A dark field defect detection device

Abstract

The present invention discloses a dark-field defect detection device, which relates to the field of optical detection technology. The dark-field defect detection device includes a first illumination optical system, a first reflector, and an imaging system; the first illumination optical system is configured to emit a dark-field illumination beam, which is incident from the end face of the object to be tested to the interior of the object to be tested; the imaging system is configured to image the light beam emitted from the upper surface or lower surface of the object to be tested; and the first reflector is configured to reflect the light beam emitted from the end face of the object to be tested back into the object to be tested. The embodiments of the present invention improve energy utilization, save costs, and increase the adjustability and flexibility of detection.

Description

Technical Field

[0001] The present invention relates to the field of optical detection technology, and in particular to a dark field defect detection device. Background Art

[0002] In the precision manufacturing industry, due to the complexity and diversity of production processes, minor local defects such as pores, scratches, and cracks may occur on the surface and inside of products during machine processing and manual operation, resulting in product defects. To ensure product yield, defect detection is particularly important.

[0003] In practical applications, defects on the mask exist not only on the surface but also within the mask. Commonly used defect detection optical paths require high installation precision and are complex. Furthermore, commonly used implementation methods are relatively simple, making it difficult to accommodate diverse detection methods. Summary of the Invention

[0004] The embodiment of the present invention provides a dark field defect detection device, which reduces the complexity of the defect detection optical path, reduces the precision requirements of mechanical installation, and improves the utilization rate of light energy.

[0005] An embodiment of the present invention provides a dark field defect detection device, comprising a first illumination optical system, a first reflector, and an imaging system;

[0006] The first illumination optical system is configured to emit a dark field illumination beam, wherein the dark field illumination beam is incident from the end surface of the object to be measured to the interior of the object to be measured;

[0007] The imaging system is configured to image the light beam emitted from the upper surface or the lower surface of the object to be measured;

[0008] The first reflector is configured to reflect the light beam emitted from the end face of the object to be measured and return it to the object to be measured.

[0009] Optionally, the dark field defect detection device further includes a second reflector, a third reflector and a right-angle reflector;

[0010] The second reflector is located on the optical path between the upper surface of the object to be measured and the third reflector, and the third reflector is located on the optical path between the second reflector and the right-angle reflector. The second reflector and the third reflector are configured to project the light beam emitted from the upper surface of the object to be measured onto the right-angle reflector, and then project it onto the imaging system via the right-angle reflector.

[0011] Optionally, an incident angle of the first illumination optical system onto the end face of the object to be measured is within a preset angle range.

[0012] Optionally, the dark field defect detection device further includes a fourth reflector and a fifth reflector;

[0013] The fourth reflector is located on the optical path between the lower surface of the object to be measured and the fifth reflector, and the fifth reflector is located on the optical path between the fourth reflector and the right-angle reflector. The fourth reflector and the fifth reflector are configured to project the light beam emitted from the lower surface of the object to be measured onto the right-angle reflector, and then project it onto the imaging system via the right-angle reflector.

[0014] Optionally, the dark field defect detection device further includes a second illumination optical system, which is located on one side of the upper surface of the object to be detected and is configured to emit a bright field illumination beam.

[0015] Optionally, when the first illumination optical system is turned off and the second illumination optical system is turned on, the reflected light beam reflected by the upper surface of the object to be measured is reflected to the third reflector, the right-angle reflector and the imaging system;

[0016] and / or,

[0017] When the first illumination optical system is turned off and the second illumination optical system is turned on, the transmitted light beam passing through the lower surface of the object to be measured is reflected to the fifth reflecting mirror, the right-angle reflecting mirror and the imaging system.

[0018] Optionally, the dark field defect detection device further includes a first motor, which is configured to drive the fourth reflector and the fifth reflector to move up and down to achieve layer-by-layer imaging.

[0019] Optionally, when the first illumination optical system is turned on and the second illumination optical system is turned off, dark field detection is performed.

[0020] Optionally, when the first illumination optical system and the second illumination optical system are turned on, the transmitted light beam passing through the lower surface of the object to be measured is reflected to the fifth reflector, the right-angle reflector and the imaging system; and the second reflector is controlled to be located outside the propagation path of the reflected light beam reflected by the upper surface of the object to be measured.

[0021] Optionally, the dark field defect detection device further includes a second motor, and the second motor is configured to change the tilt angle of the second reflector.

[0022] Optionally, the right-angle reflector includes an upper reflective surface and a lower reflective surface;

[0023] The light beam emitted from the upper surface of the object to be measured is reflected by the upper reflecting surface and projected onto the imaging system;

[0024] The light beam emitted from the lower surface of the object to be measured is reflected by the lower reflecting surface and projected onto the imaging system.

[0025] Optionally, both the upper reflecting surface and the lower reflecting surface are coated with a reflective film.

[0026] Optionally, the object to be measured includes a mask.

[0027] An embodiment of the present invention provides a dark field defect detection device, which includes a first illumination optical system, a first reflector, and an imaging system. It can realize defect detection inside the object to be measured, reduce the complexity of the defect detection optical path, and reduce the precision requirements of mechanical installation. On the other hand, a first reflector is provided on the side opposite to the first illumination optical system in the direction in which the first illumination optical system is incident on the object to be measured. The light beam emitted from the end face of the object to be measured is reflected back into the object to be measured by the first reflector. The light beam reflected back into the object to be measured by the first reflector meets the internal defects again and is scattered, which increases the number of light rays entering the imaging system, can improve the imaging brightness, improve the utilization rate of light energy, and reduce the required cost of the first illumination optical system. There is no need to provide a first illumination optical system with higher brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 1 is a schematic structural diagram of a dark field defect detection device provided by an embodiment of the present invention;

[0029] Figure 2 1 is a schematic structural diagram of another dark field defect detection device provided by an embodiment of the present invention;

[0030] Figure 3 1 is a schematic structural diagram of another dark field defect detection device provided by an embodiment of the present invention;

[0031] Figure 4 It is a schematic diagram of the imaging area of ​​the upper and lower light paths in the imaging system;

[0032] Figure 5 1 is a schematic structural diagram of another dark field defect detection device provided by an embodiment of the present invention;

[0033] Figure 6 1 is a schematic structural diagram of another dark field defect detection device provided by an embodiment of the present invention;

[0034] Figure 7 It is a structural schematic diagram of another dark field defect detection device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0036] Figure 1 FIG. 1 is a schematic structural diagram of a dark field defect detection device provided by an embodiment of the present invention. Figure 1 As shown, the dark field defect detection device includes a first illumination optical system 1, a first reflector 2 and an imaging system 3. Among them, the first illumination optical system 1, the first illumination optical system 1 is configured to emit a dark field illumination light beam. The dark field illumination light beam is incident from the end face of the object to be measured 4 to the interior of the object to be measured 4. The imaging system 3 is configured to image the light beam emitted from the upper surface or lower surface of the object to be measured 4. Among them, the end face of the object to be measured 4 and the upper surface of the object to be measured 4 are different surfaces, and the end face of the object to be measured 4 and the lower surface of the object to be measured 4 are different surfaces. The upper surface and the lower surface of the object to be measured 4 are arranged opposite to each other. The first reflector 2 is configured to reflect the light beam emitted from the end face of the object to be measured 4 into the object to be measured 4 again.

[0037] Exemplarily, the end face of the object to be measured 4 connects the upper surface of the object to be measured 4 and the lower surface of the object to be measured 4. In one embodiment, the object to be measured 4 is a flat rectangular parallelepiped, a cube, a cylinder, etc., and the upper surface of the object to be measured 4 and the lower surface of the object to be measured 4 are opposite to each other. The area of ​​the upper surface of the object to be measured 4 and the lower surface of the object to be measured 4 are larger than the area of ​​the end face of the object to be measured 4. The object to be measured 4 includes four end faces (the end faces described in this article are also the four side faces of the object to be measured). The dark field illumination light beam emitted by the first illumination optical system 1 can be incident on the interior of the object to be measured 4 from at least one end face.

[0038] Exemplarily, the first illumination optical system 1 is located on the end face side of the object to be measured 4. The first reflector 2 is located on the end face side of the object to be measured 4 and on the side of the object to be measured 4 away from the first illumination optical system 1.

[0039] Defect detection of the object 4 to be tested can achieve different detection effects through different lighting modes. The usual lighting method is generally bright field lighting from above the object 4 to be tested, but this method can only detect the surface of the object 4 to be tested and cannot detect internal defects of the object 4 to be tested.

[0040] For example, during dark field illumination, the first illumination optical system 1 emits a dark field illumination beam, which is incident from the end face of the object to be measured 4. After entering the interior of the object to be measured 4, the dark field illumination beam is totally reflected on the upper and lower surfaces of the object to be measured 4. If there are defects inside the object to be measured 4 (such as Figure 1As shown in the figure, taking the defect as an air bubble 14 as an example), the dark field illumination beam will be scattered in several directions at the defect, and part of the scattered light will be emitted from the upper surface or the lower surface of the object to be measured 4. The imaging system 3 images the scattered light emitted from the upper surface or the lower surface of the object to be measured 4, thereby realizing the detection of internal defects of the object to be measured 4.

[0041] In other embodiments, the dark-field illumination light beam is incident from the end face of the object to be measured 4. After entering the interior of the object to be measured 4, the dark-field illumination light beam refracts back and forth in the body between the upper and lower surfaces inside the object to be measured 4, and propagates in a straight wave-like manner (the dark-field illumination light beam is incident from the end face to the interior of the object to be measured at a certain inclination angle. After entering the interior of the object to be measured, the light beam is emitted in a straight line to one of the surfaces of the object to be measured, and after being reflected by the surface, it is emitted from its body to the other surface, and this process is repeated, forming a wave-like propagation path inside the object to be measured), or propagates inside the object to be measured 4 parallel to the upper surface of the object to be measured 4; alternatively, the dark-field illumination light beam does not meet the total reflection condition in the object to be measured 4, and the detection of internal defects of the object to be measured 4 can also be achieved.

[0042] The light source intensity of dark field inspection is very important. If the light source is too dim, the resolution of defect detection will be insufficient and under-detection may occur. Roughly increasing the light energy will waste energy and increase costs.

[0043] An embodiment of the present invention provides a dark field defect detection device, which includes a first illumination optical system 1, a first reflector 2, and an imaging system 3. It can realize defect detection inside the object to be measured 4, reduce the complexity of the defect detection optical path, and reduce the precision requirement of mechanical installation. On the other hand, a first reflector 2 is provided on the side opposite to the first illumination optical system 1 in the direction in which the first illumination optical system 1 is incident on the object to be measured 4. The light beam emitted from the end face of the object to be measured 4 is reflected back into the object to be measured 4 by the first reflector 2. The light beam reflected back into the object to be measured 4 by the first reflector 2 meets the internal defects again and is scattered, which increases the number of light rays entering the imaging system 3, can improve the imaging brightness, improve the utilization rate of light energy, and reduce the cost required for the first illumination optical system 1. There is no need to set a first illumination optical system 1 with higher brightness.

[0044] Optional, reference Figure 1 The dark-field defect detection device further includes a second reflector 5, a third reflector 6, and a right-angle reflector 7. The second reflector 5 is located in the optical path between the upper surface of the object to be tested 4 and the third reflector 6, and the third reflector 6 is located in the optical path between the second reflector 5 and the right-angle reflector 7. The second reflector 5 and the third reflector 6 are configured to project the light beam emitted from the upper surface of the object to be tested 4 onto the right-angle reflector 7, and then onto the imaging system 3 via the right-angle reflector 7. Using the upper optical path optical system, internal defect detection of the object to be tested 4 can be achieved.

[0045] For example, because the second reflector 5 receives scattered light from defects on the object 4 to be tested, the scattered light is emitted in all directions. This eliminates the need to oversize the second reflector 5, which can receive scattered light from defects on the object 4 to be tested. In one embodiment, the second reflector 5 can be smaller than the object 4 to reduce its size and, consequently, the volume of the dark-field defect detection apparatus.

[0046] refer to Figure 1 The dark field illumination beam is scattered in several directions at the defect of the object to be measured 4. Part of the scattered light is emitted from the upper surface of the object to be measured 4, projected onto the second reflector 5, and then reflected to the third reflector 6. The scattered light is reflected by the third reflector 6 to the right-angle reflector 7, and then reflected by the right-angle reflector 7 to the imaging system 3.

[0047] Figure 2 This is a schematic diagram of the structure of another dark field defect detection device provided by an embodiment of the present invention, referring to Figure 2 , the incident angle of the first illumination optical system 1 onto the end face of the object to be measured 4 is within a preset angle range.

[0048] At incident angles within a preset range, the dark-field illumination beam incident on the interior of the object 4 can undergo total internal reflection within the object 4. The dark-field illumination beam does not need to enter the object 4 at a specific angle; its incident angle only needs to satisfy the condition that the dark-field illumination beam can undergo total internal reflection within the object 4. This design reduces restrictions on the spatial layout of the first illumination optical system 1 and provides greater adjustability and flexibility in the installation accuracy of the first illumination optical system 1 and its relative position setting with respect to the object 4.

[0049] Figure 3 This is a schematic diagram of the structure of another dark field defect detection device provided by an embodiment of the present invention, referring to Figure 3 The dark-field defect detection apparatus further includes a fourth reflector 8 and a fifth reflector 9. The fourth reflector 8 is located in the optical path between the lower surface of the object 4 to be tested and the fifth reflector 9, and the fifth reflector 9 is located in the optical path between the fourth reflector 8 and the right-angle reflector 7. The fourth reflector 8 and the fifth reflector 9 are configured to project the light beam emitted from the lower surface of the object 4 to the right-angle reflector 7, and then project it to the imaging system 3 via the right-angle reflector 7. Using the lower optical path optical system, internal defect detection of the object 4 to be tested can be achieved.

[0050] For example, when detecting internal defects of the object to be measured 4, an upper optical path optical system and / or a lower optical path optical system may be used.

[0051] For example, refer to Figure 3The dark field illumination beam is scattered in several directions at the defect of the object to be measured 4, and part of the scattered light is emitted from the lower surface of the object to be measured 4. The scattered light emitted from the lower surface of the object to be measured 4 is projected onto the fourth reflector 8, and after being reflected by the fourth reflector 8, it is projected onto the fifth reflector 9, and is reflected by the fifth reflector 9 to the right-angle reflector 7, and finally reflected by the right-angle reflector 7 into the imaging system 3.

[0052] Figure 4 This is a schematic diagram of the imaging area of ​​the upper and lower light paths in the imaging system, refer to Figure 3 and Figure 4 , Figure 3 The dark field defect detection device shown has two imaging light paths, one above the other, which can detect defects of the object 4 completely independently. The imaging area in the imaging system 3 is as follows: Figure 4 As shown, the imaging circle 11 of the imaging system 3 includes an upper optical path imaging area 12 and a lower optical path imaging area 13. The upper optical path imaging area 12 and the lower optical path imaging area 13 are arranged at intervals. The upper optical path imaging area 12 and the lower optical path imaging area 13 can be two target surfaces of the same camera or two cameras. Figure 1 As shown in FIG, scattered light from a defect (using a bubble 14 as an example) is imaged by the upper optical path optical system in upper optical path imaging area 12. Scattered light from internal defects in the object 4 is imaged by the lower optical path optical system in lower optical path imaging area 13. Upper optical path imaging area 12 and lower optical path imaging area 13 ensure simultaneous defect detection in the upper and lower optical paths. Simultaneous defect detection along the two optical paths allows for comparison and verification. Furthermore, the optimal inspection image can be selected based on the different imaging effects of the upper and lower optical paths, reducing missed detections and achieving superior inspection quality.

[0053] Surface defects on the object 4 under test can affect the photolithographic pattern and product quality, and are just as important as internal defect detection. Building on the above-described embodiments, the present invention not only enables dark field detection of internal defects on the object 4 under test, but also enables surface defect detection on the object 4 under test.

[0054] Figure 5 This is a schematic diagram of the structure of another dark field defect detection device provided by an embodiment of the present invention, referring to Figure 5 The darkfield defect detection device further includes a second illumination optical system 10, which is located on the upper surface of the object 4 to be detected. The second illumination optical system 10 is configured to emit a brightfield illumination beam. The darkfield defect detection device provided by the embodiment of the present invention includes the first illumination optical system 1 and the second illumination optical system 10, and can perform both darkfield and brightfield defect detection.

[0055] Optional, reference Figure 5When the first illumination optical system 1 is turned off and the second illumination optical system 10 is turned on, the angle between the second reflector 5 and the upper surface of the object to be measured 4 is controlled to be not equal to 45 degrees. For example, the angle between the second reflector 5 and the upper surface of the object to be measured 4 is controlled to be greater than 0 degrees and less than 45 degrees, or greater than 45 degrees and less than 90 degrees. The reflected light beam reflected by the upper surface of the object to be measured 4 is reflected to the third reflector 6, the right-angle reflector 7 and the imaging system 3. In this way, the reflected light beam formed by the bright field illumination beam reflected by the object to be measured 4 is used to realize defect detection on the upper surface of the object to be measured 4 and the area near the upper surface. When the first illumination optical system 1 is turned off and the second illumination optical system 10 is turned on, the angle between the fourth reflector 8 and the lower surface of the object to be measured 4 is controlled to be not equal to 45 degrees. For example, the angle between the fourth reflector 8 and the lower surface of the object to be measured 4 is controlled to be greater than 0 degrees and less than 45 degrees, or greater than 45 degrees and less than 90 degrees. The transmitted light beam passing through the lower surface of the object 4 is reflected toward the fifth reflector 9, right-angle reflector 7, and imaging system 3. This allows for defect detection on the lower surface and the vicinity thereof using the transmitted light beam formed by the brightfield illumination beam transmitted through the object 4. Alternatively, internal defects of the object 4 can be detected. In other embodiments, defect detection on either the upper or lower surface of the object 4 can be achieved using only the reflected or transmitted light beam.

[0056] For example, refer to Figure 5 When the first illumination optical system 1 is turned off and the second illumination optical system 10 is turned on, for the reflected light beam, the bright field illumination light beam output by the second illumination optical system 10 is obliquely incident on the object to be measured 4 and reflected. The inclination angle of the second reflector 5 is flexibly changed according to the incident angle of the bright field illumination light beam, so that the reflected light beam is reflected by the second reflector 5 and projected onto the third reflector 6, and then reflected by the third reflector 6 and the right-angle reflector 7 and finally enters the imaging system 3. The reflected light beam carries the defect information on the upper surface of the object to be measured 4, thereby realizing the defect detection on the upper surface of the object to be measured 4. It should be noted that since the illumination light output by the second illumination optical system 10 is obliquely incident on the object to be measured 4, rather than vertically incident on the upper surface of the object to be measured 4, it means that the propagation direction of the reflected light of the bright field illumination light beam is not perpendicular to the upper surface of the object to be measured 4. Therefore, the angle between the second reflector 5 and the upper surface of the object to be measured 4 should not be 45 degrees. For example, the included angle between the second reflector 5 and the upper surface of the object to be measured 4 is controlled to be greater than 0 degrees and less than 45 degrees, or greater than 45 degrees and less than 90 degrees.

[0057] For example, refer to Figure 5When the first illumination optical system 1 is off and the second illumination optical system 10 is on, the brightfield illumination light beam output by the second illumination optical system 10 is obliquely incident on the object to be measured 4, and the portion that passes through the object to be measured 4 is the transmitted light beam. The angle between the fourth reflector 8 and the lower surface of the object to be measured 4 is controlled according to the exit angle of the transmitted light beam, so that the transmitted light beam is reflected by the fourth reflector 8 and projected onto the fifth reflector 9. It is then reflected by the fifth reflector 9 and the right-angle reflector 7, ultimately entering the imaging system 3. It should be noted that since the illumination light output by the second illumination optical system 10 is obliquely incident on the object to be measured 4, this means that the exit direction of the transmitted light beam is not perpendicular to the lower surface of the object to be measured 4. Therefore, in order for the transmitted light beam to ultimately enter the imaging system 3, the angle between the fourth reflector 8 and the lower surface of the object to be measured 4 should not be equal to 45 degrees. For example, the angle between the fourth reflector 8 and the lower surface of the object to be measured 4 is greater than 0 degrees and less than 45 degrees, or greater than 45 degrees and less than 90 degrees.

[0058] Figure 6 This is a schematic diagram of the structure of another dark field defect detection device provided by an embodiment of the present invention, referring to Figure 6 The dark field defect detection device further includes a first motor 15, which is configured to drive the fourth reflector 8 and the fifth reflector 9 to move up and down to achieve layer-by-layer imaging.

[0059] For example, refer to Figure 5 The first motor 15 drives the fourth reflector 8 and the fifth reflector 9 upward, shortening the optical path from the lower surface of the object 4 to the imaging system 3 while maintaining the focal length of the imaging system 3. Therefore, the object plane corresponding to the image of the transmitted light beam passing through the object 4 in the imaging system 3 moves upward accordingly. The first motor 15 drives the fourth reflector 8 and the fifth reflector 9 downward, causing the object plane corresponding to the image of the transmitted light beam passing through the object 4 in the imaging system 3 to move downward accordingly. By driving the fourth reflector 8 and the fifth reflector 9 up and down by the first motor 15, internal defects of the object 4 can be imaged layer by layer, enabling detection of both internal defects and lower surface defects of the object 4.

[0060] Optionally, when the first illumination optical system 1 is turned on and the second illumination optical system 10 is turned off, dark field detection is performed. When the first illumination optical system 1 is turned on and the second illumination optical system 10 is turned off, the dark field illumination light beam scattered by the defects of the object to be tested 4 will enter the imaging system 3. Dark field detection of internal defects of the object to be tested 4 is realized. The dark field defect detection device provided by the embodiment of the present invention has the advantages of optional light source, switchable light source and dark field, mobile detection, etc., and layered imaging has certain necessity and superiority in defect detection. When the defect is located on the upper surface of the object to be tested 4, it can be detected through the bright field light path, but the area located in the internal area below the upper surface may be out of focus or even indistinguishable, while layered detection can realize the defect detection of the entire object to be tested 4 by moving the lower light path layer by layer in a transmission manner, reducing the cases of missed detection and insufficient detection, and improving the accuracy of defect detection. In addition, if the internal defects cannot be detected by bright field, they can be switched to dark field illumination, and the accuracy of detection is improved by dark field detection, which can be used for comparison or auxiliary confirmation of detection results.

[0061] Illustratively, when performing dark field detection, the first illumination optical system 1 is turned on, the second illumination optical system 10 is turned off, and the angle between the fourth reflector 8 and the lower surface of the object to be measured 4 is controlled to be equal to 45 degrees; and / or, the angle between the second reflector 5 and the upper surface of the object to be measured 4 is controlled to be equal to 45 degrees.

[0062] Figure 7 This is a schematic diagram of the structure of another dark field defect detection device provided by an embodiment of the present invention, referring to Figure 7 When the first illumination optical system 1 and the second illumination optical system 10 are turned on, the angle between the fourth reflector 8 and the lower surface of the object to be measured 4 is controlled to be not equal to 45 degrees. For example, the angle between the fourth reflector 8 and the lower surface of the object to be measured 4 is controlled to be greater than 0 degrees and less than 45 degrees, or greater than 45 degrees and less than 90 degrees. The transmitted light beam passing through the lower surface of the object to be measured 4 is reflected to the fifth reflector 9, the right-angle reflector 7 and the imaging system 3. The lower optical path optical system implements bright field detection. The second reflector 5 is controlled to be located outside the propagation path of the reflected light beam reflected by the upper surface of the object to be measured 4. Therefore, the mirror reflected light of the bright field illumination light beam emitted by the second illumination optical system 10 cannot enter the upper optical path, that is, it cannot be received by the second reflector 5, and thus cannot be imaged by the imaging system 3. The upper optical path optical system implements dark field detection. The embodiment of the present invention can realize simultaneous bright and dark field detection.

[0063] For example, refer to Figure 7, the dark field illumination beam output by the first illumination optical system 1 is scattered by the internal defects of the object to be measured 4, and the scattered light is emitted from the upper surface of the object to be measured 4, reflected by the second reflector 5 to the third reflector 6, and then reflected by the third reflector 6 to the right-angle reflector 7, and then reflected by the right-angle reflector 7 to the imaging system 3. Dark field detection is achieved. The bright field illumination beam output by the second illumination optical system 10 passes through the lower surface of the object to be measured 4, and is reflected by the fourth reflector 8 to the fifth reflector 9, the right-angle reflector 7 and the imaging system 3. Bright field detection is achieved. Among them, the bright field illumination beam output by the second illumination optical system 10 is reflected on the upper surface of the object to be measured 4, and the second reflector 5 is located outside the propagation path of the reflected beam, so the reflected beam cannot be imaged.

[0064] Optionally, the dark field defect detection device further includes a second motor ( Figure 7 (not shown in the figure), the second motor is configured to change the tilt angle of the second reflector 5. Thus, in one application scenario, the first illumination optical system 1 is turned on, and the second illumination optical system 10 is turned on. The tilt angle of the second reflector 5 is controlled by the second motor, so that the second reflector 5 cannot receive the mirror reflection light of the bright field illumination beam emitted by the second illumination optical system 10, but can receive the scattered light caused by the illumination defects of the first illumination optical system 1. Simultaneous detection of bright field and dark field is achieved. In another application scenario, the first illumination optical system 1 is turned off, and the second illumination optical system 10 is turned on, and the tilt angle of the second reflector 5 is controlled by the second motor, so that the second reflector 5 can receive the mirror reflection light of the bright field illumination beam emitted by the second illumination optical system 10, thereby achieving bright field detection of the upper and lower light paths.

[0065] In other embodiments, the second motor may not be provided in the dark field defect detection device, and the tilt angle of the second reflector 5 may not be changed. In a dark field defect detection device, simultaneous bright field and dark field detection or bright field detection of the upper and lower optical paths may be achieved.

[0066] Optionally, right-angle reflector 7 includes an upper reflective surface and a lower reflective surface. A light beam emitted from the upper surface of the object 4 to be measured is reflected by the upper reflective surface and projected onto the imaging system 3. A light beam emitted from the lower surface of the object 4 to be measured is reflected by the lower reflective surface and projected onto the imaging system 3. Right-angle reflector 7 can simultaneously image the upper and lower surfaces of the object 4 to be measured without requiring motor control. That is, there is no need to configure a motor for right-angle reflector 7 to simultaneously image the upper and lower surfaces of the object 4 to be measured.

[0067] Exemplarily, the upper reflecting surface and the lower reflecting surface of the right-angle reflector 7 are perpendicular.

[0068] Optionally, both the upper and lower reflective surfaces of the right-angle reflector 7 are coated with a reflective film. This allows the upper reflective surface to reflect the reflected light beam, and the lower reflective surface to reflect the transmitted light beam. Furthermore, coating the reflective film can improve the reflectivity of the reflected and transmitted light beams on the right-angle reflector 7.

[0069] Optionally, the object to be tested 4 includes a mask. In other embodiments, the object to be tested 4 may also include other objects to be tested besides the mask, such as a glass plate with a pattern. Alternatively, at least one of the above-mentioned embodiments of the present invention may be applied to wafer inspection.

[0070] In summary, darkfield defect detection devices feature a simple optical path and require minimal mechanical installation precision. Depending on actual conditions and needs, both darkfield and brightfield illumination can be used for defect detection. Brightfield illumination can detect both surface and internal defects, while darkfield illumination can also be used to detect internal defects. Brightfield and darkfield illumination can be switched between, making implementation simple and flexible.

[0071] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious variations, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of the present invention. Therefore, while the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention.

Claims

1. A dark field defect detection device, characterized in that: comprising a first illumination optical system, a first reflecting mirror and an imaging system; The first illumination optical system is configured to emit a dark field illumination beam, wherein the dark field illumination beam is incident from the end face of the object to be measured to the interior of the object to be measured; The imaging system is configured to image the light beam emitted from the upper surface or the lower surface of the object to be measured; The first reflector is configured to reflect the light beam emitted from the end face of the object to be measured back into the object to be measured; Also included are a second reflector, a third reflector, and a right-angle reflector; The second reflector is located on an optical path between the upper surface of the object to be measured and the third reflector, and the third reflector is located on an optical path between the second reflector and the right-angle reflector. The second reflector and the third reflector are configured to project a light beam emitted from the upper surface of the object to be measured onto the right-angle reflector, and then project the light beam onto the imaging system via the right-angle reflector. The incident angle of the first illumination optical system onto the end face of the object to be measured is within a preset angle range; Also included are a fourth reflector and a fifth reflector; The fourth reflector is located on the optical path between the lower surface of the object to be measured and the fifth reflector, and the fifth reflector is located on the optical path between the fourth reflector and the right-angle reflector. The fourth reflector and the fifth reflector are configured to project the light beam emitted from the lower surface of the object to be measured onto the right-angle reflector, and then project it onto the imaging system via the right-angle reflector.

2. The dark field defect detection device according to claim 1, characterized in that: It also includes a second illumination optical system, which is located on one side of the upper surface of the object to be measured and is configured to emit a bright field illumination beam.

3. The dark field defect detection device according to claim 2, characterized in that: When the first illumination optical system is turned off and the second illumination optical system is turned on, the reflected light beam reflected by the upper surface of the object to be measured is reflected to the third reflector, the right-angle reflector and the imaging system; and / or, When the first illumination optical system is turned off and the second illumination optical system is turned on, the transmitted light beam passing through the lower surface of the object to be measured is reflected to the fifth reflecting mirror, the right-angle reflecting mirror and the imaging system.

4. The dark field defect detection device according to claim 3, characterized in that: It also includes a first motor, which is configured to drive the fourth reflecting mirror and the fifth reflecting mirror to move up and down to achieve layer-by-layer imaging.

5. The dark field defect detection device according to claim 2, characterized in that: When the first illumination optical system is turned on and the second illumination optical system is turned off, dark field detection is performed.

6. The dark field defect detection device according to claim 2, characterized in that: When the first illumination optical system and the second illumination optical system are turned on, the transmitted light beam passing through the lower surface of the object to be measured is reflected to the fifth reflector, the right-angle reflector and the imaging system; And the second reflector is controlled to be located outside the propagation path of the reflected light beam reflected by the upper surface of the object to be measured.

7. The dark field defect detection device according to claim 6, characterized in that: Also included is a second motor configured to change a tilt angle of the second reflector.

8. The dark field defect detection device according to claim 1, characterized in that: The right-angle reflector includes an upper reflective surface and a lower reflective surface; The light beam emitted from the upper surface of the object to be measured is reflected by the upper reflecting surface and projected onto the imaging system; The light beam emitted from the lower surface of the object to be measured is reflected by the lower reflecting surface and projected onto the imaging system.

9. The dark field defect detection device according to claim 8, characterized in that: The upper reflecting surface and the lower reflecting surface are both coated with a reflective film.

Images