System and method for fiber position mapping in multibeam systems

Abstract

The multi-beam system includes a light source configured to emit light, a fiber bundle connected to the light source, and a camera configured to capture an image set including an image corresponding to each fiber connected to the light source. The fiber bundle includes a central fiber having one end connected to the light source and N layers of fibers surrounding the central fiber. A first fiber layer includes M fibers each having one end connected to the light source, and an Nth fiber layer includes more than M fibers, but only M fibers in the Nth fiber layer have one end connected to the light source. The processor is configured to determine a centroid of each image in the image set to generate a centroid map, and generate a fiber position map including fiber positions of all fibers in the fiber bundle based on the centroid map.

Description

Technical Field

[0001] The present disclosure relates to inspection systems, and more particularly, to multi-beam inspection systems.

Background Art

[0002] Reference to Related Applications This application was filed on July 2, 2021, and claims priority to U.S. Provisional Application 63 / 218,083. The entire disclosure thereof is incorporated herein by reference.

[0003] The evolution of the semiconductor manufacturing industry has placed greater demands on yield management, particularly on metrology and inspection systems. Critical dimensions continue to shrink, and the industry needs to reduce the time to achieve high yields and high-value production. Minimizing the total time from detecting a yield problem to fixing it determines the return on investment for semiconductor manufacturers.

[0004] Manufacturing semiconductor devices such as logic devices and memory devices typically involves processing semiconductor wafers using a number of manufacturing processes to form various features and multiple levels of the semiconductor device. For example, lithography is a semiconductor manufacturing process that involves transferring a pattern from a reticle to a photoresist disposed on a semiconductor wafer. Further examples of semiconductor manufacturing processes include, but are not limited to, chemical mechanical polishing (CMP), etching, deposition, and ion implantation. Multiple semiconductor devices can be manufactured on a single semiconductor wafer that is separated into individual semiconductor devices.

[0005] Inspection processes are used at various steps during semiconductor manufacturing to detect defects on wafers in order to promote higher yields in the manufacturing process and thus higher profits. Inspection has always been an important part of manufacturing semiconductor devices such as integrated circuits (ICs). However, as the dimensions of semiconductor devices decrease, inspection becomes even more crucial for the successful manufacture of acceptable semiconductor devices, as even smaller defects can cause the device to fail. For example, as the dimensions of semiconductor devices shrink, even relatively small defects can cause undesirable aberrations in the semiconductor device, thus necessitating the detection of defects of reduced size.

[0006] One device used in the inspection process is a multi-beam system. In a multi-beam system, multiple beamlets are focused onto a scintillator. The light from the scintillator may be focused using optical fibers. The focused beamlets should be aligned to the precise fiber positions on the scintillator in order to calibrate the system. However, the precise fiber positions cannot be easily predicted based on the mechanical tolerances of the optical fibers. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] U.S. Patent No. 6587189 [Patent Document 2] U.S. Patent Application Publication No. 2013 / 0058661 [Overview of the project] [Problems that the invention aims to solve]

[0008] Therefore, a method for fiber position mapping is needed for multi-beam calibration and alignment. [Means for solving the problem]

[0009] Embodiments of this disclosure provide a method for fiber position mapping in a multibeam system. The method may include emitting light from a light source. The light may be directed towards a camera.

[0010] The method may further include providing a fiber bundle. The fiber bundle may comprise a central fiber having one end connected to a light source, and N layers of fibers surrounding the central fiber. The first layer of the fiber may be the innermost of the N layers, and the nth layer of the fiber may be the outermost of the N layers, and N ≥ 2. The first layer of the fiber may contain M fibers, and each of the M fibers in the first layer of the fiber may have one end connected to a light source. The nth fiber layer may contain more than M fibers, and the M fibers in the nth fiber layer may have one end connected to a light source.

[0011] The method may further include a step of capturing an image set using a camera. The image set may include images corresponding to each fiber connected to the light source.

[0012] The method may further include the step of determining the centroid of each image in a set of images using a processor to generate a centroid map. The processor can determine the light intensity of each pixel in each image in the set of images. When one pixel is determined to have the highest intensity among the pixels in an image, the (x,y) position of that pixel may be determined as the centroid of the image. When multiple pixels are determined to have the highest intensity among the pixels in an image, the centroid of the image may be determined based on the (x,y) position of each of the pixels with the highest intensity.

[0013] The method may further include the step of using a processor to generate a fiber position map, which includes the fiber positions of all fibers in the fiber bundle, based on the centroid map. The processor may be configured to determine the pitch and rotation of the centroid of each image in the image set, based on the centroid map. The processor may further be configured to determine the fiber positions of the remaining fibers in the Nth layer of the fiber bundle, based on the pitch and rotation. The processor may further be configured to generate a fiber position map, which includes the centroids and fiber positions of the remaining fibers in the Nth layer of the fiber bundle.

[0014] According to embodiments of the present disclosure, the processor may further be configured to determine the fiber positions of all fibers between a first fiber layer and a nth fiber layer in a fiber bundle based on pitch and rotation. The processor may further be configured to generate a fiber position map including the centroid, the fiber positions of the remaining fibers in the nth layer of the fiber bundle, and the fiber positions of all fibers between the first fiber layer and the nth fiber layer in the fiber bundle.

[0015] According to embodiments of this disclosure, only the central fiber, the M fibers of the first layer, and the M fibers of the Nth layer may be connected to the light source.

[0016] According to embodiments of the present disclosure, the N layers of fiber may surround a central fiber in a polygonal shape, and the M fibers in the N layers may correspond to the corners of the polygon. The N layers of fiber may surround a central fiber in a hexagonal shape, and the M fibers within the N layers may correspond to the corners of the hexagon.

[0017] According to embodiments of this disclosure, the fiber bundle may include more than 300 fibers.

[0018] According to one embodiment of the present disclosure, the method may further include the step of calibrating a multibeam system based on a fiber position map. The processor may further be configured to receive images from a beam source having a multibeam array. The processor may further be configured to superimpose the fiber position map onto the images from the beam source. The processor may further be configured to align the center of the fiber position map with the images from the beam source to determine an error, the error including displacement, rotation, orthogonality, aspect ratio, magnification, or astigmatism. The processor may further be configured to perform linear distortion correction based on the error.

[0019] Another embodiment of the present disclosure provides a multibeam system. The system may include a light source configured to emit light.

[0020] The system may further include a fiber bundle. The fiber bundle may comprise a central fiber having one end connected to a light source, and N layers of fibers surrounding the central fiber. The first layer of the fiber may be the innermost layer, and the nth layer of the fiber may be the outermost layer, with N ≥ 2. The first layer of the fiber may contain M fibers, each of which may have one end connected to a light source. The nth fiber layer may contain more than M fibers, each of which may have one end connected to a light source.

[0021] The system may further include a camera configured to capture an image set. The image set may include images corresponding to each fiber connected to the light source.

[0022] The system can further include a processor that communicates electronically with the camera. The processor can be configured to determine the centroid of each image in the image set to generate a centroid map. The processor can determine the intensity of the light of each pixel of each image in the image set. When one pixel is determined to have the highest intensity among the pixels in one image, the (x, y) position of that pixel can be determined as the centroid of the image. When multiple pixels are determined to have the highest intensity among the pixels in one image, the centroid of the image can be determined based on the (x, y) positions of each of the pixels having the highest intensity.

[0023] The processor may further be configured to generate a fiber position map that includes the fiber positions of all the fibers in the fiber bundle based on the centroid map. The processor can be configured to determine the pitch and rotation of the centroid of each image in the image set based on the centroid map. The processor may further be configured to determine the fiber positions of the remaining fibers in the Nth layer of the fiber bundle based on the pitch and rotation. The processor may further be configured to generate a fiber position map that includes the centroids and fiber positions of the remaining fibers in the Nth layer of the fiber bundle.

[0024] According to an embodiment of the present disclosure, the processor may further be configured to determine the fiber positions of all the fibers between the first fiber layer and the Nth fiber layer in the fiber bundle based on the pitch and rotation. The processor may further be configured to generate a fiber position map that includes the centroid, the fiber positions of the remaining fibers in the Nth layer of the fiber bundle, and the fiber positions of all the fibers between the first fiber layer and the Nth fiber layer in the fiber bundle.

[0025] According to an embodiment of the present disclosure, only the central fiber, the M fibers of the first layer, and the M fibers of the Nth layer may be connected to the light source.

[0026] According to an embodiment of the present disclosure, the N-layer fiber may surround the central fiber in a polygonal shape, and the M fibers of the N-layer fiber may correspond to the corners of the polygonal shape. The N layers of fibers may surround the central fiber in a hexagonal shape, and the M fibers in the N layers may correspond to the corners of the hexagon.

[0027] According to an embodiment of the present disclosure, the fiber bundle may include more than 300 fibers.

[0028] According to an embodiment of the present disclosure, the processor may be further configured to calibrate the multi-beam system based on the fiber position map. The processor may further be configured to receive an image from a beam source having a multi-beam array. The processor may further be configured to overlay the fiber position map on the image from the beam source. The processor may further be configured to align the center of the fiber position map with the image from the beam source to determine an error, which includes offset, rotation, orthogonality, aspect ratio, magnification, or aberration. The processor may be further configured to perform linear distortion correction based on the error.

Brief Description of the Drawings

[0029] To more fully understand the nature and objects of the present disclosure, reference should be made to the following detailed description in conjunction with the accompanying drawings. [Figure 1] It is a flowchart of a method for fiber position mapping in a multi-beam system according to an embodiment of the present disclosure. [Figure 2A] It is a diagram showing an exemplary image of one fiber according to an embodiment of the present disclosure. [Figure 2B] It is a diagram showing an exemplary centroid map according to an embodiment of the present disclosure. [Figure 3] It is a diagram showing an example of a fiber position map according to an embodiment of the present disclosure. [Figure 4] It is a diagram showing further steps of the method of the present disclosure for calibrating a multi-beam system. [Figure 5A] This is a schematic diagram of a multibeam system according to one embodiment of the present disclosure. [Figure 5B] This is a schematic cross-sectional view of a fiber bundle according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0030] While the claimed subject matter is described in relation to certain embodiments, other embodiments, including those that do not provide all of the benefits and features described herein, are also within the scope of this disclosure. Various structural, logical, process steps, and electronic modifications can be made without departing from the scope of this disclosure. Accordingly, the scope of this disclosure is defined solely by reference to the appended claims.

[0031] Embodiments of this disclosure provide a method for fiber position mapping in a multibeam system. As shown in Figure 1, the method may include the following steps.

[0032] In step 101, light is emitted from a light source. The light source may be an LED light source. The light may be directed towards a camera. The camera may be a charge-coupled device (CCD) camera.

[0033] In step 102, a fiber bundle is provided. The fiber bundle may include a plurality of fibers extending parallel to each other. The fibers may be silica fibers. The diameter of each fiber may vary based on the wavelength of light that can be transmitted by the fiber. The plurality of fibers may have the same diameter. The plurality of fibers may be held together by an adhesive or frame to form a fiber bundle. The fiber bundle may include a central fiber. The central fiber may be located at the center of the fiber bundle and surrounded by the other fibers in the fiber bundle. In some embodiments, a plurality of fibers may be located at the center of the fiber bundle, and therefore these fibers may be considered collectively as the central fiber. The central fiber may have one end connected to a light source. For example, one end of the central fiber may be positioned on the light source so that light emitted from the light source is directed through the central fiber.

[0034] A fiber bundle may further contain N layers of fiber. The N layers of fiber may surround a central fiber. In a fiber bundle of N layers, the first layer of fiber may be defined as the innermost layer of the N layers. For example, the first layer may be closest to the central fiber and may directly surround it. In a fiber bundle of N layers, the Nth layer of fiber may be defined as the outermost layer of the N layers. For example, the Nth fiber layer may be furthest from the central fiber and may define the outer boundary of the fiber bundle. In a fiber bundle of N layers, N may be 2 or greater. For example, if N=2, the Nth fiber layer may be the second fiber layer and may directly surround the first fiber layer. In another example, if N=3, the Nth fiber layer may be the third fiber layer and may be located between the first and Nth fiber layers. N may be any number greater than 2, and it can be understood that for each increasing number N, an additional layer of fiber is provided between the first and Nth layers.

[0035] The first layer of the fiber may contain M fibers, where M may be 4 or more.

[0036] According to certain embodiments of this disclosure, M=6. Each of the M fibers in the first layer of fibers may have one end connected to a light source. For example, one end of each of the M fibers in the first layer may be positioned on the light source so that light emitted from the light source can be directed through each of the M fibers in the first layer. The Nth fiber layer may contain more than M fibers. For example, if N=2 and M=6, the Nth fiber layer may contain 12 fibers. If N=3 and M=6, the Nth fiber layer may contain 18 fibers. Each of the M fibers in the Nth fiber layer may have one end connected to a light source. For example, one end of each of the M fibers in the Nth layer may be positioned on the light source so that light emitted from the light source passes through each of the M fibers in the Nth layer.

[0037] According to embodiments of this disclosure, only the central fiber, M fibers in the first layer, and M fibers in the nth layer may be connected to the light source. In other words, the number of fibers connected to the light source for any given fiber bundle may be equal to 2M+1. Thus, the remaining fibers in the nth layer, and all fibers in the layers between the first and nth layers, do not need to be connected to the light source. While more fibers may be connected to the light source, it can be understood that minimizing the number of fibers connected to the light source may simplify the system and reduce computational complexity. Each fiber connected to the light source may be connected to the light source by a separate connector.

[0038] According to embodiments of the present disclosure, the N layers of a fiber may surround a central fiber in a polygonal shape. The polygonal shape may be a regular polygon, meaning that all angles and sides of the polygon may be equal. For example, the shape of the polygon may be a triangle, a square, a pentagon, a hexagon, an octagon, or a polygon with any number of sides. The number of M fibers in the first layer of the fiber may correspond to the number of sides of the polygonal shape. For example, if M=6, the shape of the polygon may be a hexagon. The M fibers in the Nth fiber layer may correspond to the corners of the polygonal shape. For example, the N layers of the fiber may surround a central fiber in a hexagon, and the M fibers in the N layers may correspond to the corners of the hexagon.

[0039] As explained above, the number of fibers in a fiber bundle depends on the number of layers N and the number of fibers. With the first layer M, the number of fibers in the fiber bundle increases by several hundred, and the number of layers N increases the number of central fibers around the bundle. For example, a fiber bundle may contain more than 300 fibers. Although a fiber bundle may contain a large number of fibers, it should be understood that the number of fibers connected to the light source depends only on the M fibers in the first layer. For example, when M=6, 13 fibers can be connected to the light source regardless of the number of layers N and the total number of fibers in the fiber bundle.

[0040] In step 103, an image set is captured using a camera. The image set may include images corresponding to each fiber connected to the light source. For example, images may be captured corresponding to light directed through the central fiber, M fibers in the first layer, and M fibers in the Nth layer. In a particular embodiment where M=6, a total of 13 images can be captured. An exemplary image is shown in Figure 2A.

[0041] In step 104, the centroid of each image in the image set is determined using a processor to generate a centroid map. The centroid map may plot the (x,y) positions of each centroid on a graph, for example, as shown in Figure 2B. The centroid of each image may also be determined by image processing. For example, the processor may determine the intensity of light at each pixel in each image. The processor may perform filtering or smoothing operations on the image to remove noise before processing the image. If a pixel is determined to have the highest / peak intensity, the (x,y) position of this pixel may be determined as the centroid C of the image. If multiple pixels k are determined to have the highest / peak intensity, the centroid C may be determined based on the (x,y) position of each pixel k. For example, the centroid C may be determined by the following formula:

number

[0042] If multiple adjacent pixels have the highest / peak intensity, the (x,y) position of the central pixel of this group of pixels can be determined as the centroid C of the image.

[0043] In step 105, a fiber position map is generated using a processor. The fiber position map may include the fiber positions of all fibers in the fiber bundle based on the centroid map. For example, as shown in Figure 3, the fiber position map may plot the (x,y) positions of all fibers in the fiber bundle based on the (x,y) positions of each centroid on the graph. In Figure 3, the fiber positions from the centroid map (i.e., the positions of the central fiber, the M fibers in the first layer, and the M fibers in the Nth layer) are shown as solid lines, and the positions of all other fibers (i.e., the remaining fibers in the Nth layer and the fibers in the layers between the first and Nth layers) are shown as dotted lines, which can be determined based on the fiber bundle design.

[0044] According to embodiments of the present disclosure, step 105 may include the following steps: The pitch and rotation of the centroid of each image in the image set may be determined based on the centroid map. The pitch and rotation of the centroid of each image may correspond to the difference between the determined centroid position and the expected position of each fiber. For example, the pitch may be calculated based on the distance between the (x,y) position of the central fiber and the fiber in the first layer. The rotation may be determined based on the angle of a line extending from the central fiber to the fiber in the first layer. The pitch and rotation may also include comparisons between images. Naturally, the centroid position may not be exactly where expected due to mechanical tolerances of the optical components. For example, as shown in Figure 2B, the centroid of the central fiber is calculated as (1018, 1116), but the expected position is (1024, 1024). The fiber positions of the remaining fibers in the Nth layer of the fiber bundle may be determined based on the pitch and rotation. As explained above, the Nth fiber layer can contain more than M fibers, but the centroid is determined only for the M fibers in the Nth layer connected to the light source. For example, if N=3 and M=6, there may be 12 remaining fibers in the Nth fiber layer. The fiber positions of these fibers can be determined based on pitch and rotation. A fiber position map can be generated that includes the centroid and fiber positions of the remaining fibers in the Nth layer of the fiber bundle. For example, as shown in Figure 3, the fiber position map can plot the (x,y) positions of the remaining fibers in the Nth fiber layer based on the (x,y) position of each centroid on the graph.

[0045] According to embodiments of the present disclosure, step 105 may further include the following additional steps: The fiber positions of all fibers between the first fiber layer and the Nth fiber layer in the fiber bundle may be determined based on pitch and rotation.

[0046] As explained above, if N > 2, there may be one or more fiber layers between the first fiber layer and the nth fiber layer. The fiber positions of these fibers can be determined based on pitch and rotation. A fiber position map can be generated that includes the centroid, the fiber positions of the remaining fibers in the nth layer of the fiber bundle, and the fiber positions of all fibers between the first and nth fiber layers of the fiber bundle. For example, as shown in Figure 3, the fiber position map can plot the (x,y) positions of the fibers between the first and nth fiber layers based on the (x,y) position of each centroid on the graph and the fiber bundle design with respect to N and M.

[0047] According to embodiments of the present disclosure, method 100 may further include calibrating a multibeam system based on a fiber position map 106. Calibrating a multibeam system may include the following steps shown in Figure 4.

[0048] In step 107, the processor may receive an image from a tool that has errors. These errors may include shift (x / y deflection), ROAM (rotation, orthogonality, aspect ratio, and / or magnification), or astigmatism (shape distortion). Linear distortion correction may be performed based on the errors. A deflector in the system can be used to correct shift errors. Lenses can be used to correct ROAM errors or astigmatism errors.

[0049] In step 108, the fiber position map may be superimposed on the image from the tool, and its center may be identified.

[0050] In step 109, the center of the fiber position map can be aligned with the image from the tool, and shift, ROAM, and / or astigmatism can be determined. In other words, the difference between the fiber position map and the image from the tool can be quantified as shift, ROAM, and / or astigmatism.

[0051] In step 110, linear distortion correction can be performed using shift, ROAM, and / or astigmatism to calibrate the multibeam system.

[0052] Method 100 of the present disclosure can simply generate a fiber position map corresponding to the physical position of each fiber in a fiber bundle. The fiber position map can be used to calibrate and align a multibeam source to improve the accuracy and efficiency of the inspection process.

[0053] An embodiment of the present disclosure shown in Figure 5A provides a device 200. The device 200 may include a light source 210 configured to emit light. Light from the light source 210 may be directed to a camera 220. The camera 220 may be a charge-coupled device (CCD) camera.

[0054] The apparatus 200 may further comprise a fiber bundle 230. The fiber bundle 230 may include a plurality of fibers extending parallel to each other. The fibers may be silica fibers. The diameter of each fiber may vary based on the wavelength of light that can be transmitted by the fiber. The plurality of fibers may have the same diameter. The plurality of fibers may be held together by an adhesive or frame to form the fiber bundle 230. The fiber bundle 230 may include a central fiber 231. The central fiber 231 may be located at the center of the fiber bundle 230 and surrounded by the other fibers in the fiber bundle 230. In some embodiments, a plurality of fibers may be located at the center of the fiber bundle, and therefore these fibers may be considered collectively as the central fiber. One end of the central fiber 231 is connected to the light source 210. For example, one end of the central fiber 231 may be positioned on the light source 210 so that light emitted from the light source 210 is directed through the central fiber 231.

[0055] The fiber bundle 230 may further include N layers of fibers surrounding the central fiber 231. In the N layers of fibers, the first layer 232 of the fiber may be defined as the innermost layer of the N layers. For example, the first layer 232 may be closest to the central fiber 231 and may directly surround the central fiber 231. In the N layers of fibers, the N layer 234 of the fiber may be defined as the outermost layer of the N layers. For example, the Nth fiber layer 234 may be furthest from the central fiber 231 and may define the outer boundary of the fiber bundle 230. In the N layers of fibers, N may be 2 or more. For example, when N=2, the Nth fiber layer 234 may be the second fiber layer and may directly surround the first fiber layer 232. In another example shown in Figure 5B, when N=3, the nth fiber layer 234 may be the third fiber layer, and the second fiber layer 233 may be located between the first fiber layer 232 and the nth fiber layer 234. N may be any number greater than 2, and it can be understood that for each increasing number N, an additional layer 233 of the fiber is provided between the first layer 232 of the fiber and the nth layer 234 of the fiber.

[0056] The first fiber layer 232 may contain M fibers, where M is 4 or more. According to a particular embodiment of the present disclosure shown in Figure 5B, M=6. Each of the M fibers in the first fiber layer 232 may have one end connected to the light source 210. For example, one end of each of the M fibers in the first fiber layer 232 may be positioned on the light source 210 so that light emitted from the light source 210 can be directed through each of the M fibers in the first fiber layer 232. The nth fiber layer 234 may contain more than M fibers. For example, if N=2 and M=6, the nth fiber layer 234 may contain 12 fibers. If N=3 and M=6, as shown in Figure 5B, the nth fiber layer 234 may contain 18 fibers. Each of the M fibers in the nth fiber layer 234 may have one end connected to the light source 210. For example, one end of each of the M fibers in the Nth fiber layer 234 may be positioned on the light source 210 such that light emitted from the light source 210 can be directed through each of the M fibers in the Nth fiber layer 234.

[0057] According to embodiments of this disclosure, only the central fiber 231, M fibers in the first layer 232, and M fibers in the nth layer 234 may be connected to the light source 210. In other words, the number of fibers connected to the light source 210 for any given fiber bundle 230 may be equal to 2M+1, and therefore the remaining fibers in the nth layer 234, and all fibers in the layers between the first fiber layer 232 and the nth fiber layer 234, may not be connected to the light source 210. For example, as shown in Figure 5A, the fibers in the second fiber layer 233 may not be connected to the light source 210. While more fibers may be connected to the light source 210, it may be understood that minimizing the number of fibers connected to the light source can simplify the system and reduce computational complexity. Each fiber connected to the light source 210 may be connected to the light source 210 by a separate connector 211.

[0058] According to embodiments of the present disclosure, the N layers of fibers 234 can surround the central fiber 231 in a polygonal shape. The polygonal shape may be a regular polygon, meaning that all angles and sides of the polygon may be equal. For example, the shape of the polygon may be a triangle, a square, a pentagon, a hexagon, an octagon, or a polygon with any number of sides. The number of M fibers in the first fiber layer 232 may correspond to the number of sides of the polygonal shape. For example, if M=6, the shape of the polygon may be a hexagon. The M fibers of the Nth fiber layer 234 can correspond to the corners of the polygonal shape. For example, the N layers of fibers 234 may surround the central fiber 231 in a hexagon, and the M fibers of the N layers of fibers 234 may correspond to the corners of the hexagon.

[0059] As explained above, depending on the number of fibers, the number of fiber bundle layers N and the number of fibers increase with the first layer M, resulting in a fiber bundle 230 having several hundred fibers and N layers of fibers surrounding the central fibers 231. For example, the fiber bundle 230 may contain more than 300 fibers. Although the fiber bundle 230 may contain a large number of fibers, it should be understood that the number of fibers connected to the light source 210 depends only on the M fibers in the first layer 232. For example, if M=6, 13 fibers can be connected to the light source 210 regardless of the number of fiber layers N or the total number of fibers in the fiber bundle 230.

[0060] The apparatus 200 may further include a camera 220. The camera 220 may be configured to capture an image set. The image set may include images corresponding to each fiber connected to the light source 210. For example, images may be captured corresponding to light directed through the central fiber 231, M fibers in the first layer 232 of the fiber, and M fibers in the Nth layer 234 of the fiber. In a particular embodiment where M=6, a total of 13 images may be captured by the camera 220. Exemplary images are shown in Figure 2A.

[0061] The device 200 may further include a processor 240. The processor 240 may include a microprocessor, a microcontroller, or other devices.

[0062] The processor 240 may be coupled to components of the apparatus 200 in any suitable manner (e.g., via one or more transmission media, which may include wired and / or wireless transmission media) so that the processor 240 can receive outputs. The processor 240 may be configured to perform several functions using its outputs. A wafer inspection tool may receive instructions or other information from the processor 240. The processor 240 may optionally communicate electronically with another wafer inspection tool, wafer measurement tool, or wafer review tool (not shown) to receive additional information or send instructions.

[0063] The processor 240 communicates electronically with wafer inspection tools such as the camera 220. The processor 240 may be configured to process images generated using measurements from the camera 220. For example, the processor can perform an embodiment of method 100.

[0064] The processor 240 may be part of a variety of systems, including personal computer systems, image computers, mainframe computer systems, workstations, network appliances, internet appliances, or other devices. The subsystem or system may also include any suitable processor known in the art, such as a parallel processor. In addition, the subsystem or system may include a platform having high-speed processing and software, either as a standalone tool or a network tool.

[0065] The processor 240 may be located within or otherwise part of the device 200 or another device. In one example, the processor 240 may be part of an independent control unit or a centralized quality control unit. Multiple processors 240 may be used to define multiple subsystems of the device 200.

[0066] The processor 240 can, in practice, be implemented by any combination of hardware, software, and firmware. Furthermore, its functions as described herein may be performed by a single unit or divided among different components, each of which may be sequentially implemented by any combination of hardware, software, and firmware. Program code or instructions for the processor 240 to implement various methods and functions may be stored in a readable storage medium such as memory.

[0067] If the device 200 includes multiple subsystems, different processors 240 can be coupled to one another so that images, data, information, instructions, etc., can be transmitted between subsystems. For example, one subsystem may be coupled to an additional subsystem by any suitable transmission medium, which may include any suitable wired and / or wireless transmission medium known in the art. Two or more such subsystems may also be effectively coupled by a shared computer-readable storage medium (not shown).

[0068] The processor 240 may be configured to perform several functions using the outputs of the device 200 or other outputs. For example, the processor 240 may be configured to send its output to an electronic data storage unit or another storage medium. The processor 240 may be further configured as described herein.

[0069] The processor 240 can be part of a defect review system, inspection system, measurement system, or any other type of system. Accordingly, the embodiments disclosed herein describe several configurations that can be adapted in several ways for systems having different capabilities that are more or less suited to different applications.

[0070] The processor 240 may be configured according to any of the embodiments described herein. The processor 240 may also be configured to perform other functions or additional steps using the output of the device 200 or using images or data from other sources.

[0071] The processor 240 may be communicatively coupled to any of the various components or subsystems of the apparatus 200 in any manner known in the art. Furthermore, the processor 240 may be configured to receive and / or acquire data or information from other systems (e.g., inspection results from an inspection system such as a review tool, a remote database containing design data, etc.) via a transmission medium which may include wired and / or wireless portions. In this way, the transmission medium may act as a data link between the processor 240 and other subsystems of the apparatus 200 or systems outside of the apparatus 200. Various steps, functions, and / or operations of the apparatus 200 and methods disclosed herein are performed by one or more of the following: electronic circuits, logic gates, multiplexers, programmable logic devices, ASICs, analog or digital controls / switches, microcontrollers, or computing systems. Program instructions implementing methods such as those described herein may be transmitted via or stored on a carrier medium. The carrier medium may include storage media such as read-only memory, random-access memory, magnetic or optical disks, non-volatile memory, solid-state memory, and magnetic tape. The carrier medium may include a transmission medium such as a wire, cable, or wireless transmission link. For example, the various steps described throughout this disclosure may be performed by a single processor 240 (or computer subsystem), or alternatively, by multiple processors 240 (or multiple computer subsystems). Furthermore, different subsystems of the device 200 may include one or more computing or logical systems. Accordingly, the above description should not be construed as an limitation to this disclosure, but merely as an example.

[0072] The processor 240 may be configured to determine the centroid of each image in the image set in order to generate a centroid map. The centroid map may plot the (x,y) position of each centroid on a graph, for example, as shown in Figure 2B. The centroid of each image may be determined by image processing. For example, the processor 240 may determine the intensity of light at each pixel in each image. The processor 240 may perform filtering or smoothing operations on the image to remove noise before processing the image. If a pixel is determined to have the highest / peak intensity, the (x,y) position of this pixel may be determined as the centroid C of the image. If multiple pixels k are determined to have the highest / peak intensity, the centroid C may be determined based on the (x,y) position of each pixel k. For example, the centroid C may be determined by the following formula:

number

[0073] If multiple adjacent pixels have the highest / peak intensity, the (x,y) position of the central pixel of this group of pixels can be determined as the centroid C of the image.

[0074] The processor 240 may further be configured to generate a fiber position map, which includes the fiber positions of all fibers in the fiber bundle 230, based on the centroid map. For example, as shown in Figure 3, the fiber position map can plot the (x,y) positions of all fibers in the fiber bundle 230 based on the (x,y) position of each centroid on the graph. In Figure 3, the fiber positions from the centroid map (i.e., the positions of the central fiber 231, the M fibers in the first layer 232, and the M fibers in the Nth layer 234) are shown as solid lines, and the positions of all other fibers (i.e., the remaining fibers in the Nth layer 234, and the fibers in the layers between the first and Nth layers) are shown as dotted lines, which can be determined based on the design of the fiber bundle 230.

[0075] According to embodiments of the present disclosure, the processor 240 may be further configured to determine the pitch and rotation of the centroid of each image in the image set based on a centroid map. The pitch and rotation of the centroid of each image may correspond to the difference between the determined centroid position and the expected position of each fiber in the fiber bundle 230. For example, the pitch can be calculated based on the distance between the (x,y) position of the central fiber 231 and the fiber in the first layer 232. The rotation may be determined based on the angle of a line extending from the central fiber 231 to the fiber in the first layer 232. Naturally, the centroid position may not be exactly where expected due to mechanical tolerances of the optical components. For example, as shown in Figure 2B, the central fiber 231 has a calculated centroid at (1018, 1116), but its expected position is (1024, 1024).

[0076] The processor 240 may further be configured to determine the fiber positions of the remaining fibers in the nth fiber layer 234 within the fiber bundle 230 based on pitch and rotation. As described above, the nth fiber layer 234 may contain more than M fibers, but the centroid is determined only for the M fibers in the nth layer connected to the light source 210. For example, when N=3 and M=6, there may be 12 remaining fibers in the nth fiber layer 234. The fiber positions of these fibers can be determined based on pitch and rotation.

[0077] The processor 240 may also be configured to generate a fiber position map that includes the fiber positions of the remaining fibers in the Nth fiber layer 234 within the fiber bundle 230. For example, as shown in Figure 3, the fiber position map can plot the (x,y) positions of the remaining fibers in the Nth fiber layer 234 based on the (x,y) positions of each centroid on the graph and the fiber bundle design for N and M.

[0078] According to embodiments of the present disclosure, the processor 240 may further be configured to determine the fiber positions of all fibers between the first fiber layer 232 and the Nth fiber layer 234 in the fiber bundle 230 based on pitch and rotation. As described above, if N > 2, there may be one or more fiber layers 233 between the first fiber layer 232 and the Nth fiber layer 234. The fiber positions of these fibers 233 can be determined based on pitch and rotation.

[0079] The processor 240 may further be configured to generate a fiber position map that includes the centroid, the fiber positions of the remaining fibers in the Nth fiber layer 234 within the fiber bundle 230, and the fiber positions of all fibers between the first fiber layer 232 and the Nth fiber layer 234 within the fiber bundle 230. Thus, the fiber position map can include the positions of all fibers 231, 232, 233, and 234 within the fiber bundle 230.

[0080] According to embodiments of the present disclosure, the processor 240 may be further configured to calibrate a multibeam system based on a fiber position map. The processor 240 may be configured to overlay the fiber position map onto an image from a beam source 250 having a multibeam array. The processor 240 may be configured to align the fiber position map with the image from the beam source and determine an error. The error may include shift (x / y deflection), ROAM (rotation, orthogonality, aspect ratio, magnification), or astigmatism (shape distortion). The difference between the fiber position map and the image from the tool may be quantified as shift, ROAM, and / or astigmatism. The processor 240 may be configured to calibrate the beam source 250 by performing linear distortion correction based on the error. The apparatus 200 may also include various lenses, apertures, deflectors, or other components. Deflectors can be used to correct shift errors. Lenses can be used to correct ROAM errors or astigmatism errors.

[0081] The apparatus 200 of this disclosure can simply generate a fiber position map corresponding to the physical position of each fiber in the fiber bundle 230. The fiber position map can be used to calibrate and align a multibeam source to improve the accuracy and efficiency of the inspection process.

[0082] Although this disclosure has described one or more specific embodiments, it will be understood that other embodiments of this disclosure may be made without departing from the scope of this disclosure. Accordingly, this disclosure is deemed to be limited only by the appended claims and their reasonable interpretation.

Claims

1. A method for fiber position mapping in a multibeam system, A step that emits light from a light source and directs it towards the camera, A step of providing a fiber bundle, wherein the fiber bundle is A central fiber with one end connected to a light source, The N layers of the fiber surrounding the central fiber, wherein the first layer of the fiber is the innermost of the N layers, the Nth layer of the fiber is the outermost of the N layers, and N ≥ 2. The fiber comprises the first layer of the fiber containing M fibers, each of the M fibers in the first layer of the fiber having one end connected to a light source, the Nth layer of the fiber containing more than M fibers, and each of the M fibers in the Nth layer of the fiber having one end connected to the light source, The steps include: using a camera to capture an image set containing images corresponding to each fiber connected to the light source; To generate a centroid map using a processor, the steps include determining the centroid of each image in the image set, Using the processor, a step of generating a fiber position map that includes the fiber positions of all fibers in the fiber bundle based on the centroid map, Equipped with, The step of generating a fiber position map that includes the fiber positions of all fibers in the fiber bundle based on the centroid map is: The steps include determining the pitch and rotation of the centroid of each image in the image set based on the centroid map, The steps include determining the fiber positions of the remaining fibers in the N layers of the fiber bundle based on the pitch and rotation, The steps include generating a fiber position map that includes the centroid and fiber positions of the remaining fibers in the N layers of the fiber bundle, Includes, The N layers of the fiber surround the central fiber in a polygon, and the M fibers in the N layers correspond to the corners of the polygon. method.

2. The step of determining the centroid of each image in the image set is: The steps include determining the light intensity of each pixel in each of the images in the set of images, When it is determined that one pixel has the highest intensity among the pixels in an image, the (x, y) position of that pixel is determined to be the centroid of the image. When multiple pixels are determined to have the highest intensity among the pixels in a single image, the centroid of the image is determined based on the (x,y) position of each of the pixels with the highest intensity. The method according to claim 1, characterized by comprising the following:

3. The step of generating a fiber position map, which includes the fiber positions of all fibers in the fiber bundle, based on the centroid map, is: A step of determining the fiber position of all fibers between the first layer and the Nth layer in the fiber bundle based on the pitch and rotation, The steps of generating a fiber position map including the centroid, the fiber positions of the remaining fibers in the Nth layer of the fiber bundle, and the fiber positions of all fibers between the first layer and the Nth layer of the fiber bundle, The method according to claim 1, further comprising:

4. The method according to claim 1, characterized in that only the central fiber, the M fibers of the first layer, and the M fibers of the N layer are connected to the light source.

5. The method according to claim 1, characterized in that the N layers of the fiber surround the central fiber in a hexagon, and the M fibers of the N layers correspond to the corners of the hexagon.

6. The method according to claim 1, characterized in that the fiber bundle includes more than 300 fibers.

7. A step of calibrating the multibeam system based on the fiber position map, The method according to claim 1, further comprising:

8. The step of calibrating the multi-beam system based on the fiber position map is: The steps include receiving an image from a beam source having a multi-beam array, The steps include superimposing the fiber position map onto the image from the beam source, The error is determined by aligning the center of the fiber position map with the image from the beam source, and the error is determined by steps including shift, rotation, orthogonality, aspect ratio, magnification, or astigmatism. A step of performing linear distortion correction based on the aforementioned error, The method according to 7, characterized by comprising:

9. It is a multibeam system, A light source configured to emit light, A fiber bundle, A central fiber with one end connected to a light source, The N layers of the fiber surrounding the central fiber, wherein the first layer of the fiber is the innermost layer, the Nth layer of the fiber is the outermost layer, and N ≥ 2, The fiber comprises the first layer of the fiber containing M fibers, each of the M fibers in the first layer of the fiber having one end connected to the light source, the Nth layer of the fiber containing more than M fibers, and each of the M fibers in the Nth layer of the fiber having one end connected to the light source, A camera configured to capture an image set including images corresponding to each fiber connected to the light source, A processor that communicates electronically with the aforementioned camera, The steps include: determining the centroid of each image in the aforementioned image set and generating a centroid map; The steps include generating a fiber position map that includes the fiber positions of all fibers in the fiber bundle based on the centroid map, A processor configured to perform the following: Equipped with, The step of generating a fiber position map that includes the fiber positions of all fibers in the fiber bundle based on the centroid map is: The steps include determining the pitch and rotation of the centroid of each image in the image set based on the centroid map, The steps include determining the fiber positions of the remaining fibers in the N layers of the fiber bundle based on the pitch and rotation, The steps include generating a fiber position map that includes the centroid and fiber positions of the remaining fibers in the N layers of the fiber bundle, Includes, The N layers of the fiber surround the central fiber in a polygon, and the M fibers in the N layers correspond to the corners of the polygon. Multibeam system.

10. The aforementioned processor, The steps include determining the light intensity of each pixel in each image within the aforementioned image set, When it is determined that one pixel has the highest intensity among the pixels in an image, the (x, y) position of that pixel is determined to be the centroid of the image. When it is determined that multiple pixels have the highest intensity among the pixels in a single image, the centroid of the image is determined based on the (x,y) position of each of the pixels with the highest intensity, The system according to claim 9, characterized in that it is configured to determine the centroid of each image in the image set.

11. The aforementioned processor, A step of determining the fiber position of all fibers between the first layer and the Nth layer in the fiber bundle based on the pitch and rotation, The steps of generating a fiber position map including the centroid, the fiber positions of the remaining fibers in the Nth layer of the fiber bundle, and the fiber positions of all fibers between the first and Nth layers of the fiber bundle, The system according to claim 9, characterized in that it is configured to generate a fiber position map, which includes the fiber positions of all fibers in the fiber bundle, based on the centroid map.

12. The system according to claim 9, characterized in that only the central fiber, the M fibers in the first layer of the fiber, and the M fibers in the N layers of the fiber are connected to the light source.

13. The system according to claim 9, characterized in that the N layers of the fiber surround the central fiber in a hexagon, and the M fibers of the N layers correspond to the corners of the hexagon.

14. The system according to claim 9, characterized in that the fiber bundle includes more than 300 fibers.

15. The aforementioned processor, A step of calibrating a multibeam system based on a fiber position map, The system according to claim 9, further configured to perform the following:

16. The aforementioned processor, The steps include receiving an image from a beam source having a multi-beam array, The steps include superimposing the fiber position map onto the image from the beam source, The error is determined by aligning the center of the fiber position map with the image from the beam source, and the error is determined by steps including shift, rotation, orthogonality, aspect ratio, magnification, or astigmatism. A step of performing linear distortion correction based on the aforementioned error, The system according to claim 15, characterized in that it is configured to calibrate the multibeam system based on the fiber position map.

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