Surface topography data correction method and device and thickness measurement method

Abstract

The invention discloses a surface topography data correction method and device and a thickness measurement method.The surface topography data correction method comprises the following steps that a measuring probe is used for collecting the relative height of the upper surface of a measured object placed on a carrying disc, and three-dimensional topography data of the upper surface of the measured object during measurement are obtained; after the relative height of the upper surface of the measured object is measured, the measuring probe is moved to the edge of the carrying disc outside the edge of the measured object, and the relative height of at least one circle of the upper surface of the carrying disc is collected to obtain first data; calculating a plane deviation value d by using the first data and second data at the same measurement radius of the upper surface of the loading disc during calibration; and correcting the three-dimensional shape data of the upper surface of the measured object by using the plane deviation value d to obtain the corrected three-dimensional shape data of the measured object. According to the surface topography data correction method, the plane deviation of the loading disc caused by temperature drift and a vacuum suction state in thickness measurement can be compensated, and the measurement precision and the reliability of process control can be ensured.

Description

Technical Field

[0001] The present invention relates to the field of measurement technology, and in particular to a surface topography data correction method, device and thickness measurement method. Background Art

[0002] During wafer processing, measuring wafer thickness is one of the key process control steps. Existing thickness measurement methods usually rely on measuring the relative height of the wafer surface and comparing it with the height of the carrier surface during carrier calibration to obtain the wafer thickness. However, the relative height values ​​of the wafer and carrier surfaces cannot be measured at the same time, and the physical condition changes between measuring the wafer and measuring the carrier will cause measurement deviations. The main influencing factors include:

[0003] 1. Temperature drift effect: Temperature changes will cause overall changes in the measurement components, including changes in the height of the measurement probe, changes in the height of the carrier surface, and tilt, etc. Therefore, when the time interval between measuring the wafer and the carrier is long, the deviation caused by temperature drift will significantly affect the measurement accuracy.

[0004] 2. Influence of vacuum state: When measuring the wafer, the wafer is fixed on the carrier by vacuum suction. The change of atmospheric pressure will cause the supporting structure of the carrier to deform, resulting in the sinking of the carrier plane, thereby changing the relative height of the upper surface of the wafer and affecting the measurement accuracy.

[0005] The existing technology lacks an effective method to compensate in real time for the temperature drift effect and the change in the carrier plane caused by the vacuum state, which leads to deviations in the thickness measurement results. Summary of the invention

[0006] The technical problem of the present invention is to provide a surface morphology data correction method, device and thickness measurement method, which can correct the carrier plane deviation caused by temperature drift and vacuum state in thickness measurement and improve measurement accuracy.

[0007] A surface topography data correction method comprises the following steps:

[0008] S11: Use the measuring probe to collect the relative height of the upper surface of the object to be measured placed on the carrier plate, and obtain the three-dimensional shape data (X w ,Y w ,Z w );

[0009] S12: After measuring the relative height of the upper surface of the measured object, move the measuring probe to the edge of the carrier plate outside the edge of the measured object, collect the relative height of at least one circle of the upper surface of the carrier plate, and obtain the first data (X t ,Y t ,Z t );

[0010] S13: Using the first data (X t ,Y t ,Z t ) and the second data (X) at the same measurement radius as the first data on the upper surface of the carrier during calibration c1 ,Y c1 ,Z c1 ), calculate the plane deviation value d;

[0011] S14: Using the plane deviation value d, the three-dimensional topography data (X w ,Y w ,Z w ) to obtain the corrected three-dimensional shape data of the object being measured (X w ,Y w ,Z r ).

[0012] In one embodiment, in step S13, the first data (X t ,Y t ,Z t ) and the second data during calibration (X c1 ,Y c1 ,Z c1 ) is used to fit and calculate the plane deviation value d.

[0013] In one embodiment, the calculating of the plane deviation value d comprises the following steps:

[0014] For the first data (X t ,Y t ,Z t ) is fitted by the least square method to obtain the carrier plane P during measurement. t The plane equation coefficient A t ,B t ,C t ,D t ;

[0015] For the second data (X c1 ,Y c1 ,Z c1 ) is fitted by the least square method to obtain the calibration plate plane P c The plane equation coefficient A c ,B c ,C c ,D c ;

[0016] The carrier plane P during measurement is calculated by the following formula t Each measuring point (X w ,Y w) corresponds to the height value Z t :

[0017]

[0018] The calibration plate plane P is calculated by the following formula c Each measuring point (X w ,Y w ) corresponds to the height value Z c :

[0019]

[0020] The plane P is calculated by the following formula c With plane P t At each measuring point (X w ,Y w ) corresponds to the plane deviation value d:

[0021] d=Z t -Z c .

[0022] In one embodiment, in step S14, the plane deviation value d is used to calculate the three-dimensional topographic data (X w ,Y w ,Z w ) to obtain the corrected three-dimensional shape data of the object being measured (X w ,Y w ,Z r ), including: using the initial relative height value Z of each measuring point of the measured object w Subtract the corresponding plane deviation value d to obtain the corrected relative height value Z r .

[0023] A thickness measurement method comprises the following steps:

[0024] S21: Use the measuring probe to collect the relative height of the upper surface of the carrier plate to obtain the three-dimensional topographic data (X c ,Y c ,Z c );

[0025] S22: Using the surface topography data correction method to obtain the corrected three-dimensional topography data (X w ,Y w ,Z r );

[0026] S23: For each measuring point, calculate the relative height value Z of the measured object after correction under the same X, Y coordinates rThe difference Z between the relative height value of the upper surface of the carrier plate during calibration △r , get the thickness data of the object being measured (X w ,Y w ,Z △r ).

[0027] In one embodiment, the relative height of the upper surface of the carrier plate is collected by using the measuring probe to obtain the three-dimensional topographic data (X) of the upper surface of the carrier plate during calibration. c ,Y c ,Z c ), including the following steps:

[0028] The carrier is driven to rotate at a constant speed around the θ axis, and the measuring probe is driven to move from the center to the edge of the carrier along the Y axis to form a concentric circle scanning path;

[0029] The relative height value of the surface of the object to be measured is collected by the measuring probe to obtain the cylindrical coordinate system data set (r, θ, z) of the upper surface of the carrier;

[0030] The cylindrical coordinate system data set (r, θ, z) is converted into a spatial rectangular coordinate system data set (x, y, z) to obtain the topographic data of the upper surface of the carrier in three-dimensional space (X c ,Y c ,Z c ).

[0031] In one embodiment, the relative height of the upper surface of the carrier plate is collected by using the measuring probe to obtain the three-dimensional topographic data (X) of the upper surface of the carrier plate during calibration. c ,Y c ,Z c ), further comprising the following steps:

[0032] The three-dimensional topographic data (X c ,Y c ,Z c ) performs region segmentation to obtain the segmented grid data Data_grid (X_grid, Y_grid) with equal spacing in the same direction;

[0033] Based on the original sampled relative height value Z of the sampling points around each grid point c [pi] and its contribution weight Wpi to the grid point, and the relative height value Zgrid[P] of each grid point is obtained through weighted calculation;

[0034] Use the measurement point (X w ,Y w ) as the resampling point set Data_rs(X w ,Y w );

[0035] Based on each resampling point in the resampling point set, the relative height values ​​Z of the four grid points around it are used P1 ,Z P2 ,Z P3 ,Z P4 and its corresponding contribution weight W q , calculate the relative height value Z_q of each resampled point, and thus generate the three-dimensional topographic data Data_rs (X w ,Y w , Z_q).

[0036] In one embodiment, the contribution weight W of the sampling point to the grid point is pi The calculation includes:

[0037] According to the distance between the sampling point and the grid point, use any method of bilinear interpolation, Gaussian function or Sigmoid function to calculate the contribution weight W of the sampling point to the grid point. pi .

[0038] In one embodiment, obtaining the relative height value Zgrid[P] of each grid point by weighted calculation includes:

[0039] The relative height values ​​Z of the sampling points around the grid point are calculated by weighted averaging. c [pi] and its contribution weight W pi Combined, the final relative height value Z of each grid point is calculated grid [P].

[0040] A surface topography data correction device, comprising:

[0041] A rotation drive assembly, used to drive the object to be measured to rotate at a constant speed around the θ axis;

[0042] A Y-axis driving component, used for driving the measuring probe to move continuously along the Y-axis direction;

[0043] The measuring probe is used to collect the relative height value of the surface of the measured object along the Y-axis direction while the measured object rotates around the θ-axis to obtain the three-dimensional shape data (X w ,Y w ,Z w ), and after measuring the relative height of the upper surface of the measured object, the measuring probe is moved to the edge of the carrier plate outside the edge of the measured object, and the relative height of at least one circle of the upper surface of the carrier plate is collected to obtain the first data (X t ,Y t ,Z t );

[0044] The moving module is used to move the measuring probe to the edge of the carrier plate outside the edge of the measured object after measuring the relative height of the upper surface of the measured object, collect the relative height of at least one circle of the upper surface of the carrier plate, and obtain the first data (X t ,Y t ,Z t );

[0045] A calculation module, used for converting the first data (X t ,Y t ,Z t ) and the second data (X) at the same measurement radius as the first data on the upper surface of the carrier during calibration c1 ,Y c1 ,Z c1 ), calculate the plane deviation value d;

[0046] A correction module is used to correct the three-dimensional shape data (X) of the upper surface of the measured object based on the plane deviation value d. w ,Y w ,Z w ) to obtain the corrected three-dimensional shape data of the object being measured (X w ,Y w ,Z r ).

[0047] The surface topography data correction method, device and thickness measurement method described above can compensate for the disc plane deviation caused by temperature drift and vacuum state during thickness measurement, and help ensure measurement accuracy and reliability of process control. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a schematic diagram of the structure of a measuring device in one embodiment of the present invention;

[0049] Figure 2 is a flow chart of a surface topography data correction method in one embodiment of the present invention;

[0050] Figure 3 It is a schematic diagram when measuring the object to be measured;

[0051] Figure 4 This is a schematic diagram of measuring the edge of the carrier plate;

[0052] Figure 5 is a flow chart of the thickness measurement method;

[0053] Figure 6 A flow chart for obtaining three-dimensional topographic data of the upper surface of the carrier during calibration;

[0054] Figure 7 It is a schematic diagram of the original carrier plate morphology data;

[0055] Figure 8 This is a schematic diagram after the grid points are divided;

[0056] Fig. 9 Schematic diagram of grid point weight calculation;

[0057] Fig.10 A schematic diagram for calculating the relative height value of the resampling point;

[0058] Fig.11 A schematic diagram of the resampled data.

[0059] Explanation of the reference numerals: 1. platform; 2. rotating table; 3. carrier plate; 4. Y-axis drive assembly; 5. bracket assembly; 6. measuring probe; 7. object to be measured. DETAILED DESCRIPTION

[0060] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, the specific implementation methods of the present invention are described clearly and completely below in conjunction with the accompanying drawings. Obviously, the specific details described below are only part of the embodiments of the present invention, and the present invention can also be implemented in many other embodiments different from those described herein. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0061] In this document, when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time. The directional words such as front, back, top, and bottom involved are defined by the positions of the parts in the drawings and the positions of the parts relative to each other, just for the clarity and convenience of expressing the technical solution. It should be understood that the use of the directional words should not limit the scope of protection claimed in the present invention.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0063] The high-precision thickness measurement method and device of the present application are used to measure the three-dimensional surface morphology of the measured object. The measured object refers to the object that needs to be measured, such as wafers, silicon wafers used in the photovoltaic industry, and other parts with flat surfaces.

[0064] like Figure 1As shown, a measuring device provided by the present application includes a rotation drive assembly, a Y-axis drive assembly 4, a measuring probe 6 and a control system, wherein the rotation drive assembly is used to drive the measured object to rotate at a constant speed around the θ axis. In this embodiment, the rotation drive assembly includes a rotating table 2 and a carrier plate 3, wherein the rotating table 2 is arranged on a platform 1, and the carrier plate 3 is placed on the rotating table 2, and the measured object is placed on the carrier plate 3 during measurement. The Y-axis drive assembly 4 is used to drive the measuring probe 6 to move along the Y-axis direction.

[0065] See also Figure 2 In one embodiment of the present invention, the surface topography data correction method comprises the following steps:

[0066] Step S11: Use the measuring probe to collect the relative height of the upper surface of the object to be measured placed on the carrier plate, and obtain the three-dimensional shape data (X w ,Y w ,Z w ),See Figure 3 .

[0067] Step S12: After measuring the relative height of the upper surface of the measured object, move the measuring probe to the edge of the carrier plate outside the edge of the measured object, collect the relative height of at least one circle of the upper surface of the carrier plate, and obtain the first data (X t ,Y t ,Z t ),See Figure 4 ;

[0068] Step S13: Using the first data (X t ,Y t ,Z t ) and the second data (X) at the same measurement radius as the first data on the upper surface of the carrier during calibration c1 ,Y c1 ,Z c1 ), calculate the plane deviation value d;

[0069] Step S14: Using the plane deviation value d, the three-dimensional shape data (X w ,Y w ,Z w ) to obtain the corrected three-dimensional shape data of the object being measured (X w ,Y w ,Z r ).

[0070] The surface topography data correction method described above can compensate for the disc plane deviation caused by temperature drift and vacuum state during thickness measurement, which helps to ensure measurement accuracy and reliability of process control.

[0071] In one embodiment, in step S13, the first data (X t ,Y t ,Z t ) and the second data during calibration (X c1 ,Y c1 ,Z c1 ) to fit and calculate the plane deviation value d. The specific calculation method is as follows:

[0072] S13-1: For the first data (X t ,Y t ,Z t ) is fitted by the least square method to obtain the carrier plane P during measurement. t The plane equation can be expressed as:

[0073] A t X+B t Y+C t Z+D t =0

[0074] Among them, A t , B t , C t , D t are the plane coefficients obtained by fitting. These coefficients are obtained by minimizing each sampling point (X t ,Y t ,Z t ) to the fitting plane, thereby ensuring the accuracy of the fitting plane.

[0075] S13-2: For the second data (X c1 ,Y c1 ,Z c1 ) is fitted by the least square method to obtain the calibration plate plane P c The plane equation can be expressed as:

[0076] A c X+B c Y+C c Z+D c =0

[0077] Among them, A c , B c , C c , D c is the plane coefficient obtained by fitting.

[0078] S13-3: Calculate the carrier plane P during measurement using the following formula t Each measuring point (X w ,Y w) corresponds to the height value Z t :

[0079]

[0080] This formula is based on the standard form of the plane equation and calculates the measurement point on the carrier plane P. t The height above indicates the theoretical height of the point under the current measurement status.

[0081] S13-4: Calculate the calibration plate plane P using the following formula c Each measuring point (X w ,Y w ) corresponds to the height value Z c :

[0082]

[0083] This height value represents the theoretical height of the point during calibration and is used as a reference.

[0084] S13-5: Calculate plane P by the following formula c With plane P t At each measuring point (X w ,Y w ) corresponds to the plane deviation value d:

[0085] d=Z t -Z c .

[0086] The deviation value d represents the change in height of the carrier plate caused by the tilt or sinking of the carrier plate plane in different states.

[0087] In one embodiment, in step S14, the three-dimensional shape data (X w ,Y w ,Z w ) is corrected. Specifically, the height value Z of each measuring point is w Subtract the corresponding plane deviation value d to get the corrected height value Z r :

[0088] Z r =Z w -d

[0089] Corrected 3D shape data (X w ,Y w ,Z r ) is the surface height data of the object being measured after plane deviation correction, eliminating the influence of the tilt or deformation of the carrier plane, thereby improving the measurement accuracy.

[0090] like Figure 5 As shown, in another embodiment of the present application, a thickness measurement method is provided, comprising the following steps:

[0091] S21: Using a measuring probe to collect the relative height of the upper surface of the carrier plate, and obtaining the three-dimensional topographic data of the upper surface of the carrier plate during calibration. Specifically, the following steps are included:

[0092] S21-1: driving the carrier to rotate at a constant speed around the θ axis, and driving the measuring probe to move from the center to the edge of the carrier along the Y axis to form a concentric circle scanning path;

[0093] S21-2: collecting the relative height value of the surface of the object to be measured (in this embodiment, the object to be measured is a wafer) through the measuring probe to obtain a cylindrical coordinate system data set (r, θ, z) of the upper surface of the carrier;

[0094] S21-3: Convert the obtained cylindrical coordinate system data set (r, θ, z) into a spatial rectangular coordinate system data set to obtain the topographic data (X c ,Y c ,Z c ).

[0095] In one embodiment, for a carrier having a plurality of grooves of different radii on the surface, the topographic data of the carrier surface cannot be obtained at the groove positions. To solve this problem, this embodiment provides a topographic data resampling method, which resamples the topographic data of the carrier surface, including the following steps:

[0096] Step S21-4: Sample data (X c ,Y c ,Z c ) to perform region segmentation and obtain the segmented grid data Data_grid (X_grid, Y_grid) with equal spacing in the same direction.

[0097] The purpose of grid point division is to transform the sampling data (X c ,Y c ,Z c ) is evenly divided into multiple regular grid areas to provide anchor points for subsequent data resampling. This division process is performed on the XY plane. By setting an appropriate step size, the entire sampling area is divided into equally spaced grids and the height values ​​of the grid points are initialized. The specific implementation method is as follows:

[0098] 1. Determine the scope of sampling data

[0099] First, calculate the sampling data (X c ,Y c ,Z c)’s X-coordinate range and Y-coordinate range are:

[0100] X min =min(X c ),X max =max(X c )

[0101] Y min =min(Y c ),Y max =max(Y c )

[0102] These values ​​represent the minimum and maximum coordinates of the sampled data on the X-axis and Y-axis, respectively.

[0103] 2. Determine the step size of the grid

[0104] According to application requirements, set the step size in the X direction and Y direction, denoted as X step and Y step The step size defines the spacing between grid points. The step size directly affects the density of the grid. The smaller the step size, the denser the grid. The choice of step size can be adjusted according to the distribution of sampling points and the measurement accuracy requirements.

[0105] 3. Generate grid point coordinates

[0106] Centered at (0,0), based on X step and Y step Generate an equally spaced grid in the X and Y directions. The range of the grid should be able to completely cover the minimum range of all sampling points, that is:

[0107] X grid ={X min ,X min +X step ,…,X max}

[0108] Y grid = {Y min ,Y min +Y step ,…,Y max}

[0109] The coordinates of the grid points are marked (X grid ,Y grid ), which form a regular grid structure in the XY plane.

[0110] 4. Initialize the height value of the grid point

[0111] For each generated grid point, initialize its height value Z gridThe purpose of initialization is to provide a data anchor point for subsequent resampling. The height value Z of the grid point grid It will be updated in subsequent recalculation steps to ensure that the heights of the grid points reflect the actual measured topography information.

[0112] 5. Output grid data

[0113] After the grid division is completed, the output grid data set Data_grid contains the X coordinates, Y coordinates and initial height value Z of all grid points:

[0114] Data_grid={(X_grid,Y_grid,Z_grid)}

[0115] Where X_grid and Y_grid are the X-axis and Y-axis coordinates of the equally spaced grid points, and Z_grid is the corresponding initial height value.

[0116] like Figure 8 As shown in the figure, the grid point division effect shows uniformly distributed grid points, covering the entire range of the sampling area. By mapping the sampling points to these regular grids, the impact of uneven distribution of sampling points on subsequent topography measurements can be eliminated. Ultimately, grid point division provides a basis for resampling relative height information and data homogenization.

[0117] Step S21-5: Based on the original sampled relative height values ​​Z of the sampling points around each grid point c [pi] and its contribution weight W to the grid point pi , the relative height value Zgrid[P] of each grid point is obtained through weighted calculation.

[0118] The grid point weight calculation aims to accurately estimate the relative height value Z of each grid point by using the information of the surrounding sampling points. grid [P] to ensure that the morphological information of the mesh vertices can accurately reflect the actual morphology of the semiconductor wafer. This process uses a weight-based interpolation method, and the weights can be calculated by various methods such as bilinear interpolation, Gaussian function or Sigmoid function. The specific implementation is as follows:

[0119] 1. Collection of sampling points

[0120] First, the sample data (X c ,Y c ,Z c ) are divided into corresponding grid areas according to their coordinates. For each grid point P(x, y), collect the sampling points pi that fall around the grid (usually the four nearest sampling points in the grid). The relative height value Z of the sampling point c [pi] will be used to calculate the final relative height value Z of the grid pointgrid [P].

[0121] 2. Calculate the distance and weight of the sampling points

[0122] For each grid point P(x,y), according to the X and Y distances D of the surrounding sampling points pi(X_i,Y_i) x and D y , calculate the contribution weight W of each sampling point to the grid point pi .

[0123] (1) Calculate distance

[0124] See Fig. 9 , for the distance between each sampling point pi and the grid point P:

[0125] D x =|x-X_i|,D y =|y-Y_i|

[0126] Among them, x and y are the coordinates of the grid point P, and X_i and Y_i are the coordinates of the sampling point pi.

[0127] (2) Calculate weight

[0128] When calculating weights, different methods can be used to evaluate the contribution of each sampling point to the grid point P. The following are three common weight calculation methods:

[0129] a. Bilinear interpolation weight calculation

[0130] Bilinear interpolation is based on the distance between the sampling point and the grid point in the X and Y directions, with weight W pi The calculation formula is:

[0131]

[0132] Among them, X step and Y step is the mesh step size.

[0133] b. Gaussian function weight calculation

[0134] The Gaussian function uses the square of the distance as input and the weight W pi The calculation formula is:

[0135]

[0136] Here, δ is the standard deviation parameter of the Gaussian distribution, which can be set according to specific needs, for example, δ=0.6 or δ=0.3.

[0137] c. Sigmoid function weight calculation

[0138] The Sigmoid function combines the Euclidean distance between the sampling point and the grid point, and the weight W pi The calculation formula is:

[0139]

[0140] This formula smoothes the distance through the nonlinear mapping of the Sigmoid function.

[0141] Note: The weight calculation method is not limited to the above three methods, and other interpolation or weighting functions can be used according to specific application requirements.

[0142] 3. Calculate the relative height value of the grid point

[0143] After calculating the weight W of each sampling point to the grid point P pi After that, the final relative height value Z of the grid point P can be calculated by weighted average. grid [P]. The formula is as follows:

[0144]

[0145] in:

[0146] Z c [pi] is the original sampling relative height value of sampling point pi;

[0147] W pi is the contribution weight of sampling point pi to grid point P;

[0148] N is the number of sampling points around the grid point.

[0149] Through the above calculation, the relative height value Z of the grid point grid [P] can reflect the morphological characteristics within the sampling area, and because of the use of weight calculation, it can fully consider the spatial relationship between the sampling points and the grid points, making the estimated morphological data more accurate.

[0150] 4. Complete the calculation of all grid points

[0151] The above calculation method is applied to each grid point until the relative height value Z of all grid points is grid All calculations are completed. The resulting grid data set Data_grid contains the coordinates of each grid point (X grid ,Y grid ) and the corresponding relative height value Z grid , these data will be used to reconstruct the carrier morphology.

[0152] Step S21-6: Use the measurement point (X w ,Yw ) as the resampling point set Data_rs(X w ,Y w ).

[0153] Step S21-7: Based on the resampling point set Data_rs(X w ,Y w ) is used to calculate the relative height values ​​Z of the four surrounding grid points. P1 ,Z P2 ,Z P3 ,Z P4 and its corresponding contribution weight W q , calculate the relative height value Z_q of each resampling point, thereby generating the resampled data Data_rs (X_q, Y_q, Z_q).

[0154] Similarly, according to the distance between the sampling point and the grid point, any method of bilinear interpolation, Gaussian function or Sigmoid function is used to calculate the contribution weight W of the four grid points around the resampling point to the resampling point q The following is an explanation using the bilinear interpolation method as an example.

[0155] Resampling calculates the relative height value of each resampling point through a bilinear interpolation algorithm, and finally obtains accurate resampling data Data_rs. This process will use the grid data of the sampling point to interpolate the topography data of each resampling point to ensure that the relative height value of each point accurately reflects the topography information of the wafer.

[0156] 1. Determine the grid where the resampling points are located

[0157] For each resampled point q(X_q,Y_q), we first need to determine the grid it is in. The grid consists of four vertices P1(x P1 ,y P1 ),P2(x P2 ,y P2 ),P3(x P3 ,y P3 ),P4(x P4 ,y P4 ) is surrounded by. Fig.10 The resampled points q are shown to lie within a quadrilateral grid.

[0158] The vertex coordinates of the mesh are determined by the following conditions:

[0159] X_q-x P1 >0 and X_q-x P2 ≤0 (the resampling point is between P1 and P2)

[0160] Y_q-y P1>0 and Y_q-y P3 ≤0 (the resampling point is between P1 and P3)

[0161] After determining the grid to which the resampled point q belongs, the relative height values ​​Z of the four vertices of the grid P1 ,Z P2 ,Z P3 ,Z P4 Will be used for interpolation calculations.

[0162] 2. Calculate the relative distance between the resampling point and the mesh vertex

[0163] For a given grid, calculate the relative distances d_x and d_y of the resampled point q relative to the vertex P1 in the X and Y directions:

[0164] d_x=X_q-xP1,d_y=Y_q-yP1

[0165] Where: d_x is the distance of point q relative to P1 in the X direction, and d_y is the distance of point q relative to P1 in the Y direction.

[0166] 3. Bilinear interpolation calculation

[0167] Use the relative height values ​​Z of the four mesh vertices P1 ,Z P2 ,Z P3 ,Z P4 As well as the relative distances d_x and d_y of the resampling points, the relative height value Z_q of the resampling point q is calculated by bilinear interpolation. The calculation formula is as follows:

[0168] Z_q=[Z P1 *(X step -dx)*(Y step -dy)+Z P2 *dx*(Y step -dy)+Z P3 *dx*dy+Z P4 *(X step -dx)*dy] / (X step *Y step )

[0169] in:

[0170] X step and Y step are the step sizes of the grid in the X and Y directions respectively.

[0171] Z P1 ,Z P2 ,Z P3 ,Z P4 The relative height values ​​of the four vertices of the mesh.

[0172] 4. Complete the calculation of all resampling points

[0173] According to the above steps, bilinear interpolation is performed on each resampling point to obtain the relative height values ​​Data_rs of all resampling points. This data set contains the coordinates (X_q, Y_q) of all resampling points and the corresponding relative height values ​​Z_q. The resampled data is as follows Fig.11 .

[0174] The resampling algorithm of the present application is applied to obtain the resampled data of the upper surface of the carrier plate.

[0175] S22: Using the surface topography data correction method in the above embodiment to obtain the corrected three-dimensional topography data (X w , Y w , Z r ).

[0176] S23: For each measuring point, calculate the relative height value Z of the measured object after correction under the same X, Y coordinates r The difference Z between the relative height value of the upper surface of the carrier plate during calibration Δr , get the thickness data of the object being measured (X w , Y w , Z Δr ). Specifically, the corrected relative height value Z of each measuring point is r Subtract the relative height value Z of the corresponding measuring point on the upper surface of the carrier during calibration c Or Z_q, get the thickness value of the object being measured.

[0177] In another embodiment of the present invention, there is provided a surface topography data correction device, comprising:

[0178] A rotation drive assembly, used to drive the object to be measured to rotate at a constant speed around the θ axis;

[0179] A Y-axis driving component, used for driving the measuring probe to move continuously along the Y-axis direction;

[0180] The measuring probe is used to collect the relative height value of the surface of the measured object along the Y-axis direction while the measured object rotates around the θ-axis to obtain the three-dimensional shape data (X w ,Y w ,Z w ), and after measuring the relative height of the upper surface of the measured object, the measuring probe is moved to the edge of the carrier plate outside the edge of the measured object, and the relative height of at least one circle of the upper surface of the carrier plate is collected to obtain the first data (X t ,Y t ,Z t );

[0181] The moving module is used to move the measuring probe to the edge of the carrier plate outside the edge of the measured object after measuring the relative height of the upper surface of the measured object, collect the relative height of at least one circle of the upper surface of the carrier plate, and obtain the first data (X t ,Y t ,Z t );

[0182] A calculation module, used for converting the first data (X t ,Y t ,Z t ) and the second data (X) at the same measurement radius as the first data on the upper surface of the carrier during calibration c1 ,Y c1 ,Z c1 ), calculate the plane deviation value d;

[0183] A correction module is used to correct the three-dimensional shape data (X) of the upper surface of the measured object based on the plane deviation value d. w ,Y w ,Z w ) to obtain the corrected three-dimensional shape data of the object being measured (X w ,Y w ,Z r ).

[0184] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A surface topography data correction method, characterized in that: The following steps are involved: S11: Use the measuring probe to collect the relative height of the upper surface of the object to be measured placed on the carrier plate, and obtain the three-dimensional shape data (X w ,Y w ,Z w ); S12: After measuring the relative height of the upper surface of the measured object, move the measuring probe to the edge of the carrier plate outside the edge of the measured object, collect the relative height of at least one circle of the upper surface of the carrier plate, and obtain the first data (X t ,Y t ,Z t ); S13: Using the first data (X t ,Y t ,Z t ) and the second data (X) at the same measurement radius as the first data on the upper surface of the carrier during calibration c1 ,Y c1 ,Z c1 ), calculate the plane deviation value d; S14: Using the plane deviation value d, the three-dimensional topography data (X w ,Y w ,Z w ) to obtain the corrected three-dimensional shape data of the object being measured (X w ,Y w ,Z r ).

2. The surface topography data correction method according to claim 1, characterized in that: In step S13, the first data (X t ,Y t ,Z t ) and the second data during calibration (X c1 ,Y c1 ,Z c1 ) is used to fit and calculate the plane deviation value d.

3. The surface topography data correction method according to claim 2, characterized in that: The calculation of the plane deviation value d comprises the following steps: For the first data (X t ,Y t ,Z t ) is fitted by the least square method to obtain the carrier plane P during measurement. t The plane equation coefficient A t ,B t ,C t ,D t ; For the second data (X c1 ,Y c1 ,Z c1 ) is fitted by the least square method to obtain the calibration plate plane P c The plane equation coefficient A c ,B c ,C c ,D c ; The carrier plane P during measurement is calculated by the following formula t Each measuring point (X w ,Y w ) corresponds to the height value Z t : The calibration plate plane P is calculated by the following formula c Each measuring point (X w ,Y w ) corresponds to the height value Z c : The plane P is calculated by the following formula c With plane P t At each measuring point (X w ,Y w ) corresponds to the plane deviation value d: d=Z t -Z c 。 4. The surface topography data correction method according to claim 1, characterized in that: In step S14, the plane deviation value d is used to calculate the three-dimensional topographic data (X w ,Y w ,Z w ) to obtain the corrected three-dimensional shape data of the object being measured (X w ,Y w ,Z r ), including: using the initial relative height value Z of each measuring point of the measured object w Subtract the corresponding plane deviation value d to obtain the corrected relative height value Z r .

5. A thickness measurement method, characterized in that: The following steps are involved: S21: using a measuring probe to collect the relative height of the upper surface of the carrier plate, and obtaining three-dimensional topographic data of the upper surface of the carrier plate during calibration; S22: Obtain corrected three-dimensional shape data (X) of the object to be measured by using the surface shape data correction method according to any one of claims 1 to 4. w ,Y w ,Z r ); S23: For each measuring point, calculate the relative height value Z of the object being measured after correction under the same X, Y coordinates r The difference Z between the relative height value of the upper surface of the carrier plate during calibration △r , get the thickness data of the object being measured (X w ,Y w ,Z △r ).

6. The thickness measurement method according to claim 5, characterized in that: The method of collecting the relative height of the upper surface of the carrier plate by using the measuring probe to obtain the three-dimensional topographic data of the upper surface of the carrier plate during calibration includes the following steps: The carrier is driven to rotate at a constant speed around the θ axis, and the measuring probe is driven to move from the center to the edge of the carrier along the Y axis to form a concentric circle scanning path; The relative height value of the surface of the object to be measured is collected by the measuring probe to obtain the cylindrical coordinate system data set (r, θ, z) of the upper surface of the carrier; The cylindrical coordinate system data set (r, θ, z) is converted into a spatial rectangular coordinate system data set (x, y, z) to obtain the topographic data of the upper surface of the carrier in three-dimensional space (X c ,Y c ,Z c ).

7. The thickness measurement method according to claim 6, characterized in that: The method of collecting the relative height of the upper surface of the carrier plate by using the measuring probe to obtain the three-dimensional topographic data of the upper surface of the carrier plate during calibration also includes the following steps: The three-dimensional topographic data (X c ,Y c ,Z c ) performs region segmentation to obtain the segmented grid data Data_grid (X_grid, Y_grid) with equal spacing in the same direction; Based on the original sampled relative height value Z of the sampling points around each grid point c [pi] and its contribution weight Wpi to the grid point, and the relative height value Zgrid[P] of each grid point is obtained through weighted calculation; Use the measurement point (X w ,Y w ) as the resampling point set Data_rs(X w ,Y w ); Based on each resampling point in the resampling point set, the relative height values ​​Z of the four grid points around it are used P1 ,Z P2 ,Z P3 ,Z P4 and its corresponding contribution weight W q , calculate the relative height value Z_q of each resampled point, and thus generate the three-dimensional topographic data Data_rs (X w ,Y w , Z_q).

8. The thickness measurement method according to claim 7, characterized in that: The contribution weight W of the sampling point to the grid point pi The calculation includes: According to the distance between the sampling point and the grid point, the contribution weight W of the sampling point to the grid point is calculated by using any method of bilinear interpolation, Gaussian function or Sigmoid function. pi .

9. The thickness measurement method according to claim 7, characterized in that: The relative height value Zgrid[P] of each grid point obtained by weighted calculation includes: The relative height values ​​Z of the sampling points around the grid point are calculated by weighted averaging. c [pi] and its contribution weight W pi Combined, the final relative height value Z of each grid point is calculated grid [P].

10. A surface topography data correction device, characterized in that: include: A rotation drive assembly, used to drive the object to be measured to rotate at a constant speed around the θ axis; A Y-axis driving component, used for driving the measuring probe to move continuously along the Y-axis direction; The measuring probe is used to collect the relative height value of the surface of the measured object along the Y-axis direction while the measured object rotates around the θ-axis to obtain the three-dimensional shape data (X w ,Y w ,Z w ), and after measuring the relative height of the upper surface of the measured object, the measuring probe is moved to the edge of the carrier plate outside the edge of the measured object, and the relative height of at least one circle of the upper surface of the carrier plate is collected to obtain the first data (X t ,Y t ,Z t ); The moving module is used to move the measuring probe to the edge of the carrier plate outside the edge of the measured object after measuring the relative height of the upper surface of the measured object, collect the relative height of at least one circle of the upper surface of the carrier plate, and obtain the first data (X t ,Y t ,Z t ); A calculation module, used for converting the first data (X t ,Y t ,Z t ) and the second data (X) at the same measurement radius as the first data on the upper surface of the carrier during calibration c1 ,Y c1 ,Z c1 ), calculate the plane deviation value d; A correction module is used to correct the three-dimensional shape data (X) of the upper surface of the measured object based on the plane deviation value d. w ,Y w ,Z w ) to obtain the corrected three-dimensional shape data of the object being measured (X w ,Y w ,Z r ).

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