Method for compensating for rotational axis rotation deviation

Abstract

A rotation axis rotation deviation compensation method, comprising: obtaining a lateral offset amount ΔX and a longitudinal offset amount ΔY of an image acquisition unit coordinate system origin relative to a rotation axis coordinate system origin; selecting a mark point on a wafer and obtaining a lateral coordinate X1 and a longitudinal coordinate Y1 of the mark point in the image acquisition unit coordinate system; calculating a theoretical rotation angle θ and a theoretical movement distance R when the mark point is moved to the image acquisition unit coordinate system origin based on rotation of the rotation axis and X-axis movement of a movement platform; obtaining a longitudinal offset amount δy of the mark point relative to the image acquisition unit coordinate system origin; calculating a rotation deviation angle Δθ of the rotation axis based on the longitudinal offset amount δy, and compensating for rotation of the rotation axis. Since all measurement data is obtained under actual operating conditions and real positions of the equipment, the rotation deviation conditions of the rotation axis in actual work can be accurately reflected, and the rotation accuracy of the rotation axis is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method for compensating for rotational deviation of a rotating shaft. Background Technology

[0002] In chip manufacturing, the rotating axis is an indispensable key component in semiconductor inspection equipment. It is primarily used to support and rotate the wafer, ensuring precise multi-angle measurements and alignment during inspection. The rotational accuracy of the axis directly affects the accuracy of overlay and critical dimension (CD) measurements in semiconductor manufacturing, and is one of the core factors ensuring chip manufacturing quality.

[0003] The primary function of the rotating axis is to sequentially move different areas on the wafer to the detection position through precise rotational movement, ensuring that each area can be accurately measured. This rotational movement requires extremely high precision to guarantee the repeatability and accuracy of the measurements. In semiconductor manufacturing, the patterns and structures on the wafer need to be measured from multiple angles to comprehensively evaluate their quality and accuracy. The precise rotation of the rotating axis makes multi-angle measurements possible, thereby improving the comprehensiveness and reliability of the inspection. Overlay accuracy refers to the alignment accuracy between different layers in multilayer lithography. The rotational accuracy of the rotating axis directly affects the overlay accuracy because the alignment between different layers of the wafer requires precise rotational control. If the rotational accuracy of the rotating axis is insufficient, it will cause deviations in the pattern on the wafer between different layers, thus affecting the chip's performance and reliability. Therefore, high-precision rotation of the rotating axis is crucial to ensuring overlay accuracy.

[0004] However, there are still many problems with the compensation of the rotational accuracy of the rotating shaft in the existing technology. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a method for compensating for rotational deviation of a rotating shaft, so as to improve the rotational compensation accuracy of the rotating shaft.

[0006] To address the aforementioned problems, the present invention provides a method for compensating for rotational deviation of a rotation axis, comprising: obtaining the lateral offset ΔX and longitudinal offset ΔY of the origin of the image acquisition unit coordinate system relative to the origin of the rotation axis coordinate system in a rectangular coordinate system; selecting a marker point on a wafer and obtaining the lateral coordinate X1 and longitudinal coordinate Y1 of the marker point in the image acquisition unit coordinate system; calculating the theoretical rotation angle θ required for the rotation axis and the theoretical movement distance R required for the movement platform X-axis when the marker point is moved to the origin of the image acquisition unit coordinate system based on the rotation of the rotation axis and the movement of the X-axis of the motion platform; after moving the marker point based on the calculated theoretical rotation angle θ and the theoretical movement distance R, obtaining the longitudinal offset δy of the marker point relative to the origin of the image acquisition unit coordinate system; calculating the rotational deviation angle Δθ of the rotation axis based on the longitudinal offset δy; and compensating for the rotation of the rotation axis based on the obtained rotational deviation angle Δθ after obtaining the rotational deviation angle Δθ.

[0007] Optionally, the theoretical travel distance R is:

[0008] θ = β - α;

[0009] , .

[0010] Optionally, the rotational deviation angle Δθ is:

[0011] .

[0012] Optionally, before obtaining the offset ΔX and longitudinal offset ΔY, the method further includes: aligning the X-axis of the motion platform coordinate system with the X-axis of the image acquisition unit coordinate system.

[0013] Optionally, the method for obtaining the longitudinal offset δy of the marker point relative to the origin of the coordinate system of the image acquisition unit includes: setting an image acquisition unit above the rotation axis, taking an image of the marker point based on the image acquisition unit, and obtaining the longitudinal offset δy of the marker point relative to the origin of the coordinate system of the image acquisition unit.

[0014] Optionally, the number of marker points can be multiple.

[0015] Optionally, the plurality of the marker points are distributed in a circular pattern on the edge region of the wafer.

[0016] Optionally, the method for compensating the rotation of the rotating axis based on the obtained rotation deviation angle Δθ includes: constructing a compensation curve over the entire rotation angle range of the rotating axis; and, during the rotation of the rotating axis, adjusting the current rotation angle θ of the rotating axis accordingly. cReal-time query of the compensation curve to obtain the corresponding rotation deviation angle Δθ; based on the rotation deviation angle Δθ and the current rotation angle θ c The rotation of the rotating shaft is compensated.

[0017] Optionally, the method for constructing the compensation curve includes: traversing each of the marker points, obtaining the theoretical rotation angle θ and the corresponding rotation deviation angle Δθ when each marker point moves to the origin of the image acquisition unit coordinate system, forming discrete error data collected within the full rotation angle range of the rotation axis; and constructing the compensation curve based on the discrete error data.

[0018] Optionally, the method for constructing a compensation curve based on discrete error data includes: dividing the angles of adjacent marker points into several intervals, performing linear interpolation fitting on the error within each interval, and generating a continuous angle-error compensation curve.

[0019] Optionally, based on the rotation deviation angle Δθ and the current rotation angle θ c The method for compensating for the rotation of the rotating axis includes: comparing the rotation deviation angle Δθ with the current rotation angle θ of the rotating axis. c The values ​​are superimposed to generate the compensated angle command.

[0020] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0021] In the method for compensating rotational deviation of a rotating axis according to the technical solution of the present invention, the wafer is placed on the rotating axis, and several marker points are selected on the surface of the wafer. With the cooperative action of the rotating axis and the motion platform, the marker points are precisely moved, and the rotational deviation angle Δθ of the rotating axis is calculated. Since all measurement data are acquired under the actual operating conditions and real positions of the equipment, they can truly and accurately reflect the rotational deviation of the rotating axis in actual operation. Furthermore, the closed-loop mapping between polar coordinates and Cartesian coordinates effectively solves the measurement distortion problem. Compensation based on this high-precision error data can more effectively offset the actual rotational error of the rotating axis, significantly improving the rotational accuracy of the rotating axis.

[0022] Furthermore, before obtaining the offset ΔX and longitudinal offset ΔY, the method further includes: aligning the X-axis of the motion platform coordinate system with the X-axis of the image acquisition unit coordinate system to be parallel, which can eliminate the initial angle deviation and thus simplify the calculation process of the theoretical rotation angle θ and the theoretical movement distance R.

[0023] Furthermore, multiple marker points are distributed circumferentially on the edge region of the wafer. Marker points at the edge positions can more comprehensively reflect the possible offset of the rotation axis during rotation because the trajectory radius of the marker points at the edge positions is larger during rotation, and their positional offset changes are more obvious, thus allowing for more accurate measurement of the rotational error of the rotation axis. Secondly, the selection of marker points at the edge positions simplifies the measurement process because edge positions are relatively easy to locate and identify, reducing the complexity and uncertainty in the measurement process.

[0024] Furthermore, the method for compensating the rotation of the rotation axis based on the acquired rotation deviation angle Δθ includes: traversing each of the marker points, acquiring the theoretical rotation angle θ when each marker point moves to the origin of the image acquisition unit coordinate system, and the corresponding rotation deviation angle Δθ, forming discrete error data acquired over the entire rotation angle range of the rotation axis; constructing a compensation curve based on the discrete error data; and during the rotation of the rotation axis, compensating for the rotation based on the current rotation angle θ of the rotation axis. c Real-time query of the compensation curve to obtain the corresponding rotation deviation angle Δθ; based on the rotation deviation angle Δθ and the current rotation angle θ c The rotation of the rotating axis is compensated. By constructing a continuous angle-error compensation curve, the gaps between discrete measurement data can be effectively filled, ensuring the integrity and continuity of the compensation curve. This allows the compensation curve to more accurately cover the error situation of the rotating axis across the entire rotation angle range, providing comprehensive and reliable data support for dynamic compensation. Attached Figure Description

[0025] Figure 1 and Figure 2 This is a schematic diagram of the measurement platform in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the coordinate system of the image acquisition unit and the coordinate system of the rotation axis in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the structure in an embodiment of the present invention where the wafer is placed on a rotation axis;

[0028] Figure 5 This is a schematic diagram illustrating the determination of the theoretical rotation angle and theoretical movement distance before moving the marker point in an embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram of the longitudinal offset obtained after moving the marker point in an embodiment of the present invention;

[0030] Figure 7 This is a schematic diagram of the rotational deviation angle obtained in an embodiment of the present invention. Detailed Implementation

[0031] As described in the background section, there are still many problems with the existing technology for compensating for the rotational accuracy of a rotating shaft. These will be explained in detail below.

[0032] Currently, the rotational accuracy of the rotating shaft mainly relies on offline measurement by external measuring sensors. However, offline measurement of the rotational deviation of the rotating shaft has a large error and cannot reflect the real offset changes of the surface of the platform under the actual working state and position. Consequently, it is impossible to accurately obtain the deviation of the rotational accuracy of the rotating shaft in actual work, making the compensation for the rotational deviation of the rotating shaft inaccurate.

[0033] Based on this, the present invention provides a method for compensating for rotational deviation of a rotating axis. This involves placing the wafer on the rotating axis and selecting several marker points on the wafer surface. By leveraging the coordinated action of the rotating axis and the motion platform, the marker points are precisely moved, and the rotational deviation angle Δθ of the rotating axis is calculated. Since all measurement data is acquired under the actual operating conditions and real positions of the equipment, it can accurately reflect the rotational deviation of the rotating axis during actual operation. Furthermore, the closed-loop mapping between polar and Cartesian coordinates effectively solves the measurement distortion problem. Compensation based on this high-precision error data can more effectively offset the actual rotational error of the rotating axis, significantly improving the rotational accuracy of the rotating axis.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0035] Figure 1 and Figure 2 This is a schematic diagram of the measurement platform in an embodiment of the present invention; Figure 3 This is a schematic diagram of the coordinate system of the image acquisition unit and the coordinate system of the rotation axis in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure in an embodiment of the present invention where the wafer is placed on a rotation axis; Figure 5 This is a schematic diagram illustrating the determination of the theoretical rotation angle and theoretical movement distance before moving the marker point in an embodiment of the present invention; Figure 6 This is a schematic diagram of the longitudinal offset obtained after moving the marker point in an embodiment of the present invention; Figure 7 This is a schematic diagram of the rotational deviation angle obtained in an embodiment of the present invention.

[0036] Please refer to Figure 1 and Figure 2 , and build a measurement platform.

[0037] In this embodiment, the structure and function of the measurement platform are designed to ensure complete online in-situ measurement. The measurement platform mainly includes the following key components: a motion platform 100, a rotation axis 101, a wafer 102, and an image acquisition unit 103. Each of these components has an independent coordinate system.

[0038] The motion platform 100 is the basic structure of the measurement platform, and it includes an X-axis 1001 and a Y-axis 1002 connected to each other. The motion platform 100 has a motion platform coordinate system S1. The main function of the motion platform 100 is to provide precise planar motion control, ensuring that the rotation axis 101 can be accurately moved to a specified position in the X-axis 1001 and Y-axis 1002 directions.

[0039] The rotating shaft 101 is mounted on the motion platform 100 and is moved by the motion platform 100. The rotating shaft 101 itself can rotate and has an independent rotating axis coordinate system S2. The main function of the rotating shaft 101 is to attract and fix the wafer 102, while providing rotational motion to meet the measurement requirements of the wafer 102 at different angles during the measurement process.

[0040] The wafer 102 is the object being measured, which is attached and fixed to the rotation axis 101 and has a wafer coordinate system S3. The wafer coordinate system S3 is defined based on the geometric center and orientation of the wafer 102 itself and is used to describe the positions of marked points on the wafer 102. In actual operation, the position of the wafer 102 on the rotation axis 101 is not fixed, as long as the rotation axis 101 can hold the wafer 102 in place. Therefore, the origin of the wafer coordinate system S3 and the origin of the rotation axis coordinate system S2 will almost never coincide. Only in very rare coincidences will the origins of the wafer coordinate system S3 and the rotation axis coordinate system S2 coincide when the wafer 102 is placed on the rotation axis 101.

[0041] The image acquisition unit 103 is positioned above the wafer 102 and is used to capture images of the marker points on the wafer 102. It also has an image acquisition unit coordinate system S4. The main function of the image acquisition unit 103 is to capture the position information of the marker points on the wafer 102 in real time.

[0042] In this embodiment, before obtaining the lateral offset ΔX and longitudinal offset ΔY, the coordinate systems mentioned above need to be precisely aligned to facilitate the subsequent calculation process. The specific steps are as follows: unifying the motion reference, that is, by rotating the rotation axis 101, the X-axis of the rotation axis coordinate system S2 is parallel to the X-axis of the wafer coordinate system S3 and parallel to the X-axis of the image acquisition unit coordinate system S4. The purpose of this step is to eliminate initial angular deviations, ensure the foundation for coordinate system alignment, and thus simplify the subsequent calculation of theoretical rotation angle θ and theoretical movement distance R. Adjusting the X-axis of the rotation axis coordinate system S2 to be parallel with the X-axis of the motion platform coordinate system S1 ensures that the movement direction of the motion platform 100 is the direction in which the subsequent marker points will move. The origins of the rotation axis coordinate system S2 and the motion platform coordinate system S1 can also remain coincident. Unifying the measurement reference, the origins of the motion platform coordinate system S1 and the rotation axis coordinate system S2 in the measurement platform coincide. Then, by adjusting the position of the image acquisition unit 103, the origin of the image acquisition unit coordinate system S4 coincides with the origin of the wafer coordinate system S3. This step aims to ensure spatial consistency between the measurement values ​​of the image acquisition unit 103 and the wafer coordinate system S3, thereby enabling the direct acquisition of accurate position information of the marker points on the wafer 102 during subsequent measurements and simplifying the subsequent calculation of theoretical rotation angle θ and theoretical movement distance R.

[0043] Please refer to Figure 3 The horizontal offset ΔX and vertical offset ΔY of the origin of the image acquisition unit coordinate system S4 relative to the origin of the rotation axis coordinate system S2 are obtained.

[0044] In this embodiment, after unifying the motion reference and measurement reference, the offset of the origin of the image acquisition unit coordinate system S4 relative to the origin of the rotation axis coordinate system S2 is obtained. The specific steps are as follows: The lateral offset ΔX and longitudinal offset ΔY of the origin of the image acquisition unit coordinate system S4 relative to the origin of the rotation axis coordinate system S2 are obtained through direct measurement. If the origin of the rotation axis coordinate system S2 coincides with the origin of the image acquisition unit coordinate system S4, then the values ​​of both the lateral offset ΔX and longitudinal offset ΔY are 0. Obtaining the offsets ΔX and ΔY of the origin of the image acquisition unit coordinate system S4 relative to the origin of the rotation axis coordinate system S2 reflects the actual placement position of the wafer 102 on the rotation axis 101, providing basic data for subsequent measurement and compensation.

[0045] It should be noted that in this embodiment, the horizontal offset ΔX and the vertical offset ΔY have positive and negative values. The horizontal offset ΔX is the abscissa of the origin of the image acquisition unit coordinate system S4 in the rotation axis coordinate system, and the vertical offset ΔY is the ordinate of the origin of the image acquisition unit coordinate system S4 in the rotation axis coordinate system. Figure 3The image acquisition unit coordinate system S4 origin is located in the first quadrant of the rotation axis coordinate system, so the corresponding horizontal offset ΔX and vertical offset ΔY are both positive values.

[0046] In other embodiments, if the origin of the image acquisition unit coordinate system S4 is located in the second quadrant of the rotation axis coordinate system, the corresponding lateral offset ΔX is negative and the longitudinal offset ΔY is positive; if the origin of the image acquisition unit coordinate system S4 is located in the third quadrant of the rotation axis coordinate system, both the corresponding lateral offset ΔX and the longitudinal offset ΔY are negative; if the origin of the image acquisition unit coordinate system S4 is located in the fourth quadrant of the rotation axis coordinate system, the corresponding lateral offset ΔX is positive and the longitudinal offset ΔY is negative.

[0047] Please refer to Figure 4 Marker point 104 is selected on the wafer 102, and the horizontal coordinate X1 and vertical coordinate Y1 of the marker point 104 in the image acquisition unit coordinate system S4 are obtained.

[0048] In this embodiment, there are multiple marker points 104, and these marker points 104 are distributed circumferentially on the edge region of the wafer 102. The marker points 104 at the edge positions can more comprehensively reflect the possible offset of the rotation axis 101 during rotation because the trajectory radius of the marker points 104 at the edge positions is larger during rotation, and their positional offset changes are more obvious, thus allowing for more accurate measurement of the rotation error of the rotation axis 101. Secondly, the selection of marker points 104 at the edge positions simplifies the measurement process because the edge positions are relatively easy to locate and identify, reducing the complexity and uncertainty in the measurement process.

[0049] In this embodiment, Figure 4 Only one of the marker points 104 currently being measured is shown in the image.

[0050] In this embodiment, the number of marker points 104 is 30 to 50.

[0051] In this embodiment, for ease of observation, the edge of the wafer 102 is tangent to the edge of the rotation axis 101, that is, the marker point 104 is also located at the edge of the rotation axis 101.

[0052] Please refer to Figure 5 Calculate the theoretical rotation angle θ required by the rotation axis 101 and the theoretical movement distance R required by the motion platform X-axis 1001 when the marker point 104 is moved to the origin of the image acquisition unit coordinate system S4 based on the rotation of the rotation axis 101 and the movement of the motion platform X-axis 1001.

[0053] In this embodiment, the corresponding theoretical rotation angle θ and the theoretical movement distance R are:

[0054] θ = β - α;

[0055] , .

[0056] It should be noted that in the theoretical model of the measurement platform 100, the theoretical rotation angle θ and the theoretical movement distance R are parameters calculated based on ideal conditions. Ideally, assuming the rotation axis 101 has no rotational deviation (here it is assumed that the motion platform X-axis 1001 has no movement deviation), after rotating the rotation axis 101 by the theoretical rotation angle θ and moving the motion platform X-axis 1001 by the theoretical movement distance R, the marker point 104 should precisely coincide with the origin of the image acquisition unit coordinate system S4. However, in actual operation, the rotation axis 101 inevitably has a rotational deviation. This means that after rotating the rotation axis 101 by the theoretical rotation angle θ and moving the motion platform X-axis 1001 by the theoretical movement distance R, the marker point 104 cannot coincide with the origin of the image acquisition unit coordinate system S4. This deviation leads to a difference between the actual measurement result and the theoretical expectation. To correct this deviation, subsequent steps require accurate calculation of the actual rotational deviation angle of the rotation axis 101. This step determines the rotational deviation of the rotation axis 101 by comparing the actual position of the marker point 104 after actual rotation and movement with the theoretical position of the origin of the image acquisition unit coordinate system S4. By calculating this deviation angle, the rotation of the rotation axis 101 can be compensated, thereby improving the rotational accuracy of the rotation axis 101.

[0057] In this embodiment, the calculated theoretical rotation angle θ ranges from 0° to 360°. The rotation axis rotates clockwise based on the theoretical rotation angle θ, ensuring that the marker point 104 is always rotated to coincide with the X-axis of the image acquisition unit coordinate system S4. The motion platform X-axis 1001 then moves the marker point 104 by the theoretical distance R in the negative X-axis direction. Furthermore, during the formula calculation, the horizontal coordinate X1 and vertical coordinate Y1 of the marker point 104 also have positive and negative values. Figure 5 The diagram shows that the marker point 104 is located in the first quadrant of the image acquisition unit coordinate system S4, so the corresponding horizontal coordinate X1 and vertical coordinate Y1 are both positive values.

[0058] In other embodiments, if the marker point is located in the second quadrant of the image acquisition unit coordinate system S4, the corresponding horizontal coordinate X1 is negative and the vertical coordinate Y1 is positive; if the marker point is located in the third quadrant of the image acquisition unit coordinate system S4, the corresponding horizontal coordinate X1 and vertical coordinate Y1 are both negative; if the marker point is located in the fourth quadrant of the image acquisition unit coordinate system S4, the corresponding horizontal coordinate X1 is positive and the vertical coordinate Y1 is negative.

[0059] In this embodiment, before calculating the theoretical rotation angle θ and the theoretical movement distance R, the method further includes defining the positive and negative directional properties of the rotation axis 101 during counterclockwise and clockwise rotation. By defining the positive and negative directional properties of the rotation direction, a clear and consistent rotation direction reference is provided for the subsequent measurement and compensation process, avoiding directional ambiguity that may occur during angle calculation.

[0060] Please refer to Figure 6 After moving the marker point 104 based on the calculated theoretical rotation angle θ and theoretical moving distance R, the longitudinal offset δy of the marker point 104 relative to the origin of the image acquisition unit coordinate system S4 is obtained.

[0061] In this embodiment, the method for obtaining the longitudinal offset δy of the marker point 104 relative to the origin of the image acquisition unit coordinate system S4 includes: taking a picture of the marker point 104 based on the image acquisition unit 103, and obtaining the longitudinal offset δy of the marker point 104 relative to the origin of the image acquisition unit coordinate system S4.

[0062] It should be noted that during the operation of the measurement platform, in order to ensure that the image acquisition unit 103 can accurately capture the marker point 104 on the wafer 102, the field of view of the image acquisition unit 103 and the position of the marker point 104 need to be precisely adjusted. Since the field of view of the image acquisition unit 103 is a very small area centered on the origin of the image acquisition unit coordinate system S4, simply rotating the rotation axis 101 to make the marker point 104 coincide with the X-axis of the image acquisition unit coordinate system S4 is insufficient. At this time, the marker point 104 may still be located at a relatively far position outside the field of view of the image acquisition unit 103 and cannot be captured by the image acquisition unit 103. To bring the marker point 104 into the field of view of the image acquisition unit 103, the X-axis 1001 of the motion platform is required. Specifically, the X-axis 1001 of the motion platform moves the marker point 104 along the X-axis until the marker point 104 faces the field of view of the image acquisition unit 103. The optimal stopping position for the motion platform X-axis 1001 to move the moving marker 104 is the origin of the image acquisition unit coordinate system S4. This position should also coincide with the origin of the image acquisition unit coordinate system S4. This adjustment ensures that the marker 104 is within the field of view of the image acquisition unit 103, thereby enabling accurate measurement of the marker 104.

[0063] Please refer to Figure 7 The rotational deviation angle Δθ of the rotating shaft 101 is calculated based on the longitudinal offset δy.

[0064] In this embodiment, the calculated rotational deviation angle Δθ is the angle of rotational deviation of the rotation axis 101, and the rotational deviation angle Δθ is:

[0065] .

[0066] By placing the wafer 102 on the rotation axis 101 and selecting a plurality of marker points 104 on the surface of the wafer 102, the marker points 104 are precisely moved by means of the coordinated action of the rotation axis 101 and the motion platform, and the rotational deviation angle Δθ of the rotation axis 101 is calculated. Since all measurement data are acquired under the actual operating conditions and real positions of the equipment, they can truly and accurately reflect the rotational deviation of the rotation axis 101 in actual operation. In addition, the closed-loop mapping between polar coordinates and Cartesian coordinates can effectively solve the measurement distortion problem. Compensation based on these high-precision error data can more effectively offset the actual rotational error of the rotation axis 101, significantly improving the rotational accuracy of the rotation axis 101.

[0067] It should be noted that, in this embodiment, Figure 7 The dashed blue and green circles represent the initial positions of the wafer 102 and the rotation axis 101. For ease of understanding the calculation process, these initial positions are shown as follows: Figure 7 It will be retained and displayed in the text.

[0068] Please continue to refer to this. Figure 7 After obtaining the rotation deviation angle Δθ, the rotation of the rotating shaft 101 is compensated according to the obtained rotation deviation angle Δθ.

[0069] In this embodiment, the method for compensating the rotation of the rotation axis 101 based on the acquired rotation deviation angle Δθ includes: traversing each of the marker points 104, acquiring the theoretical rotation angle θ and the corresponding rotation deviation angle Δθ when each marker point 104 moves to the origin of the image acquisition unit coordinate system S4, forming discrete error data acquired over the entire rotation angle range of the rotation axis 101; constructing a compensation curve based on the discrete error data; and during the rotation of the rotation axis 101, compensating for the rotation based on the current rotation angle θ of the rotation axis 101. c Real-time query of the compensation curve to obtain the corresponding rotation deviation angle Δθ; based on the rotation deviation angle Δθ and the current rotation angle θ c The rotation of the rotating shaft 101 is compensated.

[0070] By constructing a continuous angle-error compensation curve, the gaps between discrete measurement data can be effectively filled, ensuring the integrity and continuity of the compensation curve. This allows the compensation curve to more accurately cover the error situation of the rotating shaft 101 within the full rotation angle range, providing comprehensive and reliable data support for dynamic compensation.

[0071] In this embodiment, the method for constructing a compensation curve based on discrete error data includes: dividing the angles of adjacent marker points 104 into several intervals, performing linear interpolation fitting on the error in each interval, and generating a continuous angle-error compensation curve.

[0072] In this embodiment, based on the rotation deviation angle Δθ and the current rotation angle θ c The method for compensating for the rotation of the rotation axis 101 includes: comparing the rotation deviation angle Δθ with the current rotation angle θ of the rotation axis 101. c The values ​​are superimposed to generate the compensated angle command.

[0073] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for compensating rotational deviation of a rotating shaft, characterized in that, include: Obtain the horizontal offset ΔX and vertical offset ΔY of the origin of the image acquisition unit coordinate system relative to the origin of the rotation axis coordinate system in the rectangular coordinate system; Marking points are selected on the wafer, and the horizontal coordinates X1 and vertical coordinates Y1 of the marking points in the coordinate system of the image acquisition unit are obtained; Calculate the theoretical rotation angle θ required for the rotation axis and the theoretical movement distance R required for the X-axis of the motion platform when the marker point is moved to the origin of the image acquisition unit coordinate system; After moving the marker point based on the calculated theoretical rotation angle θ and theoretical moving distance R, the longitudinal offset δy of the marker point relative to the origin of the image acquisition unit coordinate system is obtained; The rotational deviation angle Δθ of the rotating axis is calculated based on the longitudinal offset δy; After obtaining the rotation deviation angle Δθ, the rotation of the rotation axis is compensated based on the obtained rotation deviation angle Δθ; wherein, The theoretical travel distance R is: R= ,θ=β-α; β=arctan ,α=acrsin( ); The rotational deviation angle Δθ is: Δθ=arcsin( )-a.

2. The method for compensating rotational deviation of a rotating shaft as described in claim 1, characterized in that, Before obtaining the offset ΔX and longitudinal offset ΔY, the following steps are also included: aligning the X-axis of the motion platform coordinate system with the X-axis of the image acquisition unit coordinate system.

3. The method for compensating rotational deviation of a rotating shaft as described in claim 1, characterized in that, The method for obtaining the longitudinal offset δy of the marker point relative to the origin of the coordinate system of the image acquisition unit includes: setting an image acquisition unit above the rotation axis, taking an image of the marker point based on the image acquisition unit, and obtaining the longitudinal offset δy of the marker point relative to the origin of the coordinate system of the image acquisition unit.

4. The method for compensating rotational deviation of a rotating shaft as described in claim 1, characterized in that, The number of marker points is multiple.

5. The method for compensating rotational deviation of a rotating shaft as described in claim 4, characterized in that, The multiple marker points are distributed in a circular pattern on the edge region of the wafer.

6. The method for compensating rotational deviation of a rotating shaft as described in claim 5, characterized in that, The method for compensating the rotation of the rotating shaft based on the obtained rotation deviation angle Δθ includes: constructing a compensation curve over the entire rotation angle range of the rotating shaft; during the rotation of the rotating shaft, adjusting the current rotation angle θ of the rotating shaft... c Real-time query of the compensation curve to obtain the corresponding rotation deviation angle Δθ; based on the rotation deviation angle Δθ and the current rotation angle θ c The rotation of the rotating shaft is compensated.

7. The method for compensating rotational deviation of a rotating shaft as described in claim 6, characterized in that, The method for constructing the compensation curve includes: traversing each of the marker points, obtaining the theoretical rotation angle θ and the corresponding rotation deviation angle Δθ when each marker point moves to the origin of the coordinate system of the image acquisition unit, forming discrete error data collected within the full rotation angle range of the rotation axis; and constructing the compensation curve based on the discrete error data.

8. The method for compensating rotational deviation of a rotating shaft as described in claim 7, characterized in that, The method for constructing a compensation curve based on discrete error data includes: dividing the angles of adjacent marker points into several intervals, performing linear interpolation fitting on the error within each interval, and generating a continuous angle-error compensation curve.

9. The method for compensating rotational deviation of a rotating shaft as described in claim 6, characterized in that, Based on the rotation deviation angle Δθ and the current rotation angle θ c The method for compensating for the rotation of the rotating axis includes: comparing the rotation deviation angle Δθ with the current rotation angle θ of the rotating axis. c The values ​​are superimposed to generate the compensated angle command.

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