System and method for generating comparable regions of a lithographic mask

Abstract

To provide a method for generating an in-die reference for a die-to-die defect detection technique.SOLUTION: An inspection method using an in-die reference includes finding of a similar block of a lithography mask, where the similar block is defined by similar CAD information. On the basis of (i) an area of the similar block and (ii) a spatial relationship between the similar blocks, a comparison distance is selected. On the basis of the comparison distance, the similar blocks are aggregated and a plurality of aggregated areas is provided. On the basis of the plurality of aggregated areas, comparison possible areas of the lithography mask are defined. Using an inspection module, images of at least some comparison possible areas of the comparison possible areas of the lithography mask is acquired. The acquired images are compared.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 16 / 752,353, filed January 24, 2020, the disclosure of which is incorporated herein by reference in its entirety for all purposes. [Background technology]

[0002] The lithographic mask is exposed to radiation during a lithographic process, thereby forming a pattern on the wafer.

[0003] An error in a lithography mask can result in a large number of defective wafers, and different mask errors can be associated with different costs.

[0004] The costs associated with some lithography mask errors are significant, which calls for rigorous inspection of lithography masks.

[0005] Lithography masks include multi-die lithography masks and single-die lithography masks. A multi-die mask can form multiple dies when exposed during a lithography process. A single-die mask can form multiple dies when sequentially exposed during a lithography process.

[0006] Multi-die lithography masks can be inspected using die-to-die comparison.

[0007] Single die lithography masks cannot be inspected using die-to-die comparison.

[0008] There is an increasing need to provide an accurate and rapid method for inspecting lithographic masks without the use of die-to-die comparison. Summary of the Invention

[0009] Aspects and embodiments of the present disclosure are directed to inspecting lithography masks using in-die references for die-to-die defect detection techniques. The disclosed method uses the following operational steps: finding similar blocks of the lithography mask, where the similar blocks are defined by similar CAD information, selecting a comparison distance based on (i) the area of ​​the similar blocks and (ii) the spatial relationship between the similar blocks, aggregating the similar blocks based on the comparison distance to provide a plurality of aggregated areas, and defining a comparable region of the lithography mask based on the plurality of aggregated areas. Additional operational steps may be obtaining images of at least some of the comparable regions, and comparing the images of at least some of the comparable regions to provide an inspection result.

[0010] In one embodiment, defining comparable regions may include at least one of (i) ignoring aggregated areas that do not meet a size criterion, and (ii) adding striped aggregated areas to each other.

[0011] In some implementations, selecting the comparison distance may include calculating, for each distance in the set of distances, an aggregate area of ​​similar blocks spaced apart by that distance, thereby providing the set of aggregate areas. Alternatively, selecting the comparison distance may include finding the largest aggregate area in the set of aggregate areas and defining the distance associated with the largest aggregate area as the comparison distance.

[0012] In some implementations, selecting the set of distances precedes providing the set of aggregate areas. Selecting the set of distances can include ignoring distances that are less than a distance threshold. The method can include repeating providing the set of aggregate areas for different sets of distances.

[0013] In one embodiment, aggregating similar blocks can include defining contiguous stripes, each of which has a width equal to the comparison distance, finding similar blocks in each pair of adjacent stripes of the contiguous stripes that are spaced apart by the comparison distance, and ignoring blocks in each pair of adjacent stripes that do not have similar blocks spaced apart by the comparison distance.

[0014] In one embodiment, the method may include repeating the steps of selecting a comparison distance, aggregating similar blocks, and defining comparable regions for each of a plurality of directions oriented relative to one another.

[0015] The disclosed system includes a computer system for performing one or more of the methods described herein. In one embodiment, the computer system is connected to or integrated with an inspection system that includes a mechanical stage for carrying a lithographic mask to be inspected and an image acquisition module for acquiring an image of a portion or the entire lithographic mask.

[0016] In one embodiment, the system comprises a non-transitory computer-readable storage medium on which instructions encoding one or more of the methods described herein may be stored.

[0017] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of this specification, however, the invention, both as to organization and method of operation, together with its objects, features and advantages, may best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings. [Brief description of the drawings]

[0018] [Figure 1] 1 is a flow diagram of a method for generating within-die fiducials in accordance with one or more aspects of the present disclosure. [Diagram 2] 1 is a flow diagram of a method for inspecting a lithography mask in accordance with one or more aspects of the present disclosure. [Diagram 3] 1 is a flow diagram of a method for generating within-die fiducials in accordance with one or more aspects of the present disclosure. [Figure 4] 1 is a flow diagram of a method for generating within-die fiducials in accordance with one or more aspects of the present disclosure. [Diagram 5] FIG. 1 is a block diagram of an exemplary inspection system operating in accordance with examples of the present invention. [Figure 6] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 7] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 8] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 9] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 10] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 11] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 12] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 13]1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 14] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 15] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 16] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 17] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. [Figure 18] 1A-1C are schematic diagrams illustrating areas of a lithographic mask illustrating aspects of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] It will be understood that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

[0020] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the present invention.

[0021] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of this specification, however, the invention, both as to organization and method of operation, together with its objects, features and advantages, may best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings.

[0022] It will be understood that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

[0023] Because the illustrated embodiments of the present invention can, for the most part, be implemented using electronic components and circuits known to those skilled in the art, they will not be described in any more detail than is deemed necessary for an understanding and appreciation of the ideas underlying the present invention, as set forth above, in order to avoid obscuring or distracting from the teachings of the present invention.

[0024] Any reference in this specification to a method should, mutatis mutandis, apply to a system capable of carrying out the method, and should, mutatis mutandis, apply to a non-transitory computer readable medium storing instructions for carrying out the method when executed by a computer.

[0025] Any reference in this specification to a system should be applied, mutatis mutandis, to methods that the system may perform, and should be applied, mutatis mutandis, to a non-transitory computer readable medium storing instructions that the system may perform.

[0026] Any reference herein to a non-transitory computer readable medium should be applied, mutatis mutandis, to a system capable of executing instructions stored on that non-transitory computer readable medium, and should be applied, mutatis mutandis, to a method by which a computer reading and executing instructions stored on that non-transitory computer readable medium can execute.

[0027] Detecting defects on masks and on wafers using die-to-die defect detection techniques is well known. An image of a die to be measured is compared to an image of a reference die, and the differences between the die images are analyzed to detect defects. The reference die can be another die on the same mask or on the same wafer.

[0028] Defect-free manufacturing of single die masks poses challenges using die-to-die techniques, for example, in single die mask inspection, there is no reference die.

[0029] According to an embodiment of the present invention, a method is provided for generating an intra-die fiducial for a die-to-die defect detection technique. The fiducial is generated by defining comparable regions within a die based on analyzing die design data and imaging the comparable regions with an inspection tool. A dedicated imaging plan for the inspection tool for the comparable regions can be created. The comparable regions can be defined such that the dedicated imaging plan is optimized with respect to operational considerations for the operation of the inspection tool. For example, fewer reorientations of a mechanical stage of the inspection tool may be required to scan the comparable regions.

[0030] Once images of comparable areas are obtained, they can be used for defect detection using known die-to-die defect detection techniques.

[0031] FIG. 1 illustrates a method 700 according to one embodiment of the present invention.

[0032] The method 700 is a method for generating comparable regions using computer-aided design information.

[0033] The method 700 may begin with step 710 of finding similar blocks of a lithography mask. As used herein, the term "block" refers to a portion of an area of ​​a lithography mask die. Each block of a lithography mask is defined by computer-aided design information. Alternatively, the blocks may be defined using "design intent" information for the mask. Post-OPC information may also be used. The invention is not limited by the particular technique used to find similar blocks, and known similarity analysis techniques may be used.

[0034] Blocks can be defined to correspond to functionality criteria, e.g., CPU cores, memory regions, etc. Blocks can be defined based on size criteria, where a block is defined as a sufficiently large mask area where image registration inaccuracies, edge imaging effects, throughput-related and other imaging factors and operational considerations will not degrade the efficiency and completeness of inspection and detection. According to an embodiment of the present invention, blocks are defined automatically based on design information and by using similarity criteria. Alternatively, blocks and / or block sizes can be predefined or empirically set based on trial and error testing during a preliminary preparation stage.

[0035] For illustration, given a lithography mask with an area of ​​10 cm×10 cm, and a typical pixel size of a few nanometers, e.g. 30 nm×30 nm or less, the block size, which is the minimum size of the comparable region, can be defined in the order of hundreds of nanometers, e.g. 100 nm×100 nm, hundreds of μm, e.g. 100 μm×100 μm, hundreds of millimeters, e.g. 100 mm×100 mm, and more. According to an embodiment of the invention, a minimum block size can be set. The invention is not limited by the shape of the blocks and comparable regions, and for simplicity, the examples given above relate to squares.

[0036] Similar blocks are defined by similar computer-aided design information.

[0037] In accordance with known techniques for assessing similarity, the term "similar" means identical up to an acceptable deviation, which may refer to the acceptable number of different patterns, the acceptable number of block segments that differ from each other.

[0038] The allowable deviation may be a predefined value, a value defined by the lithography mask manufacturer, a mask shop, a programmer, or an inspection tool user.

[0039] When comparing two blocks, non-limiting examples of acceptable deviations between the two blocks are that the number of corresponding block segments that differ from each other is up to 1, 2, 3, 4, or 5 percent (or more). Corresponding block segments are located at the same position within the pair of blocks.

[0040] According to another embodiment (not shown in FIG. 4), step 710 is replaced with an alternative step of receiving similar blocks of a lithography mask. For example, the die layout information can be provided from another system or by a user.

[0041] After finding similar blocks, repeating combinations of similar blocks need to be found.

[0042] This repeating combination can be determined in terms of a comparison distance, a characteristic that corresponds to the repeating period of the repeating combination of similar blocks.

[0043] Step 710 may be followed by step 720 of selecting a comparison distance based on (i) the area of ​​similar blocks of the target lithographic mask and (ii) the spatial relationship between the similar blocks. The similar blocks are defined by similar CAD information.

[0044] The spatial relationship may include the distance between similar blocks.

[0045] It may be desirable to provide a comparable region that includes multiple similar blocks. Inspection of lithographic masks may benefit (higher signal-to-noise ratio, higher robustness) from a comparable region that includes multiple similar blocks.

[0046] Step 720 may be followed by step 730 of aggregating similar blocks based on the comparison distance to provide multiple aggregated areas.

[0047] Step 730 may be followed by step 740 of defining comparable regions of the lithographic mask based on the multiple aggregate areas.

[0048] Comparable regions define areas of lithographic masks that should be compared to each other when inspecting the lithographic masks. Comparable regions can be included in an inspection recipe. For example, the locations of the comparable regions can be used to set the image acquisition plan of an inspection tool.

[0049] The comparable regions can be stored, sent to another system, used for inspecting lithography masks, etc.

[0050] FIG. 2 illustrates a method 701 according to one embodiment of the present invention.

[0051] Method 701 is a method for inspecting a lithographic mask. The inspection uses comparable regions.

[0052] The method 701 may begin with a series of steps including steps 710 , 720 , 730 and 740 .

[0053] Following step 740, a step 810 may be performed of obtaining images of at least some of the comparable regions.

[0054] Step 810 may include obtaining images of two, some, or all of the comparable regions found during step 740 .

[0055] Step 810 may include irradiating the lithographic mask with radiation (or irradiating at least at least some of the comparable areas) and acquiring an image with an inspection system or other system that senses radiation resulting from the irradiation.

[0056] Alternatively, step 810 may include retrieving images of at least some of the comparable regions rather than generating images, which may include, for example, retrieving images from a memory unit, an inspection system, etc.

[0057] Following step 810, a step 820 may be performed in which the images of at least some of the comparable regions are compared to provide an inspection result.

[0058] A testing method may be provided that may begin by receiving information regarding comparable regions, following which steps 810 and 820 may be performed.

[0059] According to one embodiment of the present invention, the spatial relationship between similar blocks, and in particular the distance between similar blocks, may be responsive to multiple directions, including directions oriented at 90 degrees or other angular deviations relative to each other.

[0060] For example, assume the multiple directions include an X-axis and a Y-axis. In this case, generating comparable regions includes defining an X-axis comparable region and defining a Y-axis comparable region.

[0061] Defining the X-axis comparable region may include selecting an X-axis comparison distance based on a spatial relationship along the X-axis, aggregating similar blocks, and defining the X-axis comparable region.

[0062] Defining the Y-axis comparable region may include selecting a Y-axis comparison distance based on a spatial relationship along the Y-axis, aggregating similar blocks, and defining the Y-axis comparable region.

[0063] FIG. 3 illustrates a method 702 according to one embodiment of the present invention.

[0064] The method 702 may begin at step 708 with selecting a new direction (eg, the X-axis or the Y-axis).

[0065] Following step 708, steps 710, 720, 730 and 740 may be performed.

[0066] Following step 740 a jump can be made to step 708.

[0067] When the directions are the X and Y axes, two iterations of steps 710, 720, 730 and 740 are performed.

[0068] After all iterations of steps 710, 720, 730 and 740 are completed, comparable regions for multiple directions have been found.

[0069] When inspecting a lithographic mask, comparable areas for one or more directions can be used.

[0070] Thus, following step 740, steps 810 and 820 may be performed.

[0071] FIG. 4 illustrates a method 703 according to one embodiment of the present invention.

[0072] FIG. 4 illustrates some of the steps that may be included in steps 720, 730, and 740.

[0073] Step 720 may include steps 721, 722, and 723. Step 721 is followed by step 722, and step 722 is followed by step 723.

[0074] Step 721 may include selecting a set of distances, which may include a number of different distances, from which a comparison distance is selected.

[0075] A minimum and / or maximum distance threshold may be selected, and the minimum and / or maximum distance threshold may remain fixed during execution of method 703 or may vary over time.

[0076] For example, FIG. 9 shows four distances V1, V2, V3 and V4 defined between different similar blocks belonging to two areas 200 and 300 of a lithographic mask.

[0077] Step 721 may be followed by step 722 of calculating, for each distance in the set of distances, the aggregate area of ​​similar blocks spaced that distance apart, thereby providing a set of aggregate areas.

[0078] See, for example, Table 333 in FIG.

[0079] Table 333 includes a column for the distance of each of V1, V2, V3, and V4. Table 333 has three rows: one showing the distance, another row ("related similar blocks") listing blocks that have similar blocks located at a distance from them, and a third row showing the aggregate size of all the similar blocks (area(V1), area(V2), area(V3), and area(V4)).

[0080] With respect to distance V1, the related similar blocks include blocks 203-210, 215, 216, 218, 303-306, and 311-318, and the aggregate size of these blocks is indicated by area(V1).

[0081] For distance V2, the related similar blocks include blocks 203-206, 303-305, and 311-314, and the aggregate size of these blocks is indicated by area(V2).

[0082] For distance V3, the related similar blocks include blocks 201, 202, 203-214, and 215-219, and the aggregate size of these blocks is indicated by area (V3).

[0083] For distance V4, the related similar blocks include blocks 203, 207-210, and 215-218, and the aggregate size of these blocks is indicated by area(V4).

[0084] Step 722 may be followed by step 723 of finding the largest aggregated area of ​​the set of aggregated areas and defining the distance associated with this largest aggregated area as a comparison distance.

[0085] For example, referring to the example of FIG. 9, assuming that area (V1) is greater than each one of area (V2), area (V3) and area (V4), V1 is the comparison distance.

[0086] Step 730 may include steps 731, 732, and 733. Step 731 may be followed by steps 732 and 733.

[0087] Step 731 may include defining contiguous stripes, each of which has a stripe width equal to the comparison distance.

[0088] Step 732 may include finding similar blocks in each pair of adjacent ones of these contiguous stripes that are spaced a comparison distance apart.

[0089] Step 733 may include ignoring blocks in each pair of adjacent stripes that do not have a similar block spaced a comparison distance apart.

[0090] Steps 731, 732 and 733 may be performed multiple times for different comparison distances.

[0091] Step 740 may include step 741.

[0092] Step 741 may include at least one of (i) ignoring aggregated areas that do not meet a size criterion (e.g., the width and / or height of the aggregated area may be too small (less than a predefined threshold)) and (ii) adding striped aggregated areas to each other.

[0093] FIG. 5 shows a lithographic mask 1990 and inspection system 1900 in accordance with one embodiment of the present invention.

[0094] The inspection system 1900 may include a processor 1920, a mechanical stage 1940, and an image acquisition module 1910. The image acquisition module 1910 may include an optical component 1914 and a controller 1912 for controlling the optical component 1914.

[0095] The mechanical stage 1940 is configured to support the lithography mask 1990 and move the lithography mask 1990 relative to the image acquisition module 1910 .

[0096] The optical component 1914 is configured (under the control of the controller 1912) to illuminate the lithography mask 1990 (or at least a comparable area of ​​the lithography mask 1990), detect radiation resulting from this illumination, and generate an image of the lithography mask 1990 (or the illuminated comparable area).

[0097] The optics 1914 are configured (under the control of the controller 1912) to irradiate the lithography mask 1990 with one or more beams of any type of radiation (visible, ultraviolet, deep ultraviolet, extreme ultraviolet, electrons, ions).

[0098] The image acquisition module 1910 can detect photons, electrons and / or ions.

[0099] The optics 1914 may detect transmitted radiation (transmitted through the lithographic mask 1990), scattered particles and / or photons, reflected particles and / or photons, and the like.

[0100] The inspection system 1900 may or may not be an aerial inspection system.

[0101] The processor 1920 may be configured to calculate the comparable area and, additionally or alternatively, may be configured to process the detection signal from the image acquisition module 1910 to provide an inspection result.

[0102] In some cases, the blocks are large enough that there is no need to aggregate them, but even in this case, the choice of the areas that form the comparable region is not trivial and a tradeoff between throughput and accuracy must be made.

[0103] FIG. 6 illustrates various areas of a lithographic mask 100, in accordance with one embodiment of the present invention.

[0104] The various areas include areas A1 101 and A2 102 of a first level, areas B 110, B1 111 and B2 112 of a second level, areas C 120, C1 121, C2 122 and C3 123 of a second level, area D 130 of a fourth level, area E 131 of a fifth level, area F 132 of a sixth level, areas G 140, G1 141, G2 142 and G3 143 of a seventh level, area H 133 of an eighth level, areas I1 135 and I2 136 of a ninth level, and area T 134 of a tenth level.

[0105] An area A1 101 in a first level includes an area B1 111 in a second level, an area C1 121 in a third level and an area G1 141 in a seventh level.

[0106] Area A2 102 of the first level includes area B2 112 of the second level, area C2 122 of the third level and area G2 142 of the seventh level.

[0107] The areas A1 101 and A2 102 in the first level are similar to each other. Assuming that the areas A1 101 and A2 102 in the first level are defined as comparable areas, the question remains whether to define the areas B1 111 and B2 112 in the second level as comparable areas.

[0108] Since areas B1 111 and B2 112 of the second level are already included in the comparable region (areas A1 101 and A2 102 of the first level), a comparison of areas B1 111 and B2 112 of the second level seems redundant.

[0109] On the other hand, if the areas B1 111 and B2 112 of the second level are not defined as comparable areas, then the area B 110 of the second level (located outside the areas A1 101 and A2 102 of the first level) cannot be evaluated since it has no comparable area to compare with.

[0110] The same considerations are applicable to defining the third level areas C1 121 and C2 122 as comparable regions.

[0111] The same considerations can be applied to defining the seventh level areas G1 141 and G2 142 as comparable regions. However, there are two seventh level areas (G 140 and G3 143) outside the first level areas A1 101 and A2 102, and it is simpler not to define the seventh level areas G1 141 and G2 142 as comparable regions.

[0112] According to one embodiment, a predefined number of areas should be selected from among a certain number of areas with the highest level, the predefined number and the certain number can be defined by the user of the inspection tool, the lithography mask manufacturer, the mask shop, etc.

[0113] FIG. 7 shows various areas 200 and 300 of a lithographic mask, according to one embodiment of the present invention.

[0114] Areas 200 and 300 contain multiple similar blocks of different types.

[0115] FIG. 8 illustrates various areas 200 and 300 of a lithographic mask and similar blocks 201-219 and 301-322 in those various areas, according to one embodiment of the present invention.

[0116] Blocks 201 to 219 belong to area 200, and blocks 301 to 322 belong to area 300.

[0117] Blocks 201 and 301 are similar to each other.

[0118] Blocks 202 and 302 are similar to each other.

[0119] Blocks 203-214 and 303-310 are similar to each other.

[0120] Blocks 215-219 and 311-322 are similar to each other.

[0121] FIG. 10 shows areas 410, 420, 430 and 440 of a lithographic mask, according to one embodiment of the present invention.

[0122] Areas 410, 420, 430, and 440 form a sequence of four consecutive stripes. Areas 410, 420, 430, and 440 are substantially identical to one another and contain similar blocks, such as (i) blocks 441, 442, 443, and 444 that are similar to one another, (ii) blocks 462, 463, and 464 that are similar to one another, (iii) blocks 472, 473, and 474 that are similar to one another, (iv) blocks 481, 482, 483, and 484 that are similar to one another, and (v) blocks 491, 492, 493, and 494 that are similar to one another.

[0123] Blocks 441 , 481 and 491 belong to area 410 .

[0124] Blocks 442 , 462 , 472 , 482 and 492 belong to area 420 .

[0125] Blocks 443, 463, 473, 483 and 493 belong to area 430.

[0126] Blocks 444 , 464 , 474 , 484 and 494 belong to area 440 .

[0127] Block 461 belongs to area 410 and is different from corresponding blocks 462 , 463 and 464 .

[0128] Block 471 belongs to area 410 and is different from corresponding blocks 472 , 473 and 474 .

[0129] FIG. 11 shows areas 410, 420, 430 and 440 of a lithographic mask, according to one embodiment of the present invention.

[0130] FIG. 11 shows that the comparison distance V is equal to the width of the area 410 .

[0131] 11 shows an area of ​​a lithographic mask after a first iteration of aggregating similar blocks based on comparison distance. In FIG. 11, a first area 410 is shown having (i) an X-axis value X L (ii) the leftmost block 4101 having a left boundary with an X-axis value of X L +V 452.

[0132] FIG. 12 shows areas 410, 420, 430 and 440 of a lithographic mask, according to one embodiment of the present invention.

[0133] FIG. 12 shows that block 4102, which extends beyond the left boundary, has been truncated.

[0134] The blocks in area 410 (after truncating block 4102) should be compared with the blocks in area 420.

[0135] 13 illustrates an area of ​​a lithographic mask after a second iteration of aggregating similar blocks based on comparison distance. In FIG. 13, a second area 420 is illustrated having (i) an X-axis value X L +V 452; and (ii) the leftmost block 4201 having a left boundary with an X-axis value of X L +2V 453 is defined as extending between the right boundary and

[0136] 14 illustrates an area of ​​a lithographic mask after a third iteration of aggregating similar blocks based on comparison distance. In FIG. 14, a third area 430 is illustrated having (i) an X-axis value X L+2V 453; and (ii) the leftmost block 4301 with a left boundary having an X-axis value X L +3V 454 is defined as extending between the right border and

[0137] The blocks in the third area 430 are compared to the blocks in the fourth area 440 .

[0138] The result of aggregating the blocks of areas 410, 420, 430, and 440 may be to define one of each of areas 410, 420, 430, and 440 as an aggregated area. Alternatively, the result of aggregating the blocks of areas 410, 420, 430, and 440 may be to define the combination of areas 410 and 420 as one aggregated area and the combination of areas 430 and 440 as another aggregated area.

[0139] If a lithographic mask includes separate instances of areas 410, 420, 430, and 440, the combination of areas 410, 420, 430, and 440 may be considered a single aggregate area.

[0140] FIG. 15 shows areas 511-514, 521-524, aggregate areas 531-534, and segments 535 and 536 of a lithographic mask according to one embodiment of the present invention.

[0141] Areas 511, 512, 513, 514, 521, 522, 523, and 524 are similar to each other and are arranged as two area series. The first area series includes areas 511-514. The second area series includes areas 521-524.

[0142] The first area column is disposed above the second area column, and is shifted to the left compared to the second area column.

[0143] FIG. 15 also shows four comparable areas 531 , 532 , 533 and 534 .

[0144] Comparable area 531 has a rectangular shape and includes a portion of area 511 and area 521. Comparable area 532 has a rectangular shape and includes areas 512 and 522. Comparable area 533 has a rectangular shape and includes areas 513 and 523. Comparable area 534 has a rectangular shape and includes areas 514 and a portion of area 524.

[0145] Because of the left shift between the first area column and the second area column, comparable area 531 includes segment 535.

[0146] Due to the left shift between the first area column and the second area column, segment 536 is outside of comparable area 534 .

[0147] Vacancies 535 and portions 536 do not compare with any corresponding portions. Therefore, this definition of comparable areas is flawed.

[0148] FIG. 16 shows areas 511-514, 521-524, aggregated areas 541-544 and aggregated areas 552-555 of a lithographic mask according to one embodiment of the present invention.

[0149] Aggregation area 541 includes area 511, aggregation area 542 includes area 512, aggregation area 543 includes area 513, and aggregation area 544 includes area 514.

[0150] Aggregation area 552 includes area 521, aggregation area 553 includes area 522, aggregation area 554 includes area 523, and aggregation area 555 includes area 524.

[0151] It should be noted that one aggregation area may include a combination of areas 511 and 512, and another aggregation area may include a combination of areas 513 and 514.

[0152] It should be noted that one aggregation area may include a combination of areas 521 and 522, and another aggregation area may include a combination of areas 523 and 524.

[0153] It should also be noted that one aggregation area may include a combination of areas 521-524, and another aggregation area may include a combination of areas 511-514.

[0154] FIG. 17 illustrates an area 600 that includes a number of blocks, according to one embodiment of the present invention.

[0155] Area 600 includes various blocks. Block 601 is similar to various blocks such as blocks 602, 603 and 604. The distance between block 601 and block 602 is V1, the distance between block 601 and block 603 is V2, and the distance between block 601 and block 604 is V3. V2 is greater than V1 and less than V3.

[0156] FIG. 17 shows that searching the comparison distances (and in particular selecting the set of distances from which the comparison distance is selected) can include starting with distances greater than or equal to V3, i.e., ignoring distances less than a distance threshold equal to V3.

[0157] With this restriction imposed, and after defining the aggregation area, other aggregation areas can be searched for by allowing the comparison distance to be less than V3, i.e., by decreasing the distance threshold. The distance threshold can be decreased to V2, and after defining the aggregation area (using V2), the distance threshold can be further decreased to V1. Alternatively, the distance threshold can be decreased from V3 to V1 or some other value less than V3.

[0158] It has been found that aggregation of blocks can be an iterative process that may involve modifying the comparison distance limit, which may involve lowering the comparison distance limit.

[0159] Starting aggregation from a higher limit for the comparison distance may result in a larger aggregation area.

[0160] Each subsequent iteration of aggregation may involve lowering the limit on the minimum comparison distance until a predefined threshold is reached.

[0161] When aggregating along a direction, an aggregated area may have the shape of a strip that is wider along this direction. One or more aggregated areas in strip form may be added to each other to provide comparable regions.

[0162] FIG. 18 illustrates comparable regions 920 and 930, X-axis aggregated areas 921, 922 and 923, and Y-axis aggregated areas 931, 932 and 933, according to one embodiment of the present invention.

[0163] X-axis aggregate areas 921 , 922 and 923 are strip-shaped areas that are combined to provide a comparable region 920 .

[0164] Y-axis aggregate areas 931 , 932 and 933 are strip-shaped areas that are combined to provide a comparable region 930 .

[0165] Any of the aggregation areas described with respect to Figures 11-18 can be comparable areas.

[0166] The embodiments of the invention described herein aim to enable.

[0167] In the foregoing specification, the invention has been described with reference to specific examples of embodiments thereof, but it will be evident that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims.

[0168] Furthermore, where terms such as "front," "back," "top," "bottom," "upper," "lower," and the like are used in this description and in the claims, such terms are used for purposes of explanation and not necessarily to describe permanent relative positions, and it is understood that these terms, as so used, are interchangeable, under appropriate circumstances, such that the embodiments of the invention described herein can, for example, operate in orientations other than those illustrated or in other ways than those described herein.

[0169] The connections discussed herein may be any type of connection suitable for transferring signals from the respective corresponding nodes, units or devices, e.g., via an intermediate device, or any type of connection suitable for transferring signals to the respective corresponding nodes, units or devices, e.g., via an intermediate device. Thus, unless otherwise implied or stated, the connections may be, e.g., direct or indirect connections. The connections may be illustrated or described as being single, multiple, unidirectional or bidirectional connections. However, the implementation of the connections may differ in different embodiments. For example, separate unidirectional connections may be used instead of bidirectional connections, and vice versa. Furthermore, the multiple connections may be replaced by a single connection that transfers multiple signals sequentially or in a time division multiplexed manner. Similarly, a single connection carrying multiple signals may be split into different connections carrying subsets of these signals. Thus, many options exist for transferring signals.

[0170] Although particular conductivity types or polarities of potentials are described in the examples, it should be understood that the conductivity types and polarities of potentials can be reversed.

[0171] Each signal described herein may be designed as positive logic or as negative logic. For negative logic signals, the signal is active low, with the logically true state corresponding to a logic level 0. For positive logic signals, the signal is active high, with the logically true state corresponding to a logic level 1. It should be noted that any signal described herein may be designed as a negative logic signal or as a positive logic signal. Thus, in alternative embodiments, those signals described as positive logic signals may be implemented as negative logic signals, and those signals described as negative logic signals may be implemented as positive logic signals.

[0172] Additionally, the terms "assert" or "set" and "negate" (or "deassert" or "clear") are used herein to refer to the rendering of a signal, status bit, or similar device into its logically true or logically false state, respectively. If the logically true state is a logic level 1, then the logically false state is a logic level 0. If the logically true state is a logic level 0, then the logically false state is a logic level 1.

[0173] Those skilled in the art will recognize that the boundaries between logical blocks are merely examples, and that alternative embodiments may merge logical blocks or circuit elements or impose alternative decompositions of functionality on various logical blocks or circuit elements. Thus, it is understood that the architectures illustrated herein are merely examples, and that in fact many other architectures may be implemented which achieve the same functionality.

[0174] Any arrangement of components to achieve the same functionality is substantially "associated" such that the desired functionality is achieved. Thus, any two components herein that are combined to achieve a particular functionality can be viewed as "associated" with one another such that the desired functionality is achieved, regardless of architecture or intervening components. Similarly, any two components so associated can also be viewed as "operably connected" or "operably coupled" with one another such that the desired functionality is achieved.

[0175] Moreover, those skilled in the art will recognize that the boundaries between operations described above are merely examples. Operations may be combined into a single operation, a single operation may be divided into multiple additional operations, and operations may be performed in a manner that at least partially overlaps in time. Additionally, alternative embodiments may include multiple instances of a particular operation, and the order of operations may be changed in various other embodiments.

[0176] Further, for example, in one embodiment, the illustrated examples may be implemented as circuitry located on a single integrated circuit or within the same device, or the examples may be implemented as any number of separate integrated circuits or separate devices interconnected with each other in any suitable manner.

[0177] However, other modifications, variations and alternatives are also possible. Accordingly, the specification and drawings are to be regarded in an illustrative sense and not in a restrictive sense.

[0178] In the claims, reference signs in parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of other elements or steps than those recited in the claim. Furthermore, as used herein, the terms "a" or "an" are defined as one or more than one. Furthermore, the use of introductory phrases such as "at least one" and "one or more" in a claim should not be construed as implying that the introduction of another claim element by the indefinite article "a" or "an" limits a particular claim containing such introduced claim element to an invention containing only one such element. This is true even when the same claim contains the introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an". The same is true with respect to the use of definite articles. Unless otherwise specified, terms such as "first" and "second" are used to arbitrarily distinguish between the elements that such terms describe. Thus, these terms are not necessarily intended to indicate a temporal or other priority of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

[0179] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes and equivalents will occur to those skilled in the art, and it is therefore to be understood that the appended claims are intended to cover all such modifications and changes which fall within the true spirit of the invention. [Explanation of symbols]

[0180] 100 Lithography Mask 200 Area of ​​lithography mask 300 Area of ​​lithography mask 410 Lithography Mask Area 420 Lithography Mask Area 430 Lithography Mask Area 440 Lithography Mask Area 511 Lithography Mask Area 512 Lithography Mask Area 513 Lithography Mask Area 514 Lithography Mask Area 521 Lithography Mask Area 522 Lithography Mask Area 523 Lithography Mask Area 524 Lithography Mask Area 531 Aggregation Area 532 Aggregation Area 533 Aggregation Area 534 Aggregation Area 535 Segments 536 Segments 541 Aggregation Area 542 Aggregation Area 543 Aggregation Area 544 Aggregation Area 552 Aggregation Area 553 Aggregation Area 554 Aggregation Area 555 Aggregation Area 600 Area 601 Block 602 Block 603 Block 604 Block 920 Comparable area 921 X-axis aggregation area 922 X-axis aggregation area 923 X-axis aggregation area 930 Comparable area 931 Y-axis aggregation area 932 Y-axis aggregation area 933 Y-axis aggregation area 1900 Inspection System 1910 Image Acquisition Module 1912 Controller 1914 Optical components 1920 Processor 1940 Machine Stage 1990 Lithography Mask

Claims

1. A method for generating in-die fiducials for a lithography mask, comprising: finding similar blocks of the lithography mask, the similar blocks being defined by similar CAD information; selecting a comparison distance based on (i) the area of ​​the similar blocks and (ii) the spatial relationship between the similar blocks; aggregating the similar blocks based on the comparison distance to provide a plurality of aggregated areas; defining a comparable region that provides the within-die reference for the lithography mask based on the plurality of aggregate areas; A method comprising:

2. The method of claim 1 , comprising obtaining images of at least some of the comparable areas and comparing the images of the at least some of the comparable areas to provide an inspection result.

3. The method of claim 1 , wherein the defining the comparable regions comprises ignoring aggregate areas that do not meet a size criterion.

4. 2. The method of claim 1, wherein said selecting said comparison distances comprises: for each distance in a set of distances, calculating an aggregate area of ​​similar blocks spaced apart by said distances, thereby providing a set of aggregate areas.

5. 5. The method of claim 4, wherein the selecting the comparison distance comprises finding a largest aggregate area among the set of aggregate areas and defining a distance associated with the largest aggregate area as the comparison distance.

6. 5. The method of claim 4, wherein selecting the set of distances precedes the providing the set of aggregate areas, and wherein selecting the set of distances includes ignoring distances that are less than a distance threshold.

7. The method of claim 6 , comprising repeating the providing of the set of aggregate areas for different sets of distances.

8. aggregating the similar blocks defining consecutive stripes, each stripe width of said consecutive stripes being equal to said comparison distance; finding similar blocks in each pair of adjacent ones of said consecutive stripes that are spaced apart by said comparison distance; and ignoring blocks in each pair of adjacent stripes that do not have a similar block spaced apart by the comparison distance. The method of claim 1 , comprising:

9. 2. The method of claim 1, comprising repeating the steps of selecting the comparison distance, aggregating the similar blocks, and defining the comparable region for each of a plurality of directions oriented relative to one another.

10. A non-transitory computer-readable medium comprising instructions for generating in-die fiducials for a lithography mask, the instructions, when executed by a processor, causing the processor to: finding similar blocks of the lithographic mask, the similar blocks being defined by similar CAD information; selecting a comparison distance based on (i) the area of ​​the similar blocks and (ii) the spatial relationship between the similar blocks; aggregating the similar blocks based on the comparison distances to provide a plurality of aggregated areas; and defining a comparable region that provides the within-die reference for the lithography mask based on the plurality of aggregate areas; A non-transitory computer-readable medium for causing operations to be performed, including:

11. A system for generating in-die fiducials for a lithography mask, comprising: Memory, Finding similar blocks of a lithographic mask, the similar blocks being defined by similar CAD information; selecting a comparison distance based on (i) the area of ​​the similar blocks and (ii) the spatial relationship between the similar blocks; aggregating the similar blocks based on the comparison distances to provide a plurality of aggregated areas; and defining a comparable region that provides the within-die reference for the lithography mask based on the plurality of aggregate areas; a processor operatively coupled to the memory and configured to execute instructions to A system comprising:

12. the system is connected to or integrated with an inspection system capable of inspecting lithography masks, and the processor further comprises: obtaining an image of at least a portion of the comparable area; configured to compare the images of the at least some of the comparable regions to provide an inspection result. The system of claim 11.

13. To define the comparable region, the processor further (i) ignoring aggregated areas that do not meet a size criterion; and / or (ii) configuring striped aggregated areas to be added together; The system of claim 11.

14. To select, the processor further comprises: configured to calculate, for each distance in the set of distances, an aggregate area of ​​similar blocks spaced apart by said distances, thereby providing a set of aggregate areas. The system of claim 11.

15. To select, the processor further comprises: Find the largest aggregate area of ​​the set of aggregate areas, configured to define as the comparison distance a distance associated with the largest aggregate area; The system of claim 11.

16. The processor further comprises: configured to select the set of distances by ignoring distances that are less than a distance threshold before providing the set of aggregated areas; The system of claim 11.

17. The processor further comprises: and repeating the providing of the set of aggregate areas for different sets of distances.

17. The system of claim 16.

18. To aggregate the similar blocks, the processor further comprises: defining consecutive stripes, each of said consecutive stripes having a width equal to said comparison distance; finding similar blocks in each pair of adjacent ones of said consecutive stripes that are spaced apart by said comparison distance; configured to ignore blocks in each pair of adjacent stripes that do not have a similar block spaced apart by the comparison distance; The system of claim 11.

19. The processor further comprises: configured to repeat the steps of selecting the comparison distance, aggregating the similar blocks, and defining the comparable region for each of a plurality of directions oriented relative to one another. The system of claim 11.

Images