Wafer two-dimensional warping degree measuring device and method and wafer measuring system

Abstract

The invention discloses a wafer two-dimensional warping degree measuring device and 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, and the controller controls the first motion platform to move according to a to-be-measured point located by the image collecting device; and reading the three-dimensional coordinate data of the at least three measuring points uploaded by the distance measuring module until the to-be-measured point coincides with the central point of the polygon formed by the at least three measuring points of the distance measuring module on the surface of the wafer, and calculating the two-dimensional inclination angle of the to-be-measured point according to the three-dimensional coordinate data. According to the invention, the to-be-measured point on the wafer can be accurately positioned, and then the warping degree of the to-be-measured point is accurately measured.

Description

Technical Field

[0001] The present application relates to the technical field of wafer warpage detection, and in particular to a device and method for measuring two-dimensional wafer warpage and a wafer measurement system. Background Art

[0002] With the huge computing power demand brought by AI, higher unit computing density and lower power consumption requirements are required, which has led to the rapid development of NAND and DRAM. As NAND and DRAM develop towards 3D process structures, the line width of the etched 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 high aspect ratio structures is a very critical and challenging process step in the semiconductor device manufacturing process, which will significantly affect the performance and yield of the device. Figure 1 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 the wafer on the wafer stage having a non-zero two-dimensional tilt angle relative to the reference plane during measurement. The CD-SAXS (critical dimension small angle X-ray scattering) measurement technology relies on the model iterative fitting solution of the scattering signal of the wafer at different incident angles.

[0003] Since CD-SAXS is used for NAND wafer measurement with patterns, in order to accurately measure deep hole structure units within a specific grain range on the wafer, it is necessary to first accurately measure the inclination angle caused by the wafer warpage, and then perform inclination compensation correction during the CD-SAXS measurement process. However, the existing CD-SAXS measurement technology cannot accurately locate the measurement point and measure the inclination angle, resulting in inaccurate final measurement results. Summary of the invention

[0004] In view of this, the present application provides a wafer two-dimensional warpage measurement device, method and wafer measurement system to solve the problem that the existing CD-SAXS measurement technology cannot accurately locate the test point and then perform tilt measurement and compensation.

[0005] In order to solve the above technical problems, a technical solution adopted in the present application is: to provide a wafer two-dimensional warpage degree measuring device, which includes: a first motion platform, the first motion platform is used to carry the wafer to be measured; an image acquisition device, used to capture the wafer surface image and locate the point to be measured on the wafer according to the image; a distance measuring module, the distance measuring module forms at least three measurement points on the wafer surface, the at least three measurement points are constructed into a polygon, and the distance measuring module is used to obtain three-dimensional coordinate data of at least three measurement points; a controller, which is electrically connected to the first motion platform, the image acquisition device, and the distance measuring module, respectively, and is used to control the movement of the first motion platform according to the point to be measured located by the image acquisition device, so that the point to be measured coincides with the center point of the polygon, and then reads the three-dimensional coordinate data of at least three measurement points uploaded by the distance measuring module, and calculates the two-dimensional inclination of the point to be measured according to the three-dimensional coordinate data.

[0006] As a further improvement of the present application, the distance measurement module includes at least three spectral confocal distance meters or at least three laser interferometer distance meters.

[0007] As a further improvement of the present application, a visual standard sample is also provided on the first motion platform, which is used to calibrate the relative spatial position of the image acquisition device and the ranging module to determine the relative position 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 movement of the first motion platform 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 position relationship so that the point to be measured coincides with the center point of the polygon.

[0008] As a further improvement of the present application, the three-dimensional coordinate data of at least three measurement points are expressed 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 vertical plane as the wafer reference plane are represented by P k (x k ,y k ), P k (x k ,y k ) Pre-calibrated by visual standard samples;

[0009] Fit the plane equation z using the least squares method:

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

[0011] Where (A, B) is the fitting L measurement points P k The plane equation coefficient, C = -1;

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

[0013]

[0014] in, To obtain the normal vector of the plane through multi-point fitting, θ x represents the inclination angle of the measuring point along the X-axis direction, θ y Indicates the inclination angle of the measuring point along the Y-axis.

[0015] As a further improvement of the present application, the distance measuring module includes three distance measuring instruments, and three distance measuring points formed by the three distance measuring instruments on the surface of the wafer form an equilateral triangle.

[0016] As a further improvement of the present application, the three-dimensional coordinate data obtained by the three rangefinders are expressed 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 position 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 expressed as:

[0018]

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

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

[0021] In order to solve the above technical problems, another technical solution adopted in the present application is: to provide a method for measuring the two-dimensional warpage degree of a wafer, which is applied to one of the above-mentioned two-dimensional warpage degree measuring devices for a wafer, and the two-dimensional warpage degree measuring device for a wafer includes a first motion platform, an image acquisition device, a ranging module and a controller; the method includes: the image acquisition device captures the 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 on the wafer surface by the ranging module; 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, and the controller calculates the two-dimensional inclination angle of the point to be measured 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 point to be measured based on the three-dimensional coordinate data, it also includes: the controller periodically drives the first motion platform to move according to a preset step size, so that the center point of the polygon moves to a new point to be measured, and each time it moves to a new point to be measured, obtains the three-dimensional coordinate data of the new point to be measured collected by the ranging module, and calculates the two-dimensional inclination angle of the new point to be measured based on the three-dimensional coordinate data of the new point to be measured.

[0023] In order to solve the above technical problems, another technical solution adopted in the present application is: to provide a wafer measurement system, which includes a light source module, a vacuum scattering tube, a detection module and one of the above-mentioned wafer two-dimensional warpage degree measuring devices, the wafer two-dimensional warpage degree measuring device includes a first motion platform, an image acquisition device, a ranging module and a controller, the X-rays emitted by the light source module pass through the vacuum scattering tube to irradiate the measured point of the wafer on the first motion platform, the controller calculates the two-dimensional inclination angle of the measured point according to the three-dimensional coordinate data uploaded by the ranging module, the controller controls the rotation of the first motion platform according to the two-dimensional inclination angle to perform surface inclination compensation, and the detection module is used to collect the scattered image formed by the X-ray irradiation of the wafer to be measured point after the inclination compensation.

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

[0025] The beneficial effects of this application are:

[0026] The wafer two-dimensional warpage degree measuring device of the present application locates the point to be measured on the wafer through an image acquisition device, and then moves the wafer by moving the first motion platform so that the point to be measured on the wafer coincides with the center point of the polygon formed by at least three measuring points on the wafer surface by the ranging module, and then uses the ranging module to measure the distance to obtain the three-dimensional coordinate data of at least three measuring points, and calculates the two-dimensional warpage degree of the point to be measured using the three-dimensional coordinate data of at least three measuring points, which realizes the precise positioning of the point to be measured and the precise measurement of the two-dimensional warpage degree of the point to be measured, and only needs to measure the coordinate data of each measuring point at the same time to calculate the two-dimensional warpage degree of the point to be measured, and the measurement speed is faster, which provides a guarantee for the precise measurement of the wafer in the CD-SAXS measurement technology. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 2 is a schematic structural diagram of a device for measuring two-dimensional warpage of a wafer according to an embodiment of the present invention;

[0029] Figure 3 Schematic diagram of electrical connection relationship of a device for measuring two-dimensional warpage of a wafer according to an embodiment of the present invention;

[0030] Figure 4 Schematic diagram of the measurement points of the wafer two-dimensional warpage measurement device and the field of view of the image acquisition device according to an embodiment of the present invention;

[0031] Figure 5 is a schematic diagram of a device for measuring two-dimensional warpage of a wafer according to an embodiment of the present invention when a range finder measures data;

[0032] Figure 6 It is a schematic diagram of a distance meter of a wafer two-dimensional warpage measurement device according to an embodiment of the present invention measuring data on a warped wafer surface;

[0033] Figure 7 2. It is a schematic diagram of the image acquisition device and the distance measurement module of the wafer two-dimensional warpage degree measurement device according to an embodiment of the present invention when they move;

[0034] Figure 8 1 is a schematic flow chart of a method for measuring a two-dimensional warpage degree of a wafer according to an embodiment of the present invention;

[0035] Fig. 9 It is a schematic diagram of a method for measuring a two-dimensional warpage degree of a wafer according to an embodiment of the present invention when measuring a two-dimensional tilt angle according to a preset step length;

[0036] Fig.10 It is a schematic diagram of the overall result of measuring the two-dimensional tilt angle according to a preset step length in the method for measuring the two-dimensional warpage degree of a wafer according to an embodiment of the present invention;

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

[0038] Fig.12 It is a schematic diagram of the image acquisition device and the distance measurement module of the wafer measurement system according to an embodiment of the present invention when they move. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] The terms "first", "second", "third" in this application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", "third" can expressly or implicitly include at least one of the features. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the embodiments of this application, all directional indications (such as up, down, left, right, front, back ...) are only used to explain the relative spatial position, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the steps or units listed, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0041] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0042] Figure 2 Schematic diagram of the structure of the device for measuring the two-dimensional warpage of a wafer according to an embodiment of the present invention. Figure 2As shown, the wafer two-dimensional warpage degree measuring device includes: a first motion platform 1, an image acquisition device 2, a distance measurement module 3 and a controller 4 (see Figure 3 shown).

[0043] The first motion platform 1 is a six-axis motion platform with 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 microscope camera, which is used to capture the image of the wafer 7 on the first motion platform 1 and locate the point to be measured on the surface of the wafer 7 from the image. The point to be measured is a mark point pre-marked with a special pattern on the wafer 7. In the process of locating the point to be measured, the image acquisition device 2 is used to scan the surface of the wafer 7 until the point to be measured 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 using 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 a three-dimensional coordinate data. It should be noted that this embodiment does not limit the number of sides and shape of the polygon.

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

[0047] Specifically, when measuring the two-dimensional warpage of the wafer 7, the controller 4 first obtains the positioning coordinates of the point to be measured obtained by the image acquisition device 2, and then controls the first motion platform 1 to move according to the positioning coordinates, so that the point to be measured on the wafer 7 coincides with the center point O2 of the polygon; then, the controller 4 obtains the three-dimensional coordinate data of at least three measuring points uploaded by the ranging module 3, and calculates the two-dimensional inclination of the point to be measured using the three-dimensional coordinate data. Among them, the two-dimensional inclination is based on the vertical plane as the wafer reference reference plane, and the inclination of the measuring point along the X-axis direction and the inclination along the Y-axis direction constitute the two-dimensional inclination.

[0048] It should be noted that this embodiment uses the center point O2 of the polygon formed by at least three measuring points as the target point, which can take each measuring point into consideration. By moving the point to be measured to the center point O2, the final measurement result can be more accurate.

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

[0050] Further, in some embodiments, the distance measurement module 3 includes at least three spectral confocal distance meters or at least three laser interferometer distance meters. Both spectral confocal distance meters and laser interferometer distance meters can be used for distance measurement in this embodiment, and this embodiment does not limit it.

[0051] Further, based on the above implementation, in other embodiments, such as Figure 1 and Figure 4 As shown, a visual standard sample 5 is also provided on the first motion platform 1, which is used to calibrate the relative spatial position of the image acquisition device 2 and the distance measurement module 3, so as to determine the relative position relationship between the field of view center O1 of the image acquisition device 2 and the center point O2 of the polygon. The controller 4 is also used to control the movement of the first motion platform 1 so that the point to be measured coincides with the field of view center O1, and then drive the first motion platform 1 to move according to the relative position relationship so that the point to be measured coincides with the center point O2 of the polygon.

[0052] It should be noted that the image acquisition device 2 is preferably an optical microscope camera. Figure 4 As shown ( Figure 4 Only three measurement points are shown in the figure), the field of view formed by the optical microscope camera on the surface of the wafer 7 is a rectangular field of view (Vision), and the optical microscope camera and the ranging module 3 are calibrated through the visual standard sample 5 to obtain the relative position relationship between the field of view center O1 of the rectangular field of view and the center point O2 of the polygon.

[0053] Specifically, during the process of scanning the surface of the wafer 7 by the optical microscope camera, when the optical microscope camera identifies a point to be measured (such as Figure 4 After finding the Mark point in the image, control the first motion platform 1 to move so that the point to be measured coincides with the center O1 of the rectangular field of view, and then drive the first motion platform 1 to move again according to the relative position relationship between the center O1 of the field of view and the center point O2 of the polygon, so that the point to be measured coincides with the center point O2 of the polygon, thereby completing the positioning of the point to be measured.

[0054] In this embodiment, the field of view center O1 of the image acquisition device 2 and the center point O2 of the ranging module 3 are pre-calibrated through the visual standard sample 5. After the coordinate information of the point to be measured is obtained, the field of view center O1 of the image acquisition device 2 is used as a jump to achieve rapid coincidence of the point to be measured and the center point O2 of the ranging module 3. It is no longer necessary to construct a coordinate system with the point to be measured and the center point O2 of the ranging module 3, and then achieve coincidence of the point to be measured and the center point O2 after performing coordinate transformation operations, thereby reducing the amount of calculation and improving the measurement speed of the entire measurement process of the two-dimensional warping degree of the wafer 7.

[0055] Further, for the convenience of calculation, in some embodiments, the distance measuring module 3 includes three distance measuring devices, and the three distance measuring points formed by the three distance measuring devices on the surface of the wafer 7 form an equilateral triangle (such as Figure 4 shown).

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

[0057] It should be understood that, in some embodiments, the triangle formed by the three rangefinders on the surface of the wafer 7 may also be a non-equilateral triangle, and other triangles may also be used to measure the warpage degree of the point to be measured.

[0058] Furthermore, in this embodiment, the calculation of the two-dimensional inclination angle of the measured point is explained by taking three three-dimensional coordinate points obtained by three rangefinders as an example. Figure 5 and Figure 6 As shown in the figure, Zs1, Zs2, and Zs3 represent the height values ​​measured by three rangefinders, and P1, P2, and P3 represent the three-dimensional coordinate data of three measuring points. The normal vectors of the planes where the three measuring points are located, and the three-dimensional coordinate data obtained by the three rangefinders are expressed as P1 (x1, y1, z1), P2 (x2, y2, z2), and P3 (x3, y3, z3), where 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 angle is expressed as:

[0060]

[0061] in, represents the plane normal vector, They are the vector representations of the three-dimensional coordinate data P1(x1,y1,z1), P2(x2,y2,z2), and P3(x3,y3,z3). represents the normal vector norm, θ x Indicates the inclination angle of the measuring point along the X-axis, θ yIndicates the inclination of the measuring point along the Y axis. represents the X-axis direction vector, Represents the Y-axis direction vector.

[0062] In addition, when the number of rangefinders used is greater than 3, assuming that the number of rangefinders used is L, the three-dimensional coordinate data of L measurement points obtained for one motion acquisition is expressed as P k (x k ,y k ,z k ), where k = 1, 2, ..., L. Each measurement point P k (x k ,y k ) The relative position is pre-calibrated by the visual standard sample 5 and is a known parameter;

[0063] Fit the plane equation z using the least squares method:

[0064] z=Ax+By+C;

[0065] Where (A, B) is the fitting L data points P k The plane equation coefficient, C = -1;

[0066] For more than 3 rangefinders, the method for calculating the [X, Y] direction inclination angle of the plane where the measured point is located relative to the wafer reference plane is as follows:

[0067]

[0068] in, To obtain the normal vector of the plane through multi-point fitting, θ x Indicates the inclination angle of the measuring point along the X-axis, θ y represents the inclination angle of the measuring point along the Y-axis direction. Further, based on the above embodiment, in other embodiments, Figure 2 and Figure 7 As shown, the wafer two-dimensional warpage degree measuring device also includes a second motion platform 6 electrically connected to the controller 4, and the image acquisition device 2 and the ranging 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 ranging module 3 to move between a preset standby position and a 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 measurement module 3 may pass through the optical path of the X-rays when performing the two-dimensional inclination measurement of the point to be measured, thereby blocking the X-rays. Therefore, in order to avoid interference between the image acquisition device 2 and the distance measurement module 3 and the X-ray optical path, in this embodiment, the image acquisition device 2 and the distance measurement module 3 are arranged on the second motion platform 6, and the image acquisition device 2 and the distance measurement module 3 are moved by the second motion platform 6. When the two-dimensional inclination 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 measurement module 3 move from the preset standby position to the preset measurement position, and then the image acquisition device 2 and the distance measurement module 3 start to work, and measure the two-dimensional inclination of the point to be measured. After the measurement is completed, the controller 4 controls the second motion platform 6 to move, so that the image acquisition device 2 and the distance measurement module 3 move from the preset measurement position to the preset standby position to avoid blocking the X-rays.

[0070] Furthermore, after moving the image acquisition device 2 and the ranging module 3 to the preset working position, the second motion platform 6 is also used to adjust the distance between the image acquisition device 2 and the ranging module 3 and the wafer 7, so that the image acquisition device 2 and the ranging module 3 can locate and measure the distance of the point to be measured at the same working distance.

[0071] Figure 8 1 is a flow chart of a method for measuring the two-dimensional warpage of a wafer according to an embodiment of the present invention. The method for measuring the two-dimensional warpage of a wafer is applied to a device for measuring the two-dimensional warpage of a wafer according to one of the above embodiments, and the device for measuring the two-dimensional warpage of a wafer comprises a first motion platform, an image acquisition device, a distance measurement module and a controller. Figure 8 As shown, the wafer two-dimensional warpage degree measurement method includes:

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

[0073] Specifically, the image acquisition device has a rectangular field of view of 1 to 10 mm according to different magnifications. When acquiring the surface image of the wafer, the second moving stage 6 is first moved to make the center of the microscope field of view coincide with the center of the wafer. According to the circular surface of a 12-inch wafer with a diameter of 300 mm, the rough distance between the point to be measured and the center of the wafer is taken as a rough range of 40×40 mm from the center position of the point to be measured, and the first moving stage is moved to scan until the point to be measured is scanned.

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

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

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

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

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

[0079] Specifically, the details of steps S1 to S5 of this embodiment may be found in the above-mentioned embodiment of the device for measuring the two-dimensional warpage of a wafer, and will not be repeated here.

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

[0081] The controller controls the second motion platform to move, so as to drive the image acquisition device and the distance measurement module to move from a preset standby position to a preset measurement position.

[0082] After step S5, the method further includes:

[0083] The controller controls the second motion platform to move, so as to drive the image acquisition device and the distance measurement module to move from a preset measurement position to a preset standby position.

[0084] Specifically, in order to prevent the image acquisition device and the ranging module from blocking the optical path of X-rays when the two-dimensional wafer warpage measurement device is applied to the CD-SAXS measurement technology, this embodiment arranges the image acquisition device and the ranging module on the second moving platform, and before performing the CD-SAXS measurement, moves the image acquisition device and the ranging module to a preset measurement position to realize the two-dimensional inclination measurement of the point to be measured; after the two-dimensional inclination measurement is completed, moves the image acquisition device and the ranging module to a preset standby position to avoid blocking the optical path of X-rays during the CD-SAXS measurement process.

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

[0086] The two-dimensional warpage degree measurement method of the wafer in the present embodiment locates the point to be measured on the wafer by an image acquisition device, and then moves the wafer by moving the first motion platform so that the point to be measured on the wafer coincides with the center point of the polygon formed by at least three measuring points on the wafer surface by the ranging module, and then the ranging module is used to measure the distance to obtain the three-dimensional coordinate data of at least three measuring points, and the two-dimensional warpage degree of the point to be measured is calculated using the three-dimensional coordinate data of at least three measuring points, which realizes the precise positioning of the point to be measured and the precise measurement of the two-dimensional warpage degree of the point to be measured, and provides a guarantee for the precise measurement of wafers in the CD-SAXS measurement technology.

[0087] Furthermore, in some embodiments, after step S5, the following steps are further included:

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

[0089] Specifically, in order to achieve grid-based point-by-point scanning measurement of the X-axis direction and the Y-axis direction of the wafer surface, thereby constructing a two-dimensional tilt angle measurement result of a warped and bent wafer, in this embodiment, Fig. 9 As shown in FIG. 1 , a two-dimensional coordinate system is constructed with the vertical plane as the wafer reference plane. After the two-dimensional inclination angle measurement of the test point is completed, the controller controls the first motion platform to move a preset step length along the X-axis direction or the Y-axis direction, so that the center point of the polygon moves to a new test point, and then the two-dimensional inclination angle of the new test point is calculated to obtain the two-dimensional inclination angle of the new test point, and so on, thereby obtaining a coordinate system as shown in FIG. Fig.10 The measurement results are shown.

[0090] Fig.11 Schematic diagram of the structure of the wafer measurement system according to an embodiment of the present invention. Fig.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 degree measurement device 400 as described in one of the above embodiments.

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

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

[0093] The controller is used to calculate the two-dimensional inclination of the point to be measured according to the three-dimensional coordinate data uploaded by the distance measurement module 3, and then control the rotation of the first motion platform 1 according to the two-dimensional inclination to perform surface inclination compensation.

[0094] The detection module 300 is used to collect the scattered image formed by X-rays irradiating the wafer test point after tilt compensation.

[0095] It should be noted that the wafer measurement system is implemented based on CD-SAXS measurement technology, which relies on model iterative fitting and solving of scattered signals at different incident angles of the wafer. In order to ensure accurate measurement results, CD-SAXS measurement technology has strict requirements on the incident angle of the X-ray irradiated to the point to be measured on the wafer. Therefore, in this embodiment, it is necessary to accurately measure the inclination angle caused by the wafer warping, and then perform inclination compensation correction during the CD-SAXS measurement process, so that the incident angle of the X-ray irradiated to the warped part of the wafer meets the requirements.

[0096] Specifically, the first motion platform 1 is a six-degree-of-freedom motion platform, including three translation axes and three rotational degrees of freedom. In this embodiment, after the two-dimensional inclination angle of the point to be measured is measured by the wafer two-dimensional warpage degree measuring device 400, the first motion platform 1 is controlled to rotate according to the two-dimensional inclination angle, so that the X-ray irradiated to the point to be measured after rotation meets the incident angle requirement. Among them, the two-dimensional inclination angle includes the inclination angle along the X-axis direction and the inclination angle along the Y-axis direction. When performing inclination compensation, the first motion platform 1 can be first controlled to rotate with the Y-axis as the rotation axis to overcome the inclination angle along the X-axis direction, and then the first motion platform 1 can be controlled to rotate with the X-axis as the rotation axis to overcome the inclination angle along the Y-axis direction. After compensating for the two-dimensional inclination angle, the light source module 100 is controlled to emit X-rays to irradiate the point to be measured on the wafer, and the detection module 300 is controlled to collect the scattered image formed by the X-ray irradiation of the wafer point to be measured after the inclination compensation.

[0097] The wafer measurement system of the present embodiment uses the wafer two-dimensional warpage measurement device 400 to perform two-dimensional inclination measurement on the test point on the wafer, and then compensates the two-dimensional inclination of the test point according to the measurement result, and then performs CD-SAXS measurement on the compensated test point, which ensures that the incident angle of the X-ray irradiated to the test point meets the requirement, avoids inaccurate CD-SAXS measurement results due to wafer surface warpage, and greatly improves the accuracy of CD-SAXS measurement.

[0098] Further, based on the above embodiments, in other embodiments, such as Fig.11 and Fig.12As shown, the wafer two-dimensional warpage degree measuring device 400 further includes 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 also used 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 inclination angle of the point to be measured and compensate for the inclination angle before measuring the wafer, 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 this 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 inclination measurement is required, 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 inclination of the point to be measured. After the measurement is completed, 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 measurement position to the preset standby position to avoid blocking X-rays.

[0100] In this 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 measurement module 3 to move from a preset standby position to a preset measurement position.

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

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

[0104] 4. The controller drives the first motion platform 1 until the point to be measured coincides with the center point of the polygon formed by at least three measurement points of the distance measuring module 3 on the wafer surface.

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

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

[0107] 7. The controller controls the first motion platform 1 to rotate according to the two-dimensional inclination angle to compensate for the two-dimensional inclination angle, and at the same time controls the second motion platform 6 to drive the image acquisition device 2 and the distance measurement 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 the test point on the wafer.

[0109] 9. The detection module 300 collects the scattered image formed by X-rays irradiating the wafer test point after tilt compensation.

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

[0111] It should be noted that the distance measuring module 3 needs to form at least three measuring points, so it has at least three distance measuring instruments. When measuring multiple points to be measured, multiple distance measuring instruments need to be moved repeatedly between the standby position and the measuring position, and displacement errors will be generated during the repeated movement. Specifically, this embodiment takes three distance measuring instruments as an example for explanation. During the CD-SAXS measurement process, due to the uncertainty of the displacement distance of the motion platform, that is, when the motion platform moves from one position to, it cannot ensure that the position of each movement is completely coincident, and there is a certain displacement error [ΔX, ΔY] in the X-axis and Y-axis directions. At the same time, due to the spontaneous jitter effect of the motion platform, a height measurement error ΔZ in the Z direction is caused, that is, for a point to be measured on the wafer plane, when the three measuring instruments are not fixed together, each measuring instrument moves separately, and there will be an error during the movement, thereby generating measurement errors [ΔX, ΔY, ΔZ] on the three axes. 1,2,3 . When there are N points to be measured, 3N measurements are required, and there will be 9N measurement errors. If the three measuring instruments are moved in a parallel fixed manner, the relative positions between the three measuring instruments are fixed and will not change. Therefore, each measurement only produces one movement, and only one set of errors [ΔX, ΔY, ΔZ] will be generated. For the measurement of multiple points to be measured, the accumulated error amount is less. Therefore, in this embodiment, at least three rangefinders of the ranging module 3 are fixedly set on the second motion platform 6, and the second motion platform 6 is used to drive at least three rangefinders to move synchronously, thereby greatly reducing the accumulation of errors and improving the overall measurement accuracy.

[0112] The above are only implementation methods of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are 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: A first motion platform, wherein the first motion platform is used to carry a wafer to be tested; An image acquisition device, used to capture an image of the wafer surface and locate a point to be measured on the wafer according to the image; A distance measuring module, wherein the distance measuring module forms at least three measuring points on the surface of the wafer, wherein the at least three measuring points form a polygon, and the distance measuring module is used to obtain 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, and is used to control the movement of the first motion platform according to the point to be measured located by the image acquisition device, so that the point to be measured coincides with the center point of the polygon, and then reads the three-dimensional coordinate data of the at least three measuring points uploaded by the ranging module, and calculates the two-dimensional inclination angle of the point to be measured according to the three-dimensional coordinate data.

2. The wafer two-dimensional warpage measurement device according to claim 1, characterized in that: The distance measuring module includes at least three spectral confocal distance measuring devices or at least three laser interferometer distance measuring devices.

3. The wafer two-dimensional warpage measurement device according to claim 1, characterized in that: The first motion platform is also provided with a visual standard sample for calibrating the relative spatial position of the image acquisition device and the distance measurement module, so as to determine the relative position relationship between the center of the field of view of the image acquisition device and the center point of the polygon; The controller is further used to control the movement of the first motion platform 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 position relationship so that the point to be measured coincides with the center point of the polygon.

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

5. The wafer two-dimensional warpage measurement device according to claim 1, characterized in that: The distance measuring module includes three distance measuring instruments, and three distance measuring points formed by the three distance measuring instruments on the surface of the wafer form an equilateral triangle.

6. The device for measuring the two-dimensional warpage of a wafer according to claim 5, characterized in that: The three-dimensional coordinate data obtained by the three rangefinders are expressed 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; The calculation process of the two-dimensional inclination angle is expressed as: in, represents the plane normal vector, They are the vector representations of the three-dimensional coordinate data P1(x1,y1,z1), P2(x2,y2,z2), and P3(x3,y3,z3). represents the normal vector norm, θ x represents the inclination angle of the measuring point along the X-axis direction, θ y represents the inclination angle of the measuring point along the Y axis, represents the X-axis direction vector, 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, the image acquisition device and the distance measurement module are arranged on the second motion platform, and the second motion platform is used to drive the image acquisition device and the distance measurement module to move between a preset standby position and a preset measurement position.

8. A method for measuring the 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 to 7, wherein the wafer two-dimensional warpage measurement device comprises a first motion platform, an image acquisition device, a distance measurement module and a controller; the method comprises: The image acquisition device captures the 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 a center point of a polygon formed by at least three measurement points of the ranging module on the surface of the wafer; The distance measurement 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 inclination angle of the point to be measured based on the three-dimensional coordinate data.

9. The method for measuring the two-dimensional warpage of a wafer according to claim 8, characterized in that: After the controller calculates the two-dimensional warping degree of the point to be measured based on the three-dimensional coordinate data, the controller further 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 point to be measured, and each time it moves to the new point to be measured, obtains the three-dimensional coordinate data of the new point to be measured collected by the ranging module, and calculates the two-dimensional inclination angle of the new point to be measured based on the three-dimensional coordinate data of the new point to be measured.

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 one of claims 1 to 7, wherein the wafer two-dimensional warpage measurement device includes a first motion platform, an image acquisition device, a ranging module and a controller, the X-rays emitted by the light source module pass through the vacuum scattering tube and irradiate the wafer to be measured on the first motion platform, the controller calculates the two-dimensional inclination angle of the wafer to be measured according to the three-dimensional coordinate data uploaded by the ranging module, the controller controls the first motion platform to rotate according to the two-dimensional inclination angle to perform surface inclination compensation, and the detection module is used to collect the scattered image formed by the X-ray irradiation of the wafer to be measured after the inclination compensation.

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

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