Method for examining a blank of a microlithographic photomask

Abstract

A method for inspecting a blank plate (100) of a photomask includes the following steps: a) placing the blank plate (S1) on a first support platform of a first inspection device (102) such that a first edge (106) and a second edge (108) of the blank plate rest against stops (116, 118, 120) of the first support platform (114); b) determining (S2) an inspection position (B) on the blank plate in a first coordinate system (128) by means of the first inspection device; c) placing the blank plate (S3) on a platform having a On the second stage (136) of the second inspection device (126) of the image recording unit (150); d) using the image recording unit to record (S4) at least one image (152, 154, 156) of the blank plate, such that at least part of the first edge and the second edge are obtained; and e) determining (S5) a conversion rule based on the first edge and the second edge obtained in the at least one image to convert the inspection position obtained in the first coordinate system into a second coordinate system (142) of the second inspection device.

Description

Method for inspecting blank plates of lithography masks The present invention relates to a method for inspecting a blank plate of a lithography mask. The content of the priority application DE 10 2023 130 586.7 is incorporated herein by reference in its entirety. Lithography is used to create microstructured components, such as integrated circuits. The lithography process is performed using a lithography apparatus equipped with an illumination system and a projection system. An image of a mask (a photomask or lithography mask) illuminated by the illumination system is projected through the projection system onto a substrate (such as a silicon wafer) coated with a photosensitive layer (photoresist) positioned in the image plane of the projection system, transferring the mask structure to the substrate's photosensitive coating. The mask blank is processed so that it has a corresponding mask structure. The generated mask structure is projected onto the substrate at a reduced scale. The mask structure itself is already very small and has dimensions, for example, of the order of a few micrometers to a few nanometers. In order to use lithography to generate microstructure components very accurately, the lithography mask structure must also be manufactured very accurately and the mask must be free of defects (e.g. defective structures and contaminants). Defect-free lithography masks are also very important because lithography masks are usually used for multiple exposures. Therefore, it is costly to inspect lithography masks for defects. Then, attempts are made to repair the identified defective structures or to remove contaminants. The defects can also be very small and have dimensions, for example, of the order of a few nanometers. Therefore, work on lithography masks and lithography mask blank inspection should be performed with high spatial resolution and precision. In this context, an object of the present invention is to provide an improved method for inspecting blanks of lithography masks. Therefore, a method for inspecting a lithography mask blank is provided. The method comprises the following steps: a) placing the blank on a first loading platform of a first inspection apparatus such that a first edge and a second edge of the blank rest against a stopper of the first loading platform; b) determining an inspection position on the blank in a first coordinate system using the first inspection apparatus; c) placing the blank on a second loading platform of a second inspection apparatus having an image recording unit; d) recording at least one image of the blank using the image recording unit such that at least a portion of the first edge and the second edge are captured; and e) determining a conversion rule based on the first edge and the second edge captured in the at least one image to convert the inspection position obtained in the first coordinate system into a second coordinate system of the second inspection apparatus. In inspecting a mask blank, the proposed method allows the use of two different inspection devices (i.e., first and second inspection devices) with different coordinate systems (i.e., first and second coordinate systems). For example, the mask blank may not have any structure, such as markings, for reproducibly positioning the mask blank on the carriers of the two inspection devices (i.e., first and second carriers). If there are no structures or markings (alignment marks) for reproducible mask placement, or if such structures or markings are not used, the proposed method allows the first and second edges of the mask blank to rest against the first carrier stop in the first carrier of the first inspection device. Furthermore, when the mask blank is positioned in the second carrier of the second inspection device, the positions of the first and second edges of the mask blank can be determined through image processing. This can then be used to determine the conversion rules for converting spatial coordinates from the first coordinate system to the second coordinate system. Thus, the inspection position (e.g., defect location) on the mask blank determined by the first inspection device can be converted to the second coordinate system of the second inspection device. Thus, the examination position determined by means of the first examination device can be further examined by a second examination device (eg with a higher spatial resolution than the first examination device). Furthermore, the first and second edges of the blank that abut the stopper of the first inspection device can be any desired edges of the blank. Furthermore, the second inspection device can also include multiple stoppers for abutting the edges of the blank. The proposed method does not require that the stopper of the second inspection device abut the same edge and / or the same position on the corresponding edge as the stopper of the first inspection device. The blank plate is a blank plate of a lithography mask, for example, the blank plate is a blank plate of a transmission lithography mask for deep ultraviolet (DUV) lithography (working light wavelength is in the range of 30-250 nm) or a blank plate of a reflective lithography mask for extreme ultraviolet (EUV) lithography (working light wavelength is in the range of 0.1-30 nm, especially 13.5 nm). The blank plate includes, for example, a substrate. For example, the substrate includes silicon dioxide (SiO 2), for example quartz glass and / or an alternating sequence of molybdenum and silicon layers. For example, the blank typically does not include any structures that are projected onto the substrate during the lithography process (e.g., no absorbing material structures or phase-shifting structures). In particular, the blank also does not include a plurality of marks (alignment marks) that are used to reproducibly position the blank in the carrier of one or more inspection devices. For example, the blank's outer dimensions fall within a predetermined tolerance range. For example, according to international standards for DUV lithography masks and / or EUV lithography masks, the blank's outer dimensions fall within predetermined tolerances. For example, international standards for DUV lithography masks and / or EUV lithography masks include the international standard "SEMI P1" (e.g., SEMI P1 2008 Edition, July 2008) and / or the international standard "SEMI P37" (Specification for Extreme Ultraviolet Lithography Substrates and Blanks). Purely by way of example, the width and length tolerance range for a 6-inch blank according to the "SEMI P1" standard is + / - 400 µm. For example, the first inspection device is configured to identify one or more blank defects, such as contaminants. For example, the first inspection device is configured to establish a series of determined locations for the identified defects. In this case, the inspection locations determined in step b) are, for example, the locations of the identified defects. For example, the first inspection device has a spatial resolution in the range of 0.5 μm to 25 μm. The first inspection device includes an image recording device with a spatial resolution in the range of 0.5 μm to 25 μm. Alternatively or additionally, the first inspection device may also be configured to detect blank defects, for example, by light scattering. In this case, the spatial resolution of the first inspection device may also be better than 0.5 μm, for example, 100 nm or better and / or 50 nm or better. For example, in addition to the stops configured to abut the first and second edges of the blank, the first support platform may include one or more elastic elements under tension. For example, the one or more elastic elements press the blank against the stops of the first support platform. For example, in step a), a first elastic element under tension is disposed on a third edge of the blank opposite the first edge. For example, a second elastic element under tension is disposed on a fourth edge of the blank opposite the second edge. For example, the blank plate includes a main extension plane. Furthermore, the first edge and the second edge of the blank plate are arranged on the main extension plane. Specifically, the first edge and the second edge of the blank plate are at an angle to each other, such as (for example, substantially) perpendicular to each other. For example, the first edge and the second edge are adjacent edges. If the blank plate includes rounded corners and / or chamfers, the rounded corners and / or chamfers are, for example, arranged only between the first edge and the second edge. Specifically, the first coordinate system is the coordinate system of the first inspection device. For example, both the first coordinate system and the second coordinate system are right-handed Cartesian coordinate systems. For example, both the first coordinate system and the second coordinate system are two-dimensional coordinate systems. For example, both the first coordinate system and the second coordinate system have horizontal and vertical axes that are perpendicular to each other. In step b), a plurality of inspection positions on the blank can also be determined in the first coordinate system by means of the first inspection device. For example, in step b), one or more inspection positions on the surface of the blank can be determined. Specifically, the second inspection apparatus includes an image recording unit. For example, the second supporting platform of the second inspection apparatus may also include one or more stoppers for abutting against the first edge, the second edge, the third edge (e.g., disposed opposite the first edge), and / or the fourth edge (e.g., disposed opposite the first edge). The proposed method makes it possible to perform an accurate coordinate conversion from the first coordinate system to the second coordinate system, for example, even if the stop elements of the second carrier table abut against different edges of the blank (for example, the third and fourth edges) instead of the stop elements of the first carrier table abutting against the first and second edges of the blank. Determining a transformation rule based on the first edge and the second edge obtained in the at least one image allows, in particular, determining the position of the first edge and the second edge obtained in the at least one image in a second coordinate system of the second inspection device. For example, step e) of the method comprises determining the positions of the first and second edges in the first and second coordinate systems based on image processing of the at least one image. For example, the transformation rule is a mathematical transformation rule. For example, the transformation rule includes a transformation matrix and / or an affine transformation matrix. For example, the transformation rule includes a rotation via a rotation angle and / or a translation using a translation vector. The transformation rule is used, for example, for a two-dimensional coordinate transformation between a first and a second coordinate system. For example, the transformation rule is used to perform a basic transformation between the first and second coordinate systems. According to one embodiment, the second inspection apparatus includes a scanning microscope apparatus, a scanning electron microscope apparatus, a scanning probe microscope apparatus, and / or an atomic force microscope apparatus. For example, a scanning microscope, scanning electron microscope, scanning probe microscope, and / or atomic force microscope can be configured to record at least one image of the blank. This allows for recording the at least one image of the blank with high spatial resolution, wherein at least a portion of the first edge and the second edge are captured. Consequently, the positions of the first edge and the second edge (and / or the positions of various reference points on the first edge and the second edge) can be more accurately determined, thereby enabling more accurate coordinate conversion using the conversion rule. Specifically, the scanning microscope device includes a scanning electron microscope (SEM), a scanning probe microscope (SPM), an atomic force microscope (AFM) and / or a scanning tunneling microscope (STM). According to a further embodiment, the spatial resolution of the image recording unit of the second inspection device is 100 μm or better, 50 μm or better, 30 μm or better, 10 μm or better, 5 μm or better, 1 μm or better, 0.1 μm or better, 50 nm or better, 10 nm or better, 5 nm or better and / or 3 nm or better. The higher the spatial resolution used to record the at least one image, the more accurately the positions of the first and second edges (and / or the positions of reference points on the first and second edges) can be determined by image processing, and thus the transformation rule can be determined more accurately. According to another embodiment, the method inspects the blank for one or more defects. Furthermore, in step b), the position of at least one defect of the blank is determined in the first coordinate system using a first inspection device. Furthermore, a conversion rule is determined for converting the at least one defect position determined in the first coordinate system into a position in the second coordinate system. Thus, the location of one or more defects in the blank can be determined by the first inspection device. For example, a list of the locations of defects in the blank can be created by the first inspection device. For example, the location of one or more defects in the blank, or the list of locations of defects in the blank, determined by the first inspection device can be transmitted to the second inspection device. Since the one or more defect locations determined by the first inspection device have been converted into the second coordinate system of the second inspection device by the conversion rule, the one or more defects can be more easily found by the second inspection device. Furthermore, based on the data sent by the first inspection device, one or more defects can be inspected more accurately (eg, with a higher resolution) with the aid of the second inspection device. According to another embodiment of the invention, the method comprises after step e): recording at least one image of the at least one defect using an image recording unit of a second inspection device, wherein the image recording unit is aligned based on the position of the at least one defect converted into the second coordinate system. For example, the image detail from the image recording unit is selected based on the position of the at least one defect, which position has been converted into the second coordinate system. For example, the position of the at least one defect converted into the second coordinate system is located at the center of the image detail. For example, the second inspection device may also be configured to remove defects (e.g., particles) from the surface of the blank. For example, the second inspection device may include a micromanipulator and / or nanomanipulator for moving and / or removing particles from the surface of the blank. According to another embodiment, the first support platform includes a first stop, a second stop, and a third stop. The blank is positioned on the first support platform such that the first edge abuts the first and second stops, and the second edge abuts the third stop. The blank's first, second, and third reference points are defined at the contact locations of the first, second, and third stops on the first and second edges. Furthermore, in step d), an image of the blank is recorded for each reference point, and the corresponding reference point is obtained in the image. Furthermore, a conversion rule is determined based on the first, second, and third reference points obtained in the recorded image. In other words, the positions of the first and second edges are determined based on the recorded images at three reference points, at which the three stops of the first inspection device come into contact. This is advantageous if the edges of the blank (e.g., the first and / or second edges) deviate from a straight line (e.g., depending on the resolution of the second inspection device). Thus, the conversion rule can be accurately determined even if the blank edges are not 100% straight (e.g., relative to the resolution of the second inspection device). Specifically, the contact positions of the first edge of the blank against the first and second stoppers of the first loading platform of the first inspection apparatus define the first and second reference points of the blank. Furthermore, the contact position of the second edge of the blank against the third stopper of the first loading platform defines the third reference point of the blank. For example, step e) of the method comprises determining, based on image processing of at least one image, the corresponding positions of in each case the first, second and third reference point in the first and second coordinate systems. According to another embodiment, the positions of the first and second reference points in the second coordinate system are determined based on image processing of the corresponding recorded images, and / or the position of the third reference point in the second coordinate system is determined based on image processing of the corresponding recorded images. For example, it is assumed that the first coordinate system of the first inspection device corresponds to the coordinate system of the blank. In other words, it is assumed that the blank is arranged on the first carrier in step a) without deviations relative to the first coordinate system of the first inspection device, or that such deviations are ignored for simplification purposes because they are initially unknown. According to another embodiment, the transformation rule comprises a rotation by a rotation angle and / or a translation by a translation vector. Furthermore, the rotation angle is determined based on the determined positions of the first and second reference points in the second coordinate system, and / or the vector components of the translation vector are determined based on the determined position of the third reference point in the second coordinate system and the determined position of the first or second reference point in the second coordinate system. For example, the first coordinate system of the first inspection device is twisted relative to the second coordinate system of the second inspection device by a rotation angle (e.g., counterclockwise). In other words, the angle between a line parallel to the first abscissa axis of the first coordinate system and a line parallel to the second abscissa axis of the second coordinate system corresponds to the rotation angle. The rotation angle can then be calculated based on the right triangle formed by the line parallel to the first abscissa axis and the line parallel to the second abscissa axis. For example, the oblique triangle is formed such that the length of the opposite side Δy of the right triangle is given by the distance between the ordinate positions of the first and second reference points in the second coordinate system. Furthermore, for example, the oblique triangle is formed such that the length of the adjacent side Δx of the right triangle is given by the distance between the abscissa positions of the first and second reference points in the second coordinate system. Furthermore, the length of the hypotenuse Δu of the oblique triangle is specifically given by the distance between the abscissa positions of the first and second reference points in the first coordinate system. Therefore, the length of the opposite side Δy of the right triangle is calculated based on the determined distance between the ordinate positions of the first reference point and the second reference point in the second coordinate system. Furthermore, if the rotation is assumed to be very small, then it can be assumed that the length of the adjacent side Δx of the right triangle is approximately the same as the length of the hypotenuse Δu of the right triangle. For example, the distance between the first reference point and the second reference point in the first coordinate system, i.e., the length of the hypotenuse Δu, can be determined based on the predetermined configuration data of the first inspection device. For example, the predetermined configuration data of the first inspection device includes the predetermined distance between the first stop and the second stop of the first carrier in the first inspection device. Furthermore, the first reference point of the blank plate corresponds to the first stop of the first carrier of the first inspection device. Furthermore, the second reference point of the blank plate corresponds to the second stop of the first inspection device. Therefore, based on the predetermined distance between the first stop and the second stop of the first carrier in the first inspection device, the distance between the first reference point and the second reference point of the blank plate in the first coordinate system is determined. Then, the rotation angle Θ is approximately given by the inverse tangent of the quotient of the opposite side Δy and the adjacent side Δx (the adjacent side is assumed to be approximately the same size as the hypotenuse Δu as above): Alternatively, the rotation angle Θ can be directly obtained by taking the arcsine of the quotient of the opposite side Δy and the hypotenuse Δu: The determined rotation angle Θ can then be used to calculate the distance Δx between the first reference point and the second reference point in the second coordinate system based on the cosine of the rotation Θ: Alternatively, the distance Δx between the first reference point and the second reference point in the second coordinate system may be calculated based on Pythagoras' theorem: Optionally, the calculation of the distance Δx between the first reference point and the second reference point in the second coordinate system may also be determined based on multiple iterations. In the next calculation step, the position of the first origin of the first coordinate system can then be determined in the second coordinate system. It is particularly useful if the first straight line connecting the first origin and the third reference point R3 is arranged perpendicular to the second straight line connecting the first and second reference points R1 and R2. In other words, the first vector V1 pointing from the first origin to the third reference point R3 is arranged perpendicular to the second vector V2 pointing from the first reference point R1 to the second reference point R2. Therefore, the scalar product of the first and second connecting vectors is zero: Furthermore, the parameter form of the second connecting straight line passing through the first reference point R1 and the second reference point R2 can be expressed such that each point on the second connecting straight line is assigned a parameter λ: If the parametric form of the second connecting straight line is substituted into the above equation together with the scalar product, the following equation is obtained: This equation can be solved for λ, and thus the parameter λ can be calculated. The parameter λ thus determined can now be inserted into the above-mentioned parametric form of the second connecting straight line to calculate the origin O. According to another embodiment, the transformation rule comprises a transformation matrix according to the following equation: , where u and v represent the coordinates of the position in the first coordinate system, x and y represent the coordinates of the position in the second coordinate system, Θ represents the rotation angle of the first coordinate system relative to the second coordinate system, and t x and t y represents a translation of the first coordinate system relative to the second coordinate system. Alternatively or additionally, the transformation rule comprises a rotation by a rotation angle satisfying the following equation: , where Θ represents the rotation angle of the first coordinate system relative to the second coordinate system, Δx represents the horizontal coordinate difference between the first reference point and the second reference point in the second coordinate system, and Δy represents the vertical coordinate difference between the first reference point and the second reference point in the second coordinate system. According to another specific embodiment, determining the conversion rule includes determining the coordinate origin of the first coordinate system based on the following conditions: the coordinate origin of the first coordinate system is located on a first straight line where the first reference point and the second reference point exist simultaneously, and the first straight line is perpendicular to a second straight line where the coordinate origin of the first coordinate system and the third reference point exist simultaneously. Therefore, even when the corners of the blank plate are rounded and / or chamfered, the coordinate origin of the first coordinate system can be determined. In various embodiments, steps a) to e) are repeatedly performed so that an average conversion rule can be determined. In various embodiments, steps a) through e) are repeated to accurately translate the coordinates for a plurality of different first inspection devices. Specifically, steps a) through e) are performed (at least once) for each of the plurality of different first inspection devices. For example, the plurality of different first inspection devices may differ in that their stoppers abut the blank at different contact positions. Thus, a plurality of different conversion rules are determined and then averaged. The determined average conversion rule can then be used for coordinate conversion, regardless of which of the plurality of first inspection devices is used. According to another embodiment of the present invention, the method includes before step a): placing a blank plate on a second loading platform of a second inspection device; and using the second inspection device to create a plurality of marks on the blank plate according to predetermined nominal positions of the second coordinate system. Furthermore, in step b), positions of the plurality of markers in the first coordinate system are determined by means of the first inspection device. Furthermore, in step e), a correction rule for correcting the transformation rule is determined based on deviations between the positions of the markers in the first coordinate system determined by means of the first inspection device and the nominal positions of the markers in the second coordinate system. Therefore, marks are created on the blank by the second inspection device (i.e., in the second coordinate system), and these created marks are detected by the first inspection device (i.e., in the first coordinate system). This can then be used to determine a conversion rule for converting the first coordinate system into the second coordinate system. This, in turn, allows for the determination of a correction rule for correcting the conversion rule determined based on the image representation of the first and second edges. For example, at least three marks are created on the blank plate by means of the second inspection device. According to a further embodiment, the plurality of marks are produced by particle beam induced deposition and / or etching and / or by embossing on a blank. For example, the second inspection apparatus includes a device for performing particle beam induced processing (e.g., deposition and / or etching) on ​​the blank. For example, the device for particle beam induced processing includes a particle beam supply unit for providing a particle beam (e.g., an electron beam or an ion beam). Furthermore, the device for particle beam induced processing includes, for example, a gas supply unit for providing process gases (e.g., deposition gas or etching gas). For example, the process gas may be a deposition gas and / or an etching gas. For example, the process gas may be a mixture of multiple gaseous components, i.e., a process gas mixture. For example, the process gas may be a mixture of multiple gaseous components, each of which has only a specific molecular type. In particular, alkyl compounds of main group elements, metals or transition elements are considered to be suitable as deposition gases for depositing or growing raised structures. Examples thereof include cyclopentadienyl (trimethyl) platinum (CpPtMe 3Me=CH 4) Methylcyclopentadienyl (trimethyl) platinum (MeCpPtMe 3) Tetramethyltin (SnMe 4) Trimethylgallium (GaMe 3) Ferrocene (Cp 2Fe), diaryl chromium (Ar 2Cryl) ​​compounds and main group elements, metals or transition elements, such as chromium hexacarbonyl (Cr(CO) 6) Molybdenum hexacarbonyl (Mo(CO) 6) Tungsten hexacarbonyl (W(CO) 6) Dicobalt octacarbonyl (Co 2(CO) 8) Triruthenium dodecacarbonyl (Ru 3(CO) 12 ), iron pentacarbonyl (Fe(CO) 5) and / or alkoxide compounds of main group elements, metals or transition elements, such as tetraethoxysilane (Si(OC 2H 5)4)Ti(OC 3H 7) 4) and / or halide compounds of main group elements, metals or transition elements, such as tungsten hexafluoride (WF 6) Tungsten hexachloride (WCl 6) Titanium tetrachloride (TiCl 4) Boron trifluoride (BCl 3) Silicon tetrachloride (SiCl 4) and / or complex elements with main group elements, metals or transition metals, such as copper bis(hexafluoroacetylacetonate) (Cu(C 5F 6HO 2) 2) Trifluoroacetylacetonate dimethylgold (Me 2Au(C 5F 3H 4O 2)) and / or organic compounds, such as carbon monoxide (CO), carbon dioxide (CO 2) Aliphatic compounds and / or aromatic hydrocarbons, etc. A deposition gas may also contain styrene, hexacarbonyl, ethylene, styrene, pyrene, hexadecane, formic acid, acrylic acid, propionic acid, and / or methyl methacrylate. For example, the etching gas may contain: xenon difluoride (XeF 2) Xenon dichloride (XeCl 2) Xenon tetrachloride (XeCl 4) Steam (H 2O), heavy water (D 2O), oxygen (O 2) Ozone (O 3) Ammonia (NH 3) Nitrosyl chloride (NOCl) and / or one of the following halides: XNO, XONO 2. X 2O, XO 2. X 2O 2. X 2O 4. X 2O 6, wherein X is a halide. Other etching gases for etching one or more deposited test structures are described in applicant's U.S. patent application Ser. No. 13 / 0103281. The process gas may include additional gases, such as oxidizing gases, such as hydrogen peroxide (H 2O 2) Nitrous oxide (N 2O), nitric oxide (NO), nitrogen dioxide (NO 2) Nitric acid (HNO 3) and other oxygen-containing gases and / or halides, such as chlorine (Cl 2), hydrogen chloride (HCl), hydrogen fluoride (HF), iodine (I 2) Hydrogen iodide (HI), bromine (Br 2) Hydrogen bromide (HBr), phosphorus trichloride (PCl 3) Phosphorus pentachloride (PCl 5) Phosphorus trifluoride (PF 3) and other halogen-containing gases, and / or reducing gases, such as hydrogen (H 2) Ammonia (NH 3) Methane (CH 4) and other hydrogen-containing gases. These additional gases can be used, for example, in etching processes, as buffer gases, as passivation media, etc. According to a further embodiment, the plurality of markings have a circular form and / or a diameter of 10 nm or more, 50 nm or more, 100 nm or more and / or 300 nm or more. If a circular marker is used, the first inspection device can more easily detect the marker and better determine its position. In particular, it can more easily determine the center of the marker. However, other shapes than circles may be used for the markings. A minimum size of 10 nm ensures that the mark can be detected by the first inspection device. Furthermore, the larger the mark, the better and more reliably it can be detected by the first inspection device. For example, the maximum size of a mark is 50 µm. According to another embodiment, a plurality of marks are created on the blank plate in a regular pattern and / or a regular grid or an irregular pattern. For example, a plurality of marks can be created in a regular or irregular pattern / grid that completely covers the blank surface. An example of a regular pattern is a regular grid with uniform distances between grid nodes. An example of an irregular pattern is a distribution of marks created on the blank surface, the density of which increases towards the edges of the blank. According to a further embodiment, the method inspects the blank for one or more defects and determines the positions of defects arranged between the created marks by interpolating the positions of the marks determined by the first inspection device. Therefore, the position of a defect that is not located on one of the created marks can also be easily converted from the first coordinate system to the second coordinate system. For example, the position of the defect disposed between the coordinates of the established marks is determined by interpolating the positions of the marks determined by the first inspection device. For example, the interpolation includes triangulation, Delauny triangulation, radial basis functions, and / or any other interpolation method. In various embodiments, a reference blank containing a plurality of markings at corresponding predetermined nominal positions may also be provided. The plurality of markings may have one or more of the aforementioned characteristics of the markings. The reference blank is then placed on a second carrier of a second inspection device. Furthermore, the positions of the plurality of markings on the reference blank are determined in a second coordinate system by the second inspection device. Furthermore, a correction rule for correcting the conversion rule is determined based on the deviation between the positions of the markings in the second coordinate system determined by the second inspection device and the nominal positions of the markings. In this case, the word "a" or "an" should not necessarily be construed as limiting to a single element. Instead, multiple elements may be provided, such as, for example, two, three, or more. Any other numerical value used herein should not be construed as limiting the number of elements. Instead, numerical deviations of greater and lesser values ​​are possible unless otherwise indicated. Other possible implementations of the present invention also include combinations of features or specific embodiments not described above or below with respect to the exemplary embodiments. In this case, those skilled in the art may also add individual aspects to improve or supplement the individual basic forms of the present invention. Further advantageous configurations and aspects of the present invention are the subject of the following appended claims and exemplary embodiments of the present invention. The present invention will be explained in detail below based on preferred embodiments with reference to the accompanying drawings. Unless otherwise indicated, identical or functionally identical elements are denoted by the same reference numerals in the drawings. Note also that the illustrations in the drawings are not necessarily drawn to scale. A method for inspecting a lithography mask blank 100 according to one embodiment is described below. In a first step S1 of the present method, a blank plate 100 for a lithography mask is arranged in a first inspection device 102, as shown in Figure 1. The blank plate 100 has a main extension plane 104 (the uv plane in Figure 1). The blank plate 100 further includes a first edge 106, a second edge 108, a third edge 110, and a fourth edge 112. Specifically, the edges 106, 108, 110, and 112 of the blank plate 100 are arranged parallel to its main extension plane 104. The first edge 106 and the second edge 108 are at a certain angle to each other, and in particular, are arranged to be substantially perpendicular to each other. The third edge 110 is arranged relative to the first edge 106. Furthermore, the fourth edge 112 is arranged relative to the second edge 108. Specifically, the first inspection apparatus 102 includes a first carrier 114 for mounting the blank plate 100. The first carrier 114 includes a plurality of stoppers 116, 118, and 120 that abut against the blank plate 100. Specifically, in a first step S1, the blank plate 100 is placed on the first carrier 114 such that the first edge 106 and the second edge 108 abut against the stoppers 116, 118, and 120 of the first carrier 114. In the example shown in FIG1 , the first carrier 114 includes a first stopper 116, a second stopper 118, and a third stopper 120. Furthermore, in this example, the blank 100 is positioned on the first carrier 114 such that the first edge 106 of the blank 100 abuts the first stopper 116 and the second stopper 118. Furthermore, the second edge 108 of the blank 100 abuts the third stopper 120. The contact point A1 where the first edge 106 abuts the first stop 116 defines a first reference point R1 of the blank 100. Similarly, the contact point A2 where the first edge 106 abuts the second stop 118 defines a second reference point R2 of the blank 100. Furthermore, the contact point A3 where the second edge 108 abuts the third stop 120 defines a third reference point R3 of the blank 100. In the example shown in FIG1 , the first support platform 114 also includes a spring element 122 under tension, which presses the blank 100 toward the stops 116 , 118 , and 120 . A first spring element 122 is shown as an example; it presses against the third edge 110 of the blank 100. Furthermore, a second spring element 122 is shown as an example; it presses against the fourth edge 112 of the blank 100. More or fewer spring elements may be used instead of two spring elements 122. In a second step S2 of the method, an inspection position B is determined on the blank plate 100 using the first inspection device 102. For example, the inspection position B is a position on the surface 124 of the blank plate 100. The inspection position B of the blank plate 100 is the position initially inspected by the first inspection device 102 and subsequently inspected by the second inspection device 126 ( FIG. 2 ). The first inspection apparatus 102 has a first coordinate system 128. As apparent from Figure 1, a first abscissa axis 130 of the first coordinate system 128 is labeled with reference numeral u, and a first ordinate axis 132 of the first coordinate system 128 is labeled with reference numeral v. In step S2, the inspection position B on the hollow plate 100 in the first coordinate system 128 is determined by means of the first inspection device 102. In the process, for example, the u coordinate u of the inspection position B is determined in the first coordinate system 128. B and v coordinate v B . For example, the method is used to inspect a blank plate 100 for one or more defects D. For example, the defects D may be particles, such as foreign matter and / or dust particles. In this case, in step S2, the positions B of the one or more defects D of the blank plate 100 are determined in the first coordinate system 128. At the end of step S2 , the blank plate 100 may be output from the first inspection device 102 . In the third step S3 of the method, the blank plate 100 is placed in the second inspection device 126 , as shown in FIG. 2 . The second inspection device 126 includes a second carrier 136 for mounting the blank plate 100. The second carrier 136 may also include one or more stops 138, 140. In the example shown in FIG2 , the second carrier 136 includes a stop 138 that abuts the third edge 110 of the blank plate 100. Furthermore, for example, the second carrier 136 includes an additional stop 140 that abuts the fourth edge 112 of the blank plate 100. The second carrier 136 may also include more or fewer stops 138, 140 than the two shown. This also includes the case where the second carrier 136 does not include any stops. Furthermore, the stops 138, 140 of the second carrier 136 may also abut against edges other than the third edge 110 and the fourth edge 112 of the blank plate 100. The second inspection apparatus 126 has a second coordinate system 142. The second coordinate system 142 has a second abscissa axis 144 marked by reference numeral x, a second ordinate axis 146 marked by reference numeral y, and a coordinate origin 148. As shown in FIG2 , the blank plate 100 is arranged on the second carrier 136 of the second inspection apparatus 126 in a manner that allows it to be twisted and displaced relative to the second carrier 136 and the second coordinate system 142. This twisting and / or displacement may be caused, for example, by defects resulting from tolerances in the mechanical structure. For example, the displacement may be on the order of several micrometers (μm) to several millimeters (mm). Furthermore, the twisting may be on the order of several microradians (μrad) to several milliradians (mrad). It is important to note that for illustrative purposes, this twisting and displacement are shown exaggerated in FIG2 and subsequent figures. The coordinates u of the inspection position B in the first coordinate system 128 are determined by means of the first inspection device 102. B and v B The inspection position B determined by the first inspection device 102 should now be found in the second coordinate system 142 of the second inspection device 126 = (u B , v B ). With respect to the second coordinate system 142 of the second inspection device 126, the inspection position B now appears at coordinate x in the second coordinate system 142. B and y B As shown in Figure 2. For the sake of clarity, the inspection position B = (u B , v B ) is marked by reference symbol B. Furthermore, the inspection position B' = (x B , y B ) is marked by reference symbol B', but this is the same position only in different coordinates. In order to find and be able to inspect the inspection position B, B' through the second inspection device 126, it is necessary to convert the position B determined by the first inspection device 102 into (u B , v B ) is converted into a second coordinate system 142 of the second inspection device 126. In a fourth step S4 of the method, at least one image 152, 154, 156 of the blank plate 100 is recorded using the image recording unit 150 of the second inspection device 126 ( FIG. 3 ). FIG. 2 depicts only the image recording unit 150. Specifically, the image recording unit 150 is a high-resolution image recording unit having a spatial resolution of, for example, 50 μm or better, or even a spatial resolution of several nanometers. For example, the image recording unit 150 is a scanning microscope, such as the scanning electron microscope described in detail in the context of FIG. 9 . Specifically, the image recording unit 150 is used to record at least one image 152 , 154 , 156 of the blank plate 100 , so that the first edge 106 and the second edge 108 of the blank plate 100 are at least partially obtained in the at least one image 152 , 154 , 156 . Preferably, a separate image 152, 154, 156 (first to third images 152 to 156) is recorded for each reference point R1, R2, R3 of the blank 100. As is apparent from FIG3, the images capture the corresponding reference points R1, R2, R3 at the corresponding edges 106, 108 and a portion of the corresponding edges 106, 108. Exemplary image details 158, 160, 162 of the images 152, 154, 156 are labeled in FIG2. In a fifth step S5 of the method, a transformation rule is determined. The transformation rule is used to transform the inspection position B obtained in the first coordinate system 128 into the inspection position B′ in the second coordinate system 142 of the second inspection device 126. The transformation rule is determined based on the first edge 106 and the second edge 108 obtained in the at least one image 152, 154, 156. Specifically, the positions P1, P2, and P3 of the first and second edges 106 and 108 in the first coordinate system 128 and the positions P1′, P2′, and P3′ of the first and second edges 106 and 108 in the second coordinate system 142 are determined based on image processing of the at least one image 152, 154, and 156. For example, the positions P1, P2, and P3 of the first and second edges 106 and 108 at three reference points R1, R2, and R3 in the first coordinate system 128 are determined based on image processing of the at least one image 152, 154, and 156. For example, the positions P1′, P2′, and P3′ of the first and second edges 106 and 108 at three reference points R1, R2, and R3 in the second coordinate system 142 are further determined based on image processing of the at least one image 152, 154, and 156. 4 and 5 illustrate the rotation 164 of the first coordinate system 128 relative to the second coordinate system 142 by the rotation angle Θ. Furthermore, FIG. 6 illustrates the rotation 164 of the first coordinate system 128 relative to the second coordinate system 142 by the rotation angle Θ. The translation 166 of the first coordinate system 128 is labeled. 4 and 6 and the determination of the conversion rules, it is assumed that the coordinate system of the blank 100 corresponds to the first coordinate system 128 of the first inspection device 102. In other words, when configuring the blank 100 in step S1, any deviations relative to the first coordinate system 128 of the first inspection device 102 are ignored. As shown in FIG4 , the first reference point R1 has a position P1 = (u 1, v 1), and has a position P1' = (x 1, y 1). Furthermore, the second reference point R2 has a position P2 = (u 2, v 2), and has a position P2' = (x 2, y 2). Furthermore, the third reference point R3 has a position P3 = (u 3, v 3), and has a position P3' = (x 3, y 3). In step S5, based on the image analysis of the image 154 ( FIG. 3 ), the corresponding coordinate positions y of the first reference point R1 and the second reference point R2 in the second coordinate system 142 are determined. 1.y 2. Furthermore, based on image analysis, the horizontal coordinate position x of the third reference point R3 in the second coordinate system 142 is determined. 3. 4-6 , first coordinate system 128 of first inspection apparatus 102 is twisted by rotation angle θ relative to second coordinate system 142 of second inspection apparatus 126. That is, first transverse axis 130 of first coordinate system 128 is rotated by rotation angle θ relative to second transverse axis 144 of second coordinate system 142. Then, the rotation angle θ is calculated based on the right triangle 168 formed by the first abscissa axis 130 and the second abscissa axis 144. Specifically, the length Δy of the opposite side of the right triangle 168 can be calculated based on the determined ordinate positions y of the first and second reference points R1 and R2 in the second coordinate system 142. 1.y 2 to calculate, where Δy = y 2-y 1. Furthermore, it can be assumed that the length Δx of the adjacent side of right triangle 168 and the length Δu of the hypotenuse of right triangle 168 are approximately the same. Specifically, length Δu is the distance between first reference point R1 and second reference point R2 in the first coordinate system. For example, length Δu is determined based on pre-determined configuration data of first inspection apparatus 102, specifically, based on the pre-determined distance between first stopper 116 and second stopper 118 of first platform 114 of first inspection apparatus 102. Then, the rotation angle θ is approximately given by the inverse tangent of the quotient of the opposite side Δy and the adjacent side Δx, according to the following equation: . In the examples shown in FIG. 4 and FIG. 6 , the first coordinate system 128 of the first inspection device 102 is based on the translation vector ( FIG. 6 ) is displaced relative to the second coordinate system 142 of the second inspection device 126. That is, the first coordinate origin 134 of the first coordinate system 128 is displaced relative to the second coordinate origin 148 of the second coordinate system 142 by the translation vector = (t x , t y ), as shown in Figure 6. For example, the transformation rule includes a transformation matrix T (eg, an affine transformation matrix) according to the following equation: . In the above equation, u and v represent the coordinates of the position in the first coordinate system 128 (e.g., inspection position B), x and y represent the coordinates of the position in the second coordinate system 142 (e.g., inspection position B'), Θ represents the rotation angle of the first coordinate system 128 relative to the second coordinate system 142, and t x and t y Represents the translation vector The vector components of . As mentioned above, the rotation angle Θ can be calculated based on Δx and Δy. Translation vector The vector component t x and t y The position P3 (particularly x 3) and the determined position P1, P2 (especially y 1.y 1) Be confirmed. Specifically, the above transformation rule can be rewritten as follows through matrix multiplication: . Therefore, for reference point R2, the following occurs: . Therefore, for reference point R3, the following occurs: . These two equations can be solved for t x and t y Since the position y of the reference point R2 2 and the position x of the reference point R3 3 is determined from the recorded images 154, 156 (see also FIG4) through image processing, and since u 1 and u 2 is known from the construction data of the first inspection device 102, so it can be respectively obtained from the x and t y Solve the equation to determine t x and t y . Using the determined rotation angle Θ and translation vector The vector component t x and t y , all matrix elements of the transformation matrix T are known. Therefore, any position B (eg, one or more inspection positions B) in the first coordinate system 128 can be transformed into a corresponding position B′ in the second coordinate system 142 . If the method is used, for example, to inspect one or more defects D on a blank plate 100, the first inspection device 102 can determine the position B in the first coordinate system = (u B , v B The first inspection device 102 may further determine the position B = (u B , v B ) is transmitted to the second inspection device 126. The computing device of the second inspection device 126 (not shown in FIG. 2 ; for example, the control device 242 in FIG. 9 ) can then convert the transmitted position B = (u B , v B ) is converted into the corresponding position B' in the second coordinate system 142 of the second inspection device 126 = (x B , y B ). Therefore, the defect D of the blank plate 100 can be easily found by the second inspection device 126 and can be inspected in detail, for example, with high spatial resolution. For example, if it is intended to inspect a plurality of defects D or a plurality of positions B, B' on the blank 100, it is sufficient to determine a transformation rule only once using the transformation matrix T. This is the case in particular when the blank 100 does not move in the second inspection device 126. Then, by applying a transformation rule, the plurality of positions B delivered by the first inspection device 102 can be transformed into (u B , v B ) is converted into the corresponding plurality of positions B' = (x B , y B ). FIG. 7 illustrates a case where a blank 100 ′ for a lithography mask has rounded corners 172 . In the present case, it is assumed, as previously described, that the coordinate system of the blank 100' corresponds to the first coordinate system 128. In the case of rounded corners 172 of the blank 100' or chamfered corners (not shown), the coordinate origin 134 of the first coordinate system 128 can be determined based on the following explanation. As shown in Figure 7, first, the coordinate origin 134 of the first coordinate system 128 lies on a first straight line 174, which also includes the first reference point R1 and the second reference point R2. Second, the coordinate origin 134 of the first coordinate system 128 and the third reference point R3 define a second straight line 176. This also applies to the arrangement of the first straight line 174 perpendicular to the second straight line 176. Therefore, even in the case of rounded corners 172 and / or chamfered corners of the blank 100', the coordinate origin 134 of the first coordinate system 128 can be determined. Optionally, steps S1 to S5 may be repeated to allow for a more accurate determination of an average conversion rule (statistical average). Optionally, steps S1 through S5 can be repeated using the same method performed for a plurality of different first inspection devices 102. For example, the plurality of different first inspection devices 102 may differ from one another in that the stoppers 116 through 120 abut against the blank plate 100 at different contact positions A1 through A3. By performing steps S1 through S5 at least once for each of the plurality of different first inspection devices 102, a plurality of different transformation rules are determined in step S5. The determined plurality of different transformation rules are then averaged. Application of the thus-established average transformation rule allows the average transformation rule to be applied to any desired first inspection device 102 for coordinate transformation purposes. In the optional sixth step S6 of the method, at least one image 170 ( FIG. 8 ) of at least one defect D is recorded using the second inspection device 126. In this case, the image recording unit 150 is based on the position B′=(x B , y B Specifically, the image recording unit 150 is controlled so that the position B' converted into the second coordinate system 142 in the image 170 is obtained = (x B , y B For example, the image recording unit 150 is controlled so that the position B' converted into the second coordinate system 142 is equal to (x B , y B ) is imaged to the center of image 170. In an optional further step of the method, defects D are removed from the blank plate 100 by means of a second inspection device 126 . FIG9 shows another exemplary embodiment of a second inspection apparatus 200 that can be used in the methods described above and / or below. The second inspection apparatus 200 in FIG9 is an apparatus for inspecting (i.e., analyzing) a sample 202, such as a blank plate 100 ( FIG1 ). The second inspection apparatus 200 can also be configured as an apparatus for processing the sample 202 (e.g., blank plate 100). For example, the inspection apparatus 200 includes a housing 204. The housing 204 can be evacuated (e.g., to 10 -5 -10 -9 mbar residual gas pressure). The inspection apparatus 200 also includes a particle beam providing unit 208 disposed in the housing 204 and configured to provide a particle beam 210 . For example, the particle beam providing unit 208 is specifically implemented as an electron column 212 configured to provide the electron beam 210 . The particle beam providing unit 208 (eg, electron column 212 ) can be specifically designed as an electron microscope 212 (scanning electron microscope). The scanning electron microscope 212 is an example of the image recording unit 150 ( FIG. 2 ). Inspection apparatus 200 (as an example of a second inspection apparatus) includes, for example, a sample carrier 214 (as an example of a second carrier) for mounting a sample 202 (e.g., blank plate 100). Sample carrier 214 may further include a positioning unit 216 (not separately shown). This positioning unit allows sample carrier 214 to be displaced relative to base 218 in, for example, three spatial directions (x, y, and z), and to be rotated about at least one axis (e.g., an axis parallel to the z-direction in FIG. 9 ). Reference numeral 220 denotes a sample carrier device, which includes sample carrier 214, base 218, and positioning unit 216. The inspection apparatus 200 may also optionally include a process gas supply unit 224 for providing a process gas 226 . The process gas supply unit 224 may be used in conjunction with the particle beam supply unit 208 to perform a particle beam induced treatment process on the sample 202 (e.g., the blank 100 ). To this end, for example, the process gas 226 is supplied via the process gas supply unit 224 and irradiated by the particle beam 210 . The inspection apparatus 200 may optionally include a manipulator unit 228 (eg, a micromanipulator unit and / or a nanomanipulator unit) for performing manipulations on the sample 202 or on the surface 222 of the sample 202 (eg, on the surface 124 of the blank 100 in FIG. 2 ). For example, the manipulator unit 228 includes an atomic force microscope 230. The atomic force microscope 230 includes a tip 232 for analyzing and / or processing the sample 202. The tip 232 is disposed on a cantilever arm 234, which is movably fixed to a positioning unit 236 (movement unit). Specifically, the cantilever arm 234 includes a first end 238 (base end 238), at which the cantilever arm 234 is movably fixed to the positioning unit 236. The cantilever arm 234 also includes a second end 240 (free end 240), at which the tip 232 is disposed. The positioning unit 236 allows the tip 232 to be moved in three spatial directions (x, y, and z) (translational movement in the x, y, and z directions). Movement in the x and / or y directions is referred to herein as lateral movement. Here, movement in the z-direction represents the tip 232 being moved closer to the sample 202 (negative z-direction) and the tip 232 being moved away from / from the sample 202 (positive z-direction). The atomic force microscope 230 can be used to perform operations on the sample 202. For example, the tip 232 can be used to pick up (i.e., lift) a particle D adhered to the sample surface 222 of the sample 202 (Figures 1 and 2). To this end, the tip 232 is moved accordingly, for example, via the positioning unit 236. To facilitate this, the sample carrier 120 can also be moved via its positioning unit 216. For example, the electron microscope 212 can be used to monitor in real time the picking up (i.e., lifting) of the particle D by the tip 232. The tip 232 is then moved, for example, via the positioning unit 236, to a storage unit (not shown), where the particle D is transferred from the tip 232 to the storage unit. Additionally or alternatively to this operation, the atomic force microscope 230 may also be configured to record images. The inspection apparatus 200 further comprises, for example, a control device 242 for controlling the manipulator unit 228 (eg, the positioning unit 236 ), the sample carrier 214 or the further positioning unit 216 , the particle beam providing unit 208 and / or the process gases. 10 and 12 , a method for inspecting a blank 300 of a lithography mask according to another embodiment will be described below. In the first step S101 of the method according to another embodiment ( FIG. 12 ), the blank plate 300 is placed on the second loading platform 136 of the second inspection device 126 ( FIG. 2 ). In a second step S102 of the method according to a further embodiment, a plurality of marks 302 are created on the blank plate 300 by means of the second inspection device 126. In Fig. 10, some of the plurality of marks 302 have been provided with reference numerals, by way of example. For example, the plurality of marks 302 are created by particle beam induced deposition and / or etching. For example, the second inspection apparatus embodiment shown in FIG9 can be used for this purpose. For example, a process gas 226 is provided to the surface of the blank 300 (e.g., the surface 222 of the sample 202 in FIG. 9 ) via the gas supply unit 224. Furthermore, the particle beam supply unit 208 (e.g., the electron column 212) provides an active particle beam 210 (e.g., an electron beam) to the surface of the blank 300. This can induce a chemical reaction, causing material to be deposited on the surface of the blank 300 from the gas phase of the process gas 226 (in the case of a deposition gas), or to be etched away from the blank (in the case of an etching gas). Alternatively, the mark 302 may be formed on the surface of the blank 300 by embossing. Preferably, each of the plurality of marks 302 has a circular form 304, as shown in Figure 10. Therefore, the first inspection device 102 can more easily determine the position of the mark 302, especially the center of the mark 302, in the subsequent step S2'. Furthermore, each of the plurality of marks 302 has a diameter 306 of at least 10 nm or larger, for example. The larger the diameter 306 of an individual mark 302 is, the easier it is to be detected by the first inspection device 102 in the subsequent step S2 ′. 10 , a plurality of markers 302 are arranged in a regular pattern 308, and more particularly, in a regular grid 310. Specifically, the markers 302 are arranged at nodes of the regular grid 310. Furthermore, the nodes are arranged at regular distances from each other. Although not shown in the drawings, the marks 302 may be created on the blank plate 300 in an irregular pattern. The example of Figure 10 shows a plurality of established marks 302. However, in other examples, more or fewer marks 302 than shown in Figure 10 may be established on the blank plate 300 by means of the second inspection device 126. For example, only three marks 302 may be established on the blank plate 300. In step S102, according to the predetermined nominal position P of the second coordinate system 142, N A plurality of marks 302 are created on the blank plate 300. For example, the nominal position P in the second coordinate system 142 N = (x N , y N ) is a mark used for one of the multiple marks 302 shown in Figure 10. It is possible that the blank plate 300 is positioned in the second carrier 136 of the second inspection apparatus 126 using a slight twist and / or displacement, as shown in FIG2 . Then, as shown in FIG10 , a mark 302 is created on the blank plate 300 based on the inaccurate placement of the blank plate 300 on the carrier 136 . Therefore, the created mark 302 contains information about the inaccurate placement of the blank plate 300 on the carrier 136 of the second inspection apparatus 126 . After step S102 , steps S1 ′ to S5 ′ ( FIG. 12 ) are executed, which correspond to steps S1 to S5 of the above method ( FIG. 11 ). In this case, in step S2′, the positions P of the plurality of established marks 302 in the first coordinate system 128 are determined by means of the first inspection device 102. M Furthermore, the position P of the mark 302 in the first coordinate system 126 determined by the first inspection device 102 is M and the nominal position P of the marker 302 in the second coordinate system 142 N Deviation between. Subsequently, steps S3 ′ and S4 ′ similar to steps S3 and S4 are performed. Then, step S5' is executed, wherein after the conversion rule is determined, the mark 302 detected by the first inspection device 102 in step S2' is used to further improve the determined conversion rule. Specifically, the position P of the mark 302 in the first coordinate system 126 determined in step S2' is M and the nominal position P of the marker 302 in the second coordinate system 142 N The deviation is used to determine a correction rule for correcting the conversion rule. Specifically, the method can be applied by applying the marking 302 to a (for example, a single) blank to be checked and thereby determining the deviation once. The deviation thus determined can then be applied when checking a different blank, in particular a corresponding correction can be performed. If this method is used to inspect one or more defects D of a blank plate 300, it may be the case that the micro-defect D is located at the coordinates of one of the plurality of marks 302. The position of the defect D can then be easily determined. However, if the position of the defect D is located between the coordinates of the established marks 302, the position of the defect D can be determined between the coordinates of the plurality of positions P of the marks 302 determined by the first inspection device 102. M Interpolation 312 is applied between them; as shown in FIG10 . Although the present invention has been described on the basis of exemplary embodiments, the present invention can be modified in many ways. 100, 100': Blank plate 102: Inspection device 104: Main extension plane 106: Edge 108: Edge 110: Edge 112: Edge 114: Carrier 116: Stop 118: Stop 120: Stop 122: Elastic element 124: Surface 126: Inspection device 128: Coordinate system 130: Horizontal coordinate axis 132: Vertical coordinate axis 134: Coordinate origin 136: Carrier 138: Stopper 140: Stopper 142: Coordinate System 144: Horizontal Axis 146: Vertical Axis 148: Coordinate Origin 150: Image Recording Unit 152: Image 154: Image 156: Image 158: Image Detail 160: Image Detail 162: Image Detail 164: Rotation 166: Translation 168: Triangle 170: Image 172: Corner 174: Line 176: Line 2 00: Inspection device 202: Sample 204: Housing 206: Pump 208: Particle beam providing unit 210: Particle beam 212: Electron microscope / electron column 214: Sample carrier 216: Storage unit 218: Base 220: Sample carrier device 222: Surface 224: Process gas supply unit 226: Process gas 228: Manipulator unit 230: Atomic force microscope 232: Tip 234: Cantilever arm 236: Storage unit 238: End 240: End 242: Control device 300: Blank plate 302: Mark 304: Shape 306: Diameter 308: Pattern 310: Grid 312: Interpolation A1-A3: Position B, B': Position D, D': Defect Δu: Length Δy: Length Θ: Angle R1-R3: Reference point P1-P3: Position P1'-P3': Position P M Position P N Location : translation vector t x , t y : Vector components S1-S6: Method steps S1'-S6': Method steps S101, S102: Method step u: Direction, axis u 1.u 2.u 3: Position u B 、u M、u N :position v:direction, axis v 1. v 2. v 3: Position v B 、v M 、v N :position x:direction, axis x 1.x 2. x 3: Position x B 、x N :position y:direction, axis y 1.y 2.y 3: Position y B 、y N :position z:direction,axis FIG1 shows a blank of a lithography mask disposed in a first inspection apparatus according to one embodiment; FIG2 shows the blank plate shown in FIG1 configured in a second inspection device according to one embodiment; FIG3 shows images of the blank plate recorded by the second inspection device shown in FIG2 , wherein first, second, and third reference points on the edge of the blank plate are obtained in a plurality of images; FIG4 schematically illustrates the blank plate shown in FIG2 and a first coordinate system of the first inspection device and a second coordinate system of the second inspection device; Figure 5 shows an enlarged detail of Figure 4; FIG6 shows a view similar to FIG4 , with the translation of the first coordinate system relative to the second coordinate system marked; FIG7 shows a view similar to FIG4 , schematically illustrating a blank plate with rounded corners; FIG8 shows an image of a blank plate defect recorded by the second inspection device; FIG9 shows a further embodiment of the second inspection apparatus; FIG10 schematically illustrates a mark established on a blank plate using a second inspection device; FIG11 is a flow chart showing a method for inspecting a blank plate of a lithography mask according to one embodiment; and FIG. 12 is a flow chart illustrating a method for inspecting a blank of a lithography mask according to another embodiment. 100, 100': blank 128: Coordinate System 130: horizontal axis 142: Coordinate system 144: horizontal axis 164: Rotation 168: Triangle Θ: Angle u 1.u 2.u 3: Location v: direction, axis x: direction, axis x 1.x 2. x 3: Location y: direction, axis y 1.y 2.y 3: Location

Claims

1. A method for inspecting a blank plate (100) of a photomask, comprising the following steps: a) placing the blank plate (100) on a first support stage (114) of a first inspection device (102) such that a first edge (106) and a second edge (108) of the blank plate (100) rest against stops (116, 118, 120) of the first support stage (114); b) determining (S2) an inspection position (B) on the blank plate (100) in a first coordinate system (128) by means of the first inspection device (102); c) placing the blank plate (100) on a second support stage (136) of a second inspection device (126) having an image recording unit (150); d) Using the image recording unit (150) to record (S4) at least one image (152, 154, 156) of the blank plate (100), such that at least part of the first edge (106) and the second edge (108) are obtained; and e) based on the first edge (106) and the second edge (108) obtained in the at least one image (152, 154, 156), a conversion rule is determined (S5) to convert the inspection position (B) obtained in the first coordinate system (128) into a second coordinate system (142) of the second inspection device (126).

2. The method as described in claim 1, wherein the second inspection device (126) includes a scanning microscope device (212), a scanning electron microscope device (212), a scanning probe microscope device and / or an atomic force microscope device (230).

3. The method as described in claim 1 or 2, wherein the spatial resolution of the image recording unit (150) of the second inspection device (126) is 100 μm or more preferably 50 μm or more preferably 30 μm or more preferably 10 μm or more preferably 5 μm or more preferably 1 μm or more preferably 0.1 µm or more preferably 50 nm or more preferably 10 nm or more preferably 5 nm or more preferably and / or 3 nm or more preferably.

4. The method as described in claim 1 or 2, wherein: One or more defects (D) of the blank plate (100) are inspected in the method; in step b), the location (B) of at least one defect (D) of the blank plate (100) is determined in the first coordinate system (128) by means of the first inspection device (102); and the determined conversion rule is used to convert the location (B) of at least one defect (D) obtained in the first coordinate system (128) into a location (B') in the second coordinate system (142).

5. The method as described in claim 4, including after step e): using the image recording unit (150) of the second inspection device (126) to record (S6) at least one image (152, 154, 156) of the at least one defect (D), wherein the image recording unit (150) is aligned based on the position (B') of the at least one defect (D) which has been converted into the second coordinate system (142).

6. The method as described in claim 1 or 2, wherein: The first support platform (114) includes a first, second, and third stop (116, 118, 120); the blank plate (100) is disposed on the first support platform (114) such that the first edge (106) is close to the first stop (116) and the second stop (118) and the second edge (108) is close to the third stop (120), such that the first, second, and third reference points (R1, R2, R3) of the blank plate (100) are thus defined at the contact positions (A1, A2, A3) of the first, second, and third stops (116, 118, 120) on the first and second edges (106, 108); In step d), images (152, 154, 156) of the blank plate (100) are recorded for each reference point (R1, R2, R3), and the corresponding reference points (R1, R2, R3) are obtained in the images; and the conversion rule is determined based on the first, second and third reference points (R1, R2, R3) obtained in the recorded images (152, 154, 156).

7. The method as described in claim 6, wherein: Image processing based on the corresponding recorded images (152, 154) is used to determine the positions (P1, P2) of the first and second reference points (R1, R2) in the second coordinate system (142); and / or image processing based on the corresponding recorded image (156) is used to determine the position (P3) of the third reference point (R3) in the second coordinate system (142).

8. The method as described in claim 7, wherein: The transformation rule includes a rotation (164) by a rotation angle (Θ) and / or a translation (166) using a translation vector (). The rotation angle (Θ) is determined based on the determined positions (P1, P2) of the first and second reference points (R1, R2) in the second coordinate system (128, 142). The vector components (tx, ty) of the translation vector (). are determined based on the determined position (P3) of the third reference point (R3) in the second coordinate system (142) and the determined position (P1, P2) of the first or second reference point (R1, R2) in the second coordinate system (142).

9. The method as described in claim 1 or 2, wherein: The transformation rule includes a transformation matrix according to the following equation: , where u and v represent the coordinates of position (B) in the first coordinate system (128), x and y represent the coordinates of position (B') in the second coordinate system (142), Θ represents the rotation angle (164) of the first coordinate system (128) relative to the second coordinate system (142), and tx and ty represent the translation (166) of the first coordinate system (128) relative to the second coordinate system (142), and / or the transformation rule includes a rotation (164) through the rotation angle Θ, which satisfies the following equation: , Wherein, Θ represents the rotation angle (164) of the first coordinate system (128) relative to the second coordinate system (142), Δx represents the coordinate difference between the first reference point (R1) and the second reference point (R2) in the second coordinate system (142) at the horizontal coordinates (x1, x2), and Δy represents the coordinate difference between the first reference point (R1) and the second reference point (R2) in the second coordinate system (142) at the vertical coordinates (y1, y2).

10. The method as described in claim 6, wherein determining the transformation rule includes determining the origin (134) of the first coordinate system (128) based on the following conditions: the origin (134) of the first coordinate system (128) lies on a first straight line (174) on which both the first reference point (R1) and the second reference point (R2) exist; and the first straight line (174) is perpendicular to a second straight line (176) on which both the origin (134) of the first coordinate system (128) and the third reference point (R3) exist.

11. The method as described in claim 1, wherein: The method includes, prior to step a), configuring (S101) the blank plate (300) on the second stage (136) of the second inspection device (126); and using the second inspection device (126) to establish (S102) a plurality of marks (302) on the blank plate (300) according to a predetermined nominal position (PN) of the second coordinate system (142); determining, in step b), the positions (PM) of the plurality of marks in the first coordinate system (128) by means of the first inspection device (102); and determining, in step e), a correction rule for correcting the conversion rule based on the deviation between the position (PM) of the marks (302) in the first coordinate system (128) determined by means of the first inspection device (102) and the nominal position (PN) of the marks (302) in the second coordinate system (142).

12. The method as described in claim 11, wherein the plurality of marks (302) are generated by particle beam induced deposition and / or etching and / or imprinting through the blank plate (300).

13. The method as described in claim 11, wherein the plurality of marks (302) have a circular form (304) and / or a diameter (306) of 10 nm or greater, 50 nm or greater, 100 nm or greater and / or 300 nm or greater.

14. The method as described in claim 11, wherein the plurality of marks (302) are generated on the blank plate (300) using a regular pattern (308) and / or a regular grid (310) or an irregular pattern.

15. The method as described in claim 11, wherein one or more defects (D) of the blank (300) are inspected in the method, and the location (B) of the defect (D) disposed between the established marks (302) is determined by interpolation (312) of the position (PM) of the marks (302) determined by the first inspection device (102).

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