Optical detection method, optical detection device and storage medium

Abstract

The embodiment of the invention discloses an optical detection method, an optical detection device and a storage medium, and belongs to the technical field of optical imaging. In the embodiment of the invention, in a process of controlling a bright field detector and a dark field detector to carry out relative motion scanning on the surface of a to-be-detected object, a first position relation between a bright field imaging area of the bright field detector and an image space to-be-detected area of the surface of the to-be-detected object is acquired; the second position relation between the dark field imaging area of the dark field detector and the image space to-be-detected area is obtained; on the basis of the first position relation and the second position relation, the detection triggering conditions of the bright field detector and the dark field detector are controlled to detect a bright field image and a dark field image corresponding to the image space to-be-detected area, false triggering of the bright field detector and the dark field detector in the detection process can be effectively avoided, and the detection accuracy is improved. A bright field image and a dark field image can be accurately detected.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical imaging technology, and in particular, to an optical detection method, an optical detection device, and a storage medium. Background Art

[0002] In existing optical detection, a bright-field camera and a dark-field camera are often used to scan the surface of an object to be measured respectively; when the bright-field camera scans, it can detect the transmitted light of the light source on the surface of the object to be measured to obtain a bright-field image of the surface of the object to be measured; when the dark-field camera scans, it can detect the diffracted light of the light source on the surface of the object to be measured to obtain a dark-field image of the surface of the object to be measured; by integrating the bright-field image and the dark-field image, a detection image of the surface of the object to be measured is obtained.

[0003] In existing optical detection, the object to be measured is loaded on a moving platform, and the moving platform drives the object to be measured to move under the bright-field camera and the dark-field camera; during the process of scanning the surface of the object to be measured on the moving platform by using the bright-field camera and the dark-field camera, the detection processes of the bright-field camera and the dark-field camera are triggered based on the moving process of the moving platform; however, during the moving process of the moving platform, due to mechanical failures, motion accuracy, platform jitter, etc., it is easy to cause the failure to accurately drive the object to be measured to move, and the bright-field camera and the dark-field camera are prone to false triggering during the detection process, resulting in difficulty in accurately detecting the bright-field image and the dark-field image. Summary of the Invention

[0004] The embodiments of the present application provide an optical detection method, an optical detection device, and a storage medium, which can accurately detect the bright-field image and the dark-field image.

[0005] The embodiments of the present application provide an optical detection method, including:

[0006] During the process of controlling the bright-field detector and the dark-field detector to perform relative motion scanning on the surface of the object to be measured, obtaining a first positional relationship between the bright-field imaging region of the bright-field detector and the image-side region to be measured on the surface of the object to be measured, and a second positional relationship between the dark-field imaging region of the dark-field detector and the image-side region to be measured; wherein, the bright-field imaging region and the dark-field imaging region are spaced apart by a preset distance in physical space;

[0007] Based on the first positional relationship and the second positional relationship, controlling the detection trigger conditions of the bright-field detector and the dark-field detector to detect the bright-field image and the dark-field image corresponding to the image-side region to be measured.

[0008] Further, the controlling the detection trigger conditions of the bright-field detector and the dark-field detector based on the first positional relationship and the second positional relationship includes:

[0009] When any side area edge of the bright-field imaging area contacts the object-side area to be measured, trigger the bright-field detector to perform imaging detection; when the opposite side area edge of the bright-field imaging area leaves the object-side area to be measured, stop triggering the bright-field detector;

[0010] When any side area edge of the dark-field imaging area contacts the object-side area to be measured, trigger the dark-field detector to perform imaging detection; when the opposite side area edge of the dark-field imaging area leaves the object-side area to be measured, stop triggering the dark-field detector.

[0011] Further, controlling the detection triggering conditions of the bright-field detector and the dark-field detector based on the first position relationship and the second position relationship includes:

[0012] When any side area edge in the bright-field imaging area and the dark-field imaging area contacts the object-side area to be measured, synchronously trigger the bright-field detector and the dark-field detector to perform imaging detection;

[0013] When the opposite side area edge of the side area edge in the bright-field imaging area and the dark-field imaging area leaves the object-side area to be measured, synchronously stop triggering the bright-field detector and the dark-field detector.

[0014] Further, when the area size of the bright-field imaging area or the dark-field imaging area is smaller than the area size of the object-side area to be measured, controlling the bright-field detector and the dark-field detector to synchronously perform relative motion scanning on the surface of the object to be measured includes:

[0015] Controlling the bright-field detector and the dark-field detector to synchronously scan the surface of the object to be measured in relative motion in a first scanning direction;

[0016] When both the bright-field imaging area and the dark-field imaging area leave the object-side area to be measured, controlling the bright-field detector and the dark-field detector to synchronously scan the surface of the object to be measured in relative motion in a second scanning direction; wherein, the second scanning direction is opposite to the first scanning direction, and the scanning areas of the second scanning direction and the first scanning direction have an overlapping part.

[0017] Further, controlling the detection triggering conditions of the bright-field detector and the dark-field detector based on the first position relationship and the second position relationship includes:

[0018] Obtaining the scanning compensation value in the first scanning direction and the scanning compensation value in the second scanning direction;

[0019] During the scanning process in the first scanning direction, based on the first positional relationship and the second positional relationship, determine the first initial trigger positions of the bright-field detector and the dark-field detector, and compensate the first initial trigger positions through the scanning compensation value in the first scanning direction to obtain the first target trigger positions;

[0020] During the scanning process in the second scanning direction, based on the first positional relationship and the second positional relationship, determine the second initial trigger positions of the bright-field detector and the dark-field detector, and compensate the second initial trigger positions through the scanning compensation value in the second scanning direction to obtain the second target trigger positions.

[0021] Further, the method further includes:

[0022] Carry the object to be measured on a moving platform. When the bright-field imaging area or the dark-field imaging area is outside the image-side area to be measured on the surface of the object to be measured, control the moving platform to drive the object to be measured to accelerate, so that the image-side area to be measured approaches and coincides with the bright-field imaging area and the dark-field imaging area;

[0023] When the bright-field imaging area or the dark-field imaging area enters the image-side area to be measured on the surface of the object to be measured, control the moving platform to drive the object to be measured to move at a constant speed;

[0024] When the bright-field imaging area or the dark-field imaging area leaves the image-side area to be measured on the surface of the object to be measured, control the moving platform to drive the object to be measured to decelerate.

[0025] Further, after controlling the moving platform to drive the object to be measured to move at a constant speed, turn on the focus tracking functions of the bright-field detector and the dark-field detector;

[0026] Before controlling the moving platform to drive the object to be measured to decelerate, turn off the focus tracking functions of the bright-field detector and the dark-field detector.

[0027] Further, the turning on the focus tracking functions of the bright-field detector and the dark-field detector includes:

[0028] Based on the surface edge of the surface of the object to be measured and the size of the working light spot for focus tracking, turn on the focus tracking functions of the bright-field detector and the dark-field detector;

[0029] The turning off the focus tracking functions of the bright-field detector and the dark-field detector includes:

[0030] Based on the surface edge of the object to be measured, the size of the working light spot for focus tracking, the execution duration of turning off focus tracking, and the scanning speed, turn off the focus tracking functions of the bright-field detector and the dark-field detector.

[0031] An embodiment of the present application further provides an optical detection device, including:

[0032] An acquisition unit, during the process of controlling the bright-field detector and the dark-field detector to perform relative motion scanning on the surface of the object to be measured, acquires a first positional relationship between the bright-field imaging area of the bright-field detector and the image-space area to be measured on the surface of the object to be measured, and a second positional relationship between the dark-field imaging area of the dark-field detector and the image-space area to be measured; wherein, the bright-field imaging area and the dark-field imaging area are spaced apart by a preset distance in physical space;

[0033] A control unit, configured to control the detection triggering conditions of the bright-field detector and the dark-field detector based on the first positional relationship and the second positional relationship, so as to detect a bright-field image and a dark-field image of the image-space area to be measured.

[0034] An embodiment of the present application further provides a computer-readable storage medium, the computer-readable storage medium includes instructions, when the instructions are run on a computer by a processor, the method described above is implemented.

[0035] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0036] In the embodiment of the present application, during the process of controlling the bright-field detector and the dark-field detector to perform relative motion scanning on the surface of the object to be measured, a first positional relationship between the bright-field imaging area of the bright-field detector and the image-space area to be measured on the surface of the object to be measured is acquired, and a second positional relationship between the dark-field imaging area of the dark-field detector and the image-space area to be measured is acquired; wherein, the bright-field imaging area and the dark-field imaging area are spaced apart by a preset distance in physical space; based on the first positional relationship and the second positional relationship, the detection triggering conditions of the bright-field detector and the dark-field detector are controlled, so as to detect a bright-field image and a dark-field image corresponding to the image-space area to be measured.

[0037] It can be seen that in the embodiment of the present application, based on the positional relationship between the imaging area of the detector and the image-space area to be measured on the surface of the object to be measured, the detection triggering conditions of the detector are controlled, which can effectively avoid mis-triggering of the bright-field detector and the dark-field detector during the detection process, and can accurately detect a bright-field image and a dark-field image. Description of the Drawings

[0038] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, other accompanying drawings can also be obtained based on these drawings.

[0039] Figure 1 It is a flowchart of an optical detection disclosed in the embodiments of the present application;

[0040] Figure 2 It is a detection flowchart of time-sharing triggering disclosed in the embodiments of the present application;

[0041] Figure 3 It is a detection flowchart of synchronous triggering disclosed in the embodiments of the present application;

[0042] Figure 4 It is a path planning flowchart of focusing disclosed in the embodiments of the present application;

[0043] Figure 5 It is a schematic diagram of synchronous triggering scanning disclosed in the embodiments of the present application;

[0044] Figure 6 It is a distribution diagram of bright and dark field imaging regions in an objective lens disclosed in the embodiments of the present application;

[0045] Figure 7 It is a schematic diagram of path planning for optical detection disclosed in the embodiments of the present application;

[0046] Figure 8 It is a diagram of an optical detection device disclosed in the embodiments of the present application;

[0047] Figure 9 It is another diagram of an optical detection device disclosed in the embodiments of the present application. Detailed implementation manners

[0048] To enable those skilled in the art to better understand the solutions of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0049] In the description of the embodiments of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the embodiments of the present application.

[0050] In the description of the embodiments of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific situations.

[0051] In the existing optical detection, the object to be measured is loaded on a moving platform, and the moving platform drives the object to be measured to move under a bright-field camera and a dark-field camera; during the process of scanning the surface of the object to be measured on the moving platform by using the bright-field camera and the dark-field camera, the detection processes of the bright-field camera and the dark-field camera are triggered based on the moving process of the moving platform; however, during the moving process of the moving platform, due to mechanical failures and other reasons, it is easy to cause the failure to accurately drive the object to be measured to move, and the bright-field camera and the dark-field camera are prone to false triggering during the detection process, resulting in difficulty in accurately detecting the bright-field image and the dark-field image. Therefore, the embodiments of the present application provide an optical detection method that can accurately detect the bright-field image and the dark-field image, as Figure 1 shown, and specifically includes the following steps:

[0052] 101. During the process of controlling the bright-field detector and the dark-field detector to perform relative motion scanning on the surface of the object to be measured, obtain the first positional relationship between the bright-field imaging area of the bright-field detector and the image-space area to be measured on the surface of the object to be measured, and the second positional relationship between the dark-field imaging area of the dark-field detector and the image-space area to be measured.

[0053] In the embodiments of the present application, the optical detection device can control the bright-field detector and the dark-field detector to synchronously scan the surface of the object to be measured. During the process of controlling the bright-field detector and the dark-field detector to perform relative motion scanning on the surface of the object to be measured, the first positional relationship between the bright-field imaging region (i.e., the bright-field object-space detection region) of the bright-field detector and the image-space region to be measured (i.e., the space where the image points of the surface of the object to be measured are located) of the surface of the object to be measured is obtained, and the second positional relationship between the dark-field image-space region (dark-field object-space detection region) of the dark-field detector and the region to be measured is obtained.

[0054] Among them, the bright-field detector (bright-field vision detector) is used to receive the bright-field imaging light beam (such as reflected light) of the bright-field imaging region, and the dark-field detector (dark-field vision detector) is used to receive the dark-field imaging light beam (such as scattered light) of the dark-field imaging region. The relative motion means that the bright-field detector and the dark-field detector are in a moving state relative to the surface of the object to be measured. For example, they can approach the surface of the object to be measured or move away from the surface of the object to be measured. Among them, the bright-field imaging region and the dark-field imaging region are spaced apart by a preset distance in physical space. The preset distance can be a numerical value in the range of 1 cm to 4 cm, and specific details are not limited here; that is, the bright-field imaging region and the dark-field imaging region do not overlap in space. When the bright-field detector receives the bright-field imaging light beam, the dark-field detector can receive the dark-field imaging light beam.

[0055] Among them, the object to be measured can be loaded on a moving platform, and the positions of the bright-field detector and the dark-field detector are fixed. By moving the moving platform to drive the object to be measured, the bright-field detector and the dark-field detector can scan the surface of the object to be measured; or, the bright-field detector and the dark-field detector can be loaded on the moving platform, and the position of the object to be measured is fixed. By moving the moving platform, the bright-field detector and the dark-field detector are driven to scan the surface of the object to be measured, and specific details are not limited here. It can be understood that during the process of controlling the bright-field detector and the dark-field detector to scan the surface of the object to be measured, when the detector starts to be triggered, the detector will detect the received reflected light. That is, the bright-field detector can receive the bright-field imaging light beam in real time during the scanning process, and will detect the bright-field imaging light beam only when the bright-field detector starts to be triggered to obtain a bright-field image; the dark-field detector is similar, and specific details are not elaborated here.

[0056] It can be understood that the positional relationship between the bright-field imaging region and the dark-field imaging region in the imaging plane is not limited. For example, the bright-field imaging region can be on the left side of the dark-field imaging region, or the bright-field imaging region can be on the right side of the dark-field imaging region. Specifically, it is not limited here. Generally, the relative position of the bright-field detector and the dark-field detector is the same as the relative position of the bright-field imaging region and the dark-field imaging region. Preferably, the shapes and sizes of the bright-field imaging region and the dark-field imaging region are the same. Among them, the bright-field detector and the dark-field detector can be arranged in the same camera, and the corresponding bright-field imaging region and dark-field imaging region can be arranged on both sides of the central field of view of the objective lens of the camera; or, the bright-field detector can be a separate camera, and the dark-field detector can be another separate camera. The two separate cameras can use the same objective lens for imaging. At this time, the corresponding bright-field imaging region and dark-field imaging region can also be arranged on both sides of the central field of view of the objective lens of the camera. The distribution of the bright-field and dark-field imaging regions in the objective lens field of view is as Figure 6 shown. The circle represents the objective lens field of view. TDI1 is any detection region in the bright-field and dark-field imaging regions, TDI2 is another detection region corresponding to TDI1, d represents the image-side pitch of the bright-field and dark-field imaging regions, and TDISensorwidth represents the width of the detection region. It can be seen that the bright-field imaging region and the dark-field imaging region can be arranged on both sides of the central field of view of the objective lens of the camera.

[0057] Among them, the surface of the object to be measured can be the surface of a wafer, the surface of a thin film, the surface of glass, etc. Specifically, it is not limited here. The image-side region to be measured on the surface of the object to be measured is the region on the surface of the object to be measured that needs to be detected, such as the die region to be detected on the surface of a wafer. The first positional relationship between the bright-field imaging region and the image-side region to be measured on the surface of the object to be measured, and the second positional relationship between the dark-field imaging region and the image-side region to be measured can be determined by analyzing the imaging light beams received by the bright-field detector and the dark-field detector. For example, when the imaging light beam received by the bright-field detector is the light beam reflected within the image-side region to be measured, it is determined that the bright-field imaging region is within the image-side region to be measured; when the imaging light beam received by the bright-field detector is the light beam reflected from a region other than the image-side region to be measured, it is determined that the bright-field imaging region is outside the image-side region to be measured; when the imaging light beam received by the bright-field detector only contains the light beam reflected from the region edge of the image-side region to be measured, it is determined that the bright-field imaging region is in contact with the image-side region to be measured. The second positional relationship between the dark-field imaging region and the image-side region to be measured is similar and will not be elaborated here.

[0058] 102. Based on the first positional relationship and the second positional relationship, control the detection triggering conditions of the bright-field detector and the dark-field detector.

[0059] After obtaining the first position relationship and the second position relationship, the detection triggering conditions of the bright field detector and the dark field detector can be controlled based on the first position relationship and the second position relationship to detect and obtain the bright field image and dark field image corresponding to the image side test area of the surface of the object to be tested. Specifically, when the bright field imaging area contacts the image side test area, the bright field detector can be triggered for detection, and when the dark field imaging area contacts the image side test area, the dark field detector can be triggered for detection; or when the bright field imaging area contacts the image side test area, the bright field detector and the dark field detector can be triggered for detection at the same time, and the specific details are not limited here. By controlling the detection triggering conditions of the detectors through the positional relationship, the detectors can be accurately triggered for detection during the scanning process.

[0060] It can be seen that in the embodiment of the present application, based on the positional relationship between the imaging area of the detector and the image area to be measured on the surface of the object to be measured, the detection triggering of the detector is controlled, which can effectively avoid the false triggering of the bright field detector and the dark field detector during the detection process, and can accurately detect and obtain the bright field image and the dark field image.

[0061] Furthermore, the bright field detector and the dark field detector can be triggered in different time periods, and the detection behaviors of the bright field detector and the dark field detector do not interfere with each other, which effectively improves the accuracy of the detection triggering. Figure 2 As shown, the specific steps include:

[0062] 201. When the size of the imaging area is smaller than the image side area to be measured, the bright field detector and the dark field detector are controlled to synchronously scan the surface of the object to be measured back and forth.

[0063] In an embodiment of the present application, when the area size of the bright field imaging area or the dark field imaging area is smaller than the area size of the image side area to be tested (preferably, the area size of the bright field imaging area is the same as the area size of the dark field imaging area, that is, when the area size of the imaging area is smaller than the image side area to be tested), in order to completely scan the image side area to be tested on the surface of the object to be tested, it is necessary to control the bright field detector and the dark field detector to synchronously scan the surface of the object to be tested back and forth.

[0064] Specifically, the bright-field detector and the dark-field detector can be controlled to scan the surface of the object to be measured in relative motion synchronously in a first scanning direction; when both the bright-field imaging area and the dark-field imaging area leave the image-side area to be measured of the surface of the object to be measured, the bright-field detector and the dark-field detector are controlled to scan the surface of the object to be measured in relative motion synchronously in a second scanning direction; wherein, the second scanning direction is opposite to the first scanning direction, and the scanning areas of the second scanning direction and the first scanning direction have an overlapping part. The first scanning direction can be a forward row scan, and the second scanning direction can be a reverse row scan. A margin is left between every two rows of scanning areas, that is, there is an overlapping part between the scanning areas. The width of the overlapping part can be 5 pixel points or 10 pixel points, and specific details are not limited here. By making the scanning areas of the second scanning direction and the first scanning direction have an overlapping part, the images obtained by scanning in the second scanning direction and the first scanning direction can be completely stitched together.

[0065] 202. Obtain a first positional relationship between the bright-field imaging area of the bright-field detector and the image-side area to be measured of the surface of the object to be measured, and a second positional relationship between the dark-field imaging area of the dark-field detector and the image-side area to be measured.

[0066] It can be understood that step 202 is similar to the above step 101, and specific details are not elaborated here.

[0067] 203. Control the detection triggering situation of the bright-field detector based on the first positional relationship, and control the detection triggering situation of the dark-field detector based on the second positional relationship.

[0068] In the embodiment of the present application, the detection trigger signals of the bright-field detector and the dark-field detector can be given in a time-sharing manner. The detection triggering situation of the bright-field detector can be controlled based on the first positional relationship, and the detection triggering situation of the dark-field detector can be controlled based on the second positional relationship. Specifically, when any side area edge of the bright-field imaging area comes into contact with the image-side area to be measured, the bright-field detector is triggered to perform imaging detection; when the opposite side area edge of the bright-field imaging area (that is, the other side area edge far from the any side area edge) leaves the image-side area to be measured, the bright-field detector is stopped from being triggered.

[0069] When the edge of any side area of the dark-field imaging area contacts the image-side area to be measured, the dark-field detector is triggered to start imaging detection; when the opposite side area of the dark-field imaging area (i.e., the edge of the other side area far from the edge of any side area) leaves the image-side area to be measured, the triggering of the dark-field detector stops. That is, during the reciprocating scanning process, when the edge of the area on the bright-field imaging area close to the image-side area to be measured (the front edge in the scanning direction) contacts the image-side area to be measured during the scanning of the bright-field detector along the scanning direction (the first scanning direction or the second scanning direction), the bright-field detector is triggered to start detection; when the edge of the area on the bright-field imaging area far from the image-side area to be measured (the rear edge in the scanning direction) leaves the image-side area to be measured, the triggering of the bright-field detector stops. The dark-field detector is similar, and will not be elaborated here specifically.

[0070] At this time, there is a certain triggering delay distance for the detection triggering of the bright-field detector and the dark-field detector. The corresponding triggering delay distance Δx is: where M Obj represents the objective magnification, and M Tube represents the tube lens magnification.

[0071] 204. Compensate the initial trigger position in the detection trigger situation based on the scan compensation value to obtain the target trigger position.

[0072] Furthermore, during the reciprocating scanning (back-and-forth scanning) process, in order to ensure that the images obtained by the reciprocating scanning are completely aligned, scan compensation is required. The initial trigger position in the detection trigger situation can be compensated based on the scan compensation value to obtain the target trigger position. Specifically, the scan compensation value for the first scanning direction and the scan compensation value for the second scanning direction can be obtained; the scan compensation value can be 5 pixel points or 6 pixel points, and no specific limitation is made here. The scan compensation value can be determined based on the objective magnification. The larger the objective magnification, the larger the scan compensation value.

[0073] During the scanning process in the first scanning direction, the first initial trigger position of the bright-field detector can be determined based on the first position relationship, and the first initial trigger position of the dark-field detector can be determined based on the second position relationship. That is, during the scanning of the bright-field detector (or dark-field detector) in the first scanning direction, the position where the edge of the area on the bright-field imaging area (or dark-field imaging area) close to the image-side area to be measured contacts the image-side area to be measured is the corresponding first initial trigger position. Compensate the first initial trigger position with the scan compensation value in the first scanning direction to obtain the first target trigger position. That is, the first initial trigger position can be moved along the opposite direction of the first scanning direction by the distance corresponding to the scan compensation value in the first scanning direction to obtain the first target trigger position; during the scanning of the detector in the first scanning direction, when the imaging area of the detector reaches the first target trigger position, the detector is triggered to start detection.

[0074] During scanning in the second scanning direction, a second initial trigger position of the brightfield detector can be determined based on the first positional relationship, and a second initial trigger position of the darkfield detector can be determined based on the second positional relationship. The second initial trigger position can be compensated by the scanning compensation value in the second scanning direction to obtain a second target trigger position. That is, the second initial trigger position can be moved in the opposite direction of the second scanning direction by a distance corresponding to the scanning compensation value in the second scanning direction to obtain the second target trigger position. During scanning in the second scanning direction, when the imaging area of the detector reaches the second target trigger position, the detector is triggered to begin detection.

[0075] That is, during the reciprocating scanning process, the detector can be triggered in advance in the corresponding scanning direction, leaving a certain trigger distance outside the image area to be measured, leaving enough detection start time for the detector to start triggering, further ensuring the accuracy of detection.

[0076] It is understandable that during the reciprocating scanning process, scanning compensation may be performed or not performed, that is, step 204 may be selectively performed or not performed.

[0077] It can be seen that in the embodiment of the present application, the bright field detector and the dark field detector can be triggered in a time-sharing manner, and the detection behavior of the detector itself can be started or stopped by the positional relationship between the imaging area of the detector itself and the area to be measured on the image side. The detection behaviors of the bright field detector and the dark field detector do not interfere with each other, which effectively improves the accuracy of the detection triggering and improves the accuracy of image detection.

[0078] Furthermore, the bright field detector and the dark field detector can be triggered synchronously. The bright field detector and the dark field detector start triggering and detecting at the same time or stop triggering at the same time. Synchronous triggering can effectively simplify the triggering control and improve the detection speed.

[0079] 301. When the size of the imaging area is smaller than the image side area to be measured, the bright field detector and the dark field detector are controlled to synchronously scan the surface of the object to be measured back and forth.

[0080] 302. Acquire a first positional relationship between a bright field imaging area of a bright field detector and an image-side area to be measured on a surface of an object to be measured, and a second positional relationship between a dark field imaging area of a dark field detector and an image-side area to be measured.

[0081] It is understandable that step 301 and step 302 are similar to the above-mentioned step 201 and step 202, and the details are not repeated here.

[0082] 303. Synchronously control the detection triggering status of the bright field detector and the dark field detector based on the first position relationship and the second position relationship.

[0083] In the embodiments of the present application, the detection triggering of the bright-field detector and the dark-field detector can be synchronously controlled based on the first positional relationship and the second positional relationship. Specifically, when the edge of any one side region in the bright-field imaging region and the dark-field imaging region contacts the object-side region to be measured, the bright-field detector and the dark-field detector are synchronously triggered to perform detection; when the edge of the region opposite to the edge of any one side region in the bright-field imaging region and the dark-field imaging region leaves the object-side region to be measured, the triggering of the bright-field detector and the dark-field detector is synchronously stopped.

[0084] Wherein, the surface of the object to be measured can be the surface of a wafer, and the object-side region to be measured on the surface of the object to be measured is the corresponding die region to be measured (die detection region). The process of reciprocally scanning the wafer surface in the row direction is as Figure 5 shown. In the figure, waferedge represents the wafer edge, die start (the first region edge of the die detection region) and die end (the second region edge of the die detection region) enclose the corresponding die detection region (i.e., the object-side region to be measured on the surface of the object to be measured), scanDirection represents the scanning direction, swath represents the scanning width of the row-direction scanning, frame represents a frame of image (bright-field image and dark-field image) output after the detector detects, TDI1 is any one of the bright-field imaging region and the dark-field imaging region, and TDI2 is the other imaging region corresponding to any one imaging region. When scanning in the first scanning direction (forward scanning), triggering starts (Forward Trigger start) when the front edge of TDI1 along the scanning direction contacts the die detection region, and ends (Forward Trigger end) when the rear edge of TDI2 leaves the die detection region. When scanning in the second scanning direction (reverse scanning), triggering starts (Backward Trigger start) when the front edge of TDI2 along the scanning direction contacts the die detection region, and ends (Backward Trigger end) when the rear edge of TDI1 leaves the die detection region. At this time, the bright-field detector and the dark-field detector will each obtain an image of a non-detection region, and later cropping processing is performed at the image processing end.

[0085] 304. Compensate the initial trigger position in the detection trigger situation based on the scan compensation value to obtain the target trigger position.

[0086] In the embodiments of the present application, during the reciprocating scanning process, scanning compensation can also be performed, that is, the initial trigger position in the detection trigger situation can be compensated based on the scanning compensation value to obtain the target trigger position. Specifically, the scanning compensation value in the first scanning direction and the scanning compensation value in the second scanning direction can be obtained; during the scanning process in the first scanning direction, based on the first position relationship and the second position relationship, the first initial trigger positions of the bright-field detector and the dark-field detector are determined; that is, during the scanning process in the first scanning direction, the position where the edge of any one side area in the bright-field imaging area and the dark-field imaging area contacts the object under test area on the image side is the first initial trigger position of the bright-field detector and the dark-field detector; the first initial trigger position is compensated by the scanning compensation value in the first scanning direction to obtain the first target trigger position. During the scanning process in the second scanning direction, based on the first position relationship and the second position relationship, the second initial trigger positions of the bright-field detector and the dark-field detector are determined; that is, during the scanning process in the second scanning direction, the position where the edge of any one side area in the bright-field imaging area and the dark-field imaging area contacts the object under test area on the image side is the second initial trigger position of the bright-field detector and the dark-field detector; the second initial trigger position is compensated by the scanning compensation value in the second scanning direction to obtain the second target trigger position. The specific scanning compensation method is similar to step 204 above, and will not be elaborated here specifically.

[0087] In the embodiments of the present application, the wafer can be loaded on the moving platform. In the coordinate system corresponding to the moving platform, based on the center of the field of view of the objective lens (that is, the position represented below is the position corresponding to the center of the field of view of the objective lens), the trigger positions of the detector during the forward scan and the reverse scan are determined. The corresponding trigger positions can be expressed as:

[0088]

[0089] Among them, ForwardOffset Obj represents the scanning compensation value for the forward scan, and BackwardOffset Obj represents the scanning compensation value for the reverse scan.

[0090] It can be understood that during the reciprocating scanning process, scanning compensation can be performed or not, that is, step 304 can be selected to be executed or not.

[0091] It can be seen that in the embodiments of the present application, the bright-field detector and the dark-field detector can be triggered synchronously. When any detector contacts the object under test area on the image side of the surface of the object to be measured, the bright-field detector and the dark-field detector are synchronously triggered to start detection. When all detectors leave the object under test area on the image side, the bright-field detector and the dark-field detector are synchronously stopped from being triggered. By synchronous triggering, the control of triggering can be effectively simplified and the detection speed can be improved.

[0092] Further, during the process of controlling the bright-field detector and the dark-field detector to synchronously scan the surface of the object to be measured, when moving the object to be measured through the moving platform, or moving the bright-field detector and the dark-field detector through the moving platform, during the movement of the moving platform, due to acceleration and deceleration, there may be a jitter situation, which is likely to affect the focusing effect during the scanning process; to ensure the focusing stability, the embodiment of the present application also provides a motion path planning process of the moving platform and a corresponding focusing process.

[0093] 401. Place the object to be measured on the moving platform, and control the moving platform to drive the object to be measured to move so as to scan the surface of the object to be measured.

[0094] In the embodiment of the present application, the object to be measured can be placed on the moving platform, and the moving platform can be controlled to drive the object to be measured to move so as to scan the surface of the object to be measured. Specifically, the object to be measured can be placed on the moving platform. When the bright-field imaging area or the dark-field imaging area is outside the image-side area to be measured on the surface of the object to be measured, control the moving platform to drive the object to be measured to accelerate, that is, accelerate towards the bright-field imaging area and the dark-field imaging area, so that the image-side area to be measured approaches and coincides with the bright-field imaging area and the dark-field imaging area; when the bright-field imaging area or the dark-field imaging area enters the image-side area to be measured on the surface of the object to be measured, control the moving platform to drive the object to be measured to move at a constant speed; when the bright-field imaging area or the dark-field imaging area leaves the image-side area to be measured on the surface of the object to be measured, control the moving platform to drive the object to be measured to decelerate. Among them, based on the center of the field of view of the objective lens, it can be determined that the bright-field imaging area or the dark-field imaging area is outside the image-side area to be measured on the surface of the object to be measured, inside the image-side area to be measured on the surface of the object to be measured, and outside the image-side area to be measured on the surface of the object to be measured by the center of the field of view of the objective lens being outside the image-side area to be measured on the surface of the object to be measured, inside the image-side area to be measured on the surface of the object to be measured, and outside the image-side area to be measured on the surface of the object to be measured.

[0095] During the process of the moving platform driving the object to be measured to move, the opening and closing of the corresponding autofocus (AF) functions of the bright-field detector and the dark-field detector can be controlled based on the moving speed of the moving platform, as shown in the following steps 402 to 430:

[0096] 402. After controlling the moving platform to drive the object to be measured to move at a constant speed, turn on the autofocus functions of the bright-field detector and the dark-field detector.

[0097] It is understandable that after controlling the motion platform to drive the object under test to move at a constant speed, the motion platform will not experience obvious jitter during the constant-speed movement. At this time, the focusing functions of the bright-field detector and the dark-field detector can be enabled. Specifically, the focusing functions of the bright-field detector and the dark-field detector can be enabled based on the surface edge of the object under test and the size of the working focusing spot; that is, when passing through the surface edge of the object under test and entering the surface of the object under test at the center of the field of view of the objective lens, the focusing functions of the bright-field detector and the dark-field detector can be enabled through the size of the working focusing spot; where the size of the working focusing spot for focusing refers to the diameter of the circular spot irradiated by the focusing module on the sample surface, and only when the spot completely hits the sample surface, the returned focusing signal will be accurate.

[0098] 403. Before controlling the motion platform to drive the object under test to decelerate, turn off the focusing functions of the bright-field detector and the dark-field detector.

[0099] It is understandable that when the motion platform decelerates, the motion platform may experience obvious jitter. At this time, before controlling the motion platform to drive the object under test to decelerate, the focusing functions of the bright-field detector and the dark-field detector can be turned off. Specifically, the focusing functions of the bright-field detector and the dark-field detector can be turned off based on the surface edge of the object under test, the size of the working focusing spot, the execution duration of turning off the focus, and the scanning speed. That is, when about to pass through the surface edge of the object under test and leave the surface of the object under test at the center of the field of view of the objective lens, the focusing functions of the bright-field detector and the dark-field detector can be turned off through the execution duration of turning off the focus and the scanning speed. Among them, the execution duration of turning off the focus represents the time required to turn off the focusing function, and the scanning speed represents the moving speed of the motion platform.

[0100] In an implementable manner, when loading a wafer on the motion platform and driving the wafer to move through the motion platform to perform reciprocating scanning on the wafer surface, the positions for turning on and off the focus in the motion platform coordinate system are:

[0101] ForwardAutoFocusStart = wafer edge1 + the size of the working focusing spot;

[0102] ForwardAutoFocusEnd = wafer edge2 - (the size of the working focusing spot + the execution duration of turning off the focus × the scanning speed)

[0103] BackwardAutoFocusStart = wafer edge2 - the size of the working focusing spot

[0104] BackwardAutoFocusEnd = wafer edge1 + (the working spot size of autofocus + the execution duration for turning off autofocus × scanning speed). Here, ForwardAutoFocusStart represents the position where autofocus is turned on during forward scanning, and ForwardAutoFocusEnd represents the position where autofocus is turned off during forward scanning; BackwardAutoFocusStart represents the position where autofocus is turned on during backward scanning, and BackAutoFocusEnd represents the position where autofocus is turned off during backward scanning. It can be understood that during the scanning process, the position of turning off autofocus is determined by the execution duration for turning off autofocus, reserving the execution time for turning off autofocus, effectively avoiding the spot of autofocus from irradiating outside the surface of the object to be measured and preventing errors in autofocus.

[0105] Among them, the path planning of optical detection during the movement of the moving platform is as Figure 7 shown. It can be seen that in the embodiments of the present application, by controlling the detection trigger conditions of the bright-field detector and the dark-field detector, and simultaneously coupling the influence of the jitter of the moving platform and the autofocus module, a scientific path planning method and idea are provided for the bright and dark field automatic optical detection system, effectively ensuring the stability and accuracy during the optical detection process.

[0106] The embodiments of the present application also provide an optical detection device, as Figure 8 shown, including:

[0107] An acquisition unit 801, which acquires a first positional relationship between the bright-field imaging area of the bright-field detector and the image-side area to be measured on the surface of the object to be measured, and a second positional relationship between the dark-field imaging area of the dark-field detector and the image-side area to be measured during the process of controlling the bright-field detector and the dark-field detector to perform relative motion scanning on the surface of the object to be measured; wherein, the bright-field imaging area and the dark-field imaging area are spaced apart by a preset distance in the physical space;

[0108] A control unit 802, configured to control the detection trigger conditions of the bright-field detector and the dark-field detector based on the first positional relationship and the second positional relationship, so as to detect a bright-field image and a dark-field image of the image-side area to be measured.

[0109] The embodiments of the present application also provide an optical detection device 900, as Figure 9 shown. The optical detection device 900 in the embodiments of the present application may include one or more central processing units CPU (CPU, central processing units) 901 and a memory 902, and one or more application programs or data are stored in the memory 902.

[0110] Among them, the memory 902 can be volatile storage or persistent storage. The programs stored in the memory 902 can include one or more modules, and each module can include a series of instruction operations on the electronic device. Further, the central processing unit 901 can be configured to communicate with the memory 902 and execute a series of instruction operations in the memory 902 on the optical detection device 900.

[0111] The optical detection device 900 can also include one or more power supplies 905, one or more wired or wireless network interfaces 904, one or more input / output interfaces 903, and / or one or more operating systems, such as Windows ServerTM, Mac OS XTM, UnixTM, LinuxTM, FreeBSDTM, etc.

[0112] The central processing unit 901 can perform the operations executed by any of the foregoing specific method embodiments, which will not be elaborated herein.

[0113] The embodiment of the present application also provides a computer-readable storage medium, and the computer-readable storage medium includes instructions that, when run on a computer by a processor, implement the method as described above.

[0114] Those skilled in the art can clearly understand that for the convenience and brevity of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments, which will not be elaborated herein.

[0115] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be in an electrical, mechanical, or other form.

[0116] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0117] In addition, in each embodiment of the present application, each functional unit may be integrated in a processing unit, may exist physically alone for each unit, or two or more units may be integrated in one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of a software functional unit.

[0118] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it may be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, may be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, read-only memory), random access memories (RAM, random access memory), magnetic disks, or optical discs that can store program codes.

Claims

1. An optical detection method, characterized in that, Including: During the process of controlling the bright-field detector and the dark-field detector to perform relative motion scanning on the surface of the object to be measured, obtaining a first positional relationship between the bright-field imaging area of the bright-field detector and the image-space area to be measured on the surface of the object to be measured, and a second positional relationship between the dark-field imaging area of the dark-field detector and the image-space area to be measured; wherein, the bright-field imaging area and the dark-field imaging area are spaced apart by a preset distance in physical space; Based on the first positional relationship and the second positional relationship, controlling the detection triggering conditions of the bright-field detector and the dark-field detector to detect a bright-field image and a dark-field image corresponding to the image-space area to be measured.

2. The optical detection method according to claim 1, wherein The controlling the detection triggering conditions of the bright-field detector and the dark-field detector based on the first positional relationship and the second positional relationship includes: When any side area edge of the bright-field imaging area contacts the image-space area to be measured, start triggering the bright-field detector to perform imaging detection; when the opposite side area edge of the bright-field imaging area leaves the image-space area to be measured, stop triggering the bright-field detector; When any side area edge of the dark-field imaging area contacts the image-space area to be measured, start triggering the dark-field detector to perform imaging detection; when the opposite side area edge of the dark-field imaging area leaves the image-space area to be measured, stop triggering the dark-field detector.

3. The optical detection method according to claim 1, characterized in that, The controlling the detection triggering conditions of the bright-field detector and the dark-field detector based on the first positional relationship and the second positional relationship includes: When any side area edge in the bright-field imaging area and the dark-field imaging area contacts the image-space area to be measured, simultaneously start triggering the bright-field detector and the dark-field detector to perform imaging detection; When the opposite side area edge of the side area edge in the bright-field imaging area and the dark-field imaging area leaves the image-space area to be measured, simultaneously stop triggering the bright-field detector and the dark-field detector.

4. The optical detection method according to claim 2 or 3, characterized in that, When the area size of the bright-field imaging area or the dark-field imaging area is smaller than the area size of the image-space area to be measured, controlling the bright-field detector and the dark-field detector to simultaneously perform relative motion scanning on the surface of the object to be measured includes: Controlling the bright-field detector and the dark-field detector to simultaneously scan the surface of the object to be measured in relative motion in a first scanning direction; When both the bright-field imaging area and the dark-field imaging area leave the image-space area to be measured, controlling the bright-field detector and the dark-field detector to simultaneously scan the surface of the object to be measured in relative motion in a second scanning direction; wherein, the second scanning direction is opposite to the first scanning direction, and the scanning areas of the second scanning direction and the first scanning direction have an overlapping part.

5. The optical detection method according to claim 4, wherein The controlling the detection triggering conditions of the bright-field detector and the dark-field detector based on the first positional relationship and the second positional relationship includes: Obtaining a scanning compensation value in the first scanning direction and a scanning compensation value in the second scanning direction; During the scanning in the first scanning direction, based on the first positional relationship and the second positional relationship, determine the first initial trigger positions of the bright-field detector and the dark-field detector, and compensate the first initial trigger positions with the scanning compensation value in the first scanning direction to obtain the first target trigger positions; During the scanning in the second scanning direction, based on the first positional relationship and the second positional relationship, determine the second initial trigger positions of the bright-field detector and the dark-field detector, and compensate the second initial trigger positions with the scanning compensation value in the second scanning direction to obtain the second target trigger positions.

6. The optical detection method according to claim 1, wherein The method further includes: Carry the object to be measured on a moving platform. When the bright-field imaging area or the dark-field imaging area is outside the image-side area to be measured on the surface of the object to be measured, control the moving platform to drive the object to be measured to accelerate, so that the image-side area to be measured approaches and coincides with the bright-field imaging area and the dark-field imaging area; When the bright-field imaging area or the dark-field imaging area enters the image-side area to be measured on the surface of the object to be measured, control the moving platform to drive the object to be measured to move at a constant speed; When the bright-field imaging area or the dark-field imaging area leaves the image-side area to be measured on the surface of the object to be measured, control the moving platform to drive the object to be measured to decelerate.

7. The optical detection method according to claim 6, wherein After controlling the moving platform to drive the object to be measured to move at a constant speed, turn on the focus tracking functions of the bright-field detector and the dark-field detector; Before controlling the moving platform to drive the object to be measured to decelerate, turn off the focus tracking functions of the bright-field detector and the dark-field detector.

8. The optical detection method according to claim 7, wherein The turning on of the focus tracking functions of the bright-field detector and the dark-field detector includes: Based on the surface edge of the surface of the object to be measured and the size of the working light spot for focus tracking, turn on the focus tracking functions of the bright-field detector and the dark-field detector; The turning off of the focus tracking functions of the bright-field detector and the dark-field detector includes: Based on the surface edge of the surface of the object to be measured, the size of the working light spot for focus tracking, the execution duration of turning off the focus tracking, and the scanning speed, turn off the focus tracking functions of the bright-field detector and the dark-field detector.

9. An optical detection device, characterized in that, It includes: An acquisition unit, during the process of controlling the bright-field detector and the dark-field detector to perform relative motion scanning on the surface of the object to be measured, acquire the first positional relationship between the bright-field imaging area of the bright-field detector and the image-side area to be measured on the surface of the object to be measured, and the second positional relationship between the dark-field imaging area of the dark-field detector and the image-side area to be measured; wherein, the bright-field imaging area and the dark-field imaging area are spaced apart by a preset distance in physical space; A control unit, configured to control the detection trigger conditions of the bright-field detector and the dark-field detector based on the first positional relationship and the second positional relationship, so as to detect the bright-field image and the dark-field image of the image-side area to be measured.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes instructions that, when executed by a processor on a computer, implement the method according to any one of claims 1 to 8.

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