Projection exposure equipment with thermal manipulator

Abstract

A microlithography projection exposure apparatus (10, 80) includes a projection lens (26) for projecting the structure of a mask (12) onto a substrate plane (30) by exposure radiation (18), wherein at least one optical element (38, 40, 82) of the projection lens (26) is equipped with a manipulator (M4, M5) configured to selectively input thermal energy into the optical element (38, 40, 82) without significantly heating one of the other optical elements of the projection lens in the process. The projection exposure apparatus (10, 80) further includes a control device (56) configured to control the exposure radiation (18) and to control the manipulator (M4, M5) such that the effect on the optical properties of the projection lens caused by the reduction of thermal energy input to the projection lens (26) due to exposure pauses is at least partially compensated by the energy input of the manipulator (M4, M5). Furthermore, the present invention relates to a corresponding method for controlling the microlithography projection exposure apparatus (10, 80).

Description

[0001] This application claims priority to German patent application 10 2020 201 723.9, dated February 12, 2020. The entire disclosure of that patent application is incorporated herein by reference. Background Technology

[0002] This invention relates to a microlithography projection exposure apparatus, including a projection lens for projecting a structure onto a substrate plane by exposure radiation. Specifically, at least one optical element of the projection lens is equipped with a manipulator configured to input thermal energy into the optical element. Furthermore, this invention relates to a method for controlling such a projection exposure apparatus.

[0003] During the fabrication of integrated circuits or other micro- or nanostructured components, projection exposure equipment can be used to create extremely small structures on a substrate. To do this, the projection lens of the projection exposure equipment images the structure of a mask or master mask onto the photosensitive layer of the substrate during predefined exposure intervals. Typically, a wafer made of semiconductor material is used as the substrate. After exposure has been performed, the substrate is usually moved or replaced for further exposure.

[0004] With the miniaturization of semiconductor structures and the demand for faster manufacturing processes with shorter exposure times, increasingly stringent requirements are being placed on the imaging properties of projection exposure equipment, particularly projection lenses. Therefore, to image the mask structure onto the wafer as accurately as possible, projection lenses with the smallest possible imaging aberrations are required. Besides imaging aberrations caused by manufacturing or mounting tolerances, imaging aberrations that occur during operation are also known. In this regard, the unavoidable absorption of some electromagnetic radiation used for exposure in the optics of projection exposure equipment typically leads to uneven heating of the optics. This heating of lens elements or mirrors is also known as "lens heating" and results in localized changes in refractive index, expansion, and mechanical stress, as well as wavefront aberrations propagating in the projection lens.

[0005] Various optical manipulators are used to correct wavefront aberrations occurring during operation. For example, DE 10 2015201 020 A1 discloses a manipulator having multiple individually heatable regions within an optical element. In the case of these thermal manipulators, thermal input is induced, for example, by infrared radiation or by an electrical conductor track and resistive structure. Other known manipulators allow for surface deformation or repositioning of the optical element in one or more of the six rigid body degrees of freedom. The manipulators enable the optical effect of the corresponding optical element to be established by changing the corresponding state during operation of the projection exposure apparatus. Depending on the aberration characteristics of the projection lens, measured or determined by simulation, wavefront deformation, at least partially suitable for compensating for currently occurring wavefront aberrations, can be induced during operation in this manner.

[0006] During the operation of projection exposure equipment, there is a constant alternation between exposure time and exposure pauses without exposure radiation. For example, wafer replacement occurs during a pause. This constant alternation between exposure time and exposure pauses leads to rapidly changing, thermally determined imaging aberrations. This effect is also known as "rapid lens heating" and causes rapid, periodic changes in imaging properties, resulting in corresponding imaging aberrations. In the case of known projection exposure equipment, these imaging aberrations can only be poorly compensated for by the manipulator, or not compensated for at all, because the necessary measurements or simulations of the imaging properties and the calculation and setting of the corresponding stroke for the manipulator are particularly time-consuming.

[0007] Purpose of the invention

[0008] The object of the present invention is to provide an apparatus and method that solves the above-mentioned problems, and in particular results in a reduction of imaging aberrations caused by the constant alternation between exposure time and exposure pause of the projection exposure apparatus. Summary of the Invention

[0009] The aforementioned objective can be achieved according to the invention, for example, by a microlithography projection exposure apparatus comprising a projection lens for projecting a structure onto a substrate plane by exposure radiation, wherein at least one optical element of the projection lens is equipped with a manipulator configured to selectively input thermal energy into the optical element without significantly heating one of the other optical elements of the projection lens in the process. Furthermore, the projection exposure apparatus includes a control device configured to control the exposure radiation and to control the manipulator, such that the effect on the optical properties of the projection lens caused by the reduction in thermal energy input to the projection lens due to exposure pauses is at least partially compensated by the energy input of the manipulator.

[0010] In other words, the control device is configured to control the manipulator such that the effect on the optical properties of the projection lens caused by the reduction of thermal energy input to the projection lens due to exposure pause is at least partially compensated by the energy input of the manipulator. The requirement to input thermal energy into the optical elements in a targeted manner, without significantly heating other optical elements of the projection lens in the process, should be understood as meaning that no thermal energy is input into the optical elements during the process, or that only a maximum of 5%, particularly a maximum of 1%, of the energy input into the first optical element is input into the other optical elements.

[0011] The optical elements of the projection lens are, for example, wavefront-shaping lens elements, plane plates that transmit exposure radiation, or mirror elements. The manipulator preferably allows specific thermal energy to be input to different sections or zones of the optical element, causing heating in response to corresponding changes in optical properties. The predefined temperature change of a section or zone is also referred to as the travel of that section or zone.

[0012] Exposure pause should be understood as a period of time during which the intensity of exposure radiation in the projection lens is reduced or decreased, and therefore no exposure radiation subsequently passes through the projection lens. The reduction in heat input due to exposure pause is at least partly caused by the reduction in the intensity of exposure radiation during the exposure pause.

[0013] In other words, according to the invention, the effect of reduced thermal energy input to the projection lens caused by exposure pauses is compensated at least partially in a targeted manner. This is accomplished by a manipulator configured to input thermal energy into the optical elements in a targeted manner. The operation of the projection lens according to the invention can also be simply referred to as "reverse-cycle heating of the optical elements." Heating occurs specifically when no exposure occurs, and is therefore reverse-cycled relative to each exposure time period. The targeted input of thermal energy into the optical elements, without significantly heating one of the other optical elements of the projection lens in the process, allows for precise compensation of the effects of exposure pauses on the projection lens, so that the optical response of the optical elements to the input thermal energy can be accurately predicted and is not disrupted by the less accurate known optical response of the other optical elements.

[0014] Compared to conventional wavefront correction using an optimization method known as a "lens model," where the wavefront deviation of the projection lens is determined over a specific time period and then corrected by appropriate manipulator changes, the operation according to the invention allows for much faster correction of wavefront aberrations caused by exposure pauses, or even complete prevention of their occurrence. The long timescale in conventional wavefront correction stems from the fact that the wavefront deviation must first be established as a result of thermal changes occurring in the relevant optical elements during exposure pauses, and then this deviation can only be corrected by appropriate manipulator changes calculated using the "lens model." In the case of introducing thermal energy into the optical elements according to the invention, the formation of the corresponding wavefront deviation is at least partially prevented.

[0015] In the case of relatively thick optical elements, the rapid on- and off-off of exposure radiation during operation of the projection exposure apparatus causes almost no short-term temperature fluctuations that alter the imaging properties. Instead, during operation, these optical elements are heated to thermal equilibrium. Imaging aberrations caused by heating can generally be compensated for by appropriate settings of the manipulator determined through control methods known in the art.

[0016] The present invention is based on the understanding that the rapid on and off of exposure radiation that occurs during the operation of the projection exposure device is different from the case of relatively thick optical elements. In the case of thin lens elements or other thin optical elements, heating occurs due to exposure radiation during each exposure interval and cooling occurs during the intermediate exposure pauses, which leads to rapidly changing thermally determined imaging aberrations.

[0017] This effect leads to the "rapid lens heating" mentioned in the introduction, which in turn causes rapid periodic changes in imaging properties, and thus corresponding imaging aberrations. As already mentioned, in the case of known projection exposure equipment, these imaging aberrations can only be poorly compensated, or not compensated at all, by a manipulator controlled by a "lens model," because the necessary measurements or simulations of the imaging properties and the calculation and setting of the corresponding stroke for the manipulator are particularly time-consuming.

[0018] According to the invention, the energy input of the manipulator at least partially compensates for the reduction in thermal energy input to the projection lens due to exposure pauses, thereby reducing imaging aberrations caused by the continuous alternation between exposure time and exposure pauses in the projection lens with thin optical elements.

[0019] According to one embodiment, the effect of at least partially compensating for the energy input via the manipulator includes altering the wavefront aberration of the projection lens due to exposure pause. According to other embodiments, the projection exposure apparatus further includes a wavefront determination device for determining the wavefront deviation between the projection lens and the target wavefront, wherein the control device is further configured to correct the wavefront deviation between the projection lens and the target wavefront via the manipulator of the projection lens and / or at least one additional manipulator.

[0020] According to other embodiments, the temporal distribution of the effect of energy input caused by the manipulator is coordinated with the temporal distribution of the effect of exposure pause on the optical properties of the projection lens. In particular, the temporal distribution of the effect of energy input is coordinated with the temporal distribution of the effect of exposure pause on the wavefront aberration of the projection lens.

[0021] According to other embodiments, the optical element equipped with the manipulator has a sub-aperture ratio of at least 0.4, particularly greater than 0.75 or greater than 0.9. As known to those skilled in the art from US2013 / 0188246A1, for example, the sub-aperture ratio of the optical element is formed by the quotient of the sub-aperture diameter and the optical free diameter. The sub-aperture diameter is given by the maximum diameter of the corresponding surface that is illuminated when imaging any point (but specifically a selected point) on the object field of the optical element. The optical free diameter is the diameter of the smallest circle around the corresponding reference axis of the corresponding optical element, which is included in the portion of the optical element illuminated when imaging the entire object field.

[0022] For example, a sub-aperture ratio greater than 0.75 implies an arrangement in the pupil plane or a near-pupil arrangement, a sub-aperture ratio less than 0.25 implies an arrangement in the field plane or a near-field arrangement, and an intermediate sub-aperture arrangement implies an intermediate arrangement of the optical element between the field plane and the pupil plane. Therefore, in this embodiment, a predefined sub-aperture ratio of at least 0.4 includes both intermediate and near-pupil arrangements.

[0023] According to other embodiments, the optical element equipped with the manipulator has a central thickness of up to 10 mm, particularly up to 8 mm or up to 5 mm. The central thickness of the optical element should be understood as meaning the size of the optical element in the direction of the beam path of the projection lens in the region centered on the optical axis of the optical element or in the region of the optical element's cross-section relative to the beam path. The thinner the optical element, the faster the localized heating occurs during exposure radiation, and the faster the cooling of the heated area occurs in the absence of exposure radiation.

[0024] According to other embodiments, at least one additional optical element from the projection lens is assigned to the optical element equipped with the manipulator, such that the sub-aperture ratio of the assigned additional optical element deviates from the sub-aperture ratio of the optical element equipped with the manipulator by a maximum of 0.3, wherein the central thickness of the assigned additional optical element is at most 10 mm. Specifically, the sub-aperture ratios deviate from each other by a maximum of 0.2 or a maximum of 0.1. For example, if the optical element equipped with the manipulator is located in the pupil plane, the designated additional optical element is also located in the pupil plane or only a small distance away from it. According to various embodiment variations, the central thickness of the assigned additional optical element is at most 8 mm or at most 5 mm. According to one embodiment variation, the central thickness of the optical element equipped with the manipulator deviates from the central thickness of the assigned optical element by at most 5 mm, particularly at most 2 mm.

[0025] According to other embodiments, the additional optical element is configured as a meniscus lens element arranged in front of the concave mirror. As those skilled in the art will appreciate, a meniscus lens element should be understood to mean a lens element combining a concave surface and a convex surface. In this case, the refractive power of such a meniscus lens element can be positive or negative. According to one embodiment, the concave mirror constitutes the primary mirror of the projection lens, i.e., the mirror with the highest refractive power in the projection lens.

[0026] According to other embodiments, the additional optical elements disposed thereon have a sub-aperture ratio of at least 0.4, particularly a sub-aperture ratio greater than 0.75 or greater than 0.9. A sub-aperture ratio greater than 0.75 is also considered to imply that the optical elements are arranged near the pupil.

[0027] According to other embodiments, at least one additionally allocated optical element includes a lens element arranged in the front third of the projection lens, a lens element arranged in the rear third of the projection lens, and / or a lens element arranged in front of the concave mirror. In other words, the lens element arranged in the front third of the projection lens, the lens element arranged in the rear third of the projection lens, and / or the lens element arranged in front of the concave mirror can form the above-described allocated optical element or multiple such allocated optical elements. The projection lens is subdivided into three different parts based on the length of the beam path in the projection lens.

[0028] According to other embodiments, the projection exposure apparatus is configured to operate in the DUV wavelength range. Specifically, the operating wavelength of the projection exposure apparatus is approximately 248 nm or approximately 193 nm.

[0029] According to one embodiment, the projection exposure apparatus further includes a determining device configured to determine the distribution of thermal intensity input to the optical element by exposure radiation during the exposure process. The determining device may include a simulation module for calculating the distribution of thermal energy input to the element by exposure radiation during the exposure process. Alternatively, the input thermal energy distribution may also be determined by measurement or a combination of measurement and simulation and / or calculation by a suitable measuring device of the determining device. As known to those skilled in the art, the thermal intensity distribution is understood to mean the spatial energy distribution transferred to the optical element per unit time and per unit area.

[0030] In other embodiments, the control device is configured to control the manipulator based on a determined heat intensity distribution. As an example, the manipulator is controlled such that the thermal input generated by the manipulator substantially corresponds to the determined heat intensity distribution. In other words, by means of the manipulator, the determined heat intensity distribution remains substantially unchanged even during exposure pauses. This measure allows control to be achieved such that the temperature distribution within the optical element does not change or only changes insignificantly due to the on and off of exposure radiation.

[0031] According to other embodiments, the control device is configured to control the manipulator such that energy input is distributed in a spatially resolved manner over the optically effective area of ​​the optical element. As an example, the manipulator is designed to heat individual segments or sections of the optical element. The control device can then be configured such that each segment or section is heated individually, thereby generating a predefined heat intensity distribution or a predefined spatially resolved temperature profile.

[0032] According to other embodiments, the control device is configured to realize energy input induced by the manipulator within a time period of up to 10% of the wavefront deviation corresponding to the reduction in thermal energy input in the projection lens. Specifically, the control device is configured to realize energy input induced within a time period of up to 1% or up to 0.1% of the wavefront deviation corresponding to the reduction in thermal energy input. The wavefront deviation corresponding to the reduction in thermal energy input should be understood as meaning the wavefront deviation of the projection lens formed after a certain time period in the absence of energy input induced by the manipulator. Since there is no thermal energy input, the optical element requires this time period to achieve a new thermal equilibrium.

[0033] According to other embodiments of the projection exposure apparatus, the control device is configured to implement thermal energy input for a period of up to 15 seconds. Specifically, the control device is configured to implement thermal energy input for a period of up to 10 seconds, up to 7 seconds, or up to 5 seconds. In other words, the energy input from the actuator ends after a maximum of 15, 10, 7, or 5 seconds. According to one embodiment, the period without energy input from the actuator is at least as long as the period of energy input.

[0034] In other embodiments of the invention, the control device is configured to provide thermal energy input for a period of at least 2 seconds. Specifically, the control device is configured to provide thermal energy input for a period of at least 3 seconds or at least 5 seconds. In particular, periodic energy input can be provided during each exposure pause between two exposures.

[0035] According to other embodiments, the projection exposure apparatus further includes a wavefront determination device for determining the wavefront deviation between the projection lens and the target wavefront. Furthermore, the control device is configured to correct the wavefront deviation between the projection lens and the target wavefront via a manipulator and / or at least one additional manipulator of the projection lens. The wavefront determination device may include, for example, a measuring device, a simulation module, or both, for determining the wavefront deviation. The simulation by the simulation module is based, for example, on a suitable “lens model” known to those skilled in the art. The measuring device may be designed, for example, to implement phase-shifting interferometry techniques, such as shearing interferometry or point diffraction interferometry.

[0036] According to other embodiments, the optical elements are configured as planar parallel plates, also referred to as planar plates. According to other embodiments, multiple optical elements of the projection lens are all configured as planar parallel plates. Specifically, each optical element configured as a planar parallel plate is equipped with a manipulator configured to input thermal energy into the optical element.

[0037] According to other embodiments of the projection exposure apparatus, the manipulator includes a heating element for inputting thermal energy into the optical element. For example, the heating element is an electrically operated heating element. In the case of such a heating element, the current supply can be provided either by an electrical conductor or inductively. In the case of electrical heating, the energy input can be controlled by corresponding control of the heating current. Furthermore, according to one embodiment, the optical element comprises a quartz body. Increased temperature in the quartz results in an increase in its refractive index. According to a variation of one embodiment, the heating power of the heating element is 10 W / m. 2 With 150W / m 2 Especially at 50W / m 2 and 100W / m 2 According to other embodiments, the total power of the heating element is between 0.2W and 5W, particularly between 0.5W and 2.0W.

[0038] According to one embodiment of the invention, the projection lens includes additional optical elements with manipulators configured to input thermal energy into the optical elements, and the two optical elements are implemented as planar parallel plates, each having a plurality of heatable partitions. Preferably, the heatable partitions are arranged in a manner distributed across the cross-section of the exposure beam path of the projection lens. According to one embodiment, for each partition, in the case of two plates used for electrical heating, very small conductive and resistive structures are provided. Furthermore, for the purpose of cooling the plates, an airflow or gas flow can be guided in the gap between the two plates.

[0039] According to other embodiments, a gap having a width of at least 3 mm, particularly at least 5 mm, is arranged between each optical element of a plate configured to be planar parallel. According to other embodiments, the gap width is at most 20 mm or at most 10 mm.

[0040] According to other embodiments, the manipulator includes an irradiation device for radiating thermal radiation onto optical elements. The heating radiation may have a wavelength different from that of the exposure radiation; alternatively, the heating radiation may also have the same wavelength as the exposure radiation.

[0041] Heating radiation can be directed laterally onto the optical element relative to the beam path of the exposure radiation, i.e., radiating from the edge of the optical element. This process is also referred to as "heating by lateral light." Alternatively, for example, by means of a mirror, the heating radiation can be coupled into a region of the exposure beam path and thus radiate substantially perpendicularly onto the optical element. In an alternative embodiment, a manipulator is used to direct a flow of hot gas onto the optical element, thereby inputting thermal energy into the optical element.

[0042] In other embodiments, the projection exposure apparatus is configured to operate in the UV wavelength range. Specifically, the operating wavelengths of the projection exposure apparatus are approximately 365 nm, approximately 248 nm, or approximately 193 nm. Alternatively, the projection exposure apparatus can be designed to operate in the extreme ultraviolet (EUV) wavelength range, having wavelengths less than 100 nm, particularly approximately 13.5 nm or approximately 6.8 nm. EUV wavelength range projection exposure apparatuses essentially consist of mirrors as optical elements. Furthermore, compared to projection exposure apparatuses used for radiation in different, longer wavelength spectral ranges, EUV projection exposure apparatuses typically have significantly fewer optical elements or optical surfaces to reduce intensity loss due to absorption.

[0043] The aforementioned objective can also be achieved, for example, by a method for controlling a microlithography projection exposure apparatus, the apparatus comprising a projection lens and a manipulator for at least one optical element of the projection lens, the manipulator being used to selectively input thermal energy into the optical element without significantly heating one of the other optical elements of the projection lens in the process. The method includes controlling the exposure radiation for projecting the structure onto a substrate plane and controlling the manipulator such that the effect on the optical properties of the projection lens caused by the reduction in thermal energy input to the projection lens due to exposure pauses is at least partially compensated by the energy input of the manipulator.

[0044] An embodiment of the method according to the invention further includes determining the heat intensity distribution input to the optical element by exposure radiation during the exposure process, and controlling the manipulator based on the determined heat intensity distribution.

[0045] The features specified above, such as those of the embodiments, exemplary embodiments, and variations thereof, of the projection exposure apparatus according to the invention, can be correspondingly applied to the control method according to the invention. These and other features of embodiments according to the invention will be explained in the description of the claims and drawings. Individual features may be implemented separately or in combination as embodiments of the invention. Furthermore, they may describe advantageous embodiments that can be protected independently, as well as protection claimed only during or after the period when this application is pending (if reasonable). Attached Figure Description

[0046] The above and other advantageous features of the invention are illustrated in the following detailed description of exemplary embodiments thereof, with reference to the accompanying schematic drawings. In the drawings: +

[0047] Figure 1A first exemplary embodiment of a microlithography projection exposure apparatus according to the present invention is illustrated in schematic diagram. The projection lens includes two parallel optical plates and, in various cases, manipulators for heating multiple zones of each plate.

[0048] Figure 2 A more detailed schematic diagram is shown according to Figure 1 One of the optical flat plates in an exemplary embodiment,

[0049] Figure 3 A second exemplary embodiment of the projection exposure apparatus according to the present invention is illustrated schematically, comprising a thin optical plate as an optical element having a heatable partition.

[0050] Figure 4 The diagram illustrates the various regions on the optical elements of the projection lens that experience high-intensity exposure radiation.

[0051] Figure 5 The diagram illustrates the following: Figure 4 The thermal intensity distribution on the optical element determined by the exposure radiation.

[0052] Figure 6 The diagram illustrates the thermal power input to the optical element via exposure radiation and thermal manipulators during the exposure of multiple wafers, and...

[0053] Figure 7 The figure illustrates a comparison of the time profiles of the Zernike coefficient Z12 shift during the exposure of multiple wafers using the projection exposure apparatus according to the present invention and conventional projection exposure apparatus. Detailed Implementation

[0054] In the exemplary embodiments, examples, or variations thereof described below, elements that are functionally or structurally similar to each other are provided with the same or similar reference numerals wherever possible. Therefore, in order to understand the characteristics of individual elements of a particular exemplary embodiment, reference should be made to the description of other exemplary embodiments of the invention or to the general description of the invention.

[0055] For ease of description, a Cartesian xyz coordinate system is indicated in some of the accompanying drawings, and the positional relationship of the components shown in the drawings with respect to this coordinate system is self-evident. Figure 1 In the diagram, the y-direction extends vertically into and out of the plane of the attached diagram, the x-direction points to the right, and the z-direction points downward.

[0056] Figure 1A microlithography projection exposure apparatus 10 for producing microstructured components, such as integrated circuits, is illustrated schematically. The projection exposure apparatus 10 is used to project the structure of a mask 12 or mask master onto the photosensitive layer of a substrate 14. A wafer made of silicon or some other semiconductor is typically used as the substrate 14.

[0057] For projection, the projection exposure apparatus 10 includes a radiation source 16 for providing electromagnetic radiation as exposure radiation 18. In this exemplary embodiment, the radiation source 16 provides radiation in the UV range, particularly radiation in DUV with wavelengths of, for example, approximately 248 nm or 193 nm, and for this purpose includes, for example, a suitably designed laser. In an alternative exemplary embodiment, the radiation source may also be configured to provide radiation in the extreme ultraviolet (EUV) wavelength range, with wavelengths less than 100 nm, particularly approximately 13.5 nm or approximately 6.8 nm.

[0058] Exposure radiation 18 from radiation source 16 first passes through illumination system 20 of projection exposure device 10. Illumination system 20 includes multiple optical elements, among which lens element 22 and deflecting mirror 24 are... Figure 1 The image is symbolically shown. The illumination system 20 sets the desired illumination of the mask 12. Such an illumination setting is also referred to as an illumination configuration. Such an illumination configuration defines the angular distribution of the exposure radiation 18 radiated onto the mask 12. Examples of illumination configurations include dipole, quadrupole, or multipole illumination. Furthermore, the illumination system may include or make possible a scanner slot for continuously scanning the mask 12 with an exposure beam having a rectangular cross-section.

[0059] The projection exposure apparatus 10 also includes a projection lens 26 for imaging the structure of the mask 12 onto the photosensitive layer of the substrate 14. For this purpose, the structure of the mask 12 is arranged in the object plane 28 and the photosensitive layer is arranged in the image plane 30 of the projection lens 26. The image plane 30 can therefore also be referred to as the substrate plane on which the mask structure is projected. For the purpose of imaging the structure, the projection lens 26 includes multiple optical elements in the form of lens elements, mirrors, etc. Figure 1 The image illustrates, by way of example, lens element 41, first optical plate 38, second optical plate 40, first deflecting mirror 32, concave mirror 36, meniscus lens element 35 directly disposed in front of concave mirror 36, second deflecting mirror 34, and thin converging lens element 37. The optical elements of projection lens 26 define the beam path 42 of projection lens 26. According to an exemplary embodiment, concave mirror 26 constitutes the primary mirror of projection lens 26, i.e., it is the mirror with the highest refractive power in the projection lens. Figure 1In the illustrated exemplary embodiment, lens element 41 is arranged in the first third of the projection lens 26, while thin converging lens element 37 is arranged in the last third of the projection lens 26. The subdivision of the projection lens 26 is here achieved based on the length of the beam path of the exposure radiation 18 in the projection lens 26.

[0060] The central thickness of the meniscus lens element 35 is at most 10 mm, and more particularly at most 5 mm, and together with the concave mirror 36, it forms a so-called Schumann achromatic effect.

[0061] Lens element 41, optical plates 38 and 40, thin diverging lens element 36, and thin converging lens element 37 are each arranged in the beam path 42 of the projection lens 26 such that their sub-aperture ratios are at least 0.4, particularly at least 0.7 or at least 0.9, meaning they are at a considerable optical distance from the field plane or conjugate field plane, and, according to a particular embodiment, are located near the pupil plane or the conjugate pupil plane of the projection lens 26. For the definition of sub-aperture ratio, refer to the explanation given above herein. According to one embodiment, the maximum deviation of the sub-aperture ratio of optical plates 38 and 40 from the corresponding sub-aperture ratio of thin diverging lens element 36, thin converging lens element 37, and / or lens element 41 is 0.3, particularly 0.1.

[0062] To maintain and accurately position the mask 12, the projection exposure apparatus 10 includes a mask mount 44. Even during operation, the mask mount 44 can achieve spatial displacement, rotation, or tilting of the mask 12 by means of an actuator. Furthermore, for scanning operations, the mask mount 44 can be designed to move the mask 12 perpendicular to the optical axis 46 of the projection lens 26. Correspondingly, a substrate mount 47 is provided for the substrate 14 and is designed to spatially displace, rotate, or tilt the substrate 14 by means of an actuator, even during operation. Furthermore, for step-scan operations, the substrate 14 can be specified to move perpendicular to the optical axis 46.

[0063] To avoid manufacturing defects in the case of microstructured or nanostructured components, imaging aberrations of the projection lens 26 must be minimized during the imaging of the structure of mask 12 onto substrate 14. Besides imaging aberrations caused by manufacturing and assembly tolerances, imaging aberrations may occur only in the projection lens 26 during operation of the projection exposure apparatus 10. In this regard, individual optical elements thus experience localized heating due to the inevitable absorption of a portion of the incident or transmitted exposure radiation 18. Heating may cause localized changes in surface geometry due to expansion or mechanical stress, or lead to changes in material properties such as refractive index. Another reason for operationally determined imaging aberrations is aging effects, such as material shrinkage.

[0064] The imaging aberrations of a lens are typically described as the deviation of the measured optical wavefront from the target wavefront. This deviation is also known as wavefront distortion or wavefront aberration, and can be decomposed into individual components through a series expansion. It has been found that decomposing it into Zernike polynomials is particularly suitable in this case because the individual terms of the decomposition can be assigned to specific imaging aberrations, such as astigmatism or coma.

[0065] To compensate for such wavefront aberrations that occur or change during operation, the projection lens 26 includes various manipulators for altering the optical properties of the optical elements. A manipulator M1 is arranged for the first deflector 32, configured to move the first deflector 32 in a plane and thus in two mutually perpendicular directions. The plane of displacement is arranged, for example, parallel to the reflecting surface of the first deflector 32 or parallel to the optical axis 46.

[0066] The second deflector 34 can be tilted by rotating the manipulator M2 about an axis parallel to the y-axis. The angle of the reflecting surface of the second deflector 34 relative to the incident exposure radiation is thus changed. In other exemplary embodiments, the manipulators M1, M2, and M3 may have other degrees of freedom. Typically, the associated optical elements 32 and 34 can be moved by performing rigid body motion along a predefined path. As an example, such a path can be a combination of translation, tilting, or rotation in any manner.

[0067] The concave reflector 36 is implemented as a deformable or adaptive reflector. For this purpose, the projection lens 26 includes a manipulator M3 configured to individually deform multiple regions of the reflective coating into partitions whose optical effects can be individually set. The travel of the manipulator M3 describes the specific deformation of the concave reflector 36 via multiple actuators.

[0068] For the first and second transparent optical plates 38 and 40, the projection lens 26 includes electrically operated thermal manipulators M4 and M5 in each case. Both manipulators M4 and M5 have multiple conductive and resistive structures in the respective plates for heating localized zones. The optical plates 38 and 40 are arranged perpendicular to the optical axis 46 and planar parallel to each other in the beam path of the projection lens 26. A gap 48 is formed between the optical plates 38 and 40 to guide air, gas, or liquid flow 50 through them for cooling purposes.

[0069] In this exemplary embodiment, optical plates 38 and 40 are implemented as thin quartz plates, each with a central thickness of approximately 5 mm. The quartz plates can have a uniform thickness, so the term "thickness" can be used instead of "central thickness." There is a gap of approximately 7 mm between the quartz plates. Alternatively, more than two optical plates, non-planar parallel plates, or lens elements with multiple heatable zones can be arranged in the projection lens. In quartz, an increase in temperature near a wavelength of 193 nm leads to an increase in refractive index. This effect is particularly due to wavefront aberrations caused by lens heating. At optical plates 38 and 40, this effect is used to produce wavefront distortion designed to compensate for wavefront aberrations currently occurring in the projection lens 26, such as those caused by lens heating in one or more optical elements. In other words, the temporal profile of the effect of the energy input caused by manipulators M4 and / or M5 is coordinated with the temporal profile of the effect of exposure pause on the optical properties of the projection lens 26. However, rapid lens heating, as further described, may occur at the thin optical plates 38, 40, the meniscus lens 35, and the thin converging lens 37. Heating and cooling occur during the cycle of exposure time and exposure pauses. This results in rapid changes in periodic imaging aberrations.

[0070] Figure 2 A schematic diagram of a first optical plate 38 is illustrated. The first plate 38 comprises a two-dimensional matrix of individually heatable partitions 52. In this exemplary embodiment, the first optical plate 38 has a 14×14 matrix of partitions 52. Here, ninety-six individually heatable partitions 52 are arranged optically efficiently in the beam path 42 of the projection lens 26. A corresponding embodiment of the second optical plate 40 is shown, such that a total of one hundred and ninety-two heatable partitions 52 are arranged in the beam path 42. Alternatively, different numbers, arrangements, and forms of partitions 42 are also possible; as examples, the partitions may be arranged radially or implemented as strips or in an arcuate manner.

[0071] According to one embodiment, the heating zone 52 ensures that the cooler and hotter areas are generally balanced relative to the ambient temperature. Furthermore, the zones 52 at the edges of the optical plates 38, 40 that are in thermal contact with other components of the projection lens 26 are actively heated to ambient temperature. This ensures the thermal neutrality of the optical plates 38, 40 relative to their surroundings.

[0072] The following description references [references to] Figure 1 and Figure 2 The manipulators M4 and M5 for the optical plates 38 and 40 also include an actuator 54 for setting a predefined temperature profile or thermal intensity distribution for the two optical plates 38 and 40. Such a temperature profile specifies temperature values ​​or corresponding values, such as in W / m². 2The heating power is expressed as a unit, representing the stroke of each section 52 of the two optical plates 38, 40. Therefore, the heat intensity distribution represents the stroke. The actuator 54 supplies an appropriate heating current to each section 52 of the optical plates 38, 40 to set a predefined stroke, and can additionally adjust the cooling via airflow, gasflow, or liquidflow 50.

[0073] Based on the temperature profiles settable at optical plates 38 and 40 via manipulators M4 and M5, thermal energy can be selectively introduced into the relevant optical plate 38 or corresponding optical plate 40 without significantly heating any other optical elements 41, 32, 35, 36, 34, 37, and 40 or corresponding 38 arranged in the beam path of the projection lens 26. This should be understood to mean that no thermal energy is input to another optical element during the process, or at most 5%, particularly at most 1%, of the energy input to the first optical element is input to the optical plate 38 or corresponding optical plate 40.

[0074] Furthermore, for lens element 41, projection lens 26 includes a manipulator M6 configured to heat various sections of lens element 41 via infrared radiation. For this purpose, manipulator M6 includes a plurality of irradiation units 55 that radiate infrared light provided by the infrared light source of manipulator M6 onto specific areas or sections of lens element 41 at intensities set in various cases. Lens element 41 with manipulator M6 can be arranged in the field plane or pupil plane of projection lens 26, or intermediately (i.e., between the field plane and pupil plane). The thermal manipulator M6, which radiates infrared light onto specific areas or sections of lens element 41, is particularly suitable for exposure radiation in the deep ultraviolet (DUV) or VUV spectral range, and for exposure radiation as described, for example, in US 2008 / 0204682 A1. By means of the manipulator M6, heat energy can thus be directed to the lens element 41 without significantly heating any other optical elements 38, 40, 32, 35, 36, 34 and 37 arranged in the beam path of the projection lens 26.

[0075] The projection exposure apparatus 10 also includes a control unit 56, which is configured specifically for controlling the exposure radiation 18 and the manipulators M1 to M5. For this purpose, the control unit 56 includes an exposure controller 58 and a manipulator controller 60. By means of the exposure controller 58, the illumination system 20 is set to achieve the desired illumination settings, exposure time periods, and exposure pauses as accurately as possible. Exposure pauses are particularly necessary when changing wafers. The set illumination settings 62, as well as the exposure time and exposure pauses, are transmitted to the manipulator controller 60.

[0076] The manipulator controller 60 includes a wavefront determination device 64 for determining the wavefront deviation between the projection lens 26 and the target wavefront. In this case, the wavefront 68 measured by the wavefront measurement device 66, along with other state characteristics, is transmitted to the wavefront determination device 64 and taken into account when determining the wavefront deviation. The wavefront measurement device can be configured, for example, to implement phase-shifting interferometry techniques, such as shearing interferometry or point diffraction interferometry. Alternatively or additionally, the wavefront deviation calculated by the simulation module 70 using a lens model can be taken into account. In this way, depending on the position of the manipulator, the wavefront deviation can even be determined before or between wavefront measurements.

[0077] To compensate for the determined wavefront deviation, the stroke generator 72 is used to determine the optimal stroke X1 to X5 for each manipulator M1 to M5. In this case, an optimization method of appropriate design, also known as a "lens model," known to those skilled in the art, can be used. The determined strokes X1 to X5 are then transmitted to the manipulators M1 to M5, which then implement the corresponding settings for the optical elements 32 to 41. In this way, for example, imaging aberrations of the projection lens 26 can be compensated for, for example, due to slow heating of the optical elements or other components during multiple exposure periods and exposure pauses, or due to aging effects (such as the shrinkage of optical materials). However, this process is not suitable for correcting imaging aberrations caused by rapid lens heating.

[0078] To compensate for this instantaneous periodic wavefront deviation caused by rapid lens heating at the two optical plates 38, 40, the control device 56 additionally includes a determining device 74 for determining the heat intensity distribution in the first and second optical plates 38, 40 by the exposure radiation input. This determination is achieved by taking into account the illumination setting 62 transmitted by the exposure controller 58, as well as the transmitted exposure time period and exposure pause. In this case, the heat intensity distribution can be calculated using the simulation module 70, or... Figure 1 The intensity distribution is measured by a measuring device not shown in the figure.

[0079] Based on the determined heat intensity distribution, the stroke generator 72 of the control device 56 generates strokes X4, X5 for the manipulators M4, M5 of the two optical plates 38, 44 for exposure pause, such that the heat intensity distribution does not change even during exposure pause. In this case, energy is input by the manipulators M4, M5, preferably directly at the beginning of exposure pause, but at least for a period of time during which a wavefront deviation corresponding to a reduction in heat energy input due to exposure radiation is formed in the projection lens (26) by a maximum of 10%.

[0080] In other words, the spatially resolved energy input of the exposure radiation 18 is maintained during the exposure pause via the corresponding thermal energy input of the manipulators M4 and M5. In this way, the spatially resolved temperature profile remains substantially constant during the exposure time and during the exposure pause at the two thin optical plates 38 and 40. This reverse-cycle heating by means of the thermal manipulators M4 and M5 effectively reduces imaging aberrations caused by rapid heating and cooling during the exposure time cycle.

[0081] Figure 3 The illustration shows another microlithography projection exposure apparatus 80. The projection exposure apparatus 80 corresponds to... Figure 1 The projection exposure device differs from the one based on Figure 1 Compared to the projection exposure apparatus 10, in the projection exposure apparatus 80, the two parallel plane plates 38, 40 have been removed and replaced by a thin lens element 82. The central thickness of the lens element 82 is at most 10 mm. In particular, the central thickness of the lens element 82 is at most 8 mm or at most 5 mm. The lens element 82 is essentially implemented as a thin flat plate and serves as a placeholder for the two parallel plane plates 38, 40 in the projection lens 26. For this reason, it has essentially the same optical properties as the unheated optical plates 38, 40, so the projection lens 26 can be further used even without the parallel plane optical plates 38, 40.

[0082] At the thin lens element 82, rapid lens heating occurs in response to the corresponding rapid and periodic changes in imaging aberrations during the cycles of exposure time and exposure pauses, which also occur during the operation of the projection exposure apparatus 80. To compensate for these imaging aberrations, the thin lens element 82 also includes multiple electrically heated zones. For example, electrical conductors and resistive elements for heating are arranged at each zone.

[0083] Alternatively, thin lens element 82 and similarly, according to Figure 1The two optical plates 38 and 40 can also be heated by corresponding irradiation using heating radiation (e.g., infrared light). This irradiation using heating radiation can be similar to the irradiation of lens element 41 via irradiation unit 55 of manipulator M6 described above. The heating radiation can have a wavelength different from that of exposure radiation 18; alternatively, the heating radiation can also have the same wavelength as exposure radiation 18. The heating radiation can be radiated laterally to the optical element relative to the beam path of the exposure radiation, i.e., radiated from the edge of the optical element. This process is also referred to as “heating by lateral light”. Alternatively, for example, by means of a mirror, the heating radiation can be coupled to a region of the exposure beam path and thus radiated substantially perpendicularly to the associated optical element, i.e., the thin lens element 82 or one of the two optical plates 38 and 40. In an alternative embodiment, the manipulator is used to direct a flow of hot gas to the associated optical element, thereby inputting thermal energy into the optical element.

[0084] Similar to according to Figure 1 The projection exposure equipment, according to Figure 3 The determining device 74 determines the thermal intensity distribution caused by the exposure radiation 18, taking into account the transmitted exposure setting 62, which includes exposure time periods and exposure pauses. Based on the determined thermal intensity distribution, the stroke generator 72 generates a stroke X4 for the manipulator M4 of the thin lens element 82 during exposure pauses. The stroke X4 is then designed so that the thermal intensity distribution does not change even during exposure pauses. The spatially resolved temperature profile of the thin lens element 82 remains substantially constant during many exposure time periods and exposure pauses. In this way, when the lens element 82 is used as a placeholder for the two optical plates 38, 40, imaging aberrations caused by rapid lens heating are prevented.

[0085] Figure 4 As an example, regions 90 with high-intensity exposure radiation 18 are shown in the cross-section of the beam path 42 at the optical plates 38, 40 of the projection lens 26. Therefore, the corresponding distribution of radiation intensity also serves as a placeholder for the optical plate at the thin lens element 82. The intensity distribution of exposure radiation 18 depends essentially on the exposure settings selected and set in each case. Depending on the exposure settings, higher radiation intensities occur in different regions 90 of the cross-section of the beam path 42, while lower radiation intensities occur in other regions. The greater the radiation intensity in region 90, the greater the degree of absorption of exposure radiation in the optical plates 38, 40 or lens element 82, which in turn causes localized heating of the optical plates 38, 40 or lens element 82 in these regions 90. During exposure pauses, these regions cool rapidly, and thus, along with heating, rapid periodic changes in optical properties occur along with corresponding imaging aberrations.

[0086] Figure 5The schematic illustration shows the surface 94 of the optical element 96 (e.g., optical plate 38, 40 or lens element 82) – according to Figure 4 The thermal intensity distribution 92 is determined for the exposure radiation. Dark areas 98 indicate high energy input, while brighter areas 100 indicate lower energy input. The beam path cross-sections for numerical apertures NA = 1.35 (solid circle 102) and NA = 0.85 (dashed circle 104) are illustrated. This spatially resolved thermal intensity distribution 92 is determined by the determining device 74 using illumination settings transmitted by the exposure controller, where calculations by the simulation module 70 or measurements by the measuring device can influence this determination. During exposure pauses, the manipulator controller 60 controls the manipulators M4, M5 of the optical plates 38, 40 or the manipulator M4 of the lens element 82, such that the same intensity distribution is produced as accurately as possible by the manipulator. This counter-periodic operation of the manipulators M4, M5 relative to the exposure time prevents rapid temperature changes and thus prevents corresponding imaging aberrations.

[0087] Figure 6 The diagram illustrates the input thermal power, or heat, applied to optical plates 38 and 40 by exposure radiation 18 and thermal manipulators M4 and M5 during the exposure of multiple wafers. Time is plotted in seconds along the x-axis and power in watts along the y-axis. The first exposure 110 lasts approximately 15 seconds and results in a power input of just over 0.7 watts during this time period. During the subsequent exposure pause 112, which is used for wafer replacement and has a duration of approximately 10 seconds, heat is applied by manipulators M4 and M5 at a similarly slightly higher power of 0.7 watts. The second and all subsequent exposures 114 also last approximately 15 seconds, with alternating inputs of approximately 0.72 watts and approximately 0.68 watts. After each exposure 114, an exposure pause 116 is applied, each lasting approximately 5 seconds. Here, manipulators M4 and M5 apply heat at the power of the preceding exposure 114 in each case. This prevents cooling and therefore prevents changes in the optical properties of optical plates 38 and 40.

[0088] Figure 7The diagram illustrates a comparison of the temporal profiles of the Zernike coefficient Z12 shift during the exposure of multiple wafers using the projection exposure apparatus according to the invention and a conventional projection exposure apparatus. The Zernike coefficient Z12, along with the Zernike coefficient Z13, describes the fifth-order astigmatism as an imaging aberration of the projection lens. In the diagram, time in seconds is plotted along the x-axis, and the shift of the Zernike coefficient Z12 in nanometers is plotted along the y-axis. The upper curve 120 shows the profile of Z12 in the case of a conventional projection exposure apparatus without the need for counter-cyclic heating via manipulators M4, M5, and a projection lens 26 with two thin, electrically heatable optical plates 38, 40. Short-term periodic fluctuations due to rapid heating and cooling during the exposure time and exposure pause cycles are clearly discernible. Furthermore, in general, general heating occurs with increasing negative shift of Z12. In contrast, the lower curve 122 of the projection exposure apparatus according to the invention exhibits significantly smaller periodic fluctuations because heat is applied counter-cyclically by the manipulators.

[0089] The exemplary embodiments, examples, or variations thereof described above should be considered as examples. This disclosure, thus achieved, firstly enables those skilled in the art to understand the invention and its associated advantages, and secondly covers obvious variations and modifications in the structures and methods described, as understood by those skilled in the art. Therefore, all such variations and modifications (provided they fall within the scope of the invention as defined by the appended claims) and their equivalents are intended to be covered by the claims.

[0090] List of reference numerals

[0091] 10 Projection Exposure Equipment

[0092] 12 Masks

[0093] 14 substrate

[0094] 16 Radiation Sources

[0095] 18 Exposure Radiation

[0096] 20 Lighting System

[0097] 22 Lens elements

[0098] 24 Deflecting mirrors

[0099] 26 Projection Lenses

[0100] 28 Object plane

[0101] 30 Image plane

[0102] 32 First deflecting mirror

[0103] 34 Second deflecting mirror

[0104] 35. Meniscus lens element

[0105] 36 Concave Reflector

[0106] 37 Thin converging lens element

[0107] 38 First Optical Flat Panel

[0108] 40 Second optical plate

[0109] 41 Lens element

[0110] 42 bundle paths

[0111] 44 Mask mounting components

[0112] 46 optical axes

[0113] 47. Substrate mounting components

[0114] 48 gap

[0115] 50 Gas Flow

[0116] 52 partitions

[0117] 54 Actuation device

[0118] 55 Irradiation Units

[0119] 56 Control device

[0120] 58 Exposure Controller

[0121] 60. Manipulator Controller

[0122] 62 Lighting Settings

[0123] 64 Wavefront Determination Device

[0124] 66 Wavefront Measurement Device

[0125] 68. Measured wavefront

[0126] 70 Simulation Modules

[0127] 72 Actuation stroke generator

[0128] 74. Device for determining heat intensity distribution

[0129] 80 Projection Exposure Equipment

[0130] 82 Thin lens element

[0131] Area 90

[0132] 92. Heat Intensity Distribution

[0133] 94 Surface

[0134] 96 Optical Components

[0135] 98 Dark Area

[0136] 100 bright area

[0137] 102 Solid circles

[0138] 104 Dashed circle

Claims

1. A microlithography projection exposure apparatus, comprising: - A projection lens for projecting the structure of a mask onto a substrate plane via exposure radiation, wherein at least one optical element of the projection lens is equipped with a manipulator configured to selectively input thermal energy into the optical element, so as not to significantly heat one of the other optical elements of the projection lens, and - A control device, configured to control the exposure radiation and to control the manipulator, such that the effect on the optical properties of the projection lens caused by the reduction in thermal energy input to the projection lens due to exposure pause is at least partially compensated in a targeted manner by the energy input of the manipulator. The control device is further configured to implement the thermal energy input within a time period of up to 15 seconds. The effect at least partially compensated by the energy input of the manipulator includes altering the wavefront aberration of the projection lens due to the exposure pause, and At least one additional optical element from the optical elements of the projection lens is assigned to the optical element equipped with the manipulator such that the sub-aperture ratio of the assigned additional optical element deviates from the sub-aperture ratio of the optical element equipped with the manipulator by a maximum value of 0.3, wherein the central thickness of the assigned additional optical element is at most 10 mm.

2. The projection exposure device according to claim 1, wherein The temporal distribution of the effect of the energy input caused by the manipulator is consistent with the temporal distribution of the effect of the exposure pause on the optical properties of the projection lens.

3. The projection exposure apparatus according to claim 1 or 2, wherein The sub-aperture ratio of the optical element equipped with the manipulator is at least 0.

4.

4. The projection exposure apparatus according to any one of the preceding claims, wherein The optical element equipped with the manipulator has a maximum central thickness of 10 mm.

5. The projection exposure apparatus according to any one of the preceding claims, wherein The additional optical elements are configured as meniscus lens elements arranged in front of the concave mirror.

6. The projection exposure apparatus according to any one of the preceding claims, wherein The sub-aperture ratio of the additional elements allocated is at least 0.

4.

7. The projection exposure apparatus according to any one of the preceding claims, wherein The at least one additional allocated optical element includes a lens element arranged in the front third of the projection lens, a lens element arranged in the back third of the projection lens, and / or a lens element arranged in front of the concave mirror.

8. The projection exposure apparatus according to any one of the preceding claims, The projection exposure device is configured to operate in the DUV wavelength range.

9. The projection exposure apparatus according to any one of the preceding claims, The projection exposure apparatus further includes a determining device configured to determine the distribution of thermal intensity input to the optical element by the exposure radiation during the exposure process.

10. The projection exposure apparatus according to any one of the preceding claims, wherein The control device is configured to control the manipulator such that the energy input is distributed in a spatially resolved manner over the optically effective area of ​​the optical element.

11. The projection exposure apparatus according to any one of the preceding claims, wherein, The control device is configured to achieve the energy input caused by the manipulator within a time period of up to 10% in the projection lens, during which a wavefront deviation corresponding to the reduction in thermal energy input is formed.

12. The projection exposure apparatus according to any one of the preceding claims, wherein The control device is configured to implement the thermal energy input for a period of at least 2 seconds.

13. The projection exposure apparatus according to any one of the preceding claims, wherein The optical element is configured as a flat plate with parallel planes.

14. The projection exposure apparatus according to any one of the preceding claims, wherein, The projection lens has multiple optical elements, each configured as a flat plate with a parallel plane.

15. The projection exposure apparatus according to any one of the preceding claims, wherein The manipulator includes a heating element for inputting the thermal energy into the optical element.

16. The projection exposure apparatus according to any one of the preceding claims, wherein The projection lens includes additional optical elements with manipulators configured to input thermal energy into the optical elements. The two optical elements, each equipped with a manipulator, are implemented as planar parallel plates, each plate having multiple heatable zones and being transparent optical plates.

17. The projection exposure apparatus according to claim 16, wherein The optical elements, each having a gap of at least 3 mm in width, are arranged between the optical elements, which are respectively configured as planar parallel plates.

18. The projection exposure apparatus according to any one of the preceding claims, wherein The manipulator includes an irradiation device for irradiating the optical element with thermal radiation.

19. A method for controlling a microlithography projection exposure apparatus, the microlithography projection exposure apparatus comprising a projection lens and a manipulator for at least one optical element of the projection lens, the manipulator being configured to selectively input thermal energy into the optical element so as not to significantly heat one of the other optical elements of the projection lens, the method comprising the steps of: - Control the exposure radiation used to project the mask structure onto the substrate plane. - Control the manipulator so that the effect on the optical properties of the projection lens caused by the reduction in thermal energy input to the projection lens due to exposure pause is at least partially compensated in a targeted manner by the energy input of the manipulator. The effect at least partially compensated by the energy input of the manipulator includes altering the wavefront aberration of the projection lens due to the exposure pause, and At least one additional optical element from the optical elements of the projection lens is assigned to the optical element equipped with the manipulator such that the sub-aperture ratio of the assigned additional optical element deviates from the sub-aperture ratio of the optical element equipped with the manipulator by a maximum value of 0.3, wherein the central thickness of the assigned additional optical element is at most 10 mm.

20. The method according to claim 19, It also includes determining the heat intensity distribution input to the optical element by the exposure radiation during the exposure process, and controlling the manipulator based on the determined heat intensity distribution.

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