Wafer detection system and method

Abstract

The wafer detection system comprises a light source module, an optical detection module, a sample transmission and positioning module and a data processing and analysis module: the light source module adopts a mode of combining a deep ultraviolet laser source and an LED light source and is provided with a beam shaping module; the optical detection module comprises a differential interference part, a light-induced generation part and a spectrum detection part, and relates to the technical field of semiconductor manufacturing. According to the wafer detection system and method, through cooperative work of the photoluminescence light path, the differential interference light path and the spectrum detection light path, surface defects of tiny scratches and roughness changes on the surface of the wafer can be detected, and subsurface defects of internal cracks and impurity gathering areas can be recognized; meanwhile, the types and properties of the defects are further confirmed in combination with spectral analysis, all-directional coverage of the defects of the wafer is achieved, and the problem that the detection range is limited in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, specifically to a wafer inspection system and method. Background Technology

[0002] The reference patent title is: Automated Inspection System and Control Method for Wafer Chips (Authorization Announcement No.: CN117367329A, Authorization Announcement Date: 2024.01.09). The system includes a workbench with an inspection area at its center. This inspection area includes an inspection mechanism for inspecting wafer products and a wafer edge finding mechanism. Two opposite corners of the workbench are a wafer loading area and a wafer unloading area, while the other two opposite corners are a first robotic arm fixing area and a second robotic arm fixing area. Wafer stacking boxes are fixed in both the wafer loading and unloading areas. A loading robotic arm is fixed in the first robotic arm fixing area, and a unloading robotic arm is fixed in the second robotic arm fixing area. The advantages of this invention are: significant savings in wafer loading and unloading time; automatic and precise wafer loading and unloading; uninterrupted operation; shortened testing time; reduced risk of wafer breakage and edge chipping; rapid measurement; resolution of interference issues during wafer retrieval; and reduced risk of wafer contamination during transfer.

[0003] Based on the aforementioned documents: common wafer inspection technologies each have their advantages and disadvantages. Bright-field inspection, based on the principles of optical reflection and scattering, can effectively detect macroscopic defects on the wafer surface, such as larger particles and obvious scratches, and is suitable for inspection after the early stages of wafer manufacturing. However, it lacks sensitivity to minute defects. Dark-field inspection mainly collects scattered light generated by defects and can detect minute defects; however, its inspection system is complex in terms of illumination and imaging optical system design and requires extremely high equipment precision. While electron microscopy can achieve high-resolution imaging and detect nanoscale defects, the equipment cost is high, and the detection... Existing detection methods are slow and cannot meet the rapid inspection needs of large-scale production. X-ray inspection can be used to analyze internal and surface defects of wafers, and is especially suitable for the detection of three-dimensional structures and internal defects. However, the equipment is large and the operation is complex, and there are radiation safety issues. Laser scanning and surface profilometers also have certain limitations, such as limited detection range and poor detection effect for specific types of defects. In addition, existing detection methods often cannot simultaneously detect surface defects and subsurface defects, resulting in incomplete detection results and inability to accurately control wafer quality. Therefore, this invention provides a wafer inspection system and method. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a wafer inspection system and method that solves the problems of insufficient inspection accuracy, limited inspection range, and inability to simultaneously detect surface and subsurface defects in existing technologies.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a wafer inspection system, comprising: a light source module, an optical inspection module, a sample transfer and positioning module, and a data processing and analysis module.

[0006] The light source module adopts a combination of deep ultraviolet laser source and LED light source, and is equipped with a beam shaping module;

[0007] The optical detection module includes a differential interference section, a photoluminescence section, and a spectral detection section. The photoluminescence section, together with a laser, a detection camera, and some elements of the differential interference section, forms a photoluminescence optical path. The spectral detection section, together with an LED light source, some elements of the differential interference section, and a spectrometer, forms a spectral detection optical path.

[0008] The sample transfer and positioning module includes a high-precision wafer carrier stage and a vision positioning system;

[0009] The data processing and analysis module uses a high-performance computer and has built-in detection data analysis software.

[0010] Preferably, the differential interference section consists of a polarizer and a Wollaston prism. The light emitted by the LED light source is converted into linearly polarized light by the polarizer, and then split into two mutually perpendicular linearly polarized beams by the Wollaston prism. After passing through the wafer surface, the beams pass through the Wollaston prism and the polarizer again, and the two beams interfere to form interference fringes, which are received by the detection camera to form the first image.

[0011] Preferably, the optical elements in the photoluminescence generation unit collect and guide the photoluminescence signal generated by the wafer being irradiated by a laser, so that the photoluminescence signal enters the detection camera to form a second image, and subsurface defects are detected by analyzing the intensity, position and spectral characteristics of the photoluminescence in the second image.

[0012] Preferably, the optical elements in the spectral detection unit collect and spectrally disperse the LED light after passing through the wafer, and introduce light of different wavelengths into the spectrometer, which performs spectral analysis on the light to extract defect spectral information.

[0013] Preferably, the wafer carrier stage enables precise movement and rotation of the wafer in the X, Y, and Z directions, and is made of highly stable materials with vibration isolation properties; the visual positioning system monitors the wafer position and orientation in real time through multiple high-resolution cameras and feeds the feedback to the control system to adjust the position of the carrier stage.

[0014] This invention also discloses a method for inspecting wafers, comprising the following steps:

[0015] S1. Inspection Preparation: Place the wafer on the wafer carrier stage, position it using the vision positioning system, adjust the parameters of the light source module, calibrate the optical inspection module, start the data processing and analysis module and load the preset parameters and defect spectrum library;

[0016] S2. Surface Defect Detection: The LED light source is turned on to form a differential interference optical path, the detection camera acquires the first image and transmits it to the data processing and analysis module to analyze and identify surface defects.

[0017] S3, Subsurface Defect Detection: Turn off the LED light source, turn on the laser to form a photoluminescence optical path, the detection camera acquires the second image and transmits it to the data processing and analysis module to analyze and identify subsurface defects;

[0018] S4. Spectral Analysis: Turn on the LED light source. The light after passing through the wafer enters the spectrometer through the spectral detection unit. The spectral data is transmitted to the data processing and analysis module and compared with the defect spectral library to confirm the defect type and nature.

[0019] S5. Data Integration and Report Generation: Integrate test data, evaluate wafer quality, and generate test reports.

[0020] Preferably, the data processing and analysis module in S2 processes the first image through image enhancement, edge detection, and feature extraction algorithms, and identifies the type, location, and size of surface defects based on interference fringe deformation and abnormal brightness areas.

[0021] Preferably, the data processing and analysis module in S3 analyzes the intensity distribution, location, and spectral characteristics of photoluminescence in the second image, identifies subsurface defects using a specific algorithm, and classifies, records, and statistically analyzes them according to preset rules.

[0022] Beneficial effects

[0023] This invention provides a wafer inspection system and method. Compared with the prior art, it has the following advantages:

[0024] Beneficial effects:

[0025] 1. This wafer inspection system and method utilizes the coordinated operation of three channels: photoluminescence optical path, differential interference optical path, and spectral detection optical path. It can detect surface defects such as minute scratches and roughness variations on the wafer surface, as well as identify subsurface defects such as internal cracks and impurity accumulation areas. Furthermore, it combines spectral analysis to further confirm the defect type and nature, achieving comprehensive coverage of wafer defects and solving the problem of limited detection range in existing technologies.

[0026] 2. The wafer inspection system and method adopts a deep ultraviolet laser source. With its short wavelength and high energy characteristics, combined with advanced optical inspection module design and high-performance data processing algorithm, it has extremely high sensitivity to nanoscale defects. It can accurately extract key information such as the shape, size, location, and spectral characteristics of defects, meet the stringent requirements of semiconductor manufacturing for high-precision inspection, and provide a reliable basis for chip quality control.

[0027] 3. This wafer inspection system and method ensures rapid and accurate inspection of all areas of the wafer through a fast sample transfer and positioning module. The high-performance data processing and analysis module can process and analyze data in real time and perform defect classification statistics to generate an inspection report containing detailed information. This not only meets the online inspection needs in large-scale production and improves inspection efficiency, but also provides strong data support for wafer quality assessment and process improvement, which helps to improve chip manufacturing yield and reduce production costs. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the comprehensive testing process of this invention.

[0029] Figure 2 This is a flowchart illustrating the high sensitivity and high precision implementation process of the present invention.

[0030] Figure 3 This is a flowchart illustrating the efficient detection and accurate evaluation process of this invention.

[0031] Figure 4 This is a flowchart illustrating the overall system logic of the present invention.

[0032] Figure 5 This is a flowchart illustrating the operation of the wafer inspection method of the present invention.

[0033] In the diagram: 1-Light source module, 2-Optical detection module, 3-Sample transfer and positioning module, 4-Data processing and analysis module. Detailed Implementation

[0034] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Please see Figure 1-5 This invention provides two technical solutions:

[0036] Example 1: Detection of scratches on the surface of wafers

[0037] S1. Preparation: Select a wafer that may have surface scratches and place it on the wafer carrier stage. Use the vision positioning system to accurately position the wafer and ensure that it is in the center of the detection optical path. Turn on the light source module, set the power of the DUV laser source to 10mW, the wavelength to 248nm, and the brightness of the LED light source to 500lux. Calibrate the optical detection module to ensure that the position and angle of each optical element are accurate. Start the data processing and analysis module and load the preset detection parameters and defect spectrum library.

[0038] S2. Surface Defect Detection: The LED light source is turned on to form a differential interference optical path. The detection camera acquires interference images of the wafer surface and transmits them to the data processing and analysis module. The software processes the images and identifies abnormal deformation areas of multiple interference fringes through an edge detection algorithm. After feature extraction and analysis, these areas are determined to be surface scratches. Based on the position and size information of the scratches in the image, the actual position and length of the scratches on the wafer surface are calculated. The detection shows that there are 3 scratches on the wafer surface, with lengths of 20μm, 35μm and 15μm respectively.

[0039] S3. Subsurface Defect Detection and Spectral Analysis: With the LED light source off and the laser on, subsurface defect detection was performed. The detection camera did not detect any obvious abnormal photoluminescence signal, indicating that no subsurface defects were found on the wafer under the detection conditions. Subsequently, spectral analysis was performed. After comparing the spectral data obtained by the spectrometer with the defect spectral library, no characteristic spectral peaks related to known defects were found, further verifying that the wafer had no obvious subsurface defects or other impurity-related defects.

[0040] S4. Generate Inspection Report: The data processing and analysis module integrates the surface defect inspection results and generates an inspection report. The report records in detail the wafer number, inspection time, inspection equipment information, and the number, location, and length of surface scratches, and gives the quality assessment conclusion that "the wafer has surface scratch defects and needs further processing or assessment of its impact on subsequent processes."

[0041] Example 2: Detection of Impurity Aggregation Inside Wafers

[0042] S1. Preparation: Select a wafer suspected of having internal impurity accumulation, repeat the preparation steps in Example 1, and ensure that the detection system is in optimal working condition.

[0043] S2. Surface defect detection: Surface defect detection was performed according to the method in Example 1. The data processing and analysis module did not detect any obvious surface defects, and the interference image showed that the microstructure of the wafer surface was normal.

[0044] S3. Subsurface Defect Detection: The laser is turned on, the photoluminescence optical path is working, and the detection camera captures multiple abnormal photoluminescence bright spots in the image. The data processing and analysis module analyzes the intensity, distribution and spectral characteristics of these bright spots to determine that these areas are internal impurity accumulation areas. Based on the intensity and distribution of the photoluminescence signal, the size and depth range of the impurity accumulation area are initially estimated. After detection, five impurity accumulation areas were found inside the wafer, with the largest area having a diameter of about 50 μm and a depth of about 10 μm.

[0045] S4. Spectral Analysis: Spectral analysis is performed. Characteristic spectral peaks related to specific impurities appear in the spectral data acquired by the spectrometer. By comparing with the defect spectral library, the impurity type is determined to be silicide. The data processing and analysis module combines the spectral analysis results with the subsurface defect detection results to further clarify the nature and characteristics of the impurity accumulation region.

[0046] S5. Generate Inspection Report: The data processing and analysis module generates an inspection report, which records in detail the relevant information of the wafer, the number, location, size, depth and type of subsurface impurity aggregation regions, and the quality assessment conclusion that "the wafer has internal impurity aggregation defects, which may have an adverse effect on chip performance and requires further evaluation and treatment."

[0047] As can be seen from the above embodiments, the wafer inspection system and method can effectively detect various defects in wafers, including surface scratches and subsurface impurity accumulation. The inspection results are accurate and reliable, and have good practicality and application prospects.

[0048] Furthermore, any content not described in detail in this specification is existing technology known to those skilled in the art.

[0049] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A wafer inspection system, characterized in that, include: The light source module (1), optical detection module (2), sample transfer and positioning module (3), and data processing and analysis module (4) are: The light source module (1) adopts a combination of deep ultraviolet laser source and LED light source, and is equipped with a beam shaping module; The optical detection module (2) includes a differential interference section, a photoluminescence section and a spectral detection section. The photoluminescence section, together with a laser, a detection camera and some elements of the differential interference section, forms a photoluminescence optical path. The spectral detection section, together with an LED light source, some elements of the differential interference section and a spectrometer, forms a spectral detection optical path. The sample transfer and positioning module (3) includes a high-precision wafer carrier stage and a vision positioning system; The data processing and analysis module (4) uses a high-performance computer and has built-in detection data analysis software.

2. The wafer inspection system according to claim 1, characterized in that: The differential interference section consists of a polarizer and a Wollaston prism. The light emitted by the LED light source is converted into linearly polarized light by the polarizer, and then split into two mutually perpendicular linearly polarized beams by the Wollaston prism. After passing through the wafer surface, the beams pass through the Wollaston prism and polarizer again, and the two beams interfere to form interference fringes, which are received by the detection camera to form the first image.

3. The wafer inspection system according to claim 1, characterized in that: The optical elements in the photoluminescence generator collect and guide the photoluminescence signal generated by the laser irradiation of the wafer, so that the photoluminescence signal enters the detection camera to form a second image. Subsurface defects are detected by analyzing the intensity, position and spectral characteristics of the photoluminescence in the second image.

4. The wafer inspection system according to claim 1, characterized in that: The optical elements in the spectral detection unit collect and disperse the LED light after it passes through the wafer, and introduce light of different wavelengths into the spectrometer. The spectrometer performs spectral analysis on the light to extract defect spectral information.

5. The wafer inspection system according to claim 1, characterized in that: The wafer carrier stage enables precise movement and rotation of the wafer in the X, Y, and Z directions, and is made of highly stable materials with vibration isolation properties. The visual positioning system monitors the wafer position and orientation in real time through multiple high-resolution cameras and feeds the feedback to the control system to adjust the position of the carrier stage.

6. The wafer inspection method according to claims 1-5, characterized in that, Includes the following steps: S1. Inspection preparation: Place the wafer on the wafer carrier stage, position it using the vision positioning system, adjust the parameters of the light source module (1), calibrate the optical inspection module (2), start the data processing and analysis module (4) and load the preset parameters and defect spectrum library; S2, Surface Defect Detection: Turn on the LED light source to form a differential interference optical path, the detection camera acquires the first image and transmits it to the data processing and analysis module (4) to analyze and identify surface defects; S3, Subsurface Defect Detection: Turn off the LED light source, turn on the laser to form a photoluminescence path, and the detection camera acquires the second image and transmits it to the data processing and analysis module (4) to analyze and identify subsurface defects; S4. Spectral analysis: Turn on the LED light source. The light after passing through the wafer enters the spectrometer through the spectral detection unit. The spectral data is transmitted to the data processing and analysis module (4) and compared with the defect spectral library to confirm the defect type and properties. S5. Data Integration and Report Generation: Integrate test data, evaluate wafer quality, and generate test reports.

7. The wafer inspection method according to claim 6, characterized in that: The data processing and analysis module (4) in S2 processes the first image through image enhancement, edge detection, and feature extraction algorithms, and identifies the type, location, and size of surface defects based on interference fringe deformation and abnormal brightness areas.

8. The wafer inspection method according to claim 6, characterized in that: The data processing and analysis module (4) in S3 analyzes the intensity distribution, location and spectral characteristics of photoluminescence in the second image, uses a specific algorithm to identify subsurface defects, and classifies, records and counts them according to preset rules.

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