System and method for detecting wafer crack and computer readable storage medium

Abstract

The invention discloses a system and method for detecting wafer cracks and a computer readable storage medium, and relates to the technical field of semiconductor detection, and the system comprises a main detection camera which is used for collecting a white light image of the surface of a wafer so as to detect the cracks of the surface of the wafer; and the re-judgment camera is used for collecting an infrared image of the bottom layer of the wafer so as to detect the crack of the bottom layer of the wafer. Through the system, the accuracy and the detection efficiency of wafer crack defect detection can be improved.

Description

Technical Field

[0001] The present application generally relates to the field of semiconductor detection technology. More specifically, the present application relates to a system, method and storage medium for detecting wafer cracks. Background Art

[0002] When producing chips, the silicon materials used often go through a series of processes such as growth, slicing, grinding, testing, epitaxial growth, photolithography, and deposition. Due to the brittleness of silicon wafers, each process may damage them, causing cracks and scratches. Generally, scratches on the surface will not affect the working performance of the chip, while surface cracks are often accompanied by hidden cracks in the bottom layer of the wafer (the raw material of the chip). Hidden cracks correspond to smaller and harder to detect cracks, which will seriously affect the working performance of the chip. Therefore, it is very necessary to detect cracks on the entire wafer.

[0003] In the past, the detection methods usually used optical microscopes, laser scanning methods or X-ray imaging methods to detect wafer cracks. However, these methods are limited to only detecting cracks on the surface of the wafer or cracks on the bottom of the wafer, and cannot detect both cracks at the same time, which affects the accuracy of wafer detection.

[0004] In view of this, there is an urgent need to provide a system, method and computer-readable storage medium solution for detecting wafer cracks, so as to improve the accuracy of detecting wafer crack defects. Summary of the invention

[0005] In order to at least solve one or more of the technical problems mentioned above, the present application proposes a system, method and storage medium solution for detecting wafer cracks in multiple aspects.

[0006] In a first aspect, the present application provides a system for detecting cracks in a wafer, comprising: a main inspection camera for capturing white light images of a wafer surface to detect cracks on the wafer surface; and a re-inspection camera for capturing infrared images of a bottom layer of the wafer to detect cracks in the bottom layer of the wafer.

[0007] In some embodiments, the main inspection camera includes: an objective lens, a turret, a focusing device, a lighting device and a detection camera; the objective lens is arranged below the turret to magnify the surface of the wafer; the turret is arranged below the detection camera to switch the objective lens; the focusing device and the lighting device are arranged beside the detection camera, the focusing device is used to assist the detection camera in focusing, and the lighting device is used to provide a white light source for the detection camera; the detection camera is arranged above the turret to capture the light reflected or scattered by the wafer surface to form the white light image.

[0008] In some embodiments, the re-judgment camera includes: an infrared camera, an infrared lens barrel, an infrared objective lens, and an infrared light source; the infrared camera is arranged above the infrared lens barrel for capturing infrared images; one end of the infrared lens barrel is connected to the infrared camera, and the other end is connected to the infrared objective lens for providing an optical path for infrared light; the infrared objective lens is arranged below the infrared lens barrel for focusing infrared light; the infrared light source is used to provide infrared light for the infrared camera.

[0009] In some embodiments, the main inspection camera is used to detect cracks on the edge surface of the wafer, and the re-inspection camera is used to detect cracks in the bottom layer of the wafer based on the detection results of the main inspection camera.

[0010] In some embodiments, a main control unit is also included, which is used to control the main inspection camera to detect cracks on the edge surface of the wafer, and to control the re-inspection camera to detect cracks in the bottom layer of the wafer according to the detection results of the main inspection camera.

[0011] In some embodiments, at a position where the main inspection camera detects a crack on the edge surface of the wafer, the re-inspection camera detects whether there is a crack on the bottom layer of the wafer within a first preset distance range from the end of the crack at the position of the crack to the inside of the wafer; at a position where the main inspection camera detects no crack on the edge surface of the wafer, the re-inspection camera detects whether there is a crack on the bottom layer of the wafer within a second preset distance range from the edge of the wafer to the inside of the wafer.

[0012] In some embodiments, the first preset distance range and the second preset distance range are three lens field of view ranges of the re-judgment camera.

[0013] In a second aspect, the present application also provides a method for detecting wafer cracks, comprising: controlling a main inspection camera to capture a white light image of the wafer surface; detecting whether there are cracks on the wafer surface based on the white light image and outputting a detection result; based on the detection result, controlling a re-inspection camera to capture an infrared image of the bottom layer of the wafer; and detecting cracks in the bottom layer of the wafer based on the infrared image.

[0014] In some embodiments, controlling the re-judgment camera to capture an infrared image of the bottom layer of the wafer based on the detection result includes: if the detection result is yes, controlling the re-judgment camera to capture an infrared image within a first preset distance range from the end of the crack to the inside of the wafer at the location of the crack; if the detection result is no, controlling the re-judgment camera to capture an infrared image within a second preset distance range from the edge of the wafer to the inside of the wafer.

[0015] In a third aspect, the present application further provides a computer-readable storage medium storing computer program instructions for detecting wafer cracks. When the computer program instructions are executed by a processor, the method described in any one of the above items is performed.

[0016] The embodiment of the present application provides a system for detecting wafer cracks as provided above, including: a main inspection camera, which is used to collect white light images of the wafer surface to detect cracks on the wafer surface; and a re-judgment camera, which is used to collect infrared images of the bottom layer of the wafer to detect cracks in the bottom layer of the wafer. Through the above two cameras, it is possible to perform fine detection of cracks on the wafer surface and even on the bottom layer of the wafer, thereby improving the accuracy of wafer crack detection. Further, in some embodiments, the main inspection camera collects white light images of the wafer surface, detects whether there are cracks on the wafer surface according to the white light images, and outputs the detection results. Subsequently, the re-judgment camera collects infrared images of the bottom layer of the wafer according to the detection results, and detects cracks in the bottom layer of the wafer according to the infrared images. Further, in some embodiments, if the detection result shows that there are cracks on the wafer surface, the re-judgment camera collects infrared images of the first preset distance range from the end of the crack to the inside of the wafer at the position of the crack; if the detection result shows that there are no cracks on the wafer surface, the re-judgment camera collects infrared images of the second preset distance range from the edge of the wafer to the inside of the wafer. By controlling the re-inspection camera to execute corresponding inspection strategies according to different inspection results, it is possible to improve the overall inspection efficiency while ensuring that wafer cracks are fully detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] By reading the detailed description below with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present application will become easy to understand. In the accompanying drawings, several embodiments of the present application are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein: Figure 1 A schematic diagram of the structure of a main inspection camera in a system for detecting wafer cracks in an embodiment of the present application is shown; Figure 2 A schematic diagram of the structure of a re-judgment camera in a system for detecting wafer cracks according to an embodiment of the present application is shown; Figure 3 An exemplary flow chart showing a method for detecting wafer cracks according to some embodiments of the present application is shown; Figure 4 A first schematic diagram of a wafer surface in an embodiment of the present application is shown; Figure 5 A second schematic diagram of a wafer surface in an embodiment of the present application is shown; Figure 6 An example diagram of a real detection image of the main detection camera in an embodiment of the present application is shown; Figure 7 An example diagram of a real detection image of a re-judgment camera in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0019] It should be understood that the terms "include" and "comprising" used in the specification and claims of the present application indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0020] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this application specification and claims, unless the context clearly indicates otherwise, the singular forms of "a", "an" and "the" are intended to include plural forms. It should also be further understood that the term "and / or" used in this application specification and claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0021] As used in this specification and claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0022] The specific implementation of the present application is described in detail below with reference to the accompanying drawings.

[0023] Reference Figure 1 and Figure 2 , to introduce the system for detecting wafer cracks in the present application (hereinafter referred to as the system). In the system, a main inspection camera and a re-inspection camera are included. The main inspection camera is used to collect white light images of the wafer surface to detect cracks on the wafer surface. The re-inspection camera is used to collect infrared images of the bottom layer of the wafer to detect cracks in the bottom layer of the wafer. In some embodiments, the main inspection camera is a device for detecting cracks on the wafer surface, such as Figure 1The main inspection camera shown can use a white light source or other broad-spectrum light source to illuminate the wafer surface, and the light is reflected back according to the different morphologies and heights of the wafer surface. If there are cracks on the wafer surface, the height of the wafer surface will be different, which will affect the reflection effect of the light. The main inspection camera uses this principle to collect white light images and capture small height changes on the wafer surface, including cracks, scratches, etc.

[0024] In addition, the white light image captured by the main inspection camera can be used not only to detect cracks on the surface of the wafer, but also to identify scratches. In the actual production process, scratches and cracks may occur on the surface of the wafer, and minor scratches usually do not affect the normal function of the chip. The main inspection camera can distinguish between scratches and cracks on the surface of the wafer and filter them out from the identification results of wafer cracks. In a feasible embodiment, scratches identified from the white light image can be classified according to features such as their height difference. Scratches that do not affect the working performance of the wafer can be ignored or marked as defects that do not need to be paid attention to, thereby avoiding unnecessary detection interference. It should be noted that white light cannot penetrate to the bottom layer of the wafer, so the main inspection camera can only be used to detect cracks on the surface of the wafer, and potential cracks in the bottom layer of the wafer need to be detected by a re-judgment camera.

[0025] like Figure 2 The re-inspection camera shown is an infrared industrial camera that can emit infrared light that penetrates the surface of the wafer and reaches the bottom layer. Different layers of the wafer have different absorption and reflection of infrared light, and the presence of cracks will affect the transmission path and reflection path of infrared light. These changes can be captured by the re-inspection camera to form an infrared image. By identifying and analyzing the infrared image, cracks in the bottom layer of the wafer can be detected. In a feasible embodiment, the re-inspection camera can be a short-wave infrared camera based on indium gallium arsenide, which can have a good response in the wavelength range of 900 to 1700nm, suitable for penetrating the wafer for infrared imaging.

[0026] In the above content, through the division of labor between the main inspection camera and the re-inspection camera, white light detection and infrared detection are combined together, which can achieve effective detection of cracks on the surface and bottom layer of the wafer in a targeted and comprehensive manner, thereby improving the accuracy of wafer crack detection.

[0027] Reference Figure 1, the system for detecting wafer cracks of the present application is introduced in detail, wherein the main inspection camera includes: an objective lens 1, a turret 2, a focusing device 3, a detection camera 5 and an illumination device 4. The objective lens 1 is arranged below the turret 2 for magnifying the surface of the wafer; the turret 2 is arranged below the detection camera 5 for switching the objective lens 1; the focusing device 3 and the illumination device 4 are arranged beside the detection camera 5, the focusing device 3 is used to assist the detection camera 5 in focusing, and the illumination device 4 is used to provide a white light source for the detection camera 5; the detection camera 5 is arranged above the turret 2 for capturing the light reflected or scattered from the wafer surface to form a white light image.

[0028] In some embodiments, the objective lens 1 can magnify the wafer surface and accurately project the magnified optical image of the wafer to the detection camera 5, thereby helping the detection camera 5 to capture a clear white light image of the wafer surface. In a feasible embodiment, there can be multiple objective lenses 1, and these multiple objective lenses have different magnifications. Objective lenses of different magnifications determine the accuracy and range of detection, so they can be used for different detection needs. For example, a low-magnification objective lens can be used for large-scale scanning and preliminary inspection of the wafer surface, while a high-magnification objective lens can be used to detect more subtle crack defects or surface features on the wafer surface. Figure 1 The three objective lenses shown can be switched via the turret 2 .

[0029] The turret 2 is a rotating device in the main inspection camera, which is used to support the switching of multiple objective lenses. In a feasible embodiment, the rotation of the turret 2 can be controlled by a main control unit (not shown in the figure). Figure 1 As shown, the turret 2 is arranged below the detection camera and has three objective lens mounting positions, each of which is equipped with an objective lens 1. The turret can realize rapid switching between different objective lenses by rotating to adapt to different detection tasks.

[0030] In some cases, the slight height difference of the wafer surface needs to be compensated by focusing, and the focusing device 3 can achieve the above purpose. The focusing device 3 can adjust the distance between the objective lens and the wafer surface to achieve clear image imaging. Figure 1 As shown, the focusing device 3 is arranged below the side of the detection camera 5. During the detection process, the focusing device 3 can achieve real-time focusing, thereby assisting the detection camera 5 to obtain a clear white light image.

[0031] The lighting device 4 uses a white light source or other types of light sources (such as LEDs, fluorescent lamps, etc.), which provides necessary lighting support for the white light image acquisition process of the inspection camera 5, and improves the contrast of the white light image finally obtained by the main inspection camera by illuminating the wafer surface. Figure 1As shown, the lighting device 4 is arranged beside the inspection camera 5, and is vertically directed downward to the wafer inspection station. In a feasible implementation, the position and illumination intensity of the lighting device 4 can be adjusted to adapt to the collection of white light images of different wafer surfaces.

[0032] The detection camera 5 is installed above the turret 2, and is responsible for collecting the reflection image of the wafer surface under white light irradiation, thereby obtaining a white light image. The detection camera 5 needs to have a high resolution and be matched with a high-magnification objective lens to meet the high-precision acquisition requirements of white light images. For example, as a feasible implementation, the resolution of the detection camera can be 5120*4096, the pixel (that is, the most basic measurement unit of the image sensor in the camera) size is 4.5um, and the objective lens magnification is 20. This combination can detect defects larger than 5um. In addition, in a feasible implementation, two or more detection cameras with different imaging fields of view can be used to complete the task of collecting white light images. Figure 1 As shown, the detection camera 5 includes a detection camera 51 and a detection camera 52. The detection camera 51 at the top has a large imaging field of view and a faster detection speed. The detection camera 52 at the bottom has a small imaging field of view and is more suitable for fine detection. In the actual acquisition process, the detection camera 51 can quickly scan the wafer surface due to its large imaging field of view, so it is mainly used for preliminary screening of the wafer surface. The detection camera 52 at the bottom has a smaller imaging field of view, higher precision and more detailed focusing ability, so it can be used for higher resolution detail detection of the area preliminarily screened by the detection camera 51. In this way, the detection camera 51 has a fast detection speed due to its large imaging field of view, while the detection camera 52 focuses on fine detection. The combination of the two can ensure detection efficiency while not losing detection accuracy.

[0033] In the above embodiment, the objective lens 1, the turret 2, the focusing device 3, the lighting device 4, and the detection camera 5 constitute the main inspection camera, which will be used to collect the white light image of the wafer surface. At the same time, multiple objective lenses with different magnifications can be adapted to different detection requirements. The detection cameras with different imaging fields can flexibly complete the collection of white light images.

[0034] Reference Figure 2, to continue to introduce the system of the present application for detecting wafer cracks, wherein the re-inspection camera includes: an infrared camera 8, an infrared lens barrel 7, an infrared objective lens 6, and an infrared light source. The infrared camera 8 is arranged above the infrared lens barrel 7 to capture infrared images; one end of the infrared lens barrel 7 is connected to the infrared camera 8, and the other end is connected to the infrared objective lens 6 to provide an optical path for the infrared light; the infrared objective lens 6 is arranged below the infrared lens barrel 7 to focus the infrared light; and the infrared light source is used to provide infrared light for the infrared camera 8. In some embodiments, the infrared camera 8 is the core component of the re-inspection camera, which can capture the infrared light reflected from the bottom layer of the wafer through a built-in detector (such as an InGaAs detector, etc.), and convert it into an infrared image that can be analyzed. Figure 2 As shown, the infrared camera 8 is installed above the infrared lens barrel 7 and faces the infrared objective lens 6 below.

[0035] The infrared lens barrel 7 plays a supporting and docking role, connecting the infrared camera 8 with the infrared objective lens 6, and providing an optical path to guide the infrared light focused by the infrared objective lens 6 so that these lights can accurately enter the infrared camera 8 so that the infrared camera 8 can image and process them. The infrared objective lens 6 is located below the infrared lens barrel, which is responsible for focusing the infrared light and focusing the infrared light onto the detector of the infrared camera 8. The infrared light source (not shown in the figure) can emit infrared light of a specific wavelength (such as 1100nm) to penetrate the inside of the wafer. Optionally, the infrared light source can be a continuous wave emitter (such as an LED infrared light source) or a pulse emitter (laser diode). In a feasible implementation, the composition of the components of the re-judgment camera can be set as follows: the resolution of the infrared camera is 1280*1024, the pixel size is 5um, the magnification of the infrared objective lens is 5X, and the infrared light source provides 1100nm infrared light. The above composition can make the re-judgment camera achieve a detection accuracy of 1um, that is, it can identify defects with a minimum size of 1um.

[0036] To facilitate understanding of the overall process of infrared image acquisition by the re-judgment camera, the following is combined with Figure 2 The structure of the re-inspection camera shown in FIG. 1 is described as a whole. First, the infrared light source can irradiate infrared light of a specific wavelength to the wafer at the inspection station. The infrared light can penetrate the surface of the wafer and reach the bottom layer. During this period, due to the interaction with the inside and surface of the wafer, part of the infrared light is reflected. The reflected infrared light is focused by the infrared objective lens 6 and reaches the infrared camera through the infrared lens barrel 7. The infrared camera 8 receives the reflected light signal through the built-in indium gallium arsenide detector and converts it into an electrical signal. These electrical signals are processed to form the final infrared image.

[0037] In the above embodiment, the re-inspection camera can effectively detect deep cracks in the wafer while performing non-destructive inspection on the wafer, thereby making up for the deficiency that the main inspection camera can only inspect the surface of the wafer.

[0038] Furthermore, in the system for detecting wafer cracks in the present application, the main inspection camera is used to detect cracks on the edge surface of the wafer, and the re-inspection camera is used to detect cracks in the bottom layer of the wafer according to the detection results of the main inspection camera. In most scenarios, the edge area of ​​the wafer is more prone to cracks than the middle part during the manufacturing, cutting, transportation and other processing processes. Therefore, in some embodiments, the main inspection camera can be used to directly detect the crack-prone areas of the wafer, that is, the cracks on the surface at the edge of the wafer, so that the overall detection efficiency can be improved. It is understandable that the presence of cracks on the surface of the wafer will also cause small cracks in the bottom layer of the wafer to a great extent. Therefore, the re-inspection camera can further detect cracks in the bottom layer of the wafer according to the detection results of the main inspection camera. In a feasible embodiment, the re-inspection camera can detect cracks in the bottom layer by detecting cracks in the bottom layer at the edge of the wafer and cracks in the bottom layer inside the wafer.

[0039] Furthermore, the system for detecting wafer cracks provided by the present application also includes a main control unit, which can control the main inspection camera to detect cracks on the edge surface of the wafer, and control the re-judgment camera to detect cracks in the bottom layer of the wafer according to the detection results of the main inspection camera. In some embodiments, a communication connection can be established between the main control unit and the main inspection camera and the re-judgment camera, and data and signals are exchanged through a high-speed data transmission channel. In this system, the main control unit is responsible for coordinating and controlling the entire detection process. It can receive white light images and infrared images collected by the main inspection camera and the re-judgment camera respectively, and analyze and process them to identify cracks on the surface and bottom layer of the wafer. At the same time, the main control unit can also control the detection methods of the main inspection camera and the re-judgment camera respectively.

[0040] In a feasible embodiment, the main control unit controls the main inspection camera to scan the edge of the wafer surface and complete the acquisition of the white light image. Then, the main control unit detects and analyzes the white light image to determine whether there is a crack on the edge of the wafer surface. Then, the main control unit controls the re-judgment camera to detect cracks in the bottom layer of the wafer based on the detection result. For ease of understanding, the following is combined with Figure 4 and Figure 5 To explain, Figure 4 and Figure 5 The schematic diagram of the wafer surface is shown in FIG. The annular area is the wafer edge surface, the circular area is the inner area of ​​the wafer surface, and the part below the surface is collectively referred to as the wafer bottom layer. Figure 4 As shown in the figure, when the detection result of the main inspection camera is that there is a crack on the edge surface of the wafer, the re-inspection camera, as shown by the dotted arrow, detects whether there is a crack on the bottom layer of the wafer within a first preset distance range from the end of the crack to the inside of the wafer at the location where the crack is detected. Figure 5As shown by the two dotted arrows, the re-inspection camera detects whether there is a crack in the bottom layer of the wafer within a second preset distance range from the edge of the wafer to the inside of the wafer along the direction indicated by the upper dotted arrow, and then repeats the above process again in the direction indicated by the lower dotted arrow to detect other areas of the wafer.

[0041] The first preset distance range and the second preset distance range refer to a specific number of lens field of view ranges of the re-judgment camera. It can be understood that, based on the component composition of the re-judgment camera, the size of its lens field of view is jointly determined by the size of the infrared objective lens and the photosensitive element inside the infrared camera. As a feasible implementation, the first preset distance range and the second preset distance range can be set as three lens field of view ranges of the re-judgment camera. Specifically, the re-judgment camera detects whether there is a crack in the bottom layer of the wafer within the first preset distance range from the end of the crack to the inside of the wafer. In this process, the re-judgment camera is positioned at the end of the crack, and then starts from the end of the crack and gradually moves toward the inside of the wafer. Every time it passes through a lens field of view, an infrared image is collected. That is, the re-judgment camera passes through three different lens field of view areas in turn, and continuously collects three infrared images to check the tiny cracks in the bottom layer of the wafer, where each lens field of view area represents a position or angle taken by the re-judgment camera.

[0042] Similarly, the re-inspection camera detects whether there are cracks on the bottom layer of the wafer within a second preset distance range from the edge of the wafer to the inside of the wafer. During this process, the re-inspection camera starts from the edge of the wafer and gradually scans toward the inside of the wafer, passing through three different lens field of view areas in turn, and continuously collects three infrared images to check for tiny cracks on the bottom layer of the wafer. Optionally, in a feasible implementation, the running trajectory of the re-inspection camera during this process may only pass through part of the edge areas on both sides of the wafer, while the internal area of ​​the wafer passes quickly. Figure 5 As shown by the directions of the two dotted arrows in the figure, the re-inspection camera moves from the edge area on the left side of the wafer to the inner area of ​​the wafer, passes through the inner area of ​​the wafer quickly, and then moves out from the edge area on the right side of the wafer. In another feasible implementation, the running trajectory of the re-inspection camera can also be a full coverage scan of the wafer, that is, collecting infrared images of the entire area of ​​the wafer.

[0043] It should be noted that the settings of the first preset distance range and the second preset distance range need to be set together according to the original lens field of view of the re-inspection camera, the wafer size, and the crack extension range. If the distance range is set too small, the bottom cracks of the wafer may not be fully detected, while if it is set too large, the overall detection efficiency may be reduced. In the above embodiment, the first preset distance range and the second preset distance range are set as the three lens field of view ranges of the re-inspection camera, which can ensure that the bottom defects can be fully detected while ensuring the detection efficiency. In other feasible embodiments, the first preset distance range and the second preset distance range can be set as needed to the lens field of view ranges of different numbers of re-inspection cameras, without too much limitation here.

[0044] In the above embodiment, by first using the main inspection camera to perform a rapid, large-scale preliminary inspection of the wafer surface, obvious surface cracks or defects can be quickly captured. Then, the re-inspection camera is used to further inspect the more difficult-to-detect cracks in the bottom layer of the wafer based on the inspection results of the main inspection camera. In this way, the reliability and accuracy of wafer crack detection can be improved. At the same time, through targeted inspection processes, the overall inspection efficiency can also be improved.

[0045] Figure 3 The method 30 for detecting wafer cracks of the present application is shown. It is understandable that the method 30 for detecting wafer cracks can be implemented based on the system described above. Therefore, the description of each component in the system in the above text can also be applied to the following. Figure 3 As shown, the method 30 for detecting wafer cracks includes: at step S301, controlling the main inspection camera to collect a white light image of the wafer surface. In some embodiments, the main inspection camera can be controlled to complete the task of collecting the white light image of the wafer surface by outputting different types of control signals to the main inspection camera. For example, by outputting movement signals in the X-axis, Y-axis and Z-axis directions to the main inspection camera, the movement of the main inspection camera in the horizontal and vertical directions is controlled to ensure that it can accurately align with different areas of the wafer surface. In addition, the moving speed of the main inspection camera, as well as the autofocus and shooting timing of the main inspection camera can be controlled separately by speed control signals and shooting trigger signals.

[0046] In a feasible embodiment, the main inspection camera can be controlled to only collect white light images of the crack-prone areas on the wafer surface, such as the white light images of the edge of the wafer surface, to improve the inspection efficiency. In this process, the computer vision algorithm built into the main control unit can be used to identify the edge of the wafer, so as to use it as the collection area, avoiding the collection of other unnecessary areas of the wafer.

[0047] Next, at step S302, the surface of the wafer is detected based on the white light image to see if there are cracks and the detection results are output. In some embodiments, the white light image captured by the main inspection camera is further processed and analyzed to detect whether there are cracks on the surface of the wafer. In one embodiment, the white light image can be pre-processed by denoising, graying and other pre-processing steps to keep clearer image features. Subsequently, a specific detection algorithm (such as Canny edge detection, etc.) can be used to extract the contour of the approximate crack in the white light image, and morphological operations such as expansion and corrosion can be used to enhance the connectivity of the crack. Finally, the texture analysis technology is used to detect the area where the crack is located. In addition, in order to ensure that cracks rather than scratches are detected, the corresponding aspect ratio, shape and other parameters can be calculated based on the area where the crack is located to determine whether it meets the crack standard, thereby further completing the verification of the crack detection results.

[0048] After the white light image detection is completed, the corresponding detection result can be output, which includes whether there are cracks on the wafer surface. If there are cracks, it also includes the number of cracks, location on the wafer, size, etc. Based on the detection result, the re-judgment camera can be controlled to carry out further detection in the subsequent process.

[0049] Further, at step S303, according to the detection result, the re-judgment camera is controlled to collect an infrared image of the bottom layer of the wafer. In some embodiments, the detection result of the main inspection camera determines how the re-judgment camera will collect an infrared image of the bottom layer of the wafer. If the detection result is yes, that is, there is a crack on the surface of the wafer, the re-judgment camera is controlled to collect an infrared image from the end of the crack to the inside of the wafer at the crack position, and the collection range is the first preset distance range. If the detection result is no, that is, there is no crack on the surface of the wafer, the re-judgment camera is controlled to collect an infrared image from the edge of the wafer to the inside of the wafer, and the collection range is the second preset distance range. In a feasible embodiment, the first preset distance range and the second preset distance range can be the three lens field of view ranges of the re-judgment camera.

[0050] In addition, in the scenario where the detection result is yes, for the infrared image acquisition of other areas on the wafer other than the crack, the same method of controlling the re-judgment camera to collect infrared images starting from the edge of the wafer to the inside of the wafer can be used. In this process, the running trajectory and running speed of the re-judgment camera can be set in sections. As a feasible implementation method, the re-judgment camera can be controlled to move slowly along the preset wafer edge running trajectory (such as a running speed of 10-20 mm / s), while collecting infrared images of the bottom layer of the wafer edge. For the inside of the wafer, the re-judgment camera can be controlled to pass quickly (such as a running speed of 30-50 mm / s), while collecting infrared images of the bottom layer inside the wafer to increase the detection speed and avoid unnecessary detection. The above control process for the re-judgment camera can be implemented based on a programmable logic controller or a servo drive system. At the same time, the re-judgment camera can be controlled to use different exposure times and photo frequencies to match different running speeds.

[0051] In the above embodiment, by controlling the re-judgment camera to collect the infrared image of the bottom layer of the wafer according to the detection results, and by setting the running trajectory and running speed of the re-judgment camera in segments, the efficiency can be significantly improved while ensuring the detection accuracy.

[0052] At step S304, cracks in the bottom layer of the wafer are detected based on the infrared image. In some embodiments, the infrared image used by the re-judgment camera is mainly used to detect cracks in the bottom layer of the wafer. Specifically, the infrared image can be denoised using Gaussian filtering or median filtering, and then a specific detection algorithm or deep learning neural network can be used to detect whether there are cracks in the infrared image. In a feasible implementation, the white light image of the main inspection camera and the infrared image of the re-judgment camera can be compared and calculated to achieve high-precision detection of bottom layer cracks. Reference Figure 6 and Figure 7 , Figure 6 is the real detection image of the main detection camera, Figure 7 The dark strip area pointed by the arrow is the bottom crack of the wafer detected in the same area. Figure 6 The image shown in the figure shows that the real image captured by the main inspection camera cannot show the cracks on the bottom layer of the wafer. Figure 7 The infrared image of the same area shown clearly shows the cracks in the bottom layer of the wafer.

[0053] In the above embodiment, the re-inspection camera can effectively detect deep cracks in the wafer while performing non-destructive inspection on the wafer, thereby making up for the deficiency that the main inspection camera can only inspect the surface of the wafer.

[0054] The present application also discloses a computer-readable storage medium, in which program instructions are stored, and the program instructions are suitable for being loaded and executed by a processor: controlling the main inspection camera to collect a white light image of the surface of the wafer; detecting whether there is a crack on the surface of the wafer according to the white light image and outputting the detection result; according to the detection result, controlling the re-judgment camera to collect an infrared image of the bottom layer of the wafer; detecting cracks in the bottom layer of the wafer according to the infrared image. Based on this, when the scheme of the present application is embodied in the form of a software product (computer-readable storage medium), the software product can be stored in a memory, which may include several instructions to enable a computer device (such as a personal computer, a server or a network device, etc.) to perform some or all steps of the method described in the embodiment of the present application. The aforementioned memory may include, but is not limited to, various media that can store program codes, such as a USB flash drive, a flash drive, a read-only memory 10ROM, a random access memory ("Random Access Memory", abbreviated as RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0055] Although multiple embodiments of the present application have been shown and described herein, it is obvious to those skilled in the art that such embodiments are provided only by way of example. Those skilled in the art can think of many changes, modifications and alternatives without departing from the thought and spirit of the present application. It should be understood that in the process of practicing the present application, various alternatives to the embodiments of the present application described herein can be adopted. The attached claims are intended to limit the scope of protection of the present application, and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A system for detecting wafer cracks, characterized in that: include: A main inspection camera, used for collecting white light images of the wafer surface to detect cracks on the wafer surface; A re-inspection camera is used to collect an infrared image within a first preset distance range from the end of the crack to the inside of the wafer at a position where the main inspection camera detects a crack on the surface of the wafer, so as to detect whether there is a crack on the bottom layer of the wafer; Alternatively, when the main inspection camera detects that there are no cracks on the surface of the wafer, an infrared image is collected within a second preset distance range from the edge of the wafer to the inside of the wafer to detect whether there are cracks on the bottom layer of the wafer.

2. The system according to claim 1, characterized in that The main inspection camera includes: an objective lens, a turret, a focusing device, an illumination device and a detection camera; The objective lens is arranged below the turret and is used to magnify the surface of the wafer; The turret is arranged below the detection camera and is used to switch the objective lens; The focusing device and the lighting device are arranged beside the detection camera, the focusing device is used to assist the detection camera in focusing, and the lighting device is used to provide a white light source for the detection camera; The detection camera is arranged above the turret and is used to capture the light reflected or scattered by the surface of the wafer to form the white light image.

3. The system according to claim 1, characterized in that The re-judgment camera comprises: an infrared camera, an infrared lens tube, an infrared objective lens, and an infrared light source; The infrared camera is arranged above the infrared lens barrel and is used to capture infrared images; One end of the infrared lens barrel is connected to the infrared camera, and the other end is connected to the infrared objective lens, so as to provide an optical path for the infrared light; The infrared objective lens is arranged below the infrared lens barrel and is used to focus infrared light; The infrared light source is used to provide infrared light for the infrared camera.

4. The system according to claim 1, characterized in that The main inspection camera is used to detect cracks on the edge surface of the wafer.

5. The system according to claim 4, characterized in that It also includes a main control unit for controlling the main inspection camera to detect cracks on the edge surface of the wafer, and for controlling the re-inspection camera to detect cracks in the bottom layer of the wafer according to the detection results of the main inspection camera.

6. The system according to claim 1, characterized in that The first preset distance range and the second preset distance range are three lens field of view ranges of the re-judgment camera.

7. A method for detecting wafer cracks, characterized in that: include: Control the main inspection camera to collect white light images of the wafer surface; Detecting whether there are cracks on the surface of the wafer according to the white light image and outputting a detection result; According to the detection result, controlling the re-judgment camera to collect an infrared image of the bottom layer of the wafer; Detecting cracks in the bottom layer of the wafer according to the infrared image; wherein, according to the detection result, controlling the re-judgment camera to collect the infrared image of the bottom layer of the wafer comprises: If the detection result is yes, controlling the re-judgment camera to collect an infrared image within a first preset distance range from the end of the crack to the inside of the wafer at the location of the crack; If the detection result is no, the re-judgment camera is controlled to collect infrared images within a second preset distance range from the edge of the wafer to the inside of the wafer.

8. A computer-readable storage medium, characterized in that: The computer readable storage medium stores computer program instructions for detecting wafer cracks. When the computer program instructions are executed by a processor, the method according to claim 7 is implemented.

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