to provide wavelengths less than 100 nm or greater than 1000 nm.

[0084] The expansion or actuator amplitude of an optical strain component can vary depending on the amount of light absorbed, and therefore especially depending on the wavelength. Different optical strain materials may have different sensitivities to different wavelengths of light.

[0085] In an advantageous development of the present invention, at least one of the light sources may be configurable with respect to the wavelength, intensity, focusing, and / or alignment of the emitted light.

[0086] Thus, the deformation can be set particularly advantageously by the electrical control of at least one light source.

[0087] In an advantageous development of the present invention, at least one of the light sources may have optical devices, particularly one or more lens elements, one or more micromirrors, and / or one or more optical filters (e.g., an LCD unit) to influence the characteristics of the beam path and / or the emitted light.

[0088] For example, if the setting accuracy of the light source is sufficient, it may be possible to use only one light source, or at least a few, for illuminating at least one optical distortion component.

[0089] However, in an advanced form of the present invention, the actuator device may have a plurality of the aforementioned light sources, each independently controllable to illuminate at least one optical distortion component.

[0090] The use of multiple light sources that can be controlled independently of each other is generally preferred.

[0091] According to an advanced form of the present invention, the optical assembly may have a control device that controls at least one light source to illuminate at least one optical distortion component such that a desired deformation occurs in the optical element.

[0092] The control device may take the form of a microprocessor. Instead of a microprocessor, any other device that implements the control device may be provided, such as one or more discrete electrical components arranged on a printed circuit board, a programmable logic controller (PLC), an application-specific integrated circuit (ASIC), or any other programmable circuit, such as a field-programmable gate array (FPGA), a programmable logic array (PLA), and / or a commercially available computer.

[0093] The present invention also relates to a method for deforming an optical element of a projection exposure apparatus. To deform the optical element, at least one light source illuminates the optical distortion component, which is mechanically coupled to the optical element to transmit tensile and / or compressive forces, as intended, in order to induce tensile and / or compressive forces in the optical distortion component. Various advantageous variations of the method are described in claims 20 to 22.

[0094] Therefore, it is proposed to use an optical distortion material to deform the mirror of a projection exposure apparatus, preferably an EUV lithography optical unit, in order to correct the optical surface. Thus, instead of using a piezoelectric element or other actuator to deform the mirror, a mirror that can be deformed by the optical distortion effect can be provided.

[0095] The placement and number of optical distortion components in an optical element can vary as described above and below. The same applies to the number and positioning of light sources that illuminate the optical distortion components and thus manipulate them as intended.

[0096] The present invention further relates to a computer program product having program code means that, when a program is executed on a control device, particularly a control device for the optical assembly described above, executes a method for deforming optical elements as described above and below.

[0097] In particular, the present invention is suitable for use in projection exposure apparatus, as further described later, or generally for use in lithography optical units. However, in principle, the present invention may also be suitable for any desired application in which optical elements are to be deformed, particularly in aerospace and astronomical applications, and military applications.

[0098] The present invention also relates to a microlithography projection exposure apparatus comprising an illumination system having a radiation source, an illumination optical unit, and a projection optical unit. The illumination optical unit and / or projection optical unit comprises at least one optical assembly as described above and below.

[0099] The present invention is particularly suitable for correcting imaging errors in a projection exposure apparatus by deforming the optical elements of an optical assembly.

[0100] The use of the optical distortion component for deforming optical elements according to the present invention is preferable because it is possible to avoid electrical wiring within or adjacent to the optical elements, making it possible to provide a high-precision system that is technically easy to implement and has little impact on the overall system of the projection exposure apparatus.

[0101] The present invention is particularly suitable for use in microlithography DUV projection exposure systems, but especially for use in EUV projection exposure systems. Possible applications of the present invention also relate to immersion lithography.

[0102] Features described in relation to one of the subjects of the present invention, specifically optical assemblies, methods for deforming optical elements, computer program products, and projection exposure apparatus, are advantageously applicable to other subjects of the present invention. Similarly, advantages expressed in relation to one of the subjects of the present invention can be understood to apply to other subjects of the present invention.

[0103] Furthermore, please note that terms such as "equip," "possess," or "include" do not exclude other features or steps. Moreover, words such as "a(n)" or "the" indicating individual steps or features do not exclude multiple features or steps, and vice versa.

[0104] However, in a purely purist embodiment of the present invention, features introduced into the invention using the terms “equipped with,” “having,” or “including” may be considered an exhaustive enumeration. Thus, one or more enumerations of features can be considered exhaustive within the scope of the invention, for example, when considered on a claim-by-claim basis. For example, the present invention may consist only of the features described in claim 1.

[0105] Please note that notations such as "First" or "Second" are primarily used to distinguish between the features of each apparatus or method, and do not necessarily indicate that the features are mutually necessary or related.

[0106] It should be further emphasized that the values ​​and parameters described herein include deviations or variations of ±10%, preferably ±5%, more preferably ±1%, and most preferably ±0.1% or less from each specified value or parameter, provided that these deviations are not excluded in practice of the present invention. The designation of a range by start and end values ​​includes all values ​​and fractional parts included in each designated range, in particular the start and end values ​​and each mean value.

[0107] The present invention also relates to an optical assembly, separate from claim 1, comprising an optical element and an actuator device that affects the optical element, wherein the actuator device comprises at least one optical distortion component and at least one light source, the optical distortion component being mechanically coupled to the optical element to deform, align, and / or position the optical element, and the light source being configured to illuminate the optical distortion component as intended. Further features of claim 1 and its dependent claims and features described herein relate to advantageous embodiments and variations of this optical assembly.

[0108] Exemplary embodiments of the present invention will be described in more detail below with reference to the drawings.

[0109] Each figure shows a preferred exemplary embodiment illustrating the combination of individual features of the present invention. Features of any exemplary embodiment can also be implemented independently of other features of the same exemplary embodiment and can therefore be readily combined by those skilled in the art to form further executable combinations and subcombinations with features of other exemplary embodiments.

[0110] In the diagram, functionally identical elements are given the same reference numeral. [Brief explanation of the drawing]

[0111] [Figure 1] A schematic diagram of the meridian cross-section of an EUV projection lithography system is shown. [Figure 2] A schematic diagram of a DUV projection lithography system is shown. [Figure 3] A schematic diagram of an optical assembly comprising an optical element, an optical distortion component placed within the optical element, and multiple light sources for illuminating the optical distortion component is shown. [Figure 4] A schematic diagram of an optical assembly comprising an optical element, a light-distorting component placed within the optical element, and multiple light sources placed within the optical element to illuminate the light-distorting component is shown. [Figure 5] A schematic diagram of an optical assembly comprising an optical element, an optical distortion component positioned on the front side of the optical element, and multiple light sources for illuminating the optical distortion component is shown. [Figure 6] A schematic diagram of an optical assembly comprising an optical element, a light-distortion component positioned behind the optical element, and multiple light sources illuminating the light-distortion component is shown. [Figure 7] A schematic diagram of an optical assembly comprising an optical element, multiple optical distortion components mechanically coupled to the back of the optical element via an intermediate element, a reference body, and multiple light sources for illuminating the optical distortion components is shown. [Modes for carrying out the invention]

[0112] First, referring to Figure 1, the essential components of the microlithography EUV projection exposure apparatus 100 will be illustrated below. The description of the basic structure of the EUV projection exposure apparatus 100 and its components should not be interpreted as limited here.

[0113] The illumination system 101 of the EUV projection exposure apparatus 100 includes, in addition to the radiation source 102, an illumination optical unit 103 for illuminating the object field of view 104 of the object surface 105. Here, a reticle 106 positioned in the object field of view 104 is exposed. The reticle 106 is held by a reticle holder 107. The reticle holder 107 is displaceable, particularly in the scanning direction, by a reticle displacement drive 108.

[0114] Figure 1 shows a Cartesian xyz coordinate system to aid in the explanation. The x-direction extends perpendicular to the plane of the figure. The y-direction extends horizontally, and the z-direction extends vertically. In Figure 1, the scanning direction extends in the y-direction. The z-direction extends perpendicular to the object plane 10°.

[0115] The EUV projection exposure apparatus 100 includes a projection optical unit 109. The projection optical unit 109 functions to image the object field of view 104 onto the image field of view 110 of the image plane 112. The image plane 111 extends parallel to the object plane 105. Alternatively, angles other than 0° are possible between the object plane 105 and the image plane 111.

[0116] The structure on the reticle 106 is imaged onto the photosensitive layer of the wafer 112, which is positioned in the image field 110 region of the image plane 111. The wafer 112 is held by a wafer holder 113. The wafer holder 113 is displaceable, particularly in the y-direction, by a wafer displacement drive 114. Firstly, the displacement of the reticle 106 by the reticle displacement drive 108 and secondly, the displacement of the wafer 112 by the wafer displacement drive 114 can be performed in synchronous motion.

[0117] Radiation source 102 is an EUV radiation source. Radiation source 102 emits EUV radiation 115, which is also referred to below as the radiation used or illumination radiation. The radiation used 115 has a wavelength in the range of 5 nm to 30 nm. Radiation source 102 may be a plasma source, such as an LPP (laser-generated plasma) source or a GDPP (gas discharge plasma) source. It may also be a synchrotron-based radiation source. Radiation source 102 may be a free electron laser (FEL).

[0118] Illumination radiation 115 emitted from the radiation source 102 is focused by a collector 116. The collector 116 may be a collector having one or more elliptical and / or hyperbolic reflectors. Illumination radiation 115 may be incident on at least one reflector of the collector 116 at an oblique angle (GI), i.e., at an angle of incidence greater than 45°, or at a normal angle (NI), i.e., at an angle of incidence less than 45°. The collector 116 may be structured and / or coated to first optimize its reflectivity for the radiation used 115, and second to suppress external light.

[0119] Downstream of the collector 116, the illumination radiation 115 propagates through the intermediate focal plane 117. The intermediate focal plane 117 may represent the separation between the radiation source module, which has the radiation source 102 and the collector 116, and the illumination optical unit 103.

[0120] The illumination optical unit 103 comprises a deflection mirror 118 and a first facet mirror 119 positioned downstream of it in the beam path. The deflection mirror 118 may be a planar deflection mirror or a mirror having a beam influence effect beyond a pure deflection effect. Alternatively or additionally, the deflection mirror 118 may be in the form of a spectral filter that separates the wavelength of light used by the illumination radiation 115 from external light of wavelengths deviating from it. When the first facet mirror 119 is positioned in the plane of the illumination optical unit 103 that is optically conjugate to the object plane 105 as the field of view plane, it is also referred to as a field of view facet mirror. The first facet mirror 119 includes a number of individual first facets 120, which are also referred to below as field of view facets. Only some of these first facets 120 are illustrated in Figure 1.

[0121] The first facet 120 can be embodied in the form of a macroscopic facet, particularly in the form of a rectangular facet, or in the form of a facet having an arc-shaped peripheral contour or a peripheral contour of a partial circle. The first facet 120 can be embodied as a planar facet, or as a convex or concave curved facet.

[0122] For example, as is known from German Patent Application Publication No. 10 2008 009 600, the first facet 120 itself can also be composed of multiple individual mirrors, particularly multiple micromirrors. The first facet mirror 119 may take the form of a micro-electromechanical system (MEMS system). See German Patent Application Publication No. 10 2008 009 600 for further details.

[0123] The illumination radiation 115 travels horizontally, i.e., in the y-direction, between the collector 116 and the deflection mirror 118.

[0124] In the beam path of the illumination optical unit 103, the second facet mirror 121 is positioned downstream of the first facet mirror 119. When the second facet mirror 121 is positioned on the pupil plane of the illumination optical unit 103, it is also referred to as a pupil facet mirror. The second facet mirror 121 can also be positioned away from the pupil plane of the illumination optical unit 103. In this case, the combination of the first facet mirror 119 and the second facet mirror 121 is also referred to as a specular reflector. Specular reflectors are known from U.S. Patent Application Publication No. 2006 / 0132747, European Patent No. 1614008, and U.S. Patent No. 6,573,978.

[0125] The second facet mirror 121 includes multiple second facets 122. In the case of a pupil facet mirror, the second facets 122 are also referred to as pupil facets.

[0126] Similarly, the second facet 122 may be a macroscopic facet having, for example, a circular, rectangular, or hexagonal boundary, or it may be a facet composed of micromirrors. In this regard, see German Patent Application Publication No. 10 2008 009 600.

[0127] The second facet 122 may have a planar reflective surface or a curved reflective surface that is convex or concave.

[0128] The illumination optical unit 103 consequently forms a dual-faceted system. This basic principle is also referred to as a fly-eye integrator.

[0129] It may be advantageous not to precisely position the second facet mirror 121 on a plane that is optically conjugate to the pupil plane of the projection optical unit 109.

[0130] The individual first facets 120 are imaged into the object field of view 104 using the second facet mirror 121. The second facet mirror 121 is the last beam shaping mirror or, in fact, the final mirror for the illumination radiation 115 in the beam path upstream of the object field of view 104.

[0131] In yet another embodiment (not shown) of the illumination optical unit 103, a transfer optical unit, which contributes particularly to the imaging of the first facet 120 onto the object field of view 104, may be positioned in the beam path between the second facet mirror 121 and the object field of view 104. The transfer optical unit may include strictly one mirror, or two or more mirrors positioned in sequence in the beam path of the illumination optical unit 103. In particular, the transfer optical unit may include one or two mirrors for perpendicular incidence (NI mirrors, "perpendicular incidence" mirrors) and / or one or two mirrors for oblique incidence (GI mirrors, "oblique incidence" mirrors).

[0132] In the embodiment shown in Figure 1, the illumination optical unit 103 has exactly three mirrors downstream of the collector 116, specifically a deflection mirror 118, a field of view facet mirror 119, and a pupil facet mirror 121.

[0133] In yet another embodiment of the illumination optical unit 103, the deflection mirror 118 can be omitted, so the illumination optical unit 103 may have exactly two mirrors downstream of the collector 116, specifically a first facet mirror 119 and a second facet mirror 121.

[0134] The imaging of the first facet 120 onto the object surface 105 by the second facet 122, or by using the second facet 122 and the transfer optics unit, is usually only an approximate image.

[0135] The projection optical unit 109 includes a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the EUV projection exposure apparatus 100.

[0136] In the example shown in Figure 1, the projection optical unit 109 includes six mirrors M1 to M6. Substitution with four, eight, ten, twelve, or any other number of mirrors Mi is equally possible. The second-to-last mirror M5 and the last mirror M6 each have apertures through which illumination radiation 115 passes. The projection system 109 is a double-shielded optical unit. The projection optical unit 109 has an image-side numerical aperture greater than 0.5 and may be greater than 0.6, for example, 0.7 or 0.75.

[0137] The reflective surface of mirror Mi may be in the form of a free-form surface without an axis of rotational symmetry. Alternatively, the reflective surface of mirror Mi can be designed as an aspherical surface with exactly one axis of rotational symmetry of the reflective surface shape. Similar to the mirror of illumination optical unit 103, mirror Mi may have a high-reflectivity coating for illumination radiation 115. These coatings can be designed in particular as multilayer coatings having alternating layers of molybdenum and silicon.

[0138] The projection optical unit 109 has a large object-image offset in the y-direction between the y-coordinate of the center of the object field of view 104 and the y-coordinate of the center of the image field of view 110. In the y-direction, this object-image offset may be approximately the same size as the z-distance between the object plane 105 and the image plane 111.

[0139] In particular, the projection optics unit 109 can have an anamorphic form. Specifically, it has different imaging scales βx and βy in the x and y directions. The two imaging scales βx and βy of the projection optics unit 109 are preferably (βx, βy) = (+ / -0.25, + / -0.125). A positive imaging scale β means imaging without image inversion. A negative sign for the imaging scale β means imaging with image inversion.

[0140] As a result, the projection optical unit 109 is reduced in size in the x-direction, i.e., in the direction perpendicular to the scanning direction, at a ratio of 4:1.

[0141] The projection optical unit 109 reduces its size in the y-direction, i.e., in the scanning direction, at a ratio of 8:1.

[0142] Other imaging scales are also possible. Imaging scales with the same sign and absolute value in the x and y directions, for example, 0.125 or 0.25 absolute value, are also possible.

[0143] The number of intermediate image planes in the x and y directions in the beam path between the object field of view 104 and the image field of view 110 may be the same or different depending on the embodiment of the projection optical unit 109. An example of a projection optical unit with a different number of such intermediate images in the x and y directions is known from U.S. Patent Application Publication No. 2018 / 0074303.

[0144] Each of the second facets 122 is assigned to exactly one of the field facets 120 to form an illumination channel that illuminates the object field of view 104. In particular, this allows illumination according to Köhler's principle. The distant field of view is decomposed into multiple object fields of view 104 using the field facets 120. The field facets 120 generate multiple images at intermediate focal points in the pupil facets 122 each assigned to them.

[0145] Due to the assigned pupil facet 122, the field of view facets 120 overlap and are imaged onto the reticle 106 for the purpose of illuminating the object field of view 104. The illumination of the object field of view 104 is particularly uniform, preferably with a uniformity error of less than 2%. Field of view uniformity can be achieved by overlapping different illumination channels.

[0146] The illumination of the entrance pupil of the projection optical unit 109 can be geometrically defined by the arrangement of the pupil facets. By selecting the illumination channels to guide light, particularly a subset of the pupil facets, the intensity distribution in the entrance pupil of the projection optical unit 109 can be set. This intensity distribution is also referred to as the illumination setting.

[0147] Similarly desirable pupil uniformity in a defined illuminated area of ​​the illumination pupil of the illumination optical unit 103 can be achieved by redistributing the illumination channels.

[0148] Further aspects and details of the illumination of the object field of view 104, particularly the entrance pupil of the projection optical unit 109, will be described below.

[0149] The projection optics unit 109 may have a concentric entrance pupil, which can be made accessible or inaccessible.

[0150] The entrance pupil of the projection optical unit 109 cannot generally be accurately illuminated by the pupil facet mirror 121. When the projection optical unit 109 forms a telecentric image of the center of the pupil facet mirror 121 onto the wafer 112, the aperture rays often do not intersect at a single point. However, it is possible to find a plane where the distance between pairs of aperture rays is minimized. This plane represents the entrance pupil or a real-space plane conjugate to it. In particular, this plane has a finite curvature.

[0151] The projection optics unit 109 may have different entrance pupil positions for the tangential beam path and the sagittal beam path. In this case, an imaging element, particularly an optical component of the transfer optics unit, should be placed between the second facet mirror 121 and the reticle 106. This optical element can be used to account for the differences in position and orientation between the tangential and sagittal entrance pupils.

[0152] In the arrangement of the components of the illumination optical unit 103 shown in Figure 1, the pupil facet mirror 121 is positioned on a plane conjugate to the entrance pupil of the projection optical unit 109. The field of view facet mirror 119 is positioned at an angle with respect to the object plane 105. The first facet mirror 119 is positioned at an angle with respect to the arrangement plane defined by the deflection mirror 118.

[0153] The first facet mirror 119 is positioned so as to be inclined with respect to the arrangement plane defined by the second facet mirror 121.

[0154] Figure 2 shows an exemplary DUV projection lithography apparatus 200. The DUV projection lithography apparatus 200 comprises an illumination system 201, a device known as a reticle stage 202 for housing and precisely positioning a reticle 203 that determines the subsequent structure on a wafer 204, a wafer holder 205 for holding, moving, and precisely positioning the wafer 204, and an imaging device having a plurality of optical elements, in particular a lens element 207, specifically a projection optical unit 206, the lens element 207 being held by a mount 208 in a lens housing 209 of the projection optical unit 206.

[0155] In addition to or as an alternative to the illustrated lens element 207, various refraction, diffraction, and / or reflective optical elements, particularly mirrors, prisms, end plates, etc., can also be provided.

[0156] In the basic functional principle of the DUV projection lithography apparatus 200, the structure introduced into the reticle 203 is imaged onto the wafer 204.

[0157] The illumination device 201 supplies a projection beam 210 in the form of electromagnetic radiation necessary for imaging the reticle 203 onto the wafer 204. The source of this radiation may be a laser, a plasma source, or the like. The radiation is shaped by optical elements in the illumination system 201 so that the projection beam 210 has desired characteristics in terms of diameter, polarization, wavefront shape, etc., when incident on the reticle 203.

[0158] The image of the reticle 203 is generated by the projection beam 210 and transferred from the projection optical unit 206 to the wafer 204 in an appropriate reduced form. In this case, since the reticle 203 and the wafer 204 can be moved synchronously, each region of the reticle 203 is imaged onto the corresponding region of the wafer 204 virtually continuously during the so-called scanning operation.

[0159] The gap between the final lens element 207 and the wafer 204 can be optionally replaced with a liquid medium having a refractive index greater than 1.0. The liquid medium may be, for example, high-purity water. Such a configuration is also called immersion lithography and has high photolithographic resolution.

[0160] The use of the present invention is not limited to use in projection exposure apparatuses 100 and 200, nor to projection exposure apparatuses having the configuration described in particular. The present invention and the following exemplary embodiments should not be understood as being limited to a specific design. The following figures illustrate the present invention in a very schematic manner, merely as an example.

[0161] The target deformation of optical elements 118, 119, 120, 121, 122, Mi, and 207 of projection exposure apparatuses, such as projection exposure apparatuses 100 and 200, can be particularly suitable for correcting the imaging error of the above apparatus. This is the starting point of the present invention.

[0162] Figures 3 to 8 illustrate and very schematically show various exemplary embodiments of the optical assembly 1 according to the present invention. The optical assembly 1 enables target deformation of the optical element 2 to correct imaging errors in projection exposure apparatuses 100, 200, for example.

[0163] As described above, the optical element 2 may be an optical element 2 of the projection exposure apparatus 100, 200 in particular, and more specifically an optical element 2 in the illumination optical unit 103 and / or projection optical units 109, 206 of one of the above-mentioned projection exposure apparatus 100, 200 (or any other projection exposure apparatus).

[0164] In an exemplary embodiment, the optical element 2 is shown as a mirror and has an optically active front side with a reflective layer 3 and a back side 4 opposite to the front side. When incident on the optical element 2, illumination radiation 115 or projection beam 210 is affected by the reflective layer 3. Typically, the optical element 2 has a body 5 extending from the reflective layer 3.

[0165] First, an exemplary first embodiment of the optical assembly 1 according to the present invention will be described with reference to Figure 3.

[0166] In addition to the optical element 2, the optical assembly 1 includes an actuator device 6 for deforming the optical element 2. The actuator device 6 includes at least one optical strain component 7 and at least one light source 8. To deform the optical element 2, the optical strain component 7 is mechanically coupled to the optical element 2 to transmit tensile and / or compressive forces, and the light source 8 is configured to illuminate the optical strain component 7 as intended to induce tensile and / or compressive forces on the optical strain component 7. In the figure, the corresponding light beam 9 is shown as a dashed line.

[0167] Preferably, at least one optical distortion component 7 is aligned parallel to or at least substantially parallel to the optical element 2. However, it is also possible to give it an orthogonal or oblique arrangement, for example. At this point, although the optical distortion component 7 is basically shown as a uniform layer having the same layer thickness in exemplary embodiments, it should be noted that the layer thickness can be varied to achieve different actuator effects in different regions, for example.

[0168] The optical strain component 7 can be designed as a thin layer with a thickness of 1 nm to 500 μm. A thickness of 500 nm to 100 μm is preferred. The layer thickness affects the possible actuator amplitude and can preferably be determined so that an actuator amplitude of 1 nm or more can be obtained.

[0169] At least one optical strain component 7 can, in principle, be formed from any desired optical strain material, such as a ferroelectric material, a polar semiconductor, a nonpolar semiconductor, or an organic polymer. It is particularly preferable that at least one optical strain component 7 be made of BiFeO3 or PbTiO3.

[0170] Preferably, at least one light source 8 is designed to emit monochromatic light. Preferably, at least one light source 8 is also designed to illuminate the optical distortion component 7 as point-like and therefore as focused as possible. In a preferred variant, at least one light source 8 may be in the form of a laser, for example, a laser diode.

[0171] Light source 8 may be configured to emit light with wavelengths of 100 nm to 1000 nm, particularly 350 nm to 700 nm, for example, 365 nm. Different types of photo-straining materials are typically sensitive to different wavelength ranges. It is preferable that the light emitted by at least one light source 8 is compatible with the photo-straining material being used. A wavelength of approximately 365 nm may be particularly advantageous for use with BiFeO3 or PbTiO3.

[0172] At least one light source 8 may be configurable in terms of the wavelength, intensity, focus, and / or alignment of the emitted light. In this way, the deformation of the optical element 2 can be influenced more precisely.

[0173] The actuator device 6 preferably has a single optical strain component 7 designed as a continuous material layer, such as a film or foil, as shown in Figure 3.

[0174] Various advantageous configurations can be provided for the arrangement of the optical distortion component 7 on or within the optical element 2, as shown below. Combinations of the aforementioned configurations are also possible in principle.

[0175] As shown in Figure 3, for example, at least one optical distortion component 7 can be positioned on the optical element 2 beneath the reflective layer 3 of the optical element 2. In this case, the reflective layer 3 or (preferably) the body 5 is transparent to light from the light source 8 in order to allow excitation of the optical distortion component 7. Typically, the body 5 is made of glass in any case and is therefore transparent to the wavelength range mentioned above. As long as the body 5 is transparent, it is advantageous that the optical distortion component 7 can be illuminated on the back side of the optical element 2.

[0176] To illuminate the optical distortion component 7, Figure 3 shows that multiple independently controllable light sources 8 are provided to illuminate the optical distortion component 7 as intended in multiple regions. To control at least one light source 8, a control device 10 can be provided, configured to illuminate at least one optical distortion component 7 by controlling the light source 8 to cause a desired deformation of the optical element 2. To perform an advantageous method of deforming the optical element 2, a corresponding computer program product having program code means can be executed in the control device 10.

[0177] This provides an advantageous option for operating or deforming the optical element 2 without contact. If the focusing is sufficient, the light source 8 can, in principle, be placed at any distance from the optical element 2. Therefore, wiring and / or heat dissipation from the light source 8 may be possible in a particularly simple manner.

[0178] In principle, it is preferable to position the light source 8 at a distance from the optical element 2. However, at least one of the light sources 8 may be directly fixed to the back side 4 of the optical element 2, for example, by friction fitting, shape fitting, or material bonding.

[0179] In addition to or as an alternative to the arrangement shown in Figure 3, other advantageous configurations of the actuator device 6 can also be provided, which are described below. In principle, the present invention should not be understood to be limited to the illustrated exemplary embodiments.

[0180] The exemplary embodiment of the optical assembly 1 shown in Figure 4 generally corresponds to the exemplary embodiment in Figure 3. In this case as well, the optical distortion component 7, embodied as a continuous material layer, is positioned on the optical element 2 between the reflective layer 3 and the back side 4 of the optical element 2. In this way, the front side or the reflective layer 3 can be influenced particularly as intended.

[0181] For simplicity, the control device 10 is not further shown in Figures 4 to 7.

[0182] Unlike the arrangement of the light source 8 shown in Figure 3, the light source 8 in Figure 4 is not positioned away from the optical element 2, but is embedded in the optical element 2. For this purpose, the optical element 2 may be provided with corresponding recesses, for example, extending from the back side 4 into the optical element 2. It is preferable that the light source 8 is housed in the optical element 2 such that there is still a favorable possibility of contact from the back side 4 of the optical element 2.

[0183] Figure 5 shows yet another exemplary embodiment of the optical assembly 1, in which at least one of the optical distortion components 7 is positioned adjacent to the reflective layer 3 on the front side of the optical element 2. In this case as well, the optical distortion component 7 can be illuminated from the back side 4 of the optical element 2 as shown. However, alternatively or additionally, illumination can also be performed from the front or side of the optical element 2.

[0184] An alternative or additional modification may involve the mechanical attachment of one or more optical distortion components 7 to the side of the optical element, as shown by the dashed line in Figure 5.

[0185] The mechanical coupling shown in Figure 5 between at least one optical distortion component 7 and the optical element 2 provides, for example, very good suppression of deformation of the optical element 2 in the peripheral region and / or can introduce long-wavelength deformation to the optical element 2.

[0186] Another exemplary embodiment of the advantageous optical assembly 1 is shown in Figure 6. At least one optical distortion component 7 is mechanically connected, in particular directly, to the back side 4 of the optical element 2. The optical distortion component 7 can be, for example, bonded to the back side 4 of the optical element 2 or deposited on the back side of the optical element 2. In principle, any mounting technique can be provided. In this case, it is not necessarily required that the body 5 and / or reflective layer 3 transmit light from the light source 8 in order to illuminate the optical distortion component 7.

[0187] Figure 6 also shows another possibility for illuminating the optical distortion component 7 with a single light source 8 (or a few light sources 8). The light source 8 has additional optical devices 11, such as one or more lens elements, one or more micromirrors, and / or one or more optical filters, to influence the beam path and / or characteristics of the emitted light. The optical devices 11 are only schematically shown as black boxes in Figure 6. Because the beam path from the light source 8 can be influenced, multiple regions of at least one optical distortion component 7 can be illuminated (possibly with different intensities and / or wavelengths) without necessarily providing multiple light sources 8 for this purpose.

[0188] The exemplary embodiment shown in Figure 7 demonstrates that even significantly more complex arrangements of the optical element 2 and actuator device 6 can be provided within the scope of the present invention.

[0189] As shown in Figure 7, the optical distortion component 7 can be indirectly connected to the reflective layer 3 of the optical element 2. For this purpose, an intermediate layer 12 can be provided between at least one optical distortion component 7 and the reflective layer 3. The optical distortion component 7 can be directly attached to the intermediate layer 12, and the intermediate layer 12 can be further attached directly or indirectly to the reflective layer 3. In the exemplary embodiment of Figure 7, an optional spacer strut 13 is provided between the intermediate layer 12 and the reflective layer 3 to enable more targeted force transmission.

[0190] At least one optical distortion component 7 can be placed between the main body 5 and the reflective layer 3 of the optical element 2, and can be directly connected to the main body 5, for example. Finally, the other side of the optical distortion component 7 can be connected to the back side of the reflective layer 3 of the optical element 2, for example, via the intermediate layer 12 shown in the figure. The main body 5 can be connected to the reflective layer 3, for example, via individual support struts 14, or to the intermediate layer 12 as shown in the figure.

[0191] In the modified form of the present invention shown in Figure 7, it is preferable that the main body 5 is designed to be transparent to light from the light source 8.

[0192] Similarly, as shown in Figure 7, multiple optical strain components 7 can be selectively distributed and arranged along the optical element 2, for example, between the support struts 14. However, in principle, a configuration of the optical strain component 7 as a single continuous material layer is preferable.

Claims

1. An optical assembly (1) comprising an optical element (2) that affects the beam path of a projection exposure apparatus (100, 200) and an actuator device (6) that deforms the optical element (2), wherein the actuator device (6) includes at least one optical strain component (7) and at least one light source (8), wherein, in order to deform the optical element (2), the optical strain component (7) is mechanically coupled to the optical element (2) to transmit tensile and / or compressive forces, the light source (8) is configured to illuminate the optical strain component (7) as intended to induce tensile and / or compressive forces on the optical strain component (7), and the optical element (2) has an optically active front side having a reflective layer (3) for affecting the beam path from a radiation source (102) and a back side (4) opposite to the front side, in the optical assembly (1), a) At least one of the light sources (8) is fixed to the back side (4) of the optical element (2), and / or b) At least one of the optical distortion components (7) is positioned on the optical element (2) between the reflective layer (3) and the back side (4) of the optical element (2), and at least one of the light sources (8) is positioned on the optical element (2) between the optical distortion component (7) and the back side (4) of the optical element (2). An optical assembly characterized by the following features.

2. The optical assembly (1) according to claim 1, wherein the optical element (2) has a body (5) that extends from the back side (4) of the optical element (2) to the reflective layer (3) and is formed of a material that is transparent or at least partially transparent to light from the light source (8).

3. An optical assembly (1) according to claim 1 or 2, characterized in that at least one of the optical distortion components (7) is disposed on the optical element (2) between the reflective layer (3) and the back side (4) of the optical element (2).

4. An optical assembly (1) according to any one of claims 1 to 3, characterized in that at least one of the optical distortion components (7) is arranged adjacent to the reflective layer (3) on the front side of the optical element (2).

5. The optical assembly (1) according to claim 3 or 4, wherein at least one of the light sources (8) is positioned on the optical element (2) between the light distortion component (7) and the back side (4) of the optical element (2).

6. An optical assembly (1) according to any one of claims 1 to 5, characterized in that at least one of the optical distortion components (7) is mechanically connected to the back side (4) of the optical element (2).

7. An optical assembly (1) according to any one of claims 1 to 6, characterized in that the at least one optical distortion component (7) is aligned parallel to the optical element (2).

8. An optical assembly (1) according to any one of claims 1 to 7, characterized by a strictly single optical distortion component (7) designed as a continuous material layer.

9. An optical assembly (1) according to any one of claims 1 to 8, characterized in that at least one of the optical distortion components (7) is designed as a thin layer with a thickness of 1 nm to 500 μm.

10. An optical assembly (1) according to any one of claims 1 to 9, characterized in that at least one of the optical distortion components (7) is made of BiFeO3 or PbTiO3.

11. An optical assembly (1) according to any one of claims 1 to 10, characterized in that at least one of the light sources (8) is designed as a laser to emit monochromatic light.

12. An optical assembly (1) according to any one of claims 1 to 11, characterized in that at least one of the light sources (8) is configured to emit light having a wavelength of 100 nm to 1000 nm.

13. An optical assembly (1) according to any one of claims 1 to 12, characterized in that at least one of the light sources (8) is configurable with respect to the wavelength, intensity, focus, and / or alignment of the emitted light.

14. An optical assembly (1) according to any one of claims 1 to 13, wherein at least one of the light sources (8) has an optical device (11), in particular one or more lens elements, one or more micromirrors, and / or one or more optical filters, to affect the characteristics of the beam path and / or the characteristics of the emitted light.

15. An optical assembly (1) according to any one of claims 1 to 14, comprising a control device (10) for controlling the at least one light source (8) to illuminate the at least one optical distortion component (7) such that a desired deformation occurs in the optical element (2).

16. An optical assembly (1) according to any one of claims 1 to 15, comprising a plurality of independently controllable light sources (8) for illuminating the at least one optical distortion component (7).

17. A method for deforming an optical element (2) of a projection exposure apparatus (100, 200), wherein, in order to deform the optical element (2), at least one light source (8) illuminates the optical distortion component (7), which is mechanically coupled to the optical element (2) to transmit tensile and / or compressive forces, as intended, and the optical element (2) has an optically active front side having a reflective layer (3) for influencing the beam path from a radiation source (102), and a back side (4) opposite to the front side, a) At least one of the light sources (8) is fixed to the back side (4) of the optical element (2), and / or b) At least one of the optical distortion components (7) is positioned on the optical element (2) between the reflective layer (3) and the back side (4) of the optical element (2), and at least one of the light sources (8) is positioned on the optical element (2) between the optical distortion component (7) and the back side (4) of the optical element (2). A method characterized by the following:

18. A computer program product having program code means that, when a program is executed on a control device (10), executes a method for deforming the optical element (2) described in claim 17.

19. A microlithography projection exposure apparatus (100, 200) comprising an illumination system (101, 201) including a radiation source (102), an illumination optical unit (103), and projection optical units (109, 206), wherein the illumination optical unit (103) and / or the projection optical units (109, 206) include at least one optical assembly (1) as described in any one of claims 1 to 16.

Images