Chip multi-layer AOI detection equipment and detection method of chip multi-layer AOI detection equipment

Abstract

The invention discloses a chip multi-layer AOI detection device and a detection method of the chip multi-layer AOI detection device, and relates to the technical field of optical detection device.The chip multi-layer AOI detection device comprises an illumination module, an imaging module, a light splitting module and a plurality of cameras, and the illumination module is used for emitting an illumination light source; the imaging module is in light path connection with the illumination module and is used for receiving light rays from the chip to be detected and forming imaging light; the light splitting module is arranged in an output light path of the imaging module and is used for splitting imaging light output by the imaging module into multiple beams of light; and the plurality of cameras are respectively arranged in an output light path of the light splitting module, and the optical distances between the cameras and the imaging module are different, so that the cameras are used for receiving images of different focal planes at the same time. According to the technical scheme provided by the invention, layered imaging can be carried out on the chip through the same imaging module along the same optical path, so that low-cost and high-efficiency three-dimensional synchronous imaging is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical detection equipment, in particular to a chip multi-layer AOI detection equipment and a detection method of the chip multi-layer AOI detection equipment. BACKGROUND

[0002] In the field of Micro-LED chip detection, automatic optical inspection (AOI) technology has become a key means to improve detection efficiency and accuracy. AOI technology mainly relies on high-resolution imaging systems to capture images of the chip surface and compare them with pre-set standard images or CAD data to identify and classify potential defects. Currently, AOI detection equipment on the market can be broadly divided into two categories: one is ordinary planar AOI detection equipment, which can only detect defects on the surface of the chip; the other is 3D AOI detection, which usually uses multi-view or structured light to obtain 3D images of the chip to achieve overall chip detection.

[0003] Although existing AOI detection technology meets the needs of Micro-LED wafer detection to some extent, there are still some shortcomings. As a three-dimensional structure, the chip not only has the risk of surface defects, but also has defects in the contact area with the substrate, which can have a serious impact on the performance and reliability of the chip. Ordinary AOI detection equipment can only detect a certain focal plane of the chip and cannot simultaneously observe the surface scratches and bottom scratches of the chips on the wafer. 3D AOI equipment can obtain 3D images of the chip, but the system structure is complex and the detection efficiency is low, requiring structured light or complex light source systems for illumination and multi-angle shooting, and using complex algorithms for three-dimensional reconstruction, greatly increasing the detection cost. SUMMARY

[0004] The main purpose of the present application is to provide a chip multi-layer AOI detection equipment and a detection method of the chip multi-layer AOI detection equipment, which can realize low-cost and high-efficiency three-dimensional synchronous imaging by layering imaging of the chip through the same imaging module along the same optical path.

[0005] To achieve the above purpose, the present application provides a chip multi-layer AOI detection equipment, which comprises: An illumination module for emitting an illumination light source; An imaging module connected with the illumination module in optical path, for receiving light from the chip to be detected and forming imaging light; A light splitting module provided in the output light path of the imaging module, for splitting the imaging light output by the imaging module into multiple beams of light; and Multiple cameras are respectively set in the output optical path of the beam splitting module, and each camera is at a different optical distance from the imaging module, so as to simultaneously receive images of different focal planes.

[0006] In one embodiment, the imaging module includes an objective lens, a tube lens, and a first beam splitter arranged in sequence, and the first beam splitter is disposed adjacent to the illumination module; the first beam splitter is disposed adjacent to the beam splitter module; The objective lens is used to collect light reflected or transmitted from the chip under test; the first beam splitter is used to reflect the illumination light from the illumination module to the coaxially arranged objective lens, and to transmit the parallel light carrying the chip under test information returned by the objective lens to the tube mirror and the beam splitter module; the tube mirror is used to pair with the objective lens to receive the parallel light transmitted from the first beam splitter and to converge the parallel light into a clear real image.

[0007] In one embodiment, the number of cameras is three, and the three cameras are respectively defined as a first camera, a second camera, and a third camera; the distance between the first camera and the tube mirror is the standard working distance, the distance between the second camera and the tube mirror is greater than the working distance, and the distance between the third camera and the tube mirror is less than the working distance.

[0008] In one embodiment, the second camera, the third camera, and the first camera are arranged sequentially on the side of the imaging module away from the chip to be detected.

[0009] In one embodiment, the chip multilayer AOI inspection device further includes multiple adjustable fixing sleeves, each of which is connected to a camera for adjusting the distance between the camera and the tube mirror.

[0010] In one embodiment, the beam splitting module includes a plurality of second beam splitting prisms, and the plurality of second beam splitting prisms and a camera are arranged sequentially along the same straight line on the side of the first beam splitting prism away from the tube mirror, forming a first optical path; the side of each second beam splitting prism forms a second optical path with a camera, for splitting the imaging light to the plurality of cameras according to a preset ratio.

[0011] In one embodiment, the illumination module includes an illumination source, a condenser lens, and a lens arranged in sequence, and the lens is connected to the optical path of the imaging module.

[0012] In one embodiment, the illumination module further includes an aperture stop, which is disposed between the illumination source and the condenser lens, and is used to adjust the angle range of the light illuminating the chip under test by the illumination source.

[0013] In one embodiment, the illumination module further includes a field stop, which is disposed between the condenser lens and the lens, and is used to adjust the size of the field stop.

[0014] This invention also proposes a detection method for a multi-layer AOI inspection device for chips. The multi-layer AOI inspection device for chips adopts the multi-layer AOI inspection device described above. The steps of the detection method for the multi-layer AOI inspection device for chips include: The control lighting module emits illumination light to the chip under test; The same set of objective lenses, tube lenses, and first beam splitter of the imaging module are used to collect light reflected or transmitted through different layers of the chip under test to form imaging light. The beam splitting module splits the imaging light into multiple imaging sub-paths; Multiple cameras arranged along the multi-beam imaging sub-optical path simultaneously receive the imaging light, wherein the optical working distance of each camera relative to the tube mirror is set differently, so that each camera synchronously captures images of different focal planes of the chip under test; and Based on the images of different focal planes captured synchronously by each of the cameras, the defect distribution of the chip under test in three-dimensional space is analyzed.

[0015] The chip multilayer AOI inspection device of this invention includes an illumination module, an imaging module, a beam splitting module, and multiple cameras. The illumination module emits an illumination source. The imaging module is optically connected to the illumination module to form imaging light. The beam splitting module splits the imaging light into multiple beams. Multiple cameras are respectively positioned in the output optical path of the beam splitting module, with each camera having a different optical distance from the imaging module. Thus, multilayer images of the chip can be simultaneously acquired through a single exposure along the same optical path using the same imaging module, eliminating the time delay caused by mechanical movement. It eliminates the need for complex light source systems and 3D reconstruction algorithms, directly acquiring image data of each focal plane through optical beam splitting, thereby achieving low-cost, high-efficiency synchronous 3D imaging. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the chip multilayer AOI inspection device provided by the present invention; Figure 2The chip multilayer AOI inspection equipment provided by this invention is used to inspect two defective chips. Figure 3 This is a schematic diagram showing two chips to be inspected focused on the upper surface of the chip multilayer AOI inspection device provided by the present invention; Figure 4 A schematic diagram showing two chips to be inspected by the chip multilayer AOI inspection equipment provided by the present invention, with the central light-emitting layer focused; Figure 5 This is a schematic diagram showing two chips to be inspected in the multilayer AOI inspection equipment provided by the present invention focused on the bottom substrate; Figure 6 This is a schematic diagram showing the three-dimensional state formed by the combination of the upper surface, middle light-emitting layer and bottom substrate of the two chips to be inspected by the chip multilayer AOI inspection equipment provided by the present invention. Figure 7 This is a schematic diagram of the steps of the detection method of the chip multilayer AOI detection device provided by the present invention.

[0018] Explanation of icon numbers: 10. Illumination module; 11. Illumination source; 12. Condenser lens; 13. Lens; 14. Aperture stop; 15. Field stop; 20. Imaging module; 21. Objective lens; 22. Tube lens; 23. First beam splitter; 40. Camera; 40a. First camera; 40b. Second camera; 40c. Third camera; 50. Adjustable fixing sleeve; 60. Second beam splitter; 1. Chip to be tested.

[0019] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0022] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0023] In existing technologies, automated optical inspection is commonly used in the field of Micro-LED chip inspection to identify surface defects. However, defects in the multi-layered structure within the chip are difficult to detect effectively using a single focal plane imaging method. Traditional equipment relies on structured light or multi-angle imaging to acquire three-dimensional information, resulting in high system complexity and low inspection efficiency. For example, in wafer inspection scenarios, surface scratches and bottom scratches on the chip need to be inspected separately, making it impossible to simultaneously capture multi-layered defect information, thus extending the inspection cycle and increasing costs.

[0024] To address the aforementioned issues, existing multi-focal-plane synchronous imaging methods typically require adjusting objective lens positions or introducing complex optical components, leading to reduced system stability and increased costs. Analysis reveals that beam splitting of multi-focal-plane images within the same optical path can avoid the time losses associated with mechanical adjustments. Further research shows that by using a beam-splitting module to proportionally distribute the imaging light to cameras at different optical distances, image information from multiple focal planes can be acquired simultaneously, thereby eliminating the reliance on 3D reconstruction algorithms.

[0025] Therefore, please refer to Figure 1 This application proposes a chip multilayer AOI inspection device including an illumination module 10, an imaging module 20, a beam splitting module, and multiple cameras 40. The illumination module 10 is used to emit an illumination source 11. The imaging module 20 is optically connected to the illumination module 10 to form imaging light. The beam splitting module splits the imaging light into multiple beams. The multiple cameras 40 are respectively arranged in the output optical path of the beam splitting module, and the optical distance between each camera 40 and the imaging module 20 is different.

[0026] The beam splitting module consists of a second beam splitting prism 60, which can be a coated prism to split the incident light into multiple sub-beams according to a preset ratio. Multiple cameras 40 are arranged along the optical axis, and the mounting position of each camera 40 forms a different working distance with the imaging module 20.

[0027] Specifically, the light emitted by the illumination module 10 illuminates the surface of the chip 1 under test. The light reflected or transmitted from the chip 1 is then collected by the imaging module 20 to form a parallel beam. This beam is focused by the imaging module 20 to form a real image. The beam is then divided into multiple sub-beam paths by the beam splitting module. Each sub-beam path enters a camera 40 at a different optical distance. Due to the difference in depth of focus, each camera 40 simultaneously captures clear images of the chip surface, intermediate layer, and bottom layer.

[0028] Compared to existing technologies, traditional equipment requires multiple adjustments to the objective lens 21 position or the use of multiple lens sets to achieve layered detection. This solution acquires multiple layers of images simultaneously in a single exposure, eliminating the time delay caused by mechanical movement. Compared to 3D detection equipment using structured light, this solution eliminates the need for complex light source systems and 3D reconstruction algorithms. It directly acquires image data of each focal plane through optical beam splitting, significantly reducing system complexity and data processing volume.

[0029] Through the above technical solution, this application achieves simultaneous detection of multi-layer defects in chips, effectively identifying surface scratches, internal cracks, and substrate contact defects. Since multiple focal plane images are acquired through beam splitting on the same optical path, image registration errors caused by multi-angle shooting are avoided, improving detection accuracy. Furthermore, the combination of the beam splitting module and the fixed camera 40 simplifies the optical system, reducing equipment manufacturing costs and maintenance difficulty.

[0030] Please see Figure 1 This application further proposes an imaging module 20 comprising an objective lens 21, a tube lens 22, and a first beam splitter 23 arranged sequentially, wherein the first beam splitter 23 is disposed adjacent to the illumination module 10; the first beam splitter 23 is disposed adjacent to the beam splitter module; the objective lens 21 is used to collect light reflected or transmitted from the chip 1 to be tested; the first beam splitter 23 is used to reflect the illumination light from the illumination module 10 to the coaxially disposed objective lens 21, and to transmit the parallel light returned by the objective lens 21 carrying the information of the chip 1 to the tube lens 22 and the beam splitter module; the tube lens 22 is used to pair with the objective lens 21 to receive the parallel light transmitted from the first beam splitter 23 and to converge the parallel light into a clear real image.

[0031] In this embodiment, objective lens 21 refers to an optical element used to collect light reflected or transmitted from the chip 1 under test. Specifically, it can be implemented using a high numerical aperture microscope objective lens 21, and its function is to convert the light from the chip into parallel light. Tube lens 22 refers to an optical element used in conjunction with objective lens 21. Specifically, it can be implemented using a convex lens with a focal length matching objective lens 21, and its function is to converge the parallel light transmitted by objective lens 21 into a real image. First beam splitter prism 23 refers to an optical prism with beam splitting function. Specifically, it can be implemented using a cubic prism coated with a beam splitting film, and its function is to reflect the illumination light from illumination module 10 to objective lens 21, while allowing the imaging light from objective lens 21 to be transmitted to tube lens 22 and beam splitter module.

[0032] Specifically, objective lens 21 collects light reflected or transmitted from the chip 1 under test to form parallel light. First beam splitter 23 reflects illumination light from illumination module 10 back to objective lens 21, while simultaneously allowing parallel light carrying chip information to be transmitted to tube lens 22. Tube lens 22 and objective lens 21 form an optical pairing relationship, converging the parallel light into a real image. First beam splitter 23 is positioned between objective lens 21 and tube lens 22, adjacent to the beam splitting module, allowing imaging light to be transmitted to subsequent beam splitting modules. Through the synergistic effect of objective lens 21, tube lens 22, and first beam splitter 23, the separation of illumination light reflection and imaging light transmission is achieved in the same optical path, ensuring that imaging module 20 only requires a single set of optical components to complete multi-layer optical path processing.

[0033] Compared with existing technologies, traditional AOI equipment requires multiple independent imaging systems or complex optical path switching devices to achieve multi-layer detection. However, this solution integrates the objective lens 21, the tube lens 22 and the first beam splitter 23, enabling a single imaging module 20 to simultaneously complete optical path separation and real image generation, avoiding redundancy of multiple components and simplifying the optical path structure.

[0034] Through the above technical solution, this application achieves simultaneous processing of multi-layer optical path information during a single imaging process, solving the problem of low efficiency caused by optical path switching in traditional equipment, while reducing system complexity and manufacturing costs. The paired design of objective lens 21 and tube lens 22 ensures imaging quality, while the beam-splitting function of the first beam-splitting prism 23 ensures that the illumination and imaging optical paths do not interfere with each other, providing a foundation for subsequent multi-layer synchronous detection of the beam-splitting module.

[0035] Please see Figure 1 This application further proposes that the chip multilayer AOI inspection device has three cameras 40, which are defined as the first camera 40a, the second camera 40b and the third camera 40c respectively; the distance between the first camera 40a and the tube mirror 22 is the standard working distance, the distance between the second camera 40b and the tube mirror 22 is greater than the working distance, and the distance between the third camera 40c and the tube mirror 22 is less than the working distance.

[0036] In this embodiment, the standard working distance refers to the distance from the clear real image plane formed by the imaging system composed of objective lens 21 and tube lens 22 under optimal focusing conditions to tube lens 22. Specifically, it can be determined by simulation using optical design software or experimental calibration. Its function is to ensure that the first camera 40a can capture a clear image of a specific focal plane of the chip 1 under test. "Greater than the working distance" means that the optical distance of the second camera 40b relative to tube lens 22 is longer than the standard working distance. This can be achieved by adjusting the position of the second camera 40b or adding optical elements in the optical path. Its function is to expand the depth of field of the imaging system, enabling the second camera 40b to capture images of focal planes located at deeper layers in the chip 1 under test. "Less than the working distance" means that the optical distance of the third camera 40c relative to tube lens 22 is shorter than the standard working distance. This can be achieved by shortening the installation position of the third camera 40c or reducing the number of optical elements in the optical path. Its function is to enable the third camera 40c to capture images of focal planes located at the surface of the chip 1 under test.

[0037] Specifically, the beam splitting module divides the imaging light from the imaging module 20 into three paths, which enter the first camera 40a, the second camera 40b, and the third camera 40c, respectively. Since the three cameras 40 are at different optical distances from the tube lens 22, the focal point of each imaging light path corresponds to a different depth of the chip 1 under test when it reaches its corresponding camera 40. For example, the first camera 40a receives the focal plane image corresponding to the standard working distance, the second camera 40b receives the focal plane image of a deeper layer, and the third camera 40c receives the focal plane image of a more superficial layer. Thus, the three cameras 40 can simultaneously acquire image information from different depths of the chip, achieving multi-layer imaging without mechanical focusing or multiple shots.

[0038] Compared to existing technologies, traditional AOI inspection equipment can only acquire images of a single focal plane in a single shot. If multi-layer structures need to be inspected, the relative position of the objective lens 21 and the chip must be repeatedly adjusted, resulting in low inspection efficiency. In contrast, this solution achieves simultaneous capture of multi-focal-plane images through a combination of a beam splitting module and multiple fixed-space cameras 40, avoiding the time loss caused by mechanical focusing, and eliminating the need to rely on complex structured light or 3D reconstruction algorithms.

[0039] Please see Figure 1 This application further proposes that the second camera 40b, the third camera 40c and the first camera 40a are arranged in sequence on the side of the imaging module 20 away from the chip 1 to be detected.

[0040] In this embodiment, the imaging module 20 includes three cameras 40: a first camera 40a, a second camera 40b, and a third camera 40c. The distance between the first camera 40a and the tube mirror 22 is the standard working distance, corresponding to the standard focal plane of the sample; the distance between the second camera 40b and the tube mirror 22 is greater than the standard working distance, corresponding to the far focal plane (i.e., a deeper focal plane) of the sample; the distance between the third camera 40c and the tube mirror 22 is less than the standard working distance, corresponding to the near focal plane (i.e., a shallower focal plane) of the sample. The three cameras 40 are arranged sequentially along the optical axis on the side of the imaging module 20 away from the chip 1 to be detected, specifically in the following order: second camera 40b (far focal plane), third camera 40c (near focal plane), and first camera 40a (standard focal plane).

[0041] Specifically, in the optical path design, the imaging beam from the tube lens 22 first encounters the beam splitting module. The beam splitting sequence is arranged as follows: First, the beam is split to the second camera 40b (far focal plane): the imaging beam is reflected by the first second beam splitter 60 and directly guided to the second camera 40b. This optical path involves only one reflection, has the shortest optical path, and involves the fewest optical components. Second, the beam is split to the third camera 40c (near focal plane): the beam transmitted through the first second beam splitter 60 is reflected by the second second beam splitter 60 and guided to the third camera 40c. This optical path involves one transmission and one reflection, with a moderate optical path and number of optical components. Finally, the beam is split to the first camera 40a (standard focal plane): the beam transmitted through the second second beam splitter 60 is directly guided to the first camera 40a. This optical path involves two transmissions, has the longest optical path, and involves relatively more optical components.

[0042] Although the position of the focal plane (i.e., the sample depth at which camera 40 focuses) is uniquely determined solely by the physical position (image distance) of the camera relative to the tube lens 22 and is independent of the beam splitting order, the beam splitting order in this embodiment is designed based on aberration control optimization. Key considerations are as follows: The images corresponding to the telephoto plane (second camera 40b) and the near-focal plane (third camera 40c) are inherently more susceptible to aberrations due to their deviation from the standard working distance of the objective lens 21-tube lens 22 system. These images are less aberration-corrected, have weaker optical performance, and are more easily affected by additional aberrations (such as coma and astigmatism). Therefore, the most sensitive optical path is prioritized and allowed to undergo the shortest possible optical path to minimize aberration introduction.

[0043] The second camera, 40b (telephoto plane), branches out first, resulting in the shortest optical path. This avoids aberration deterioration caused by long optical paths and preserves the already relatively fragile image quality. The third camera, 40c (nearphoto plane), has a centrally located optical path, striking a balance between aberration control and optical path complexity. The first camera, 40a (standard focal plane), offers the best image quality and aberration correction, thus enabling it to withstand longer optical paths with minimal negative impact.

[0044] Through the above design, this beam-splitting sequence ensures the stability of the overall imaging system, making the image clarity of each focal plane consistent during multi-layer detection, and improving the accuracy and reliability of AOI detection. While ensuring accurate focal plane positioning, it optimizes image quality, making it particularly suitable for precision detection of multi-layered chip structures. Those skilled in the art will understand that the specific implementation of the beam-splitting sequence may be adjusted using prisms, mirror groups, or other optical elements, but the core principle of optical path optimization based on aberration control should fall within the protection scope of this invention.

[0045] Please see Figure 1 This application further proposes that the chip multilayer AOI inspection device also includes multiple adjustable fixing sleeves 50, each of which is connected to a camera 40 for adjusting the distance between the camera 40 and the tube lens 22.

[0046] In this embodiment, the adjustable fixing sleeve 50 is a mechanical connection component with an adjustable axial length. Specifically, it can be implemented using a threaded engagement structure or a slide rail structure. By rotating or sliding, the overall length of the sleeve is changed, thereby adjusting the optical distance between the camera 40 and the lens 22. This structure allows different cameras 40 to be precisely fixed at different working distance positions, ensuring that each camera 40 simultaneously captures clear images from different focal planes.

[0047] Specifically, in the output optical path of the imaging module 20, each camera 40 is connected to the beam splitter module via an independently installed adjustable fixed sleeve 50. When it is necessary to adjust the distance between the camera 40 and the lens 22, the sleeve length can be changed by rotating the variable diameter threaded sleeve or sliding the slide rail mechanism, allowing the camera 40 to move along the optical axis to a preset working distance. For example, when the second camera 40b needs to obtain an imaging position greater than the standard working distance, its corresponding sleeve can be adjusted to an extended state; the sleeve corresponding to the third camera 40c is shortened to achieve a positioning less than the standard working distance. This independent adjustment mechanism allows multiple cameras 40 to simultaneously maintain differentiated optical distances from the lens 22, achieving crosstalk-free synchronous acquisition of images from different focal planes.

[0048] Compared to existing technologies, traditional AOI equipment typically uses a fixed mounting method for the camera 40, making it impossible to dynamically adjust the working distance for multi-layer inspection needs. This solution, however, utilizes the mechanical adjustment function of the adjustable fixing sleeve 50 to achieve independent control of the spacing between multiple cameras 40 without altering the optical path structure, thus avoiding the introduction of complex optical compensation devices or motor drive systems.

[0049] Through the above technical solution, this application realizes the rapid and accurate adjustment of the camera's working distance of 40°, ensuring the synchronization and stability of image acquisition at different focal planes, solving the problem of low efficiency in multi-layer detection caused by fixed installation of traditional equipment, and reducing system complexity and manufacturing costs.

[0050] Please see Figure 1 This application further proposes a beam splitting module including multiple second beam splitting prisms 60, the multiple second beam splitting prisms 60 and a camera 40 are arranged in sequence along the same straight line on the side of the first beam splitting prism 23 away from the tube mirror 22, and form a first optical path; the side of each second beam splitting prism 60 forms a second optical path with a camera 40, which is used to split the imaging light into multiple cameras 40 according to a preset ratio.

[0051] In this embodiment, the second beam-splitting prism 60 refers to an optical element with beam-splitting function, specifically a cubic beam-splitting prism or a flat beam-splitting prism. Its function is to split the incident imaging light into transmitted light and reflected light in a specific ratio. The first optical path refers to the main transmission path between the second beam-splitting prism 60 and the camera 40, which can be achieved by maintaining the straightness of the optical path using coaxial optical elements. Its function is to maintain the transmission direction of the main imaging optical path. The second optical path refers to the optical path split from the side of the second beam-splitting prism 60. This can be achieved by adjusting the angle of the prism's reflective surface. Its function is to guide the split beam to the corresponding camera 40. The preset ratio beam splitting refers to setting the ratio of transmitted to reflected energy of the beam-splitting prism according to imaging requirements. This can be achieved by selecting prisms with different coating parameters. Its function is to ensure that each camera 40 receives an imaging light signal of sufficient intensity.

[0052] Specifically, multiple second beam splitters 60 are arranged in a straight line behind the first beam splitter 23. The main imaging light passes through each beam splitter in sequence. Each beam splitter reflects part of the light to the side camera 40, and the remaining light continues to be transmitted in a straight line to the next beam splitter.

[0053] Compared to existing technologies, traditional multi-layer detection requires multiple focus adjustments for time-division shooting or the use of multiple independent imaging systems, increasing hardware costs. This solution, however, utilizes a cascaded beam-splitting structure of beam-splitting modules to simultaneously acquire multi-focal-plane images in a single exposure, avoiding the time delay of mechanical focusing and reducing the number of optical components.

[0054] Please see Figure 1 This application further proposes that the illumination module 10 in the chip multilayer AOI inspection equipment includes an illumination source 11, a condenser lens 12 and a lens 13 arranged in sequence, and the lens 13 is optically connected to the imaging module 20.

[0055] In this embodiment, the illumination source 11 refers to a light-emitting device used to generate the light required for detection, and its function is to provide basic illumination for the chip 1 under test. The condenser lens 12 refers to an optical element used to convert divergent light into convergent light, specifically a convex lens or a Fresnel lens, and its function is to focus the divergent light emitted by the illumination source 11 to improve light intensity utilization. The lens 13 refers to an optical element used to collimate or focus light, specifically a plano-convex lens or a biconvex lens, and its function is to convert the convergent light output from the condenser lens 12 into parallel light, ensuring that the illumination light uniformly covers the detection area of ​​the chip 1 under test. Optical path connection refers to the transmission of light through the spatial arrangement of optical elements, specifically coaxial alignment or a mirror group, and its function is to guide the light output from the illumination module 10 to the imaging module 20, allowing the illumination light and imaging light to share part of the optical path to simplify the system structure.

[0056] Specifically, the light emitted by the illumination source 11 is first focused by the condenser lens 12 to form a high-intensity converging beam, and then collimated by the lens 13 to generate a parallel beam. This parallel beam is transmitted to the imaging module 20, where it is coaxially aligned with the objective lens 21 and then illuminates the surface of the chip 1 under test. Due to the collimation effect of the lens 13, the illumination light forms a uniform illumination area on the chip surface, avoiding local brightness differences caused by light divergence. At the same time, the optical path connection design allows the illumination module 10 and the imaging module 20 to share core optical components such as the objective lens 21, reducing the introduction of additional optical path adjustment structures and thus reducing system complexity.

[0057] Compared with existing technologies, existing AOI equipment usually uses multi-angle light sources or structured light projection to acquire three-dimensional information, which requires complex multi-optical path design and algorithm reconstruction. In contrast, this solution achieves efficient collimation illumination through the combination of condenser lens 12 and lens 13, and only a single optical path is needed to cover multi-layer detection requirements.

[0058] Please see Figure 1 This application further proposes that the illumination module 10 of the chip multilayer AOI inspection equipment also includes an aperture stop 14, which is disposed between the illumination source 11 and the condenser lens 12, and is used to adjust the angle range of the light illuminating the chip 1 under test by the illumination source 11.

[0059] In this embodiment, the aperture stop 14 refers to a mechanical structure that controls the range of incident light angles. Specifically, it can be implemented using a thin metal sheet with an adjustable opening or a rotating aperture assembly. By changing the diameter of the light-passing aperture, the maximum divergence angle of the incident light is limited. The positional relationship between the illumination source 11 and the condenser lens 12 refers to the aperture stop 14 being positioned in the front of the focusing section of the light path exiting the light source. For example, it can be placed in the parallel light path between the collimating lens 13 and the condenser lens 12, achieving angle filtering by constraining the geometric boundaries of the light propagation path.

[0060] Specifically, in the illumination module 10, the light emitted by the light source first passes through the aperture stop 14, the size of which determines the angle range at which the light enters the condenser lens 12. When the aperture stop 14 narrows, only small-angle light close to the optical axis is allowed to pass through, forming an approximately collimated illumination beam; when the aperture widens, large-angle scattered light can also pass through, forming wide-angle illumination. This adjustment capability allows the illumination system to dynamically adjust the incident angle according to the reflectivity of the chip surface. For example, a small-angle illumination can be used for highly reflective metal layers to reduce glare, while a large-angle illumination can be used for transparent dielectric layers to enhance penetration.

[0061] In some specific embodiments, the aperture stop 14 can be integrated into the mounting bracket of the condenser lens 12 and manually adjusted via a threaded knob; or an electrically driven aperture, such as a six-bladed variable aperture driven by a stepper motor, can be connected to a control system for automated adjustment. During adjustment, the physical position of the aperture stop 14 remains fixed, and optical parameters are adjusted only by changing the opening size.

[0062] Compared to existing technologies, traditional AOI equipment lighting systems typically employ fixed apertures or omit angle control structures, resulting in the lighting beam angle being unable to adapt to the optical characteristics of different material layers. This solution, by adding an adjustable aperture stop 14, achieves precise control of the lighting beam divergence angle while maintaining the compact structure of the lighting module 10. This avoids specular reflection interference caused by excessively large incident angles or insufficient penetration depth due to excessively small angles.

[0063] Through the above technical solution, this application can dynamically optimize the illumination conditions according to the reflectivity differences of the materials in each layer of the chip. For example, it can suppress specular reflection noise when detecting surface metal lines and enhance the intensity of scattered signals when detecting the underlying transparent medium, thereby improving the contrast and signal-to-noise ratio of layered imaging, without the need to add complex optical components or motion mechanisms.

[0064] Please see Figure 1 This application further proposes that the illumination module 10 of the chip multilayer AOI inspection equipment also includes a field stop 15, which is located between the condenser lens 12 and the lens 13 and is used to adjust the size of the field stop 15.

[0065] In this embodiment, the field stop 15 refers to the aperture structure disposed between the condenser lens 12 and the lens 13. Specifically, it can be implemented using a mechanical variable aperture structure, controlling the illumination area range by adjusting its opening size. This structure is used to limit the effective coverage range of the illumination beam and prevent stray light from interfering with image quality. The condenser lens 12 is a component used to focus the illumination source 11, specifically implemented using a combination of aspherical lenses, and its function is to convert divergent light into a parallel beam. The lens 13 is an optical element located behind the condenser lens 12, specifically implemented using a biconvex lens, used to adjust the optical path direction to ensure coaxial alignment with the imaging module 20.

[0066] Specifically, after the illumination source 11 emits a beam, the condenser lens 12 converts the divergent light into a parallel beam. The field stop 15, by adjusting its opening size, defines the effective coverage area of ​​the parallel beam. The beam defined by the field stop 15, after its optical path direction is adjusted by the lens 13, forms an illumination optical path coaxial with the imaging module 20. This structure, by precisely controlling the boundary of the illumination area, eliminates the interference of stray light from the edges on the imaging module 20, ensuring that the illumination spot precisely matches the effective detection area of ​​the chip 1 under test.

[0067] Compared to existing technologies, traditional AOI equipment typically lacks a field stop 15 structure, resulting in blurred boundaries of the illuminated area and allowing stray light to easily enter the imaging optical path, creating background noise. This solution adds a field stop 15, enabling controllable adjustment of the illuminated area while maintaining the coaxiality of the optical path, effectively suppressing stray light interference with image contrast.

[0068] Through the above technical solution, this application can precisely control the effective coverage area of ​​the illumination beam, avoid light interference from ineffective areas, and improve the contrast consistency of images from different focal planes. This structure optimizes illumination conditions through physical limiting, providing a stable optical environment for multiple cameras to simultaneously capture clear images, thereby improving the detection accuracy of multi-layer defects in chips.

[0069] Please see Figure 1 and Figure 7 The present invention also proposes a detection method for a multi-layer AOI inspection device for chips. The multi-layer AOI inspection device for chips adopts the multi-layer AOI inspection device described above. The steps of the detection method for the multi-layer AOI inspection device for chips include: S10: Control the lighting module 10 to emit illumination light to the chip 1 under test; Specifically, when the illumination source 11 is turned on, the light passes sequentially through the aperture stop 14, the condenser lens 12, the field stop 15, and the lens 13 to form a uniform Kohler illumination beam. This illumination beam is then guided to the first beam splitter 23.

[0070] S20: The same set of objective lenses 21, tube lenses 22 and first beam splitter 23 of the imaging module 20 are used to collect light reflected or transmitted through different layers of the chip to be detected to form imaging light. This step is the core of achieving layered imaging. The specific process is as follows: (1) After being reflected by the first beam splitter 23, the illumination beam is incident perpendicularly onto the objective lens 21 and is focused onto the chip 1 to be tested. (2) The reflected or transmitted light carrying information about the chip surface, intermediate layer and bottom layer is collected again by the objective lens 21 and returns in the form of parallel light (imaging light). (3) This parallel light (imaging light) passes through the first beam splitter 23 and enters the matching tube lens 22. The tube lens 22 focuses the parallel light to prepare for forming a real image.

[0071] S30: The beam splitting module splits the imaging light into multiple imaging sub-paths; The imaging light, converged by the tube lens 22, enters the beam-splitting module. In this embodiment, the beam-splitting module includes a beam-splitting prism (R:T=1:2) and a beam-splitting prism (R:T=1:1). The imaging light is first split into two beams by the beam-splitting prism: one beam of transmitted light (approximately 2 / 3 of the light intensity) continues to propagate forward, while the other beam of reflected light (approximately 1 / 3 of the light intensity) is deflected at 90 degrees and enters the first imaging sub-path. The transmitted light continues to propagate to the beam-splitting prism and is split equally again: one beam of reflected light enters the second imaging sub-path, and the other beam of transmitted light enters the third imaging sub-path. By rationally designing the transmittance-to-reflection ratio of the beam-splitting prism, it is ensured that the light intensity reaching each camera 40 is basically the same, thus obtaining images of similar quality.

[0072] S40: Multiple cameras 40 arranged on the multi-beam imaging sub-optical path simultaneously receive the imaging light, wherein the optical working distance of each camera 40 relative to the tube mirror 22 is set to be different, so that each camera 40 synchronously captures images of different focal planes of the chip to be detected 1. Multiple cameras 40 arranged in the multi-beam imaging sub-optical path simultaneously receive the imaging light, wherein the optical working distance of each camera 40 relative to the tube mirror 22 is set to be different, so that each camera 40 synchronously captures images of the chip under test 1 at different focal planes.

[0073] This is a crucial step in achieving synchronous, multi-layer detection. An illustration of photographing a transparent or semi-transparent chip with three-dimensional defects is shown below. Figure 2 As shown. Figure 2 The diagram illustrates two defective chips, with red balls representing the defect locations. Three cameras 40 are precisely fixed at a specific working distance relative to the scope 22 via adjustable retaining sleeves 50. The first camera 40a is set at the standard working distance of the tube lens 22. Therefore, it focuses clearly on the object surface located at the working distance of the objective lens 21, i.e., the upper surface of the chip (such as the electrode layer), and its imaging effect is as follows: Figure 3 As shown.

[0074] The second camera 40b is positioned beyond the standard working distance of the tube lens 22 via an adjustable fixing sleeve 50. According to the principles of geometric optics, this allows its sharp imaging plane to correspond to an object plane closer to the objective lens 21, i.e., the intermediate layer of the chip (such as the light-emitting layer), resulting in an imaging effect as follows: Figure 4 As shown.

[0075] The third camera 40c is positioned less than the standard working distance of the lens 22 via an adjustable fixing sleeve 50. This allows its sharp imaging plane to correspond to an object plane far from the objective lens 21, i.e., the bottom layer of the chip (such as the substrate), and its imaging effect is as follows: Figure 5 As shown.

[0076] During the detection process, the system triggers the three cameras 40 to perform synchronous exposure and image acquisition. Since the optical path beam splitting and camera 40 settings are physically fixed, clear images of the chip's upper, middle, and lower focal planes can be obtained simultaneously in a single scan, making the detection efficiency comparable to single-scan planar AOI detection.

[0077] S50: Based on the images of the different focal planes captured synchronously by each of the cameras 40, analyze the defect distribution of the chip to be tested 1 in three-dimensional space.

[0078] Multiple images captured simultaneously are transmitted to an image processing unit (not shown). Instead of performing complex, pixel-level 3D model reconstruction, the processing unit employs the following efficient analysis strategy: (1) Layered comparison: Images acquired by each camera (e.g., 40) are compared. Figure 3 , 4 5) Compare the images with the standard defect-free images of the corresponding layers to identify defects such as scratches and impurities in each layer.

[0079] (2) Three-dimensional positioning: When a defect is identified in an image of a certain layer, the approximate position of the defect in the chip depth direction (Z-axis) can be directly determined based on the camera's working distance of 40° (i.e., the known focal plane height). Combined with the defect's planar position (X, Y axes) in the image, the distribution of the defect in three-dimensional space can be quickly located (e.g., ...). Figure 6 (Illustration)

[0080] (3) Comprehensive judgment: Based on the occurrence, type and severity of defects in each layer, the overall quality of the chip is comprehensively judged to achieve rapid and accurate non-destructive testing.

[0081] In summary, the method of the present invention, through ingenious physical optical path design and camera working distance setting of 40, transforms complex three-dimensional defect detection into efficient multi-plane synchronous image acquisition and comparison, eliminating the need for repeated scanning of moving parts or complex calculation reconstruction. While ensuring comprehensive detection, it significantly improves detection efficiency and reduces system costs.

[0082] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A chip multilayer AOI inspection device, characterized in that, The chip multilayer AOI inspection equipment includes: The lighting module is used to emit a light source; An imaging module, optically connected to the illumination module, is used to receive light from the chip under test and form imaging light; A beam splitting module, disposed in the output optical path of the imaging module, is used to split the imaging light output by the imaging module into multiple beams; and Multiple cameras are respectively set in the output optical path of the beam splitting module, and each camera is at a different optical distance from the imaging module, so as to simultaneously receive images of different focal planes.

2. The chip multilayer AOI inspection equipment as described in claim 1, characterized in that, The imaging module includes an objective lens, a tube lens, and a first beam splitter arranged in sequence, with the first beam splitter being disposed adjacent to the illumination module; the first beam splitter is disposed adjacent to the beam splitter module. The objective lens is used to collect light reflected or transmitted from the chip under test; The first beam splitter is used to reflect the illumination light from the illumination module to the coaxially arranged objective lens, and to transmit the parallel light returned by the objective lens, carrying the information of the chip to be tested, to the tube mirror and the beam splitter module; the tube mirror is used to pair with the objective lens, receive the parallel light transmitted from the first beam splitter, and converge the parallel light into a clear real image.

3. The chip multilayer AOI inspection equipment as described in claim 2, characterized in that, The number of cameras is three, and the three cameras are respectively defined as the first camera, the second camera, and the third camera; the distance between the first camera and the tube mirror is the standard working distance, the distance between the second camera and the tube mirror is greater than the working distance, and the distance between the third camera and the tube mirror is less than the working distance.

4. The chip multilayer AOI inspection equipment as described in claim 3, characterized in that, The second camera, the third camera, and the first camera are arranged sequentially on the side of the imaging module away from the chip to be detected.

5. The chip multilayer AOI inspection equipment as described in claim 2, characterized in that, The chip multilayer AOI inspection device also includes multiple adjustable fixing sleeves, each of which is connected to a camera to adjust the distance between the camera and the endoscope.

6. The chip multilayer AOI inspection equipment as described in claim 2, characterized in that, The beam splitting module includes multiple second beam splitting prisms. The multiple second beam splitting prisms and a camera are arranged sequentially along the same straight line on the side of the first beam splitting prism away from the tube mirror, forming a first optical path. The side of each second beam splitting prism forms a second optical path with a camera, which is used to split the imaging light into multiple cameras according to a preset ratio.

7. The chip multilayer AOI inspection equipment as described in claim 1, characterized in that, The lighting module includes a lighting source, a condenser lens, and a lens arranged in sequence, and the lens is connected to the optical path of the imaging module.

8. The chip multilayer AOI inspection equipment as described in claim 7, characterized in that, The illumination module also includes an aperture stop, which is disposed between the illumination source and the condenser lens, and is used to adjust the angle range of the light illuminating the chip under test by the illumination source.

9. The chip multilayer AOI inspection equipment as described in claim 7, characterized in that, The illumination module also includes a field stop, which is located between the condenser lens and the lens and is used to adjust the size of the field stop.

10. A detection method for a multilayer AOI inspection device for chips, characterized in that, The chip multilayer AOI inspection equipment uses the chip multilayer AOI inspection equipment as described in any one of claims 1 to 9, and the inspection method of the chip multilayer AOI inspection equipment includes the following steps: The control lighting module emits illumination light to the chip under test; The same set of objective lenses, tube lenses, and first beam splitter of the imaging module are used to collect light reflected or transmitted through different layers of the chip under test to form imaging light. The beam splitting module splits the imaging light into multiple imaging sub-paths; Multiple cameras arranged along the multi-beam imaging sub-optical path simultaneously receive the imaging light, wherein the optical working distance of each camera relative to the tube mirror is set differently, so that each camera synchronously captures images of different focal planes of the chip under test; and Based on the images of different focal planes captured synchronously by each of the cameras, the defect distribution of the chip under test in three-dimensional space is analyzed.

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