Method for processing defect of microlithographic photomask

Abstract

To provide an improved method and an improved apparatus for processing a defect of a microlithographic photomask.SOLUTION: There is disclosed a method for processing a defect of a microlithographic photomask. A process gas is activated with the aid of a particle beam. A control unit is provided for controlling a deflection unit with a control bandwidth. The deflection unit is configured to guide the particle beam over the photomask. The method includes the following steps: a) providing an image of at least a portion of the photomask; b) ascertaining a repair shape in the image on the basis of the control bandwidth (108, 1300 to 1304), where the repair shape comprises the defect; and c) providing the particle beam at m pixels of the repair shape with the aid of the deflection unit, and activating the process gas for the purpose of processing the defect.SELECTED DRAWING: Figure 13

Description

Technical Field

[0001] The present invention relates to a method, a computer program product, and an apparatus for processing defects in a microlithography photomask.

[0002] The entire content of the priority application DE102023129605.1 is incorporated herein by reference.

Background Art

[0003] Microlithography is used to manufacture components of microstructured components, such as integrated circuits. The microlithography process is performed using a lithography apparatus comprising an illumination system and a projection system. In this case, the image of a photomask (reticle) irradiated by the illumination system is projected onto a substrate, for example a silicon wafer, coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection system in order to transfer the mask structure to the photosensitive coating of the substrate by means of the projection system.

[0004] In order to obtain smaller structure sizes and thus increase the integration density of microstructured components, the use of light with very short wavelengths, such as deep ultraviolet (DUV) or extreme ultraviolet (EUV) for example, is increasing. The wavelength of DUV is for example 193 nm and the wavelength of EUV is for example 13.5 nm.

[0005] In this case, the structural dimensions of microlithography photomasks can range from a few nanometers to several hundred nanometers. The production of such photomasks is very complex and thus costly. In particular, this is because the photomask needs to be defect-free, otherwise it cannot be guaranteed that the structures manufactured on the silicon wafer by the photomask will exhibit the desired function. In particular, the quality of the structures on the photomask is decisive for the quality of the integrated circuits manufactured on the wafer by the photomask.

[0006] For these reasons, the micro-lithography photomask is checked for defects, and the detected defects are repaired in a targeted manner. Typical defects include, for example, the absence of an assumed structure due to a failed etching process, or the presence of an unassumed structure due to, for example, an overly rapid progress of the etching process or an effect occurring at the wrong site. These defects can be improved by etching away excess material in a targeted manner, or by depositing additional material in a targeted manner at the appropriate location. For example, this can be achieved in a very targeted manner by an electron beam induced process (FEBIP, "focused electron beam induced processing").

[0007] DE102017208114 describes a method for particle beam induced etching of a photolithography mask. In this case, a particle beam, in particular an electron beam, and an etching gas are supplied to a site on the photolithography mask to be etched. The particle beam activates a local chemical reaction between the material of the photolithography mask and the etching gas, as a result of which material is locally removed from the photolithography mask. SUMMARY OF THE INVENTION

[0008] Against this background, the problem addressed by the present invention is to provide an improved method and an improved apparatus for processing defects in a micro-lithography photomask.

[0009] According to a first aspect, there is provided a method for processing defects in a micro-lithography photomask, wherein a process gas is activated with the aid of a particle beam, and a control unit for controlling a deflection unit with a control bandwidth is provided, and the deflection unit for deflecting the particle beam is configured to direct the particle beam onto the photomask, a) providing an image of at least a part of the photomask; b) A step of confirming the repaired shape within the image based on the control bandwidth, the repaired shape including a defect, the step of confirming; c) A method is provided that includes supplying a particle beam to m pixels of the repaired shape with the aid of a deflection unit and activating a process gas for the purpose of treating the defect.

[0010] By considering the control bandwidth when confirming the repaired shape, it becomes possible to take into account the static behavior of the particle beam on the target pixel. As a result, an improved edge shape, in particular an improved edge steepness or an improved edge profile, can be obtained, especially when repairing a defect.

[0011] The treatment of the defect particularly includes etching of the defect, within which the material is locally removed from the photomask or material is deposited on the photomask in the region of the defect. As an example, with the proposed method, it becomes possible to better etch and remove excess structures within the region of the defect or to better reinforce missing structures within the region of the defect.

[0012] The repaired shape includes a defect, that is, the repaired shape encompasses the defect.

[0013] An image of at least a part of the photomask is recorded, for example, by a scanning electron microscope (SEM). As an example, an image of at least a part of the photomask has a spatial resolution of about several nanometers. An image can also be recorded using a scanning probe microscope (SPM) such as an atomic force microscope (AFM) or a scanning tunneling microscope (STM).

[0014] The method may particularly include a step of taking an image of at least a part of the photomask by a scanning electron microscope and / or a scanning probe microscope.

[0015] For example, a microlithography photomask is a photomask for an EUV lithography apparatus. In this case, EUV is an abbreviation for "extreme ultraviolet" and represents the wavelength of actinic light of 0.1 nm to 30 nm, particularly 13.5 nm. In an EUV lithography apparatus, a beam shaping and irradiation system, particularly in the form of a reflective optical element (reflective photomask), is used to direct EUV radiation onto the photomask (also called a "reticle"). The photomask has a structure that is imaged and reduced onto a wafer or the like by the projection system of the EUV lithography apparatus.

[0016] For example, a microlithography photomask can also be a photomask for a DUV lithography apparatus. In this case, DUV is an abbreviation for "deep ultraviolet" and represents the wavelength of actinic light of 30 nm to 250 nm, particularly 193 nm or 248 nm. In a DUV lithography apparatus, a beam shaping and irradiation system, particularly in the form of a transmissive optical element (transmissive photomask), is used to direct DUV radiation onto the photomask. The photomask has a structure that is imaged and reduced onto a wafer or the like by the projection system of the DUV lithography apparatus.

[0017] For example, a microlithography photomask includes a substrate and a structure formed by coating on the substrate. For example, the photomask is a transmissive photomask, and in this case, the imaged pattern is realized in the form of an absorptive (i.e., opaque or partially opaque) coating on a transparent substrate. Alternatively, the photomask can also be, for example, a reflective photomask, particularly for use in EUV lithography. In a plurality of embodiments, binary photomasks or phase shift photomasks are considered.

[0018] For example, the substrate is silicon dioxide (SiO 2) For example, it includes fused quartz. For example, the structured coating includes chromium, chromium compounds, tantalum compounds, and / or compounds composed of silicon, nitrogen, oxygen, and / or molybdenum. The substrate and / or the coating may include other materials.

[0019] In the case of a photomask for an EUV lithography apparatus, the substrate may alternately include a molybdenum layer and a silicon layer.

[0020] Using the proposed method, it is possible to identify, locate, and repair defects in a photomask, particularly defects in the structured coating of the photomask. In particular, a defect is a (absorptive or reflective) coating of the photomask that is inappropriately applied to the substrate. Using this method, the coating of a site on a photomask with insufficient coating can be reinforced. Furthermore, using this method, the coating can be removed from a site on a photomask where the coating is inappropriately applied.

[0021] For this purpose, in the recorded image of at least a part of the photomask, the geometry of the defect is determined. As an example, the two-dimensional geometry of the defect is determined. The determined geometry of the defect is hereinafter referred to as the so-called repair geometry.

[0022] For the particle beam induced treatment of the repair shape, m pixels are defined within the repair shape. In the process of the method, the particle beam is directed at each of the m pixels of the repair shape. In particular, the maximum intensity value of the electron beam is directed at the center of each of the m pixels. In other words, the m pixels of the repair shape represent a raster of the repair shape for particle beam induced treatment, in particular a two-dimensional raster. For example, the m pixels of the repair shape correspond to the incident area of the particle beam during the particle beam induced treatment of the defect. For example, the pixel size is selected such that the intensity distribution of the electron beam directed at the center of the pixel drops to a predefined intensity at the edge of the pixel, based on the Gaussian intensity distribution of the electron beam. The predefined intensity may correspond to a drop to half of the maximum intensity value of the electron beam, or otherwise to a drop to some other fraction of this maximum intensity value. For example, the pixel size and / or the electron beam full width at half maximum are in the sub-nanometer range or on the order of a few nanometers.

[0023] For example, the process gas is a precursor gas and / or an etching gas. For example, the process gas can be a mixture of a plurality of gas components, i.e., a process gas mixture. For example, the process gas can be a mixture of a plurality of gas components, each having a specific molecular type only.

[0024] In particular, alkyl compounds of main group elements, metals, or transition elements can be regarded as precursor gases suitable for the deposition or growth of raised structures. These examples are (cyclopentadienyl)trimethylplatinum (CpPtMe 3 Me = CH 4 ), (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe 3 ), tetramethyltin (SnMe 4 ), trimethylgallium (GaMe 3 ), ferrocene (Cp 2 Fe), bis-allylchromium (Ar 2 Cr), and / or carbonyl compounds of main group elements, metals, or transition elements, for example, chromium hexacarbonyl (Cr(CO) 6)、Molybdenum hexacarbonyl (Mo(CO) 6 )、Tungsten hexacarbonyl (W(CO) 6 )、Dicobalt octacarbonyl (Co 2 (CO) 8 )、Triruthenium dodecacarbonyl (Ru 3 (CO) 12 )、Iron pentacarbonyl (Fe(CO) 5 ) etc., and / or alkoxide compounds of main group elements, metals, or transition elements, for example, tetraethyl orthosilicate (Si(OC 2 H 5 ) 4 )、Tetraisopropoxytitanium (Ti(OC 3 H 7 ) 4 ) etc., and / or halide compounds of main group elements, metals, or transition elements, for example, tungsten hexafluoride (WF 6 )、Tungsten hexachloride (WCl 6 )、Titanium tetrachloride (TiCl 4 )、Boron trifluoride (BF 3 )、Silicon tetrachloride (SiCl 4 ) etc., and / or complexes containing main group elements, metals, or transition elements, for example, copper bis(hexafluoroacetylacetonate) (Cu(C 5 F 6 HO 2 ) 2 )、Dimethylgold trifluoroacetylacetonate (Me 2 Au(C 5 F 3 H 4 O 2 )) etc., and / or organic compounds, for example, carbon monoxide (CO), carbon dioxide (CO 2 )、Aliphatic and / or aromatic hydrocarbons, etc.

[0025] For example, the etching gas may contain the following: Xenon difluoride (XeF 2 )、Xenon dichloride (XeCl 2 )、Xenon tetrachloride (XeCl 4 )、Water vapor (H 2O), heavy water (D 2 O), oxygen (O 2 ), ozone (O 3 ), ammonia (NH 3 ), nitrosyl chloride (NOCl), and / or the following halide compounds: XNO, XONO 2 , X 2 O, XO 2 , X 2 O 2 , X 2 O 4 , X 2 O 6 , where X is a halide, one of them. A further etching gas for etching one or more of the deposited test structures is specified in Applicant's U.S. Patent Application No. 13 / 0103281.

[0026] The process gas is an additional gas, for example, hydrogen peroxide (H 2 O 2 ), nitrous oxide (N 2 O), nitrogen oxides (NO), nitrogen dioxide (NO 2 ), nitric acid (HNO 3 ), and other oxygen-containing gases such as oxidizing gases, and / or chlorine (Cl 2 ), hydrogen chloride (HCl), hydrogen fluoride (HF), iodine (I 2 ), hydrogen iodide (HI), bromine (Br 2 ), hydrogen bromide (HBr), phosphorus trichloride (PCl 3 ), phosphorus pentachloride (PCl 5 ), phosphorus trifluoride (PF 3 ), and other halogen-containing gases such as halides, and / or hydrogen (H 2 ), ammonia (NH 3 ), methane (CH 4 ), and other hydrogen-containing gases such as reducing gases may further be included. These additional gases can be used, for example, as buffer gases, as passivation media, etc. in the etching process.

[0027] For example, the activating particle beam includes a particle beam source for generating a particle beam, a particle beam guiding device (e.g., a scanning unit) configured to direct the particle beam toward each pixel of one repair shape, a plurality of repair shapes, or each repair partial shape of a photomask, and a particle beam shaping device (e.g., an electron optical system or a beam optical system) configured to shape, particularly focus, the particle beam, at least one storage container configured to store a process gas or at least one gas component of the process gas, and at least one gas supply device configured to supply the process gas or at least one gas component of the process gas to each pixel of one repair shape, a plurality of repair shapes, or each repair partial shape at a predetermined gas flow rate. It can be supplied by the function of a device including these components.

[0028] The activating particle beam includes, for example, an electron beam, an ion beam, and / or a laser beam.

[0029] For example, the electron beam is supplied with the aid of a modified scanning electron microscope. For example, an image of at least a part of the photomask is recorded using the same modified scanning electron microscope that supplies the activating electron beam.

[0030] The activating particle beam particularly activates a local chemical reaction between the material of the photomask and the process gas, and this chemical reaction locally causes the deposition of material from the gas phase onto the photomask or the transfer of the material of the photomask into the gas phase.

[0031] The activating particle beam is sequentially supplied to each pixel of one repair shape, a plurality of repair shapes, or each repair partial shape, for example, by a particle beam guiding device (particularly a deflection unit). In step c) of the method, the activating particle beam stays on each pixel for a predetermined residence time. For example, the residence time is 100 ns.

[0032] The repair shape may include the whole or a part of the defect. The repair shape may be kidney-shaped, U-shaped, or ring-shaped. In this case, if there is nothing else that stipulates otherwise, "repair shape" may refer to the repaired partial shape.

[0033] For example, the numbers "m" and / or "n" (see below) are in each case greater than 100, 1000, 10000, 100000, or 1000000.

[0034] According to an embodiment, the control bandwidth is confirmed or provided before step a), in particular, before or when operating the particle beam column for the purpose of performing steps a) to c), and preferably, the confirmed or provided control bandwidth or a value derived from the control bandwidth is stored in the data memory before step b) and used in step b).

[0035] The control bandwidth or a value derived from the control bandwidth can in particular be stored in a computer program, and this computer program is executed within the scope of the method described above.

[0036] According to a further embodiment, step b) b1) subdividing the repair shape including the defect into k repaired partial shapes based on the control bandwidth and selecting one of the k repaired partial shapes, and / or, b2) subdividing the repair shape including the defect into k repaired partial shapes and selecting one of the k repaired partial shapes, the selection being carried out based on the control bandwidth, including subdividing and selecting. Step c) feeding the particle beam to m pixels of the selected k repaired partial shapes with the aid of the deflection unit and activating a process gas for the purpose of processing the defect.

[0037] In this case, the control bandwidth can be considered in advance when determining a series of repair sub-shapes that are continuously swept over time by a particle beam, particularly during the subdivision of the repair shape or during the selection of each repair sub-shape. According to a certain deformation mode, both the subdivision and the selection can be carried out based on the control bandwidth. "k" can be 2 or more, 10 or more, or 100 or more.

[0038] According to a further embodiment, the confirmation by step b) or the subdivision by step b1) and / or the selection by step b2) is carried out based on the interval or jump width between two repair shapes or between two of the k repair sub-shapes.

[0039] The greater the interval or jump width, the longer the time generally is until the particle beam reaches a steady state again. Therefore, it is particularly advantageous to link this information with the control bandwidth.

[0040] According to a further embodiment, step c) With the help of the deflection unit, supply the particle beam to m pixels of the first repair shape or the first of the k repair sub-shapes and activate the process gas for the purpose of treating the defect; With the help of the deflection unit, supply the particle beam to n pixels of the second repair shape or the second of the k repair sub-shapes and activate the process gas for the purpose of treating the defect.

[0041] In particular, each of the k repair sub-shapes can be swept or raster scanned more than 100 times or more than 1000 times by the particle beam before there is a switch to the next repair shape, and then, in turn, the next repair shape can also be swept more than 100 times or more than 1000 times by the particle beam. The particle beam can be deactivated or raster scanned during the repetition so that the process gas can flow into each repair sub-shape.

[0042] According to a further embodiment, the first pixel and / or the last pixel among the n or m pixels are selected in a randomized manner.

[0043] This prevents an undesirable pattern from occurring on the photomask.

[0044] According to a further embodiment, each of the k repair sub-shapes is formed without interruption in the scanning direction of the particle beam.

[0045] As a result, these repair sub-shapes can be scanned quickly without a jump effect (stationarity of the particle beam).

[0046] According to a further embodiment, the sweep line method is used in step b1) or b2).

[0047] This mathematical method enables the repair shape to be simply and efficiently divided into a plurality of repair sub-shapes, each of which is convex and / or is embodied without interruption at least in the scanning direction (i.e., without cutouts). Therefore, the particle beam does not need to cross gaps, cutouts, etc. This avoids the influence of jumps or stationarity.

[0048] According to a further embodiment, the repair shape includes cutouts, and its size dimension is less than 5 nm to less than 10 μm.

[0049] According to a further embodiment, the distance between two pixels within each one of the repair shape or the k repair sub-shapes is less than 40 nm, less than 20 nm, or less than 5 nm.

[0050] According to a further embodiment, the deflection unit includes a multipole, particularly an octupole, for beam deflection purposes.

[0051] Instead of the multipole or octupole, other means for beam deflection, such as capacitor plates or magnetic coils, can be used.

[0052] According to a further embodiment, in step c), the particle beam is moved along a straight line and / or along a line parallel and / or perpendicular to this straight line.

[0053] According to a further embodiment, in step c), the particle beam is moved parallel to the longest side and / or to one of the k repair sub-shapes.

[0054] It is thus possible to avoid unwanted jumps of the particle beam, or an effective sweeping of the repair shape or repair sub-shape by the particle beam is thus obtained.

[0055] According to a further embodiment, in step b), a first repair shape including a defect and a second repair shape are identified, and the second repair shape is at least partially located within the first repair shape.

[0056] Advantageously, something known as the bias effect can thus be obtained. Similarly in this case, the static behavior of the particle beam at the target position (target pixel) can be taken into account.

[0057] According to a further embodiment, the contour of the second repair shape is partially recessed with respect to the contour of the first repair shape.

[0058] According to a further embodiment, the second repair shape partially has the same contour as the first repair shape.

[0059] Depending on the jump pixel or target pixel of the particle beam, an offset of the contour with respect to the first repair shape may be necessary, but in some cases it may not be.

[0060] According to a further embodiment, when the first and second repair shapes overlap between two adjacent contours of the first and second repair shapes, one or more pixels are positioned along a straight line intersecting the two adjacent contours.

[0061] According to a second aspect, a computer program product is provided. The computer program product includes instructions that, when executed by an apparatus for processing defects of a photomask for a lithographic apparatus, direct the apparatus to perform the steps of the method described above.

[0062] The computer program product, for example a computer program medium, may be provided or supplied as, for example, a storage medium such as a memory card, a USB stick, a CD-ROM, a DVD, or alternatively in the form of a file downloadable from a server on a network. For example, in a wireless communication network this can be achieved by transferring a suitable file having the computer program product or computer program means.

[0063] According to a third aspect, an apparatus for processing defects of a microlithography photomask is provided. The apparatus comprises a process gas supply device for supplying a process gas, and a particle source for supplying a particle beam, and a deflection unit for deflecting the particle beam to supply the particle beam to m pixels of a repair shape and to activate the process gas, and a control unit for controlling the deflection unit with a control bandwidth, and a detector unit for providing an image of at least a part of the photomask, and a confirmation unit for confirming a repair shape in the image based on the control bandwidth, wherein the repair shape includes a defect.

[0064] Each of the aforementioned and following units, for example, an arithmetic unit, a control unit, or a verification unit, can be implemented in hardware and / or software. When implemented as hardware, the corresponding unit can be embodied as a device or as part of a device, for example, as a computer or as a microprocessor. For example, the device can include a central processing unit (CPU), a graphics processing unit (GPU), programmable hardware logic (e.g., a field programmable gate array, FPGA), an application specific integrated circuit (ASIC), etc. Further, one or more units may be implemented together in a single hardware device, and these can share, for example, memory, interfaces, etc. These units can also be realized in separate hardware components.

[0065] In this case, “a(n)” should not necessarily be understood as strictly limiting to exactly one element. Rather, a plurality of elements, for example, two, three, or more, may also be provided. Any other numbers used herein should not be understood in the sense of being limited to the exactly stated number of elements. Rather, numerical deviations up and down are possible unless otherwise indicated.

[0066] Further possible implementations of the present invention also include combinations of features or embodiments that are not explicitly stated, described above with respect to the exemplary embodiments or described below. In this case, those skilled in the art will also add the individual aspects as improvements or supplements to each basic form of the present invention.

[0067] Further advantageous configurations and aspects of the present invention are the subject matter of the dependent claims and also of the exemplary embodiments of the present invention described below. The present invention will be described in detail below based on the preferred embodiments with reference to the accompanying drawings.

Brief Description of the Drawings

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[0069] Unless otherwise indicated, the same or functionally identical elements are denoted by the same reference numerals in the figures. Further, note that the depictions in the figures are not necessarily drawn at an exact scale.

[0070] FIG. 1 schematically shows details of a microlithography photomask 100. In the example shown, the photomask 100 is a transmissive photolithography mask 100. The photomask 100 includes a substrate 102. The substrate 102 is optically transparent, particularly at the wavelength at which the photomask 100 is exposed. By way of example, the material of the substrate 100 includes fused quartz.

[0071] A structured coating 104 (pattern element 104) is applied to the substrate 102. In particular, the coating 104 is a coating made of an absorbent material. For example, the material of the coating 104 includes a chromium layer. For example, the thickness of the coating 104 ranges from 50 nm to 100 nm. The structural dimension B of the structure formed by the coating 104 on the substrate 102 of the photomask 100 may vary at different positions of the photomask 100. For example, in FIG. 1, the width B of a certain region is plotted as the structural dimension. For example, the structural dimension B is within the range of 20 to 200 nm. The structural dimension B may be larger than 200 nm, for example, on the order of micrometers.

[0072] In other examples, materials other than the mentioned materials can also be used for the substrate and the coating. Furthermore, the photomask 100 can also be a reflective photomask instead of a transmissive photomask. In this case, a reflective layer is applied instead of the absorption layer 104.

[0073] In some cases, for example, due to the etching process not being executed exactly as intended, defects D may occur during the manufacture of the photomask. In FIG. 1, such defects D are represented by hatching. This is extra material because the coating 104 was not removed from this region even though two adjacent coating regions 104 are assumed to be separate in the template of the photomask 100. Also, the defect D can be said to form a connecting piece. In this case, the dimension of the defect D corresponds to the structural dimension B. Other defects smaller than the structural dimension B, for example, defects in the range of 5 to 20 nm, are also known. In order for the structure manufactured using the photomask in the lithographic apparatus to have the desired shape on the wafer, and thus for the semiconductor component manufactured in this way to perform the desired function, defects such as the defect D shown in FIG. 1, or otherwise other defects, need to be repaired. In this example, in a targeted manner, for example, by particle beam induced etching, it is necessary to remove the connecting piece.

[0074] Figures 2 to 4 are used to illustrate possible procedures for repairing the defect D shown in FIG. 2. The “healthy” area is represented by 200 on the left side of FIG. 2. That is, the coating 104 or the substrate 102 conforms to the target specifications in this area. Subsequently, the details 200 of the healthy image are copied and placed over the defect D, as is apparent from the reference numeral 200'. FIG. 3 shows an enlarged view of the defect D. The defect D is formed by a convex excess material in this exemplary embodiment. The material that needs to be removed is clarified by the overlay of the healthy material area 200.

[0075] In the case of mask repair using an electron beam, at this point, the area D is scanned thousands of times with the electron beam to remove the defect. Whether this is related to so-called white defects or black defects is not important for the time being.

[0076] FIG. 4 shows various deformations of the scan for moving the electron beam over the defect D to appropriately etch away the coating 104 under the activation of the process gas (or in other deformation modes, for depositing material from the process gas for repair purposes). For example, the pattern shown in FIG. 4 is traversed or raster scanned 100 to 1,000,000 times until the corresponding defect is removed or deposited.

[0077] In FIG. 4, the meandering x scan is represented by 400, the meandering y scan is represented by 402, and the raster scan is represented by 404. Starting from the meandering x scan 400 in the center of FIG. 4, the solid line 406 (hereinafter referred to as the “scan line”) there represents a column of pixels 410 that are sequentially scanned or raster scanned. The particle beam is offset in the y direction at the end of each scan line 406 (hereinafter referred to as a “jump” 408). Immediately thereafter, the particle beam is moved in the negative x direction parallel to the previous scan line 406 before a further jump 408 is scheduled.

[0078] Scanning in the x - direction can be carried out just as easily in the y - direction as well. As a result, the pixels here are scanned in the y - direction and the jumps are carried out in the x - direction. This is shown on the right side of Figure 4 (the meandering y - scan 402). What is known as a raster scan 404 is shown on the left side of Figure 4. In this case, there are jumps that return diagonally at the end of each scan line 406, and as a result, the starting point returns to x = 0 (the origin O).

[0079] Pixel 410 corresponds to the image point of the detailed image 200’ in Figure 2. Each pixel 410 corresponds to a location on the photomask 100. There, an electron beam is incident on the process gas, and an etching or deposition process is triggered at this location. The pixel pitch is, for example, less than 40 nm, less than 20 nm, less than 5 nm. In Figure 4, this pitch is shown as an example for two adjacent pixels 410 and is represented by A in Figure 4.

[0080] In the region of the scan line 406, the electron beam moves at a defined speed. In the process, individual pixels 410 are addressed, that is, the electron beam stays at each pixel 410 for a defined period (the “dwell time”). The electron beam moves as fast as possible within the region of each jump 408. For example, the dwell time can be set to 10 - 500 nanoseconds. When the dwell time ends, the electron beam moves to the next pixel, and the intermediate region between two adjacent pixels 410 within the interval A is swept. The electron beam is not deactivated within the intermediate region. However, since the exposure time within the intermediate region is very short, the electron beam does not exhibit any significant effect. For this reason, the electron beam is not deactivated at the end of the dwell time at the first pixel but moves to the next pixel and is reactivated there.

[0081] The same applies to jump 408. The last pixel of scan line 406 is represented by reference numeral 410’ as an example. The first pixel of the next scan line 406 is represented by 410”. The electron beam moves between pixels 410’ and 410” as fast as possible. For example, the electron beam is not deactivated at the end of the dwell time at pixel 410’ and is reactivated at the next pixel 410”.

[0082] The jump between two adjacent pixels 410 is characterized in that the scanning direction (in this case the positive x direction) is maintained. In contrast, the jump between pixel 410 and 410’ in different scan lines 406 is characterized by a change from one scanning direction (in this case the positive x direction) to another, optionally opposite, scanning direction (in this case the negative x direction). There is a jump from one repair (sub) shape to another between the two repair shapes 500 and 502 (see below).

[0083] FIG. 5 shows defect D and the assigned repair shape 108 identified from the image detail 200’. With the assistance of a computer device and an appropriate algorithm, the repair shape 108 is decomposed, for example, into two repair sub - shapes (sub) 500, 502. The repair sub - shapes are, for example, in this case a rectangle 500 and a rectangular ring 502, but are spaced apart from each other in the scanning direction x. Thus, the first scan line 406 occurs within the repair sub - region 500, followed by a jump 504, and then a further scan line 406’ occurs within the repair sub - shape 502. Here, since a meandering x - scan 400 is performed as an example, the electron beam is offset in the y direction at the end of scan line 406’, thereby causing a jump 408. Thereafter, the electron beam is returned in the direction of the origin O parallel to scan line 406.

[0084] The repair partial shape 502 includes a cutout portion 506. This is the area surrounded by the ring 502. For example, the cutout portion 506 may have a width d that is at least 500 nm and less than 10 μm in the scanning direction x. Accordingly, there are further jumps 508 of the electron beam within the repair shape 502.

[0085] FIG. 6 shows a plot with time t on the horizontal axis and jump width P on the vertical axis. As described, the electron beam moves as fast as possible within the regions of jumps 408, 504, 506. For this purpose, the electron beam is first strongly accelerated and advanced from position P0 (the first pixel), and then strongly decelerated toward position P1 (the next pixel). In the case of an electron beam column, the electron beam is deflected from position P0 toward position P1 by a deflection unit (shown in FIG. 8).

[0086] For example, the deflection unit exists as an octupole (or other multipole) at the lower end of the electron beam column. The octupole includes a plurality of coils or electrodes that generate an electric field or a magnetic field for the purpose of beam deflection. In other embodiments, instead of an octupole, one or more capacitors, particularly capacitor plates, can also be used. The deflection unit is controlled by a control unit (shown in FIG. 8). As a result of the control unit having a finite control bandwidth, the electron beam will necessarily settle at the end point of the movement (static curve 600), i.e., position P1, initially.

[0087] As shown at point P2 in FIG. 6, when the jump width is shorter, the amplitude AP of the static curve 600' is smaller than the amplitude AP of the static curve 600. This means that initially, there is a different dose distribution (electron dose) at the target points P1 or P2 of jumps 408, 504, 506 with respect to the initial point P0. It is also clear that, with the same control bandwidth, the smaller the jump width, the better the electron dose after the jump can be concentrated at a single point (see position P2). The same also holds when the control bandwidth is widened while keeping the jump width unchanged.

[0088] In FIG. 7, a plan view of the partial details of the photomask 100 is shown on the left. In the region shown, the photomask 100 comprises two coatings 104 that are separated from each other by an exposed region 102 where the substrate is visible. In an exemplary embodiment, the electron beam jumps from point P0 to point P1. The dwell time at point P0 (corresponding to the last pixel of a scanning line not shown) is, similar to point P1 (the first pixel of a scanning line not shown), for example 20 ns. The control bandwidth is 5 MHz.

[0089] At the edge 702 of the structure 104, a smear due to the static curve 600 (see FIG. 6) has occurred. Corresponding to this, since the increase in the dose distribution becomes flat, the edge steepness (so-called sidewall angle) of the edge repair is affected negatively. The problem of static behavior does not occur at the jump point, and thus, a sharp edge exists here. This can also be seen similarly from the left image in FIG. 7.

[0090] The photomask 100' is shown on the right side of FIG. 7. In this case, the structure corresponds to the structure in the left figure. However, the electron beam column used for the processing of the photomask 100' has a higher control bandwidth, specifically 100 MHz. Therefore, the amplitude AP of the static curve (see 600' in FIG. 6) is smaller. For this reason, the edge steepness is larger compared to the left figure. Therefore, the edge 702' is in a sharp embodiment in the right figure of FIG. 7.

[0091] FIG. 8 shows an apparatus 800 for particle beam induced processing of a defect D of a microlithography photomask 100, for example the defect D of the photomask 100 in FIGS. 1, 2, 3, 5, and 7. For example, the apparatus 800 is a repair tool for the photomask 100 for a DUV or EUV lithography apparatus.

[0092] FIG. 8 schematically shows a cross-section through some components of an apparatus 800 for particle beam induced repair of a defect D in a photomask 100, which in this case can be used for etching. Further, the apparatus 800 can also be used for imaging a photomask, in particular the structured coating 104 of the mask 100 and the defect D, before, during, and after the repair process is carried out.

[0093] The apparatus 800 shown in FIG. 8 represents a modified scanning electron microscope 800. In this case, in order to repair the defect D, a particle beam in the form of an electron beam 802 is used. Using the electron beam 802 as an active particle beam has the advantage that the photomask 100, in particular its substrate 102, is substantially not damaged or only slightly damaged by the electron beam 802.

[0094] In a plurality of embodiments, instead of or in addition to the electron beam 802, a laser beam can be used to activate a local particle beam induced repair process of the photomask 100 (not shown in FIG. 8). Further, instead of the electron beam and / or the laser beam, an ion beam, an atomic beam, and / or a molecular beam for activating a local chemical reaction can be used (not shown in FIG. 8).

[0095] Most of the apparatus 800 is arranged within a vacuum housing 804 maintained at a specific gas pressure by a vacuum pump 806.

[0096] A photomask 100 to be processed is arranged on a sample stage 808. By way of example, the sample stage 808 is configured to define the position of the photomask 100 with an accuracy of a few nanometers in three spatial directions and about three rotation axes.

[0097] Apparatus 800 includes an electron column 810. The electron column 810 includes an electron source 812 for supplying an activated electron beam 802. Further, the electron column 810 includes an electron optical system or beam optical system 814. The electron source 812 generates an electron beam 802, and the electron optical system or beam optical system 814 focuses the electron beam 802 and directs the electron beam 802 toward a photomask 100 at the output of the column 810. The electron column 810 further includes a deflection unit 816 (scanning unit 816) configured to direct the electron beam 802 across the surface of the photomask 100, i.e., to perform a raster scan or scan with the electron beam 802.

[0098] Apparatus 800 further includes a detector 818 for detecting secondary electrons and / or backscattered electrons generated by the photomask 800 by the incident electron beam 802. For example, as shown, the detector 818 is arranged in a ring-shaped pattern around the electron beam 802 within the electron column 810. As an alternative and / or addition to the detector 818, apparatus 800 may also include other / further detectors (not shown in FIG. 8) for detecting secondary electrons and / or backscattered electrons.

[0099] Further, apparatus 800 may include one or more scanning probe microscopes, such as a scanning force microscope, that can be used to analyze a defect D of the photomask 100 (not shown in FIG. 8).

[0100] Apparatus 800 further includes a gas supply device 820 for supplying a process gas to the surface of the photomask 100. For example, the gas supply device 820 includes a valve 822 and a gas line 824. The electron beam 802 directed by the electron column 810 to a location on the surface of the photomask 100 can perform an electron beam induced process (EBIP) in conjunction with the process gas supplied externally by the gas supply device 820 through the valve 822 and the gas line 824. In particular, the above process includes material deposition and / or etching.

[0101] The apparatus 800 further comprises an arithmetic unit 826 having a control unit 828, a verification unit 830, and a memory unit 832, for example a computer. In the example of FIG. 8, the arithmetic unit 826 is arranged outside the vacuum housing 804.

[0102] In particular, the arithmetic unit 826 controls the supply of the electron beam 802 by controlling the electron column 810. In particular, the control unit 828 controls the raster scanning of the electron beam 802 over the surface of the photomask 100 by controlling the deflection unit 816. Further, the arithmetic unit 826 controls the supply of the process gas by controlling the gas supply device 820.

[0103] Furthermore, the arithmetic unit 826 can receive measurement data from the detector 818 and / or other detectors of the apparatus 800, create an image from the measurement data, and display this image on a monitor (not shown). Further, the image created from the measurement data can be stored in the memory unit 832 of the arithmetic unit 826.

[0104] In order to check the photomask 100, in particular the structured coating 104 of the photomask 100, the apparatus 800 is configured to capture an image of the photomask 100 (FIG. 1) or an image 200' of a detail of the photomask 100 from measurement data from the detector 818 and / or other detectors of the apparatus 800. As an example, the spatial resolution of the image 300 is on the order of a few nanometers.

[0105] The arithmetic unit 826, in particular the verification unit 830, is configured to recognize defects D (FIG. 1) in the recorded image 200', to identify the positions of the above-mentioned defects, and to check the geometric shape (repair shape 108) of the defects D. For example, the verified repair shape 108 is a two-dimensional geometric shape.

[0106] The computing device 826, in particular the verification unit 830, is configured to place the repaired shape 108 within a grid comprising m pixels 410 (see FIG. 4). For example, the repaired shape 108 comprises one million pixels 304 (m = 1000000). For example, the size of the pixel 304 is 1.5 nm × 1.5 nm. During the process of the repair method, the electron beam 802 is directed multiple times to the center of each pixel 410 by the deflection unit 816. In particular, the intensity maximum of the Gaussian intensity profile of the electron beam 802 is directed multiple times to the center of each pixel 410 during the process of the method.

[0107] FIG. 9 schematically shows some components of FIG. 8. The control unit 828 creates a control signal XS that it uses to control the deflection unit 816. FIG. 9A shows the amplitude A of the control signal XS as a function of the frequency f XS The control unit 828 can be regarded as a low-pass filter. The low-pass filter passes signals with frequencies up to the cutoff frequency GF - herein referred to as the control bandwidth - without substantially changing them. In contrast, the output signal XS of the control unit 828 is significantly attenuated above the cutoff frequency GF. Accordingly, the control signal XS is composed of frequency components below the control bandwidth GF. The control signal XS is preferably analog. The control unit 828 itself can have an analog or digital implementation. In particular, the control unit 828 receives a digital signal from the verification unit 830, and this digital signal is converted into an analog signal within the control unit 828.

[0108] For example, the function depicted in FIG. 9A can be verified by examining the control signal XS for its frequency components. For example, the control bandwidth GF can be defined as the frequency f when the amplitude A XS drops below a value of 80% of the maximum amplitude A XS as plotted as an example in FIG. 9A. The control bandwidth GF is provided to the verification unit 830.

[0109] In one variant, the control bandwidth GF is read from the control unit 828 after calibration of the device 800 or during operation of the device 800, i.e., during the raster scan of the pixel 410. As a result, it becomes possible for the verification unit 830 to respond to changes in the control bandwidth.

[0110] In another variant, the control signal XS is measured after operating and calibrating the device 800, and the control bandwidth GF is verified, more specifically calculated, from the measurement data. The control bandwidth GF thus determined is stored, for example, in the data memory 832 (see FIG. 8). In particular, the control bandwidth GF can be stored as part of a computer program executed on the arithmetic unit 826. In particular, the computer program can form part of the verification unit 830. In the verification unit 830, the control bandwidth GF is used to verify the repaired shape 108 having the defect D based on the above control bandwidth.

[0111] Overall, the corresponding method is depicted in FIG. 10. In step S1, at least a partial image of the photomask 100 is recorded with the aid of the device 800 and provided by the device 800. In particular, the recording is carried out with the aid of the detector unit 818.

[0112] In step S2, the repaired shape 108 is verified in the image 200’, precisely in a manner dependent on the control bandwidth GF. The repaired shape 108 contains the defect D, precisely at least a part or all of it. How the repaired shape 108 is verified in detail will be explained in detail below. It is important to note that this verification does not have to be carried out in a manner directly dependent on the control bandwidth GF. In particular, it is also possible to use a value derived from the control bandwidth GF. As already explained for the control bandwidth GF, this value can be read from the control unit 828 and / or optionally provided to the memory unit 832 as part of the aforementioned computer program. Such an indirect use of the control bandwidth GF is also encompassed by the present case.

[0113] In step S3, the particle beam 802 is supplied, with the aid of the deflection unit 816, to the m pixels 410 of the repair shape 108, where the particle beam activates a process gas, thereby ultimately processing, and more particularly etching or depositing, the defect.

[0114] Step S2 can be designed to carry out one or more of the variant forms S2-1 to S2-3 depicted on the left side of FIG. 10. In this context, one of the variant forms S2-1 to S2-3 can be carried out in the apparatus 800, or alternatively, a plurality of variant forms can be carried out, in which case one of the variant forms S2-2 to S2-3 is optionally selected in an automated manner depending on the application.

[0115] Variants S2-1 and S2-2 will be explained in detail below, in particular with reference to FIGS. 13 to 15. For variant S2-3, see FIGS. 22 to 25.

[0116] A possible embodiment of step S2-1 of the method will be described with reference to FIGS. 11 and 12. FIGS. 11 and 12 each show an annular defect D, or corresponding repair shapes 108, 108'. These each include cutouts 1100 and 1200 in which the pixels are not scanned, or this region remains unaffected by the treatment with the electron beam 802. The diameter of the cutout 1100 is designated d1 and the diameter of the cutout 1200 is designated d2. In the case of the diameter d1, i.e., the repair shape 108, the verification unit 830 determines here that the corresponding jump width is too large and thus does not result in an acceptable edge. This is taking into account the determined control bandwidth GF. In response to this, the verification unit 830 subdivides the repair shape 108 into two semi-circular repair shapes 1102, 1104, which are then scanned by separate meandering scans 400, 400'.

[0117] In contrast, in view of the diameter d2 that is smaller compared to the control bandwidth GF and the diameter d1, the confirmation unit 830 evaluates that the defect D or the repair shape 108’ can be scanned using a meandering x-scan over the entire repair shape 108’. Therefore, the scan line 406 has a jump 1202 within the area of the cutout 1200.

[0118] FIG. 13 shows the repair shape 108 of the defect D for the purpose of explaining step S2-2, and this repair shape 108 is subdivided into, for example, three repair partial shapes 1300, 1302, and 1304 with the help of the confirmation unit 830. For example, the confirmation unit 830 determines that the jump width 1306 in the scanning direction x is still acceptable from the perspective of the control bandwidth GF, and thus it can be determined to scan both the repair shape 1300 and the repair shape 1302 on the portion 1308 in the y direction (i.e., the direction transverse to the scanning direction x) using one scan line 406.

[0119] This does not apply to the repair shape 1304. In this case, the confirmation unit 830 determines that the jump width 1310 becomes too large from the perspective of the control bandwidth GF. Therefore, the repair shape 1304 is scanned separately only after or only before the repair shapes 1300 and 1302 are scanned.

[0120] FIG. 14 shows a rectangular defect D or a rectangular repair shape 108. For example, the rectangular repair shape 108 is subdivided again into rectangular repair shapes, and they form a grid in the x direction and the y direction. As an example, some of the repair shapes are labeled 1400 to 1410. The subdivision into the repair shapes 1400 to 1410, i.e., the size of each rectangle, can be determined, for example, such that the process gas atmosphere is maintained to a sufficient extent during the raster scan of the pixels (not shown) of each rectangle 1400 to 1410 for etching or deposition. This cannot necessarily be guaranteed when the repair shape is too large.

[0121] The repair shapes 1400 to 1410 are each scanned independently, and thus each of them is assigned a meandering scan 400. For each of the repair shapes 1400 to 1410, the meandering scan 400 can be repeated thousands of times, for example, until there is a change to the next respective repair shape 1400 to 1410. This change is shown in FIG. 14 by jumps 1412, 1414, 1416, and 1418. These jumps, or the determination regarding the next jump destination repair shape, are determined by the confirmation unit 830 in consideration of the control bandwidth GF. Considering the control bandwidth GF, it can be found here that the individual jumps are too far in terms of obtaining sufficient edge steepness. For example, the control unit 830 may determine that jumps 1414 or 1416 are too far, but jumps 1412 and 1418 are acceptable. As shown for jump 1414 as an example, here it may also be determined that the jump to pixel 1420 is too far, but the jump to pixel 1422 is still acceptable.

[0122] The confirmation unit 830 can be further configured to select, in a randomized manner, the jump pixel shown here as pixel 1424 and / or the target pixel 1422 from the pixels included in the repair shape 1400 or 1406. This prevents the repetition of (undesirable) patterns determined by the jump positions and target positions that would normally be invariant from occurring on the photomask 100.

[0123] FIG. 15 shows an exemplary embodiment having a repair shape 108 corresponding to the repair shape of FIG. 5. However, here, subdivision into five sub - repair shapes 1500, 1502, 1504, 1506, and 1508 is performed. This is carried out such that acceptable jumps are made at any time given the control bandwidth GF.

[0124] In other cases, it should be noted that an acceptable repair shape 108 can be found in advance by changing the scanning direction from x to y from the viewpoint of the control bandwidth GF. This also applies to the case of the cutout portion 1510 formed with the same dimensions in the x and y directions. However, when the width of the cutout portion 1510 in the x direction is large and the depth in the y direction is shallow, changing the scanning direction from x to y will result in no more acceptable jump widths.

[0125] Figures 16 to 20 show various options for subdividing the repair shape 108 so that an acceptable jump width can be found from the viewpoint of the control bandwidth GF or so that jumps are completely avoided.

[0126] For example, the annular segment 108 in FIG. 16 is subdivided by the confirmation unit 830 into two semi-circular annular segments.

[0127] The kidney-shaped shape 108 in FIG. 17 is also subdivided by the confirmation unit 830 into two acceptable repair shapes.

[0128] Regarding the serrated edge region 1800 of the repair shape 108 in FIG. 18, the confirmation unit 830 determines that this repair shape can be scanned without jumping by a meandering x scan.

[0129] Regarding FIG. 19, the confirmation unit 830 subdivides the repair shape 108 into two repair shapes, specifically two polygons, in this case a quadrilateral 1900 and a pentagon 1902.

[0130] The repair shape 108 in FIG. 20 is partially kidney-shaped as well, but is subdivided into five repair shapes and can be traversed without jumping using a meandering x scan. The separation lines 2000, 2002, 2004, and 2006 plotted during the process are all directed towards the inflection points of the outer enclosing line 2010 of the repair shape 108 (one of which is represented by reference numeral 2008 as an example).

[0131] As described with reference to the above figures, in order to subdivide the repair shape 108 into the repair sub-shapes, the sweeping line method can be used in any case.

[0132] FIG. 21 shows the aforementioned aspect in which the scanning direction is selected based on the control bandwidth GF. The reference numeral 2100 represents the longest side of the repair shape 108. In the case of the repair shape 108 depicted in FIG. 21, jumps occur in the case of scanning in the x direction. In contrast, as shown by the scanning line 406, when the scanning is performed in the y direction (i.e., parallel to the longest side 2100), each jump is avoided. However, such a rotation can be performed only, for example, when it is determined by the confirmation unit 830 that this is necessary in view of the control bandwidth GF. Therefore, if the jump width in the scanning direction x is small, it is possible to cope without changing the scanning direction in the y direction (which also includes a 90° rotation of the photomask 100).

[0133] FIG. 22 shows again the repair shape 108 already known from FIG. 5. This repair shape 108 is subdivided into a rectangle 2200 and a rectangular ring 2202 (frame). All pixels corresponding to the defect D to be scanned are located therein.

[0134] Next, in order to execute step S2-3 (see FIG. 10), a repair shape 2300 is selected within the repair shape 2200 (see FIG. 23). This has a contour 2300 that is recessed with respect to the (right-hand) edge 2204. The edge 2204 of the repair shape 2200 is adjacent to a gap 2206 that will be bridged within the range of the meandering x-scan. The corresponding gap 2206 corresponds in this case to the corresponding jump of the electron beam 802 that enables the continuation of the scanning line 406 in the repair sub-region 2202.

[0135] FIG. 24 shows an enlarged view of a part of FIG. 23 in the region of the edge 2204. The electron beam 802 sequentially scans the pixels 2400, 2402, and 2404 in the scanning direction x. The electron beam jumps at the pixel 2404 and continues to advance on the scanning line 406 within the region 2202. This is acceptable for the repair process because the jumping is not associated with smearing or static behavior. If the electron beam moves in the opposite direction, i.e., the negative x direction - referring to the scanning line 406' within the region 2202 - the electron beam jumps there and lands on the repair sub-region 2200. In principle, if the scanning pattern has not changed, the electron beam lands on the pixel 2406. However, this results in an unintended edge flatness due to static behavior. Therefore, the second repair shape 2300 is retracted with respect to the first repair shape 2200 such that the electron beam reaches the pixel 2408 instead of the pixel 2406 after jumping over the gap 2206. This is also referred to as "biasing" in this case.

[0136] Therefore, a repair shape 2500 having retracted contours 2502 and 2504 as shown in FIG. 25 can also be confirmed with respect to the repair partial shape 2202, and in both cases, the static behavior of the electron beam 802 considering the control bandwidth GF there is taken into account.

[0137] Although the present invention has been described based on exemplary embodiments, the present invention can be variously modified.

Explanation of Reference Numerals

[0138] 100 Photomask 102 Substrate 104 Coating 108 Repair Shape 108’ Repair Shape 200 Details of an Image without Problems 200’ Details of a Defective Image 400 Sinuous x Scanning 400’ Sinuous x Scanning 402 Sinuous y Scanning 404 raster scan 406 scanning line 406’ scanning line 408 jump 410 pixel 410’ pixel 410’’ pixel 410’’’ pixel 500 repaired part shape 502 repaired part shape 504 jump 600 statically determinate curve 600’ statically determinate curve 700 jump 702 edge 702’ edge 800 device 802 electron beam 804 vacuum housing 806 vacuum pump 808 sample stage 810 electron column 812 electron source 814 electron optical system 816 deflection unit 818 detector unit 820 gas supply unit 822 valve 824 gas line 826 arithmetic unit 828 control unit 830 confirmation unit 832 memory unit 1100 cut-out part 1102 repaired part shape 1104 repaired part shape 1200 cut-out part 1202 jump 1300 repaired part shape 1302 repaired part shape 1304 repaired part shape 1306 jump 1308 overlapping part 1310 gap 1400 repaired part shape 1402 Repair partial shape 1404 Repair partial shape 1406 Repair partial shape 1408 Repair partial shape 1410 Repair partial shape 1412 Jump 1413 Jump 1414 Jump 1416 Jump 1418 Jump 1420 Pixel 1422 Pixel 1424 Pixel 1500 Repair partial shape 1502 Repair partial shape 1504 Repair partial shape 1506 Repair partial shape 1508 Repair partial shape 1510 Cut-out part 1800 Edge region 1900 Repair partial shape 1902 Repair partial shape 2000 Separation line 2002 Separation line 2004 Separation line 2006 Separation line 2008 Inflection point 2010 Contour 2100 Longest side 2200 Repair partial shape 2202 Repair partial shape 2204 Edge 2300 Repair partial shape 2302 Contour 2400 Pixel 2402 Pixel 2404 Pixel 2406 Virtual pixel 2408 Pixel 2410 Pixel 2500 Repair partial shape 2502 Contour 2504 Contour A Interval AP Amplitude A XS Amplitude B Structure Width d Width d1 Diameter d2 Diameter D Defect f Frequency GF Control Bandwidth O Origin P Position P0 Position P1 Position P2 Position Steps of S1~S3 Methods T Time x Scanning Direction XS Control Signal y Scanning Direction

Claims

1. A method for treating defects (D) in a microlithography photomask (100), comprising: a process gas being activated with the aid of a particle beam (802); a control unit (828) for controlling a deflection unit (816) with a control bandwidth (GF) is provided; the deflection unit (816) for deflecting the particle beam (802) is configured to direct the particle beam (802) onto the photomask (100); a) providing (S1) an image (200') of at least a portion of said photomask (100); b) identifying a repair feature (108, 500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508) in said image (200') based on said control bandwidth (GF), wherein said repair feature (108, 500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508) includes said defect (D); c) directing said particle beam (802) with the aid of said deflection unit (816) to m pixels (410) of said repair shape (108, 500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508) and activating said process gas in order to treat said defect (D); A method comprising:

2. 2. The method of claim 1, wherein the control bandwidth (GF) is ascertained or provided prior to step a), in particular prior to or upon operating the particle beam column (810) for performing steps a) to c), and, depending on preference, the ascertained or provided control bandwidth (GF) or a value derived from the control bandwidth (GF) is stored in a data memory (832) prior to step b) and used in step b).

3. Step b) is b1) subdividing (S2-1) the repair shape (108) including the defect (D) into k repair part shapes (1102, 1104) based on the control bandwidth (GF) and selecting one of the k repair part shapes (1102, 1104); and / or b2) subdividing (S2-2) the repair shape (108) including the defect (D) into k repair part shapes (1300-1304, 1400-1410) and selecting one of the k repair part shapes (1300-1304, 1400-1410), the selection being performed based on the control bandwidth (GF); Step c) is providing said particle beam (802) with the aid of said deflection unit (816) to m pixels (410) of said selected k repair part shapes (1300-1304, 1400-1410) and activating said process gas for treating said defects (D), The method according to claim 1 or 2.

4. The method according to any one of claims 1 to 3, wherein said checking according to step b) or said subdivision according to step b1) and / or said selection according to step b2) is performed based on a spacing or jump width (d1, d2, 1202, 1306, 1310, 1412-1418) between two repair shapes (108, 2200, 2002, 2300, 2500) or between two of the k repair part shapes (1300-1304, 1400-1410).

5. - delivering, with the aid of the deflection unit (816), the particle beam (802) to m pixels (410) of a first repair shape (2200, 2202) or of a first of the k repair part shapes (500) to activate the process gas in order to treat the defect (D); - delivering, with the aid of the deflection unit (816), the particle beam (802) to n pixels (410''') of a second repair shape (2300, 2500) or of a second of the k repair part shapes (502) to activate the process gas in order to treat the defect; The method according to any one of claims 1 to 4, comprising:

6. The method of any one of claims 1 to 5, wherein the first pixel (1422) and / or the last pixel (1424) of the m or n pixels are selected in a randomized manner.

7. The method according to any one of claims 3 to 6, wherein each of the k repair part shapes (1102, 1104, 1300-1304, 1400-1410) is formed uninterruptedly in a scanning direction (x) of the particle beam (802).

8. The method according to any one of claims 3 to 7, wherein in step b1) or b2) a swept line method is used.

9. The method of any one of claims 1 to 8, wherein the repair feature (108) comprises a cutout (506, 1100, 1200, 1510) having a maximum dimension (d, d1, d2) of at least 5 nm to less than 10 μm.

10. 10. The method of claim 1, wherein a spacing (A) between two pixels (410) within the repair shape (108) or each one of the k repair part shapes (500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508) is less than 40 nm, less than 20 nm, or less than 5 nm.

11. The method according to any one of claims 1 to 10, wherein the deflection unit (816) comprises an octupole for beam deflection purposes.

12. The method according to any one of claims 1 to 11, wherein in step c) the particle beam (802) is moved along a straight line (406, 406') and / or along a line (406, 406') parallel and / or perpendicular to the straight line (406, 406').

13. The method according to any one of claims 1 to 12, wherein in step c) the particle beam (802) is moved parallel to a longest side (2100) of the repair shape (108) and / or of one of the k repair part shapes (500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508).

14. 14. The method according to claim 1, wherein in step b) a first repair shape (2200, 2202) containing the defect (D) and a second repair shape (2300, 2500) are identified, the second repair shape (2300, 2500) being at least partially located within the first repair shape (2200, 2202).

15. The method of claim 14 , wherein a contour of the second repair shape (2300, 2500) is partially recessed relative to a contour of the first repair shape (2200, 2202).

16. 16. The method of claim 14 or 15, wherein the second repair shape (2300, 2500) has in part the same contour as the first repair shape (2200, 2202).

17. 17. The method according to claim 14, wherein when the first and second repair shapes (2200, 2202; 2300, 2500) overlap between two adjacent contours of the first and second repair shapes (2200, 2202; 2300, 2500), one or more pixels (2404, 2406) are positioned along a straight line (406, 406') that intersects with the two adjacent contours (2204, 2302, 2502, 2504).

18. 18. A computer program product comprising instructions which, when executed by an apparatus (800) for processing defects (D) in a microlithography photomask (100), instruct the apparatus (800) to perform steps (S1-S3) of the method according to any one of claims 1 to 17.

19. An apparatus (800) for processing defects (D) in a microlithography photomask (100), comprising: a process gas supply device (820) for supplying a process gas; a particle source (812) for providing a particle beam (802); a deflection unit (816) for deflecting said particle beam (802) to deliver said particle beam (802) to m pixels (410) of a repair shape (108, 500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508) and to activate said process gas; a control unit (828) for controlling said deflection unit (816) with a control bandwidth (GF); a detector unit (818) for providing an image (200') of at least a portion of said photomask (100); and a verification unit (830) for verifying the repair shape (108, 500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508) in the image (200') based on the control bandwidth (GF), wherein the repair shape (108, 500, 502, 1102, 1104, 1300-1304, 1400-1410, 1500-1508) includes the defect (D).

Images