WO2023208590A1

WO2023208590A1 - Supporting components of an optical device

Info

Publication number: WO2023208590A1
Application number: PCT/EP2023/059608
Authority: WO
Inventors: Ralf Zweering; Marwene Nefzi; Wolfgang Scherm; Jens Kugler; Stefan Hembacher; Andreas Raba
Original assignee: Carl Zeiss Smt Gmbh
Priority date: 2022-04-27
Filing date: 2023-04-13
Publication date: 2023-11-02
Also published as: DE102022204044A1; TW202401130A

Abstract

The present invention relates to an optical arrangement of a microlithographic imaging device, particularly for using light in the extreme UV (EUV) range, comprising a group of optical elements, a support structure (104.2), an active support device (108) and a control device (106). The group of optical elements comprises a plurality N of optical elements (M1 to M6) which are supported on the support structure (104.2) by way of the active support device (108). The active support device (108) comprises an active support unit (108.1, 108.2) for each optical element (M1 to M6) of the group of optical elements, which active support unit is configured to adjustably support the optical element (M1 to M6) on the support structure (104.2) under control device (106) control. The group of optical elements comprises a first subgroup with a plurality M of first optical elements (M2, M4, M5, M6) and a second subgroup with a number K of second optical elements (M1, M3). The control device (106) and a first active support unit (108.1) assigned to the respective first optical element (M2, M4, M5, M6) are configured to adjust the first optical element (M2, M4, M5, M6) in at least one degree of freedom with a maximum control bandwidth which is within a first control bandwidth range. Further, the control device (106) and a second active support unit (108.2) assigned to the respective second optical element (M1, M3) are configured to adjust and/or deform the second optical element (M1, M3) in at least one degree of freedom with a maximum control bandwidth which is within a second control bandwidth range. In this case, the first control bandwidth range is below the second control bandwidth range and spaced apart from the second control bandwidth range by an interval. The interval is at least 50%, preferably at least 100%, further preferably at least 125% of an upper limit of the first control bandwidth range and/or at least 40 Hz to 80 Hz, preferably 50 Hz to 175 Hz, further preferably 75 Hz to 125 Hz.

Description

SUPPORTING COMPONENTS OF AN OPTICAL DEVICE

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims benefit under 35 U.S.C. §119 of German patent application no. 102022 204 044.9, filed on 27 April 2022, the entire contents of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an optical arrangement of a microlithographic imaging device suitable for the use of used UV light, in particular light in the extreme ultraviolet (EUV) range. The invention further relates to an optical imaging device having such an optical arrangement, a method for supporting optical elements, and an optical imaging method. The invention can be used in conjunction with any desired optical imaging methods. It can be used particularly advantageously in the production or the inspection of microelectronic circuits and the optical components used for them (for example optical masks).

The optical devices used in conjunction with the production of microelectronic circuits typically comprise a plurality of optical element units comprising one or more optical elements, such as lens elements, mirrors or optical gratings, which are arranged in the imaging light path. Said optical elements typically cooperate in an imaging process in order to transfer an image of an object (for example a pattern formed on a mask) to a substrate (for example a so-called wafer). The optical elements are typically combined in one or more functional groups, which are optionally held in separate imaging units. In particular in the case of principally refractive systems that operate with a wavelength in the so-called vacuum ultraviolet range (VUV, for example at a wavelength of 193 nm), such imaging units are often formed from a stack of optical modules holding one or more optical elements. Said optical modules typically comprise a support structure having a substantially ring-shaped outer support unit, which supports one or more optical element holders, which in turn hold the optical element.

The ever-advancing miniaturization of semiconductor components results in a constant demand for increased resolution of the optical systems used for their production. This demand for increased resolution necessitates the demand for an increased numerical aperture (NA) and an increased imaging accuracy of the optical systems.

One approach for obtaining an increased optical resolution is to reduce the wavelength of the light used in the imaging process. The trend in recent years has increasingly fostered the development of systems in which light in the so-called extreme ultraviolet (EUV) range is used, typically at wavelengths of 5 nm to 20 nm, in most cases at a wavelength of approximately 13 nm. In this EUV range, it is no longer possible to use conventional refractive optical systems. This is owing to the fact that in this EUV range the materials used for refractive optical systems have an absorbance that is too high to achieve acceptable imaging results with the available light power. Consequently it is necessary to use reflective optical systems for the imaging, in this EUV range.

This transition to purely reflective optical systems having a high numerical aperture (e.g., NA > 0.4, optionally even NA > 0.5) in the EUV range results in considerable challenges with regard to the design of the imaging device.

The factors mentioned above result in very stringent requirements with regard to the position and/or orientation of the optical elements participating in the imaging relative to one another and also with regard to the deformation of the individual optical elements in order to achieve a desired imaging accuracy. Moreover, it is necessary to maintain this high imaging accuracy over operation in its entirety, ultimately over the lifetime of the system.

As a consequence, the components of the optical imaging device (i.e., for example, the optical elements of the illumination device, the mask, the optical elements of the projection device and the substrate) which cooperate during the imaging are supported in a well- defined manner in order to maintain a predetermined well-defined spatial relationship between these components and to obtain a minimal undesired deformation of these components in order ultimately to achieve the highest possible imaging quality.

The high numerical aperture is accompanied, inter alia, by the problem that this requires the use of optical elements with comparatively large dimensions, and these are associated with large masses or moments of inertia. As a result of these large masses or moments of inertia, it is very difficult to ensure the high dynamics, required for commercial use, during the highly precise positioning with respect to one another of the components involved with the optical imaging (in particular the optical elements of the projection device), in order ultimately to obtain the smallest possible imaging aberration or the highest possible imaging quality. To face the problem of larger and hence more sluggish components, WO 2013/004403 A1 (Kwan et al., the entire disclosure of which is incorporated herein by reference) has already proposed the practice of using the heaviest optical element as an inertial reference and ultimately aligning the other optical elements in relation to this particularly sluggish optical element. Although the optical element which forms this inertial reference is actively supported, it is supported only with a comparatively small maximum control bandwidth, while all remaining components must be aligned vis-a-vis this inertial reference with a significantly higher maximum control bandwidth. However, a problem here is that the outlay required to meet the requirements in respect of the control dynamics increases with the aforementioned increasing numerical aperture for these remaining optical elements, which likewise become ever larger.

BRIEF SUMMARY OF THE INVENTION

The invention is therefore based on the object of specifying an optical arrangement of a microlithographic imaging device suitable for the use of used UV light, in particular light in the extreme ultraviolet (EUV) range. The invention also relates to the provision of an optical imaging device having such an optical arrangement, a method for supporting optical elements, and an optical imaging method, which do not have the aforementioned disadvantages, or at least have these to a lesser extent, and, especially in a simple manner, reduce the outlay for the imaging device while keeping the imaging quality at least unchanged.

The invention achieves this object using the features of the independent claims.

The invention is based on the technical teaching that the outlay for the imaging device can easily be reduced while keeping the imaging quality at least unchanged if a plurality of optical elements, which are to be assigned to a first subgroup of the projection device and which are involved with imaging (for example of the pattern of a mask onto a substrate), are only supported with a comparatively low maximum control bandwidth. On account of the reduced dynamics of the adjustment of the optical elements of the first subgroup, this initially results in an increased imaging aberration, which emerges from a deviation of the optical elements of the first subgroup from their target state no longer being able to be corrected sufficiently quickly. Then, this imaging aberration is at least partially compensated by one or more further optical elements which are actuated with an appropriately high control bandwidth, which are likewise involved with the imaging, and which are to be assigned to a second subgroup of the projection device. The control bandwidth ranges of the maximum control bandwidth for the optical elements of the first and the second subgroup differ here by a noticeable interval, with the result that it is possible to obtain clearly perceivable savings in terms of the outlay for the optical elements of the first subgroup.

Thanks to their lower required maximum control bandwidth of actuation, the optical elements of the first subgroup can be configured to be correspondingly lighter and hence simpler. This also has a positive effect on the outlay required for the actuator system, that is to say for example the active support, of these optical elements. The support for the optical elements of the first subgroup realized thus can also be referred to as a floating support or low-stiffness support, since deviations from a target state are only reacted to comparatively slowly or sluggishly. Then, it may be typically sufficient to correspondingly precisely detect at least the pose (i.e., position and/or orientation) of these optical elements of the first subgroup in the degrees of freedom relevant to a high imaging quality (right up to all six degrees of freedom in space) and to subsequently use this information for driving the actuator system of the relevant optical element of the second subgroup.

The relevant optical element of the second subgroup then preferably is an optical element that is smaller and lighter in any case, and for which the required high dynamics of the actuation can be obtained with comparatively little outlay. The support for the optical elements of the second subgroup realized here can also be referred to as a high-stiffness support, since there is a comparatively quick or agile reaction to corresponding stipulations regarding a target state.

In this case, it may be sufficient for the second subgroup to comprise only a single optical element (i.e., a single correction element); however, a plurality of optical elements can also be used for correction purposes. The latter can be advantageous, in particular, inasmuch as the correction of different imaging aberrations is carried out by different correction elements, with the result that the complexity of the actuator system for these correction elements is reduced. However, the correction of a specific imaging aberration can likewise be distributed among a plurality of correction elements. This can also reduce the complexity of the actuator system for these correction elements. Express reference is made here to the fact that the term imaging aberration as used in the present description can, as appropriate, comprise a plurality of different types of aberrations which together describe the overall imaging quality of the imaging. To correct the imaging aberration, it may possibly be sufficient to impress a corresponding deformation of its optical surface onto the correction element or to appropriately set the pose of the correction element in terms of the relevant degrees of freedom (up to all six degrees of freedom in space). Naturally, a combined correction can likewise be realized by way of deformation and pose control. In this case, it is not mandatory for a complete correction of the imaging aberration to be realized solely by way of the correction element or correction elements. Likewise, further components involved in the imaging, for example the mask or the substrate (or their respective holding devices) can be used for correction purposes and the actuator system thereof can be controlled accordingly in order to obtain the smallest possible imaging aberration in the sum of the corrections (within the scope of the error budget specified for the individual imaging or imaging device).

It is further understood that, alone or in any combination, any relevant imaging aberration can be corrected; by way of example, this can be the known, so-called line-of-sight error (LoS error, that is to say a position error of the imaging of points of the object plane in relation to the target position in the image plane) and/or what are known as wavefront aberrations. The correction thereof can be obtained purely by an appropriate actuation of a correction element or by a concerted actuation of a plurality of correction elements and optionally further components (e.g., mask and/or substrate).

According to one aspect, the invention therefore relates to an optical arrangement of a microlithographic imaging device, particularly for using light in the extreme UV (EUV) range, comprising a group of optical elements, a support structure, an active support device, and a control device. The group of optical elements comprises a plurality N of optical elements which are supported on the support structure by way of the active support device. Here, the active support device comprises an active support unit for each optical element of the group of optical elements, which active support unit is configured to adjustably support the optical element on the support structure under control device control. The group of optical elements comprises a first subgroup with a plurality M of first optical elements and a second subgroup with a number K of second optical elements. The control device and a first active support unit assigned to the respective first optical element are configured to adjust the first optical element in at least one degree of freedom (up to all six degrees of freedom in space) with a maximum control bandwidth which is within a first control bandwidth range. Further, the control device and a second active support unit assigned to the respective second optical element are configured to adjust and/or deform the second optical element in at least one degree of freedom (up to all six degrees of freedom in space) with a maximum control bandwidth which is within a second control bandwidth range. The first control bandwidth range is below the second control bandwidth range and spaced apart from the second control bandwidth range by an interval. Here, the interval is at least 50%, preferably at least 100%, further preferably at least 125% of an upper limit of the first control bandwidth range and/or at least 40 Hz to 80 Hz, preferably 50 Hz to 175 Hz, further preferably 75 Hz to 125 Hz. In this way, it is advantageously possible to obtain a clearly noticeable reduction in the outlay for the optical elements of the first subgroup and the support thereof, while a sufficiently high imaging quality can be ensured at the same time.

In principle, the two control bandwidth ranges can be located as desired and can have a span (i.e. , variation of the maximum control bandwidth located therein) of any desired size for as long as it is possible to obtain a correspondingly noticeable reduction in the outlay for the optical elements of the first subgroup. In certain variants, the first control bandwidth range ranges from 50 Hz to 180 Hz, preferably from 75 Hz to 160 Hz, further preferably from 90 Hz to 120 Hz. Additionally or alternatively, the second control bandwidth range can range from 180 Hz to 260 Hz, preferably from 200 Hz to 250 Hz, further preferably from 220 Hz to 250 Hz. Both allow a noticeable reduction in the outlay for the optical elements of the first subgroup while maintaining a high imaging quality.

In certain variants, the control device is connected to a capturing device, wherein the capturing device is configured to capture first pose information at least for the first optical elements, the said pose information being representative for a respective position and/or orientation of the first optical element vis-a-vis a reference in at least one degree of freedom (up to all six degrees of freedom in space). In this respect, the sensor system typically already present in any case (for example for adjusting with a high control bandwidth) can easily be used, with the result that the outlay for this does not increase. The first pose information can then be used to realize the correction of the imaging aberration which arises from the reduced dynamics of the actuation of the first optical elements, by way of the appropriate actuation of at least one second optical element (and optionally further components involved with the imaging, as were explained above).

Additionally or alternatively, the capturing device can be configured to capture first deformation information at least for the first optical elements, the said deformation information being representative for a respective deformation of the first optical element in at least one degree of freedom. The procedure here can be analogous to the just described capturing and use of the first pose information, and so reference in this respect is made to the embodiments above. Capturing the deformation information is particularly advantageous inasmuch as large or heavy optical elements are nevertheless able to react with comparatively large deformations, which may have a significant influence on the imaging aberration, during operation, even in the case of a support with a reduced maximum control bandwidth (and consequently with reduced accelerations acting thereon).

Additionally or alternatively, the capturing device can also be configured to capture imaging aberration information which is representative for an imaging aberration of the imaging device. The procedure here, too, can be analogous to the just described capturing and use of the first pose information or first deformation information, and so reference in this respect likewise is made to the embodiments above.

In the aforementioned cases, the control device is then, as mentioned, configured to drive the at least one second active support unit on the basis of the first pose information and/or on the basis of the first deformation information and/or on the basis of the imaging aberration information.

In advantageous variants, the group of optical elements causes an imaging aberration of the imaging device during operation, wherein the control device is configured to drive the at least one second active support unit, alone or in combination with at least one further component of the imaging device, in an imaging aberration correction step so that the imaging aberration is at least reduced, in particular substantially eliminated. In principle, the imaging aberration can be corrected in any suitable manner by way of the corresponding actuation of at least one second active support unit and optionally at least one further component of the imaging device.

In certain variants, the imaging aberration is corrected in the imaging aberration correction step (optionally only) by way of a deformation of the at least one second optical element with the maximum control bandwidth (from the second control bandwidth range). To this end, the at least one second active support unit can have an active deformation unit which, driven by the control device, sets a deformation of the assigned second optical element in at least one degree of freedom (up to all six degrees of freedom in space) with the maximum control bandwidth for the second optical element. Consequently, what is known as a correction accuracy can be specified for the second optical element and then set by way of appropriate driving of the relevant second active support unit on the assigned second optical element.

It is understood here that the pose of the second optical element need not necessarily be set with a maximum control bandwidth from the second control bandwidth range. Rather, in these cases, it is also possible to adjust the pose of the second optical element with a maximum control bandwidth from the first control bandwidth range, that is to say only adjust the deformation of the second optical element with a maximum control bandwidth from the second control bandwidth range. Consequently, it thus may be the case that one or more optical elements are both part of the first subgroup (since the pose of the relevant optical element is adjusted with a maximum control bandwidth from the first control bandwidth range) and part of the second subgroup (since the deformation of the relevant optical element is adjusted with a maximum control bandwidth from the second control bandwidth range). In certain other variants, however, provision may also be made for the first and second subgroup to be mutually exclusive, consequently for the respective optical element to be part of only the first subgroup or only the second subgroup.

Additionally or alternatively, the imaging aberration however can also be corrected in the imaging aberration correction step (optionally only) by way of a pose adaptation of the at least one second optical element with the maximum control bandwidth (from the second control bandwidth range). To this end, the at least one second active support unit can have an active pose control unit which, driven by the control device, sets a position and/or orientation of the assigned second optical element in at least one degree of freedom with the maximum control bandwidth for the second optical element. Consequently, what is known as a correction pose can therefore also be specified for the second optical element and then set by way of appropriate driving of the relevant second active support unit on the assigned second optical element. In this context, it is understood that it is also possible to specify a superposition of correction accuracy and correction pose.

As already mentioned multiple times, the control device may naturally optionally undertake a further correction of the imaging aberration (on the basis of the aforementioned information captured by way of the capturing device) by actuating at least one further component of the imaging device (e.g., an object device such as a mask device, and/or an image device like a substrate device), in order overall to obtain a desired low imaging aberration of the imaging. In preferred variants, the at least one further component of the imaging device is an image device (e.g., a substrate device) or an object device (e.g., a mask device) of the imaging device.

The control information required for driving the relevant second active support unit (and optionally the further component) can be determined in any desired way as a matter of principle. Preferably, a stored correction model is used by the control device in the imaging aberration correction step for the purpose of driving the at least one second active support unit and, optionally, the at least one further component of the imaging device in order to at least reduce, in particular substantially eliminate, the imaging aberration. In this case, the correction model can supply, on the basis of the first pose information, control information for driving the at least one second active support unit. Additionally or alternatively, the correction model can supply, on the basis of the first deformation information, control information for driving the at least one second active support unit. Likewise, the correction model can additionally or alternatively supply, on the basis of the imaging aberration information, control information for driving the at least one second active support unit. In this case, the correction model may optionally supply, in each case on the basis of the first pose information and/or first deformation information and/or imaging aberration information, control information for driving an active third support unit of the at least one further component of the imaging device. In this way, a correction or reduction of the entire imaging aberration that is as comprehensive as possible can be obtained in a particularly simple and cost-effective manner.

In principle, the correction model may have been determined in any suitable desired way. Thus, it may have been created purely theoretically on the basis of pure numerical modelling of the optical arrangement and optionally the entire imaging device. Likewise, it may have been created on the basis of measurements on an optical arrangement and optionally an entire imaging device (wherein this relates at least to a comparable or structurally identical optical arrangement or imaging device, but preferably the specific optical arrangement or imaging device itself). Naturally, mixed forms of these two extremes are possible and typically particularly advantageous.

In principle, the correction model can be a static model which remains unchanged, at least over a relatively long period of operation. Preferably, this is an adaptive model which is intermittently adapted to the actual conditions of the optical arrangement or imaging device. In the process, it is possible to implement in particular a self-adapting algorithm which, triggered by certain temporal events (e.g., at certain specified intervals) and/or by nontemporal events (start and/or end of operation, setting change of the illumination device and/or projection device, reaching certain specified operating parameters, for example the temperature at certain components, exceeding an imaging aberration tolerance, etc.), checks the effectiveness of the correction of the imaging aberration and undertakes a corresponding correction of the correction model.

In certain advantageous variants, the control device is consequently configured to correct the correction model in a model correction step on the basis of at least one imaging aberration information item, which emerges from a preceding imaging aberration correction step, in particular on the basis of the imaging aberration information emerging from the directly preceding imaging aberration correction step. In the process, it is optionally also possible for a plurality of imaging aberration information items AFI from a plurality of (optionally directly) successive capturing steps to be included in the correction, for example in order to take account of the development of the imaging aberration over time, and to adequately correct the correction model. Then, the control device is configured to use the correction model corrected in the most recent preceding model correction step in the imaging aberration correction step. In this way, it is possible to realize an adaptive correction model KM in a particularly advantageous manner.

It is understood that the capturing device can only capture the corresponding aforementioned capturing variables or information for the first subgroup as a matter of principle and that these can be used for actuating the second subgroup and optionally the further component(s). However, preferably there is also analogous capturing at the second subgroup or for the second subgroup in order to obtain a particularly advantageous and effective correction.

In certain variants, the capturing device is consequently configured to capture second pose information for the at least one second optical element, the said pose information being representative for a position and/or orientation of the at least one second optical element vis- a-vis a reference in at least one degree of freedom (up to all six degrees of freedom in space). Additionally or alternatively, the capturing device can be configured to capture second deformation information for the at least one second optical element, the said deformation information being representative for a deformation of the at least one second optical element in at least one degree of freedom (up to all six degrees of freedom in space). In this context, the control device then is configured in each case to drive the at least one second active support unit on the basis of the second pose information and/or on the basis of the second deformation information.

In certain variants with the above-described correction model, the correction model then supplies, on the basis of the second pose information, the control information for driving the at least one second active support unit. Additionally or alternatively, the correction model can supply, on the basis of the second deformation information, the control information for driving the at least one second active support unit. In this case, provision can in particular be made once again for the control device to be configured to correct, in a model correction step, the correction model on the basis of the imaging aberration information from a preceding imaging aberration correction step, in particular to carry out this correction on the basis of the imaging aberration information from the immediately preceding imaging aberration correction step. Then, the control device is configured to use the correction model corrected in the model correction step in the imaging aberration correction step.

As a matter of principle, the optical arrangement described herein can be used in imaging devices of any design or composition. In particular, the group of optical elements may comprise any desired number of optical elements. The same applies to the division of the group of optical elements into the first and the second subgroup. Preferably the plurality N is equal to 2 to 12, preferably equal to 4 to 10, more preferably equal to 6 to 8. Additionally or alternatively, the plurality M can be equal to 2 to 10, preferably be equal to 3 to 8, more preferably be equal to 4 to 6. Additionally or alternatively, the number K can finally be equal to 1 to 12, preferably be equal to 4 to 10, more preferably be equal to 6 to 8. Consequently, for example, a single correction element may therefore be sufficient to obtain the desired small imaging aberration (optionally together with the described actuation of one or more further components). In any event, all these cases lead to particularly advantageous set-ups, in which small imaging aberrations are possible with comparatively little outlay for the first subgroup.

The optical elements can be assigned to the first and the second subgroup according to any desired criteria as a matter of principle. Typically, elements whose adjustment with a maximum control bandwidth from the second control bandwidth range was found to be particularly difficult are assigned to the first subgroup. Further, it is possible to assign certain optical elements to the first subgroup even though they could be actuated with a maximum control bandwidth from the second control bandwidth range. This can realize a reduction in the outlay even for those optical elements. As already mentioned, in the case of the second subgroup it may optionally also be possible to adjust the pose of the second optical element with a maximum control bandwidth from the first control bandwidth range, that is to say in that case only adjust the deformation of the second optical element with a maximum control bandwidth from the second control bandwidth range.

Particularly advantageous set-ups arise if the first subgroup comprises the largest optical element of the group of optical elements and/or the heaviest optical element of the group of optical elements. Additionally or alternatively, the first subgroup may comprise the second largest optical element of the group of optical elements and/or the second heaviest optical element of the group of optical elements. Likewise additionally or alternatively, the second subgroup may comprise the smallest optical element of the group of optical elements and/or the lightest optical element of the group of optical elements. Additionally or alternatively, the second subgroup may comprise the second smallest optical element of the group of optical elements and/or the second lightest optical element of the group of optical elements.

The present invention also relates to an optical imaging device, in particular a microlithographic optical imaging device, comprising an illumination device having a first optical element group, an object device for receiving an object, a projection device having a second optical element group and an image device. The illumination device is configured to illuminate the object while the projection device is configured to project an image of the object onto the image device. In this case, the projection device comprises at least one optical arrangement according to the invention, as has been described above. This makes it possible to realize the variants and advantages described above in relation to the optical arrangement to the same extent, and so reference is made to the explanations given above in this respect in order to avoid repetition.

The present invention further relates to a method for supporting a group of optical elements on a support structure of a microlithographic imaging device, in particular for using light in the extreme UV (EUV) range, wherein the group of optical elements comprises a plurality N of optical elements which are supported on the support structure by way of the active support device, wherein the group of optical elements comprises a first subgroup with a plurality M of first optical elements and a second subgroup with a number K of second optical elements. Each optical element of the group of optical elements is adjustably supported on the support structure by way of an active support unit. In this case, the respective first optical element is adjusted in at least one degree of freedom by way of an assigned first active support unit with a maximum control bandwidth which is within a first control bandwidth range. The respective second optical element is adjusted and/or deformed in at least one degree of freedom by way of an assigned second active support unit with a maximum control bandwidth which is within a second control bandwidth range. The first control bandwidth range is below the second control bandwidth range and spaced apart from the second control bandwidth range by an interval. The interval is at least 50%, preferably at least 100%, further preferably at least 125% of an upper limit of the first control bandwidth range and/or at least 40 Hz to 80 Hz, preferably 50 Hz to 175 Hz, further preferably 75 Hz to 125 Hz. This makes it possible to realize the variants and advantages described above in relation to the optical arrangement to the same extent, and so reference is made to the explanations given above in this respect in order to avoid repetition.

The present invention also relates to an optical imaging method, in particular for microlithography, wherein an illumination device which has a first optical element group illuminates an object and a projection device which has a second optical element group projects an image representation of the object onto an image device. In this case, at least the optical elements of the second optical element group of the projection device are supported by means of a method according to the invention for supporting a group of optical elements. This also makes it possible to realize the variants and advantages described above in relation to the optical arrangement to the same extent, and so reference is made to the explanations given above in this respect in order to avoid repetition.

Further aspects and exemplary embodiments of the invention are evident from the dependent claims and the following description of preferred exemplary embodiments, which refers to the accompanying figures. All combinations of the disclosed features, irrespective of whether or not they are the subject of a claim, lie within the scope of protection of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic illustration of a preferred embodiment of a projection exposure apparatus according to the invention, which comprises a preferred embodiment of an optical arrangement according to the invention and with which a preferred embodiment of the imaging method according to the invention can be carried out using a preferred embodiment of the method according to the invention for supporting optical elements.

Figure 2 is a flowchart of a preferred embodiment of the imaging method according to the invention, which can be carried out by the projection exposure apparatus from Figure 1 using a preferred embodiment of the method according to the invention for supporting optical elements.

DETAILED DESCRIPTION OF THE INVENTION

Preferred exemplary embodiments of a microlithographic projection exposure apparatus 101 according to the invention, which comprises a preferred exemplary embodiment of an optical arrangement according to the invention, are described below with reference to Figures 1 and 2. To simplify the following explanations, an x, y, z coordinate system is indicated in the drawings, the z direction running parallel to the direction of gravitational force. Accordingly, the x-direction and the y-direction run horizontally, with the x-direction running perpendicularly into the plane of the drawing in the illustration in Figure 1. It goes without saying that it is possible in further configurations to choose any desired other orientations of an x, y, z coordinate system.

The essential integral parts of a projection exposure apparatus 101 are described in exemplary fashion below initially with reference to Figure 1. The description of the basic structure of the projection exposure apparatus 101 and its components should not be construed as limiting here.

An illumination device or an illumination system 102 of the projection exposure apparatus 101 comprises, in addition to a radiation source 102.1 , an optical element group in the form of illumination optical unit 102.2 for illuminating an object field 103.1 (shown schematically). The object field 103.1 lies in an object plane 103.2 of an object device 103. A reticle 103.3 (also referred to as a mask) arranged in the object field 103.1 is illuminated in this case. The reticle 103.3 is held by a reticle holder 103.4. The reticle holder 103.4 is displaceable by way of a reticle displacement drive 103.5, in particular in one or more scanning directions. In the present example, such a scanning direction runs parallel to the y-axis.

The projection exposure apparatus 101 furthermore comprises a projection device 104 with a further optical element group in the form of projection optical unit 104.1. The projection optical unit 104.1 serves for imaging the object field 103.1 into an image field 105.1 (as depicted schematically), which is located in an image plane 105.2 of an image device 105.

The image plane 105.2 extends parallel to the object plane 103.2. Alternatively, an angle that differs from 0° is also possible between the object plane 103.2 and the image plane 105.2.

During exposure, a structure of the reticle 103.3 is imaged onto a light-sensitive layer of a substrate in the form of a wafer 105.3, the light-sensitive layer being arranged in the image plane 105.2 in the region of the image field 105.1. The wafer 105.3 is held by a substrate holder or wafer holder 105.4. The wafer holder 105.4 is displaceable by way of a wafer displacement drive 105.5, in particular in the y-direction. The displacement, firstly, of the reticle 103.3 by way of the reticle displacement drive 103.5 and, secondly, of the wafer 105.3 by way of the wafer displacement drive 105.5 may be implemented so as to be mutually synchronized. This synchronization can be implemented, for example, by way of a common control device 106 (shown only very schematically in Figure 1 and without control paths).

The radiation source 102.1 is an EUV radiation (extreme ultraviolet radiation) source. The radiation source 102.1 emits EUV radiation 107 in particular, which is also referred to below as used radiation or illumination radiation. In particular, the used radiation has a wavelength in the range between 5 nm and 30 nm, in particular a wavelength of approximately 13 nm. The radiation source 102.1 can be a plasma source, for example an LPP (laser produced plasma) source or a GDPP (gas discharge produced plasma) source. It may also be a synchrotron-based radiation source. However, the radiation source 102.1 can also be a free electron laser (FEL).

Since the projection exposure apparatus 101 operates with used light in the EUV range, the optical elements used are exclusively reflective optical elements. In further configurations of the invention, it is also possible (in particular depending on the wavelength of the illumination light), of course, to use any type of optical elements (refractive, reflective, diffractive) alone or in any desired combination for the optical elements.

The illumination radiation 107 emerging from the radiation source 102.1 is focused by a collector 102.3. The collector 102.3 may be a collector with one or more ellipsoidal and/or hyperboloidal reflection surfaces. The illumination radiation 107 can be incident on the at least one reflection surface of the collector 102.3 with grazing incidence (Gl), that is to say at angles of incidence of greater than 45°, or with normal incidence (Nl), that is to say at angles of incidence of less than 45°. The collector 11 can be structured and/or coated on the one hand for optimizing its reflectivity for the used radiation and on the other hand for suppressing extraneous light.

Downstream of the collector 102.3, the illumination radiation 107 propagates through an intermediate focus in an intermediate focal plane 107.1. In certain variants, the intermediate focal plane 107.1 can represent a separation between the illumination optical unit 102.2 and a radiation source module 102.4, which comprises the radiation source 102.1 and the collector 102.3.

Along the beam path, the illumination optical unit 102.2 includes a deflection mirror 102.5 and a downstream first facet mirror 102.6. The deflection mirror 102.5 may be a plane deflection mirror or, alternatively, a mirror with a beam-influencing effect going beyond a pure deflection effect. Alternatively or additionally, the deflection mirror 102.5 can be configured as a spectral filter which at least partially separates what is known as extraneous light from the illumination radiation 107, the wavelength of which extraneous light differs from the used light wavelength. If the optically effective surfaces of the first facet mirror 102.6 are arranged in the region of a plane of the illumination optical unit 102.2 which is optically conjugate to the object plane 103.2 as a field plane, the first facet mirror 102.6 is also referred to as a field facet mirror. The first facet mirror 102.6 comprises a multiplicity of individual first facets

102.7, which are also referred to as field facets below. These first facets and their optical surfaces are indicated only very schematically in Figure 1 by the dashed contour 102.7.

The first facets 102.7 may be embodied as macroscopic facets, in particular as rectangular facets or as facets with an arcuate edge contour or an edge contour of part of a circle. The first facets 102.7 may be embodied as facets with a plane optical surface or alternatively with a convexly or concavely curved optical surface.

As known for example from DE 102008 009 600 A1(the entire disclosure of which is incorporated herein by reference), the first facets 102.7 themselves can also be composed in each case of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. The first facet mirror 102.6 can in particular be configured as a microelectromechanical system (MEMS system), as is described in detail in DE 102008 009600 A1, for example.

In the present example, the illumination radiation 107 travels horizontally, that is to say in the y-direction, between the collector 102.3 and the deflection mirror 102.5. It goes without saying, however, that in the case of other variants different alignments may also be chosen.

In the beam path of the illumination optical unit 102.2, a second facet mirror 102.8 is arranged downstream of the first facet mirror 102.6. If the optically effective surfaces of the second facet mirror 102.8 are arranged in the region of a pupil plane of the illumination optical unit 102.2, the second facet mirror 102.8 is also referred to as a pupil facet mirror. The second facet mirror 102.8 can also be arranged at a distance from a pupil plane of the illumination optical unit 102.2. In this case, the combination of the first facet mirror 102.6 and the second facet mirror 102.8 is also referred to as a specular reflector. Such specular reflectors are known, for example, from US 2006/0132747 A1, EP 1 614 008 B1 or US 6,573,978 (the respective entire disclosure of which is incorporated herein by reference).

The second facet mirror 102.8 in turn comprises a plurality of second facets, which are indicated only very schematically in Figure 1 by the dashed contour 102.9. In the case of a pupil facet mirror, the second facets 102.9 are also referred to as pupil facets. In principle, the second facets 102.9 can have the same design as the first facets 102.7. In particular, the second facets 102.9 can likewise be macroscopic facets, which can have a round, rectangular or hexagonal edge, for example. Alternatively, the second facets 102.9 can be facets composed of micromirrors. The second facets 102.9 in turn may have plane reflection surfaces or alternatively reflection surfaces with convex or concave curvature. In this regard, reference is made anew to DE 102008 009600 A1.

In the present example, the illumination optical unit 102.2 consequently forms a doubly faceted system. This basic principle is also referred to as fly's eye integrator. In certain variants, it may furthermore be advantageous to arrange the optical surfaces of the second facet mirror 102.8 not exactly in a plane which is optically conjugate to a pupil plane of the projection optical unit 104.1.

In a further embodiment, not shown, of the illumination optical unit 102.2, a transfer optical unit 102.10 (depicted only schematically) contributing in particular to the imaging of the first facets 102.7 into the object field 103.1 may be arranged in the beam path between the second facet mirror 102.8 and the object field 103.1. The transfer optical unit 102.10 may have exactly one mirror, or alternatively have two or more mirrors, which are arranged one behind the other in the beam path of the illumination optical unit 102.2. The transfer optical unit 102.10 may in particular comprise one or two normal-incidence mirrors (Nl mirrors) and/or one or two grazing-incidence mirrors (Gl mirrors).

In the embodiment as shown in Figure 1, the illumination optical unit 102.2 has exactly three mirrors downstream of the collector 102.3, specifically the deflection mirror 102.5, the first facet mirror 102.6 (e.g., a field facet mirror), and the second facet mirror 102.8 (e.g., a pupil facet mirror). In a further embodiment of the illumination optical unit 102.2, there is also no need for the deflection mirror 102.5, and so the illumination optical unit 102.2 may then have exactly two mirrors downstream of the collector 102.3, specifically the first facet mirror 102.6 and the second facet mirror 102.8.

With the aid of the second facet mirror 102.8, the individual first facets 102.7 are imaged into the object field 103.1. The second facet mirror 102.8 is the last beam-shaping mirror or actually the last mirror for the illumination radiation 107 in the beam path upstream of the object field 103.1. The imaging of the first facets 102.7 into the object plane 103.2 by means of the second facets 102.9 or using the second facets 102.9 and a transfer optical unit 102.10 is often only approximate imaging.

The projection optical unit 104.1 comprises a plurality of mirrors Mi, which are numbered in accordance with their arrangement along the beam path of the projection exposure apparatus 101. In the example illustrated in Figure 1, the projection optical unit 104.1 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve or any other number of mirrors Mi are likewise possible. The penultimate mirror M5 and the last mirror M6 may each have a passage opening (not depicted in any more detail) for the illumination radiation 107. In the present example, the projection optical unit 104.1 is a doubly obscured optical unit. The projection optical unit 104.1 has an image-side numerical aperture NA which is greater than 0.5. In particular, the image-side numerical aperture NA may also be greater than 0.6. By way of example, the image-side numerical aperture NA may be 0.7 or 0.75.

The reflection surfaces of the mirrors Mi may be in the form of freeform surfaces without an axis of rotational symmetry. Alternatively, the reflection surfaces of the mirrors Mi may be configured as aspheric surfaces with exactly one axis of rotational symmetry of the reflection surface shape. Just like the mirrors of the illumination optical unit 102.2, the mirrors Mi can have highly reflective coatings for the illumination radiation 107. These coatings can be constructed from a plurality of coatings (multilayer coatings); in particular, they may be configured with alternating layers of molybdenum and silicon.

In the present example, the projection optical unit 104.1 has a large object-image offset in the y-direction between a y-coordinate of a centre of the object field 103.1 and a y-coordinate of the centre of the image field 105.1. This object-image offset in the y-direction can be of approximately the same magnitude as a distance between the object plane 103.2 and the image plane 105.2 in the z-direction.

The projection optical unit 104.1 may in particular have an anamorphic form. In particular, it has different imaging scales px, y in the x- and y-directions. The two imaging scales px, Py of the projection optical unit 104.1 are preferably (Px, Py) = (+/-0.25, +/-0.125). A positive imaging scale p means imaging without image inversion. A negative sign for the imaging scale p means imaging with image inversion. In the present example, the projection optical unit 104.1 consequently leads to a reduction in size with a ratio of 4:1 in the x-direction, that is to say in a direction perpendicular to the scanning direction. By contrast, the projection optical unit 104.1 leads to a reduction in size of with a ratio of 8:1 in the y-direction, that is to say in the scanning direction. Other imaging scales are likewise possible. Imaging scales with the same sign and the same absolute value in the x-direction and y-direction are also possible, for example with absolute values of 0.125 or of 0.25.

The number of intermediate image planes in the x-direction and in the y-direction in the beam path between the object field 103.1 and the image field 105.1 can be the same. Likewise, the number of intermediate image planes may also differ, depending on the design of the projection optical unit 104.1. Examples of projection optical units with differing numbers of such intermediate images in the x- and y-directions are known, for example, from US 2018/0074303 A1 (the entire disclosure of which is incorporated herein by reference).

In each case one of the pupil facets 102.9 in the present example is assigned to exactly one of the field facets 102.7 for forming in each case an illumination channel for illuminating the object field 103.1. This may in particular produce illumination according to the Kohler principle. The far field is decomposed into a multiplicity of object fields 103.1 with the aid of the field facets 102.7. The field facets 102.7 generate a plurality of images of the intermediate focus on the pupil facets 102.9 respectively assigned thereto.

The field facets 102.7 are each imaged onto the reticle 103.3 by an assigned pupil facet 102.9, with the image representations being overlaid such that there is thus an overlaid illumination of the object field 103.1. The illumination of the object field 103.1 is preferably as homogeneous as possible. It preferably has a uniformity error of less than 2%. The field uniformity can be achieved by way of the overlay of different illumination channels.

The illumination of the entrance pupil of the projection optical unit 104.1 can be defined geometrically by way of an arrangement of the pupil facets 102.9. The intensity distribution in the entrance pupil of the projection optical unit 104.1 can be set by selecting the illumination channels, in particular the subset of the pupil facets 102.9 which guide light. This intensity distribution is also referred to as illumination setting of the illumination system 102. A likewise preferred pupil uniformity in the region of sections of an illumination pupil of the illumination optical unit 102.2 which are illuminated in a defined manner may be achieved by a redistribution of the illumination channels. In the case of actively adjustable facets, the aforementioned settings can be made in each case by corresponding control by way of the control device 106.

Further aspects and details of the illumination of the object field 103.1 and in particular of the entrance pupil of the projection optical unit 104.1 are described below.

The projection optical unit 104.1 may have in particular a homocentric entrance pupil. The latter can be accessible or else be inaccessible. The entrance pupil of the projection optical unit 104.1 frequently cannot be exactly illuminated using the pupil facet mirror 102.8. In the case of imaging of the projection optical unit 104.1 which telecentrically images the centre of the pupil facet mirror 102.8 onto the wafer 105.3, the aperture rays often do not intersect at a single point. However, it is possible to find an area in which the spacing of the aperture rays determined in pairs becomes minimal. This area represents the entrance pupil or an area in real space that is conjugate thereto. In particular, this area has a finite curvature.

It may be the case for certain variants that the projection optical unit 104.1 has different poses of the entrance pupil for the tangential beam path and for the sagittal beam path. In this case, it is preferable for an imaging optical element, in particular an optical component part of the transfer optical unit 102.10, to be provided between the second facet mirror 102.8 and the reticle 103.3. With the aid of this imaging optical element, the different poses of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

With the arrangement of the components of the illumination optical unit 102.2, as shown in Figure 1 , the optical surfaces of the pupil facet mirror 102.8 are arranged in a surface that is conjugate to the entrance pupil of the projection optical unit 104.1. The first facet mirror 102.6 (field facet mirror) defines a first main plane of extent of its optical surfaces, which is arranged tilted to the object plane 5 in the present example. In the present example, this first main plane of extent of the first facet mirror 102.6 is arranged tilted to a second main plane of extent, which is defined by the optical surface of the deflection mirror 102.5. In the present example, the first main plane of extent of the first facet mirror 102.6 is also arranged tilted to a third main plane of extent, which is defined by the optical surfaces of the second facet mirror 102.8.

By way of example, the illumination device 102 and/or the projection device 104 may comprise one or more optical arrangements 108 according to the invention, as is described below.

The projection device 104 forms an optical arrangement according to the invention with a group G of optical elements in the form of the projection optical unit 104.1 , which is formed by a plurality N = 6 of optical elements, specifically the mirrors Mi, that is to say the mirrors M1 to M6 in this case. The respective mirror M1 to M6 is supported by an active support device 108 on a support structure 104.2 (only indicated very schematically) of the projection device 104. In this case, the active support device 108 comprises an active support unit 108.1, 108.2 for each optical element M1 to M6 of the group G of optical elements, which active support unit is configured to adjustably support the respective optical element M1 to M6 on the support structure 104.2 under control device 106 control.

In the present example, the group G of optical elements M1 to M6 of the projection optical unit 104.1 comprises a first subgroup UG1 with a plurality M = 4 of first optical elements and a second subgroup UG2 with a number K = 2 of second optical elements. In the present example, the mirrors M2, M4, M5 and M6 belong to the first subgroup UG1 while the mirrors M1 and M3 belong to the second subgroup UG2. It goes without saying that in the case of other variants any other assignment may also be provided. By way of example, the mirror M1 may also be assigned to the first subgroup UG1 in that case, with the result that the second subgroup UG2 then only consists of the mirror M3.

As will be explained below on the basis of the mirror M6 and the assigned first active support unit 108.1, the control device 106 and the first active support unit 108.1 assigned to the respective first optical element M2, M4, M5, M6 (the active support units have not been depicted for mirrors M2, M4, M5 for reasons of clarity) are configured to adjust the first optical element M2, M4, M5, M6 in at least one degree of freedom DOF (up to all six degrees of freedom DOF in space) with a maximum control bandwidth RBM1 which is within a first control bandwidth range RBB1. As will further be explained below on the basis of the mirror M3 and the assigned second active support unit 108.2, the control device 106 and the second active support unit 108.2 assigned to the respective second optical element M1 , M3 are configured to adjust and/or deform the second optical element M1, M3 in at least one degree of freedom DOF (up to all six degrees of freedom DOF in space) with a maximum control bandwidth RBM2 which is within a second control bandwidth range RBB2. In this case, it is understood that maximum control bandwidths RBM1 and RBM2 which differ from one another in each case as desired can be provided for the optical elements M1 to M6, depending on the requirements of the imaging device. Likewise, however, the same maximum control bandwidth RBM1 or RBM2 may also be provided for each optical element of the respective subgroup UG1 and UG2.

The first control bandwidth range RBB1 is below the second control bandwidth range RBB2 and spaced apart from the second control bandwidth range RBB2 by an interval RBA. Here, the interval RBA is at least 50%, preferably at least 100%, further preferably at least 125% of an upper limit of the first control bandwidth range RBB1 and/or at least 40 Hz to 80 Hz, preferably 50 Hz to 175 Hz, further preferably 75 Hz to 125 Hz.

Consequently, the first optical elements M2, M4, M5, M6 of the first subgroup UG1 are supported with a comparatively small maximum control bandwidth RBM1. On account of the reduced dynamics of the adjustment of the optical elements M2, M4, M5, M6 of the first subgroup UG1 , this initially results in an increased imaging aberration, which emerges from a deviation of the optical elements M2, M4, M5, M6 of the first subgroup UG1 from their target state no longer being able to be corrected sufficiently quickly. As will still be explained below, this imaging aberration is then at least partially compensated for by the optical elements M1, M3 of the one second subgroup UG2, which are actuated with a correspondingly high control bandwidth RBM2.

Thanks to their lower required maximum control bandwidth RBM1 of actuation, the optical elements M2, M4, M5, M6 of the first subgroup UG1 can be configured to be correspondingly lighter and hence simpler. This also has a positive effect on the outlay required to operate their assigned actuator system, that is to say the respective first active support unit 108.1. In this way, it is advantageously possible to obtain a clearly noticeable reduction in the outlay for the optical elements M2, M4, M5, M6 of the first subgroup UG1 and the support thereof (i.e. , the first active support units 108.1), while a sufficiently high imaging quality can be ensured at the same time.

The relevant optical element M1, M3 of the second subgroup UG2 in the present example is an optical element that is smaller and lighter in any case, and for which the required high dynamics of the actuation for a compensation of the imaging aberration by way of the second active support units 108.2 can be obtained with comparatively little outlay.

In principle, the two control bandwidth ranges RBB1 and RBB2 can be located as desired and can have a span (i.e., variation of the maximum control bandwidth RBB1 or RBB2 located therein) of any desired size for as long as it is possible to obtain a correspondingly noticeable reduction in the outlay for the optical elements M2, M4, M5, M6 of the first subgroup UG1. In certain variants, the first control bandwidth range RBB1 ranges from 50 Hz to 180 Hz, preferably from 75 Hz to 160 Hz, further preferably from 90 Hz to 120 Hz. Additionally or alternatively, the second control bandwidth range RBB2 can range from 180 Hz to 260 Hz, preferably from 200 Hz to 250 Hz, further preferably from 220 Hz to 250 Hz. Both allow a noticeable reduction in the outlay for the optical elements M2, M4, M5, M6 of the first subgroup UG1 while maintaining a high imaging quality.

In the present example, the control device 106 is connected to a capturing device 109 (only depicted very schematically in Figure 1), wherein the capturing device 109 is configured in conventional fashion to capture first pose information LI1 at least for the first optical elements M2, M4, M5, M6, the said pose information being representative for a respective position and/or orientation of the first optical element M2, M4, M5, M6 vis-a-vis a reference R in at least one degree of freedom DOF (up to all six degrees of freedom DOF in space). In this respect, the sensor system 109 typically already present in conventional imaging devices in any case (for example for adjusting with a high control bandwidth) can easily be used, with the result that the outlay for this does not increase.

In the present example, the first pose information LI1 is used to realize the correction of the imaging aberration, which emerges from the reduced dynamics of the actuation of the first optical elements M2, M4, M5, M6, by way of the appropriate actuation of the second optical elements M1 , M3 via the second active support units 108.2 and optionally via the corresponding actuation of further components (for example the object device 103 and/or the image device 105) involved with the imaging, as was explained above.

It may be sufficient to only capture the first pose information LI1 and use the latter for driving the second active support units 108.2. However, in the present example, the capturing device 109 is also configured to capture first deformation information DI1 at least for the first optical elements M2, M4, M5, M6, the said deformation information being representative for a respective deformation of the first optical element M2, M4, M5, M6 in at least one degree of freedom (up to all six degrees of freedom in space). The procedure here can be analogous to the just described capturing and use of the first pose information L11 , and so reference in this respect is made to the embodiments above. Capturing the deformation information DI1 is particularly advantageous inasmuch as large or heavy optical elements (such as the mirrors M2 and M6, for example) are nevertheless able to react with comparatively large deformations, which may have a significant influence on the imaging aberration, during operation, even in the case of a support with a reduced maximum control bandwidth RBM1 (and consequently with reduced accelerations acting thereon).

Further, the capturing device 109 of the present example is also configured to capture imaging aberration information AFI, which is representative of an imaging aberration of the imaging device. The procedure here, too, can be analogous to the just described capturing and use of the first pose information LI1 or first deformation information DI1 , and so reference in this respect likewise is made to the embodiments above.

In the present example, the control device 106 is configured to drive the second active support units 108.2 in an imaging aberration correction step on the basis of the first pose information L11 , the first deformation information DI1 and the imaging aberration information AFI in order to keep the imaging aberration of the projection exposure apparatus 101 overall as low as possible. In the process, the control device 106 can drive the second active support units 108.2 also in combination with at least one further component of the projection exposure apparatus 101 , for example the object device 103 and/or the image device 105, in order to at least reduce, in particular substantially eliminate, the imaging aberration of the projection exposure apparatus 101. This will be explained briefly below on the basis of the flowchart in Figure 2.

As may be gathered from Figure 2, the procedure is initially started in a step 110.1. Then, a check is carried out in a step 110.2 as to whether imaging should take place. Should this be the case, the above-described first pose information LI1 and the first deformation information DI1 are determined in a step 110.3. As will still be explained in more detail below, a stored correction model KM is then used in a step 110.4 to determine, in the control device 106, correction information KI from the information of the capturing device 109. The control device 106 then uses this correction information KI in the imaging aberration correction step 110.5 to correctively drive the second active support units 108.2, optionally in combination with at least one further component of the projection exposure apparatus 101, for example the object device 103 and/or the image device 105, before or while an image representation is generated in an imaging step 110.6. Whether the actual imaging aberration of the projection exposure apparatus 101 is within certain specified tolerances or whether this is not the case and therefore a model correction of the correction model KM is required is captured in a step 110.7 in parallel with or after the imaging step 110.6. Should such a model correction be required, it is carried out in a step 110.9 on the basis of the imaging aberration of the projection exposure apparatus 101 captured in step 110.7. In both cases, a check is then carried out in a step 110.10 as to whether the procedure should be terminated. Should this be the case, the procedure is ended in a step 110.11. Otherwise, there is a jump back to step 110.2.

In certain variants, the imaging aberration is corrected in the imaging aberration correction step 110.5 (optionally only) by way of a deformation of at least one of the second optical elements M1, M3 with the maximum control bandwidth RBM2 (from the second control bandwidth range RBB2). To this end, the relevant second active support unit 108.2 has an active deformation unit (not depicted in any more detail) which, driven by the control device 106, sets a deformation of the assigned second optical element M1 or M3 in at least one degree of freedom DOF (up to all six degrees of freedom DOF) with the maximum control bandwidth RBM2 for the second optical element M1 or M3. Consequently, the control device 106 in the process specifies what is known as a correction accuracy KP for the second optical element M1 or M3, which is then set on the assigned second optical element M1 or M3 by way of appropriate driving of the relevant second active support unit 108.2 (by way of the control device 106). It is understood here that the pose of the second optical element M1 or M3 need not necessarily be set with a maximum control bandwidth RBM2 from the second control bandwidth range RBB2. Rather, in these cases, it is also possible to adjust the pose of the relevant second optical element M1 or M3 with a maximum control bandwidth RBM from the first control bandwidth range RBB1 , that is to say only adjust the deformation of the second optical element M1 or M3 with a maximum control bandwidth RBM2 from the second control bandwidth range RBB2.

However, it is understood that the imaging aberration however can also be corrected in the imaging aberration correction step 110.5 (optionally only) by way of pose adjustment of the relevant second optical element M1 or M3 with the maximum control bandwidth RBM2 from the second control bandwidth range RBB2. To this end, the associated second active support unit 108.2 can then have an active pose control unit (not depicted in any more detail) which, driven by the control device 106, sets a position and/or orientation of the assigned second optical element M1 or M3 in at least one degree of freedom DOF (up to all six degrees of freedom DOF in space) with the maximum control bandwidth RBM2 for the second optical element M1 or M3 in the imaging aberration correction step 110.5.

Consequently, what is known as a correction pose KL can therefore also be specified for the relevant second optical element M1 or M3 and then set by way of appropriate driving of the relevant second active support unit 108.2 on the assigned second optical element M1 or M3. In this context, it is understood that it is also possible to specify, by way of the control device 106, a superposition of correction accuracy KP and correction pose KL.

As already mentioned multiple times, the control device 106 may naturally optionally undertake a further correction of the imaging aberration (on the basis of the aforementioned information captured by way of the capturing device) by actuating at least one further component of the imaging device (e.g., the mask device or object device 103 and/or the substrate device or image device 105), in order overall to obtain a desired low imaging aberration of the imaging.

The control information, that is to say the correction information KI, required for driving the relevant second active support unit 108.2 (and optionally the further component 103, 105) can be determined in any desired way as a matter of principle. In the present example, the control device 106 uses a stored correction model KM in the imaging aberration correction step 110.5 for the purpose of driving the relevant second active support unit 108.2 and, optionally, the at least one further component 103, 105 of the imaging device 101 in order to at least reduce, in particular substantially eliminate, the imaging aberration. # In this case, the correction model KM can supply, on the basis of the first pose information L11 , control information or correction information KI for driving the relevant second active support unit 108.2.

In the present example, the correction model KM supplies the control information or correction information KI for driving the relevant second active support unit 108.2 also on the basis of the first deformation information D11. Likewise, in certain variants, the correction model can supply the control information or correction information KI for driving the relevant second active support unit 108.2 also on the basis of the most recent imaging aberration information AFI. In this case, the correction model KM may optionally supply, in each case on the basis of the first pose information and/or first deformation information and/or imaging aberration information, control information for driving an active third support unit 103.5 or 105.5 of the further component 103 or 105 of the imaging device. In this way, a correction or reduction of the entire imaging aberration that is as comprehensive as possible can be obtained in a particularly simple and cost-effective manner.

In principle, the correction model KM may have been determined in any suitable desired way. Thus, it may have been created purely theoretically on the basis of pure numerical modelling of the optical arrangement and optionally the entire imaging device 101. Likewise, it may have been created on the basis of measurements on an optical arrangement and optionally an entire imaging device, wherein this relates at least to a comparable or structurally identical optical arrangement or imaging device, but preferably the specific optical arrangement or imaging device 101 itself. Naturally, mixed forms of these two extremes are possibly and typically particularly advantageous.

In principle and as mentioned, the correction model KM can be a static model which remains unchanged, at least over a relatively long period of operation. Preferably, like in the present example, this is an adaptive model which is intermittently adapted, specifically in step 110.8, to the actual conditions of the optical arrangement or imaging device 101. In the process, it is possible to implement a self-adapting algorithm which, triggered in step 110.8 only by certain temporal events (e.g., at certain specified intervals) and/or by non-temporal events (start and/or end of operation, setting change of the illumination device and/or projection device, reaching certain specified operating parameters, for example the temperature at certain components, exceeding an imaging aberration tolerance, etc.), checks the effectiveness of the correction of the imaging aberration and undertakes a corresponding correction of the correction model in step 110.9. In the present example, the control device 106 is accordingly configured to correct the correction model KM in the correction step 110.9 on the basis of at least one imaging aberration information item AFI which emerges from a preceding imaging aberration correction step 110.5 (and was captured in a step 110.7), in particular on the basis of the imaging aberration information emerging from the directly preceding imaging aberration correction step 110.5. In the process, it is optionally also possible for a plurality of imaging aberration information items AFI from a plurality of (optionally directly) successive steps 110.7 to be included in the correction, for example in order to take account of the development of the imaging aberration over time, and to adequately correct the correction model KM. In the present example, the control device 106 is configured to use the correction model KM corrected in the most recent preceding model correction step 110.9 in the imaging aberration correction step 110.5. In this way, it is possible to realize an adaptive correction model KM in a particularly advantageous manner.

It is understood that the capturing device 109 can only capture the corresponding aforementioned capturing variables or information for the first subgroup UG1 as a matter of principle and that these can be used for actuating the second subgroup UG2 and optionally the further component(s) 103, 105. However, in the present example there preferably is also analogous capturing at the second subgroup or for the second subgroup UG2 in order to obtain a particularly advantageous and effective correction in the imaging aberration correction step 110.5.

In the present example, the capturing device 109 is consequently configured to capture second pose information LI2 for the relevant second optical element M1, M3 in step 110.3, the said pose information being representative for a position and/or orientation of the relevant second optical element M1 , M3 vis-a-vis the reference R in at least one degree of freedom DOF (up to all six degrees of freedom DOF in space). Additionally, the capturing device is configured to capture second deformation information DI2 for the relevant second optical element M1, M3, the said deformation information being representative for a deformation of the relevant second optical element M1, M3 in at least one degree of freedom DOF (up to all six degrees of freedom DOF in space). Then, the control device 106 is configured to drive the relevant second active support unit 108.2 in the imaging aberration correction step 110.5 also on the basis of the second pose information LI2 and on the basis of the second deformation information DI2.

In the present example, the correction model KM then consequently supplies the control information or correction information KI for driving the relevant second active support unit 108.2 also on the basis of the second pose information LI2 and the second deformation information DI2.

It is understood that, in principle, the optical arrangement described herein can be used for imaging devices 101 of any design or composition. In particular, the group G of optical elements may comprise any desired number of optical elements. The same applies to the division of the group of optical elements into the first and the second subgroup. Preferably the plurality N is equal to 2 to 12, preferably equal to 4 to 10, more preferably equal to 6 to 8. Additionally or alternatively, the plurality M can be equal to 2 to 10, preferably be equal to 3 to 8, more preferably be equal to 4 to 6. Additionally or alternatively, the number K can finally be equal to 1 to 12, preferably be equal to 4 to 10, more preferably be equal to 6 to 8. Consequently, for example, a single correction element may therefore be sufficient to obtain the desired small imaging aberration (optionally together with the described actuation of one or more further components). In any event, all these cases lead to particularly advantageous set-ups, in which small imaging aberrations are possible with comparatively little outlay for the first subgroup.

The optical elements M1 to M6 can be assigned to the first and the second subgroup UG1, UG2 according to any desired criteria as a matter of principle. Typically, optical elements whose adjustment with a maximum control bandwidth RBM from the second control bandwidth range RBB2 was found to be particularly difficult are assigned to the first subgroup UG1. Further, it is possible to assign certain optical elements to the first subgroup UG1 even though they could be actuated with a maximum control bandwidth RBM from the second control bandwidth range RBB2. This can realize a reduction in the outlay even for those optical elements. As already mentioned, in the case of the second subgroup UG2 it may optionally also be possible to adjust the pose of the second optical element M1, M3 with a maximum control bandwidth RBM from the first control bandwidth range RBB1 , that is to say in that case only adjust the deformation of the second optical element M1, M3 with a maximum control bandwidth RBM2 from the second control bandwidth range RBB2.

Particularly advantageous set-ups arise if the first subgroup UG1 , like in the present example, comprises the largest optical element M6 of the group G of optical elements, which in this case is also the heaviest optical element of the group G of optical elements. Additionally, the first subgroup UG1 comprises the second largest optical element M2 of the group G of optical elements, which is also the second heaviest optical element of the group G of optical elements. Further, the second subgroup comprises the smallest optical element M3 of the group G of optical elements, which is also the lightest optical element of the group G of optical elements. Additionally, the second subgroup UG2 comprises the second smallest optical element M1 of the group G of optical elements, which is also the second lightest optical element of the group G of optical elements.

The present invention has been described above exclusively on the basis of examples from the field of microlithography. However, it is self-evident that the invention can also be used in the context of any desired other optical applications, in particular imaging methods at different wavelengths, in which similar problems arise in terms of the active correction of imaging aberrations.

Furthermore, the invention can be used in connection with the inspection of objects, such as for example so-called mask inspection, in which the masks used for microlithography are inspected for their integrity, etc. In figure 1, a sensor unit, for example, which detects the imaging of the projection pattern of the reticle 104.1 (for further processing), then takes the place of the wait for 105.1. This mask inspection can then take place substantially at the same wavelength as is used in the later microlithographic process. However, it is similarly possible also to use any desired wavelengths deviating therefrom for the inspection.

Finally, the present invention has been described above on the basis of specific exemplary embodiments showing specific combinations of the features defined in the following patent claims. It should expressly be pointed out at this juncture that the subject matter of the present invention is not restricted to these combinations of features, rather all other combinations of features such as are evident from the following patent claims also belong to the subject matter of the present invention.

Claims

1. Optical arrangement of a microlithographic imaging device, in particular for using light in the extreme UV (EUV) range, comprising

- a group of optical elements,

- a support structure (104.2),

- an active support device (108) and

- a control device (106), wherein

- the group of optical elements comprises a plurality N of optical elements (M1 to M6) which are supported on the support structure (104.2) by way of the active support device (108),

- the active support device (108) comprises an active support unit (108.1 , 108.2) for each optical element (M1 to M6) of the group of optical elements, which active support unit is configured to adjustably support the optical element on the support structure (104.2) under control device (106) control,

- the group of optical elements comprises a first subgroup with a plurality M of first optical elements (M2, M4, M5, M6),

- the group of optical elements comprises a second subgroup with a number K of second optical elements (M1 , M3),

- the control device (106) and a first active support unit (108.1) assigned to the respective first optical element (M2, M4, M5, M6) are configured to adjust the first optical element (M2, M4, M5, M6) in at least one degree of freedom with a maximum control bandwidth which is within a first control bandwidth range,

- the control device (106) and a second active support unit (108.2) assigned to the respective second optical element (M1 , M3) are configured to adjust and/or deform the second optical element (M1 , M3) in at least one degree of freedom with a maximum control bandwidth which is within a second control bandwidth range, characterized in that

- the first control bandwidth range is below the second control bandwidth range and spaced apart from the second control bandwidth range by an interval, wherein

- the interval is at least 50%, preferably at least 100%, further preferably at least 125% of an upper limit of the first control bandwidth range and/or

- the interval is at least 40 Hz to 80 Hz, preferably 50 Hz to 175 Hz, further preferably 75 Hz to 125 Hz. Optical arrangement according to Claim 1, wherein

- the first control bandwidth range ranges from 50 Hz to 180 Hz, preferably ranges from 75 Hz to 160 Hz, further preferably ranges from 90 Hz to 120 Hz and/or

- the second control bandwidth range ranges from 180 Hz to 260 Hz, preferably ranges from 200 Hz to 250 Hz, further preferably ranges from 220 Hz to 250 Hz. Optical arrangement according to Claim 1 or 2, wherein

- the control device (106) is connected to a capturing device (109), wherein

- the capturing device (109) is configured to capture first pose information at least for the first optical elements (M2, M4, M5, M6), the said pose information being representative for a respective position and/or orientation of the first optical element (M2, M4, M5, M6) vis-a-vis a reference (R) in at least one degree of freedom, and/or

- the capturing device (109) is configured to capture first deformation information at least for the first optical elements (M2, M4, M5, M6), the said deformation information being representative for a respective deformation of the first optical element (M2, M4, M5, M6) in at least one degree of freedom, and/or

- the capturing device (109) is configured to capture imaging aberration information which is representative for an imaging aberration of the imaging device (101), wherein - the control device (106) is configured to drive the at least one second active support unit (108.2) on the basis of the first pose information and/or on the basis of the first deformation information and/or on the basis of the imaging aberration information.

4. Optical arrangement according to Claim 3, wherein

- the group of optical elements causes an imaging aberration of the imaging device (101) during operation and

- the control device (106) is configured to drive the at least one second active support unit (108.2), alone or in combination with at least one further component (103, 105) of the imaging device (101), in an imaging aberration correction step

(110.5) so that the imaging aberration is at least reduced, in particular substantially eliminated, wherein in particular

- the at least one second active support unit (108.2) has an active deformation unit which, driven by the control device (106), sets a deformation of the assigned second optical element (M1, M3) in at least one degree of freedom with the maximum control bandwidth for the second optical element (M1, M3), and/or

- the at least one second active support unit (108.2) has an active pose control unit which, driven by the control device (106), sets a position and/or orientation of the assigned second optical element (M1, M3) in at least one degree of freedom with the maximum control bandwidth for the second optical element (M1, M3), and/or

- the at least one further component (103, 105) of the imaging device is an image device (105) or an object device (103) of the imaging device (101).

5. Optical arrangement according to Claim 4, wherein

- the control device (106) uses a stored correction model in the imaging aberration correction step (110.5) for the purpose of driving the at least one second active support unit (108.2) and, optionally, the at least one further component (103, 105) of the imaging device (101) in order to at least reduce, in particular substantially eliminate, the imaging aberration, wherein

- the correction model supplies, on the basis of the first pose information, control information for driving the at least one second active support unit (108.2) and/or

- the correction model supplies, on the basis of the first deformation information, control information for driving the at least one second active support unit (108.2) and/or

- the correction model supplies, on the basis of the imaging aberration information, control information for driving the at least one second active support unit (108.2), wherein optionally

- the correction model supplies, on the basis of the first pose information and/or first deformation information and/or imaging aberration information, control information for driving an active third support unit (103.5, 105.5) of the at least one further component (103, 105) of the imaging device (101).

6. Optical arrangement according to Claim 5, wherein

- the control device (106) is configured to correct, in a model correction step (110.9), the correction model on the basis of the imaging aberration information from a preceding imaging aberration correction step (110.5), in particular on the basis of the imaging aberration information from the immediately preceding imaging aberration correction step (110.5), and

- the control device (106) is configured to use the correction model corrected in the model correction step (110.9) in the imaging aberration correction step (110.5).

7. Optical arrangement according to any one of Claims 3 to 6, wherein

- the capturing device (109) is configured to capture second pose information for the at least one second optical element (M1 , M3), the said pose information being representative for a position and/or orientation of the at least one second optical element (M1, M3) vis-a-vis a reference (R) in at least one degree of freedom, and/or

- the capturing device (109) is configured to capture second deformation information for the at least one second optical element (M1, M3), the said deformation information being representative for a deformation of the at least one second optical element (M1, M3) in at least one degree of freedom, wherein

- the control device (106) is configured to drive the at least one second active support unit (108.2) on the basis of the second pose information and/or on the basis of the second deformation information. Optical arrangement according to Claims 5 and 7, wherein

- the correction model supplies, on the basis of the second pose information, the control information for driving the at least one second active support unit (108.2) and/or

- the correction model supplies, on the basis of the second deformation information, the control information for driving the at least one second active support unit (108.2), wherein in particular

- the control device (106) is configured to correct, in a model correction step (110.9), the correction model on the basis of at least one imaging aberration information item emerging from a preceding imaging aberration correction step (110.5), in particular on the basis of the imaging aberration information emerging from the directly preceding imaging aberration correction step (110.5), and the control device (106) is configured to use the correction model corrected in the most recent preceding model correction step (110.9) in the imaging aberration correction step (110.5). Optical arrangement according to any one of Claims 1 to 8, wherein

- the plurality N is equal to 2 to 12, preferably is equal to 4 to 10, more preferably is equal to 6 to 8, and/or

- the plurality M is equal to 2 to 10, preferably is equal to 3 to 8, more preferably is equal to 4 to 6, and/or - the number K is equal to 1 to 12, preferably is equal to 4 to 10, more preferably is equal to 6 to 8, and/or

- the first subgroup comprises the largest optical element (M6) of the group of optical elements and/or the heaviest optical element (M6) of the group of optical elements and/or

- the first subgroup comprises the second largest optical element (M2) of the group of optical elements and/or the second heaviest optical element (M2) of the group of optical elements and/or

- the second subgroup comprises the smallest optical element (M3) of the group of optical elements and/or the lightest optical element (M3) of the group of optical elements and/or

- the second subgroup comprises the second smallest optical element (M1) of the group of optical elements and/or the second lightest optical element (M1) of the group of optical elements. Optical imaging device, in particular microlithographic optical imaging device, comprising

- an illumination device (102) with a first group of optical elements (102.2),

- an object device (103) for receiving an object (103.3),

- a projection device (104) with a second group of optical elements (104.1) and

- an image device (105), wherein

- the illumination device (102) is configured to illuminate the object (103.3) and

- the projection device (104) is configured to project an image of the object (103.3) onto the image device (105), characterized in that the projection device (104) comprises at least one optical arrangement (108, 208) according to any one of Claims 1 to 9. Method for supporting a group of optical elements on a support structure (104.2) of a microlithographic imaging device, in particular for using light in the extreme UV (EUV) range, wherein

- the group of optical elements comprises a plurality N of optical elements (M1 to M6) which are supported on the support structure (104.2) by way of the active support device (108), wherein the group of optical elements comprises a first subgroup with a plurality M of first optical elements (M2, M4, M5, M6) and a second subgroup with a number K of second optical elements (M1, M3),

- each optical element of the group of optical elements is adjustably supported on the support structure (104.2) by way of an active support unit,

- the respective first optical element (M2, M4, M5, M6) is adjusted in at least one degree of freedom by way of an assigned first active support unit (108.1) with a maximum control bandwidth which is within a first control bandwidth range,

- the respective second optical element (M1, M3) is adjusted and/or deformed in at least one degree of freedom by way of an assigned second active support unit (108.2) with a maximum control bandwidth which is within a second control bandwidth range, characterized in that

- the interval is at least 40 Hz to 80 Hz, preferably 50 Hz to 175 Hz, further preferably 75 Hz to 125 Hz. Method according to Claim 11, wherein

- the first control bandwidth range ranges from 50 Hz to 180 Hz, preferably ranges from 75 Hz to 160 Hz, further preferably ranges from 90 Hz to 120 Hz and/or the second control bandwidth range ranges from 180 Hz to 260 Hz, preferably ranges from 200 Hz to 250 Hz, further preferably ranges from 220 Hz to 250 Hz.

13. Method according to Claim 11 or 12, wherein

- first pose information is captured at least for the first optical elements (M2, M4, M5, M6), the said pose information being representative for a respective position and/or orientation of the first optical element (M2, M4, M5, M6) vis-a-vis a reference (R) in at least one degree of freedom, and/or

- first deformation information is captured at least for the first optical elements (M2, M4, M5, M6), the said deformation information being representative for a respective deformation of the first optical element (M2, M4, M5, M6) in at least one degree of freedom, and/or

- imaging aberration information which is representative for an imaging aberration of the imaging device (101) is captured, wherein

- the at least one second active support unit (108.2) is driven on the basis of the first pose information and/or on the basis of the first deformation information and/or on the basis of the imaging aberration information.

14. Method according to Claim 13, wherein

- the at least one second active support unit (108.2) is driven, alone or in combination with at least one further component (103, 105) of the imaging device (101), in an imaging aberration correction step (110.5) so that the imaging aberration is at least reduced, in particular substantially eliminated, wherein in particular

- the at least one second active support unit (108.2) has an active deformation unit which is used to set a deformation of the assigned second optical element (M1 , M3) in at least one degree of freedom with the maximum control bandwidth for the second optical element (M1, M3) and/or

- the at least one second active support unit (108.2) has an active pose control unit which is used to set a position and/or orientation of the assigned second optical element (M1, M3) in at least one degree of freedom with the maximum control bandwidth for the second optical element (M1, M3) and/or

- the at least one further component of the imaging device is an image device (105) or an object device (103) of the imaging device (101). Method according to Claim 14, wherein

- a stored correction model is used in the imaging aberration correction step (110.5) for the purpose of driving the at least one second active support unit (108.2) and, optionally, the at least one further component of the imaging device in order to at least reduce, in particular substantially eliminate, the imaging aberration, wherein

- the correction model supplies, on the basis of the first pose information and/or first deformation information and/or imaging aberration information, control information for driving an active third support unit (103.5, 105.5) of the at least one further component (103, 105) of the imaging device (101). Method according to Claim 15, wherein

- the correction model is corrected in a model correction step (110.9) on the basis of at least one imaging aberration information item which emerges from a preceding imaging aberration correction step (110.5), in particular on the basis of the imaging aberration information which emerges from the directly preceding imaging aberration correction step (110.5), and

- the correction model corrected in the most recent preceding model correction step (110.9) is used in the imaging aberration correction step (110.5).

17. Method according to any one of Claims 13 to 16, wherein

- second pose information is captured for the at least one second optical element (M1, M3), the said pose information being representative for a position and/or orientation of the at least one second optical element (M1, M3) vis-a-vis a reference in at least one degree of freedom, and/or

- second deformation information is captured for the at least one second optical element (M1, M3), the said deformation information being representative for a deformation of the at least one second optical element (M1, M3) in at least one degree of freedom, wherein

- the at least one second active support unit (108.2) is driven on the basis of the second pose information and/or on the basis of the second deformation information.

18. Method according to Claims 15 and 17, wherein

- the correction model is corrected in a model correction step (110.9) on the basis of the imaging aberration information from a preceding imaging aberration correction step (110.5), in particular on the basis of the imaging aberration information from the directly preceding imaging aberration correction step (110.5), and the correction model corrected in the model correction step (110.9) is used in the imaging aberration correction step (110.5). Optical imaging method, in particular microlithographic optical imaging method, wherein - an illumination device (102) which has a first group of optical elements (102.2) illuminates an object (103.3) and

- a projection device (104) which has a second group of optical elements (104.1) projects an image representation of the object (103.3) onto an image device (105), characterized in that - at least the optical elements (M1 to M6) of the second group of optical elements of the projection device (104) are supported by means of a method according to any one of Claims 11 to 18.