Wafer edge area measuring device and method

Abstract

The invention discloses a wafer edge area measuring device and method, and the device comprises a first light path structure which is used for illuminating a first to-be-measured area at the edge of a wafer from the front side, and the first to-be-measured area comprises an EBR milling edge line; the second light path structure is used for illuminating a second to-be-detected area at the edge of the wafer from the back, the second to-be-detected area comprises an edge vertex, and the second to-be-detected area and the first to-be-detected area are arranged back to back relative to the wafer; the image acquisition unit is used for carrying out reflected light imaging on the first to-be-detected area and carrying out correlation light imaging on the second to-be-detected area to obtain a to-be-detected image containing a milling edge line and an edge vertex; and the processing unit is used for calculating the width of the EBR operation area according to the imaging position relation between the edge milling line and the edge vertex in the to-be-detected image. The edge milling line of the EBR and the wafer edge area are imaged in the same image, accurate measurement of the width of the EBR operation area between the edge milling line and the edge vertex is achieved, and the measurement error is reduced.

Description

Technical Field

[0001] This application relates to the technical field of wafer detection, and particularly to a wafer edge region measurement device and method. Background Art

[0002] When spin-coating photoresist on a wafer, the photoresist is thrown to the edge of the substrate, resulting in a thicker photoresist at the wafer edge than in the middle region. It will fall off during subsequent process steps, affecting subsequent process steps such as exposure and development, so it needs to be removed. Currently, the method for removing the photoresist at the wafer edge in the lithography process mainly uses the EBR (Edge Bead Removal) method. After the EBR operation, the effect on the wafer edge region still needs to be measured by optical imaging to determine whether the operation width of the EBR meets the process requirements.

[0003] However, in the existing method, the bright-field illumination method is generally used to detect the front EBR line, that is, the circular line near the edge slope on the front of the wafer, which is the contour line (the milling edge line of the EBR) left after the EBR operation. As Figure 1 shown, when using a detector to collect the image of the EBR operation area at the wafer edge, the reflection angles of the illumination light in the planar area and the inclined area at the wafer edge are different, resulting in the reflection light in the inclined area of the wafer not being collected by the detector. Furthermore, the radial width from the EBR line to the vertex of the wafer edge cannot be measured, thus affecting the accuracy of the EBR test data. Summary of the Invention

[0004] In view of this, this application provides a wafer edge region measurement device and a wafer edge region measurement method to solve the problem of inaccurate measurement results of the width of the EBR operation area after removing the photoresist at the wafer edge.

[0005] To solve the above technical problems, a technical solution adopted in this application is: providing a wafer edge region measurement device, which includes: a first optical path structure for illuminating a first measurement area at the wafer edge from the front, the first measurement area including the milling edge line of the EBR; a second optical path structure for illuminating a second measurement area at the wafer edge from the back, the second measurement area including the edge vertex, and the second measurement area is arranged opposite to the first measurement area with respect to the wafer; an image acquisition unit for imaging the reflected light of the first measurement area and imaging the incident light of the second measurement area to obtain a measurement image including the milling edge line and the edge vertex; and a processing unit for calculating the width of the EBR operation area according to the imaging position relationship between the milling edge line and the edge vertex in the measurement image.

[0006] As a further improvement of the present application, the first area to be measured covers the planar area and the inclined area of the wafer edge, and the milling line is provided in the planar area of the wafer edge; the first optical path structure includes a first illumination source, and the first illumination light emitted by the first illumination source is incident on the first area to be measured at an incident angle less than 90°, and is reflected at different angles in the planar area and the inclined area of the wafer edge, and only the light beam reflected by the planar area of the wafer edge is configured to reach the image acquisition unit.

[0007] As a further improvement of the present application, the second optical path structure includes a second illumination source, and the second illumination light emitted by the second illumination source is incident on the second area to be measured, and a part of the second illumination light directly reaches the image acquisition unit along the edge vertex.

[0008] As a further improvement of the present application, the second illumination light is configured as parallel light, and the optical axis of the second illumination light forms a preset angle with the wafer surface.

[0009] As a further improvement of the present application, an optical path turning component is further included, and the optical path turning component is arranged in the outer space on the back side of the wafer and is used to guide the second illumination light emitted by the second illumination source to the second area to be measured in a turning manner.

[0010] As a further improvement of the present application, the optical path turning component includes a first reflector and a second reflector. The first reflector is used to receive the second illumination light and guide the second illumination light to the second reflector, and the second reflector is used to redirect the second illumination light to the second area to be measured.

[0011] As a further improvement of the present application, the image acquisition unit includes a CCD camera and is used to receive the optical signals of the first optical path structure and the second optical path structure simultaneously.

[0012] As a further improvement of the present application, a rotating platform is further included and is used to carry the wafer and realize 360° rotation. The rotating platform drives the wafer to rotate one week, and all the images of the wafer edge are collected by the image acquisition unit.

[0013] To solve the above technical problems, another technical solution adopted in this application is: to provide a method for measuring the edge region of a wafer, which is applied to the wafer edge region measuring device described above. The wafer edge region measuring device includes a first optical path structure, a second optical path structure, an image acquisition unit, and a processing unit; the method includes: the first optical path structure illuminates a first region to be measured on the edge of the wafer from the front, and the second optical path structure synchronously illuminates a second region to be measured on the edge of the wafer from the back. The first region to be measured includes the milling line of the EBR, and the second region to be measured includes the edge vertex, and the second region to be measured is arranged opposite to the first region to be measured with respect to the wafer; the image acquisition unit performs reflected light imaging on the first region to be measured and performs opposed light imaging on the second region to be measured, and obtains a to-be-measured image including the milling line and the edge vertex; the processing unit calculates the width of the EBR operation region according to the imaging position relationship between the milling line and the edge vertex in the to-be-measured image.

[0014] The beneficial effects of this application are: The wafer edge region measuring device of this application uses the first optical path structure to irradiate the first region to be measured on the edge of the wafer from the front to detect the milling line of the EBR, and uses the second optical path structure to irradiate the second region to be measured on the edge of the wafer from the back of the wafer to detect the edge vertex of the wafer, so that the milling line of the EBR and the edge vertex of the wafer are in the same image through front bright-field imaging and opposed imaging. Finally, the processing unit accurately calculates the width of the EBR operation region according to the distance between the milling line of the EBR and the edge vertex, reducing the measurement error of the EBR, and at the same time, it can also overcome the limitation that only the width of the region between the milling line of the EBR and the edge bevel line can be obtained by directly using the front bright-field imaging method in the existing method. Description of the Drawings

[0015] Figure 1 is a schematic diagram of a cross-sectional structure of the wafer edge of the present invention; Figure 2 is a schematic structural diagram of an embodiment of the wafer edge region measuring device of the present invention; Figure 3 is a schematic diagram of the optical axis of an embodiment of the wafer edge region measuring device of the present invention; Figure 4 is another schematic diagram of the cross-sectional structure of the wafer edge of the present invention, where (a) is a schematic diagram of an arc-shaped edge, and (b) is a schematic diagram of the combination of an arc-shaped inclined surface and a vertical vertex; Figure 5 is a schematic diagram of the image collected when only the first optical path structure irradiates; Figure 6 is a schematic diagram of the image collected when the first optical path structure and the second optical path structure irradiate simultaneously; Figure 7It is a schematic flowchart of an embodiment of the method for measuring the edge region of a wafer according to the present invention; Among them, the reference numerals in the figure are as follows: 1. First optical path structure; 2. Second optical path structure; 21. Second illumination light source; 22. Optical path turning assembly; 221. First reflector; 222. Second reflector; 3. Image acquisition unit; 4. Processing unit. Detailed implementation manners

[0016] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0017] The terms "first", "second", and "third" in the present application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", and "third" may explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined. All directional indications (such as up, down, left, right, front, back...) in the embodiments of the present application are only used to explain the relative spatial positions and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0018] Referring to "embodiment" in this article means that the specific features, structures, or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0019] Figure 2 It is a schematic structural diagram of the wafer edge region measuring device according to the embodiment of the present invention. As Figure 2As shown in the figure, the wafer edge region measuring device includes a first optical path structure 1, a second optical path structure 2, an image acquisition unit 3, and a processing unit 4.

[0020] Among them, the first optical path structure 1 is used to illuminate the first area to be measured on the edge of the wafer from the front (please refer to Figure 1 ), and the first area to be measured includes the milling line of the EBR.

[0021] The second optical path structure 2 is used to illuminate the second area to be measured on the edge of the wafer from the back (please refer to Figure 1 ), the second area to be measured includes the edge vertex, and the second area to be measured is arranged opposite to the first area to be measured with respect to the wafer.

[0022] The image acquisition unit 3 is used to perform reflected light imaging on the first area to be measured and perform transmitted light imaging on the second area to be measured, and obtain a to-be-measured image containing the milling line and the edge vertex.

[0023] The processing unit 4 is electrically connected to the image acquisition unit 3 and is used to calculate the width of the EBR operation area according to the imaging position relationship between the milling line and the edge vertex in the to-be-measured image.

[0024] Specifically, the first optical path structure 1 is preferably arranged in the outer space on the front side of the wafer, and is used to emit the first illumination light to the front side of the wafer, form a front bright field illumination on the first area to be measured on the edge of the front side of the wafer, the reflected light of the front illumination of the first area to be measured is collected by the image acquisition unit 3, and reflected light imaging is performed on the first area to be measured. The second optical path structure 2 is preferably arranged in the outer space on the back side of the wafer, and the second optical path structure 2 is used to emit the second illumination light to the second area to be measured on the back side of the wafer, the second illumination light is collected by the image acquisition unit 3, and transmitted light imaging is performed on the second area to be measured. It should be noted that the image acquisition unit 3 synchronously collects the optical signals of the first optical path structure 1 and the second optical path structure 2, and synchronously realizes reflected light imaging on the first area to be measured and transmitted light imaging on the second area to be measured, so as to obtain a to-be-measured image containing the milling line and the edge vertex. Finally, the processing unit 4 calculates the width of the EBR operation area according to the distance between the milling line and the edge vertex in the to-be-measured image.

[0025] The wafer edge region measuring device of this embodiment irradiates the first region to be measured on the wafer edge by using the first optical path structure 1 from the front to detect the milling line of the EBR, and irradiates the second region to be measured on the wafer edge from the back of the wafer by using the second optical path structure 2 to detect the vertex of the wafer edge. Thus, the milling line of the EBR and the vertex of the wafer edge are in the same image through the front bright field imaging and the opposed imaging methods. Finally, the processing unit 4 accurately calculates the width of the EBR operation region according to the distance between the milling line of the EBR and the vertex of the wafer edge, reducing the measurement error of the EBR. At the same time, it can also overcome the limitation that only the width of the region between the milling line of the EBR and the edge bevel line can be obtained by the direct front bright field imaging method in the existing method.

[0026] Further, as Figure 1 shown, the first region to be measured covers the planar region and the inclined surface region of the wafer edge, and the milling line is provided in the planar region of the wafer edge.

[0027] The first optical path structure 1 includes a first illumination source. The first illumination light emitted by the first illumination source is incident on the first region to be measured at an incident angle less than 90°, and different angles of reflection occur in the planar region and the inclined surface region of the wafer edge (please refer to Figure 3 together). Only the light beam reflected by the planar region of the wafer edge is configured to reach the image acquisition unit 3. To improve the imaging effect, the first optical path structure further includes a collimating lens group, which can collimate the first illumination light, so that the collimated first illumination light is incident on the first region to be measured.

[0028] Specifically, please refer to Figure 2 , the incident angle of the first illumination light emitted by the first illumination source is an acute angle, that is, 0° < incident angle < 90°. The first illumination source irradiates the planar region and the inclined surface region of the first region to be measured. Due to the inclination angle of the inclined surface region, the reflection angle of the reflected light in the inclined surface region is different from the reflection angle of the reflected light in the planar region, and the image acquisition unit 3 is arranged on the path of the reflected light in the planar region. Thus, the image acquisition unit 3 will only collect the reflected light in the planar region and will not collect the reflected light in the inclined surface region.

[0029] It should be noted that there are other structural forms on the wafer edge in addition to the Figure 1 and Figure 3 shown edge structures. Other structural forms are still applicable to the wafer edge region measuring device provided in this application. Please refer to Figure 4, which shows another cross-sectional structure of the wafer edge. Among them, (a) is a schematic diagram of an arc-shaped edge, and (b) is a schematic diagram of the combination of an arc-shaped inclined plane and a vertical vertex. In figure (a), the edge of the wafer consists of a planar region, an arc-shaped inclined plane region, and an arc-shaped vertex. The arc-shaped vertex at the arc-shaped extended end forms the edge vertex. In figure (b), the edge of the wafer consists of a planar region, an arc-shaped inclined plane region, and a vertical plane region. Any point on the vertical plane region can form an edge vertex. Since the milling line of the EBR always exists in the planar region of the wafer edge, regardless of whether the shape of the inclined plane region of the wafer edge is a straight inclined plane or an arc-shaped inclined plane, it does not affect the first optical path structure in the wafer edge region measuring device to illuminate the planar region obliquely and perform surface reflection, and the image acquisition unit can image the entire planar region. Since the edge vertex of the wafer edge is on the outermost side of the edge, it is related to the width of the inclined plane region and has nothing to do with the shape of the inclined plane region. Therefore, the second optical path structure in the wafer edge region measuring device is used to perform counter-illumination on the edge vertex to find the position of the edge vertex, and the image acquisition unit can image the edge vertex. When the position of the edge bevel line does not need to be considered, as long as the pixel positions of the EBR milling line and the edge vertex are recognized in the image, the operating region width of the EBR can be obtained by conversion.

[0030] It can be understood that the wafer edge region measuring device provided by the present application can solve the measurement problem of the EBR operating region width of edges with different shapes, reduce the measurement error of the EBR, and at the same time can overcome the limitation that only the region width between the milling line of the EBR and the edge bevel line can be obtained by the direct front bright field imaging method in the existing method.

[0031] As Figure 5 shown, Figure 5 shows the image collected by the image acquisition unit 3 when only the first illumination light source irradiates. The position of the boundary line between the black region and the gray region in the figure is the dividing line between the planar region and the inclined plane region.

[0032] Furthermore, the second optical path structure 2 includes a second illumination light source 21. The second illumination light emitted by the second illumination light source 21 is directed towards the second region to be measured, and a part of the second illumination light directly reaches the image acquisition unit 3 along the edge vertex.

[0033] It should be noted that the illumination region of the second illumination light exceeds the boundary of the second region to be measured. As a result, a part of the second illumination light is blocked by the second region to be measured and will not be collected by the image acquisition unit 3, while the other part of the unblocked light beam irradiates the image acquisition unit 3 along the wafer edge vertex and is collected by the image acquisition unit 3. Thus, when the reflected light of the first illumination light and the second illumination light are collected by the image acquisition unit 3, it forms as Figure 6The image shown, where the first gray area corresponds to the second illumination light, the boundary line between the first gray area and the black area is the position of the vertex of the wafer edge, the black area is the bevel area, the boundary line between the black area and the second gray area is the dividing line between the flat area and the bevel area, and the milling line of the EBR is on the second gray area. By calculating the distance between the position of the vertex of the wafer edge and the milling line of the EBR in the image to be measured, the width of the EBR operation area can be obtained.

[0034] It should be noted that Figure 6 The positions of the vertex of the wafer edge and the milling line of the EBR are given in the image shown, and it is easy to obtain the number of pixels in the straight-line direction between the two. Since the numerical conversion relationship between a single pixel and the actual distance can be known according to the imaging magnification, the width of the EBR operation area can be calculated based on the number of pixels and the numerical conversion relationship.

[0035] Furthermore, in order to more accurately capture the position of the vertex of the wafer edge, the second illumination light is configured as parallel light, and the optical axis of the second illumination light forms a preset angle with the wafer surface.

[0036] Specifically, the second illumination light is configured as parallel light. The parallel light beam has direction consistency, which can reduce the light path diffusion and make the edge vertex form a high-contrast bright-dark boundary line on the detector (such as Figure 6 the boundary line between the first gray area and the black area in the figure), thereby improving the measurement resolution. It should be noted that in order to ensure clear imaging of the vertex of the wafer edge, the optical axis of the second illumination light has an axial relationship with the diameter of the wafer, so that the second illumination light can be irradiated onto the image acquisition unit 3 parallel to the plane where the vertex of the wafer edge is located. If the optical axis of the second illumination light does not have an axial relationship with the diameter of the wafer, the second illumination light may irradiate the side area of the vertex of the wafer edge (please refer to Figure 1 the figure shown), resulting in inaccurate positioning of the vertex of the wafer edge. It should be understood that while the optical axis of the second illumination light has an axial relationship with the diameter of the wafer, the optical axis of the second illumination light forms a preset angle with the wafer surface, such as an acute angle between the optical axis of the second illumination light and the wafer surface, so that the optical axis of the second illumination light is parallel to the optical axis of the reflected light of the first illumination light.

[0037] Furthermore, during the wafer detection process, the bottom space of the operation table is limited and there is no condition to install the second illumination source 21. Therefore, in some embodiments, the second optical path structure 2 further includes an optical path folding component 22. The optical path folding component 22 is arranged in the outer space on the back of the wafer and is used to guide the second illumination light emitted by the second illumination source 21 to the second area to be measured through a folding method.

[0038] Specifically, by arranging a reflector in the outer space on the back side of the wafer, the second illumination light emitted by the second illumination source 21 is guided to the second area to be measured, so that it is not necessary to arrange the second illumination source 21 in the outer space on the back side of the wafer.

[0039] It should be understood that the first optical path structure 1 can also be arranged at other spatial positions. By arranging a reflector, the illumination light emitted by the first optical path structure 1 can be guided to the first area to be measured.

[0040] Furthermore, in some embodiments, the optical path turning assembly 22 includes a first reflector 221 and a second reflector 222. The first reflector 221 is used to receive the second illumination light and guide the second illumination light to the second reflector 222, and the second reflector 222 is used to redirect the second illumination light to the second area to be measured.

[0041] Furthermore, the image acquisition unit 3 includes a CCD camera, which is used to simultaneously receive the optical signals of the first optical path structure 1 and the second optical path structure 2. The CCD camera here can be a line array imaging camera or a area array imaging camera.

[0042] Furthermore, the wafer edge region measuring device further includes a rotating platform, which is used to carry the wafer and realize 360° rotation. The rotating platform drives the wafer to rotate one week, and all the images of the wafer edge are acquired by the image acquisition unit 3.

[0043] Specifically, after the positions of the first optical path structure 1 and the second optical path structure 2 are calibrated, by placing the wafer on the rotating platform and using the rotating platform to drive the wafer to rotate, the wafer edge sequentially passes through the areas illuminated by the first optical path structure 1 and the second optical path structure 2, so as to complete the detection of all areas of the wafer edge.

[0044] Figure 7 It is a schematic structural diagram of the wafer edge region measuring method according to an embodiment of the present invention. The wafer edge region measuring method is applied to the wafer edge region measuring device in one of the above embodiments. The wafer edge region measuring device includes: a first optical path structure, a second optical path structure, an image acquisition unit, and a processing unit. As Figure 7 shown, the wafer edge region measuring method includes: Step S1: The first optical path structure illuminates the first area to be measured on the wafer edge from the front side, and the second optical path structure synchronously illuminates the second area to be measured on the wafer edge from the back side. The first area to be measured includes the milling line of the EBR, and the second area to be measured includes the edge vertex, and the second area to be measured is arranged opposite to the first area to be measured with respect to the wafer.

[0045] Step S2: The image acquisition unit performs reflected light imaging on the first area to be measured and transmitted light imaging on the second area to be measured, and obtains a to-be-measured image including the milling line and the edge vertex.

[0046] Step S3: The processing unit calculates the width of the EBR operation area according to the imaging position relationship between the milling line and the edge vertex in the image to be measured.

[0047] The method for measuring the wafer edge region in this embodiment irradiates the first region to be measured on the wafer edge by using the first optical path structure from the front to detect the milling line of the EBR, and irradiates the second region to be measured on the wafer edge from the back of the wafer by using the second optical path structure to detect the edge vertex of the wafer. Thus, through the front bright-field imaging and the opposed imaging method, the milling line of the EBR and the edge vertex of the wafer are in the same image. Finally, the processing unit accurately calculates the width of the EBR operation area according to the distance between the milling line of the EBR and the edge vertex of the wafer, reducing the measurement error of the EBR. At the same time, it can also overcome the limitation that only the width of the region between the milling line of the EBR and the edge bevel line can be obtained by the direct front bright-field imaging method in the existing method.

[0048] The above are only the implementation manners of the present application, and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present application.

Claims

1. A wafer edge region measuring device, characterized in that, It includes: A first optical path structure for illuminating a first area to be measured at the edge of the wafer from the front, where the first area to be measured includes the milling line of the EBR; A second optical path structure for illuminating a second area to be measured at the edge of the wafer from the back, where the second area to be measured includes the edge vertex, and the second area to be measured is arranged opposite to the first area to be measured with respect to the wafer; An image acquisition unit for performing reflected light imaging on the first area to be measured and performing transmitted light imaging on the second area to be measured, and acquiring a to-be-measured image including the milling line and the edge vertex; A processing unit for calculating the width of the EBR operation area according to the imaging position relationship between the milling line and the edge vertex in the to-be-measured image.

2. The wafer edge region measuring device according to claim 1, wherein, The first area to be measured covers the flat area and the inclined area at the edge of the wafer, and the milling line is arranged in the flat area at the edge of the wafer; The first optical path structure includes a first illumination source, and the first illumination light emitted by the first illumination source is incident on the first area to be measured at an incident angle less than 90°, and is reflected at different angles in the flat area and the inclined area at the edge of the wafer, and only the light beam reflected by the flat area at the edge of the wafer is configured to reach the image acquisition unit.

3. The wafer edge region measuring device according to claim 1, characterized in that The second optical path structure includes a second illumination source, and the second illumination light emitted by the second illumination source is incident on the second area to be measured, and a part of the second illumination light directly reaches the image acquisition unit along the edge vertex.

4. The wafer edge region measuring device according to claim 3, wherein, The second illumination light is configured as parallel light, and the optical axis of the second illumination light forms a preset angle with the wafer surface.

5. The wafer edge region measuring device according to claim 3, wherein It further includes an optical path turning component, which is arranged in the outer space on the back of the wafer and is used to guide the second illumination light emitted by the second illumination source to the second area to be measured in a turning manner.

6. The wafer edge region measuring device according to claim 5, characterized in that, The optical path turning component includes a first reflector and a second reflector. The first reflector is used to receive the second illumination light and guide the second illumination light to the second reflector, and the second reflector is used to redirect the second illumination light to the second area to be measured.

7. The wafer edge region measuring device according to claim 1, characterized in that, The image acquisition unit includes a CCD camera for simultaneously receiving the optical signals of the first optical path structure and the second optical path structure.

8. The wafer edge region measuring device according to claim 1, characterized in that, It further includes a rotating platform for carrying the wafer and realizing 360° rotation. The rotating platform drives the wafer to rotate one week, and all the images at the edge of the wafer are acquired by the image acquisition unit.

9. A method for measuring a wafer edge region, characterized in that, It is applied to the wafer edge area measuring device according to any one of claims 1-8. The wafer edge area measuring device includes a first optical path structure, a second optical path structure, an image acquisition unit and a processing unit; the method includes: The first optical path structure illuminates a first area to be measured at the edge of the wafer from the front, and the second optical path structure simultaneously illuminates a second area to be measured at the edge of the wafer from the back. The first area to be measured includes the milling line of the EBR, the second area to be measured includes the edge vertex, and the second area to be measured is arranged opposite to the first area to be measured with respect to the wafer; The image acquisition unit performs reflected light imaging on the first area to be measured and opposed light imaging on the second area to be measured, and acquires a to-be-measured image including the milling line and the edge vertices; The processing unit calculates the width of the EBR operation area according to the imaging position relationship between the milling line and the edge vertices in the to-be-measured image.

Images