Stabilization of a repaired area of ​​an object for lithography

Abstract

The present invention relates, inter alia, to a method for passivating a repair area of ​​a lithographic mask, wherein the method comprises a) supplying a passivation gas and b) directing a particle beam onto a passivation area of ​​the mask, wherein the passivation area has at least one section which lies outside the repair area.

Description

1. Technical area

[0001] The present invention relates to methods and apparatus for passivating a repaired region of a lithographic mask. 2. State of the art

[0002] As a result of the increasing integration density in the semiconductor industry, lithography masks (hereinafter also referred to as lithographic masks) must image increasingly smaller structures on wafers. On the lithography side, the trend toward increasing integration density is being addressed by shifting the exposure wavelength of lithography devices to ever smaller wavelengths.

[0003] Although lithographic masks are manufactured using state-of-the-art tools and in a controlled environment, it may still be necessary for a manufactured mask to contain spots or regions that do not meet the desired specifications (e.g., with regard to the mask's absorbing and / or phase-shifting transmission properties, resulting in an opaque defect, for example). Defects can also arise during the course of a mask's operation. This problem can be at least partially addressed by subjecting the mask in question to a repair process, e.g., a particle beam-based repair, in which excess material is removed and / or missing material is deposited.

[0004] In this context, a method and a device for etching a lithography mask are known from DE 10 2020 120 884 A1, for example.

[0005] With regard to the production of modern lithographic masks, it can be seen that due to the increasing integration density and the resulting smaller structures on the wafer, possible repairs of defects on the lithographic mask are becoming more frequent and increasingly complex. This increase in complexity is based on the fact that the structure size of potential defects and associated repair areas is shifting towards ever smaller structures. Both aspects can lead to an already repaired area degrading over time. This can particularly be the case if a further repair of the same mask is carried out at a different location, which could potentially negatively influence the first repair site, e.g. due to an undesired and / or uncontrolled progression of a repair (e.g. etching).

[0006] The present invention is therefore based on the problem of providing methods and devices which can further improve the repair process of lithographic masks and other objects, in particular masks with a high integration density, such as DUV and / or EUV masks, and enable a better controllable repair process. 3. Summary of the invention

[0007] According to an embodiment of the present invention, this problem is solved by methods according to claims 1 and 3 and by devices according to claims 25 and 27.

[0008] In a first embodiment, a method for passivating a repair region of a lithographic mask may comprise a) supplying a passivation gas and b) directing a particle beam onto a passivation region of the mask, wherein the passivation region has at least a portion lying outside the repair region.

[0009] By passivating the passivation region of the lithographic mask according to the invention, the respective passivated region can be stabilized so that crosstalk from a repair to another repair region on the mask does not have a significant impact on the passivated region. This enables efficient suppression of undesired progression of a repair process in an already repaired region. Thus, passivation of the passivation region can generally enable an improved and more targeted repair of a lithographic mask. In addition, for example, increased resistance to a reactive species during the manufacturing process of the lithographic mask and / or during cleaning of the lithographic mask can also be achieved.

[0010] The inventors recognized that it can be crucial for stabilizing a repair area that the passivation area does not coincide 1:1 with the repair area, but rather that the passivation area is located at least partially outside the repair area. This is because the edges of the repair area (at least some of them) are often particularly susceptible to subsequent defects. These can be particularly advantageously prevented by reliably passivating these edges over a large area, e.g., by not limiting the passivation area exactly to the repair area, but rather arranging it (also) outside the repair area.

[0011] The method may further comprise supplying a repair gas prior to supplying the passivation gas and directing the particle beam toward the repair region in the presence of the repair gas to repair a defect located in the repair region.

[0012] By supplying a repair gas, a selective etching process can be initiated on the lithographic mask with the aid of the particle beam. This allows any excess material from the lithographic mask in the repair area to be removed (e.g., by initiating an etching process). However, supplying a repair gas can also enable the particle beam to selectively deposit material in the repair area of ​​the lithographic mask. In both cases, the repair process can be followed by a passivation process according to the invention.

[0013] The repair gas can be supplied in the presence of a particle beam, which is preferably directed at the repair area. Alternatively or additionally, the repair gas can be supplied before the particle beam is directed at the repair area and / or between successive steps in which the particle beam is directed at the repair area.

[0014] The passivation region may further comprise at least one portion located in the repair region.

[0015] This can be beneficial for passivating the repair area, e.g., because the edges of the repair area can be covered even better. This can, in particular, contribute to an improved repair result of a repair method according to the invention.

[0016] According to a further embodiment, a method for repairing a lithographic mask may comprise: a) a particle beam-based repair of a defect in a repair region of the mask in the presence of a repair gas and b) a subsequent passivation of the repair region in a passivation region in the presence of a passivation gas, wherein the passivation is preferably carried out in a particle beam-based manner.

[0017] The inventive passivation of a repair region can, analogously to the above explanations, advantageously support the stabilization of the repair region or of a (subsequent) non-repaired region, so that disruption caused by further repair processes at neighboring locations can be suppressed. Furthermore, the subsequent passivation, and thus a sequential separation of the repair and passivation processes, enables passivation of the repair region without significantly affecting the repair process. Repair and passivation can be optimized independently of one another. This can contribute to improved repair of the lithographic mask.

[0018] The particle beam can be a charged or uncharged beam. It can contain massless particles and / or massive particles. In the case of a charged beam, the particle beam can be provided, for example, as an electron, ion, or proton beam. Alternatively, it is possible for the particle beam (in the case of an uncharged particle beam) to be provided, for example, as a neutron or photon beam or another suitable beam type.

[0019] The repair gas may, for example, contain Xe and / or F, preferably XeF2. To slow down and / or homogenize the repair process (preferably an etching process), the repair gas may additionally contain H and / or O, preferably H2O.

[0020] Passivation can be understood as a change (e.g. by covering) of a surface of the lithographic mask in the passivation region, so that a direct interaction of an atmosphere surrounding the lithographic mask, within which the repair and / or passivation takes place, with the material of the mask contained in the passivation region can be suppressed.

[0021] For example, the passivation step can be designed in such a way that the passivation region can withstand at least 5, 10, 15 or at least 20 subsequent etchings on the same sample, wherein the etchings are particle beam-based etchings of, for example, one repair region each on the same sample with an area of ​​0.25 µm 2 in which material with a thickness in the range of 10 nm to 150 nm is removed.

[0022] The passivation area can completely cover the repair area.

[0023] This can enable complete passivation of the repair area, so that a progressive, undesired repair process can be prevented across the entire repair area.

[0024] The passivation area may have a larger surface area than the repair area.

[0025] On the one hand, this can enable an integral overlap of the sections of the passivation area, thus enabling a generally increased stability of the passivation area.

[0026] The passivation region may extend at least partially along an edge portion of the repair region.

[0027] In this way, the edge section of the repair area, in particular, can be stabilized after the repair process. This can be particularly advantageous since an edge section can be considered particularly sensitive to the progression of the repair process. Thus, undesirable progression of the repair process along the edge of the repair area can be prevented.

[0028] The repair area may be at least partially delimited from a non-repaired area by an edge and / or a peripheral border.

[0029] The repair area can be sharply demarcated from a non-repaired area (where no scanning by a particle beam took place) by scanning the particle beam over the repair area. In such a case, a defined edge can result between the repair area and the non-repaired area. Such an edge can be formed, for example, by an absorbing and / or phase-shifting pattern element of the mask.

[0030] The passivation region may at least partially comprise the edge and / or the peripheral rim.

[0031] This allows, in particular, the progression of the repair process beyond the edge and / or the peripheral edge (e.g., into a non-repaired area) to be achieved through targeted stabilization of the edge and / or the peripheral edge. The edge and / or the peripheral edge can be completely contained within the passivation area.

[0032] The passivation region may have at least one section extending beyond the edge and / or the peripheral edge with a width between 2 and 150 nm. The section may, for example, extend completely along the edge and / or completely along the peripheral edge.

[0033] In this way, the passivation region can reliably protect the edge and / or the surrounding perimeter. In some cases, a greater extension of the passivation region beyond the edge and / or the surrounding perimeter can achieve increased stabilization of the area surrounding the repair area, for example, by prophylactically protecting a larger section of the non-repaired area through passivation to prevent undesired progression of the repair process beyond the repair area.

[0034] The passivation region may have at least one section extending beyond the edge and / or the peripheral edge with a width of 2 to 150 nm.

[0035] Similar to the aspects described above, this can contribute to a particularly permanent passivation of the repair area. The edge and / or the surrounding border, which are particularly vulnerable, can thus be comprehensively protected.

[0036] The method may further be configured such that no passivation occurs in at least a portion of the repair area.

[0037] The at least one non-passivated portion may, for example, comprise a center point of the repair area. It may, for example, comprise substantially the entire repair area except for a portion extending along an edge of the repair area, as described herein.

[0038] This allows the passivation process to be concentrated on the edge and / or peripheral area, which tend to be more critical for the progress of the repair process. This can contribute to a faster and more cost-effective passivation process and support a more efficient repair of a lithographic mask overall.

[0039] The passivation gas may have a first component comprising Si and / or O.

[0040] Due to the presence of Si and O, SiO2 can form in the passivation area in some preferred cases, thus preventing any subsequent exposure to a process gas.

[0041] The first component of the passivation gas may comprise a tetraethoxysilane, TEOS.

[0042] This can support particularly effective passivation.

[0043] The passivation gas may comprise a second component comprising N and / or O, preferably NO2.

[0044] This can contribute to increased stability of the passivated area. It has been found that this can reduce the carbon content of a passivation layer containing Si and O, which can be formed, for example, by deposition with TEOS. This can occur, for example, through an oxidizing effect of the NO2. This can, for example, support increased stability of the passivation area, e.g., against a process gas during the repair process (repair gas), against a reactive species during the manufacturing process of the lithographic mask and / or during cleaning of the lithographic mask. Furthermore, the presence of the second component can help to reduce the amount of material required for passivation. This can contribute to more efficient and cost-effective passivation.Furthermore, the reduced amount of material can contribute to a reduction in the effects of passivation on the optical properties of the mask. This can prevent any undesirable influence on the optical properties of the mask caused by passivation (e.g., an undesirable increase in the absorption properties of the mask).

[0045] The defect can comprise a defect with excess material of an absorbing and / or phase-shifting material. For example, the defect can be caused by a dirt particle. However, it is also possible that, for example, a pattern element is arranged beyond its intended geometry. The defect material and / or the material of the pattern element can comprise, for example, Ta, preferably TaN. The defect can be an opaque defect.

[0046] Through the repair, the lithographic mask can be brought into the range of specifications required for function in an environment of the repair area.

[0047] A repair process, preferably provided as an etching process (e.g., in the case of an opaque defect), can enable the excess material on the lithographic mask to be removed in a targeted and defined manner. This can eliminate the undesirable absorption properties and / or phase-shifting properties associated with the excess material.

[0048] In the presence of the particle beam and the passivation gas, a passivation layer can be deposited in the passivation region, which preferably contains Si and / or O.

[0049] By depositing a passivation layer in the passivation area, physical coverage of the passivation area can be achieved. This can enable (complete) physical coverage of the passivation area from a volume in which repair gases may be present, which could lead to undesired etching upon interaction with a material in the repair area and / or the non-repaired area.

[0050] The deposited layer can be a Si x O y C z -layer.

[0051] This can enable particularly effective and preferential passivation of the passivation region. Preferably, z < x and / or z < y, so that the composition is as close as possible to SiO2.

[0052] The passivation layer can be designed in such a way that the deposition of the passivation layer does not significantly affect the specification of the mask.

[0053] In particular, the passivation layer can be formed in such a way that it does not significantly influence the optical properties of the lithographic mask in the passivation region with regard to its absorbing and / or phase-shifting properties compared to a region of the lithographic mask not covered by the passivation.

[0054] A non-significant impact on the mask's specifications occurs when the deviation caused by the passivation layer is so small that the mask still meets the specifications afterward. However, it is also conceivable that the (anticipated) changes caused by the passivation are already taken into account during the repair, so that, at least overall, the mask remains within specifications after repair and passivation.

[0055] A thickness of the passivation layer may be in a range of 100 pm to 35 nm, preferably in a range of 1 nm to 30 nm or 2 nm to 20 nm, and particularly preferably in a range of 2 nm to 10 nm.

[0056] The thickness of the passivation layer may be essentially constant across the passivation region. Alternatively, the thickness of the passivation layer may vary across the passivation region, with the average thickness of the passivation layer being within the above-mentioned range.

[0057] The deposited passivation layer may have a complex refractive index with a smaller real and / or imaginary part than a real and / or imaginary part of a complex refractive index of a material of a pattern element of the mask.

[0058] The real and / or imaginary part of the complex refractive index of the passivation layer can, for example, be smaller by a factor of 1.5 to 10 than a real and / or imaginary part of the complex refractive index of the material of the pattern element of the mask.

[0059] This can help ensure that the presence of the passivation layer does not significantly affect the absorption properties and / or the phase-shifting properties of the lithographic mask.

[0060] The pattern element can be, for example, a “lines-and-spaces” pattern.

[0061] The deposited passivation layer may be provided such that it is not significantly affected by at least five, preferably at least ten further repair cycles on the lithographic mask (with respect to defects located elsewhere on the mask).

[0062] In this way, it can be ensured that an undesired influence on the passivation area can be suppressed by a certain number of further repair cycles on the mask (e.g. by crosstalk of the further repair cycles on the passivation area).

[0063] The functions described above may be implemented in hardware, software executed by a processor (e.g., as a computer program), firmware, or any combination thereof. When implemented in software executed by a processor, the functions may be stored on or transmitted over a computer-readable medium as one or more instructions or code. For example, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations thereof. Features that implement functions may also be physically arranged in different locations, including being distributed such that portions of the functions are implemented in different physical locations.

[0064] According to a further embodiment, an apparatus for passivating a repair region of a lithographic mask may comprise: a) means for supplying a passivation gas and b) means for directing a particle beam onto a passivation region, wherein the passivation region has at least one portion lying outside the repair region.

[0065] According to a further embodiment, an apparatus for repairing a lithographic mask may comprise: a) means for particle beam-based repair of a defect in a repair region of the mask in the presence of a repair gas and b) means for downstream passivation of the repair region in a passivation region and in the presence of a passivation gas, wherein the passivation is preferably carried out particle beam-based.

[0066] The apparatus may further comprise means for automatically performing the downstream passivation after completion of the particle beam-based repair.

[0067] Thus, immediate passivation of at least part of a repair area after the repair process can be advantageously ensured, thus suppressing any undesirable progression of the repair process due to the presence of the repair gas. This can contribute to more targeted control of the repair process.

[0068] The above devices may further comprise means for determining the passivation region based on an extent of the repair region.

[0069] The means may comprise algorithms configured to (automatically) determine an optimal geometry of the passivation region based on knowledge of the repair region. For example, a passivation region described herein may be automatically defined that completely covers the repair region and / or runs completely along an edge or a peripheral margin of the repair region.

[0070] Additionally or alternatively, the means may comprise a (graphical) user interface (GUI) that may enable a user of the device to define a region to be passivated on the lithographic mask by interacting with the graphical user interface. This may, for example, enable selection between the alternatives "complete coverage" or "only edge area" of the repair area. Additionally or alternatively, the GUI may also be used to specify a width of an edge located outside and / or inside the repair area (possibly along an edge and / or running around the repair area).

[0071] The devices may further comprise means for (automatically) carrying out the method according to any one of the preceding claims.

[0072] The devices may further comprise the above-mentioned computer program.

[0073] Another aspect of the present invention relates to a method for repairing and / or inspecting a lithographic mask. The method may include particle beam-based passivation of a reference mark.

[0074] This can advantageously contribute to ensuring a more stable reference mark during the repair. For example, a reference mark can be generated on the mask (or more generally: sample), e.g., using a particle beam. The reference mark can then be passivated. This aspect can also be combined with the further aspects of the invention described herein. The passivation region can be configured analogously to the region in which the reference mark is arranged, as described herein with respect to a repair region.

[0075] Although the invention is explained primarily with reference to lithographic masks, the various aspects of the invention are also applicable to other objects, e.g. substrates, wafers, mask blanks, etc. or in general: samples. 4. Description of the drawings

[0076] In the following detailed description, currently preferred embodiments of the invention are described with reference to the drawings, wherein Fig. 1A-1D: show an illustration of the process steps of a repair process according to the invention and a passivation process on a lithographic mask in a sectional view; Fig. 2A-2D: show an exemplary illustration of a passivation in a lines-and-spaces pattern of a lithographic mask in a top view; Fig. 3A-3C: show a scanning electron microscope (SEM) image of an exemplary repair region of a lithographic mask and exemplary (geometric) configurations of a passivation region; Fig. 4A-4B: shows a comparison of the effects of the width of a passivation region on its stability; Fig. 5A-5B: show exemplary SEM images of a non-passivated repair area; Fig. 6: exemplary SEM images with passivated repair areas; Fig. 7A-7B: show an SEM image of a lines-and-spaces pattern of a lithographic mask in the presence and absence of a passivation layer, respectively; Fig. 8A-8B: exemplary SEM images of a partially repaired defect to illustrate a passivation process. 5. Detailed description of preferred embodiments

[0077] Currently preferred embodiments of devices according to the invention and of a method according to the invention for passivating a region of a lithographic mask are explained in more detail below. However, the use of the devices according to the invention and the method according to the invention is not limited to the examples discussed below. Rather, they can be used generally for passivating a lithographic mask.

[0078] Fig. 1A-1D show exemplary process steps of a repair and a passivation process on a lithographic mask 110. The mask 110 can be, for example, an EUV mask.

[0079] Fig. 1A shows an exemplary repair process on the mask 110. By way of example, a plurality of absorbing and / or phase-shifting elements 120 are applied to the top side of the mask 110 (in one example, these may be parallel lines of a so-called "lines-and-spaces" structure). The absorbing and / or phase-shifting elements 120 may preferably comprise a layer made of a material comprising Ta, preferably TaN. This layer may form the majority of the elements 120, e.g., have a thickness greater than 50% of the thickness of the elements 120.

[0080] The elements 120 can be arranged, for example, on a cover layer of the mask 110, which can comprise ruthenium, for example. A Mo-Si stack can be arranged beneath the cover layer, which can be located on a substrate of the mask 110.

[0081] At the selected absorbing or phase-shifting element 130 (in Fig. 1A (far left) a repair process is carried out as an example to remove the absorbing or phase-shifting element 130 in the repair area 140 (in other examples, only the height can be reduced).

[0082] For this purpose, a particle beam 150 is directed onto the repair area 140 of the absorbing and / or phase-shifting element 130. Typically, the particle beam 150 is focused so that it can be applied locally, e.g., with a diameter of < 1 nm. The particle beam 150 can comprise, for example, electrons. The electrons can be accelerated, e.g., with an acceleration voltage of 0.01 kV to 30 kV. Typical currents of the particle beam (e.g., an electron beam) can be, for example, in the range of 0 to 300 nA, 3 pA to 20 nA, 10 pA to 300 nA, or 1 pA to 150 pA.

[0083] The particle beam 150 is preferably directed during and / or after the supply of a repair gas 160. In a preferred embodiment of the invention, the repair gas 160 may contain, for example, Xe and / or F, preferably XeF2. In some exemplary cases, the repair gas 160 may further contain H2O to slow down and thus achieve better control over the repair process, which may contribute to a more homogeneous etching process (compared to a repair without H2O). Additionally or alternatively, it is possible for the repair gas to contain NO2, e.g., in addition to XeF2 and H2O.

[0084] The interaction of the particle beam 150 and the repair gas 160 can lead to a particle beam-induced etching of the absorbing and / or phase-shifting element 130 in the repair region 140, thereby reducing the thickness of the absorbing and / or phase-shifting element 130. This can controllably reduce the absorbing and / or phase-shifting properties of the treated absorbing and / or phase-shifting element 130 in the repair region 140.

[0085] Fig. 1B shows the repair area 140 on the absorbing and / or phase-shifting element 130 after completion of the repair process.

[0086] Through an interaction between particle beam 150 and the supplied repair gas 160 (containing, among other things, H2O), a passivation layer can be deposited in the repair area 140. The passivation layer can comprise Ta2O5.

[0087] Although a passivation layer 170 can, in principle, form in the repair area 140, in some cases this is only partially achieved and not to a satisfactory extent. Problems can arise here, particularly with tantalum-containing elements 120 / 130, especially when they are arranged on a ruthenium-containing cover layer.

[0088] It was recognized that in some cases, instead of a closed Ta2O5-containing layer, a layer may form which contains defect areas, which may result in the material of the lithographic mask present in the repair area 140 not being completely covered by the passivation layer 170.

[0089] In some cases, the defect sites can TaO x F y This can lead to the release of reactive F-containing species, which in turn can promote undesirable progression of the repair process.

[0090] Since the repair region 140 in the present case is merely an insufficiently passivated region, the presence of residues of the repair gas 160 can lead to further etching in a non-repaired region of the absorbing and / or phase-shifting element 130. This can include, on the one hand, etching a portion of the absorbing and / or phase-shifting element 130 that was not previously part of the repair process (or onto which the particle beam 150 has not yet been directed), or can include further etching of the repair region 140 already processed with the particle beam 150, so that a further (undesired) reduction in the thickness of the absorbing and / or phase-shifting element 130 can occur in the region of the repair region 140, or the etching process can progress into a non-repaired region.

[0091] Even targeted re-passivation by redirecting the particle beam 150 and re-supplying the repair gas 160 (e.g., containing H2O) usually does not lead to sufficient passivation. This is attributed to the fact that the supply of, for example, H2O, especially when the defect areas contain TaO x F y species, can lead to the formation of reactive species, which can promote undesirable progression of the repair process in repair area 140 (or beyond).

[0092] Additionally or alternatively, it may be possible that XeF2 gas remained in the atmosphere in which the above-described repair process was carried out, which can be used, for example, as repair gas 160. This can lead to the remaining repair gas, due to its reactive properties, contributing to further progress of the repair process in the repair area 140 (e.g., in the area of ​​the defects) and / or a previously unrepaired area. Additionally or alternatively, it can contribute to the formation of reactive HF through interaction with H2O.

[0093] In order to Fig. 1B described problem, shows Fig. 1C illustrates a passivation process according to one aspect of the present invention.

[0094] Fig. 1C shows directing the particle beam 150 onto at least a portion of the repair region 140, i.e., a passivation region 145.

[0095] Additionally, a passivation gas 180 is added to the process. The passivation gas may be identical to the repair gas in at least one of its constituents. Alternatively, the passivation gas may be completely different from the repair gas.

[0096] Fig. 1D shows an example of a deposited passivation layer 190, which is deposited by the interaction of the particle beam 150 and the passivation gas 180 and which completely covers the passivation region 145. The passivation layer 190 preferably has a portion both in the repair region 140 and outside the repair region 140. In addition, an edge of the element 130 can be completely covered by the passivation layer 190. Thus, the portion of the passivation region in the repair region (in Fig. 1 running horizontally on the top layer of the mask) with the section outside the repair area (in Fig. 1 horizontally on the element 130) be connected by a (in Fig. 1 vertical) section of the passivation layer 190.

[0097] As already described above, the passivation gas 180 may contain NO2. This can contribute to a reduction in the carbon content of the deposited material and thus lead to a reduction in the thickness of the deposited passivation layer (compared to the thickness of the passivation layer achieved in the absence of a NO2-containing passivation gas 180 with a similar stabilizing effect).

[0098] Empirically, it has been determined that at least approximately 25 passivation passes are required to achieve detectable stabilization. In this context, a passivation pass is defined as a single scanning of a passivation area with a particle beam in the presence of a passivation gas to deposit a passivation layer in the passivation area. The passivation pass can be repeated to enhance the effects induced by the passivation process. Additional repair processes can be performed between passivation passes.

[0099] Preferred results were achieved after approximately 200 passivation passes. Increasing the number of passivation passes from, for example, 200 to 500 could further increase stability slightly, while further increasing the number of passivation passes from, for example, 500 to 1000 did not result in any significant improvement in stabilization.

[0100] The thickness of the deposited passivation layer can be determined, for example, using atomic force microscopy (AFM) images and is approximately 1.5 nm to 3.5 nm for 200 passivation cycles, while it is approximately 5.5-6.5 nm for 500 passivation cycles.

[0101] Furthermore, based on the passivation passes performed and subsequent thickness measurements of the deposited passivation layer, the relationship between the number of passivation passes and the deposited passivation layer thickness was determined. It was found that the thickness of the passivation layer is typically proportional to the number of passivation passes performed. Experimentally, it was determined that with ten passivation passes, a passivation layer with a thickness of approximately 75 to 150 pm can be deposited.

[0102] Example thicknesses of the passivation layer are therefore 100 pm to 30 nm, preferably 150 pm to 15 nm or 200 pm to 5 nm.

[0103] Fig. 2A-2D show an exemplary passivation pass on a lines-and-spaces pattern of a lithographic mask in a plan view according to one aspect of the present invention. The figures described with reference to Fig. 2A-2D (e.g. absorbing and / or phase-shifting elements 220 / 240, repair area 240, etc.) correspond to the respective corresponding elements which are related to Fig. 1A-1D have already been described above.

[0104] Fig. 2A shows an edge of a repaired absorbing and / or phase-shifting element 230 of a lithographic mask arranged next to non-repaired (and not in need of repair) absorbing and / or phase-shifting elements 220.

[0105] Fig. Figure 2B shows the situation after the repair process.

[0106] Fig. 2C shows an exemplary application of a passivation layer 290 to the repair area 240 with a portion that does not extend into the repair area 240. The passivation area may extend beyond the repair area in at least two dimensions. In the example of Fig. 2, the passivation area extends both horizontally (perpendicular to the course of the “lines”) and vertically beyond the repair area.

[0107] Fig. 2D shows the exemplary (long-term) effects of applying the passivation layer 290 to the absorbing and / or phase-shifting element 230. As in Fig. As shown in Figure 2D, the application of the passivation layer 290 leads to a stabilization of the absorbing and / or phase-shifting element 230, in particular in the region of the repair region 240. In this way, a stabilization of the repair region 240 can be achieved and an undesired and / or uncontrolled progression of the repair process can be suppressed.

[0108] By applying the passivation layer 290 in the repair area 240, a resistance of the repair area 240 against an (undesired) progression of the etching process can thus be achieved, as can also be achieved in non-repaired areas of a lithographic mask.

[0109] Fig. 3A-3C show possible configurations of a passivation region around a repair region in the presence of a regular arrangement (in plan view) of so-called “contact holes” (CH) arranged on a lithographic mask.

[0110] CHs are holes in the substrate of a lithographic mask, which can be obtained, for example, by an etching process, and extend over one or more layers of a lithographic mask and can serve to connect one or more layers of a lithographic mask to each other.

[0111] Fig. Figure 3A shows an SEM image of a lithographic mask 300, which has a regular pattern of CHs 310. For testing purposes, the material in the repair area 320 is to be completely removed. Subsequently, passivation is to take place.

[0112] As part of the passivation process, it is possible to Fig. 3A, the passivation region 330 is provided only to provide an edge created by the removal of material. The pre-existing edges of the CHs 310 arranged on the outer sides of the repair region 320, as well as the connecting lines between these CHs 310 themselves, are not to be passivated.

[0113] According to this embodiment, surface passivation of the repair area 320 does not occur.

[0114] This enables a quick and cost-effective passivation of an outer region of the repair area 320, which can tend to be considered to be the most sensitive to the progress of a repair process.

[0115] In this example, the repair region 330 is partially linear, wherein the lines run centrally along the edges generated by the removal process and can have a variable width (e.g., ± 2 nm to ± 150 nm, e.g., ± 4 nm to ± 100 nm or ± 8 nm to ± 80 nm, in each case viewed substantially from the edge).

[0116] Fig. 3B shows another SEM image of an exemplary repair area 320 formed as described with reference to Fig. 3A can be designed.

[0117] According to Fig. 3B, the passivation region 320 is not only arranged in sections in a linear manner along the edges created by the material removal. It is also arranged in a linear manner around the already existing edges of the CHs 310 located in the edge region of the repair region 320. As a result, a passivation region is created in the form of a crenellated line encircling the repair region (which can have widths as with reference to Fig. 3A).

[0118] This can be done analogously to the explanations for Fig. 3A contribute to a rapid and cost-effective, and thus efficient, stabilization of at least a portion of a repair region 320 and at least a portion of a non-repaired region of the lithographic mask 300. Furthermore, the non-repaired edges of the CHs 310 can also be passivated to reduce the risk that they may be attacked in processes downstream of the actual repair, as described herein. A surface passivation of the repair region 320 does not occur according to this embodiment.

[0119] Fig. Figure 3C shows another SEM image of a lithographic mask 300 (top view) with a regular pattern of CHs 310 and another possible passivation geometry.

[0120] According to Fig. 3C, it is possible to select the passivation geometry such that the repair region 320 is completely covered by the passivation region 330. Furthermore, the passivation region 330 also has an additional peripheral edge, so that the CHs 310 at the edge of the repair region 320 are also completely covered. The edge can also extend slightly beyond the edges of the CHs 310.

[0121] This can contribute to a particularly stable passivation of the repair area 320.

[0122] Fig. 4A and Fig. 4B show a comparison of the effects of the width of the passivation region along a peripheral edge of a repair region (as discussed herein) for two possible characteristics of ± 4 nm ( Fig. 4A) and ± 10 nm ( Fig. 4B) on the stability of the passivation obtained.

[0123] Fig. 4A (left) shows an SEM image (analogous to the SEM images of the Fig. 3A-3C) of a mask 400, wherein an etching was carried out for test purposes in a repair area 410 (including CHs 420, such as CHs 310) of the mask 400.

[0124] The performed etching process resulted in the formation of edges 430 which separate the repair area 410 from a non-repaired area of ​​the mask 400.

[0125] Furthermore, the repair area 410 was in accordance with the statements on Fig. 3A with a passivation layer, wherein the passivation layer was deposited with a width of ± 4 nm around the edge 430.

[0126] Fig. 4A (right) shows the repair area 410 provided with a passivation layer (as previously described) after 22 further exemplary repair cycles have been performed on the mask 400.

[0127] Fig. 4A (right) shows opposite Fig. 4A (left) shows a clearly visible degradation of the mask 400, which is visible, among other things, in the area of ​​the edge 430. Furthermore, the repair area 410 in Fig. 4A (right) shows a marble-like pattern, which is also due to degradation of the mask at the location of the repair area 410.

[0128] In contrast, Fig. 4B (left) also shows an SEM image of a mask 400, in analogy to the SEM images of the Fig. 4A, on which an etching was also carried out in a repair area 410.

[0129] In contrast to the statements on Fig. 4A, was designed for the Fig. 4B, a passivation layer with a width of ± 10 nm is applied around the edge 430 onto the mask 400.

[0130] Fig. 4B (right), however, shows the repair area 420 provided with a passivation layer after 22 further repair cycles have been carried out on the mask 400.

[0131] In direct comparison between Fig. 4A (right) and Fig. 4B (right) it can be seen that a wider passivation layer (ie ± 10 nm ( Fig. 4A) instead of ± 4 nm ( Fig. 4B)) leads to improved stability of the repair region 410 or the edge 430 and the passivation region applied around it.

[0132] A systematic characterization of the stability of a deposited passivation layer as a function of the selected width was able to show that a greater width generally (within certain limits) leads to a more long-term stable passivation layer, ie the passivation layer can withstand the effects of any repair gas still present for a longer time or a higher number of repair cycles carried out at another location on the mask (without significant degradation).

[0133] However, it was also shown that in some examples, a passivation range wider than ± 10 nm does not lead to any significant further improvement. Even a surface passivation (as in relation to Fig. 6) does not lead to significantly better results in some examples. Good results could also be achieved with a passivation region of ± 7 nm. However, it was also shown that a passivation region with a width of less than ± 4 nm usually leads to significant degradation of the mask in the repair area 410 and at the edge 430.

[0134] Example widths of the repair area are therefore at least ± 4 nm, with ± 40 nm being a possible practical upper limit to minimize the duration of the passivation process. In some cases, the widths can range from ± 5 nm to ± 20 nm.

[0135] For example, a width of the passivation region along an edge of a repair region can be selected such that the passivation region can withstand at least 5, 10, 15 or at least 20 subsequent etches on the same sample, wherein the etches are particle beam-based etches of, for example, one repair region each on the same sample with an area of ​​0.25 µm 2 in which material with a thickness in the range of 10 nm to 150 nm is removed.

[0136] For example, a thickness of a passivation region can be selected such that the passivation region can withstand at least 5, 10, 15 or at least 20 subsequent etchings on the same sample, wherein the etchings are particle beam-based etchings of, for example, one repair region each on the same sample with an area of ​​0.1 µm 2 up to 1 µm 2 , e.g. 0.25 µm 2, in which material with a thickness in the range of 10 nm to 150 nm, e.g. 100 nm, is removed.

[0137] Fig. 5A and Fig. 5B show contrasting SEM images of a lithographic mask immediately after ( Fig. 5A) and one day ( Fig. 5B) after an exemplary etching process, which was used to create openings 510 and 520 in a lithographic mask at two locations by material removal in order to characterize the passivation process described herein.

[0138] Fig. Figure 5A shows openings 510 and 520 (immediately) after completion of the electron beam-based removal and etching processes. The etch depth extended to an etch stop layer (formed by a Ru cap layer in this example).

[0139] Fig. 5B shows the openings 510 and 520 as related to Fig. 5A, but on a day following the day of repair.

[0140] As from Fig. 5B, the openings 510 and 520 show a degradation of the external appearance, which results from the missing passivation layer on these openings 510 and 520.

[0141] Fig. Figure 6 shows various openings 610-630 created in a mask by electron beam etching. In the present example, this was done by etching a tantalum-containing layer down to an etch stop layer (formed in the present example by a ruthenium-containing cap layer).

[0142] After etching, however, in contrast to the Fig. 5A and Fig. 5B, one passivation step was performed each time. Openings 610-630 were passivated using an electron beam and TEOS gas and NO2 as an additional gas with a different number of passes.

[0143] The images of apertures 610-630 were also taken after one day. No noticeable degradation of the apertures is visible.

[0144] The openings were passivated for different lengths of time. Opening 610 was passivated with 200 passivation passes. Opening 620 was passivated with 500 passivation passes. Opening 630 was passivated with 1000 passivation passes.

[0145] The openings 610-630 thus created have exemplary dimensions of 400 nm x 400 nm and form the repair region. Each opening 610-630 is surrounded by an edge 640, which delimits the repair region from a non-repaired region. Each edge 640 is surrounded (symmetrically) by a passivation region 650. The exemplary dimensions of the passivation region are 600 nm x 600 nm, resulting in a width of the passivation region along the edges 640 of at least approximately ±100 nm. In some examples, the passivation region within the repair region is configured differently and completely covers the latter.

[0146] Following the openings 610-630, it can be seen that an increasing number of passivation cycles leads to an increase in the thickness of the passivation layer 650. This is reflected in the increasing darkening of the passivation region 650.

[0147] The use of TEOS can advantageously promote passivation of the environment of a repair area, for example, by inactivating chemisorbed F, HF and / or XeF2 through a chemical reaction with TEOS molecules or species formed from TEOS by electron beam induced irradiation, and / or by displacing fluorine compounds through physisorption and / or chemisorption of TEOS molecules. Furthermore, the use of TEOS can inactivate at least one TaO x F y species, which could otherwise act as a source of reactive fluorine compounds and contribute to the release of reactive HF.

[0148] In some examples, the amount of e.g. Si deposited by passivation at the repaired area can x O y C zlocally change the optical properties of the lithographic mask. The change in the optical properties can be proportional to the thickness and area of ​​the deposited passivation layer and can depend on the complex refractive index of the materials used to deposit the passivation layer. In particular, the absorption for EUV light can be changed. Furthermore, the deposited passivation layer can change the phase-shifting properties of the mask. The thickness of the deposited layer can therefore be selected so that the optical properties of the repaired area (absorption, phase shift) do not change beyond a predefined limit.

[0149] If the amount of deposited material required for passivation exceeds a limit, it may be necessary to include the effect of the deposited material and thus the thickness of the passivation layer in the planning of the passivation process. For example, a repair process prior to passivation can deliberately remove more material than is necessary for the reconstruction of the area in question in order to bring the lithographic mask into specification. This area additionally exposed by the particle beam can, for example, be specified in the form of a bias in pixels and comprise an "artificial" extension of the repair process to a material section of the lithographic mask which, due to its properties, does not need to be part of the repair process. The material deposited for passivation thus contributes to the reconstruction of the edge.The desired optical properties of the repair area then result from the combination of the optical properties of the repair area and the optical properties of the deposited passivation layer.

[0150] Fig. 7A and Fig. 7B shows an exemplary SEM image of a “lines-and-spaces” pattern of a lithographic mask in top view.

[0151] Fig. 7A shows a "lines-and-spaces" pattern in which two "lines" 710 were connected by excess material. This section 720 was subjected to a repair process, whereby this excess material was removed using a particle beam method. Subsequently, the repaired section 720 was passivated according to an inventive method as described herein.

[0152] Fig. Figure 7B shows an analogously repaired “lines-and-spaces” pattern with a repair area 720, which was not subsequently passivated. Compared to Fig. 7A shows that after several additional repair cycles, which were performed, for example, in an environment of the repair area 720, the repair site was subject to degradation caused by an undesirable progression of the repair process. This can lead to a deviation from a desired repair result.

[0153] Fig. 8A and Fig. 8B show exemplary SEM images of an exemplary “lines-and-spaces” pattern in top view.

[0154] Fig. Figure 8A shows a partial repair of a defect 820 that connected three of the lines 810, namely lines 811, 812, and 813. The defect 820 was removed between lines 812 and 813 by a repair process.

[0155] To protect the repair area from undesired progress of the repair process, one edge of the repair area was subjected to a passivation process according to the invention, whereby the passivation area was applied linearly around the repair area with a width of ± 5 nm, with 200 passivation passes. As can be seen from Fig. 8A, after completion of the passivation process, there was no further significant progress in the repair area and no other significant degradation occurred.

[0156] In contrast, Fig. 8B shows a similar defect 820 that was repaired in a similar manner, but with only 100 passivation passes. As in Fig. 8B, a significant degradation of the “lines-and-spaces” pattern was observed after the repair (e.g. compared to Fig.8A). This is attributed to the fact that passivation was not carried out sufficiently.

[0157] It can thus be seen that, for example, a linear passivation area width of ± 5 nm and 100 passivation passes did not yet result in satisfactory resistance of the repair area. However, if the number of passivation passes is increased to 200, a clearly discernible resistance of the repair area is already evident.

[0158] In some examples, the mask (or sample more generally) is not necessarily processed. For example, it may simply be examined. For both examination and processing (e.g., deposition and / or etching), both of which can be particle beam-based, it may be necessary to use fiducial markings on the sample. These can be used, for example, for orientation and / or drift control. However, once the particle beam hits the fiducial markings, they can be worn away. Therefore, it may be useful to passivate fiducial markings present on the sample and / or fiducial markings deposited or etched thereon, as described herein with respect to a repair area. This allows the fiducial markings to be used more permanently and to be protected from harmful and unwanted etching processes that may be performed on the mask, as well as other negative influences.

[0159] The following is a brief (not exhaustive) overview of possible passivation gases and possible additional gases.

[0160] Possible passivation gases include (but are not limited to) (metal, transition element, or main group) alkyls such as cyclopentadienyl (Cp)- or methylcyclopentadienyl (MeCp)-trimethylplatinum (CpPtMe3 or MeCpPtMe3), tetramethyltin SnMe4, trimethylgallium GaMe3, ferrocene Cp2Fe, bis-aryl-chromium Ar2Cr, and other such compounds. Also suitable are (metal, transition element, or main group) carbonyls such as chromium hexacarbonyl Cr(CO)6, molybdenum hexacarbonyl Mo(CO)6, tungsten hexacarbonyl W(CO)6, dicobalt octacarbonyl Co2(CO)s, and triruthenium dodecacarbonyl Ru3(CO). 12, ruthenocene Cp2Ru, iron pentacarbonyl Fe(CO)5, and other similar compounds can be used. Additionally or alternatively, (metal, transition element, main group) alkoxides such as tetraethoxysilane Si(OC2H5), tetraisopropoxytitanium Ti(OC3H7)4, and other similar compounds can be used. Furthermore, (metal, transition element, main group) halides such as WF6, WCl6, TiCl6, BCl3, SiCl4, and other similar compounds can be used. It is also possible to use (metal, transition element, main group) complexes such as copper bishexafluoroacetylacetonate Cu(C5F6HO2)2, dimethylgold trifluoroacetylacetonate Me2Au(C5F3H4O2), and other similar compounds. Additionally or alternatively, organic compounds such as CO, CO2, aliphatic or aromatic hydrocarbons, components of vacuum pump oil, volatile organic compounds and other such compounds can also be used.

[0161] Gases that can be added to the passivation gas include, for example, oxidizing agents such as, but not limited to, O2, O3, H2O, H2O2, N2O, NO, NO2, HNO3, and other oxygen-containing gases. Additionally or alternatively, the gases that can be added can also contain halides such as Cl2, HCl, XeF2, HF, I2, HI, Br2, HBr, NOCl, PCl3, PCl5, PF3, and other halogen-containing gases. Additionally or alternatively, the gases that can be added can also contain gases with a reducing effect such as H2, NH3, CH4, and other hydrogen-containing gases. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2020 120 884 A1

[0004]

Claims

[1] A method for passivating a repair area (140) of a lithographic mask (110), comprising: a) supplying a passivating gas (180); b) directing a particle beam (150) onto a passivation region (145) of the mask, wherein the passivation region (145) has at least a portion that lies outside the repair region (140). [2] The method of claim 1, further comprising: Supplying a repair gas (160) before supplying the passivation gas (180) and directing the particle beam (160) onto the repair region (140) in the presence of the repair gas (160) to repair a defect arranged in the repair region (140). [3] The method of claim 1 or 2, wherein the passivation region (145) further comprises at least a portion located in the repair region (140). [4] A method for repairing a lithographic mask (110), comprising: a) particle beam-based repair of a defect in a repair region (140) of the mask (110) in the presence of a repair gas (160); b) Subsequent passivation of the repair region (140) in a passivation region (145) in the presence of a passivation gas (180), wherein the passivation is preferably carried out particle beam-based. [5] Method according to one of the preceding claims, wherein the passivation region (145) completely covers the repair region (140). [6] Method according to one of the preceding claims, wherein the passivation region (145) has a larger surface area than the repair region (140). [7] Method according to one of the preceding claims, wherein the passivation region (145) extends at least partially along an edge portion of the repair region (140). [8] Method according to one of the preceding claims, wherein the repair area (140) is at least partially delimited from a non-repaired area by an edge and / or a peripheral edge. [9] The method according to claim 8, wherein the passivation region (145) at least partially comprises the edge and / or the peripheral edge. [10] Method according to one of claims 8 or 9, wherein the passivation region (145) has at least one section extending beyond the edge and / or the peripheral edge with a width between 2 and 150 nm. [11] Method according to one of the preceding claims, wherein the passivation region (145) has at least one section extending over the edge and / or the peripheral edge with a width of 2 and 150 nm. [12] Method according to one of the preceding claims, wherein no passivation takes place on at least a portion of the repair area (140). [13] Method according to one of the preceding claims, wherein the passivation gas (180) has a first component which includes Si and / or O. [14] The method of claim 13, wherein the first component comprises a tetraethoxysilane, TEOS. [15] Method according to one of claims 13 or 14, wherein the passivation gas (180) comprises a second component comprising N and / or O, preferably NO2. [16] A method according to any one of claims 2, 4, or 3, 5-15, when dependent on any one of claims 2 or 4, wherein the defect comprises a defect with excess material of an absorbing and / or phase-shifting material. [17] Method according to one of claims 2, 4, or 3, 5-16, dependent on one of claims 2 or 4, wherein the repair brings the mask (110) into specification in an environment of the repair area. [18] Method according to one of the preceding claims, wherein in the presence of the particle beam (150) and the passivation gas, a passivation layer (190) is deposited in the passivation region (145), which preferably contains Si and / or O. [19] The method of claim 18, wherein the deposited layer (190) comprises a Si x O y C z -layer. [20] Method according to one of claims 18 or 19, wherein the specification of the mask is not significantly influenced by the deposition of the passivation layer (190). [21] The method according to any one of claims 18-20, wherein a thickness of the passivation layer (190) is in a range of 1 to 15 nm. [22] Method according to one of claims 18-21, wherein the deposited passivation layer (190) has a complex refractive index with a smaller real and / or imaginary part than a real and / or imaginary part of a complex refractive index of a material of a pattern element of the mask (110). [23] Method according to one of claims 18-22, wherein the deposited passivation layer (190) is not significantly affected by at least five, preferably at least ten further repair cycles on the mask (110). [24] A computer program comprising code which, when executed, performs the method of any one of claims 1-23. [25] Apparatus for passivating a repair area of ​​a lithographic mask (110), comprising: a) means for supplying a passivating gas (180); b) means for directing a particle beam (150) onto a passivation region (145), wherein the passivation region (145) has at least one portion which lies outside the repair region (140). [26] The apparatus of claim 25, further comprising: Means for automatically carrying out the method according to any one of claims 1, 2 or 4-23. [27] Apparatus for repairing a lithographic mask (110), comprising: a) means for particle beam-based repair of a defect in a repair region (140) of the mask in the presence of a repair gas (160); b) means for downstream passivation of the repair region (160) in a passivation region (145) and in the presence of a passivation gas (180), wherein the passivation is preferably carried out particle beam-based. [28] The apparatus of claim 27, further comprising: Means for automatically performing the downstream passivation after completion of the particle beam-based repair. [29] Apparatus according to any one of claims 27 or 28, further comprising: Means for automatically executing the method according to any one of claims 3-23. [30] Device according to any one of claims 25-29, further comprising: Means for determining the passivation area (145) based on an extent of the repair area (140). [31] Apparatus according to any one of claims 25-30, further comprising the computer program according to claim 24.

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