Wafer defect detection method and system and terminal equipment

Abstract

The invention discloses a wafer defect detection method and system and terminal equipment, and the method comprises the steps: obtaining a plurality of first signals of a target wafer moving based on a target motion track, one first signal corresponding to one sampling point in the target motion track, and the time intervals of the sampling moments of every two adjacent sampling points are the same; acquiring motion parameters of the target wafer when the target wafer passes through each sampling point so as to calculate a space interval between every two adjacent sampling points; sampling the plurality of first signals at equal space intervals to obtain a plurality of second signals, wherein the space interval between two sampling points corresponding to two second signals obtained by every two adjacent times of sampling is a target space interval; and the signal envelope is generated based on the plurality of second signals so as to perform defect pre-detection on the target wafer, and the laser power is adjusted based on the defect pre-detection result, so that the wafer defect detection precision is high, the laser power adjustment precision is high, and the applicability is high.

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 equipment. Background Art

[0002] Wafer semiconductor inspection technology plays an important role in the semiconductor production, packaging and testing processes, among which wafer defect detection is the key in semiconductor inspection technology. Pre-inspection of wafer defects before wafer defect detection can improve the imaging effect of wafer images. During the pre-inspection of wafer defects, the intensity of the light spot formed by the laser irradiation on the wafer can be detected to generate a signal envelope indicating the defect size, shape and other information of the wafer. If the defect size, shape and other characteristics indicated by the signal envelope do not match the laser power, it will affect the illumination effect of the laser, and then affect the imaging effect of the wafer image, resulting in false detection or missed detection of wafer defects based on wafer images.

[0003] In order to improve the accuracy of wafer defect pre-inspection, the laser power modulation (LPM) system in the patternless wafer inspection equipment can be used to pre-inspect wafer defects based on a spiral scanning trajectory and adjust the laser power based on the wafer defect pre-inspection results. 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 then obtains information such as defect size and shape based on the signal envelope. LPM determines whether the curvature change of the signal envelope exceeds the threshold to determine whether the wafer has defects, and extracts the signal fitting peak at the moment when the curvature exceeds the threshold to determine the defect size, so as to adjust the intensity of the spot generated by the laser irradiation 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 yield, the moving stage in the patternless wafer inspection equipment often has changes in movement speed during the wafer scanning process. At this time, the signal envelope width generated based on the sampled digital signal is also inconsistent. The curvature error formed by the width error of the signal envelope leads to low pre-inspection accuracy of the defect size. Therefore, the pre-inspection result cannot adapt well to the wafer defect detection scenario with changes in movement speed during the wafer scanning process, has poor applicability, and has poor accuracy in laser power adjustment. 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 applicability.

[0005] In a first aspect, the present application provides a wafer defect detection method, the method comprising: acquiring multiple first signals of a target wafer, the first signals being light intensity digital signals obtained by sampling light intensity signals of the target wafer moving based on a 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 intervals of the sampling moments corresponding to each two adjacent sampling points in the target motion trajectory are the same; acquiring 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 calculating the spatial interval between each two adjacent sampling points based on the motion parameters; sampling the multiple first signals corresponding to the multiple sampling points at equal spatial intervals to obtain multiple second signals, wherein the spatial intervals between the two sampling points corresponding to the two second signals obtained by each two adjacent samplings are both target spatial intervals; generating a signal envelope based on the multiple second signals, and performing 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.

[0006] By adopting the present application, the sampling points of the first signal can be sampled at equal spatial intervals to ensure that the number of sampling points within the defect range of two wafers of the same size is the same, thereby reducing the morphological error of the signal envelope generated by the second signal obtained based on the sampling. Therefore, the detection accuracy of wafer defect pre-inspection based on the signal envelope can be improved, the accuracy of adjusting the laser power based on the wafer defect pre-inspection results can be improved, and the applicability can be enhanced.

[0007] In a possible implementation of the first aspect, the acquisition of multiple first signals of the target wafer includes: acquiring multiple first signals generated by an analog-to-digital converter performing analog-to-digital conversion on multiple first light intensity analog signals; 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. With the present application, the terminal device can implement sampling of light intensity digital signals at equal time intervals through an analog-to-digital converter, and can obtain the first light intensity analog signal from the photomultiplier tube at equal time intervals through the analog-to-digital converter and perform analog-to-digital conversion to generate the first signal. Compared with analog signals, digital signals are processed faster and have stronger anti-interference capabilities, so the detection accuracy and detection speed of wafer defect pre-inspection can be further improved, and the applicability is strong.

[0008] In a possible implementation of the first aspect, the motion parameters include the sampling time and the motion speed; the motion parameters of the target wafer passing through each of the sampling points in the process of moving based on the target motion trajectory are obtained, and the spatial interval between each two adjacent sampling points is calculated based on the motion parameters, including: obtaining the sampling time and the motion speed of the target wafer when the target wafer passes through each of the sampling points in the process of moving based on the target motion trajectory through a motion controller; obtaining the time interval between the two adjacent sampling points based on the sampling time of the two adjacent sampling points, and calculating the spatial interval between the two adjacent sampling points based on the time interval and the motion speed. With the present application, the terminal device can control the motion platform to carry the target wafer through the motion controller and obtain the sampling time and motion speed of the target wafer passing through the sampling points in real time, and then calculate the spatial interval between the two adjacent sampling points. The real-time performance is strong, and the data acquisition is more accurate. Therefore, the detection accuracy and detection speed of wafer defect pre-inspection can be further improved, and the applicability is strong.

[0009] In a possible implementation of the first aspect, the movement speed includes a linear speed; the spatial interval between two adjacent sampling points is calculated based on the time interval and the movement speed, including: when the target wafer moves at a constant linear speed, the spatial interval between two adjacent sampling points is calculated based on the product of the linear speed and the time interval. The present application can be applied to the case where the target wafer moves at a constant linear speed, and the terminal device can calculate the spatial interval between two adjacent sampling points based on the linear speed and the time interval, which is simple to calculate and has strong applicability.

[0010] In a possible implementation of the first aspect, the movement speed includes an angular velocity, and the target movement trajectory includes a spiral trajectory; the spatial interval between the two adjacent sampling points is calculated based on the time interval and the movement speed, including: when the target wafer moves at a constant angular velocity, the movement angle of the target wafer is generated based on the product of the angular velocity and the time interval; based on the movement angle, the arc length corresponding to the movement angle in the spiral trajectory is determined, and the arc length is determined as the spatial interval between the two adjacent sampling points. The present application can be applied to the case where the target wafer moves at a constant angular velocity. The terminal device can calculate the movement angle based on the angular velocity and the time interval, and then calculate the spatial interval between the two adjacent sampling points based on the movement angle. The calculation is simple and has strong applicability.

[0011] In a possible implementation manner of the first aspect, the two sampling points corresponding to the two second signals obtained by sampling every two adjacent times are two adjacent target sampling points; and the sampling of the multiple first signals corresponding to the multiple sampling points at equal spatial intervals to obtain the multiple second signals includes: acquiring the above-mentioned target spatial interval; traversing the multiple sampling points based on the spatial interval between every two adjacent sampling points, and selecting multiple target sampling points from the multiple sampling points, wherein the spatial interval between every two adjacent target sampling points is equal to the above-mentioned target spatial interval; and selecting the first signal corresponding to each of the multiple first signals as the second signal to obtain the multiple second signals. By adopting the present application, multiple target sampling points can be determined from multiple sampling points through the target spatial interval. Since the spatial interval between each two adjacent target sampling points is the same, it can be ensured that the number of sampling points in two wafer defects of the same size is also the same, thereby improving the accuracy of the signal envelope generated by the second signal, 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 results; in addition, by re-sampling the multiple first signals, unnecessary data in the first signal can be eliminated, and the interference caused by excessive data can also be reduced, thereby further improving the detection speed and detection accuracy of wafer defects.

[0012] In a possible implementation of the first aspect, the above-mentioned traversing the plurality of sampling points based on the spatial interval between each adjacent two sampling points, and selecting a plurality of target sampling points from the plurality of sampling points, includes: determining a reference sampling point from the plurality of sampling points, and obtaining the spatial distance between each sampling point after the reference sampling point and the reference sampling point based on the spatial interval between each adjacent two sampling points; determining the sampling point closest to the reference sampling point and having a spatial distance from the reference sampling point equal to the target spatial interval as an equidistant sampling point, so as to determine the reference sampling point and the equidistant sampling point as two adjacent target sampling points. By adopting the present application, the plurality of sampling points can be traversed in sequence according to the sampling time sequence, and the reference sampling points and the equidistant sampling points having the same spatial distance as the target spatial interval can be calculated to determine a plurality of target sampling points, thereby ensuring that the spatial interval between each adjacent two 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 a wafer defect detection method provided in the first aspect or any possible implementation manner of the first aspect.

[0014] Exemplarily, the device comprises: A first acquisition module is used to acquire multiple first signals of a target wafer, wherein the first signals are light intensity digital signals obtained by sampling light intensity signals 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 intervals between sampling moments corresponding to each two adjacent sampling points in the target motion trajectory are the same; A second acquisition module is used to obtain 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, used for sampling the plurality of first signals corresponding to the plurality of sampling points at equal spatial intervals 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 the result of the defect pre-inspection.

[0015] By adopting the present application, multiple first signals of the target wafer can be acquired through the first acquisition module, the spatial interval between each two adjacent sampling points can be calculated through the second acquisition module, the multiple first signals can be sampled at equal spatial intervals through the sampling module to obtain multiple second signals, and the signal envelope can be generated based on the multiple second signals through the generation module to adjust the laser power. This can improve the detection accuracy of wafer defect pre-inspection, improve the accuracy of adjusting the laser power based on the wafer defect pre-inspection results, and has strong applicability.

[0016] In the third aspect, the present application provides a terminal device, including: a transceiver, a memory, and a processor; 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 described in the first aspect and any possible implementation 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 collaboration of the processor and the memory, which can improve the detection accuracy of wafer defect pre-inspection, improve the accuracy of adjusting the laser power based on the wafer defect pre-inspection results, and has strong applicability.

[0017] In a fourth aspect, the present application provides a wafer defect detection system, the system comprising: an analog-to-digital converter and a terminal device as described in the second aspect; the analog-to-digital converter is used to obtain 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 obtain the first light intensity analog signal is obtained by the device parameters of the analog-to-digital converter. By adopting the present application, the 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 flexible to install, and has fast sampling speed and analog-to-digital conversion speed. The obtained first signal has strong anti-interference ability and small error. Therefore, the detection accuracy of wafer defect pre-inspection can be improved, and the accuracy of adjusting the laser power based on the wafer defect pre-inspection results can be improved, and the applicability is strong.

[0018] In a possible implementation of the fourth aspect, the system further 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. By adopting the present application, the relatively weak light beam reflected by the target wafer can be received by the photomultiplier tube, and a clear first light intensity analog signal can be generated, thereby improving the detection accuracy of wafer defect pre-inspection, improving the accuracy of adjusting the laser power based on the wafer defect pre-inspection results, and the photomultiplier tube is small in size, flexible in loading, and has strong applicability.

[0019] In a possible implementation of the fourth aspect, the system further comprises a laser emitting device; the laser emitting device is used to emit laser light to provide illumination for the target wafer. With the present application, the laser emitting device can emit laser light to illuminate the target wafer and project a characteristic image on the target wafer for wafer pre-inspection. The projection shape of the laser light can be adjusted, and the laser power can be adjusted, so the system has strong applicability.

[0020] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium, in which a computer program is stored. The computer program is suitable for being loaded by a processor and executing the wafer defect detection method provided by the first aspect or any possible implementation method of the first aspect.

[0021] In a sixth aspect, an embodiment of the present application provides a computer program product, wherein the computer program product comprises computer instructions, and the computer instructions are suitable for being loaded by a processor and executing the wafer defect detection method provided by the first aspect or any possible implementation scheme of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of an application scenario of a wafer defect detection system provided by the present application; Figure 2 It is a schematic diagram of the spiral trajectory provided by this application; Figure 3 It is a schematic diagram of the light spot provided by this application; Figure 4 is a schematic diagram of changes in the first light intensity simulation signal provided by the present application; Figure 5 It is a schematic diagram of the location of the sampling points provided in this application; Figure 6 It is a flow chart of the wafer defect detection method provided by the present application; Figure 7 is another schematic diagram of the location of the sampling points provided in this application; Figure 8 It is a schematic diagram of the signal envelope provided by this application; Fig. 9 It is a structural schematic diagram of a wafer defect detection device provided by the present application; Fig.10 It is a structural diagram of the terminal device provided by this application. DETAILED DESCRIPTION

[0023] The technical solution in this application will be described below in conjunction with the drawings in this application.

[0024] To facilitate understanding, some nouns are briefly explained as follows: 1. The target motion trajectory refers to the trajectory of the motion stage carrying the target wafer. Multiple sampling points can be set in the target motion trajectory. When the motion stage carries the target wafer through the sampling points, the sampling device can sample the target wafer. Among them, the target motion trajectory can be pre-set in the motion controller used to control the motion of the motion stage to trigger the motion of the target wafer carrying the motion stage according to the specified trajectory. In this application, the target motion trajectory is a spiral trajectory.

[0025] 2. Primary sampling refers to a 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 a first signal.

[0026] 3. Secondary sampling refers to the process of sampling the first signal based on multiple target sampling points with equal spatial intervals to obtain the second signal.

[0027] 4. Sampling point refers to a marking point in the target motion trajectory used to determine the spatial position of a sample of the target wafer. It can be recorded in the form of coordinates, or the position of the sampling point can be determined by determining the sampling time. In this application, when the target wafer passes through the sampling point, it can be sampled once by an analog-to-digital converter to obtain a first signal. Among them, one sampling point corresponds to one first signal, and the time interval between the sampling times of each two adjacent sampling points is the same, and the above sampling time is determined by the device parameters of the analog-to-digital converter.

[0028] 5. Target sampling point, a marking point selected from multiple sampling points for resampling the first signal of the target wafer. In the present application, when the target wafer passes through the target sampling point, multiple first signals can be resampled by the terminal device to obtain multiple second signals. Among them, one target sampling point corresponds to one second signal, and the spatial interval between each two adjacent sampling points is the same.

[0029] 6. Signal envelope refers to a curve that reflects the change of signal intensity over time, which is intuitively expressed as the outline of the signal waveform. Since the spatial position of the target wafer in this application increases with the increase of the sampling time, that is, the sampling time and the spatial position are positively correlated, in order to better understand the effect of medium-space interval sampling in this application, the horizontal axis of the signal envelope schematic diagram in this application is replaced from indicating the sampling time to indicating the spatial position. The raised area in the signal envelope is used to indicate that there may be wafer defects in the spatial position corresponding to the raised area, so the initial position and end position of the wafer defect can be determined by analyzing the initial position and end position of the raised area of ​​the signal envelope. The above-mentioned raised area can also be called the signal fitting peak. The difference in the extraction of the signal fitting peak caused by the different signal envelope morphology, and the inconsistency in the width of the signal envelope generated by wafer defects of the same size, can affect the calculation accuracy of the wafer defect size.

[0030] 7. An analog-to-digital converter is a device that converts analog signals into digital signals. The main function of an analog-to-digital converter is to convert a continuous-time, continuous-amplitude analog signal into a discrete-time, discrete-amplitude digital signal. An analog-to-digital converter generally includes four processes: sampling, holding, quantization, and encoding. In this application, the target wafer may be sampled once by an analog-to-digital converter, and in some feasible implementations, the analog-to-digital converter may also be used for secondary sampling.

[0031] 8. Defect pre-inspection is an indispensable part of the wafer defect detection process. It detects the target wafer to find potential or existing wafer defects, and then adjusts the laser power irradiating the target wafer according to the defect pre-inspection situation to make the laser power adapt to the subsequent scanning of the target wafer.

[0032] The wafer defect detection method and wafer defect detection system provided in this application can be applied to the application scenario of wafer defect pre-inspection, and can also be applied to other application scenarios that require detection of target wafers. The specific application scenario can be determined according to the actual application scenario and is not limited here. For the sake of ease of description, this application takes the application scenario of wafer defect pre-inspection as an example. In this application scenario, the motion control and defect detection of the wafer can be performed by a working system. The working system includes but is not limited to the wafer defect detection system provided in this application. The wafer defect detection system is used for pre-inspection of wafer defect detection. See. Figure 1 , Figure 1Schematic diagram of the application scenario of the wafer defect detection system provided by this application. Figure 1 In the application scenario shown, the working system may include a motion stage, a motion controller and a wafer defect detection system, wherein the wafer defect detection system may include a terminal device and an analog-to-digital converter.

[0033] In some possible implementations, such as Figure 1 As shown, the target wafer can be carried by the motion stage and move with the motion stage based on the target motion trajectory. The motion stage can be controlled by a 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 motion stage can be an X / Z / Theta axis motion stage, or it can be other motion stages that can be loaded with target wafers. This application does not limit this, and takes the X / Z / Theta axis motion stage as an example for explanation. It can be understood that the motion stage can move on the X-axis, Z-axis and Theta axis, corresponding to lateral movement, vertical movement and rotation angle movement, respectively. The motion stage can load the target wafer and adjust the target wafer position by movement. Optionally, the motion stage can also include a Y-axis motion stage, and the Y-axis motion stage can load the target wafer to move the target wafer longitudinally. The above-mentioned motion controller can be a chip such as a microcontroller unit (MCU), which can generate control instructions to control the movement of the motion stage. The motion platform can move according to the target motion trajectory, which includes but is not limited to a spiral trajectory, a concentric circle trajectory, a square trajectory, a polygonal trajectory, and a horizontal and vertical trajectory. For ease of description, this application takes a spiral trajectory as an example. For ease of understanding, please refer to Figure 2 , Figure 2 is a schematic diagram of the spiral trajectory provided by this application. Figure 2 As shown, the spiral trajectory can be a spiral line, and the spiral trajectory can include multiple sampling points ( Figure 2 Only some sampling points are shown in the figure), each sampling point can correspond to a movement radius and a sampling time.

[0034] In some possible implementations, such as Figure 1 As shown, the above working system may also include a laser emitting device, which can emit laser to illuminate the target wafer. The laser can be a monochromatic light beam, such as a white light beam, a red light beam, etc. When the laser is irradiated onto the surface of the target wafer, a light spot of a specific shape, such as a rectangular light spot, etc., can be formed. For ease of understanding, please refer to Figure 3 , Figure 3 is a schematic diagram of the light spot provided by this application. Figure 3As shown, a light spot with a length of h and a width of w can be generated on the surface of the target wafer, wherein 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, h and w are fixed values. It should be noted that the power of the laser is controlled by the power of the laser emitting device, and the laser can be adjusted by adjusting the power of the laser emitting device, wherein the higher the power of the laser emitting device, the higher the laser power; the lower the power of the laser emitting device, the lower the laser power. Optionally, the laser emitting device can be integrated into the wafer defect detection system, or it can be set outside the wafer defect detection system, which can be 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 terminal equipment and analog-to-digital converters, and may also include laser emitting equipment, which can be determined according to the actual product form, and is not limited here.

[0035] In some possible implementations, such as Figure 1 As shown, the above working system may also include a photomultiplier tube. After the laser emitted by the laser emitting device irradiates the target wafer, the target wafer can reflect the light beam in the light spot area, and then converge the light beam to the photomultiplier tube through a lens and other equipment to trigger the photomultiplier tube to sample the light intensity of the light spot. The above photomultiplier tube can convert the optical signal into an electrical signal, that is, the photomultiplier tube can receive the optical signal generated by the light beam in the light spot area reflected by the target wafer under 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 above first light intensity analog signal is an electrical signal, which 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 above photomultiplier tube can convert a weak optical signal into a clear electrical signal. In actual application scenarios, the photomultiplier tube can also be replaced by other devices that can generate a first light intensity analog signal based on the optical signal of the light beam reflected by the target wafer, and this application is not limited. The photomultiplier tube can be integrated into the wafer defect detection system or can be set outside the wafer defect detection system. The specific form can be determined according to the actual application scenario, and no limitation is made here. In other words, the wafer defect detection system can include terminal equipment and analog-to-digital converters, and can also include laser emission equipment and photomultiplier tubes. The specific form can be determined according to the actual product form, and no limitation is made here.

[0036] In some feasible implementations, the analog-to-digital converter may obtain multiple first light intensity analog signals from the photomultiplier tube to obtain multiple first light intensity analog signals when the target wafer passes through multiple sampling points, one first light 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 multiple sampling moments may be determined according to the sampling frequency of the analog-to-digital converter, and then multiple sampling points may be determined in the target motion trajectory based on the above time interval.

[0037] See also Figure 4 , Figure 4 Schematic diagram of the change of the first light intensity simulation signal provided by the present application. Figure 4 As shown, the horizontal axis is the sampling time of the sampling point corresponding to the first light intensity analog signal, and the vertical axis is the signal intensity of the first light intensity analog signal. Figure 4 The convex area in the first light intensity simulation signal curve shown in can be used to indicate that there may be a wafer defect in the spatial position corresponding to the convex area. By analyzing the critical value of the convex area, the range of the wafer defect can be determined. For example, by analyzing the sampling time corresponding to the initial boundary point of the convex area, the sampling point corresponding to the sampling time can be determined, and then the initial position of the wafer defect can be determined by the sampling point (such as Figure 4 Similarly, the sampling point corresponding to the sampling time can be determined by analyzing the sampling time corresponding to the end boundary point of the convex area, and then the end position of the wafer defect can be determined by the sampling point (such as Figure 4 Therefore, the position and size of the wafer defect can be determined by the initial position and end position of the wafer defect.

[0038] In some feasible embodiments, the analog-to-digital converter can obtain the first light intensity analog signal from the photomultiplier tube when the target wafer moves to the sampling point when the laser provides illumination. After the analog-to-digital converter obtains the first light intensity analog signal, it can perform analog-to-digital conversion on the first light intensity analog signal to generate a first signal (also referred to as a first light intensity digital signal), thereby realizing a single sampling of the light intensity signal of the target wafer (also referred to as 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 of the first signal based on multiple target sampling points with equal spatial intervals (also referred to as equal spatial interval sampling). Among them, the terminal device can obtain multiple first signals of the target wafer moving based on the target motion trajectory, one first signal corresponds to a sampling point in the target motion trajectory, and the time interval of the sampling moments corresponding to each adjacent two sampling points is the same. The terminal device can also obtain the motion parameters of the target wafer when it passes through each sampling point during the motion process based on the target motion trajectory. The above motion parameters may include sampling time and motion speed, and then the spatial interval between each adjacent two 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, wherein the equal spatial interval sampling is implemented based on the spatial position of the sampling points, and the spatial interval (i.e., the interval of the spatial position) between the two sampling points corresponding to the two second signals obtained by each two adjacent samplings is the target spatial interval. The terminal device can also generate a signal envelope based on the multiple second signals, and then perform defect pre-inspection on the target wafer based on the above signal envelope to adjust the power of the laser based on the result of the defect pre-inspection.

[0039] In some feasible implementations, the terminal device may obtain from the analog-to-digital converter a plurality of first signals generated by the analog-to-digital converter performing analog-to-digital conversion on a plurality of first light intensity analog signals. The above-mentioned first light intensity analog signal is obtained by the analog-to-digital converter from the time interval of the photomultiplier tube based on a plurality of sampling points in the target motion trajectory, 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. The terminal device may obtain through the motion controller the sampling moment when the target wafer passes through each sampling point in the process of moving based on the target motion trajectory and the movement speed of the target wafer, and obtain the time interval between the two adjacent sampling points based on the sampling moment of the two adjacent sampling points, and calculate the space interval between the two adjacent sampling points based on the time interval and the movement speed. For example, the terminal device may obtain through the motion controller the sampling moment of the first sampling point (such as 1 microsecond) and the linear speed of the target wafer when passing through the first sampling point (such as 1 meter / second). When the terminal device detects that the target wafer passes through the second sampling point, the terminal device may obtain the sampling moment of the second sampling point (such as 2 microseconds) and the linear speed of the target wafer when passing through the second sampling point (such as 1 meter / second), and so on. The terminal device can calculate the difference between the sampling moments of the first sampling point and the second sampling point, and obtain that the time interval between the sampling moments of the first sampling point and the second sampling point is 1 microsecond. It should be noted that, since the time interval between the sampling moments of each two adjacent sampling points in the multiple sampling points is equal, it is only necessary to calculate the time interval once in the actual application scenario. Optionally, the time interval of the above sampling moments may not be calculated, but may be directly obtained by the device parameter setting of the analog-to-digital converter.

[0040] Optionally, in some feasible implementations, the target wafer may move at a constant linear velocity, and the terminal device may 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 motion stage to move at a constant linear velocity, the motion velocity in the motion parameter obtained by the terminal device is the linear velocity. For example, if the terminal device detects that the linear velocity of the target wafer during the process of moving from the first sampling point to the second sampling point is 1 m / s, and the time interval between the sampling moments of the first sampling point and the second sampling point is 1 microsecond, then the spatial interval between the first sampling point and the second sampling point can be calculated to be 1 micron.

[0041] Optionally, in some feasible implementations, the target wafer may also move at a constant angular velocity. In this case, the terminal device may 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 above movement angle in the spiral trajectory based on the movement angle, and determine the above arc length as the spatial interval between two adjacent sampling points. When the motion controller controls the motion stage to move at a constant angular velocity, the movement speed in the motion parameter obtained by the terminal device is the angular velocity. For example, if the terminal device detects that the angular velocity of the target wafer during the process of moving from the second sampling point to the third sampling point is 360° / second, and the time interval between the sampling moments of the first sampling point and the second sampling point is 1 microsecond, then the movement angle can be calculated to be 0.00036°, and then the above movement angle is substituted into the arc length calculation formula to obtain the spatial interval (such as 1 micron) between the first sampling point and the second sampling point.

[0042] It can be understood that since the movement speed can be detected in real time by the motion controller that controls the movement of the motion platform, 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.

[0043] In some feasible implementations, the multiple sampling points in the target motion trajectory may include multiple target sampling points, 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 each two adjacent samplings are two adjacent target sampling points. Among them, the terminal device can obtain the target spatial interval, and traverse multiple sampling points based on the spatial interval between each two adjacent sampling points, and then select multiple target sampling points from the multiple sampling points, wherein the spatial interval between each two adjacent target sampling points is equal to the target spatial interval. It can be understood that the terminal device can determine the 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 in the order of sampling time, or the reference sampling point can be determined by a preset selection rule, or a sampling point can be selected as the reference sampling point by other means, and this application does not limit it. The above traversal order can be determined in the order of sampling time, or in other orders, and this application does not limit it. Taking the example that the terminal device determines the sampling point with the earliest sampling time as the reference sampling point, the terminal device can obtain the spatial distance between each sampling point after the reference sampling point and the target sampling point based on the spatial interval between each two adjacent sampling points. The terminal device can also determine the sampling point closest to the reference sampling point and whose spatial distance from the reference sampling point is equal to the target spatial interval as an 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. In other words, the above process of determining the reference sampling point and the equidistant sampling point can be repeated.

[0044] 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. Figure 5 , Figure 5 is a schematic diagram of the location of the sampling points provided in this application. Figure 5 As shown, if the terminal device selects sampling point 1 as the reference sampling point, sampling point 1 can be used as the origin (the point with coordinates of 0), and the coordinate axis indicating the spatial position can be established according to the positive direction of the traversal order as the positive direction of the X-axis. The above-mentioned coordinate axis includes the X-axis and the Y-axis, and a unit length is 1 micron. 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). It can be calculated that the spatial interval between sampling point 1 and sampling point 2 is 1 micron, the spatial interval between sampling point 2 and sampling point 3 is 1 micron, and the spatial interval between sampling point 1 and sampling point 3 is 2 microns. If the target spatial interval obtained by the terminal device is 2 microns, the terminal device can determine sampling point 3, which has a spatial interval of 2 microns with the reference sampling point (sampling point 1), as an equidistant sampling point, thereby determining 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 points may be performed cyclically, and the terminal device may use the above sampling point 3 as the reference sampling point in the next process, thereby determining the equidistant sampling points in the next process based on the sampling point 3.

[0045] In some feasible implementations, the terminal device may select the first signal corresponding to each target sampling point from the multiple first signals as the second signal to obtain multiple second signals. 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, 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, the third light intensity digital signal is selected as the second second signal, and so on, until the first signals corresponding to all 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 spatial interval. Since the spatial interval between each two adjacent target sampling points is the same, it can be ensured that the number of sampling points in two wafer defects of the same size is also the same, thereby improving the accuracy of the signal envelope generated by the second signal, 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 results; in addition, the secondary sampling of the first signal can eliminate unnecessary data in the first signal and reduce the interference caused by excessive data, thereby further improving the detection speed and detection accuracy of wafer defects.

[0046] In some feasible implementations, the above-mentioned wafer defect detection system may further include a filter ( Figure 1 The 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, which is not limited in this application. The filter may 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.

[0047] By adopting the present application, a plurality of first signals with the same time interval of sampling points 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 can be obtained and the spatial interval between each two adjacent sampling points can be calculated based on the motion parameters, the plurality of first signals corresponding to the plurality of sampling points can be sampled at equal spatial intervals to obtain a plurality of second signals, a signal envelope can be generated based on the plurality of second signals, a defect pre-inspection of the target wafer can be performed based on the signal envelope to adjust the power of the laser based on the result of the defect pre-inspection; a first light intensity analog signal can be obtained through an analog-to-digital converter in the wafer defect detection system and a first signal can be generated through analog-to-digital conversion; a light intensity of a light spot generated by a moving target wafer under laser illumination can be sampled through a photomultiplier tube in the wafer defect detection system to obtain a first light intensity analog signal; a target wafer can be irradiated with a laser and a light spot can be generated 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 adjustment accuracy of laser power is high, and the applicability is strong.

[0048] The present application also provides a wafer defect detection method, which can improve the pre-detection accuracy of wafer defects, improve the accuracy of adjusting the laser power, and enhance applicability. Figure 6 , Figure 6 Schematic diagram of the process of wafer defect detection method provided by the present application. For the convenience of description, the present application is described with the terminal device described in the first embodiment as the execution subject. Figure 6 As shown, the above wafer defect detection method may include the following steps: Step S101, obtaining multiple first signals of the target wafer, wherein the above-mentioned first signals are light intensity digital signals obtained by sampling the light intensity signal of the above-mentioned target wafer moving based on the target motion trajectory when the laser provides illumination, wherein one of the above-mentioned first signals corresponds to a sampling point in the above-mentioned target motion trajectory, and the time interval between the sampling moments corresponding to each two adjacent sampling points in the above-mentioned target motion trajectory is the same.

[0049] In some feasible embodiments, the terminal device may obtain multiple first signals of a target wafer moving based on a target motion trajectory when a laser provides illumination. The target motion trajectory may be a spiral trajectory, and the target motion trajectory may include multiple sampling points, one sampling point corresponds to a sampling moment, and the target wafer may be carried by a moving table and move with the moving table. It is understandable that as the movement time of the target wafer (the above movement time is indicated by the sampling moment) increases, the movement distance of the target wafer based on the target motion trajectory will also increase, so the position of sampling the target wafer can be determined by determining the sampling moment of the target wafer. The multiple first signals can be obtained by high-frequency, equally timed sampling, so among the multiple sampling points corresponding to the multiple first signals, the time interval between the sampling moments of each two adjacent sampling points is the same.

[0050] In some feasible implementations, the terminal device may obtain multiple first signals from an analog-to-digital converter. The first signal is obtained by performing analog-to-digital conversion on the first light intensity analog signal by the analog-to-digital converter, that is, the first signal is obtained by sampling the target wafer once by the analog-to-digital converter. The above-mentioned first light intensity analog signal is obtained from the photomultiplier tube at equal time intervals based on multiple sampling points in the target motion trajectory of the target wafer by the analog-to-digital converter, and the time interval between the sampling moments of each two adjacent sampling points is the same. The above-mentioned time interval is obtained by the device parameters of the analog-to-digital converter, such as the sampling frequency of the analog-to-digital converter.

[0051] In some feasible implementations, the first light intensity analog signal can be obtained from the photomultiplier tube by an analog-to-digital converter according to its own sampling frequency, that is, the analog-to-digital converter can obtain the first light intensity analog signal from the photomultiplier tube once every period of time. For example, if the sampling frequency of the analog-to-digital converter is 1 microsecond / time (i.e., sampling once every 1 microsecond), the time interval between the sampling moments of each two adjacent sampling points in the target motion trajectory can be set to 1 microsecond. Therefore, whenever the target wafer passes through the sampling point, the terminal device can obtain from the analog-to-digital converter the first signal obtained by the analog-to-digital converter by 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.

[0052] Step S102 , obtaining motion parameters of the target wafer when it passes through each of the sampling points in a process of moving along the target motion trajectory, and calculating a spatial interval between each two adjacent sampling points based on the motion parameters.

[0053] In some feasible implementations, the terminal device may obtain the motion parameters of the target wafer when it passes through each sampling point, and the above motion parameters may be the motion speed of the target wafer and the sampling time of the passed sampling points. The terminal device may obtain the motion parameters once when the target wafer passes a sampling point, or may obtain the motion parameters once at a certain time interval (for example, obtaining the motion parameters once every 1 microsecond), which is not limited in this application.

[0054] In some feasible implementations, the motion parameters of the target wafer when passing through each sampling point in the process of moving based on the target motion trajectory may include the sampling time of the sampling point and the motion speed of the target wafer. The sampling time of the above sampling point can also be regarded as the sampling time of the target wafer. Figure 1As shown, the target wafer can be loaded on the moving table, and the movement of the target wafer based on the target motion trajectory can be controlled by the moving table, and the terminal device can obtain the sampling time and movement speed of the target wafer passing through each sampling point in the process of moving based on the target motion trajectory from the motion controller. Among them, one sampling point corresponds to one sampling time and one movement speed. It should be noted that in the scanning process of the spiral trajectory, when the moving table carries the target wafer to move, the corresponding movement radius of the sampling point in the spiral trajectory is greater than the movement radius threshold, the moving table can carry the target wafer to move at a constant angular velocity; when the moving table carries the target wafer to move, the corresponding movement radius in the spiral trajectory is less than or equal to the movement radius threshold, the constant linear velocity movement is adopted, which can reduce the scanning error caused by the excessive linear velocity when scanning the target wafer in motion from the outside to the inside in the scanning spiral trajectory to the area close to the spiral center. Optionally, when the moving table carries the target wafer to move, it can also first perform constant angular velocity movement, and then perform constant linear velocity movement, and the wafer can be scanned from the inside to the outside. Therefore, in this application, the above-mentioned motion speed used to calculate the spatial position of the sampling point can be an angular velocity or a linear velocity, which should be determined according to the specific form of the product, and this application does not impose any restrictions. The terminal device can calculate the time interval between two adjacent sampling points based on the sampling moments of the two adjacent sampling points, and then calculate the spatial interval between the two adjacent sampling points based on the time interval and the motion speed (angular velocity or linear velocity).

[0055] For example, if the target wafer moves at a constant linear velocity from the first sampling point (i.e., the initial sampling point) in the target motion trajectory to the second sampling point, the terminal device can obtain the linear velocity (e.g., 1 m / s) of the target wafer when it passes the first sampling point and the linear velocity (e.g., 1 m / s) of the target wafer when it passes the second sampling point from the motion controller, and then calculate the spatial interval based on 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 from the second sampling point to the third sampling point, the terminal device can obtain the angular velocity (e.g., 360° / s) of the target when it passes the third sampling point from the motion controller, and then calculate the motion 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 motion angle based on the arc length calculation formula adapted to the spiral trajectory, and then determine the arc length as the spatial interval between two adjacent sampling points. For example, if the terminal device detects that the target wafer moves from the first sampling point to the second sampling point with an angular velocity of 360° / second and a time interval of 1 micron, the movement angle can be calculated to be 0.00036°, and the spatial interval can be calculated based on the above movement angle and arc length calculation formula.

[0056] In some feasible implementations, the terminal device can calculate the time interval between two adjacent sampling points by calculating the difference between the sampling moments of the two adjacent sampling points. For example, the time interval between the sampling moments of the first sampling point and the second sampling point is 1 microsecond, and the time interval between the sampling moments of the second sampling point and the third sampling point is also 1 microsecond. By analogy, the time interval between the sampling moments of each two adjacent sampling points is 1 microsecond. It should be noted that since the time interval between the sampling moments of each two adjacent sampling points in the multiple sampling points is equal, it is only necessary to calculate the time interval once in the actual application scenario. Optionally, the above time interval can also be obtained from the device parameters of the analog-to-digital converter, and the above sampling moments can also be recorded in other ways and the time interval between two adjacent sampling points can be calculated by a calculation method matching the recording method. The above method for calculating the time interval is only a feasible example provided by this application, and this application does not limit the calculation process of the time interval.

[0057] Step S103, sampling the plurality of first signals corresponding to the plurality of sampling points at equal spatial intervals 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.

[0058] In some feasible implementations, the terminal device may 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 signal is selected from the multiple first signals, the number of the above-mentioned first signals is greater than or equal to the number of the above-mentioned second signals. The terminal device may determine a reference sampling point from multiple sampling points, for example, traverse multiple sampling points in sampling time order, and determine the sampling point with the earliest sampling time as the reference sampling point, or, may determine a sampling point from multiple sampling points based on a preset selection rule as the reference sampling point, and this application does not limit it. The terminal device may obtain the spatial distance between each sampling point and the reference sampling point based on the spatial interval between each adjacent two sampling points in each sampling point. When the terminal device detects the first sampling point whose spatial distance to the reference sampling point is equal to the target spatial distance in the traversal order, the sampling point is determined as an equidistant sampling point.

[0059] The above process of determining the reference sampling point and the equidistant sampling point can be performed cyclically. In other words, the process of determining two adjacent target sampling points can be performed cyclically. For example, the terminal device can sequentially traverse the above multiple sampling points, and after determining an equidistant sampling point, use the equidistant sampling point as the reference sampling point in the next determination process to determine the equidistant 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.

[0060] For easier understanding, please also refer to Figure 7 , Figure 7 is another schematic diagram of the location of the sampling points provided in this application. Figure 7As shown, assuming that the above target spatial interval is 4 microns, and the target motion 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, wherein a 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 spatial interval between sampling point 1 and sampling point 2 is 1 micron, and the spatial interval between sampling point 1 and sampling point 2 is not equal to the target spatial interval, so 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 spatial interval between sampling point 2 and sampling point 3 is 1 micron, and 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 spatial 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 spatial interval between sampling point 3 and sampling point 4 is 2 microns, and 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 spatial interval, the terminal device can determine sampling point 4 as an equidistant sampling point of sampling point 1, thereby determining 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 next determination process of two adjacent target sampling points, and calculate the spatial distance between each sampling point and sampling point 4, thereby determining the equidistant sampling point of sampling point 4 in the next determination process, and so on, until 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 may first calculate the spatial interval between each two adjacent sampling points in the multiple sampling points between the sampling point to be calculated and the reference sampling point to obtain multiple spatial intervals, and then accumulate the multiple spatial intervals to obtain the spatial distance between the sampling point to be calculated and the reference sampling point. Optionally, the terminal device may also directly calculate the spatial distance based on the spatial position of each sampling point and the spatial position of the reference sampling point. Due to the different actual product forms, the acquisition method and marking method of the spatial positions of the above-mentioned multiple sampling points are different, and the calculation difficulty is also different. Therefore, it is necessary to determine the appropriate calculation method according to the actual product form, and this application does not limit it.

[0061] In some feasible implementations, the terminal device may select a first signal corresponding to each target sampling point from a plurality of first signals as a second signal based on a plurality of target sampling points, thereby obtaining a plurality of second signals. Figure 7 As shown, sampling point 1 corresponds to the first first signal (which can be recorded as first signal 1), sampling point 2 corresponds to the second first signal (which can be recorded as first signal 2), sampling point 3 corresponds to the third first signal (which can be recorded as first signal 3), sampling point 4 corresponds to the fourth first signal (which can be recorded as first signal 4), and so on. If the terminal device determines that sampling point 1 is the first target sampling point, first signal 1 can be selected as the first second signal; if the terminal device determines that sampling point 4 is the second target sampling point, first signal 4 can be selected as the second second signal, and so on, until the first signals corresponding to all target sampling points are selected.

[0062] It should be noted that after the above-mentioned equal spatial interval sampling of multiple first signals, the terminal device can obtain at least three second signals, and the number of the above-mentioned second signals is less than or equal to the number of first signals. In a feasible implementation, after the above-mentioned 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 each two adjacent first signals is the target spatial interval, at least three second signals can be obtained by equal spatial interval sampling based on at least three first signals, and 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 first signal 1, first signal 2 and first signal 3), wherein the spatial position of sampling point 1 corresponding to first signal 1 is recorded as (0, 0), the spatial position of sampling point corresponding to first signal 2 is recorded as (1, 0), and the spatial position of sampling point corresponding to first signal 3 is recorded as (2, 0), and the target spatial interval is 1 micron, then the spatial distance between the above-mentioned 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, the first signal 2 can be determined as the second second signal, and the first signal 3 can be determined as the third second signal, so that three second signals can be obtained. It can be understood that if the spatial distance between each two adjacent first signals among the multiple first signals obtained by the terminal device is the target spatial interval, then the same number of second signals as the first signals can be obtained by performing equal spatial interval sampling based on the multiple first signals.

[0063] In another feasible implementation, if the spatial distance between each adjacent two first signals in the above-mentioned multiple first signals is not the target spatial interval, at least four first signals are required to perform equal spatial interval sampling to select at least three second signals, and 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), wherein the spatial position of first signal 1 is recorded as (0, 0), the spatial position of first signal 2 is recorded as (1, 0), the spatial position of first signal 3 is recorded as (2, 0), the spatial position of first signal 4 is recorded as (4, 0), and the target spatial interval is 2 microns. At this time, it can be calculated that the spatial distance between first signal 1 and first signal 2 is 1 micron, 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 microns, 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 the first signal 3 and the first signal 4 is 2 microns, and the spatial distance between the first signal 3 and the first signal 4 is equal to the target spatial interval, so the first signal 4 can be determined as the third second signal. It can be understood that if the spatial distance between each adjacent two first signals among the multiple first signals obtained by the terminal device is not the target spatial interval, then the multiple first signals can be sampled at equal spatial intervals to obtain second signals whose number is less than that of the first signals.

[0064] Optionally, in some feasible implementations, the terminal device may also process the above-mentioned second signal, for example, it may perform denoising and other operations to improve the accuracy of the second signal. It is understandable that when the movement speed of the target wafer changes, the number of sampling points generated in the area of ​​the same width is different, and the width of the signal envelope generated based on the sampling points is also different. The different width of the signal envelope in the area of ​​the same width affects the accuracy of wafer defect pre-inspection. Therefore, the present application adopts equal time intervals for secondary sampling to ensure that the spatial intervals between the sampling points corresponding to the two adjacent second signals are the same, thereby ensuring that the number of sampling points in the area of ​​the same width is the same, which can improve the accuracy of wafer defect pre-inspection. In addition, the use of secondary sampling can avoid the long processing time caused by directly processing the huge amount of data obtained during one sampling. The secondary sampling can remove redundant data and reduce interference while ensuring that the information indicated by the signal is basically intact, thereby improving the speed and accuracy of wafer defect pre-inspection.

[0065] Step S104 , generating a signal envelope based on the plurality of second signals, and performing 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.

[0066] In some feasible implementations, the terminal device may generate a signal envelope based on the second signal, and then analyze the potential position and shape of the wafer defect based on the shape of the signal envelope to perform defect pre-inspection on the target wafer, and adjust the power of the laser based on the detection result of the defect pre-inspection so that the power of the laser can adapt to the subsequent scanning of the target wafer. For example, the power of the laser emitting 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 laser power from being too high to damage the wafer, or the laser power from being too low to cause missed detection or misdetection of wafer defects.

[0067] See also Figure 8 , Figure 8 is a schematic diagram of the signal envelope provided by this application. Figure 8 As shown, the horizontal axis is the spatial position of the target sampling point, the vertical axis is the signal strength of the second signal, the solid arrow below the signal envelope is used to indicate the second signal, and the intersection of the solid arrow and the horizontal axis indicates the target sampling point position for secondary sampling of the terminal device ( Figure 8 Not all of them are marked, only the location of one target sampling point is shown). Figure 8 As shown, the spatial intervals between the target sampling points corresponding to each two adjacent second signals are the same. It should be noted that, since the spatial position in the present application increases with the increase of the sampling time, that is, the sampling time and the spatial position are positively correlated, in order to better understand the effect of the medium-spaced sampling in the present application, the horizontal axis of the signal envelope diagram in the present application indicates the spatial position of the target wafer. It can be understood that since the spatial intervals between each two adjacent target sampling points in the multiple target sampling points used for secondary sampling are 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 accuracy of the sampling and more accurately judging the size of the wafer defect.

[0068] In some feasible implementations, the initial position and the end position of the wafer defect can be determined according to the change rate (i.e., slope) of the signal envelope generated by 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 less than 1.4 to greater than or equal to 1.4 can be determined as the initial position of the wafer defect, as shown in FIG. Figure 8 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 greater than or equal to 1.4 to less than 1.4 can be determined as the end position of the wafer defect, as shown in FIG. Figure 8 The end position shown. Figure 8As shown, the portion between the initial position and the end position is a raised area, and the raised area is used to indicate that a wafer defect may exist at a spatial position corresponding to the raised area.

[0069] By adopting the present application, the terminal device can obtain multiple first signals of the target wafer moving based on the target motion trajectory, the first signal is a light intensity digital signal obtained by sampling the light intensity signal of the target wafer under the condition of laser illumination, wherein one first signal corresponds to a sampling point in the target motion trajectory, and the time interval of the sampling moments corresponding to each two adjacent sampling points in the target motion trajectory is the same. In addition, the terminal device can obtain the motion parameters of the target wafer when it passes through each sampling point 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; the multiple first signals corresponding to the multiple sampling points are sampled at equal spatial intervals to obtain multiple second signals, wherein the spatial interval between the two sampling points corresponding to the two second signals obtained by each two adjacent samplings is the target spatial interval. Based on the multiple second signals, a signal envelope is generated, and the target wafer is pre-detected for defects based on the signal envelope to adjust the power of the laser based on the result of the defect pre-detection, which can avoid the situation where 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 area of ​​the same width when the motion speed of the target wafer changes, and can ensure that the number of sampling points in the area of ​​the same width is the same, thereby improving the accuracy of wafer defect pre-detection. 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 be reduced while ensuring that the information indicated by the first signal is basically kept intact. Therefore, the speed and accuracy of wafer defect pre-inspection can be improved, and the accuracy of laser power adjustment can be improved, and the applicability is strong.

[0070] See also Fig. 9 , Fig. 9 Schematic diagram of the structure of the wafer defect detection device provided by this application. Fig. 9 The wafer defect detection device 10 shown may be a computer device having a computer program (including program code) for implementing the above-mentioned wafer defect detection method. The wafer defect detection device 10 may also be a computer program, for example, the computer program is an application software. The device may be used to execute the corresponding steps in the wafer defect detection method provided in the embodiment of the present application. Fig. 9 As shown, the wafer defect detection device 10 may include: a first acquisition module 101 , a second acquisition module 102 , a sampling module 103 and a generation module 104 .

[0071] A first acquisition module 101 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 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 each two adjacent sampling points in the target motion trajectory is the same; A second acquisition module 102 is used to acquire motion parameters of the target wafer when it passes through each of the sampling points in the process of moving according to the target motion trajectory, and calculate the spatial interval between each two adjacent sampling points based on the motion parameters; The sampling module 103 is used 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 two adjacent samplings is a target spatial interval; The generating module 104 is configured to 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 a result of the defect pre-inspection.

[0072] In some feasible implementations, the first acquisition module 101 is further used to acquire the multiple first signals generated by an analog-to-digital converter performing analog-to-digital conversion on multiple first light intensity analog signals; 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.

[0073] In some feasible implementations, the above-mentioned motion parameters include the above-mentioned sampling time and motion speed; the above-mentioned second acquisition module 102 includes: a first acquisition unit 1021 and a calculation unit 1022.

[0074] The first acquisition unit 1021 is used to acquire, through 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 motion speed of the target wafer; The calculation unit 1022 is used to obtain the time interval between the two adjacent sampling points based on the sampling moments of the two adjacent sampling points, and to obtain the spatial interval between the two adjacent sampling points based on the time interval and the movement speed.

[0075] In some feasible implementations, the above-mentioned movement speed includes a linear speed; and the above-mentioned calculation unit 1022 includes a first calculation subunit 10221 .

[0076] The first calculation subunit 10221 is used for calculating 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.

[0077] In some feasible implementations, the movement speed includes an angular velocity, and the target movement trajectory includes a spiral trajectory; the calculation unit 1022 includes a second calculation subunit 10222 and a third calculation subunit 10223 .

[0078] A second calculation subunit 10222 is used to generate a movement angle of the target wafer based on a product of the angular velocity and the time interval when the target wafer moves at a constant angular velocity; The third calculation subunit 10223 is used 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.

[0079] In some feasible implementations, the two sampling points corresponding to the two second signals obtained from every two adjacent 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 .

[0080] The second acquisition unit 1031 is used to acquire the above target space interval; A traversal unit 1032 is used to traverse the plurality of sampling points based on the spatial interval between each two adjacent sampling points, and select 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; The selection unit 1033 is configured to select the first signal corresponding to each of the target sampling points from the multiple first signals as the second signal to obtain the multiple second signals.

[0081] In some feasible implementations, the traversal unit 1032 includes: The first determining subunit 10321 is used to 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 second determining subunit 10322 is used to determine the sampling point that is closest to the reference sampling point and whose spatial distance to the reference sampling point is equal to the target spatial interval as an equidistant sampling point, so as to determine the reference sampling point and the equidistant sampling point as two adjacent target sampling points.

[0082] In some feasible implementations, the implementation of each module, unit and / or sub-unit included in the above-mentioned wafer defect detection device can refer to the above-mentioned Figures 6 to 8 The implementation methods provided in each step of the wafer defect detection method shown are not described in detail.

[0083] By adopting the present application, a wafer defect detection device can obtain multiple first signals of a target wafer moving based on a target motion trajectory, wherein the first signal is a light intensity digital signal obtained by sampling the light intensity signal of the target wafer under the condition of laser illumination, wherein one first signal corresponds to a sampling point in the target motion trajectory, and the time interval of the sampling moments corresponding to each 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 it passes through each sampling point 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; perform equal spatial interval sampling on multiple first signals corresponding to multiple sampling points to obtain multiple second signals, wherein the spatial interval between the two sampling points corresponding to the two second signals obtained by each two adjacent samplings is the target spatial interval. Based on multiple second signals, a signal envelope is generated, and based on the signal envelope, a defect pre-inspection is performed on the target wafer to adjust the power of the laser based on the result of the defect pre-inspection, which can avoid the situation where the width of the signal envelope generated based on the sampling point is different due to the different number of sampling points generated in the area of ​​the same width when the motion speed of the target wafer changes, and can ensure that the number of sampling points in the area of ​​the same width is the same, thereby improving 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 be reduced while ensuring that the information indicated by the first signal is basically kept intact. Therefore, the speed and accuracy of wafer defect pre-inspection can be improved, and the adjustment accuracy of laser power can be improved, and the applicability is strong.

[0084] See also Fig.10 , Fig.10 is a schematic diagram of the structure of the terminal device provided by this application. Fig.10As shown, 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). The memory 1001 may optionally be at least one storage device located away 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 is not limited in this application. The transceiver 1003 may include a user interface and a network interface, wherein the user interface may include a display (Display) and a keyboard (Keyboard), and the optional 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 Fig.10 As 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. Figure 1 The processor 1002 described in this embodiment can execute the above Figure 1 The functions performed by the processor provided in the illustrated embodiment.

[0085] Optionally, in some feasible implementations, the terminal device 100 may further include: a controller 1004 and at least one communication bus 1005. The communication bus 1005 is used to implement connection and communication between components such as the memory 1001, the processor 1002, the transceiver 1003 and the controller 1004.

[0086] In such Fig.10 In the terminal device 100 shown, the network interface in the transceiver 1003 can provide a network communication function, and the user interface is mainly used to provide an input interface for the user; the memory 1001 can store program code or data; and the processor 1002 can be used to call the program code data stored in the memory 1001 to execute the aforementioned Figures 6 to 8 Wafer defect detection method in the illustrated embodiment. If the terminal device includes a controller 1004, the controller 1004 can receive data sent by the processor 1002 and generate control instructions to control devices such as laser emitting devices through a transceiver. Optionally, the controller 1004 can 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.

[0087] It should be understood that the terminal device 100 described in this application can execute the above Figures 6 to 8 In the wafer defect detection method of the embodiment shown, the terminal device 100 can be a separate device or can be used together with Figure 1 The analog-to-digital converters of the illustrated embodiment are integrated into the same device, which is not limited in this application. In addition, the description of the beneficial effects of adopting the same method is not repeated.

[0088] In addition, it should be pointed out here that: the embodiment of the present application also provides a computer-readable storage medium, and the computer-readable storage medium stores a computer program executed by the wafer defect detection method mentioned above, and the computer program includes program instructions. When the processor executes the program instructions, the above-mentioned Figures 6 to 8 The above-mentioned wafer defect detection method provided by the illustrated embodiment is therefore not described in detail. In addition, the description of the beneficial effects of adopting the same method is not described in detail. For technical details not disclosed in the computer-readable storage medium embodiment involved in this application, please refer to the description of the method embodiment of this application.

[0089] The computer-readable storage medium may be the wafer defect detection method provided in any of the aforementioned embodiments or the internal storage unit of the terminal device, such as a hard disk or memory of the terminal device. The computer-readable storage medium may 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. Furthermore, the computer-readable storage medium may also include both an internal storage unit and an 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 may also be used to temporarily store data that has been output or is to be output.

[0090] In addition, it should be noted that: the embodiment of the present application also provides 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 above Figures 6 to 8 The method provided by the illustrated embodiment.

[0091] Those skilled in the art will appreciate that the wafer defect detection methods, systems, and terminal devices of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Professional and technical personnel may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond 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.

Images