Apparatus and method for checking a component, and lithography system

Abstract

Apparatus and method for checking a component, and lithography system The invention relates to an apparatus (1) for checking a component (2) with a periodic structure (3) having substructures (5) arranged on a lattice (4), at least comprising a measurement radiation source (6) for creating measurement radiation (7) and an optics system (8). The apparatus (1) comprises a mask device (10) for influencing a phase angle of the measurement radiation (7), the mask device (10) having a dual lattice (11) which is reciprocal to a target shape of the lattice (4), wherein the component (2), the measurement radiation source (6), the optics system (8) and the mask device (10) are arrangeable in such a way that the measurement radiation (7) is diffracted at the lattice (4) in such a way that at least one of the 0th diffraction orders of the diffracted measurement radiation (7) is at least approximately coinciding with at least one of the points of the dual lattice (11).

Description

[0001] Apparatus and method for checking a component, and lithography system

[0002] German Patent Application No. DE 102023203731.9 filed April 24, 2023 is incorporated in this application by reference in their entirety to form a part of the present disclosure.

[0003] The invention relates to an apparatus for checking a component with a periodic structure having substructures arranged on a lattice, at least comprising a measurement radiation source for creating measurement radiation and an optics system.

[0004] The invention also relates to a method for checking a component with a periodic structure having substructures arranged on a lattice, with use being made of at least one measurement radiation source for creating measurement radiation and an optics system.

[0005] Moreover, the invention relates to a lithography system, in particular a projection exposure apparatus for producing a semiconductor component, having an illumination system with a radiation source and an optical unit which comprises at least one optical element.

[0006] The prior art has disclosed the formation of semiconductor components by etching and / or coating.

[0007] The prior art has also disclosed the formation of NAND memory chips in 3-D construction by etching and / or coating periodically arranged through openings or vias. In this context, the vias are freguently realized in deep double layer stacks, in particular multiple double layer stacks, or so-called bilayer stacks.

[0008] Typically, such semiconductor components reguire a check for defects or a measurement and / or gualification.

[0009] The prior art has disclosed non-destructive and destructive methods for checking the semiconductor components.

[0010] As non-destructive methods, tomographic methods or ptychographic methods or coherent diffraction imaging methods (CDI methods) using x-ray light are known from the prior art.

[0011] However, disadvantages of the non-destructive methods known from the prior art are their complicated implementation and the low throughput obtainable therewith and slow realizable inspection speeds.

[0012] For example, the destructive methods known from the prior art comprise scanning electron microscopy using focused ion beams (FIB-SEM). The present invention is based on the object of developing an apparatus for checking a component, which avoids the disadvantages of the prior art, in particular enables an efficient and reliable check of periodic structures.

[0013] According to the invention, this object is achieved by an apparatus having the features specified in Claim 1.

[0014] The present invention is based on the object of developing an apparatus for checking a component, which avoids the disadvantages of the prior art, in particular enables an efficient and reliable check of periodic structures.

[0015] According to the invention, this object is achieved by a method having the features specified in Claim 30.

[0016] The present invention is based on the object of developing a lithography system, which avoids the disadvantages of the prior art, in particular enables production of efficiently and reliably checked semiconductor components.

[0017] According to the invention, this object is achieved by a lithography system having the features specified in Claim 44.

[0018] The apparatus according to the invention serves for checking a component with a periodic structure having substructures arranged on a lattice, and comprises at least one measurement radiation source for creating measurement radiation and at least one optics system. According to the invention, the apparatus comprises a mask device for influencing a field distribution of the measurement radiation, the mask device having a dual lattice which is reciprocal to a target shape of the lattice, wherein the component, the measurement radiation source, the optics system and the mask device are configured and arrangeable in such a way that the measurement radiation is diffracted at the lattice in such a way that at least one of the Oth diffraction orders of the diffracted measurement radiation is at least approximately coinciding with at least one of the points of the dual lattice.

[0019] Provision can be made for the component, the measurement radiation source, the optics system, and the mask device to be configured and arrangeable in such a way that the measurement radiation is diffracted at the lattice in such a way that at least approximately all of the Oth diffraction orders of the diffracted measurement radiation are at least approximately coinciding with at least approximately all of the points of the dual lattice.

[0020] Provision can be made for the component, the measurement radiation source, the optics system, and the mask device to be configured and arrangeable in such a way that the measurement radiation is diffractable at the target shape of the lattice in such a way that at least approximately all of the Oth diffraction orders of the diffracted measurement radiation are at least approximately coinciding with at least approximately all of the points of the dual lattice.

[0021] Additionally, or alternatively, the component, the measurement radiation source, the optics system, and the mask device are configured and / or arrangeable in such a way that the lattice, the measurement radiation, and the dual lattice at least approximately mutually fulfil a Laue condition for the target shape of the lattice.

[0022] The apparatus according to the invention allows checking of the component with a high throughput or a high inspection speed and can be used within a production line in particular.

[0023] The apparatus according to the invention has a superior accuracy in comparison with inspection methods known from the prior art, which are based on the comparison of conventional intensity images. As a result, the apparatus according to the invention is suitable for a fast and sufficiently accurate inspection of the component within a production line or for an in-line inspection.

[0024] The apparatus according to the invention enables a direct interferometric comparison between a position of a respective individual substructure and its target position. In contrast to a comparison with intensity images captured by means of a conventional microscopy objective, this enables a direct and simultaneous detection of amplitude deviations and phase deviations.

[0025] By preference, the apparatus according to the invention can be configured to overlay a diffraction image of the lattice and of the corresponding dual or reciprocal dual lattice, which are preferably virtually punctiform lattices.

[0026] Provision can be made for the dual lattice to be arranged such that the diffraction image of the lattice and the dual lattice are overlaid in an imaging pupil. Further, provision can be made for the zeroth order of diffraction of the dual lattice to have a similar efficiency as the complementary orders contributing to the image overall.

[0027] Provision can be made for the light source to be configured for a Kohler-type illumination of the component.

[0028] It may be provided that the apparatus according to the invention is configured for operation in reflection.

[0029] Since the dual lattice and the lattice can be arranged relative to each other in such a way that the Laue condition is fulfilled at least for the target shape, i.e. the nominal shape, of the lattice, a measurement can be carried out without artifacts in a resulting interferogram.

[0030] In the context of the invention, the Laue condition is preferably understood to mean that a diffraction vector, which is defined by the difference between a wave vector of measurement radiation incident on the lattice and a wave vector of measurement radiation diffracted away from the lattice, is a dual lattice vector of the dual lattice. In other words, the Laue condition ensures that the measurement radiation hits the dual grating in the correct orientation after diffraction at the target shape of the lattice.

[0031] In an advantageous development of the apparatus according to the invention, provision can be made for the measurement radiation source to be configured to create the measurement radiation in such a way that a diffraction pattern of the target shape of the lattice is at least approximately fully alignable with the dual lattice.

[0032] In particular, the measurement radiation source is preferably configured to create the measurement radiation in such a way that a diffraction pattern of the target shape of the lattice is at least approximately fully coinciding with the dual lattice.

[0033] It is particularly advantageous if the components of the device according to the invention, and in particular the measurement radiation source, are set up and can be arranged in such a way that the diffraction image of the target shape off the lattice, i.e. the nominal shape of the grating, can be completely aligned with the dual lattice.

[0034] In an advantageous development of the apparatus according to the invention, provision can be made for the measurement radiation source to be configured to create the measurement radiation in such a way that the measurement radiation at an entry pupil of the optics system has a pattern at least partially corresponding to the dual lattice.

[0035] The pattern of the measurement radiation can be understood as an intensity pattern and / or a phase pattern and / or a pattern of beam directions.

[0036] It may be provided that the lattice and / or the mask device are aligned perpendicular to an optical axis of the optical system.

[0037] In this case in particular, it is advantageous if the device or the optical system are configured in such a way that an illumination pupil formed by the measurement radiation is designed in such a way that its support is at least partially aligned with the dual lattice, the dual lattice being reciprocal to the lattice.

[0038] A beam mask device can be provided which is set up to generate the illumination directions of the measurement radiation in such a way that the measurement radiation is diffracted at the lattice in such a way that at least one of the 0thdiffraction orders of the diffracted measurement radiation is at least approximately coinciding with at least one of the points of the dual lattice.

[0039] In particular, the beam mask device can be part of the measurement radiation source and / or the optics system. A beam mask device can be provided which is set up to generate the illumination directions permissible for fulfilling the Laue condition by diffraction of a plane wave at a grating with grating vectors G*.

[0040] It may be provided that the measurement radiation is directed towards the beam mask device with grating vectors G*.

[0041] For plane-wave illuminations from various directions, which have pupil coordinates k, an interferogram is measured according to formula (11) with coordinates x at the site of recording of the interferogram. The lattice of the periodic structure is given by G.

[0042] Z(x) := |ob / fc(x) objk(x + £)| with objk(xj := obj (x) exp(ifcx) (11)

[0043]

[0044] The expression exp(ifcx) describes a tilted incident wave. The interferogram according to formula (11) thus detects in particular a non-periodicity of the tilted incident wave.

[0045] For an illumination pupil, i.e. an illumination pattern at the location of the entrance pupil into the optical system, which corresponds at least in sections and / or at least partially to the dual grating, the interferogram is obtained according to formula (12).

[0046] I (x) := | obj (x) - Zgec obj (x + gj | (12)

[0047]

[0048] In contrast to formula (11), the lattice G according to formula (12) describes a set of frequency vectors of the ideal periodic structure, i.e. the lattice. This results in formula (13).

[0049] objidea(x + gj = objideal(x) Vg E G (13)

[0050] Formula (12) is discussed in more detail in the context with formula (4) later.

[0051] It is particularly advantageous if the measurement radiation source comprises a laser. Furthermore, the measurement radiation source can also have at least one aperture device for producing the desired pattern at the entrance pupil.

[0052] Thus, the illumination pupil preferably comprises at least approximately only frequencies in the vicinity of the dual lattice.

[0053] The condition described above can be realized in particular by a plane wave of a laser source incident perpendicular to the component or periodic structure and thus the lattice, in particular if both the lattice and the mask device and the dual lattice are perpendicular to an optical axis In an advantageous development of the apparatus according to the invention, provision can be made for the apparatus to comprise a camera device.

[0054] By means of the camera device and / or a detector device, for example a sensor, an interferogram from the measured radiation can be analyzed in a particularly advantageous and reproducible manner.

[0055] In an advantageous development of the apparatus according to the invention, provision can be made for the apparatus to comprise a mixing device.

[0056] It may be provided that the mixing device is set up to make plane waves of the measurement radiation incoherent with respect to one another.

[0057] In particular, it may be provided that the mixing device is set up to make the plane waves of the measurement radiation belonging to the dual lattice, which originate from the aforementioned entrance pupil or illumination pupil, incoherent with respect to one another.

[0058] By means of the mixing device, the device according to the invention thus makes it possible to provide different illumination systems with an illumination pupil, so that the illumination pupil firstly only has frequencies close to the dual lattice and secondly the plane waves of the measurement radiation belonging to the dual lattice are incoherent to one another, so that speckle effects in the image can be suppressed.

[0059] In an advantageous development of the apparatus according to the invention, provision can be made for the mixing device to comprise a plurality of optical fibers, the plurality of optical fibers having different lengths.

[0060] It may be provided that the mixing device is designed as part of the measurement radiation source by having laser sources that are temporally incoherent to each other.

[0061] These can have one or more separate pump light sources.

[0062] In particular, it may be provided that a plurality of fiber lasers with a single pump source are present, with the fibers of the fiber lasers preferably having different lengths.

[0063] In particular, it may be provided that in pairs a length difference is greater than a coherence length L of the measurement radiation, which may in particular be in the form of laser light.

[0064] Formula (14) describes the coherence length L, which is given by a spectral width AX of the measurement radiation with center wavelength A, in particular of the laser light, and a refractive index n of the fiber. In an advantageous development of the apparatus according to the invention, provision can be made for the mixing device to comprise a diffuser element.

[0065] It may be possible to disturb the coherence of the measurement radiation by means of the diffuser element.

[0066] In particular, it may be provided that the diffuser element is set up for time averaging.

[0067] Preferably, it may be provided that the diffuser element is designed as a stochastically phase-shifting element.

[0068] In one embodiment of the device, it may be provided that the diffuser element is designed to form a turbulent flow of a medium in a beam path of the measurement radiation. The medium can be gaseous and / or liquid.

[0069] It may be provided that a refractive index variation anof the medium, in particular of the gas, is greater than TTA / Z over a time average. Here, I preferably describes an optical path length of the measurement radiation in the flow, in particular an optical flow, of the medium. Furthermore, A describes the wavelength of the measurement radiation.

[0070] In one embodiment of the device, it may alternatively or additionally be provided that the diffuser device has a moving, in particular rotating, phase mask in the beam path of the measurement radiation. Such a phase mask can be designed in particular as a diffusing disk.

[0071] In an advantageous development of the apparatus according to the invention, provision can be made for the measurement radiation source to be configured to create the measurement radiation in such a way that a wavelength spectrum of the measurement radiation contains a band of wavelengths.

[0072] It may be provided that the measurement radiation has a wavelength band with a width of 0.001 times to 0.1 times a center wavelength of the wavelength band.

[0073] It may be provided that the measurement radiation source is designed as a relatively broadband laser source.

[0074] In an advantageous development of the apparatus according to the invention, provision can be made for the mask device to be partly or completely formed as a phase mask device for influencing a phase angle of the field distribution of the measurement radiation.

[0075] By influencing the phase angle of the measurement radiation, interference phenomena can be precisely utilized. In an advantageous development of the apparatus according to the invention, provision can be made for the mask device to be partly or completely formed as an amplitude mask device for influencing an amplitude of the field distribution of the measurement radiation.

[0076] By influencing the amplitude distribution, a contrast of a resulting interferogram can be tuned.

[0077] In an advantageous development of the apparatus according to the invention, provision can be made for the mask device to be partly or completely formed as combination of a phase mask device for influencing a phase angle of the field distribution of the measurement radiation and an amplitude mask device for influencing an amplitude of the field distribution of the measurement radiation.

[0078] In an advantageous development of the apparatus according to the invention, provision can be made for the mask device to have dual substructures arranged on the dual lattice.

[0079] By preference, the dual substructures correspond to a target shape of the substructures to be examined.

[0080] In an advantageous development of the apparatus according to the invention, provision can be made for the dual substructures to be at least approximately circular.

[0081] Especially when examining or measuring vias, which frequently have a circular target cross section, whereby the substructures to be examined also have circular target cross sections, it is advantageous if also the dual substructures have a circular cross section.

[0082] In an advantageous development of the apparatus according to the invention, provision can be made for the dual substructures to be at least partly absorbing the measurement radiation.

[0083] This constitutes a preferred embodiment for the amplitude mask device.

[0084] In an advantageous development of the apparatus according to the invention, provision can be made for the phase mask device to bring about, away from the dual substructures, a phase offset of the measurement radiation of half a wavelength of the measurement radiation vis-a-vis a complement of the dual substructures on the phase mask device.

[0085] In a preferred configuration, the phase mask device brings about, away from the dual substructures, a phase offset of the measurement radiation of half a wavelength of the measurement radiation vis-a-vis a complement of the dual substructures and the dual substructures have an at least approximately circular embodiment.

[0086] A mask device can be preferably formed as a binary A / 2 phase aperture mask with a carrier in the dual lattice and is given by the expression XG* in Formula (2). rieG*(fc) , k E G* * XK [| + ieb(fc) mod A , otherwise

[0087]

[0088] In Formula (2), XK : = {k< E} specifies a disc of radius E or a differently shaped environment of zero. Further, the operator * symbolizes mathematical convolution.

[0089] Hence, G*‘ XK realizes an s-neighbourhood of the dual lattice. In Formula (2) the dual lattice is denoted as G*. The E-neighbourhoods can also be referred to as holes.

[0090] Here, the phase mask device is the case ec= eb= 0.

[0091] Provision can be made for the amplitude mask device with a non-vanishing eG.(fc) or ebas per Formula (2) to also be provided in addition to the phase mask device, the amplitude mask device being used to lower a transmission of the measurement radiation in a region away from the dual substructures or in a complement of the dual substructures on the phase mask device. In this case, e(fc) > 0 denotes a real absorption coefficient within or in the complement of the dual substructures.

[0092] In an advantageous development of the apparatus according to the invention, provision can be made for the optics system to comprise at least one Fourier device for performing an optical Fourier transform on the measurement radiation.

[0093] By using a Fourier device for performing the optical Fourier transform, the diffraction image of the lattice can be overlaid on the dual lattice in a particularly simple manner.

[0094] In an advantageous development of the apparatus according to the invention, provision can be made for an arrangement device to be provided and configured to accommodate the component in such a way that the periodic structure is arranged in an object plane of the Fourier device.

[0095] If the apparatus is configured to arrange the component such that the periodic structure is arranged in the object plane of the Fourier device, then the optical Fourier transform can be implemented particularly reliably and precisely.

[0096] The object plane is preferably arranged perpendicular to an optical axis of the optics system and / or the Fourier device.

[0097] In particular, the object plane can advantageously be arranged in, or coincide with, a focal plane, preferably a front focal plane, of the Fourier device. To this end, it is particularly advantageous if an arrangement device is provided and configured to accommodate the component.

[0098] In an advantageous development of the apparatus according to the invention, provision can be made for the mask device to be arranged in a pupil plane of the Fourier device which is reciprocal to the object plane.

[0099] An arrangement of the mask device in the pupil plane of the Fourier device allows a particularly reliable overlay of the diffraction image of the lattice, subject to an optical Fourier transform by the Fourier device, with the dual lattice on the mask device. By preference, the mask device is arranged in the imaging pupil of the Fourier device.

[0100] In an advantageous development of the apparatus according to the invention, provision can be made for the Fourier device to comprise a lens and either have a first numerical aperture in order to check the entire periodic structure perpendicularly to the object plane or have a second numerical aperture in order to check only a sectional region of the periodic structure parallel to the object plane.

[0101] In particular, provision can be made for the first numerical aperture to be preferably smaller than the second numerical aperture.

[0102] If a small numerical aperture or a high depth of field is used, then it is possible to detect, in simultaneously averaged fashion, all deviations of the periodic structure of the component along an optical axis or along a depth of the periodic component. The depth of field Az can be given by Formula (3).

[0103]

[0104] In Formula (3), A specifies the wavelength of the measurement radiation and NA specifies the numerical aperture of the Fourier device comprising a microscope objective.

[0105] By contrast, if use is made of a very large numerical aperture or a small depth of field (see Formula (3)), then it is possible to analyse sectional planes at a depth of the component along the optical axis.

[0106] Provision can be made for the apparatus according to the invention to be configured to scan the component at a depth z of the component. The depth z can be oriented along an optical axis in particular. By scanning at the depth z, it is possible to interferometrically determine positional deviations and / or other deviations as a function of the depth z.

[0107] Provision can be made for the Fourier device to be configured for operation in a first mode of operation, in which the Fourier device has the first numerical aperture, and for operation in a second mode of operation, in which the Fourier device has the second numerical aperture, with the first mode of operation and the second mode of operation not being present at the same time.

[0108] In an advantageous development of the apparatus according to the invention, provision can be made for the Fourier device to comprise an aperture stop which is configured to set the numerical aperture of the Fourier device.

[0109] The aperture stop enables a simple switchover between the first mode of operation and the second mode of operation.

[0110] Setting the numerical aperture or the depth of field, which may be linked as per Formula (3), is successful particularly simply and reliably by adapting a stop radius of the aperture stop of the Fourier device.

[0111] In this case, it is particularly advantageous if the lens of the Fourier device is designed as a high NA lens. By reducing the stop radius, it is possible in this case to reduce the high initial NA of the lens, whereby there is an increase in the depth of field.

[0112] In an advantageous development of the apparatus according to the invention, provision can be made for the mixing device to be formed as a part of the at least one Fourier device, wherein the at least one Fourier device comprises a refractive power, the refractive power being proportional to the wavelengths of the measurement radiation.

[0113] It can be provided that the beam mask device has diffractive behavior being proportional to the wavelengths of the measurement radiation.

[0114] In particular, it can be provided that the Fourier device is located downstream of the beam mask device along the beam path of the measurement radiation.

[0115] Particularly preferably, it can be provided that both the Fourier device downstream of the beam mask device for illuminating the component and the downstream Fourier device for imaging the measurement radiation, in particular the imaging device that will be described later, have refractive powers which are proportional, or at least approximately proportional, to a wavelength in the wavelength band or useful spectrum used.

[0116] As the refractive power is preferably proportional to the wavelength, the focal length of the Fourier device is preferably inversely proportional to the wavelength, in particular in first order inversely proportional.

[0117] Provision can be made for the focal to be linearly dependent on the inverse of the wavelength. This broader formulation allows for an offset, that can be optically corrected by a suitable set of lenses. Formula (15) gives an ideal Fourier mapping of a field E' in a plane of the entrance pupil with the spatial coordinates x' onto the respective object and / or image plane. The object plane is given with an index “plus” and the image plane with an index “minus”, so that the spatial coordinates are given by x±.

[0118] E+(x+,A) = f dx'E'(x',A) exp (±i^M (15)

[0119]

[0120] If the focal length in formula (15) is at least approximately inversely proportional to the wavelength, the Fourier mapping according to formula (15) is approximately independent of the wavelength.

[0121] The inventors have recognized that the wavelength-dependent beam splitting by a beam mask device, in particular a periodic beam mask device, leads to a wavelength-independent periodic image shift in the object plane and / or the image plane.

[0122] It may be provided that the inverse proportionality of the refractive forces in a pair-axial case is realized by a dispersion of optical imaging elements and / or illumination elements of the optical system.

[0123] In particular, it may be provided that the optical system has coated glasses and / or mirror layers.

[0124] In particular, it may be provided that the coated glasses and / or mirror layers are used in a combination with intermediate images.

[0125] Furthermore, the use of diffractive optics and / or metal lenses may be provided in the optical system or device to achieve the anti-proportionality.

[0126] It can therefore be provided that a magnification of lenses, in particular of the Fourier device, of the optical system as well as the lattice vectors of the dual lattice in the beam mask device which are reciprocal to the inspected lattice are independent of the wavelength of the measurement radiation.

[0127] In particular, it may be provided that the mask device simultaneously fulfills the function of the beam mask device. Thus, the mask device fulfills both the function of averaging the interferogram and the function of splitting the illumination.

[0128] It may be provided that the optical system contains an illumination optic for illuminating the component and an imaging optic for imaging the measurement radiation. In particular, it may be provided that the illumination optics and the imaging optics coincide during operation in reflection.

[0129] Furthermore, it can be provided that the illumination optics and the imaging optics are telecentric. This avoids that the image of the periodic structure or the interferogram does not contain a phase factor from a telecentric error. In particular, the phase factor can be proportional to Ixl2. In an advantageous development of the apparatus according to the invention, provision can be made for a holding device to be provided and configured to displace the mask device in the pupil plane, preferably in both spatial directions of the pupil plane.

[0130] By displacing the mask device in the pupil plane, it is possible to minimize influences of optical aberrations on a measurement result of the check of the component.

[0131] In a manner analogous to phase shifting known from interferometry, some of the aberrations can be "removed by calibration" by displacing the mask device. Additionally, this enables a more accurate determination of the interference phases of the measurement radiation.

[0132] In an advantageous development of the apparatus according to the invention, provision can be made for the phase mask device to be formed by an etched structuring of a half wavelength coating on a transmissive or transmissive substrate.

[0133] In an advantageous development of the apparatus according to the invention, provision can be made for the amplitude mask device to be formed by a coating on a substrate

[0134] If the mask is produced by an etched structuring of a A / 2 coating on a transmissive substrate, this enables a particularly simple and reliable formation of both the mask device and a constant absorptive effect eG. > 0 in the dual substructures and / or eb> 0 in their complement within the mask device as per Formula (2). In a preferred embodiment eG* > ehis achieved by etching the complement of the dual substructures.

[0135] In particular, provision can be made for the transmissive substrate to be part of the optical system and / or an optics design of the apparatus according to the invention.

[0136] The mask device can be formed by transmissive or slightly absorbent glasses which have a structured thickness. By preference, the thickness of the glasses is lower in the complement of the dual substructures and proportional to the phase effect of the mask device given in Formula (2) by XG*. The depth variation required to this end can be achieved by etching processes in particular.

[0137] In an alternative or in addition, provision can be made for the phase mask device to be formed by a mirror with height structuring. In this case, the height structuring of the mirror is preferably proportional to the phase effect XG* as per Formula (2).

[0138] In both the embodiment by means of a glass with a depth structure or a mirror with a height structure, the path difference between the dual substructures and their complement on the phase mask device for the measurement radiation is an optical path length of half a wavelength or A / 2 modulo integer multiples of A. By preference, provision is made for the aberrations caused by the mask device or the substrate to be compensated for by the optical system, in particular the Fourier device and very particularly the lens there.

[0139] In an alternative or in addition, provision can be made for a laser to be used to form or drill holes with an optical length of A / 2 in a glass substrate.

[0140] In an advantageous development of the apparatus according to the invention, provision can be made for the mask device, in particular the phase mask device, to be designed to be digitally actuatable and / or transmissive and / or reflective and / or as a microelectronic mechanical system and / or as a spatial light modulator (SLM), in particular as a liquid crystal on silicon SLM (LCOS-SLM) and / or as a spatial optical phase modulator.

[0141] If a digitally actuatable, transmissive, or reflective mask device based on MEMS (microelectromechanical system) for example is used, it is possible to set any desired phase and / or amplitude effects or any desired dual lattices or G* patterns within the spatial resolution of the MEMS.

[0142] In an advantageous development of the apparatus according to the invention, provision can be made for an imaging device to be provided for imaging the measurement radiation on the camera device.

[0143] The imaging device enables, preferably in a second Fourier step, reliable imaging of the measurement radiation, which carries the information about the component, on a camera device. In particular, this can ensure a high image quality which enables a preferably digital analysis of the interferograms arising as a result.

[0144] In an advantageous development of the apparatus according to the invention, provision can be made for the Fourier device to comprise a zoom optical unit.

[0145] The use of a zoom optical unit allows a pupil dimension of the Fourier device and hence an illumination region of the mask device to be varied. For example, the dual lattice G* can be scaled as a result.

[0146] Together with the zoom optical unit, virtually any desired pattern for the dual lattice or G* pattern can be set by means of the preferably digitally actuatable and / or transmissive and / or reflective mask device and / or the mask device designed as a microelectronic mechanical system and / or as a spatial light modulator, in particular as a liquid crystal on silicon SLM and / or as a spatial optical phase modulator.

[0147] In an advantageous development of the apparatus according to the invention, provision can be made for the measurement radiation source to be configured to create measurement radiation at different wavelengths and / or for the measurement radiation to be infrared radiation. If use is made of different wavelengths together with appropriately scaled dual lattices or G* patterns, then it is possible to increase measurement accuracy and / or detection accuracy.

[0148] The scaling of the dual lattice or the G* pattern can be implemented here by the above-described zoom lens and / or by changing the mask device.

[0149] The above-described configuration of the mask device as a dual lattice G* is particularly suitable for the purpose of inspecting NAND memory chips or, more generally, for inspecting G-periodic structures.

[0150] Further, if the lens preferably uses infrared light, then the component can be penetrated through its depth by the measurement radiation. In particular, NAND stacks can be penetrated through their depth by the measurement radiation in this way.

[0151] The prior art has proposed methods in which the substructures are compared in pairs by means of differential interference contrast microscopy (DIC microscopy). Compared to the apparatus according to the invention, such approaches are disadvantageous in that individual substructures, in particular vias, do not represent a good reference as they rigidly deviate from a target shape but may nevertheless be uncritical to the production. However, the DIC signal transports no information as to how critical the large relative deviation measured is to the practical production. Such problems are circumvented by the apparatus according to the invention.

[0152] Thus, the apparatus according to the invention is particularly suitable for checking manufactured vias for defects in three dimensions and for qualifying and / or measuring vias.

[0153] In an advantageous development of the apparatus according to the invention, provision can be made for the dual lattice to be designed as a reciprocal of a one-dimensional and / or two-dimensional target shape of the lattice.

[0154] The apparatus is particularly advantageous when used to measure a one-dimensional and / or two-dimensional lattice.

[0155] For measuring a two-dimensional lattice, the dual lattice preferably likewise has a two-dimensional, in particular extensive, form.

[0156] For measuring a one-dimensional lattice, the dual lattice preferably likewise has a one-dimensional, in particular linear, form.

[0157] The invention also relates to a method for checking a component, having the features specified in Claim 30. In the method according to the invention for checking a component with a periodic structure having substructures arranged on a lattice, use is made of at least one measurement radiation source for creating measurement radiation and at least one optics system. According to the invention, provision is made for a respective deviation of the substructures from a single reference substructure to be ascertained by interferometry.

[0158] In the method according to the invention, a deviation of the periodic structure from a target structure is ascertained by interferometry. In this case, a respective shape of the substructures and their position on the lattice is considered to be a complex-value optical mask.

[0159] The method according to the invention is advantageous in that the direct interferometric comparison, in contrast to the averaging of intensity images of a conventional microscopy objective, allows a direct detection of amplitude deviations and phase deviations.

[0160] In the method according to the invention, a diffraction image of the lattice and of the corresponding dual or reciprocal dual lattice, which are preferably virtually punctiform lattices, can be overlaid on one another.

[0161] In an advantageous development of the method according to the invention, provision can be made for the reference substructure to be ascertained by periodic averaging of the periodic structure.

[0162] The interferogram made of the object, i.e. the component or the lattice, and the reference substructure, with the reference substructure arising by periodic averaging, can in particular be measurable as an intensity image of the form given in Formula (4).

[0163] / ( / ?%) oc obj(x) — c obj(x + g)

[0164]

[0165] g£G

[0166] In Formula (4), G represents the lattice, on the lattice points of which the substructures are arranged, or G can be referred to as the lattice of the substructure positions.

[0167] The lattice can have a one-dimensional and / or two-dimensional form.

[0168] x describes a location in the object space and describes an imaging scale of the optical system, and c describes a complex constant, preferably near the inverse of the number of lattice points, with the result that the reference substructure approximately represents periodic averaging.

[0169] In an advantageous development of the method according to the invention, provision can be made for the periodic averaging to be performed by overlaying a diffraction image of the periodic structure with a mask device. In particularly advantageous fashion, the periodic averaging can be created by the overlay of the diffraction images of the dual lattice G* which is correspondingly dual or is referred to as reciprocal to the lattice G using terminology of crystallography.

[0170] An alternative method for recording the interference image l(x) according to Formula (4) can consist in a separate creation of a reference image and a test image, followed by coherently overlaying the reference image and the test image.

[0171] In an advantageous development of the method according to the invention, provision can be made for the measurement radiation source is configured to create the measurement radiation in such a way that the measurement radiation at an entry pupil of the optics system has a pattern at least partially corresponding to the dual lattice.

[0172] This allows to measure the resulting interferogram without artifacts originating form a tilt between the diffracted measurement radiation and the mask device.

[0173] For an object in transmission, an illumination pupil pattern of the measurement radiation, especially a beam mask device, and an imaging pupil pattern, especially the mask device, are preferably conjugate.

[0174] The origin 0 in G* does not have to lie on the optical axis of a rotationally symmetric objective.

[0175] Conversely, one can define the 0 in G* as the origin of the pupil. In this case the aperture would no longer be centered and / or the objective would no longer be rotationally symmetric. Thus, the object would be tilted with a correspondingly modified effective lattice G.

[0176] In reflection, this also applies for the time being.

[0177] A Laue condition results from conjugacy and / or the condition the G* is reciprocal to G, i.e. G*=reciprocal(G). Therefore, an optical axis of the lens is not decisive.

[0178] In the case of NAND inspection (see later), however, the optical axis is the preferred Oth order illumination direction due to the z-orientation of the holes or vias in the NAND.

[0179] In an advantageous development of the method according to the invention, provision can be made for the measurement radiation to be influenced by the mask device by virtue of a phase angle of the measurement radiation within dual substructures, preferably circular dual substructures, on a dual lattice which is reciprocal to a target shape of the lattice.

[0180] The dual substructures can be absorbing the measurement radiation, thus defining an embodiment of the mask device being partly or completely an amplitude mask device. In case the dual substructures are completely absorbing, that is eG* = oo in Formula (2) above, the interferogram resembles a dark field microscopy image that captures deviations from the periodicity.

[0181] For the amplitude mask device, the gray filter should preferably absorb on G*, not in the complement, so that the weighting between the object and the reference substructure is correct.

[0182] The case of complete absorption by the amplitude mask device constitutes a dark field inspection method.

[0183] In an advantageous development of the method according to the invention, provision can be made for the dual substructures to be offset by half a wavelength of the measurement radiation vis-a-vis a complement of the dual substructures on the mask device.

[0184] In this case the mask device is partly or completely formed as a phase mask device.

[0185] Furthermore, the mask device acts on the measurement radiation in the style of a binary, e.g. A / 2 phase, aperture mask, in which the dual substructures are arranged on a carrier which is represented by the dual lattice G*.

[0186] Provision can be made for the dual substructures to be at least partly absorbing the measurement radiation.

[0187] It is advantageous if the zeroth order of diffraction of the mask device has a similar diffraction efficiency to the sum of the higher, imaged orders of diffraction such that object and reference, i.e. an image of the component and an image of the mask device, which are described by the two summands in Formula (4), have similar intensities, at least in a mean value over the location x. To this end, the complement of the perforated mask or the dual substructures on the mask device can have an absorption coefficient eG»(fc) > 0 as per Formula (2).

[0188] Provision can be made for an intensity pattern of the measurement radiation on the camera device to be ascertained by virtue of the measurement radiation being imaged on the camera device by an imaging device following the overlay of the diffraction image of the periodic structure with the mask device.

[0189] In an advantageous development of the method according to the invention, provision can be made for a focal length of the Fourier device to be varied by a zoom optical unit.

[0190] This allows the realization of dual lattices G* for different object lattice structures or for different lattices G without exchanging the mask device or the phase aperture mask. Moreover, slight wavelength adaptations can be carried out by way of the zoom optical unit provided the phase offset in the phase mask device or the phase aperture mask remains at least approximately at half a wavelength of the measurement radiation.

[0191] If the above-described aperture mask is imaged on the camera device, then the intensity image given by Formula (4) arises on the camera device and is rendered measurable by the camera device. This facilitates a digital analysis of the intensity distribution. On the camera device, the intensity distribution arises as the norm square of a complex-linear mapping S which, apart from scaling but with consideration of a diffraction at a pupil edge, is given by Formula (5).

[0192] S(o& / )(px) := F^CXNA • exp(iXG*) • Ffobj)(x) (5)

[0193]

[0194] In Formula (5) specified above, XG* describes the perforated mask or the mask device as per Formula (2). According to Formula (5), the periodic structure of the component is given as a complex-value optical mask obj. Ft denotes an operator of a Fourier transform with focal length f, which is given by Formula (5a).

[0195] f / < xk,x > 2n\ Fftpbj'Xxk) •■= I exp I — i - - - — j obj(x) dzx (5a)

[0196]

[0197] J \ J A '

[0198] In Formula (5a), the vector specifies two-dimensional Xk spatial coordinates in a collimated region of the measurement radiation. Physical pupil coordinates k, which describe a beam direction of the measurement radiation and which are normalized to 2TT / A, are described by Formula (5b).

[0199] x^ 2rc

[0200]

[0201] As a function of k, FfObj is thus a conventional Fourier transform of obj.

[0202] A characteristic function of the pupil-restricting stop is given in Formula (6).

[0203] „ 2TT (FI) XNAC^)=1 for |fc| < NA • — ; 0 otherwise ' '

[0204]

[0205] Further, f‘ describes a focal length of a second Fourier step, in particular an effect of the imaging device, with the result that the mapping S contains the imaging scale 0 •■= y.

[0206]

[0207] The above-described characteristic function for restricting the pupil represents a low-pass filter in the present case. The characteristic function for restricting the pupil can be expressed as a convolution of the signal of the measurement radiation with an amplitude point spread function ^””1XNA Such a convolution can be observable as a blurring of the signal in particular, especially in the form of Airy discs.

[0208] However, phase information in the difference signal of the measurement radiation advantageously is preserved a priori in the intensity signal according to Formula (5).

[0209] The intensity distribution given in Formula (5) can be further rewritten mathematically, whereby the equation according to Formula (7) arises approximately.

[0210] S(obj)(^x) « [F~PXNA * obj + t' obj }) (x) (7)

[0211]

[0212] In Formula (7), t, f denote positive constants in x, which depend in particular on a diameter of the dual substructures and on the absorption coefficient of the mask device in the complement of the dual substructures. Further, 5G* denotes a Dirac delta function on the carrier of the dual lattice G*. The expression given in Formula (7) can be rewritten approximately as the expression given in Formula (8) using Fourier's theorem.

[0213] S(obj)(^x) « P^F^XNA

[0214]

[0215] * {“t obj + t' 8G* * obj })(x) (8)

[0216] In turn, the expression as per Formula (8) can be rewritten as the expression for the mapping S given in Formula (9). In this case, the expressions on the right-hand side of Formula (8) and Formula (9) are mathematically identical.

[0217] S(pbj)(J3x) « p I FfPxNA * Sobj + t' obj(x + g) ■ j (x) (9)

[0218]

[0219] The norm square of S thus approximates the interferogram according to the invention as per Formula (4).

[0220] In a manner analogous to phase shifting known from interferometry, some of the aberrations can additionally be "removed by calibration" by varying the mask device, in particular, the 2 / 2 phase shift in the phase mask device and / or the absorption coefficients of the amplitude mask device, resulting in varying complex constants c in Formula (4). Further, a partial calibration of aberrations and hence a more accurate determination of the interference phases of the measurement radiation is made possible.

[0221] Advantageously, provision can be made for the Fourier device to comprise a neutral density filter, preferably a neutral density filter arranged in a pupil plane. Particularly preferably, the neutral density filter has the shape of a Gaussian profile as per Formula (10).

[0222] xrf) °C exp

[0223]

[0224] In Formula (10), NA2Gauss denotes a numerical aperture under the assumption of a Gaussian distribution.

[0225] What can be achieved by the neutral density filter designed as per Formula (10) is that the expression ~ XNA itself is Gaussian and in particular a positive real, whereby the interference signal of the measurement radiation is only Gauss averaged but not phase modulated by the neutral density filter.

[0226] Alternatively, the neutral density filter can be integrated directly in the aperture mask or the mask device by way of the absorption coefficients eG*(fc),efcin Formula (2).

[0227] In an advantageous development of the method according to the invention, provision can be made for the diffraction image of the periodic structure and the mask device to be overlaid in a pupil plane of the Fourier device.

[0228] The Fourier device can preferably be designed as a Fourier lens. For example, the Fourier device can be designed as a catadioptric lens element, as for example known from document US 7,639,419 B2, in particular from Figure 16 therein, and / or as part of a lithography lens, as for example known from document US 2018 / 0031815 A1 , in particular from Figure 1 therein.

[0229] It is advantageous if provision is made for the Fourier device to be aberration optimized. In particular, it is advantageous if the Fourier device has only small phase gradients such that distortions and hence a mismatch between the mask device and the periodic structure can be avoided.

[0230] In this case, aberrations may lead to small phase modulations, with aberrations in Formula (5) arising as a result of the following applying:

[0231] argfex) * 0 for | k|<NA- —

[0232]

[0233] In an advantageous development of the method according to the invention, provision can be made for a plurality of interferograms to be recorded, with the mask device being displaced to a different location in the pupil plane for each interferogram.

[0234] Some of the above-described aberrations can be removed by calibration by way of phase shifting. As a result of an offset of the perforated mask, the phase of t'(e) in the difference signal S can be varied as per Formula (9), which in a manner analogous to phase shifting in interferometry allows a more accurate determination of the interference phases. In an advantageous development of the method according to the invention, provision can be made for different wavelengths of the measurement radiation to be used, with preferably the dual lattice being scaled in accordance with the wavelength of the measurement radiation used.

[0235] Measurement accuracy can be increased further by varying the wavelength.

[0236] In an advantageous development of the method according to the invention, provision can be made for the scaling of the dual lattice

[0237] to be brought about by a change of the mask device and / or

[0238] to be brought about by the Fourier device which preferably comprises a zoom optical unit, with a pupil size and / or an illumination region of the mask device being varied.

[0239] By varying the mask device and / or a focal length of the Fourier device, it is possible to scale the dual lattice in particularly simple and reliable fashion.

[0240] The zoom optical unit allows optical properties of the Fourier device to be varied particularly quickly. This can increase a throughput of the method.

[0241] In an advantageous development of the method according to the invention, provision can be made for the component to be additionally checked using a method for measuring an optically critical dimension, the intensity distribution of which is simulated with the aid of a parameterized model of the component.

[0242] In addition to the above-described developments, the method according to the invention can also be combined with methods for measuring the optically critical dimension (OCD methods). In OCD methods, the mapping S to be expected as per Formula (9) is simulated with the aid of a parameterized model of the component. In the process, the parameters of the parameterized model are optimized such that they fit to a measurement result, i.e. to the actual measured mapping S as per Formula (9).

[0243] This results in an accuracy of a parameter reconstruction of the parameterized model which is advantageously increased a priori by way of the inclusion according to the invention of the phase information of the measurement radiation.

[0244] In an advantageous development of the method according to the invention, provision can be made for a NAND memory chip with periodically arranged vias to be checked as the component.

[0245] The method is particularly suitable for checking a memory chip comprising a NOT-AND logic gate (NAND memory chip). The vias arranged periodically in such NAND memory chips, as a periodic structure, can particularly advantageously be checked in reliable and quick fashion by means of the method according to the invention. It is also advantageous if a parameterized model of the NAND memory chip is simulated within the scope of the combination with OCD methods.

[0246] Provision can be made for the method according to the invention to be combined with methods of differential interference contrast microscopy.

[0247] Methods of differential interference contrast microscopy for measuring components are described in DE 102018217 115 A1 , for example. The methods according to DE 102018217 115 A1 may be suitable in particular for implementing mixed forms with the method according to the invention.

[0248] In an advantageous development of the method according to the invention, provision can be made for the dual lattice to be designed as a reciprocal of a one-dimensional and / or two-dimensional target shape of the lattice.

[0249] The invention further relates to a lithography system having the features specified in Claim 44.

[0250] The lithography system according to the invention, in particular a projection exposure apparatus for producing a semiconductor component, comprises an illumination system with a radiation source and an optical unit which comprises at least one optical element. According to the invention, an above-described apparatus according to the invention is provided for checking a component, in particular for checking the semiconductor component. In an alternative or in addition, provision is made for the lithography system to be configured to carry out the method according to the invention for checking a component, in particular for checking the semiconductor component.

[0251] Thus, the apparatus according to the invention for checking a component is provided in the lithography system according to the invention as a part of the lithography system, and is preferably configured to check the semiconductor component to be produced by the lithography system. In an alternative or in addition, the lithography system is configured to carry out the above-described method according to the invention for checking a component, with the lithography system preferably being configured to perform the method according to the invention for checking the semiconductor component to be produced by the lithography system.

[0252] Provision can be made for, in the lithography system according to the invention, the apparatus for checking the semiconductor component to be spatially separate from the location where the semiconductor component is exposed and / or for the method for checking the semiconductor component to be produced by the lithography system to be performed spatially separate from the location where the semiconductor component is exposed.

[0253] As a result of the integrated quality control, the lithography system according to the invention enables the efficient and reliable production of high-quality semiconductor components. In the present case, the method according to the invention and the apparatus according to the invention are used to check a component presently provided by the semiconductor component to be produced.

[0254] In an advantageous development of the lithography system according to the invention, provision can be made for the latter to be configured to produce and check a semiconductor component designed as a NAND memory chip with periodically arranged vias.

[0255] In general terms, it is advantageous if the lithography system according to the invention is configured to produce structures imaged on a wafer and check these with regards to possible malformations.

[0256] The component to be checked according to the invention is preferably a semiconductor component, in particular a semiconductor component produced by a or the lithography system. By preference, the semiconductor component is a NAND memory chip.

[0257] Features described in conjunction with one of the subjects of the invention, specifically given by the apparatus according to the invention, the method according to the invention, or the lithography system according to the invention, are also advantageously implementable for the other subjects of the invention. Likewise, advantages specified in conjunction with one of the subjects of the invention can also be understood in relation to the other subjects of the invention.

[0258] Additionally, it should be noted that terms such as "comprising", "having", or "with" do not exclude other features or steps. Furthermore, terms such as "a(n)" or "the" which indicate single steps or features do not exclude a plurality of features or steps - and vice versa.

[0259] However, in a puristic embodiment of the invention, provision may also be made for the features introduced in the invention using the terms "comprising", "having", or "with" to be an exhaustive enumeration. Accordingly, one or more enumerations of features can be considered to be exhaustive within the scope of the invention, for example respectively considered for each claim. By way of example, the invention can consist exclusively of the features specified in Claim 1 .

[0260] It should be noted that labels such as "first" or "second", etc. are used predominantly for reasons of distinguishability between respective apparatus or method features and are not necessarily intended to indicate that features require one another or are related to one another.

[0261] Moreover, at this point it is disclosed that the apparatus according to the invention and / or the method according to the invention is also suitable for measuring a surface of any desired element. For example, the surface can be a surface of a component from the automotive industry. In this respect, the applicant reserves the right to file a divisional application in which the feature "optical element" has been replaced by the feature "element". Exemplary embodiments of the invention will be described in detail hereinbelow with reference to the drawing.

[0262] The figures each show preferred exemplary embodiments in which individual features of the present invention are illustrated in combination with one another. Features of an exemplary embodiment are also implementable independently of the other features of the same exemplary embodiment, and may readily be combined accordingly by a person skilled in the art to form further viable combinations and subcombinations with features of other exemplary embodiments.

[0263] In the figures, functionally identical elements are given the same reference signs.

[0264] In the drawing:

[0265] Figure 1 shows a meridional section of an EUV projection exposure apparatus;

[0266] Figure 2 shows a DUV projection exposure apparatus;

[0267] Figure 3 shows a schematic illustration of a possible embodiment of an apparatus according to the invention for checking a component;

[0268] Figure 4 shows a schematic illustration of a possible embodiment of the mask device;

[0269] Figure 5 shows a block diagram-type illustration of a possible embodiment of a method according to the invention for checking a component;

[0270] Figure 6 shows a schematic illustration of a possible embodiment of a NAND memory chip to be checked;

[0271] Figure 7 shows a schematic illustration of a possible embodiment of a mixing device.

[0272] Figure 8 shows a schematic illustration of a further possible embodiment of the mixing device;

[0273] Figure 9 shows a schematic illustration of a further possible embodiment of the mixing device; and

[0274] Figure 10 shows a schematic illustration of a further possible embodiment of the apparatus according to the invention and in particular of the mixing device.

[0275] With reference to Figure 1, the essential components of a microlithographic EUV projection exposure apparatus 100 as an example of a lithography system are initially described below in exemplary fashion. The description of the basic structure of the EUV projection exposure apparatus 100 and of the component parts thereof should not be interpreted restrictively here.

[0276] An illumination system 101 of the EUV projection exposure apparatus 100 comprises, besides a radiation source 102, an illumination optical unit 103 for the illumination of an object field 104 in an object plane 105. What is exposed here is a reticle 106 arranged in the object field 104. The reticle 106 is held by a reticle holder 107. The reticle holder 107 is displaceable, in particular in a scanning direction, by way of a reticle displacement drive 108.

[0277] In Figure 1 , a Cartesian xyz-coordinate system is plotted to aid the explanation. The x-direction runs perpendicularly into the plane of the drawing. The y-direction runs horizontally, and the z-direction runs vertically. In Figure 1 , the scanning direction runs along the y-direction. The z-direction runs perpendicularly to the object plane 105.

[0278] The EUV projection exposure apparatus 100 comprises a projection optical unit 109. The projection optical unit 109 serves for imaging the object field 104 into an image field 110 in an image plane 111. The image plane 111 extends parallel to the object plane 105. Alternatively, an angle that differs from 0° between the object plane 105 and the image plane 111 is also possible.

[0279] A structure on the reticle 106 is imaged onto a light-sensitive layer of a wafer 112 arranged in the region of the image field 110 in the image plane 111. The wafer 112 is held by a wafer holder 113. The wafer holder 113 is displaceable, in particular along the y-direction, by way of a wafer displacement drive 114. The displacement on the one hand of the reticle 106 by way of the reticle displacement drive 108 and on the other hand of the wafer 112 by way of the wafer displacement drive 114 may take place in such a way as to be synchronized with one another.

[0280] The radiation source 102 is an EUV radiation source. The radiation source 102 emits EUV radiation 115, in particular, which is also referred to as used radiation or illumination radiation below. In particular, the used radiation 115 has a wavelength in the range between 5 nm and 30 nm. The radiation source 102 can be a plasma source, for example an LPP source ("laser produced plasma") or a GDPP source ("gas discharged produced plasma"). It can also be a synchrotron-based radiation source. The radiation source 102 can be a free electron laser (FEL).

[0281] The illumination radiation 115 emanating from the radiation source 102 is focused by a collector 116. The collector 116 may be a collector with one or more ellipsoidal and / or hyperboloid reflection surfaces. The at least one reflection surface of the collector 116 can be impinged upon by the illumination radiation 115 with grazing incidence (Gl), i.e. with angles of incidence greater than 45°, or with normal incidence (Nl), i.e. with angles of incidence less than 45°. The collector 116 can be structured and / or coated, firstly, for optimizing its reflectivity for the used radiation 115 and, secondly, for suppressing extraneous light. Downstream of the collector 116, the illumination radiation 115 propagates through an intermediate focus in an intermediate focal plane 117. The intermediate focal plane 117 may represent a separation between a radiation source module, having the radiation source 102 and the collector 116, and the illumination optical unit 103.

[0282] The illumination optical unit 103 comprises a deflection mirror 118 and, downstream thereof in the beam path, a first facet mirror 119. The deflection mirror 118 may be a plane deflection mirror or, alternatively, a mirror with a beam-influencing effect that goes beyond the pure deflection effect. In an alternative or in addition, the deflection mirror 118 may be designed as a spectral filter that separates a used light wavelength of the illumination radiation 115 from extraneous light at a different wavelength. If the first facet mirror 119 is arranged in a plane of the illumination optical unit 103 that is optically conjugate to the object plane 105 as a field plane, it is also referred to as a field facet mirror. The first facet mirror 119 comprises a plurality of individual first facets 120, which are also referred to below as field facets. Only a few of these facets 120 are illustrated in Figure 1 in exemplary fashion.

[0283] The first facets 120 can be embodied in the form of macroscopic facets, in particular in the form of rectangular facets or in the form of facets with an arcuate peripheral contour or a peripheral contour of part of a circle. The first facets 120 may be embodied as plane facets or alternatively as convexly or concavely curved facets.

[0284] As is known for example from DE 10 2008 009 600 A1 , the first facets 120 themselves can also each be composed of a multiplicity of individual mirrors, in particular a multiplicity of micromirrors. In particular, the first facet mirror 119 can be in the form of a microelectromechanical system (MEMS system). For details, reference is made to DE 102008 009600 A1.

[0285] The illumination radiation 115 travels horizontally, i.e. along the y-direction, between the collector 116 and the deflection mirror 118.

[0286] In the beam path of the illumination optical unit 103, a second facet mirror 121 is arranged downstream of the first facet mirror 119. Provided the second facet mirror 121 is arranged in a pupil plane of the illumination optical unit 103, it is also referred to as a pupil facet mirror. The second facet mirror 121 can also be arranged at a distance from a pupil plane of the illumination optical unit 103. In this case, the combination of the first facet mirror 119 and the second facet mirror 121 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1 , EP 1 614 008 B1 and US 6,573,978.

[0287] The second facet mirror 121 comprises a plurality of second facets 122. In the case of a pupil facet mirror, the second facets 122 are also referred to as pupil facets. The second facets 122 may likewise be macroscopic facets, which may for example have a round, rectangular or else hexagonal periphery, or may alternatively be facets composed of micromirrors. In this regard, reference is likewise made to DE 102008 009600 A1.

[0288] The second facets 122 can have plane or, alternatively, convexly or concavely curved reflection surfaces.

[0289] The illumination optical unit 103 consequently forms a doubly faceted system. This basic principle is also referred to as fly's eye integrator.

[0290] It may be advantageous to arrange the second facet mirror 121 not exactly in a plane that is optically conjugate to a pupil plane of the projection optical unit 109.

[0291] With the aid of the second facet mirror 121 , the individual first facets 120 are imaged into the object field 104. The second facet mirror 121 is the last beam-shaping mirror or else indeed the last mirror for the illumination radiation 115 in the beam path upstream of the object field 104.

[0292] In a further embodiment (not illustrated) of the illumination optical unit 103, a transfer optical unit may be arranged in the beam path between the second facet mirror 121 and the object field 104, and contributes in particular to the imaging of the first facets 120 into the object field 104. The transfer optical unit may have exactly one mirror or, alternatively, also two or more mirrors, which are arranged in succession in the beam path of the illumination optical unit 103. In particular, the transfer optical unit can comprise one or two mirrors for normal incidence (Nl mirror, "normal incidence" mirror) and / or one or two mirrors for grazing incidence (Gl mirror, "grazing incidence" mirror).

[0293] In the embodiment shown in Figure 1 , the illumination optical unit 103 comprises exactly three mirrors downstream of the collector 116, specifically the deflection mirror 118, the field facet mirror 119 and the pupil facet mirror 121.

[0294] In a further embodiment of the illumination optical unit 103, the deflection mirror 118 can also be omitted, and so the illumination optical unit 103 can then have exactly two mirrors downstream of the collector 116, specifically the first facet mirror 119 and the second facet mirror 121 .

[0295] The imaging of the first facets 120 into the object plane 105 by means of the second facets 122 or using the second facets 122 and a transfer optical unit is routinely only approximate imaging.

[0296] The projection optical unit 109 comprises a plurality of mirrors Mi, which are numbered in accordance with their arrangement in the beam path of the EUV projection exposure apparatus 100.

[0297] In the example illustrated in Figure 1 , the projection optical unit 109 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve or any other number of mirrors Mi are likewise possible. The second-last mirror M5 and the last mirror M6 each have a through opening for the illumination radiation 115. The projection optical unit 109 is a doubly obscured optical unit. The projection optical unit 109 has an image-side numerical aperture which is greater than 0.5 and which can also be greater than 0.6 and which, for example, can be 0.7 or 0.75.

[0298] Reflection surfaces of the mirrors Mi can be in the form of 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 unit 103, the mirrors Mi may have highly reflective coatings for the illumination radiation 115. These coatings may be in the form of multi-layer coatings, in particular with alternating layers of molybdenum and silicon.

[0299] The projection optical unit 109 has a large object-image offset in the y-direction between a y-coordinate of a centre of the object field 104 and a y-coordinate of the centre of the image field 110. In the y-direction, this object-image offset can be of approximately the same magnitude as a z-distance between the object plane 105 and the image plane 111.

[0300] The projection optical unit 109 may in particular have an anamorphic form. In particular, it has different imaging scales px, py in the x- and y-directions. The two imaging scales px, py of the projection optical unit 109 are preferably (px, py) = (+ / -0.25, + / -0.125). A positive imaging scale p means imaging without image inversion. A negative sign for the imaging scale p means imaging with image inversion.

[0301] The projection optical unit 109 consequently leads to a reduction in size with a ratio of 4:1 in the x-direction, i.e. in a direction perpendicular to the scanning direction.

[0302] The projection optical unit 109 leads to a reduction in size of 8:1 in the y-direction, i.e. in the scanning direction.

[0303] Other imaging scales are likewise possible. Imaging scales with the same signs and the same absolute values in the x-direction and y-direction, for example with absolute values of 0.125 or 0.25, are also possible.

[0304] The number of intermediate image planes in the x-direction and in the y-direction in the beam path between the object field 104 and the image field 110 may be the same or may be different depending on the design of the projection optical unit 109. 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.

[0305] One of the pupil facets 122 in each case is assigned to exactly one of the field facets 120, in each case to form an illumination channel for illuminating the object field 104. In particular, this can produce illumination according to the Kohler principle. The far field is deconstructed into a multiplicity of object fields 104 using the field facets 120. The field facets 120 create a plurality of images of the intermediate focus on the pupil facets 122 respectively assigned thereto.

[0306] The field facets 120 are each imaged by an assigned pupil facet 122 onto the reticle 106 in a manner overlaid on one another in order to illuminate the object field 104. The illumination of the object field 104 is in particular as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be attained by overlaying different illumination channels.

[0307] The illumination of the entrance pupil of the projection optical unit 109 can be defined geometrically by way of an arrangement of the pupil facets. The intensity distribution in the entrance pupil of the projection optical unit 109 can be set by selecting the illumination channels, in particular the subset of the pupil facets that guide light. This intensity distribution is also referred to as illumination setting.

[0308] A likewise preferred pupil uniformity in the region of portions of an illumination pupil of the illumination optical unit 103 that are illuminated in a defined way can be achieved by a redistribution of the illumination channels.

[0309] Further aspects and details of the illumination of the object field 104 and in particular of the entrance pupil of the projection optical unit 109 are described below.

[0310] The projection optical unit 109 may have a homocentric entrance pupil in particular. The latter can be accessible. It can also be inaccessible.

[0311] The entrance pupil of the projection optical unit 109 generally cannot be illuminated exactly by means of the pupil facet mirror 121. The aperture rays often do not intersect at a single point in the event of imaging the projection optical unit 109, which telecentrically images the centre of the pupil facet mirror 121 onto the wafer 112. However, it is possible to find a surface area in which the spacing of the aperture rays, which is determined in pairs, becomes minimal. This surface area represents the entrance pupil or a surface area in real space that is conjugate thereto. In particular, this surface area exhibits a finite curvature.

[0312] It may be the case that the projection optical unit 109 has 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 of the transfer optical unit, should be provided between the second facet mirror 121 and the reticle 106. With the aid of this optical component, it is possible to take account of the different pose of the tangential entrance pupil and the sagittal entrance pupil.

[0313] In the arrangement of the components of the illumination optical unit 103 illustrated in Figure 1 , the pupil facet mirror 121 is arranged in an area conjugate to the entrance pupil of the projection optical unit 109. The first field facet mirror 119 is arranged so as to be tilted in relation to the object plane 105. The first facet mirror 119 is arranged so as to be tilted in relation to an arrangement plane defined by the deflection mirror 118.

[0314] The first facet mirror 119 is arranged so as to be tilted in relation to an arrangement plane defined by the second facet mirror 121 .

[0315] Figure 2 shows an exemplary DUV projection exposure apparatus 200. The DUV projection exposure apparatus 200 comprises an illumination system 201 , a device known as a reticle stage 202 for receiving and exactly positioning a reticle 203 by which the later structures on a wafer 204 are determined, a wafer holder 205 for holding, moving, and exactly positioning the wafer 204, and an imaging unit, specifically a projection optical unit 206, with a plurality of optical elements, in particular lens elements 207, which are held by way of mounts 208 in a lens housing 209 of the projection optical unit 206.

[0316] As an alternative or in addition to the lens elements 207 illustrated, provision can be made of various refractive, diffractive, and / or reflective optical elements, inter alia also mirrors, prisms, terminating plates, and the like.

[0317] The basic functional principle of the DUV projection exposure apparatus 200 makes provision for the structures introduced into the reticle 203 to be imaged onto the wafer 204.

[0318] The illumination system 201 provides a projection beam 210 in the form of electromagnetic radiation, which is required for the imaging of the reticle 203 onto the wafer 204. The source used for this radiation may be a laser, a plasma source, or the like. The radiation is shaped in the illumination system 201 by means of optical elements such that the projection beam 210 has the desired properties with regard to diameter, polarization, shape of the wavefront, and the like when it is incident on the reticle 203.

[0319] An image of the reticle 203 is created by means of the projection beam 210 and transferred from the projection optical unit 206 onto the wafer 204 in an appropriately reduced form. In this case, the reticle 203 and the wafer 204 can be moved synchronously, so that regions of the reticle 203 are imaged onto corresponding regions of the wafer 204 virtually continuously during what is called a scanning operation.

[0320] An air gap between the last lens element 207 and the wafer 204 can optionally be replaced by a liquid medium which has a refractive index of greater than 1.0. The liquid medium can be high-purity water, for example. Such a set-up is also referred to as immersion lithography and has an increased photolithographic resolution.

[0321] The use of the invention is not restricted to use in projection exposure apparatuses 100, 200, in particular also not with the described set-up. The invention is suitable for any desired lithography systems or microlithography systems, but in particular for projection exposure apparatuses having the described setup. The invention is also suitable for EUV projection exposure apparatuses which have a smaller image- side numerical aperture than those described in the context of Figure 1 , and have no obscured mirror M5 and / or M6. In particular, the invention is also suitable for EUV projection exposure apparatuses which have an image-side numerical aperture from 0.25 to 0.5, preferably 0.3 to 0.4, particularly preferably 0.33. The invention and the following exemplary embodiments should also not be understood as being restricted to a specific design.

[0322] The figures that follow illustrate the invention merely by way of example and in highly schematized form.

[0323] Figure 3 shows a schematic illustration of a possible embodiment of an apparatus 1 for checking a component 2.

[0324] The apparatus 1 serves to check the component 2 with a periodic structure 3, which comprises substructures 5 arranged on a lattice 4. The apparatus 1 comprises at least one measurement radiation source 6 for creating measurement radiation 7 and an optics system 8. The apparatus 1 also contains a mask device 10 for influencing a field distribution of the measurement radiation 7, the mask device 10 having a dual lattice 11 which is reciprocal to a target shape of the lattice 4.

[0325] Furthermore, the component 2, the measurement radiation source 6, the optics system 8 and the mask device 10 are configured and arrangeable in such a way that the measurement radiation 7 is diffracted at the lattice 4 in such a way that at least one of the Oth diffraction orders of the diffracted measurement radiation 7 is at least approximately coinciding with at least one of the points of the dual lattice 11.

[0326] Preferably, the component 2, the measurement radiation source 6, the optics system 8 and the mask device 10 can be arrangeable in such a way that the lattice 4, the measurement radiation 7 and the dual lattice 11 at least approximately mutually fulfil a Laue condition for the target shape of the lattice 4.

[0327] Preferably, the measurement radiation source 6 of the apparatus 1 is configured to create the measurement radiation 7 in such a way that a diffraction pattern of the target shape of the lattice 4 is at least approximately fully alignable with the dual lattice 11.

[0328] According to the exemplary embodiment shown in figure 3 the measurement radiation source 6 is configured to create the measurement radiation 7 in such a way that the measurement radiation 7 at an entry pupil of the optics system 8 has a pattern at least partially corresponding to the dual lattice 11.

[0329] To this end, the measurement radiation source 6 comprises a beam mask device 25 defining an entry pupil of the optics system 8 accordingly.

[0330] In the embodiment shown in Figure 3 the apparatus 1 comprises a camera device 9. By preference, the measurement radiation source 6 is configured to form a Kohler-type illumination of the component 2.

[0331] Further, a beam splitter device 6b for input coupling the measurement radiation 7 into the optics system 8 is preferably provided. A reflected light illumination of the component 2, as depicted in Figure 3, is advantageous for a component 2 to be examined which is not transmissive but instead reflective for the measurement radiation 7.

[0332] In the exemplary embodiment depicted in Figure 3, the optics system 8 preferably comprises at least one Fourier device 12 for performing the optical Fourier transform on the measurement radiation 7.

[0333] In the exemplary embodiment according to Figure 3, an arrangement device 13 is further preferably present and configured to accommodate the component 2 in such a way that the periodic structure 3 is arranged in an object plane of the Fourier device 12.

[0334] In the exemplary embodiment depicted in Figure 3, the mask device 10 is preferably also arranged in a pupil plane of the Fourier device 12 reciprocal to the object plane.

[0335] In the exemplary embodiment of the apparatus 1 according to Figure 3, the Fourier device 12 preferably comprises a lens 14.

[0336] Further, the Fourier device 12 either has a first numerical aperture in order to check the entire periodic structure 3 perpendicular to the object plane along an optical axis of the measurement radiation 7 and a depth extent of the component 2.

[0337] Alternatively, the Fourier device 12 has a second numerical aperture in order to check only a sectional region of the periodic structure 3 parallel to the object plane.

[0338] In this case, the first numerical aperture is preferably smaller than the second numerical aperture.

[0339] In order to change between different numerical apertures, the apparatus 1 in the exemplary embodiment according to Figure 3 preferably provides for the Fourier device 12 to comprise an aperture stop 15 which is configured to set the numerical aperture of the Fourier device 12.

[0340] At a given time, the Fourier device 12 has either the first or the second numerical aperture. However, the aperture stop 15 allows simple switching between the numerical apertures at different times.

[0341] In the exemplary embodiment of the apparatus 1 depicted in Figure 3, a holding device 16 is preferably provided and configured to displace the mask device 10 in the pupil plane, preferably in both spatial directions of the pupil plane. In Figure 3, the displaceability is epitomized by a double-headed arrow. The exemplary embodiment of the apparatus 1 depicted in Figure 3 also contains an imaging device 17 for imaging the measurement radiation 7 onto the camera device 9. In the exemplary embodiment, the imaging device 17 is embodied as part of the optics system 8.

[0342] In the exemplary embodiment according to Figure 3, the Fourier device 12 preferably comprises a zoom optical unit 12b.

[0343] In the exemplary embodiment depicted in Figure 3, the measurement radiation source 6 is preferably configured to create measurement radiation 7 at different wavelengths. In an alternative or in addition, provision can be made for the measurement radiation 7 to be infrared radiation.

[0344] Alternatively, the beam splitter device 6a can also be arranged between the component 2 and the zoom optical unit 12b.

[0345] By preference, the dual lattice 11 is designed as a reciprocal of a one-dimensional and / or two-dimensional target shape of the lattice 4.

[0346] The mask device 10 is preferably partly or completely formed as a phase mask device 10a for influencing a phase angle of the field distribution of the measurement radiation 10.

[0347] The mask device 10 is partly or completely formed as an amplitude mask device 10b for influencing an amplitude of the field distribution of the measurement radiation 7.

[0348] In particular, the mask device 10 is partly or completely formed as combination of the phase mask device 10a for influencing the phase angle of the field distribution of the measurement radiation 7 and an amplitude mask device 10b for influencing an amplitude of the field distribution of the measurement radiation 7.

[0349] Figure 4 shows a schematic illustration of a possible embodiment of the mask device 10.

[0350] In the exemplary embodiment depicted in Figure 4, the mask device 10 preferably comprises dual substructures 18 arranged on the dual lattice 11.

[0351] In the exemplary embodiment depicted in Figure 4, the lattice 4 has lattice vectors 4a, 4b. The dual lattice 11 has dual lattice vectors 11a, 11b.

[0352] Further, in Figure 4, the effect of a Fourier transform is epitomized by an arrow 12a.

[0353] Up to scaling, the dual lattice 11 or G* reciprocal to the lattice 4 or G is given by the inverse. Thus, the following applies: GG* = 2 ir E, where E is an identity matrix. In the case of one-dimensional phase lattices, G and G* in particular are reciprocal lattice constants. Alternatively, GG* can also be an integer multiple of 2 TT E.

[0354] Further, in the exemplary embodiment of the mask device 10 according to Figure 4, the dual substructures 18 are preferably at least approximately circular.

[0355] Moreover, away from the dual substructures 18, i.e. in a complement of the dual substructures 18, the phase mask device 10a in the exemplary embodiment according to Figure 4 brings about a phase offset of the measurement radiation 7 of half a wavelength of the measurement radiation 7 vis-a-vis the dual substructures 18.

[0356] Furthermore, the dual substructures 18 are preferably at least partly absorbing the measurement radiation 7. Therefore, the dual substructure 18 can contribute to form the amplitude mask device 10b.

[0357] In particular, the amplitude device 10b is preferably formed by a coating on a substrate.

[0358] In the exemplary embodiments according to Figures 3 and 4, the phase mask device 10a is preferably formed by an etched structuring of a half-wavelength coating (A / 2) on a transmissive substrate.

[0359] Preferably the substrates for the amplitude mask device 10b and the phase mask device 10a are identical to form the combined mask device 10.

[0360] In an exemplary embodiment (not depicted), provision is preferably made for the mask device 10 to be designed to be digitally actuatable and / or transmittive or transmissive and / or reflective and / or as a microelectronic mechanical system and / or as a spatial light modulator (SLM), in particular as a liquid crystal on silicon SLM (LCOS-SLM) and / or as a spatial optical phase modulator.

[0361] Figure 5 shows a block diagram-type illustration of a possible embodiment of a method for checking the component 2.

[0362] In the method for checking the component 2 with the periodic structure 3, which has substructures 5 arranged on the lattice 4, the measurement radiation source 6 for creating the measurement radiation 7 is used in a creation block 30. The optics system 8 and, preferably, the camera device 9 are also used. In a deviation block 31 , a respective deviation of the substructures 5 from a single reference substructure is ascertained by interferometry.

[0363] In the exemplary embodiment depicted in Figure 5, an averaging block 32 is preferably provided, in which the reference structure is ascertained by periodic averaging of the periodic structure 3. Within the scope of the averaging block 32, periodic averaging is preferably performed by overlaying a diffraction image 19 (see Figure 2) of the periodic structure 3 with the mask device 10 within the scope of an overlay block 33.

[0364] Within the scope of the overlay block 33, the measurement radiation 7 is preferably influenced by the mask device 10 by virtue of the field distribution of the measurement radiation 7 within the preferably circular dual substructures 18 on the dual lattice 11 which is reciprocal to the target shape of the lattice 4.

[0365] The dual substructures are offset by half a wavelength of the measurement radiation 7 vis-a-vis a complement of the dual substructures 18 on the phase mask device 10a.

[0366] The optics system 8 and the camera device 9 are used in an imaging block 34.

[0367] Within the scope of the imaging block 34, an intensity pattern of the measurement radiation 7 on the camera device 9 is preferably ascertained by virtue of the measurement radiation 7 being imaged on the camera device 9 by the imaging device 17 following the overlay of the diffraction image 19 of the periodic structure 3 with the mask device 10.

[0368] Within the scope of the overlay block 33, the diffraction image 19 of the periodic structure 3 and the mask device 10 are preferably overlaid in the pupil plane of the Fourier device 12.

[0369] Within the scope of the imaging block 34, a plurality of interferograms is preferably also recorded, with the mask device 10 being displaced to another location in the pupil plane within the scope of the overlay block 33 for each interferogram.

[0370] By preference, different wavelengths of the measurement radiation 7 are used as part of the creation block 30, with the dual lattice 11 preferably being scaled within the scope of a scaling block 35 in a manner dependent on the employed wavelength of the measurement radiation 7.

[0371] Within the scope of the scaling block 35, the scaling of the dual lattice 11 is preferably brought about by changing the mask device 10.

[0372] As an alternative or in addition, the scaling of the dual lattice 11 within the scope of the scaling block 35 is preferably brought about by virtue of a focal length of the Fourier device 12 being varied by the zoom optical unit 12b.

[0373] In the process, a pupil size and / or an illumination region of the mask device 10 is preferably varied. Within the scope of the deviation block 31 , the component 2 is preferably additionally checked using a method for measuring an optically critical dimension, the intensity split of which is simulated with the aid of a parameterized model of the component 2.

[0374] Within the scope of the overlay block 33, the dual lattice 11 is preferably designed as a reciprocal of a onedimensional and / or two-dimensional target shape of the lattice 4.

[0375] Further, in the case of the exemplary embodiment of the method depicted in Figure 5, a NAND memory chip 20 (see Figure 6) with periodically arranged through holes or vias 21 is preferably checked as component 2.

[0376] The measurement radiation source 6 is preferably configured to create the measurement radiation 7 in such a way that the measurement radiation 7 at the entry pupil of the optics system 8 has a pattern at least partially corresponding to the dual lattice 11.

[0377] Figure 6 shows a schematic illustration of a possible embodiment of a NAND memory chip 20 to be checked.

[0378] In Figure 6, the component 2 to be checked by the above-described method and the above-described apparatus 1 is presently given by the NAND memory chip 20 to be checked. The periodic structure 3 is given by the vias 21.

[0379] In the example depicted in Figure 6, the vias 21 are arranged on the lattice 4 and have a cross section representing the substructure 5. In the present example, the cross section representing the substructure 5 has a circular embodiment.

[0380] The NAND memory chip 20 depicted in Figure 6 is realized in a 3-D construction by etching and / or coating periodically arranged vias 21 at deep, i.e. multiple bilayer stacks 22.

[0381] By means of a suitable setting of the NA of the Fourier device 12, the vias 21 can be checked along their depth extent either in averaged fashion in the case of a small NA of the lens 14 or in sections in the case of a large NA.

[0382] Figures 1 and 2 each show a lithography system, in particular a projection exposure apparatus 100, 200 for semiconductor lithography, having an illumination system 101 , 201 with a radiation source 102 and an optical unit 103, 109, 206 which comprises at least one optical element 116, 118, 119, 120, 121 , 122, Mi, 207. The apparatus 1 for checking a component 2, in particular for checking the semiconductor component, is present in the projection exposure apparatuses 100, 200 depicted in Figures 1 and 2. In an alternative or in addition, the projection exposure apparatuses 100, 200 depicted in Figures 1 and 2 are configured to perform the method for checking the component 2, in particular for checking the semiconductor component, described in the context of Figure 5.

[0383] The invention is particularly suitable for the projection exposure apparatuses 100, 200 depicted in Figures 1 and 2, provided these are configured to produce and check a semiconductor component embodied as NAND memory chip 20 with the periodically arranged vias 21.

[0384] In the exemplary embodiments depicted in Figures 1 and 2, the apparatus 1 for checking the semiconductor component is preferably spatially separate from the location of the exposure of the semiconductor component. Further, the method for checking the semiconductor component to be produced by the projection exposure apparatuses 100, 200 in each case is preferably performed spatially separate from the location of the exposure of the semiconductor component.

[0385] In a possible embodiment, the optical units of the projection exposure apparatuses 100, 200 can also be incorporated in the apparatus 1.

[0386] Preferably, the apparatus 1 comprises a mixing device 23 that is particularly configured to disturb a temporal coherence of the measurement radiation 7 to prevent speckle patterns in a resulting interferogram.

[0387] Figure 7 shows a schematic representation of a possible embodiment of the mixing device 23.

[0388] The mixing device 23 is designed in the present case as part of the measurement radiation source 6.

[0389] The mixing device 23 preferably comprises a plurality of optical fibers 6c, the plurality of optical fibers 6c having different lengths.

[0390] In particular, the measurement radiation source 6 preferably has a pump source 6b and a plurality of optical fibers 6c, whereby the optical fibers 6c each have different lengths, so that in pairs there is a difference in length above a coherence length of the measurement radiation 7.

[0391] The measurement radiation 7 is decoupled from the optical fibers 6c directly at the Fourier device 12 and focused from there onto the component 2.

[0392] Figure 8 shows a further schematic illustration of a possible embodiment of the mixing device 23, also comprising optical fibers 6c.

[0393] In comparison to the representation shown in Figure 7, the Fourier device 12 is dispensed with in the representation shown in Figure 8 and the measurement radiation is coupled out of the optical fibers 6c directly at the component 2 to be measured. Again, in the embodiment example shown in Figure 8, the mixing device 23 has a plurality of optical fibers 6c, with the plurality of optical fibers 6c each having different lengths

[0394] Figure 9 shows a schematic illustration of a further possible embodiment of the mixing device 23.

[0395] In the embodiment example shown in Figure 9, the mixing device 23 comprises a diffuser element 24.

[0396] In the embodiment example shown in Figure 9, the measurement radiation 7 is formed by the measurement radiation source 6, which is preferably designed as a laser source.

[0397] In the embodiment example shown in Figure 9, the beam mask device 25 is arranged in front of the diffuser element 24.

[0398] By means of the beam mask device 25, illumination directions corresponding to the dual lattice 11 are first generated by diffraction of a plane wave of the measurement radiation 7 at the beam mask device 25.

[0399] The coherence of the illumination light 7 thus obtained is then disturbed by time averaging via the diffuser element 24, in particular a stochastically phase-shifting element.

[0400] The beam mask device 25 preferably has a grating, which can be designed as a phase grating and / or as an amplitude grating and / or as a combination of a phase grating and / or an amplitude grating.

[0401] In particular, the mask device 10 according to Figure 1 can alternatively or additionally be arranged in front of the diffuser element 25 and thus in an illumination pupil instead of an imaging pupil.

[0402] In the embodiment shown in Figure 9, a double passage through the beam mask device 25 can be provided when inspecting the component in a reflection configuration. In particular, it may be provided that the beam mask device 25 and / or the mask device 10 fulfills both a function of averaging the diffraction images and an illumination function according to the embodiment example shown in Figure 9.

[0403] Furthermore, it may be provided that further beam splitters, in particular polarization beam splitters, are present (not shown) in the embodiment example shown in Figure 9. This makes it possible to ensure that the diffuser element 24 is only included in an illumination path of the measurement beam 7 but not in an imaging path of the measurement beam 7. This can prevent poor quality imaging of the resulting interferogram.

[0404] Figure 10 shows a schematic representation of a further possible embodiment of the device 1 and in particular of the mixing device 23. In the embodiment example shown in Figure 10, the measurement radiation source 6 is preferably set up to form the measurement radiation 7 in such a way that a wavelength spectrum of the measurement radiation 7 comprises a band of wavelengths.

[0405] The light of the measurement radiation 7 is therefore not sharply monochromatic, but has a certain distribution of wavelengths or a wavelength spectrum of a certain width.

[0406] Furthermore, in the embodiment example shown in Figure 10, the mixing device 23 is designed as part of the Fourier device 12 and the measurement radiation source 6, wherein the at least one Fourier device 12 has a refractive power which is inversely proportional to the wavelengths of the measured radiation 7.

[0407] In the embodiment example of the device 1 shown in Figure 10, operation of the apparatus 1 and / or inspection of the component 2 is provided in a reflection configuration.

[0408] Furthermore, in the embodiment example shown in Figure 10, the mask device 10 fulfills both the function of averaging the diffraction images and the function of splitting the illumination radiation of the measurement radiation 7.

[0409] Figure 10 shows in particular such a reflective inspection optic of the apparatus 1 schematically for two wavelengths and three field points on the component 2. In the design example shown in Figure 10, a shorter wavelength from the wavelength spectrum of the measurement radiation 7 is shown in solid lines and a longer wavelength in dashed lines.

[0410] It can be seen that the field points can be imaged sharply, while in a beam path between the mask device 10 and the field points a splitting by wavelength takes place.

[0411] Subsequent imaging on the camera device 9 can in turn be performed with the polychromatic measurement radiation 7, whereby undesirable interference or speckle effects can be suppressed. List of reference signs

[0412] 1 Apparatus

[0413] 2 Component

[0414] 3 Periodic structure

[0415] 4 Lattice

[0416] 4a, b Lattice vector

[0417] 5 Substructure

[0418] 6 Measurement radiation source 6a Beam splitter device

[0419] 6b Pump source

[0420] 6c Optical Fiber

[0421] 7 Measurement radiation

[0422] 8 Optics system

[0423] 9 Camera device

[0424] 10 Mask device

[0425] 11 Dual lattice

[0426] 11 a,b Dual lattice vector

[0427] 12 Fourier device

[0428] 12a Arrow

[0429] 12b Zoom optical unit

[0430] 13 Arrangement device

[0431] 14 Lens

[0432] 15 Aperture stop

[0433] 16 Holding device

[0434] 17 Imaging device

[0435] 18 Dual substructure

[0436] 19 Diffraction image

[0437] 20 NAND memory chip

[0438] 21 Via

[0439] 22 Bi layer stack

[0440] 23 Mixing device

[0441] 24 Diffuser element

[0442] 25 Beam mask device

[0443] 30 Creation block

[0444] 31 Deviation block

[0445] 32 Averaging block

[0446] 33 Overlay block

[0447] 34 Imaging block 35 Scaling block

[0448] 100 EUV projection exposure apparatus 101 Illumination system

[0449] 102 Radiation source

[0450] 103 Illumination optical unit

[0451] 104 Object field

[0452] 105 Object plane

[0453] 106 Reticle

[0454] 107 Reticle holder

[0455] 108 Reticle displacement drive

[0456] 109 Projection optical unit

[0457] 110 Image field

[0458] 111 Image plane

[0459] 112 Wafer

[0460] 113 Wafer holder

[0461] 114 Wafer displacement drive

[0462] 115 EUV / used / illumination radiation

[0463] 116 Collector

[0464] 117 Intermediate focal plane

[0465] 118 Deflection mirror

[0466] 119 First facet mirror / field facet mirror 120 First facets / field facets

[0467] 121 Second facet mirror / pupil facet mirror 122 Second facets / pupil facets

[0468] 200 DUV projection exposure apparatus 201 Illumination system

[0469] 202 Reticle stage

[0470] 203 Reticle

[0471] 204 Wafer

[0472] 205 Wafer holder

[0473] 206 Projection optical unit

[0474] 207 Lens element

[0475] 208 Mount

[0476] 209 Lens housing

[0477] 210 Projection beam

[0478] Mi Mirrors

Claims

Claims:

1. Apparatus (1) for checking a component (2) with a periodic structure (3) having substructures (5) arranged on a lattice (4), at least comprising a measurement radiation source (6) for creating measurement radiation (7) and an optics system (8),characterized in thatthe apparatus (1) comprises a mask device (10) for influencing a field distribution of the measurement radiation (7), the mask device (10) having a dual lattice (11) which is reciprocal to a target shape of the lattice (4), whereinthe component (2), the measurement radiation source (6), the optics system (8) and the mask device (10) are configured and arrangeable in such a way that the measurement radiation (7) is diffracted at the lattice (4) in such a way that at least one of the 0thdiffraction orders of the diffracted measurement radiation (7) is at least approximately coinciding with at least one of the points of the dual lattice (11).

2. Apparatus (1) according to Claim 1 ,characterized in thatthe measurement radiation source (6) is configured to create the measurement radiation (7) in such a way that a diffraction pattern of the target shape of the lattice (4) is at least approximately fully alignable with the dual lattice (11).

3. Apparatus (1) according to Claim 1 or 2,characterized in thatthe measurement radiation source (6) is configured to create the measurement radiation (7) in such a way that the measurement radiation (7) at an entry pupil of the optics system (8) has a pattern at least partially corresponding to the dual lattice (11).

4. Apparatus (1) according to any of Claims 1 to 3,characterized in thatthe apparatus (1) comprises a camera device (9).

5. Apparatus (1) according to any of Claims 1 to 4,characterized in thatthe apparatus (1) comprises a mixing device (23).

6. Apparatus (1) according to Claim 5,characterized in thatthe mixing device (23) comprises a plurality of optical fibers (6c), the plurality of optical fibers (6c) having different lengths.

7. Apparatus (1) according to Claim 5 or 6,characterized in thatthe mixing device (23) comprises a diffuser element (24).

8. Apparatus (1) according to any of Claims 1 to 7,characterized in thatthe measurement radiation source (6) is configured to create the measurement radiation (7) in such a way that a wavelength spectrum of the measurement radiation (7) contains a band of wavelengths.

9. Apparatus (1) according to any of Claims 1 to 8,characterized in thatthe mask device (10) is partly or completely formed as a phase mask device (10a) for influencing a phase angle of the field distribution of the measurement radiation (7).

10. Apparatus (1) according to any of Claims 1 to 9,characterized in thatthe mask device (10) is partly or completely formed as an amplitude mask device (10b) for influencing an amplitude of the field distribution of the measurement radiation (7).

11. Apparatus (1) according to any of Claims 1 to 10,characterized in thatthe mask device (10) is partly or completely formed as combination of a phase mask device (10a) for influencing a phase angle of the field distribution of the measurement radiation (7) and an amplitude mask device (10b) for influencing an amplitude of the field distribution of the measurement radiation (7).

12. Apparatus (1) according to any of Claims 1 to 11,characterized in thatthe mask device (10) has dual substructures (18) arranged on the dual lattice (11).

13. Apparatus (1) according to Claim 12,characterized in thatthe dual substructures (18) are at least approximately circular.

14. Apparatus (1) according to Claim 12 or 13,characterized in thatthe dual substructures (18) are at least partly absorbing the measurement radiation (7).

15. Apparatus (1) according to any of Claims 12 to 14,characterized in thatthe phase mask device (10a) brings about, away from the dual substructures (18), a phase offset of the measurement radiation (7) of half a wavelength of the measurement radiation (7) vis-a-vis a complement of the dual substructures (18) on the phase mask device (10a).

16. Apparatus (1) according to any of Claims 1 to 15,characterized in thatthe optics system (8) comprises at least one Fourier device (12) for performing the optical Fourier transform on the measurement radiation (7).

17. Apparatus (1) according to Claim 16,characterized in thatan arrangement device (13) is provided and configured to accommodate the component (2) in such a way that the periodic structure (3) is arranged in an object plane of the Fourier device (12).

18. Apparatus (1) according to Claim 16 or 17,characterized in thatthe mask device (10) is arranged in a pupil plane of the Fourier device (12) which is reciprocal to the object plane.

19. Apparatus (1) according to any of Claims 16 to 18,characterized in thatthe Fourier device (12) comprises a lens (14) and eitherhas a first numerical aperture in order to check the entire periodic structure (3) perpendicularly to the object plane orhas a second numerical aperture in order to check only a sectional region of the periodic structure (3) parallel to the object plane.

20. Apparatus (1) according to Claim 19,characterized in thatthe Fourier device (12) comprises an aperture stop (15) which is configured to set the numerical aperture of the Fourier device (12).

21. Apparatus (1) according to any of Claims 5 to 20,characterized in thatthe mixing device (23) is formed as a part of the at least one Fourier device (12), wherein the at least one Fourier device (12) comprises a refractive power, the refractive power being proportional to the wavelengths of the measurement radiation (7).

22. Apparatus (1) according to any of Claims 18 to 21 ,characterized in thata holding device (16) is provided and configured to displace the mask device (10) in the pupil plane, preferably in both spatial directions of the pupil plane.

23. Apparatus (1) according to any of Claims 9 to 22,characterized in thatthe phase mask device (10a) is formed by an etched structuring of a half wavelength coating on a transmissive substrate.

24. Apparatus (1) according to any of Claims 10 to 23,characterized in thatthe amplitude mask device (10b) is formed by a coating on a substrate.

25. Apparatus (1) according to any of Claims 1 to 24,characterized in thatthe mask device (10) is designed to be digitally actuatable and / or transmissive and / or reflective and / or as a microelectronic mechanical system and / or as a spatial light modulator (SLM), in particular as a liquid crystal on silicon SLM (LCOS-SLM) and / or as a spatial optical phase modulator.

26. Apparatus (1) according to any of Claims 1 to 25,characterized in thatan imaging device (17) is provided for imaging the measurement radiation (7) on the camera device (9).

27. Apparatus (1) according to any of Claims 16 to 26,characterized in thatthe Fourier device (12) comprises a zoom optical unit (12b).

28. Apparatus (1) according to any of Claims 1 to 27,characterized in thatthe measurement radiation source (6) is configured to create measurement radiation (7) at different wavelengths and / orthe measurement radiation (7) is infrared radiation.

29. Apparatus (10) according to any of Claims 1 to 28,characterized in thatthe dual lattice (11) is designed as a reciprocal of a one-dimensional and / or two-dimensional target shape of the lattice (4).

30. Method for checking a component (2) with a periodic structure (3) having substructures (5) arranged on a lattice (4), with use being made of at least one measurement radiation source (6) for creating measurement radiation (7) and an optics system (8),characterized in thata respective deviation of the substructures (5) from a single reference substructure is ascertained by interferometry.

31. Method according to Claim 30,characterized in thatthe reference substructure is ascertained by periodic averaging of the periodic structure (3).

32. Method according to Claim 31 ,characterized in thatthe periodic averaging is performed by overlaying a diffraction image (19) of the periodic structure (3) with a mask device (10).

33. Method according to Claim 32,characterized in thatthe measurement radiation (7) is influenced by the mask device (10) by virtue of a field distribution of the measurement radiation (7) within, preferably circular, dual substructures (18) on a dual lattice (11) which is reciprocal to a target shape of the lattice (4).

34. Method according to any of Claims 30 to 33,characterized in thatthe measurement radiation source (6) is configured to create the measurement radiation (7) in such a way that the measurement radiation (7) at an entry pupil of the optics system (8) has a pattern at least partially corresponding to the dual lattice (11).

35. Method according to Claim 33 or 34,characterized in thatthe dual substructures (18) are offset by half a wavelength of the measurement radiation (7) vis-a- vis a complement of the dual substructures (18) on the mask device (10).

36. Method according to any of Claims 32 to 35,characterized in thatthe diffraction image (19) of the periodic structure (3) and the mask device (10) are overlaid in a pupil plane of a Fourier device (12).

37. Method according to Claim 36,characterized in thata focal length of the Fourier device (12) is varied by a zoom optical unit (12b).

38. Method according to any of Claims 30 to 37,characterized in thata plurality of interferograms is recorded, with the mask device (10) being displaced to a different location in the pupil plane for each interferogram.

39. Method according to any of Claims 33 to 38,characterized in thatdifferent wavelengths of the measurement radiation (7) are used, with preferably the dual lattice (11) being scaled in accordance with the wavelength of the measurement radiation (7) used.

40. Method according to Claim 39,characterized in thatthe scaling of the dual lattice (11)is brought about by a change of the mask device (10) and / oris brought about by the Fourier device (12) which preferably comprises a zoom optical unit (12b), with a pupil size and / or an illumination region of the mask device (10) being varied.

41. Method according to any of Claims 30 to 40,characterized in thatthe component (2) is additionally checked using a method for measuring an optically critical dimension, the intensity distribution of which is simulated with the aid of a parameterized model of the component (2).

42. Method according to any of Claims 30 to 41 ,characterized in thata NAND memory chip (20) with periodically arranged vias (21) is checked as the component (2).

43. Method according to any of Claims 33 to 42,characterized in thatthe dual lattice (11) is designed as a reciprocal of a one-dimensional and / or two-dimensional target shape of the lattice (4).

44. Lithography system, in particular projection exposure apparatus (100, 200) for producing a semiconductor component, having an illumination system (101 , 201) with a radiation source (102) and an optical unit (103, 109, 206) which comprises at least one optical element (116, 118, 119, 120, 121 , 122, Mi, 207),characterized in thatan apparatus (1) is provided for checking a component (2) according to any of Claims 1 to 29, in particular for checking the semiconductor component, and / orthe lithography system is configured to perform a method for checking a component (2) according to any of Claims 30 to 43, in particular for checking the semiconductor component.

45. Lithography system according to Claim 44, configured to produce and check a semiconductor component designed as a NAND memory chip (20) with periodically arranged vias (21).

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