Method for analyzing and / or processing a lithography mask and repair system

Abstract

Method for analyzing and / or processing a lithography mask (100) for a lithography system (1), the method comprising: providing (S1) a reference structure (124) on the lithography mask (100) such that the reference structure (124) is not imaged when the lithography mask (100) is imaged on a wafer (13) using the lithography system (1); generating (S2) an image of the reference structure (124) using a particle beam (202); and controlling (S3) the particle beam (202) for analyzing and / or processing the lithography mask (100) depending on the generated image of the reference structure (124).

Description

[0001] The present invention relates to a method for analyzing and / or processing a lithography mask and a repair system.

[0002] Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithography process is carried out using a lithography system that has an illumination system and a projection system. The image of a mask (here also referred to as a "lithography mask" or "reticle") illuminated by the illumination system is projected by the projection system onto a substrate, such as a silicon wafer, coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection system in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0003] Driven by the pursuit of ever smaller structures in the production of integrated circuits, EUV lithography systems are currently being developed that use light with a wavelength in the range of 0.1 nm to 30 nm, particularly 13.5 nm. Since most materials absorb light at this wavelength, such EUV lithography systems must use reflective optics, i.e., mirrors, instead of the refractive optics, i.e., lenses, as was previously the case.

[0004] As the structure sizes of both masks used in the lithography process and microlithographically structured wafers become ever smaller, the analysis and processing or repair of such masks represent an increasingly demanding challenge in practice.

[0005] A lithography mask is used to produce a large number of individual components, for example, several hundred thousand or even several million. If a lithography mask has a defect, i.e., a defined structure on the lithography mask is not positioned within a defined area, this defect will be transferred to the light-sensitive coating and thus to the substrate during each exposure process with the lithography mask. It is therefore extremely important that the lithography masks used are defect-free. In this context, it is worthwhile to invest considerable effort in the inspection and repair of lithography masks.

[0006] Known repair processes, for example, are based on particle beam-induced etching or deposition processes, which can be carried out with high spatial resolution using the particle beam. During particle beam-induced repair of defects on lithography masks, electrostatic charges on the lithography mask or mechanical drifts of system components and / or the lithography mask can lead to the particle beam or electron beam not hitting a designated position on the lithography mask. To minimize these time-dependent drift effects of the particle beam or electron beam, the lithography mask, and / or the sample stage during processing or imaging, reference structures are usually created on the lithography mask in the periphery of the repair site before the start of the repair process.These reference structures are regularly captured by an image acquisition device to measure a deviation relative to at least one reference image. This deviation can be used to correct the position of the particle beam or electron beam in the form of a drift correction.

[0007] In particle- or electron-beam-based systems, such reference structures are created by depositing material on the lithography mask at the periphery of the area to be processed or repaired. These reference structures are also referred to as drift correction marks (or DC marks) and are made from dot-deposited deposits of the precursors TEOS or Cr(CO)6.

[0008] Typically, the deposited reference structures remain on the lithography mask after completion of the repair process and are not reliably removed even by a mask cleaning procedure.

[0009] However, due to increasingly smaller feature sizes on the lithography masks, especially in EUV and / or high NA EUV lithography, this leads to the remaining reference structures forming disturbances during component fabrication using the lithography mask, which can adversely change the optical properties of the lithography mask.

[0010] Against this background, it is an object of the present invention to provide an improved method for analyzing and / or processing a lithography mask and an improved repair system.

[0011] Accordingly, a method for analyzing and / or processing a lithography mask for a lithography system is proposed. The method comprises the following steps: - Providing a reference structure on the lithography mask such that when the lithography mask is imaged on a wafer using the lithography system, the reference structure is not imaged; - generating an image of the reference structure using a particle beam; and - Controlling the particle beam for analyzing and / or processing the lithography mask depending on the generated image of the reference structure.

[0012] The analysis and / or processing of the lithography mask preferably comprises a repair process during which at least one defect location of the lithography mask is repaired by the particle beam by etching or enriching particles at the defect location.

[0013] The phrase “image of the lithography mask” preferably refers to a result of the lithographic process in microelectronics or semiconductor manufacturing. This lithographic process is used in particular for producing integrated circuits (ICs). The “image” of the lithography mask preferably refers to the transfer of the pattern from the mask to the wafer during the exposure step. With reference to the above, the at least one reference structure is designed such that it is not imaged on the wafer during the exposure step, which also includes the image of the at least one reference structure on the wafer having a maximum dimension (i.e., maximum dimension) or being describable by another parameter, wherein the maximum dimension or the other parameter is below a predetermined threshold value.The threshold value is dimensioned such that the imaged at least one reference structure is non-critical for a predetermined imaging process in a predetermined lithography system (i.e., it only insignificantly influences this process). To achieve this, the at least one reference structure can preferably be optimized with respect to a plurality of design parameters, which will be explained in more detail below. The physical properties of the at least one reference structure are thus selected such that they are not imaged on the lithography mask or the reference structure does not change the optical properties of the lithography mask beyond a permissible limit. The reference structure or the drift correction mark therefore never adversely changes the imaging in the lithography process.

[0014] Examples of suitable masks include those used in lithography with UV, DUV, or EUV light. Binary masks, phase-shifting masks, or hybrids of both are particularly used.

[0015] A "wafer" is a preferably flat, round and / or nearly round, especially disc-shaped, substrate made of a semiconductor material such as silicon, which is used in microelectronics and semiconductor manufacturing. Wafers serve as the starting material for the production of integrated circuits (ICs) and other electronic components. Wafers can have a multilayer structure.

[0016] As already mentioned at the beginning, during particle beam-induced repair of defects on lithography masks, electrostatic charges in the lithography mask or mechanical drifts of system components and / or the lithography mask can lead to the particle beam or electron beam not hitting a designated position on the lithography mask. To minimize these time-dependent drift effects of the particle beam or electron beam, the lithography mask, and / or the sample stage during processing or imaging, reference structures are created in the periphery of the repair site before the start of the repair process. In embodiments, the "reference structure" can be formed as one or more so-called drift correction marks, which are used to correct the alignment of a particle beam, for example, an electron beam, of the lithography system during an undesired drift movement.

[0017] The phrase "image of the reference structure using the particle beam" means that the at least one reference structure is preferably captured or imaged by an image recording device in order to measure a deviation relative to at least one reference image in which the reference structure was recorded, for example, at an earlier time step. The deviation thus determined can be used to correct the position of the particle beam or electron beam in the form of a drift correction. The control of the particle beam for analyzing and / or processing the lithography mask is thus carried out "depending on the generated image of the reference structure using a particle beam."

[0018] Providing a reference structure that is not imaged or only insignificantly imaged during imaging onto the wafer can help prevent misimages on the wafer. This is particularly important because defects in the mask can lead to defective chips or semiconductor devices. The process contributes to quality assurance in semiconductor manufacturing by improving the accuracy and / or consistency of the lithography mask. This ultimately reduces manufacturing costs and improves chip yield. Since the reference structure is designed in such a way that it does not negatively affect the optical properties of the lithography mask, the reference structure can also be printed on a lithography mask before the lithography mask is used.If a defect occurs during use, or if an analysis of a part of the lithography mask is required, the existing reference structure can then be used to enable repair and / or analysis using the particle beam using drift correction.

[0019] According to one embodiment, the provision takes place as a function of at least one parameter of the lithography system, wherein the parameter is selected from a wavelength of a working light of the lithography system and / or an intensity of a working light of the lithography system and / or a numerical aperture of the lithography system.

[0020] Based on the at least one parameter, the at least one reference structure is configured and / or designed such that it is not imaged during the imaging of the lithography mask on a wafer in the lithography system. For example, a size and / or at least one dimension and / or at least one refractive index of the reference structure can be determined as a function of a wavelength used by the lithography system, so that it is not imaged on the wafer during the imaging step because the reference structure is designed, for example, to absorb light of this wavelength. Similarly, the reference structure can be designed based on the intensity and / or the numerical aperture (NA).

[0021] According to a further embodiment, the reference structure is provided in such a way that it is not imaged on the wafer by selecting a volume and / or a basic geometry and / or a refractive index and / or a material and / or a material composition of the reference structure and / or a distance of the reference structure to at least part of an imaging structure of the lithography mask, which is imaged during the imaging of the lithography mask on the wafer using the lithography system.

[0022] The "image structure" describes the pattern and / or structure created on the lithography mask and to be transferred to a substrate or semiconductor wafer. The image structure on the lithography mask preferably comprises various elements that represent the structures and / or circuits to be transferred to the wafer. These structures can be, for example, conductive traces, transistors, insulators, contacts, and / or other microelectronic components. The nature of the image structure on the mask is crucial because it directly influences the quality and / or performance of the manufactured microelectronic components or chips.

[0023] At a defect location, the imaging structure deviates from a specified value and / or from a specification. To enable error-free use of the lithography mask, this defect location is to be analyzed and / or processed or repaired using the present method. To enable error-free repair and / or analysis using the particle beam, the reference structure is provided adjacent to at least a portion of the imaging structure, in particular to an expected or existing defect within it, and is used or employed to correct the drift of the particle beam.

[0024] According to a further embodiment, the reference structure is formed by depositing a material on the lithography mask using a process gas. Alternatively, the reference structure is formed by a recess and / or a notch in the lithography mask by etching away using a process gas. A preferred minimum depth of the recess and / or notch is at least 10 nm.

[0025] If the reference structure is provided as a material deposit, material is deposited on the lithography mask to a height that is preferably above a topographic level in the immediate vicinity of the reference structure. If the reference structure is provided as a recess, material is removed from the lithography mask to a depth that is preferably below a topographic level in the immediate vicinity of the reference structure. The recess or notch should preferably be no deeper than 60 nm or no deeper than an absorption depth of the lithography mask.

[0026] In the case of a recess / notch, the amount of material missing compared to the native lithography mask is preferably selected such that the optical properties of the mask are not adversely affected. In this case, the recess / notch can remain on the mask since it is not imaged on the wafer anyway. The advantage of providing a notch and / or a depression as a reference structure is that no material needs to be deposited on the lithography mask. Furthermore, a secondary electron current in an SEM image is higher at edges than in the vicinity of the edges. In contrast, a secondary electron current on an inner side of the recess or notch is lower than in the surrounding area. Thus, the reference structure can be clearly identified as such based on its contrast. The recess and / or notch can preferably be created using gas-assisted, electron beam-induced etching and / or a mechanical probe.

[0027] According to a further embodiment, the imaging structure has at least one defect site to be repaired by means of the particle beam, wherein the reference structure is provided in the immediate periphery of the defect site.

[0028] "At least one defect to be repaired by means of the particle beam" preferably describes a location and / or a site within, at, or on the imaging structure where at least one defect or error has occurred. This defect is to be repaired or corrected using a particle beam. The particle beam can, for example, comprise electrons, ions, or other charged particles. The fact that "the reference structure is provided in the immediate periphery of the defect" means that at least one reference structure is present in the immediate vicinity of the defect. The reference structure can serve as a template or pattern to ensure that the defect repair can be carried out precisely.

[0029] According to a further embodiment, a maximum dimension of the reference structure, measured in particular parallel to a main extension plane of the lithography mask, is less than or equal to 60 nm, preferably less than or equal to 50 nm, preferably less than or equal to 40 nm, preferably less than or equal to 30 nm, preferably less than or equal to 20 nm.

[0030] To select a maximum dimension for the reference structure, it is preferable to specify that particle defects up to a size of 52 nm (critical dimension, "CD") must be detected, or that particles larger than this size are recognized as optical defects in the lithography mask. Since the reference structure is not intended to be imaged on the wafer or at least not to negatively influence the optical properties of the wafer, it is preferred if the maximum dimension of the reference structure is smaller than 52 nm. The use of such "small" reference structures has the advantage that the secondary electron current is increased due to a larger radius of curvature of the surface of the reference structure or the deposit.

[0031] The "main extension plane" of the lithography mask refers to the plane in which the essential structures of the lithography mask are aligned. This plane is crucial for the lithography process, in which the pattern is transferred from the mask to a semiconductor wafer or substrate. The main extension plane of the lithography mask is preferably parallel to the surface of the mask.

[0032] According to a further embodiment, a maximum dimension of the reference structure, in particular measured parallel to the main extension plane of the lithography mask, is selected to be smaller than a minimum dimension of the imaging structure, in particular measured parallel to the main extension plane of the lithography mask.

[0033] This corresponds to the goal that the reference structure is not later imaged on the wafer because it is smaller than the smallest imageable component of the lithography mask.

[0034] According to a further embodiment, the refractive index of the reference structure has a phase-shifting component and an absorbing component, wherein the phase-shifting component of the refractive index has a difference from the vacuum of at most 0.045, and wherein the absorbing component of the refractive index has a difference from the vacuum of at most 0.02.

[0035] The "refractive index of the reference structure" refers to the optical property of the reference structure that indicates how light or electromagnetic radiation is refracted or diffracted in the structure. The refractive index is a dimensionless value that describes the change in the phase velocity of light in the structure compared to the vacuum velocity. The "phase-shifting part" describes that the refractive index of the reference structure has a part that changes the phase velocity of light but does not cause significant absorption or energy loss. This phase-shifting part can be used to control the phase shift of light, which can be important in optical applications. The "absorbing part" describes that the refractive index of the reference structure has a part that can absorb light.This means that some of the incident light is absorbed into the structure and converted into heat instead of being transmitted or reflected.

[0036] According to a further embodiment, the material comprises one or more of the following chemical elements Si, Ba, Ce, La, Br, Rb, Be, Sr, P, S, Ca, Y, B, Sc, Zr, Gd, Nd, C, Ti, Se, F, Cl.

[0037] In principle, other materials or material compositions not mentioned here are also conceivable if they are suitable for not being later imaged on the wafer in the form of the reference structure.

[0038] According to a further embodiment, the material of the reference structure is selected such that a secondary electron current of the reference structure is greater than a secondary electron current of a region of the lithography mask surrounding the reference structure. Alternatively or additionally (and / or), a current of backscattered electrons of the reference structure is smaller or greater than a current of backscattered electrons of a region of the lithography mask surrounding the reference structure. Thus, for deposited structures, for example, curved surfaces, the signal of the secondary electron yield is preferably greater than that of the surroundings, for example, a flat surface.

[0039] The secondary electron current is preferably proportional to a secondary electron yield. The backscattered electron current is preferably proportional to a backscattered electron yield. The secondary electron current can be recorded in the form of a measurement signal that can be measured by a detector. The backscattered electron current can be recorded in the form of a measurement signal that can be measured by a detector. The respective detector signal is preferably proportional to the respective current.

[0040] Because the secondary electron yield of the reference structure is significantly higher or significantly lower than the secondary electron yield at other locations on the lithography mask due to material and / or geometry, the reference structure can be clearly identified as such and used for drift correction. It is advisable to maximize the secondary electron yield of the reference structure as much as possible in order to clearly distinguish it from the surrounding lithography mask. The same applies to the current of backscattered electrons. An acceptable signal difference in the secondary electron yield or the secondary electron current proportional to it preferably corresponds to a gray value difference of 70. An acceptable signal difference in the secondary electron yield orThe secondary electron current proportional thereto preferably corresponds to an image contrast of C = gray value (reference structure) - gray value (overall image) / gray value (overall image) = 184 - 116 / 116 = 0.59. Particularly preferably, the reference structure has an image contrast that is greater than 0.5, more preferably greater than 0.6, even more preferably greater than 0.7, and most preferably greater than 0.8.

[0041] According to a further embodiment, the reference structure has an auxiliary layer by which the secondary electron current and / or the current of backscattered electrons of the at least one reference structure is amplified.

[0042] The auxiliary layer acts, for example, as a type of "amplifier" to further amplify the signal of the secondary electron current and / or the current of backscattered electrons relative to the respective signal of the lithography mask. The auxiliary layer is preferably applied and / or applied between the lithography mask and the reference structure and preferably comprises a material that is different from the lithography mask and the reference structure. The auxiliary layer preferably has a maximum dimension, in particular measured parallel to the main extension plane of the lithography mask, that is greater than a maximum dimension of the reference structure. The auxiliary layer is preferably produced using precursors such as TEOS, Cr(CO)6, or Mo(CO)6. Other precursors mentioned in the present text are also possible as material bases for the auxiliary layer.The respective electron yield of the auxiliary layer preferably differs more from the respective electron yield of the auxiliary structure than from the electron yield of the lithography mask.

[0043] According to a further embodiment, the depression and / or the notch is filled by a material deposited and / or deposited therein, preferably flush with a surface of the lithography mask.

[0044] Before using the depression and / or notch as a reference structure, the respective depression and / or notch can be filled with a material whose secondary electron yield upon electron bombardment with the particle beam differs from the secondary electron yield of the area surrounding the depression and / or notch. Preferably, the filling material is selected such that the optical properties of the lithography mask can be at least partially reconstructed. This creates a reference structure that essentially provides a material contrast without altering the topography of the lithography mask in the area of ​​the reference structure.

[0045] According to a further embodiment, the working light used in imaging the lithography mask on the wafer has a wavelength of between 0.1 nm and 30 nm, preferably between 13 and 14 nm, in particular 13.5 nm and / or the lithography system has a numerical aperture greater than 0.3, in particular greater than 0.33, preferably greater than 0.5, for example 0.55, for example between 0.3 and 0.75, in particular greater than 0.6, preferably greater than 0.7.

[0046] According to a further aspect, a repair system for performing a particle beam-based repair process of a lithography mask is provided, the repair system comprising: - a repair device; and - the lithography mask which can be analyzed and / or processed by means of the repair device according to the method according to one of its embodiments.

[0047] The repair system may also include the (predetermined) lithography system.

[0048] According to a further aspect, a method is provided for analyzing and / or processing a lithography mask, the lithography mask comprising an imaging structure to be imaged onto a wafer with at least one edge, the method comprising the steps of: - detecting at least one portion of the at least one edge at a first time by an image recording device or a detector; - determining an edge position of the at least one portion of the at least one edge on the lithography mask based on at least one reference position at the first time; - (in particular pixel-by-pixel) determining roughness information of the at least one section of the at least one edge at the first time; - capturing the at least one portion of the at least one edge at a second time by the image recording device; - determining an edge position of the at least one portion of the at least one edge on the lithography mask based on at least one reference position at the second time; - (in particular pixel-by-pixel) determining roughness information of the at least one section of the at least one edge at the second time; - comparing the roughness information determined at the first time with the roughness information determined at the second time; and - Tracking a particle beam used to repair the lithography mask based on the comparison.

[0049] In this case, instead of (or in addition to) a reference structure, roughness information of an edge or an edge section of the lithography mask can also be used for drift correction.

[0050] In this case, an image of the relevant edge or edge section together with a surrounding periphery of the lithography mask is acquired at a first point in time. The edge position is extracted from the image and, preferably pixel by pixel, roughness information, in particular a roughness fingerprint, e.g. in the form of a roughness parameter, of the edge or edge section is determined. This can be done, for example, using an edge roughness algorithm. The roughness information can be determined in real space and / or in Fourier space. Subsequently, another image of the relevant edge or edge section together with a surrounding periphery of the lithography mask is acquired at a second point in time. The edge position is again extracted and the roughness information, in particular a roughness fingerprint, is determined.Based on this, a comparison of the roughness information between the first and second images can be made. This comparison is used to calculate particle beam drift or distortion. The particle beam can then be tracked based on this calculation.

[0051] If strong or high-resolution structural or roughness information about the edge or edge section is available, drift correction in a given spatial direction can be performed based on this information. Overall, drift correction can be performed in two spatial directions, depending on the edge's shape, by evaluating edge roughness information. It is advantageous here that the placement accuracy requirements are generally higher in the direction of strong or high-resolution structural information than in the direction of comparatively weak structural information.

[0052] According to a further embodiment, the at least one section of the at least one edge is protected by a protective layer, in particular removable by mask cleaning, wherein the protective layer preferably comprises a Mo- or a C-containing material.

[0053] It is also conceivable to protect the mask structures or edge information used for tracking in the manner described with a protective layer that can be removed by mask cleaning.

[0054] Reference structures that have less deposited material than otherwise usual reference structures or drift correction marks can be altered more significantly by a particle beam and / or process gases during the repair process than is the case with commonly used reference structures. To compensate for the failure of individual reference structures during a repair process, it may be preferable to produce a grid of small reference structures prior to the repair. Since a material, dimensioning, and / or refractive index of the reference structures is preferably selected such that neither a single reference structure nor a grid of reference structures adversely affects the lithography process (imaging process) in whole or in part, such reference structures can also remain on the lithography mask.

[0055] During a repair process for a defect in a lithography mask, the condition of the reference structures and / or the quality of the associated drift correction are checked at regular intervals and assigned a quality criterion. As soon as the quality of the reference structures and / or the drift correction falls below a certain threshold, a new set of reference structures is preferably applied to the lithography mask or provided on the lithography mask.

[0056] A location at which the new reference structures are to be deposited and / or provided can be determined by a user, preferably before the start of the repair process, when creating a repair form.

[0057] Thus, according to a further aspect, a method for analyzing and / or processing a lithography mask is provided, the method comprising the steps of: - capturing and / or providing an SEM (Scanning Electron Microscope) image of a defect site, in particular including a periphery of the lithography mask present around the defect site, an imaging structure of the lithography mask; - Providing at least one reference structure and / or a reference structure grid, in particular based on a repair plan for repairing the defect site; and - Tracking a particle beam used to repair the lithography mask on the basis of the at least one reference structure and / or the reference structure grid.

[0058] The method particularly preferably comprises: - replacing at least one existing reference structure and / or providing at least one further reference structure on the lithography mask if at least one already existing reference structure falls below a predetermined visibility threshold or has been at least partially removed from the lithography mask by the particle beam or by process gases; and - Tracking a particle beam used to repair the lithography mask also on the basis of at least one further reference structure.

[0059] The at least one additional reference structure can preferably be created at a location on a previous reference structure or at a different location on the lithography mask. The first case corresponds to a regeneration of the reference structure. Particularly preferred precursors for creating reference structures are TEOS and Cr(CO)6. It is also possible to use H2O or NO2 as additive gases.

[0060] The following scenarios are preferably conceivable for the generation of further reference structures.

[0061] Typically, the quality of the drift correction is assessed with a score between 0 and 100 (100 represents any absolute highest achievable value). As soon as a quality value falls below a certain threshold, e.g., 50, at least one additional reference structure can be written or provided on the lithography mask.

[0062] The creation of at least one further reference structure can also take the form of an emergency mechanism in which, for example, at least one further reference structure is created whenever a degradation of at least one reference structure is detected during a repair and / or the tracking of a reference structure is lost.

[0063] It is also possible to always generate at least one additional reference structure after a specific repair time has elapsed. The generation of at least one additional reference structure then preferably occurs as a fixed step during the repair of a defect. The degradation behavior of the reference structure can preferably be determined from previous test series. In particular, it can be estimated how long a reference structure can fulfill its function with sufficient quality under given process conditions.

[0064] In order to switch from one reference structure to another reference structure preferably without interruption during the repair process, a comparison between SEM images of the two reference structures is preferred.

[0065] Furthermore, a user can deposit a predetermined number of reference structures on the lithography mask and specify a position of at least one further reference structure, which is to be generated if necessary during the repair. If a repair is now carried out, the drift correction is initially carried out by the predetermined number of reference structures. During the repair, the quality of the predetermined number of reference structures and / or the quality of the drift correction is further checked and / or evaluated, preferably at intervals or continuously. If the quality of at least one of the predetermined number of reference structures and / or the quality of the drift correction falls below a respective limit value, the at least one further reference structure is generated based on the position previously specified by the user. A reference image is preferably recorded of the at least one further reference structure.Furthermore, a comparison can be made with current SEM images of the predetermined number of reference structures. The subsequent drift correction is then preferably initially performed temporarily based on the predetermined number of reference structures and the at least one additional reference structure, and then based on a correspondingly reduced number of previous reference structures with the at least one additional reference structure. It is also possible for a direct transfer to the at least one additional reference structure to occur.

[0066] The advantages of the described method can be summarized as follows: Functional drift correction is guaranteed at all times. The risk that a repair must be aborted or incorrectly performed due to the loss of at least one reference structure is thus minimized. Furthermore, the material for reference structures on the lithography mask remains below a threshold value for undisturbed optical properties of the lithography mask.

[0067] The at least one further reference structure is preferably created in such a way that the repair is impaired as little as possible. The at least one further reference structure is preferably created using the same precursor with which the previous reference structure(s) were created. The at least one further reference structure is preferably created using a different precursor than the previous reference structure(s). The process gas used for the repair is used to create the at least one further reference structure.

[0068] If a precursor suitable for electron beam-induced material deposition is used during the repair, it is possible to use the same precursor to create at least one additional reference structure. If a precursor suitable for electron beam-induced material removal is used during the repair, it is possible to use the same precursor to create at least one additional reference structure.

[0069] It is possible that the previous reference structures and the at least one further reference structure are each generated using different precursors.

[0070] The lithography mask is used in the lithography system. The lithography system is, for example, an EUV or DUV lithography system. EUV stands for "extreme ultraviolet" (EUV) and refers to a wavelength of the working light in the range of 0.1 nm to 30 nm, especially 13.5 nm. Furthermore, DUV stands for "deep ultraviolet" (DUV) and refers to a wavelength of the working light between 30 nm and 250 nm, especially 193 nm or 248 nm.

[0071] The EUV or DUV lithography system comprises an illumination system and a projection system. In particular, the EUV or DUV lithography system projects the image of a lithography mask illuminated by the illumination system (to which the method described above has been applied in whole or in part) onto a substrate coated with a light-sensitive layer and arranged in the image plane of the projection system, for example, a silicon wafer, by means of the projection system in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0072] According to a further embodiment of the method and / or the repair system, the analyzing and / or processing of the lithography mask and / or the repair process comprises a particle beam-induced etching process and / or deposition process.

[0073] The creation of structures using particle beam-induced processes is possible with high precision, especially with high spatial resolution. This allows edges to be machined with high accuracy. The machining accuracy is particularly at the atomic level, meaning the spatial resolution of the process can be in the angstrom and nanometer range. For example, edges with a pitch of 1 nm can be created. This is particularly advantageous using electron beam-induced processes (EBIP). The respective particle beam-induced process is preferably carried out with the addition of precursor gases.The precursor gases are supplied to the position to be processed on the lithography mask and the particle beam is focused onto the position, which excites and / or decomposes the precursor gases, whereby the excited species and / or decomposition products cause a deposition or etching of the surface of the lithography mask.

[0074] Precursor gases suitable for the deposition or growth of raised structures include, in particular, alkyl compounds of main group elements, metals, or transition elements. Examples include cyclopentadienyl trimethyl platinum (CpPtMe3 Me = CH4), methylcyclopentadienyl trimethyl platinum (MeCpPtMe3), tetramethyltin (SnMe4), trimethylgallium (GaMe3), ferrocene (Cp2Fe), bis-aryl chromium (Ar2Cr), and / or carbonyl compounds of 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 (Co2(CO)8), triruthenium dodecacarbonyl (Ru3(CO)) 12), iron pentacarbonyl (Fe(CO)5), and / or alkoxide compounds of main group elements, metals or transition elements, such as tetraethoxysilane (Si(OC2H5)4), tetraisopropoxytitanium (Ti(OC3H7)4), and / or halide compounds of main group elements, metals or transition elements, such as tungsten hexafluoride (WF6), tungsten hexachloride (WCl6), titanium tetrachloride (TiCl4), boron trifluoride (BCl3), silicon tetrachloride (SiCl4), and / or complexes with main group elements, metals or transition elements, such as copper bis-hexa-fluoroacetylacetonate (Cu(C3FeHO2)2), dimethyl gold trifluoroacetylacetonate (Me2Au(C3F3H4O2)), and / or organic compounds such as carbon monoxide (CO), carbon dioxide (CO2), aliphatic and / or aromatic hydrocarbons, and the like.

[0075] The precursor gas for an etching reaction may, for example, include: xenon difluoride (XeF2), xenon dichloride (XeCl2), xenon tetrachloride (XeCl4), water vapor (H2O), heavy water (D2O), oxygen (O2), ozone (O3), ammonia (NH3), nitrosyl chloride (NOCl), and / or one of the following halide compounds: XNO, XONO2, X2O, XO2, X2O2, X2O4, X2O6, where X is a halide. Further etching gases for etching one or more of the deposited test structures are described in the applicant's US patent application Ser. No.13 / 0 103 281 Other additional gases that can be used when creating the test structure include, for example, oxidizing gases such as hydrogen peroxide (H2O2), nitrous oxide (N2O), nitrogen oxide (NO), nitrogen dioxide (NO2), nitric acid (HNO3) and other oxygen-containing gases, and / or halides such as chlorine (Cl2), hydrogen chloride (HCl), hydrogen fluoride (HF), iodine (I2), hydrogen iodide (HI), bromine (Br2), hydrogen bromide (HBr), phosphorus trichloride (PCl3), phosphorus pentachloride (PCl5), phosphorus trifluoride (PF3) and other halogen-containing gases, and / or reducing gases such as hydrogen (H2), ammonia (NH3), methane (CH4) and other hydrogen-containing gases. These additional gases can be used, for example, for etching processes, as buffer gases, as passivating agents and the like.

[0076] "One" in this case is not necessarily limited to a single element. Rather, multiple elements, such as two, three, or more, may also be included. Any other counting term used here should also not be understood as implying a limitation to the exact number of elements stated. Rather, numerical deviations upwards and downwards are possible, unless otherwise stated.

[0077] The embodiments and features described for the methods apply accordingly to the proposed repair system and vice versa.

[0078] Further possible implementations of the invention also include combinations of features or embodiments described above or below with respect to the exemplary embodiments that are not explicitly mentioned. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0079] Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. The invention is explained in more detail below using preferred embodiments with reference to the accompanying figures. Fig. 1 shows a repair system with a device for particle beam-induced processing of a defect in a lithography mask according to an embodiment; Fig. 2 shows a section of an exemplary microstructured lithography mask; Fig. 3 shows the Fig. 2 shows a section of the lithography mask in a cross-sectional view along line III-III; Fig. 4 shows a schematic flow diagram of a method for analyzing and / or processing a lithography mask according to an embodiment; Fig. Figure 5 shows three different reference structures with an improved signal-to-noise ratio in a secondary electron signal; Fig. 6 shows reference structures created by a recess in the lithography mask; Fig. 7 shows three top views of a lithography mask, wherein additional reference structures are applied in each case in order to at least partially replace unusable reference structures; Fig. 8 shows a schematic representation of a lithography mask in which a roughness fingerprint of an edge portion is used as a reference structure; Fig. 9 shows a schematic flow diagram of another method for analyzing and / or processing a lithography mask according to an embodiment; and Fig. 10 shows a schematic meridional section of a projection exposure system for EUV projection lithography.

[0080] In the figures, identical or functionally equivalent elements are provided with the same reference numerals unless otherwise indicated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

[0081] In Fig. 1 is a repair system 1000 with a device 200 for particle beam-induced analysis and / or processing (e.g., etching, deposition) of a defect 126 (see Fig. 2) of a lithography mask 100. The lithography mask 100 in a lithography system 1 is shown in Fig. 10 (there also referred to as reticle 7).

[0082] The Fig. The device 200 shown in Figure 1 represents, for example, a modified scanning electron microscope 200. An electron beam 202 is used as a particle beam for imaging, analyzing, and / or processing the lithography mask 100. The device 200 is largely arranged in a vacuum housing 204. A space enclosed by the vacuum housing 204 is maintained at a specific gas pressure by a vacuum pump 206.

[0083] The lithography mask 100 to be repaired is arranged on a sample table 208. The sample table 208 is configured, for example, to adjust the position of the lithography mask 100 in three mutually perpendicular spatial directions x, y, z and, for example, additionally in three mutually perpendicular rotational axes with an accuracy of a few nanometers.

[0084] The device 200 has an electron column 210. The electron column 210 includes an electron source 212 for providing the electron beam 202. The electron column 210 further includes electron or beam optics 214. The electron source 212 generates the electron beam 202, and the electron or beam optics 214 focuses the electron beam 202 and directs it onto the lithography mask 100 at the exit of the column 210. The electron column 210 also includes a deflection unit 216 (scanning unit 216) configured to guide (scan) the electron beam 202 across the surface of the lithography mask 100. Instead of the deflection unit 216 (scanning unit 216) arranged in the column 210, a deflection unit (scanning unit)—not shown—arranged outside the column 210 can also be used.

[0085] The device 200 further comprises a detector 218 (here also referred to as an "image capture device") for detecting the secondary electrons and / or backscattered electrons generated by the incident electron beam 202 in the material of the lithography mask 100. The detector 218 is, for example, as shown, arranged in the electron column 210 in a ring around the electron beam 202. Alternatively and / or in addition to the detector 218, the device 200 may also have other / further detectors for detecting secondary electrons and / or backscattered electrons (in Fig. 1 not shown).

[0086] The device 200 can optionally also include a gas supply unit 220 for supplying process gas to the surface of the lithography mask 100. The gas supply unit 220 has, for example, a valve 222 and a gas line 224. The electron beam 202 directed by the electron column 210 to a location on the surface of the lithography mask 100 can, in cooperation with the process gas supplied from the outside by the gas supply unit 220 via the valve 222 and the gas line 224, perform an electron beam-induced processing (EBIP). This includes, in particular, the deposition and / or etching of material.

[0087] The device 200 also includes a computing device 226, such as a computer, with a control device 228 and a generating device 230. The computing device 226 is in the example of Fig. 1 arranged outside the vacuum housing 204.

[0088] The control device 228 serves, for example, to control the device 200. For example, the control device 228 controls the provision of the electron beam 202 by controlling the electron column 210. The control device 228 controls, among other things, the guidance of the electron beam 202 over the surface of the lithography mask 100 by controlling the scanning unit 216. The control device 228 can also control the gas supply unit 220 for providing process gas.

[0089] The generation device 230 receives measurement data from the detector 218 and / or other detectors of the device 200 and generates images from the measurement data that can be displayed on a monitor (not shown). The spatial resolution of the generated images is, for example, in the range of a few nanometers.

[0090] In Fig. 2 shows a section of an exemplary microstructured lithography mask 100. Fig. 3 shows the Fig. 2 shown section of the lithography mask 100 in a cross-sectional view along line III-III in Fig. 2. The lithography mask 100 has a microstructure 104. For example, the microstructure 104 has one or more raised imaging structures 106 with intermediate lower regions 108 (e.g., trenches 108). The raised imaging structures 106 have edges 110, of which Fig. 2 two are provided with a reference symbol. The lower regions 108 have, in particular, one or more first segments 112 (where reference is made here to a "segment," this could also be referred to as a "section"). Furthermore, the raised imaging structures 106 have one or more second segments 114, which are raised relative to the one or more first segments 112. In Fig. 2, two second segments 114 are shown merely as an example.

[0091] The microstructured lithography mask 100 also has, for example, a flat shape with a main extension plane E (xy plane in Fig. 2 and Fig. 4). A direction perpendicular to the main extension plane E is referred to as a height direction z of the lithography mask 100.

[0092] As shown in the cross-section of Fig. 3, the at least one first segment 112 of the lithography mask 100 has a first height H1 with respect to the height direction z of the lithography mask 100. Furthermore, the at least one second segment 114 of the lithography mask 100 has a second height H2 with respect to the height direction z, which is greater than the first height H1. In particular, the at least one second segment 114 rises by a height ΔH = H2 - H1 above a surface 116 of the at least one first segment 112. In other words, a surface 118 of the at least one second segment is arranged by the height ΔH above the surface 116 of the at least one first segment 112.

[0093] The edges 110 of the at least one second segment 114 each have in particular an edge wall 120 ( Fig. 3), which are, for example, parallel to the height direction z of the lithography mask 100 and perpendicular to the main extension plane E ( Fig. 2) of the lithography mask 100.

[0094] The lithography mask 100 has, for example, a substrate 122 ( Fig. 3) on which the one or more raised elements 106 (imaging structure) forming the at least one second segment 114 are arranged. An exposed surface of the substrate 122 forms, for example, the surface 116 of the at least one first segment 112.

[0095] Although not shown in the figures, one or more layers (coatings) may also be arranged on the substrate 122 of the lithography mask 100. If the lithography mask 100 is, for example, an EUV lithography mask, then a protective layer (also referred to as a capping layer), such as a Ru capping layer, may be arranged on the substrate 122. If one or more layers are arranged on the substrate 122, exposed regions of an uppermost one of these one or more layers may form the surface 116 of the at least one first segment 112.

[0096] The lower regions 108, e.g., the substrate 122, and the one or more raised elements 106 of the lithography mask 100 may comprise a different material or the same material. In other words, the at least one first segment 112 and the at least one second segment 114 may comprise different materials or the same material. For example, the exposed surface 116 of the at least one first segment 112 and the exposed surface 118 of the at least one second segment 114 may comprise different materials or the same material.

[0097] Furthermore, the at least one first segment 112 of the lithography mask 100 may comprise a light-transmitting or light-reflecting material, and the at least one second segment 114 of the lithography mask 100 may comprise a light-absorbing material.

[0098] The microstructured lithography mask 100 is, for example, an EUV or a DUV lithography mask, ie it is designed for use in an imaging process in an EUV or DUV lithography system (such as the one shown in Fig. 10 shown lithography system 1). For example, the image of the lithography mask 100 on a wafer 13 (see Fig. 10) The working light used by the lithography system 1 has a wavelength of between 0.1 nm and 30 nm, preferably between 13 and 14 nm, in particular 13.5 nm. Additionally or alternatively, the lithography system 1 can have a numerical aperture greater than 0.3, in particular greater than 0.33, preferably greater than 0.5, for example 0.55, for example between 0.3 and 0.75, in particular greater than 0.6, preferably greater than 0.7.

[0099] Furthermore, the lithography mask 100 in the present case has a reference structure 124. The at least one reference structure 124 can be formed by depositing a material on the lithography mask 100 using a process gas. Alternatively, the at least one reference structure 124 can be formed by providing a recess and / or a notch in the lithography mask 100, in particular by etching away using a process gas.

[0100] The reference structure 124 is provided in particular to enable a drift correction of the particle beam 202 during a repair process. Such a repair process is to be carried out, for example, when the imaging structure 106 has at least one defect 126 to be repaired. The reference structure 124 is then preferably provided in the immediate periphery of the defect 126 in order to enable a drift correction during the repair of the defect 126 by the particle beam 202. The reference structure 124 therefore preferably serves to adjust the particle beam 202 according to the procedure described below with reference to Fig. 4, in particular to enable drift correction in at least one of the spatial directions x, y.

[0101] Fig. 4 shows a flowchart of the method for analyzing and / or processing the lithography mask 100.

[0102] In a step S1, the at least one reference structure 124 is provided on the lithography mask 100 such that the reference structure 124 is not imaged when the lithography mask 100 is imaged on a wafer 13 in the lithography system 1. The provision S1 can preferably be performed depending on at least one parameter of the lithography system 1, wherein the parameter is selected from a wavelength of a working light of the lithography system 1 and / or an intensity of a working light of the lithography system 1 and / or a numerical aperture (NA) in the lithography system 1.

[0103] In a step S2, an image of the reference structure 124 is generated using the particle beam 202 using the detector 218.

[0104] In a step S3, the particle beam 202 is further controlled to analyze and / or process the lithography mask 100 depending on the image of the reference structure 124 generated using a particle beam 202.

[0105] The provision S1 of the reference structure 124 preferably takes place depending on or by manipulating and / or adapting and / or specifically designing a volume and / or a basic geometry and / or a refractive index and / or a material and / or a material composition of the reference structure 124 and / or a distance of the reference structure 124 from at least a part of the imaging structure 106 of the lithography mask 100.

[0106] Exemplary reference structures 124, which are not imaged on the wafer 13, are shown in the Fig. 5 to 7 are shown as examples and are explained in more detail below.

[0107] The reference structure 124 preferably has a maximum dimension, measured in particular parallel to the main extension plane of the lithography mask 100, of less than or equal to 60 nm, preferably less than or equal to 50 nm, preferably less than or equal to 40 nm, preferably less than or equal to 30 nm, preferably less than or equal to 20 nm. The refractive index n + i*k of the reference structure 124 preferably has a phase-shifting component n and an absorbing component k. The phase-shifting component n preferably differs from the value for the vacuum by at most 0.045. The absorbing component k preferably differs from the value for the vacuum by at most 0.02.

[0108] Fig. 5 shows three different reference structures 124, each with an improved signal-to-noise ratio, at least in the secondary electron signal in the detector 218. This improvement can be influenced, for example, by the material and / or material composition of the respective reference structure 124. One or more of the following elements: Si, Ba, Ce, La, Br, Rb, Be, Sr, P, S, Ca, Y, B, Sc, Zr, Gd, Nd, C, Ti, Se, F, Cl can be used as a material or in a material composition.

[0109] According to Fig. 5(a), the material of the reference structure 124 is selected such that a secondary electron current I(SE)2 of the reference structure 124 is greater than a secondary electron current I(SE)1 of a region 502 of the lithography mask 100 surrounding the reference structure 124. Furthermore, the material of the reference structure 124 is selected such that a current of backscattered electrons I(BSE)2 of the reference structure 124 is smaller or greater than a current of backscattered electrons I(BSE)1 of the region 502 surrounding the reference structure 124. The respective secondary electron signal is generated by the primary electron signal PE of the particle beam 202. The material is preferably selected such that a work function of electrons from the two materials is selected to be as different as possible.

[0110] According to Fig. 5(b), a reference structure 124 has an auxiliary layer 500, by which the secondary electron current I(SE)4 and / or the backscattered electron current I(BSE)4 of the at least one reference structure 124 is amplified. The auxiliary layer 500 is preferably a thin auxiliary layer deposited on the surface of the lithography mask 100. The reference structure 124 is deposited onto the auxiliary layer 500. The material of the auxiliary layer 500 is selected such that the difference in the secondary electron current I(SE)4 and / or the backscattered electron current I(BSE)4 of the reference structure 124 compared to the secondary electron current I(SE)3 and / or the backscattered electron current I(BSE)3 of the auxiliary layer 500 is maximized. Preferably: I(SE)3 << I(SE)4 and / or I(BSE)3 << I(BSE)4 or I(BSE)3 >> I(BSE)4.

[0111] According to Fig. 5(c), the geometry of the reference structure 124 is selected such that the work function of the electrons is reduced and the yield of secondary electrons is thereby increased, particularly compared to a background 502 provided by the lithography mask 100. For example, the reference structure 124 is selected such that it has at least one tip and / or a cone shape. Preferably, the following applies: I(SE)6 << I(SE)3.

[0112] Fig. 6 shows an embodiment in which the reference structure 124 is provided by providing a recess or notch 600. Fig. 6(a) shows the case of a recess formed by chemical or mechanical action with respect to a surface O of the lithography mask 100. Fig. 6(b) shows an embodiment in which the recess and / or the notch 600 is filled by a material 602 deposited and / or deposited therein, preferably flush with a surface O of the lithography mask 100.

[0113] Fig. 7(a) to 7(c) each show a schematic representation of the lithography mask 100 in a plan view, wherein the Fig. 7(a) to 7(c) each show the lithography mask 100 at different times of a repair process. At a first time, which is shown in Fig. As shown in Figure 7(a), four reference structures 124 are provided in the immediate periphery around the defect location 126 of the mapping structure 106. The four displayed boxes 700 mark the location where new reference structures can be written or provided as needed during the repair process. The positions of the boxes 700 can be defined by a user, for example, with the aid of software on a user interface.

[0114] During the repair process, due to the particle beam 202 and / or process gases, one or more of the reference structures 124 may be ablated and thus no longer be available with sufficient accuracy for drift correction. This is Fig. 7(b), where the removed or defective reference structures are identified by reference numeral 124b. Consequently, new or additional reference structures 124c are provided on the lithography mask 100 to enable drift correction that is as uninterrupted and precise as possible.

[0115] According to Fig. 7(c) the defective reference structures 124b are no longer shown.

[0116] Alternatively or additionally, in order to analyze the lithography mask 100 and to process and / or use it based on the analysis, it may be necessary to detect contours of the microstructures 104, e.g., the edges 110 of the second raised segments 114. For example, it may be necessary to determine a position and / or (e.g., two-dimensional) geometric shape of the edges 110 of the second segments 114.

[0117] Fig. 8 shows a top view of a lithography mask 100 in which at least one roughness information item of an edge 110 or an edge section 900 is used as a replacement for a (possibly non-existent) reference structure 124 for drift correction. As an example, a line-and-space structure is shown as the imaging structure 106 on a lithography mask 100.

[0118] Such a method is described with reference to the schematic flow diagram in Fig. 9 is explained in more detail.

[0119] In a step S51, at least one section 900 of the at least one edge 110 is detected at a first time by an image recording device or a detector 218. The detected edge section 900 contains a roughness fingerprint, i.e., individualized roughnesses that allow a clear localization of the edge section 900. Roughness here is the (e.g., vertical) deviation from the edge that is specified by the mask design. The roughness is in Fig. 8 is illustrated by an arrangement of serrated structures with different serration sizes.

[0120] In a step S52, an edge position of the at least one section 900 of the at least one edge 110 on the lithography mask 100 is determined on the basis of at least one reference position at the first time.

[0121] In a step S53, roughness information of the at least one section 900 of the at least one edge 110 at the first time is determined. In this step, in particular, the aforementioned roughness fingerprint is determined, for example, depending on the spike sizes contained in the acquired image.

[0122] In a step S54, the at least one section 900 of the at least one edge 110 is captured at a second time by the image recording device.

[0123] In a step S55, an edge position of the at least one section 900 of the at least one edge 110 on the lithography mask 100 is determined on the basis of at least one reference position at the second time.

[0124] In a step S56, roughness information of the at least one section 900 of the at least one edge 110 is determined at the second time.

[0125] In step S57, the roughness information determined at the first time is compared with the roughness information determined at the second time. The comparison of the roughness information or roughness fingerprints can be performed by pixel-by-pixel image comparison or by comparing a respective transformation of the roughness information at the first and second time points.

[0126] In a step S58, a particle beam 202 used to repair the lithography mask 100 is tracked on the basis of the comparison.

[0127] The at least one section 900 of the at least one edge 110 can be protected by a protective layer, in particular removable by mask cleaning. The protective layer preferably comprises a molybdenum (Mo) or carbon (C)-containing material.

[0128] Fig. 10 shows an embodiment of a projection exposure system 1 (lithography system), in particular an EUV lithography system. One embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, an illumination optics 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the remaining illumination system 2. In this case, the illumination system 2 does not include the light source 3.

[0129] A reticle 7 (here also referred to as a lithography mask 100) arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced via a reticle displacement drive 9, particularly in a scanning direction.

[0130] In the Fig. For illustrative purposes, Figure 10 shows a Cartesian coordinate system with an x-direction x, a y-direction y, and a z-direction z. The x-direction x runs perpendicular to the plane of the drawing. The y-direction y runs horizontally, and the z-direction z runs vertically. The scanning direction runs in the Fig. 10 along the y-direction y. The z-direction z runs perpendicular to the object plane 6.

[0131] The projection exposure system 1 comprises a projection optics 10. The projection optics 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 runs parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

[0132] A structure on the reticle 7 is imaged onto a light-sensitive layer of the wafer 13 arranged in the image plane 12 in the region of the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, in particular along the y-direction y, via a wafer displacement drive 15. The displacement of the reticle 7, on the one hand, via the reticle displacement drive 9, and the displacement of the wafer 13, on the other hand, via the wafer displacement drive 15, can be synchronized with each other.

[0133] The light source 3 is an EUV radiation source. The light source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation 16 has, in particular, a wavelength in the range between 5 nm and 30 nm. The light source 3 can be a plasma source, for example, an LPP source (Laser Produced Plasma) or a DPP source (Gas Discharged Produced Plasma). It can also be a synchrotron-based radiation source. The light source 3 can be a free-electron laser (FEL).

[0134] The illumination radiation 16 emanating from the light source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 17 can be exposed to the illumination radiation 16 at grazing incidence (GI), i.e., at angles of incidence greater than 45°, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector 17 can be structured and / or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light.

[0135] After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the light source 3 and the collector 17, and the illumination optics 4.

[0136] The illumination optics 4 comprises a deflecting mirror 19 and, downstream of this in the beam path, a first facet mirror 20. The deflecting mirror 19 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first facet mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugated to the object plane 6 as the field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, which can also be referred to as field facets. Of these first facets 21, Fig. 10 only some examples are shown.

[0137] The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partially circular edge contour. The first facets 21 can be designed as flat facets or, alternatively, as convexly or concavely curved facets.

[0138] As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 themselves can also be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 20 can, in particular, be designed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1.

[0139] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction y.

[0140] In the beam path of the illumination optics 4, a second facet mirror 22 is arranged downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1 614 008 B1, and US Pat. No. 6,573,978.

[0141] The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

[0142] The second facets 23 can also be macroscopic facets, which can, for example, be round, rectangular, or hexagonal, or alternatively facets composed of micromirrors. Reference is also made to DE 10 2008 009 600 A1 in this regard.

[0143] The second facets 23 can have planar or alternatively convex or concave curved reflection surfaces.

[0144] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a fly's-eye integrator.

[0145] It may be advantageous to arrange the second facet mirror 22 not exactly in a plane that is optically conjugate to a pupil plane of the projection optics 10. In particular, the second facet mirror 22 can be arranged tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 10 2017 220 586 A1.

[0146] With the help of the second facet mirror 22, the individual first facets 21 are imaged into the object field 5. The second facet mirror 22 is the last beam-forming mirror or actually the last mirror for the illumination radiation 16 in the beam path before the object field 5.

[0147] In a further embodiment of the illumination optics 4 (not shown), a transmission optics can be arranged in the beam path between the second facet mirror 22 and the object field 5, which transmission optics contributes in particular to the imaging of the first facets 21 into the object field 5. The transmission optics can have exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optics can in particular comprise one or two mirrors for normal incidence (NI mirrors, normal incidence mirrors) and / or one or two mirrors for grazing incidence (GI mirrors, grazing incidence mirrors).

[0148] The illumination optics 4 has in the version shown in the Fig. 10, after the collector 17 there are exactly three mirrors, namely the deflection mirror 19, the first facet mirror 20 and the second facet mirror 22.

[0149] In a further embodiment of the illumination optics 4, the deflection mirror 19 can also be omitted, so that the illumination optics 4 can then have exactly two mirrors after the collector 17, namely the first facet mirror 20 and the second facet mirror 22.

[0150] The imaging of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optics into the object plane 6 is usually only an approximate imaging.

[0151] The projection optics 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

[0152] In the Fig. In the example shown in Figure 10, the projection optics 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or a different number of mirrors M1 are also possible. The projection optics 10 is a doubly obscured optic. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics 10 has an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6, for example, 0.7 or 0.75.

[0153] Reflection surfaces of the mirrors Mi can be designed as freeform surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one rotational symmetry axis of the reflection surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0154] The projection optics 10 has a large object-image offset in the y-direction y between a y-coordinate of a center of the object field 5 and a y-coordinate of the center of the image field 11. This object-image offset in the y-direction y can be approximately as large as a z-distance between the object plane 6 and the image plane 12.

[0155] The projection optics 10 can, in particular, be anamorphic. It has, in particular, different magnifications βx, βy in the x and y directions x, y. The two magnifications βx, βy of the projection optics 10 are preferably (βx, βy) = (+ / - 0.25, + / - 0.125). A positive magnification β means imaging without image inversion. A negative sign for the magnification β means imaging with image inversion.

[0156] The projection optics 10 thus leads to a reduction in the ratio 4:1 in the x-direction x, i.e. in the direction perpendicular to the scanning direction.

[0157] The projection optics 10 leads to a reduction of 8:1 in the y-direction y, i.e. in the scanning direction.

[0158] Other magnifications are also possible. Magnifications with the same sign and absolutely identical in the x and y directions (x, y), for example, with absolute values ​​of 0.125 or 0.25, are also possible.

[0159] The number of intermediate image planes in the x- and y-directions x, y in the beam path between the object field 5 and the image field 11 can be the same or can be different, depending on the design of the projection optics 10. Examples of projection optics with different numbers of such intermediate images in the x- and y-directions x, y are known from US 2018 / 0074303 A1.

[0160] Each of the second facets 23 is assigned to exactly one of the first facets 21 to form a respective illumination channel for illuminating the object field 5. This can, in particular, result in illumination according to the Köhler principle. The far field is divided into a plurality of object fields 5 using the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 assigned to them.

[0161] The first facets 21 are each imaged onto the reticle 7 by an associated second facet 23, superimposed on one another, to illuminate the object field 5. The illumination of the object field 5 is, in particular, as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0162] By arranging the second facets 23, the illumination of the entrance pupil of the projection optics 10 can be geometrically defined. By selecting the illumination channels, in particular the subset of the second facets 23 that guide light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting or illumination pupil fill.

[0163] A likewise preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by redistributing the illumination channels.

[0164] Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optics 10 are described below.

[0165] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0166] The entrance pupil of the projection optics 10 cannot usually be precisely illuminated with the second facet mirror 22. When imaging the projection optics 10, which images the center of the second facet mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found in which the pairwise determined distance of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in spatial space. In particular, this surface exhibits a finite curvature.

[0167] It is possible that the projection optics 10 have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second facet mirror 22 and the reticle 7. With the help of this optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

[0168] In the Fig. In the arrangement of the components of the illumination optics 4 shown in Figure 10, the second facet mirror 22 is arranged in a surface conjugate to the entrance pupil of the projection optics 10. The first facet mirror 20 is arranged tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the deflection mirror 19. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the second facet mirror 22.

[0169] The reference structure 124 described here ( Fig. 2) on the lithography mask 7, 100 is recorded in the image on the wafer 13 ( Fig. 10) does not occur, since the illumination radiation 16 is not influenced or only uncritically influenced for the imaging process due to the reference structure 124.

[0170] Although the present invention has been described using exemplary embodiments, it can be modified in many ways. LIST OF REFERENCE SYMBOLS 1 projection exposure system 2 Lighting system 3 Light source 4 Lighting optics 5 Object field 6 Object level 7 reticles 8 reticle holders 9 Reticle displacement drive 10 Projection optics 11 Image field 12 Image plane 13 wafers 14 wafer holders 15 Wafer relocation drive 16 Illumination radiation 17 Collector 18 Intermediate focal plane 19 Deflecting mirrors 20 first facet mirror 21 first facet 22 second facet mirror 23 second facet 100 lithography masks 104 Microstructure 106 Image structure 108 area 110 edge 112 segments 114 segments 116 Surface 118 Surface 120 wall 122 Substrat 124 Reference structure 124b defective reference structure 124c further reference structure 126 Defect location 200 repair device 202 particle beam 204 housings 206 Pump 208 Sample table 210 electron column 212 Electron source 214 Electron or beam optics 216 Deflection unit 218 Detector or image recording device 220 Gas Supply Unit 222 Valve 224 gas pipeline 226 Calculating device 228 Control device 230 generating facility 500 auxiliary shift 502 area or underground 600 depression or notch 602 deposited material 700 boxes 800 threshold 900 edge section 1000 Repair System D1-D5 deposition height E Main extension level H Height H1 height H2 height ΔH height I(SE)1 secondary electron current I(SE)2 secondary electron current I(SE)3 secondary electron current I(SE)4 secondary electron current I(SE)5 secondary electron current I(SE)6 secondary electron current I(BSE)1 current of backscattered electrons I(BSE)2 current of backscattered electrons I(BSE)3 current of backscattered electrons I(BSE)4 current of backscattered electrons I(BSE)5 current of backscattered electrons I(BSE)6 current of backscattered electrons M1 mirror M2 mirror M3 mirror M4 mirror M5 mirror M6 mirror O Surface S1-S3 process steps S51-S58 Process steps x, y, z direction QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2008 009 600 A1 [0138, 0142] US 2006 / 0132747 A1

[0140] EP 1 614 008 B1

[0140] US 6,573,978

[0140] DE 10 2017 220 586 A1

[0145] US 2018 / 0074303 A1

[0159]

Claims

[1] Method for analyzing and / or processing a lithography mask (100) for a lithography system (1), comprising the method: - Providing (S1) a reference structure (124) on the lithography mask (100) such that when the lithography mask (100) is imaged onto a wafer (13) using the lithography system (1), the reference structure (124) is not imaged; - Generating (S2) an image of the reference structure (124) using a particle beam (202); and - Control (S3) of the particle beam (202) to analyze and / or process the lithography mask (100) depending on the generated image of the reference structure (124). [2] Method according to claim 1, wherein the provision (S1) of the reference structure (124) is performed depending on at least one parameter of the lithography system (1), wherein the parameter is selected from a wavelength of a working light (16) of the lithography system (1) and / or an intensity of a working light of the lithography system (1) and / or a numerical aperture of the lithography system (1). [3] Method according to claim 1 or 2, wherein the provision (S1) of the reference structure (124) is carried out in such a way that it is not imaged on the wafer (13) by selecting a volume and / or a basic geometry and / or a refractive index and / or a material and / or a material composition of the reference structure (124) and / or a distance of the reference structure (124) to at least a part of an imaging structure (106) of the lithography mask (100) which is imaged on the wafer (13) using the lithography system (1). [4] Method according to any one of claims 1-3, wherein the reference structure (124) is formed by depositing a material on the lithography mask (100) using a process gas, or wherein the reference structure (124) is formed by a depression and / or an indentation in the lithography mask (100) by etching using at least one process gas. [5] Method according to one of claims 1-4, wherein the imaging structure (106) has at least one defect (126) to be repaired by means of the particle beam (202), wherein the reference structure (124) is provided in the immediate periphery of the defect (126). [6] Method according to one of claims 1-5, wherein a maximum dimension of the reference structure (124), measured in particular parallel to a principal extension plane of the lithography mask (100), is less than or equal to 60 nm, preferably less than or equal to 50 nm, preferably less than or equal to 40 nm, preferably less than or equal to 30 nm, preferably less than or equal to 20 nm. [7] Method according to one of claims 1-6, wherein a maximum dimension of the reference structure (124), in particular measured parallel to the main extension plane of the lithography mask (100), is selected to be smaller than a minimum dimension of the imaging structure (106), in particular measured parallel to the main extension plane of the lithography mask (100). [8] Method according to one of claims 3-7, wherein the refractive index (n, k) of the reference structure (124) has a phase-shifting component (n) and an absorbing component (k), wherein the phase-shifting component (n) of the refractive index has a difference to vacuum of at most 0.045, and wherein the absorbing component of the refractive index has a difference to vacuum of at most 0.

02. [9] Method according to any one of claims 3-8, wherein the material comprises one or more of the following elements Si, Ba, Ce, La, Br, Rb, Be, Sr, P, S, Ca, Y, B, Sc, Zr, Gd, Nd, C, Ti, Se, F, Cl. [10] Method according to any one of claims 3-9, wherein the material of the reference structure (124) is selected such that a secondary electron current (I(SE)2) of the reference structure (124) is greater than a secondary electron current (I(SE)1) of a region (502) surrounding the reference structure (124) of the lithography mask (100), and / or that a current of backscattered electrons (I(BSE)2) of the reference structure (124) is less or greater than a current of backscattered electrons (I(BSE)1) of a region (502) surrounding the reference structure (124) of the lithography mask (100). [11] Method according to claim 10, wherein the reference structure (124) has an auxiliary layer (500) by which the secondary electron current (I(SE)4) and / or the backscattered electron current (I(BSE)4) of the at least one reference structure (124) is enhanced. [12] Method according to any one of claims 1-11, wherein the reference structure (124) has a conical shape and / or at least one tip. [13] Method according to one of claims 4-12, wherein the depression and / or the indentation (600) is filled by a material (602) deposited and / or laid down therein, preferably flush with a surface of the lithography mask (100). [14] Method according to one of the preceding claims, wherein the working light used in imaging the lithography mask (100) on the wafer (13) has a wavelength of between 0.1 nm and 30 nm, preferably between 13 and 14 nm, in particular 13.5 nm and / or the lithography system has a numerical aperture greater than 0.3, in particular greater than 0.33, preferably greater than 0.5, for example 0.55, for example between 0.3 and 0.75, in particular greater than 0.6, preferably greater than 0.

7. [15] Repair system (1000) for carrying out a particle beam-based repair process of a lithography mask (100), comprising: - a repair device (200); and - a lithography mask (100) which can be analyzed and / or processed by means of the repair device (200) according to the method of one of claims 1-14. [16] Method for analyzing and / or processing a lithography mask (100) for a lithography system (1), the lithography mask (100) comprising an imaging structure (106) to be imaged onto a wafer (13) with at least one edge (110), the method comprising the steps: - Capturing at least one section (900) of at least one edge (110) at a first time point by an image acquisition device (218); - Determining an edge position of the at least one section (900) of the at least one edge (110) on the lithography mask (100) based on at least one reference position at the first time; - Determining roughness information of at least one section (900) of at least one edge (110) at the first time point; - Capturing at least one section (900) of at least one edge (110) at a second time point by the image acquisition device (218); - Determining an edge position of the at least one section (900) of the at least one edge (110) on the lithography mask (100) based on at least one reference position at the second time point; - Determining roughness information of at least one section (900) of at least one edge (110) at the second time point; - Comparing the roughness information determined at the first time point with the roughness information determined at the second time point; and - Tracking of a particle beam (202) used to repair the lithography mask (100) based on the comparison. [17] Method according to claim 16, wherein the at least one section (900) of the at least one edge (110) is protected by a protective layer, in particular removable by mask cleaning, wherein the protective layer preferably comprises a Mo- or a C-containing material. [18] Lithography mask (100) which is analyzed and / or processed according to a method according to one of the preceding claims.

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