Wafer Defect Detection Method, System and Terminal Device

Abstract

The present application discloses a wafer defect detection method, system and terminal device. The method includes: obtaining a plurality of first signals of a target wafer moving along a target motion trajectory, where one first signal corresponds to one sampling point in the target motion trajectory, and the time interval between the sampling times of every two adjacent sampling points is the same; obtaining the motion parameters of the target wafer when passing through each sampling point to calculate the spatial interval between every two adjacent sampling points; performing equi-spatial interval sampling on the plurality of first signals to obtain a plurality of second signals, and the spatial interval between the two sampling points corresponding to every two adjacent sampled second signals is the target spatial interval; generating a signal envelope based on the plurality of second signals to perform a preliminary defect check on the target wafer and adjusting the power of the laser based on the result of the preliminary defect check. The wafer defect detection has high accuracy, the laser power adjustment has high precision, and it has strong applicability.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular, to a wafer defect detection method, system, and terminal device. Background Art

[0002] Wafer semiconductor detection technology plays an important role in semiconductor production, packaging, testing, and other processes. Among them, the defect detection of wafers is the key in semiconductor detection technology. Before the defect detection of wafers, pre-inspection of wafer defects can improve the imaging effect of wafer images. During the pre-inspection of wafer defects, a signal envelope for indicating information such as the defect size and shape of the wafer can be generated by detecting the light intensity of the light spot formed by the detection laser irradiating on the wafer. If the characteristics such as the defect size and shape indicated by the signal envelope do not match the laser power, it will affect the illumination effect of the laser, and further affect the imaging effect of the wafer image, resulting in misdetection or missed detection in the wafer defect detection based on the wafer image.

[0003] In order to improve the accuracy of wafer defect pre-inspection, the laser power modulation (LPM) in the patternless wafer detection device can be used to pre-inspect wafer defects based on a spiral scan trajectory and adjust the laser power based on the wafer defect pre-inspection result. Among them, LPM generates an electrical signal by detecting the light intensity of the laser spot, and then converts the electrical signal into a light intensity digital signal to generate a signal envelope based on the light intensity digital signal, and further obtains information such as the defect size and shape based on the signal envelope. It is determined whether there are defects on the wafer by judging whether the curvature change of the signal envelope exceeds a threshold, and the signal fitting peak is extracted at the moment when the curvature exceeds the threshold to judge the defect size, so as to adjust the light spot intensity generated by the laser irradiating the wafer based on the defect size so that the defective part of the wafer can be completely imaged. However, in order to improve the wafer production rate, the moving stage in the patternless wafer detection device often has a change in moving speed during the scanning of the wafer. At this time, the widths of the signal envelopes generated based on the sampled digital signals are also inconsistent, and the curvature error formed by the width error of the signal envelope results in a low pre-inspection accuracy of the defect size. Therefore, based on the pre-inspection result, it is not possible to well adapt to the wafer defect detection scenario with a change in moving speed during the wafer scanning process, the applicability is poor, and the accuracy of laser power adjustment is poor. Summary of the Invention

[0004] The present application provides a wafer defect detection method, system, and terminal device, which can improve the pre-inspection accuracy of wafer defects, improve the accuracy of laser power adjustment, and enhance the applicability.

[0005] First aspect, the present application provides a method for detecting wafer defects. The method includes: obtaining a plurality of first signals of a target wafer, where the first signals are digital light intensity signals obtained by sampling the light intensity signals of the target wafer moving along a target motion trajectory under laser illumination. One of the first signals corresponds to one sampling point in the target motion trajectory, and the time interval between the sampling times corresponding to every two adjacent sampling points in the target motion trajectory is the same; obtaining the motion parameters of the target wafer when passing through each of the sampling points during the movement along the target motion trajectory, and calculating the spatial interval between every two adjacent sampling points based on the motion parameters; performing equidistant spatial sampling on the plurality of first signals corresponding to the plurality of sampling points to obtain a plurality of second signals, where the spatial interval between the two sampling points corresponding to every two adjacent samplings of the two second signals is a target spatial interval; generating a signal envelope based on the plurality of second signals, and performing preliminary defect detection on the target wafer based on the signal envelope to adjust the power of the laser based on the result of the preliminary defect detection.

[0006] By using the present application, equidistant spatial sampling of sampling points can be performed on the first signals, ensuring that the number of sampling points within the defect ranges of two wafers of the same size is the same, thereby reducing the topographic error of the signal envelope generated based on the sampled second signals. Therefore, the detection accuracy of the preliminary wafer defect detection based on the signal envelope can be improved, the accuracy of adjusting the laser power based on the result of the preliminary wafer defect detection can be enhanced, and the applicability can be strengthened.

[0007] In a possible implementation manner of the first aspect, the obtaining of the plurality of first signals of the target wafer includes: obtaining the plurality of first signals generated by an analog-to-digital converter performing analog-to-digital conversion on a plurality of first light intensity analog signals; the time interval between the sampling times of every two adjacent sampling points is obtained from the device parameters of the analog-to-digital converter. By using the present application, the terminal device can implement sampling of digital light intensity signals at equal time intervals through the analog-to-digital converter, and can obtain the first light intensity analog signals from the photomultiplier tube at equal time intervals and perform analog-to-digital conversion to generate the first signals. Digital signals are processed faster and have stronger anti-interference ability than analog signals. Therefore, the detection accuracy and detection speed of the preliminary wafer defect detection can be further improved, and the applicability is strong.

[0008] In a possible implementation of the first aspect, the above-mentioned motion parameters include the above-mentioned sampling moments and the motion speed; obtaining the motion parameters of the target wafer when passing through each of the above-mentioned sampling points during the process of moving based on the above-mentioned target motion trajectory, and calculating the spatial interval between every two adjacent above-mentioned sampling points based on the above-mentioned motion parameters, includes: obtaining, through a motion controller, the above-mentioned sampling moments and the motion speed of the target wafer when passing through each of the above-mentioned sampling points during the process of moving based on the above-mentioned target motion trajectory; obtaining the time interval between two adjacent above-mentioned sampling points based on the sampling moments of the two adjacent above-mentioned sampling points, and calculating the spatial interval between the two adjacent above-mentioned sampling points based on the above-mentioned time interval and the above-mentioned motion speed. By using the present application, the terminal device can control the moving stage to carry the target wafer to move through the motion controller and obtain the sampling moments and the motion speed of the target wafer when passing through the sampling points in real time, and then can calculate the spatial interval between two adjacent sampling points, with strong real-time performance and more accurate data acquisition. Therefore, the detection accuracy and detection speed of pre-inspection of wafer defects can be further improved, and the applicability is strong.

[0009] In a possible implementation of the first aspect, the above-mentioned motion speed includes the linear speed; calculating the spatial interval between two adjacent above-mentioned sampling points based on the above-mentioned time interval and the above-mentioned motion speed includes: when the target wafer moves at a constant linear speed, calculating the spatial interval between two adjacent above-mentioned sampling points based on the product of the above-mentioned linear speed and the above-mentioned time interval. By using the present application, it can be applicable to the situation where the target wafer moves at a constant linear speed. The terminal device can calculate the spatial interval between two adjacent sampling points based on the linear speed and the time interval, with simple calculation and strong applicability.

[0010] In a possible implementation of the first aspect, the above-mentioned motion speed includes the angular speed, and the above-mentioned target motion trajectory includes a spiral trajectory; calculating the spatial interval between two adjacent above-mentioned sampling points based on the above-mentioned time interval and the above-mentioned motion speed includes: when the target wafer moves at a constant angular speed, generating the motion angle of the target wafer based on the product of the above-mentioned angular speed and the above-mentioned time interval; determining the arc length corresponding to the above-mentioned motion angle in the above-mentioned spiral trajectory based on the above-mentioned motion angle, and determining the above-mentioned arc length as the spatial interval between two adjacent above-mentioned sampling points. By using the present application, it can be applicable to the situation where the target wafer moves at a constant angular speed. The terminal device can calculate the motion angle based on the angular speed and the time interval, and then calculate the spatial interval between two adjacent sampling points based on the motion angle, with simple calculation and strong applicability.

[0011] In a possible implementation of the first aspect, the two target sampling points corresponding to the two second signals obtained by every two adjacent samplings are two adjacent target sampling points; the equal-space interval sampling of the multiple first signals corresponding to the multiple sampling points to obtain multiple second signals includes: obtaining the target space interval; traversing the multiple sampling points based on the space interval between every two adjacent sampling points, and selecting multiple target sampling points from the multiple sampling points, wherein the space interval between every two adjacent target sampling points is equal to the target space interval; selecting the first signals corresponding to the respective target sampling points from the multiple first signals as the second signals to obtain the multiple second signals. By using the present application, multiple target sampling points can be determined from multiple sampling points through the target space interval. Since the space interval between every two adjacent target sampling points is the same, it is ensured that the number of sampling points in two wafer defects of the same size is also the same. Furthermore, the accuracy of the signal envelope generated by the second signal can be improved, thereby further improving the detection accuracy of wafer defect pre-inspection based on the signal envelope and the accuracy of adjusting the laser power based on the wafer defect pre-inspection result; in addition, by resampling the multiple first signals, unnecessary data in the first signals can be eliminated, and the interference caused by excessive data can also be reduced. Therefore, the detection speed and detection accuracy of wafer defect prediction can be further improved.

[0012] In a possible implementation of the first aspect, the traversing the multiple sampling points based on the space interval between every two adjacent sampling points and selecting multiple target sampling points from the multiple sampling points includes: determining a reference sampling point from the multiple sampling points, and obtaining the space distance between each sampling point after the reference sampling point and the reference sampling point based on the space interval between every two adjacent sampling points; determining the sampling point closest to the reference sampling point and having a space distance equal to the target space interval from the reference sampling point as an equidistant sampling point, and determining the reference sampling point and the equidistant sampling point as two adjacent target sampling points. By using the present application, the multiple sampling points can be traversed in sequence according to the sampling time order, and the reference sampling point and the equidistant sampling point with the same space distance as the target space interval can be calculated to determine multiple target sampling points, so as to ensure that the space interval between every two adjacent target sampling points is the same, which can further improve the detection accuracy of wafer defect pre-inspection based on the signal envelope and the accuracy of adjusting the laser power based on the wafer defect pre-inspection result, and the calculation process is simple, the calculation speed is fast, and the applicability is strong.

[0013] In a second aspect, the present application provides a wafer defect detection device, which includes a module or unit for executing the wafer defect detection method provided in the first aspect or any possible implementation of the first aspect.

[0014] Exemplarily, the device includes:

[0015] A first acquisition module, configured to acquire a plurality of first signals of a target wafer, where the first signals are digital light intensity signals obtained by sampling the light intensity signals of the target wafer moving along a target motion trajectory under the illumination of a laser. One of the first signals corresponds to one sampling point in the target motion trajectory, and the time interval between the sampling times corresponding to every two adjacent sampling points in the target motion trajectory is the same;

[0016] A second acquisition module, configured to acquire the motion parameters of the target wafer when passing through each of the sampling points during the movement of the target wafer along the target motion trajectory, and calculate the spatial interval between every two adjacent sampling points based on the motion parameters;

[0017] A sampling module, configured to perform equidistant spatial sampling on the plurality of first signals corresponding to the plurality of sampling points to obtain a plurality of second signals, where the spatial interval between the two sampling points corresponding to every two adjacent samplings of the two second signals is a target spatial interval;

[0018] A generation module, configured to generate a signal envelope based on the plurality of second signals, and perform preliminary defect detection on the target wafer based on the signal envelope to adjust the power of the laser based on the result of the preliminary defect detection.

[0019] By adopting the present application, a plurality of first signals of the target wafer can be acquired through the first acquisition module, the spatial interval between every two adjacent sampling points can be calculated through the second acquisition module, the plurality of first signals can be sampled at equidistant spatial intervals through the sampling module to obtain a plurality of second signals, and a signal envelope can be generated based on the plurality of second signals through the generation module to adjust the laser power, which can improve the detection accuracy of the preliminary wafer defect detection, improve the accuracy of adjusting the laser power based on the result of the preliminary wafer defect detection, and has strong applicability.

[0020] In a third aspect, the present application provides a terminal device, including: a transceiver, a memory, and a processor; the memory is configured to store program codes and data, and the processor is configured to call the program codes so that the transceiver and the processor process the data to implement the wafer defect detection method described in the first aspect and any possible implementation manner of the first aspect. By adopting the present application, data can be received and sent through the transceiver, and the wafer defect detection method can be implemented through the cooperation of the processor and the memory, which can improve the detection accuracy of the preliminary wafer defect detection, improve the accuracy of adjusting the laser power based on the result of the preliminary wafer defect detection, and has strong applicability.

[0021] Fourth aspect, the present application provides a wafer defect detection system, and the above system includes: an analog-to-digital converter and a terminal device as described in the second aspect; the above analog-to-digital converter is used to obtain a first light intensity analog signal and perform analog-to-digital conversion on the above first light intensity analog signal to generate the above first signal; wherein, the time interval for the above analog-to-digital converter to obtain the above first light intensity analog signal is obtained from the device parameters of the above analog-to-digital converter. By adopting the present application, sampling and analog-to-digital conversion of the first light intensity analog signal can be realized through the analog-to-digital converter. The analog-to-digital converter is flexibly installed, with fast sampling speed and analog-to-digital conversion speed, and the obtained first signal has strong anti-interference ability and small error. Therefore, the detection accuracy of wafer defect pre-inspection can be improved, the accuracy of adjusting the laser power based on the wafer defect pre-inspection result can be improved, and the applicability is strong.

[0022] In a possible implementation manner of the fourth aspect, the above system further includes a photomultiplier tube; the above photomultiplier tube is used to sample the light intensity of the spot generated by the moving target wafer under laser illumination and transmit the sampled first light intensity analog signal to the above analog-to-digital converter. By adopting the present application, a relatively weak light beam reflected by the target wafer can be received through the photomultiplier tube, and a clear first light intensity analog signal can be generated. Therefore, the detection accuracy of wafer defect pre-inspection can be improved, the accuracy of adjusting the laser power based on the wafer defect pre-inspection result can be improved, and the photomultiplier tube has a small volume, flexible loading, and strong applicability.

[0023] In a possible implementation manner of the fourth aspect, the above system further includes a laser emission device; the above laser emission device is used to emit a laser to provide illumination for the above target wafer. By adopting the present application, a laser can be emitted by the laser emission device to irradiate the target wafer and project a characteristic image on the target wafer for wafer pre-inspection. The projection shape of the laser can be adjusted, and the laser power can be adjusted. Therefore, the applicability is strong.

[0024] Fifth aspect, an embodiment of the present application provides a computer-readable storage medium, and a computer program is stored in the above computer-readable storage medium. The above computer program is adapted to be loaded and executed by a processor to perform the wafer defect detection method provided in the first aspect or any possible implementation manner of the first aspect.

[0025] Sixth aspect, an embodiment of the present application provides a computer program product, and the above computer program product includes computer instructions. The above computer instructions are adapted to be loaded and executed by a processor to perform the wafer defect detection method provided in the first aspect or any possible implementation manner of the first aspect. Description of the Drawings

[0026] Figure 1 is a schematic diagram of the application scenario of the wafer defect detection system provided by the present application;

[0027] Figure 2It is a schematic diagram of the spiral trajectory provided by this application;

[0028] Figure 3 It is a schematic diagram of the light spot provided by this application;

[0029] Figure 4 It is a schematic diagram of the change of the first light intensity analog signal provided by this application;

[0030] Figure 5 It is a schematic diagram of a position of the sampling point provided by this application;

[0031] Figure 6 It is a schematic diagram of the process flow of the wafer defect detection method provided by this application;

[0032] Figure 7 It is a schematic diagram of another position of the sampling point provided by this application;

[0033] Figure 8 It is a schematic diagram of the signal envelope provided by this application;

[0034] Figure 9 It is a schematic diagram of the structure of the wafer defect detection device provided by this application;

[0035] Figure 10 It is a schematic diagram of the structure of the terminal device provided by this application. Detailed implementation manners

[0036] Next, the technical solutions in this application will be described with reference to the accompanying drawings in this application.

[0037] For ease of understanding, some terms are first simply explained as follows:

[0038] 1. Target motion trajectory refers to the trajectory along which the moving stage carries the target wafer. Multiple sampling points can be set on the target motion trajectory. When the moving stage carries the target wafer past the sampling point, the sampling device can sample the target wafer. Among them, the target motion trajectory can be preset in the motion controller used to control the movement of the moving stage to trigger the moving stage to carry the target wafer to move along the specified trajectory. In this application, the target motion trajectory is a spiral trajectory.

[0039] 2. Primary sampling refers to the process of sampling the first light intensity analog signal at equal time intervals and performing analog-to-digital conversion on the first light intensity analog signal to generate the first signal.

[0040] 3. Secondary sampling refers to the process of sampling the first signal based on multiple target sampling points at equal space intervals to obtain the second signal.

[0041] 4. Sampling point: A marked point in the target motion trajectory used to determine the spatial position of a single sampling of the target wafer. It can be recorded by coordinates or by determining the sampling moment. In this application, when the target wafer passes through the sampling point, an analog-to-digital converter can perform a single sampling to obtain a first signal. One sampling point corresponds to one first signal, and the time interval between the sampling moments of every two adjacent sampling points is the same. The above sampling moment is determined by the device parameters of the analog-to-digital converter.

[0042] 5. Target sampling point: A marked point selected from multiple sampling points for secondary sampling of the first signal of the target wafer. In this application, when the target wafer passes through the target sampling point, the terminal device can perform secondary sampling on multiple first signals to obtain multiple second signals. One target sampling point corresponds to one second signal, and the spatial interval between every two adjacent sampling points is the same.

[0043] 6. Signal envelope: A curve reflecting the change of signal intensity over time, intuitively manifested as the contour of the signal waveform. Since the spatial position of the target wafer in this application increases with the increase of the sampling moment, that is, the sampling moment and the spatial position are in a positive correlation relationship. Therefore, to better understand the effect of sampling at equal spatial intervals in this application, the horizontal axis of the signal envelope schematic diagram in this application is replaced from indicating the sampling moment to indicating the spatial position. The convex region in the signal envelope is used to indicate that there may be wafer defects in the spatial position corresponding to the convex region. Therefore, the initial position and the end position of the wafer defect can be determined by analyzing the initial position and the end position of the convex region of the signal envelope. The above convex region can also be called the signal fitting peak. The extraction difference of the signal fitting peak caused by the different signal envelope morphologies and the width inconsistency of the signal envelopes generated by the wafer defects of the same size can affect the calculation accuracy of the wafer defect size.

[0044] 7. Analog-to-digital converter: A device that converts an analog signal into a digital signal. The main function of the analog-to-digital converter is to convert an analog signal with continuous time and continuous amplitude into a digital signal with discrete time and discrete amplitude. The analog-to-digital converter usually includes four processes: sampling, holding, quantization, and encoding. In this application, the target wafer can be sampled once by the analog-to-digital converter. In some feasible embodiments, the analog-to-digital converter can also be used for secondary sampling.

[0045] 8. Defect pre-inspection: An essential part of the wafer defect detection process. By detecting the target wafer to find potential or existing wafer defects, the laser power irradiating the target wafer can be adjusted according to the defect pre-inspection situation, so that the laser power is adapted to the subsequent scanning of the target wafer.

[0046] The wafer defect detection method and the wafer defect detection system provided by this application can be applicable to the application scenario of wafer defect pre-inspection, and can also be applicable to other application scenarios that require the detection of target wafers. Specifically, it can be determined according to the actual application scenario and is not limited here. For the convenience of description, this application takes the application scenario of wafer defect pre-inspection as an example for illustration. In this application scenario, the motion control and defect detection of the wafer can be executed by a working system, and the working system includes, but is not limited to, the wafer defect detection system provided by this application. The wafer defect detection system is used for the pre-inspection of wafer defect detection. Refer to Figure 1 , Figure 1 which is a schematic diagram of the application scenario of the wafer defect detection system provided by this application. In the application scenario as shown in Figure 1 , the working system may include a moving stage, a motion controller, and a wafer defect detection system. Among them, the wafer defect detection system may include a terminal device and an analog-to-digital converter.

[0047] In some feasible implementation manners, as shown in Figure 1 , the target wafer can be carried by the moving stage and move along with the moving stage based on the target motion trajectory. The moving stage can be controlled by the motion controller, and the analog-to-digital converter can obtain the motion parameters of the target wafer (such as sampling time and motion speed, etc.) through the motion controller. The above-mentioned moving stage can be an X / Z / Theta axis moving stage, or other moving stages that can load the target wafer. This application does not limit this and takes the X / Z / Theta axis moving stage as an example for illustration. It can be understood that the moving stage can move on the X axis, Z axis, and Theta axis, corresponding to lateral movement, vertical movement, and rotational angle movement respectively. The moving stage can load the target wafer and adjust the position of the target wafer through motion. Optionally, the moving stage may further include a Y axis moving stage, and the Y axis moving stage can load the target wafer to make the target wafer move longitudinally. The above-mentioned motion controller can be a chip such as a microcontroller unit (MCU), and can generate control instructions to control the movement of the moving stage. The moving stage can move according to the target motion trajectory. The above-mentioned target motion trajectory includes, but is not limited to, a spiral trajectory, a concentric circle trajectory, a square trajectory, a polygon trajectory, and a horizontal and vertical trajectory. For the convenience of description, this application takes the spiral trajectory as an example for illustration. For the convenience of understanding, please refer to Figure 2 , Figure 2 which is a schematic diagram of the spiral trajectory provided by this application. As shown in Figure 2 , the spiral trajectory can be a spiral line, and the spiral trajectory may include multiple sampling points ( Figure 2 only shows some sampling points), and each sampling point can correspond to a motion radius and a sampling time.

[0048] In some feasible implementation manners, as shown in Figure 1As shown, the above working system may further include a laser emission device. The laser emission device can emit laser light to illuminate the target wafer. The laser can be a monochromatic light beam, such as a white light beam, a red light beam, or other light beams. When the laser irradiates the surface of the target wafer, a light spot with a specific shape can be formed, such as a rectangular light spot. For ease of understanding, please refer to Figure 3 , Figure 3 which is a schematic diagram of the light spot provided by this application. As Figure 3 shown, a light spot with a length of h and a width of w can be generated on the surface of the target wafer. Here, h and w are fixed values generated according to the irradiation conditions of the laser. If the irradiation angle, light intensity, and other parameters of the laser are not adjusted, then h and w are fixed values. It should be noted that the power of the laser is controlled by the power of the laser emission device. The laser can be adjusted by adjusting the power of the laser emission device. Among them, the higher the power of the laser emission device, the higher the laser power; the lower the power of the laser emission device, the lower the laser power. Optionally, the laser emission device can be integrated inside the wafer defect detection system or can be set outside the wafer defect detection system, which can be specifically determined according to the form of the product in the actual application scenario and is not limited here. In other words, the wafer defect detection system may include a terminal device and an analog-to-digital converter, and may also include a laser emission device, which can be specifically determined according to the actual product form and is not limited here.

[0049] In some feasible implementation manners, as Figure 1 shown, the above working system may further include a photomultiplier tube. After the laser emitted by the laser emission device irradiates the target wafer, the target wafer can reflect the light beam in the light spot area, and then the light beam is converged to the photomultiplier tube through devices such as lenses to trigger the photomultiplier tube to sample the light intensity of the light spot. The photomultiplier tube can convert the optical signal into an electrical signal. That is to say, the photomultiplier tube can receive the optical signal generated by the light beam reflected by the target wafer in the light spot area under the condition of laser illumination, and then generate a first light intensity analog signal based on the optical signal to sample the light intensity of the light spot. The first light intensity analog signal is an electrical signal and can be used to indicate the light intensity of the light spot. The photomultiplier tube can transmit the first light intensity analog signal to the analog-to-digital converter. It can be understood that the photomultiplier tube can convert a weak optical signal into a clear electrical signal. In the actual application scenario, the photomultiplier tube can also be replaced by other devices that can generate a first light intensity analog signal based on the optical signal reflected by the target wafer, which is not limited in this application. The photomultiplier tube can be integrated inside the wafer defect detection system or can be set outside the wafer defect detection system, which can be specifically determined according to the form of the product in the actual application scenario and is not limited here. In other words, the wafer defect detection system may include a terminal device and an analog-to-digital converter, and may also include a laser emission device and a photomultiplier tube, which can be specifically determined according to the actual product form and is not limited here.

[0050] In some feasible embodiments, the analog-to-digital converter may obtain a plurality of first optical intensity analog signals from a photomultiplier tube to obtain a plurality of first optical intensity analog signals when the target wafer passes through a plurality of sampling points. One first optical intensity analog signal corresponds to one sampling moment, and the time interval between the sampling moments of two adjacent sampling points may be determined by the device parameters of the analog-to-digital converter. For example, the time interval between a plurality of sampling moments may be determined according to the sampling frequency of the analog-to-digital converter, and then a plurality of sampling points may be determined in the target motion trajectory based on the above time interval.

[0051] Please refer to Figure 4 , Figure 4 which is a schematic diagram of the change of the first optical intensity analog signal provided by this application. As Figure 4 shown, the horizontal axis is the sampling moment of the sampling point corresponding to the first optical intensity analog signal, and the vertical axis is the signal intensity of the first optical intensity analog signal. Figure 4 The convex region in the first optical intensity analog signal curve shown in may be used to indicate that there may be a wafer defect within the spatial position corresponding to the convex region. By analyzing the critical value of the convex region, the range of the wafer defect can be determined. For example, by analyzing the sampling moment corresponding to the initial boundary point of the convex region, the sampling point corresponding to the sampling moment can be determined, and then the initial position of the wafer defect can be determined through the sampling point (such as the initial position shown in Figure 4 ); similarly, by analyzing the sampling moment corresponding to the end boundary point of the convex region, the sampling point corresponding to the sampling moment can be determined, and then the end position of the wafer defect can be determined through the sampling point (such as the end position shown in Figure 4 ), therefore, the position and size of the wafer defect can be determined through the initial position and the end position of the wafer defect.

[0052] In some feasible embodiments, the analog-to-digital converter can obtain a first light intensity analog signal when the target wafer moves to the sampling point under the illumination provided by the laser. After obtaining the first light intensity analog signal, the analog-to-digital converter can perform analog-to-digital conversion on the first light intensity analog signal to generate a first signal (which can also be called the first light intensity digital signal), thereby realizing a primary sampling of the light intensity signal of the target wafer (which can be called equal-time-interval sampling). In addition, the analog-to-digital converter can also transmit the first signal to the terminal device to trigger the terminal device to perform secondary sampling on the first signal based on multiple target sampling points at equal spatial intervals (which can be called equal-spatial-interval sampling). Among them, the terminal device can obtain multiple first signals of the target wafer moving along the target motion trajectory. One first signal corresponds to one sampling point in the target motion trajectory, and the time interval between the sampling times corresponding to every two adjacent sampling points is the same. The terminal device can also obtain the motion parameters of the target wafer when passing through each sampling point during the movement along the target motion trajectory. The above motion parameters can include the sampling time and the motion speed, and thus the spatial interval between every two adjacent sampling points can be calculated based on the motion parameters. In addition, the terminal device can also perform equal-spatial-interval sampling on multiple first signals based on multiple sampling points to obtain multiple second signals. Among them, the above equal-spatial-interval sampling is realized based on the spatial positions of the sampling points, and the spatial interval (i.e., the interval of the spatial positions) between the two sampling points corresponding to every two adjacent samplings of the two second signals is the target spatial interval. The terminal device can also generate a signal envelope based on multiple second signals, and then perform defect pre-inspection on the target wafer based on the above signal envelope and adjust the power of the laser based on the results of the defect pre-inspection.

[0053] In some feasible embodiments, the terminal device can obtain a plurality of first signals generated by the analog-to-digital converter (ADC) for performing analog-to-digital conversion on a plurality of first light intensity analog signals. The above-mentioned first light intensity analog signals are obtained by the ADC at equal time intervals from a photomultiplier tube based on a plurality of sampling points in the target motion trajectory, and the time interval between the sampling times of every two adjacent sampling points is obtained from the device parameters of the ADC. The terminal device can obtain the sampling time when the target wafer passes through each sampling point and the motion speed of the target wafer during the motion of the target wafer along the target motion trajectory through the motion controller, and obtain the time interval between two adjacent sampling points based on the sampling times of two adjacent sampling points, and calculate the spatial interval between two adjacent sampling points based on the time interval and the motion speed. For example, the terminal device can obtain the sampling time of the first sampling point (such as 1 microsecond) and the linear velocity of the target wafer when passing through the first sampling point (such as 1 meter per second) through the motion controller. When the terminal device detects that the target wafer passes through the second sampling point, the terminal device can obtain the sampling time of the second sampling point (such as 2 microseconds) and the linear velocity of the target wafer when passing through the second sampling point (such as 1 meter per second), and so on. The terminal device can calculate the difference between the sampling times of the first sampling point and the second sampling point, and obtain that the time interval between the sampling times of the first sampling point and the second sampling point is 1 microsecond. It should be noted that since the time intervals between the sampling times of every two adjacent sampling points among the plurality of sampling points are equal, in actual application scenarios, it is only necessary to calculate the time interval once. Optionally, the time interval of the sampling time may not be calculated, but directly set by the device parameters of the ADC.

[0054] Optionally, in some feasible embodiments, the target wafer can move at a constant linear velocity. At this time, the terminal device can calculate the spatial interval between two adjacent sampling points based on the product of the linear velocity and the time interval. When the motion controller controls the moving stage to move at a constant linear velocity, the motion speed in the motion parameters obtained by the terminal device is the linear velocity. For example, if the terminal device detects that the linear velocity of the target wafer is 1 meter per second during the process of moving from the first sampling point to the second sampling point, and the time interval between the sampling times of the first sampling point and the second sampling point is 1 microsecond, then after calculation, it can be obtained that the spatial interval between the first sampling point and the second sampling point is 1 micrometer.

[0055] Optionally, in some feasible embodiments, the target wafer may also move at a constant angular velocity. At this time, the terminal device can calculate the movement angle of the target wafer based on the product of the angular velocity and the time interval, and then determine the arc length corresponding to the movement angle in the spiral trajectory, and determine the arc length as the spatial interval between two adjacent sampling points. When the motion controller controls the moving stage to move at a constant angular velocity, the motion speed in the motion parameters obtained by the terminal device is the angular velocity. For example, if the terminal device detects that the angular velocity of the target wafer is 360° / second during the process of moving from the second sampling point to the third sampling point, and the time interval between the sampling times of the first sampling point and the second sampling point is 1 microsecond, the movement angle can be calculated to be 0.00036°, and then substituting the movement angle into the arc length calculation formula, the spatial interval between the first sampling point and the second sampling point (such as 1 micron) can be obtained.

[0056] It can be understood that since the motion speed can be detected in real time by the motion controller that controls the movement of the moving stage, and the calculation of the time interval is simple, the terminal device can quickly calculate the spatial interval, with strong real-time performance, more accurate data acquisition, and strong applicability.

[0057] In some feasible embodiments, multiple target sampling points may be included among the multiple sampling points in the target motion trajectory, and the target sampling points are used to perform secondary sampling on the target wafer. In other words, the two sampling points corresponding to the two second signals obtained by the terminal device in every two adjacent samplings are two adjacent target sampling points. Among them, the terminal device can obtain the target spatial interval, and traverse the multiple sampling points based on the spatial interval between every two adjacent sampling points, and then select multiple target sampling points from the multiple sampling points, where the spatial interval between every two adjacent target sampling points is equal to the target spatial interval. It can be understood that the terminal device can determine a reference sampling point from the multiple sampling points. For example, the sampling point with the earliest sampling time can be selected as the reference sampling point according to the sampling time sequence, or the reference sampling point can be determined through a preset selection rule, or a sampling point can be selected as the reference sampling point in other ways, which is not limited in this application. The traversal order can be determined according to the sequence of sampling times, or can be determined in other orders, which is not limited in this application. Taking the terminal device determining the sampling point with the earliest sampling time as the reference sampling point as an example, the terminal device can obtain the spatial distances between each sampling point after the reference sampling point and the target sampling point based on the spatial interval between every two adjacent sampling points. The terminal device can also determine the sampling point closest to the reference sampling point and with a spatial distance equal to the target spatial interval from the reference sampling point as the equidistant sampling point to obtain two adjacent target sampling points, and use the equidistant sampling point as the reference sampling point for determining the next target sampling point to obtain multiple target sampling points. That is to say, the above process of determining the reference sampling point and the equidistant sampling point can be carried out cyclically.

[0058] For example, the terminal device may select a sampling point from multiple sampling points in the target motion trajectory as the reference sampling point. For example, the sampling point with the earliest sampling time in the target motion trajectory may be used as the reference sampling point. For ease of understanding, please also refer to Figure 5 , Figure 5 is a schematic diagram of the position of the sampling point provided by this application. As Figure 5 shown, if the terminal device selects sampling point 1 as the reference sampling point, the coordinate axes indicating the spatial position can be established with sampling point 1 as the origin (the point with coordinates 0) and the positive order direction of the traversal order as the positive direction of the X-axis. The above coordinate axes include the X-axis and the Y-axis, and one unit length is 1 micrometer. Among them, the coordinates of sampling point 1 are (0, 0), the coordinates of sampling point 2 are (1, 0), and the coordinates of sampling point 3 are (2, 0). Then, the spatial interval between sampling point 1 and sampling point 2 can be calculated as 1 micrometer, the spatial interval between sampling point 2 and sampling point 3 is 1 micrometer, and the spatial interval between sampling point 1 and sampling point 3 is 2 micrometers. If the target spatial interval obtained by the terminal device is 2 micrometers, the terminal device can determine sampling point 3, whose spatial interval from the reference sampling point (sampling point 1) is 2 micrometers, as the equidistant sampling point, so as to determine the reference sampling point and the equidistant sampling point as two adjacent target sampling points. The above process of determining the reference sampling point and the equidistant sampling point can be carried out cyclically. The terminal device can use the above sampling point 3 as the reference sampling point in the next process, so as to determine the equidistant sampling point in the next process based on sampling point 3.

[0059] In some feasible embodiments, the terminal device may select the first signals corresponding to each target sampling point from multiple first signals as the second signals to obtain multiple second signals. For example, as Figure 5As shown, sampling point 1 corresponds to the first light intensity digital signal, sampling point 2 corresponds to the second light intensity digital signal, and sampling point 3 corresponds to the third light intensity digital signal. If sampling point 1 is determined as the first target sampling point, then the first light intensity digital signal is selected as the first second signal; if sampling point 3 is determined as the second target sampling point, then the third light intensity digital signal is selected as the second second signal, and so on, until all the first signals corresponding to the target sampling points are selected. It can be understood that the terminal device determines multiple target sampling points from multiple sampling points through the target space interval. Since the space interval between every two adjacent target sampling points is the same, the number of sampling points in two wafer defects of the same size can be guaranteed to be the same, thereby improving the accuracy of the signal envelope generated from the second signal, and further improving the detection accuracy of wafer defect pre-inspection based on the signal envelope and the accuracy of adjusting the laser power based on the wafer defect pre-inspection result; in addition, the resampling of the first signal can eliminate unnecessary data in the first signal and reduce the interference caused by excessive data, so the detection speed and detection accuracy of wafer defect prediction can be further improved.

[0060] In some feasible embodiments, the above wafer defect detection system may further include a filter ( Figure 1 not shown in the figure). The above filter may be a low-pass filter (LPF) or other filters. The filter may be disposed between the photomultiplier tube and the analog-to-digital converter, or may be integrated in the analog-to-digital converter. The present application does not make any restrictions. The filter can eliminate the noise of the first light intensity analog signal, thereby reducing the interference of the noise and improving the accuracy of wafer defect pre-inspection.

[0061] By adopting the present application, multiple first signals with the same sampling point time interval of the target wafer can be obtained through the terminal device in the wafer defect detection system, the motion parameters of the target wafer when passing through each sampling point are obtained, and the space interval between every two adjacent sampling points is calculated based on the motion parameters. Equal-space interval sampling is performed on the multiple first signals corresponding to the multiple sampling points to obtain multiple second signals, a signal envelope is generated based on the multiple second signals, and defect pre-inspection is performed on the target wafer based on the signal envelope to adjust the power of the laser based on the result of the defect pre-inspection; the first light intensity analog signal is obtained through the analog-to-digital converter in the wafer defect detection system and the first signal is generated through analog-to-digital conversion; the light intensity of the spot generated by the moving target wafer under laser illumination is sampled through the photomultiplier tube in the wafer defect detection system to obtain the first light intensity analog signal; the target wafer is irradiated with a laser to generate a spot on the surface of the target wafer to provide illumination for the target wafer. By adopting the present application, the pre-inspection accuracy of wafer defects is high, the accuracy of adjusting the laser power is high, and the applicability is strong.

[0062] The present application also provides a wafer defect detection method, which can improve the pre-inspection accuracy of wafer defects, enhance the adjustment accuracy of laser power, and improve applicability. Refer to Figure 6 , Figure 6 which is a schematic flow chart of the wafer defect detection method provided by the present application. For ease of description, the present application is described by taking the terminal device described in Embodiment 1 as the execution subject. As Figure 6 shown, the above-mentioned wafer defect detection method may include the following steps:

[0063] Step S101, obtaining a plurality of first signals of a target wafer, where the first signals are digital light intensity signals obtained by sampling the light intensity signals of the target wafer moving along a target motion trajectory under the illumination of a laser. Among them, one of the first signals corresponds to one sampling point in the target motion trajectory, and the time intervals between the sampling times corresponding to every two adjacent sampling points in the target motion trajectory are the same.

[0064] In some feasible implementation manners, the terminal device may obtain a plurality of first signals of the target wafer moving along a target motion trajectory under the illumination of a laser. The target motion trajectory may be a spiral trajectory, and the target motion trajectory may include a plurality of sampling points. One sampling point corresponds to one sampling time. The target wafer may be carried by a moving stage and move along with the moving stage. It can be understood that as the motion time of the target wafer (the motion time is indicated by the sampling time) increases, the motion distance of the target wafer along the target motion trajectory also increases. Therefore, the sampling position of the target wafer can be determined by determining the sampling time of the target wafer. The plurality of first signals may be obtained by high-frequency and equidistant sampling. Therefore, among the plurality of sampling points corresponding to the plurality of first signals, the time intervals between the sampling times of every two adjacent sampling points are the same.

[0065] In some feasible implementation manners, the terminal device may obtain a plurality of first signals from an analog-to-digital converter. Among them, the first signal is obtained by the analog-to-digital converter performing analog-to-digital conversion on the first light intensity analog signal, that is, the first signal is obtained by the analog-to-digital converter sampling the target wafer once. The first light intensity analog signal is obtained by the analog-to-digital converter from a photomultiplier tube at equal time intervals based on a plurality of sampling points in the target motion trajectory of the target wafer. The time intervals between the sampling times of every two adjacent sampling points are the same, and the time interval is obtained from the device parameters of the analog-to-digital converter, such as the sampling frequency of the analog-to-digital converter.

[0066] In some feasible embodiments, the first light intensity analog signal can be obtained from the photomultiplier tube by the analog-to-digital converter according to its own sampling frequency. That is to say, the analog-to-digital converter can obtain the first light intensity analog signal from the photomultiplier tube every once in a while. For example, if the sampling frequency of the analog-to-digital converter is 1 microsecond per time (i.e., sampling once every 1 microsecond), the time interval between the sampling times of every two adjacent sampling points in the target motion trajectory can be set to 1 microsecond. Therefore, whenever the target wafer passes through a sampling point, the terminal device can obtain from the analog-to-digital converter the first signal obtained by the analog-to-digital converter through analog-to-digital conversion of the first light intensity analog signal obtained from the photomultiplier tube when the target wafer passes through the sampling point.

[0067] Step S102: Obtain the motion parameters of the target wafer when passing through each of the above sampling points during the movement of the target wafer based on the above target motion trajectory, and calculate the space interval between every two adjacent sampling points based on the above motion parameters.

[0068] In some feasible embodiments, the terminal device can obtain the motion parameters of the target wafer when passing through each sampling point. The above motion parameters can be the motion speed of the target wafer and the sampling time of the sampling point passed through. The terminal device can obtain the motion parameters once every time the target wafer passes through a sampling point, or can obtain the motion parameters every once in a while (for example, obtain the motion parameters once every 1 microsecond). This application does not make any restrictions.

[0069] In some feasible embodiments, the motion parameters of the target wafer when passing through each sampling point during the movement of the target wafer based on the target motion trajectory can include the sampling time of the sampling point and the motion speed of the target wafer. The sampling time of the sampling point can also be regarded as the sampling time of the target wafer. As Figure 1As shown, the target wafer can be loaded on the moving stage. The movement of the target wafer based on the target movement trajectory can be controlled by the moving stage. The terminal device can obtain the sampling time and movement speed of the target wafer when passing through each sampling point during the movement based on the target movement trajectory from the motion controller. Among them, one sampling point corresponds to one sampling time and one movement speed. It should be noted that during the scanning of the spiral trajectory, when the movement radius corresponding to the sampling point reached when the moving stage carries the target wafer in the spiral trajectory is greater than the movement radius threshold, the moving stage can carry the target wafer to move at a constant angular velocity; when the movement radius corresponding to the sampling point reached when the moving stage moves with the target wafer in the spiral trajectory is less than or equal to the movement radius threshold, a constant linear velocity is used, which can reduce the scanning error caused by the too fast linear velocity when scanning the area close to the spiral center from the outside to the inside in the scanning spiral trajectory. Optionally, when the moving stage carries the target wafer to move, it can also first move at a constant angular velocity and then move at a constant linear velocity, and the wafer scanning can be performed from the inside to the outside. Therefore, in this application, the movement speed for calculating the spatial position of the sampling point can be the angular velocity or the linear velocity, which should be determined according to the specific form of the product, and this application does not make any restrictions. The terminal device can calculate the time interval between two adjacent sampling points based on the sampling times of the two adjacent sampling points, and then can calculate the spatial interval between the two adjacent sampling points based on the time interval and the movement speed (angular velocity or linear velocity).

[0070] For example, if the target wafer moves at a constant linear velocity during the process of moving from the first sampling point (i.e., the initial sampling point) to the second sampling point in the target movement trajectory, the terminal device can obtain the linear velocity of the target wafer when passing through the first sampling point (such as 1 m / s) and the linear velocity of the target wafer when passing through the second sampling point (such as 1 m / s) from the motion controller, and then can calculate the spatial interval according to the product of the linear velocity and the time interval between the first sampling point and the second sampling point. If the target wafer moves at a constant angular velocity during the process of moving from the second sampling point to the third sampling point, the terminal device can obtain the angular velocity of the target when passing through the third sampling point (such as 360° / s) from the motion controller, and then can calculate the movement angle based on the angular velocity and the time interval between the second sampling point and the third sampling point, and then calculate the arc length corresponding to the above movement angle according to the arc length calculation formula adapted to the spiral trajectory, and then determine the arc length as the spatial interval between the two adjacent sampling points. For example, if the terminal device detects that the angular velocity of the target wafer is 360° / s and the time interval is 1 μm during the process of moving from the first sampling point to the second sampling point, the movement angle can be calculated to be 0.00036°, and then the spatial interval can be calculated based on the above movement angle and the arc length calculation formula.

[0071] In some feasible embodiments, the terminal device can calculate the time interval between two adjacent sampling points by calculating the difference between the sampling times of two adjacent sampling points. For example, the time interval between the sampling times of the first sampling point and the second sampling point is 1 microsecond, and the time interval between the sampling times of the second sampling point and the third sampling point is also 1 microsecond, and so on. The time interval between the sampling times of every two adjacent sampling points is 1 microsecond. It should be noted that since the time intervals between the sampling times of every two adjacent sampling points among multiple sampling points are equal, in practical application scenarios, it is only necessary to calculate the time interval once. Optionally, the above time interval can also be obtained from the device parameters of the analog-to-digital converter. The above sampling times can also be recorded by other means and the time interval between two adjacent sampling points can be calculated by a calculation method matching the recording method. The calculation method of the time interval described above is only a feasible example provided by this application, and this application does not limit the calculation process of the time interval.

[0072] Step S103: Perform equidistant spatial sampling on the multiple first signals corresponding to the multiple sampling points to obtain multiple second signals, where the spatial interval between the two sampling points corresponding to the two second signals obtained by each adjacent two samplings is the target spatial interval.

[0073] In some feasible embodiments, the terminal device can sample multiple first signals corresponding to multiple sampling points, and then obtain multiple second signals from the first signals based on the spatial positions of the multiple sampling points. Since the second signals are selected from the multiple first signals, the number of the first signals is greater than or equal to the number of the second signals. The terminal device can determine a reference sampling point from the multiple sampling points. For example, by traversing the multiple sampling points in the sampling time order, the sampling point with the earliest sampling time is determined as the reference sampling point, or a sampling point can be determined as the reference sampling point from the multiple sampling points based on a preset selection rule, which is not limited in this application. The terminal device can obtain the spatial distances between each sampling point and the reference sampling point based on the spatial intervals between every two adjacent sampling points among all sampling points. When the terminal device detects, in the traversal order, the first sampling point whose spatial distance from the reference sampling point is equal to the target spatial distance, the sampling point is determined as the equidistant sampling point.

[0074] The above process of determining the reference sampling point and the equally-spaced sampling points can be carried out cyclically. In other words, the determination processes of two adjacent target sampling points can be carried out cyclically. For example, the terminal device can sequentially traverse the above-mentioned multiple sampling points. After determining an equally-spaced sampling point, the equally-spaced sampling point is used as the reference sampling point in the next determination process to determine the equally-spaced sampling point in the next determination process, and so on until multiple target sampling points are determined. Among them, the spatial interval between the reference sampling point and the sampling point adjacent to the reference sampling point is equal to the spatial distance between the reference sampling point and the sampling point adjacent to the reference sampling point.

[0075] For ease of understanding, please also refer to Figure 7 , Figure 7 which is another schematic diagram of the position of the sampling points provided in this application. As Figure 7As shown, assume that the above-mentioned target space interval is 4 microns. The target movement trajectory includes multiple sampling points such as sampling point 1, sampling point 2, sampling point 3, and sampling point 4. The terminal device can mark sampling point 1 as the reference sampling point and establish a coordinate axis based on sampling point 1. Among them, one unit length in the coordinate axis is 1 micron, and the direction from sampling point 1 to sampling point 2 is the positive direction of the X-axis. According to the coordinate axis, the spatial position of sampling point 1 is recorded as (0, 0), then the spatial position of sampling point 2 is recorded as (1, 0), the spatial position of sampling point 3 is recorded as (2, 0), and the spatial position of sampling point 4 is recorded as (4, 0), and so on to mark the spatial positions of multiple sampling points. It can be calculated that the space interval between sampling point 1 and sampling point 2 is 1 micron, and the space interval between sampling point 1 and sampling point 2 is not equal to the target space interval. Therefore, the terminal device calculates the spatial distance between the next sampling point (i.e., sampling point 3) and sampling point 1. It can be calculated that the space interval between sampling point 2 and sampling point 3 is 1 micron, then the spatial distance between sampling point 1 and sampling point 3 is 2 microns. Since the spatial distance between sampling point 1 and sampling point 3 is not equal to the target space interval, the terminal device calculates the spatial distance between the next sampling point (i.e., sampling point 4) and sampling point 1. It can be calculated that the space interval between sampling point 3 and sampling point 4 is 2 microns, then the spatial distance between sampling point 1 and sampling point 4 is 4 microns. Since the spatial distance between sampling point 1 and sampling point 4 is equal to the target space interval, the terminal device can determine sampling point 4 as the equidistant sampling point of sampling point 1, so as to determine sampling point 1 and sampling point 4 as two adjacent target sampling points. Further, the terminal device can determine sampling point 4 as the reference sampling point in the determination process of the next two adjacent target sampling points, and calculate the spatial distance between each sampling point and sampling point 4, so as to determine the equidistant sampling point of sampling point 4 in the next determination process, and so on until all multiple sampling points are traversed. Optionally, when calculating the spatial distance between each sampling point and the reference sampling point, if there are multiple sampling points between the sampling point to be calculated and the reference sampling point, the terminal device can first calculate the space interval between each adjacent two of the multiple sampling points between the sampling point to be calculated and the reference sampling point to obtain multiple space intervals, and then accumulate the multiple space intervals to obtain the spatial distance between the sampling point to be calculated and the reference sampling point. Optionally, the terminal device can also directly calculate the spatial distance according to the spatial positions of each sampling point and the reference sampling point. Due to the different actual product forms, the acquisition methods and marking methods of the spatial positions of the above multiple sampling points are different, and the calculation difficulty is also different. Therefore, it is necessary to determine a suitable calculation method according to the actual product form, and this application does not make any restrictions.

[0076] In some feasible embodiments, the terminal device may select, from multiple first signals, the first signal corresponding to each target sampling point as a second signal based on multiple target sampling points, and thus obtain multiple second signals. For example, as Figure 7 shown, sampling point 1 corresponds to the first first signal (which can be denoted as the first signal 1), sampling point 2 corresponds to the second first signal (which can be denoted as the first signal 2), sampling point 3 corresponds to the third first signal (which can be denoted as the first signal 3), sampling point 4 corresponds to the fourth first signal (which can be denoted as the first signal 4), and so on. If the terminal device determines that sampling point 1 is the first target sampling point, it may select the first signal 1 as the first second signal; if the terminal device determines that sampling point 4 is the second target sampling point, it may select the first signal 4 as the second second signal, and so on, until the first signals corresponding to all target sampling points are selected.

[0077] It should be noted that after the above equal-spatial-interval sampling of multiple first signals, the terminal device can obtain at least three second signals, and the number of the above second signals is less than or equal to the number of first signals. In a feasible embodiment, after the above one-time sampling of the light intensity signal of the target wafer, the terminal device can obtain at least three first signals. If the spatial distance between every two adjacent first signals is the target spatial interval, at least three second signals can be obtained by performing equal-spatial-interval sampling based on at least three first signals. At this time, the number of second signals is the same as the number of first signals. Exemplarily, if the terminal device obtains three first signals (such as the first signal 1, the first signal 2, and the first signal 3), where the spatial position of sampling point 1 corresponding to the first signal 1 is denoted as (0, 0), the spatial position of the sampling point corresponding to the first signal 2 is denoted as (1, 0), and the spatial position of the sampling point corresponding to the first signal 3 is denoted as (2, 0), and the target spatial interval is 1 micrometer, then the spatial distance between the first signal 1 and the first signal 2, and the spatial distance between the first signal 2 and the first signal 3 are both equal to the target spatial interval. Therefore, if the terminal device determines the first signal 1 as the first second signal, it can determine the first signal 2 as the second second signal and the first signal 3 as the third second signal, thereby obtaining three second signals. It can be understood that if, among the multiple first signals obtained by the terminal device, the spatial distance between every two adjacent first signals is the target spatial interval, equal-spatial-interval sampling can be performed based on the multiple first signals to obtain the same number of second signals as the number of first signals.

[0078] In another feasible implementation, if the spatial distances between every two adjacent first signals among the multiple first signals are not all the target spatial intervals, at least four first signals are required for equal-spatial-interval sampling to obtain at least three second signals. At this time, the number of second signals is less than the number of first signals. Exemplarily, the terminal device can obtain four first signals (such as First Signal 1, First Signal 2, First Signal 3, and First Signal 4). Among them, the spatial position of First Signal 1 is denoted as (0, 0), the spatial position of First Signal 2 is denoted as (1, 0), the spatial position of First Signal 3 is denoted as (2, 0), and the spatial position of First Signal 4 is denoted as (4, 0). The target spatial interval is 2 micrometers. At this time, the spatial distance between First Signal 1 and First Signal 2 can be calculated as 1 micrometer, and the spatial distance between First Signal 1 and First Signal 2 is not equal to the target spatial interval; the spatial distance between First Signal 3 and First Signal 1 is 2 micrometers, and the spatial distance between First Signal 1 and First Signal 3 is equal to the target spatial interval. Therefore, if the terminal device determines First Signal 1 as the first second signal, First Signal 3 can be determined as the second second signal. Further, the terminal device can calculate that the spatial distance between First Signal 3 and First Signal 4 is 2 micrometers, and the spatial distance between First Signal 3 and First Signal 4 is equal to the target spatial interval. Therefore, First Signal 4 can be determined as the third second signal. It can be understood that if the spatial distances between every two adjacent first signals obtained by the terminal device are not all the target spatial intervals, second signals with a number less than that of the first signals can be obtained by equal-spatial-interval sampling based on the multiple first signals.

[0079] Optionally, in some feasible implementations, the terminal device can also process the above second signals. For example, operations such as denoising can be performed to improve the accuracy of the second signals. It can be understood that when the movement speed of the target wafer changes, the number of sampling points generated in the same-width area is different, and the signal envelope width generated based on the sampling points is also different. The different signal envelope widths in the same-width area affect the accuracy of wafer defect pre-inspection. Therefore, in this application, equal-time-interval secondary sampling is used to ensure that the spatial intervals between the sampling points corresponding to two adjacent second signals are the same, thereby ensuring that the number of sampling points in the same-width area is the same, and the accuracy of wafer defect pre-inspection can be improved. In addition, by using the secondary sampling method, it is possible to avoid the excessively long processing time caused by directly processing the huge amount of data obtained during the first sampling. The secondary sampling can remove redundant data while ensuring that the information indicated by the signal is basically retained intact, reducing interference. Therefore, the speed and accuracy of wafer defect pre-inspection can be improved.

[0080] Step S104: Generate a signal envelope based on the multiple second signals, and perform defect pre-inspection on the target wafer based on the signal envelope to adjust the power of the laser based on the result of the defect pre-inspection.

[0081] In some feasible embodiments, the terminal device may generate a signal envelope based on the second signal, and then analyze the possible potential positions and defect shapes of the wafer defects based on the shape of the signal envelope to perform a preliminary defect check on the target wafer, and adjust the power of the laser based on the detection result of the preliminary defect check, so that the power of the laser can be adapted to the subsequent scanning of the target wafer. For example, the power of the laser emission device may be increased or decreased according to the position and shape of the wafer defect to increase or decrease the power of the laser, thereby preventing the wafer from being damaged due to too high laser power, or preventing the missed detection or misdetection of wafer defects due to too low laser power.

[0082] See Figure 8 , Figure 8 is a schematic diagram of the signal envelope provided by this application. As Figure 8 shown, the horizontal axis is the spatial position of the target sampling point, the vertical axis is the signal intensity of the second signal, and the solid arrow below the signal envelope is used to indicate the second signal. The intersection of the solid arrow and the horizontal axis indicates the position of the target sampling point for the terminal device to perform secondary sampling ( Figure 8 not all marked in, only the position of one target sampling point is shown). As Figure 8 shown, the spatial interval between the target sampling points corresponding to every two adjacent second signals is the same. It should be noted that since the spatial position increases with the increase of the sampling time in this application, that is, the sampling time and the spatial position are in a positive correlation relationship, therefore, for a better understanding of the effect of sampling at equal spatial intervals in this application, the horizontal axis of the signal envelope schematic diagram in this application indicates the spatial position of the target wafer. It can be understood that since the spatial intervals between every two adjacent target sampling points among the multiple target sampling points for secondary sampling are all equal, the number of sampling points in two defects of the same size will not be inconsistent due to the change in the movement speed of the target wafer, thereby ensuring the sampling accuracy and enabling a more accurate judgment of the size of the wafer defect.

[0083] In some feasible embodiments, the initial position and the end position of the wafer defect may be determined according to the change rate (i.e., the slope) of the signal envelope generated from the second signal. For example, if the change rate threshold is set to 1.4, the spatial position of the sampling point corresponding to the second signal whose change rate changes from below 1.4 to above or equal to 1.4 can be determined as the initial position of the wafer defect, as can be seen in Figure 8 shown in the initial position. If the change rate threshold is set to 1.4, the spatial position of the sampling point corresponding to the second signal whose change rate changes from above or equal to 1.4 to below 1.4 can be determined as the end position of the wafer defect, as can be seen in Figure 8 shown in the end position. As Figure 8As shown, the part between the initial position and the end position is a convex area, which is used to indicate that there may be wafer defects in the spatial position corresponding to the convex area.

[0084] By adopting the present application, the terminal device can obtain a plurality of first signals of a target wafer moving along a target motion trajectory. The first signals are digital light intensity signals obtained by sampling the light intensity of the target wafer under the illumination of a laser. Among them, one first signal corresponds to one sampling point in the target motion trajectory, and the time intervals between the sampling times corresponding to every two adjacent sampling points in the target motion trajectory are the same. In addition, the terminal device can obtain the motion parameters of the target wafer when passing through each sampling point during the movement along the target motion trajectory, calculate the spatial interval between every two adjacent sampling points based on the motion parameters; perform equal-spatial-interval sampling on the plurality of first signals corresponding to the plurality of sampling points to obtain a plurality of second signals, where the spatial interval between the two sampling points corresponding to every two adjacent sampled second signals is the target spatial interval. Generate a signal envelope based on the plurality of second signals, and perform preliminary defect detection on the target wafer based on the signal envelope to adjust the power of the laser based on the result of the preliminary defect detection. This can avoid the situation where the widths of the signal envelopes generated based on the sampling points are different due to different numbers of sampling points generated in the same-width area when the moving speed of the target wafer changes, ensure that the number of sampling points in the same-width area is the same, and improve the accuracy of the preliminary wafer defect detection. In addition, by selecting the second signals, the data processing volume for wafer defect detection can be reduced, and the interference of unnecessary data can also be reduced while ensuring that the information indicated by the first signals is basically retained intact. Therefore, the speed and accuracy of the preliminary wafer defect detection can be improved, the adjustment accuracy of the laser power can be improved, and the applicability is strong.

[0085] Please refer to Figure 9 , Figure 9 which is a schematic structural diagram of the wafer defect detection device provided by the present application. As Figure 9 shown, the wafer defect detection device 10 can be a computer device, which has a computer program (including program code) for implementing the above-mentioned wafer defect detection method. The wafer defect detection device 10 can also be a computer program, for example, this computer program is an application software. This device can be used to execute the corresponding steps in the wafer defect detection method provided by the embodiments of the present application. As Figure 9 shown, the above-mentioned wafer defect detection device 10 can include: a first acquisition module 101, a second acquisition module 102, a sampling module 103, and a generation module 104.

[0086] A first acquisition module 101, configured to acquire a plurality of first signals of a target wafer, where the first signals are digital light intensity signals obtained by sampling the light intensity signals of the target wafer moving along a target motion trajectory under the illumination of a laser. One of the first signals corresponds to one sampling point in the target motion trajectory, and the time interval between the sampling times corresponding to every two adjacent sampling points in the target motion trajectory is the same;

[0087] A second acquisition module 102, configured to acquire the motion parameters of the target wafer when passing through each of the sampling points during the movement of the target wafer along the target motion trajectory, and calculate the spatial interval between every two adjacent sampling points based on the motion parameters;

[0088] A sampling module 103, configured to perform equal-spatial-interval sampling on the plurality of first signals corresponding to the plurality of sampling points to obtain a plurality of second signals, where the spatial interval between the two sampling points corresponding to every two adjacent samplings of the two second signals is a target spatial interval;

[0089] A generation module 104, configured to generate a signal envelope based on the plurality of second signals, and perform pre-inspection of defects on the target wafer based on the signal envelope to adjust the power of the laser based on the result of the pre-inspection of defects.

[0090] In some feasible embodiments, the first acquisition module 101 is further configured to acquire the plurality of first signals generated by an analog-to-digital converter for analog-to-digital conversion of a plurality of first analog light intensity signals; the time interval between the sampling times of every two adjacent sampling points is obtained from the device parameters of the analog-to-digital converter.

[0091] In some feasible embodiments, the motion parameters include the sampling time and the motion speed; the second acquisition module 102 includes: a first acquisition unit 1021 and a calculation unit 1022.

[0092] The first acquisition unit 1021 is configured to obtain the sampling time and the motion speed of the target wafer when passing through each of the sampling points during the movement of the target wafer along the target motion trajectory through a motion controller;

[0093] The calculation unit 1022 is configured to obtain the time interval between two adjacent sampling points based on the sampling times of the two adjacent sampling points, and calculate the spatial interval between the two adjacent sampling points based on the time interval and the motion speed.

[0094] In some feasible embodiments, the motion speed includes a linear speed; the calculation unit 1022 includes a first calculation sub-unit 10221.

[0095] The first calculation subunit 10221 is configured to calculate the spatial interval between two adjacent sampling points based on the product of the linear velocity and the time interval when the target wafer moves at a constant linear velocity.

[0096] In some feasible embodiments, the motion speed includes an angular velocity, and the target motion trajectory includes a spiral trajectory; the calculation unit 1022 includes a second calculation subunit 10222 and a third calculation subunit 10223.

[0097] The second calculation subunit 10222 is configured to generate the motion angle of the target wafer based on the product of the angular velocity and the time interval when the target wafer moves at a constant angular velocity.

[0098] The third calculation subunit 10223 is configured to determine the arc length corresponding to the motion angle in the spiral trajectory based on the motion angle, and determine the arc length as the spatial interval between two adjacent sampling points.

[0099] In some feasible embodiments, the two sampling points corresponding to the two second signals obtained by each adjacent two samplings are two adjacent target sampling points; the sampling module 103 includes: a second acquisition unit 1031, a traversal unit 1032, and a selection unit 1033.

[0100] The second acquisition unit 1031 is configured to acquire the target spatial interval.

[0101] The traversal unit 1032 is configured to traverse the multiple sampling points based on the spatial interval between every two adjacent sampling points, and select multiple target sampling points from the multiple sampling points, wherein the spatial interval between every two adjacent target sampling points is equal to the target spatial interval.

[0102] The selection unit 1033 is configured to select the first signals corresponding to the respective target sampling points from the multiple first signals as the second signals to obtain the multiple second signals.

[0103] In some feasible embodiments, the traversal unit 1032 includes:

[0104] The first determination subunit 10321 is configured to determine a reference sampling point from the multiple sampling points, and obtain the spatial distances between the sampling points after the reference sampling point and the reference sampling point based on the spatial interval between every two adjacent sampling points.

[0105] A second determination subunit 10322 is configured to determine a sampling point that is closest to the above-mentioned reference sampling point and has a spatial distance from the above-mentioned reference sampling point equal to the above-mentioned target spatial interval as an equidistant sampling point, so as to determine the above-mentioned reference sampling point and the above-mentioned equidistant sampling point as two adjacent target sampling points.

[0106] In some feasible implementation manners, the implementation manners of each module, unit, and / or subunit included in the above-mentioned wafer defect detection device can refer to the implementation manners provided in each step of the above-mentioned Figures 6 to 8 wafer defect detection method shown, and will not be elaborated here.

[0107] By using the present application, the wafer defect detection device can obtain a plurality of first signals of a target wafer moving along a target motion trajectory. The first signal is an optical intensity digital signal obtained by sampling the optical intensity signal of the target wafer under the illumination of a laser. Among them, one first signal corresponds to one sampling point in the target motion trajectory, and the time interval between the sampling times corresponding to every two adjacent sampling points in the target motion trajectory is the same. In addition, the wafer defect detection device can obtain the motion parameters of the target wafer when passing through each sampling point during the movement along the target motion trajectory, calculate the spatial interval between every two adjacent sampling points based on the motion parameters; perform equidistant sampling on the plurality of first signals corresponding to the plurality of sampling points to obtain a plurality of second signals, where the spatial interval between the two sampling points corresponding to every two adjacent samplings is the target spatial interval. Generate a signal envelope based on the plurality of second signals, and perform defect pre-inspection on the target wafer based on the signal envelope to adjust the power of the laser based on the result of the defect pre-inspection, which can avoid the situation that the width of the signal envelope generated based on the sampling points is different due to the different number of sampling points generated in the same-width area when the movement speed of the target wafer changes, ensure that the number of sampling points in the same-width area is the same, and improve the accuracy of wafer defect pre-inspection. In addition, by selecting the second signal, the data processing amount of wafer defect detection can be reduced, and the interference of unnecessary data can also be reduced while ensuring that the information indicated by the first signal is basically retained completely. Therefore, the speed and accuracy of wafer defect pre-inspection can be improved, the adjustment accuracy of the laser power can be improved, and the applicability is strong.

[0108] Please refer to Figure 10 , Figure 10 which is a schematic structural diagram of a terminal device provided by the present application. As Figure 10As shown in the figure, the terminal device 100 may include: a memory 1001, a processor 1002, and a transceiver 1003. The memory 1001 includes a random access memory (RAM) and a non-volatile memory (NVM), such as an erasable programmable read-only memory (EPROM). Optionally, the memory 1001 may also be at least one storage device located far from the aforementioned processor 1002. The processor 1002 may be a central processing unit, a microprocessor, or a programmable gate array chip, or other processors, which are not limited in this application. The transceiver 1003 may include a user interface and a network interface. Among them, the user interface may include a display and a keyboard. Optionally, the user interface may also include a standard wired interface and a wireless interface. The network interface may optionally include a standard wired interface and a wireless interface (such as a WI-FI interface). As Figure 10 shown, the memory 1001, as a computer-readable storage medium, may include an operating system, a network communication module, a user interface module, and a device control application program. In this embodiment, the memory 1001 can execute the functions of the memory in the Figure 1 wafer defect detection system shown above. The processor 1002 described in this embodiment can execute the functions performed by the processor in the Figure 1 embodiment shown above.

[0109] Optionally, in some feasible embodiments, the above terminal device 100 may further include: a controller 1004 and at least one communication bus 1005. The communication bus 1005 is used to realize the connection and communication between components such as the memory 1001, the processor 1002, the transceiver 1003, and the controller 1004.

[0110] In the terminal device 100 as Figure 10 shown, the network interface in the transceiver 1003 can provide network communication functions, while the user interface is mainly used to provide an input interface for users; the memory 1001 can store program codes or data; and the processor 1002 can be used to call the program code data stored in the memory 1001 to execute the wafer defect detection method in the Figures 6 to 8 embodiment shown above. If the terminal device includes a controller 1004, the controller 1004 can receive the data sent by the processor 1002 and generate control instructions to control devices such as a laser emission device through the transceiver. Optionally, the above controller 1004 may be a laser controller or other types of controllers, which should be determined according to the actual application scenario. This application only takes the laser controller as an example for illustration.

[0111] It should be understood that the terminal device 100 described in the present application can execute the wafer defect detection method of the foregoing Figures 6 to 8 illustrated embodiment. The terminal device 100 can be a separate device or integrated with an analog-to-digital converter as in the Figure 1 illustrated embodiment in the same device, and the present application does not make any restrictions. In addition, the description of the beneficial effects of adopting the same method will not be repeated.

[0112] In addition, it should be noted here that: The embodiments of the present application further provide a computer-readable storage medium, and the computer-readable storage medium stores a computer program executed by the foregoing wafer defect detection method, and the computer program includes program instructions. When the foregoing processor executes the program instructions, it can execute the foregoing Figures 6 to 8 illustrated embodiment of the foregoing wafer defect detection method. Therefore, it will not be repeated. In addition, the description of the beneficial effects of adopting the same method will not be repeated. For the technical details not disclosed in the embodiments of the computer-readable storage medium involved in the present application, please refer to the description of the method embodiments of the present application.

[0113] The foregoing computer-readable storage medium can be the internal storage unit of the wafer defect detection method or the foregoing terminal device provided in any of the foregoing embodiments, such as the hard disk or memory of the terminal device. The computer-readable storage medium can also be an external storage device of the terminal device, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the terminal device. Further, the computer-readable storage medium can also include both the internal storage unit and the external storage device of the terminal device. The computer-readable storage medium is used to store the computer program and other programs and data required by the terminal device. The computer-readable storage medium can also be used to temporarily store the data that has been output or will be output.

[0114] In addition, it should be noted here that: The embodiments of the present application further provide a computer program product or a computer program. The computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. The processor of the terminal device loads and executes the computer instructions, so that the terminal device can execute the foregoing Figures 6 to 8 illustrated embodiment of the method.

[0115] Those of ordinary skill in the art can realize that the wafer defect detection methods, systems, and terminal devices of the various examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Professionals can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

Claims

1. A wafer defect detection method, characterized in that: The method comprises: Acquire multiple first signals of the target wafer, wherein the first signal is a light intensity digital signal obtained by sampling the light intensity signal of the target wafer moving along the target motion trajectory under the condition of laser illumination, wherein one of the first signals corresponds to a sampling point in the target motion trajectory, and the time interval between sampling moments corresponding to every two adjacent sampling points in the target motion trajectory is the same; Acquire motion parameters of the target wafer when it passes through each of the sampling points in the process of moving based on the target motion trajectory, and calculate the spatial interval between every two adjacent sampling points based on the motion parameters; Performing equal spatial interval sampling on the plurality of first signals corresponding to the plurality of sampling points to obtain a plurality of second signals, wherein the spatial interval between the two sampling points corresponding to the two second signals obtained by every two adjacent samplings is the target spatial interval; A signal envelope is generated based on the plurality of second signals, and a defect pre-inspection is performed on the target wafer based on the signal envelope to adjust the power of the laser based on a result of the defect pre-inspection.

2. The method according to claim 1, characterized in that: The step of acquiring a plurality of first signals of the target wafer includes: A plurality of first signals generated by analog-to-digital conversion of a plurality of first light intensity analog signals by an analog-to-digital converter are obtained; and the time interval between the sampling moments of each two adjacent sampling points is obtained by the device parameters of the analog-to-digital converter.

3. The method according to claim 2, characterized in that The motion parameters include the sampling time and the motion speed; the step of obtaining the motion parameters of the target wafer when it passes through each of the sampling points during the movement of the target motion trajectory, and calculating the spatial interval between each two adjacent sampling points based on the motion parameters includes: Acquire, by a motion controller, the sampling time when the target wafer passes through each of the sampling points in the process of moving based on the target motion trajectory and the movement speed of the target wafer; The time interval between two adjacent sampling points is obtained based on the sampling moments of the two adjacent sampling points, and the spatial interval between two adjacent sampling points is calculated based on the time interval and the movement speed.

4. The method according to claim 3, characterized in that The movement speed includes a linear speed; the calculation based on the time interval and the movement speed to obtain a spatial interval between two adjacent sampling points includes: When the target wafer moves at a constant linear velocity, the spatial interval between two adjacent sampling points is calculated based on the product of the linear velocity and the time interval.

5. The method according to claim 3, characterized in that: The movement speed includes an angular velocity, and the target movement trajectory includes a spiral trajectory; the calculation based on the time interval and the movement speed to obtain the spatial interval between two adjacent sampling points includes: When the target wafer moves at a constant angular velocity, generating a movement angle of the target wafer based on a product of the angular velocity and the time interval; The arc length corresponding to the motion angle in the spiral trajectory is determined based on the motion angle, and the arc length is determined as the spatial interval between two adjacent sampling points.

6. The method according to claim 4 or 5, characterized in that: The two sampling points corresponding to the two second signals obtained by every two adjacent samplings are two adjacent target sampling points; The method of sampling the first signals corresponding to the sampling points at equal intervals to obtain the second signals includes: Acquire the target spatial interval; Traversing the plurality of sampling points based on the spatial interval between each two adjacent sampling points, and selecting a plurality of target sampling points from the plurality of sampling points, wherein the spatial interval between each two adjacent target sampling points is equal to the target spatial interval; A first signal corresponding to each of the target sampling points is selected from the plurality of the first signals as a second signal to obtain a plurality of the second signals.

7. The method according to claim 6, characterized in that The traversing the plurality of sampling points based on the spatial interval between each two adjacent sampling points and selecting a plurality of target sampling points from the plurality of sampling points comprises: Determine a reference sampling point from the plurality of sampling points, and obtain a spatial distance between each sampling point after the reference sampling point and the reference sampling point based on the spatial interval between every two adjacent sampling points; The sampling point which is closest to the reference sampling point and whose spatial distance from the reference sampling point is equal to the target spatial interval is determined as an equidistant sampling point, so that the reference sampling point and the equidistant sampling point are determined as two adjacent target sampling points.

8. A wafer defect detection device, characterized in that: The device comprises: A first acquisition module is used to acquire multiple first signals of a target wafer, wherein the first signal is a light intensity digital signal obtained by sampling a light intensity signal of the target wafer moving along a target motion trajectory under the condition that a laser provides illumination, wherein one of the first signals corresponds to a sampling point in the target motion trajectory, and the time interval between sampling moments corresponding to each two adjacent sampling points in the target motion trajectory is the same; A second acquisition module is used to acquire motion parameters of the target wafer when it passes through each of the sampling points in the process of moving based on the target motion trajectory, and calculate the spatial interval between each two adjacent sampling points based on the motion parameters; a sampling module, configured to perform equal spatial interval sampling on the plurality of first signals corresponding to the plurality of sampling points to obtain a plurality of second signals, wherein the spatial interval between the two sampling points corresponding to the two second signals obtained by every two adjacent samplings is a target spatial interval; A generating module is used to generate a signal envelope based on the plurality of second signals, and to perform defect pre-inspection on the target wafer based on the signal envelope to adjust the power of the laser based on a result of the defect pre-inspection.

9. A terminal device, characterized in that: include: transceivers, memory, and processors; The memory is used to store program code and data, and the processor is used to call the program code so that the transceiver and the processor process the data to implement the wafer defect detection method as described in any one of claims 1-7.

10. A wafer defect detection system, characterized in that: The system comprises: an analog-to-digital converter and a terminal device as claimed in claim 9; The analog-to-digital converter is used to acquire a first light intensity analog signal, and perform analog-to-digital conversion on the first light intensity analog signal to generate the first signal; wherein the time interval for the analog-to-digital converter to acquire the first light intensity analog signal is obtained by a device parameter of the analog-to-digital converter.

11. The system according to claim 10, characterized in that The system also includes a photomultiplier tube; The photomultiplier tube is used to sample the light intensity of the light spot generated by the moving target wafer under laser illumination and transmit the sampled first light intensity analog signal to the analog-to-digital converter.

12. The system according to claim 11, characterized in that The system also includes a laser emitting device; The laser emitting device is used to emit laser to provide illumination for the target wafer.

13. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is suitable for being loaded by a processor and executing the method according to any one of claims 1 to 7.

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