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] The present disclosure relates to a measurement device and a measurement method. [Background technology]

[0002] For example, Patent Document 1 describes a technique for measuring the distance from the center to the edge of a wafer for each angle in the radial direction of the wafer over the outer periphery of the wafer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5024555 [Patent Document 2] Patent No. 6210525 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desired to measure the distance from the center to the edge of a wafer over the circumference of the wafer with high accuracy using a simple method.

[0005] The present disclosure has been made to solve such problems, and aims to provide a measurement device and a measurement method that can measure the distance from the center to the edge of a wafer over the entire circumference of the wafer with high accuracy using a simple method. [Means for solving the problem]

[0006] A measurement device according to the present disclosure includes a stage having a rotation axis and rotating a test wafer around the rotation axis; an imaging unit that images an imaging area including an edge of the test wafer from one side along which the rotation axis extends; a calculation unit that calculates, from an edge image captured while the test wafer is rotated on the stage, reference edge pixel coordinates corresponding to the position of the edge in a radial direction perpendicular to a tangent to the edge in the imaging area relative to the rotation angle of the stage; and a calculation unit that calculates, from an image captured while the reference wafer having a known reference radius is rotated on the stage, the reference edge pixel coordinates of the reference wafer relative to each reference radius. 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, wherein the calculation unit calculates, from a predetermined angle image obtained when the test wafer is rotated by the predetermined angle, predetermined corner edge pixel coordinates corresponding to the position of the edge at the predetermined angle, and calculates a difference between the calculated predetermined corner 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 measurement device, a magnification of the imaging unit when the predetermined angle image is captured may be greater than a magnification of the imaging unit when the edge image is captured.

[0008] In the above-described measuring device, the calculation unit may calculate the amount of eccentricity from the center of the test wafer based on the edge image, the stage may move the test wafer in the radial direction so as to cancel out the amount of eccentricity that is set to the predetermined angle when the predetermined angle image is captured, and the acquisition unit may calculate pixel coordinates of the predetermined corner end of the test wafer at the predetermined angle that has been moved in the radial direction.

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

[0010] The measurement method according to the present disclosure includes a first step of calculating, from an edge image captured by an imaging unit of an imaging area including an edge of the test wafer from one side of the rotation axis while rotating the test wafer around the rotation axis on a stage having the rotation axis, reference edge pixel coordinates corresponding to the position of the edge in a radial direction perpendicular to a tangent to the edge within the imaging area relative to the rotation angle of the stage; and a second step of storing, in a storage unit, the reference edge pixel coordinates of the reference wafer calculated from an image captured by the imaging unit while rotating the reference wafer having a known reference radius on the stage, in association with each reference radius. The method includes a second step of acquiring the reference radius of the test wafer by comparing the reference edge pixel coordinates with the reference edge pixel coordinates of the test wafer; a third step of calculating, from a predetermined angle image captured by the imaging unit when the test wafer is rotated by the predetermined angle, predetermined corner edge pixel coordinates corresponding to the position of the edge at the predetermined angle; and a fourth step of calculating, based on the calculated predetermined corner edge pixel coordinates at the predetermined angle and the acquired reference radius of the test wafer, a difference between the calculated predetermined corner edge pixel coordinates at the predetermined angle and the reference radius of the edge of the test wafer at the predetermined angle.

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

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

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

[0014] According to the present disclosure, it is possible to provide a measurement device and a measurement method that can measure the distance from the center to the edge of a wafer over the entire circumference of the wafer with high accuracy using a simple method. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a configuration diagram illustrating a measurement device according to a first embodiment. [Figure 2] 2 is a plan view illustrating a wafer on a stage in the measurement device according to the first embodiment. FIG. [Figure 3] 4 is a diagram illustrating an example of an image of an imaging area captured by an imaging unit when a wafer is placed at a set position in the measurement device according to the first embodiment. FIG. [Figure 4] 4 is a diagram illustrating an example of an image of an imaging area captured by an imaging unit when a stage is rotated from a set position in the measurement device according to the first embodiment. FIG. [Figure 5] 2 is a block diagram illustrating a processing unit in the measurement device according to the first embodiment. FIG. [Figure 6]1 is a graph illustrating data processed by a processing unit in the measurement device according to the first embodiment, where the horizontal axis indicates the rotation angle of the stage and the vertical axis indicates the position of the edge in the radial direction. [Figure 7] 1 is a graph illustrating data processed by a processing unit in the measurement device according to the first embodiment, where the horizontal axis indicates the rotation angle of the stage and the vertical axis indicates the position of the edge in the radial direction. [Figure 8] 1 is a graph illustrating data processed by a processing unit in the measurement device according to the first embodiment, where the horizontal axis indicates the rotation angle of the stage and the vertical axis indicates the amount of eccentricity. [Figure 9] 1 is a graph illustrating data processed by a processing unit in the measurement device according to the first embodiment, where the horizontal axis indicates the rotation angle of the stage and the vertical axis indicates the radius. [Figure 10] FIG. 2 is a flowchart illustrating a measurement method using the measurement device according to the first embodiment. [Figure 11] FIG. 10 is a configuration diagram illustrating a measurement device according to a second embodiment. [Figure 12] FIG. 10 is a flowchart illustrating a measurement method using the measurement device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

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

[0018] The wafer WF may include a reference wafer serving as a reference and a test wafer to be subjected to a test such as measurement. The reference wafer may have a reference radius indicating a known radius to be used as a reference. The reference wafer may be, for example, a wafer whose reference radius is known by contact or a calibrated wafer. The wafer WF may include multiple reference wafers each having a different reference radii.

[0019] The stage 10 places the wafer WF on it. The stage 10 has a stage surface 11. The stage 10 places the wafer WF flat on the stage surface 11. The back surface of the wafer WF contacts the stage surface 11. The stage 10 may have a predetermined set position on the stage surface 11 where the wafer WF is set. For example, when measuring the wafer WF, the wafer WF may first be fixed at the set position. The wafer WF has a wafer surface WF1. Here, for convenience of explanation of the measurement apparatus 1, an XYZ Cartesian coordinate system is introduced. The plane parallel to the stage surface 11 is defined as the XY plane. The direction perpendicular to the stage surface 11 is defined as 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 referred to as θ. Also, any predetermined angle is referred to as θ1.

[0021] The stage 10 may also have a sliding mechanism. The sliding mechanism slides the wafer WF in one direction within the XY plane. For example, the stage 10 slides in the X-axis direction. This causes the stage 10 to move the wafer WF in the X-axis direction. Specifically, the stage 10 may move the wafer WF in the radial direction R. The radial direction R is a direction 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. In this way, the stage 10 has an R-θ drive axis. The stage 10 may move the wafer WF in the X-axis direction or the radial direction R to cancel the effect of eccentricity of the wafer WF (when the wafer WF is placed on the stage 10 with the center C of the stage 10 misaligned from the center of the wafer WF), as described below. The stage 10 may move the wafer WF in the X-axis direction or the radial direction R by a predetermined distance Diff (not shown) so that the notch portion of the wafer WF is included in the imaging area IA, as described below. For example, the wafer WF is moved in the radial direction R (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 a position that is 1 / 4 of the field of view. The position moved by the distance Diff may be used by the stage 10 as a reference position when imaging the wafer WF, and the wafer WF may be moved in the X-axis direction or the radial direction R so as to cancel the effects of eccentricity of the wafer WF based on the position moved by the distance Diff.

[0022] The stage 10 may have a three-axis adjustment mechanism or the like that adjusts 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 that senses the rotation angle θ rotated from a predetermined set position.

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

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

[0025] Fig. 3 is a diagram illustrating an image of the imaging area IA captured by the imaging unit 20 when the wafer WF is placed at the set position in the measurement apparatus 1 according to embodiment 1. Fig. 4 is a diagram illustrating an image of the imaging area IA captured by the imaging unit 20 when the stage 10 is rotated from the set position in the measurement apparatus 1 according to embodiment 1.

[0026] As shown in FIG. 3, the imaging unit 20 images an imaging area IA including the edge WFE of the wafer WF from one side along which the rotation axis C1 extends. Specifically, as an example, the imaging unit 20 images the imaging area IA from an imaging direction parallel to the rotation axis C1. The imaging area 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 captured of the imaging area IA includes the edge WFE. In the image, the position WOR of the edge WFE includes the coordinate WOR of the edge WFE. The position WOR of the edge WFE may also be referred to as the coordinate WOR of the edge WFE. The position WOR of the edge WFE may also be referred to as the coordinate (θ=0, WOR) of the edge WFE.

[0027] Although the edge WFE of the wafer WF is defined as the physical edge WFE of the boundary of the illumination light L1, this is not limited to this. The edge WFE of the wafer WF may be defined as the outer periphery of the flat wafer surface WF1 or as a predetermined position on the slope at the edge of the wafer WF. In these cases, reflected illumination may be used.

[0028] 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 is misaligned with the center C of the stage 10, or if the radius of the wafer WF is not uniform along its periphery, the position (WOR) of the edge WFE 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) shifted by a length Δd in the radial direction R from the initial position WOR also has the coordinates (θ, WOR).

[0029] The imaging unit 20 may include multiple objective lenses 21 with different magnifications. The imaging unit 20 may include, for example, a high-magnification objective lens 21 with high resolution and a low-magnification objective lens 21 with low resolution. An image of the imaging area IA when acquiring reference edge pixel coordinates (described later) may be referred to as an edge image. An image of the imaging area IA when acquiring predetermined corner edge pixel coordinates (described later) may be referred to as a predetermined angle image. When acquiring the predetermined angle image, the imaging unit 20 may use an objective lens 21 with a higher magnification than when acquiring the edge image to image the imaging area IA. The predetermined angle may be multiple 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 a first cycle to acquire an image (edge ​​image) used to calculate the reference edge pixel coordinates of the wafer WF, and in a second cycle to acquire an image (predetermined angle image) used to calculate the predetermined corner edge pixel coordinates at the predetermined angle of the wafer WF. The imaging magnification in the second cycle is preferably higher than that in the first cycle. When the center of the wafer WF coincides with the center C (rotation axis C1) of the stage (not eccentric), imaging of the wafer WF to acquire an image (edge ​​image) used to calculate the reference edge pixel coordinates and imaging of the wafer WF to acquire an image (predetermined angle image) used to calculate the predetermined corner edge pixel coordinates at a predetermined angle of the wafer WF can be performed in one cycle, for example. 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 via a communication line including at least one of wireless and wired. Specifically, the imaging unit 20 is connected in a state in which information including data such as image data can be transmitted to the processing unit 30. The imaging unit 20 outputs information such as captured image data to the processing unit 30.

[0031] Fig. 5 is a block diagram illustrating the processing unit 30 in the measurement device 1 according to the first embodiment. As shown in Fig. 5, the processing unit 30 includes a calculation unit 31, a storage unit 32, and an acquisition unit 33. The calculation unit 31, the storage unit 32, and the acquisition unit 33 function as a calculation means, a storage means, and an acquisition means. The processing unit 30 is an information processing device including a computer such as a PC, a server, or a smartphone.

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

[0033] As shown in FIG. 7, the calculation unit 31 calculates the average value R of the position (θ, WOR) of the edge WFE of the wafer WF. AVE For example, the calculation unit 31 calculates the average value R of the position (θ, WOR) of the edge WFE of the wafer WF from the relationship between the value (maximum value) of the position (θ, WOR) of the edge WFE on the one side in the radial direction R and the value (minimum value) of the position (θ, WOR) of the edge WFE on the other side in the radial direction R. AVE As a result, the calculation unit 31 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 showing the average R coordinate WOR AVE These are sometimes called the reference edge pixel coordinates.

[0034] In this way, the calculation unit 31 calculates the reference edge pixel coordinates corresponding to the wafer WF from an image captured while the wafer WF is rotated, for example, once on the stage 10. The wafer WF may be a test wafer or a reference wafer.

[0035] Therefore, a similar measurement may be performed on a reference wafer having a known radius. That is, the calculation unit 31 calculates in advance the average R coordinate WOR of the reference wafer from an image captured while rotating the reference wafer having a known reference radius, for example, once on the stage 10. AVE The standard R coordinate of the reference wafer WOR may be calculated. AVE std may be referred to as the reference edge pixel coordinate of the reference wafer. The calculation unit 31 may also calculate the reference edge pixel coordinates for a plurality of reference wafers each having a plurality of different reference radii.

[0036] The calculation unit 31 calculates the average R coordinate WOR of the test wafer as shown in the following equation (1): AVE and the average R coordinate of the reference wafer WOR AVE Average radius value Radius from the difference with std AVE Calculate the average radius value Radius AVE is sometimes called the reference radius.

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

[0038] The storage unit 32 stores information output from the stage 10 and information output from the imaging unit 20. The storage unit 32 also stores information calculated by the calculation unit 31 and information acquired by the acquisition unit 33. For example, the storage unit 32 may store images captured while the wafer WF is rotated on the stage 10, or may store reference end pixel coordinates calculated from the images.

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

[0040] The acquiring unit 33 acquires information about the wafer WF using the information calculated by the calculating unit 31 and the information stored in the storage unit 32. For example, the acquiring unit 33 acquires information about the wafer WF using the average R coordinate WOR of the test wafer calculated by the calculating unit 31. AVE (reference edge pixel coordinates) and the average R coordinate WOR of the reference wafer stored in the memory unit 32 AVE The average radius value of the test wafer is calculated by comparing the std (reference edge pixel coordinate) with AVE (Reference radius) may be obtained.

[0041] The imaging unit 20 captures an image of the imaging area IA including the edge WFE when the test wafer is rotated by a predetermined angle to obtain a predetermined angle image. AVE The average radius value Radius (reference radius) is obtained when the edge image has already been acquired by the first cycle of imaging, and when the center of the wafer WF is aligned with the rotation axis C1 of the stage (not eccentric). AVE The test wafer may be in a state where the reference radius (R) can be obtained. In this case, the imaging unit 20 may use a high-magnification objective lens 21. In this case, the average R coordinate WOR of the test wafer AVEis placed at a predetermined set position. Then, the stage 10 moves the test wafer in the radial direction R so as to cancel out the eccentricity ΔR. The eccentricity ΔR may be calculated by a known method (for example, the method disclosed in Patent Document 2). Specifically, when the wafer WF placed on the stage 10 is rotated and an image of the end WFE of the wafer WF is captured, the position of the objective lens 21 where the focus is achieved is determined by an autofocus optical system. Then, the eccentricity between the rotation axis C1 and the wafer WF may be calculated based on the position of the objective lens 21 when the wafer is rotated.

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

[0043] 8 and 9, the calculation unit 31 calculates the pixel coordinates (θ1, WRE) of the edge at the predetermined angle θ1 corresponding to the position of the edge WFE at the predetermined angle θ1 from the predetermined angle image, which is an image obtained by rotating the test wafer by the predetermined angle θ1. Then, the calculation unit 31 calculates the pixel coordinates (θ1, WRE) of the edge at the predetermined angle θ1 calculated at the predetermined angle θ1 and the average radius value Radius of the acquired test wafer. AVE Average R coordinate WOR relative to (reference radius) AVE (reference edge pixel coordinates) and calculates the radius Radius from the center of the test wafer to the edge WFE at the predetermined angle θ1. In other words, the calculation unit 31 calculates the distance corresponding to the difference in coordinates between the predetermined corner 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 between the (reference radius) and the length to the edge WFE at the predetermined angle θ1 is calculated.

[0044] The calculation unit 31 calculates the eccentricity amount ΔR as the average radius value Radius AVE The radius of the test wafer, Radius, is obtained by adding to the above. The radius, Radius, reflects the unevenness of the edge, WFE, of the wafer, WF.

[0045] Radius=Radius AVE +ΔR (2)

[0046] As described above, the average radius value Radius AVE When the test wafer for which the reference radius has been acquired is rotated by a predetermined angle, the stage 10 moves the test wafer in the radial direction R so as 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 accuracy.

[0047] The processing unit 30 is connected to the stage 10 and the imaging unit 20 via a communication line that includes at least one of wireless and wired lines. Specifically, the processing unit 30 is connected in a state in which it can transmit information including rotation angle data to the stage 10. The processing unit 30 is also connected in a state in which it can transmit information including data such as image data to the imaging unit 20.

[0048] Next, a description will be given of a measurement method using the measurement device 1 of this embodiment. Fig. 10 is a flow chart illustrating an example of a measurement method using the measurement device 1 according to the first embodiment.

[0049] 10, the calculation unit 31 calculates the reference end pixel coordinates corresponding to the position of the edge WFE on the test wafer. Specifically, the calculation unit 31 calculates the reference end pixel coordinates for the rotation angle θ of the stage 10 from an 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 having the 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 an 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 acquired. For example, the storage unit 32 stores in advance the reference edge pixel coordinates of the reference wafer calculated from images captured by the imaging unit 20 while the reference wafer having a known reference radius is rotated, for example, once on the stage 10. The storage unit 32 also stores the reference edge pixel coordinates in association with each reference radius of multiple reference wafers having multiple different reference radii. The acquisition unit 33 then acquires 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 calculation unit 31 calculates the predetermined corner pixel coordinates corresponding to the position of the edge WFE at the predetermined angle. Specifically, the calculation unit 31 calculates the predetermined corner pixel coordinates corresponding to the position of the edge WFE at the predetermined angle θ1 from the image captured by the imaging unit 20 when the test wafer for which the reference radius has been acquired is rotated by the predetermined angle. The magnification of the imaging unit 20 in step S13 may be larger than the magnification of the imaging unit 20 in step S11.

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

[0054] In step S11, the calculation unit 31 may calculate the amount of eccentricity ΔR from the center of the test wafer based on images captured by the imaging unit 20 while rotating the test wafer, for example, once around the rotation axis C1. Based on the result of the calculation, in step S13, the stage 10 may move the test wafer in the radial direction R so as to cancel out the amount of eccentricity ΔR. Then, the calculation unit 31 acquires pixel coordinates of a predetermined corner end at a predetermined angle θ1 of the test wafer moved in the radial direction R. In this manner, the test wafer can be measured by a measurement method using the measurement device 1.

[0055] Next, the effects of this embodiment will be described. In the measurement apparatus 1 according to this embodiment, the calculation unit 31 calculates 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. This allows the calculation unit 31 to calculate the difference between the reference radius of the edge WFE of the test wafer at the predetermined angle θ1 based on the calculated pixel coordinates of the predetermined corner edge at the predetermined angle θ1 and the acquired reference radius of the test wafer. Therefore, the radius from the center of the wafer WF to the edge WFE can be measured with high accuracy over the entire circumference of the wafer WF using a simple method.

[0056] The magnification of the imaging unit 20 when imaging the imaging area IA when the test wafer, for which the reference radius has been acquired, is rotated by a predetermined angle is set to be larger than the magnification of the imaging unit 20 when imaging the test wafer while rotating it once. This allows observation from a rough perspective when acquiring an overall index of the wafer, such as the reference radius of the test wafer, and allows imaging at a high magnification when acquiring an index that requires precision, such as the difference from the reference radius of the edge WFE. Therefore, it is possible to achieve both high observation precision and a shortened measurement time.

[0057] When the test wafer for which the reference radius has been acquired is rotated by a predetermined angle θ1, the stage 10 moves the test wafer in the radial direction R so as to cancel out the eccentricity ΔR from the center of the test wafer. This allows the calculation unit 31 to calculate the pixel coordinates of the predetermined corner end at the predetermined angle θ1 for the test wafer for which the eccentricity ΔR has been canceled. Therefore, the edge WFE of the test wafer can be calculated with high accuracy.

[0058] <Modification> Next, a modified example of the measurement apparatus 1 according to the first embodiment will be described. In this modified example, when acquiring an imaging area IA of the edge WFE of the wafer WF, the stage 10 is moved a predetermined distance Diff in the direction of the radius R. The predetermined distance Diff is a distance determined in advance so that the notch formed in the edge WFE of the wafer WF can be captured within the imaging area IA regardless of the size of the wafer WF. That is, the imaging unit 20 acquires an edge image and a predetermined angle image while moving the stage 10 a predetermined distance Diff in the direction of the radius R more than in the first embodiment. This allows the position of the notch to be accurately determined, making it possible, for example, to specify or identify the coordinates of the edge WFE of the wafer WF with the notch as the reference position (θ = 0°).

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

[0060] The marking processing unit 40 performs, for example, a process of marking at a predetermined marking position on the test wafer. The predetermined marking position is identified based on a predetermined angle and a 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 that is a predetermined marking distance in the radial direction 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 a marking process and a notification process.

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

[0062] According to this embodiment, marking processing can be performed on highly accurate coordinates of the wafer WFE. Also, the marking position can be measured with high accuracy. Other configurations and effects are included in the description of the first embodiment.

[0063] Although the embodiments of the present invention have been described above, the present invention includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited to the above-described embodiments. [Explanation of symbols]

[0064] 1, 2 Measurement equipment 10 stages 11 Stage surface 20 Imaging unit 21 Objective Lens 22 Camera 30 Processing section 31 Calculation section 32 Storage section 33 Acquisition Department 40 Marking processing section 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 for rotating the test wafer about the rotation axis; an imaging unit that images an imaging area including an edge of the test wafer from one side along which the rotation axis extends; a calculation unit that calculates, from an edge image captured while rotating the test wafer on the stage, a reference edge pixel coordinate corresponding to the position of the edge in a radial direction orthogonal to a tangent to the edge within an imaging area relative to a rotation angle of the stage; a storage unit that stores the pixel coordinates of the reference end portion of the reference wafer, which are calculated from an image captured while rotating a reference wafer having a known reference radius on the stage, in association with each reference radius; 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; Equipped with The calculation unit calculating, from a predetermined angle image obtained by rotating the test wafer by a predetermined angle, pixel coordinates of a predetermined corner end portion corresponding to the position of the edge at the predetermined angle; calculating a difference between the calculated pixel coordinates of the predetermined corner end at the predetermined angle and the reference radius of the edge of the test wafer at the predetermined angle based on the calculated pixel coordinates of the predetermined corner end at the predetermined angle and the reference radius of the test wafer; Measuring equipment.

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

3. the calculation unit calculates an 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 the eccentricity amount that is set to the predetermined angle when the predetermined angle image is captured; the acquisition unit calculates pixel coordinates of the predetermined corner end portion at the predetermined angle of the test wafer moved in the radial direction. The measurement device according to claim 1 .

4. a marking processing unit that performs marking processing on a predetermined position on the test wafer; The predetermined position is identified based on the predetermined angle and a distance from the edge of the test wafer at the predetermined angle. The measuring device according to any one of claims 1 to 3.

5. a first step of calculating, from an edge image captured by an imaging unit of an imaging area including an edge of the test wafer from one side along which the rotation axis extends while rotating the test wafer around the rotation axis on a stage having a rotation axis, reference edge pixel coordinates corresponding to the position of the edge in a radial direction orthogonal to a tangent to the edge in the imaging area relative to the rotation angle of the stage; a second step of acquiring the reference radius of the test wafer by comparing the reference end pixel coordinates of the reference wafer, which are calculated from an image captured by the imaging unit while rotating a reference wafer having a known reference radius on the stage, with the reference end pixel coordinates stored in a storage unit that stores the reference end pixel coordinates in association with each reference radius; a third step of calculating pixel coordinates of a predetermined corner end portion corresponding to a position of the edge at a predetermined angle from a predetermined angle image captured by the imaging unit when the test wafer is rotated by the predetermined angle; a fourth step of calculating a difference between the calculated pixel coordinates of the predetermined corner end at the predetermined angle and the reference radius of the edge of the test wafer at the predetermined angle based on the calculated pixel coordinates of the predetermined corner end at the predetermined angle and the reference radius of the test wafer; A measurement method that includes:

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

7. In the first step, calculating an amount of eccentricity from the center of the test wafer based on the edge image; In the third step, moving the test wafer in the radial direction on the stage so as to cancel out the eccentricity amount that is set to the predetermined angle when the predetermined angle image is captured; calculating pixel coordinates of the predetermined corner end portion at the predetermined angle of the test wafer moved in the radial direction; The measurement method according to claim 5 .

8. A fifth step of performing a marking process on a predetermined position on the test wafer is further included. In the fifth step, the predetermined position is identified based on the predetermined angle and a distance from the edge of the test wafer at the predetermined angle; The measurement method according to any one of claims 5 to 7.

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