Workpiece surface defect detection device based on dark field confocal microscopic imaging

Abstract

The invention discloses a workpiece surface defect detection device based on dark field confocal microscopic imaging, and the device comprises a first illumination assembly which is used for generating a first light beam which forms a first linear light spot on the surface of a to-be-detected workpiece; the second illumination assembly is used for generating a second light beam forming a second linear light spot on the surface of the to-be-detected workpiece; the imaging assembly is used for receiving scattered light generated after the first light beam and the second light beam irradiate the surface of the to-be-detected workpiece and generating a dark field microscopic image; and the image analysis assembly is used for analyzing the dark field microscopic image of the surface of the to-be-detected workpiece so as to determine whether the surface of the to-be-detected workpiece has defects or not. Illumination light paths are provided in different directions through the two groups of illumination assemblies, and finally two linear light spots are combined, so that the two linear light spots are completely overlapped or partially overlapped, multi-angle and high-energy-density collinear illumination is realized, and the reduction of the quality of a detection image caused by a single illumination direction can be effectively avoided.

Description

Technical Field

[0001] The present invention belongs to the field of intelligent manufacturing, and particularly relates to a workpiece surface defect detection device based on dark-field confocal microscopy. Background Art

[0002] During the manufacturing and processing of components such as wafers, surface defects such as scratch defects will have a significant impact on the quality and performance of the components. For example, scratches on the wafer surface will damage the surface flatness, affect the accuracy of lithography patterns, and may damage key circuit structures, resulting in short circuits or open circuits, reducing the reliability of the chip, etc. Therefore, the detection of scratches and other defects on the surface of the above components is very important.

[0003] In the prior art, the surface scratch detection of components such as wafers can be completed by a dark-field line confocal microscopy device. It uses a line laser as a light source, focuses the linear light beam on the workpiece sample to be detected, receives the scattered light emitted from surface defects such as scratches in a dark-field imaging environment, and uses a slit aperture to exclude the scattered light outside the focal plane, thereby enhancing the contrast and detection sensitivity at the surface defects.

[0004] However, the linear illumination light source used in the traditional dark-field line confocal microscopy device can only provide a single illumination direction, resulting in different intensities of scattered light generated when irradiating surface defects at different positions and depths. As a result, in the finally obtained image, the brightness of surface defects at different positions is different. For example, when the defect is a scratch approximately in a straight line, if the length direction of the scratch has a very small angle or is close to parallel to the laser incident direction, the scratch will have a higher brightness, while the scratch perpendicular to the laser incident direction will have a darker brightness, and defects such as scratches cannot be observed (as Figure 1 shown), which affects the detection result of the defect and is prone to missed detection. To avoid this defect, the laser line or the workpiece sample to be detected can be rotated to repeat the detection multiple times, but this will lead to a decrease in the detection efficiency. Summary of the Invention

[0005] To solve the above problems, the present invention proposes a workpiece surface defect detection device based on dark-field confocal microscopy, which provides illumination light paths in different directions through two groups of illumination components, and finally combines the two line light spots, so that the two line light spots completely overlap or partially overlap, realizing collinear illumination with multiple angles and high energy density, and effectively avoiding the degradation of the detection image quality caused by a single illumination direction.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] There is provided a workpiece surface defect detection device based on dark-field confocal microscopy, which includes:

[0008] A first illumination component for generating a first light beam that irradiates the surface of a workpiece to be detected, so as to form a first linear light spot on the surface of the workpiece to be detected, and the length direction of the first linear light spot is perpendicular to the optical axis of the first light beam;

[0009] A second illumination component for generating a second light beam that irradiates the surface of a workpiece to be detected, so as to form a second linear light spot on the surface of the workpiece to be detected, and the length direction of the second linear light spot is not perpendicular to the optical axis of the second light beam;

[0010] An imaging component for receiving the scattered light generated after the first light beam and the second light beam irradiate the surface of the workpiece to be detected, and generating a dark-field microscopic image of the surface of the workpiece to be detected based on the dark-field imaging principle;

[0011] And an image analysis component connected to the imaging component for analyzing the dark-field microscopic image of the surface of the workpiece to be detected to determine whether there are defects on the surface of the workpiece to be detected.

[0012] Preferably, the value range of the acute angle α1 formed by the optical axis of the first light beam and the surface of the workpiece to be detected is 20° to 40°.

[0013] Preferably, the value range of the acute angle α2 formed by the length direction of the second linear light spot and the optical axis of the second light beam is 45° to 70°.

[0014] Preferably, the projection of the optical axis of the first light beam on the horizontal plane is perpendicular to the projection of the optical axis of the second light beam on the horizontal plane.

[0015] Preferably, the central axis of the first linear light spot in its length direction and the central axis of the second linear light spot in its length direction completely coincide;

[0016] Or, the central axis of the first linear light spot in its length direction and the central axis of the second linear light spot in its length direction partially coincide;

[0017] Or, the central axis of the first linear light spot in its length direction and the central axis of the second linear light spot in its length direction are parallel to each other.

[0018] Preferably, the first illumination component includes:

[0019] A first laser for outputting a laser beam;

[0020] A first Powell prism for expanding the laser beam output by the first laser, and the ridge line direction is perpendicular to both the optical axis of the first light beam and the length direction of the first linear light spot to obtain a one-dimensional laser line;

[0021] and a first cylindrical lens group, which includes a plurality of cylindrical lenses and is used for focusing and shaping the one-dimensional laser line to obtain a first light beam irradiated on the surface of the workpiece to be detected.

[0022] Preferably, in the first cylindrical lens group, at least one cylindrical lens is perpendicular to the optical axis of the one-dimensional laser line and at least one cylindrical lens is used for converging the light beam expanded by the first Powell prism to control the length of the first line spot on the workpiece to be detected.

[0023] Preferably, the second illumination assembly includes:

[0024] a second laser, which is used for outputting a laser beam;

[0025] a second Powell prism, which is used for expanding the laser beam output by the second laser to obtain a one-dimensional laser line;

[0026] and a second cylindrical lens group, which includes a plurality of cylindrical lenses and is used for refracting and shaping the one-dimensional laser line to obtain a second light beam irradiated on the surface of the workpiece to be detected.

[0027] Preferably, in the second cylindrical lens group, the acute angle formed by the cylindrical lens farthest from the second laser and the optical axis of the one-dimensional laser line ranges from 45° to 70°.

[0028] The workpiece surface defect detection device according to claim 1, wherein the imaging assembly includes: a camera, a tube lens and an objective lens, wherein the camera, the tube lens and the objective lens are coaxially arranged; after the scattered light generated after the first light beam and the second light beam irradiate on the surface of the workpiece to be detected passes through the objective lens, it is converted into parallel light, and the parallel light passes through the tube lens and then enters the lens of the camera and is sensed by the sensor of the camera to generate a dark-field microscopic image.

[0029] The beneficial effects of the present invention are:

[0030] The optical path structure of the workpiece surface defect detection device in the present invention is simple and occupies a small space. It provides illumination optical paths in different directions through two groups of illumination assemblies, and finally combines the two line spots, so that the two line spots completely coincide or partially coincide, realizing collinear illumination with multiple angles and high energy density, which can effectively avoid the decline of the detection image quality caused by a single illumination direction, and at the same time greatly improve the detection ability of the dark-field line confocal detection system for workpiece surface defects in different directions, and significantly improve the detection quality and detection efficiency of the dark-field line confocal microscopic imaging detection. Description of the Drawings

[0031] Figure 1 is a dark-field microscopic image obtained by a dark-field line confocal microscopic imaging device in the prior art;

[0032] Figure 2 It is a schematic structural diagram of the workpiece surface defect detection device in the present invention;

[0033] Figure 3 It is a schematic structural diagram of the first lighting component in the present invention;

[0034] Figure 4 It is a schematic structural diagram of the second lighting component in the present invention;

[0035] Figure 5 It is a schematic diagram of the positional relationship between the first line light spot and the second line light spot in the present invention;

[0036] Figure 6a The first line light spot and the second line light spot in the present invention are Figure 5 The dark-field microscopic image obtained when they coincide in the form of part (a);

[0037] Figure 6b The first line light spot and the second line light spot in the present invention are Figure 5 The dark-field microscopic image obtained when they coincide in the form of part (b);

[0038] Figure 6c The first line light spot and the second line light spot in the present invention are Figure 5 The dark-field microscopic image obtained when they coincide in the form of part (c);

[0039] Figure 7 It is a schematic structural diagram of the imaging component in the present invention. Specific Embodiments

[0040] To make the purpose, technical solution and advantages of the present technical solution clearer and more understandable, the present technical solution will be further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are exemplary and not intended to limit the scope of the present technical solution.

[0041] Example 1:

[0042] This example provides a workpiece surface defect detection device based on dark-field confocal microscopy imaging, as shown in Figures 2-4 shown, which includes:

[0043] A first lighting component 1, which is used to generate a first light beam L1 that irradiates the surface of the workpiece P to be detected, so as to form a first line light spot 11 (the two endpoints of the first line light spot 11 are point A and point B) on the surface of the workpiece P to be detected, and the length direction Y1 of the first line light spot 11 is perpendicular to the optical axis L11 of the first light beam L1; at the same time, the included acute angle α1 formed by the optical axis L11 of the first light beam L1 and the surface of the workpiece P to be detected ranges from 20° to 40°; for example, as Figure 3As shown, in this embodiment, the length direction Y1 of the first linear light spot 11 may be the Y-axis direction;

[0044] The second illumination component 2 is used to generate a second light beam L2 that irradiates the surface of the workpiece P to be detected, so as to form a second linear light spot 21 (the two end points of the second linear light spot 21 are point C and point D) on the surface of the workpiece P to be detected. The included angle α2 between the length direction Y2 of the second linear light spot 21 and the optical axis L21 of the second light beam L2 ranges from 45° to 70°; and the projection of the optical axis L11 of the first light beam L1 on the horizontal plane is perpendicular to the projection of the optical axis L21 of the second light beam L2 on the horizontal plane; As Figure 1 shown, the projection of the optical axis L11 of the first light beam L1 on the horizontal plane extends along the X-axis, and the projection of the optical axis L21 of the second light beam L2 on the horizontal plane extends along the Y-axis, then the two optical axes are perpendicular to each other;

[0045] The imaging component 3 is used to receive the scattered light generated after the first light beam L1 and the second light beam L2 irradiate the surface of the workpiece P to be detected, and generate a dark-field microscopic image of the surface of the workpiece P to be detected based on the dark-field imaging principle;

[0046] And the image analysis component 4 is connected to the imaging component 3, and is used to analyze the dark-field microscopic image of the surface of the workpiece P to be detected to determine whether there are defects on the surface of the workpiece P to be detected and determine the defect type. In this embodiment, the workpiece P to be detected includes a wafer, and the defects include one or several of scratches, depressions, and protrusions; At the same time, the process of determining whether there are defects on the surface of the workpiece P to be detected and determining the defect type can be completed based on algorithms such as a neural network model, which belongs to the prior art and will not be elaborated here, or can be determined manually after scaling the dark-field microscopic image;

[0047] Among them, both the first linear light spot 11 and the second linear light spot 21 are rectangular. Further, as Figure 5 shown, the central axis Y11 of the first linear light spot 11 in its length direction Y1 and the central axis Y21 of the second linear light spot 21 in its length direction Y2 completely coincide (as shown in part (a) of Figure 5 ), and the widths of the first linear light spot 11 and the second linear light spot 21 are the same / different, and the lengths of the first linear light spot 11 and the second linear light spot 21 are the same; The central axis Y11 of the first linear light spot 11 in its length direction Y1 refers to the connection line of the midpoints of the two short sides of the first linear light spot 11. Similarly, the central axis Y21 of the second linear light spot 21 in its length direction Y2 refers to the connection line of the midpoints of the two short sides of the second linear light spot 21;

[0048] Or, the central axis Y11 of the first line-shaped light spot 11 in its length direction Y1 and the central axis Y21 of the second line-shaped light spot 21 in its length direction Y2 partially overlap (as shown in part (b) of Figure 5 ), and the widths of the first line-shaped light spot 11 and the second line-shaped light spot 21 are the same / different, and the lengths of the first line-shaped light spot 11 and the second line-shaped light spot 21 are the same / different;

[0049] Or, the central axis Y11 of the first line-shaped light spot 11 in its length direction Y1 and the central axis Y21 of the second line-shaped light spot 21 in its length direction Y2 are parallel to each other (as shown in part (c) of Figure 5 ), and the widths of the first line-shaped light spot 11 and the second line-shaped light spot 21 are the same / different, and the lengths of the first line-shaped light spot 11 and the second line-shaped light spot 21 are the same / different. At the same time, the first line-shaped light spot 11 and the second line-shaped light spot 21 partially overlap.

[0050] Therefore, in this embodiment, two groups of lighting components provide illumination light paths in different directions (such as in the X-axis direction and the Y-axis direction respectively), and finally the two line-shaped light spots are combined, so that the two line-shaped light spots completely overlap or partially overlap, realizing collinear illumination with multiple angles and high energy density, so as to increase the light intensity of a specific area on the workpiece surface, reduce the requirements for the maximum power of a single line-shaped light spot light source (such as a laser) and the damage threshold requirements of each element in the light path, improve the safety of the overall light path, greatly improve the detection ability of the dark-field line confocal detection system for workpiece surface defects in different directions, and reduce the number of detections in different illumination directions.

[0051] When the first line-shaped light spot 11 and the second line-shaped light spot 21 overlap in the three forms of (a), (b), and (c) in Figure 5 respectively, the corresponding dark-field microscopic images as shown in Figures 6a-6c are obtained. It can be seen from this that compared with the images obtained by the existing dark-field line confocal microscopy equipment (as shown in Figure 1 ), the dark-field microscopic images in this embodiment can show clear scratches (as shown in the square box in Figures 6a-6c ).

[0052] Embodiment 2:

[0053] The difference between this embodiment and Embodiment 1 is only that, as shown in Figures 2-3 , the first lighting component 1 includes:

[0054] A first laser 12, which is used to output a laser beam;

[0055] The first Powell prism 13 is used to expand the laser beam output by the first laser 12 along the length direction of the first line spot 11, and the ridge line direction is perpendicular to both the optical axis L11 of the first light beam L1 and the length direction Y1 of the first line spot, so as to obtain a one-dimensional laser line;

[0056] And the first cylindrical lens group 14, which includes a plurality of cylindrical lenses 141, is used to focus and shape the one-dimensional laser line to obtain the first light beam L1 irradiated on the surface of the workpiece P to be detected, and the first light beam L1 forms the first line spot 11 on the surface of the workpiece P to be detected; at the same time, to ensure that the length direction Y1 of the first line spot 11 is perpendicular to the optical axis L11 of the first light beam L1, so that the first light beam L1 is further converged in the direction perpendicular to the length direction Y1. In the first cylindrical lens group 14, at least one cylindrical lens 141 is perpendicular to the optical axis of the one-dimensional laser line and at least one cylindrical lens 141 is used to converge the light beam expanded by the first Powell prism 13 to control the length of the first spot 11 on the workpiece P to be detected (i.e., the length of the line segment AB);

[0057] As Figure 2 , as shown in FIG. 4, the second illumination assembly 2 includes:

[0058] The second laser 22 is used to output a laser beam;

[0059] The second Powell prism 23 is used to expand the laser beam output by the second laser 22 to obtain a one-dimensional laser line;

[0060] And the second cylindrical lens group 24, which includes a plurality of cylindrical lenses, is used to refract and shape the one-dimensional laser line to obtain the second light beam L2 irradiated on the surface of the workpiece P to be detected, and the second light beam L2 forms the second line spot 21 on the surface of the workpiece P to be detected; at the same time, to ensure that the second line spot 21 is coplanar with the surface of the workpiece P to be detected, and the first line spot 11 and the second line spot 21 completely or partially overlap. In the second cylindrical lens group 24, the acute angle formed by the cylindrical lens 241 farthest from the second laser 22 and the optical axis of the one-dimensional laser line is also α2, so that the illumination light can converge on the surface of the workpiece P to be detected that is not perpendicular to the optical axis L21, so as to realize multi-angle and high-energy-density collinear illumination.

[0061] Embodiment 3:

[0062] The difference between this embodiment and Embodiment 1 or 2 is only that, as Figure 7As shown, the imaging component 3 includes: a camera 31, a tube lens 32, and an objective lens 33. Among them, the camera 31 is a TDI (Time Delay Integration) camera, and the camera 31, the tube lens 32, and the objective lens 33 are coaxially arranged; after the scattered light generated after the first light beam L1 and the second light beam L2 irradiate the surface of the workpiece P to be detected passes through the objective lens 33, it is converted into parallel light. The parallel light enters the lens of the camera 31 after passing through the tube lens 32 and is sensed by the sensor of the camera 31 to generate a dark-field microscopic image.

[0063] At the same time, the distance from the objective lens 33 to the surface of the workpiece P to be detected is the same as the working distance of the objective lens 33, whereby it can be ensured that the parallel light entering the lens of the camera 31 can be accurately focused, ensuring the clarity of imaging and reducing energy loss.

[0064] Embodiment 4:

[0065] The difference between this embodiment and any one of Embodiments 1-3 is only that, as Figure 2 , shown in FIG. 7, the workpiece surface defect detection device further includes:

[0066] A moving platform 5, which is used to carry the workpiece P to be detected and drive the workpiece P to move along the X-axis, Y-axis, or Z-axis.

[0067] In summary, the optical path structure of the workpiece surface defect detection device in the present invention is simple, occupies little space, is convenient to construct and maintain. It provides illumination optical paths in different directions through two groups of illumination components, and finally combines the two line light spots, so that the two line light spots completely overlap or partially overlap, realizing collinear illumination with multiple angles and high energy density. It can effectively avoid the decline in the quality of the detection image caused by a single illumination direction, and at the same time greatly improves the detection ability of the dark-field line confocal detection system for workpiece surface defects in different directions, significantly improving the detection quality and detection efficiency of dark-field line confocal microscopic imaging detection.

[0068] The above content is only the preferred embodiment of the present invention. For those of ordinary skill in the art, according to the idea of the technical content of the present application, many changes can be made in the specific implementation manner and application scope. As long as these changes do not depart from the concept of the present invention, they all belong to the protection scope of this patent.

Claims

1. A workpiece surface defect detection device based on dark field confocal microscopy, characterized in that: include: A first lighting assembly, which is used to generate a first light beam that is irradiated on the surface of the workpiece to be inspected to form a first line light spot on the surface of the workpiece to be inspected, and the length direction of the first line light spot is perpendicular to the optical axis of the first light beam; A second lighting assembly is used to generate a second light beam that is irradiated on the surface of the workpiece to be inspected to form a second line light spot on the surface of the workpiece to be inspected, and the length direction of the second line light spot is not perpendicular to the optical axis of the second light beam; An imaging component, which is used to receive scattered light generated after the first light beam and the second light beam are irradiated onto the surface of the workpiece to be inspected, and generate a dark field microscopic image of the surface of the workpiece to be inspected based on the dark field imaging principle; And an image analysis component, which is connected to the imaging component and is used to analyze the dark field microscopic image of the surface of the workpiece to be inspected to determine whether there are defects on the surface of the workpiece to be inspected.

2. The workpiece surface defect detection device according to claim 1, characterized in that: The acute angle α1 formed between the optical axis of the first light beam and the surface of the workpiece to be detected ranges from 20° to 40°.

3. The workpiece surface defect detection device according to claim 1, characterized in that: The value range of the acute angle α2 formed by the length direction of the second line light spot and the optical axis of the second light beam is 45° to 70°.

4. The workpiece surface defect detection device according to claim 1, characterized in that: The projection of the optical axis of the first light beam on the horizontal plane and the projection of the optical axis of the second light beam on the horizontal plane are perpendicular to each other.

5. The workpiece surface defect detection device according to claim 1, characterized in that: The central axis of the first line light spot in the length direction and the central axis of the second line light spot in the length direction completely coincide with each other; Or, the central axis of the first line light spot in the length direction and the central axis of the second line light spot in the length direction partially overlap; Alternatively, a central axis of the first line light spot in its length direction and a central axis of the second line light spot in its length direction are parallel to each other.

6. The workpiece surface defect detection device according to claim 1, characterized in that: The first lighting assembly comprises: A first laser, which is used to output a laser beam; A first Powell prism is used to expand the laser beam output by the first laser, and the prism direction is perpendicular to the optical axis of the first beam and the length direction of the first line spot to obtain a one-dimensional laser line; And a first cylindrical mirror group, which includes a plurality of cylindrical mirrors, is used to focus and shape the one-dimensional laser line to obtain a first light beam irradiated on the surface of the workpiece to be detected.

7. The workpiece surface defect detection device according to claim 6, characterized in that: In the first cylindrical mirror group, at least one cylindrical mirror is perpendicular to the optical axis of the one-dimensional laser line and at least one cylindrical mirror is used to converge the light beam expanded by the first Powell prism to control the length of the first line spot on the workpiece to be measured.

8. The workpiece surface defect detection device according to claim 1, characterized in that: The second lighting assembly comprises: a second laser for outputting a laser beam; a second Powell prism, used for expanding the laser beam output by the second laser to obtain a one-dimensional laser line; and a second cylindrical mirror group, which includes a plurality of cylindrical mirrors and is used for refracting and shaping the one-dimensional laser line to obtain a second light beam irradiated on the surface of the workpiece to be inspected.

9. The workpiece surface defect detection device according to claim 8, characterized in that: In the second cylindrical mirror group, the acute angle formed by the cylindrical mirror farthest from the second laser and the optical axis of the one-dimensional laser line ranges from 45° to 70°.

10. The workpiece surface defect detection device according to claim 1, characterized in that: The imaging component includes: a camera, a tube lens and an objective lens, wherein the camera, the tube lens and the objective lens are coaxially arranged; the scattered light generated after the first light beam and the second light beam are irradiated onto the surface of the workpiece to be inspected is converted into parallel light after passing through the objective lens, and the parallel light enters the camera lens after passing through the tube lens and is sensed by the sensor of the camera to generate a dark field microscopic image.

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