DE102022204044A1 - SUPPORTING COMPONENTS OF AN OPTICAL DEVICE - Google Patents

Abstract

The present invention relates to an optical arrangement of an imaging device for microlithography, in particular for the use of light in the extreme UV range (EUV), with 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 of N optical elements (M1 to M6), which are supported on the support structure (104.2) via 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 is designed to support the optical element (M1 to M6) controlled by the control device (106). adjustable on the support structure (104.2). The group of optical elements includes 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 designed to control the first optical element (M2, M4, M5, M6) with a maximum control bandwidth, which lies in a first control bandwidth range, to be adjusted in at least one degree of freedom. Furthermore, the control device (106) and a second active support unit (108.2) assigned to the respective second optical element (M1, M3) are designed to control the second optical element (M1, M3) with a maximum control bandwidth that lies in a second control bandwidth range. to adjust and/or deform in at least one degree of freedom. The first control bandwidth range lies below the second control bandwidth range and is spaced from the second control bandwidth range by a distance. The distance is at least 50%, preferably at least 100%, more 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, more preferably 75 Hz to 125 Hz.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an optical arrangement of an imaging device for microlithography, which is suitable for the use of useful UV light, in particular light in the extreme ultraviolet (EUV) range. The invention further relates to an optical imaging device with such an optical arrangement, a method for supporting optical elements and an optical imaging method. The invention can be used in connection with any optical imaging method. It can be used particularly advantageously in the production or inspection of microelectronic circuits and the optical components used for this purpose (for example optical masks).

The optical devices used in connection with the fabrication of microelectronic circuits typically include a plurality of optical element units that include one or more optical elements such as lenses, mirrors or optical gratings arranged in the imaging light path. These optical elements typically cooperate in an imaging process to transfer an image of an object (e.g., a pattern formed on a mask) to a substrate (e.g., a so-called wafer). The optical elements are typically combined in one or more functional groups, which may be held in separate imaging units. Particularly in primarily refractive systems that work 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 that hold one or more optical elements. These optical modules typically include a support structure with a substantially annular outer support unit that supports one or more optical element holders, which in turn hold the optical element.

The ever-increasing miniaturization of semiconductor components leads to a constant need for increased resolution of the optical systems used to produce them. This need for increased resolution requires increased numerical aperture (NA) and increased imaging accuracy of the optical systems.

One approach to obtain increased optical resolution is to reduce the wavelength of light used in the imaging process. In recent years there has been increased development of systems that use light in the so-called extreme ultraviolet (EUV) range, typically at wavelengths of 5 nm to 20 nm, in most cases at a wavelength of around 13 nm In the EUV range it is no longer possible to use conventional refractive optical systems. This is due to the fact that the materials used for refractive optical systems in this EUV range have an absorption level that is too high to achieve acceptable imaging results with the available light output. Consequently, reflective optical systems must be used for imaging in this EUV range.

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

The above-mentioned factors lead to very strict requirements with regard to the position and/or orientation of the optical elements that participate in the imaging, relative to one another, as well as with regard to the deformation of the individual optical elements in order to achieve a desired imaging accuracy. It is also necessary to maintain this high level of imaging accuracy throughout the entire operation, ultimately over the lifespan 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) that cooperate during imaging are supported in a well-defined manner in order to achieve a predetermined well-defined spatial relationship between them components and to achieve minimal undesirable deformation of these components in order to ultimately achieve the highest possible imaging quality.

The high numerical aperture brings with it, among other things, the problem that it requires the use of optical elements with comparatively large dimensions, which are associated with high masses or moments of inertia. These high masses or moments of inertia make it very difficult to ensure the high dynamics required for commercial use in the highly precise positioning of the components involved in the optical imaging (in particular the optical elements of the projection device) in relation to one another, in order to ultimately To achieve the lowest possible imaging error or the highest possible imaging quality.

In order to address the problem of large and therefore sluggish components, WO 2013/004403 A1 (Kwan et al., the entire disclosure of which is incorporated herein by reference) has already proposed using the heaviest optical element as an inertial reference and ultimately aligning the other optical elements with respect to this particularly inert optical element. The optical element that forms this inertial reference is active, but is only supported with a comparatively small maximum control bandwidth, while all other components have to be aligned with this inertial reference with a significantly higher maximum control bandwidth. The problem here, however, is that with the above-mentioned increasing numerical aperture, more and more effort has to be made for these other optical elements, which are also becoming larger and larger, in order to meet the requirements for the control dynamics.

BRIEF SUMMARY OF THE INVENTION

The invention is therefore based on the object of providing an optical arrangement of an imaging device for microlithography which is suitable for the use of useful UV light, in particular light in the extreme ultraviolet (EUV) range. Furthermore, the invention relates to an optical imaging device with such an optical arrangement, a method for supporting optical elements and an optical imaging method, which does not have the aforementioned disadvantages or at least to a lesser extent and in particular in a simple manner At least consistent imaging quality reduces the effort for the imaging device.

The invention solves this problem with the features of the independent claims.

The invention is based on the technical teaching that the effort for the imaging device can be reduced in a simple manner while maintaining at least the same imaging quality if several optical elements, which can be assigned to a first subgroup of the projection device, and are attached to the image (for example of the pattern of a mask). a substrate) are involved, is only supported with a comparatively small maximum control bandwidth. Due to the reduced dynamics of the adjustment of the optical elements of the first subgroup, this initially results in an increased imaging error, which results from the correction of a deviation of the optical elements of the first subgroup from their target state no longer being available sufficiently quickly. This imaging error is then at least partially compensated for by one or more additional optical elements actuated with a correspondingly high control bandwidth, which are also involved in the imaging and can 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 second subgroup differ by a noticeable distance, so that a clearly noticeable saving in the effort for the optical elements of the first subgroup can be achieved.

Thanks to the lower required maximum control bandwidth, the optical elements of the first subgroup can be designed to be lighter and therefore simpler for their actuation. This also has a positive effect on the effort required for the actuators, for example the active support, of these optical elements. The support of the optical elements of the first subgroup realized in this way can also be referred to as floating support or support with low rigidity, since the reaction to deviations from a target state is only comparatively slow or sluggish. It can then typically be sufficient to accurately record at least the position (i.e. position and/or orientation) of these optical elements of the first subgroup in the degrees of freedom relevant for high imaging quality (up to all six degrees of freedom in space) and then use this information for to use the control of the actuator system of the relevant optical element of the second subgroup.

The relevant optical element of the second subgroup is then preferably a smaller and lighter optical element, in which the required high dynamics of the actuation can be achieved with comparatively little effort. The support realized here for the optical elements of the second subgroup can also be referred to as support with high rigidity, since the corresponding specifications for a target state are responded to comparatively quickly or agilely.

It may be sufficient for the second subgroup to comprise only a single optical element (i.e. a single correction element), but several optical elements can also be used for correction. The latter can be particularly advantageous insofar as the correction of different imaging errors is carried out by different correction elements, so that the complexity of the actuator system for these correction elements is reduced. Likewise, the Cor Correction of a specific imaging error can also be distributed over several correction elements. This can also reduce the complexity of the actuators for these correction elements. It should be expressly mentioned here that in the present description the term imaging error may include several errors of different types, which together describe the overall imaging quality of the image.

To correct the imaging error, it may be sufficient for the correction element to have a corresponding deformation of its optical surface applied or for the position of the correction element to be adjusted accordingly in the relevant degrees of freedom (up to all six degrees of freedom in space). Of course, a combined correction via deformation and position control can also be implemented. It is not absolutely necessary that a complete correction of the imaging error is realized via the correction element or the correction elements alone. Likewise, other components involved in the imaging, such as the mask or the substrate (or their respective holding device) can be used for correction and their actuators can be controlled accordingly in order to achieve the sum of the corrections (within the framework of the predetermined for the individual imaging or imaging device Error budgets) to achieve the lowest possible imaging error.

It is further understood that any relevant imaging errors can be corrected alone or in any combination; this can be, for example, the so-called line-of-sight error (LoS error, i.e. a position error in the imaging of points on the object plane with respect to the Target position in the image plane) and/or so-called wavefront aberrations. Their correction can be achieved solely by appropriate actuation of a correction element or by concerted actuation of several correction elements and, if necessary, further components (e.g. mask and/or substrate).

According to one aspect, the invention therefore relates to an optical arrangement of an imaging device for microlithography, in particular for the use of light in the extreme UV range (EUV), with 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 via the active support device. The active support device comprises an active support unit for each optical element of the group of optical elements, which is designed to support the optical element on the support structure in an adjustable manner controlled by the control device. The group of optical elements includes 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 designed to adjust the first optical element with a maximum control bandwidth, which lies in a first control bandwidth range, in at least one degree of freedom (up to all six degrees of freedom in space). Furthermore, the control device and a second active support unit assigned to the respective second optical element are designed to adjust the second optical element with a maximum control bandwidth, which lies in a second control bandwidth range, in at least one degree of freedom (up to all six degrees of freedom in space). and/or deform. The first control bandwidth range lies below the second control bandwidth range and is spaced apart from the second control bandwidth range by a distance. The distance is at least 50%, preferably at least 100%, more 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, more preferably 75 Hz to 125 Hz. In this way, a clearly noticeable reduction in the effort for the optical elements of the first subgroup and their support can be achieved in an advantageous manner, while at the same time a sufficiently high imaging quality can be ensured.

The two control bandwidth ranges can in principle be located anywhere and have an arbitrarily large range (i.e. variation of the maximum control bandwidth within them), as long as a correspondingly noticeable reduction in the effort for the optical elements of the first subgroup can be achieved. In certain variants, the first control bandwidth range ranges from 50 Hz to 180 Hz, preferably from 75 Hz to 160 Hz, more preferably from 90 Hz to 120 Hz. Additionally or alternatively, the second control bandwidth range may range from 180 Hz to 260 Hz, preferably from 200 Hz to 250 Hz, more preferably from 220 Hz to 250 Hz. Both allow a noticeable reduction in the effort for the optical elements of the first subgroup with high imaging quality.

In certain variants, the control device is connected to a detection device, the detection device being designed to detect first position information at least for the first optical elements, which is relevant for a respective position and/or orientation of the first optical element with respect to a reference in at least one degree of freedom (up to all of them six degrees of freedom in space) is representative. For this purpose, the sensors that are typically already present (for example for a setting with a high control bandwidth) can be easily used, so that the effort required for this does not increase. The first position information can then be used to correct the imaging error that results from the reduced dynamics of the actuation of the first optical elements via the corresponding actuation of at least a second optical element (and possibly other components involved in the imaging, as described above explained).

Additionally or alternatively, the detection device can be designed to detect first deformation information at least for the first optical elements, which is representative of a respective deformation of the first optical element in at least one degree of freedom. Here you can proceed in an analogous manner to the acquisition and use of the first position information just described, so that reference is made to the above statements. The detection of the deformation information is particularly advantageous in that large or heavy optical elements, even when supported with a reduced maximum control bandwidth (hence reduced accelerations acting on them), can still react with comparatively large deformations during operation, which have a significant influence on the may have imaging errors.

Additionally or alternatively, the detection device can also be designed to detect imaging error information that is representative of an imaging error of the imaging device. Here too, a procedure can be carried out in a manner analogous to the acquisition and use of the first position information or first deformation information just described, so that reference is also made to the above statements in this respect.

In the aforementioned cases, the control device is then, as mentioned, designed to control the at least one second active support unit as a function of the first position information and/or as a function of the first deformation information and/or as a function of the imaging error information.

In advantageous variants, the group of optical elements causes an imaging error of the imaging device during operation, the control device then being designed to control 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 error correction step in such a way that the imaging error is at least is reduced, in particular essentially eliminated. The correction of the imaging error can in principle be carried out in any suitable manner via the corresponding actuation of at least one second active support unit and, if necessary, at least one further component of the imaging device.

In certain variants, the imaging error is corrected in the imaging error correction step (possibly alone) via a deformation of the at least one second optical element with the maximum control bandwidth (from the second control bandwidth range). For this purpose, the at least one second active support unit can have an active deformation unit, which, controlled by the control device, sets a deformation of the associated second optical element in at least one degree of freedom (up to all six degrees of freedom) with the maximum control bandwidth for the second optical element. A so-called correction pass can therefore be specified for the second optical element, which is then set on the associated second optical element via a corresponding control of the relevant second active support unit.

It goes without saying that the position of the second optical element does not necessarily have to be set with a maximum control bandwidth from the second control bandwidth range. In these cases, it is also possible to set the position of the second optical element with a maximum control bandwidth from the first control bandwidth range, i.e. only to set the deformation of the second optical element with a maximum control bandwidth from the second control bandwidth range. It can therefore be the case that one or more optical elements belong to both the first subgroup (since the position of the optical element in question is set with a maximum control bandwidth from the first control bandwidth range) and belong to the second subgroup (since the deformation of the relevant optical element is set with a maximum control bandwidth from the second control bandwidth range). In certain other variants, however, it can also be provided that the first and second subgroups exclude each other, meaning that the respective optical element belongs either only to the first subgroup or only to the second subgroup.

Additionally or alternatively, the correction of the imaging error in the imaging error correction step (possibly alone) can also be done via a position adjustment of the at least one second optical element with the maximum control bandwidth (from the second control bandwidth range). For this purpose, the at least one second active support unit can have an active position adjustment unit, which, controlled by the control device, sets a position and/or orientation of the associated second optical element in at least one degree of freedom with the maximum control bandwidth for the second optical element. A so-called correction position can therefore also be specified for the second optical element, which is then set via a corresponding control of the relevant second active support unit on the assigned second optical element. It goes without saying that an overlay of correction pass and correction position can also be specified.

As already mentioned several times, the control device (depending on the above-mentioned information recorded via the detection device) can of course optionally carry out a further correction of the imaging error 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 , such as a substrate device) in order to achieve a desired low overall imaging error. In preferred variants, the at least one further component of the imaging device is an imaging device (e.g. a substrate device) or an object device (e.g. a mask device) of the imaging device.

The determination of the control information required for controlling the relevant second active support unit (and possibly the further component) can in principle be carried out in any suitable manner. Preferably, the control device uses a stored correction model to control the at least one second active support unit and optionally the at least one further component of the imaging device in the imaging error correction step in order to at least reduce, in particular essentially eliminate, the imaging error. Depending on the first position information, the correction model can provide control information for controlling the at least one second active support unit. Additionally or alternatively, the correction model can provide control information for controlling the at least one second active support unit depending on the first deformation information. Likewise, the correction model can additionally or alternatively, depending on the imaging error information, provide control information for controlling the at least one second active support unit. The correction model can optionally provide control information for controlling an active third support unit of the at least one further component of the imaging device depending on the first position information and/or the first deformation information and/or the imaging error information. In this way, the greatest possible correction or reduction of the entire imaging error can be achieved in a particularly simple and inexpensive manner.

The correction model can in principle have been determined in any suitable way. So it can have been created purely theoretically on the basis of purely numerical modeling of the optical arrangement and possibly the entire imaging device. Likewise, it can have been created on the basis of measurements on an optical arrangement and possibly an entire imaging device (which is at least a comparable or identical optical arrangement or imaging device, but preferably the specific optical arrangement or imaging device itself). Of course, mixed forms of these two extremes are also possible and are typically particularly cheap.

The correction model can in principle be a static model that remains unchanged at least over a longer operating period. It is preferably an adaptive model that is adapted from time to time to the actual conditions of the optical arrangement or the imaging device. In particular, a self-adapting algorithm can be implemented, which is triggered by certain temporal events (e.g. at certain predetermined intervals) and/or by non-temporal events (start and/or end of operation, change of setting of the lighting device and/or the projection device, achievement of certain ones). specified operating parameters, e.g. the temperature of certain components, exceeding an imaging error tolerance, etc.) checks the effectiveness of the correction of the imaging error and makes a corresponding correction to the correction model.

In certain advantageous variants, the control device is consequently designed to correct the correction model in a model correction step depending on at least one image error information resulting from a previous image error correction step, in particular depending on the image error information that results from the immediately preceding image error correction step. If necessary, several imaging error information AFI from several (possibly immediately) successive detection steps can also be included in the correction, for example in order to take into account the development of the imaging error over time and the cor rectification model to be adequately corrected. The control device is then designed to use the correction model corrected in the last previous model correction step in the imaging error correction step. This makes it possible to implement an adaptive correction model KM in a particularly cost-effective manner.

It is understood that the detection device can basically only detect the corresponding above-mentioned detection variables or information for the first subgroup and these can be used to actuate the second subgroup and, if necessary, the other component(s). However, analog detection is preferably also carried out on the second or for the second subgroup in order to achieve a particularly favorable and effective correction.

In certain variants, the detection device is consequently designed to detect second position information for the at least one second optical element, which is responsible for a position and/or orientation of the at least one second optical element with respect to a reference in at least one degree of freedom (up to all six degrees of freedom in space) is representative. Additionally or alternatively, the detection device can be designed to detect second deformation information for the at least one second optical element, which is representative of 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 case, the control device is then designed to control the at least one second active support unit depending on the second position information and/or depending on the second deformation information.

In certain variants with the correction model described above, the correction model then supplies the control information for controlling the at least one second active support unit depending on the second position information. Additionally or alternatively, the correction model can provide the control information for controlling the at least one second active support unit depending on the second deformation information. In particular, it can again be provided that the control device is designed to correct the correction model in a model correction step depending on the imaging error information from a previous imaging error correction step, in particular to correct it depending on the imaging error information from the immediately preceding imaging error correction step. The control device is then designed to use the correction model corrected in the model correction step in the imaging error correction step.

The optical arrangement described here can in principle be used in imaging devices of any design or composition. In particular, the group of optical elements can include any number of optical elements. The same applies to the division of the group of optical elements into the first and second subgroups. 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 equal to 3 to 8, more preferably equal to 4 to 6 . Additionally or alternatively, the number K can finally be 1 to 12, preferably 4 to 10, more preferably 6 to 8. Therefore, for example, a single correction element can be sufficient to achieve the desired low imaging error (possibly together with the described actuation of one or more other components). In all of these cases, particularly favorable constellations arise in which small imaging errors are possible with comparatively little effort for the first subgroup.

The optical elements can basically be assigned to the first and second subgroups according to any criteria. Typically, those optical elements are assigned to the first subgroup whose setting with a maximum control bandwidth from the second control bandwidth range is particularly difficult. Furthermore, it is possible to assign certain optical elements to the first subgroup, although actuation with a maximum control bandwidth from the second control bandwidth range would be possible for them. In this way, a reduction in effort can also be achieved for such optical elements. As already mentioned, in the second subgroup it is optionally also possible to set the position of the second optical element with a maximum control bandwidth from the first control bandwidth range, i.e. then only to set the deformation of the second optical element with a maximum control bandwidth from the second control bandwidth range.

Particularly favorable constellations arise when the first subgroup comprises the largest optical element of the group of optical elements and/or comprises the heaviest optical element of the group of optical elements. Additionally or alternatively, the first subgroup may include the second largest optical element of the group of optical elements and/or the second heaviest optical element of the group of optical elements include. Likewise, additionally or alternatively, the second subgroup may comprise the smallest optical element of the group of optical elements and/or comprise 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 comprise the second lightest optical element of the group of optical elements.

The present invention further relates to an optical imaging device, in particular for microlithography, with an illumination device with a first optical element group, an object device for recording an object, a projection device with a second optical element group and an image device. The illumination device is designed to illuminate the object, while the projection device is designed to project an image of the object onto the image device. The projection device comprises at least one optical arrangement according to the invention, as described above. This allows the variants and advantages described above in connection with the optical arrangement to be realized to the same extent, so that reference is made to the above statements 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 an imaging device for microlithography, in particular for the use of light in the extreme UV range (EUV), in which the group of optical elements comprises a plurality N optical elements, which are supported on the support structure via the active support device, the group of optical elements comprising 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 adjustable and supported on the support structure by an active support unit. The respective first optical element is adjusted in at least one degree of freedom via an assigned first active support unit with a maximum control bandwidth that lies in a first control bandwidth range. The respective second optical element is adjusted and/or deformed in at least one degree of freedom via an assigned second active support unit with a maximum control bandwidth that lies in a second control bandwidth range. The first control bandwidth range lies below the second control bandwidth range and is spaced apart from the second control bandwidth range by a distance. The distance is at least 50%, preferably at least 100%, more 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, more preferably 75 Hz to 125 Hz. Hereby The variants and advantages described above in connection with the optical arrangement can be implemented to the same extent, so that reference is made to the above statements in order to avoid repetition.

The present invention further relates to an optical imaging method, in particular for microlithography, in which 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 of the object onto an image device. 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 allows the variants and advantages described above in connection with the optical arrangement to be realized to the same extent, so that reference is made to the above statements in order to avoid repetition.

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

BRIEF DESCRIPTION OF THE DRAWINGS

• 1 is a schematic representation of a preferred embodiment of a projection exposure system 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.
• 2 is a flowchart of a preferred embodiment of the imaging method according to the invention, which uses a preferred embodiment of the method according to the invention to support optical elements with the projection exposure system 1 can be carried out.

DETAILED DESCRIPTION OF THE INVENTION

The following is with reference to the 1 and 2 preferred embodiments of a projection exposure system 101 according to the invention for microlithography are described, which includes a preferred embodiment of an optical arrangement according to the invention. To simplify the following explanations, an x,y,z coordinate system is given in the drawings, with the z direction running parallel to the direction of the gravitational force. The x-direction and the y-direction are therefore horizontal, with the x-direction in the representation 1 runs vertically into the drawing plane. Of course, in further embodiments it is possible to choose any orientation that deviates from that of an x,y,z coordinate system.

Below we will initially refer to the 1 The essential components of a projection exposure system 101 are described as an example. The description of the basic structure of the projection exposure system 101 and its components is not intended to be restrictive.

A lighting device or a lighting system 102 of the projection exposure system 101 includes, in addition to a radiation source 102.1, an optical element group in the form of lighting optics 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. The reticle 103.3 is held by a reticle holder 103.4. The reticle holder 103.4 can be displaced in particular in one or more scanning directions via a reticle displacement drive 103.5. In the present example, such a scanning direction runs parallel to the y-axis.

The projection exposure system 101 further comprises a projection device 104 with a further optical element group in the form of projection optics 104.1. The projection optics 104.1 is used to image the object field 103.1 into a (schematized) image field 105.1, which lies in an image plane 105.2 of an image device 105. The image plane 105.2 runs parallel to the object plane 103.2. Alternatively, an angle other than 0° between the object plane 103.2 and the image plane 105.2 is also possible.

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 area 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 can be displaced in particular along the y direction via a wafer displacement drive 105.5. The displacement on the one hand of the reticle 103.3 via the reticle displacement drive 103.5 and on the other hand of the wafer 105.3 via the wafer displacement drive 105.5 can take place synchronized with one another. This synchronization can be done, for example, via a shared (in 1 Control device 106 (shown only very schematically and without control paths).

The radiation source 102.1 is an EUV radiation source (extreme ultraviolet radiation). The radiation source 102.1 emits in particular EUV radiation 107, which is also referred to below as useful radiation or illumination radiation. The useful radiation in particular 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 source (Laser Produced Plasma, i.e. using a Laser generated plasma) or a DPP source (Gas Discharged Produced Plasma, i.e. plasma generated by gas discharge). It can also be a synchrotron-based radiation source. The radiation source 102.1 can also be a free electron laser (free electron laser, FEL).

Since the projection exposure system 101 works with useful light in the EUV range, the optical elements used are exclusively reflective optical elements. In further embodiments of the invention, it is of course also possible (particularly depending on the wavelength of the illuminating light) to use any type of optical element (refractive, reflective, diffractive) alone or in any combination for the optical elements.

The illumination radiation 107, which emanates from the radiation source 102.1, is focused by a collector 102.3. The collector 102.3 can be a collector with one or more ellipsoidal and/or hyperboloid reflection surfaces. The at least one reflection surface of the collector 102.3 can be exposed to the illumination radiation 107 in grazing incidence (Grazing Incidence, Gl), i.e. with angles of incidence greater than 45°, or in normal incidence (Normal Incidence, NI), i.e. with angles of incidence smaller than 45° become. On the one hand, the collector 11 can be used to optimize its reflectivity for the purpose radiation and on the other hand be structured and/or coated to suppress false light.

After the collector 102.3, the illumination radiation 107 propagates through an intermediate focus in an intermediate focus plane 107.1. In certain variants, the intermediate focus plane 107.1 can represent a separation between the illumination optics 102.2 and a radiation source module 102.4, which includes the radiation source 102.1 and the collector 102.3.

The illumination optics 102.2 includes a deflection mirror 102.5 along the beam path and a downstream first facet mirror 102.6. The deflection mirror 102.5 can be a flat deflection mirror or, alternatively, a mirror with an effect that influences the bundle beyond the pure deflection effect. Alternatively or additionally, the deflection mirror 102.5 can be designed as a spectral filter, which at least partially separates out so-called false light from the illumination radiation 107, the wavelength of which deviates from the useful light wavelength. If the optically effective surfaces of the first facet mirror 102.6 are arranged in the area of a plane of the illumination optics 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 large number of individual first facets 102.7, which are also referred to below as field facets. These first facets and their optical surfaces are in the 1 only strongly indicated schematically by the dashed contour 102.7.

The first facets 102.7 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or part-circular edge contour. The first facets 102.7 can be designed as facets with a planar or alternatively with a convex or concave curved optical surface.

Like, for example, from the DE 10 2008 009 600 A1 (the entire disclosure of which is incorporated herein by reference), the first facets 102.7 themselves can also each be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 102.6 can in particular be designed as a microelectromechanical system (MEMS system), as is the case, for example, in FIG DE 10 2008 009 600 A1 is described in detail.

In the present example, the illumination radiation 107 runs horizontally between the collector 102.3 and the deflection mirror 102.5, i.e. along the y-direction. However, it is understood that a different orientation can also be selected for other variants.

A second facet mirror 102.8 is arranged downstream of the first facet mirror 102.6 in the beam path of the illumination optics 102.2. If the optically effective surfaces of the second facet mirror 102.8 are arranged in the area of a pupil plane of the illumination optics 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 optics 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 , the EP 1 614 008 B1 or the US 6,573,978 (the 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 in the 1 are only strongly indicated schematically by the dashed contour 102.9.

The second facets 102.9 are also referred to as pupil facets in the case of a pupil facet mirror. The second facets 102.9 can basically be designed like the first facets 102.7. In particular, the second facets 102.9 can also be macroscopic facets, which can have, for example, round, rectangular or even hexagonal edges. Alternatively, the second facets 102.9 can be facets composed of micromirrors. The second facets 102.9 can in turn have planar or alternatively convex or concave curved reflection surfaces. In this regard, we refer again to the DE 10 2008 009 600 A1 referred.

In the present example, the lighting optics 102.2 thus forms a double-faceted system. This basic principle is also known as the fly's eye integrator. In certain variants, it can also be advantageous not to arrange the optical surfaces of the second facet mirror 102.8 exactly in a plane that is optically conjugate to a pupil plane of the projection optics 104.1.

In a further, not shown, embodiment of the illumination optics 102.2, a transmission optics 102.10 (shown only in a very schematic form) can be arranged in the beam path between the second facet mirror 102.8 and the object field 103.1, which is used in particular for imaging of the first facets 102.7 contributes to the object field 103.1. The transmission optics 102.10 can have exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 102.2. The transmission optics 102.10 can in particular include one or two mirrors for vertical incidence (NI mirror, normal incidence mirror) and/or one or two mirrors for grazing incidence (GL mirror, grazing incidence mirror).

The lighting optics 102.2 has the design as shown in the 1 is shown, after the collector 102.3 exactly three mirrors, namely 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 lighting optics 102.2, the deflection mirror 102.5 can also be omitted, so that the lighting optics 102.2 can then have exactly two mirrors after the collector 102.3, namely the first facet mirror 102.6 and the second facet mirror 102.8.

With the help 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-forming mirror or actually the last mirror for the illumination radiation 107 in the beam path in front of the object field 103.1. The image of the first facets 102.7 by means of the second facets 102.9 or with the second facets 102.9 and a transmission optics 102.10 into the object plane 103.2 is generally only an approximate image.

The projection optics 104.1 comprises a plurality of mirrors Mi, which are numbered according to their arrangement along the beam path of the projection exposure system 101. At the one in the 1 In the example shown, the projection optics 104.1 includes six mirrors M1 to M6. Alternatives with four, eight, ten, twelve or another number of mirrors Mi are also possible. The penultimate mirror M5 and the last mirror M6 can each have a passage opening (not shown) for the illumination radiation 107. In the present example, the projection optics 104.1 is a double-obscured optic. The projection optics 104.1 has an image-side numerical aperture NA that is greater than 0.5. In particular, the image-side numerical aperture NA can also be larger than 0.6. For example, the image-side numerical aperture NA can be 0.7 or 0.75.

The reflection surfaces of the mirrors Mi can be designed as free-form surfaces without an axis of rotational symmetry. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one axis of rotational symmetry of the reflection surface shape. The mirrors Mi, just like the mirrors of the lighting optics 102.2, can have highly reflective coatings for the lighting radiation 107. These coatings can be made up of several layers (multilayer coatings), in particular they can be designed with alternating layers of molybdenum and silicon.

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

The projection optics 104.1 can in particular be anamorphic. In particular, it has different imaging scales βx, βy in the x and y directions. The two imaging scales βx, βy of the projection optics 104.1 are preferably (βx; βy) = (+/- 0.25; +/- 0.125). A positive image scale β means an image without image reversal. A negative sign for the image scale β means an image with image reversal. In the present example, the projection optics 104.1 thus leads to a reduction in the x-direction, i.e. in the direction perpendicular to the scanning direction, in a ratio of 4:1. In contrast, the projection optics 104.1 in the y direction, i.e. in the scanning direction, leads to a reduction in size in a ratio of 8:1. Other image scales are also possible. Image scales of the same sign and absolutely the same in the x and y directions are also possible, for example with absolute values of 0.125 or 0.25.

The number of intermediate image planes in the x and y directions 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 can be different depending on the design of the projection optics 104.1. Examples of projection optics with different numbers of such intermediate images in the x and y directions are, for example, from US 2018/0074303 A1 known (the entire disclosure of which is incorporated herein by reference).

In the present example, one of the pupil facets 102.9 is assigned to exactly one of the field facets 102.7 to form an illumination channel for illuminating the object field 103.1. This can in particular result in lighting based on Köhler's principle. The far field is created using the field facets 102.7 is broken down into a large number of object fields 103.1. The field facets 102.7 generate a plurality of images of the intermediate focus on the pupil facets 102.9 assigned to them.

The field facets 102.7 are each imaged onto the reticle 103.3 by an assigned pupil facet 102.9, with the images superimposing one another, so that there is an overlapping 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%. Field uniformity can be achieved by overlaying different lighting channels.

By arranging the pupil facets 102.9, the illumination of the entrance pupil of the projection optics 104.1 can be geometrically defined. By selecting the illumination channels, in particular the subset of the pupil facets 102.9 that carry light, the intensity distribution in the entrance pupil of the projection optics 104.1 can be adjusted. This intensity distribution is also referred to as the lighting setting of the lighting system 102. A likewise preferred pupil uniformity in the area of defined illuminated sections of an illumination pupil of the illumination optics 102.2 can be achieved by redistributing the illumination channels. The aforementioned settings can be made for actively adjustable facets by appropriate control via the control device 106.

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

The projection optics 104.1 can in particular have a homocentric entrance pupil. This can be accessible or inaccessible. The entrance pupil of the projection optics 104.1 often cannot be illuminated precisely with the pupil facet mirror 102.8. When imaging the projection optics 104.1, which images the center of the pupil facet mirror 102.8 telecentrically onto the wafer 105.3, the aperture rays often do not intersect at a single point. However, an area can be found in which the pairwise distance of the aperture beams becomes minimal. This surface represents the entrance pupil or a surface conjugate to it in local space. In particular, this surface shows a finite curvature.

In certain variants, it may be that the projection optics 104.1 has different positions of the entrance pupil for the tangential and sagittal beam paths. In this case, it is preferred if an imaging optical element, in particular an optical component of the transmission optics 102.10, is provided between the second facet mirror 102.8 and the reticle 103.3. With the help of this imaging optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

When arranging the components of the lighting optics 102.2, as shown in the 1 is shown, the optical surfaces of the pupil facet mirror 102.8 are arranged in a surface conjugate to the entrance pupil of the projection optics 104.1. The first facet mirror 102.6 (field facet mirror) defines a first main extension plane of its optical surfaces, which in the present example is arranged tilted relative to the object plane 5. In the present example, this first main extension plane of the first facet mirror 102.6 is arranged tilted to a second main extension plane, which is defined by the optical surface of the deflection mirror 102.5. In the present example, the first main extension plane of the first facet mirror 102.6 is further arranged tilted to a third main extension plane, which is defined by the optical surfaces of the second facet mirror 102.8.

The lighting device 102 and/or the projection device 104 can, for example, comprise one or more optical arrangements 108 according to the invention, as will be 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 optics 104.1, which is formed by a plurality of N = 6 optical elements, namely the mirrors Mi, here the mirrors M1 to M6. The respective mirror M1 to M6 is supported via an active support device 108 on a (only very schematically indicated) support structure 104.2 of the projection device 104. The active support device 108 includes an active support unit 108.1, 108.2 for each optical element M1 to M6 of the group G of optical elements, which is designed to adjustably support the respective optical element M1 to M6 on the support structure 104.2 controlled by the control device 106.

In the present example, the group G of optical elements M1 to M6 of the projection optics 104.1 includes a first subgroup UG1 with a plurality M = 4 first optical elements and a second subgroup UG2 with a number K = 2 second optical elements. In the present example, mirrors M2, M4, M5 and M6 belong to the first Subgroup UG1, while mirrors M1 and M3 belong to the second subgroup UG2. It goes without saying that any other assignment can also be provided for other variants. For example, the mirror M1 can then also be assigned to the first subgroup UG1, so that the second subgroup UG2 then only consists of the one mirror M3.

As will be explained below with reference to 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 (for reasons of clarity for the mirrors M2, M4 , M5 not shown) is designed to provide the first optical element M2, M4, M5, M6 with a maximum control bandwidth RBM1, which lies in a first control bandwidth range RBB1, in at least one degree of freedom DOF (up to all six degrees of freedom DOF in space). adjust. As will be explained below with reference to the mirror M3 and the associated 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 designed to control the second optical element M1, M3 with a maximum control bandwidth RBM2, which lies in a second control bandwidth range RBB2, to adjust and / or deform in at least one degree of freedom DOF (up to all six degrees of freedom DOF in space). It goes without saying that, depending on the needs of the imaging device, any different maximum control bandwidths RBM1 or RBM2 can be provided for the optical elements M1 to M6. Likewise, the same maximum control bandwidth RBM 1 or RBM2 can also be provided for the optical elements of the respective subgroup UG1 and UG2.

The first control bandwidth range RBB1 lies below the second control bandwidth range RBB2 and is spaced from the second control bandwidth range RBB2 by a distance RBA. The distance RBA is at least 50%, preferably at least 100%, more 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, more preferably 75 Hz to 125 Hz.

The first optical elements M2, M4, M5, M6 of the first subgroup UG1 are therefore supported with a comparatively small maximum control bandwidth RBM1. Due to the reduced dynamics of the setting of the optical elements M2, M4, M5, M6 of the first subgroup UG1, this initially results in an increased imaging error, which results from the correction of a deviation of the optical elements M2, M4, M5, M6 no longer being available sufficiently quickly first subgroup UG1 from its target state. As will be explained below, this imaging error is then at least partially compensated for by the optical elements M1, M3 of a second subgroup UG2, which are actuated with a correspondingly high control bandwidth RBM2.

Thanks to the lower required maximum control bandwidth RBM1, the optical elements M2, M4, M5, M6 of the first subgroup UG1 can be made lighter and therefore simpler in terms of their actuation. This also has a positive effect on the effort required to operate its assigned actuator system, i.e. the respective first active support unit 108.1. This advantageously allows a clearly noticeable reduction in the effort for the optical elements M2, M4, M5, M6 of the first subgroup UG1 and their support (i.e. the first active support units 108.1) to be achieved, while at the same time a sufficiently high imaging quality can be ensured.

In the present example, the relevant optical element M1, M3 of the second subgroup UG2 is an already smaller and lighter optical element, in which the required high dynamics of the actuation for compensation of the imaging error can be achieved via the second active support units 108.2 with comparatively little effort can be achieved.

The two control bandwidth ranges RBB1 and RBB2 can basically be located anywhere and have any range (i.e. variation of the maximum control bandwidth RBM1 or RBM2 located therein), as long as there is a correspondingly noticeable reduction in the effort for the optical elements M2, M4, M5, M6 of the first Subgroup UG1 can be achieved. In certain variants, the first control bandwidth range RBB1 ranges from 50 Hz to 180 Hz, preferably from 75 Hz to 160 Hz, more 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, more preferably from 220 Hz to 250 Hz. Both allow a noticeable reduction in the effort for the optical elements M2, M4, M5, M6 of the first subgroup UG1 with high imaging quality.

In the present example, the control device 106 is equipped with a (in 1 only very schematically shown) detection device 109 connected, the detection device 109 being designed in a conventional manner, at least least for the first optical elements M2, M4, M5, M6 to detect first position information Ll1, which is for a respective position and / or orientation of the first optical element M2, M4, M5, M6 with respect to a reference R in at least one degree of freedom DOF ( up to all six degrees of freedom DOF in space) is representative. For this purpose, the sensor system 109 that is typically already present in conventional imaging devices (for example for a setting with a high control bandwidth) can be used in a simple manner, so that the effort required for this does not increase.

The first position information LI1 is used in the present example to correct the imaging error, which results from the reduced dynamics of the actuation of the first optical elements M2, M4, M5, M6, via the corresponding actuation of the second optical elements M1, M3 via the second active support units 108.2 and, if necessary, the corresponding actuation of other components involved in the imaging (for example those of the object device 103 and / or the image device 105), as explained above.

It may be sufficient to simply record the first position information Ll1 and use it to control the second active support units 108.2. In the present example, the detection device 109 is also designed to detect first deformation information DI1 at least for the first optical elements M2, M4, M5, M6, which is necessary 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). Here you can proceed in an analogous manner to the acquisition and use of the first position information LI1 just described, so that reference is made to the above statements. The detection of the deformation information DI1 is particularly advantageous in that large or heavy optical elements (such as the mirrors M2 and M6), even when supported with a reduced maximum control bandwidth RBM1 (hence reduced accelerations acting on them), still operate comparatively can react to large deformations, which can have a significant influence on the imaging error.

Furthermore, the detection device 109 in the present example is also designed to detect imaging error information AFI, which is representative of an imaging error of the imaging device. Here too, a procedure can be carried out in a manner analogous to the acquisition and use of the first position information Ll1 or first deformation information DI1 just described, so that reference is also made to the above statements in this respect.

In the present example, the control device 106 is designed to control the second active support units 108.2 in an imaging error correction step as a function of the first position information LI1, the first deformation information DI1 and the imaging error information AFI in order to keep the overall imaging error of the projection exposure system 101 as low as possible. The control device 106 can also control the second active support units 108.2 in combination with at least one further component of the projection exposure system 101, for example the object device 103 and/or the image device 105, in order to at least reduce, in particular essentially eliminate, the imaging error of the projection exposure system 101 . This is explained below using the flowchart 2 briefly explained.

Again 2 As can be seen, the process flow is first started in a step 110.1. In a step 110.2 it is then checked whether an image should be made. If this is the case, the first position information LI1 and the first deformation information DI1 described above are determined in a step 110.3. As will be explained in more detail below, in a step 110.4, correction information KI is then determined in the control device 106 from the information from the detection device 109 using a stored correction model KM. The control device 106 then uses this correction information KI in the imaging error correction step 110.5 to correctively control the second active support units 108.2, if necessary in combination with at least one further component of the projection exposure system 101, for example the object device 103 and/or the image device 105, before or during an imaging step 110.6 an image is created. Parallel to or after the imaging step 110.6, it is recorded in a step 110.7 whether the actual imaging error of the projection exposure system 101 is within certain predetermined tolerances or whether this is not the case and therefore a model correction of the correction model KM is required. If such a model correction is necessary, it is carried out in a step 110.9 based on the imaging error of the projection exposure system 101 detected in step 110.7. In both cases, a check is then made in a step 110.10 as to whether the process should be ended. If this is the case, the process is ended in a step 110.11. Otherwise, the system jumps back to step 110.2.

In certain variants, the imaging error is corrected in the imaging error correction step 110.5 (if necessary alone) via 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). For this purpose, the relevant second active support unit 108.2 has an active deformation unit (not shown) which, controlled by the control device 106, deforms the associated second optical element M1 or M3 in at least one degree of freedom DOF (up to all six degrees of freedom DOF). sets the maximum control bandwidth RBM2 for the second optical element M1 or M3. The control device 106 therefore specifies a so-called correction pass KP for the second optical element M1 or M3, which is then activated via a corresponding control of the relevant second active support unit 108.2 (by the control device 106) on the assigned second optical element M1 or M3 is set.

It goes without saying that the position of the second optical element M1 or M3 does not necessarily have to be set with a maximum control bandwidth RBM2 from the second control bandwidth range RBB2. In these cases, it is also possible to set the position of the relevant second optical element M1 or M3 with a maximum control bandwidth RBM from the first control bandwidth range RBB1, i.e. only the deformation of the second optical element M1 or M3 with a maximum control bandwidth RBM2 to set the second control bandwidth range RBB2.

However, it is understood that the correction of the imaging error in the imaging error correction step 110.5 (if necessary alone) can also take place via a position adjustment of the relevant second optical element M1 or M3 with the maximum control bandwidth RBM2 from the second control bandwidth range RBB2. For this purpose, the associated second active support unit 108.2 can then have an active position adjusting unit (not shown in detail), which in the aberration correction step 110.5, controlled by the control device 106, determines a position and/or orientation of the associated 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. A so-called correction position KL can therefore also be specified for the relevant second optical element M1 or M3, which is then set via a corresponding control of the relevant second active support unit 108.2 on the associated second optical element M1 or M3. It goes without saying that the control device 106 can also specify an overlay of correction pass KP and correction position KL.

As already mentioned several times, the control device 106 can of course (depending on the above-mentioned information recorded via the detection device) further correct the imaging error 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 to achieve a desired low overall imaging error in the image.

The determination of the control information required for controlling the relevant second active support unit 108.2 (and possibly the further component 103, 105), i.e. the correction information KI, can in principle be carried out in any suitable manner. In the present example, the control device 106 uses a stored correction model KM to control the relevant second active support unit 108.2 and possibly the at least one further component 103, 105 of the imaging device 101 in the imaging error correction step 110.5 in order to at least reduce the imaging error, in particular to essentially eliminate it. #

The correction model KM can, depending on the first position information LI1, provide control information or correction information Kl for controlling the relevant second active support unit 108.2.

In the present example, the correction model KM supplies the control information or correction information Kl for controlling the relevant second active support unit 108.2, also depending on the first deformation information DI1. Likewise, in certain variants, the correction model can also provide the control information or correction information Kl for controlling the relevant second active support unit 108.2 depending on the last imaging error information AFI. The correction model KM can optionally provide control information for controlling an active third support unit 103.5 or 105.5 of the further component 103 or 105 of the imaging device, depending on the first position information and/or the first deformation information and/or the imaging error information. In this way, the greatest possible correction or reduction of the entire imaging error can be achieved in a particularly simple and inexpensive manner.

The correction model KM can in principle have been determined in any suitable way. So it can be created purely theoretically on the basis of purely numerical modeling of the optical arrangement and possibly the entire imaging device 101. Likewise, it can have been created on the basis of measurements on an optical arrangement and possibly an entire imaging device, which is at least a comparable or identical optical arrangement or imaging device, but preferably the specific optical arrangement or imaging device 101 itself. Of course, mixed forms of these two extremes are also possible and are typically particularly cheap.

As mentioned, the correction model KM can basically be a static model that remains unchanged at least over a longer operating period. As in the present example, it is preferably an adaptive model that is adapted from time to time, namely in step 110.8, to the actual conditions of the optical arrangement or the imaging device 101. A self-adapting algorithm can be implemented, which in step 110.8 is only triggered by certain temporal events (e.g. at certain predetermined intervals) and/or by non-temporal events (start of operation and/or end of operation, change of setting of the lighting device and/or the Projection device, reaching certain predetermined operating parameters, e.g. the temperature at certain components, exceeding an imaging error tolerance, etc.) checks the effectiveness of the correction of the imaging error and carries out a corresponding correction of the correction model in step 110.9.

In the present example, the control device 106 is accordingly designed to correct the correction model KM in the model correction step 110.9 depending on at least one image error information AFI, which results from a previous image error correction step 110.5 (and was detected in a step 110.7), in particular depending on the Image error information that results from the immediately preceding image error correction step 110.5. If necessary, several imaging error information AFI from several (possibly immediately) successive steps 110.7 can also flow into the correction, for example in order to take into account the development of the imaging error over time and to adequately correct the correction model KM. In the present example, the control device 106 is designed to use the correction model KM corrected in the last previous model correction step 110.9 in the imaging error correction step 110.5. This makes it possible to implement an adaptive correction model KM in a particularly cost-effective manner.

It is understood that the detection device 109 can basically only detect the corresponding above-mentioned detection variables or information for the first subgroup UG1 and these can be used to actuate the second subgroup UG2 and, if necessary, the further component(s) 103, 105. In the present example, however, an analog detection also takes place on the second or for the second subgroup UG2 in order to achieve a particularly favorable and effective correction in the imaging error correction step 110.5.

In the present example, the detection device 109 is therefore designed to detect second position information LI2 for the relevant second optical element M1, M3 in step 110.3, which represents a position and/or orientation of the relevant second optical element M1, M3 with respect to the reference R is representative in at least one degree of freedom DOF (up to all six degrees of freedom DOF in space). In addition, the detection device is designed to detect second deformation information DI2 for the relevant second optical element M1, M3, which is responsible 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 ) is representative. The control device 106 is then designed to control the relevant second active support unit 108.2 in the imaging error correction step 110.5 as a function of the second position information LI2 and as a function of the second deformation information DI2.

In the present example, the correction model KM supplies the control information or correction information Kl for controlling the relevant second active support unit 108.2 as a function of the second position information LI2 and the second deformation information DI2.

It goes without saying that the optical arrangement described here can in principle be used in imaging devices 101 of any design or composition. In particular, the group G optical elements can include any number of optical elements. The same applies to the division of the group of optical elements into the first and second subgroups. 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 equal to 3 to 8, further ahead preferably equal to 4 to 6. Additionally or alternatively, the number K can finally be 1 to 12, preferably 4 to 10, more preferably 6 to 8. Therefore, for example, a single correction element can be sufficient to achieve the desired low imaging error (possibly together with the described actuation of one or more other components). In all of these cases, particularly favorable constellations arise in which small imaging errors are possible with comparatively little effort for the first subgroup.

The assignment of the optical elements M1 to M6 to the first and second subgroups UG1, UG2 can in principle be carried out according to any criteria. Typically, those optical elements are assigned to the first subgroup UG1, the setting of which is particularly difficult with a maximum control bandwidth RBM from the second control bandwidth range RBB2. Furthermore, it is possible to assign certain optical elements to the first subgroup UG1, although actuation with a maximum control bandwidth RBM from the second control bandwidth range RBB2 would be possible for them. In this way, a reduction in effort can also be achieved for such optical elements. As already mentioned, in the second subgroup UG2 it is possibly also possible to set the position of the second optical element M1, M3 with a maximum control bandwidth RBM from the first control bandwidth range RBB1, i.e. then only the deformation of the second optical element M1, M3 with a set the maximum control bandwidth RBM2 from the second control bandwidth range RBB2.

Particularly favorable constellations arise when, as in the present example, the first subgroup UG1 comprises the largest optical element M6 of the group of optical elements, which here is also the heaviest optical element of the group G of optical elements. In addition, the first subgroup UG1 includes 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.

Furthermore, the second subgroup includes 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. In addition, the second subgroup UG2 includes 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 using examples from the field of microlithography. However, it is understood that the invention can also be used in connection with any other optical applications, in particular imaging methods at other wavelengths, in which similar problems arise with regard to the active correction of imaging errors.

Furthermore, the invention can be used in connection with the inspection of objects, such as so-called mask inspection, in which the masks used for microlithography are examined for their integrity, etc. Wafer 105.1 is then replaced by 1 for example, a sensor unit that captures the image of the projection pattern of the reticle 104.1 (for further processing). This mask inspection can then take place at essentially the same wavelength that is used in the later microlithography process. However, any wavelengths that deviate from this can also be used for the inspection.

The present invention was finally described above using concrete exemplary embodiments, which show concrete combinations of the features defined in the following patent claims. It should be expressly pointed out at this point that the subject matter of the present invention is not limited to these combinations of features, but all other combinations of features, as resulting from the following patent claims, also belong to the subject matter of the present invention.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2013004403 A1 [0009]
• DE 102008009600 A1 [0054, 0058]
• US 20060132747 A1 [0056]
• EP 1614008 B1 [0056]
• US 6573978 [0056]
• US 20180074303 A1 [0067]

Claims (19)

Optical arrangement of an imaging device for microlithography, in particular for the use of light in the extreme UV range (EUV), with - 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 of N optical elements (M1 to M6), which are supported on the support structure (104.2) via the active support device (108), - the active support device (108) for each optical element (M1 to M6) the group of optical elements comprises an active support unit (108.1, 108.2), which is designed to support the optical element on the support structure (104.2) in an adjustable manner controlled by the control device (106), - the group of optical elements comprises a first subgroup with a A plurality of M 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 one of the respective first optical The first active support unit (108.1) assigned to the element (M2, M4, M5, M6) is designed to provide the first optical element (M2, M4, M5, M6) with a maximum control bandwidth, which lies in a first control bandwidth range, in at least one degree of freedom to adjust, - the control device (106) and a second active support unit (108.2) assigned to the respective second optical element (M1, M3) are designed to control the second optical element (M1, M3) with a maximum control bandwidth, which is in a second Control bandwidth range is to be adjusted and/or deformed in at least one degree of freedom, characterized in that - the first control bandwidth range lies below the second control bandwidth range and is spaced from the second control bandwidth range by a distance, wherein - the distance is at least 50%, preferably at least 100 %, more preferably at least 125%, of an upper limit of the first control bandwidth range. and/or - the distance is at least 40 Hz to 80 Hz, preferably 50 Hz to 175 Hz, more 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, more preferably ranges from 90 Hz to 120 Hz, and / or - the second control bandwidth range ranges from 180 Hz to 260 Hz, preferably from 200 Hz to 250 Hz ranges, more preferably from 220 Hz to 250 Hz, Optical arrangement according to Claim 1 or 2 , wherein - the control device (106) is connected to a detection device (109), wherein - the detection device (109) is designed to detect first position information at least for the first optical elements (M2, M4, M5, M6). is representative of a respective position and/or orientation of the first optical element (M2, M4, M5, M6) with respect to a reference (R) in at least one degree of freedom, and/or - the detection device (109) is designed to do so, at least for first optical elements (M2, M4, M5, M6) to detect first deformation information which is representative of a respective deformation of the first optical element (M2, M4, M5, M6) in at least one degree of freedom, and / or - the detection device ( 109) is designed to detect imaging error information that is representative of an imaging error of the imaging device (101), wherein - the control device (106) is designed to control the at least one second active support unit (108.2) depending on the first position information and / or to control depending on the first deformation information and / or depending on the imaging error information. Optical arrangement according to Claim 3 , wherein - the group of optical elements causes an imaging error in the imaging device (101) during operation and - the control device (106) is designed to control the at least one second active support unit (108.2) alone or in combination with at least one further component (103, 105 ) the imaging device (101) in an imaging error correction step (110.5) in such a way that the imaging error is at least reduced, in particular essentially eliminated, in particular - the at least one second active support unit (108.2) has an active deformation unit which is controlled by the control device (106) sets a deformation of the associated 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) is an active one Position adjusting unit, which, controlled by the control device (106), sets a position and/or orientation of the associated second optical element (M1, M3) in at least one degree of freedom with the maximum control band width 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). Optical arrangement according to Claim 4 , wherein - the control device (106) uses a stored correction model to control 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 the imaging error correction step (110.5) to correct the imaging error at least to reduce, in particular to essentially eliminate, wherein - the correction model, depending on the first position information, provides control information for controlling the at least one second active support unit (108.2), and / or - the correction model, depending on the first deformation information, provides control information for Controlling the at least one second active support unit (108.2), and/or - the correction model, depending on the imaging error information, supplies control information for driving the at least one second active support unit (108.2), where appropriate - the correction model depending on the first position information and / or the first deformation information and / or the imaging error information provides control information for controlling an active third support unit (103.5, 105.5) of the at least one further component (103, 105) of the imaging device (101). Optical arrangement according to Claim 5 , wherein - the control device (106) is designed to correct the correction model in a model correction step (110.9) depending on the imaging error information from a previous imaging error correction step (110.5), in particular depending on the imaging error information from the immediately preceding imaging error correction step (110.5), and - the control device (106) is designed to use the correction model corrected in the model correction step (110.9) in the imaging error correction step (110.5). Optical arrangement according to one of the Claims 3 until 6 , wherein - the detection device (109) is designed to detect second position information for the at least one second optical element (M1, M3), which is for a position and / or orientation of the at least one second optical element (M1, M3) with respect to a reference (R) is representative in at least one degree of freedom, and / or - the detection device (109) is designed to detect second deformation information for the at least one second optical element (M1, M3), which is responsible for a deformation of the at least one second optical element (M1, M3) is representative in at least one degree of freedom, wherein - the control device (106) is designed to control the at least one second active support unit (108.2) depending on the second position information and / or depending on the second deformation information head for. Optical arrangement according to Claim 5 and 7 , wherein - the correction model, depending on the second position information, supplies the control information for controlling the at least one second active support unit (108.2), and / or - the correction model, depending on the second deformation information, provides the control information for controlling the at least one second active support unit (108.2 ). which results from the immediately preceding aberration correction step (110.5), and the control device (106) is designed to use in the aberration correction step (110.5) the correction model corrected in the last previous model correction step (110.9). Optical arrangement according to one of the Claims 1 until 8th , wherein - the majority N is equal to 2 to 12, preferably equal to 4 to 10, more preferably equal to 6 to 8, and / or - the majority M is equal to 2 to 10, preferably equal to 3 to 8, more preferably equal 4 to 6, and/or - the number K is 1 to 12, preferably 4 to 10, more preferably 6 to 8, and/or - the first subgroup is the largest optical element (M6) of the optical group Comprises elements and/or comprises 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 includes and/or - the second subgroup contains the smallest optical element ment (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) includes the group of optical elements. Optical imaging device, in particular for microlithography, with - an illumination device (102) with a first group of optical elements (102.2), - an object device (103) for recording an object (103.3), - a projection device (104) with a second group of optical Elements (104.1) and - an image device (105), wherein - the lighting device (102) is designed to illuminate the object (103.3) and - the projection device (104) is designed to project an image of the object (103.3) onto the image device (105) is designed, characterized in that - the projection device (104) has at least one optical arrangement (108; 208) according to one of Claims 1 until 9 includes, Method for supporting a group of optical elements on a support structure (104.2) of an imaging device for microlithography, in particular for the use of light in the extreme UV range (EUV), in which - the group of optical elements includes a plurality of N optical elements (M1 to M6 ), which are supported on the support structure (104.2) via the active support device (108), the group of optical elements comprising 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 adjustable on the support structure (104.2) by an active support unit, - the respective first optical element (M2, M4, M5, M6). an assigned first active support unit (108.1) with a maximum control bandwidth, which lies in a first control bandwidth range, is adjusted in at least one degree of freedom, - the respective second optical element (M1, M3) via an assigned second active support unit (108.2) with a maximum Control bandwidth, which lies in a second control bandwidth range, is adjusted and/or deformed in at least one degree of freedom, characterized in that - the first control bandwidth range lies below the second control bandwidth range and is spaced from the second control bandwidth range by a distance, wherein - the distance is at least 50 %, preferably at least 100%, more preferably at least 125%, of an upper limit of the first control bandwidth range. and/or - the distance is at least 40 Hz to 80 Hz, preferably 50 Hz to 175 Hz, more preferably 75 Hz to 125 Hz. Procedure 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, more preferably ranges from 90 Hz to 120 Hz, and / or - the second control bandwidth range ranges from 180 Hz to 260 Hz, preferably from 200 Hz to 250 Hz ranges, more preferably from 220 Hz to 250 Hz, Procedure according to Claim 11 or 12 , wherein - at least for the first optical elements (M2, M4, M5, M6) a first position information is recorded, which is for a respective position and / or orientation of the first optical element (M2, M4, M5, M6) with respect to a reference (R) is representative in at least one degree of freedom, and / or - at least for the first optical elements (M2, M4, M5, M6) a first deformation information is recorded, which is for a respective deformation of the first optical element (M2, M4, M5 , M6) is representative in at least one degree of freedom, and / or - an imaging error information is recorded which is representative of an imaging error of the imaging device (101), wherein - the at least one second active support unit (108.2) depending on the first position information and / or is controlled as a function of the first deformation information and/or as a function of the imaging error information. Procedure according to Claim 13 , wherein - the group of optical elements causes an imaging error of the imaging device (101) during operation and - 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 error correction step (110.5) is controlled in such a way that the imaging error is at least reduced, in particular essentially eliminated, in particular - the at least one second active support unit (108.2) has an active deformation unit, via which a deformation of the assigned second optical element (M1, M3 ) is set 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 position adjustment unit the position and/or orientation of the associated second optical element (M1, M3) is set 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 Image device (105) or an object device (105) of the imaging device (101). Procedure according to Claim 14 , wherein - to control the at least one second active support unit (108.2) and optionally the at least one further component of the imaging device in the imaging error correction step (110.5) a stored correction model is used in order to at least reduce the imaging error, in particular to essentially eliminate it, wherein - the correction model supplies control information for controlling the at least one second active support unit (108.2) as a function of the first position information, and/or - the correction model supplies control information for controlling the at least one second active support unit (108.2) as a function of the first deformation information, and/or - the correction model provides control information for controlling the at least one second active support unit (108.2) as a function of the imaging error information, wherein optionally - the correction model provides control information as a function of the first position information and/or the first deformation information and/or the imaging error information for controlling an active third support unit (103.5, 105.5) which supplies at least one further component (103, 105) of the imaging device (101). Procedure according to Claim 15 , wherein - the correction model is corrected in a model correction step (110.9) depending on at least one image error information that results from a previous image error correction step (110.5), in particular corrected as a function of the image error information that results from the immediately preceding image error correction step (110.5). and - in the imaging error correction step (110.5) the correction model corrected in the last previous model correction step (110.9) is used. Procedure according to one of the Claims 13 until 16 , wherein - for the at least one second optical element (M1, M3), a second position information is recorded, which is representative of a position and / or orientation of the at least one second optical element (M1, M3) with respect to a reference in at least one degree of freedom , and / or - for the at least one second optical element (M1, M3), a second deformation information is recorded, which is representative of a deformation of the at least one second optical element (M1, M3) in at least one degree of freedom, whereby - the at least one second active support unit (108.2) is controlled depending on the second position information and / or depending on the second deformation information. Procedure according to Claim 15 and 17 , wherein - the correction model, depending on the second position information, supplies the control information for controlling the at least one second active support unit (108.2), and / or - the correction model, depending on the second deformation information, provides the control information for controlling the at least one second active support unit (108.2 ) provides, in particular - correcting the correction model in a model correction step (110.9) depending on the imaging error information from a previous imaging error correction step (110.5), in particular depending on the imaging error information from the immediately preceding imaging error correction step (110.5), and in the imaging error correction step (110.5 ) the correction model corrected in the model correction step (110.9) is used. Optical imaging method, in particular for microlithography, in which - 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 ), an image of the object (103.3) is projected 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) by means of a method Claim 11 until 18 be supported.

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