Detection method, device and equipment for wafer edge polishing

Abstract

The application discloses a kind of detection method, device and equipment for wafer edge polishing.The detection method includes positioning to be detected wafer;Obtain the planar part topography data and curved surface part topography data of the wafer after positioning;Curve fitting is carried out to planar part topography data and curved surface part topography data respectively, obtain first curve and second curve;Feature extraction and feature point matching are carried out to curve;Based on matched feature point pair, the homography transformation matrix between two curves is calculated;Determine the coincidence area of the first curve and the second curve;Confirm the best stitching point;According to the first curve and the second curve are docked according to best stitching point, the curve after docking is used as the edge detection curve of to-be-detected wafer.By the integration design of the functions such as centering positioning of wafer, height compensation, curve fitting and topography observation, the data synchronism of multi-parameter measurement is ensured, and the accuracy and reliability of measurement result are enhanced.

Description

Technical Field

[0001] This invention relates to the field of wafer inspection technology, and in particular to an inspection method, apparatus and equipment for wafer edge polishing. Background Technology

[0002] During wafer inspection, wafer mapping mainly focuses on its internal area, while the mapping of the edge area is often neglected or not processed with sufficient precision.

[0003] For edge region inspection, existing technologies often use thickness sensors and edge sensors to map the topography of the horizontal plane and curved sections of the wafer. These sensors can provide the edge profile of the wafer, helping to detect and analyze wafer quality issues.

[0004] However, since thickness sensors and edge sensors can only detect the horizontal and arc portions of the wafer edge separately, the detection of the wafer edge requires the overall monitoring data of the wafer edge to be evaluated. Existing methods tend to directly merge the data of the horizontal and arc portions of the wafer edge together. However, this simple merging leads to low accuracy at the data fusion point, failing to fully consider the overall continuity of the curve and local morphological features, thus resulting in obvious deviations or uneven transitions.

[0005] Therefore, existing methods generally lack precise mapping methods for wafer edges, resulting in the inability to effectively identify and control defects and polishing amounts in edge areas during wafer processing and application. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a detection method, apparatus and equipment for wafer edge polishing, so as to achieve the best smooth docking of fitting curves between different morphology regions in wafer edge morphology mapping at the stitching point.

[0007] To achieve the above objectives, the present invention provides a detection method for wafer edge polishing, wherein the wafer includes a planar portion and a curved portion at the edge, comprising the following steps:

[0008] S1. Obtain planar part topography data and curved part topography data of the wafer to be inspected. The planar part topography data includes data of a straight line segment along the radial direction on the planar part of the wafer, and the curved part topography data includes data of a curved segment at a radial cross section of the curved part of the wafer.

[0009] S2. Perform curve fitting on the planar part morphology data and the curved part morphology data respectively to obtain the first curve and the second curve;

[0010] S3. Extract feature points from the first curve and the second curve respectively, and match the feature points;

[0011] S4. Based on the geometric correspondence between the matched feature point pairs, transform the geometric position of one of the first curve and the second curve so that the two feature points in each matched feature point pair coincide.

[0012] S5. For the points in the overlapping area of ​​the transformed first curve and second curve, filter them based on curvature characteristics to determine the optimal stitching point.

[0013] S6. At the optimal stitching point, the first curve and the second curve are aligned, and the aligned curve is used as the edge detection curve of the wafer to be inspected.

[0014] More preferably, in S4, the geometric correspondence is obtained by calculating the homography transformation matrix between the matched feature point pairs.

[0015] More preferably, the homography transformation matrix is ​​calculated using the following formula:

[0016]

[0017] Where M is the set of matched feature point pairs, p 1i It is a feature point located on the first curve, p 2j It is a characteristic point located on the second curve; p 1i and p 2j A set of matched feature point pairs.

[0018] More preferably, in S5, a cost function is constructed to filter points within the overlapping region. The cost function is set to evaluate the merits of points within the overlapping region as stitching points based on curvature features.

[0019] Furthermore, the cost function is constructed according to the following formula:

[0020]

[0021] Where R is the set of points within the overlapping region, p k It is a point in R, ω k It is assigned to p k The weights are set as a function of the curvature or curvature change of the points, d(p k， p) is a point p k The distance to the suture point p.

[0022] Furthermore, weights are set based on the curvature or rate of change of curvature of the points within the overlapping region. The stitching point that minimizes the cost function is the optimal stitching point.

[0023] More preferably, in S2, the step of performing curve fitting on the planar part topography data and the curved part topography data to obtain the first curve and the second curve includes:

[0024] Curve fitting is performed on the planar part morphology data and curved part morphology data of the upper surface of the wafer to be inspected to obtain the first curve and the second curve of the upper surface. The first curve and the second curve of the upper surface are then stitched together according to the steps described in S3-S6.

[0025] And / or perform curve fitting on the planar part topography data and curved part topography data of the lower surface of the wafer to be inspected to obtain the first curve and the second curve of the lower surface; stitch and connect the first curve and the second curve of the lower surface according to the steps described in S3-S6.

[0026] In a further preferred embodiment, S0 is included before S1: positioning the wafer to be tested. Step S0 includes centering the wafer to be tested and height positioning the wafer to be tested.

[0027] A further preferred method for centering and positioning the wafer to be inspected includes:

[0028] Place the wafer to be tested at the test position and measure the eccentricity of the wafer to be tested;

[0029] Adjust the center position of the wafer to be tested based on the obtained eccentricity.

[0030] Furthermore, the measurement of the eccentricity of the wafer under test includes the following steps:

[0031] The amount of light leakage after the emitted detection light passes through the wafer under test is measured by an eccentric sensor.

[0032] The edge points of the wafer to be tested are determined based on the amount of light leakage, and the actual center position of the wafer to be tested is determined based on the edge points.

[0033] The eccentricity is calculated based on the distance between the predetermined center and the actual center.

[0034] Furthermore, the height positioning of the wafer to be inspected includes:

[0035] The distance A from the laser to the upper surface of the wafer to be inspected is measured using an upper thickness sensor;

[0036] The distance B from the laser to the lower surface of the wafer under test is measured using a thickness sensor.

[0037] Adjust the height position of the wafer to be tested so that A and B are equal.

[0038] The present invention also provides a detection device for wafer edge polishing, comprising:

[0039] The data acquisition module is used to acquire planar part topography data and curved part topography data of the wafer to be inspected; the planar part topography data includes data of a straight line segment along the radial direction on the planar part of the wafer, and the curved part topography data includes data of a curved segment at a radial cross section of the curved part of the wafer;

[0040] The data processing module performs curve fitting on the planar part topography data and the curved part topography data respectively to obtain a first curve and a second curve; extracts feature points from the first curve and the second curve respectively; matches the feature points; transforms the geometric position of one of the first curve and the second curve based on the geometric correspondence between the matched feature point pairs so that the two feature points in each matched feature point pair coincide; filters the points in the overlapping area of ​​the transformed first curve and the second curve based on curvature features to determine the optimal stitching point; and aligns the first curve and the second curve at the optimal stitching point, using the aligned curve as the edge detection curve of the wafer to be inspected.

[0041] More preferably, in the data processing module, the geometric correspondence is obtained by calculating the homography transformation matrix between the matched feature point pairs; the homography transformation matrix is ​​calculated using the following formula:

[0042]

[0043] Where M is the set of matched feature point pairs, p 1i It is a feature point located on the first curve, p 2j It is a characteristic point located on the second curve; p 1i and p 2j A set of matched feature point pairs.

[0044] Further preferably, a cost function is constructed to filter points within the overlapping region, wherein the cost function is set to evaluate the merits of points within the overlapping region as stitching points based on curvature features;

[0045] The cost function is calculated according to the following formula:

[0046]

[0047] Where R is the set of points within the overlapping region, p k It is a point in R, ω k It is assigned to p k The weights are set as a function of the curvature or curvature change of the points, d(p k， p) is a point p k The distance to the suture point p.

[0048] A further preferred embodiment also includes a wafer positioning module for positioning the wafer to be inspected;

[0049] The wafer positioning module includes an eccentric sensor, a four-axis motion platform, and a positioning judgment unit;

[0050] The four-axis motion platform is used to drive the wafer to be inspected located at the inspection position to perform linear motion in the X, Y, and Z directions, and rotate during the motion;

[0051] The eccentric sensor is used to obtain the amount of light leakage when the wafer to be tested rotates;

[0052] The positioning judgment unit measures the eccentricity of the wafer to be tested based on the amount of light leakage, adjusts the position of the wafer to be tested based on the obtained eccentricity, and obtains the thickness value of the wafer to be tested.

[0053] The position of the neutral plane is determined based on the obtained thickness value, and height compensation calibration is performed to position the wafer to be tested.

[0054] More preferably, the data acquisition module includes a thickness sensor; the thickness sensor is used to measure the planar topography data of the wafer to be inspected; it includes: an upper thickness sensor and a lower thickness sensor;

[0055] The upper thickness sensor measures the distance A from the laser to the upper surface of the wafer to be inspected;

[0056] The lower thickness sensor measures the distance B from the laser reaching the lower surface of the wafer to be inspected;

[0057] Adjust the height position of the wafer to be tested to make A and B equal, and perform height compensation calibration.

[0058] Furthermore, the data acquisition unit also includes an edge sensor, which is used to measure the surface topography data of the curved surface of the wafer to be inspected. The edge sensor includes an upper edge sensor and a lower edge sensor.

[0059] The upper edge sensor is used to collect surface topography data of the upper surface during the rise compensation calibration process of the wafer under test;

[0060] The lower edge sensor is used to collect surface topography data of the lower surface of the wafer during descent compensation calibration.

[0061] Furthermore, curve fitting was performed on the planar part morphology data and the curved part morphology data respectively to obtain the first curve and the second curve, including:

[0062] Curve fitting is performed on the planar part morphology data and curved part morphology data of the upper surface of the wafer to be inspected to obtain the first curve and the second curve of the upper surface. The first curve and the second curve of the upper surface are then stitched together.

[0063] And / or perform curve fitting on the planar part topography data and curved part topography data of the lower surface of the wafer to be inspected to obtain the first curve and the second curve of the lower surface; and stitch the first curve and the second curve of the lower surface together.

[0064] Further preferably, it also includes a camera and a compensation light source; the camera is used to acquire images of the edge and various positions of the positioning port of the wafer to be inspected.

[0065] The present invention also provides an inspection device for wafer edge polishing, the device comprising:

[0066] Memory, which stores computer program instructions;

[0067] The processor, when the computer program instructions are executed by the processor, implements the steps of the detection method for wafer edge polishing as described above.

[0068] The wafer edge polishing detection method disclosed in this application adjusts the horizontal position of the wafer by collecting eccentricity data and adjusts the vertical position of the wafer using a thickness sensor. After adjustment, the wafer is in the optimal measurement position in both the horizontal and vertical positions. Then, horizontal and curve data are scanned, the scanned data are fitted, and the intersection position is identified. The obtained optimal stitching point is used to stitch the horizontal and curve data together, ensuring that the curve at the data fusion point is smooth. This achieves the best smooth docking of the fitted curves between different morphology regions in wafer edge morphology mapping at the stitching point.

[0069] Through the integrated design of functions such as wafer centering, height compensation, curve fitting, and morphology observation, the data synchronization of multi-parameter measurements is ensured, and the accuracy and reliability of the measurement results are enhanced.

[0070] By accurately mapping the edge of the wafer, the amount of wafer polishing can be quantitatively represented. Attached Figure Description

[0071] Figure 1 This is a schematic flowchart of the detection method for wafer edge polishing according to the present invention.

[0072] Figure 2 This is a schematic diagram of the area where planar part topography data and curved part topography data are obtained in this invention.

[0073] Figure 3 This is a schematic diagram of the eccentric sensor in this invention.

[0074] Figure 4 This is a schematic diagram illustrating the principle of eccentricity calculation in this invention.

[0075] Figure 5 This is a schematic diagram of the wafer edge polishing detection device in this invention.

[0076] Figure 6 This is a schematic diagram of the structure of the four-axis motion platform of the present invention.

[0077] Figure 7 This is a schematic diagram showing the installation position of the eccentric sensor of the present invention.

[0078] Figure 8 This is a schematic diagram of the eccentric sensor of the present invention.

[0079] Figure 9 This is a schematic diagram of the installation structure of the thickness sensor in this invention.

[0080] Figure 10 This is a schematic diagram of the edge sensor structure in this invention.

[0081] Figure 11 This is a schematic diagram of the mounting structure of the camera and light source in this invention.

[0082] In the picture:

[0083] 1. Four-axis motion platform; 1a. X-axis motion stage; 1b. Y-axis motion stage; 1c. Z-axis motion stage; 1d. T-axis motion stage; 2. Edge sensor; 201. Upper sensor; 202. Lower sensor; 3. Thickness sensor; 301. Upper thickness sensor; 302. Lower thickness sensor; 4. Eccentric sensor; 401. Light emitting device; 402. Light receiving device; 5. Camera; 6. Light source; 7. Suction cup; W. Wafer. Detailed Implementation

[0084] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0085] like Figure 1 As shown, the present invention also provides a detection method for wafer edge polishing, comprising the following steps:

[0086] S1. Acquire planar surface topography data and curved surface topography data of the wafer to be inspected. The planar surface topography data includes data of a straight line segment along the radial direction on the planar surface of the wafer, and the curved surface topography data includes data of a curved segment at a radial cross-section of the curved surface of the wafer; in S1, as... Figure 2As shown, when the wafer is placed flat at the detection position, the planar part morphology data is the data of a straight line segment along the radial direction on the planar part of the wafer, specifically the first plane and the second plane that are opposite each other in the wafer thickness direction, and the curved part morphology data is the convex curved surface connecting the first plane and the second plane on the left and right sides of the wafer.

[0087] S2. Perform curve fitting on the planar part morphology data and the curved part morphology data respectively to obtain the first curve and the second curve; including:

[0088] Curve fitting is performed on the planar part morphology data and curved part morphology data obtained from the upper surface of the wafer to be inspected to obtain the first curve and the second curve of the upper surface; and / or curve fitting is performed on the planar part morphology data and curved part morphology data obtained from the lower surface of the wafer to be inspected to obtain the first curve and the second curve of the lower surface.

[0089] S3. Extract feature points from the first curve and the second curve respectively, and match the feature points; wherein, the feature points of the first curve can be points extracted from the end region of the first curve near the planar portion; the feature points of the second curve can be points extracted from the end region of the second curve near the wafer edge. Therefore, the extracted feature points must include points that appear simultaneously in both the first curve and the second curve; therefore, when performing feature point matching, it is actually matching points that appear simultaneously in both the first curve and the second curve.

[0090] S4. Based on the geometric correspondence between the matched feature point pairs, transform the geometric position of one of the first curve and the second curve so that the two feature points in each matched feature point pair coincide.

[0091] Feature point extraction and matching: Let P1 = {p 1i} and P2={p 2j Let} represent the feature point sets on curves L1 and L2, respectively, where i = 1, 2, ..., n and j = 1, 2, ..., m. Feature point pairs (p) can be obtained using a feature point extraction algorithm. 1i ,p 2j )

[0092] Furthermore, the geometric correspondence is obtained by calculating the homography transformation matrix between the matched feature point pairs; the homography transformation matrix is ​​calculated using the following formula:

[0093]

[0094] Where M is the set of matched feature point pairs, p 1i It is a feature point located on the first curve, p 2j It is a characteristic point located on the second curve; p 1iand p 2j Let argmin be a set of matched feature point pairs. argmin represents the variable value that minimizes the function, i.e., the formula obtains the matrix H that makes the transformed feature points on the second curve closest to the corresponding feature points on the first curve.

[0095] S5. For the points in the overlapping region of the transformed first curve and second curve, the optimal stitching point is determined by screening based on curvature features; the points in the overlapping region are screened by constructing a cost function, wherein the cost function is set to evaluate the merits of the points in the overlapping region as stitching points based on curvature features.

[0096] Construct the cost function according to the following formula:

[0097]

[0098] Where R is the set of points within the overlapping region, p k It is a point in R, ω k It is assigned to p k The weights are set as a function of the curvature or curvature change of the points, d(p k， p) is a point p k The distance to the suture point p.

[0099] Weights are assigned based on the curvature or rate of change of curvature at the locations of points within the overlapping region. The weight ω is... k The calculation takes into account the curvature k of the point. κ or rate of change of curvature

[0100] Here, f is a function that maps curvature and its rate of change to weights. The stitching point where the cost function is minimized is the optimal stitching point. Determining the optimal stitching point: The optimal stitching point p* is the point that minimizes the cost function C(p).

[0101] p*=argmin p∈R C(p); Use an optimization algorithm to find p*;

[0102] Based on the calculated homography transformation matrix H, curve L2 is transformed to achieve seamless alignment with L1 at p*. The transformed point p′ 2j The calculation is as follows:

[0103] p′ 2j =H·p 2j

[0104] S6. At the optimal stitching point, the first curve and the second curve are aligned, and the aligned curve is used as the edge detection curve of the wafer to be inspected.

[0105] It should be noted that S0 is included before S1: positioning the wafer to be tested, including centering the wafer to be tested and height positioning the wafer to be tested.

[0106] The process of centering and positioning the wafer to be inspected includes the following steps:

[0107] S01. Place the wafer to be inspected at the inspection position and measure the eccentricity of the wafer to be inspected; further, measuring the eccentricity of the wafer to be inspected includes:

[0108] The amount of light leakage after the emitted detection light passes through the wafer under test is measured by an eccentric sensor.

[0109] The edge points of the wafer to be tested are determined based on the amount of light leakage, and the actual center position of the wafer to be tested is determined based on the edge points.

[0110] The eccentricity is calculated based on the distance d between the predetermined center O1 and the actual center O2.

[0111] S02. Adjust the center position of the wafer to be tested based on the obtained eccentricity.

[0112] Height positioning of the wafer to be inspected includes:

[0113] The distance A from the laser to the upper surface of the wafer to be inspected is measured using an upper thickness sensor;

[0114] The distance B from the laser to the lower surface of the wafer under test is measured using a thickness sensor.

[0115] Adjust the height of the wafer to be tested so that A and B are equal. Calculate the wafer thickness t by obtaining the round-trip time of the light beam inside the wafer during measurement using the upper or lower thickness sensor.

[0116] The position of the neutral plane is determined based on t = C - (A + B), and height compensation calibration is performed.

[0117] like Figure 5 As shown, the present invention also provides a detection apparatus for wafer edge polishing, comprising the steps of implementing the above-described wafer edge polishing detection method, including:

[0118] The data acquisition module is used to acquire planar part topography data and curved part topography data of the wafer to be inspected; the planar part topography data includes data of a straight line segment along the radial direction on the planar part of the wafer, and the curved part topography data includes data of a curved segment at a radial cross section of the curved part of the wafer;

[0119] The data processing module performs curve fitting on the planar part topography data and the curved part topography data respectively to obtain a first curve and a second curve; extracts feature points from the first curve and the second curve respectively; matches the feature points; transforms the geometric position of one of the first curve and the second curve based on the geometric correspondence between the matched feature point pairs so that the two feature points in each matched feature point pair coincide; filters the points in the overlapping area of ​​the transformed first curve and the second curve based on curvature features to determine the optimal stitching point; and aligns the first curve and the second curve at the optimal stitching point, using the aligned curve as the edge detection curve of the wafer to be inspected.

[0120] The data acquisition module includes a side thickness sensor 3 for acquiring planar topography data of the wafer to be inspected and an edge sensor 2 for acquiring curved topography data;

[0121] The thickness sensor includes an upper thickness sensor 301 and a lower thickness sensor 302. During the process of the wafer under test rising from position Z1 to Z1+ΔZ (compensation), the upper thickness sensor collects data. During the process of the wafer under test falling from position Z1 to Z1-ΔZ (compensation), the lower thickness sensor collects data.

[0122] Similarly, the edge sensor is used to measure the surface topography data of the curved surface. The edge sensor, which includes an upper edge sensor and a lower edge sensor, is used to measure the surface topography data of the curved surface of the wafer to be inspected.

[0123] The upper edge sensor is used to collect surface topography data of the curved surface of the upper surface during the rise compensation calibration process of the wafer under test;

[0124] The lower edge sensor is used to collect surface topography data of the lower surface of the wafer during descent compensation calibration.

[0125] Based on the collected data, calculations are performed to fit curves. Curve fitting is performed on the planar part morphology data and the curved part morphology data respectively to obtain the first curve and the second curve, including:

[0126] Curve fitting was performed on the planar topography data of the upper surface of the wafer to be inspected to obtain the first curve and the second curve of the upper surface;

[0127] Alternatively, curve fitting can be performed on the planar topography data of the lower surface of the wafer to be inspected to obtain the first curve and the second curve of the lower surface.

[0128] like Figure 5 As shown Figure 6The diagram shows a four-axis motion platform 1 and a suction cup 7. During measurement in the measurement unit, the four-axis motion platform 1 and the suction cup 7 are used to rotate and fix the wafer W to be inspected. Specifically, the four-axis motion platform 1 includes stages 1a, 1b, 1c, and 1d that can operate independently or in concert, where 1a is an X-axis motion stage, 1b is a Y-axis motion stage, 1c is a Z-axis motion stage, and 1d is a T-axis motion stage; these stages can move precisely in predetermined X, Y, Z, and T (rotational) directions. During measurement, the suction cup 7 firmly holds the wafer W to be inspected by precisely controlled suction force, ensuring that the wafer W remains stationary under the operation of the four-axis motion platform 1. Based on this, the four-axis motion platform 1 executes movement and rotation actions according to control commands, precisely positioning the edge portion of the wafer W to be inspected to the measurement position. An edge sensor 2, a thickness sensor 3, and an eccentric sensor 4 are also included. These three sensor mechanisms are positioned around the wafer W. It also includes a camera 5 and a light source 6 for observing the surface condition of the edge portion of the wafer W to be inspected, in order to detect the polishing morphology of the wafer edge portion and the Notch (wafer notch).

[0129] It also includes a wafer positioning module for positioning the wafer to be inspected; the wafer positioning module includes an eccentric sensor, a four-axis motion platform, and a positioning judgment unit;

[0130] The four-axis motion platform is used to drive the wafer to be inspected located at the inspection position to perform linear motion in the X, Y, and Z directions, and rotate during the motion;

[0131] The eccentric sensor is used to obtain the amount of light leakage when the wafer to be tested rotates;

[0132] The positioning judgment unit performs centering positioning and height positioning of the wafer to be tested.

[0133] When performing centering and positioning of the wafer to be inspected, the following steps are taken: using an eccentric sensor to measure the amount of light leakage after the emitted detection light passes through the wafer to be inspected;

[0134] The edge points of the wafer to be tested are determined based on the amount of light leakage, and the actual center position of the wafer to be tested is determined based on the edge points.

[0135] The eccentricity is calculated based on the distance d between the predetermined center O1 and the actual center O2.

[0136] like Figure 3As shown, the eccentric sensor 4 is a high-precision optical sensor that emits a beam of light to the edge of the wafer. Ideally, when the light hits the edge of the wafer, all the light will be absorbed by the wafer or reflected back to the sensor. If the wafer is off-center, some light will "leak" out of this edge area. The sensor receives the reflected light and measures the amount of light leaking out. The amount of light leakage is related to the distance from the edge point to the predetermined center.

[0137] The eccentric sensor 4 continuously measures light leakage during wafer rotation, thereby obtaining a series of distance data from the predetermined center point to the edge. This data can be used to calculate the actual center of the wafer. For example... Figure 4 As shown, the actual center of the wafer is compared with the theoretical center, and the difference between the two is the eccentricity. The actual center position of each point on the actual circle is different, so the eccentricity for each point is also different. During wafer rotation, compensation is continuously made based on the eccentricity. The compensation amount can be automatically provided by the system, and compensation is achieved by moving a four-axis motion platform.

[0138] like Figure 7 and Figure 8 As shown, the eccentricity sensor 4 of this invention includes a light emitting device 401 and a light receiving device 402, which are mounted tangentially to the side of the wafer W, such that the edge portion of the wafer W is positioned between them. The light emitting device 401 emits a laser beam vertically downwards, precisely aligned with the edge region of the wafer W. The laser beam propagates radially along the wafer W and intersects with the wafer W at the edge region, causing a portion of the laser beam to be blocked by the edge of the wafer W. Therefore, only the unblocked laser beam can be captured by the light receiving device 402. The light receiving device 402 digitizes the received light signal through a data processing unit to calculate the diameter parameter of the wafer W. During the measurement process, the four-axis motion platform 1 rotates and moves according to predetermined control commands to measure the diameter at multiple points on the edge portion of the wafer W, obtaining continuous data on the wafer diameter, thereby calculating the eccentricity of the wafer.

[0139] When performing height positioning on the wafer to be inspected, the process includes: determining the position of the neutral plane based on the obtained thickness value and performing height compensation calibration; and positioning the wafer to be inspected, specifically including:

[0140] The distance A from the laser to the upper surface of the wafer to be inspected is measured using an upper thickness sensor;

[0141] The distance B from the laser to the lower surface of the wafer under test is measured using a thickness sensor.

[0142] Adjust the position of the wafer so that A = B; when adjusting the wafer, the thickness t of the wafer can be calculated by acquiring the round-trip propagation time of the light beam inside the wafer to be tested by the upper or lower thickness sensor during measurement.

[0143] The position of the neutral plane is determined based on t = C - (A + B), and height compensation calibration is performed.

[0144] like Figure 9 As shown, after the centering step, the point to be measured is rotated to align with the thickness sensor 3, and the thickness value at this time is recorded as a parameter for height compensation calibration. The upper thickness sensor 301 and the lower thickness sensor 302 are independently operating units, each responsible for measuring the upper and lower surfaces of wafer W. Both the upper and lower thickness sensors 301 and 302 employ laser beam focusing technology to precisely focus the laser beam onto the surface of wafer W. The thickness of the wafer is accurately calculated by measuring the time it takes for the laser beam to travel back and forth inside wafer W. The position of the neutral plane is determined by measuring the distance between the upper and lower surfaces of wafer W and the thickness sensor 3, and height compensation calibration is completed to ensure the positioning accuracy of wafer W. During calibration, A=B is set to ensure that the distances from the upper and lower surfaces to the thickness sensor 3 are equal, improving calibration efficiency and ensuring the repeatability of wafer W's positioning accuracy during measurement.

[0145] like Figure 10 As shown, to improve measurement accuracy and overcome the limitation of the measurement range of a single sensor, this application provides an upper sensor 201 and a lower sensor 202. The upper sensor 201 and lower sensor 202 in the edge sensor 2 have the same function as the thickness sensor. Sensor 201 is positioned above the edge portion of the wafer W to be inspected, and sensor 202 is positioned below the edge portion of the wafer W. During the process of the wafer W rising from position Z1 to Z1+ΔZ (compensation), edge data from the upper surface is collected. Based on the collected data, calculations are performed to fit a curve to obtain the edge features of the upper surface of the wafer W. Similarly, during the process of the wafer W descending from position Z2 to Z2+ΔZ, edge data from the lower surface is collected. Likewise, based on the collected data, calculations are performed to fit a curve to obtain the edge features of the lower surface of the wafer W.

[0146] like Figure 11 As shown, it also includes a camera and a compensation light source; the camera is used to acquire images of the edge and various positions of the positioning port of the wafer to be inspected.

[0147] In the data processing module, calculating the homography transformation matrix between two curves based on matched feature point pairs includes: calculating the homography transformation matrix between the two curves according to the following formula:

[0148]

[0149] Where M is the set of matched feature point pairs, p 1i It is a feature point located on the first curve, p 2j It is a characteristic point located on the second curve; p 1i and p 2j A set of matched feature point pairs.

[0150] Construct the cost function according to the following formula:

[0151]

[0152] Where R is the set of points within the overlapping region, p k It is a point in R, ω k It is assigned to p k The weights, d(p) k， p) is a point p k The distance to the suture point p.

[0153] Constructing a cost function within the overlapping region and identifying the optimal stitching point includes: matching weights according to the curvature or rate of change of curvature at the location of the stitching point based on the cost function; the stitching point where the cost function is minimized is the optimal stitching point.

[0154] The data processing module further includes: connecting the first curve and the second curve according to the optimal seam point, including transforming the first curve to the second curve using a homography transformation matrix based on the obtained optimal seam point, so as to achieve seamless connection between the first curve and the second curve at the optimal seam point.

[0155] The present invention also provides an inspection device for wafer edge polishing, the device comprising: a memory storing computer program instructions; and a processor that, when the computer program instructions are executed by the processor, implements the steps of the inspection method for wafer edge polishing as described above.

[0156] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for detecting wafer edge polishing, the wafer comprising a planar portion and a curved portion at the edge, characterized in that, Includes the following steps: S1. Obtain planar part topography data and curved part topography data of the wafer to be inspected. The planar part topography data includes the data of a straight line segment along the radial direction on the planar part of the wafer, and the curved part topography data includes the data of a curved segment at a radial cross section of the curved part of the wafer. S2. Perform curve fitting on the planar part morphology data and the curved part morphology data respectively to obtain the first curve and the second curve; S3. Extract feature points from the first curve and the second curve respectively, and match the feature points; S4. Based on the geometric correspondence between the matched feature point pairs, transform the geometric position of one of the first curve and the second curve so that the two feature points in each matched feature point pair coincide. S5. For the points in the overlapping area of ​​the transformed first curve and second curve, the optimal stitching point is determined by screening based on the curvature characteristics. S6. At the optimal stitching point, the first curve and the second curve are aligned, and the aligned curve is used as the edge detection curve of the wafer to be inspected. In S5, a cost function is constructed to filter points within the overlapping region. The cost function is set to evaluate the merits of points within the overlapping region as stitching points based on curvature features. Construct the cost function according to the following formula: Where R is the set of points within the overlapping region, p k It is a point in R, ω k It is assigned to p k The weights are set as a function of the curvature or curvature change of the points, d(p k， p) is a point p k The distance to the suture point p; Weights are assigned based on the curvature or rate of change of curvature of the points within the overlapping region. The stitching point that minimizes the cost function is the optimal stitching point.

2. The detection method for wafer edge polishing according to claim 1, characterized in that, In S4, the geometric correspondence is obtained by calculating the homography transformation matrix between the matched feature point pairs.

3. The detection method for wafer edge polishing according to claim 2, characterized in that, The homography transformation matrix is ​​calculated using the following formula: Where M is the set of matched feature point pairs, p 1i It is a feature point located on the first curve, p 2j It is a characteristic point located on the second curve; p 1i and p 2j A set of matched feature point pairs.

4. The detection method for wafer edge polishing according to claim 1, characterized in that, In S2, the step of performing curve fitting on the planar part topography data and the curved part topography data to obtain the first curve and the second curve includes: Curve fitting is performed on the planar part morphology data and curved part morphology data of the upper surface of the wafer to be inspected to obtain the first curve and the second curve of the upper surface. The first curve and the second curve of the upper surface are then stitched together according to steps S3-S6. And / or perform curve fitting on the planar part topography data and curved part topography data of the lower surface of the wafer to be inspected to obtain the first curve and the second curve of the lower surface; stitch and connect the first curve and the second curve of the lower surface according to steps S3-S6.

5. The detection method for wafer edge polishing according to any one of claims 1-3, characterized in that, Before S1, there is also S0: positioning the wafer to be tested. Step S0 includes centering the wafer to be tested and height positioning the wafer to be tested.

6. The detection method for wafer edge polishing according to claim 5, characterized in that, Centering and positioning of the wafer to be inspected includes: Place the wafer to be tested at the test position and measure the eccentricity of the wafer to be tested; Adjust the center position of the wafer to be tested based on the obtained eccentricity.

7. The detection method for wafer edge polishing according to claim 6, characterized in that, Measuring the eccentricity of the wafer under test includes the following steps: The amount of light leakage after the emitted detection light passes through the wafer under test is measured by an eccentric sensor. The edge points of the wafer to be tested are determined based on the amount of light leakage, and the actual center position of the wafer to be tested is determined based on the edge points. The eccentricity is calculated based on the distance between the predetermined center and the actual center.

8. The detection method for wafer edge polishing according to claim 5, characterized in that, The height positioning of the wafer to be inspected includes: The distance A from the laser to the upper surface of the wafer to be inspected is measured using an upper thickness sensor; The distance B from the laser to the lower surface of the wafer under test is measured using a thickness sensor. Adjust the height position of the wafer to be tested so that A and B are equal.

9. A detection apparatus for wafer edge polishing, used to perform the detection method for wafer edge polishing as described in claim 1, characterized in that, include: The data acquisition module is used to acquire planar part topography data and curved part topography data of the wafer to be inspected; the planar part topography data includes data of a straight line segment along the radial direction on the planar part of the wafer, and the curved part topography data includes data of a curved segment at a radial cross section of the curved part of the wafer; The data processing module performs curve fitting on the planar part topography data and the curved part topography data respectively to obtain a first curve and a second curve; extracts feature points from the first curve and the second curve respectively; matches the feature points; and transforms the geometric position of one of the first curve and the second curve based on the geometric correspondence between the matched feature point pairs so that the two feature points in each matched feature point pair coincide. Points within the overlapping region of the transformed first and second curves are selected based on curvature characteristics to determine the optimal stitching point; the first and second curves are then joined at the optimal stitching point, and the joined curve is used as the edge detection curve of the wafer to be inspected. Points within the overlapping region are selected by constructing a cost function. The cost function is set to evaluate the merits of points within the overlapping region as stitching points based on curvature features. The cost function is calculated according to the following formula: Where R is the set of points within the overlapping region, p k It is a point in R, ω k It is assigned to p k The weights are set as a function of the curvature or curvature change of the points, d(p k， p) is a point p k The distance to the suture point p.

10. The detection device for wafer edge polishing according to claim 9, characterized in that, In the data processing module, the geometric correspondence is obtained by calculating the homography transformation matrix between matched feature point pairs; the homography transformation matrix is ​​calculated using the following formula: Where M is the set of matched feature point pairs, p 1i It is a feature point located on the first curve, p 2j It is a characteristic point located on the second curve; p 1i and p 2j A set of matched feature point pairs.

11. The inspection device for wafer edge polishing according to claim 9 or 10, characterized in that, It also includes a wafer positioning module for positioning the wafer to be inspected; The wafer positioning module includes an eccentric sensor, a four-axis motion platform, and a positioning judgment unit; The four-axis motion platform is used to drive the wafer to be inspected located at the inspection position to perform linear motion in the X, Y, and Z directions, and rotate during the motion; The eccentric sensor is used to obtain the amount of light leakage when the wafer to be tested rotates; The positioning judgment unit measures the eccentricity of the wafer to be tested based on the amount of light leakage, adjusts the position of the wafer to be tested based on the obtained eccentricity, and obtains the thickness value of the wafer to be tested. The position of the neutral plane is determined based on the obtained thickness value, and height compensation calibration is performed to position the wafer to be tested.

12. The inspection device for wafer edge polishing according to claim 9 or 10, characterized in that, The data acquisition module includes a thickness sensor; the thickness sensor is used to measure the planar topography data of the wafer to be inspected; it includes an upper thickness sensor and a lower thickness sensor. The upper thickness sensor measures the distance A from the laser to the upper surface of the wafer to be inspected; The lower thickness sensor measures the distance B from the laser reaching the lower surface of the wafer to be inspected; Adjust the height position of the wafer to be tested to make A and B equal, and perform height compensation calibration.

13. The detection device for wafer edge polishing according to claim 12, characterized in that, The data acquisition module also includes an edge sensor, which is used to measure the surface topography data of the curved surface of the wafer to be inspected. The edge sensor includes an upper edge sensor and a lower edge sensor. The upper edge sensor is used to collect surface topography data of the curved surface of the upper surface during the rise compensation calibration process of the wafer under test; The lower edge sensor is used to collect surface topography data of the lower surface of the wafer during descent compensation calibration.

14. The detection device for wafer edge polishing according to claim 13, characterized in that, Curve fitting was performed on the planar part morphology data and the curved part morphology data respectively to obtain the first curve and the second curve, including: Curve fitting is performed on the planar part morphology data and curved part morphology data of the upper surface of the wafer to be inspected to obtain the first curve and the second curve of the upper surface. The first curve and the second curve of the upper surface are then stitched together. And / or perform curve fitting on the planar part topography data and curved part topography data of the lower surface of the wafer to be inspected to obtain the first curve and the second curve of the lower surface; and stitch the first curve and the second curve of the lower surface together.

15. The inspection device for wafer edge polishing according to claim 9 or 10, characterized in that, It also includes a camera and a compensation light source; the camera is used to acquire images of the edge and various positions of the positioning port of the wafer to be inspected.

16. An inspection device for wafer edge polishing, characterized in that, The device includes Memory, which stores computer program instructions; A processor, when the computer program instructions are executed by the processor, implements the steps of the detection method for wafer edge polishing as described in any one of claims 1 to 8.

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