Spectral confocal measurement equipment and method for geometrical characteristics of wafer

Abstract

The invention relates to spectral confocal measurement equipment and method for geometrical characteristics of a wafer, the equipment comprises a base, a workbench, a horizontal movement mechanism, a mounting rack, a vertical movement mechanism and a spectral confocal sensor, a linear motor is used for driving, an air floating guide rail is used for orientation, and the spectral confocal sensor is used for detection, so that high-efficiency, high-precision and low-cost nondestructive detection of the wafer is realized; the problems that in the prior art, when geometrical characteristics of a wafer are measured, repeated measurement precision is low, measurement efficiency is low, measurement cost is high, and surface nondestructive measurement cannot be achieved while precision is guaranteed are solved.

Description

Technical Field

[0001] The present invention relates to the field of wafer detection, and in particular to a spectral confocal measurement device and method for wafer geometric characteristics. Background Art

[0002] Among numerous industries, the semiconductor and photovoltaic industries have long been recognized as key drivers of global technological growth. Furthermore, wafers are core components of key devices such as integrated circuits, semiconductor chips, and solar cells. Therefore, wafers are considered the backbone of these industries, playing an irreplaceable role in these fields. Furthermore, the quality of wafer geometry directly determines the performance and reliability of these devices. Accurate and reliable wafer geometry characterization is a prerequisite for wafer geometry quality control, helping to improve device consistency and quality stability.

[0003] Important characteristic parameters used to characterize wafer geometric quality include thickness, total thickness variation (TTV), bow, and warp. The definitions of these geometric quality parameters are detailed in the latest version of the International Semiconductor Technology Roadmap and Semiconductor Equipment and Materials International (SEMI) standards.

[0004] Currently, there are two mainstream measurement methods: contact and non-contact. Contact instruments, such as micrometers, profilometers, and contact probes, are relatively simple and intuitive, with low uncertainty. However, these methods suffer from low measurement accuracy and can contaminate or even damage the wafer, necessitating wafer scrapping after measurement, adding unnecessary costs. To achieve high-precision measurement of wafer geometric parameters while preventing sample damage, non-contact methods and equipment more suitable for wafer measurement are needed. Currently, inductive sensors are known for their low power consumption, high sensitivity, and low cost, but their resolution is only 6.5μm, making them unsuitable for high-precision measurements. Optical interferometry is widely used for high-precision geometric thickness measurement, but measurement accuracy needs to be improved. Furthermore, systematic errors caused by coupling errors inherent in interferometry are difficult to avoid. Ultrasonic and X-ray techniques have also been used in such applications, but the harsh operating conditions required present many practical difficulties.

[0005] In summary, wafer geometric characteristics include thickness, TTV, bow, and warpage. These geometric quality characteristics significantly impact device consistency and reliability, necessitating reliable measurement methods to characterize these characteristics during the manufacturing process. In the measurement field, accuracy, efficiency, and cost are three key, mutually constrained factors. While intuitively, a balance of all three is optimal, achieving a balance is often the key. Wafer geometric feature measurement currently faces challenges such as low repeatability, low measurement efficiency, high measurement costs, and the inability to achieve non-destructive surface measurement while maintaining accuracy. Summary of the Invention

[0006] Based on this, the present invention provides a spectral confocal measurement device and method for wafer geometric characteristics to solve the technical problems faced by the existing technology in measuring the geometric characteristics of wafers, such as low repeated measurement accuracy, low measurement efficiency, high measurement cost, and the inability to achieve surface non-destructive measurement while ensuring accuracy.

[0007] In a first aspect, the present invention comprises a base 1, a workbench 2, a horizontal motion mechanism 3, a mounting frame 4, a vertical motion mechanism 5 and a spectral confocal sensor 6, wherein:

[0008] The horizontal motion mechanism 3 includes a first displacement mechanism 31 for movement in the X direction and a second displacement mechanism 32 for movement in the Y direction, which are fixedly mounted on the horizontal workbench 21;

[0009] The mounting frame 4 is provided with a mounting surface 41 for placing the wafer 8, and is fixedly connected to the horizontal motion mechanism 3, and is driven by the horizontal motion mechanism 3 to achieve horizontal movement;

[0010] The center of the mounting surface 41 is provided with a circular through hole 411 and one or more recessed platforms 412 for mounting standard gauge blocks;

[0011] The upper crossbeam 221 of the gantry workbench 22 is used to install the vertical motion mechanism 5, and the lower crossbeam 222 is used to install the six-degree-of-freedom micro-motion device 7;

[0012] The first displacement mechanism 31 is driven by one or more first power devices 311 and its movement direction is constrained by one or more first guide rails 312; the second displacement mechanism 32 is driven by one or more second power devices 321 and its movement direction is constrained by one or more second guide rails 322.

[0013] The spectral confocal sensor 6 includes an upper spectral confocal sensor 61 for measuring the upper surface of the wafer 8 and a lower spectral confocal sensor 62 for measuring the lower surface of the wafer 8. The upper spectral confocal sensor 61 is fixedly connected to the vertical motion mechanism 5, and the lower spectral confocal sensor 62 is fixedly connected to the six-degree-of-freedom micro-motion device 7, and the measurement axes of the upper spectral confocal sensor 61 and the lower spectral confocal sensor 62 coincide.

[0014] Furthermore, the base 1 is provided with two or more pairs of shock absorbing mechanisms 10 , and each shock absorbing mechanism 10 is provided with a support leg 11 for adjusting the tilt direction of the workbench under it. The support leg 11 is connected to the shock absorbing mechanism 10 through a threaded connection and is provided with a locking nut 12 .

[0015] Furthermore, the number of the recessed platforms 412 is 8, which are used to place standard gauge blocks 9 of different specifications.

[0016] Furthermore, the mounting surface 41 is arranged between the upper beam 221 and the lower beam 222, and the mounting surface 41 is provided with three silicon ball mounting holes 413 for supporting wafers. The center diameter of the silicon ball mounting hole 413 is slightly larger than the circumference of the circular through hole 411, and the adjacent angle is 120°. The diameter of the silicon ball is 1 mm, and the diameter of the circular through hole 411 is 300 mm.

[0017] Furthermore, the workbench 2 includes a horizontal workbench 21 and a gantry workbench 22 vertically fixed on the horizontal workbench 21 , and is installed on the ground through the base 1 .

[0018] Furthermore, the vertical motion mechanism 5 is driven by one or more power devices 501 and the motion direction is constrained by one or more cylinders 502 .

[0019] Furthermore, the first power device 311 , the second power device 321 and the power device 501 are linear motors, and the first guide rail 312 and the second guide rail 322 are air-floating guide rails.

[0020] Furthermore, the mounting surface 41 is provided with a fixing block 414 for fixing the wafer 8 , and the contact point between the fixing block 414 and the wafer 8 coincides with the wafer outline.

[0021] According to another aspect of the present invention, the present invention further provides a measurement method of a spectral confocal measurement device based on any one of the wafer geometric characteristics described above, comprising the following steps:

[0022] S1) Place a standard gauge block 9 of thickness S on the concave platform 412 and press it with a fixing block 414. Then place the wafer 8 on the mounting surface 41, support it with three silicon balls mounted in the silicon ball mounting holes 413, and fix the wafer with a fixing block 414.

[0023] S2) adjusting the horizontal motion mechanism 3, the first displacement mechanism 31 in the X direction and the second displacement mechanism 32 in the Y direction to their stroke centers;

[0024] S3) Adjust the vertical motion mechanism 5 to adjust the upper spectral confocal sensor 61 to a suitable position, then adjust the six-degree-of-freedom micro-motion device 7 to adjust the lower spectral confocal sensor 62 to a suitable position, and ensure that the measurement axes of the two spectral confocal sensors coincide, and at this time, the measurement axes of the two sensors pass through the center of the wafer 8;

[0025] S4) controlling the horizontal motion mechanism 3 to move the standard gauge block 9 between the upper spectral confocal sensor 61 and the lower spectral confocal sensor 62, calibrating the upper spectral confocal sensor 61 and the lower spectral confocal sensor 62 and recording the upper sensor indication and the lower sensor indication;

[0026] S5) Control the horizontal motion mechanism 3 to move, drive the mounting frame 4 to scan along the set path, and record the indication S of the horizontal motion mechanism 3 xi 、S yi And the indication value X of the upper and lower sensors 1i 、X 2i , where i=1…n is the number of points;

[0027] S6) After the scanning is completed, the upper sensor value and the lower sensor value are corrected for deviation, and the wafer geometric characteristics are calculated:

[0028] a) Calculate the center thickness T c and the thickness T at each point on the wafer i :

[0029] T i =(X 1i -X b1 )+(X 2i -X b2 )+S

[0030] T c =(X 1c -X b1 )+(X 2c -X b2 )+S

[0031] The value of the sensor at point i is X 1i , the value of the lower sensor at point i is X 2i , the sensor value at the center of the circle is X1c , the value of the sensor at the center of the circle is X 2c , the sensor reading on the standard gauge block is X b1 , the lower sensor shows the value of X b2 , the change in the value of the upper sensor measuring point is (X 1i -X b1 ), the change in the value of the lower sensor measurement point is (X 2i -X b2 ), the thickness of the standard gauge block is S;

[0032] b) Assume that the thickness of each point on the wafer takes the maximum value T at the coordinates of the maximum thickness point tmax and the minimum thickness point tmin respectively. max and the minimum value T min , the total thickness change is expressed as:

[0033] TVV=T max -T min

[0034] =(X 1,tmax -X b1 )+(X 2,tmax -X b2 )+S-(X 1,tmin -X b1 )-(X 2,tmin -X b2 )-S

[0035] =(X 1,tmax +X 2,tmax )-(X 1,tmin +X 2,tmin )

[0036] The total thickness change is TVV, and the value of the upper sensor at tmax is X 1tmax , the upper sensor reading at tmin is X 1,tmax , the value of the lower sensor at tmax is X 2tmax , the value of the lower sensor at tmin is X 2,tmax ;

[0037] c) Calculate the middle plane based on the indications of the two sensors, expressed as:

[0038]

[0039] The middle plane of point i is C i ;

[0040] The least squares plane is obtained by fitting the middle plane using the least squares method. The expression is:

[0041] LS Reference plane(Li )=Least-squares methodfit((C i ))

[0042] The Z-axis coordinate of the least squares plane at point i is L i , the least squares method is Least-squaresmethodfit(·), and the least squares reference plane is LS Reference plane(·);

[0043] Calculate bending:

[0044]

[0045] The bend is Bow, the z-axis coordinate of the mid-plane at the center of the circle is Cc, and the z-axis coordinate of the least squares plane at the center of the circle is Lc;

[0046] d) Obtain the coordinates dmax of the point where the difference is maximum and dmin of the point where the difference is minimum, and calculate the warpage:

[0047] Warp=D max -D min =(L max -C max )-(L min -C min )

[0048] The maximum difference between the middle plane and the least squares plane is D at dmax. max The minimum difference between the middle plane and the least squares plane at dmin is D min , the z-axis coordinate of the least squares plane at dmax is L dmax , the z-axis coordinate of the least squares plane at dmin is L dmin , the z-axis coordinate of the middle plane at dmax is C dmax , the z-axis coordinate of the middle plane at dmin is C dmin , warping is Warp;

[0049] S7) Repeat steps S4-S6 three or more times, and take the average of the three calculation results as the measurement result value.

[0050] Furthermore, the method for correcting the deviation of the upper sensor indication value and the lower sensor indication value includes:

[0051] In the temperature-controlled box, the standard displacement block data of the spectral confocal sensor at different temperatures, the original output values and true values of the upper and lower sensors are collected. The random sampling consensus algorithm is used to eliminate abnormal temperature-sensitive points, and a second-order polynomial compensation model is established. The expression is:

[0052]

[0053] The output value after temperature compensation is The output value is W, the real-time temperature is T, and the reference temperature is T ref , the correction coefficients are μ1 and μ2 respectively;

[0054] Obtain relevant data from the spectral confocal sensor, including environmental parameters, equipment status parameters, and process characteristic parameters. Input the relevant data into the neural network deviation correction model and give the loss function, which is expressed as:

[0055]

[0056] The total number of samples is N, and the ath true value is U a , the corrected a-th original output value is The regularization coefficient is β, the Euclidean norm is ||·||, and the output value is The gradient of

[0057] Monte Carlo simulation was used to add a temperature perturbation of ±0.5 degrees. When the temperature sensitivity was nonlinear, the model was segmented into three stages: low temperature, normal temperature, and high temperature.

[0058] The segmented temperature data is input into the dynamic temperature compensation model, and the temperature deviation is obtained through dynamic re-integration. The expression is:

[0059]

[0060] The temperature deviation is ΔD T , the dynamic weight of the zth segment is λ z , the order is M, the jth power of the real-time temperature is (T) j , the coefficient of the j-term polynomial of the z-th segment is θ z,j ;

[0061] The upper spectral confocal sensor and the lower spectral confocal sensor are compensated by temperature deviation to obtain corrected upper sensor indications and lower sensor indications.

[0062] The spectral confocal measurement device for wafer geometric characteristics and the polishing method thereof of the present invention can achieve the following beneficial effects by adopting the above technical solution:

[0063] 1) The spectral confocal measurement device for wafer geometric features of the present invention solves the problems faced by existing technologies in measuring wafer geometric features, such as low repeated measurement accuracy, low measurement efficiency, high measurement cost, and the inability to achieve non-destructive surface measurement while ensuring accuracy. By using linear motor drive, air-floating guide rail orientation, and spectral confocal sensor detection, it achieves efficient, high-precision, and low-cost non-destructive testing of wafers, thereby solving the problems existing in wafer geometric feature detection.

[0064] 2) By providing two or more pairs of shock-absorbing mechanisms on the base, and threaded support legs beneath each shock-absorbing mechanism, the present invention allows for adjustable tilt of the workbench, adapting to various installation environments. Furthermore, to enhance stability, locking nuts are provided to prevent tilting caused by loosening of the support legs after installation.

[0065] 3) The present invention is provided with 8 concave platforms for placing standard gauge blocks of different specifications. Standard gauge blocks of different specifications are installed at each concave platform position, which solves the problem of limited measurement range of the spectral confocal displacement sensor.

[0066] 4) The three silicon balls are arranged on a circle with a diameter slightly larger than the circular through hole, and the adjacent angle is 120°, which avoids the problem that the support method has a significant impact on the measurement accuracy.

[0067] 5) The driving mechanism adopts a combination of linear motor and air-floating guide rail, which has higher positioning accuracy and better stability;

[0068] 6) The mounting surface is provided with a fixing block for fixing the wafer. The contact point between the fixing block and the wafer coincides with the wafer outline, avoiding the problem of wafer deviation due to inertia during measurement.

[0069] 7) The spectral confocal measurement method for wafer geometric characteristics proposed in this paper takes into account the characteristics of wafer properties and dual-spectral confocal sensor measurement, avoids the problem of deviation from the true physical meaning, and the data is more real and valid. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0071] Figure 1 Schematic diagram of the structure of the spectral confocal measurement equipment for wafer geometric characteristics;

[0072] Figure 2 A local enlarged view of area A;

[0073] Figure 3 A local enlarged view of area B;

[0074] Figure 4 This is a schematic diagram of the installation of standard gauge blocks;

[0075] Figure 5 This is a schematic diagram of the structure of the mounting frame before placing the wafer in Example 1;

[0076] Figure 6 This is a schematic diagram of the structure of the mounting frame after the wafer is placed in Example 1;

[0077] Figure 7 Schematic diagram of the scanning results of the upper spectral confocal sensor;

[0078] Figure 8 This is a schematic diagram of the scanning results of the lower spectral confocal sensor;

[0079] Figure 9 Schematic diagram of the thickness change distribution.

[0080] Figure 10 This is a schematic diagram of the structure of the mounting frame before placing the wafer in Example 2;

[0081] Figure 11 This is a schematic diagram of the structure of the mounting frame after the wafer is placed in the second embodiment;

[0082] In the figure: 1. Base, 2. Workbench, 21. Horizontal workbench, 22. Gantry workbench, 221. Upper beam, 222. Lower beam, 3. Horizontal motion mechanism, 31. First displacement mechanism, 311. First power unit, 312. First guide rail, 32. Second displacement mechanism, 321. Second power unit, 322. Second guide rail, 4. Mounting frame, 41. Mounting surface, 411. Circular through hole, 412. Concave table, 4121. Mounting gasket, 413. Silicon ball mounting hole, 414. Fixed block, 415. 8-inch mounting plate, 5. Vertical motion mechanism, 501. Power unit, 502. Cylinder, 6. Spectral confocal sensor, 61. Upper spectral confocal sensor, 62. Lower spectral confocal sensor, 7. Six-degree-of-freedom micro-motion device, 8. Wafer, 9. Standard gauge block, 10. Shock absorption mechanism, 11. Support leg, 12. Locking nut. DETAILED DESCRIPTION

[0083] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. The terms such as "upper", "lower", "left", "right", "middle" and "one" cited in the embodiments are only for the convenience of description, and are not used to limit the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantial changes in the technical content. In order to better explain the present invention and facilitate understanding, the present invention will be described in detail below in conjunction with the accompanying drawings through specific embodiments. Among them, the directional nouns such as "upper", "lower", "front", "back", "left", and "right" mentioned herein are Figure 1 The orientation is referenced.

[0084] An embodiment of the present invention proposes a spectral confocal measurement device for wafer geometric characteristics, which includes a base, a workbench, a horizontal motion mechanism, a mounting frame, a vertical motion mechanism, and a spectral confocal sensor, wherein: the workbench includes a horizontal workbench and a gantry workbench vertically fixed to the horizontal workbench, and is installed on the ground through the base; the horizontal motion mechanism includes a first displacement mechanism for achieving X-direction movement and a second displacement mechanism for achieving Y-direction movement, and is fixedly installed on the horizontal workbench; the mounting frame is provided with a mounting surface for placing the wafer, is fixedly connected to the horizontal motion mechanism, and is driven by the horizontal motion mechanism to achieve horizontal movement; a circular The gantry worktable has a through hole and is provided with one or more recessed platforms for mounting standard gauge blocks. The upper crossbeam of the gantry worktable is used to mount the vertical motion mechanism, and the lower crossbeam is used to mount the six-degree-of-freedom micro-motion device. The mounting surface is arranged between the upper and lower crossbeams, and there is no motion interference between the mounting frame and the gantry worktable during measurement. The spectral confocal sensor includes an upper spectral confocal sensor for measuring the upper surface of the wafer and a lower spectral confocal sensor for measuring the lower surface of the wafer. The upper spectral confocal sensor is fixedly connected to the vertical motion mechanism, and the lower spectral confocal sensor is fixedly connected to the six-degree-of-freedom micro-motion device, and the measurement axes of the upper and lower spectral confocal sensors coincide. This solves the problems of poor repeatability, low detection efficiency, and high detection cost in the existing technology for detecting wafer geometric features.

[0085] Example 1:

[0086] Reference Figure 1 The embodiment of the present invention provides a spectral confocal measurement device for wafer geometric characteristics, which is referred to as "the device" for ease of description. The "device" includes a base 1, a workbench 2, a horizontal motion mechanism 3, a mounting frame 4, a vertical motion mechanism 5, and a spectral confocal sensor 6;

[0087] In this embodiment, the size of the “wafer 8” is 12 inches. For the sake of convenience, it is collectively referred to as “wafer 8” in this embodiment.

[0088] Specifically, refer to Figure 1 The workbench 2 is installed on the ground through the base 1. Two or more pairs of shock-absorbing mechanisms 10 are provided under the base 1. Each shock-absorbing mechanism 10 is provided with a support leg 11 for adjusting the tilt direction of the workbench. The support leg 11 is connected to the shock-absorbing mechanism 10 through a thread and is provided with a locking nut 12. The distance of the workbench 2 from the ground can be adjusted by rotating the support leg 11. After adjusting the position, tighten the locking nut 12 to lock it.

[0089] The workbench 2 includes a horizontal workbench 21 and a gantry workbench 22 vertically fixed to the horizontal workbench 21; wherein the horizontal motion mechanism 3 is fixedly mounted on the horizontal workbench 21; the gantry workbench 22 is further divided into an upper crossbeam 221 and a lower crossbeam 222, the vertical motion mechanism 5 is mounted on the upper crossbeam 221, and the six-degree-of-freedom micro-motion device 7 is mounted on the lower crossbeam 222;

[0090] The spectral confocal sensor 6 includes an upper spectral confocal sensor 61 for measuring the upper surface of the wafer 8 and a lower spectral confocal sensor 62 for measuring the lower surface of the wafer 8. The upper spectral confocal sensor 61 is fixedly connected to the vertical motion mechanism 5, and the lower spectral confocal sensor 62 is fixedly connected to the six-degree-of-freedom micro-motion device 7. The six-degree-of-freedom micro-motion device 7 is adjusted to ensure that the measurement axes of the upper spectral confocal sensor 61 and the lower spectral confocal sensor 62 coincide with each other.

[0091] The mounting frame 4 is fixedly connected to the horizontal motion mechanism 3 and is driven by the horizontal motion mechanism 3 to achieve horizontal movement. The horizontal motion mechanism 3 includes a first displacement mechanism 31 for achieving movement in the X direction and a second displacement mechanism 32 for achieving movement in the Y direction. The first displacement mechanism 31 is driven by two first power devices 311 and has its movement direction constrained by two first guide rails 312. The second displacement mechanism 32 is driven by a second power device 321 and has its movement direction constrained by a second guide rail 322. The vertical motion mechanism 5 is driven by a power device 501 and has its movement direction constrained by two cylinders 502.

[0092] Preferably, the first power device 311, the second power device 321 and the power device 501 are linear motors, and the first guide rail 312 and the second guide rail 322 are air-floating guide rails;

[0093] Reference Figure 2 As shown, the mounting frame 4 is a frame structure, provided with a mounting surface 41 for placing the wafer 8, a circular through hole 411 is provided in the center of the mounting surface 41, and one or more recessed platforms 412 for mounting the standard gauge block 9 are provided; the mounting surface 41 is arranged between the upper crossbeam 221 and the lower crossbeam 222, and there will be no motion interference between the mounting frame 4 and the gantry worktable 22 during the measurement process; in addition, the mounting surface 41 is also provided with three silicon ball mounting holes 413 for supporting the wafer, and the center diameter of the silicon ball mounting hole 413 is slightly larger than the circumference of the circular through hole 411, and the adjacent angles are 120°.

[0094] In this embodiment, the silicon ball is fixed inside the silicon ball mounting hole 413 by glue. Figure 3 As shown;

[0095] Preferably, the number of the concave platforms 412 is 8, which are used to place standard gauge blocks 9 of different specifications. In this embodiment, the standard gauge blocks 9 are installed in the concave platforms 412 through the installation gaskets 4121. Figure 4 As shown;

[0096] Preferably, the diameter of the silicon ball is 1 mm, and the diameter of the circular through hole 411 is 300 mm;

[0097] The mounting surface 41 is provided with a fixing block 414 for fixing the wafer 8 , and the contact point between the fixing block 414 and the wafer 8 coincides with the wafer outline.

[0098] An embodiment of the present invention provides a spectral confocal measurement method for wafer geometric characteristics, comprising the following steps:

[0099] S1) Place the standard gauge block 9 with a thickness of S on the concave platform 412 and press it with the fixing block 414. Figure 4 The silicon ball is fixed to the inside of the silicon ball mounting hole 413 by glue, and the mounting frame 4 is not placed when the wafer is referenced Figure 5 As shown;

[0100] Then, the wafer 8 is placed on the mounting surface 41, supported by three silicon balls mounted in the silicon ball mounting holes (413), and fixed with a fixing block (413), referring to Figure 6 As shown;

[0101] S2) adjusting the horizontal motion mechanism 3, the first displacement mechanism 31 in the X direction and the second displacement mechanism 32 in the Y direction to their stroke centers;

[0102] S3) Adjust the vertical motion mechanism 5 to adjust the upper spectral confocal sensor 61 to a suitable position, then adjust the six-degree-of-freedom micro-motion device 7 to adjust the lower spectral confocal sensor 62 to a suitable position, and ensure that the measurement axes of the two spectral confocal sensors coincide, and at this time, the measurement axes of the two sensors pass through the center of the wafer 8;

[0103] S4) By controlling the horizontal motion mechanism 3, the standard gauge block 9 is moved between the upper spectral confocal sensor 61 and the lower spectral confocal sensor 62, the upper spectral confocal sensor 61 and the lower spectral confocal sensor 62 are calibrated and the sensor readings X of the upper and lower sensors are recorded respectively. b1 and X b2 ;

[0104] S5) Control the horizontal motion mechanism 3 to move, drive the mounting frame 4 to scan along the set path, and record the indication S of the horizontal motion mechanism 3 xi 、S yi And the indication value X of the upper and lower sensors 1i 、X 2i, where i = 1…n is the number of points; the upper and lower sensor values recorded at different locations refer to Figure 7 and Figure 8 As shown;

[0105] S6) After the scanning is completed, the upper sensor value and the lower sensor value are corrected for deviation, and the wafer geometric characteristics are calculated:

[0106] a) Calculate the center thickness T c and the thickness T at each point on the wafer i :

[0107] T i =(X 1i -X b1 )+(X 2i -X b2 )+S

[0108] T c =(X 1c -X b1 )+(X 2c -X b2 )+S

[0109] The value of the sensor at point i is X 1i , the value of the lower sensor at point i is X 2i , the sensor value at the center of the circle is X 1c , the value of the sensor at the center of the circle is X 2c , the sensor reading on the standard gauge block is X b1 , the lower sensor shows the value of X b2 , the change in the value of the upper sensor measuring point is (X 1i -X b1 ), the change in the value of the lower sensor measurement point is (X 2i -X b2 ), the thickness of the standard gauge block is S;

[0110] b) Assume that the thickness of each point on the wafer takes the maximum value T at the coordinates of the maximum thickness point tmax and the minimum thickness point tmin respectively. max and the minimum value T min , the total thickness change is expressed as:

[0111] TVV=T max -T min

[0112] =(X 1,tmax -X b1 )+(X 2,tmax -X b2 )+S-(X 1,tmin -X b1 )-(X2,tmin -X b2 -S

[0113] =(X 1,tmax +X 2,tmax )-(X 1,tmin +X 2,tmin )

[0114] The total thickness change is TVV, and the value of the upper sensor at tmax is X 1tmax , the upper sensor reading at tmin is X 1,tmax , the value of the lower sensor at tmax is X 2tmax , the value of the lower sensor at tmin is X 2,tmax ;

[0115] c) Calculate the middle plane based on the indications of the two sensors, expressed as:

[0116]

[0117] The middle plane of point i is C i ;

[0118] The least squares plane is obtained by fitting the middle plane using the least squares method. The expression is:

[0119] LS Reference plane(L i )=Least-squares methodfit((C i ))

[0120] The Z-axis coordinate of the least squares plane at point i is L i , the least squares method is Least-squaresmethodfit(·), and the least squares reference plane is LS Reference plane(·);

[0121] Calculate bending:

[0122]

[0123] The bend is Bow, the z-axis coordinate of the midplane at the center of the circle is Cc, and the z-axis coordinate of the least squares plane at the center of the circle is Lc;

[0124] d) Obtain the coordinates dmax of the point where the difference is maximum and dmin of the point where the difference is minimum, and calculate the warpage:

[0125] Warp=D max -D min =(L max -C max )-(L min -Cmin )

[0126] The maximum difference between the middle plane and the least squares plane is D at dmax. max The minimum difference between the middle plane and the least squares plane at dmin is D min , the z-axis coordinate of the least squares plane at dmax is L dmax , the z-axis coordinate of the least squares plane at dmin is L dmin , the z-axis coordinate of the middle plane at dmax is C dmax , the z-axis coordinate of the middle plane at dmin is C dmin , warping is Warp;

[0127] S7) Repeat steps S4-S6 three or more times, and take the average of the three calculation results as the measurement result value, 9.920 μm, the calculation result of the bow is 10.098 μm, and the calculation result of the warp Crap is 20.901 μm.

[0128] In this embodiment, the method for correcting the deviation of the upper sensor value and the lower sensor value includes:

[0129] In the temperature-controlled box, the standard displacement block data of the spectral confocal sensor at different temperatures, the original output values and true values of the upper and lower sensors are collected. The random sampling consensus algorithm is used to eliminate abnormal temperature-sensitive points, and a second-order polynomial compensation model is established. The expression is:

[0130]

[0131] The output value after temperature compensation is The output value is W, the real-time temperature is T, and the reference temperature is T ref , the correction coefficients are μ1 and μ2 respectively;

[0132] Obtain relevant data from the spectral confocal sensor, including environmental parameters, equipment status parameters, and process characteristic parameters. Input the relevant data into the neural network deviation correction model and give the loss function, which is expressed as:

[0133]

[0134] The total number of samples is N, and the ath true value is U a , the corrected a-th original output value is The regularization coefficient is β, the Euclidean norm is ||·||, and the output value is The gradient of

[0135] Monte Carlo simulation was used to add a temperature perturbation of ±0.5 degrees. When the temperature sensitivity was nonlinear, the model was segmented into three stages: low temperature, normal temperature, and high temperature.

[0136] The segmented temperature data is input into the dynamic temperature compensation model, and the temperature deviation is obtained through dynamic re-integration. The expression is:

[0137]

[0138] The temperature deviation is ΔD T , the dynamic weight of the zth segment is λ z , the order is M, the jth power of the real-time temperature is (T) j , the coefficient of the j-term polynomial of the z-th segment is θ z,j ;

[0139] The upper spectral confocal sensor and the lower spectral confocal sensor are compensated by temperature deviation to obtain corrected upper sensor indications and lower sensor indications.

[0140] Example 2:

[0141] The difference from Example 1 is that in this embodiment, the size of the "wafer 8" is 8 inches. For the sake of convenience, it is also collectively referred to as "wafer 8" in this embodiment.

[0142] When the diameter of the circular through hole 411 of the mounting surface 41 is 300 mm, it is only used to measure the wafer material with a size of 12 inches. For the detection of small-sized wafers, only the mounting piece of the corresponding size is needed. As described in this embodiment, the detection of the 8-inch wafer 8 requires the installation of the 8-inch mounting piece 415. When the mounting frame 4 is not placed with the wafer 8, refer to Figure 10 Then, the wafer 8 is placed on the mounting surface 41, supported by three silicon balls mounted in the silicon ball mounting holes 413, and fixed with a fixing block 413, referring to Figure 11 shown.

[0143] The remaining steps are consistent with those in Example 1.

[0144] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A spectral confocal measurement device for wafer geometric characteristics, characterized in that: The invention comprises a base (1), a workbench (2), a horizontal motion mechanism (3), a mounting frame (4), a vertical motion mechanism (5) and a spectral confocal sensor (6), wherein the workbench (2) comprises a horizontal workbench (21) and a gantry workbench (22), wherein: The horizontal motion mechanism (3) includes a first displacement mechanism (31) for achieving movement in the X direction and a second displacement mechanism (32) for achieving movement in the Y direction, and is fixedly mounted on the horizontal workbench (21); The mounting frame (4) is provided with a mounting surface (41) for placing the wafer (8), is fixedly connected to the horizontal motion mechanism (3), and moves in the horizontal direction under the drive of the horizontal motion mechanism (3); The center of the mounting surface (41) is provided with a circular through hole (411), and one or more recessed platforms (412) for mounting standard gauge blocks are provided; The upper crossbeam (221) of the gantry workbench (22) is used to install the vertical motion mechanism (5), and the lower crossbeam (222) is used to install the six-degree-of-freedom micro-motion device (7); The first displacement mechanism (31) is driven by one or more first power devices (311), and its movement direction is constrained by one or more first guide rails (312); the second displacement mechanism (32) is driven by one or more second power devices (321), and its movement direction is constrained by one or more second guide rails (322); The spectral confocal sensor (6) comprises an upper spectral confocal sensor (61) for measuring the upper surface of the wafer (8) and a lower spectral confocal sensor (62) for measuring the lower surface of the wafer (8), the upper spectral confocal sensor (61) is fixedly connected to the vertical motion mechanism (5), the lower spectral confocal sensor (62) is fixedly connected to the six-degree-of-freedom micro-motion device (7), and the measurement axes of the upper spectral confocal sensor (61) and the lower spectral confocal sensor (62) coincide.

2. The spectral confocal measurement device for wafer geometric characteristics according to claim 1, characterized in that: The base (1) is provided with two or more pairs of shock absorbing mechanisms (10), and a support leg (11) for adjusting the tilt direction of the workbench is provided below each shock absorbing mechanism (10). The support leg (11) is connected to the shock absorbing mechanism (10) through a threaded connection and is provided with a locking nut (12).

3. The spectral confocal measurement device for wafer geometric characteristics according to claim 1, characterized in that: The number of the recessed platforms (412) is 8 and they are used to place standard gauge blocks (9) of different specifications.

4. The spectral confocal measurement device for wafer geometric characteristics according to claim 1, characterized in that: The mounting surface (41) is arranged between the upper crossbeam (221) and the lower crossbeam (222), and the mounting surface (41) is provided with three silicon ball mounting holes (413) for supporting wafers. The center diameter of the silicon ball mounting hole (413) is slightly larger than the circumference of the circular through hole (411), and the diameter of the silicon balls with adjacent angles of 120° is (1) mm, and the diameter of the circular through hole (411) is 300 mm.

5. The spectral confocal measurement device for wafer geometric characteristics according to claim 1, characterized in that: The workbench (2) comprises a horizontal workbench (21) and a gantry workbench (22) vertically fixed on the horizontal workbench (21), and is installed on the ground through the base (1).

6. The spectral confocal measurement device for wafer geometric characteristics according to claim 1, characterized in that: The vertical motion mechanism (5) is driven by one or more power devices (501), and the motion direction is constrained by one or more cylinders (502).

7. The spectral confocal measurement device for wafer geometric characteristics according to claim 1, characterized in that: The first power device (311), the second power device (321) and the power device (501) are linear motors, and the first guide rail (312) and the second guide rail (322) are air-floating guide rails.

8. The spectral confocal measurement device for wafer geometric characteristics according to claim 1, characterized in that: The mounting surface (41) is provided with a fixing block (414) for fixing the wafer (8), and the contact point between the fixing block (414) and the wafer (8) coincides with the wafer outline.

9. A measurement method of a spectral confocal measurement device based on wafer geometric characteristics according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1) placing a standard gauge block (9) with a thickness of S on a concave platform (412) and pressing it with a gasket (414), then placing a wafer (8) on a mounting surface (41), supporting it with three silicon balls mounted in silicon ball mounting holes (413), and fixing the wafer with a fixing block (414); S2) adjusting the horizontal motion mechanism (3), the first displacement mechanism (31) in the X direction and the second displacement mechanism (32) in the Y direction to their stroke centers respectively; S3) adjusting the vertical motion mechanism (5) to adjust the upper spectral confocal sensor (61) to a suitable position, then adjusting the six-degree-of-freedom micro-motion device (7) to adjust the lower spectral confocal sensor (62) to a suitable position, and ensuring that the measurement axes of the two spectral confocal sensors coincide, at which point the measurement axes of the two sensors pass through the center of the wafer (8); S4) controlling the horizontal motion mechanism (3) to move the standard gauge block (9) between the upper spectral confocal sensor (61) and the lower spectral confocal sensor (62), calibrating the upper spectral confocal sensor (61) and the lower spectral confocal sensor (62), and recording the upper sensor indication value and the lower sensor indication value; S5) Control the horizontal motion mechanism (3) to move, drive the mounting frame (4) to scan along the set path, and record the indication S of the horizontal motion mechanism (3) xi 、S yi And the indication value X of the upper and lower sensors 1i 、X 2i , where i=1…n is the number of points; S6) After the scanning is completed, the upper sensor value and the lower sensor value are corrected for deviation, and the wafer geometric characteristics are calculated: a) Calculate the center thickness T c and the thickness T at each point on the wafer i : T i =(X 1i -X b1 )+(X 2i -X b2 )+S T c =(X 1c -X b1 )+(X 2c -X b2 )+S The value of the sensor at point i is X 1i , the value of the lower sensor at point i is X 2i , the sensor value at the center of the circle is X 1c , the value of the sensor at the center of the circle is X 2c , the sensor reading on the standard gauge block is X b1 , the lower sensor shows the value of X b2 , the change in the value of the upper sensor measuring point is (X 1i -X b1 ), the change in the value of the lower sensor measurement point is (X 2i -X b2 ), the thickness of the standard gauge block is S; b) Assume that the thickness of each point on the wafer takes the maximum value T at the coordinates of the maximum thickness point tmax and the minimum thickness point tmin respectively. max and the minimum value T min , the total thickness change is expressed as: TVV=T max -T min =(X 1,tmax -X b1 )+(X 2,tmax -X b2 )+S-(X 1,tmin -X b1 )-(X 2,tmin -X b2 )-S =(X 1,tmax +X 2,tmax )-(X 1,tmin +X 2,tmin ) The total thickness change is TVV, and the value of the upper sensor at tmax is X 1tmax , the upper sensor reading at tmin is X 1,tmax , the value of the lower sensor at tmax is X 2tmax , the value of the lower sensor at tmin is X 2,tmax ; c) Calculate the middle plane based on the indications of the two sensors, expressed as: The middle plane of point i is C i ; The least squares plane is obtained by fitting the middle plane using the least squares method. The expression is: L-S Reference plane(L i )=Least-squares methodfit((C i )) The Z-axis coordinate of the least squares plane at point i is L i , the least squares method is Least-squares methodfit(·), and the least squares reference plane is LS Reference plane(·); Calculate bending: The bend is Bow, the z-axis coordinate of the midplane at the center of the circle is Cc, and the z-axis coordinate of the least squares plane at the center of the circle is Lc; d) Obtain the coordinates dmax of the point where the difference is maximum and dmin of the point where the difference is minimum, and calculate the warpage: Warp=D max -D min =(L max -C max )-(L min -C min ) The maximum difference between the middle plane and the least squares plane is D at dmax. max The minimum difference between the middle plane and the least squares plane at dmin is D min , the z-axis coordinate of the least squares plane at dmax is L dmax , the z-axis coordinate of the least squares plane at dmin is L dmin , the z-axis coordinate of the middle plane at dmax is C dmax , the z-axis coordinate of the middle plane at dmin is C dmin , warping is Warp; S7) Repeat steps S4-S6 three or more times, and take the average of the three calculation results as the measurement result value.

10. The measurement method of the spectral confocal measurement device for wafer geometric characteristics according to claim 9, characterized in that: The method for correcting the deviation of the upper sensor indication value and the lower sensor indication value includes: In the temperature-controlled box, the standard displacement block data of the spectral confocal sensor at different temperatures, the original output values and true values of the upper and lower sensors are collected. The random sampling consensus algorithm is used to eliminate abnormal temperature-sensitive points, and a second-order polynomial compensation model is established. The expression is: The output value after temperature compensation is The output value is W, the real-time temperature is T, and the reference temperature is T ref , the correction coefficients are μ1 and μ2 respectively; Obtain relevant data from the spectral confocal sensor, including environmental parameters, equipment status parameters, and process characteristic parameters. Input the relevant data into the neural network deviation correction model and give the loss function, which is expressed as: The total number of samples is N, and the ath true value is U a , the corrected a-th original output value is The regularization coefficient is β, the Euclidean norm is ||·||, and the output value is The gradient of Monte Carlo simulation was used to add a temperature perturbation of ±0.5 degrees. When the temperature sensitivity was nonlinear, the model was segmented into three stages: low temperature, normal temperature, and high temperature. The segmented temperature data is input into the dynamic temperature compensation model, and the temperature deviation is obtained through dynamic re-integration. The expression is: The temperature deviation is ΔD T , the dynamic weight of the zth segment is λ z , the order is M, the jth power of the real-time temperature is (T) j , the coefficient of the j-term polynomial of the z-th segment is θ z,j ; The upper spectral confocal sensor and the lower spectral confocal sensor are compensated by temperature deviation to obtain corrected upper sensor indications and lower sensor indications.

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