Method and apparatus for processing lithographic mask

Abstract

To address the problem of improving the known approaches for repairing and respectively processing masks, in particular when defects with extensive and / or small structures are present.SOLUTION: Methods for repairing a defect of a lithographic mask with a particle beam are described. One such method can comprise the following steps: processing the defect with the particle beam with a first set of processing parameters; processing the defect with the particle beam with a second set of processing parameters; wherein at least one parameter from the first set of processing parameters differs from the second set of processing parameters.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This patent application claims priority to German patent application DE 10 2020 208 183.2 entitled "Verfahren und Vorrichtung zum Bearbeiten einer lithograghischen Maske" and filed with the German Patent and Trademark Office, which is expressly incorporated herein by reference.

[0002] The present invention relates to a method and apparatus for processing a lithography mask, and more particularly to a method and apparatus for repairing defects in a lithography mask. [Background technology]

[0003] As a result of the constantly increasing integration density of microelectronics, lithography masks are required to image ever-smaller structural features into the photoresist layer of the wafer. To meet this requirement, exposure wavelengths are constantly shifting to shorter wavelengths. Currently, argon fluoride (ArF) excimer lasers are primarily used for exposure, emitting light at a wavelength of 193 nm. Intensive research is being conducted on light sources emitting in the extreme ultraviolet (EUV) wavelength range (10 nm to 15 nm) and corresponding EUV masks. To improve the resolution capabilities of the wafer exposure process, several variants of the conventional binary photolithography mask are simultaneously being developed. Examples include phase masks or phase-shift masks and masks for multiple exposures.

[0004] Due to the constantly decreasing dimensions of structural elements, lithography masks, especially photolithography masks, cannot always be manufactured defect-free. Because photomask manufacturing is expensive, defective photomasks are repaired whenever possible. There are two important groups of defects in photolithography masks. First, there are dark defects. Dark defects are areas where absorber or phase-shifting material is present but should be removed. These defects are preferably repaired by removing the excess material with the help of a local etching process. Second, there are so-called white defects. These are defects on the photomask that, upon light exposure in a wafer stepper or wafer scanner, have a greater optical transmittance than a similar reference location without a defect. During the mask repair process, these defects can be removed by depositing a material with appropriate optical properties. Ideally, the optical properties of the material used for repair should correspond to those of the absorber or phase-shifting material.

[0005] Defects can be further subdivided into printable defects and non-printable defects. During wafer exposure, a photomask with printable defects or printable mask defects will produce a pattern on the wafer that does not meet all of the design conditions. In contrast, during wafer exposure, a mask with one or more non-printable defects will produce a pattern on the wafer that meets all of the design conditions.

[0006] The applicant develops and manufactures measurement devices for analyzing photolithography masks, for example, sold under the trade names PROVE®, AIMS™, or WLCD. Additionally, the applicant develops and sells repair devices for photolithography masks, known for example under the trade names MeRiT®, RegC®, or ForTune®.

[0007] Repair is typically performed with a particle beam (e.g., including electrons, ions, atoms, molecules, and / or photons) with specific, characteristic beam parameters. Together with a precursor gas to which the mask is exposed, the particle beam excites local chemical reactions in the mask under defined process parameters. In this case, material can be locally deposited on the mask, or material can be locally etched from the mask.

[0008] The same particle beam with the same specific beam parameters is generally used not only for the actual repair process in which defects are removed, but also for prior, downstream, or intermittent inspection or characterization of the mask. For example, an image of the mask can be recorded (e.g., with the help of an electron beam) to ascertain a so-called repair shape that describes the defects to be repaired (the repair shape usually indicates the pixels to be exposed for repair, and optionally the exposure duration of individual pixels, or some other measure of the local depth of the defect, and optionally further parameters for repairing the pixels).

[0009] The defects are then removed according to the repair shape, for example, by pixel-by-pixel exposure with the particle beam, with the aid of a particle beam and an appropriate precursor gas under predetermined process parameters. The image information can then also be used to determine whether a particular repair goal has been achieved.

[0010] An apparatus and a corresponding method for repairing defects are disclosed in WO2009106288A2. During a processing step, an electron beam is used to remove the defects with the help of electron-beam-induced local chemical reactions. In a separate measurement step, the electron beam can be used to verify whether an endpoint has been reached with the help of backscattered electron detection. In the measurement step, it is possible to choose a different dwell time, a different sequence, a repetition rate ("refresh time") of the electron beam, or a different gas flow rate compared to during the processing process.

[0011] The present invention addresses the problem of improving known techniques for repairing and respectively processing masks, especially when defects with extensive and / or small structures are present. Summary of the Invention

[0012] This problem is at least partially solved by various aspects of the present invention.

[0013] According to a first aspect, there is provided a method for particle beam repair of defects in a lithography mask, the defect being treated with the particle beam using a first set of processing parameters, the same defect being treated with a second set of processing parameters, and at least one parameter from the first set of processing parameters being different from the second set of processing parameters.

[0014] Instead of the routine procedure of the prior art in which defects are uniformly removed by a particle beam using exactly the same processing parameters, the defects are treated, for example, using different processing parameters. This makes it possible, for example, to optimize the processing parameters in different work steps targeting different regions of the defect (e.g., adjacent / neighboring or overlapping regions) to the requirements of each work step or region. This can improve the quality and / or speed of the repair. Therefore, even in the case of defects with fine structures, it is possible to achieve high quality with a minimum processing time, for example, by processing only the fine structure of the defect with high precision (and at a low speed), while the coarse structure of the defect is processed with an appropriate (sufficient) lower precision (and in return, a higher speed).

[0015] The processes using the first and second sets of process parameters may include local particle beam-induced etching and / or deposition and should be distinguished from pure diagnostic processes in particular. Therefore, the process parameters may be varied within the entire process, including (sub)processes, i.e., "processing using the first set of process parameters" and "processing using the second set of process parameters."

[0016] By way of example, a first section of the defect may be repaired (exclusively) with the aid of a first set of processing parameters. By way of example, a second section of the defect may be repaired (exclusively) with the aid of a second set of processing parameters, said second section not overlapping (being separate during projection onto the mask plane) with the first section.

[0017] The definition of the repair shape and / or the treatment of the defect can be performed pixel by pixel (e.g., according to the repair shape). A typical pixel size for creating the repair shape is, for example, 1.5 nm × 1.5 nm (however, other sizes, for example, 1 nm × 1 nm, 2 nm × 2 nm, 3 nm × 3 nm, etc., can also be used). Treatment with particle beams having a range of similar sizes (i.e., corresponding areas or effective diameters when impinging on the defect) is possible. However, it can also be advantageous to perform exposure on multiple pixels at least partially simultaneously, i.e., to choose a particle beam size (i.e., area or effective diameter when impinging on the defect) that is correspondingly larger than the pixel size used to create the repair shape (typical particle beam sizes can be, for example, in the range of 6 nm × 6 nm or more when an electron beam with an energy of, for example, 400 eV to 1 keV is used). Each pixel or each region of a pixel (depending on the effective diameter of the particle beam used, respectively) is exposed for a specific duration (exposure duration or "dwell time"). The exposure is repeated in successive cycles until the required exposure dose is achieved. Hereinafter, the term pixel size refers to the pixel size or the size of the particle beam used to create the repair shape, depending on the context.

[0018] According to a further aspect of the present invention, at least one first pixel (first region of pixels) of the defect can then be processed using a first set of processing parameters. At least one other second pixel (second region of pixels) of the defect can then be processed using a second set of processing parameters. For example, classification can be performed based on conditions to be met for individual pixels. For example, one particular pixel (first set of pixels) that is important and therefore intended to be processed accurately can be processed using corresponding processing parameters that provide the desired accuracy. For example, another pixel (second set of pixels) that is less important and therefore does not need to be processed as accurately can be processed using corresponding processing parameters that provide, for example, lower accuracy but, in return, higher processing speed.

[0019] For example, a first region or first set of pixels can be processed (exclusively) with a first set of processing parameters. A separate (i.e., nearby) region or second set of pixels can be processed (exclusively) with a second set of processing parameters. Processing with the first and respective second sets of processing parameters can occur sequentially in time, or can even occur (at least partially) simultaneously.

[0020] The particle beam can include an electron beam, an ion beam, an atomic beam, a molecular beam, and / or a photon beam.

[0021] The processing parameters may be, for example, intrinsic parameters of the particle beam (hereinafter, intrinsic beam parameters). The intrinsic beam parameters may include, for example, the pixel size of the particle beam (e.g., in the form of the diameter and / or area of ​​the particle beam on the mask), the particle type, the particle energy (when striking the mask), the particle beam flux or current (the ratio of particles per time, multiplied by the charge per particle, if appropriate; only the flux or current will be mentioned below in some respects, but the respective other terms are also intended to be concomitantly disclosed), and / or the particle beam fluence (the ratio of particles per time and per area of ​​the mask). The mentioned variables may be directly indicated by the respective parameters. However, it is also possible to provide indirect intrinsic beam parameters that at least partially determine only one or more of the mentioned variables, such as the particle primary energy, acceleration voltage, sample voltage (sample bias), aperture, numerical aperture, magnification, type of focusing device, etc. It is also conceivable to provide as intrinsic beam parameters the beam profile (e.g., using a circular, elliptical, etc. profile when impinging on the mask), the eccentricity of the beam profile (e.g., using a non-circular aperture), the offset of the aperture from the optical axis (or the offset of the aperture's center of gravity from the optical axis in the case of an aperture that is not rotationally symmetric), since these also influence the intensity of the local chemical reaction induced by the beam and can thereby concomitantly determine, for example, the "brush fineness".

[0022] In some examples, only one or more intrinsic beam parameters are changed. However, according to one aspect of the present invention, alternatively or additionally, processing parameters (hereinafter, process parameters) other than intrinsic beam parameters can also play a role. For example, gas parameters (gas type, (partial) pressure, flow rate, or other parameters affecting gas chemistry) can be processing parameters that differ between the first set and the second set, respectively. However, processing parameters can also include the type and scanning parameters of the scanning device, the gas refresh time (the period between two consecutive time intervals during which the particle beam is applied to the mask, i.e., the period during which each "exposure pulse" is produced), the step length between pixels (the distance between adjacent pixels, called the line step), and / or the scanning direction (line-by-line in the x-direction, line-by-line in the y-direction, a combination of x and y directions, spiral, randomized, or random), and / or the type of scanning device (e.g., column electronics or external deflection device). The scanning direction can be dependent on the geometry of the defect, so that the particle beam needs to be moved as little as possible to repair the defect. The pixel size used in creating the repair shape can also be a processing parameter.

[0023] One process parameter (in the broad sense) is also the so-called pixel exposure duration (the period during which the beam exposes a pixel without interruption, called the "dwell time"). However, in this case, the process parameter in the narrow sense is understood to be only all other process parameters, i.e., the pixel exposure duration is not a process parameter in the narrow sense. The process parameter may be a parameter of the apparatus used to carry out the method.

[0024] In some examples, the first and second sets of processing parameters can also differ in two or more parameters. Correlation of the differences between corresponding parameters between the first and second sets of processing parameters is possible. For example, the first set can have a smaller pixel size (of the repair shape or particle beam) than the second set, and the first set also has a lower beam current (or lower beam fluence, lower particle energy).

[0025] In this method, it can be provided that the processing of the pixels of the defect is selectively performed using either the first set of processing parameters or the second set of processing parameters, in particular depending on the position of the pixel within the defect. In this regard, for example, the position of the pixel can be taken as a basis for predetermining whether the pixel is intended to be processed using the first set of processing parameters or the second set of processing parameters. The first set and the second (separate) set of pixels can, for example, be predetermined from the totality of the pixels of the defect.

[0026] The corresponding first and second processing parameters can be predetermined (i.e., they can be fixed before assigning pixels to the first and second sets, respectively). Alternatively or additionally, the processing parameters can also depend at least in part on the first and second sets of pixels intended to be processed using the first and second sets of processing parameters, respectively. For example, the set of processing parameters for the first and / or second set of pixels can be selected depending on the total area of ​​the pixels in this set. In this regard, particularly for a set of pixels forming one large contiguous area, it is possible to select a high beam current, a high beam fluence, a high particle energy, a high gas flow rate, and / or a large pixel size of the particle beam. In particular, for a set of pixels forming one or more smaller contiguous areas, it is possible to select a low beam current, a low beam fluence, a low particle energy, a low gas flow rate, and / or a small pixel size of the particle beam.

[0027] Similarly, for a set of pixels associated with a greater depth of the defect, it is possible to use, for example, a higher beam current, a higher beam fluence, a higher particle energy, and / or a higher gas flow rate (and vice versa for a set of pixels associated with a smaller depth of the defect).

[0028] According to one embodiment of the present invention, it is also possible to select (as a processing parameter) a first pixel size and / or a second pixel size of the particle beam for repairing the defect depending on the first set and / or the respective second set of pixels. In particular, it is possible to select the pixel size of the particle beam for the first set and / or the respective second set of pixels depending on the total area of ​​the pixels of the respective sets. For example, the pixel size of the particle beam can be selected so that each area is covered as much as possible with an integer number of pixels. This can be important regardless of whether only one set or multiple sets of pixels processed using a set of processing parameters are available for repair. In particular, even if the defect is intended to be repaired using only a single set of processing parameters, it can be advantageous to appropriately optimize the pixel size.

[0029] At least one peripheral pixel of the defect can be processed using a first set of processing parameters, and / or at least one non-peripheral pixel of the defect can be processed using a second set of processing parameters. For example, a set of processing parameters that provides high resolution can be used for the peripheral pixels. A low beam current, a low fluence, a low particle energy, a low gas flow rate, and / or a small pixel size (e.g., of the particle beam) can be provided (parameters for high resolution). A set of processing parameters that provides lower resolution but in return allows for a higher processing speed can be used for the non-peripheral pixels. A higher beam current, a higher beam fluence, a higher particle energy, a higher gas flow rate, and / or a larger pixel size (e.g., of the particle beam) can be provided (parameters for low resolution). In this regard, metaphorically speaking, a large defect can be processed in its interior with a "coarse brush," while its peripheral region is processed with a "fine brush." ​​In this regard, different operating points can be provided, such as a high-resolution / high-precision operating point and a high-throughput, high-speed operating point.

[0030] For example, defects can be classified into peripheral regions with peripheral pixels and non-peripheral regions with non-peripheral pixels. Non-peripheral pixels (also called volume pixels) can be distinguished by the fact that they are surrounded by additional pixels of the defect. Peripheral pixels can be identified by the fact that they are at least partially free of pixels of the defect. Alternatively, the distinction can be made as follows: A pixel is a peripheral pixel if the distance between its center point or centroid and the peripheral contour of the defect is less than a predetermined threshold (which allows for multiple rows of peripheral pixels). Such a predetermined threshold can have a value of, for example, 1 to 25 nm, 1 to 15 nm, or 1 to 5 nm, e.g., 25 nm, 15 nm, or 5 nm.

[0031] Alternatively or additionally, peripheral pixels can be subdivided into edge pixels and non-edge pixels. Non-edge pixels are those peripheral pixels that are not adjacent to the planned edge after repair (or whose center point or center of gravity is at a distance from the planned edge after repair that exceeds a predetermined threshold). In contrast, edge pixels are those peripheral pixels that are adjacent to the planned edge after repair (or whose center point or center of gravity is at a distance from the planned edge after repair that does not exceed a predetermined threshold). Thus, for example, the accuracy requirements (only) for edge pixels that define the planned edge after repair can be expanded.

[0032] At least one edge pixel of the defect can be processed using a first set of processing parameters, and / or at least one non-edge pixel of the defect can be processed using a second set of processing parameters. For example, a set of processing parameters that provides high resolution can be used for the edge pixels. A low beam current, a low fluence, a low particle energy, a low gas flow rate, and / or a small pixel size (e.g., of the particle beam) can be provided (parameters for high resolution). A first set of processing parameters that provides lower resolution but in return allows for higher processing speed can be used for the non-edge pixels. A higher beam current, a higher beam fluence, a higher particle energy, a higher gas flow rate, and / or a larger pixel size (e.g., of the particle beam) can be provided (parameters for low resolution). Volume pixels can similarly be processed using the first set of processing parameters. However, alternatively, they may be processed using a dedicated set of parameters having a (even) higher beam current, a (even) higher beam fluence, a (even) higher particle energy, a (even) higher gas flow rate, and / or a (even) larger pixel size (e.g., of the particle beam) than the second (first) set of processing parameters.

[0033] By way of example, pixels may be divided into at least two of the following types of pixels: volume pixels, edge pixels, and non-edge pixels. For each of the two or more types, a different set of processing parameters may be used, as described herein.

[0034] In one example, pixels are classified into a first set of pixels including volume pixels and non-edge pixels and a second set of pixels including edge pixels. The first set of pixels can be processed using a set of low-resolution processing parameters. The second set of pixels can be processed using a set of high-resolution processing parameters.

[0035] At least one parameter from the first set of processing parameters may include at least one of the following elements: a lower beam current, a lower beam flux, a lower beam fluence, a lower particle energy, or a smaller pixel size (e.g., of the particle beam) than that defined by the second set of processing parameters. As a result, the area of ​​the defect processed using the first set can be processed more finely, while the area processed using the second set can be processed more coarsely, but generally more quickly. For example, the defect may first be processed using the second set of processing parameters, e.g., to remove the defect more coarsely and quickly. Thereafter, the defect may then be processed using the first set of processing parameters (e.g., with a lower beam current, a lower beam flux, etc., as described above) to remove finer details of the defect. It is also possible to start with the first set of processing parameters and only thereafter process the defect using the second set of processing parameters (e.g., with a higher beam current, a higher beam flux, etc.). In this case, the pixel size may refer to the pixel size used in creating the repair shape and / or the pixel size of the particle beam.

[0036] For example, a first set of processing parameters may be used to process one or more edge pixels (and / or perimeter pixels), and a second set of processing parameters may be used to process, for example, non-edge and / or volume pixels (and / or non-perimeter pixels).

[0037] Alternatively or additionally, the first set of processing parameters may include at least one of the following elements: a higher beam current, a higher beam flux, a higher beam fluence, a higher particle energy, a larger pixel size (e.g., of the particle beam) than those defined by the second set of processing parameters.

[0038] A defect can be understood as a (geometrically) contiguous set of pixels that must be exposed for the repair of the mask.

[0039] It is also within the scope of the present invention to treat a first defect using a first set of processing parameters, particularly specific beam parameters, and treat a second defect using a second set of processing parameters, particularly specific beam parameters. At least one parameter from the first set of processing parameters differs from the second set of processing parameters. In this regard, the processing parameters, particularly specific beam parameters, can be optimized for each defect. In this case, the processing parameters (as described above in relation to the area of ​​the defect) can be optimized, for example, according to the defect's geometry. Defects with larger areas can be treated using a higher beam current, a higher beam fluence, a higher particle energy, a higher gas flow rate, and / or a larger pixel size (e.g., of the particle beam) (the opposite applies to defects with smaller areas). Similarly, defects associated with larger depths can be treated using, for example, a higher beam current, a higher beam fluence, a higher particle energy, and / or a higher gas flow rate (the opposite applies to defects associated with smaller depths). Furthermore, the pixel size can be optimized during defect repair. For example, the pixel size (of the repair shape and / or particle beam) can be selected so that each defect is covered as much as possible using an integer number of pixels. The first defect and the second defect may both be dark defects or both be bright defects. The first defect and the second defect may be included in a common repair shape. The first defect and the second defect may be repaired, for example, sequentially, alternately (in parallel), or simultaneously, for example, without removing the mask from the corresponding device that provides the particle beam during this process.

[0040] It is noted that in some examples, more than just a first set and a second set of processing parameters may be provided for processing one or more defects. It is also possible to process the defects using three or more different sets of processing parameters (at least one parameter being different in each case), or to process three or more defects using different sets of processing parameters.

[0041] One aspect of the present invention is to predetermine a set of processing parameters and associated pixels (of the defect). In this regard, it becomes possible to optimize the processing parameters for each defect (each region of the defect). In response, information about the defect can be received. Based at least in part thereon, it is then possible to assign the pixels of the defect to a first pixel (first set of pixels) and / or a respective second pixel (second set of pixels) and / or to select the first set and / or the respective second set of processing parameters.

[0042] According to one embodiment, instead of different sets of processing parameters using one particle beam, different processing parameters using multiple particle beams are also provided. For example, a first defect (a first region of the defect) can be processed (using a first set of processing parameters) with a first particle beam, and a second defect (a second region of the defect) can be processed (using a first set of processing parameters) with a second particle beam. Simultaneous or at least partially sequential processing with the first particle beam and each second particle beam is contemplated.

[0043] According to a further aspect, an apparatus for repairing defects in a lithography mask with a particle beam is provided. The apparatus includes means for providing a particle beam and means for receiving information about the defect. The apparatus further includes means for determining, based on the information, at least one first region of the defect for treatment with the particle beam using a first set of processing parameters and at least one second region of the defect for treatment with the particle beam using a second set of processing parameters, wherein at least one parameter from the first set of processing parameters is different from the second set of processing parameters.

[0044] The processing using the first and second sets of processing parameters can include localized particle beam-induced etching and / or deposition, and should be distinguished from purely diagnostic processes. The apparatus can be implemented such that the second region does not overlap with the first section (is separate during projection onto the mask plane). For example, the first section of the defect can be repaired exclusively with the aid of the first set of processing parameters. For example, the second section of the defect can be repaired exclusively with the aid of the second set of processing parameters.

[0045] Defect processing is typically done pixel by pixel (eg, according to a repair shape).

[0046] As a result, the apparatus has means for determining, based on the information, at least one first pixel of the defect for processing by a particle beam using a first set of processing parameters and at least one second pixel of the defect for processing by a particle beam using a second set of processing parameters, wherein at least one parameter from the first set of processing parameters is different from the second set of processing parameters.

[0047] In this manner, the method described herein can be performed with the aid of an apparatus. In particular, the apparatus can receive information about defects. A first pixel and a second pixel (or a first set of pixels and a second set of pixels) are then determined based on the received information. By way of example, the selection can be performed as described above with respect to the method. As a result, different regions of the mask can be processed in an optimized manner according to their respective local requirements. The first pixel and the second pixel, or the first set of pixels and the second set of pixels, can be configured so that they do not overlap, i.e., are located next to each other on the mask.

[0048] The apparatus can be configured such that the means for receiving information is designed to receive information regarding the geometry of the defect. In this manner, the means for determining can perform pixel assignment for the defect and / or selection of the first and / or second sets of processing parameters based on the geometry of the defect. The means for determining can, for example, define pixel assignments and / or processing parameters appropriate for each defect depending on its size and / or propose them to a user of the apparatus for definition (e.g., via a graphical user interface).

[0049] The receiving means can be designed to obtain the information, for example, from a unit for recording an image of the mask (which can likewise be part of an apparatus, for example by a (scanning) electron microscope or an optical microscope, etc.) or from a corresponding user interface for input by a user. For example, the size of the defect can be ascertained automatically from the image information and / or the repair shape ascertained thereon.

[0050] The means for determining can be configured such that the decision for processing is selectively made using either the first set of processing parameters or the second set of processing parameters depending on the location of the respective pixel within the defect.

[0051] The means for receiving and / or the means for determining may also include a user interface suitable for inputting information by a user and / or outputting information to a user.

[0052] The determining means can be configured so that at least one first pixel includes at least one peripheral pixel of the defect and / or so that at least one second pixel includes at least one non-peripheral pixel of the defect. For example, software or hardware, or a combination thereof, can allow a user of the apparatus to provide information regarding a predetermined peripheral thickness. The determining means can then classify the pixels of the defect into peripheral pixels and non-peripheral pixels (e.g., peripheral pixels are pixels whose center points or centroids are located within a predetermined threshold distance from the peripheral contour of the defect). Alternatively, the determining means can use a previously stored value for peripheral thickness for this purpose without requiring user input. For example, the determining means can be configured to automatically classify a defect into a set of peripheral pixels and non-peripheral pixels if its peripheral contour exceeds a predetermined complexity measure and / or if the area of ​​the defect exceeds a predetermined threshold. The user interface may also be configured to allow the classification into marginal and non-marginal pixels to be optionally enabled or disabled for the mask, or for regions of the mask, or for each individual defect. Alternatively or additionally, in the above-described manner, marginal pixels may be subdivided into edge and non-edge pixels in a manner similar to that described above with respect to the method.

[0053] Furthermore, the determining means (e.g., a computer unit, a processor, etc.) can automatically select a set of parameters accordingly, for example, depending on a predetermined peripheral thickness (of peripheral pixels or edge pixels). The smaller the peripheral thickness, the more the parameters can be optimized for high resolution. Semi-automatic selection is also possible, in which the device offers the user a selection of sets of parameters adapted to the predetermined peripheral thickness, from which the user can make a final selection. Furthermore, the determining means can, for example, automatically select a set of parameters for non-peripheral pixels, for example, depending on area, etc. (as described above). The larger the peripheral thickness, the more the parameters can be optimized for low resolution and correspondingly rapid processing. Furthermore, the determining means can, correspondingly, for example, automatically select pixel sizes (of the repair shape and / or particle beam) for both peripheral pixels (particularly edge pixels and non-edge pixels) and non-peripheral pixels (as described above with respect to the method). Semi-automatic selection is also possible, in which the device offers the user a choice of pixel sizes adapted to a predetermined peripheral thickness and / or area of ​​non-peripheral and / or peripheral pixels, from which the user can then make a final selection.

[0054] The apparatus for repairing defects of a lithographic mask may not comprise a means for providing a particle beam. It may, for example, be provided as a separate hardware device that is provided for interacting with the device for providing a particle beam, for example via a (software) interface for providing a set of parameters and information about a (set of) pixels. In addition to or as an alternative to the apparatus for this purpose, a corresponding computer program may also be provided.

[0055] A further aspect of the present invention relates to a method for processing a lithography mask, the method comprising: a first process in which a particle beam according to a first set of specific beam parameters is guided onto the mask; in a second process, a particle beam according to a second set of specific beam parameters is guided onto the mask; at least one parameter from the first set of specific beam parameters is different from the second set of specific beam parameters; in other words, the specific beam parameters are changed during the entire process, including the (sub)processes "first process" and "second process."

[0056] Instead of using the same intrinsic beam parameters throughout (and at most changing the precursor gas supply between individual processes) as in the prior art, the intrinsic beam parameters can be optimized for each process type as described above. As already explained further above, the intrinsic beam parameters can include, for example, the pixel size of the particle beam (e.g., the diameter or area of ​​the particle beam on the mask), the fluence, the beam current, the beam flux, the particle energy, and the particle type (e.g., electrons, photons, (various) atoms, (various) molecules, and (various) ions). Any of these can be directly represented as intrinsic beam parameters. However, it is also possible to provide indirect types of intrinsic beam parameters, such as the acceleration voltage, the aperture, the magnification, the numerical aperture, the type of focusing device, and the like, as already explained.

[0057] In some examples, the first process is a diagnostic process. This can include, for example, a process for upstream image recording, a process for creating a repair shape, etc. This can further include a process for creating drift correction markers and / or a process for drift correction. Furthermore, this can include a process for downstream or intermittent image recording, for example, to check the progress of the repair. This can include, for example, a so-called endpoint indication process, which verifies whether material has already been removed to the desired depth and / or whether material has already been deposited to the desired thickness.

[0058] Alternatively or additionally, the second process can be a repair process, which can include, for example, an etching process and / or a deposition process. The particle beam can, together with the precursor gas, cause a local chemical reaction.

[0059] Generally, it may be advantageous to perform a further process between the first and second processes. The further process may be, for example, a diagnostic process, in which, for example, a particle beam with a second set of specific beam parameters is guided onto the mask. In this case, adjustments that are necessary due to, for example, variations in the specific beam parameters, may be made.

[0060] The above-mentioned aspects of optimizing the individual processes make it possible to optimize not only the resolution ("minimum repair size") and the speed of repair ("throughput"). Rather, for example, by optimizing parameters related to drift correction markers, it is possible to ensure correct positioning of the repair, minimize marker degradation, and accordingly reduce the degree of error reached in the critical dimension (CD) (smaller ΔCD / CD or smaller edge placement error). Through use during endpoint indication, it is also possible to ensure that the repair is correct, i.e., for example, reliably detected, as soon as a defect at a specific location is completely removed, thereby, for example, avoiding over-etching of the mask into the substrate.

[0061] According to one embodiment, the particle beam described herein can include an electron beam, and / or a first set of beam or process parameters can be designed such that the secondary electron contribution (in the example of an electron beam, per electron in the electron beam) is in the range of 0.5 to 1.5, preferably in the range of 0.75 to 1.25. Alternatively or additionally, a second set of beam or process parameters can be designed such that the secondary electron contribution is greater than 1.5, preferably greater than 1.75.

[0062] Thereby, the two sets of parameters can be optimized towards different goals. In the case of imaging of the mask (in the first process), for example, it is useful for the mask to be as little charged as possible, so that a secondary electron contribution of about 1 is desirable. During processing of the sample (in the second process), it can be useful to make the process as stable as possible with respect to energy fluctuations of the particle beam. For this purpose, it can be useful to configure the particle beam so that the secondary electron contribution is maximal, for example, greater than 1.5, or greater than 1.75, or close to 2.

[0063] In some examples, at least one parameter from the first set of specific beam parameters includes a higher particle energy than that defined by the second set of process parameters. In this regard, for example, while imaging via a high particle energy (in the first process), it is possible to achieve high image resolution (e.g., through additional depth information as a result of a higher penetration depth, smaller aberrations at higher energies, a better signal-to-noise ratio, etc.). During repair, for example, a lower particle energy can then be used to obtain finer repair resolution.

[0064] The methods described herein can further include supplying at least one precursor gas such that the particle beam excites a chemical reaction of the at least one precursor gas in the mask, each precursor gas having one or more gas supply parameters (such as gas type, partial pressure, gas flow rate, etc.).

[0065] A further aspect of the present invention is an apparatus for processing a lithography mask. The apparatus includes means for directing a particle beam onto the mask. The apparatus further includes means for receiving information regarding a first process and a second process. The apparatus additionally includes means for determining a first set of specific beam parameters and a second set of specific beam parameters for the first process and the second process, respectively, for which the particle beam is intended to be directed onto the mask. At least one parameter from the first set of specific beam parameters differs from the second set of specific beam parameters.

[0066] The device can therefore contribute in particular to optimizing a specific set of beam parameters for the first process and respectively the second process.

[0067] The receiving means may include a user interface. For example, software or hardware or a mixture thereof may allow the user of the device to provide information regarding the first process and / or the second process. The device may then automatically select a set of parameters accordingly with the aid of a determining means (e.g., a computer unit, a processor, etc.). Semi-automatic selection is also possible, in which the device offers the user a selection of sets of parameters adapted to each process, from which the user can then make a final selection.

[0068] The apparatus can be configured such that the means for receiving information can receive information identifying the first process as a diagnostic process and / or the second process as a repair process.

[0069] The apparatus for processing a lithographic mask may not comprise a means for guiding a particle beam onto the mask. It may, for example, be provided as a separate hardware device that is provided for interacting with the device for guiding a particle beam onto the mask, for example via a (software) interface for providing a set of specific beam parameters and / or information about the first and / or second process. In addition to or as an alternative to the apparatus for this purpose, a corresponding computer program may also be provided.

[0070] The apparatus described herein may include means for supplying at least one precursor gas such that the particle beam excites a chemical reaction of the at least one precursor gas in the mask.

[0071] The apparatus described herein can generally be designed to carry out the methods described herein, and conversely, all aspects described with respect to the apparatus in this case can also be carried out as steps in the method.

[0072] According to a further aspect of the present invention there is provided a computer program comprising executable instructions designed to perform the steps of one of the methods described herein when executed by a computer.

[0073] The following detailed description describes presently preferred exemplary embodiments of the invention with reference to the following drawings: [Brief explanation of the drawings]

[0074] [Figure 1] 1A-C are diagrams of examples of defects on a photomask, classification of the defects into sets of perimeter pixels and sets of non-perimeter pixels, and further classification of the defects into sets of edge pixels and non-edge pixels. [Figure 2] A and B are cross-sectional views of the particle beam interaction volume and secondary electron contribution at high and low particle energies, respectively. [Figure 3] FIG. 1 is a schematic diagram of secondary electron contribution as a function of particle energy. [Figure 4] 1 is a flow diagram of a method for particle beam repair of defects in a lithography mask. [Figure 5] 1 is a schematic diagram of an apparatus for particle beam repair of defects in a lithography mask; DETAILED DESCRIPTION OF THE INVENTION

[0075] Presently preferred embodiments of the invention are described in more detail below with reference to the drawings.

[0076] 1A-1C illustrate an exemplary lithography mask 100 (hereafter simply mask 100) having a defect 120, according to one example.

[0077] FIG. 1A shows an exemplary pattern 110 of a mask 100. The pattern 110 is shown as an absorbing pattern including horizontally oriented strips of absorbing material that absorb radiation during exposure. Radiation striking the photomask 100 between the strips during exposure can penetrate the photomask and expose an object on the other side of the photomask, such as a wafer coated with a photosensitive material. One of the strips has a defect 120. The absorbing material is at least partially missing in the area of ​​the defect 120. The defect 120 is shown as an exemplary rectangular structure. Therefore, radiation striking the area of ​​the defect 120 during exposure may at least partially inadvertently penetrate the mask 100. Therefore, the defect 120 is shown as an exemplary white defect 120. To repair the mask 100, an absorbing material can be deposited in the area of ​​the defect 120. The geometric shape of the pattern 110 and the nature of the defect as a white defect are merely exemplary.

[0078] In addition to two-dimensional coordinates (eg, x, y coordinates) that may extend within the mask plane, defect 120 may also have three-dimensional coordinates (eg, z coordinates) that may indicate the depth of the defect.

[0079] In the prior art, defects such as defect 120 were repaired using the exact same beam and process parameters, which is not always optimal, especially for large area defects.

[0080] To improve repair, defect 120 is divided into a first region 121 and a second region 122, as shown in Figures 1B and 1C. The first region and the respective second region can be formed by a first and a respective second (geometrically) contiguous set of pixels of defect 120 (or a repair shape of defect 120).

[0081] The first set of pixels (region 121) may be formed, for example, by one or more non-peripheral pixels of defect 120. The second set of pixels (region 122) may be formed, for example, by one or more peripheral pixels of defect 120.

[0082] The first set of pixels 121 can be exposed with beam and / or process parameters that result in a processing mode with, for example, relatively low resolution, relatively low accuracy, but relatively high throughput, e.g., high beam current, high particle energy, high gas flow rate, and / or large pixel size (e.g., of the particle beam) can be used.

[0083] The second set of pixels 122 can be exposed with beam and / or process parameters that result in a processing mode with, for example, relatively high resolution, relatively high accuracy, but relatively low throughput, e.g., a low beam current, low particle energy, low gas flow rate, and / or a small pixel size (e.g., of the particle beam) can be used.

[0084] Alternatively or additionally, the second set of pixels 122 (peripheral pixels) can be subdivided into edge pixels 122a and non-edge pixels 122b. The edge pixels 122a can be exposed with beam and / or process parameters that result in a processing mode with, for example, relatively high resolution, relatively high accuracy, but relatively low throughput. For example, a lower beam current, lower particle energy, lower gas flow rate, and / or smaller pixel size (e.g., of the particle beam) can be used compared to the beam and / or process parameters for the non-edge pixels 121 and / or non-edge pixels 122b. The same beam and / or process parameters as the non-edge pixels 121 can be used for the non-edge pixels 122b. However, it is also possible to use a lower beam current, lower particle energy, lower gas flow rate, and / or smaller pixel size (e.g., of the particle beam) for the non-edge pixels 122b compared to the beam and / or process parameters for the non-edge pixels 121.

[0085] The processing of the first set of pixels 121 and the second set of pixels 122, as well as the processing of sets 122a and 122b, can be performed simultaneously, alternately (in parallel) or sequentially in time.

[0086] For example, 1 to 10 nm for peripheral and / or edge pixels. 2 , preferably 1 to 5 nm 2 , e.g., 1×1 nm 2 , 2×2 nm 2 For non-peripheral pixels and / or non-edge pixels and / or volume pixels, the pixel size of the repair shape can be larger, for example, 5-25 nm. 2 , preferably 10 to 25 nm 2 , e.g., 2 × 2 nm 2 , 3×3 nm 2 , 4×4nm 2 , or 5 × 5 nm 2 It can be said that:

[0087] For example, 1 to 10 nm for peripheral and / or edge pixels. 2 , preferably 1 to 5 nm 2 , e.g., 1×1 nm 2 , 2×2 nm 2 For non-peripheral pixels and / or non-edge pixels and / or volume pixels, the particle beam pixel size can be larger, for example, 5 to 40 nm, preferably 10 to 25 nm. 2 , e.g., 2 × 2 nm 2 , 3×3 nm 2 , 4×4nm 2 , 5×5nm 2 , or 6 × 6 nm 2 It can be said that:

[0088] It is also possible to express pixel size (of the particle beam or repair shape) in units of the minimum focus diameter of the particle beam.

[0089] The assignment of pixels of the repair shape of the defect 120 to one or more sets of pixels can also be considered as segmenting the repair shape into one or more sub-repair shapes, each of which includes a set of pixels. The processing of the sets of pixels can then be performed, in particular, sequentially in time, i.e., by sequential processing of the individual sub-repair shapes. For example, the sequence of repair shapes and their respective process steps and their parameters can be stored in a common file. The latter can then be processed by a corresponding device as described herein.

[0090] 2A-2B illustrate the effect of varying particle energy during processing of a substrate 200, e.g., a mask, based on an electron beam 220. The electron beam 220 can be incident on the substrate 200, e.g., nearly perpendicularly. A relatively high particle energy of the electrons results in a relatively large interaction volume 225 with the substrate 220 (FIG. 2A). A relatively low particle energy results in a relatively small interaction volume with the substrate (FIG. 2B). The interaction volume 225 is approximately drop-shaped in cross section, with the tip of the drop pointing in the direction of the incident beam 220, while the drop can have a generally rounded shape on the side opposite the incident beam 220. The drop depth generally increases with particle energy, as does the average diameter of the drop in the direction of the particle beam.

[0091] Therefore, by appropriately choosing the particle energy (e.g., by adapting the acceleration voltage), it is possible to set the "roughness" of the grid where repairs are made both in the plane of the mask and in the z-direction. As an example, simulation of secondary electrons from a quartz surface allows the following estimation: At an acceleration voltage of 1 kV, secondary electrons are generated within a radius of approximately 25 nm around the impact point of the primary beam. At acceleration voltages of only 0.6 kV or 0.2 kV, said radius decreases to approximately 15 nm or 10 nm, respectively.

[0092] Around the tip of the droplet there is generally a zone 240 where secondary electrons are liberated upon impact by the particle beam. The size or extent of these zones 240 on the substrate also depends on the particle energy of the incident particle beam. At higher particle energies, the zones tend to be somewhat deeper and also tend to have a larger surface area in the substrate plane. Thus, the exit plane for the secondary electrons occurs at the top surface of the substrate facing the particle beam.

[0093] FIG. 3 shows an exemplary functional relationship 300 between particle energy and secondary electron yield. This relationship is shown for an electron beam as an example, showing the secondary electron yield n per incident electron as a function of electron energy (in keV). As electron energy increases, the secondary electron yield initially rises from a value close to or equal to zero. At a particle energy of approximately 0.15 keV, the secondary electron yield is then approximately n=1. This point is identified by reference numeral 340 in FIG. 3. Subsequently, the increase in n levels off somewhat, reaching a maximum value 320 of approximately n=2 at a particle energy of approximately 0.5 keV. The yield then decreases again, reaching a value of n=1 again (reference numeral 360) at an energy of approximately 2 keV, and then further decreasing with increasing particle energy.

[0094] In some exemplary embodiments, for the purpose of processing a lithography mask, it may be useful to perform a first process with a different set of specific beam parameters compared to a second process. The first process and the respective second process in this sense may be, for example, an image recording process for generating a repair shape, a process for creating at least one drift correction marker, the actual repair process (e.g., particle beam-induced etching and / or deposition), a process for drift correction during the actual repair process, an endpoint indication process (checking whether material has already been removed to the desired depth and / or whether material has already been deposited to the desired thickness), an image recording process for verifying the repair.

[0095] In some exemplary embodiments, for purposes of processing a lithography mask, it may be useful to perform a first process at a different acceleration voltage of the particle beam (e.g., electrons or ions) compared to a second process. For example, the process for generating a repair shape and / or the process for imaging may be performed at a different acceleration voltage compared to the actual repair process based on the generated repair shape. The acceleration voltages may be optimized independently of each other and may be performed without removing the mask from the device providing the particle beam, even if the processes serve to repair and diagnose one and the same defect. According to one example, the voltages may each be optimized for different successive processes (e.g., image recording and / or repair steps) related to the same defect.

[0096] According to one example, the imaging process (for creating the repair shape and / or checking the repair) is performed at a higher acceleration voltage to obtain a high image resolution. For this purpose, for example, backscattered electrons / ions can be detected with the aid of, for example, the technique of energy-selective backscattering (EsB). Conversely, for the subsequent repair process (by local etching and / or local deposition with the aid of precursor gases), a lower acceleration voltage can be used to obtain a high repair resolution. This is because a lower acceleration voltage results in a smaller zone 240 (see FIG. 2) in which secondary electrons are released upon impact with the particle beam. Therefore, the local chemical reaction used for the repair is better locally defined, improving the repair resolution. For example, practical repairs for e-beam and EUV masks can use acceleration voltages of 50-1200 V, 100-1200 V, 200-1200 V, 300-1000 V, 400-800 V, or 500-700 V, preferably 550-650 V or about 600 V. For imaging processes, voltages of, for example, >2 kV can be used, e.g., 2-5 kV, 2-4 kV, 2.5-3.5 kV, or about 3 kV.

[0097] In a further example, the acceleration voltage for the imaging process can be selected so that the secondary electron yield is approximately 1. This can be particularly useful when sample charging effects can be problematic. In the case of an electron beam, the acceleration voltage can have a value of approximately 300-700 V, 400-600 V, 450-550 V, or approximately 500 V. In actual repair, it is possible to use an acceleration voltage that allows the desired resolution, e.g., optimal resolution, for example, 50-1200 V, 100-1200 V, 200-1200 V, 300-1000 V, 400-800 V, or 500-700 V, preferably 550-650 V or approximately 600 V (e.g., for electron beam and / or EUV masks).

[0098] In a further example, the acceleration voltage of the imaging process (before, after, or otherwise during the actual repair process) can be selected to optimize material contrast (e.g., by energy-selective detection of backscattered electrons with an EsB detector). In another example, the acceleration voltage of the imaging process (before, after, or otherwise during the actual repair process) can be selected to minimize edge effects (so that edges appear in the correct position). Furthermore, the acceleration voltage of the imaging process (before, after, or otherwise during the actual repair process) can be selected to maximize edge effects (so that edges are more clearly discernible). For the actual repair, different acceleration voltages can be used that allow the desired repair resolution, e.g., optimal resolution, using, for example, in each case (e.g., in the case of electron beam and / or EUV masks), 50-1200 V, 100-1200 V, 200-1200 V, 300-1000 V, 400-800 V, or 500-700 V, preferably 550-650 V or approximately 600 V.

[0099] In the above example, the acceleration voltage is merely an example, and other voltages (e.g., sample bias voltage) can also be varied and used accordingly as different parameters for the first and second processes.

[0100] In some examples, different pixel sizes are used for the first and second processes for processing the lithography mask, and the pixel sizes can be optimized for each process independently of each other.

[0101] According to one example, a repair shape is generated at a first pixel size. The actual repair can be performed (at least in part) at a different pixel size (of the particle beam). By way of example, the pixels of the repair shape can be divided into a first set of pixels and a respective second set of pixels. The pixel sizes of the particle beam for repairing the first set and the second set can then be optimized in each case for the first set and the respective second set, as described herein.

[0102] However, in actual repair, it is also possible to use different pixel sizes without dividing the repair shape into multiple sets of pixels. For example, the pixel size (of the particle beam) can be chosen depending on the geometry of the repair shape. The pixel size can be chosen to allow repair with as many integer pixels as possible. The pixel size can be chosen depending on the total area of ​​the defect and / or the complexity of the defect contour.

[0103] It is also possible to optimize at least one further parameter (beam and / or process parameter) for the pixel size used in the respective process. In the device of the present invention, for example, automatic optimization of the further parameters for the respective pixel size used can be performed, which can optionally include an (automatic) check as to whether the respectively selected pixel size is appropriate and / or acceptable. This can ensure that the (isolated) selection of a particular pixel size does not introduce errors into the process.

[0104] According to one example, two repair processes are performed. In the first process, overcorrection is performed. For example, material is deposited (or etched away) over an area larger than the area corresponding to the extent of the defect. Then, in a second step, the deposited material is partially etched away again (or, respectively, material is deposited) so that the remaining material reproduces the contours of the defect as closely as possible. The first process can be performed with one or more parameters for high resolution. The second process can be performed with one or more parameters for low resolution. This can be advantageous for quickly achieving a (large area) repair that roughly corresponds to the defect. Then, in the second step, the necessary fine-tuning for an accurate repair can be performed. Then, a high-resolution (slower) process needs to be performed only over a smaller area.

[0105] In particular, as a result of changes in beam and / or process parameters, it may be necessary to ensure alignment between different images. This is because masks may expand or bend differently due to various possible thermal loads. Furthermore, particularly when using electron beams, particle beams may be deflected to different degrees as a result of different electrostatic charges. For this purpose, it is possible to create and / or use markings on the mask. However, it is also possible to ensure alignment through model-based predictions. One example of this is disclosed in DE 10 2018 209 562 B3. Further development of models for different parameters may make it unnecessary to use markings on the mask, as described here. This is especially advantageous when different parameters are intended to be used, as in this case, and thus the need for adaptation of displacement or distortion corrections increases, since markings also deteriorate over time and therefore should be scanned as little as possible. For example, it is possible to empirically determine which changes in certain parameters cause which changes in the image. However, models that physically calculate and / or predict changes based on machine learning are also possible.

[0106] An apparatus for processing a lithography mask and / or repairing defects in a lithography mask may include: (a) means for recording measurement data while the mask is exposed to a particle beam; and (b) means for predetermining drift of a beam of charged particles relative to the lithography mask using a trained machine learning model and / or a predictive filter, where the trained machine learning model and / or the predictive filter uses at least the measurement data as input data. In particular, the predictive filter and / or the trained model may enable ascertaining drift of a changed set of processing parameters from drift of a particular set of processing parameters (beam parameters and / or process parameters), such that correction for drift when changing processing parameters for a second process only needs to be made relative to corrections already made in the first process.

[0107] A further aspect to be considered is that, as described in this case, the point spread function (PSF) of the imaging system can be adapted, if appropriate, taking into account the material effects of the mask, especially when parameters are changed in the process. For this purpose, provisions can be made to measure the PSF. Measurements can be made for different sets of parameters that will then be used later. However, it is also possible that one or more measurements are made only for one or more selected sets of parameters, and then the PSF is confirmed in each case for the set of parameters that will be used later. For this purpose, interpolation or extrapolation or complex transformations can be performed based on mathematical models.

[0108] The measurement can be carried out with the aid of a sample, as described, for example, in DE 10 2018 210 522. Alternatively or additionally, two or more images of the reference structure can be recorded, in particular under different recording conditions. The PSF can be generated for two or more recorded images using a corrected reference image of the reference structure, for example by recording the images in the form of a focal stack.

[0109] The images recorded in each case can then be deconvolved with the measured PSF or with a PSF determined based on the measured data, optionally taking into account material effects. Finally, a restoration can be generated from the sharpened images in this way.

[0110] FIG. 4 shows an exemplary flow diagram of a method for processing a lithography mask or, respectively, for repairing defects in the mask.

[0111] The method may initially include a process 410 for creating drift-correction markers. This optional process 410 may be performed at the beginning of the method; however, it may also be performed at a later time. The drift-correction markers may be observed, for example, during processing, where they may be corrected for drift or distortion.

[0112] The method may additionally include a process 420 of recording image information about the defect. Recording may be performed using a particle beam, for example, by an electron beam, which may be provided in an SEM (see FIG. 5).

[0113] Generating the repair shape 430 can be provided as a further process. The repair shape can be generated, for example, by a computer system (see FIG. 5). For this purpose, information from the recording by process 420 can be used, for example. The generation can be performed by a computer system integrated into the apparatus for providing the particle beam (e.g., an apparatus including an SEM, see FIG. 5). However, as an alternative, the computer system can also obtain the corresponding information from the recording via an interface, for example, a user interface or some other interface (to a data carrier, a server, the Internet, etc.). The computer system can also obtain information from some other, for example, previously used measuring device (e.g., an AIMS, an AFM (atomic force microscope)) and use that information to generate the repair shape. Furthermore, user input can also be taken into account in the process of generating the repair shape by the computer system, which input can be received via the user interface.

[0114] In a further step 440, at least one first pixel of the defect and at least one second pixel of the defect can be selected. The selection can be performed at least partially manually by a user with the aid of a user interface. However, the selection can also be performed at least partially automatically by a computer system.

[0115] In a further step (not shown), a first set of processing parameters and a second set of processing parameters for the processing of at least one first pixel and respectively at least one second pixel can be defined with the aid of a computer system, which definition can also be performed at least partly automatically with the aid of a user interface and / or at least partly manually.

[0116] In a further process 450, the defect, in particular the at least one first pixel, can be treated using a particle beam and a first set of processing parameters. A further process 460 of drift correction can be performed during this process.

[0117] In an additional process 470, the defect, and in particular the at least one second pixel, can be processed using a particle beam and a second set of processing parameters. During this processing, a further process 460 of drift correction can also be performed, but typically the correction parameters are changed.

[0118] Finally, further processes may be performed to record image information about the defect for "endpoint indication" 480 and / or to record image information for verification of repair of the defect 490.

[0119] 5 shows a schematic cross section through some key components of an apparatus 500 that can be used to process or repair (one or more defects in) a lithography mask. The exemplary apparatus 500 of FIG. 5 includes a modified scanning particle microscope 510 in the form of a scanning electron microscope (SEM) 510.

[0120] The apparatus 500 includes a particle beam source 505 in the form of an electron beam source 505 that generates an electron beam 515 as a particle beam 515. The electron beam 515 has the advantage over an ion beam that electrons striking the sample 525 or a lithography mask are unlikely to substantially damage the sample or mask. However, it is also possible to use an ion beam, an atomic beam, a molecular beam, or a photon beam (not shown in FIG. 5 ) for the purpose of processing the sample 525 in the apparatus 500.

[0121] The scanning particle microscope 510 comprises an electron beam source 505 and a column 520 within which is arranged a beam optics unit 513, e.g., in the form of an electron optics unit of the SEM 510. In the SEM 510 of Figure 5, the electron beam source 505 generates an electron beam 515 which is directed as a focused electron beam 515 at location 522 onto a sample 525, which may include a lithography mask, by imaging elements arranged in the column 520, said imaging elements being not shown in Figure 5. The beam optics unit 513 thus forms the imaging system 513 of the electron beam source 505 of the SEM 500.

[0122] Additionally, the imaging elements of the column 520 of the SEM 510 can scan the electron beam 515 across the sample 525. The sample 525 can be examined using the electron beam 515 of the SEM 510.

[0123] Backscattered and secondary electrons generated by the electron beam 515 in the interaction region of the sample 525 are recorded by a detector 517. Detectors 517 arranged in the electron column 520 are called "in-lens detectors." The detector 517 can be installed in the column 520 in various embodiments. The detector 517 converts secondary electrons generated by the electron beam 515 at the measurement point 522 and / or electrons backscattered from the sample 525 into electrical measurement signals and sends the electrical measurement signals to an evaluation unit 585 of the computer system 580 of the apparatus 500. The detector 517 can include a filter or filter system to distinguish electrons with respect to energy and / or solid angle (not reproduced in FIG. 5 ). The detector 517 is controlled by a configuration unit 590 of the apparatus 500.

[0124] The exemplary apparatus 500 may include a second detector 519. The second detector 519 may be designed to detect electromagnetic radiation, particularly in the X-ray range. As a result, the detector 519 makes it possible to analyze the material composition of the radiation generated by the sample 525 during its examination. The detector 519 is likewise controlled by the configuration unit 590.

[0125] Additionally, apparatus 500 may include a third detector (not shown in FIG. 5), which is often embodied in the form of an Everhart-Thornley detector and is generally located outside column 520. Typically, it is used to detect secondary electrons.

[0126] The apparatus 500 may include an ion source (not shown in FIG. 5) that supplies ions with low kinetic energy to the region of the sample 525. The ions with low kinetic energy may compensate for charging of the sample 525. Additionally, the apparatus 500 may include a mesh (also not shown in FIG. 5) at the output of the column 520 of the modified SEM 510. Electrostatic charging of the sample 525 may likewise be compensated for by applying a voltage to the mesh. Additionally, the mesh may be grounded.

[0127] The sample 525 is placed on a sample stage 530 or sample holder 530 for inspection purposes. The sample stage 530 is also known in the art as a "stage." As represented by the arrow symbols in FIG. 5, the sample stage 530 can be moved in three spatial directions relative to the electron beam 515 of the SEM 510, for example, via a micromanipulator (not shown in FIG. 5).

[0128] In addition to translation, the sample stage 530 can rotate about at least an axis oriented parallel to the beam direction of the particle beam source 505. Furthermore, the sample stage 530 can be embodied to be rotatable about one or two additional axes, which or these axes are arranged in the plane of the sample stage 530. The two or three rotation axes preferably form a Cartesian coordinate system. As can be seen from FIG. 5, rotation of the sample stage 530 about a rotation axis arranged in the plane of the sample stage 530 is often only possible to a limited extent due to the small distance between the end of the column and the sample 525.

[0129] The sample 525 to be tested can be any microstructured component or device requiring analysis and, if necessary, subsequent processing, such as repair of local defects in a lithography mask. In this regard, the sample 525 can include, for example, a transmission or reflection photomask and / or template for nanoimprint technology. Transmission and reflection photomasks can include any type of photomask, such as a binary mask, a phase-shift mask, an OMOG mask, or a mask for double or multiple exposure.

[0130] Additionally, the apparatus 500 of FIG. 5 may include one or more scanning probe microscopes, for example in the form of atomic force microscopes (AFMs) (not shown in FIG. 5), that can be used to analyze and / or process the sample 525.

[0131] The exemplary scanning electron microscope 510 shown in Figure 5 operates within a vacuum chamber 570. To create and maintain the reduced pressure required in the vacuum chamber 570, the SEM 510 of Figure 5 has a pumping system 572.

[0132] Apparatus 500 includes a computer system 580. Computer system 580 can form the means described herein for receiving information regarding a first process and a second process, and / or means for determining a first set of specific beam parameters and a second set of specific beam parameters for the first process and the second process, respectively.

[0133] Additionally, the computer system 580 may form the means described herein for receiving information about the defect and / or means for determining, based on the information, at least one first pixel of the defect for processing by a particle beam using a first set of processing parameters and at least one second pixel of the defect for processing by a particle beam using a second set of processing parameters.

[0134] The computer system 580 may further include a scanning unit 582 for scanning the electron beam 515 across the sample 525. Furthermore, the computer system 580 may comprise a setting unit 590 for setting various parameters of the modified scanning particle microscope 510 of the apparatus 500. Furthermore, the setting unit 590 may control the deflection system and the rotation of the sample stage 530.

[0135] Furthermore, the computer system 580 may include an evaluation unit 585 that analyzes the measurement signals of the detectors 517 and 519 and generates an image of the sample 525 therefrom. The image can be displayed on a graphical user interface of the computer system 580, which may include a display 595 and input means. In particular, the evaluation unit 585 may be designed to determine the location and contour of defects of missing material and / or defects of excess material of the sample 525, for example, a lithography mask, from the measurement data of the detector 517. The evaluation unit 585 may additionally include one or more algorithms that enable determining repair shapes corresponding to the analyzed mask defects. The evaluation unit 585 of the computer system 580 may additionally include one or more algorithms that enable ascertaining parameters (beam and / or process parameters) of a particular process. The algorithms of the evaluation unit 585 may be implemented using hardware, software, or a combination thereof. In particular, the algorithms may be realized in the form of an ASIC (Application Specific Integrated Circuit) and / or an FPGA (Field Programmable Gate Array).

[0136] Computer system 580 and / or evaluation unit 585 may include a memory (not shown in FIG. 5 ), preferably a non-volatile memory, that stores one or more models of repair shapes for various mask types. Evaluation unit 585 may be designed to calculate repair shapes for defects in lithography masks from measurement data of detector 517 based on the repair models. Furthermore, computer system 580 may include an interface 587 for exchanging data with the Internet, an intranet, and / or some other device. Interface 587 may include a wireless interface or a wired interface.

[0137] 5, the evaluation unit 585 and / or the configuration unit 590 may be integrated into the computer system 580. However, it is also possible for the evaluation unit 585 and / or the configuration unit 590 to be embodied as independent units inside or outside the apparatus 500. In particular, the evaluation unit 585 and / or the configuration unit 590 may be designed to perform some of their tasks by means of dedicated hardware implementations.

[0138] Computer system 580 may be integrated into apparatus 500 or may be embodied as a separate device (not shown in FIG. 5). Computer system 580 may be embodied using hardware, software, firmware, or a combination.

[0139] Further exemplary embodiments: 1. A method for particle beam repair of defects (120) in a lithography mask (100), comprising: a. Treating (450) the defect (120) with a particle beam using a first set of treatment parameters; b. treating (470) the defect (120) with a particle beam using a second set of treatment parameters; Including, c. A method wherein at least one parameter from the first set of processing parameters is different from the second set of processing parameters. 2. 10. The method of exemplary embodiment 1, wherein a first section (122) of the defect is repaired with the help of a first set of processing parameters and a second section (121) of the defect is repaired with the help of a second set of processing parameters, wherein the first section does not overlap with the second section. 3. 3. The method according to exemplary embodiment 1 or 2, wherein processing the pixels of the defect is selectively performed using either a first set of processing parameters or a second set of processing parameters depending on the position of the pixel in the defect. 4. The method according to any one of exemplary embodiments 1 to 3, wherein at least one peripheral pixel of the defect is processed using a first set of processing parameters and / or at least one non-peripheral pixel of the defect is processed using a second set of processing parameters. 5. The method according to any one of exemplary embodiments 1 to 4, wherein at least one edge pixel (122a) of the defect is processed using a first set of processing parameters, and / or at least one non-edge pixel (122b) of the defect and / or a volume pixel (121) is processed using a second set of processing parameters. 6. The method of any of exemplary embodiments 1-5, wherein at least one parameter from the first set of processing parameters comprises at least one of the following elements: lower beam current, lower beam flux, lower beam fluence, lower particle energy, smaller pixel size than those defined by the second set of processing parameters. 7. 1. An apparatus (500) for particle beam repair of defects in a lithography mask, comprising: a. means for providing a particle beam (505); b. means for receiving information regarding the defect (580); c. means (580) for determining, based on the information, at least one first region of the defect for treatment with a particle beam using a first set of treatment parameters, and at least one second region of the defect for treatment with a particle beam using a second set of treatment parameters; Including, d. An apparatus (500) in which at least one parameter from the first set of processing parameters differs from the second set of processing parameters. 8. 8. The apparatus of Exemplary Embodiment 7, wherein the information about the defect includes information about the geometric shape of the defect. 9. The apparatus of any of exemplary embodiments 7 and 8, wherein the determining means is configured such that the decision to process is selectively made using either the first set of processing parameters or the second set of processing parameters depending on the location of each pixel in the defect. 10. The apparatus of any of exemplary embodiments 7 to 9, wherein the means for determining is configured such that at least one first pixel has at least one peripheral pixel that is defective, and / or at least one second pixel has at least one non-peripheral pixel that is defective. 11. 1. A method for processing a lithography mask, comprising: a. a first process in which a particle beam using a first set of specific beam parameters is directed onto a mask; b. a second process in which the particle beam is guided onto the mask using a second set of specific beam parameters; Including, c. The method wherein at least one parameter from the first set of specific beam parameters differs from the second set of specific beam parameters. 12. The method according to exemplary embodiment 11, wherein the first process is a diagnostic process, in particular a process for correcting drift, and / or the second process is a repair process. 13. 13. The method of any of exemplary embodiments 11 and 12, wherein the first set of intrinsic beam parameters is configured such that the secondary electron contribution is in the range of 0.5 to 1.5, preferably in the range of 0.75 to 1.25, and / or the second set of intrinsic beam parameters is configured such that the secondary electron contribution is greater than 1.5, preferably greater than 1.75. 14. 14. The method according to any one of exemplary embodiments 11 to 13, wherein at least one parameter from the first set of intrinsic beam parameters comprises at least one of the following elements: a particle energy higher than that defined by the second set of processing parameters: 15. 15. The method of any one of exemplary embodiments 1-6 or 11-14, further comprising supplying at least one precursor gas such that the particle beam excites a chemical reaction of the at least one precursor gas in the mask. 16. An apparatus (500) for processing a lithography mask, comprising: a. means (520) for directing a particle beam onto a mask; b. means for receiving information regarding the first process and the second process (580); c. means (580) for determining a first set of specific beam parameters and a second set of specific beam parameters for a first process and a second process, respectively, for which the particle beam is intended to be directed onto the mask; Including, d. An apparatus (500) wherein at least one parameter from the first set of specific beam parameters differs from the second set of specific beam parameters. 17. 17. The apparatus of exemplary embodiment 16, wherein the information identifies the first process as a diagnostic process and / or the second process as a repair process. 18. The apparatus of any of exemplary embodiments 7-10 or 16, 17, further comprising a means for supplying at least one precursor gas such that the particle beam excites a chemical reaction of the at least one precursor gas in the mask. 19. A computer program comprising executable instructions designed to perform the steps of the method according to any one of exemplary embodiments 1 to 6 or 11 to 15 when executed by a computer.

Claims

1. A method for particle beam repair of defects (120) in a lithography mask (100), comprising: Treating (450) the defect (120) with the particle beam using a first set of treatment parameters; b. treating (470) the defect (120) with the particle beam using a second set of processing parameters; Including, c. at least one parameter from the first set of processing parameters is different from the second set of processing parameters; d. The method of claim 1, wherein at least one peripheral pixel of said defect is processed using said first set of processing parameters and at least one non-peripheral pixel of said defect is processed using said second set of processing parameters.

2. 2. The method of claim 1, wherein a first section (122) of the defect is repaired with the aid of a first set of processing parameters and a second section (121) of the defect is repaired with the aid of a second set of processing parameters, the first section not overlapping the second section.

3. 3. The method of claim 1, wherein the processing of pixels of the defect is selectively performed using either the first set of processing parameters or the second set of processing parameters depending on the location of the pixel in the defect.

4. 4. The method according to claim 1, wherein at least one edge pixel (122a) of the defect is processed using the first set of processing parameters and / or at least one non-edge pixel (122b) and / or volume pixel (121) of the defect is processed using the second set of processing parameters.

5. 5. The method of claim 1, wherein the at least one parameter from the first set of processing parameters comprises at least one of the following elements: lower beam current, lower beam flux, lower beam fluence, lower particle energy, smaller pixel size than those defined by the second set of processing parameters.

6. 1. An apparatus (500) for particle beam repair of defects in a lithography mask, comprising: a. a means for providing a particle beam (505); b. means (580) for receiving information regarding said defect; c. means (580) for determining, based on the information, at least one first region of the defect for treatment with the particle beam using a first set of treatment parameters, and at least one second region of the defect for treatment with the particle beam using a second set of treatment parameters; Including, d. at least one parameter from the first set of processing parameters is different from the second set of processing parameters; e. the means for determining is configured such that the at least one first region has at least one peripheral pixel of the defect and the at least one second region has at least one non-peripheral pixel of the defect.

7. The apparatus of claim 6 , wherein the information about the defect includes information about the geometry of the defect.

8. 1. A method for processing a lithography mask, comprising: a. a first process in which a particle beam using a first set of specific beam parameters is directed onto the mask; b. a second process in which the particle beam is directed onto the mask using a second set of specific beam parameters; Including, c. at least one parameter from the first set of specific beam parameters is different from the second set of specific beam parameters; d. The method wherein the at least one parameter from the first set of specific beam parameters includes at least one of the following elements: a higher particle energy than that defined by the second set of specific beam parameters.

9. 9. The method according to claim 8, wherein the first process is a diagnostic process, in particular a process for correcting drift, and / or the second process is a repair process.

10. 10. The method of claim 8, wherein the first set of intrinsic beam parameters is configured such that the secondary electron contribution is in the range of 0.5 to 1.5, preferably in the range of 0.75 to 1.25, and / or the second set of intrinsic beam parameters is configured such that the secondary electron contribution is greater than 1.5, preferably greater than 1.

75.

11. 11. The method of any of claims 1 to 5 or 8 to 10, further comprising supplying at least one precursor gas such that the particle beam excites a chemical reaction of the at least one precursor gas in the mask.

12. An apparatus (500) for processing a lithography mask, comprising: a. means (520) for directing a particle beam onto said mask; b. means (580) for receiving information regarding the first process and the second process; c. means (580) for determining a first set of intrinsic beam parameters and a second set of intrinsic beam parameters for the first process and the second process, respectively, for which the particle beam is intended to be directed onto the mask; Including, d. at least one parameter from the first set of specific beam parameters is different from the second set of specific beam parameters; e. The apparatus (500), wherein the at least one parameter from the first set of specific beam parameters includes at least one of the following elements: a particle energy higher than that defined by the second set of specific beam parameters.

13. The apparatus of claim 12 , wherein the information identifies the first process as a diagnostic process and / or the second process as a repair process.

14. 14. The apparatus of claim 6, 7, 12, or 13, further comprising means for supplying at least one precursor gas such that the particle beam excites a chemical reaction of the at least one precursor gas in the mask.

15. A computer program comprising executable instructions designed to carry out the steps of the method of any of claims 1 to 5 or 8 to 11 when executed by a computer.

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