Optical detection method and system, equipment and storage medium

Abstract

An optical detection method, system and device and a storage medium are used for detecting the height of a feature point of a to-be-detected object, and the method comprises the following steps: obtaining a region of interest of a detector target surface according to the estimated height of the feature point of the to-be-detected object; imaging the to-be-detected object by using the detector, and obtaining the position of an imaging light spot of the feature point in the region of interest of the target surface of the detector; and obtaining the measurement height of the feature point along the direction perpendicular to the surface of the object to be measured according to the position of the imaging light spot of the region of interest. According to the invention, the calculation power is saved, the detection efficiency is improved, and high-stability and high-precision optical detection is realized.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of optical detection, and in particular, to an optical detection method and system, device and storage medium. Background Art

[0002] With the rapid development of integrated circuit manufacturing technology, advanced packaging forms such as 2.5D / 3D integration and wafer-level packaging have become the main direction of packaging technology development.

[0003] With the high-density development of integrated circuit manufacturing, the package size is getting smaller and smaller, and the interconnection density is increasing. In integrated circuits, the size and spacing of the bumps connecting the chips are getting smaller and smaller. At the same time, the interconnection short circuit problem caused by solder deformation is becoming increasingly prominent. Therefore, the demand for three-dimensional defect detection of chip bump coplanarity is more urgent.

[0004] Currently, optical detection methods are usually used for three-dimensional defect detection. Summary of the invention

[0005] The problem solved by the embodiments of the present invention is to provide an optical detection method and system, equipment and storage medium to achieve high-stability and high-precision optical detection.

[0006] To solve the above problems, an embodiment of the present invention provides an optical detection method for detecting the height of feature points of an object to be measured, including: obtaining an area of ​​interest on the detector target surface according to the estimated height of the feature points of the object to be measured; using the detector to image the object to be measured to obtain the position of the imaging spot of the feature point in the area of ​​interest on the detector target surface; and obtaining the measured height of the feature point along a direction perpendicular to the surface of the object to be measured according to the position of the imaging spot of the area of ​​interest.

[0007] An embodiment of the present invention also provides an optical detection system for detecting the height of feature points of an object to be measured, comprising: an area of ​​interest acquisition module, used to acquire the area of ​​interest of the detector target surface according to the estimated height of the feature points of the object to be measured; an imaging module, used to image the object to be measured using the detector, and acquire the position of the imaging spot of the feature point in the area of ​​interest of the detector target surface; and a measured height acquisition module, used to acquire the measured height of the feature point along a direction perpendicular to the surface of the object to be measured according to the position of the imaging spot of the area of ​​interest.

[0008] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0009] In the parameter setting method for optical detection provided by an embodiment of the present invention, an area of ​​interest on the detector target surface is obtained according to the estimated height of the feature point of the object to be detected, the detector is used to image the object to be detected, the position of the imaging spot of the feature point in the area of ​​interest on the detector target surface is obtained, and the measured height of the feature point along a direction perpendicular to the surface of the object to be detected is obtained according to the position of the imaging spot in the area of ​​interest; the embodiment of the present invention obtains the area of ​​interest and then uses the imaging spot position of the area of ​​interest to calculate the measured height of the feature point, which is beneficial to saving computing power, improving detection efficiency, and realizing high-stability and high-precision optical detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A flow chart of an embodiment of a detection method of the present invention;

[0011] Figure 2 and Figure 3 is a schematic diagram of a detection device and a light path diagram corresponding to an embodiment of a detection method of the present invention;

[0012] Figure 4 yes Figure 3 A local magnified image of any convex point to be tested;

[0013] Figure 5 is a top view of a detection device corresponding to an embodiment of a detection method of the present invention;

[0014] Figure 6 is a functional block diagram of an embodiment of a detection system of the present invention;

[0015] Figure 7 It is a hardware structure diagram of an embodiment of the device provided by the present invention. DETAILED DESCRIPTION

[0016] As can be seen from the background technology, optical detection method is a commonly used detection technology for feature points on the object to be detected. However, in the existing optical detection methods used for detection, the accuracy of the detection results needs to be improved, and a better optical detection parameter setting method is needed to achieve high stability and high precision optical detection.

[0017] In order to solve the technical problem, an embodiment of the present invention provides an optical detection method for detecting the height of feature points of an object to be measured, including: obtaining an area of ​​interest on a detector target surface according to the estimated height of the feature points of the object to be measured; using the detector to image the object to be measured to obtain the position of an imaging spot of the feature point in the area of ​​interest on the detector target surface; and obtaining the measured height of the feature point along a direction perpendicular to the surface of the object to be measured according to the position of the imaging spot of the area of ​​interest.

[0018] The embodiment of the present invention obtains the region of interest and then uses the imaging spot position of the region of interest to calculate the measured height of the feature point, which is beneficial to saving computing power, improving detection efficiency, and achieving high-stability and high-precision optical detection.

[0019] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0020] refer to Figure 1 , Figure 1 It is a flow chart of an embodiment of the detection method of the present invention.

[0021] In this embodiment, the detection method includes the following steps:

[0022] Step S1: obtaining an area of ​​interest on the detector target surface according to the estimated height of the feature point of the object to be measured;

[0023] Step S2: imaging the object to be measured using a detector to obtain the position of the imaging spot of the feature point in the region of interest on the detector target surface;

[0024] Step S3: obtaining the measured height of the feature point along the direction perpendicular to the surface of the object to be measured according to the position of the imaging light spot in the region of interest.

[0025] The embodiment of the present invention obtains the region of interest and then uses the imaging spot position of the region of interest to calculate the measured height of the feature point, which is beneficial to saving computing power, improving detection efficiency, and achieving high-stability and high-precision optical detection.

[0026] The following describes each step of the detection method in conjunction with the detection system.

[0027] Combined with reference Figures 2 to 5 , Figure 2 and Figure 3 is a schematic diagram of a detection device and a light path diagram corresponding to an embodiment of a detection method of the present invention, Figure 4 yes Figure 3 A local enlarged view of any bump to be tested. Figure 5 Detailed description of the detection method described in this embodiment is given.

[0028] In this embodiment, the optical detection method is suitable for performing detection scanning on the object to be detected 100 using the incident light spot 800s, and the detection scanning uses the detector 810 to image the object to be detected 100.

[0029] Specifically, in this embodiment, the incident light is reflected on the surface of the object to be measured 100 to form a signal light, forming a triangular light path, so that the height of the feature point is detected by using the triangulation method.

[0030] In other embodiments, a dispersion spectrometer may be used to detect the height, or a confocal microscope may be used to detect the height.

[0031] Combined with reference Figure 2 and Figure 3 , the characteristic point is the convex point 101 to be measured, and the detection method of this embodiment is used to measure the microscopic three-dimensional morphology of the height of the convex point 101 to be measured.

[0032] In this embodiment, the optical detection method is suitable for forming an incident light spot 800s on the surface of the object to be tested 100 having sampling points through incident light, and collecting signal light from the sampling points through a detector 810 to obtain the measured height of the feature points according to the signal light, and the sampling points include the feature points.

[0033] As an example, the object to be tested 100 with sampling points is a wafer, and the optical detection of this embodiment is used to detect three-dimensional defects of coplanarity of convex points on the wafer surface. In other embodiments, the object to be tested can also be a mobile phone case, a chip, a glass surface, etc.

[0034] In this embodiment, the sampling points also include reference points on the surface of the object to be tested 100 .

[0035] This embodiment can obtain the height difference between the feature point and the reference point by optically detecting the sampling point, thereby obtaining the actual measured height of the feature point.

[0036] Execute step S1: obtain the region of interest of the target surface 80 of the detector 810 according to the estimated height of the feature point of the object to be detected 100.

[0037] The region of interest (ROI) is obtained, and the subsequent detection of sampling points is performed by analyzing the ROI to reduce the workload and improve efficiency.

[0038] In this embodiment, the detector 810 includes a first detector 820 and a second detector 830 (eg, Figure 3 shown).

[0039] In this embodiment, the two detectors 810 work alternately to collect imaging information of the incident light spot 810s and the incident light spot 820s respectively until the linear scan of the object to be detected 100 is completed, which is beneficial to improving the detection efficiency.

[0040] In other embodiments, the detector may also include only one detector (eg Figure 2 shown).

[0041] Accordingly, in this embodiment, obtaining the region of interest on the target surface 80 of the detector 810 according to the estimated height of the feature point of the object to be measured 100 includes: respectively obtaining the region of interest on the target surface 80 of the first detector 820 and the target surface 80 of the second detector 830 .

[0042] The regions of interest on the target surface 80 of the first detector 820 and the target surface 80 of the second detector 830 are acquired respectively, and then the information acquired from the regions of interest of the first detector 820 and the second detector 830 are spliced ​​according to the scanning sequence to obtain the global information of the object to be detected 100.

[0043] In this embodiment, the region of interest of the target surface 80 of the detector 810 is obtained according to the estimated height of the feature point of the object to be detected 100, including: determining the size of the region of interest along the first direction of the target surface 80 of the detector 810 according to the estimated height of the feature point.

[0044] A height direction is preset on the target surface 80 of the detector 810 , namely, the first direction. In this embodiment, the first direction is the column direction of the target surface 80 of the detector 810 .

[0045] Specifically, in this embodiment, the size of the first direction in the region of interest of the target surface 80 of the detector 810 is obtained according to the estimated height of the feature point of the object to be detected 100, and the size of the first direction is the scanning direction of the detection scan (such as Figure 5 The dimensions are shown in the X direction.

[0046] In this embodiment, the size of the region of interest along the first direction of the target surface 80 of the detector 810 is determined based on the estimated height of the feature point, including: obtaining the corresponding height value within the height range of the feature point, and the mapping relationship between the size of the region of interest along the first direction, the mapping relationship including: the larger the corresponding height value within the height range of the feature point, the larger the size of the region of interest along the first direction.

[0047] That is to say, the mapping relationship between the height interval of the feature point and the size of the region of interest along the scanning direction of the detection scan is obtained. The larger the corresponding height value in the height interval of the feature point, the larger the size of the region of interest along the scanning direction of the detection scan.

[0048] This embodiment is for detecting the height of feature points. The larger the height of the feature points is, the larger the distance between the feature points and the reference point light spots on the target surface 80 of the detector 810 is, and the corresponding region of interest needs to be larger in the scanning direction of the detection scan. At the same time, the height of the feature points is divided into height intervals of the feature points to reduce the amount of change in the region of interest for different feature point heights and simplify the method of setting the region of interest.

[0049] In this embodiment, the height interval in which the estimated height of the feature point is located is obtained.

[0050] The height interval is obtained, which is used as a reference for obtaining the size of the region of interest in the first direction.

[0051] Correspondingly, in this embodiment, the size of the region of interest along the first direction of the target surface 80 of the detector 810 is obtained according to the height interval where the estimated height of the feature point is located and the mapping relationship.

[0052] In this embodiment, before obtaining the area of ​​interest of the target surface 80 of the detector 810 according to the estimated height of the feature point of the object to be measured 100, it also includes: obtaining the position deviation of the sampling spot formed by the first detector 820 and the second detector 830 collecting signal light in the same area on the object to be measured 100; obtaining a position correction parameter according to the position deviation, the position correction parameter is an integer multiple of a single correction step length, and the integer multiple is set to: suitable for reducing the absolute value of the difference between the position correction parameter and the position deviation.

[0053] The position deviation of the sampling spot formed by the signal light collected by the first detector 820 and the second detector 830 in the same area on the object to be tested 100 is, that is, the position deviation of the same position point on the target surface 80 of the first detector 820 and the second detector 830 relative to the target surface 80. In the actual detection process, the calibration of the detector 810 usually has a fixed calibration step and is difficult to adjust at will. As an example, the position deviation of the first detector 820 and the second detector 830 is dC, and the position calibration parameter obtained according to dC is dC1=n*k, where n is an integer and k is a single calibration step.

[0054] Specifically, in this embodiment, the integer multiple is set to: make the absolute value of the difference between the position correction parameter and the position deviation reach the minimum value, which is conducive to making the image information of the corrected first detector 820 and the second detector 830 closest, and at the same time is conducive to the subsequently obtained second correction parameter being as small as possible, so that less calculation compensation is performed in the subsequent calculation process, reducing calculation errors.

[0055] In this embodiment, the aforementioned position correction parameter is used as the first correction parameter, and a second correction parameter is obtained according to the position deviation, and the second correction parameter is the difference between the position deviation and the first correction parameter.

[0056] In the actual detection process, the calibration of the detector 810 usually has a fixed calibration step. Therefore, it is usually difficult to calibrate exactly according to the fixed calibration step. Moreover, the calibration step of the detector 810 is usually an integer. Therefore, it is also difficult to calibrate exactly according to the calibration step for position deviations with decimals. Therefore, it is also necessary to obtain a second calibration parameter that cannot be adjusted by a fixed calibration step for subsequent calculation compensation in the calculation process. As an example, the second calibration parameter is dC2=dC-dC1.

[0057] For example, the position deviation dC between the first detector 820 and the second detector 830 is 14 pixels, and the single correction step length k is 4 pixels, then n is taken as 3, and the second correction parameter dC2=dC-dC1=2 is obtained.

[0058] For another example, the position deviation dC between the first detector 820 and the second detector 830 is 14.3 pixels, and the single correction step length k is 4 pixels, then n is taken as 3, and the second correction parameter dC2=dC-dC1=2.3 is obtained.

[0059] In this embodiment, the grayscale deviation of the sampling spot formed by the first detector 820 and the second detector 830 collecting the signal light in the same area on the object to be measured 100 is also obtained as a grayscale calibration value for calculation compensation of grayscale value calculation in the subsequent calculation process.

[0060] In this embodiment, the starting positions of the regions of interest on the target surface 80 of the first detector 820 and the target surface 80 of the second detector 830 are respectively obtained, and the difference between the starting positions of the two is used as the position correction parameter.

[0061] The difference between the starting positions of the regions of interest of the first detector 820 and the second detector 830 is obtained as a position correction parameter. That is, the starting position of the region of interest of the detector 810 that is closer to the origin when calculating the position deviation is used as a reference, and the starting position of the region of interest of the other detector 810 is set as the reference + dG1, so that the images obtained from the regions of interest of the first detector 820 and the second detector 830 are basically consistent.

[0062] In this embodiment, the position deviation of the sampling spot formed by the signal light collected by the first detector 820 and the second detector 830 in the same area on the object to be tested 100 is obtained, including: for the same area on the object to be tested 100, a first calibration image is obtained using the target surface 80 of the first detector 820, and a second calibration image is obtained using the target surface 80 of the second detector 830.

[0063] The first calibration image and the second calibration image are used to obtain the position deviation of the same point on the object to be measured 100 on the two detectors 810 .

[0064] In this embodiment, the image center positions of the first calibration image and the second calibration image are calculated respectively.

[0065] Usually, the first calibration image and the second calibration image are obtained as sampling spots, so calculating the center position of the image is to calculate the position of the same point on the object to be tested 100. Using the center position of the image as the calibration reference is conducive to simplifying the method of selecting the position of the same point on the object to be tested 100, making it easy to obtain the position deviation of the position of the same point.

[0066] Accordingly, in this embodiment, the position deviation of the first detector 820 and the second detector 830 is obtained by comparing the center positions of the light spots of the first calibration image and the second calibration image.

[0067] In this embodiment, before acquiring the region of interest of the target surface 80 of the detector 810 according to the estimated height of the feature point of the object to be detected 100, the detection method further includes: acquiring a scanning step length of the detection scan.

[0068] It should be noted that the scanning step length should not be too large. If the scanning step length is too large, a gap is likely to be generated between two adjacent incident light spots 800s in the subsequent detection scan, resulting in an incomplete scan of the surface of the object 100 to be tested, and thus making it difficult to perform a complete detection of the object 100 to be tested, affecting the detection result. For this reason, in this embodiment, the scanning step length is less than or equal to the size of the incident light spot 800s along the scanning direction, so as to ensure that the two adjacent incident light spots 800s are exactly spliced ​​or have overlapping parts.

[0069] In this embodiment, obtaining the scanning step length of the detection scan includes: obtaining a mapping relationship between the diameter interval of the feature point and the scanning step length, and the larger the diameter value corresponding to the diameter interval of the feature point is, the larger the scanning step length is.

[0070] In order to efficiently scan the object to be measured 100, the scanning step length is increased accordingly when the diameter of the feature point is larger, which is beneficial to ensure that the total number of times the signal light is captured during the scanning process will not be too many. At the same time, the diameter is divided into diameter intervals to reduce the change in the scanning step length for different diameters and simplify the method of setting the scanning step length.

[0071] Specifically, in this embodiment, the scanning step length is obtained according to the estimated diameter of the feature point and the mapping relationship.

[0072] As an example, when the estimated diameter of the feature point is within a diameter interval of less than or equal to 60 μm, a scanning step length of 3 μm is obtained; when the estimated diameter of the feature point is within a diameter interval of greater than 60 μm, a scanning step length of 6 μm is obtained.

[0073] In this embodiment, before acquiring the region of interest on the target surface of the detector 810 , the process further includes: pre-scanning the object to be detected 100 to obtain an image of the object to be detected 100 .

[0074] The image of the object to be tested 100 is used to adjust the placement position of the object to be tested 100 and is also used as a basis for planning a detection scanning path during the detection scanning process.

[0075] In this embodiment, the placement position of the object to be measured 100 is calibrated according to the image.

[0076] The placement position of the object to be tested 100 is calibrated according to the image, so that the placement position of the object to be tested 100 relative to the detection device is more accurate.

[0077] In this embodiment, a path planning is performed for detecting and scanning the object to be tested 100 according to the image, and the path planning covers all feature points on the surface of the object to be tested 100 .

[0078] The path planning for the detection scan of the object to be detected 100 is performed according to the image, so that the scanning path of the detection scan is reasonable and relatively accurate.

[0079] Execute step S2: use the detector 810 to image the object to be measured 100, and obtain the position of the imaging spot of the feature point in the area of ​​interest of the target surface 80 of the detector 810.

[0080] The position of the imaging spot of the feature point in the region of interest of the target surface 80 of the detector 810 is obtained, which is used as a reference for the subsequent acquisition of the measurement height of the feature point.

[0081] In this embodiment, the detector 810 is used to image the object to be tested 100, including: using the incident light spot 800s to detect and scan the object to be tested, so that the incident light spot 800s and the object to be tested 100 are relatively translated, so as to use the detector 810 to perform multiple imaging on the object to be tested 100 and obtain multiple detection images.

[0082] The object to be tested 100 is scanned and the sampling points are placed at different relative positions through continuous relative movement. The relative position is the position of the sampling point relative to the object to be tested 100 .

[0083] In this embodiment, the direction of the detection scan (such as Figure 5 The X direction is perpendicular to the length direction of the incident light spot 800s.

[0084] In this embodiment, during the scanning process, the detector 810 collects signal light once every scanning step, and the scanning step is less than or equal to the size of the incident light spot 800s along the scanning direction.

[0085] In this embodiment, the length of the incident light spot 800s is relatively large and the width is relatively small. After scanning the area spanned by the length of the incident light spot 800s on the surface of the object to be measured 100 along the scanning direction, this embodiment can perform the next round of scanning of the area spanned by the length of the incident light spot 800s, which is beneficial to ensure the regularity of each scanning translation and reduce the jumpiness of the scanning, which is beneficial to make the scanning of the surface of the object to be measured 100 simple and smooth.

[0086] In this embodiment, using the incident light spot 800s to detect and scan the object to be tested includes: forming the incident light spot 800s on the surface of the object to be tested 100 by the incident light, and the incident light forms a signal light after passing through the sampling point.

[0087] In this embodiment, the incident angle α of the incident light is less than 45 degrees or greater than 45 degrees.

[0088] In this embodiment, the incident angle of the incident light is less than 45 degrees, which is beneficial to reduce the probability of feature points on the object to be tested 100 being blocked by flexibly adjusting the incident angle of the incident light, so that the feature points can obtain more sufficient illumination, which is beneficial to making the imaging of the feature points more accurate. The incident angle of the incident light is greater than 45 degrees, which is beneficial to increase the space above the object to be tested 100 by flexibly adjusting the incident angle of the incident light, so as to facilitate the installation of other detection devices.

[0089] In this embodiment, the incident angle of the incident light is 25 degrees to 35 degrees.

[0090] The incident light is mirror-reflected by the surface of the object to be tested 100, and the incident angle of the incident light is equal to the reflection angle of the signal light. The incident angle of the incident light is 25 to 35 degrees. This ensures that the feature points can be more fully illuminated, and is conducive to facilitating the setting of the relative positions of the lighting module and the imaging module in the detection equipment, and is also conducive to the complete reception of the signal light by the imaging module, thereby facilitating more accurate imaging in the imaging module.

[0091] In this embodiment, the incident light spot 800s is in a strip shape, so that the detection device can be used to perform linear scanning on the object to be detected 100. In other embodiments, the incident light spot can also be a point light spot or a regional light spot.

[0092] The object to be measured 100 is scanned using a strip-shaped incident light spot 800s. Along the scanning direction, the edges of adjacent linear incident light spots 800s can be just butted against or partially overlapped. The linear incident light spots 800s are used to complete the linear scanning, which is beneficial to achieving full coverage of the object to be measured 100 by all linear incident light spots 800s. At the same time, each linear incident light spot 800s can be fully utilized, and a smaller number of linear incident light spots 800s can be used to complete the scanning of the object to be measured 100, thereby helping to improve the scanning efficiency.

[0093] Specifically, in conjunction with reference Figure 2 and Figure 3 The detection device used in the detection method includes a lighting module, the lighting module includes a light path transmission direction (such as Figure 2 and Figure 3 The light source assembly 200, the first slit element 400 and the first lens group 500 are sequentially arranged (as shown by the direction of the arrow on the dotted line), the light source assembly 200 is used to generate a linear light beam, the first slit element 400 is used to allow the light beam to pass through to generate a linear incident light, and the first lens group 500 is used to focus the linear incident light onto the object to be measured 100 to generate a strip-shaped incident light spot 800s.

[0094] In this embodiment, along the transmission direction of the optical path, the light beam generated by the light source assembly 200 passes through the first slit element 400, thereby generating an incident light spot 800s on the object to be measured 100. Therefore, compared with a circular light beam, the light source assembly 200 generates a linear light beam. When the light beam generated by the light source assembly 200 is coupled with the first slit element 400, it is beneficial to reduce the waste of light beam energy and improve the coupling efficiency.

[0095] In this embodiment, the light source assembly 200 includes a light source and a shaping element 220 . The light source is an incoherent light source. The shaping element 220 is used to shape the light emitted by the light source to generate a linear light beam.

[0096] The light source in this embodiment is an incoherent light source. Compared with a coherent light source (for example, a laser light source), an incoherent light source has smaller noise points. Therefore, the light beam generated by the incoherent light source ultimately has a higher image signal-to-noise ratio in the imaging module, thereby being able to obtain more accurate imaging information of feature points in the imaging module.

[0097] Specifically, in this embodiment, the types of light sources include LED light sources, halogen lamps or xenon lamps.

[0098] In practical applications, an incoherent light source usually emits a circular light beam. Therefore, the shaping element 220 is used to shape the light emitted by the light source to ensure that the light source assembly 200 generates a linear light beam.

[0099] In this embodiment, the shaping element 220 includes: an optical fiber bundle, the shape of the incident port of the optical fiber bundle matches the shape of the light spot of the light emitted by the light source, and the optical fibers at the output port of the optical fiber bundle are arranged in a straight line.

[0100] The use of an optical fiber bundle to shape the light emitted by a light source is simple and easy to operate, and the port shape of the optical fiber bundle is easy to adjust, so that the incident port of the optical fiber bundle can be adjusted according to the light spot formation of the light emitted by the light source, and the exit port of the optical fiber bundle can be adjusted according to the shape of the incident light to be obtained.

[0101] In this embodiment, the shape of the incident port of the optical fiber bundle matches the spot shape of the light emitted by the light source, thereby improving the coupling efficiency between the light emitted by the light source and the optical fiber bundle. The shape of the output port of the optical fiber bundle is in a straight line, thereby enabling the light source assembly 200 to generate a linear light beam.

[0102] In this embodiment, the light source assembly 200 further includes a filter color wheel for controlling the spectrum emitted by the light source assembly 200 .

[0103] As an example, the light source assembly 200 includes a light box 210 , in which a light source and a filter color wheel are disposed. The filter color wheel is used to control the spectrum emitted by the light box 210 .

[0104] The light box 210 is used as a device for placing a light source and a filter color wheel.

[0105] As an example, the light source emits white light, and after passing through the filter color wheel, the light box 210 can emit blue, green, yellow or red light.

[0106] In this embodiment, the spectrum of the filter color wheel is adjusted according to the spectrum of the surface coating of the feature point, for example, according to the spectrum of the coating on the surface of the wafer. Specifically, the spectrum of the filter color wheel is consistent with the spectrum of the surface coating of the feature point, which is conducive to improving the signal-to-noise ratio of the signal light generated by the incident light on the surface of the feature point.

[0107] In this embodiment, the length direction of the slit opening in the first slit element 400 is perpendicular to the incident surface of the optical path of the incident light, so that linear incident light matching the slit opening can be obtained. Accordingly, in this embodiment, the length of the linear incident light obtained is controlled by setting the slit opening length of the first slit element 400.

[0108] The first lens group 500 is used to focus the linear incident light onto the object to be measured to generate a linear light spot, and is also used to control the size of the generated linear light spot. As an example, the first lens group 500 is a first microscope objective lens.

[0109] In this embodiment, the size and spacing of the bumps to be tested are usually small, so a finer incident light spot of 800s is required to detect the bumps to be tested.

[0110] In this embodiment, the first lens group 500 is used to reduce the first slit element 400 and image it on the object to be tested 100, thereby reducing the width of the linear incident light passing through the first slit element 400, so that an incident light spot 800s with a smaller width can be obtained. When the incident light spot 800s is used to perform a linear scan on the object to be tested 100, it is beneficial to improve the scanning accuracy, thereby improving the accuracy of the detection result.

[0111] In this embodiment, the first slit element 400 and the first lens group 500 are used to shape and image the light beam generated by the light source assembly 200. The first lens group 500 can be used to reduce the first slit element 400 and image it on the object to be tested 100, so that a smaller incident light spot 800s can be obtained. The incident light spot 800s forms signal light through the object to be tested 100, which is conducive to obtaining higher-precision imaging information and correspondingly obtaining high-stability and high-precision detection results.

[0112] In this embodiment, the lighting module further includes: a fiber coupler 300 disposed between the light source assembly 200 and the first slit element 400 , and the fiber coupler 300 is used to couple the light beam to the slit opening of the first slit element 400 .

[0113] In this embodiment, the light source assembly 200 generates a linear light beam through an optical fiber bundle, and the light beam generated by the optical fiber bundle is a discontinuous light spot. Therefore, the optical fiber coupler 300 is used to converge the light beam and couple it at the slit opening of the first slit element 400, which is beneficial to improve the lighting efficiency of the incident light, control the light of the incident light, reduce the divergence of the incident light, and help improve the uniformity of imaging in the imaging module.

[0114] In this embodiment, the optical fiber coupler 300 includes: a cylindrical mirror 310, which is arranged on a side of the optical fiber coupler 300 close to the light emitting end face, or arranged on a side of the optical fiber coupler 300 close to the light incident end face.

[0115] The cylindrical mirror 310 is used to improve the lighting efficiency and uniformity of the incident light.

[0116] Specifically, in this embodiment, the detection device includes an imaging module, and the imaging module includes an imaging component 600 and a detector 810 . The imaging component 600 is used to converge the signal light into the detector 810 .

[0117] In this embodiment, at least part of the signal light is collected by the detector 810, and imaging information of the sampling point is acquired according to the collected signal light, and the imaging information includes the spot position of the sampling spot of the sampling point.

[0118] In this embodiment, the target surface 80 is perpendicular to the incident direction of the corresponding received signal light, so that the setting of the target surface 80 in this embodiment is relatively simple and the modification to the original detection system is reduced.

[0119] Specifically, the detection device also includes: a beam splitter 700, which is used to transmit the received signal light along multiple different optical path directions, and project the signal light transmitted along multiple different optical path directions into the detector 810 respectively, and each detector 810 collects each signal light in turn to form an image of different areas of the object to be tested 100.

[0120] In this embodiment, the signal light transmitted by the beam splitter 700 along a plurality of different optical path directions is projected onto the first detector 820 and the second detector 830 respectively.

[0121] In this embodiment, the imaging component 600 includes a second lens group 620, an aperture 630 and a tube lens 640 which are arranged in sequence along the light path transmission direction. The second lens group 620 is used to collect signal light and inject the signal light into the aperture 630. The tube lens 640 is used to receive the signal light passing through the aperture 630 and converge the signal light.

[0122] In this embodiment, the second lens group 620 is used to amplify the optical path of the signal light, so that the imaging of the feature point is clearer. As an example, the second lens group 620 is a second microscope objective lens.

[0123] In this embodiment, the aperture 630 is used to control the amount of signal light passing through. The aperture 630 is also used to limit the telecentricity of the main light of the signal light, so that the telecentricity of the signal light is infinitely close to 0, which is beneficial to making the imaging quality of each field of view in the imaging module uniform, thereby facilitating the acquisition of imaging information with higher accuracy.

[0124] In this embodiment, the aperture 630 images the feature point at infinity, and the tube lens 640 is used to image the feature point at a finite distance. Correspondingly, it is used to image the feature point on the detector 810. The use of the aperture 630 and the tube lens 640 in combination is beneficial to ensure that the imaging quality of the signal light on the detector 810 is uniform, clear and accurate after passing through the imaging component 600.

[0125] In this embodiment, the imaging assembly 600 further includes: a second slit element 610 disposed on a side of the second lens group 620 facing away from the aperture 630 , and the second slit element 610 is used to reduce stray light of the signal light.

[0126] In this embodiment, the second slit element 610 is used to limit the numerical aperture (NA) of the optical system of the signal light and reduce the divergence of the signal light.

[0127] In this embodiment, before imaging the object 100 using the detector 810 , after acquiring the region of interest of the target surface 80 of the detector 810 , the process further includes: obtaining the focus position of the detector 810 , and determining whether the focus position is qualified.

[0128] In this embodiment, the focus position of the detector 810 is obtained based on the optical axis position of the detector 810, the area of ​​interest of the target surface 80 of the detector 810, and the longitudinal position deviation (Yoffset) of the detector 810. In the actual detection process, the required focus position is pre-set as the preset position according to actual needs. For example, the top of the feature point is set as the preset position, and then the focus position and the preset position are used to determine whether it meets the requirements, that is, whether it is qualified.

[0129] In this embodiment, when the deviation between the focus position and the preset position is less than or equal to a preset threshold, the focus position is qualified; when the deviation between the focus position and the preset position is greater than the preset threshold, the focus is adjusted according to the deviation between the focus position and the preset position; after the focus adjustment, the process returns to execute detection scanning of the object to be tested using the incident light spot.

[0130] When the deviation between the focus position and the preset position is less than or equal to the preset threshold, it means that the focus position is relatively accurate and meets the requirements, and the focus position is qualified; when the deviation between the focus position and the preset position is greater than the preset threshold, it means that the focus position deviates far from the preset position, and does not meet the requirements, and the focus position needs to be adjusted. After the focus adjustment, return to execute the detection scan of the object to be tested using the incident light spot.

[0131] Execute step S3: obtain the measured height of the feature point along the direction perpendicular to the surface of the object 100 according to the position of the imaging light spot of the region of interest.

[0132] This embodiment obtains the region of interest and then uses the imaging spot position of the region of interest to calculate the measured height of the feature point, which is beneficial to saving computing power, improving detection efficiency, and achieving high-stability and high-precision optical detection.

[0133] In this embodiment, the measured height of the feature point along the direction perpendicular to the surface of the object 100 is obtained according to the position of the imaging spot in the region of interest, including: obtaining the top centroid position and the bottom centroid position of the feature point in the region of interest according to multiple detection images.

[0134] The top centroid position and the bottom centroid position are used to calculate the height of the feature point.

[0135] Specifically, in conjunction with reference Figure 4 In this embodiment, the incident angle α of the incident light is less than 45 degrees. Figure 4 A partial enlarged view of any bump to be tested is shown for ease of explanation. Figure 4In the figure, two convex points to be tested with different heights overlap, wherein a black solid convex point is used to represent the first convex point to be tested 101a, and a dotted outline is used to represent the second convex point to be tested 101b. For the first convex point to be tested 101a, when the incident light is irradiated on the first convex point to be tested 101a, it is reflected by point P to form a signal light (the optical path of the signal light formed by the reflection of point P is represented by a dotted line), and the imaging spot on the target surface 80 is at point P'. For the second convex point to be tested 101b, when the incident light is irradiated on the second convex point to be tested 101b, it is reflected by point Q to form a signal light (the optical path of the signal light formed by the reflection of point P is represented by a solid line), and the imaging spot on the target surface 80 is at point Q'.

[0136] In this embodiment, the target surface 80 is perpendicular to the incident direction of the corresponding received signal light, therefore, the conjugate image of the target surface 80 is located on the base surface 80e passing through point P, and the base surface 80e is perpendicular to the main optical path 10b of the signal light, however, the incident angle α of the incident light is less than 45 degrees, and the incident light is mirror reflected, then the incident light and the signal light are not perpendicular, therefore, the base surface 80e and the optical axis 10a of the incident light do not coincide, that is, point Q on the second convex point 101b to be measured is not on the base surface 80e, so that the imaging spot of the incident light passing through point Q is a diffuse spot, that is, point Q cannot be clearly imaged at point Q', but forms a diffuse spot at point Q', therefore, in order to obtain a clear position of point Q', the diffuse spot also needs to be processed.

[0137] In this embodiment, the center of the diffuse spot is extracted to obtain the center of the diffuse spot, which is the clear position of the Q' point, that is, the centroid position.

[0138] In this embodiment, the method for center extraction includes grayscale centroid method, quadratic curve fitting vertex method, Gaussian curve fitting vertex method, centroid method or maximum value position method.

[0139] Grayscale centroid method, quadratic curve fitting vertex method, Gaussian curve fitting vertex method, centroid method or maximum position method are all commonly used methods for center extraction in the field of optics. The calculation methods are relatively mature and simple, which is conducive to more accurate center extraction and obtaining a more accurate and clear position of the Q' point.

[0140] In this embodiment, obtaining the top centroid position and the bottom centroid position of the feature point in the region of interest according to the multiple detection images includes: segmenting the detection image along a segmentation direction to obtain multiple sub-detection images at different positions along the segmentation direction, where the segmentation direction is perpendicular to the scanning direction;

[0141] The detection image is divided into a plurality of sub-detection images along a scanning direction perpendicular to the detection scan, and each sub-detection image corresponds to position information along the scanning direction perpendicular to the detection scan.

[0142] In this embodiment, the centroid position of the light spot of each sub-detection image is obtained to obtain centroid one-dimensional point cloud data; the grayscale sum of each sub-detection image is obtained to obtain grayscale one-dimensional point cloud data; multiple centroid one-dimensional point cloud data are spliced ​​to obtain a centroid position point cloud map; and multiple grayscale one-dimensional point cloud data are spliced ​​to obtain a grayscale point cloud map.

[0143] The centroid one-dimensional point cloud data represents the corresponding position relationship between the centroid position of the light spot in the region of interest and multiple sub-detection images, and the grayscale one-dimensional point cloud data represents the corresponding position relationship between the grayscale sum value in the region of interest and multiple sub-detection images.

[0144] The centroid position point cloud is the correspondence between different positions in the detector target surface area of ​​interest and the centroid position, and the grayscale and value point cloud is the correspondence between different positions in the detector target surface area of ​​interest and the grayscale and value.

[0145] The centroid position point cloud map and the grayscale and value point cloud map are used as reference cloud maps for calculating the top centroid position and the bottom centroid position, and are uploaded to the server for subsequent calculations.

[0146] Correspondingly, in this embodiment, the top centroid position and the bottom centroid position are obtained according to the centroid position point cloud image and the grayscale point cloud image.

[0147] In this embodiment, when the incident light spot is used to detect and scan the object to be detected, the first detector 820 and the second detector 830 are used to alternately image the object to be detected and scanned, and a detection image corresponding to the first detector 820 and a detection image corresponding to the second detector 830 are respectively obtained.

[0148] In this embodiment, in acquiring the spot centroid position of each sub-detection image, the spot centroid position corresponding to the second detector 830 is the sum of the spot centroid position corresponding to the first detector 820 and the second calibration parameter.

[0149] The second correction parameter cannot be adjusted by a fixed correction step size, so that the starting position of the area of ​​interest of the detector 810 that is closer to the origin when calculating the position deviation is taken as the first detector 820, and the centroid position obtained by the second detector 830 can be obtained by calculation compensation, that is, the sum of the centroid position of the light spot corresponding to the first detector 820 and the second calibration parameter, which is conducive to saving computing power and improving efficiency.

[0150] In this embodiment, in obtaining the grayscale sum value of each sub-detection image, the grayscale sum value corresponding to the second detector 830 is the product of the grayscale sum value corresponding to the first detector 820 and the grayscale calibration value.

[0151] The detector 810 with a lower grayscale sum value is used as the first detector 820, and the grayscale sum value corresponding to the second detector 830 is the product of the grayscale sum value corresponding to the first detector 820 and the grayscale calibration value, which is beneficial to saving computing power and improving efficiency.

[0152] In this embodiment, the centroid one-dimensional point cloud data of multiple sub-detection images are spliced ​​along the scanning direction of the detection scan to obtain a centroid position point cloud map.

[0153] The centroid one-dimensional point cloud data of the multiple sub-detection images are spliced ​​along the scanning direction of the detection scan, so as to obtain a centroid position point cloud map representing the centroid position of the global sampling points of the object to be detected 100.

[0154] Specifically, the centroid one-dimensional point cloud data of the plurality of sub-detection images are spliced ​​alternately along the scanning direction of the detection scan according to the sampling order of the first detector 820 and the second detector 830 .

[0155] The grayscale one-dimensional point cloud data of the multiple sub-detection images are spliced ​​along the scanning direction of the detection scan, so as to obtain a grayscale point cloud image representing the grayscale and value of the global feature points of the object to be detected 100.

[0156] Specifically, the grayscale one-dimensional point cloud data of the plurality of sub-detection images are spliced ​​alternately along the scanning direction of the detection scan according to the sampling order of the first detector 820 and the second detector 830 .

[0157] In this embodiment, obtaining the top centroid position of the feature point according to the centroid position point cloud image and the grayscale point cloud image includes: determining the position of the feature point according to the centroid position point cloud image.

[0158] The centroid position point cloud map represents the centroid position corresponding to the position of each point on the object to be measured 100 . The position of the feature point on the object to be measured 100 can be determined through the distribution of the centroid position in the centroid position point cloud map.

[0159] In this embodiment, in determining the position of the feature point according to the centroid position point cloud image, the position of the feature point is determined by combining the grayscale point cloud image and the centroid position point cloud image.

[0160] The feature points and the reference points have different reflected light intensities after being irradiated by incident light, and there is a more obvious difference in the grayscale point cloud map. Therefore, combining the grayscale point cloud map as an aid in determining the position of the feature points is conducive to more accurate determination of the position of the feature points.

[0161] In this embodiment, points in the same set area around the position of the feature point are obtained in the centroid position point cloud image and the grayscale point cloud image respectively.

[0162] The points in the same set area around the position of the feature point refer to the effective points around the position of the feature point for detecting the feature point, that is, the points of the sampling spots obtained at multiple relative positions of the same feature point during the scanning process.

[0163] In this embodiment, the centroid position point cloud data corresponding to the points within the set area is used as the top measurement point cloud data; the grayscale and value corresponding to the points within the set area is used as the top measurement grayscale and value; based on the top measurement point cloud data and the top measurement grayscale and value, the top centroid position of the feature point is obtained.

[0164] That is, the top centroid position of the feature point is obtained according to the centroid position and grayscale sum value in the same area.

[0165] In this embodiment, the point in the centroid position point cloud image is used as the first point, and the point in the grayscale point cloud image is used as the second point.

[0166] In this embodiment, the top centroid position of the feature point is obtained based on the top measurement point cloud data and the top measurement grayscale and value, including: using the top measurement grayscale and value of each second point in the set area of ​​the grayscale point cloud image as the weight of the top measurement point cloud data of the first point at the corresponding position in the set area of ​​the centroid position point cloud image, performing weighted averaging processing on the top measurement point cloud data, and obtaining the top centroid position.

[0167] The grayscale sum value can characterize the quality of the signal light of the obtained feature point. The larger the grayscale sum value is, the better the quality of the signal light representing the feature point is. In other words, the better the imaging quality of the feature point is, the larger the proportion it occupies in the weighted average processing, so that a more accurate height after weighted processing can be obtained.

[0168] Based on the weight, weighted averaging is performed on the top measurement point cloud data, which is beneficial to comprehensively consider the imaging quality of feature points at different relative positions, improve the accuracy of obtaining the top centroid position of the feature points, and thus help obtain high-precision detection results.

[0169] The top-measured grayscale and value are directly used as the weight corresponding to the top-measured point cloud data. While comprehensively considering the quality of the signal light at different relative positions, the weight is obtained more intuitively and the calculation method is simpler, which is conducive to the implementation of the detection method.

[0170] In other embodiments, the top centroid position of the feature point can also be obtained based on the top measurement point cloud data and the top measurement grayscale and value, including: dividing the top measurement point cloud data into multiple data columns along the scanning direction of the detection scan; using the top measurement grayscale and value of each second point in the set area of ​​the grayscale point cloud image as the weight of the top measurement point cloud data of the first point at the corresponding position in the set area of ​​the centroid position point cloud image, performing weighted averaging processing on the top measurement point cloud data in each data column to obtain multiple top centroid sub-positions; and obtaining the average value of the multiple top centroid sub-positions as the top centroid position.

[0171] For feature points with relatively flat tops, the average value of multiple top centroid sub-positions can be directly obtained as the top centroid position.

[0172] In other embodiments, the top centroid position of the feature point can also be obtained based on the top measurement point cloud data and the top measurement grayscale and value, including: dividing the top measurement point cloud data into multiple data columns along the scanning direction of the detection scan; using the top measurement grayscale and value of each second point in the set area of ​​the grayscale point cloud image as the weight of the top measurement point cloud data of the first point at the corresponding position in the set area of ​​the centroid position point cloud image, performing weighted averaging processing on the top measurement point cloud data in each data column to obtain multiple top centroid sub-positions; performing fitting processing on the multiple top centroid sub-positions to obtain the contour curve corresponding to the feature point, and the contour curve corresponds to the multiple top centroid positions of the feature point.

[0173] For feature points with large surface undulations, there is no exact position to characterize the height of the feature points. Fitting processing is used to obtain the contour curve of the top centroid position, thereby obtaining the distribution of the top centroid position of the feature point surface. Subsequently, the height distribution of the feature point surface is obtained accordingly, and then according to actual needs, the height points that meet the needs are adopted from the height distribution.

[0174] In this embodiment, obtaining the bottom centroid position of the feature point according to the centroid position point cloud image and the grayscale point cloud image includes: determining the position of the reference point at the bottom of the feature point according to the grayscale point cloud image.

[0175] In this embodiment, in the centroid position point cloud map, the centroid position point cloud data of the reference point position is taken as the bottom measurement point cloud data; and the average value of the bottom measurement point cloud data is taken as the bottom centroid position.

[0176] Usually, the surface of the object to be measured 100 is relatively flat, and the grayscale and value corresponding differences of each reference point are not large, so the average value of the bottom measurement point cloud data can be directly taken as the bottom centroid position.

[0177] In this embodiment, the measured height of the feature point is obtained according to the image position difference between the top centroid position and the bottom centroid position.

[0178] The measured height of the feature point is obtained according to the image position difference between the top centroid position and the bottom centroid position, and the height difference between the feature point and the surface of the object to be measured 100 can be obtained. The actual height of the feature point is obtained accordingly, which is beneficial to reduce the detection error caused by the unevenness of the object to be measured 100 itself, thereby facilitating more accurate acquisition of the measured height of the feature point.

[0179] In this embodiment, the measured height of the feature point is obtained based on the image position difference between the top center of mass position and the bottom center of mass position, including: obtaining the pixel value corresponding to the image position difference between the top center of mass position and the bottom center of mass position; and taking the product of the pixel value and the actual height value corresponding to the unit pixel as the measured height of the feature point.

[0180] By taking the product of the pixel value and the height value corresponding to the unit pixel as the measured height of the feature point, the pixel difference in the detection image can be converted into a height value in three-dimensional measurement.

[0181] In this embodiment, after the detector 810 is used to perform multiple imaging of the object to be tested 100 and multiple detection images are obtained, before the top centroid position and the bottom centroid position of the feature point in the region of interest are obtained based on the multiple detection images, it also includes: denoising the detection images.

[0182] Denoising the detected image is beneficial to obtaining a detection image with higher accuracy and reducing the interference of image noise, which is beneficial to accurately obtaining the height information corresponding to the feature points.

[0183] In this embodiment, the denoising process is performed on the detected image, and further includes: performing median filtering on the image information to remove salt and pepper noise.

[0184] The median filter has a good filtering effect on salt and pepper noise (i.e., impulse noise), and while filtering the noise, it can protect the edge of the signal so that it is not blurred. In addition, the median filter algorithm is relatively simple and easy to implement with hardware.

[0185] In this embodiment, after the detector 810 is used to perform multiple imaging of the object to be tested 100 and multiple detection images are obtained, before the top centroid position and the bottom centroid position of the feature point in the region of interest are obtained based on the multiple detection images, it also includes: performing threshold segmentation processing on the detection image, and setting the grayscale value of the point in the detection image whose grayscale value is lower than the preset grayscale value to zero.

[0186] The sampling spots of the sampling points of each detection image are different, so the benchmarks for threshold segmentation are different, so it is necessary to set a grayscale threshold for each detection image. Grayscale threshold segmentation is helpful to more accurately filter out the sampling spots of stray light on the surface of the object to be tested 100, and reduce the interference of stray light on the imaging of feature points.

[0187] In this embodiment, before obtaining the top centroid position and the bottom centroid position according to the centroid position point cloud map and the grayscale sum value point cloud map, it also includes: determining the position of the surface of the object to be tested 100 according to the centroid position point cloud map; obtaining the grayscale value of the position of the surface of the object to be tested 100 in the detection image; when the grayscale value of the position of the surface of the object to be tested 100 in the detection image is greater than or equal to the grayscale threshold, obtaining the detection image.

[0188] When the grayscale value of the position of the surface of the object to be tested 100 in the detection image is greater than or equal to the grayscale threshold, it indicates that the surface reflection of the object to be tested 100 is good and is suitable as a reference for measuring the height of the feature point.

[0189] In this embodiment, when the grayscale value of the position of the surface of the object to be tested 100 in the detection image is less than the grayscale threshold, the grayscale values ​​of all surfaces of the object to be tested 100 in the detection image are adjusted to be greater than or equal to the preset grayscale value; the detection scan of the object to be tested 100 is returned to be executed until the grayscale value of the position of the surface of the object to be tested 100 in the detection image is greater than or equal to the grayscale threshold.

[0190] When the grayscale value of the position of the surface of the object to be tested 100 in the detection image is less than the grayscale threshold, it indicates that the surface reflection of the object to be tested 100 is poor, and the reflection difference of the incident light at different reference points is large, and the grayscale value needs to be adjusted.

[0191] Specifically, in this embodiment, the grayscale values ​​of all surfaces of the object 100 under test 100 in the detection image are adjusted to be greater than or equal to a preset grayscale value, and the adjustment includes: increasing the brightness of the incident light and / or increasing the exposure time of the detector.

[0192] By adjusting the grayscale values ​​of all reference points on the object to be measured to be greater than or equal to the preset grayscale value, the reference points can be more accurately selected according to the grayscale value, which is conducive to more accurately obtaining the measurement height of the feature points.

[0193] In the present embodiment, after obtaining the measured height of the feature point along the direction perpendicular to the surface of the object to be measured according to the position of the imaging spot of the area of ​​interest, the detection method further includes: obtaining the difference between the measured height and the estimated height of the feature point, and judging whether the difference is greater than a preset threshold value; if the difference is greater than the preset threshold value, performing a surface film thickness detection on the reference area of ​​the surface of the object to be measured 100, obtaining the surface film thickness of the object to be measured 100 in the reference area, and correcting the measured height according to the film thickness.

[0194] By comparing the measured height with the estimated height, it is possible to determine whether the results of the optical detection are accurate.

[0195] Specifically, in this embodiment, when the difference is less than or equal to the preset threshold, it indicates that the result of the optical detection is accurate.

[0196] In this embodiment, when the difference is greater than a preset threshold, the surface film thickness of the object to be tested 100 is detected in the reference area of ​​the surface of the object to be tested, the surface film thickness of the object to be tested 100 in the reference area is obtained, and the actual detection height obtained by the actual detection is compensated according to the film thickness, so as to obtain a more accurate detection height in the actual detection process.

[0197] In this embodiment, a thickness measuring instrument is used to obtain the thickness of the film layer on the surface of the object to be measured 100 in the reference area.

[0198] It should be noted that due to the presence of glue layers of different thicknesses on the surface of some wafer products, there will be measurement deviations in the height measurement of the wafer surface at the bottom of the feature point (that is, the surface of the object to be measured), resulting in the problem that the difference between the measured height and the estimated height is greater than the preset threshold. At this time, it is necessary to correct the measured height according to the thickness of the film layer on the surface of the object to be measured 100.

[0199] Accordingly, this embodiment also provides a detection system. Figure 6 It is a functional block diagram of an embodiment of the detection system of the present invention.

[0200] The detection system 50 includes: an area of ​​interest acquisition module 501, which is used to acquire the area of ​​interest of the detector target surface according to the estimated height of the feature point of the object to be tested; an imaging module 502, which is used to use the detector to image the object to be tested and obtain the position of the imaging spot of the feature point in the area of ​​interest of the detector target surface; a measurement height acquisition module 503, which is used to obtain the measurement height of the feature point along the direction perpendicular to the surface of the object to be tested according to the position of the imaging spot of the area of ​​interest.

[0201] In this embodiment, the optical detection system is suitable for performing detection scanning on the object to be detected using an incident light spot, and the detection scanning uses a detector to image the object to be detected.

[0202] Specifically, in this embodiment, incident light is reflected on the surface of the object to be measured to form signal light, forming a triangular optical path, so that the height of the feature point is detected using the triangulation method.

[0203] In other embodiments, a dispersion spectrometer may be used to detect the height, or a confocal microscope may be used to detect the height.

[0204] Combined with reference Figure 2 and Figure 3 , the characteristic point is the convex point to be measured, and the detection method of this embodiment is used to measure the microscopic three-dimensional morphology of the height of the convex point to be measured.

[0205] In this embodiment, the optical detection system is suitable for forming an incident light spot on the surface of the object to be measured having sampling points through incident light, and collecting signal light from the sampling points through detectors to obtain the measured height of the feature points according to the signal light, and the sampling points include the feature points.

[0206] As an example, the object to be tested with sampling points is a wafer, and the optical detection of this embodiment is used to detect three-dimensional defects of coplanarity of convex points on the wafer surface. In other embodiments, the object to be tested can also be a mobile phone case, a chip, a glass surface, etc.

[0207] In this embodiment, the sampling points also include reference points on the surface of the object to be measured.

[0208] This embodiment can obtain the height difference between the feature point and the reference point by optically detecting the sampling point, thereby obtaining the actual measured height of the feature point.

[0209] The region of interest acquisition module 501 is used to acquire the region of interest of the detector target surface according to the estimated height of the feature point of the object to be detected.

[0210] The region of interest (ROI) is obtained, and the subsequent detection of sampling points is performed by analyzing the ROI to reduce the workload and improve efficiency.

[0211] In this embodiment, the detector includes a first detector and a second detector for alternately performing detection scanning.

[0212] In this embodiment, the two detectors work alternately to collect the incident light spot and the imaging information of the incident light spot respectively until the linear scan of the object to be detected is completed, which is beneficial to improving the detection efficiency.

[0213] In other embodiments, the detector may also include only one detector.

[0214] Correspondingly, in this embodiment, acquiring the region of interest on the detector target surface according to the estimated height of the feature point of the object to be measured includes: acquiring the region of interest on the first detector target surface and the second detector target surface respectively.

[0215] The regions of interest on the first detector target surface and the second detector target surface are acquired respectively, and then the information acquired from the regions of interest of the first detector and the second detector are spliced ​​according to the scanning sequence to obtain the global information of the object to be detected.

[0216] In this embodiment, obtaining the region of interest of the detector target surface 80 according to the estimated height of the feature point of the object to be measured includes: determining the size of the region of interest along the first direction of the detector target surface 80 according to the estimated height of the feature point.

[0217] A height direction is preset on the detector target surface, namely, the first direction. In this embodiment, the first direction is the column direction of the detector target surface.

[0218] Specifically, in this embodiment, the size in the first direction of the region of interest on the detector target surface is obtained according to the estimated height of the feature point of the object to be detected, and is the size in the scanning direction of the detection scan.

[0219] In this embodiment, the size of the region of interest along the first direction of the detector target surface is determined based on the estimated height of the feature point, including: obtaining the corresponding height value within the height range of the feature point, and the mapping relationship between the size of the region of interest along the first direction, the mapping relationship including: the larger the corresponding height value within the height range of the feature point, the larger the size of the region of interest along the first direction.

[0220] That is to say, the mapping relationship between the height interval of the feature point and the size of the region of interest along the scanning direction of the detection scan is obtained. The larger the corresponding height value in the height interval of the feature point, the larger the size of the region of interest along the scanning direction of the detection scan.

[0221] This embodiment is for detecting the height of feature points. The larger the height of the feature points is, the larger the distance between the feature points and the reference point light spots on the detector target surface 80 is, and the corresponding region of interest needs to be larger in the scanning direction of the detection scan. At the same time, the height of the feature points is divided into height intervals of the feature points to reduce the amount of change in the region of interest for different feature point heights, thereby simplifying the method of setting the region of interest.

[0222] In this embodiment, the height interval in which the estimated height of the feature point is located is obtained.

[0223] The height interval is obtained, which is used as a reference for obtaining the size of the region of interest in the first direction.

[0224] Correspondingly, in this embodiment, the size of the region of interest along the first direction of the detector target surface is obtained according to the height interval where the estimated height of the feature point is located and the mapping relationship.

[0225] In this embodiment, before obtaining the area of ​​interest of the detector target surface 80 according to the estimated height of the feature point of the object to be measured, it also includes: obtaining the position deviation of the sampling spot formed by the first detector and the second detector collecting signal light from the same area on the object to be measured; obtaining a position correction parameter according to the position deviation, the position correction parameter is an integer multiple of a single correction step, and the integer multiple is set to: suitable for reducing the absolute value of the difference between the position correction parameter and the position deviation.

[0226] The position deviation of the sampling spot formed by the signal light collected by the first detector and the second detector in the same area on the object to be tested is, that is, the position deviation of the same position point on the target surface 80 of the first detector and the second detector relative to the target surface 80. In the actual detection process, the calibration of the detector usually has a fixed calibration step and is difficult to adjust at will. As an example, the position deviation of the first detector and the second detector is dC, and the position correction parameter obtained according to dC is dC1=n*k, where n is an integer and k is a single calibration step.

[0227] Specifically, in this embodiment, the integer multiple is set to: make the absolute value of the difference between the position correction parameter and the position deviation reach the minimum value, which is conducive to making the image information of the corrected first detector and the second detector closest, and at the same time is conducive to the subsequently obtained second correction parameter being as small as possible, so that less calculation compensation is performed in the subsequent calculation process, reducing calculation errors.

[0228] In this embodiment, the aforementioned position correction parameter is used as the first correction parameter, and a second correction parameter is obtained according to the position deviation, and the second correction parameter is the difference between the position deviation and the first correction parameter.

[0229] In the actual detection process, the calibration of the detector usually has a fixed calibration step. Therefore, it is usually difficult to calibrate exactly according to the fixed calibration step. Moreover, the calibration step of the detector is usually an integer. Therefore, it is also difficult to calibrate a decimal position deviation according to the calibration step. Therefore, it is necessary to obtain a second calibration parameter that cannot be adjusted by a fixed calibration step for subsequent calculation compensation in the calculation process. As an example, the second calibration parameter is dC2=dC-dC1.

[0230] For example, the position deviation dC between the first detector and the second detector is 14 pixels, and the single correction step length k is 4 pixels, then n is taken as 3, and the second correction parameter dC2=dC-dC1=2 is obtained.

[0231] For another example, the position deviation dC between the first detector and the second detector is 14.3 pixels, and the single correction step length k is 4 pixels, then n is taken as 3, and the second correction parameter dC2=dC-dC1=2.3 is obtained.

[0232] In this embodiment, the grayscale deviation of the sampling spot formed by the first detector and the second detector collecting the signal light in the same area on the object to be measured is also obtained as a grayscale calibration value for calculation compensation of grayscale value calculation in the subsequent calculation process.

[0233] In this embodiment, the starting positions of the regions of interest on the target surface of the first detector and the target surface of the second detector are respectively obtained, and the difference between the starting positions of the two is used as the position correction parameter.

[0234] The difference between the starting positions of the regions of interest of the first detector and the second detector is obtained as a position correction parameter. That is to say, the starting position of the region of interest of the detector that is closer to the origin when calculating the position deviation is used as a reference, and the starting position of the region of interest of the other detector is set as the reference + dG1, so that the images obtained by the regions of interest of the first detector and the second detector are basically consistent.

[0235] In this embodiment, the position deviation of the sampling spot formed by the signal light collected by the first detector and the second detector in the same area on the object to be tested is obtained, including: for the same area on the object to be tested, a first calibration image is obtained using the target surface of the first detector, and a second calibration image is obtained using the target surface of the second detector.

[0236] The first calibration image and the second calibration image are used to obtain the position deviation of the same point on the object to be measured on the two detectors.

[0237] In this embodiment, the image center positions of the first calibration image and the second calibration image are calculated respectively.

[0238] Usually, the first calibration image and the second calibration image are obtained as sampling spots, so calculating the center position of the image is to calculate the position of the same point on the object to be measured. Using the center position of the image as the calibration reference is conducive to simplifying the method of selecting the position of the same point on the object to be measured, making it easy to obtain the position deviation of the position of the same point.

[0239] Accordingly, in this embodiment, the position deviation of the first detector and the second detector is obtained by comparing the center positions of the light spots of the first calibration image and the second calibration image.

[0240] In this embodiment, before obtaining the region of interest of the detector target surface 80 according to the estimated height of the feature point of the object to be detected, the detection method further includes: obtaining a scanning step length of the detection scan.

[0241] It should be noted that the scanning step length should not be too large. If the scanning step length is too large, a gap is likely to be generated between two adjacent incident light spots in the subsequent detection scan, resulting in an incomplete scan of the surface of the object to be tested, and thus making it difficult to perform a complete detection of the object to be tested, affecting the detection results. To this end, in this embodiment, the scanning step length is less than or equal to the size of the incident light spot along the scanning direction, so as to ensure that the two adjacent incident light spots are exactly spliced ​​or have overlapping parts.

[0242] In this embodiment, obtaining the scanning step length of the detection scan includes: obtaining a mapping relationship between the diameter interval of the feature point and the scanning step length, and the larger the diameter value corresponding to the diameter interval of the feature point is, the larger the scanning step length is.

[0243] In order to efficiently scan the object to be measured, the scanning step length is increased accordingly when the diameter of the feature point is larger, which is beneficial to ensure that the total number of signal light captures during the scanning process will not be too many. At the same time, the diameter is divided into diameter intervals to reduce the change in the scanning step length for different diameters and simplify the method of setting the scanning step length.

[0244] Specifically, in this embodiment, the scanning step length is obtained according to the estimated diameter of the feature point and the mapping relationship.

[0245] As an example, when the estimated diameter of the feature point is within a diameter interval of less than or equal to 60 μm, a scanning step length of 3 μm is obtained; when the estimated diameter of the feature point is within a diameter interval of greater than 60 μm, a scanning step length of 6 μm is obtained.

[0246] In this embodiment, before acquiring the region of interest on the detector target surface, the method further includes: pre-scanning the object to be measured to obtain an image of the object to be measured.

[0247] The image of the object to be tested is used to adjust the placement of the object to be tested, and is also used as a basis for planning the detection scanning path during the detection scanning process.

[0248] In this embodiment, the placement position of the object to be measured is calibrated according to the image.

[0249] The placement position of the object to be tested is calibrated according to the image, so that the placement position of the object to be tested relative to the detection device is more accurate.

[0250] In this embodiment, a path planning is performed for detecting and scanning the object to be detected based on the image, and the path planning covers all feature points on the surface of the object to be detected.

[0251] The path planning for the inspection and scanning of the object to be inspected is performed according to the image, so that the scanning path of the inspection and scanning is reasonable and relatively accurate.

[0252] The imaging module 502 is used to image the object to be measured using a detector to obtain the position of the imaging spot of the feature point in the area of ​​interest of the detector target surface.

[0253] The position of the imaging spot of the feature point in the region of interest on the detector target surface is obtained, which is used as a reference for the subsequent acquisition of the measurement height of the feature point.

[0254] In this embodiment, imaging the object to be tested by using a detector includes: using an incident light spot to detect and scan the object to be tested, so that the incident light spot and the object to be tested are relatively translated, so as to image the object to be tested multiple times by using the detector to obtain multiple detection images.

[0255] The object to be tested is scanned and the sampling points are placed in different relative positions through continuous relative movement. The relative position is the position of the sampling point relative to the object to be tested.

[0256] In this embodiment, the detection scanning direction is perpendicular to the length direction of the incident light spot.

[0257] In this embodiment, during the scanning process, the detector collects signal light once every scanning step, and the scanning step is less than or equal to the size of the incident light spot along the scanning direction.

[0258] In this embodiment, the length of the incident light spot is relatively large and the width is relatively small. After scanning the area spanned by the length of the incident light spot on the surface of the object to be measured along the scanning direction, this embodiment can perform the next round of scanning of the area spanned by the length of the incident light spot. This is beneficial to ensuring the regularity of each scanning translation and reducing the jumpiness of the scanning, which is beneficial to making the scanning of the surface of the object to be measured simple and smooth.

[0259] In this embodiment, before imaging the object to be measured by using the detector, after obtaining the region of interest on the target surface of the detector, the process further includes: obtaining the focus position of the detector, and determining whether the focus position is qualified.

[0260] In this embodiment, the focus position of the detector is obtained according to the optical axis position of the detector, the area of ​​interest of the detector target surface, and the longitudinal position deviation (Yoffset) of the detector. In the actual detection process, the required focus position is pre-set as the preset position according to actual needs. For example, the top of the feature point is set as the preset position, and then the focus position and the preset position are used to judge whether the focus position meets the requirements, that is, whether it is qualified.

[0261] In this embodiment, when the deviation between the focus position and the preset position is less than or equal to a preset threshold, the focus position is qualified; when the deviation between the focus position and the preset position is greater than the preset threshold, the focus is adjusted according to the deviation between the focus position and the preset position; after the focus adjustment, the process returns to execute detection scanning of the object to be tested using the incident light spot.

[0262] When the deviation between the focus position and the preset position is less than or equal to the preset threshold, it means that the focus position is relatively accurate and meets the requirements, and the focus position is qualified; when the deviation between the focus position and the preset position is greater than the preset threshold, it means that the focus position deviates far from the preset position, and does not meet the requirements, and the focus position needs to be adjusted. After the focus adjustment, return to execute the detection scan of the object to be tested using the incident light spot.

[0263] The measurement height acquisition module 503 is used to obtain the measurement height of the feature point along the direction perpendicular to the surface of the object to be measured according to the position of the imaging light spot of the region of interest.

[0264] This embodiment obtains the region of interest and then uses the imaging spot position of the region of interest to calculate the measured height of the feature point, which is beneficial to saving computing power, improving detection efficiency, and achieving high-stability and high-precision optical detection.

[0265] In this embodiment, the measured height of the feature point along the direction perpendicular to the surface of the object to be measured is obtained according to the position of the imaging spot in the region of interest, including: obtaining the top centroid position and the bottom centroid position of the feature point in the region of interest according to multiple detection images.

[0266] The top centroid position and the bottom centroid position are used to calculate the height of the feature point.

[0267] Specifically, in conjunction with reference Figure 4 In this embodiment, the incident angle α of the incident light is less than 45 degrees. Figure 4 A partial enlarged view of any bump to be tested is shown for ease of explanation. Figure 4 In the figure, two convex points to be tested with different heights overlap, wherein a first convex point a to be tested is represented by a black solid convex point, and a second convex point b to be tested is represented by a dotted outline. For the first convex point a to be tested, when the incident light is irradiated on the first convex point a to be tested, it is reflected by point P to form a signal light (the optical path of the signal light formed by the reflection at point P is represented by a dotted line), and the imaging spot on the target surface 80 is at point P'. For the second convex point b to be tested, when the incident light is irradiated on the second convex point b to be tested, it is reflected by point Q to form a signal light (the optical path of the signal light formed by the reflection at point P is represented by a solid line), and the imaging spot on the target surface 80 is at point Q'.

[0268] In this embodiment, the target surface 80 is perpendicular to the incident direction of the corresponding received signal light, therefore, the conjugate image of the target surface 80 is located on the base surface 80e passing through point P, and the base surface 80e is perpendicular to the main optical path 10b of the signal light, however, the incident angle α of the incident light is less than 45 degrees, and the incident light is mirror reflected, then the incident light and the signal light are not perpendicular, therefore, the base surface 80e and the optical axis 10a of the incident light do not coincide, that is, point Q on the second convex point b to be measured is not on the base surface 80e, so that the imaging spot of the incident light passing through point Q is a diffuse spot, that is, point Q cannot be clearly imaged at point Q', but forms a diffuse spot at point Q', therefore, in order to obtain a clear position of point Q', the diffuse spot also needs to be processed.

[0269] In this embodiment, the center of the diffuse spot is extracted to obtain the center of the diffuse spot, which is the clear position of the Q' point, that is, the centroid position.

[0270] In this embodiment, the method for center extraction includes grayscale centroid method, quadratic curve fitting vertex method, Gaussian curve fitting vertex method, centroid method or maximum value position method.

[0271] Grayscale centroid method, quadratic curve fitting vertex method, Gaussian curve fitting vertex method, centroid method or maximum position method are all commonly used methods for center extraction in the field of optics. The calculation methods are relatively mature and simple, which is conducive to more accurate center extraction and obtaining a more accurate and clear position of the Q' point.

[0272] In this embodiment, obtaining the top centroid position and the bottom centroid position of the feature point in the region of interest according to the multiple detection images includes: segmenting the detection image along a segmentation direction to obtain multiple sub-detection images at different positions along the segmentation direction, where the segmentation direction is perpendicular to the scanning direction;

[0273] The detection image is divided into a plurality of sub-detection images along a scanning direction perpendicular to the detection scan, and each sub-detection image corresponds to position information along the scanning direction perpendicular to the detection scan.

[0274] In this embodiment, the centroid position of the light spot of each sub-detection image is obtained to obtain centroid one-dimensional point cloud data; the grayscale sum of each sub-detection image is obtained to obtain grayscale one-dimensional point cloud data; multiple centroid one-dimensional point cloud data are spliced ​​to obtain a centroid position point cloud map; and multiple grayscale one-dimensional point cloud data are spliced ​​to obtain a grayscale point cloud map.

[0275] The centroid one-dimensional point cloud data represents the corresponding position relationship between the centroid position of the light spot in the region of interest and multiple sub-detection images, and the grayscale one-dimensional point cloud data represents the corresponding position relationship between the grayscale sum value in the region of interest and multiple sub-detection images.

[0276] The centroid position point cloud is the correspondence between different positions in the detector target surface area of ​​interest and the centroid position, and the grayscale and value point cloud is the correspondence between different positions in the detector target surface area of ​​interest and the grayscale and value.

[0277] The centroid position point cloud map and the grayscale and value point cloud map are used as reference cloud maps for calculating the top centroid position and the bottom centroid position, and are uploaded to the server for subsequent calculations.

[0278] Correspondingly, in this embodiment, the top centroid position and the bottom centroid position are obtained according to the centroid position point cloud image and the grayscale point cloud image.

[0279] In this embodiment, when the incident light spot is used to detect and scan the object to be detected, the first detector and the second detector are used to alternately image the object to be detected and scanned, and a detection image corresponding to the first detector and a detection image corresponding to the second detector are respectively obtained.

[0280] In this embodiment, in acquiring the spot centroid position of each sub-detection image, the spot centroid position corresponding to the second detector is the sum of the spot centroid position corresponding to the first detector and the second calibration parameter.

[0281] The second correction parameter cannot be adjusted by a fixed correction step size, so that the starting position of the area of ​​interest of the detector that is closer to the origin when calculating the position deviation is taken as the first detector, and the centroid position obtained by the second detector can be obtained by calculation compensation, that is, the sum of the centroid position of the light spot corresponding to the first detector and the second calibration parameter, which is conducive to saving computing power and improving efficiency.

[0282] In this embodiment, in obtaining the grayscale sum value of each sub-detection image, the grayscale sum value corresponding to the second detector is the product of the grayscale sum value corresponding to the first detector and the grayscale calibration value.

[0283] The detector with the lower grayscale sum value is used as the first detector, and the grayscale sum value corresponding to the second detector is the product of the grayscale sum value corresponding to the first detector and the grayscale calibration value, which is beneficial to saving computing power and improving efficiency.

[0284] In this embodiment, the centroid one-dimensional point cloud data of multiple sub-detection images are spliced ​​along the scanning direction of the detection scan to obtain a centroid position point cloud map.

[0285] The centroid one-dimensional point cloud data of multiple sub-detection images are spliced ​​along the scanning direction of the detection scan, so as to obtain a centroid position point cloud map representing the centroid position of the global sampling points of the object to be detected.

[0286] Specifically, the centroid one-dimensional point cloud data of the plurality of sub-detection images are spliced ​​alternately along the scanning direction of the detection scan according to the sampling order of the first detector and the second detector.

[0287] The grayscale one-dimensional point cloud data of multiple sub-detection images are spliced ​​along the scanning direction of the detection scan, so as to obtain a grayscale point cloud image representing the grayscale and value of the global feature points of the object to be detected.

[0288] Specifically, the grayscale one-dimensional point cloud data of the plurality of sub-detection images are spliced ​​alternately along the scanning direction of the detection scan according to the sampling order of the first detector and the second detector.

[0289] In this embodiment, obtaining the top centroid position of the feature point according to the centroid position point cloud image and the grayscale point cloud image includes: determining the position of the feature point according to the centroid position point cloud image.

[0290] The centroid position point cloud map represents the centroid position corresponding to the position of each point on the object to be measured. The position of the feature point on the object to be measured can be determined by the distribution of the centroid position in the centroid position point cloud map.

[0291] In this embodiment, in determining the position of the feature point according to the centroid position point cloud image, the position of the feature point is determined by combining the grayscale point cloud image and the centroid position point cloud image.

[0292] The feature points and the reference points have different reflected light intensities after being irradiated by incident light, and there is a more obvious difference in the grayscale point cloud map. Therefore, combining the grayscale point cloud map as an aid in determining the position of the feature points is conducive to more accurate determination of the position of the feature points.

[0293] In this embodiment, points in the same set area around the position of the feature point are obtained in the centroid position point cloud image and the grayscale point cloud image respectively.

[0294] The points in the same set area around the position of the feature point refer to the effective points around the position of the feature point for detecting the feature point, that is, the points of the sampling spots obtained at multiple relative positions of the same feature point during the scanning process.

[0295] In this embodiment, the centroid position point cloud data corresponding to the points within the set area is used as the top measurement point cloud data; the grayscale and value corresponding to the points within the set area is used as the top measurement grayscale and value; based on the top measurement point cloud data and the top measurement grayscale and value, the top centroid position of the feature point is obtained.

[0296] That is, the top centroid position of the feature point is obtained according to the centroid position and grayscale sum value in the same area.

[0297] In this embodiment, the point in the centroid position point cloud image is used as the first point, and the point in the grayscale point cloud image is used as the second point.

[0298] In this embodiment, the top centroid position of the feature point is obtained based on the top measurement point cloud data and the top measurement grayscale and value, including: using the top measurement grayscale and value of each second point in the set area of ​​the grayscale point cloud image as the weight of the top measurement point cloud data of the first point at the corresponding position in the set area of ​​the centroid position point cloud image, performing weighted averaging processing on the top measurement point cloud data, and obtaining the top centroid position.

[0299] The grayscale sum value can characterize the quality of the signal light of the obtained feature point. The larger the grayscale sum value is, the better the quality of the signal light representing the feature point is. In other words, the better the imaging quality of the feature point is, the larger the proportion it occupies in the weighted average processing, so that a more accurate height after weighted processing can be obtained.

[0300] Based on the weight, weighted averaging is performed on the top measurement point cloud data, which is beneficial to comprehensively consider the imaging quality of feature points at different relative positions, improve the accuracy of obtaining the top centroid position of the feature points, and thus help obtain high-precision detection results.

[0301] The top-measured grayscale and value are directly used as the weight corresponding to the top-measured point cloud data. While comprehensively considering the quality of the signal light at different relative positions, the weight is obtained more intuitively and the calculation method is simpler, which is conducive to the implementation of the detection method.

[0302] In other embodiments, the top centroid position of the feature point can also be obtained based on the top measurement point cloud data and the top measurement grayscale and value, including: dividing the top measurement point cloud data into multiple data columns along the scanning direction of the detection scan; using the top measurement grayscale and value of each second point in the set area of ​​the grayscale point cloud image as the weight of the top measurement point cloud data of the first point at the corresponding position in the set area of ​​the centroid position point cloud image, performing weighted averaging processing on the top measurement point cloud data in each data column to obtain multiple top centroid sub-positions; and obtaining the average value of the multiple top centroid sub-positions as the top centroid position.

[0303] For feature points with relatively flat tops, the average value of multiple top centroid sub-positions can be directly obtained as the top centroid position.

[0304] In other embodiments, the top centroid position of the feature point can also be obtained based on the top measurement point cloud data and the top measurement grayscale and value, including: dividing the top measurement point cloud data into multiple data columns along the scanning direction of the detection scan; using the top measurement grayscale and value of each second point in the set area of ​​the grayscale point cloud image as the weight of the top measurement point cloud data of the first point at the corresponding position in the set area of ​​the centroid position point cloud image, performing weighted averaging processing on the top measurement point cloud data in each data column to obtain multiple top centroid sub-positions; performing fitting processing on the multiple top centroid sub-positions to obtain the contour curve corresponding to the feature point, and the contour curve corresponds to the multiple top centroid positions of the feature point.

[0305] For feature points with large surface undulations, there is no exact position to characterize the height of the feature points. Fitting processing is used to obtain the contour curve of the top centroid position, thereby obtaining the distribution of the top centroid position of the feature point surface. Subsequently, the height distribution of the feature point surface is obtained accordingly, and then according to actual needs, the height points that meet the needs are adopted from the height distribution.

[0306] In this embodiment, obtaining the bottom centroid position of the feature point according to the centroid position point cloud image and the grayscale point cloud image includes: determining the position of the reference point at the bottom of the feature point according to the grayscale point cloud image.

[0307] In this embodiment, in the centroid position point cloud map, the centroid position point cloud data of the reference point position is taken as the bottom measurement point cloud data; and the average value of the bottom measurement point cloud data is taken as the bottom centroid position.

[0308] Usually, the surface of the object to be measured is relatively flat, and the grayscale and value corresponding differences of each reference point are not large, so the average value of the bottom measurement point cloud data can be directly taken as the bottom centroid position.

[0309] In this embodiment, the measured height of the feature point is obtained according to the image position difference between the top centroid position and the bottom centroid position.

[0310] The measured height of the feature point is obtained according to the image position difference between the top centroid position and the bottom centroid position. The height difference between the feature point and the surface of the object to be measured can be obtained, and the actual height of the feature point can be obtained accordingly, which is conducive to reducing the detection error caused by the unevenness of the object to be measured itself, thereby facilitating more accurate measurement of the feature point.

[0311] In this embodiment, the measured height of the feature point is obtained based on the image position difference between the top center of mass position and the bottom center of mass position, including: obtaining the pixel value corresponding to the image position difference between the top center of mass position and the bottom center of mass position; and taking the product of the pixel value and the actual height value corresponding to the unit pixel as the measured height of the feature point.

[0312] By taking the product of the pixel value and the height value corresponding to the unit pixel as the measured height of the feature point, the pixel difference in the image information can be converted into a height value in three-dimensional measurement.

[0313] In this embodiment, after the detector is used to perform multiple imaging of the object to be tested and multiple detection images are obtained, before the top centroid position and the bottom centroid position of the feature point in the region of interest are obtained based on the multiple detection images, it also includes: denoising the detection images.

[0314] Denoising the detected image is beneficial to obtaining a detection image with higher accuracy and reducing the interference of image noise, which is beneficial to accurately obtaining the height information corresponding to the feature points.

[0315] In this embodiment, the denoising process is performed on the detected image, and further includes: performing median filtering on the image information to remove salt and pepper noise.

[0316] The median filter has a good filtering effect on salt and pepper noise (i.e., impulse noise), and while filtering the noise, it can protect the edge of the signal so that it is not blurred. In addition, the median filter algorithm is relatively simple and easy to implement with hardware.

[0317] In this embodiment, after the detector is used to perform multiple imaging of the object to be tested and multiple detection images are obtained, before the top centroid position and the bottom centroid position of the feature point in the region of interest are obtained based on the multiple detection images, it also includes: performing threshold segmentation processing on the detection image, and setting the grayscale value of the point in the detection image whose grayscale value is lower than the preset grayscale value to zero.

[0318] The sampling spots of the sampling points of each detection image are different, so the benchmarks for threshold segmentation are different, so it is necessary to set a grayscale threshold for each detection image. Grayscale threshold segmentation is helpful to more accurately filter out the sampling spots of stray light on the surface of the object to be tested, and reduce the interference of stray light on the imaging of feature points.

[0319] In this embodiment, before obtaining the top centroid position and the bottom centroid position according to the centroid position point cloud map and the grayscale sum value point cloud map, it also includes: determining the position of the surface of the object to be measured according to the centroid position point cloud map; obtaining the grayscale value of the position of the surface of the object to be measured in the detection image; when the grayscale value of the position of the surface of the object to be measured in the detection image is greater than or equal to the grayscale threshold, obtaining the detection image.

[0320] When the grayscale value of the position of the surface of the object to be measured in the detection image is greater than or equal to the grayscale threshold, it indicates that the reflection condition of the surface of the object to be measured is good and is suitable as a reference for measuring the height of the feature point.

[0321] In this embodiment, when the grayscale value of the position of the surface of the object to be tested in the detection image is less than the grayscale threshold, the grayscale values ​​of all surfaces of the object to be tested in the detection image are adjusted to be greater than or equal to the preset grayscale value; the detection scan of the object to be tested is returned to be executed until the grayscale value of the position of the surface of the object to be tested in the detection image is greater than or equal to the grayscale threshold.

[0322] When the grayscale value of the position of the surface of the object to be tested in the detection image is less than the grayscale threshold, it indicates that the reflection of the surface of the object to be tested is poor, and the reflection difference of the incident light at different reference points is large, and the grayscale value needs to be adjusted.

[0323] Specifically, in this embodiment, the grayscale values ​​of all surfaces of the object to be tested in the detection image are adjusted to be greater than or equal to a preset grayscale value, and the adjustment includes: increasing the brightness of the incident light and / or increasing the exposure time of the detector.

[0324] By adjusting the grayscale values ​​of all reference points on the object to be measured to be greater than or equal to the preset grayscale value, the reference points can be more accurately selected according to the grayscale value, which is conducive to more accurately obtaining the measurement height of the feature points.

[0325] In this embodiment, after obtaining the measured height of the feature point along the direction perpendicular to the surface of the object to be measured according to the position of the imaging spot of the area of ​​interest, the detection method also includes: obtaining the difference between the measured height and the estimated height of the feature point, and judging whether the difference is greater than a preset threshold; if the difference is greater than the preset threshold, performing a surface film thickness detection on a reference area of ​​the surface of the object to be measured, obtaining the surface film thickness of the object to be measured in the reference area, and correcting the measured height according to the film thickness.

[0326] By comparing the measured height with the estimated height, it is possible to determine whether the results of the optical detection are accurate.

[0327] Specifically, in this embodiment, when the difference is less than or equal to the preset threshold, it indicates that the result of the optical detection is accurate.

[0328] In this embodiment, when the difference is greater than a preset threshold, the surface film thickness detection is performed on the reference area of ​​the surface of the object to be tested, the surface film thickness of the object to be tested in the reference area is obtained, and the actual detection height obtained by the actual detection is compensated according to the film thickness, so as to obtain a more accurate detection height in the actual detection process.

[0329] In this embodiment, a thickness measuring instrument is used to obtain the thickness of the film layer on the surface of the object to be measured in the reference area.

[0330] It should be noted that due to the presence of glue layers of different thicknesses on the surface of some wafer products, there will be measurement deviations in the height measurement of the wafer surface at the bottom of the feature point (that is, the surface of the object to be measured), resulting in the problem that the difference between the measured height and the estimated height is greater than the preset threshold. At this time, it is necessary to correct the measured height according to the thickness of the film layer on the surface of the object to be measured.

[0331] The embodiment of the present invention further provides a device, which can implement the detection method provided by the embodiment of the present invention by loading the above detection method in the form of a program. An optional hardware structure of the terminal device provided by the embodiment of the present invention can be as follows Figure 7 As shown, it includes: at least one processor 01, at least one communication interface 02, at least one memory 03 and at least one communication bus 04.

[0332] In this embodiment, the number of processor 01, communication interface 02, memory 03, and communication bus 04 is at least one, and the processor 01, communication interface 02, and memory 03 communicate with each other through the communication bus 04. The communication interface 02 can be an interface of a communication module for network communication, such as an interface of a GSM module. The processor 01 may be a central processing unit CPU, or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement an embodiment of the present invention. The memory 03 may include a high-speed RAM memory, and may also include a non-volatile memory (NVM), such as at least one disk storage. Among them, the memory 03 stores one or more computer instructions, and the one or more computer instructions are executed by the processor 01 to implement the detection method provided in the embodiment of the present invention.

[0333] It should be noted that the above-mentioned terminal device may also include other devices (not shown) that may not be necessary for understanding the contents disclosed in the embodiments of the present invention; given that these other devices may not be necessary for understanding the contents disclosed in the embodiments of the present invention, the embodiments of the present invention will not introduce them one by one.

[0334] An embodiment of the present invention further provides a storage medium, wherein the storage medium stores one or more computer instructions, and the one or more computer instructions are used to implement the detection method provided by the embodiment of the present invention.

[0335] The embodiment of the present invention obtains the region of interest and then uses the imaging spot position of the region of interest to calculate the measured height of the feature point, which is beneficial to saving computing power, improving detection efficiency, and achieving high-stability and high-precision optical detection.

[0336] The above-mentioned embodiments of the present invention are combinations of elements and features of the present invention. Unless otherwise mentioned, the elements or features may be considered as optional. Each element or feature may be put into practice without being combined with other elements or features. In addition, the embodiments of the present invention may be constructed by combining some elements and / or features. The order of operations described in the embodiments of the present invention may be rearranged. Some constructions of any one embodiment may be included in another embodiment, and may be replaced by the corresponding construction of another embodiment. It is obvious to those skilled in the art that claims that do not have a clear reference relationship to each other in the attached claims may be combined into embodiments of the present invention, or may be included as new claims in the amendment after submitting this application.

[0337] Embodiments of the present invention may be implemented by various means such as hardware, firmware, software or a combination thereof. In a hardware configuration, the method according to an exemplary embodiment of the present invention may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, etc. In a firmware or software configuration, embodiments of the present invention may be implemented in the form of modules, processes, functions, etc. The software code may be stored in a memory unit and executed by a processor. The memory unit is located inside or outside the processor and may send data to the processor and receive data from the processor via various known means.

[0338] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0339] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. An optical detection method, characterized in that: Used to detect the height of the feature point of the object to be detected, the detection method includes: Acquire an area of ​​interest on the detector target surface according to the estimated height of the feature point of the object to be measured; Using the detector to image the object to be tested, and obtaining the position of the imaging spot of the feature point in the region of interest of the detector target surface; The measured height of the feature point along a direction perpendicular to the surface of the object to be measured is obtained according to the position of the imaging light spot of the region of interest.

2. The optical detection method according to claim 1, characterized in that: Acquiring a region of interest on the detector target surface according to the estimated height of the feature point of the object to be measured includes: determining a size of the region of interest along a first direction of the detector target surface according to the estimated height of the feature point.

3. The optical detection method according to claim 2, characterized in that: The optical detection method is suitable for performing detection scanning on the object to be detected using an incident light spot, and the detection scanning uses the detector to image the object to be detected; In the region of interest on the detector target surface, the size in the first direction is obtained according to the estimated height of the feature point of the object to be detected, and is the size in the scanning direction of the detection scan.

4. The optical detection method according to claim 2 or 3, characterized in that: Determining the size of the region of interest along a first direction of the detector target surface according to the estimated height of the feature point includes: Acquire a mapping relationship between a height value corresponding to the height interval of the feature point and a size of the region of interest along the first direction of the detector target surface, wherein the mapping relationship includes: the larger the height value corresponding to the height interval of the feature point is, the larger the size of the region of interest along the first direction of the detector target surface is; Obtaining the height interval where the estimated height of the feature point is located; According to the height interval where the estimated height of the feature point is located and the mapping relationship, the size of the region of interest along the first direction of the detector target surface is obtained.

5. The optical detection method according to claim 1, characterized in that: The optical detection method is suitable for performing detection scanning on the object to be detected, and the detector includes a first detector and a second detector for alternately performing the detection scanning; Acquiring the region of interest on the detector target surface according to the estimated height of the feature point of the object to be detected includes: acquiring the regions of interest on the first detector target surface and the second detector target surface respectively.

6. The optical detection method according to claim 5, characterized in that: Before obtaining the region of interest on the detector target surface according to the estimated height of the feature point of the object to be detected, the detection method further includes: obtaining the position deviation of the sampling light spot formed by the first detector and the second detector collecting the signal light of the same region on the object to be detected; obtaining a position correction parameter according to the position deviation, wherein the position correction parameter is an integer multiple of a single correction step length, and the integer multiple is configured to be suitable for reducing the absolute value of the difference between the position correction parameter and the position deviation; The starting positions of the regions of interest on the first detector target surface and the second detector target surface are respectively obtained, and the difference between the starting positions of the two regions of interest is made the position correction parameter.

7. The optical detection method according to claim 6, characterized in that: Obtaining the position deviation of the sampling light spot formed by the first detector and the second detector collecting the signal light of the same area on the object to be tested, including: for the same area on the object to be tested, using the target surface of the first detector to obtain a first calibration image, and using the target surface of the second detector to obtain a second calibration image; Calculate the center positions of the light spots of the first calibration image and the second calibration image respectively; The position deviation of the first detector and the second detector is obtained by comparing the center positions of the light spots of the first calibration image and the second calibration image.

8. The optical detection method according to claim 1, characterized in that: The optical detection method is suitable for performing detection scanning on the object to be detected using an incident light spot, and the detection scanning uses the detector to image the object to be detected; Imaging the object to be tested by using the detector includes: using the incident light spot to detect and scan the object to be tested, so that the incident light spot and the object to be tested are relatively translated, so as to use the detector to image the object to be tested multiple times and obtain multiple detection images; Obtaining the measured height of the feature point along a direction perpendicular to the surface of the object to be measured according to the position of the imaging light spot in the region of interest, including: obtaining the top centroid position and the bottom centroid position of the feature point in the region of interest according to the plurality of detection images; The measured height of the feature point is obtained according to the position difference between the top centroid position and the bottom centroid position.

9. The optical detection method according to claim 8, characterized in that: Acquiring the top centroid position and the bottom centroid position of the feature point in the region of interest according to the plurality of detection images, including: segmenting the detection image along a segmentation direction to acquire a plurality of sub-detection images at different positions along the segmentation direction, wherein the segmentation direction is perpendicular to the scanning direction; Obtain the centroid position of the light spot of each sub-detection image to obtain centroid one-dimensional point cloud data; Obtain the grayscale sum of each sub-detection image to obtain grayscale one-dimensional point cloud data; Splicing a plurality of the centroid one-dimensional point cloud data to obtain a centroid position point cloud map; Splicing a plurality of the grayscale one-dimensional point cloud data to obtain a grayscale point cloud image; The top centroid position and the bottom centroid position are obtained according to the centroid position point cloud image and the grayscale point cloud image.

10. The optical detection method according to claim 8, characterized in that: The measured height of the feature point is obtained according to the image position difference between the top centroid position and the bottom centroid position, including: obtaining the pixel value corresponding to the image position difference between the top centroid position and the bottom centroid position; and taking the product of the pixel value and the actual height value corresponding to the unit pixel as the measured height of the feature point.

11. The optical detection method according to claim 8, characterized in that: The detector is used to perform multiple imaging of the object to be tested, and after obtaining multiple detection images, before obtaining the top centroid position and the bottom centroid position of the feature point in the area of ​​interest based on the multiple detection images, it also includes: performing threshold segmentation processing on the detection image, and setting the grayscale value of the point in the detection image whose grayscale value is lower than the preset grayscale value to zero.

12. The optical detection method according to claim 9, characterized in that: Before obtaining the top centroid position and the bottom centroid position according to the centroid position point cloud map and the grayscale point cloud map, the optical detection method further includes: determining the position of the surface of the object to be detected according to the centroid position point cloud map; Obtaining the grayscale value of the position of the surface of the object to be detected in the detection image; When the grayscale value of the position of the surface of the object to be detected in the detection image is greater than or equal to the grayscale threshold, acquiring the detection image; When the grayscale value of the position of the surface of the object to be tested in the detection image is less than the grayscale threshold, the grayscale values ​​of all the surfaces of the object to be tested in the detection image are adjusted to be greater than or equal to the preset grayscale value; and the detection scan of the object to be tested is returned to be executed until the grayscale value of the position of the surface of the object to be tested in the detection image is greater than or equal to the grayscale threshold.

13. The optical detection method according to claim 12, characterized in that: The grayscale values ​​of all surfaces of the object to be tested in the detection image are adjusted to be greater than or equal to a preset grayscale value, and the adjustment includes: increasing the brightness of the incident light spot and / or increasing the exposure time of the detector.

14. An optical detection system, characterized in that: Used to detect the height of feature points of an object to be measured, the optical detection system comprises: An area of ​​interest acquisition module, used to acquire an area of ​​interest on the detector target surface according to the estimated height of the feature point of the object to be detected; An imaging module, used to image the object to be tested using the detector, and obtain the position of the imaging spot of the feature point in the area of ​​interest of the detector target surface; The measurement height acquisition module is used to obtain the measurement height of the feature point along a direction perpendicular to the surface of the object to be measured according to the position of the imaging spot of the region of interest.

15. A device, characterized in that The method comprises at least one memory and at least one processor, wherein the memory stores one or more computer instructions, wherein the one or more computer instructions are executed by the processor to implement the detection method according to any one of claims 1 to 13.

16. A storage medium, characterized in that: The storage medium stores one or more computer instructions, and the one or more computer instructions are used to implement the detection method according to any one of claims 1-13.

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