DE102021203123A1 - Computer-generated hologram (CGH) and interferometric measurement setup to determine the surface shape of a test object - Google Patents

Abstract

The invention relates to a computer-generated hologram (CGH) and an interferometric measuring arrangement for determining the surface shape of a test piece. The test object can in particular be an optical element of a microlithographic projection exposure system. A computer-generated hologram (CGH) according to the invention, in particular for use in an interferometric measuring arrangement for determining the surface shape of a test object, has a plurality of functional surface elements, each of which has a complex coding for generating different output waves, each of these functional surface elements being assigned one of the number of corresponding coding depth is assigned to the output waves generated in each case, the coding depth being a maximum of four, and the functional surface elements differing from one another with regard to the output waves generated in each case.

Description

BACKGROUND OF THE INVENTION

field of invention

The invention relates to a computer-generated hologram (CGH) and an interferometric measuring arrangement for determining the surface shape of a test piece. The test object can in particular be an optical element of a microlithographic projection exposure system.

State of the art

Microlithography is used to produce microstructured components such as integrated circuits or LCDs. The microlithographic process is carried out in a so-called projection exposure system, which has an illumination device and a projection lens. The image of a mask (= reticle) illuminated by means of the illumination device is projected by means of the projection objective onto a substrate (e.g. a silicon wafer) coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection objective in order to project the mask structure onto the light-sensitive coating of the to transfer substrate.

In projection lenses designed for the EUV range, ie at wavelengths of, for example, around 13 nm or around 7 nm, mirrors are used as optical components for the imaging process due to the lack of availability of suitable light-transmitting refractive materials. Typical projection lenses designed for EUV, such as from US 2016/0085061 A1 known, can have, for example, an image-side numerical aperture (NA) in the range of NA=0.55 and form an object field (eg in the form of a ring segment) in the image plane or wafer plane. Increasing the image-side numerical aperture (NA) is typically accompanied by an increase in the required mirror surfaces of the mirrors used in the projection exposure system. This in turn means that, in addition to manufacturing, testing the surface shape of the mirrors also represents a demanding challenge.

In particular, interferometric measuring methods using computer-generated holograms (CGH) are used for the high-precision inspection of the mirrors. The determination of the surface shape of the respective mirror or test piece is based on an interferometric superimposition of a test wave generated by the CGH with a wavefront adapted to the target shape of the surface of the test piece and a reference wave.

It is also known to carry out a calibration to take into account wavefront errors caused by the measuring arrangement or the CGH. Known approaches to this include, for example, the use of additional calibration mirrors in combination with the generation of corresponding, additional calibration waves by the CGH. For this purpose, the CGH can have a complex coding in the form of superimposed diffractive structure patterns for generating the test wave, the reference wave and the calibration waves.

Furthermore, it is known in the prior art to carry out an interferometric measurement in a plurality of different rotational positions or rotary displacement positions of the respective test object in order to increase the accuracy in the interferometric measurement of non-rotationally symmetrical surfaces.

Although the approaches mentioned above can also be used in principle for the measurement of free-form surfaces, in practice the fulfillment of increasing accuracy requirements, especially taking into account spatially high-frequency registration errors (with spatial wavelengths less than 30mm, in particular less than 10mm), represents an increasingly demanding challenge. Another, in A manufacturing problem that occurs in practice is that the high coding depth (typically five-fold coding) of a computer-generated hologram requires long writing times. In addition, with a high coding depth of the CGH, the solution of the Maxwell equations required to take into account rigorous effects (i.e. the effect of the three-dimensional structure of the CGH on its diffraction effect) proves to be correspondingly difficult and complex.

The prior art is only given as an example DE 10 2015 209 490 , U.S. 7,602,502 B2 and DE 100 58 650 A1 referred.

SUMMARY OF THE INVENTION

Against the above background, it is an object of the present invention to provide a computer-generated hologram (CGH) and an interferometric measuring arrangement for determining the surface shape of a test specimen, which allow free-form surfaces to be measured with increased accuracy, in particular with regard to considering spatially high-frequency registration errors .

This object is achieved by the computer-generated hologram (CGH) according to the features of independent patent claim 1 and the interferometric measuring arrangement according to the features of independent patent claim 9 .

• - einer Mehrzahl von Funktionsflächenelementen, welche jeweils zur Erzeugung unterschiedlicher Ausgangswellen eine komplexe Kodierung aufweisen, wobei jedem dieser Funktionsflächenelemente eine der Anzahl an jeweils erzeugten Ausgangswellen entsprechende Kodierungstiefe zugeordnet ist;
• - wobei die Kodierungstiefe maximal vier beträgt; und
• - wobei sich die Funktionsflächenelemente hinsichtlich der jeweils erzeugten Ausgangswellen voneinander unterscheiden.

A computer-generated hologram (CGH), in particular for use in an interferometric measuring arrangement to determine the surface shape of a test object, has:

• - a plurality of functional surface elements, each of which has a complex coding for generating different output waves, each of these functional surface elements being assigned a coding depth corresponding to the number of output waves generated in each case;
• - where the coding depth is a maximum of four; and
• - Wherein the functional surface elements differ in terms of the output waves generated in each case.

The invention is based in particular on the concept of designing a CGH intended for use in an interferometric measuring arrangement with a reduced coding depth and for this purpose dividing the CGH into a plurality of partial areas forming functional surface elements (“patches”), with these functional surface elements or Sub-areas differ from each other in terms of the output waves generated by their complex coding.

As a result of the configuration according to the invention, the CGH configured in this way is overall suitable for providing the functionalities required in the approaches described above, while at the same time the reduction in the coding depth is accompanied by significant advantages not only in terms of production technology (due to reduced writing times), but also higher accuracy the measurement of spatially high-frequency registration errors (as a result of reducing the number and effects of disruptive diffraction orders).

According to one embodiment, the coding depth is a maximum of three, in particular two.

According to one embodiment, the functional surface elements are arranged in such a way that an interference beam, which is generated from a beam incident on the CGH by a superlattice formed by the functional surface elements in the (+1)th diffraction order, is reflected on the test specimen and on its way back on the CGH from superlattice is diffracted in the (-1)-th diffraction order, is not parallel to the incident beam.

According to this embodiment, the invention is based on the further consideration that the above-described embodiment of the CGH with a plurality of functional surface elements or subregions leads to the formation of a superlattice, which without suitable countermeasures—as described in more detail below—results in corresponding error contributions. Thus, an interference beam generated by diffraction at said superlattice in the (+1)th order of diffraction can again be directed parallel to the beam incident on the CGH after reflection on the test object and return to the CGH by diffraction at the CGH in the (-1)th order of diffraction and thus finally also get to the interferometer camera, where the interference beam then supplies a corresponding error contribution.

According to the invention, this circumstance can be taken into account in that a course of the interference beam parallel to the beam incident on the CGH is prevented by a suitable spatial arrangement of the functional surface elements or partial areas according to the invention. In embodiments of the invention, this is achieved in that the superlattice structure of the superlattice formed by the functional surface elements is twisted at the point of passage of this interference beam at the CGH on its way back from the test object relative to the superlattice structure that is present at the point of passage of the interference beam at the CGH on its way to the test object . This rotation can in particular take place by an angle of rotation of at least 30° in terms of amount, in particular of at least 45° in terms of amount, more particularly of 90° in terms of amount.

According to one embodiment, to achieve the effect described above, the functional surface elements arranged one after the other in the radial direction outwards on the CGH are twisted relative to one another.

According to another embodiment, the effect described above is achieved in that the surface coverage density of the functional surface elements varies outwards in the radial direction.

According to one embodiment, the CGH has CGH structures located on a CGH substrate, these CGH structures each having at least one flank running at a flank angle to the CGH substrate that differs from 90°. This can result in rigorous effects at the level of the CGH structure ender forward and backward scattering can be avoided.

The invention also relates to an interferometric measuring arrangement for determining the surface shape of a test object, in particular an optical element of a microlithographic projection exposure system, the measuring arrangement having a computer-generated hologram (CGH) and the surface shape of at least one partial area of the test object being determined by interferometric superimposition of a can be carried out by means of a test wave guided onto the test object by this CGH and a reference wave, the CGH being designed with the features described above.

According to one embodiment, each of the functional surface elements generates a reference wave.

According to one embodiment, each of the functional surface elements generates either a test wave or a calibration wave in addition to the reference wave. In particular, the CGH can also be designed to generate a plurality of calibration waves, which are directed onto different calibration surfaces. Different calibration waves can be generated by different functional surface elements.

According to one embodiment, the interferometric measuring arrangement has an illumination beam path leading from a light source used to generate electromagnetic radiation to the CGH, with a unit for varying the angle of incidence of the electromagnetic radiation upon incidence on the CGH being arranged in this illumination beam path. This unit can in particular have at least one tiltable mirror.

According to one embodiment, this variation of the angle of incidence allows a changeover between a test beam path, in which a test wave is directed by the CGH onto the test object, and a calibration beam path, in which a calibration wave is directed by the CGH onto a calibration surface.

• - Durchführen wenigstens einer Interferogramm-Messreihe an dem Prüfling durch Überlagerung jeweils einer durch Beugung elektromagnetischer Strahlung an einem Computer-generierten Hologramm (CGH) erzeugten und an dem Prüfling reflektierten Prüfwelle mit einer nicht an dem Prüfling reflektierten Referenzwelle; und
• - Bestimmen der Oberflächenform des Prüflings basierend auf der durchgeführten Interferogramm-Messreihe;

wobei das Verfahren unter Verwendung eines CGH mit den vorstehend beschriebenen Merkmalen oder unter Verwendung einer interferometrischen Messanordnung mit den vorstehend beschriebenen Merkmalen durchgeführt wird.The invention also relates to a method for determining the surface shape of a test object, in particular an optical element of a microlithographic projection exposure system, the method having the following steps:

• - Carrying out at least one interferogram measurement series on the test object by superimposing in each case a test wave generated by diffraction of electromagnetic radiation on a computer-generated hologram (CGH) and reflected on the test object with a reference wave not reflected on the test object; and
• - Determination of the surface shape of the specimen based on the interferogram measurement series carried out;

wherein the method is carried out using a CGH with the features described above or using an interferometric measuring arrangement with the features described above.

According to one embodiment, a plurality of such interferogram measurement series are carried out, which differ from one another with regard to a rotational position or rotational/sliding position of the test object.

Further configurations of the invention can be found in the description and in the dependent claims.

The invention is explained in more detail below with reference to exemplary embodiments illustrated in the attached figures.

character list

• 1 eine schematische Darstellung eines möglichen Aufbaus einer interferometrischen Messanordnung;
• 2a-2c schematische Darstellungen zur Erläuterung von Aufbau und Funktionsweise eines CGH in einer beispielhaften Ausführungsform der Erfindung;
• 3a-3b schematische Darstellungen zur Erläuterung von Aufbau und Funktionsweise eines CGH in einer weiteren Ausführungsform der Erfindung;
• 4-7 schematische Darstellungen zur Erläuterung weiterer Ausführungsformen eines erfindungsgemäßen CGH;
• 8a-8c schematische Darstellungen zur Erläuterung einer möglichen weiteren Anwendung eines erfindungsgemäßen CGH; und
• 9 eine schematische Darstellung einer für den Betrieb im EUV ausgelegten Projektionsbelichtungsanlage.

Show it:

• 1 a schematic representation of a possible structure of an interferometric measuring arrangement;
• 2a-2c schematic representations to explain the structure and functioning of a CGH in an exemplary embodiment of the invention;
• 3a-3b schematic representations to explain the structure and mode of operation of a CGH in a further embodiment of the invention;
• 4-7 schematic representations for explaining further embodiments of a CGH according to the invention;
• 8a-8c schematic representations to explain a possible further application of a CGH according to the invention; and
• 9 a schematic representation of a projection exposure system designed for operation in the EUV.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

9 first shows a schematic representation of an exemplary projection exposure system designed for operation in the EUV, which has mirrors that can be checked with a method according to the invention.

According to 9 an illumination device in a projection exposure system 910 designed for EUV has a field facet mirror 903 and a pupil facet mirror 904 . The light from a light source unit, which comprises a plasma light source 901 and a collector mirror 902, is directed onto the field facet mirror 903. A first telescope mirror 905 and a second telescope mirror 906 are arranged in the light path after the pupil facet mirror 904 . A deflection mirror 907 is arranged downstream in the light path, which deflects the radiation striking it onto an object field in the object plane of a projection objective comprising six mirrors 921-926. At the location of the object field, a reflective structure-bearing mask 931 is arranged on a mask table 930, which is imaged with the aid of the projection lens in an image plane in which a substrate 941 coated with a light-sensitive layer (photoresist) is located on a wafer table 940.

1 shows first a schematic representation to explain the possible structure of an interferometric measuring arrangement, in which a CGH according to the invention for the purpose of determining the surface shape of a test piece (in particular an optical element for a microlithographic projection exposure system, e.g. one of the mirrors of the projection exposure system 910 from 9 ) can be used.

According to 1 An input wave labeled “105”, which is generated by a light source (not shown) and is supplied via an optical waveguide, runs via a beam splitter 110 to a CGH 120. The measuring arrangement according to FIG 1 has a tiltable mirror 103 for varying the angle of incidence of the electromagnetic radiation upon incidence on the CGH 120, which will be discussed in more detail below.

The CGH 120 generates in transmission by diffraction at one of the diffractive structure patterns present on the CGH 120 from the input wave 105 a test wave 125 directed onto the surface 141 of the test object 140 with a wave front adapted to the desired shape of the surface 141 .

In this transformation, the wavefront is adapted in such a way that the test wave strikes perpendicularly at each location on the surface 141 in the desired form and is reflected back into itself.

Furthermore, the CGH 120 generates in transmission by diffraction at another of its diffractive structure patterns from the input wave a reference wave 126 directed onto a further reflective element in the form of a reference mirror 131, which is reflected back into itself by this reference mirror 131. Both the test wave 125 reflected on the test object 140 and the reference wave 126 reflected on the reference mirror 131 return to the CGH 120, where they are diffracted in turn and run back to the beam splitter 110, from which they are reflected, so that they are reflected via an eyepiece 150 onto a Meet interferometer camera 160 and overlay each other there to generate an interferogram. The actual shape of the surface 141 of the test object 140 is determined from the interferogram recorded in this way via an evaluation device (not shown).

In this determination of the surface shape, the evaluation device particularly takes into account the result of a calibration. A possible implementation of such a calibration includes the use of additional calibration mirrors in combination with the generation of corresponding, additional calibration waves by the CGH 120. With regard to such a calibration, which is known per se, is shown by way of example DE 10 2015 209 490 A1 and referenced the exemplary embodiments described there.

In order to generate the test wave, the reference wave and the calibration waves, the CGH 120 according to the invention has a complex coding in the form of superimposed diffractive structure patterns. What is common to the embodiments described below for such a complex-coded CGH 120 is that the CGH is subdivided into a plurality of sub-areas in the form of functional area elements, whose respective coding depth (which corresponds to the number of output waves generated by the relevant sub-area or the respective functional area element corresponds) is limited to a maximum of four (in particular a maximum of three, more particularly two). In order to nevertheless generate the required output waves (i.e. test wave, reference wave and calibration waves) by the CGH overall, according to the invention the individual sub-areas or functional surface elements differ from one another with regard to the output waves generated in each case. For example, one of the functional surface elements can generate the test wave in addition to the reference wave, another functional surface element can generate the calibration wave corresponding to a first calibration mirror in addition to the reference wave, another functional surface element can generate the calibration wave corresponding to a second calibration mirror in addition to the reference wave, etc. Proper generation of the interferogram requires that each of the functional surface elements generates a reference wave.

In the following, a first possible embodiment of a CGH according to the invention is first described with reference to the schematic representation of FIG 2a described. In 2a Camera pixel images, in this case only imaginary camera pixel images, of the interferometer camera 160 are marked with “121”. Within these camera pixel images 121, one of which in 2a shown enlarged on the bottom right, the above-described functional surface elements K1, K2, . . . are again located. In this context it should be noted that the measurement arrangement according to 1 for varying the angle of incidence of the electromagnetic radiation upon incidence on the CGH 120 has a tiltable mirror 103, via which a changeover between a test beam path, in which a test wave is directed from the CGH 120 to the test object 140, and a calibration beam path, in which the CGH 120 directing a calibration wave onto a calibration surface or a calibration mirror can be carried out.

The CGH 120 according to 2a has such a complex coding that for a first tilting angle setting of the tiltable mirror 103 in the area labeled "A" outside of the functional surface elements, the reference wave (directed to the reference mirror 131) as well as the test wave directed to the test object 140 are generated (cf. 2 B) . On the other hand, within the functional surface elements (ie, e.g. the area marked “B”), the reference wave is generated when a second tilting angle of the tiltable mirror 103 is set, whereby in this case, in addition to the reference wave, at least one calibration wave directed onto a calibration mirror is generated instead of the test wave (cf. 2c , in which the calibration mirror is labeled “170”). With "180" is in 2 B and 2c the interferometer is indicated in each case.

3a-3b show schematic representations to explain a further embodiment of a CGH according to the invention. In this embodiment, the fact is taken into account that the functional surface elements or partial areas provided according to the invention on the CGH form a superlattice which, without appropriate countermeasures, leads to a Interference beam after reflection on the test object, return to the CGH and diffraction in the (-1)th diffraction order again runs parallel to the beam incident on the CGH and finally reaches the interferometer camera. To avoid such spurious beams and corresponding error contributions, the CGH in the embodiment of 3a-3b and also according to the further embodiments 4 and 5 designed in such a way that said superlattice for the interference beam described above is twisted on its return path from the test specimen relative to the superlattice structure, which the interference beam at the CGH “sees” on its way to the test specimen.

The effect achieved in this way is 3a illustrated where 3b shows an enlarged section. (Imaginary) images of camera pixels of the interferometer camera 160 on the CGH 120 are shown with “321” and “322”. Out of 3a it can be seen how the above-described diffraction of the useful light beam labeled "101" at the superlattice on the CGH 120 in the (+1)th diffraction order leads to the generation of an interference beam 102 that is bent away to the side, which is also reflected at the test specimen 140 (but with a non-perpendicular incidence) is reflected. When this interfering beam 102 reflected on the specimen 140 returns to the CGH 120, the diffraction in the (-1)th diffraction order at the superlattice results as a result of the above-described and from the enlarged representation of FIG 3b visible twisting of the superlattice structure means that said interfering beam 102 is not again directed parallel to the incident beam or useful light beam 101 to the interferometer camera 160, but rather is deflected to the side and consequently can no longer make an error contribution.

The twisting described above can be realized in different ways in order to enable interference beams generated by diffraction at the superlattice to be masked out. So can according to 4 Said twisting can be achieved in that functional surface elements arranged one after the other on the CGH 420 are twisted relative to one another in the radial direction outwards. 5 shows a further possible implementation, in which instead the surface coverage density of the functional surface elements is varied outwards in the radial direction (increased in the specific exemplary embodiment).

6a-6b show schematic representations to explain possible embodiments of a CGH according to the invention with regard to the formation of the diffractive structures present on the respective CGH substrate. In particular, according to 6b in the case of a CGH 625, the flank angles of said diffractive structures 627 may be formed obliquely (ie at an angle deviating from 90° relative to the CGH substrate 626). This configuration is compared to that in 6a Schematically illustrated embodiment with perpendicular formation of the CGH structures 622 to the CGH substrate 621 advantageous insofar as rigorous effects caused by forward and reverse scattering in the plane of the respective CGH structure can be avoided.

7 shows a schematic representation to explain the possible structure of a CGH according to the invention in a further embodiment. According to 7 are shown with "721" (imaginary) images of camera pixels of the interferometer camera on the CGH 720. “721e” designates a diffractive structure provided uniformly and extensively over the CGH 720 for generating the reference wave. In the lower part of 7 one of the images of camera pixels 721 is shown enlarged. In this camera pixel image there are functional surface elements 721a-721d (corresponding to the four quadrants of the camera pixel image) that are complex coded in different ways, of which three functional surface elements 721a, 721b and 721c each generate another output wave in the form of a test wave in addition to the reference wave, i.e each have a coding depth of two. The test waves generated by the functional surface elements 721a-721c differ from one another insofar as they correspond to different rotational positions or rotational/sliding positions of the test object. For this purpose, the test specimen can be adjusted in different rotational positions or different rotational/sliding positions within the corresponding interferometric measurement arrangement, which means that U.S. 7,602,502 B2 , DE 100 58 650 A1 and the publication R. Freimann et al.: "Absolute measurement of non-comatic aspheric surface errors", Optics Communication, 161, 106-114, 1999 known rotational averaging method can be implemented.

8a and 8b show a schematic representation of correspondingly different rotational/sliding positions of the test specimen in the interferometric measurement arrangement, according to which different phase functions of a CGH 820 become effective. The specimen is preferably rotated about a vertical axis in order to avoid deformation. In further embodiments, a test specimen displacement or a combination of rotation and displacement can also take place. Furthermore, the arrangement or testing of the test piece in the actual position of use is preferably carried out in a rotating/sliding position. With "880" is in 8a the interferometer indicated.

Referring again to 7 In the exemplary embodiment of the CGH 720, the functional surface element 721d (which is located in the fourth quadrant of the enlarged camera pixel image) is designed in such a way that in addition to the reference wave, at least one calibration wave, in particular up to three calibration waves, is generated as an output wave. 8c shows, again in a schematic representation, the associated scenario in the operation of the interferometric measuring arrangement, in which the corresponding calibration wave emanating from the CGH 820 is directed onto a calibration surface labeled “870”. Depending on the design of the CGH or the calibration wave generated, the calibration surface can be designed to be planar, spherical, astigmatic or toroidal.

Although the invention has also been described on the basis of specific embodiments, numerous variations and alternative embodiments will become apparent to the person skilled in the art, e.g. by combining and/or exchanging features of individual embodiments. Accordingly, it will be understood by those skilled in the art that such variations and alternative embodiments are intended to be encompassed by the present invention and the scope of the invention is limited only in terms of the appended claims and their equivalents.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited 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.

Patent Literature Cited

• US 2016/0085061 A1 [0003]
• DE 102015209490 [0008]
• US 7602502 B2 [0008, 0046]
• DE 10058650 A1 [0008, 0046]
• DE 102015209490 A1 [0038]

Claims (18)

Computer-generated hologram (CGH), in particular for use in an interferometric measuring arrangement for determining the surface shape of a test object, with: • a plurality of functional surface elements (K1, K2, K3, ...), which each have a complex coding for generating different output waves, each of these functional surface elements (K1, K2, K3, ...) one of the number of output waves generated corresponding coding depth is assigned; • where the coding depth is a maximum of four; and • where the functional surface elements (K1, K2, K3, ...) differ from one another with regard to the output waves generated in each case. Computer generated hologram (CGH) after claim 1 , characterized in that the coding depth is a maximum of three, in particular two. Computer generated hologram (CGH) after claim 1 or 2 , characterized in that the functional surface elements (K1, K2, K3, ...) are arranged in such a way that an interference beam (102), which consists of a beam (101) incident on the CGH (120) from a beam passing through the functional surface elements (K1 , K2, K3, ...) formed superlattice is generated in the (+1)th order of diffraction, reflected at the test piece (140) and diffracted on its way back at the CGH (120) from the superlattice in the (-1)th order of diffraction is not parallel to the incident beam (101). Computer generated hologram (CGH) after claim 3 , characterized in that the superlattice structure of the superlattice formed by the functional surface elements (K1, K2, K3, ...) at the point of passage of this interference beam (102) at the CGH (120) on its way back from the test object (140), relative to the superlattice structure at Point of passage of the interference beam (102) on the CGH (120) on its way to the test object (140) is twisted. Computer generated hologram (CGH) after claim 4 , characterized in that this twisting takes place by a twisting angle of at least 30° in terms of amount, in particular of at least 45° in terms of amount, more particularly of 90° in terms of amount. Computer-generated hologram (CGH) according to one of the Claims 1 until 5 , characterized in that functional surface elements (K1, K2, K3, ...) on the CGH (420) arranged one after the other in the radial direction outwards are twisted relative to one another. Computer-generated hologram (CGH) according to one of the Claims 1 until 5 , characterized in that the functional surface elements (K1, K2, K3, ...) are arranged on the CGH (520) with a surface coverage density which varies outwards in the radial direction. Computer-generated hologram (CGH) according to one of the preceding claims, characterized in that the CGH (625) on a CGH substrate (626) located CGH structures (627), wherein these CGH structures (627) each have at least one have a flank running at a flank angle different from 90° to the CGH substrate (626). Interferometric measuring arrangement for determining the surface shape of a test specimen, in particular an optical element of a microlithographic projection exposure system, the measuring arrangement having a computer-generated hologram (CGH) and the surface shape of at least one partial area of the test specimen (140) being determined by interferometric superimposition of one of this CGH (120, 420, 520) directed onto the test object (140) and a reference wave can be carried out, characterized in that the CGH is designed according to one of the preceding claims. Interferometric measurement setup claim 9 , characterized in that each of the functional surface elements (K1, K2, K3, ...) generates a reference wave. Interferometric measurement setup claim 10 , characterized in that each of the functional surface elements (K1, K2, K3, ...) generates either a test wave or a calibration wave in addition to the reference wave. Interferometric measurement arrangement according to one of claims 9 until 11 , characterized in that the CGH (120, 420, 520) is designed to generate a plurality of calibration waves which are directed onto different calibration surfaces. Interferometric measurement setup claim 12 , characterized in that different calibration waves are generated by different functional surface elements (K1, K2, K3, ...). Interferometric measurement arrangement according to one of claims 9 until 13 , characterized in that it has an illumination beam path leading from a light source used to generate electromagnetic radiation to the CGH, in which illumination beam lengang is arranged a unit for varying the angle of incidence of the electromagnetic radiation when it falls on the CGH. Interferometric measurement setup Claim 14 , characterized in that this unit has at least one tiltable mirror (103). Interferometric measurement setup Claim 14 or 15 , characterized in that this variation of the angle of incidence causes a changeover between a test beam path, in which a test wave is directed from the CGH (120, 420, 520) onto the test object (140), and a calibration beam path, in which the CGH (120 , 420, 520) a calibration wave is guided onto a calibration surface (170), can be carried out. Method for determining the surface shape of a test object, in particular an optical element of a microlithographic projection exposure system, the method having the following steps: a) carrying out at least one interferogram measurement series on the test object (140) by superimposing one each by diffraction of electromagnetic radiation on a computer-generated Hologram (CGH) generated and on the test piece (140) reflected test wave with a not on the test piece (140) reflected reference wave; and b) determining the surface shape of the test object (140) based on the interferogram measurement series that has been carried out; characterized in that the method using a CGH (120, 420, 520, 820) according to any one of Claims 1 until 8th or using an interferometric measuring arrangement according to one of claims 9 until 16 is carried out. procedure after Claim 17 , characterized in that a plurality of such interferogram measurement series is carried out, which differ from one another with regard to a rotational position or rotational/sliding position of the test object (840).

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