Wafer two-dimensional warpage measuring device, method and wafer measuring system

Abstract

The application discloses a wafer two-dimensional warping degree measuring device, a wafer two-dimensional warping degree measuring method and a wafer measuring system. The wafer two-dimensional warping degree measuring device comprises a first motion platform, an image collecting device, a distance measuring module and a controller. The controller controls the first motion platform to move according to a to-be-measured point positioned by the image collecting device until the to-be-measured point coincides with a center point of a polygon formed by at least three measuring points of the distance measuring module on a wafer surface, then three-dimensional coordinate data of the at least three measuring points uploaded by the distance measuring module is read, and a two-dimensional inclination angle of the to-be-measured point is calculated according to the three-dimensional coordinate data. The application can realize accurate positioning of a to-be-measured point on a wafer and accurate measurement of the warping degree of the to-be-measured point.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wafer warping detection, in particular to a wafer two-dimensional warping degree measuring device, method and wafer measuring system. BACKGROUND

[0002] With the huge computing power demand brought by AI, higher unit computing density and lower power consumption are required, thus giving birth to the rapid development of NAND and DRAM. With the development of NAND and DRAM to 3D process structure, the line width of etching structure in semiconductor devices becomes smaller and smaller, and the etching depth becomes larger and larger, thus forming a unique high aspect ratio structure (HAR). Etching of large aspect ratio structure is a very critical and challenging process step in semiconductor device manufacturing process, which will significantly affect the performance and yield of the device. As shown in the figure, with the improvement of process technology of semiconductor memory chips, the aspect ratio gradually increases, accompanied by greater bending and warping of the wafer, resulting in a two-dimensional tilt angle of the wafer on the wafer table relative to the reference plane. CD-SAXS (critical dimension small angle X-ray scattering) measurement technology relies on model iterative fitting solution of scattering signals at different incident angles of the wafer. Figure 1

[0003] Since CD-SAXS is applied to the measurement of patterned NAND wafers, in order to accurately measure the deep hole structure unit in a specific die range on the wafer, it is necessary to first accurately measure the tilt angle caused by wafer warping, and then compensate and correct the tilt angle during the CD-SAXS measurement process. However, the existing CD-SAXS measurement technology cannot accurately position the measurement point and measure the tilt angle, resulting in inaccurate final measurement results. SUMMARY

[0004] Therefore, the present application provides a wafer two-dimensional warping degree measuring device, method and wafer measuring system to solve the problem that the existing CD-SAXS measurement technology cannot accurately position the measurement point and measure the tilt angle.

[0005] ​To solve the above technical problems, one technical scheme adopted by the present application is to provide a wafer two-dimensional warping degree measuring device, which comprises: a first moving platform, which is used to carry a wafer to be measured; an image acquisition device, which is used to shoot a wafer surface image and locate a to-be-measured point on the wafer according to the image; a distance measuring module, which forms at least three measuring points on the wafer surface, the at least three measuring points are constructed as a polygon, and the distance measuring module is used to obtain three-dimensional coordinate data of the at least three measuring points; and a controller, which is electrically connected with the first moving platform, the image acquisition device and the distance measuring module respectively, is used to control the first moving platform to move so as to make the to-be-measured point coincide with a center point of the polygon according to the to-be-measured point located by the image acquisition device, read the three-dimensional coordinate data of the at least three measuring points uploaded by the distance measuring module, and calculate a two-dimensional inclination angle of the to-be-measured point according to the three-dimensional coordinate data.

[0006] As a further improvement of the present application, the distance measuring module comprises at least three spectral confocal range finders or at least three laser interference range finders.

[0007] As a further improvement of the present application, a visual standard sample is further arranged on the first moving platform, which is used to calibrate relative spatial positions of the image acquisition device and the distance measuring module, so as to determine a relative position relationship between a field of view center of the image acquisition device and the center point of the polygon; and the controller is further used to control the first moving platform to move so as to make the to-be-measured point coincide with the field of view center, and then drive the first moving platform to move according to the relative position relationship, so as to make the to-be-measured point coincide with the center point of the polygon.

[0008] As a further improvement of the present application, the three-dimensional coordinate data of the at least three measuring points is represented as P k (x k ,y k ,z k ), wherein k=1, 2,..., L, L represents the number of measuring points, and two-dimensional coordinate of each measuring point on a vertical plane as a wafer reference datum plane is represented as P k (x k ,y k ), P k (x k ,y k ) is pre-calibrated through the visual standard sample.

[0009] A plane equation z is fitted by using a least square method:

[0010] z=Ax k +By k +C;

[0011] wherein (A, B) is a plane equation coefficient fitted by L measuring points P k , and C=-1.

[0012] The inclination angle calculation process of the plane where the measurement point is located relative to the reference plane of the wafer in the [X, Y] direction is represented as:

[0013]

[0014] wherein, is the normal vector of the plane obtained by multi-point fitting, θ x represents the inclination angle of the measurement point along the X-axis direction, θ y represents the inclination angle of the measurement point along the Y-axis direction.

[0015] As a further improvement of the present application, the distance measuring module comprises three distance meters, and the three distance measuring points formed by the three distance meters on the wafer surface are constructed into an equilateral triangle.

[0016] As a further improvement of the present application, the three-dimensional coordinate data obtained by the three distance meters is represented as P1(x1, y1, z1), P2(x2, y2, z2), and P3(x3, y3, z3), wherein the x and y coordinate values respectively represent the plane coordinate positions of the wafer surface, and the z coordinate value represents the height value of the wafer surface.

[0017] The calculation process of the two-dimensional inclination angle is represented as:

[0018]

[0019] wherein, represents the plane normal vector, P1(x1, y1, z1), P2(x2, y2, z2), and P3(x3, y3, z3) are the vector representations of the three-dimensional coordinate data, represents the normal vector module, θ x represents the inclination angle of the measurement point along the X-axis direction, θ y represents the inclination angle of the measurement point along the Y-axis direction, represents the X-axis direction vector, represents the Y-axis direction vector.

[0020] As a further improvement of the present application, it further comprises a second motion platform, and the image acquisition device and the distance measuring module are arranged on the second motion platform, and the second motion platform is used to drive the image acquisition device and the distance measuring module to move between the preset standby position and the preset measurement position.

[0021] To solve the above technical problems, another technical solution adopted by the present application is to provide a wafer two-dimensional warping degree measurement method, which is applied to one of the wafer two-dimensional warping degree measurement devices, and the wafer two-dimensional warping degree measurement device comprises a first motion platform, an image acquisition device, a distance measuring module and a controller; the method comprises the following steps: the image acquisition device shoots a surface image of a wafer on the first motion platform and sends the surface image to the controller; the controller identifies a to-be-measured point based on a visual algorithm and determines the coordinate position of the to-be-measured point; the controller drives the first motion platform until the to-be-measured point coincides with the center point of a polygon formed by at least three measurement points on the wafer surface; the distance measuring module reads three-dimensional coordinate data of the at least three measurement points and uploads the three-dimensional coordinate data to the controller, and the controller calculates a two-dimensional inclination angle of the to-be-measured point based on the three-dimensional coordinate data.

[0022] As a further improvement of the present application, after the controller calculates the two-dimensional warping degree of the to-be-measured point based on the three-dimensional coordinate data, the method further comprises the following steps: the controller periodically drives the first motion platform to move by a preset step length, so that the center point of the polygon moves to a new to-be-measured point, and each time the first motion platform moves to a new to-be-measured point, the distance measuring module acquires three-dimensional coordinate data of the new to-be-measured point, and the controller calculates a two-dimensional inclination angle of the new to-be-measured point based on the three-dimensional coordinate data of the new to-be-measured point.

[0023] To solve the above technical problems, another technical solution adopted by the present application is to provide a wafer measurement system, which comprises a light source module, a vacuum scattering tube, a detection module and one of the wafer two-dimensional warping degree measurement devices, and the wafer two-dimensional warping degree measurement device comprises a first motion platform, an image acquisition device, a distance measuring module and a controller; the X-ray emitted by the light source module passes through the vacuum scattering tube and irradiates a to-be-measured point of a wafer on the first motion platform; the controller calculates a two-dimensional inclination angle of the to-be-measured point based on the three-dimensional coordinate data uploaded by the distance measuring module; the controller controls the first motion platform to rotate for surface inclination angle compensation according to the two-dimensional inclination angle; and the detection module is used to acquire a scattering image formed by the X-ray irradiating the to-be-measured point of the wafer after the inclination angle compensation.

[0024] As a further improvement of the present application, the wafer two-dimensional warping degree measurement device further comprises a second motion platform, and the image acquisition device and the distance measuring module are arranged on the second motion platform; and the controller is further used to control the second motion platform to drive the image acquisition device and the distance measuring module to move from a preset standby position to a preset measurement position before measuring the wafer, so as to measure the two-dimensional inclination angle of the to-be-measured point and perform the inclination angle compensation, and then drive the image acquisition device and the distance measuring module to move back to the preset standby position from the preset measurement position.

[0025] The present application has the following beneficial effects:

[0026] The wafer two-dimensional warping degree measuring device of the present application positions the to-be-measured point on the wafer through the image acquisition device, then moves the wafer by moving the first motion platform, so that the to-be-measured point on the wafer coincides with the center point of the polygon formed by the at least three measuring points on the wafer surface, then obtains the three-dimensional coordinate data of the at least three measuring points by using the distance measuring module, and calculates the two-dimensional warping degree of the to-be-measured point by using the three-dimensional coordinate data of the at least three measuring points, which realizes accurate positioning of the to-be-measured point and accurate measurement of the two-dimensional warping degree of the to-be-measured point, and the two-dimensional warping degree of the to-be-measured point can be calculated only by simultaneously measuring the coordinate data of each measuring point, so that the measurement speed is faster, and the accurate measurement of the wafer in the CD-SAXS measurement technology is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Schematic diagram of wafer bending and warping;

[0028] Figure 2 Structure schematic diagram of the wafer two-dimensional warping degree measuring device of the embodiment of the present application;

[0029] Figure 3 Electric connection relationship schematic diagram of the wafer two-dimensional warping degree measuring device of the embodiment of the present application;

[0030] Figure 4 Measurement point and field of view range schematic diagram of the image acquisition device of the wafer two-dimensional warping degree measuring device of the embodiment of the present application;

[0031] Figure 5 Distance measuring instrument measurement data schematic diagram of the wafer two-dimensional warping degree measuring device of the embodiment of the present application;

[0032] Figure 6 Distance measuring instrument measurement data schematic diagram of the wafer two-dimensional warping degree measuring device of the embodiment of the present application;

[0033] Figure 7 Image acquisition device and distance measuring module movement schematic diagram of the wafer two-dimensional warping degree measuring device of the embodiment of the present application;

[0034] Figure 8 Flowchart schematic diagram of the wafer two-dimensional warping degree measuring method of the embodiment of the present application;

[0035] Figure 9 Wafer two-dimensional warping degree measuring method of the embodiment of the present application, measuring two-dimensional inclination according to preset step length schematic diagram;

[0036] Figure 10 Wafer two-dimensional warping degree measuring method of the embodiment of the present application, overall result schematic diagram of measuring two-dimensional inclination according to preset step length;

[0037] Figure 11 is a structural schematic diagram of a wafer measurement system according to an embodiment of the present application;

[0038] Figure 12 is a schematic diagram of the image acquisition device and the ranging module of the wafer measurement system according to an embodiment of the present application when moving. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0040] The terms "first", "second", "third" in the present application are only used for description purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second", "third" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise explicitly and specifically limited. All directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative spatial position, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device.

[0041] In this document, reference to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. Those skilled in the art will appreciate that embodiments described herein can be combined with other embodiments.

[0042] Figure 2 is a structural schematic diagram of a wafer two-dimensional warping degree measurement device according to an embodiment of the present application. As shown in the figure, Figure 2As shown, the wafer two-dimensional warping degree measuring device comprises a first motion platform 1, an image acquisition device 2, a distance measuring module 3 and a controller 4 (see Figure 3

[0043] The first motion platform 1 is a six-axis motion platform, which has six degrees of freedom, including three translational motion axes and three rotational degrees of freedom, so that the first motion platform 1 can drive the wafer 7 to translate or rotate.

[0044] The image acquisition device 2 is an optical microscopic camera, which is used to shoot the image of the wafer 7 on the first motion platform 1 and locate the to-be-measured point on the surface of the wafer 7 from the image. The to-be-measured point is a mark point marked on the wafer 7 in advance by using a special pattern. In the process of locating the to-be-measured point, the image acquisition device 2 scans the surface of the wafer 7 until the to-be-measured point is found.

[0045] The distance measuring module 3 is used to form at least three measuring points on the surface of the wafer 7, and a polygon can be constructed on the surface of the wafer 7 by taking the at least three measuring points as vertices. The distance measuring module 3 measures the at least three measuring points respectively to obtain at least three three-dimensional coordinate data, and each measuring point corresponds to one three-dimensional coordinate data. It should be noted that the number of sides and the shape of the polygon are not limited in the embodiment.

[0046] The controller 4 is electrically connected with the first motion platform 1, the image acquisition device 2 and the distance measuring module 3 respectively, and is used to control the work of the first motion platform 1, the image acquisition device 2 and the distance measuring module 3.

[0047] Specifically, when measuring the two-dimensional warping degree of the wafer 7, the controller 4 first obtains the locating coordinates of the to-be-measured point acquired by the image acquisition device 2, and then controls the first motion platform 1 to move according to the locating coordinates, so that the to-be-measured point on the wafer 7 coincides with the center point O2 of the polygon. Then, the controller 4 obtains the three-dimensional coordinate data of the at least three measuring points uploaded by the distance measuring module 3, and calculates the two-dimensional inclination angle of the to-be-measured point by using the three-dimensional coordinate data. The two-dimensional inclination angle is taken as the reference surface of the wafer, and the inclination angle along the X-axis direction and the inclination angle along the Y-axis direction of the measuring point constitute the two-dimensional inclination angle.

[0048] It should be noted that the center point O2 of the polygon formed by the at least three measuring points is taken as the target point in the embodiment, and each measuring point can be considered. By moving the to-be-measured point to the center point O2, the measurement result obtained finally can be more accurate.

[0049] ​The wafer two-dimensional warping degree measuring device of the embodiment positions the to-be-measured point on the wafer 7 through the image acquisition device 2, then moves the wafer 7 by moving the first motion platform 1, so that the to-be-measured point on the wafer 7 coincides with the center point O2 of the polygon formed by the at least three measuring points on the surface of the wafer 7, then obtains the three-dimensional coordinate data of the at least three measuring points by ranging with the ranging module 3, and calculates the two-dimensional warping degree of the to-be-measured point by using the three-dimensional coordinate data of the at least three measuring points, which realizes accurate positioning of the to-be-measured point and accurate measurement of the two-dimensional warping degree of the to-be-measured point, and provides guarantee for accurate measurement of the wafer 7 in the CD-SAXS measurement technology.

[0050] Further, in some embodiments, the ranging module 3 includes at least three spectral confocal range finders or at least three laser interference range finders. The spectral confocal range finder and the laser interference range finder can both be used for ranging in the embodiment, which is not limited in the embodiment.

[0051] Further, on the basis of the above-mentioned embodiment, as shown in Figure 1 and Figure 4 , the first motion platform 1 is further provided with a visual standard sample 5 for calibrating the relative spatial positions of the image acquisition device 2 and the ranging module 3 to determine the relative positional relationship between the field center O1 of the image acquisition device 2 and the center point O2 of the polygon. The controller 4 is further used to control the movement of the first motion platform 1 so that the to-be-measured point coincides with the field center O1, and then drive the first motion platform 1 to move according to the relative positional relationship so that the to-be-measured point coincides with the center point O2 of the polygon.

[0052] It should be noted that the image acquisition device 2 is preferably an optical micro camera. As shown in Figure 4 , only three measuring points are shown in Figure 4 , the field of view of the optical micro camera on the surface of the wafer 7 is a rectangular field of view (Vision), and the relative positional relationship between the field center O1 of the rectangular field of view and the center point O2 of the polygon is obtained by calibrating the optical micro camera and the ranging module 3 through the visual standard sample 5.

[0053] Specifically, in the process of scanning the surface of the wafer 7 by the optical micro camera, when the optical micro camera recognizes the to-be-measured point (such as the Mark point in Figure 4 ), the first motion platform 1 is controlled to move so that the to-be-measured point coincides with the field center O1 of the rectangular field of view, and then the first motion platform 1 is driven to move according to the relative positional relationship between the field center O1 and the center point O2 of the polygon, so that the to-be-measured point coincides with the center point O2 of the polygon, thereby completing the positioning of the to-be-measured point.

[0054] The embodiment calibrates the visual field center O1 of the image acquisition device 2 and the center point O2 of the distance measuring module 3 in advance by the visual standard sample 5. After the coordinate information of the to-be-measured point is obtained, the visual field center O1 of the image acquisition device 2 is used as a jump to realize the rapid coincidence of the to-be-measured point and the center point O2 of the distance measuring module 3, and it is no longer needed to construct a coordinate system by the to-be-measured point and the center point O2 of the distance measuring module 3, to realize the coincidence of the to-be-measured point and the center point O2 after a coordinate transformation operation, so that the calculation amount is reduced, and the measurement speed of the whole measurement process of the two-dimensional warping degree of the wafer 7 is improved.

[0055] Further, in order to facilitate calculation, in some embodiments, the distance measuring module 3 includes three distance meters, and three distance measuring points formed by the three distance meters on the surface of the wafer 7 are constructed as an equilateral triangle (as shown in Figure 4

[0056] Specifically, the equilateral triangle is a regular figure, and the center point O2, that is, the intersection point of the midlines of the three sides, can be obtained without excessive calculation.

[0057] It should be understood that, in some embodiments, the triangle formed by the three distance meters on the surface of the wafer 7 can also be a non-equilateral triangle, and other triangles can also realize the measurement of the warping degree of the to-be-measured point.

[0058] Further, in the embodiment, the calculation of the two-dimensional inclination of the to-be-measured point is described by taking three three-dimensional coordinate points obtained by the three distance meters as an example, as shown in Figure 5 and Figure 6 In the figure, Zs1, Zs2 and Zs3 respectively represent the height values measured by the three distance meters, P1, P2 and P3 respectively represent three-dimensional coordinate data of the three measuring points, a normal vector of the plane where the three measuring points are located, and the three-dimensional coordinate data obtained by the three distance meters are represented as P1(x1, y1, z1), P2(x2, y2, z2) and P3(x3, y3, z3), wherein the x and y coordinate values respectively represent the plane coordinate positions of the surface of the wafer 7, and the z coordinate value represents the height value of the surface of the wafer 7.

[0059] The calculation process of the two-dimensional inclination is represented as:

[0060]

[0061] wherein, represents a plane normal vector, P1(x1, y1, z1), P2(x2, y2, z2) and P3(x3, y3, z3) are respectively vector representations of the three-dimensional coordinate data, represents a normal vector module, and x represents the inclination of the measuring point along the X-axis direction, and y ​represents the inclination of the measuring point along the Y-axis direction, represents the X-axis direction vector, represents the Y-axis direction vector.

[0062] Further, for the case of using more than 3 range finders, assuming that L range finders are used, for one-time motion collection, the three-dimensional coordinate data of L measuring points is represented as P k (x k ,y k ,z k ), where k = 1, 2,..., L. Each measuring point P k (x k ,y k ) is calibrated by the visual standard sample 5 to pre-calibrate the relative position, which is a known parameter;

[0063] The least squares method is used to fit the plane equation z:

[0064] z = Ax + By + C;

[0065] where (A, B) is the plane equation coefficient fitted by L data points P k , and C = -1;

[0066] For more than 3 range finders, the inclination of the plane where the measured point is located relative to the [X, Y] direction of the wafer reference plane is calculated as follows:

[0067]

[0068] where, is the normal vector of the plane obtained by multi-point fitting, θ x represents the inclination of the measuring point along the X-axis direction, and θ y represents the inclination of the measuring point along the Y-axis direction. Further, on the basis of the above embodiment, as shown in Figure 2 and Figure 7 , the wafer two-dimensional warpage measurement device further comprises a second motion platform 6 electrically connected with the controller 4, and the image acquisition device 2 and the range finding module 3 are arranged on the second motion platform 6, and the second motion platform 6 is used to drive the image acquisition device 2 and the range finding module 3 to move between the preset standby position and the preset measurement position.

[0069] It should be noted that in the CD-SAXS measurement technology, the wafer 7 on the first motion platform 1 needs to be vertically irradiated by the X-rays emitted by the light source, and the image acquisition device 2 and the distance measuring module 3 may pass through the light path of the X-rays when performing two-dimensional angle measurement of the to-be-measured point, thereby causing shielding of the X-rays. Therefore, in order to avoid interference between the image acquisition device 2 and the distance measuring module 3 and the light path of the X-rays, in the embodiment, the image acquisition device 2 and the distance measuring module 3 are arranged on the second motion platform 6, and the image acquisition device 2 and the distance measuring module 3 are moved by the second motion platform 6. When two-dimensional angle measurement needs to be performed, the controller 4 controls the second motion platform 6 to move, so that the image acquisition device 2 and the distance measuring module 3 move from a preset standby position to a preset measurement position, and then the image acquisition device 2 and the distance measuring module 3 start to work to measure the two-dimensional angle of the to-be-measured point. After the measurement is completed, the controller 4 controls the second motion platform 6 to move again, so that the image acquisition device 2 and the distance measuring module 3 move from the preset measurement position to the preset standby position, thereby avoiding shielding of the X-rays.

[0070] Further, after moving the image acquisition device 2 and the distance measuring module 3 to the preset working position, the second motion platform 6 is further used to adjust the distance between the image acquisition device 2 and the distance measuring module 3 and the wafer 7, so that the image acquisition device 2 and the distance measuring module 3 perform to-be-measured point positioning and distance measurement at the same working distance.

[0071] Figure 8 is a flowchart of a wafer two-dimensional warping degree measurement method according to an embodiment of the present application. The wafer two-dimensional warping degree measurement method is applied to the wafer two-dimensional warping degree measurement device according to one of the above embodiments, and the wafer two-dimensional warping degree measurement device includes a first motion platform, an image acquisition device, a distance measuring module, and a controller. As shown in Figure 8 , the wafer two-dimensional warping degree measurement method includes the following steps.

[0072] Step S1: The image acquisition device captures a surface image of the wafer on the first motion platform and sends the surface image to the controller.

[0073] Specifically, the image acquisition device has a rectangular field of view range of 1-10 mm according to the selection of different magnifications. When collecting the surface image of the wafer, the second motion stage 6 is first moved so that the center of the microscope field of view coincides with the center of the wafer. According to the 12-inch wafer with a 300 mm diameter circular surface, the to-be-measured point is within a rough range of 40*40 mm from the center of the wafer, and the first motion stage is moved for scanning until the to-be-measured point is scanned.

[0074] Step S2: The controller identifies the to-be-measured point based on a visual algorithm and determines the coordinate position of the to-be-measured point.

[0075] It should be noted that the visual algorithm can be implemented by a machine learning algorithm.

[0076] Step S3: the controller drives the first motion platform until the to-be-measured point coincides with the center point of a polygon formed by the at least three measurement points on the wafer surface.

[0077] Step S4: the distance measuring module reads the three-dimensional coordinate data of the at least three measurement points and uploads the three-dimensional coordinate data to the controller.

[0078] Step S5: the controller calculates the two-dimensional tilt angle of the to-be-measured point based on the three-dimensional coordinate data.

[0079] Specifically, the details of steps S1-S5 of the embodiment can be referred to the above-mentioned wafer two-dimensional warping degree measuring device embodiment, which will not be described here.

[0080] It should be noted that in some embodiments, the wafer two-dimensional warping degree measuring device further comprises a second motion platform, the image acquisition device and the distance measuring module are arranged on the second motion platform, and the second motion platform is used to drive the image acquisition device and the distance measuring module to move between a preset standby position and a preset measurement position. Therefore, before step S1, it further comprises:

[0081] The controller controls the movement of the second motion platform to drive the image acquisition device and the distance measuring module to move from the preset standby position to the preset measurement position.

[0082] After step S5, it further comprises:

[0083] The controller controls the movement of the second motion platform to drive the image acquisition device and the distance measuring module to move from the preset measurement position to the preset standby position.

[0084] Specifically, in order to prevent the wafer two-dimensional warping degree measuring device from blocking the light path of X-rays when it is applied to CD-SAXS measurement technology, the image acquisition device and the distance measuring module are arranged on the second motion platform, and before CD-SAXS measurement, the image acquisition device and the distance measuring module are moved to the preset measurement position to measure the two-dimensional tilt angle of the to-be-measured point, and after the two-dimensional tilt angle measurement is completed, the image acquisition device and the distance measuring module are moved to the preset standby position to avoid blocking the light path of X-rays during CD-SAXS measurement.

[0085] It should be noted that after moving to the preset measurement position, the second motion platform is further used to fine-tune the distance between the image acquisition device, the distance measuring module and the wafer.

[0086] The wafer two-dimensional warpage measurement method of this embodiment locates the test point on the wafer using an image acquisition device, and then moves the wafer by moving a first motion platform so that the test point on the wafer coincides with the center point of the polygon formed by at least three measurement points on the wafer surface by the ranging module. The ranging module then measures the distance to obtain the three-dimensional coordinate data of at least three measurement points, and calculates the two-dimensional warpage of the test point using the three-dimensional coordinate data of at least three measurement points. This method achieves accurate positioning of the test point and accurate measurement of the two-dimensional warpage of the test point, providing a guarantee for accurate wafer measurement in CD-SAXS measurement technology.

[0087] Furthermore, in some embodiments, after step S5, the method further includes:

[0088] The controller periodically drives the first motion platform to move at a preset step size, so that the center point of the polygon moves to a new test point. Each time it moves to a new test point, it acquires the three-dimensional coordinate data of the new test point collected by the ranging module, and calculates the two-dimensional tilt angle of the new test point based on the three-dimensional coordinate data of the new test point.

[0089] Specifically, in order to achieve gridded point-by-point scanning measurements of the wafer surface along the X and Y axes, thereby constructing two-dimensional tilt angle measurement results for warped and bent wafers, in this embodiment, as follows... Figure 9 As shown, a two-dimensional coordinate system is constructed using the vertical plane as the wafer reference plane. After the two-dimensional tilt angle measurement of the test point is completed, the controller controls the first motion platform to move a preset step distance along the X-axis or Y-axis, thereby moving the center point of the polygon to a new test point. The two-dimensional tilt angle of this new test point is then calculated, and so on, to obtain a... Figure 10 The measurement results are shown.

[0090] Figure 11 This is a schematic diagram of the wafer measurement system according to an embodiment of the present invention. Figure 11 As shown, the wafer measurement system includes a light source module 100, a vacuum scattering tube 200, a detection module 300, and a wafer two-dimensional warpage measurement device 400 as described in one of the above embodiments.

[0091] The wafer two-dimensional warp measurement device 400 includes a first motion platform 1, an image acquisition device 2, a ranging module 3, and a controller (not shown in the figure).

[0092] The light source module 100 emits X-rays that pass through the vacuum scattering tube 200 and irradiate the test point on the wafer on the first motion platform 1.

[0093] The controller is configured to calculate the two-dimensional tilt angle of the to-be-measured point according to the three-dimensional coordinate data uploaded by the distance measuring module 3, and control the first motion platform 1 to rotate for surface tilt angle compensation according to the two-dimensional tilt angle.

[0094] The detection module 300 is configured to collect a scattering image formed by X-rays irradiating the to-be-measured point on the wafer after tilt angle compensation.

[0095] It should be noted that the wafer measurement system is realized based on the CD-SAXS measurement technology. The CD-SAXS measurement technology relies on model iterative fitting to solve the scattering signals at different incident angles of the wafer. In order to ensure the accuracy of the measurement results, the CD-SAXS measurement technology has strict requirements for the incident angle of the X-rays irradiating the to-be-measured point on the wafer. Therefore, in the embodiment, the tilt angle caused by the wafer warping needs to be accurately measured, and then the tilt angle compensation correction is performed during the CD-SAXS measurement process, so that the incident angle of the X-rays irradiating the wafer warping part meets the requirements.

[0096] Specifically, the first motion platform 1 is a six-degree-of-freedom motion platform, which includes three translational motion axes and three rotational degrees of freedom. In the embodiment, after the two-dimensional tilt angle of the to-be-measured point is measured by the wafer two-dimensional warping degree measurement device 400, the first motion platform 1 is controlled to rotate according to the two-dimensional tilt angle, so that the X-rays irradiating the to-be-measured point after rotation meet the incident angle requirements. The two-dimensional tilt angle includes a tilt angle along the X-axis direction and a tilt angle along the Y-axis direction. When performing tilt angle compensation, the first motion platform 1 can be first controlled to rotate around the Y-axis to overcome the tilt angle along the X-axis direction, and then controlled to rotate around the X-axis to overcome the tilt angle along the Y-axis direction. After the two-dimensional tilt angle is compensated, the light source module 100 is controlled to emit X-rays to irradiate the to-be-measured point on the wafer, and the detection module 300 is controlled to collect a scattering image formed by X-rays irradiating the to-be-measured point on the wafer after tilt angle compensation.

[0097] The wafer measurement system of the embodiment measures the two-dimensional tilt angle of the to-be-measured point on the wafer by using the wafer two-dimensional warping degree measurement device 400, compensates the two-dimensional tilt angle of the to-be-measured point according to the measurement result, and then performs CD-SAXS measurement on the compensated to-be-measured point. This ensures that the incident angle of the X-rays irradiating the to-be-measured point meets the requirements, avoids inaccurate CD-SAXS measurement results caused by wafer surface warping, and greatly improves the accuracy of CD-SAXS measurement.

[0098] Further, on the basis of the above-mentioned embodiments, in other embodiments, for example, Figure 11 and Figure 12As shown, the wafer two-dimensional warping degree measuring device 400 further comprises a second motion platform 6, and the image acquisition device 2 and the distance measuring module 3 are arranged on the second motion platform 6. The controller is further configured to control the second motion platform 6 to drive the image acquisition device 2 and the distance measuring module 3 to move from a preset standby position to a preset measurement position to measure the two-dimensional tilt angle of the to-be-measured point and compensate the tilt angle, and then drive the image acquisition device 2 and the distance measuring module 3 to move from the preset measurement position back to the preset standby position.

[0099] Specifically, in the embodiment, the image acquisition device 2 and the distance measuring module 3 are arranged on the second motion platform 6, and the image acquisition device 2 and the distance measuring module 3 are moved by the second motion platform 6. When the two-dimensional tilt angle measurement is needed, the controller controls the second motion platform 6 to move, so that the image acquisition device 2 and the distance measuring module 3 move from the preset standby position to the preset measurement position, and then the image acquisition device 2 and the distance measuring module 3 start to work to measure the two-dimensional tilt angle of the to-be-measured point. After the measurement is completed, the controller controls the second motion platform 6 to move again, so that the image acquisition device 2 and the distance measuring module 3 move from the preset measurement position to the preset standby position, thereby avoiding blocking the X-rays.

[0100] In the embodiment, the measurement steps of the wafer measurement system specifically include:

[0101] 1. The controller controls the second motion platform 6 to drive the image acquisition device 2 and the distance measuring module 3 to move from the preset standby position to the preset measurement position.

[0102] 2. The image acquisition device 2 shoots the surface image of the wafer on the first motion platform 1 and sends the surface image to the controller.

[0103] 3. The controller identifies the to-be-measured point based on a visual algorithm and determines the coordinate position of the to-be-measured point.

[0104] 4. The controller drives the first motion platform 1 until the to-be-measured point coincides with the center point of the polygon formed by at least three measurement points on the wafer surface.

[0105] 5. The distance measuring module 3 reads the three-dimensional coordinate data of the at least three measurement points and uploads the three-dimensional coordinate data to the controller.

[0106] 6. The controller calculates the two-dimensional tilt angle of the to-be-measured point based on the three-dimensional coordinate data.

[0107] 7. The controller controls the first motion platform 1 to rotate to compensate the two-dimensional tilt angle according to the two-dimensional tilt angle, and controls the second motion platform 6 to drive the image acquisition device 2 and the distance measuring module 3 to move from the preset measurement position to the preset standby position.

[0108] 8. The controller controls the light source module 100 to emit X-rays to irradiate on the to-be-measured point of the wafer.

[0109] 9. The detection module 300 collects the scatter image formed by the X-ray irradiation on the wafer after the angle compensation.

[0110] Based on the above steps, the wafer measurement system of the embodiment can complete the measurement of one to-be-measured point on the wafer. When there are multiple to-be-measured points, the above steps need to be executed multiple times to complete the measurement of multiple to-be-measured points.

[0111] It should be noted that the ranging module 3 needs to form at least three measurement points, and it has at least three range finders. When measuring multiple to-be-measured points, multiple range finders need to move repeatedly between the standby position and the measurement position, which will produce displacement errors. Specifically, the embodiment takes three range finders as an example. In the CD-SAXS measurement process, due to the uncertainty of the displacement distance of the motion platform, that is, the motion platform cannot ensure that the position is completely coincident every time it moves from one position to another, it has a certain displacement error [ΔX, ΔY] in the X and Y axis directions. At the same time, due to the spontaneous jitter effect of the motion platform, it causes the height measurement error ΔZ in the Z direction. That is, for a to-be-measured point on the wafer plane, when the three range finders are not fixed together, each range finder moves alone, and there will be an error when moving, thereby producing measurement errors [ΔX, ΔY, ΔZ] in three axes. 1,2,3 When there are N to-be-measured points, 3N measurements need to be performed, and there will be 9N measurement errors. If the three range finders move in a parallel fixed manner, the relative positions between the three range finders are fixed and will not change, so each measurement only produces one movement and only one error [ΔX, ΔY, ΔZ]. For multiple to-be-measured point measurements, the error amount is less cumulative. Therefore, in the embodiment, the at least three range finders of the ranging module 3 are fixedly arranged on the second motion platform 6, and the second motion platform 6 drives the at least three range finders to move synchronously, thereby greatly reducing the cumulative amount of errors and improving the overall measurement accuracy.

[0112] The above is only an embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent flow transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A wafer two-dimensional warpage measurement device, characterized in that, It includes: The first motion platform is used to support the wafer to be tested; An image acquisition device is used to capture images of the wafer surface and locate the test points on the wafer based on the images; A ranging module, wherein the ranging module forms at least three measuring points on the wafer surface, the at least three measuring points being constructed into a polygon, and the ranging module is used to acquire the three-dimensional coordinate data of the at least three measuring points; The controller is electrically connected to the first motion platform, the image acquisition device, and the ranging module, respectively. It is used to control the first motion platform to move according to the measurement point located by the image acquisition device, so that the measurement point coincides with the center point of the polygon. Then, it reads the three-dimensional coordinate data of the at least three measurement points uploaded by the ranging module, and calculates the two-dimensional tilt angle of the measurement point based on the three-dimensional coordinate data.

2. The wafer two-dimensional warpage measurement device according to claim 1, characterized in that, The ranging module includes at least three spectral confocal rangefinders or at least three laser interferometric rangefinders.

3. The wafer two-dimensional warpage measurement device according to claim 1, characterized in that, The first motion platform is also equipped with a visual standard sample, which is used to calibrate the relative spatial position of the image acquisition device and the ranging module, so as to determine the relative positional relationship between the field of view center of the image acquisition device and the center point of the polygon; The controller is also used to control the first motion platform to move so that the point to be measured coincides with the center of the field of view, and then drive the first motion platform to move according to the relative positional relationship so that the point to be measured coincides with the center point of the polygon.

4. The wafer two-dimensional warpage measurement device according to claim 3, characterized in that, The three-dimensional coordinate data of the at least three measurement points are represented as P. k (x k ,y k ,z k ), where k = 1, 2, ..., L, L represents the number of measurement points, and the two-dimensional coordinates of each measurement point on the wafer reference plane with the vertical plane as the reference plane are represented by P. k (x k ,y k ), P k (x k ,y k Pre-calibrated using the aforementioned visual standard sample; Fit the plane equation z using the least squares method: z=Ax k +By k +C; Where (A,B) represents the fitted L measurement points P. k The coefficients of the plane equation, C = -1; The calculation process for the tilt angle of the plane containing the test point relative to the wafer reference plane in the [X,Y] direction is expressed as follows: in, To obtain the normal vector of the plane through multi-point fitting, θ x θ represents the inclination angle of the measurement point along the X-axis. y This indicates the inclination angle of the measurement point along the Y-axis.

5. The wafer two-dimensional warpage measurement device according to claim 1, characterized in that, The ranging module includes three rangefinders, and the three rangefinders form three ranging points on the wafer surface, which together form an equilateral triangle.

6. The wafer two-dimensional warpage measurement device according to claim 5, characterized in that, The three-dimensional coordinate data acquired by the three rangefinders are represented as P1(x1,y1,z1), P2(x2,y2,z2), and P3(x3,y3,z3), where the x and y coordinate values ​​represent the planar coordinate positions of the wafer surface, and the z coordinate value represents the height of the wafer surface. The calculation process for the two-dimensional tilt angle is expressed as follows: in, Represents the plane normal vector. These are the vector representations of the three-dimensional coordinate data P1(x1,y1,z1), P2(x2,y2,z2), and P3(x3,y3,z3), respectively. Let θ represent the magnitude of the normal vector. x θ represents the inclination angle of the measurement point along the X-axis. y This indicates the inclination angle of the measurement point along the Y-axis. Represents the X-axis direction vector. This represents the Y-axis direction vector.

7. The wafer two-dimensional warpage measurement device according to claim 1, characterized in that, It also includes a second motion platform, on which the image acquisition device and the ranging module are mounted. The second motion platform is used to move the image acquisition device and the ranging module between a preset standby position and a preset measurement position.

8. A method for measuring the degree of two-dimensional warpage of a wafer, characterized in that, It is applied to the wafer two-dimensional warpage measurement device according to any one of claims 1-7, the wafer two-dimensional warpage measurement device comprising a first motion platform, an image acquisition device, a ranging module, and a controller; the method comprises: The image acquisition device captures a surface image of the wafer on the first motion platform and sends it to the controller; The controller identifies the point to be measured based on a visual algorithm and determines the coordinate position of the point to be measured. The controller drives the first motion platform until the point to be measured coincides with the center point of the polygon formed by at least three measurement points of the ranging module on the wafer surface. The ranging module reads the three-dimensional coordinate data of at least three measurement points and uploads the three-dimensional coordinate data to the controller. The controller calculates the two-dimensional tilt angle of the point to be measured based on the three-dimensional coordinate data.

9. The method for measuring the degree of two-dimensional warpage of a wafer according to claim 8, characterized in that, After the controller calculates the degree of two-dimensional warping of the point to be measured based on the three-dimensional coordinate data, it also includes: The controller periodically drives the first motion platform to move at a preset step size, so that the center point of the polygon moves to a new test point. Each time it moves to the new test point, it acquires the three-dimensional coordinate data of the new test point collected by the ranging module, and calculates the two-dimensional tilt angle of the new test point based on the three-dimensional coordinate data of the new test point.

10. A wafer measurement system, characterized in that, It includes a light source module, a vacuum scattering tube, a detection module, and a wafer two-dimensional warpage measurement device as described in any one of claims 1-7. The wafer two-dimensional warpage measurement device includes a first motion platform, an image acquisition device, a ranging module, and a controller. X-rays emitted by the light source module pass through the vacuum scattering tube and irradiate the test point of the wafer on the first motion platform. The controller calculates the two-dimensional tilt angle of the test point based on the three-dimensional coordinate data uploaded by the ranging module. The controller controls the rotation of the first motion platform based on the two-dimensional tilt angle to perform surface tilt angle compensation. The detection module is used to acquire the scattering image formed by X-rays irradiating the test point of the wafer after tilt angle compensation.

11. The wafer measurement system according to claim 10, characterized in that, The wafer two-dimensional warpage measurement device also includes a second motion platform, and the image acquisition device and the ranging module are disposed on the second motion platform; The controller is also used to control the second motion platform to move the image acquisition device and the ranging module from a preset standby position to a preset measurement position before measuring the wafer to measure the two-dimensional tilt angle of the point to be measured and to compensate for the tilt angle, and then move the image acquisition device and the ranging module from the preset measurement position back to the preset standby position.

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