Surface inspection apparatus

Abstract

The application discloses a surface detection device, which comprises a transfer platform provided with a detection station for placing a wafer to be detected; and an image acquisition unit arranged above and / or below the detection station; wherein at least one of the transfer platform and the image acquisition unit is capable of linear reciprocating motion in the horizontal direction to adjust the positional relationship between the transfer platform and the image acquisition unit; the image acquisition unit comprises at least one camera module, the camera module comprises a camera, a ring-shaped light source arranged below a camera lens, a first light adjusting piece and a second light adjusting piece for adjusting the light brightness of the ring-shaped light source, the inner ring of the ring-shaped light source has a ring-shaped light emitting surface, the first light adjusting piece is located on the inner side of the ring-shaped light emitting surface, and the second light adjusting piece is located on the inner side of the first light adjusting piece.

Description

Technical Field

[0001] This application belongs to the field of testing equipment technology, specifically relating to a surface testing device for wafers. Background Technology

[0002] After wafer fabrication, surface defect inspection is required to ensure product quality. Currently, the mainstream inspection method involves capturing images of the wafer surface using a camera and then identifying defects through image analysis. However, the high flatness and strong reflectivity of wafer surfaces easily lead to significant specular reflection and glare during image acquisition, resulting in problems such as localized overexposure and washed-out highlights in the acquired images. This obscures minute surface defects and severely impacts image quality and the accuracy of subsequent defect analysis. Therefore, it is necessary to improve existing technologies to overcome these shortcomings. Summary of the Invention

[0003] Therefore, the technical problem to be solved by this application is to provide a surface inspection device.

[0004] To address the aforementioned technical problems, this application provides a surface inspection device for wafer inspection. The surface inspection device includes: a transfer stage with an inspection station for placing the wafer to be inspected; and an image acquisition unit located above and / or below the inspection station. At least one of the transfer stage and the image acquisition unit is capable of linear reciprocating motion in the horizontal direction to adjust the positional relationship between the transfer stage and the image acquisition unit. The image acquisition unit includes at least one camera module. The camera module includes a camera, a ring light source disposed below the camera lens, a first dimming element and a second dimming element for adjusting the brightness of the light emitted by the ring light source. The inner ring of the ring light source has a ring light-emitting surface. The first dimming element is located inside the ring light-emitting surface, and the second dimming element is located inside the first dimming element. The first dimming element is configured to partially block the annular light-emitting surface in the circumferential direction of the annular light source, so that the annular light-emitting surface is a notched annular light-emitting surface; the second dimming element is configured to partially block the annular light-emitting surface in the axial direction of the annular light source, so as to adjust the height dimension of the annular light-emitting surface in the axial direction.

[0005] In some embodiments, the annular light-emitting surface is a first inclined surface, which gradually approaches the optical axis from bottom to top. The first dimming element has a second inclined surface that fits with the annular light-emitting surface, and the second inclined surface abuts against the annular light-emitting surface. The central angle corresponding to the first dimming element is smaller than the central angle corresponding to the remaining portion of the annular light-emitting surface; or... The sum of the central angles corresponding to the first dimming element is less than the sum of the central angles corresponding to the remaining portion of the annular light-emitting surface.

[0006] In some embodiments, the image acquisition unit includes three camera modules that can be arranged to form an isosceles triangle. A pair of first dimming elements are provided on the camera module located at the vertex of the isosceles triangle, and a first dimming element is provided on each of the camera modules located at the base of the isosceles triangle. The arc length of the first dimming element on the camera module at the base is greater than the arc length of the first dimming element on the camera module at the vertex. The midpoints of the four first dimming elements on the three camera modules are connected to form an isosceles trapezoid. The midpoints of a pair of first dimming elements on the camera module at the apex form the short base of the isosceles trapezoid, and the midpoints of the two first dimming elements on the camera modules at the base corners form the long base of the isosceles trapezoid. The axis of symmetry of the isosceles trapezoid intersects perpendicularly with the optical axis of the camera module at the apex.

[0007] In some embodiments, the ratio of the short base, leg length, and long base of the isosceles trapezoid ranges from 1:2.2 to 2.6:3.6 to 4.2; and / or, The central angle A1 corresponding to the first dimming element on the camera module at the bottom corner is twice the central angle A2 corresponding to the first dimming element on the camera module at the top corner.

[0008] In some embodiments, the camera module further includes a light-shielding ring disposed on the inner ring of the ring light source, and the surface of the light-shielding ring is coated with an anti-reflective coating. The first dimming element is disposed on the bottom surface of the light-shielding ring, and the bottom surface of the light-shielding ring is flush with the top surface of the annular light-emitting surface, or the bottom surface of the light-shielding ring is located between the top and bottom of the annular light-emitting surface and is distributed close to the top. The second dimming element is disposed on the inner ring of the light-shielding ring, and a first adjustment structure is provided between the second dimming element and the light-shielding ring. The first adjustment structure is configured to adjust the position of the second dimming element on the axial direction of the ring light source.

[0009] In some embodiments, a mounting groove extending circumferentially is recessed on the outer ring of the light-shielding ring, and a set screw that mates with the mounting groove is provided on the annular light source. The annular light source is provided with a through hole for mounting the set screw, and the through hole penetrates the housing of the annular light source radially.

[0010] In some embodiments, the inner ring of the light-shielding ring is provided with a convex ring located at the top of the light-shielding ring, and the convex ring is configured to limit the range of light entering the camera lens.

[0011] In some embodiments, the bottom end face and the top end face of the convex ring are respectively provided with an annular first anti-reflective pad and a second anti-reflective pad, wherein the inner diameter of the first anti-reflective pad is equal to the inner diameter of the convex ring, the inner diameter of the second anti-reflective pad is smaller than the inner diameter of the convex ring, and the bottom of the inner ring of the convex ring is provided with a chamfer.

[0012] In some embodiments, the first dimming element is in the shape of an arc-shaped block, and the second dimming element is in the shape of a collar, wherein the surfaces of the first dimming element and the second dimming element are provided with an anti-reflective coating.

[0013] In some embodiments, the transfer stage includes a support plate having a first central hole, a plurality of telescopic claw structures disposed on the top surface of the support plate, and a first partition plate disposed on the support plate and located above the telescopic claw structures, wherein the first partition plate has a second central hole opposite to the first central hole, and the second central hole is coaxially distributed with the first central hole; The second central hole is further provided with a first ring body, which is distributed along the edge of the second central hole, wherein the inner diameter of the first ring body is larger than the inner diameter of the wafer to be tested; The first partition and a portion of the first ring body are treated with anti-glare surface treatment. The surface treatment areas on the first partition and the first ring body are located in the acquisition direction of the camera module and can cooperate with the first dimming component and the second dimming component.

[0014] The technical solution provided in this application has the following advantages: In this application, both the first dimming element and the second dimming element are light-blocking dimming structures. They are coaxially nested along the optical axis of the camera lens. By blocking part of the light path of the annular light-emitting surface, they control the amount of light transmitted, the illumination range and stray light of the illumination light entering the lens, so as to optimize the imaging contrast and avoid the edge image exposure of the wafer. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1A three-dimensional structural diagram of the surface inspection equipment provided in this application from a first-view perspective; Figure 2 A three-dimensional structural diagram of the surface inspection device provided in this application from a second perspective; Figure 3 A schematic diagram of the 3D structure of the camera module; Figure 4 for Figure 3 A schematic diagram of the decomposed structure; Figure 5 for Figure 3 A schematic diagram of the cross-sectional structure; Figure 6 This is a schematic diagram of edge exposure for wafer images in the prior art; Figure 7 A schematic diagram of edge exposure of a wafer image acquired by the surface inspection equipment of this application; Figure 8 A schematic diagram showing the distribution structure of the three camera modules; Figure 9 A schematic diagram of an isosceles trapezoid formed by connecting the midpoints of the first dimming elements on the three camera modules; Figure 10 This is a schematic diagram of the structure of the light-shielding ring from a first-view perspective. Figure 11 This is a schematic diagram of the structure of the light-shielding ring from a second perspective. Figure 12 This is a schematic diagram of the ring light source structure; Figure 13 This is a schematic diagram of the partitioning of the wafer to be inspected; Figure 14 This is a schematic diagram of the three-dimensional structure of the transfer stage; Figure 15 for Figure 14 A schematic diagram of the decomposed structure; Figure 16 This is a schematic diagram showing the positional relationship between the support plate and the telescopic claw structure; Figure 17 A three-dimensional structural diagram of the telescopic claw structure; Figure 18 This is a schematic diagram showing the exploded structure between the first partition and the first ring body. Figure 19 This is a schematic diagram of the support structure. Detailed Implementation

[0017] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. The application will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0018] It should be noted that the terms "first," "second," etc., in the specification, claims, and drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0019] In this application, unless otherwise stated, directional terms such as "upper," "lower," "top," and "bottom" are generally used in relation to the direction shown in the accompanying drawings, or in relation to the vertical, perpendicular, or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this application.

[0020] This application provides a surface inspection device for wafer inspection, specifically for detecting the surface quality of wafers. Of course, the surface inspection device includes, but is not limited to, wafer inspection; it can also be used to inspect the surface quality of other products, such as highly reflective precision parts.

[0021] like Figures 1 to 5 As shown, the surface inspection equipment includes a transfer stage 100 and an image acquisition unit. The transfer stage 100 is provided with an inspection station for placing the wafer 300 to be inspected, and the image acquisition unit is used to acquire surface image information of the wafer 300 to be inspected.

[0022] The image acquisition unit can be located above, below, or both above and below the inspection station. When the image acquisition unit is located above the inspection station, it can acquire image information of the upper surface of the wafer 300 to be inspected; when located below the inspection station, it can acquire image information of the lower surface of the wafer 300; and when located above and below the inspection station, it can simultaneously acquire image information of both the upper and lower surfaces of the wafer 300. Preferably, the image acquisition unit is located both above and below the inspection station.

[0023] At least one of the transfer stage 100 and the image acquisition unit can perform linear reciprocating motion in the horizontal direction to adjust the positional relationship between the transfer stage 100 and the image acquisition unit, thereby changing the positional relationship between the image acquisition unit and the inspection station, so as to ensure that the image acquisition unit can acquire the image information of the wafer 300 to be inspected on the inspection station.

[0024] The image acquisition unit includes at least one camera module 200. The camera module 200 includes a camera 210, a ring light source 220 disposed below the lens of the camera 210, and a first dimming element 231 and a second dimming element 240 for adjusting the brightness of the light emitted by the ring light source 220. Specifically, the inner ring of the ring light source 220 has an annular light-emitting surface 221, the first dimming element 231 is located inside the annular light-emitting surface 221, and the second dimming element 240 is located inside the first dimming element 231.

[0025] In existing technologies, during wafer image acquisition, the edges of the wafer image are often overexposed, resulting in excessive brightness. This is because, when a ring light source illuminates the wafer at an oblique angle, most of the reflected light from the center of the wafer deviates from the lens optical axis, with only a small amount of diffusely reflected light entering the lens, leading to low image brightness. However, the edges of the wafer, being rounded or chamfered surfaces, reflect light directly back to the lens via specular reflection, creating strong reflected light and causing the edge exposure to be significantly higher than the center. Figure 6 This is a schematic diagram of edge exposure for wafer images in the prior art.

[0026] In this application, both the first dimming element 231 and the second dimming element 240 are light-blocking dimming structures. They are coaxially nested along the optical axis of the camera 210 lens. By blocking part of the light path of the annular light-emitting surface 221, they control the amount of light transmitted through the incident lens, the illumination range, and stray light, thereby optimizing image contrast and preventing edge image exposure of the wafer. (Appendix) Figure 7 This is a schematic diagram of edge exposure of a wafer image acquired by the surface inspection equipment of this application. Figure 6 and Figure 7 As can be seen, in the prior art, without the first dimming element 231 and the second dimming element 240, the brightness difference between the center and the edge of the wafer is extremely large. However, by setting the first dimming element 231 and the second dimming element 240, the brightness of the center and the edge of the wafer 300 to be inspected tends to be consistent, providing a reliable guarantee for the detection of surface defects on the wafer.

[0027] In this application, the first dimming element 231 is configured to partially block the annular light-emitting surface 221 of the ring light source 220 in the circumferential direction, so that the annular light-emitting surface 221 is a notched annular light-emitting surface (not a completely circular ring). The second dimming element 240 is configured to partially block the annular light-emitting surface 221 of the ring light source 220 in the axial direction, thereby adjusting the height dimension of the annular light-emitting surface 221 in the axial direction. It is worth noting that in this application, "circumferential," "axial," and "radial" refer to the "circumferential," "axial," and "radial" directions of the ring light source 220 or the lens of the camera 210, wherein the aforementioned "axial" direction can be understood as the direction of the optical axis.

[0028] Specifically, the first dimming element 231 is in the shape of an arc-shaped block and is arranged circumferentially along the annular light-emitting surface 221. It can block a portion of the circumferential area of ​​the annular light-emitting surface 221, thereby adjusting the effective illumination range of the annular light-emitting surface 221. It is worth noting that the first dimming element 231 always blocks a portion of the circumferential area of ​​the annular light-emitting surface 221.

[0029] In this application, the annular light-emitting surface 221 is a first inclined surface, and in the direction from bottom to top, the annular light-emitting surface 221 gradually approaches the optical axis. For example... Figure 5 and Figure 10 As shown, the first dimming element 231 has a second inclined surface 2311 that fits with the annular light-emitting surface 221. The second inclined surface 2311 abuts against the annular light-emitting surface 221, thereby achieving partial circumferential shading of the annular light-emitting surface 221.

[0030] Preferably, the top of the second inclined surface 2311 is flush with the top of the annular light-emitting surface 221, and the bottom surface of the second inclined surface 2311 is flush with the bottom of the annular light-emitting surface 221. Thus, the surface of the annular light-emitting surface 221 within the circumferential region acted upon by the second inclined surface 2311 is completely blocked. Alternatively, the top of the second inclined surface 2311 may be lower than the top of the annular light-emitting surface 221, and the bottom of the second inclined surface 2311 may be higher than the bottom of the annular light-emitting surface 221. Another option is that the top of the second inclined surface 2311 is lower than the top of the annular light-emitting surface 221, and the bottom of the second inclined surface 2311 is flush with the bottom of the annular light-emitting surface 221. Yet another option is that the top of the second inclined surface 2311 is higher than the top of the annular light-emitting surface 221, and the bottom of the second inclined surface 2311 is higher than the bottom of the annular light-emitting surface 221.

[0031] When the ring light source 220 is equipped with only one first dimming element 231, the central angle corresponding to the first dimming element 231 is smaller than the central angle corresponding to the remaining portion of the ring light-emitting surface 221. When the ring light source 220 is equipped with two or more first dimming elements 231, the sum of the central angles corresponding to the first dimming elements 231 is smaller than the sum of the central angles corresponding to the remaining portion of the ring light-emitting surface 221, thereby ensuring that the ring light source 220 has sufficient light-emitting area and preventing insufficient illumination brightness due to excessive obstruction, which would affect the imaging effect.

[0032] Furthermore, the first dimming element 231 has a first state when it slides (rotates) circumferentially around the ring light source 220 and a second state when it is fixed relative to the ring light source 220. The first dimming element 231 can switch between the first and second states. That is, the circumferential position of the first dimming element 231 is adjustable, and the operator can adjust the circumferential shading area of ​​the first dimming element 231 according to actual usage needs to limit the effective lighting range to adapt to different application scenarios.

[0033] like Figure 4 As shown, the second dimming element 240 is in the shape of a ring. The axial position of the second dimming element 240 is adjustable. The second dimming element 240 has at least a first axial position where its bottom end face is flush with the top of the annular light-emitting surface 221, and a second axial position where its bottom end face is flush with the bottom of the annular light-emitting surface 221. The surfaces of the first dimming element 231 and the second dimming element 240 are provided with an anti-reflective coating, which can further improve the absorption efficiency of stray light. The light-shielding areas of the first dimming element 231 and the second dimming element 240 are matched with the lens field of view, ensuring effective illumination while minimizing the incidence of ineffective light.

[0034] When the second dimming element 240 is in the first axial position, it does not block the light path of the annular light-emitting surface 221, and therefore does not affect the brightness of the annular light-emitting surface 221. Although the second dimming element 240 does not affect the brightness of the annular light-emitting surface 221 when in the first axial position, it can act as an inner barrier to reduce or prevent light from the light source, reflected light, etc., from reaching the lens or the precision components behind the lens. At this time, the first dimming element 231 blocks part of the circumferential area of ​​the annular light-emitting surface 221, adjusting the effective illumination range; while the second dimming element 240 does not block the annular light-emitting surface 221, it can suppress stray light in the inner space of the annular light source 220.

[0035] When the second dimming element 240 is located in the second axial position, it blocks part of the light path of the ring light source 220. At this time, the second dimming element 240 not only acts as an inner wall barrier, but also reduces the light output brightness of the ring light-emitting surface 221. It works in conjunction with the first dimming element 231 to adjust the light output amount and light output area of ​​the ring light source 220 in both axial and circumferential directions, suppressing overexposure at the edge of the wafer 300 under test. This solves the problem of "overexposure at the edge and underexposure at the center" in traditional ring light source testing, and significantly improves the imaging contrast and detection accuracy of the wafer 300 under test.

[0036] Specifically, the second dimming element 240 moves between a first axial position and a second axial position. Notably, the second dimming element 240 also has multiple third axial positions between the first and second axial positions. In the third axial position, the bottom surface of the second dimming element 240 is located between the top and bottom of the annular light-emitting surface 221. The closer the bottom surface of the second dimming element 240 is to the bottom of the annular light-emitting surface 221, the greater its light-blocking ability.

[0037] Through the circumferential light regulation of the first light regulating member 231 and the axial light regulation of the second light regulating member 240, the present application forms a variety of switchable working state combinations, which can independently or coordinately regulate the illumination range and light transmission amount of the annular light source 220. It can not only effectively suppress overexposure at the edge of the wafer and improve the imaging quality, but also has strong scene adaptability and expansibility.

[0038] As Figure 8 and Figure 9 shown, the number of camera modules 200 is preferably three. The three camera modules 200 can enclose an isosceles triangle, or it can be understood that the three camera modules 200 are arranged in a "pin" shape. The following takes the image acquisition unit having three camera modules 200 as an example for illustration. However, based on the above description, it can be known that the protection scope of the present application is not limited thereby. The number of camera modules 200 can also be four, five, six, etc.

[0039] The distribution of the three camera modules 200 in an isosceles triangle can be highly matched with the optical path of the annular light source 220, effectively avoiding overexposure and uneven light at the edge of the wafer 300 to be detected, and significantly improving the imaging quality and detection stability. The symmetric structure of the isosceles triangle makes the distances and angles from the three camera modules 200 to the center of the wafer 300 to be detected similar, and the imaging conditions are basically the same, which is beneficial to improving the brightness and distortion consistency of multi-camera images, while simplifying the calibration of internal and external parameters of the camera and improving the accuracy of three-dimensional reconstruction and stitching. Compared with the linear arrangement or rectangular arrangement, the isosceles triangle layout is more compact, can achieve a larger effective field of view in a limited installation space, and at the same time makes the center of gravity of the whole machine more stable and has stronger anti-vibration and anti-impact performance.

[0040] In the present application, as Figure 8 shown, a pair of first light regulating members 231 are arranged on the camera module 200 at the apex angle position of the isosceles triangle, and one first light regulating member 231 is arranged on each of the camera modules 200 at the base angle positions of the isosceles triangle. Among them, the arc length of the first light regulating member 231 on the camera module 200 at the base angle position is greater than the arc length of the first light regulating member 231 on the camera module 200 at the apex angle position. As Figure 9 shown, the central angle A1 corresponding to the first light regulating member 231 on the camera module 200 at the base angle position is twice the central angle A2 corresponding to the first light regulating member 231 on the camera module 200 at the apex angle position. For example, the central angle A1 is 45°, and the central angle A2 is 22.5°.

[0041] The midpoints of the four first dimming elements 231 on the three camera modules 200 form an isosceles trapezoid. Specifically, the midpoints of a pair of first dimming elements 231 on the apex of the camera module 200 form the shorter base of the isosceles trapezoid, and the midpoints of the two first dimming elements 231 on the base of the camera module 200 form the longer base. The axis of symmetry M of the isosceles trapezoid intersects perpendicularly with the optical axis of the camera module 200 at the apex.

[0042] The isosceles trapezoidal arrangement of the three camera modules 200 ensures that the dimming areas of the three camera modules 200 are axially symmetrically distributed around the wafer 300 to be inspected, thus guaranteeing the uniformity of illumination of the wafer 300 to be inspected throughout the entire field of view. On the other hand, the geometric constraints of the isosceles trapezoid and the camera optical axis form a stable spatial reference, ensuring that the imaging conditions of each camera are consistent, thus ensuring the accuracy and stability of subsequent image stitching and defect detection.

[0043] The ratio of the short base, waist length, and long base of the aforementioned isosceles trapezoid ranges from 1:2.2 to 2.6:3.6 to 4.2. Preferably, the ratio is 1:2.4:3. This ratio allows for the formation of a visual baseline of appropriate length between adjacent camera modules 200, ensuring reasonable overlap of the fields of view of the three camera modules 200, facilitating image stitching and fusion. Simultaneously, it improves the matching between the distribution of the first dimming element 231 and the illumination area of ​​the ring light source, enhancing the uniformity of illumination across the entire area of ​​the wafer 300 under inspection and further suppressing edge overexposure. Here, the aforementioned "visual baseline" refers to the straight-line distance between the optical axes of adjacent camera modules 200, specifically the distance between the top corner camera module 200 and the left bottom corner camera module 200, and the distance between the top corner camera module 200 and the right bottom corner camera module 200.

[0044] In this application, the angle A3 between the first dimming element 231 on the bottom corner camera module 200 and the axis of symmetry M of the isosceles trapezoid is an acute angle, and the angle A4 between the first dimming element 231 on the top corner camera module 200 and the axis of symmetry M of the isosceles trapezoid is also an acute angle, wherein the angle A3 is smaller than the angle A4.

[0045] To further improve the stray light suppression capability of the inner space of the ring light source 220 and minimize the multi-level reflection of light in the aforementioned inner space, thereby making the illumination path cleaner and the imaging background more uniform, the camera module 200 also includes a light-shielding ring 230 disposed on the inner ring of the ring light source 220, the surface of which is coated with an anti-reflective coating.

[0046] like Figure 10 and Figure 11As shown, the first dimming element 231 is disposed on the bottom surface of the light-shielding ring 230. Below the bottom surface of the light-shielding ring 230 is an arc-shaped empty area located on the same circumference as the first dimming element 231. Light emitted from the area on the annular light-emitting surface 221 that is not blocked by the first dimming element 231 passes through the aforementioned empty area and is directed toward the wafer 300 to be tested. The bottom surface of the light-shielding ring 230 is flush with the top surface of the annular light-emitting surface 221, or the bottom surface of the light-shielding ring 230 is located between the top and bottom of the annular light-emitting surface 221, and is distributed closer to the top.

[0047] When the bottom surface of the light-shielding ring 230 is located between the top and bottom of the annular light-emitting surface 221, the bottom of the light-shielding ring 230 can block the light path of the annular light-emitting surface 221 in the circumferential direction. At this time, the bottom of the light-shielding ring 230 has the same function as the second dimming element 240, and the light-shielding ring 230 and the second dimming element 240 together form a two-stage blocking structure in the axial direction.

[0048] Preferably, the first dimming element 231 and the light-shielding ring 230 are integrally formed. The first dimming element 231 and the light-shielding ring 230 are made of the same material, and both the surface of the first dimming element 231 and the light-shielding ring 230 are provided with an anti-reflective coating.

[0049] In this application, as Figure 3 and Figure 5 As shown, the second dimming element 240 is disposed on the inner ring of the light-shielding ring 230. The inner ring of the first dimming element 231 and the outer ring of the second dimming element 240 are located on the same circumference, so that there is no gap between the two in the radial direction, forming a seamless geometric boundary and preventing light from leaking from the seam.

[0050] In order to adjust the position of the second dimming element 240 in the axial direction, a first adjustment structure 250 is provided between the second dimming element 240 and the light-shielding ring 230. The first adjustment structure 250 is used to adjust the position of the second dimming element 240 in the axial direction of the ring light source 220.

[0051] like Figure 3 As shown, the first adjustment structure 250 includes an oblong hole 251 on the second dimming element 240 and an adjusting bolt 252 inserted into the oblong hole 251. The light-shielding ring 230 has a hole 234 that mates with the adjusting bolt 252, and the oblong hole 251 extends axially. When it is necessary to adjust the axial position of the second dimming element 240, the adjusting bolt 252 is loosened, the second dimming element 240 is moved to the desired position, and then the adjusting bolt 252 is tightened. The operation and use are convenient.

[0052] In this application, as Figure 4 and Figure 10As shown, a mounting groove 232 extending circumferentially is recessed on the outer ring of the light-shielding ring 230, and a set screw 260 that mates with the mounting groove 232 is provided on the ring light source 220. The ring light source 220 is provided with a through hole 222 for mounting the set screw 260, and the through hole 222 penetrates the housing of the ring light source 220 radially.

[0053] When it is necessary to adjust the position of the first dimming element 231 in the circumferential direction, loosen the set screw 260 but not completely disengage it from the mounting slot 232. At this time, the light-shielding ring 230 can rotate freely in the circumferential direction, thereby facilitating the adjustment of the position of the first dimming element 231 in the circumferential direction. After the position of the first dimming element 231 in the circumferential direction is determined, tighten the set screw 260 to restrict the degree of freedom of the light-shielding ring 230 in the circumferential direction, thus fixing the light-shielding ring 230 relative to the ring light source 220.

[0054] like Figure 3 and Figure 4 As shown, the ring light source 220 is mounted on the lens via a bracket 290. A second adjustment structure (not shown) is provided between the bracket 290 and the lens. The second adjustment structure can adjust the axial position of the bracket 290. The second adjustment structure can be the same as the first adjustment structure 250, or other structures that can adjust the axial position of the bracket 290 can be selected.

[0055] like Figure 5 As shown, a convex ring 233 is fixed to the top of a light-shielding ring 230. The distance between the top surface of the convex ring 233 and the lens in the axial direction is a first spacing K. A first light-shielding cavity is formed between the convex ring 233, the bracket 290, and the lens of the camera 210. The axial dimension of the first light-shielding cavity is the aforementioned first spacing K. The size of the first spacing K can be adjusted by the second adjustment structure, thereby realizing the dynamic adjustment of the axial dimension of the first light-shielding cavity. The aforementioned dynamic adjustment can precisely control the stray light suppression intensity of the first light-shielding cavity and the effective light intake of the lens of the camera 210, thereby adapting to the imaging requirements of wafers with different surfaces and different detection scenarios. At the same time, it can also compensate for the processing and assembly errors of the lens of the camera 210 and the light-shielding ring 230, and can work with the second dimming component 240 to form a multi-dimensional fine dimming system, improving imaging contrast, brightness uniformity, and detection accuracy.

[0056] like Figure 19 As shown, the bracket 290 includes a sleeve 2901 disposed on the outer ring of the lens of the camera 210 and a mounting ring 2902 disposed at the bottom end of the sleeve 2901. The second adjustment structure is disposed between the sleeve 2901 and the lens of the camera 210, and the ring light source 220 is disposed on the mounting ring 2902.

[0057] The bracket 290 uses the lens of the camera 210 as a positioning reference to achieve coaxial mounting of the ring light source 220 and the lens, ensuring uniform illumination and image stability. In addition, the sleeve 2901 and the mounting ring 2902 can form a closed light-shielding space, which, together with the light-shielding ring 230 and the convex ring 233, further suppresses stray light from entering the lens and improves image quality.

[0058] In this application, as Figure 5 and Figure 11 As shown, the inner ring of the light-blocking ring 230 has a convex ring 233, which is located at the top of the light-blocking ring 230 and is configured to limit the range of light entering the lens of the camera 210. On the one hand, the convex ring 233 can form a three-level axial blocking structure with the first dimming element 231 and the second dimming element 240. On the other hand, the convex ring 233 can form a physical block at the light-incident end of the lens, accurately limiting the effective light-incident field of view of the lens, blocking ambient stray light and diffused light outside the ring light-emitting surface 221 from entering the lens, and greatly improving image contrast and sharpness. Furthermore, the convex ring 233 can serve as a physical limiting structure for the lens, preventing mechanical collisions between the lens and the structure inside the ring light source 220 during assembly and adjustment, while also preventing damage to the lens from direct exposure to the ring light source 220.

[0059] In this application, the convex ring 233 and the light-shielding ring 230 are integrally formed without additional assembly, which simplifies the number of parts and assembly process, avoids the coaxiality error of the split structure, and helps to improve structural stability and processing consistency.

[0060] Furthermore, such as Figure 4 and Figure 5 As shown, the bottom and top surfaces of the convex ring 233 are respectively provided with a first anti-reflective pad 270 and a second anti-reflective pad 280. The inner diameter of the first anti-reflective pad 270 is equal to the inner diameter of the convex ring 233, and the inner diameter of the second anti-reflective pad 280 is smaller than the inner diameter of the convex ring 233.

[0061] The second anti-reflective pad 280 has a smaller inner diameter and forms a shield on the top surface of the convex ring 233. The inner ring of the second anti-reflective pad 280 can serve as a physical limiting boundary for light entering the lens, precisely limiting the effective field of view of the lens, blocking stray light from entering the field of view, and further optimizing image quality.

[0062] The second anti-reflective pad 280 and the first anti-reflective pad 270 form an axial stepped structure. The second anti-reflective pad 280 is responsible for absorbing reflected light from the lens side, while the first anti-reflective pad 270 is responsible for extinction of light from the ring light source 220 side. The first anti-reflective pad 270 and the second anti-reflective pad 280 form a double extinction barrier along the optical axis, which can achieve full-angle coverage absorption of stray light from different directions and paths.

[0063] The bottom of the inner ring of the convex ring 233 is chamfered 2331. If the chamfer 2331 is not provided, the bottom of the inner ring of the convex ring 233 is originally a right angle. The chamfer turns the right angle into a bevel, allowing stray light to be scattered obliquely into the inner space of the ring light source 220, thereby achieving the purpose of suppressing stray light.

[0064] In this application, the surface inspection device further includes a substrate 400, and a transfer stage 100 disposed on the substrate 400. In one embodiment, the transfer stage 100 is capable of linear reciprocating motion on the substrate 400. Further, the linear reciprocating motion of the transfer stage 100 is in the horizontal direction.

[0065] Specifically, such as Figure 15 and Figure 16 As shown, a first linear drive mechanism 410 is provided on the substrate 400, and a transfer stage 100 is disposed on the first linear drive mechanism 410. The first linear drive mechanism 410 drives the transfer stage 100 to perform linear reciprocating motion in the X-axis direction. When the image acquisition unit is working, the detection station on the transfer stage 100 moves linearly reciprocating under the drive of the first linear drive mechanism 410. In one embodiment, the camera 210 is a line scan camera, and the detection station is located below the camera 210. The wafer 300 to be inspected moves continuously below the camera 210 along a preset path to achieve line scan imaging inspection. The aforementioned "preset path" is a movement path parallel to the X-axis direction.

[0066] like Figure 1 and Figure 2 As shown, a support frame 420 is also provided on the substrate 400, and the image acquisition unit is mounted on the substrate 400 via the support frame 420. Furthermore, a second linear drive mechanism 421 is also provided on the support frame 420, and the image acquisition unit is mounted on the second linear drive mechanism 421. The second linear drive mechanism 421 drives the image acquisition unit to perform linear reciprocating motion in the Y-axis direction.

[0067] In another embodiment, the transfer stage 100 remains stationary at a preset position, and the second linear drive mechanism 421 drives the camera module 200 to perform linear reciprocating motion in the Y-axis direction to achieve line scan imaging inspection of the wafer 300 to be inspected. The following description uses the example of the transfer stage 100 performing linear reciprocating motion in the X-axis direction to achieve line scan operation on the wafer 300 to be inspected. The function of the second linear drive mechanism 421 is to change the positions of the three camera modules 200 to perform line scans on different areas of the wafer to be inspected.

[0068] In this application, the diameter of the wafer 300 to be inspected is 300 mm, and the field of view of the camera 210 is 51 mm. For example... Figure 13As shown, the wafer 300 to be inspected is divided into six strip-shaped regions extending along the X-axis. Along the Y-axis, these six regions are designated L1, L2, L3, L4, L5, and L6. The inspection process involves two line scans. First, three cameras 210 perform line scans on regions L1, L3, and L5 respectively. Second, the three cameras 210 perform line scans on regions L2, L4, and L6, thus acquiring an image of the entire wafer 300. After the first line scan, the second linear drive mechanism 421 moves the three camera modules 200 synchronously to the left or to the right a preset distance, moving the three cameras 210 from above regions L1, L3, and L5 to above regions L2, L4, and L6. Then, the first linear drive mechanism 410 drives the transfer stage 100 to move continuously below the three cameras 210, thereby completing the line scan operation.

[0069] like Figure 1 and Figure 2 As shown, in order to precisely adjust the position of the camera module 200 on the X, Y, and Z axes, the camera module 200 is mounted on the second linear drive mechanism 421 via a slide module 430. Each camera module 200 is paired with one slide module 430; that is, three camera modules 200 are equipped with three slide modules 430, with each camera module 200 having its own slide module 430. The slide module 430 has adjustable displacement along the X, Y, and Z axes, allowing for independent and precise fine-tuning of the X, Y, and Z axis positions of a single camera module 200 without needing to coordinate with other camera modules 200.

[0070] In this application, as Figure 16 As shown, the transfer stage 100 includes a support plate 110 with a first central hole 111 and multiple telescopic claw structures 120 disposed on the top surface of the support plate 110. The multiple telescopic claw structures 120 are distributed along the first central hole 111. The support plate 110 is disposed on a first linear drive mechanism 410. The diameter of the first central hole 111 is larger than the diameter of the wafer to be inspected. The wafer to be inspected is located within the first central hole 111, and the position of the first central hole 111 is the inspection station of the transfer stage 100.

[0071] like Figure 17 As shown, the telescopic claw structure 120 includes at least a linear drive mechanism 121, an actuator 122 connected to the linear drive mechanism 121, and a claw portion 123 located at the free end of the actuator 122. The actuator 122 moves radially along the first central hole 111 under the drive of the linear drive mechanism 121, thereby realizing the extension or retraction of the claw portion 123.

[0072] When the wafer to be tested is placed on the claw 123, the claw 123 is in the extended state. When the claw 123 is in the extended state, the claw 123 is at least partially located inside the first central hole 111 and is distributed close to the edge of the first central hole 111.

[0073] The claw 123 is mounted on the actuator 122 via a connecting block 124. The claw 123 and the connecting block 124 are detachably connected to facilitate periodic replacement of the claw 123, thereby avoiding material waste caused by replacing the actuator 122 and the claw 123 together. The claw 123 is provided with an "L"-shaped notch 1231, and the edge of the wafer to be inspected is supported at the notch 1231.

[0074] The "L"-shaped notch 1231 has a horizontal support surface and a vertical limiting surface. The horizontal support surface and the vertical limiting surface can form a bidirectional limiting mechanism, realizing precise positioning of the wafer under test and preventing the wafer from shifting or shaking during the test, ensuring that the wafer under test is always in the optimal imaging position. At the same time, the "L"-shaped notch 1231 only contacts a small area of ​​the edge of the wafer under test, minimizing the obstruction of the effective detection area of ​​the wafer under test and avoiding missed defects.

[0075] The carrier plate 110 is also provided with a clearance opening 112, which is connected to the first central hole 111. The clearance opening 112 provides movement space for the robot (not shown), so that the robot can smoothly place the wafer to be tested onto the claw 123.

[0076] The telescopic claw structure 120 also includes a guide module 125, which is used to ensure that the actuator 122 moves in the radial direction along the first central hole 111. The guide module 125 includes a guide seat 1251 and a linear bearing 1252 disposed on the guide seat 1251, wherein the linear bearing 1252 is sleeved on the actuator 122, and the actuator 122 is slidably disposed on the guide seat 1251 through the linear bearing 1252.

[0077] The transfer platform 100 also includes a first partition 130 disposed on the support plate 110 and located above the telescopic claw structure 120. The first partition 130 has a second center hole 131 opposite to the first center hole 111, and the second center hole 131 is coaxially distributed with the first center hole 111. The diameter of the second center hole 131 is equal to the diameter of the first center hole 111.

[0078] Furthermore, such as Figure 18 As shown, a first ring body 132 is also provided inside the second central hole 131, and the first ring body 132 is distributed along the edge of the second central hole 131. The inner diameter of the first ring body 132 is larger than the inner diameter of the wafer to be inspected, so as to prevent the first ring body 132 from blocking the wafer to be inspected.

[0079] A portion of the first partition 130 and the first ring body 132 undergoes surface anti-sparking treatment. Specifically, a layer of polytetrafluoroethylene (PTFE, commonly known as Teflon) is coated on a portion of the surface of the first partition 130. The PTFE layer has low reflectivity and high absorption characteristics, which can effectively suppress stray light generated during wafer inspection and prevent stray light from entering the lens of the camera 210.

[0080] The edge of the second central hole 131 is prone to specular reflection and diffraction stray light. The first ring body 132 adopts a better surface treatment (e.g., matte black anodizing) to better eliminate the strong reflection stray light at the second central hole 131.

[0081] Specifically, a portion of the surface of the first ring 132 is coated with a matte black anodized layer. This matte black anodized layer effectively absorbs stray light in the optical path, suppresses specular reflection, avoids image overexposure, and further improves the wafer surface imaging quality and defect detection accuracy. The lens of the camera 210 is directly facing the second central hole 131. Stray light reflected from the second central hole 131 is most likely to directly enter the lens of the camera 210, causing image overexposure.

[0082] Preferably, the surface-treated areas on the first partition 130 and the surface-treated areas on the first ring body 132 are distributed at the same circumferential angle. For example, if the surface-treated areas on the first partition 130 are distributed at the nine o'clock position, then the surface-treated areas on the first ring body 132 are also distributed at the nine o'clock position.

[0083] In one embodiment, such as Figure 18 As shown, the surface-treated areas on the first partition 130 and the first ring 132 are located at region B. Region B is located in the line scanning direction (acquisition direction) of the camera module 200 and can cooperate with the first dimming element 231 and the second dimming element 240. In one embodiment, the camera module 200 performs line scanning along the X-axis direction, and region B is located in the X-axis direction.

[0084] Region B is located directly above the clearance opening 112. Region B is an axisymmetric figure, with its axis of symmetry B1 passing through the center of the second central hole 131, and B1 being parallel or collinear with the axis of symmetry M of the aforementioned isosceles trapezoid. The inner boundary of Region B is the inner ring of the first annular body 132, and the outer boundary is the outer edge of the first partition 130. Region B has a length of 230 mm in the Y-axis direction and a width of 100.26 mm in the X-axis direction. The length of Region B in the Y-axis direction is greater than the long base of the aforementioned isosceles trapezoid.

[0085] When a camera module 200 is located below the inspection station, a second partition 140 is also located below the support plate 110. The second partition 140 has a third central hole (not shown), and a second ring (not shown) is located within the inner circle of the third central hole, distributed along the edge of the third central hole. The inner diameter of the second ring is larger than the inner diameter of the wafer 300 to be inspected, to prevent the second ring from obstructing the wafer 300. The structure of the second partition 140 is the same as that of the first partition 130, and the structure of the second ring is the same as that of the first ring 132; these details will not be elaborated upon here.

[0086] It is worth noting that the second partition 140 and the second ring body are also coated, and the type and location of the coating are consistent with the type and location of the coating on the first partition 130 and the first ring body 132.

[0087] Obviously, the embodiments described above are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, those skilled in the art can make other variations or modifications without creative effort, and all such variations or modifications should fall within the scope of protection of this application.

Claims

1. A surface inspection device for wafer inspection, characterized in that, include: The transfer stage (100) is equipped with a testing station for placing the wafer (300) to be tested; An image acquisition unit is located above and / or below the detection station; Among them, at least one of the transfer stage (100) and the image acquisition unit is capable of linear reciprocating motion in the horizontal direction to adjust the positional relationship between the transfer stage (100) and the image acquisition unit; The image acquisition unit includes at least one camera module (200). The camera module (200) includes a camera (210), a ring light source (220) disposed below the lens of the camera (210), a first dimming element (231) and a second dimming element (240) for adjusting the output brightness of the ring light source (220). The inner ring of the ring light source (220) has an annular light-emitting surface (221). The first dimming element (231) is located inside the annular light-emitting surface (221), and the second dimming element (240) is located inside the first dimming element (231). The first dimming element (231) is configured to block part of the annular light-emitting surface (221) in the circumferential direction of the annular light source (220) so that the annular light-emitting surface (221) is a notched annular light-emitting surface; The second dimming element (240) is configured to partially block the annular light-emitting surface (221) in the axial direction of the annular light source (220) to adjust the height dimension of the annular light-emitting surface (221) in the axial direction.

2. The surface inspection device as described in claim 1, characterized in that, The annular light-emitting surface (221) is a first inclined surface. In the direction from bottom to top, the annular light-emitting surface (221) gradually approaches the optical axis. The first dimming element (231) has a second inclined surface (2311) that fits with the annular light-emitting surface (221). The second inclined surface (2311) abuts against the annular light-emitting surface (221). Wherein, the central angle corresponding to the first dimming element (231) is smaller than the central angle corresponding to the remaining part on the annular light-emitting surface (221); or, The sum of the central angles corresponding to the first dimming element (231) is less than the sum of the central angles corresponding to the remaining part on the annular light-emitting surface (221).

3. The surface inspection device as described in claim 1, characterized in that, The image acquisition unit includes three camera modules (200), which can be arranged to form an isosceles triangle. A pair of first dimming elements (231) are provided on the camera module (200) located at the vertex of the isosceles triangle, and a first dimming element (231) is provided on each of the camera modules (200) located at the base of the isosceles triangle. The arc length of the first dimming element (231) on the camera module (200) at the base is greater than the arc length of the first dimming element (231) on the camera module (200) at the vertex is greater. The midpoints of the four first dimming elements (231) on the three camera modules (200) are connected to form an isosceles trapezoid. The midpoints of a pair of first dimming elements (231) on the camera module (200) at the apex form the short base of the isosceles trapezoid. The midpoints of the two first dimming elements (231) on the camera module (200) at the base corner form the long base of the isosceles trapezoid. The axis of symmetry of the isosceles trapezoid intersects perpendicularly with the optical axis of the camera module (200) at the apex.

4. The surface inspection device as described in claim 3, characterized in that, The ratio of the short base, leg length, and long base of the isosceles trapezoid ranges from 1:2.2 to 2.6:3.6 to 4.2; and / or, The central angle A1 corresponding to the first dimming element (231) on the camera module (200) at the bottom corner position is twice the central angle A2 corresponding to the first dimming element (231) on the camera module (200) at the top corner position.

5. The surface inspection device as described in claim 1, characterized in that, The camera module (200) also includes a light-shielding ring (230) disposed on the inner ring of the ring light source (220), and the surface of the light-shielding ring (230) is coated with an anti-reflective coating. The first dimming element (231) is disposed on the bottom end surface of the light-shielding ring (230). The bottom end surface of the light-shielding ring (230) is flush with the top of the annular light-emitting surface (221). Alternatively, the bottom end surface of the light-shielding ring (230) is located between the top and bottom of the annular light-emitting surface (221) and is distributed close to the top. The second dimming element (240) is disposed on the inner ring of the light-shielding ring (230), and a first adjustment structure (250) is provided between the second dimming element (240) and the light-shielding ring (230). The first adjustment structure (250) is configured to adjust the position of the second dimming element (240) in the axial direction of the ring light source (220).

6. The surface inspection device as described in claim 5, characterized in that, The outer ring of the light-shielding ring (230) has a recessed mounting groove (232) extending circumferentially. The annular light source (220) is provided with a set screw (260) that mates with the mounting groove (232). The annular light source (220) is provided with a through hole (222) for mounting the set screw (260). The through hole (222) penetrates the housing of the annular light source (220) radially.

7. The surface inspection device as described in claim 5, characterized in that, The inner ring of the light-shielding ring (230) is provided with a convex ring (233), which is located at the top of the light-shielding ring (230) and is configured to limit the range of light entering the lens of the camera (210).

8. The surface inspection device as described in claim 7, characterized in that, The bottom and top surfaces of the convex ring (233) are respectively provided with a first anti-reflective pad (270) and a second anti-reflective pad (280). The inner diameter of the first anti-reflective pad (270) is equal to the inner diameter of the convex ring (233), and the inner diameter of the second anti-reflective pad (280) is smaller than the inner diameter of the convex ring (233). The bottom of the inner ring of the convex ring (233) is provided with a chamfer (2331).

9. The surface inspection device as described in claim 1, characterized in that, The first dimming element (231) is in the shape of an arc block, and the second dimming element (240) is in the shape of a ring. The surfaces of the first dimming element (231) and the second dimming element (240) are provided with an anti-reflective coating.

10. The surface inspection device as described in claim 1, characterized in that, The transfer stage (100) includes a support plate (110) with a first central hole (111), a plurality of telescopic claw structures (120) on the top surface of the support plate (110), and a first partition plate (130) on the support plate (110) and above the telescopic claw structures (120). The first partition plate (130) has a second central hole (131) opposite to the first central hole (111), and the second central hole (131) is coaxially distributed with the first central hole (111). The second central hole (131) is further provided with a first ring body (132), which is distributed along the edge of the second central hole (131), wherein the inner diameter of the first ring body (132) is larger than the inner diameter of the wafer (300) to be tested; Partial areas of the first partition (130) and the first ring (132) are treated with anti-glare surface treatment. The surface treatment areas on the first partition (130) and the first ring (132) are located in the acquisition direction of the camera module (200) and can cooperate with the first dimming element (231) and the second dimming element (240).

Images