Wafer internal flaw detection system

Abstract

The utility model relates to a wafer internal flaw detection system, and the system comprises a bearing unit which is used for bearing a wafer to be detected, and the wafer is equally divided into a plurality of layers from top to bottom; the flaw capturing unit is used for simultaneously capturing flaws in the wafers of different depth layers; the image generation unit is used for simultaneously generating wafer internal flaw images from the wafer internal flaws of different depth layers captured by the flaw capturing unit; and the analysis unit is used for processing the internal defect images of the wafers of different depth layers generated by the image generation unit to obtain an internal defect distribution diagram of the wafers. According to the detection system disclosed by the invention, flaws of different depth layers of the wafer can be imaged at the same time, the distribution of flaws in the wafer can be efficiently and conveniently detected, Z-direction scanning of the wafer is avoided, the detection time is greatly shortened, and the detection efficiency is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of wafer defect detection, and in particular to a wafer internal defect detection system. Background Art

[0002] A wafer is a silicon chip used to make silicon semiconductor integrated circuits. It is a carrier used to produce integrated circuits (ICs). Various circuit component structures can be processed and manufactured on this carrier to make them into IC products with specific electrical functions.

[0003] With the rapid development of the semiconductor industry, the production process of semiconductors has become more and more complex, the size of chip circuit units has become smaller and smaller, and wafers are more prone to various defects during the production process. Common defects include surface redundancy, crystal defects and mechanical damage that occur during a series of processes such as cutting, etching and chemical grinding. Since the quality of wafers has a direct impact on the performance and reliability of semiconductor chips, its defect detection is extremely important in the semiconductor industry.

[0004] CN202311783499.3 discloses a method and device for detecting carbon inclusions in semiconductor substrates. The solution uses a microscope lens to capture the sample to be detected irradiated with red light according to the best focus position of the multi-layer image, and carbon inclusions of different depths and sizes can be captured. Then, the carbon inclusions in the captured target image are captured, achieving the purpose of accurately identifying carbon inclusions.

[0005] Although the above scheme can detect the inside of the semiconductor substrate, the method adopted requires scanning and imaging the sample layer by layer in the Z direction and X / Y direction. The detection is time-consuming and requires a large amount of data to be processed. Utility Model Content

[0006] The purpose of the present invention is to simultaneously detect the inside of a wafer at different depths to improve wafer detection efficiency.

[0007] To achieve the above objectives, the present disclosure adopts the following technical solutions:

[0008] A wafer internal defect detection system is provided, comprising:

[0009] A carrying unit, used for carrying a wafer to be inspected, wherein the wafer is equally divided into several layers from top to bottom;

[0010] Defect capture unit, used to capture internal defects of wafers at different depth layers simultaneously;

[0011] An image generating unit, used for simultaneously generating wafer internal defect images from the wafer internal defects at different depth layers captured by the defect capturing unit;

[0012] The analyzing unit processes the wafer internal defect images at different depth layers generated by the image generating unit to obtain an internal defect distribution map of the wafer.

[0013] Preferably, the image generation unit comprises a beam splitting module and an imaging module, and the imaging module comprises imaging channels having the same number as the number of layers of the wafer;

[0014] The beam splitting module splits the internal defects of the wafer at different depth layers captured by the defect capturing unit into different imaging channels for imaging, and the imaging module simultaneously generates images of the internal defects of the wafer at corresponding depth layers.

[0015] Preferably, the imaging module includes at least 3 imaging channels, each channel includes an imager, the wafer is divided into layers equal to the number of the imagers from top to bottom, and each of the imagers is used to generate an internal defect image of the wafer at one of the depth layers.

[0016] More preferably, the defect capture unit comprises a microscope coupled to a tube lens;

[0017] The beam splitting module includes the tube lens and a beam splitter, wherein the tube lens is coupled to the beam splitter;

[0018] The imager is coupled to the beam splitter, and the beam splitter splits the internal defect images of the wafer at different depth layers into different imagers for imaging.

[0019] Preferably, the imager comprises a CCD camera.

[0020] The technical solution claimed in the present disclosure has achieved the following beneficial effects:

[0021] The detection system disclosed in the present invention can simultaneously image defects in different depth layers of the wafer, efficiently and conveniently detect the distribution of defects inside the wafer, avoid scanning the wafer in the Z direction, greatly reduce the detection time, and improve the detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are merely embodiments of the present disclosure, and a person of ordinary skill in the art can obtain other drawings based on the provided drawings without paying any creative work.

[0023] Figure 1 Schematic diagram of the wafer internal defect detection system module.

[0024] Figure 2 This is the schematic diagram of the wafer internal defect detection system.

[0025] Figure 3 Schematic diagram of the changing relationship between the microscope working distance and the imager imaging distance.

[0026] Figure 4 This is a trend chart of defect imaging at different depths inside the wafer.

[0027] Figure 5 Schematic diagram of performing "S"-shaped scanning on the wafer in the X / Y direction.

[0028] Figure 6 This is the defect distribution map inside the wafer.

[0029] Reference numerals:

[0030] 1- detection platform; 2- microscope objective lens; 3- tube lens; 4- beam splitter; 5- imager. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and beneficial effects of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0032] Example 1

[0033] Reference Figure 1 and attached Figure 2 This embodiment provides a wafer internal defect detection system, the system comprising:

[0034] The carrying unit is used to carry the wafer to be tested. The wafer is divided into several layers from top to bottom;

[0035] Defect capture unit, used to capture internal defects of wafers at different depth layers simultaneously;

[0036] An image generating unit, used for simultaneously generating an internal defect image of the wafer from internal defects of the wafer at different depth layers captured by the defect capturing unit;

[0037] The analysis unit processes the wafer internal defect images of different depth layers generated by the image generation unit to obtain the internal defect distribution map of the wafer. In the scheme of this embodiment, the analysis unit is an image processing system on a computer, and any existing image processing system for processing wafer defect images can be selected for image analysis, which will not be described in detail.

[0038] In a preferred embodiment, the image generation unit includes a beam splitting module and an imaging module, and the imaging module includes imaging channels of the same number as the number of wafer layers. The beam splitting module splits the internal defects of the wafer at different depth layers captured by the defect capture unit into different imaging channels for imaging, and the imaging module is used to simultaneously generate images of internal defects of the wafer at the corresponding depth layers.

[0039] In a more preferred embodiment, the imaging module includes at least three imaging channels, each channel includes an imager, and the imager can be exemplarily a CCD camera or any device capable of achieving the same function. The wafer is divided into layers equal to the number of imagers from top to bottom, and each imager is used to generate an image of internal defects of the wafer at one of the depth layers.

[0040] In the exemplary results, the defect capture unit includes a microscope, which is coupled to a tube lens; the beam splitting module includes a tube lens and a beam splitter, which is coupled to the tube lens and the beam splitter; the imager is coupled to the beam splitter, and the beam splitter splits the internal defect images of the wafer at different depth layers into different imagers for imaging.

[0041] In the scheme of this embodiment, defects in different depth layers of the wafer can be imaged simultaneously, and the internal defect distribution of the wafer can be detected efficiently and conveniently, avoiding scanning the wafer in the Z direction, greatly reducing the detection time, and improving the detection efficiency.

[0042] Example 2

[0043] This embodiment provides a wafer internal defect detection method performed in the wafer internal defect detection system of Embodiment 1.

[0044] The method in this embodiment comprises the following steps:

[0045] Divide the wafer to be inspected into several layers from top to bottom;

[0046] Simultaneously capture and generate images of wafer internal defects at different depth levels;

[0047] The internal defect images of the wafer at different depth layers are processed to obtain the internal defect distribution map of the wafer.

[0048] In a preferred embodiment, this embodiment simultaneously captures internal defects of the wafer at different depth layers through a microscope, respectively splits the internal defects of the wafer at different depth layers to corresponding imagers for imaging, and simultaneously obtains images of internal defects of the wafer at different depth layers.

[0049] In a more preferred embodiment, the method in this embodiment specifically includes the following steps:

[0050] S1. Divide the wafer into corresponding layers from top to bottom according to the number of imagers;

[0051] S2. Adjust the working distance of the microscope so that the preset working distance of the microscope falls on one layer of the wafer, and calculate the microscope working distances of the remaining layers of the wafer;

[0052] S3. Calculate the imaging distance of each layer of the wafer in the corresponding imager, and adjust the position of the imager according to the imaging distance;

[0053] S4. Using a microscope to simultaneously capture defects at different depth layers of horizontal coordinate points of the wafer, and using an imager to generate images of defects inside the wafer in order of depth layers;

[0054] S5. Analyze the changing trend of the defect image inside the wafer, extract the characteristics of the defects, and obtain the number and depth distribution of the defects at the coordinate points;

[0055] S6. Process the obtained number of defects and three-dimensional coordinates to obtain a distribution diagram of the number of internal defects and three-dimensional coordinates of the wafer.

[0056] In the preferred embodiment, the imaging distance is calculated according to the following formula:

[0057]

[0058] Where D is the imaging distance of the imager, WD is the working distance of the microscope, L is the distance between the microscope and the tube lens, Φ CCD is the size of the imager, Φ TL is the entrance pupil diameter of the tube lens, and NA is the numerical aperture of the microscope.

[0059] In a more preferred embodiment, the microscope scans the wafer horizontally in an S-shaped path.

[0060] This embodiment is based on multi-channel imaging. A microscope objective is equipped with multiple imagers to simultaneously image defects at different depths inside the wafer, thereby achieving efficient and convenient detection of defect distribution inside the wafer.

[0061] Application Example 1

[0062] The technical solution in the above embodiment is further described below in conjunction with specific application examples.

[0063] Attached Figure 2 This is a schematic diagram of a wafer internal defect detection device in this application example, including: a detection platform 1, a microscope objective lens 2, a tube lens 3, a beam splitter 4, and an imager 5.

[0064] The detection platform 1 is used to carry the wafer to be tested, and a microscope objective lens 2 is arranged above it. The microscope objective lens 2 is coupled with a tube lens 3 to capture internal defects of the wafer to be tested. The tube lens 3 is coupled with a beam splitter 4, and the beam splitter 4 splits the internal defects of the wafer at different depth layers captured by the microscope objective lens 2 to the corresponding imager 5 for imaging.

[0065] In this application example, the imager 5 can be set as a CCD camera, and five CCD cameras can be set as an example, respectively recorded as CCD1, CCD2, CCD3, CCD4, and CCD5. However, the number of imagers 5 is not limited to 5, and the number can be designed according to actual conditions, but cannot be less than 3.

[0066] The process of wafer internal defect detection in this application example is as follows:

[0067] Step 1: Place a wafer with known thickness on the detection platform 1, and divide its thickness into corresponding layers according to the number of CCDs in the imager 5. In this application example, the thickness of the wafer is divided into 5 layers, which are recorded as Layer 1, Layer 2, Layer 3, Layer 4, and Layer 5 from top to bottom.

[0068] Step 2: Adjust the distance between the microscope objective lens 2 and the upper surface of the wafer to be measured so that the preset working distance of the microscope objective lens 2 falls within Layer 3, and calculate the working distances WD corresponding to the remaining layers. The working distance between the microscope objective lens 2 and the wafer to be measured can also be adjusted to fall within layers at different depths, and does not need to always be located in the middle layer.

[0069] Step 3: Based on the formula Calculate the imaging distance of CCD1-5 corresponding to Layer1-5 in imager 5.

[0070] Where D is the imaging distance of the imager, WD is the working distance of the microscope, L is the distance between the microscope and the tube lens, Φ CCD is the imager size, Φ TL is the diameter of the tube lens entrance pupil, and NA is the numerical aperture of the microscope.

[0071] As attached Figure 3 As shown, when the actual working distance of the microscope objective lens deviates from the designed working distance, the imaging distance of the imager changes accordingly.

[0072] Step 4: According to the imaging distance D obtained in step 3, the position of the CCD in each imaging channel is adjusted in turn.

[0073] Step 5: Adjust the microscope objective 2 to the scanning starting point, and simultaneously image the different depth layers of the horizontal coordinate points of the wafer to be tested, and obtain the images of Layer 1-5 in depth order. Analyze the image change trend, extract the characteristics of the defects, and obtain the number and depth distribution of the defects at the coordinates.

[0074] Among them, as attached Figure 4 As shown in the trend, the defect is located in the layer corresponding to the clearest image.

[0075] If there are multiple defects at different depths at the same horizontal coordinate, their distribution trends are as shown in the attached figure. Figure 4 As shown in trend 4, the imaging result includes multiple superpositions of clear images and blurred images, and the defect is located in the layer corresponding to the clear image. Figure 4 In the figure, there is a defect in Layer 2 in Trend 1, a defect in Layer 3 in Trend 2, a defect in Layer 5 in Trend 3, and two defects in Trend 4, one in Layer 2 and one in Layer 5.

[0076] Step 6: Follow the instructions as shown in the attached Figure 5 The "S"-shaped path shown is used to scan the wafer to be tested in the horizontal direction, image the entire wafer to be tested, record the number and depth of defects corresponding to each horizontal coordinate, and obtain the number and three-dimensional coordinate distribution of defects in the entire wafer to be tested.

[0077] Step 7: Process the number and three-dimensional coordinates of the defects obtained to obtain the distribution map of the defects inside the wafer to be tested (refer to the attached Figure 6 ).

[0078] During inspection, the microscope inspects the inside of the wafer at multiple depth layers at the same time. Defects are clearly imaged only on the imager of the corresponding layer. The depth position of the defect is determined by analyzing the imaging trend at different depths, and the number and distribution of defects inside the entire wafer can be obtained by scanning only in the X / Y direction.

[0079] The embodiments and application examples described above are merely illustrative descriptions of the present disclosure and are not intended to limit the scope of the present disclosure. Without departing from the design spirit of the present disclosure, various modifications and improvements made to the technical solutions of the present disclosure by ordinary technicians in this field should all fall within the protection scope determined by the present disclosure.

Claims

1. A wafer internal defect detection system, characterized in that: include: A carrying unit, used for carrying a wafer to be inspected, wherein the wafer is equally divided into several layers from top to bottom; Defect capture unit, used to capture internal defects of wafers at different depth layers simultaneously; An image generating unit, used for simultaneously generating wafer internal defect images from the wafer internal defects at different depth layers captured by the defect capturing unit; The analyzing unit processes the wafer internal defect images at different depth layers generated by the image generating unit to obtain an internal defect distribution map of the wafer.

2. The wafer internal defect detection system according to claim 1, characterized in that: The image generation unit includes a beam splitting module and an imaging module, and the imaging module includes imaging channels having the same number as the number of layers of the wafer; The beam splitting module splits the internal defects of the wafer at different depth layers captured by the defect capturing unit into different imaging channels for imaging, and the imaging module simultaneously generates images of the internal defects of the wafer at corresponding depth layers.

3. The wafer internal defect detection system according to claim 2, characterized in that: The imaging module includes at least three imaging channels, each channel includes an imager, the wafer is divided into layers from top to bottom equal to the number of the imagers, and each of the imagers is used to generate an internal defect image of the wafer at one of the depth layers.

4. The wafer internal defect detection system according to claim 3, characterized in that: The defect capture unit includes a microscope coupled to a tube lens; The beam splitting module includes the tube lens and a beam splitter, wherein the tube lens is coupled to the beam splitter; The imager is coupled to the beam splitter, and the beam splitter splits the internal defect images of the wafer at different depth layers into different imagers for imaging.

5. The wafer internal defect detection system according to claim 4, characterized in that: The imager includes a CCD camera.

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