Measuring device and measuring method

Abstract

To provide a measuring device and a measuring method capable of highly accurately measuring a distance from the center to the edge of a wafer across the outer periphery of the wafer in a simple manner.SOLUTION: A measuring device 1 according to the present disclosure comprises: a stage 10 that rotates a test wafer around a rotation axis C1; an imaging unit 20 that images an imaging region IA including an edge WFE of the test wafer; a calculation unit 31 that calculates reference end pixel coordinates corresponding to the position of the edge WFE with respect to a rotation angle θ of the stage 10 from an edge image obtained while rotating the test wafer one revolution with the stage 10; a storage unit 32 that stores associations between each reference end pixel coordinate and each reference radius of a reference wafer; and an acquisition unit 33 that acquires a reference radius of the test wafer by comparing the reference end pixel coordinates of the test wafer with the reference end pixel coordinates of the reference wafer. The calculation unit 31 calculates end pixel coordinates indicating the position of the edge WFE at a predetermined angle θ1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to measuring devices and measuring methods. [Background technology]

[0002] For example, Patent Document 1 describes a technique for measuring the distance from the center of a wafer to its edge at each radial angle along the outer circumference of the wafer. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5024555 [Patent Document 2] Patent No. 6210525 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] There is a need for a simple and highly accurate method to measure the distance from the center of a wafer to its edge along the outer circumference of the wafer.

[0005] This disclosure was made to solve such problems and aims to provide a measuring device and a measuring method that can measure the distance from the center to the edge of a wafer with high precision in a simple manner along the outer circumference of the wafer. [Means for solving the problem]

[0006] The measuring apparatus according to this disclosure includes a stage having a rotation axis for rotating a test wafer around the rotation axis, an imaging unit for imaging an imaging region including the edge of the test wafer from one side on which the rotation axis extends, a calculation unit for calculating reference edge pixel coordinates corresponding to the position of the edge in the radial direction perpendicular to the tangent to the edge in the imaging region with respect to the rotation angle of the stage, from edge images captured while the test wafer is rotated on the stage, and a calculation unit for calculating the reference edge pixel coordinates on the reference wafer calculated from images captured while the reference wafer having a known reference radius is rotated on the stage, in relation to each reference radius. The calculation unit comprises a storage unit that stores the data accordingly, and an acquisition unit that acquires the reference radius of the test wafer by comparing the reference edge pixel coordinates of the test wafer with the reference edge pixel coordinates of the reference wafer. The calculation unit calculates the predetermined angular edge pixel coordinates corresponding to the position of the edge at the predetermined angle from a predetermined angular image when the test wafer is rotated by a predetermined angle, and calculates the difference between the calculated predetermined angular edge pixel coordinates at the predetermined angle and the reference radius of the edge of the test wafer at the predetermined angle based on the acquired reference radius of the test wafer.

[0007] In the above measuring device, the magnification of the imaging unit when the predetermined angle image is captured may be greater than the magnification of the imaging unit when the edge image is captured.

[0008] In the above measuring device, the calculation unit calculates the amount of eccentricity from the center of the test wafer based on the edge image, the stage moves the test wafer in the radial direction to cancel out the amount of eccentricity that matches the predetermined angle when the predetermined angle image is captured, and the acquisition unit calculates the pixel coordinates of the predetermined angle edge of the test wafer at the predetermined angle after it has been moved in the radial direction.

[0009] The above measuring device further includes a marking processing unit that performs marking on a predetermined position on the test wafer, and the predetermined position may be determined based on a predetermined angle and the distance from the edge of the test wafer at the predetermined angle.

[0010] The measurement method according to this disclosure comprises: a first step of calculating reference edge pixel coordinates corresponding to the position of the edge in the radial direction perpendicular to the tangent to the edge in the imaging region with respect to the rotation angle of the stage, from an edge image obtained by an imaging unit from an imaging region including the edge of the test wafer from one side on which the rotation axis extends, while rotating the test wafer on a stage having a rotation axis; and a second step of storing the reference edge pixel coordinates on the reference wafer, calculated from an image obtained by the imaging unit while rotating a reference wafer having a known reference radius on the stage, in a storage unit that stores them in association with each reference radius. The system includes a second step of obtaining the reference radius of the test wafer by comparing the reference edge pixel coordinates of the test wafer with the reference edge pixel coordinates of the test wafer; a third step of calculating the predetermined angular edge pixel coordinates corresponding to the position of the edge at the predetermined angle from the predetermined angular image captured by the imaging unit when the test wafer is rotated by the predetermined angle; and a fourth step of calculating the difference between the calculated predetermined angular edge pixel coordinates at the predetermined angle and the reference radius of the edge of the test wafer at the predetermined angle, based on the obtained reference radius of the test wafer.

[0011] In the above measurement method, the magnification of the imaging unit in the third step may be greater than the magnification of the imaging unit in the first step.

[0012] In the above measurement method, in the first step, based on the edge image, the amount of eccentricity from the center of the test wafer is calculated, and in the third step, the test wafer is moved in the radial direction on the stage so as to cancel out the amount of eccentricity corresponding to the predetermined angle when the predetermined angle image is captured, and the pixel coordinates of the predetermined angle edge of the test wafer moved in the radial direction may be calculated.

[0013] The above measurement method further includes a fifth step of performing a marking process on a predetermined position of the test wafer, and in the fifth step, the predetermined position may be specified based on the predetermined angle and the distance from the edge of the test wafer at the predetermined angle.

Effect of the Invention

[0014] According to the present disclosure, it is possible to provide a measuring device and a measuring method for measuring the distance from the center to the edge of a wafer with high accuracy in a simple manner over the outer circumference of the wafer.

Brief Description of the Drawings

[0015] [Figure 1] It is a configuration diagram illustrating a measuring device according to Embodiment 1. [Figure 2] It is a plan view illustrating a wafer on a stage in the measuring device according to Embodiment 1. [Figure 3] It is a diagram illustrating an image of an imaging region captured by an imaging unit when a wafer is placed at a set position in the measuring device according to Embodiment 1. [Figure 4] It is a diagram illustrating an image of an imaging region captured by an imaging unit when the stage is rotated from the set position in the measuring device according to Embodiment 1. [Figure 5] It is a block diagram illustrating a processing unit in the measuring device according to Embodiment 1. [Figure 6]This graph illustrates the data processed by the processing unit in the measuring device according to Embodiment 1, with the horizontal axis showing the rotation angle of the stage and the vertical axis showing the position of the edge in the radial direction. [Figure 7] This graph illustrates the data processed by the processing unit in the measuring device according to Embodiment 1, with the horizontal axis showing the rotation angle of the stage and the vertical axis showing the position of the edge in the radial direction. [Figure 8] This graph illustrates the data processed by the processing unit in the measuring device according to Embodiment 1, with the horizontal axis representing the rotation angle of the stage and the vertical axis representing the amount of eccentricity. [Figure 9] This graph illustrates the data processed by the processing unit in the measuring device according to Embodiment 1, with the horizontal axis representing the rotation angle of the stage and the vertical axis representing the radius. [Figure 10] This flowchart illustrates a measurement method using the measuring device according to Embodiment 1. [Figure 11] This is a diagram illustrating a measuring device according to Embodiment 2. [Figure 12] This flowchart illustrates a measurement method using the measuring device according to Embodiment 2. [Modes for carrying out the invention]

[0016] The specific configuration of this embodiment will be described below with reference to the drawings. The following description illustrates preferred embodiments of the present invention, and the scope of this disclosure is not limited to these embodiments. In the following description, the same reference numerals indicate substantially the same components.

[0017] (Embodiment 1) A measuring device 1 according to Embodiment 1 will now be described. Figure 1 is a configuration diagram illustrating the measuring device 1 according to Embodiment 1. In Figure 1, a portion is shown as a cross-sectional view. Figure 2 is a plan view illustrating a wafer WF on the stage 10 in the measuring device 1 according to Embodiment 1. As shown in Figures 1 and 2, the measuring device 1 according to this embodiment includes a stage 10, an imaging unit 20, and a processing unit 30. The measuring device 1 measures the wafer WF.

[0018] A wafer WF may include a reference wafer and a test wafer to be tested, such as measurement. The reference wafer may have a reference radius that indicates a known reference radius. The reference wafer may be, for example, a wafer whose reference radius is known by contact, or a calibrated wafer. A wafer WF may include multiple reference wafers, each having a different reference radius.

[0019] Stage 10 places the wafer WF on it. Stage 10 has a stage surface 11. Stage 10 places the wafer WF flat on the stage surface 11. The back surface of the wafer WF is in contact with the stage surface 11. Stage 10 may have a predetermined setting position on the stage surface 11 for setting the wafer WF. For example, when measuring the wafer WF, the wafer WF may be fixed in the setting position first. The wafer WF has a wafer surface WF1. Here, for the convenience of explaining the measuring device 1, we introduce the XYZ Cartesian coordinate system. The plane parallel to the stage surface 11 is the XY plane. The direction perpendicular to the stage surface 11 is the Z axis direction.

[0020] The stage 10 has, for example, a rotation axis C1 extending from the center C of the stage 10. The rotation axis C1 extends, for example, in the Z-axis direction. The rotation axis C1 passes through the wafer WF placed on the stage surface 11. Therefore, the stage 10 rotates the wafer WF around the rotation axis C1. For example, the stage 10 may be connected to a drive unit such as a motor. The drive unit rotates the stage 10 around the rotation axis C1. When the wafer WF rotates on the stage 10, the rotation angle from a predetermined set position is called θ. Also, any predetermined angle is called θ1.

[0021] Furthermore, stage 10 may have a sliding mechanism. The sliding mechanism slides the wafer WF in one direction within the XY plane. For example, stage 10 slides in the X-axis direction. This causes stage 10 to move the wafer WF in the X-axis direction. Specifically, stage 10 may move the wafer WF in the radial direction R. The radial direction R is perpendicular to the tangent to the edge WFE of the wafer WF within the imaging area IA imaged by the imaging unit 20. For example, the radial direction R is the X-axis direction. Thus, stage 10 has an R-θ drive axis. Stage 10 may move the wafer WF in the X-axis direction or the radial direction R to cancel out the effect of wafer WF eccentricity (where the wafer WF is placed on stage 10 with a misalignment between the center C of stage 10 and the center of wafer WF), as described later. Stage 10 may move the wafer WF in the X-axis direction or radial direction R by a predetermined distance Diff (not shown) so that the notch portion of the wafer WF is included within the imaging area IA, as described later. For example, the wafer WF may be moved radially in the R direction (X-axis direction) so that the initial position WOR of the edge WFE is located below the center of the field of view in the imaging area IA, for example, at 1 / 4 of the field of view. Stage 10 may use the position moved by distance Diff as a reference position when imaging the wafer WF, and may move the wafer WF in the X-axis direction or radial direction R to cancel the effect of wafer WF eccentricity based on the position moved by distance Diff.

[0022] The stage 10 may also have a three-axis adjustment mechanism for adjusting the position of the stage 10 and the gradient of the stage surface 11. The stage 10 may also include a sensor such as an encoder for sensing the rotation angle θ from a predetermined set position.

[0023] Stage 10 is connected to the processing unit 30 via a communication line that includes at least one of wireless and wired connections. Specifically, Stage 10 is connected in a state where it can transmit information, including data on the rotation angle θ, to the processing unit 30. Stage 10 outputs information such as the sensed rotation angle θ data to the processing unit 30.

[0024] The imaging unit 20 images an imaging region IA that includes the edge WFE of the wafer WF. The imaging unit 20 includes, for example, an objective lens 21 and a camera 22. The imaging unit 20 may include optical components other than the objective lens 21 and camera 22, as long as it can image the imaging region IA that includes the edge WFE of the wafer WF, or it may include other optical components in addition to the objective lens 21 and camera 22. The imaging unit 20 images an imaging region IA that includes transmitted illumination of illumination light L1 irradiated from the back side of the wafer WF. The imaging unit 20 may also image an imaging region IA that includes reflected illumination of illumination light L1 irradiated from the wafer surface WF1 side of the wafer WF. The optical axis of the illumination light L1 and the optical axis of the objective lens 21 may be parallel to the Z-axis as shown in the figure, or they may be inclined with respect to the Z-axis.

[0025] Figure 3 is an example of an image of the imaging region IA captured by the imaging unit 20 when a wafer WF is placed at the set position in the measuring device 1 according to Embodiment 1. Figure 4 is an example of an image of the imaging region IA captured by the imaging unit 20 when the stage 10 is rotated from the set position in the measuring device 1 according to Embodiment 1.

[0026] As shown in Figure 3, the imaging unit 20 images the imaging region IA, which includes the edge WFE of the wafer WF, from one side on which the rotation axis C1 extends. Specifically, as an example, the imaging unit 20 images the imaging region IA from an imaging direction parallel to the rotation axis C1. The imaging region IA may include, for example, the field of view of the camera 22. The imaging direction is, for example, the -Z axis direction. The imaging unit 20 images the boundary between the illumination light L1 portion and the shadow portion as the position WOR of the physical edge WFE of the wafer WF. Therefore, the image of the imaging region IA includes the edge WFE. In the image, the position WOR of the edge WFE includes the coordinates WOR of the edge WFE. The position WOR of the edge WFE is sometimes called the coordinates WOR of the edge WFE. Also, the position WOR of the edge WFE is sometimes called the coordinates (θ=0, WOR) of the edge WFE.

[0027] Note that while the wafer edge WFE is defined as the physical edge WFE of the boundary of the illumination light L1, it is not limited to this. The wafer edge WFE may also be defined as the outer circumference of the flat wafer surface WF1, or as a predetermined position on the inclined portion at the edge of the wafer WF. In these cases, reflected illumination may be used.

[0028] As shown in Figure 4, the imaging unit 20 images the imaging area IA while rotating the wafer WF on the stage 10. If the center position of the wafer WF and the center C of the stage 10 are misaligned, or if the radius of the wafer WF is not uniform across its outer circumference, the position of the edge WFE (WOR) will be shifted by a length Δd in the radial direction R from the initial position WOR. When the amount of rotation is θ, the position (WOR) that is shifted by a length Δd in the radial direction R from the initial position WOR is also the coordinate (θ, WOR).

[0029] The imaging unit 20 may include a plurality of objective lenses 21 with different magnifications. For example, the imaging unit 20 may include a high-resolution, high-magnification objective lens 21 and a low-resolution, low-magnification objective lens 21. The image obtained when acquiring the reference edge pixel coordinates, described later, from the imaging area IA may be called an edge image. The image obtained when acquiring the predetermined angle edge pixel coordinates, described later, from the imaging area IA may be called a predetermined angle image. When acquiring a predetermined angle image, the imaging unit 20 may use an objective lens 21 with a higher magnification than when acquiring an edge image to image the imaging area IA. There may be multiple predetermined angles, or the entire circumference (360°). The imaging unit 20 may image the wafer WF in at least two cycles for the following two purposes. That is, the wafer WF may be imaged in two cycles: the first cycle for acquiring an image (edge ​​image) used to calculate the reference edge pixel coordinates of the wafer WF, and the second cycle for acquiring an image (predetermined angle image) used to calculate the predetermined angle edge pixel coordinates at a predetermined angle of the wafer WF. It is preferable that the imaging magnification in the second cycle is higher than that in the first cycle. However, if the center of the wafer WF coincides with the center C of the stage (rotation axis C1) (i.e., it is not eccentric), and the imaging of the wafer WF for acquiring the image used to calculate the reference edge pixel coordinates (edge ​​image) and the imaging of the wafer WF for acquiring the image used to calculate the predetermined angle edge pixel coordinates at a predetermined angle of the wafer WF (predetermined angle image) can be performed in one cycle, then it is not essential to image the wafer WF over two cycles. In this case, all or part of the image acquired using the high-magnification objective lens 21 may be used as the edge image and as the predetermined angle image as appropriate.

[0030] The imaging unit 20 is connected to the processing unit 30 by a communication line that includes at least one of wireless and wired connections. Specifically, the imaging unit 20 is connected in a state that it can transmit information, including data such as image data, to the processing unit 30. The imaging unit 20 outputs information such as captured image data to the processing unit 30.

[0031] Figure 5 is a block diagram illustrating the processing unit 30 in the measuring device 1 according to Embodiment 1. As shown in Figure 5, the processing unit 30 includes a calculation unit 31, a storage unit 32, and an acquisition unit 33. The calculation unit 31, storage unit 32, and acquisition unit 33 have functions as calculation means, storage means, and acquisition means. The processing unit 30 is an information processing device including, for example, a computer such as a PC, server, and smartphone.

[0032] Figures 6 and 7 are graphs illustrating data processed by the processing unit 30 in the measurement device 1 according to Embodiment 1. The horizontal axis represents the rotation angle θ of the stage 10, and the vertical axis represents the position (θ, WOR) of the edge WFE in the radial direction R. As shown in Figure 6, the calculation unit 31 identifies pixels indicating the position (θ, WOR) of the edge WFE of the wafer WF from the image captured by the imaging unit 20. The calculation unit 31 identifies the position (θ, WOR) of the edge WFE over the entire circumference of the outer edge of the wafer WF from the image captured while the wafer WF is rotated once on the stage 10. The position (θ, WOR) of the edge WFE may show a profile that, for example, represents a sine wave with respect to the rotation angle θ.

[0033] As shown in Figure 7, the calculation unit 31 calculates the average value R of the position (θ, WOR) of the edge WFE of the wafer WF. AVE The calculation unit 31 calculates the average value R of the edge WFE position (θ, WOR) of the wafer WF from the relationship between the value on the farther side (maximum value) of the edge WFE position (θ, WOR) in the radial direction R and the value on the farther side (minimum value) of the edge WFE position (θ, WOR). AVE The calculation unit 31 then calculates the average value R of the position (θ, WOR) of the edge WFE of the wafer WF in the captured image. AVE The coordinates of the pixel corresponding to the position indicated can be identified. These coordinates are then given the average R coordinate WOR AVE These are sometimes called reference edge pixel coordinates.

[0034] Thus, the calculation unit 31 calculates the reference end pixel coordinates corresponding to the wafer WF from the image obtained by imaging the wafer WF while rotating it, for example, once on the stage 10. The wafer WF may be a test wafer or a reference wafer.

[0035] Therefore, similar measurements may be performed on a reference wafer with a known radius. That is, in advance, the calculation unit 31 calculates the average R coordinate WOR AVE std of the reference wafer from the image obtained by imaging the reference wafer having a known reference radius while rotating it, for example, once on the stage 10. The average R coordinate WOR AVE std of the reference wafer may be referred to as the reference end pixel coordinates of the reference wafer. Further, the calculation unit 31 may calculate the respective reference end pixel coordinates in a plurality of reference wafers having a plurality of different reference radii.

[0036] As shown in the following equation (1), the calculation unit 31 calculates the average radius value Radius AVE from the difference between the average R coordinate WOR AVE of the test wafer and the average R coordinate WOR AVE std of the reference wafer. The average radius value Radius AVE may be referred to as the reference radius.

[0037] Radius AVE = WOR AVE std - WOR AVE (1)

[0038] The storage unit 32 stores the information output from the stage 10 and the information output from the imaging unit 20. Further, the storage unit 32 stores the information calculated by the calculation unit 31 and the information acquired by the acquisition unit 33. For example, the storage unit 32 may store the image obtained by imaging the wafer WF while rotating it on the stage 10, or may store the reference end pixel coordinates calculated from the image.

[0039] The storage unit 32 may store information calculated for a reference wafer. For example, the storage unit 32 stores the reference edge pixel coordinates on a reference wafer calculated from an image taken while rotating a reference wafer having a known reference radius once on the stage 10. The storage unit 32 also stores the reference edge pixel coordinates for each of the multiple reference wafers, each having a different reference radius, in association with each reference radius. The storage unit 32 stores the reference edge pixel coordinates on a reference wafer calculated from an image taken while rotating a reference wafer having a known reference radius on the stage 10, in association with each reference radius.

[0040] The acquisition unit 33 acquires wafer WF information using the information calculated by the calculation unit 31 and the information stored in the storage unit 32. For example, the acquisition unit 33 acquires the average R coordinate WOR of the test wafer calculated by the calculation unit 31. AVE (reference edge pixel coordinates) and the average R coordinates of the reference wafer stored in the memory unit 32 WOR AVE By comparing the std (reference edge pixel coordinates) with the average radius value of the test wafer, the Radius value can be determined. AVE You may obtain the (reference radius).

[0041] The imaging unit 20 captures an image of the imaging region IA, which includes the edge WFE, when the test wafer is rotated by a predetermined angle, in order to acquire an image at a predetermined angle. At this time, the test wafer has an average radius value Radius AVE In addition to the state in which the (reference radius) has been acquired, the state in which the edge image has been acquired by the imaging in the first cycle as described above, and the state in which the center of the wafer WF is aligned with the rotation axis C1 of the stage (not eccentric), the average radius value Radius AVE Any test wafer capable of obtaining the (reference radius) is acceptable. In this case, the imaging unit 20 may use a high-magnification objective lens 21. Also, in this case, the average R coordinate WOR of the test wafer is AVEHowever, the wafer is positioned in a predetermined set position. The stage 10 then moves the test wafer radially in direction R to cancel out the eccentricity ΔR. The eccentricity ΔR may be calculated by a known method (for example, the method shown in Patent Document 2). Specifically, when the wafer WF placed on the stage 10 is rotated and an image of the edge WFE of the wafer WF is captured, the autofocus optical system determines the position of the objective lens 21 that is in focus. The eccentricity between the rotation axis C1 and the wafer WF may then be calculated based on the position of the objective lens 21 when the wafer is rotated.

[0042] Figure 8 is a graph illustrating data processed by the processing unit 30 in the measuring device 1 according to Embodiment 1, where the horizontal axis represents the rotation angle θ of the stage 10 and the vertical axis represents the eccentricity ΔR. In Figure 8, a high-magnification objective lens 21 is used. Also in Figure 8, the eccentricity ΔR is canceled out by the stage 10. Figure 9 is a graph illustrating data processed by the processing unit 30 in the measuring device 1 according to Embodiment 1, where the horizontal axis represents the rotation angle θ of the stage 10 and the vertical axis represents the radius Radius.

[0043] As shown in Figures 8 and 9, the calculation unit 31 calculates the predetermined angle edge pixel coordinates (θ1, WRE) corresponding to the position of the edge WFE at the predetermined angle θ1 from the predetermined angle image, which is an image obtained when the test wafer is rotated by a predetermined angle θ1. Then, the calculation unit 31 uses the calculated predetermined angle edge pixel coordinates (θ1, WRE) at the predetermined angle θ1 and the acquired average radius value Radius of the test wafer. AVE (Reference radius) Average R coordinate WOR AVE Based on the (reference edge pixel coordinates), the calculation unit 31 calculates the radius Radius from the center of the test wafer to the edge WFE at a predetermined angle θ1. In other words, the calculation unit 31 calculates the distance corresponding to the difference in coordinates between the predetermined angle edge pixel coordinates at the predetermined angle θ1 and the reference edge pixel coordinates corresponding to the reference radius of the test wafer, thereby calculating the average radius value Radius of the edge WFE. AVE The difference in length between the (reference radius) and the edge WFE at a predetermined angle θ1 is calculated.

[0044] The calculation unit 31 calculates the eccentricity ΔR as the average radius value Radius, as shown in equation (2) below. AVE By adding this, the radius of the test wafer is obtained. The radius reflects the unevenness of the wafer edge WFE.

[0045] Radius = Radius AVE +ΔR (2)

[0046] As described above, the acquisition unit 33 acquires the average radius value Radius AVE When the test wafer, whose (reference radius) has been obtained, is rotated by a predetermined angle, the stage 10 moves the test wafer radially in direction R to cancel out the eccentricity ΔR. Therefore, since the eccentricity ΔR is canceled out, the unevenness of the wafer WF can be measured with high precision.

[0047] The processing unit 30 is connected to the stage 10 and the imaging unit 20 by a communication line that includes at least one of wireless and wired connections. Specifically, the processing unit 30 is connected in a manner that allows it to transmit information including rotation angle data to the stage 10. The processing unit 30 is also connected in a manner that allows it to transmit information including image data and other data to the imaging unit 20.

[0048] Next, a measurement method using the measuring device 1 of this embodiment will be described. Figure 10 is a flowchart illustrating an example of a measurement method using the measuring device 1 according to Embodiment 1.

[0049] As shown in step S11 of Figure 10, the reference edge pixel coordinates corresponding to the position of the edge WFE on the test wafer are calculated. Specifically, the calculation unit 31 calculates the reference edge pixel coordinates for the rotation angle θ of the stage 10 from the image captured by the imaging unit 20 while the test wafer is rotated, for example, once around the rotation axis C1 on the stage 10 which has a rotation axis C1.

[0050] In step S11, the calculation unit 31 may calculate the eccentricity ΔR from the center of the test wafer based on the image captured by the imaging unit 20 while the test wafer is rotated, for example, once around the rotation axis C1.

[0051] Next, as shown in step S12, the reference radius of the test wafer is obtained. For example, the storage unit 32 stores, for instance, the reference edge pixel coordinates on a reference wafer having a known reference radius, calculated from an image captured by the imaging unit 20 while the reference wafer is rotated, for example, once on the stage 10. The storage unit 32 also stores the reference edge pixel coordinates for each reference radius of a plurality of reference wafers, each having a different reference radius. The acquisition unit 33 then obtains the reference radius of the test wafer by comparing the reference edge pixel coordinates stored in the storage unit 32 with the reference edge pixel coordinates of the test wafer calculated by the calculation unit 31.

[0052] Next, as shown in step S13, the predetermined angular edge pixel coordinates corresponding to the position of the edge WFE at a predetermined angle are calculated. Specifically, the calculation unit 31 calculates the predetermined angular edge pixel coordinates corresponding to the position of the edge WFE at a predetermined angle θ1 from the image captured by the imaging unit 20 when the test wafer from which the reference radius has been obtained is rotated by a predetermined angle. The magnification of the imaging unit 20 in step S13 may be greater than the magnification of the imaging unit 20 in step S11.

[0053] Next, as shown in step S14, the difference between the edge WFE of the test wafer at a predetermined angle θ1 and the reference radius is calculated. Specifically, the calculation unit 31 calculates the radius Radius of the edge WFE of the test wafer at a predetermined angle, i.e., the difference from the reference radius, more specifically, the distance corresponding to the difference in coordinates between the predetermined edge pixel coordinate at a predetermined angle θ1 and the reference edge pixel coordinate corresponding to the reference radius of the test wafer, based on the difference between the predetermined edge pixel coordinate at a predetermined angle θ1 and the reference edge pixel coordinate corresponding to the reference radius of the test wafer.

[0054] In step S11, the calculation unit 31 calculates the eccentricity ΔR from the center of the test wafer based on the image captured by the imaging unit 20 while the test wafer is rotated, for example, once around the rotation axis C1. Based on this result, in step S13, the stage 10 may move the test wafer radially in the R direction to cancel out the eccentricity ΔR. The calculation unit 31 then acquires the pixel coordinates of a predetermined corner edge at a predetermined angle θ1 of the test wafer moved radially in the R direction. In this way, the test wafer can be measured using the measurement method with the measurement device 1.

[0055] Next, the effects of this embodiment will be described. In the measuring device 1 according to this embodiment, the calculation unit 31 calculates the reference edge pixel coordinates corresponding to the position WOR of the edge WFE on the test wafer. The acquisition unit 33 acquires the reference radius of the test wafer by comparing the reference edge pixel coordinates of the test wafer with the reference edge pixel coordinates of the reference wafer. As a result, the calculation unit 31 can calculate the difference between the calculated predetermined angle edge pixel coordinates at a predetermined angle θ1 and the acquired reference radius of the test wafer, and the reference radius of the edge WFE of the test wafer at a predetermined angle θ1. Therefore, the radius from the center of the wafer WF to the edge WFE can be measured with high accuracy in a simple manner over the entire circumference of the outer edge of the wafer WF.

[0056] When imaging the imaging area IA while rotating the test wafer, from which the reference radius has been obtained, by a predetermined angle, the magnification of the imaging unit 20 is set to be greater than the magnification of the imaging unit 20 when imaging while rotating the test wafer one full turn. This allows for observation from a general perspective when obtaining the overall indicator of the wafer, such as the reference radius of the test wafer, and enables high-magnification imaging when obtaining an indicator requiring high precision, such as the difference between the edge WFE and the reference radius. Thus, it is possible to achieve both high observation accuracy and reduced measurement time.

[0057] When a test wafer from which a reference radius has been obtained is rotated by a predetermined angle θ1, the stage 10 moves the test wafer radially R in such a way that the eccentricity ΔR from the center of the test wafer is canceled out. As a result, the calculation unit 31 can calculate the pixel coordinates of the predetermined corner edge at the predetermined angle θ1 on the test wafer from which the eccentricity ΔR has been canceled out. Therefore, the edge WFE of the test wafer can be calculated with high accuracy.

[0058] <Variation> Next, a modified version of the measuring device 1 according to Embodiment 1 will be described. In the modified version, when acquiring the imaging area IA of the wafer edge WFE, the stage 10 is moved by a predetermined distance Diff in the radial R direction. The predetermined distance Diff is a distance predetermined in order to capture the notch portion formed on the edge WFE of the wafer WF within the imaging area IA, regardless of the size of the wafer WF. That is, the imaging unit 20 acquires the edge image and the predetermined angle image with the stage 10 moved by a predetermined distance Diff in the radial R direction compared to Embodiment 1. As a result, the position of the notch portion can be accurately determined, and for example, the coordinates of the wafer edge WFE can be specified or identified with the notch portion as the reference position (θ=0°).

[0059] (Embodiment 2) Next, a measuring device according to Embodiment 2 will be described. The measuring device 2 of this embodiment further includes a marking processing unit that performs marking processing on a wafer WF. Figure 11 is a configuration diagram illustrating the measuring device 2 according to Embodiment 2. As shown in Figure 11, the measuring device 2 further includes a marking processing unit 40.

[0060] The marking processing unit 40 performs, for example, a process of marking a predetermined marking position on the test wafer. The predetermined marking position is determined based on a predetermined angle and the distance from the edge WFE of the test wafer at the predetermined angle. For example, the marking position is a position having a marking angle from the predetermined position, and is a position at which a predetermined marking distance is located radially R from the edge WFE at the marking angle. The marking processing unit 40 may also perform a process of notifying the user of the marking position. The marking processing unit 40 performs at least one of the processes of marking and notifying.

[0061] Figure 12 is a flowchart illustrating a measurement method using the measuring device 2 according to Embodiment 2. As shown in step S15 of Figure 12, the measurement method of this embodiment further includes a step of performing a marking process on the test wafer, compared to the measurement method described above.

[0062] According to this embodiment, marking can be performed on the wafer WFE with high precision coordinates. Furthermore, the marking position can be measured with high precision. Other configurations and effects are described in Embodiment 1.

[0063] Although embodiments of the present invention have been described above, the present invention includes appropriate modifications that do not impair its purpose and advantages, and is not limited by the above embodiments. [Explanation of Symbols]

[0064] 1, 2 Measuring devices 10 stages 11 Stages 20 Imaging Department 21 Objective lens 22 cameras 30 Processing Unit 31 Calculation Section 32 Storage section 33 Acquisition Department 40 Marking Processing Unit C center C1 Rotation axis IA imaging area L1 illumination light WF wafer WF1 wafer surface WFE Edge WOR position

Claims

1. A stage having a rotation axis, which rotates the test wafer around the rotation axis, An imaging unit that images an imaging region including the edge of the test wafer from one side on which the rotation axis extends, A calculation unit calculates reference edge pixel coordinates corresponding to the position of the edge in the radial direction perpendicular to the tangent to the edge within the imaging area with respect to the rotation angle of the stage, from edge images captured while the test wafer is rotated on the stage. A storage unit that stores the coordinates of the reference edge pixels on the reference wafer, calculated from an image taken while rotating the reference wafer having a known reference radius on the stage, in association with each reference radius, An acquisition unit acquires the reference radius of the test wafer based on the correspondence between the reference edge pixel coordinates of the reference wafer and the known reference radius, which is stored in the storage unit, and the reference edge pixel coordinates of the test wafer. Equipped with, The calculation unit described above, From the predetermined angle image obtained when the test wafer is rotated by a predetermined angle, the predetermined angle edge pixel coordinates corresponding to the position of the edge at the predetermined angle are calculated. By calculating the distance corresponding to the difference in coordinates between the predetermined angle end pixel coordinates at the calculated predetermined angle and the reference end pixel coordinates corresponding to the reference radius of the acquired test wafer, the length of the difference between the edge of the test wafer at the predetermined angle and the reference radius of the test wafer is calculated. Based on the length of the difference and the reference radius of the test wafer, the distance from the center of the test wafer to the edge at the predetermined angle is obtained. Measuring device.

2. The magnification of the imaging unit when the predetermined angle image is captured is greater than the magnification of the imaging unit when the edge image is captured. The measuring device according to claim 1.

3. The calculation unit calculates the amount of eccentricity from the center of the test wafer based on the edge image, The stage moves the test wafer in the radial direction so as to cancel out the amount of eccentricity that corresponds to the predetermined angle when the predetermined angle image is captured. The acquisition unit calculates the coordinates of the predetermined corner edge pixels at the predetermined angle of the test wafer moved in the radial direction. The measuring device according to claim 1.

4. A first step is to calculate reference edge pixel coordinates corresponding to the position of the edge in the radial direction perpendicular to the tangent to the edge within the imaging region with respect to the rotation angle of the stage, from an edge image captured by an imaging unit from one side on which the rotation axis extends, while rotating the test wafer around the rotation axis. A second step involves obtaining the reference radius of a test wafer based on the correspondence between the reference edge pixel coordinates of the reference wafer and the known reference radius, which is stored in a storage unit that stores the reference edge pixel coordinates of the reference wafer and the known reference radius, while the reference wafer having a known reference radius is rotated on the stage, and the reference edge pixel coordinates of the test wafer. A third step involves calculating predetermined angle edge pixel coordinates corresponding to the position of the edge at the predetermined angle from the predetermined angle image captured by the imaging unit when the test wafer is rotated by a predetermined angle, By calculating the distance corresponding to the difference in coordinates between the predetermined angle end pixel coordinates at the calculated predetermined angle and the reference end pixel coordinates corresponding to the reference radius of the acquired test wafer, the length of the difference between the edge of the test wafer at the predetermined angle and the reference radius of the test wafer is calculated. A fourth step of obtaining the distance from the center of the test wafer to the edge at the predetermined angle based on the length of the difference and the reference radius of the test wafer, A measurement method equipped with [a specific feature / feature].

5. The magnification of the imaging unit in the third step is greater than the magnification of the imaging unit in the first step. The measurement method according to claim 4.

6. In the first step described above, Based on the edge image, the amount of eccentricity from the center of the test wafer is calculated. In step 3, On the stage, the test wafer is moved in the radial direction so as to cancel out the amount of eccentricity that corresponds to the predetermined angle when the predetermined angle image is captured. The coordinates of the predetermined corner edge pixels at the predetermined angle of the test wafer moved in the radial direction are calculated. The measurement method according to claim 4.

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