PROJECTION EXPOSURE APPARATUS AND METHOD FOR DESIGNING A COMPONENT OF A PROJECTION EXPOSURE APPARATUS

A component for a projection exposure apparatus for semiconductor lithography, comprises an optical element and an actuator, which are force-fittingly connected to each other. The actuator at least locally deforms the optical element. The actuator can be configured to minimize the loss in rigidity at the peripheries delimiting the actuator on the imaging quality. A method for designing a component of projection exposure apparatus is provided.

FIELD

The disclosure relates to a component for a projection exposure apparatus for semiconductor lithography and to a method for designing the component, such as for minimizing undesirable effects of parasitic deformations caused by an actuator on the imaging quality of the projection exposure apparatus.

BACKGROUND

In projection exposure apparatuses for semiconductor lithography, optical elements, such as lens elements and/or mirrors, are used for imaging a lithography mask, such as, for example, a phase mask, also known as a reticle, onto a semiconductor substrate, also known as a wafer.

In order to help achieve a high resolution especially of lithography optical units, EUV light having a wavelength of, for example, between 1 nm and 120 nm, such as in the region of 13.5 nm, has also been used for some years, in comparison with predecessor systems having typical wavelengths of 365 nm, 248 nm or 193 nm.

Some of the optical elements used in that case are manipulated, for example, mechanically in order to improve the imaging quality and in order to correct disturbances that occur during operation, wherein a distinction is drawn between a pure shift of the optical elements and a deformation of the optical elements.

In the case of deformable mirrors, actuators, for example in the form of an actuator matrix, are known to have been adhesively connected or bonded to the rear side of the mirrors to create a mechanical connection for a targeted deformation.

Actuator matrices which are embodied in the form of a quadrangular plate and comprise a plurality of interconnected actuator pads are known. The individual actuator pads typically have a quadrangular or triangular shape and comprise holes typically arranged at the corners or sides of the actuator pads. These can have the function that the actuator pads can be contacted to controllers. A physics-related loss of rigidity of the combination of the actuator with the optical element can occur at all peripheries of the actuator, that is to say at the outer edges of the plate of the actuator matrix and the peripheries of the holes, which loss results in parasitic deformations in the region of the peripheries during the actuation or for example due to different thermal expansions based on different coefficients of thermal expansion. This can negatively influence the imaging quality of the projection exposure apparatus.

Due to the scanning mode of operation of certain modern lithography systems, that is to say the movement of the phase mask underneath an illumination slit and a movement of the wafer in an opposite direction, aberrations, which can be caused by the parasitic deformations described, along the scanning direction can add up, which can makes the undesirable effect more pronounced.

SUMMARY

The present disclosure seeks to provide an improved component. The disclosure also seeks to provide a method for designing the component.

A component according to the disclosure for a projection exposure apparatus for semiconductor lithography comprises an optical element and an actuator. The optical element and the actuator are force-fittingly connected to each other, wherein the actuator is configured to at least locally deform the optical element. According to the disclosure, the actuator can be embodied such that the influence of the loss in rigidity at the peripheries delimiting the actuator on the imaging quality is minimized. The force-fitting connection between the actuator and the optical element, such as a mirror, can be brought about by an adhesive connection or bonding or by a releasable connection, such as a screw connection.

In a first embodiment of the disclosure, the actuator can be embodied in the form of an actuator matrix comprising at least two actuator pads. The actuator matrix typically comprises between 9 and 30 actuator pads.

In particular, the cumulative length of the peripheral sections of the actuator extending on an axis parallel to a scanning direction used in the projection exposure apparatus can be minimized. The scanning exposure method used in projection exposure apparatuses can mean that some optical effects of disturbances extending perpendicular to the scanning direction, such as parasitic deformations, are averaged out by the scanning operation and thus minimized.

Furthermore, the outer peripheries of the actuators can be aligned, at least in sections, at an angle to the scanning direction. As a result, the portion of the sections of the peripheries extending in the scanning direction which is summed through the scanning operation can be minimized.

In particular, the actuator can include a peripheral contour meandering around the scanning direction. The contour can be realized, for example, by a hexagonal shape of the actuator pads and by a shift of the actuator pads arranged in rows by half the width of an actuator pad, wherein protrusions of the actuator pads partially protrude into recesses of adjacent pads.

In addition, a straight peripheral structure of the actuator can be aligned at an angle to the scanning direction. This can mean that no more portions, which are aligned in the scanning direction, of the peripheries delimiting the actuator are present. However, it may be desirable to take into account a possible construction-type-related influence of the inclination of the actuator on the deformation effect of the actuator with respect to an optically effective surface.

In particular, holes for contacting the actuator pads formed in the actuator matrix can be designed such that the cumulative length of the edge sections of the holes extending on an axis parallel to a scanning direction used in the projection exposure apparatus is reduced.

This can be accomplished, for example, in that the area of at least some of the holes is minimized, as a result of which the cumulative overall length of the edges of all holes is reduced. The holes can be formed at the corners, the sides, within the effective surface of the actuator pad or in a combination of these positions. The size of the holes is defined by the space for contacting.

Furthermore, the holes can be arranged such that the number of the holes arranged on an axis extending parallel to the scanning direction is minimal. The parasitic aberration summed by the scanning movement thus becomes minimal. The number of the holes located on an axis can be reduced, for example, by an advantageous arrangement of the holes with respect to the actuator pads, as described further above.

In a further embodiment of the disclosure, the actuator pads can have a triangular, a rectangular or a hexagonal geometry. In addition to the geometry of the actuator pads, the number of the rows and columns of the actuator matrices formed by the actuator pads can also be freely selectable, with the result that for example matrices of three rows and three columns up to five rows and five columns or more are conceivable. Nor does the number of rows and columns need to be identical, and a matrix with four rows and six columns can thus also be formed.

In a further embodiment of the disclosure, the actuator can have a separately controllable section for correcting the loss in rigidity. It thereby can become possible to take into account the rigidity, which deviates in the region of the intermediate spaces, of the overall system composed of actuator pad and mirror material by correspondingly modified control of the section, as a result of which an undesired movement/deformation is counteracted and a resulting possible image error can be avoided.

In particular, the section can be formed as a peripheral actuator pad in an actuator pad arranged in the peripheral region of the actuator matrix and can be controllable independently of the second region of the actuator pad formed as a partial actuator pad and be configured for correcting the parasitic deformations caused by the loss in rigidity. Owing to the peripheral actuator pad, the deformation effect at the periphery can be increased in comparison with a non-divided actuator pad, as a result of which the loss in rigidity can be compensated.

A method according to the disclosure for designing a component of a projection exposure apparatus with an optical element and an actuator for minimizing the effects of parasitic deformations in the case of the deformation of the optical element caused by the actuator on the imaging quality of the projection exposure apparatus comprises the following method steps:designing the actuator,determining the parasitic deformations of the optical element caused by an actuation or by different coefficients of thermal expansion of the optical element and the actuator,determining the parasitic aberrations on the basis of the parasitic deformations while taking into account the summing effect of a scanning exposure used in the projection exposure apparatus,optimizing the actuator on the basis of the determined parasitic aberrations,repeating at least some of the preceding process steps until the value for the parasitic aberration falls under a predetermined value.

The parasitic deformations can be determined for example by FEM simulations or on the optically effective surface of the optical element via an optical measuring technique. The parasitic aberrations can be determined by simulations based on the parasitic deformations or by measurements on the component level or in the overall system, that is to say in the projection exposure apparatus.

Furthermore, at least a part of a travel of the actuator can be used to correct the parasitic deformations. This self-correction, as it is known, can mean that the errors can be compensated at the site where they occur.

In addition, the projection exposure apparatus can comprise a mechanism for optimizing the imaging quality can be taken into account when determining the resulting parasitic aberrations.

In particular, the mechanism can include manipulators for positioning or deforming further optical elements of the projection exposure apparatus. Typically, almost all optical elements of the projection exposure apparatus are manipulable, and therefore a large selection of additional correction mechanisms may be available.

Furthermore, one approach can involve an algorithm based on simulations for the prediction of the imaging quality while taking into account a multiplicity of influence parameters and the determination of the travels of the manipulators therefor.

EXEMPLARY EMBODIMENTS

Certain integral parts of a microlithographic projection exposure apparatus1are described in exemplary fashion below initially with reference toFIG.1. The description of the fundamental construction of the projection exposure apparatus1and the integral parts thereof is understood here to be non-limiting.

An embodiment of an illumination system2of the projection exposure apparatus1has, in addition to a radiation source3, an illumination optical unit4for illuminating an object field5in an object plane6. In an alternative embodiment, the light source3can also be provided as a module separate from the rest of the illumination system. In this case, the illumination system does not comprise the light source3.

A reticle7arranged in the object field5is exposed. The reticle7is held by a reticle holder8. The reticle holder8is displaceable by way of a reticle displacement drive9, in particular in a scanning direction.

A Cartesian xyz-coordinate system is shown inFIG.1for explanation purposes. The x-direction runs perpendicular to the plane of the drawing into the latter. The y-direction runs horizontally and the z-direction runs vertically. The scanning direction runs along the y-direction inFIG.1. The z-direction runs perpendicular to the object plane6.

The projection exposure apparatus1comprises a projection optical unit10. The projection optical unit10serves for imaging the object field5into an image field11in an image plane12. The image plane12runs parallel to the object plane6. Alternatively, an angle between the object plane6and the image plane12that differs from 0° is also possible.

A structure on the reticle7is imaged onto a light-sensitive layer of a wafer13arranged in the region of the image field11in the image plane12. The wafer13is held by a wafer holder14. The wafer holder14is displaceable by way of a wafer displacement drive15, in particular along the y-direction. The displacement, on the one hand, of the reticle7by way of the reticle displacement drive9and, on the other hand, of the wafer13by way of the wafer displacement drive15can take place in such a way as to be synchronized with one another.

The radiation source3is an EUV radiation source. The radiation source3emits, in particular, EUV radiation16, which is also referred to below as used radiation, illumination radiation or illumination light. In particular, the used radiation has a wavelength in the range between 5 nm and 30 nm. The radiation source3can be a plasma source, for example an LPP (laser produced plasma) source or a GDPP (gas discharge produced plasma) source. It can also be a synchrotron-based radiation source. The radiation source3can be a free electron laser (FEL).

The illumination radiation16emerging from the radiation source3is focused by a collector17. The collector17may be a collector with one or with a plurality of ellipsoidal and/or hyperboloidal reflection surfaces. The illumination radiation16can impinge on the at least one reflection surface of the collector17with grazing incidence (GI), that is to say at angles of incidence of greater than 45°, or with normal incidence (NI), that is to say at angles of incidence of less than 45°. The collector17can be structured and/or coated, firstly, for optimizing its reflectivity for the used radiation and, secondly, for suppressing extraneous light.

Downstream of the collector17, the illumination radiation16propagates through an intermediate focus in an intermediate focal plane18. The intermediate focal plane18can represent a separation between a radiation source module, having the radiation source3and the collector17, and the illumination optical unit4.

The illumination optical unit4comprises a deflection mirror19and, arranged downstream thereof in the beam path, a first facet mirror20. The deflection mirror19can be a plane deflection mirror or, alternatively, a mirror with a beam-influencing effect that goes beyond the purely deflecting effect. Alternatively or in addition, the deflection mirror19can be in the form of a spectral filter which separates a used light wavelength of the illumination radiation16from extraneous light with a wavelength deviating therefrom. If the first facet mirror20is arranged in a plane of the illumination optical unit4that is optically conjugate to the object plane6as a field plane, it is also referred to as a field facet mirror. The first facet mirror20comprises a multiplicity of individual first facets21, which are also referred to below as field facets.FIG.1depicts only some of the facets21by way of example.

The first facets21can be in the form of macroscopic facets, in particular as rectangular facets or as facets with an arcuate peripheral contour or a peripheral contour of part of a circle. The first facets21may be in the form of plane facets or alternatively as convexly or concavely curved facets.

As known for example from DE 10 2008 009 600 A1, the first facets21themselves may also be composed in each case of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. The first facet mirror20can in particular be formed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1.

Between the collector17and the deflection mirror19, the illumination radiation16travels horizontally, that is to say along the y-direction.

In the beam path of the illumination optical unit4, a second facet mirror22is arranged downstream of the first facet mirror20. If the second facet mirror22is arranged in a pupil plane of the illumination optical unit4, it is also referred to as a pupil facet mirror. The second facet mirror22can also be arranged at a distance from a pupil plane of the illumination optical unit4. In this case, the combination of the first facet mirror20and the second facet mirror22is also referred to as a specular reflector. Specular reflectors are known from US 2006/0132747 A1, EP 1 614 008 B1 and U.S. Pat. No. 6,573,978.

The second facet mirror22comprises a plurality of second facets23. In the case of a pupil facet mirror, the second facets23are also referred to as pupil facets.

The second facets23can likewise be macroscopic facets, which can for example have a round, rectangular, or hexagonal periphery, or alternatively be facets made up of micromirrors. In this regard, reference is likewise made to DE 10 2008 009 600 A1.

The second facets23can have plane or alternatively convexly or concavely curved reflection surfaces.

The illumination optical unit4consequently forms a doubly faceted system. This fundamental principle is also referred to as a fly's eye condenser (fly's eye integrator).

It can be advantageous to arrange the second facet mirror22not exactly in a plane that is optically conjugate to a pupil plane of the projection optical unit10. In particular, the pupil facet mirror22can be arranged so as to be tilted relative to a pupil plane of the projection optical unit10, as is described, for example, in DE 10 2017 220 586 A1.

The individual first facets21are imaged into the object field5with the aid of the second facet mirror22. The second facet mirror22is the last beam-shaping mirror or else, in fact, the last mirror for the illumination radiation16in the beam path upstream of the object field5.

In a further embodiment, not shown, of the illumination optical unit4, a transfer optical unit contributing in particular to the imaging of the first facets21into the object field5can be arranged in the beam path between the second facet mirror22and the object field5. The transfer optical unit can have exactly one mirror or else alternatively two or more mirrors, which are arranged one behind the other in the beam path of the illumination optical unit4. The transfer optical unit can in particular comprise one or two normal-incidence mirrors (NI mirrors) and/or one or two grazing-incidence mirrors (GI mirrors).

In the embodiment shown inFIG.1, the illumination optical unit4has exactly three mirrors downstream of the collector17, specifically the deflection mirror19, the field facet mirror20and the pupil facet mirror22.

The deflection mirror19can also be dispensed with in a further embodiment of the illumination optical unit4, and so the illumination optical unit4can then have exactly two mirrors downstream of the collector17, specifically the first facet mirror20and the second facet mirror22.

The imaging of the first facets21into the object plane6via the second facets23or using the second facets23and a transfer optical unit is, as a rule, only approximate imaging.

The projection optical unit10comprises a plurality of mirrors Mi, which are consecutively numbered in accordance with their arrangement in the beam path of the projection exposure apparatus1.

In the example illustrated inFIG.1, the projection optical unit10comprises six mirrors M1to M6. Alternatives with four, eight, ten, twelve or any other number of mirrors Mi are similarly possible. The penultimate mirror M5and the last mirror M6each have a through opening for the illumination radiation16. The projection optical unit10is a double-obscured optical unit. The projection optical unit10has an image-side numerical aperture which is greater than 0.5 and which can also be greater than 0.6 and, for example, be 0.7 or 0.75.

Reflection surfaces of the mirrors Mi can be embodied 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. Just like the mirrors of the illumination optical unit4, the mirrors Mi can have highly reflective coatings for the illumination radiation16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

The projection optical unit10has a large object-image offset in the y-direction between a y-coordinate of a centre of the object field5and a y-coordinate of the centre of the image field11. In the y-direction, this object-image offset can be of approximately the same magnitude as a z-distance between the object plane6and the image plane12.

In particular, the projection optical unit10can have an anamorphic form. In particular, it has different imaging scales βx, βy in the x- and y-directions. The two imaging scales βx, βy of the projection optical unit10can be (βx, βy)=(+/−0.25, +/−0.125). A positive imaging scale β means imaging without image inversion. A negative sign for the imaging scale β means imaging with image inversion.

The projection optical unit10consequently leads to a reduction in size with a ratio of 4:1 in the x-direction, that is to say in a direction perpendicular to the scanning direction.

The projection optical unit10leads to a reduction in size of 8:1 in the y-direction, that is to say in the scanning direction.

Other imaging scales are similarly possible. Imaging scales with the same sign and the same absolute value in the x-direction and y-direction are also possible, for example with absolute values of 0.125 or of 0.25.

The number of intermediate image planes in the x-direction and in the y-direction in the beam path between the object field5and the image field11can be the same or, depending on the embodiment of the projection optical unit10, can differ. Examples of projection optical units with different numbers of such intermediate images in the x- and y-directions are known from US 2018/0074303 A1.

In each case one of the pupil facets23is assigned to exactly one of the field facets21for forming in each case an illumination channel for illuminating the object field5. In particular, this can yield illumination according to the Köhler principle. The far field is decomposed into a multiplicity of object fields5with the aid of the field facets21. The field facets21produce a plurality of images of the intermediate focus on the pupil facets23respectively assigned thereto.

By way of respectively assigned pupil facets23, the field facets21are imaged onto the reticle7in a manner superposed on one another for the purposes of illuminating the object field5. The illumination of the object field5is in particular as homogeneous as possible. It can have a uniformity error of less than 2%. The field uniformity can be achieved by way of the superposition of different illumination channels.

The illumination of the entrance pupil of the projection optical unit10can be defined geometrically by way of an arrangement of the pupil facets. The intensity distribution in the entrance pupil of the projection optical unit10can be set by selecting the illumination channels, in particular the subset of the pupil facets which guide light. This intensity distribution is also referred to as illumination setting.

A likewise preferred pupil uniformity in the region of sections of an illumination pupil of the illumination optical unit4which are illuminated in a defined manner can be achieved by a redistribution of the illumination channels.

Further aspects and details of the illumination of the object field5and in particular of the entrance pupil of the projection optical unit10are described below.

In particular, the projection optical unit10can have a homocentric entrance pupil. The latter can be accessible. It can also be inaccessible.

The entrance pupil of the projection optical unit10cannot, as a rule, be exactly illuminated using the pupil facet mirror22. In the case of imaging of the projection optical unit10which telecentrically images the centre of the pupil facet mirror22onto the wafer13, the aperture rays often do not intersect at a single point. However, it is possible to find an area in which the distance of the aperture rays determined in pairs becomes minimal. This area represents the entrance pupil or an area in real space that is conjugate thereto. In particular, this area has a finite curvature.

It may be the case that the projection optical unit10has different positions of the entrance pupil for the tangential beam path and for the sagittal beam path. In this case, an imaging element, in particular an optical component part of the transfer optical unit, should be provided between the second facet mirror22and the reticle7. With the aid of this optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

In the arrangement of the components of the illumination optical unit4illustrated inFIG.1, the pupil facet mirror22is arranged in an area conjugate to the entrance pupil of the projection optical unit10. The field facet mirror20is arranged in tilted fashion with respect to the object plane6. The first facet mirror20is arranged in tilted fashion with respect to an arrangement plane defined by the deflection mirror19.

The first facet mirror20is arranged in tilted fashion with respect to an arrangement plane defined by the second facet mirror22.

FIG.2schematically shows, in a meridional section, a further projection exposure apparatus101for DUV projection lithography, in which the disclosure can likewise be used.

The construction of the projection exposure apparatus101and the principle of the imaging are comparable with the construction and procedure described inFIG.1. Identical component parts are designated by a reference sign increased by100relative toFIG.1, i.e. the reference signs inFIG.2begin with101.

In contrast to an EUV projection exposure apparatus1as described inFIG.1, refractive, diffractive and/or reflective optical elements117, such as for example lens elements, mirrors, prisms, terminating plates, and the like, can be used for imaging or for illumination in the DUV projection exposure apparatus101on account of the greater wavelength of the DUV radiation116, used as used light, in the range from 100 nm to 300 nm, in particular of 193 nm. The projection exposure apparatus101in this case substantially comprises an illumination system102, a reticle holder108for receiving and exactly positioning a reticle107provided with a structure, by which the later structures on a wafer113are determined, a wafer holder114for holding, moving and exactly positioning the wafer113and a projection lens110, with a plurality of optical elements117, which are held by way of mounts118in a lens housing119of the projection lens110.

The illumination system102provides DUV radiation116, which is used for the imaging of the reticle107on the wafer113. A laser, a plasma source or the like can be used as the source of this radiation116. The radiation116is shaped in the illumination system102via optical elements such that the DUV radiation116has the desired properties with regard to diameter, polarization, shape of the wavefront and the like when it is incident on the reticle107.

Apart from the additional use of refractive optical elements117, such as lens elements, prisms, terminating plates, the construction of the downstream projection optical unit110with the lens housing119does not differ in principle from the construction described inFIG.1and is therefore not described in further detail.

FIG.3Ashows a component30known from the prior art, which comprises a mirror31and two actuators in the form of actuator matrices32. The actuator matrices32are arranged one next to the other on the rear side of the mirror31located opposite the optically effective surface (not illustrated) of the mirror31. Each actuator matrix32has a plurality of square actuator pads33, which are arranged in rows and columns and, at their corners, have holes34for contacting the actuator pads33with a controller (not illustrated). The plate-shaped actuator matrices32are rectangular, wherein two of the four peripheries of the actuator matrices32extend in the scanning direction, which is illustrated inFIG.3Aby a broad arrow. The holes34between the actuator pads33are located respectively one behind the other on an axis (indicated by a dashed line) extending parallel to the scanning direction. The parasitic deformations occurring are summed in the scanning direction and cause aberrations. The actuator matrices32can in principle also have a curved shape. The number of the actuator matrices32arranged on a mirror31is freely selectable, which is to say three, four or more actuator matrices32can also be formed on a mirror31. In the same way, the number of rows and columns of the actuator matrices32is also freely selectable. Components30can thus also comprise on the mirror31, in addition to the embodiment explained inFIG.3Awith two actuator matrices32with four rows and three columns, three actuator matrices32with five rows and five columns, or four matrices32with four rows and five columns or any other combination. The number of actuator matrices32and rows and columns is here predominantly dependent on the application and the producibility of the actuator matrices32.

FIG.3Bshows an illustration of the parasitic aberration summed over the scanning operation. These are caused by parasitic deformations due to peripheral effects of the actuator matrices32based on losses in rigidity. The point densities used in the figure here correspond to wavefront deviations in a positive or negative direction. Clearly visible are the aberrations, aligned in the scanning direction illustrated inFIG.3Bby a broad arrow, in the form of regions of identical point densities extending in the scanning direction.

FIG.4Ashows a component30according to the disclosure, which comprises a mirror31and, arranged one next to the other, two actuators in the form of actuator matrices35. Each actuator matrix35has actuator pads36having a hexagonal shape, which likewise have holes38at the corners for contacting the actuator pads36with a controller (not illustrated). The holes38are oval, wherein the longitudinal axis of the holes38is in each case aligned perpendicular to the scanning direction. The actuator pads36are arranged in rows37perpendicular to the scanning direction, which is illustrated inFIG.4Aby a broad arrow. The rows37are likewise arranged perpendicular to the scanning direction, in each case arranged in alternation offset from one another by half the width of an actuator pad. This results in a peripheral contour meandering around the scanning direction at the peripheries of the actuator matrix35that are located parallel to the scanning direction. The parasitic deformations brought about at the peripheral contour due to the losses in rigidity are thus advantageously averaged out by the scanning operation, and the resulting aberration is thus minimized. In addition to the adaptation of the peripheral contour with respect to the scanning direction, the narrower transverse axis of the oval holes38for contacting the actuator pads36is smaller than the diameter of the holes illustrated inFIG.3A, as a result of which the cumulative length of the edge sections of the holes38extending parallel to the scanning direction is reduced. Furthermore, the holes38on a plurality of axes, which are illustrated inFIG.4Aas dash-dotted lines, are arranged parallel to the scanning direction due to the hexagonal shape of the actuator pads36, as a result of which a smaller parasitic sum error is obtained per axis. As a result, the amplitude of the aberrations is advantageously minimized. In order to keep the distance between the adjacent actuator matrices35as small as possible, the actuator matrices35are arranged in intermeshed fashion. Consequently, the deformation effect of the actuator pads36over the abutting edges of two adjacent actuator matrices35is comparable to the actuator matrices32that are known from the prior art and have been explained inFIG.3A. As was already explained with respect toFIG.3A, the actuator matrices32can in principle also have a curved shape. Furthermore, the number of the actuator matrices32arranged on a mirror31is freely selectable, which is to say three, four or more actuator matrices32can also be formed on a mirror31. In the same way, the number of rows and columns of the actuator matrices32is also freely selectable. Components30can thus also comprise on the mirror31, in addition to the embodiment explained inFIG.4Awith two actuator matrices32with four rows and three columns, three actuator matrices32with five rows and five columns, or four matrices32with four rows and five columns or any other combination. The number of actuator matrices32and rows and columns is here predominantly dependent on the application and the producibility of the actuator matrices32.

In comparison with the illustration of the parasitic aberrations explained inFIG.3B,FIG.4Bshows a discernible reduction in the parasitic aberration summed by the scanning operation; which is discernible, firstly, by a reduction in the average absolute value of the point densities and, secondly, by a deviation of the profile of the regions of identical point densities and thus identical aberrations from the scanning direction.

FIGS.5A to5Fshow further alternative embodiments of an actuator matrix39.1,39.2,39.3,39.4,39.5,39.6, which have different geometries of the actuator pads40.1,40.2,40.3,40.4,40.5,40.6and different arrangements of the holes41.1,41.2,41.3,41.4,41.5,41.6for contacting. The different combinations of the geometry of the actuator pads40.1,40.2,40.3,40.4,40.5,40.6and of the shape and the arrangement of the holes41.1,41.2,41.3,41.4,41.5,41.6are illustrated below in a table. The scanning direction is illustrated in the figures by an arrow.

Actuator padReferenceFIG.geometryHole geometry and arrangementsigns5Asquareround; in the corners40.1, 41.15Brectangularround; at the edges and corners40.2, 41.25Crectangularround; in the corners and at the edges40.3, 41.35Dtriangularround; in the centre40.4, 41.45Etriangularoval; in alternation at the periphery40.5, 41.55Fsquareoval; at an angle with respect to40.6, 41.6the scanning direction

FIG.6shows a further embodiment of the disclosure illustrating a component30having a mirror31and three actuator matrices43. As has already been described further above, the parasitic deformation brought about by losses in rigidity in the peripheral region of the actuator matrix43is minimized by the scanning operation if the peripheral length of the actuator matrix43that lies on an axis that is aligned parallel to the scanning direction is minimized. In the exemplary embodiment illustrated inFIG.6, the entire periphery is aligned not parallel to the scanning direction owing to the trapezoidal shape of the actuator matrices43, as a result of which the parasitic aberrations caused by the parasitic deformations present in the peripheral region can be avoided nearly completely or can be advantageously averaged out to a major extent by the scanning operation.

FIG.7shows a detail view of a component30with a mirror31and an actuator pad51arranged at the periphery of an actuator which is embodied in the form of an actuator matrix50. The actuator pad51is divided into a partial actuator pad52and a peripheral actuator pad53, which are controllable independently from one another via a respective line54,55. This has the advantage that the deformation of the optically effective surface56which is caused by the peripheral actuator pad53and is indicated by a solid line inFIG.7is greater in the peripheral region than the deformation which is caused by a non-divided actuator pad and is illustrated by a dashed line inFIG.7. The parasitic deformations caused by the loss in rigidity in the peripheral region of the actuator matrix50are at least partially compensated thereby, as a result of which the parasitic aberrations are advantageously minimized.

FIG.8describes a possible method for designing a component30of a projection exposure apparatus1,101with an optical element31and an actuator32,35,39.x,43,50for minimizing the effects of parasitic deformations in the case of the deformation of the optical element31caused by the actuator32,35,39.x,43,50on the imaging quality of the projection exposure apparatus1,101.

The actuator32,35,39.x,43,50is designed in a first method step61.

In a second method step62, the parasitic deformations of the optical element31caused by an actuation or by different coefficients of thermal expansion of the optical element31and the actuator32,35,39.x,43,50are determined.

In a third method step63, the parasitic aberrations are determined on the basis of the parasitic deformations while taking into account the summing effect of a scanning exposure used in the projection exposure apparatus.

In a fourth method step64, the actuator is optimized on the basis of the determined parasitic aberrations. In this case, in particular the shape and arrangement of the individual actuator pads and of the holes can be varied.

In a fifth method step65, at least some of the preceding process steps are repeated until the value for the parasitic aberration falls under a predetermined value.

LIST OF REFERENCE SIGNS