Defect detection system

Abstract

The invention discloses an inspection system for detecting defects, comprising an imaging device (100) configured for imaging a substrate (108), having at least one camera unit (102a, 102b) configured for capturing an image of the substrate (108), at least one light source for generating a coherent light beam to illuminate the substrate (108); and one or more lens units arranged along an optical path of the camera units (102a, 102b) to provide a focus range for imaging the substrate (108), the lens units having a first lens (104a) fixed to at least one of the camera units (102a, 102b) configured with a first focus range for imaging the substrate (108); and a second lens (104b) fixed to the at least one camera unit (102a, 102b) configured with a second focus range for imaging the substrate (108) and constituent layers, a processor (200) configured to extract first defect data and second defect data from image data generated by the substrate (108) and constituent layers thereof, and an analysis module (300) configured to analyze the defect data, the analysis module (300) comprises a defect localization sub-module (300a) for analyzing the first defect data and the second defect data to generate a defect data set comprising defect localization information of the substrate (108) and its constituent layers.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors. More specifically, the present invention relates to an inspection system for detecting defects in a complementary metal oxide semiconductor (CMOS) image sensor (CIS). Background Art

[0002] CMOS sensors are essential components for a variety of technological applications, including digital cameras, smartphones, and medical imaging devices. Ensuring the perfect operation and manufacturing of CMOS sensors is critical to providing a high-quality imaging and data acquisition experience. CMOS sensors are prone to defects such as pixel defects, dust particles, and scratches. These defects can degrade image quality and reduce the performance of the device. Traditional inspection methods for CMOS sensors typically rely on manual inspection or limited automated systems. However, these methods may overlook subtle defects or fail to provide real-time feedback during the manufacturing process. Therefore, there is an urgent need for an advanced inspection system that can comprehensively and efficiently detect CMOS sensor defects.

[0003] A Chinese patent application, publication number: CN114565558A, discloses a method and system for detecting surface defects of CMOS chips. The method includes segmenting image data into smaller detection blocks, binarizing each block, and extracting defects based on the binarization results. The defects are then analyzed based on their pixels and size to determine their effectiveness. Other steps include performing edge finding, positioning adjustment, and secondary binarization to improve accuracy. The system includes image acquisition, segmentation, defect extraction, and defect analysis modules.

[0004] Another Chinese patent, publication number: CN109357687A, discloses a defect detection method for a CMOS image sensor, including the following steps: obtaining a gray card image, preprocessing it into a grayscale image, performing data shift processing on the data values ​​to obtain a low-bit image, calculating the standard deviation of the differential image, and comparing it with a preset threshold. If the standard deviation exceeds the threshold, it indicates that there is a defect in the low bit of the CMOS image sensor chip. The method includes consideration of different image formats, color conversion, and specific shifting techniques.

[0005] Another Chinese patent, publication number: CN212410030U, discloses an image sensor surface defect detection device, including a fixed support, a first lifting mechanism, a lifting seat, a camera module, a coaxial side light source, and a parallel light source module. The first lifting mechanism lifts the lifting seat and the camera module. The camera module is equipped with coaxial and side light sources to capture image information of the image sensor. The parallel light source module surrounds the camera module. The device is capable of detecting surface defects on the image sensor by combining the lifting mechanism, the camera module, and various light sources.

[0006] Current inspection systems are primarily focused on identifying defects located on the outer surfaces of CMOS image sensors (i.e., upper and lower layers). However, it encounters significant limitations when it comes to effectively detecting defects present within the complex layers of CMOS image sensors, commonly referred to as "interlayer defects." These interlayer defects are a critical issue in semiconductor manufacturing as they can severely impact the overall functionality, performance, and reliability of the final CMOS image sensor. However, existing inspection systems lack the ability to identify and accurately locate these hidden defects, which poses a huge challenge to quality control and assurance in the semiconductor industry. Summary of the invention

[0007] The object of the present invention is to develop an inspection system capable of detecting interlayer defects of a CMOS image sensor (CIS). The inspection system can be configured to detect defects such as particles on a glass layer, particles under a glass layer, and surface defects. The inspection system includes an imaging device having at least one camera unit coupled to various lenses of different magnifications. One or more light sources are positioned coaxially with the lens and the camera unit. The first camera unit is configured with a standard magnification lens to capture overall defects on the CIS unit. After capturing the image by the first imaging device, the CIS unit moves to a second camera unit configured with a high magnification lens. Advantageously, the configuration of two camera units with variable focal length lenses enables the camera unit to focus on a specific layer of the CIS unit, thereby enabling the system to accurately determine the location and level of interlayer defects.

[0008] In one aspect of the present invention, a detection system for detecting defects is provided, comprising: an imaging device configured to image a substrate, having at least one camera unit, the camera unit being configured to capture an image of the substrate; at least one light source for generating a beam of coherent light for illuminating the substrate, and one or more lens units arranged along the optical path of the camera unit to provide a focal range for imaging the substrate, the lens unit having a first lens fixed to at least one camera unit, the first lens being configured with a first focal range for imaging the substrate; a second lens fixed to at least one camera unit, being configured with a second focal range for imaging a constituent layer of the substrate; a processor configured to extract first defect data and second defect data therefrom. Image data is generated for the substrate and its constituent layers, and an analysis module configured to analyze the defect data. The analysis module comprises a defect location submodule for analyzing the first defect data and the second defect data to generate a defect data set including defect location information of the substrate and its constituent layers.

[0009] Preferably, the first defect data and the second defect data include defect information of the substrate and its constituent layers.

[0010] Preferably, the first focusing range is larger than a second focusing range used for imaging the substrate and its constituent layers.

[0011] Preferably, one or more light sources are located between the lens unit and the substrate, and at least one light source is disposed transversely to a body of at least one lens unit.

[0012] Preferably, the inspection system further comprises a database for recording one or more data sets including image data, defect data and cohesive defect data sets.

[0013] Preferably, the inspection system further comprises an output module having a user interface configured to display defect location information.

[0014] In another aspect of the present invention, a method for detecting defects by an inspection system is provided, comprising the following steps: imaging a substrate by an imaging device, the imaging device having at least one camera unit configured to capture an image of the substrate, at least one light source for generating a coherent light beam to illuminate the substrate, and one or more lens units arranged along the optical path of the camera unit to provide a focal range for imaging the substrate, the lens unit having a first lens fixed to at least one camera unit, the first lens configured with a first focal range for imaging the substrate, and a second lens fixed to at least one camera unit, the second lens configured with a second focal range for imaging a component layer of the substrate, processing by a processor to extract first defect data and second defect data from the generated image data, and performing defect data analysis on the substrate and its component layers by an analysis module. The analysis module includes a defect location submodule for analyzing the first defect data and the second defect data to generate a defect data set including defect location information of the substrate and its component layers.

[0015] Preferably, the method further comprises the step of conveying the substrate between camera units by a conveyor belt for imaging.

[0016] Preferably, the method further comprises the step of storing one or more data sets including the image data, the defect data and the cohesive defect data set on a database.

[0017] Preferably, the method further comprises the step of displaying the defect location information of the substrate and its constituent layers via an output module, wherein the output module comprises a user interface for displaying said information. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 An example of a detection system according to an embodiment of the present invention is shown.

[0019] Figure 2 A block diagram of a detection system according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0020] Below, the present invention will be described according to the preferred embodiments of the present invention and with reference to the accompanying drawings. However, it should be understood that the description is limited to the preferred embodiments of the present invention only for the convenience of discussing the present invention, and it is foreseeable that those skilled in the art can design various modifications without departing from the scope of the appended claims.

[0021] Figure 1 An example of an inspection system according to an embodiment of the present invention is shown. The inspection system of the present invention includes an imaging device 100, which is configured to capture an image of a substrate 108. Preferably, the substrate 108 to be imaged is a complementary metal oxide semiconductor (CMOS) imaging sensor or any multi-layer imaging sensor, such as but not limited to a charge coupled device (CCD), a backside illumination sensor (BIS), a backside illumination sensor (BSI), and a stacked CMOS sensor. The imaging device 100 includes at least one camera unit 102a, 102b, which is configured to capture an image of the substrate 108; at least one light source for generating a coherent light beam to illuminate the substrate 108; and one or more lens units arranged along the optical path of the substrate 108. The camera units 102a, 102b provide a focal range for imaging the substrate 108.

[0022] Preferably, the camera units 102a, 102b are fixedly integrated into a robot and positioned vertically above the substrate 108 for capturing images of the substrate 108. Alternatively, at least one of the camera units 102a, 102b is integrated into a robot configured with different degrees of freedom for capturing images of the substrate 108 at different angles. Preferably, the camera unit 102a, 102b detectors are CCD or photodiode detectors.

[0023] The light source can be any type of coherent light source, such as but not limited to a laser, LED, or arc lamp. It is worth noting that the light source is coherent so that the light beams will be in phase with each other. Preferably, one or more light sources are located between the lens unit and the substrate 108, such as Figure 1 As shown in the light sources 106c and 106d. Figure 1 As shown, multiple light sources may be coaxially arranged along the optical paths of camera units 102a, 102b for illuminating substrate 108, wherein light source 106b is directly above light source 106d. Figure 1106a is disposed at the periphery of the lens unit. In alternative embodiments, the light source may be offset to one side of the substrate 108, positioned transversely to the optical path of the camera units 102a, 102b for illuminating the substrate 108. Optimally, the light source for various embodiments is positioned proximate to the substrate 108 for uniform illumination. Preferably, one or more lens units are positioned directly above the substrate 108 for focusing the generated coherent light beam onto the substrate 108.

[0024] The lens unit includes a first lens 104a fixed to at least one of the camera units 102a, 102b and a second lens 104b fixed to at least one of the camera units 102a, 102b, the first lens 104a being configured with a first focal range for imaging the substrate 108. A second focal range is configured for imaging the constituent layers of the substrate 108, wherein the first focal range is greater than the second focal range for imaging the substrate 108 and its constituent layers. The first lens 104a is configured to image the overall defects and defect locations on the substrate 108 and its constituent layers, and the second lens 104b is configured to image the defects on the constituent layers of the substrate 108. By way of example, the first lens 104a is a standard magnifying lens, which may include a plurality of converging lenses arranged in series away from each other, and thus has a larger focal range for imaging the substrate 108 with a wider depth of field. In contrast, the second lens 104b is a high power lens, which may include a plurality of converging lenses arranged in series closely adjacent to each other, and thus has a shorter focus range for imaging the substrate 108 with a narrow depth of field. Preferably, the wider depth of field of the first lens 104a is coupled to the camera unit 102a for capturing images including overall defects on the substrate 108, while the narrower depth of field of the second lens 104b is coupled to the camera unit 102b and is configured to capture images of constituent layers of the substrate 108 including defects on the constituent layers.

[0025] The inspection system also includes a processor 200 having an image processing submodule 200a, which is configured to process the raw image obtained via the imaging device 100 by adopting a computing algorithm to generate image data of the substrate 108 and its constituent layers. Optimally, the processor 200 performs initial adjustments before processing the raw image, such as correcting any lens distortion, removing sensor noise, and aligning the image. The processor 200 is configured to extract first defect data and second defect data from the image data generated for the substrate 108 and its constituent layers, wherein the first defect data and the second defect data include defect information of the substrate 108 and its constituent layers. For example, the first defect data includes overall defect information of the substrate 108, and the second defect data includes defect information of the constituent layers of the substrate 108. Preferably, the processor 200 includes a defect detection submodule 200b for identifying a specific region of interest within the image to extract the first and second defect data.

[0026] The inspection system also includes an analysis module 300 configured to analyze defect data, wherein the analysis module 300 includes a defect location submodule 300a for analyzing the first defect data and the second defect data to generate a defect data set including defect location information of the substrate 108 and its constituent layers. The analysis module 300 identifies common features of the first defect data and the second defect data to generate the defect data set. In a preferred embodiment, the common features include, but are not limited to, the size, shape, and location of the defect captured by the imaging device 100. The first defect data includes the location of the defect and its related properties on the top and bottom surfaces of the substrate 108 and the constituent layers of the substrate 108. The second defect data includes the location of the defect and its related properties on the constituent layers of the substrate 108. The analysis module 300 analyzes the data of the defect location on the surface and constituent layers of the reference substrate 108 as the common features for determining the location of the defect on the substrate 108. More specifically, the defect data set enables the inspection system to discern and accurately pinpoint the location of the defect on the constituent layers of the substrate 108.

[0027] The inspection system also includes a database 400 for recording data on one or more data sets including image data, defect data, and defect data sets. The database 400 can be a local memory, such as but not limited to a hard disk drive (HDD), a built-in memory chip, a solid-state drive (SSD), a secure digital (SD) card, etc. The data can also be wirelessly stored on a cloud server accessible by an electronic device (such as but not limited to a computer, a mobile device, etc.). In addition, the database 400 can also store program files related to the application software of the inspection system, which program files can include input parameters related to the inspection of the substrate 108. The processor 200 can be configured to execute software instructions or computer logic instructions based on the application software: used to start the inspection of the substrate 108.

[0028] The defect location information stored on the database 400 can be visually presented by an output module 500 having a user interface. Preferably, the user interface is a platform integrated into the inspection system, which may include a touch screen or a display controllable by a human machine interface (HMI) for registering input to communicate with the inspection system. An image of the substrate 108 indicating the location of the defect on the component layer can be visually presented on the display, and further allowing the user to zoom in on the image to facilitate marking or indicating the defect.

[0029] The following is a description of a method for detecting defects by a detection system. It should be understood that the steps described are non-limiting and that those skilled in the art are allowed to make minor modifications to the steps, i.e., add, omit or exchange, without substantially deviating from the description.

[0030] The method starts with a step of loading a substrate 108 into a detection system. Next, the method performs the following steps: conveying the substrate 108 by a conveyor 110 to be imaged by an imaging device 100, the imaging device 100 having at least one camera unit 102a, 102b configured to capture an image of the substrate 108, at least one light source for generating coherent light, a light beam for illuminating the substrate 108, and one or more lens units arranged along the light path of the camera units 102a, 102b to provide a focus range for imaging the substrate 108, the lens units having a first lens 104a fixed to at least one camera unit 102a, configured with a first focus range for imaging the substrate 108, and a second lens 104b fixed to at least one of the camera units 102a, 102b, configured with a second focus range for imaging a constituent layer of the substrate 108.

[0031] The conveyor 110 first conveys the substrate 108 for first imaging under the camera unit 102a fixed with the first lens 104a, which is configured with a wide depth of field to capture an image of an overall defect on the substrate 108. After the camera unit 102a detects a defect, the method proceeds to the following steps: conveying the substrate 108 under the camera unit 102b fixed with the second lens 104b for second imaging, which is configured with a narrow depth of field to capture an image of a defect of a constituent layer.

[0032] Subsequently, the method proceeds to the step of processing by the processor 200 to generate image data of the substrate 108 and its constituent layers by the image processing submodule 200a. Thereafter, the processor 200 proceeds to the step of extracting first defect data and second defect data from the image data generated for the substrate 108 and its constituent layers via the defect detection submodule 200b.

[0033] Next is the step of analyzing the defect data by the analysis module 300, wherein the analysis module 300 includes a defect location submodule 300a for analyzing the first defect data and the second defect data to generate a defect data set including defect location information of the substrate 108 and its component layers. The defect location information includes the exact location of the defect on the component layer of the substrate 108.

[0034] Thereafter, the method continues with the following steps: storing one or more data sets including image data, defect data and defect data set on the database 400. Finally, the step of displaying defect localization information of the substrate 108 and its constituent layers via the output module 500, wherein the output module 500 includes a user interface for displaying the information.

[0035] In the context of the present application, it should be clearly recognized that terms such as "upper", "lower" or similar expressions are used only for the purpose of facilitating the description of the present invention and concise descriptive content, and these terms express directional or positional references based on the illustrations provided in the relevant drawings. These terms are not intended to stipulate or infer that the devices or components they refer to are inherently limited to any particular orientation, or that they must be specifically conceived, constructed or used in this manner. Therefore, it must be emphasized that the use of such terms does not impose any limitation on the scope and applicability of the present application.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0037] The present disclosure includes the contents contained in the appended claims and the foregoing description. Although the present invention has been described in some detail in its preferred form, it should be understood that the disclosure of the preferred form of the present invention is only by way of example, and that various changes in construction details and the combination and arrangement of parts may be adopted without departing from the scope of the present invention.

Claims

1. A detection system for detecting defects, comprising: An imaging device (100) is configured to image a substrate (108) and has at least one camera unit (102a, 102b), the camera unit (102a, 102b) being configured to capture an image of a substrate (108); at least one light source for generating a light beam for illuminating a substrate (108); and One or more lens units arranged along the optical path of the camera units (102a, 102b) to provide a focal range for imaging the substrate (108), the lens units having a first lens (104a), secured to at least one of the camera units (102a, 102b), configured with a first focal range for imaging the substrate (108); and a second lens (104b), fixed to at least one of the camera units (102a, 102b), configured with a second focal range for imaging the constituent layers of the substrate (108); A processor (200) configured to extract first defect data and second defect data from image data generated of the substrate (108) and its constituent layers; and An analysis module (300), configured to analyze the defect data; The analysis module (300) includes a defect location submodule (300a) for analyzing the first defect data and the second defect data to generate a defect data set including defect location information of the substrate (108) and its component layers.

2. The detection system according to claim 1, characterized in that: The first defect data and the second defect data include defect information of the substrate (108) and its constituent layers.

3. The detection system according to claim 1 or 2, characterized in that: The first focusing range is larger than the second focusing range and is used to image the substrate (108) and its constituent layers.

4. The detection system according to any one of claims 1 to 3, characterized in that: One or more light sources are positioned between the lens unit and the substrate (108), and at least one light source is positioned transverse to a body of at least one lens unit.

5. A detection system according to any one of the preceding claims, characterized in that Also included is a database (400) for recording one or more data sets, including image data, defect data, and defect data sets.

6. A detection system according to any one of the preceding claims, characterized in that Also included is an output module (500) having a user interface, wherein the user interface is configured to display the defect location information.

7. A method for detecting defects using a detection system, comprising the following steps: The substrate (108) is imaged by an imaging device (100), wherein the imaging device (100) has at least one camera unit (102a, 102b) configured to capture an image of a substrate (108); at least one light source for generating a light beam for illuminating a substrate (108); and One or more lens units arranged along the optical path of the camera units (102a, 102b) to provide a focal range for imaging the substrate (108), the lens units having a first lens (104a), secured to at least one of the camera units (102a, 102b), configured with a first focal range for imaging the substrate (108); and a second lens (104b), fixed to at least one of the camera units (102a, 102b), configured with a second focal range for imaging the constituent layers of the substrate (108); Processed by a processor (200) to extract first defect data and second defect data from image data generated from the substrate (108) and its constituent layers; and Analyzing defect data by an analysis module (300); The analysis module (300) includes a defect location submodule (300a) for analyzing the first defect data and the second defect data to generate a defect data set including defect location information of the substrate (108) and its component layers.

8. The method according to claim 7, characterized in that Also included is the step of conveying the substrate (108) between the camera units (102a, 102b) via a conveyor (110) for imaging.

9. The method according to claim 7 or 8, characterized in that: The method also includes the step of storing one or more data sets including the image data, defect data and defect data set on a database (400).

10. The method according to any one of claims 7 to 9, characterized in that The method also includes a step of displaying defect information of the substrate (108) and its constituent layers through an output module (500), wherein the output module (500) includes a user interface for displaying the information.

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