Inspection device, inspection method, and program

Abstract

To provide an inspection device and the like that can inspect a repetitive structure of a workpiece by imaging a visual field direction of a line sensor at an approximately integer ratio without changing the magnification of an imaging system.SOLUTION: An inspection device 1 that inspects a workpiece 2 having a repetitive structure includes: a stage 10; a line sensor 20 whose visual field direction is the first direction and which images the workpiece 2 set on the stage 10; and a calculation unit 51 that calculates an imaging condition of the workpiece 2. The calculation unit 51 calculates Ry and θ with Rx (resolution of imaging in the first direction), Ta (period of one repetition of the repetitive structure), and Tb (period of another repetition of the repetitive structure) as input parameters. The inspection device 1 images the workpiece 2 by rotating the workpiece 2 so as to have an angle of θ, and scanning the line sensor 20 in a state where the workpiece 2 is tilted.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to an inspection device, an inspection method, and a program for inspecting a workpiece having a repetitive structure. [Background technology]

[0002] There is a known technique for inspecting defects in a workpiece having a repeating structure (repeated pattern). For example, a substrate of a display device such as a liquid crystal display panel or an organic EL panel, a solar cell, or an imaging device has a plurality of transistors or the like provided as a repeating structure in two orthogonal directions.

[0003] A conventional method for inspecting defects in a workpiece having such a repeating structure is to place the workpiece having the repeating structure on a stage as an object to be inspected, scan the object with a line sensor (camera) to capture an image of the object, and process the captured image to inspect for defects in the repeating structure. In this case, a comparison inspection is performed in which a comparison source pixel in the image of the object to be inspected is compared with a comparison target pixel located at a position separated by the repeating pitch, thereby making it possible to detect parts of the image that do not satisfy the periodicity of the repeating structure.

[0004] However, the repetition pitch of the repetitive structure in the inspection object and the imaging resolution of the line sensor do not necessarily have an integer ratio (integer multiple). In this case, it becomes impossible to compare the pixels of the repetitive structure of the comparison source with the correct pixels of the repetitive structure of the comparison target, which reduces the accuracy of the inspection.

[0005] Therefore, in an inspection method in which defects in the repeating structure of an object are inspected by capturing an image of the object with a camera through a lens, a technology has been proposed in which the lens is equipped with a zoom mechanism to adjust the magnification to suit the object (Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4165115 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the inspection method disclosed in Patent Document 1 has a problem in that the magnification of the lens can only be adjusted in the line sensor's field of view (direction perpendicular to the scanning direction).

[0008] The present disclosure aims to solve such problems and to provide an inspection device and an inspection method that can inspect the repetitive structure of a workpiece by capturing images in the field of view of the line sensor at approximately an integer ratio without changing the magnification of the imaging system. [Means for solving the problem]

[0009] In order to achieve the above object, one aspect of the inspection device according to the present disclosure is an inspection device for inspecting a workpiece having a repeating structure that is repeatedly provided in each of two orthogonal directions, the inspection device comprising: a stage; a line sensor having a field of view direction of a first direction and configured to capture an image of the workpiece set on the stage; a rotation drive mechanism that rotates the workpiece so as to form a predetermined angle with a second direction orthogonal to the first direction; and a calculation unit that calculates imaging conditions for the workpiece, wherein the imaging resolution of the inspection device in the first direction is defined as Rx, the imaging resolution of the inspection device in the second direction is defined as Ry, and If a fixed angle is θ, the repetition period of the repeating structure in one of the two orthogonal directions in the work is Ta, and the repetition period of the repeating structure in the other of the two orthogonal directions in the work is Tb, the calculation unit uses Rx, Ta, and Tb as input parameters to calculate Ry and θ as the imaging conditions, and the inspection device rotates the work using the rotation drive mechanism so that the angle is the θ calculated by the calculation unit, and scans the line sensor with the work tilted, thereby imaging the work.

[0010] Furthermore, one aspect of the inspection method according to the present disclosure is an inspection method for inspecting a workpiece having a repeating structure provided repeatedly in each of two orthogonal directions, the inspection method including: a calculation step of calculating predetermined imaging conditions; a rotation step of rotating and tilting the workpiece so as to form a predetermined angle with a second direction orthogonal to a first direction based on the imaging conditions; an imaging step of imaging the workpiece by scanning a line sensor whose viewing direction is the first direction in the second direction; and an inspection step of inspecting the repeating structure of the workpiece based on the image of the workpiece captured by the line sensor, wherein the resolution of imaging in the first direction is is Rx, the imaging resolution in the second direction is Ry, the predetermined angle is θ, the repetition period of the repeating structure in one of the two orthogonal directions in the work is Ta, and the repetition period of the repeating structure in the other of the two orthogonal directions in the work is Tb. In the calculation process, Rx, Ta, and Tb are used as input parameters, and Ry and θ are calculated as the imaging conditions. In the imaging process, the work is imaged by scanning the line sensor while tilting the work at the angle θ calculated in the calculation process.

[0011] Furthermore, one aspect of a program according to the present disclosure is a program used in an inspection method for inspecting a workpiece having a repeating structure provided repeatedly in each of two orthogonal directions, the inspection method including: a calculation step of calculating predetermined imaging conditions; a rotation step of rotating and tilting the workpiece so as to form a predetermined angle with a second direction orthogonal to a first direction based on the imaging conditions; an imaging step of scanning a line sensor whose viewing direction is the first direction in the second direction to image the workpiece; and an inspection step of inspecting the repeating structure of the workpiece based on the image of the workpiece imaged by the line sensor, wherein the resolution of the imaging in the first direction is Rx, and the resolution of the imaging in the second direction is Rx. If the imaging resolution in the direction is Ry, the specified angle is θ, the repetition period of the repeating structure in one of the two orthogonal directions in the work is Ta, and the repetition period of the repeating structure in the other of the two orthogonal directions in the work is Tb, in the calculation process, Rx, Ta, and Tb are used as input parameters and Ry and θ are calculated as the imaging conditions, and in the imaging process, the work is imaged by scanning the line sensor while tilting the work at the angle θ calculated in the calculation process, and the program is a program for causing a processor to execute the calculation process. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to inspect the repetitive structure of a workpiece by capturing images in the field of view of the line sensor at approximately an integer ratio without changing the magnification of the imaging system. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing the configuration of an inspection device for inspecting a workpiece having a repetitive structure. [Figure 2] FIG. 10 is a diagram for explaining the repeat pitch of the repeating structure of the workpiece. [Figure 3] FIG. 10 is a diagram showing an example of a residual error when image processing is performed on an image captured when determining defects in a repetitive structure of a workpiece without tilting the workpiece. [Figure 4] 1A to 1C are diagrams for explaining the principle of inspecting a workpiece using an inspection device according to an embodiment. [Figure 5] 10A and 10B are diagrams for explaining the repeat pitch of the repeating structure of the workpiece when the workpiece is tilted. [Figure 6] FIG. 10 is a diagram showing an example of a residual error when an image captured when tilting a workpiece to determine defects in a repetitive structure of the workpiece is subjected to image processing. [Figure 7] 1 is a diagram showing a configuration of an inspection device according to an embodiment; [Figure 8] FIG. 1 is a block diagram of an inspection device according to an embodiment. [Figure 9] FIG. 1 is a flow diagram of an inspection method according to an embodiment. [Figure 10] 10A and 10B are diagrams showing simulation results when the inspection method according to the embodiment is performed in combination with a scan ARS. [Figure 11] 10A and 10B are diagrams showing simulation results when the inspection method according to the embodiment is performed without using a scan ARS. [Figure 12] 10A and 10B are diagrams showing simulation results when an area sensor is used instead of a line sensor to perform an inspection method according to an embodiment. [Figure 13] FIG. 13 is a diagram showing numerical values ​​of the simulation results of FIGS. 10 to 12. DETAILED DESCRIPTION OF THE INVENTION

[0014] (How one aspect of the present disclosure was achieved) Before describing embodiments of the present disclosure, the process by which one aspect of the present disclosure was achieved will be described.

[0015] First, a conventional inspection method for inspecting defects in a workpiece 2 having a repeating structure will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram showing the configuration of an inspection apparatus 1X for inspecting a workpiece 2 having a repeating structure. FIG. 2 is a diagram for explaining the repetition pitch of the repeating structure of the workpiece 2, and shows a schematic enlarged view of an area A surrounded by a dashed line in the workpiece 2 in FIG. 1. In this specification and drawings, the X-axis, Y-axis, and Z-axis represent the three axes of a three-dimensional Cartesian coordinate system. The X-axis and Y-axis are orthogonal to each other and are both orthogonal to the Z-axis. In this embodiment, the Z-axis direction is the vertical direction.

[0016] As shown in Fig. 1, the inspection device 1X includes a stage 10 on which a workpiece 2 is placed, and a line sensor 20 for capturing an image of the workpiece 2. In the inspection device 1X, the field of view of the line sensor 20 is the X-axis direction. Therefore, the imaging area 20a of the line sensor 20 for one image capture extends in the X-axis direction. The scanning direction of the line sensor 20 is the Y-axis direction.

[0017] In Figure 2, black dots indicate the positions of the repeating structures of the workpiece 2. As shown in Figure 2, the repeating structures of the workpiece 2 are repeated at a certain period (pitch) in each of two orthogonal directions, the a direction and the b direction. The a direction is one of the two orthogonal directions, and the b direction is the other of the two orthogonal directions. The repeating structures of the workpiece 2 are provided repeatedly in the a direction and the b direction, with the repeating period (repeat pitch) in the a direction being Ta and the repeating period (repeat pitch) in the b direction being Tb.

[0018] When inspecting a workpiece 2 having such a repeating structure using the inspection device 1X, first, the workpiece 2 to be inspected is set on the stage 10 as shown in Fig. 1. At this time, as shown in Fig. 2, the workpiece 2 is set so that the a direction of the repeating structure coincides with the X-axis direction and the b direction coincides with the Y-axis direction. In other words, the workpiece 2 is set on the stage 10 so that the multiple repeating structures are repeated along both the X-axis direction and the Y-axis direction. Therefore, the workpiece 2 is set so that the repeating direction of the multiple repeating structures coincides with the field of view direction and scanning direction of the line sensor 20.

[0019] When inspecting the repeating structure of the workpiece 2, the line sensor 20 scans the workpiece 2 set on the stage 10 in the scanning direction (Y-axis direction) to capture an image of the entire workpiece 2, and the presence or absence of defects in the repeating structure of the workpiece 2 is determined based on the captured image. In other words, the presence or absence of defects in the repeating structure of the workpiece 2 is determined by performing image processing based on the captured image.

[0020] Specifically, in an image of the workpiece 2 captured by the line sensor 20, a comparison inspection is performed to compare the density of pixels in the reference repeating structure with the density of pixels in a target repeating structure located at a distance equal to an integer multiple of the repeat pitch, thereby determining a portion that does not satisfy the periodicity of the repeating structure as a defect. For example, the difference between the density of pixels in the reference repeating structure and the density of pixels in a target repeating structure located at a distance equal to an integer multiple of the repeat pitch of the repeating structure is calculated, and if the density value of this difference is equal to or greater than a predetermined first threshold or equal to or less than a predetermined second threshold, the portion that does not satisfy the periodicity of the repeating structure is determined to be a defect. An example of this type of image processing is described below.

[0021] If the vectors of the two actual repeating structures to be compared in work 2 are (Xa, Ya) and the vectors of the two repeating structures on the image captured by line sensor 20 are (Xp, Yp), then (Xa, Ya) can be expressed by the following (Equation 1).

[0022] (Xa,Ya)=(Cx×Xp,Cy×Yp) (Formula 1)

[0023] In addition, in (Equation 1), Cx=0, ±1, ±2, . . . and Cy=0, ±1, ±2, .

[0024] Here, (Xa, Ya) is a vector indicating the distance between the repeating structure P1 of the comparison source and the repeating structure P1 of the comparison target in the two actual repeating structures, and (Xp, Yp) is a vector indicating the distance between the repeating structure P1 of the comparison source and the repeating structure P1 of the comparison target in the two repeating structures on the image captured by the line sensor 20.

[0025] 2 shows the repeating structure P1 and the repeating structure P2 when Cx = 1 and Cy = 1 in (Equation 1). That is, in Fig. 2, the repeating structure P2 to be compared is located at a position one pitch away from the repeating structure P1 to be compared in the directions a and b.

[0026] In this case, if the imaging resolution of the line sensor 20 in the X-axis direction is Rx and the imaging resolution of the line sensor 20 in the Y-axis direction is Ry, the vector (Xp, Yp) indicating the distance between the repeating structure P1 and the repeating structure P2 on the image captured by the line sensor 20 is expressed in units of "pixels" by the following (Equation 2).

[0027] (Xp,Yp)=(Ta / Rx,Tb / Ry) (Formula 2)

[0028] In this case, image processing for defect detection is performed in pixel units, so errors will remain if (Xp, Yp) are not integers. For example, if the target repeat periods (repetition pitch) Ta and Tb are Ta = 1232 μm and Tb = 987 μm, and the imaging resolutions Rx and Ry of the line sensor 20 are Rx = 5 μm / pix and Ry = 5 μm / pix, and the remaining error is calculated within the range of ±1 for Cx and Cy, the maximum remaining error (worst value) is 0.400 pixels, as shown in Figure 3. In other words, the repetition pitch of the repeating structure in the workpiece 2 and the imaging resolution of the line sensor 20 do not have an integer ratio.

[0029] In this way, the repetition pitch of the repetitive structure in the workpiece 2 and the imaging resolution of the line sensor 20 do not necessarily have an integer ratio. In this case, the number of pixels from the pixel of the repeating structure P1 of the comparison source to the pixel of the repeating structure P2 of the comparison target on the image of the workpiece 2 does not become an integer, making it impossible to compare the pixels of the repeating structure P1 of the comparison source with the correct pixels of the repeating structure P2 of the comparison target, and reducing the accuracy of the inspection.

[0030] Therefore, as in the method disclosed in Patent Document 1, a method can be considered in which the number of pixels from the pixel of the repeating structure P1 to the pixel of the repeating structure P2 to be compared is made an integer by using a lens to change the magnification of the imaging system in the image of the workpiece 2.

[0031] However, with this method, the magnification can only be adjusted in the field of view direction of the line sensor 20 (the direction perpendicular to the scanning direction: the X-axis direction in FIG. 1). Furthermore, this method requires a mechanical drive unit for zooming the lens, which results in poor reproducibility of the operation when adjusting the lens magnification, and low lens adjustment accuracy. Furthermore, using a mechanical drive unit for zooming the lens increases the size of the inspection device.

[0032] As a result of extensive research into this issue, the inventors of the present application have come to the conclusion that by tilting the workpiece 2, it may be possible to capture an image so that the above-mentioned Xp becomes an integer.

[0033] Specifically, as shown in Fig. 4, the workpiece 2 was rotated at an angle θ to tilt the workpiece 2. Fig. 4 is a diagram showing the state when the workpiece 2 is inspected in a tilted state. Fig. 5 is a schematic enlarged view of an area A surrounded by a dashed line in the workpiece 2 in Fig. 4.

[0034] By tilting the workpiece 2 at an angle of θ, the a-direction and b-direction, which are the repeating directions of the workpiece 2, also tilt at an angle of θ, as shown in Figure 5. Specifically, the angle between the b-direction and the Y-axis direction is θ.

[0035] For this reason, when the workpiece 2 is tilted and imaged with the line sensor 20, the repetition pitch of the repeating structure in the viewing direction (X-axis direction) of the line sensor 20 is effectively smaller in the imaged image, and the repetition pitch of the repeating structure in the scanning direction (Y-axis direction) of the line sensor 20 is effectively larger in the imaged image. As a result, the workpiece 2 can be imaged so that the number of pixels from the pixel of the repeating structure P1 to the pixel of the repeating structure P2 to be compared is as close to an integer as possible. This point will be explained below.

[0036] In an image captured while rotating the workpiece 2, the vectors also rotate. Therefore, when the vectors (Xa, Ya) of the two repeating structures being compared, shown in (Equation 1), are rotated by an angle of θ, the vectors (Xn, Yn) are expressed by the following (Equation 3).

[0037] (Xn,Yn)=(Xa×cosθ-Ya×sinθ,Xa×sinθ+Ya×cosθ) (Formula 3)

[0038] Then, based on (Equation 2) and (Equation 3), we tried to select θ and Ry so that the vectors (Xp, Yp) of the two repeating structures on the image captured by the line sensor 20 would be integers as much as possible, and found that we could reduce the above error. Note that the resolution Rx in the X-axis direction is an eigenvalue of the inspection device (line sensor 20), and Ta and Tb are eigenvalues ​​of the workpiece 2, so there is no freedom in selecting Rx, Ta, and Tb. On the other hand, when considering the scan ARS described below, there is freedom in selecting Ry. For this reason, we searched for θ and Ry.

[0039] Specifically, as described above, when the target repeat periods (repetition pitch) Ta and Tb are set to Ta = 1232 μm and Tb = 987 μm, and the imaging resolution Rx of the line sensor 20 is set to Rx = 5 μm / pix, θ and Ry are selected to be θ = 3.195° and Ry = 4.903 μm / pix, and the remaining error is calculated when Cx and Cy are within the range of ±1, the maximum value (worst value) of the remaining error can be reduced to 0.019 pixels, as shown in Figure 6. In other words, the repetition pitch of the repeating structure in the workpiece 2 and the imaging resolution of the line sensor 20 can be roughly made into an integer ratio.

[0040] In this way, the inventor of the present application discovered that by tilting the workpiece 2, the field of view direction (X-axis direction) of the line sensor 20 can be imaged at approximately an integer ratio, and thus arrived at one aspect of the inspection device and inspection method disclosed herein.

[0041] Specifically, one aspect of the inspection device according to the present disclosure is an inspection device for inspecting a workpiece having a repeating structure provided repeatedly in each of two orthogonal directions, the inspection device comprising: a stage; a line sensor having a field of view in a first direction and configured to capture an image of the workpiece set on the stage; a rotation drive mechanism for rotating the workpiece so as to form a predetermined angle with a second direction orthogonal to the first direction; and a calculation unit for calculating imaging conditions for the workpiece, wherein the imaging resolution in the first direction in the inspection device is defined as Rx, the imaging resolution in the second direction in the inspection device is defined as Ry, and the predetermined angle is defined as Ry. If the angle of repetition of the repeating structure in one of the two orthogonal directions in the workpiece is θ, the repetition period of the repeating structure in one of the two orthogonal directions in the workpiece is Ta, and the repetition period of the repeating structure in the other of the two orthogonal directions in the workpiece is Tb, the calculation unit uses Rx, Ta, and Tb as input parameters to calculate Ry and θ as the imaging conditions, and the inspection device rotates the workpiece using the rotation drive mechanism to the angle of θ calculated by the calculation unit, and scans the line sensor while the workpiece is tilted, thereby imaging the workpiece.

[0042] This configuration allows the line sensor to capture images at roughly an integer ratio in the field of view without changing the magnification of the imaging system, thereby enabling accurate inspection of repetitive structures on the workpiece.

[0043] In this case, in one aspect of the inspection device according to the present disclosure, the inspection device may inspect defects in the workpiece by comparing the pixels of the two repeating structures in an image of the workpiece obtained by scanning the line sensor.

[0044] With this configuration, the workpiece can be scanned with the line sensor to capture an image of the workpiece, and the pixels of the two repeating structures in the captured image can be compared to inspect the workpiece for defects.

[0045] Furthermore, in one aspect of the inspection device according to the present disclosure, if the vectors of the two repeating structures before the workpiece is tilted at an angle of θ are (Xa, Ya), the vectors of the two repeating structures after the workpiece is tilted at an angle of θ are (Xn, Yn), and the vectors of the two repeating structures on the captured image are (Xp, Yp), Xp and Yp are expressed by the following equations: Xp = Xn / Rx = (Xa × cos θ - Ya × sin θ) / Rx, Yp = Yn / Ry = (Xa × sin θ + Ya × cos θ) / Ry, The calculation unit may calculate θ and Ry so that Xp and Yp are integers.

[0046] In this way, by calculating θ and Ry so that Xp and Yp are integers, it is possible to capture images in the field of view of the line sensor at an integer ratio.

[0047] Furthermore, in one aspect of the inspection device according to the present disclosure, the calculation unit may calculate Ry and θ by changing Ry so that Yp has an integer period on the captured image.

[0048] This allows the line sensor to capture images not only in the field of view direction at an approximate integer ratio, but also in the scanning direction of the line sensor at an approximate integer ratio, thereby enabling the repetitive structure of the workpiece to be inspected with even greater precision.

[0049] Furthermore, one aspect of the inspection method according to the present disclosure is an inspection method for inspecting a workpiece having a repeating structure provided repeatedly in each of two orthogonal directions, the inspection method including: a calculation step of calculating predetermined imaging conditions; a rotation step of rotating and tilting the workpiece so as to form a predetermined angle with a second direction orthogonal to a first direction based on the imaging conditions; an imaging step of imaging the workpiece by scanning a line sensor whose viewing direction is the first direction in the second direction; and an inspection step of inspecting the repeating structure of the workpiece based on the image of the workpiece captured by the line sensor, wherein the resolution of imaging in the first direction is is Rx, the imaging resolution in the second direction is Ry, the predetermined angle is θ, the repetition period of the repeating structure in one of the two orthogonal directions in the work is Ta, and the repetition period of the repeating structure in the other of the two orthogonal directions in the work is Tb. In the calculation process, Rx, Ta, and Tb are used as input parameters, and Ry and θ are calculated as the imaging conditions. In the imaging process, the work is imaged by scanning the line sensor while tilting the work at the angle θ calculated in the calculation process.

[0050] This allows the line sensor to capture images in the field of view at approximately an integer ratio without changing the magnification of the imaging system, thereby enabling the repetitive structure of the workpiece to be inspected with high precision.

[0051] In this case, in one aspect of the inspection method according to the present disclosure, the inspection step may inspect the workpiece for defects by comparing pixels of the two repeating structures in a captured image of the workpiece.

[0052] This allows the workpiece to be scanned with the line sensor to capture an image, and then the pixels of the two repeating structures in the captured image can be compared to inspect the workpiece for defects.

[0053] Furthermore, in one aspect of the inspection method according to the present disclosure, if the vectors of the two repeating structures before the workpiece is tilted at an angle of θ are (Xa, Ya), the vectors of the two repeating structures after the workpiece is tilted at an angle of θ are (Xn, Yn), and the vectors of the two repeating structures on the captured image are (Xp, Yp), Xp and Yp are expressed by the following equations: Xp = Xn / Rx = (Xa × cos θ - Ya × sin θ) / Rx, Yp = Yn / Ry = (Xa × sin θ + Ya × cos θ) / Ry, and in the calculation step, θ and Ry are preferably calculated so that Xp and Yp are integers.

[0054] In this way, by calculating θ and Ry so that Xp and Yp are integers, it is possible to capture images in the field of view of the line sensor at an integer ratio.

[0055] Furthermore, in one aspect of the inspection method according to the present disclosure, in the calculation step, Ry and θ may be calculated by changing Ry so that Tb has an integer period on the captured image.

[0056] This allows the line sensor to capture images not only in the field of view direction at an approximate integer ratio, but also in the scanning direction of the line sensor at an approximate integer ratio, thereby enabling the repetitive structure of the workpiece to be inspected with even greater precision.

[0057] Furthermore, the technology of the present disclosure can also be used as a program. Specifically, one aspect of the program according to the present disclosure is a program used in an inspection method for inspecting a workpiece having a repeating structure provided repeatedly in each of two orthogonal directions, the inspection method including a calculation step of calculating predetermined imaging conditions, a rotation step of rotating and tilting the workpiece based on the imaging conditions so as to form a predetermined angle with a second direction orthogonal to a first direction, an imaging step of imaging the workpiece by scanning a line sensor whose viewing direction is the first direction in the second direction, and an inspection step of inspecting the repeating structure of the workpiece based on the image of the workpiece imaged by the line sensor, wherein the resolution of the imaging in the first direction is Rx, If the resolution of imaging in two directions is Ry, the specified angle is θ, the repetition period of the repeating structure in one of the two orthogonal directions in the work is Ta, and the repetition period of the repeating structure in the other of the two orthogonal directions in the work is Tb, in the calculation process, Rx, Ta, and Tb are used as input parameters and Ry and θ are calculated as the imaging conditions, and in the imaging process, the work is imaged by scanning the line sensor while tilting the work at the angle θ calculated in the calculation process, and the program is a program for causing a processor to execute the calculation process.

[0058] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the superordinate concept of the present disclosure will be described as optional components.

[0059] Note that each figure is a schematic diagram and is not necessarily a precise illustration. Furthermore, in each figure, substantially the same configuration is assigned the same reference numeral, and duplicate explanations are omitted or simplified. Furthermore, in this specification, the terms "up" and "down" do not necessarily refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition.

[0060] (Embodiment) First, the configuration of an inspection device 1 according to an embodiment of the present disclosure will be described using Fig. 7 and Fig. 8, while also referring to Fig. 4 and Fig. 5. Fig. 7 is a diagram showing the configuration of the inspection device 1 according to the embodiment. Fig. 8 is a block diagram of the inspection device 1 according to the embodiment.

[0061] The inspection device 1 is an inspection device that inspects a workpiece 2 having a repeating structure provided repeatedly in each of two orthogonal directions.

[0062] The workpiece 2 is an object to be inspected (inspection target) by the inspection device 1. As shown in FIG. 5, the repeating structure of the workpiece 2 is repeated at a certain period (pitch) in each of two orthogonal directions, the a direction and the b direction. The a direction is one of the two orthogonal directions, and the b direction is the other of the two orthogonal directions. The repeating structure of the workpiece 2 is provided repeatedly in the a direction and the b direction, with the repeating period (repeat pitch) in the a direction being Ta and the repeating period (repeat pitch) in the b direction being Tb.

[0063] The workpiece 2 is, for example, a substrate in a liquid crystal display panel or the like. In this case, a plurality of transistors and the like are provided on the substrate, which is the workpiece 2, as a repeating structure (repeated pattern) that is repeatedly provided in each of two orthogonal directions. The plurality of transistors are repeatedly provided at a constant pitch (period) along each of the row direction (direction b) and column direction (direction a).

[0064] As shown in FIGS. 7 and 8, the inspection device 1 includes a stage 10, a line sensor 20, a rotary drive mechanism 30, a linear drive mechanism 40, and a processing device 50.

[0065] The stage 10 is a platform on which the workpiece 2, which is the object to be inspected, is placed. The stage 10 has a planar placement surface on which the workpiece 2 is placed. This placement surface is parallel to the XY plane. The stage 10 may be configured so that it can move independently in each of the X-axis direction, the Y-axis direction, and the Z-axis direction.

[0066] The line sensor 20 is a camera that captures an image of the workpiece 2 set on the stage 10. In this embodiment, the first direction, which is the field of view of the line sensor 20, is the X-axis direction. The imaging area 20a of the line sensor 20 at one time is an area that extends in a linear band along the X-axis direction. The scanning direction of the line sensor 20 is the Y-axis direction.

[0067] The rotation drive mechanism 30 has a drive device that rotates the workpiece 2 so that it forms a predetermined angle with a second direction that is perpendicular to a first direction, which is the field of view of the line sensor 20. In this embodiment, the field of view (first direction) of the line sensor 20 is the X-axis direction, and therefore the second direction that is perpendicular to the first direction is the Y-axis direction. Therefore, the rotation drive mechanism 30 rotates the workpiece 2 so that it forms a predetermined angle with the Y-axis direction.

[0068] Specifically, the rotation drive mechanism 30 has a drive device that rotates the stage 10 so that it forms a predetermined angle with the Y-axis direction. In other words, by rotating the stage 10 with the rotation drive mechanism 30, the workpiece 2 set on the stage 10 rotates and tilts at a predetermined angle with respect to the Y-axis direction.

[0069] 4 and 5, when the stage 10 is rotated by the rotation drive mechanism 30 so that the angle it forms with the Y-axis direction is θ, the workpiece 2 is tilted at an angle θ with respect to the Y-axis direction. In other words, in the repeating structure of the workpiece 2, the angle formed between the b-direction (the direction repeated at a repeat pitch of period Tb) and the Y-axis direction is angle θ.

[0070] In this embodiment, the workpiece 2 is tilted by rotating the stage 10, but this is not limiting. For example, the workpiece 2 may be tilted without rotating the stage 10. In this case, the rotation drive mechanism 30 has a drive device that rotates only the workpiece 2 mounted on the stage 10.

[0071] The linear drive mechanism 40 is a drive device that scans the line sensor 20 along a second direction (scanning direction) that is perpendicular to the first direction, which is the field of view of the line sensor 20. The linear drive mechanism 40 is composed of, for example, a scanning axis that supports the line sensor 20 and moves in the scanning direction, and a linear encoder that detects the position of the scanning axis. The linear encoder outputs a signal each time the scanning axis moves a certain distance. This makes it possible to determine the position of the line sensor 20 supported by the scanning axis (i.e., the distance that the line sensor 20 has moved in the scanning direction).

[0072] The processing device 50 has a calculation unit 51, a drive control unit 52, and an image processing unit 53. The processing device 50 may have a storage unit such as a memory. The processing device 50 may be a terminal device installed near the stage 10, or may be a remote device such as a server.

[0073] The calculation unit 51 calculates in advance the imaging conditions for the workpiece 2 when inspecting the workpiece 2. Specifically, assuming that the imaging resolution in the first direction in the inspection device 1 (in this embodiment, the imaging resolution in the field of view of the line sensor 20) is Rx, the imaging resolution in the second direction in the inspection device 1 (in this embodiment, the imaging resolution in the scanning direction of the line sensor 20) is Ry, the predetermined angle when the workpiece 2 is tilted is θ, the repetition period of the repeating structure in one of the two orthogonal directions in the workpiece 2 (in this embodiment, the a direction) is Ta, and the repetition period of the repeating structure in the other of the two orthogonal directions in the workpiece 2 (in this embodiment, the b direction) is Tb, the calculation unit 51 uses Rx, Ta, and Tb as input parameters and calculates Ry and θ as imaging conditions.

[0074] In this embodiment, the calculation unit 51 calculates Ry and θ by changing Ry so that the repeating period Tb of the repeating structure becomes an integer period on the captured image. That is, the calculation unit 51 calculates Ry and θ by changing the resolution Ry, which is the imaging resolution in the scanning direction (scanning direction) of the line sensor 20. This method is called a scan ARS (Adaptive Resolution System) and is disclosed in Japanese Patent No. 5417997.

[0075] The drive control unit 52 drives the rotation drive mechanism 30 in accordance with θ calculated by the calculation unit 51. Specifically, before capturing an image of the workpiece 2, the rotation drive mechanism 30 rotates the stage 10 in accordance with the angle θ transmitted from the drive control unit 52 to tilt the workpiece 2. The drive control unit 52 also drives the linear drive mechanism 40 to scan the line sensor 20. In other words, the line sensor 20 is scanned by the drive control unit 52 to capture an image of the workpiece 2.

[0076] The image processing unit 53 performs image processing on the image captured by the line sensor 20 to determine whether or not there is a defect in the repeating structure of the workpiece 2. At this time, the image processing unit 53 determines whether or not there is a defect in the repeating structure of the workpiece 2 based on the resolution Rx and the resolution Ry calculated by the calculation unit 51. Specifically, in the image of the workpiece 2 captured by the line sensor 20, a comparison inspection is performed to compare the density of pixels of a reference repeating structure with the density of pixels of a target repeating structure located at a distance equal to an integer multiple of the repeat pitch, thereby determining a portion that does not satisfy the periodicity of the repeating structure as a defect. For example, the difference between the density of pixels of the reference repeating structure and the density of pixels of a target repeating structure located at a distance equal to an integer multiple of the repeat pitch of the repeating structure is calculated, and if the density value of the difference is equal to or greater than a predetermined first threshold or equal to or less than a predetermined second threshold, the portion that does not satisfy the periodicity of the repeating structure is determined to be a defect.

[0077] The calculation unit 51, the drive control unit 52, and the image processing unit 53 are configured, for example, by a processor or a circuit. In this case, the calculation unit 51, the drive control unit 52, and the image processing unit 53 may be configured by separate processors or circuits, or may be configured as a single processor or circuit as a whole. Furthermore, the processing device 50 having the calculation unit 51, the drive control unit 52, and the image processing unit 53 may be configured by an information processing device such as a computer. In this case, the processing described as the operation of the processing device 50, such as the calculation unit 51, is executed by the computer. For example, the computer can execute each of the above processes by executing a program using hardware resources such as a processor (CPU), memory, and input / output circuits. The results of each process may be stored in a memory (not shown) in the processing device 50.

[0078] Next, an inspection method for the workpiece 2 using the inspection device 1 will be described with reference to Fig. 4 and Fig. 5 and with reference to Fig. 9. Fig. 9 is a flow chart of the inspection method according to the embodiment.

[0079] As shown in Figure 9, the inspection method of this embodiment is an inspection method for inspecting a workpiece 2 having a repeating structure that is repeated in each of two orthogonal directions, and includes a calculation process S1, a rotation process S2, an imaging process S3, and an inspection process S4.

[0080] The calculation step S1 is a step in which predetermined imaging conditions are calculated by the calculation unit 51. In other words, the calculation step S1 is an imaging condition calculation step in which imaging conditions are calculated in advance before the workpiece 2 is imaged by the line sensor 20. In this embodiment, the workpiece 2 is tilted with respect to the scanning direction of the line sensor 20 by rotating the workpiece 2, so in the calculation step S1, imaging conditions including angle θ as the rotation angle by which the workpiece 2 is rotated are calculated.

[0081] Specifically, if the imaging resolution in the field of view of the line sensor 20 is Rx, the imaging resolution in the scanning direction of the line sensor 20 is Ry, the predetermined angle when the workpiece 2 is tilted is θ, the repetition period in the a direction of the repeating structure of the workpiece 2 is Ta, and the repetition period in the b direction of the repeating structure of the workpiece 2 is Tb, then in the calculation step S1, Rx, Ta, and Tb are used as input parameters, and Ry and θ are calculated as imaging conditions.

[0082] More specifically, Ry and θ are calculated as follows. In this embodiment, the workpiece 2 is imaged while tilted with respect to the scanning direction of the line sensor 20. Therefore, if the vectors of the two repeating structures before the workpiece 2 is tilted at an angle of θ are (Xa, Ya), the vectors of the two repeating structures after the workpiece 2 is tilted at an angle of θ are (Xn, Yn), and the vectors of the two repeating structures on the image captured by the line sensor 20 are (Xp, Yp), then in the calculation step S1, θ and Ry are calculated so that Xp and Yp are integers. That is, a combination of θ and Ry is searched for such that Xp and Yp are integers. Note that Xp and Yp are expressed by the following (Equation 4) and (Equation 5).

[0083] Xp=Xn / Rx=(Xa×cosθ-Ya×sinθ) / Rx (Formula 4)

[0084] Yp=Yn / Ry=(Xa×sinθ+Ya×cosθ) / Ry (Formula 5)

[0085] In this embodiment, Ry and θ are calculated by the scan ARS as described above. That is, in the calculation step S1, Ry and θ are calculated by changing the resolution Ry, which is the imaging resolution in the scanning direction (scanning direction) of the line sensor 20, so that the repetition period Tb of the repeating structure becomes an integer period on the captured image.

[0086] The calculation step S1 may be performed after the workpiece 2 is set on the stage 10 of the inspection device 1, or may be performed before the workpiece 2 is set on the stage 10.

[0087] The rotation step S2 is a step of rotating the workpiece 2 to be inspected. Therefore, the rotation step S2 is performed after the workpiece 2 to be inspected is set on the stage 10.

[0088] In the rotation step S2, the workpiece 2 is rotated and tilted so as to form a predetermined angle with the scanning direction of the line sensor 20 (the Y-axis direction in this embodiment) based on the imaging conditions calculated in the calculation step S1. Specifically, as shown in Figures 4 and 5, in the rotation step S2, the workpiece 2 is rotated so that the angle between the scanning direction of the line sensor 20 and the direction repeated at a repeat pitch of period Tb in the workpiece 2 is θ. In this embodiment, by rotating the stage 10 on which the workpiece 2 is set by the rotation drive mechanism 30, the workpiece 2 is tilted so that the angle between the b direction of the repeating structure of the workpiece 2 (the direction repeated at a repeat pitch of period Tb) and the Y-axis direction is θ.

[0089] After tilting the workpiece 2 in the rotation step S2, the imaging step S3 is performed. In the imaging step S3, the linear drive mechanism 40 scans the line sensor 20 in the Y-axis direction (scanning direction) to image the workpiece 2 based on the imaging conditions calculated in the calculation step S1. In this case, in the imaging step S3, the entire workpiece 2 is imaged by the line sensor 20 with the workpiece 2 tilted at the angle θ calculated in the calculation step S1, as shown in Figures 4 and 5.

[0090] In this way, in the imaging step S3, the workpiece 2 is rotated by the rotation drive mechanism 30 to the angle θ calculated by the calculation unit 51, and the workpiece 2 is tilted and scanned by the line sensor 20, thereby imaging the workpiece 2. The captured image of the workpiece 2 captured in the imaging step S3 is sent to the image processing unit 53.

[0091] In the inspection step S4, the workpiece 2 is inspected for defects in the repeating structure based on the image of the workpiece 2 captured in the imaging step S3. Specifically, the repeating structure of the workpiece 2 is inspected based on the image of the workpiece 2 captured by the line sensor 20 in the imaging step S3. In this case, in the inspection step S4 in this embodiment, a comparison inspection is performed to compare pixels of two repeating structures in the image of the workpiece 2 acquired by scanning the line sensor 20 with the linear drive mechanism 40, thereby determining whether or not the workpiece 2 has a defect.

[0092] As described above, the presence or absence of specific defects in the workpiece 2 is determined by the image processing unit 53. That is, the image processing unit 53 performs image processing on the captured image to determine the presence or absence of defects in the repeating structure of the workpiece 2.

[0093] The inspection step S4 may be performed after the imaging step S3 or simultaneously with the imaging step S3. In other words, the presence or absence of defects in the repeating structure of the workpiece 2 may be determined by imaging the entire workpiece 2 with the line sensor 20 and then processing the image thus captured, or by performing image processing on the image captured as the workpiece 2 is imaged with the line sensor 20 at any time to determine the presence or absence of defects in the repeating structure of the workpiece 2.

[0094] In this manner, defects in the repeating structure of the workpiece 2 can be inspected.

[0095] In this way, according to the inspection device 1 and inspection method of this embodiment, by tilting the workpiece 2 having a repeating structure, θ (tilt of the workpiece 2) and Ry (resolution of the line sensor 20 in the Y-axis direction) are calculated from Rx (resolution of the line sensor 20 in the X-axis direction), Ta (repetition period of the repeating structure in the a-axis direction), and Tb (repetition period of the repeating structure in the b-axis direction), and defects in the workpiece 2 are inspected by comparing the pixels of the two repeating structures in the captured image of the workpiece 2 obtained by scanning the line sensor 20.

[0096] This allows the line sensor 20 to capture images in the field of view direction at approximately an integer ratio without changing the magnification of the imaging system, so that the repetitive structure of the workpiece 2 can be inspected with high precision.

[0097] When the workpiece 2 is tilted, the repeat pitch of the repeating structure of the workpiece 2 changes simultaneously in the viewing direction and the scanning direction of the line sensor 20. For this reason, the repeat pitch in the viewing direction and the scanning direction cannot be changed independently.

[0098] In this regard, in the inspection device 1 and inspection method according to this embodiment, Ry and θ are calculated by changing Ry so that the period Tb becomes an integer period on the captured image of the workpiece 2. In other words, in this embodiment, the repetitive structure of the workpiece 2 is inspected by also using a scanning ARS. This allows the resolution Ry in the Y-axis direction, which is the scanning direction, to be precisely adjusted, thereby increasing the degree of freedom in the combination of θ and Ry that satisfies the condition for imaging at an integer ratio in each of the line sensor's field of view and scanning direction. Therefore, by also using a scanning ARS, not only can the line sensor 20's field of view direction be imaged at approximately an integer ratio, but the line sensor 20's scanning direction can also be imaged at approximately an integer ratio. Therefore, the repetitive structure of the workpiece 2 can be inspected with even greater precision.

[0099] As described above, in the inspection apparatus 1 and inspection method of this embodiment, Ry and θ are calculated by tilting the workpiece 2. However, in an actual workpiece 2, the repetition periods Ta and Tb of the repeating structure have various values ​​depending on the workpiece 2, and the resolution Rx, which is the reference resolution and an input parameter, also has various values ​​depending on the inspection apparatus 1. For this reason, there is concern as to whether optimal θ and Ry exist for all Ta, Tb, and Rx. However, simulations have been conducted to verify that optimal θ and Ry can be calculated for all Ta, Tb, and Rx even when the workpiece 2 is tilted as described above, and the results of these simulations will be described below.

[0100] In this simulation, a rectangular chip with a side length of 300 μm to 20,000 μm (0.3 mm to 20 mm) was assumed as the workpiece 2. In other words, the chip size (workpiece size) has a side length of 300 μm to 20,000 μm.

[0101] The results of a simulation in which θ and Ry were calculated using the inspection method according to the above embodiment are shown in Figures 10, 11, and 12. Figure 10 shows the simulation results when a scan ARS is used in combination, Figure 11 shows the simulation results when a scan ARS is not used in combination, and Figure 12 shows the simulation results when an area sensor is used instead of the line sensor 20.

[0102] 10 to 12, "Example" is a case where the inspection method according to the above embodiment is used. Specifically, "Example" is a case where θ and Ry are calculated by tilting the workpiece 2 at an angle of θ. "Conventional Example" and "Comparative Example" are cases where the inspection method according to the above embodiment is not used.

[0103] 10 to 12, θ and Ry were calculated for each of the upper limits of θ to be calculated, which were 1°, 2°, . . . , 9°, and 10°, and θ and Ry were calculated for each of the reference resolutions Rx, which were 1.5 μm, 3.0 μm, 5.0 μm, 10.0 μm, and 20.0 μm. The range of Ry was varied by up to 10% in the direction of increasing the resolution relative to the reference resolution Rx so as not to reduce the inspection sensitivity. In other words, Ry was varied within the range of 0.9 × Rx ≦ Ry ≦ 1.0 × Rx.

[0104] In this simulation, θ was changed in increments of 0.001°, but this is not a limitation. θ may be changed in increments of 0.0005° or in other increments. Furthermore, when a scanning ARS is used in combination (FIG. 10), Ry can be freely selected. On the other hand, when a scanning ARS is not used in combination (FIG. 11), Ry was varied so that it could be selected in increments of 0.1 μm. Furthermore, when an area sensor is used instead of a line sensor (FIG. 12), Rx = Ry.

[0105] 10 to 12, when the best θ and Ry are selected, the remaining error (deviation) is 0.1 pixel or less and is displayed in white, and the remaining error (deviation) is 0.1 pixel or more and is displayed in black. This means that if the remaining error (deviation) is 0.1 pixel or less, θ and Ry can be calculated reliably.

[0106] Fig. 13 is a table summarizing Fig. 10 to Fig. 12 in numerical form. Fig. 13 numerically shows the percentage of remaining errors (deviation amounts) that are 0.1 pixels or less (i.e., the percentage of white areas) in Fig. 10 to Fig. 12. In Fig. 13, cases where the percentage of remaining errors (deviation amounts) that are 0.1 pixels or less is 95.0% or more are shaded.

[0107] As shown in FIG. 13, when the inspection method according to this embodiment is used ("Example"), the percentage of cases where the remaining error (deviation amount) is reduced to 0.1 pixels or less is higher than when the inspection method according to this embodiment is not used ("Comparative Example"). It is also clear that the inspection method according to this embodiment can adequately calculate θ and Ry. Furthermore, by using a scanning ARS in combination, it is clear that appropriate θ and Ry exist for almost all Rx, Ta, and Tb, even when the range of θ is limited to 3° or less. In particular, it can be said that θ and Ry certainly exist when the upper limit of θ is set to 7° or more. It is also clear that appropriate θ and Ry exist even without using a scanning ARS in combination, when the upper limit of θ is set to 6° or more.

[0108] (Variation) The inspection device and inspection method according to the present disclosure have been described above based on the embodiments, but the present disclosure is not limited to the above-described embodiments.

[0109] For example, the present disclosure also includes embodiments obtained by applying various modifications to the above-described embodiments that would occur to a person skilled in the art, and embodiments realized by arbitrarily combining the components and functions of the embodiments within the scope of the present disclosure. The present disclosure also includes any combination of two or more claims from among the multiple claims set forth in the claims at the time of filing, provided that there is no technical contradiction. For example, when a dependent claim set forth in the claims at the time of filing is made into a multiple claim or multiple multiple claims that cite all of the superordinate claims within the scope of the technical contradiction, the present disclosure also includes any combination of all claims included in the multiple claim or multiple multiple claims.

[0110] The present disclosure may be realized as a program used in the inspection method according to the above embodiment. For example, the present disclosure may be realized as a program that causes a processor to execute the calculation step S1 in the inspection method. [Industrial Applicability]

[0111] The technology disclosed herein is useful as an inspection device, an inspection method, etc. for inspecting a workpiece having a repetitive structure. [Explanation of symbols]

[0112] 1. Inspection equipment 2 Work 10 stages 20 Line Sensor 20a Imaging area 30 Rotation drive mechanism 40 Linear drive mechanism 50 Processing equipment 51 Arithmetic section 52 Drive control unit 53 Image processing section

Claims

1. An inspection apparatus for inspecting a workpiece having a repeating structure provided repeatedly in each of two orthogonal directions, comprising: Stage and a line sensor having a viewing direction in a first direction and configured to capture an image of the workpiece set on the stage; a rotation drive mechanism that rotates the workpiece so as to form a predetermined angle with a second direction perpendicular to the first direction; A calculation unit that calculates imaging conditions of the workpiece, Let Rx be the imaging resolution in the first direction in the inspection device, Ry be the imaging resolution in the second direction in the inspection device, θ be the predetermined angle, Ta be the repetition period of the repeating structure in one of the two orthogonal directions in the work, and Tb be the repetition period of the repeating structure in the other of the two orthogonal directions in the work, The calculation unit calculates Ry and θ as the imaging conditions using Rx, Ta, and Tb as input parameters, The inspection device rotates the workpiece by the rotation drive mechanism so as to have the angle of θ calculated by the calculation unit, and scans the line sensor in a state in which the workpiece is tilted, thereby capturing an image of the workpiece. Inspection equipment.

2. The inspection device inspects the workpiece for defects by comparing pixels of the two repeating structures in a captured image of the workpiece acquired by scanning the line sensor.

2. The inspection device according to claim 1.

3. The vectors of the two repeat structures before the workpiece is tilted at an angle of θ are (Xa, Ya), the vectors of the two repeat structures after the workpiece is tilted at an angle of θ are (Xn, Yn), and the vectors of the two repeat structures on the captured image are (Xp, Yp). Xp and Yp are expressed by the following equations: Xp=Xn / Rx=(Xa×cosθ−Ya×sinθ) / Rx, Yp=Yn / Ry=(Xa×sinθ+Ya×cosθ) / Ry, The calculation unit calculates θ and Ry so that Xp and Yp are integers.

3. The inspection device according to claim 2.

4. The calculation unit calculates the Ry and the θ by changing the Ry so that the Yp has an integer period on the captured image.

4. The inspection apparatus according to claim 3.

5. 1. An inspection method for inspecting a workpiece having a repeating structure provided repeatedly in each of two orthogonal directions, comprising: A calculation step of calculating predetermined imaging conditions; a rotating step of rotating and tilting the workpiece so as to form a predetermined angle with a second direction perpendicular to the first direction based on the imaging conditions; an imaging step of imaging the workpiece by scanning a line sensor whose viewing direction is the first direction in the second direction; An inspection process of inspecting the repeating structure of the workpiece based on an image of the workpiece captured by the line sensor, The image resolution in the first direction is Rx, the image resolution in the second direction is Ry, the predetermined angle is θ, the repeat period of the repeat structure in one of the two orthogonal directions in the work is Ta, and the repeat period of the repeat structure in the other of the two orthogonal directions in the work is Tb. In the calculation step, Rx, Ta, and Tb are used as input parameters, and Ry and θ are calculated as the image conditions. In the imaging step, the workpiece is imaged by scanning the line sensor while tilting the workpiece at the angle θ calculated in the calculation step. Testing method.

6. In the inspection step, the workpiece is inspected for defects by comparing pixels of the two repeating structures in the captured image of the workpiece. The inspection method according to claim 5.

7. The vectors of the two repeat structures before the workpiece is tilted at an angle of θ are (Xa, Ya), the vectors of the two repeat structures after the workpiece is tilted at an angle of θ are (Xn, Yn), and the vectors of the two repeat structures on the captured image are (Xp, Yp). Xp and Yp are expressed by the following equations: Xp=Xn / Rx=(Xa×cosθ−Ya×sinθ) / Rx, Yp=Yn / Ry=(Xa×sinθ+Ya×cosθ) / Ry, In the calculation step, θ and Ry are calculated so that Xp and Yp are integers. The inspection method according to claim 6.

8. In the calculation step, Ry is changed so that Tb has an integer period on the captured image, and Ry and θ are calculated. The inspection method according to claim 6 or 7.

9. A program used in an inspection method for inspecting a workpiece having a repeating structure provided repeatedly in each of two orthogonal directions, comprising: The inspection method includes: A calculation step of calculating predetermined imaging conditions; a rotating step of rotating and tilting the workpiece so as to form a predetermined angle with a second direction perpendicular to the first direction based on the imaging conditions; an imaging step of imaging the workpiece by scanning a line sensor whose viewing direction is a first direction in the second direction; An inspection process of inspecting the repeating structure of the workpiece based on an image of the workpiece captured by the line sensor, The image resolution in the first direction is Rx, the image resolution in the second direction is Ry, the predetermined angle is θ, the repeat period of the repeat structure in one of the two orthogonal directions in the work is Ta, and the repeat period of the repeat structure in the other of the two orthogonal directions in the work is Tb. In the calculation step, Rx, Ta, and Tb are used as input parameters, and Ry and θ are calculated as the image conditions. In the imaging step, the workpiece is imaged by scanning the line sensor while tilting the workpiece at the angle θ calculated in the calculation step, The program causes a processor to execute the calculation steps.

Images