Interferometer error calibration method and device and computer readable storage medium

Abstract

The invention discloses an interferometer error calibration method and device and a computer readable storage medium, and belongs to the technical field of measurement equipment.The method comprises the steps that measurement data collected when an interferometer moves on the x / y axis of a motion table is obtained, and x / y axis compensation amount is generated through calculation processing; meanwhile, a coordinate system transformation matrix is established and optimized by using data of a marking plate arranged on a motion table, and x-axis and y-axis non-orthogonal parameters are obtained. And then the compensation amount and the non-orthogonal parameters are input into a preset kinematic model, and the accurate position of the motion platform under the global coordinate system is calculated in real time. And when a preset updating condition is met, dynamically updating the error compensation value of the interferometer through the deviation between the actual position detected by the visual system and the calculated position. Reflector surface type error compensation and non-orthogonal parameter correction are fused, and high-precision error compensation calibration of the interferometer is achieved.

Description

Technical Field

[0001] This application relates to the field of measurement equipment technology, specifically to an interferometer error calibration method, apparatus, and computer-readable storage medium. Background Technology

[0002] Dual-frequency laser interferometers, as high-precision displacement interferometers, achieve nanometer-level displacement detection by emitting two laser beams with a fixed frequency difference and utilizing the changes in interference fringes after the beams return from the motion stage's reflector. This system constructs reference and measurement optical paths using optical components such as beam splitters and polarizers, outputting real-time x / y / Z-axis position data. It is widely used in applications requiring sub-micron-level positioning, such as semiconductor lithography machines and precision machine tools. Current interferometer systems suffer from the following problems: ① Hardware-level issues: reflector surface shape errors cause beam deflection distortion; ② Installation-level issues: xy-axis non-orthogonality leads to Abbe errors; ③ Environmental-level issues: temperature / pressure changes cause thermal deformation of the metal structure and air refractive index drift. Summary of the Invention

[0003] An interferometer error calibration method, apparatus, and computer-readable storage medium are provided, which can achieve collaborative calibration and real-time compensation of multi-source errors through dynamic compensation of reflective surface type, multi-position calibration of small-size marker plate, and error correction technology.

[0004] Firstly, an interferometer error calibration method is provided, including:

[0005] Acquire the first measurement data collected by the interferometer during the motion of the motion stage along the x-axis and y-axis, and perform compensation calculation processing based on the first measurement data to generate x-axis compensation and y-axis compensation.

[0006] Second measurement data of the marker plate arranged on the motion table is obtained, and a coordinate system transformation matrix is ​​established based on the second measurement data to perform parameter optimization processing to obtain the non-orthogonal parameters of the xy axis;

[0007] The x-axis compensation amount, the y-axis compensation amount, the x-axis non-orthogonal error parameter, and the y-axis non-orthogonal error parameter are input into a preset kinematic model to calculate the compensated position of the motion table in the global coordinate system.

[0008] Under the condition that the preset compensation update conditions are met, the error compensation value of the interferometer is updated according to the deviation between the actual position of the motion stage obtained by the visual inspection system and the compensated position.

[0009] Secondly, a measurement system error calibration device is also provided, comprising:

[0010] The first data processing module is configured to acquire the first measurement data collected by the interferometer during the motion of the motion stage along the x-axis and y-axis, and to perform compensation calculation processing based on the first measurement data to generate x-axis compensation and y-axis compensation.

[0011] The second data processing module is configured to acquire second measurement data from a marker plate arranged on the motion table, establish a coordinate system transformation matrix based on the second measurement data to perform parameter optimization processing, and obtain non-orthogonal parameters of the xy axis.

[0012] The position calculation module is configured to input the x-axis compensation amount, the y-axis compensation amount, the x-axis non-orthogonal error parameter, and the y-axis non-orthogonal error parameter into a preset kinematic model to calculate the compensated position of the motion platform in the global coordinate system.

[0013] The compensation update module is configured to update the error compensation value of the interferometer based on the deviation between the actual position of the motion stage obtained by the visual inspection system and the compensated position, provided that preset compensation update conditions are met.

[0014] Thirdly, a computer-readable storage medium is also provided, on which a computer program is stored, which is loaded by a processor to perform the steps in any of the above-described methods or design schemes.

[0015] Beneficial effects:

[0016] This application achieves high-precision error compensation calibration of the interferometer by fusing dynamically generated mirror-type error compensation quantities with xy-axis non-orthogonal parameters, effectively solving the problem of coordinated compensation for multi-source errors such as mirror deformation and mechanical non-orthogonality in traditional measurement systems. Specifically: First, based on the first measurement data acquired by the interferometer, the geometric error components along the x / y axes are analyzed using mirror-type dynamic compensation technology to generate mirror-type error compensation quantities (including x-axis compensation and y-axis compensation). Second, after calibration using markers placed at multiple coordinate positions of the motion stage and obtaining the second measurement data, a coordinate transformation matrix is ​​constructed and the xy-axis non-orthogonal parameters are obtained. Finally, the mirror-type error compensation quantities and xy-axis non-orthogonal parameters are input into a preset kinematic model to achieve real-time fusion of the first and second measurement data, obtaining the compensated position of the motion stage in the global coordinate system. When a preset compensation update condition is detected, the error compensation value of the interferometer is dynamically updated according to the compensated position of the motion stage. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of an interferometer error calibration method provided in some embodiments of this application;

[0019] Figure 2 This is a schematic diagram of an interferometer provided in some embodiments of this application;

[0020] Figure 3 This is a schematic diagram of a marking plate provided in some embodiments of this application;

[0021] Figure 4 This is a flowchart illustrating the calculation of non-orthogonal parameters of x / y provided in some embodiments of this application;

[0022] Figure 5 This is a flowchart of an interferometer error calibration method provided in some other embodiments of this application;

[0023] Figure 6 This is a schematic diagram of x-direction surface compensation provided in some embodiments of this application;

[0024] Figure 7 This is a schematic diagram of y-direction surface compensation provided in some embodiments of this application;

[0025] Figure 8 This is a schematic diagram illustrating the variation of error compensation values ​​provided in some embodiments of this application;

[0026] Figure 9 This is a structural block diagram of an interferometer error calibration device provided in some embodiments of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 201-x interferometer; 202-y interferometer; 203-x mirror; 204-y mirror; 205-motion stage;

[0029] 301 - Marking plate; 302 - Fixed marking;

[0030] 901 - First data processing module; 902 - Second data processing module; 903 - Position calculation module;

[0031] 904 - Compensation Update Module. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0034] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0035] The use of "applies to" or "configured to" in this application implies open and inclusive language, which does not exclude the applicability to or configuration to devices performing additional tasks or steps. Additionally, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0036] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0037] The purpose of this application is to solve the measurement deviation problem caused by reflector surface shape error, xy-axis non-orthogonality error, and environmental time-varying error in interferometers (such as dual-frequency laser interferometers). The x-axis and y-axis compensation amounts are calculated using first measurement data (real-time motion data of the interferometer), and a coordinate transformation matrix is ​​constructed using second measurement data (visual calibration data of the marker plate) to solve for the xy-axis non-orthogonality parameters. Finally, the data is input into a preset kinematic model to achieve multi-source data fusion calibration. This application overcomes the limitations of traditional single-factor compensation, and particularly solves the coupling error problem not covered by existing technologies, such as full-stroke calibration of small-size marker plates and local heat source deformation compensation, significantly improving the positioning accuracy and stability of the imprinting equipment.

[0038] On the one hand, this embodiment provides an interferometer error calibration method, such as Figure 1 As shown, it includes:

[0039] S110: Acquire the first measurement data collected by the interferometer during the motion of the motion stage along the x-axis and y-axis, perform compensation calculation processing based on the first measurement data, and generate x-axis compensation and y-axis compensation.

[0040] For example, the compensation calculation based on the first measurement data includes: performing a recursive operation on the mirror-type data acquired by the interferometer to calculate the x / y axis translation compensation amount (e.g., M) for each measurement point. x M y ) and rotational compensation amount (such as R) zx ,R zy The compensation amount of the reflector at any position is calculated by using a preset subspline interpolation, and the compensation amount of the x-axis and the compensation amount of the y-axis are obtained.

[0041] like Figure 2 As shown, Figure 2 This diagram illustrates a measurement system for a motion stage. In this system, the motion stage 205 has two motion directions: the x-axis and the y-axis. For the x-axis, there is an x-interferometer 201, whose signal is transmitted through an x-mirror 203, allowing the acquisition of x, x, and other data. For the y-axis, there is a y-interferometer 202, whose signal is transmitted through a y-mirror 204, allowing the acquisition of y, y, and other data. This diagram shows the layout of the interferometers and mirrors in the motion stage measurement system and their signal transmission relationship. It is used to measure and acquire data about the motion of the stage in the x and y-axis directions, enabling the monitoring and analysis of parameters such as the stage's position.

[0042] The measurement process begins by moving the motion stage to the maximum travel of the x-axis and the zero position of the y-axis. A fixed interval L is used as the step distance, and the interferometer's measurement system collects corresponding data at each point. Subsequently, the x and y axes are reversed, and the motion stage is moved to the maximum travel of the y-axis and the zero position of the x-axis. Data is collected using the same fixed interval L.

[0043] Taking the calculation of x-axis translation compensation as an example, the recursive formula for its calculation is as follows:

[0044]

[0045] Among them, M x This represents the mirror translation compensation amount along the x-axis (i.e., the x-axis translation compensation amount). d represents the average value of the measured x-axis rotational compensation around the z-axis. x The distance between the two measuring beams of the x-axis interferometer is denoted as .

[0046] Taking the calculation of y-axis translation compensation as an example, the recursive formula for its calculation is as follows:

[0047]

[0048] Among them, M y This is the y-axis mirror translation compensation amount (i.e., the y-axis translation compensation amount). d represents the average value of the measured y-axis rotational compensation around the z-axis. y The distance between the two measuring beams of the y-axis interferometer is denoted as .

[0049] The compensation amounts mentioned above are for each measurement point. The compensation amounts for the reflector at any position (i.e., the x-axis compensation amount and the y-axis compensation amount) need to be calculated by spline interpolation for a preset number of times (e.g., three times).

[0050] S120: Obtain the second measurement data of the marker plate arranged on the motion table, establish a coordinate system transformation matrix based on the second measurement data to perform parameter optimization processing, and obtain the non-orthogonal parameters of the xy axis.

[0051] For example, the marking plate is a marking plate with a high-precision array pattern, and the acquisition of the second measurement data includes: collecting marking data multiple times at different coordinate positions of the motion table through a vision detection system; such that the collected marking positions cover the working stroke of the motion table.

[0052] like Figure 3 As shown, Figure 3A high-precision square marker plate for calibrating non-orthogonal coefficient parameters is shown. The marker plate 301 has m (9 in the figure) cross-shaped fixed markers 302 arranged on it (e.g., forming a 3×3 array). The nominal position (nx, ny) of each fixed marker 302 is known. The marker plate 301 is fixed at a reference position on the motion stage. A vision inspection device is used to inspect the array of fixed markers on the marker plate, and the detected position and corresponding nominal position of each fixed marker 302 are recorded. The marker plate is placed in different positions k times, so that the detected positions of the fixed markers 302 cover the working stroke of the motion stage. The second measurement data of each fixed marker 302 in the interferometer coordinate system is then obtained through the vision inspection system.

[0053] Specifically, the step of collecting marker data multiple times at different coordinate positions of the motion platform using a visual detection system includes: moving the marker plate sequentially to multiple different coordinate positions and fixing it according to a preset movement path, wherein the movement path covers the working stroke of the motion platform; for each fixed position marker plate, moving it sequentially to each marker using the visual detection system, detecting and recording the marker position; until the recorded marker position covers the working stroke of the motion platform.

[0054] like Figure 4 As shown, calculating the non-orthogonal parameters of x / y using a visual inspection system includes:

[0055] S401: Move the marker plate to a certain position and fix it.

[0056] S402: The visual inspection system moves to a fixed mark.

[0057] S403: The visual inspection system detects and records the position of the fixed marker.

[0058] S404: Determine whether all fixed markers have been detected.

[0059] If not completed, return to S402 to continue detecting other fixed markers; if completed, proceed to the next step.

[0060] S405: Determine whether the position of the fixed mark covers the working stroke of the operating table.

[0061] If not covered, move the marker to the new position and repeat steps S401-S404;

[0062] If it is covered, proceed to the next step.

[0063] For example, the working stroke of the motion table is -270mm to +270mm on the x-axis and -250mm to +250mm on the y-axis.

[0064] S406: Use an optimization algorithm to calculate nonorthogonal parameters.

[0065] Figure 4 By detecting multiple locations marked on the marker plate, sufficient data is obtained to calculate non-orthogonal parameters, thereby calibrating the system error.

[0066] For example, the step of establishing a coordinate system transformation matrix based on the second measurement data for parameter optimization includes: constructing a matrix containing an x-axis scaling factor (such as S). x ), y-axis scaling factor (such as S) y The objective function is defined as the x-axis non-orthogonal parameter and the rotation angle (e.g., α). The objective function is solved using an unconstrained nonlinear optimization algorithm to obtain the x-axis non-orthogonal parameters, which include the x-axis non-orthogonal error parameter, the y-axis non-orthogonal error parameter, and the non-orthogonal coupling error parameter between the x and y axes.

[0067] Assume the non-orthogonal parameters of the interferometer are:

[0068]

[0069] Among them, S x S is the x-axis scaling factor, representing the x-axis non-orthogonality error parameter; y α is the Y-axis scaling factor, representing the non-orthogonal error parameter of the y-axis; α is the rotation angle, representing the non-orthogonal coupling error parameter between the x and y axes, reflecting the installation deviation between the interferometer's X and Y axes, and is the interferometer's own error; T ix T iy This is the translation amount, which is ignored here. Setting the translation amount to 0 simplifies the non-orthogonal parameters to:

[0070]

[0071] The coordinate system of the marker plate and the coordinate system of the interferometer measurement system are rotated and translated. Assume that their coordinate transformation matrix is:

[0072]

[0073] Where β is the rotation angle between the marker plate coordinate system and the interferometer measurement system coordinate system (reflecting the rotational deviation between the marker plate and the interferometer coordinate system during installation, representing an externally introduced error), and T mx T my Let be the translation amount. For one mark on a marker plate placed at a certain position, its coordinate transformation matrix and the non-orthogonality parameters of the interferometer measurement system should satisfy:

[0074]

[0075] in, For the marked detection location, Let be the nominal position of the marker. Based on this formula, construct an optimization problem with the following optimization variables:

[0076]

[0077] Among them, S x S y α is the non-orthogonal parameter of the interferometer (i.e., S). x S is the non-orthogonal error parameter of the x-axis. y α is the non-orthogonal error parameter of the y-axis, and β is the non-orthogonal coupling error parameter between the x and y axes; k , The coordinate system transformation matrix (also known as the rigid transformation matrix) parameter when placing the marker at the k-th position.

[0078] The objective function is:

[0079]

[0080] Where m is the number of marker patterns and k is the number of repetitions. Let be the nominal coordinates of the j-th mark pattern on the mark plate during the i-th placement. The detection coordinates of the same marked pattern under the interferometer measurement system are given, and the constraints are set to be unconstrained. The unconstrained nonlinear optimization problem can be solved using an unconstrained nonlinear optimization algorithm (such as the BFGS algorithm, a quasi-Newton method used to solve unconstrained nonlinear optimization problems) to obtain the aforementioned nonorthogonal parameter S. x ,S y ,α.

[0081] S130: Input the x-axis compensation amount, y-axis compensation amount, x-axis non-orthogonal error parameter, and y-axis non-orthogonal error parameter into the preset kinematic model to calculate the compensated position of the motion table in the global coordinate system.

[0082] For example, the preset kinematic model is a six-degree-of-freedom motion model, including: x-axis translation, y-axis translation component, z-axis translation; and rotation around the x-axis, y-axis rotation, and z-axis rotation component. The x-axis translation, y-axis translation component, and z-axis translation are used to correct for mechanical offsets caused by optical path difference and thermal expansion; the rotation around the x-axis, y-axis rotation, and z-axis rotation component are used to compensate for Abbe error and angular deviations caused by the tilt of the reflector installation. By coupling the translation and rotation parameters, the rigid body motion error of the motion stage in three-dimensional space can be comprehensively characterized, thereby achieving higher-precision multi-degree-of-freedom dynamic compensation through matrix operations.

[0083] Understandably, the x / y axis compensation amount comes from the mirror surface shape measurement (step S110), and the dynamic compensation amount at any position is calculated by interpolation to eliminate the unevenness error of the mirror surface; the x / y axis non-orthogonal parameter (S x,S y , α) from the calibration of the marking plate (step S120), optimize and solve the scaling factor (S x ,S y ) and the rotation angle (α), and correct the coordinate system distortion caused by the installation error. The global coordinate system is the unified reference coordinate system of the device, whose origin is aligned with the mechanical zero point of the moving stage, and the xy-axis direction is consistent with the ideal orthogonal moving axis. Different from the local coordinate system of the interferometer (there are deviations due to installation errors and the surface shape of the reflecting mirror). The kinematic model first performs a non-orthogonal transformation on the original coordinates of the interferometer (including the correction of the scaling factor S x / S y and the rotation angle α), and then superimposes the compensation amount of the reflecting mirror, and finally outputs the accurate position in the global coordinate system. The whole process runs dynamically, effectively solving the coupled influence of the surface shape error of the reflecting mirror, the non-orthogonal error of the moving axis and the system drift error, and improving the positioning accuracy of the imprinting device.

[0084] Exemplarily, the six-degree-of-freedom position of the moving stage can be calculated according to the following formula:

[0085]

[0086] Zg = -Rx 2 ×X + dzxxa×Rx 2 + Rx×Rz×X + dzxza×Rx×Rz - 2×Ry 2 ×X + dzyya×Ry 2 + ezxya×Ry×X + dzzza×Rz 2 + Ry×Z + ezya×Ry - mz + XTZ + YTZ;

[0087] In the above formula, Xg, Rzxg, Ryg, Yg, Rzyg, Rxg, Zg are denoted as the six-degree-of-freedom positions of the moving stage at the current moment; while X, Rzx, Ry, Y, Rzy, Rx, Z on the right side of the equation are the six-degree-of-freedom positions of the moving stage at the previous moment.

[0088] In the above formula, dRyix, dRziy, ux, dRxiy, dRziy, wy are non-orthogonal machine constants. If these constants are not calibrated, they can be considered zero.

[0089] YTX represents the influence of the X long strip mirror surface shape on X when the moving stage moves along the Y direction;

[0090] YRZ represents the influence of the X long strip mirror surface shape on RZ when the moving stage moves along the Y direction;

[0091] XTY represents the influence of the Y long strip mirror surface shape on X when the moving stage moves along the X direction;

[0092] XRZ represents the effect of the Y-shaped long mirror surface on RZ when the motion table moves along the X direction.

[0093] XTZ represents the effect of the Y-shaped long mirror surface on the Z direction when the motion table moves along the X direction;

[0094] YTZ represents the effect of the motion stage moving along the Y direction on the Z direction by the 45° reflector and the X-shaped long strip mirror.

[0095] Since the difference is calculated using three X-ray paths or three Y-ray paths when calculating Rx and Ry, and the distance between the three optical axes is relatively close, the influence of the surface shape can be considered very small. Therefore, surface shape compensation is generally not performed when calculating Rx and Ry.

[0096] S140: Under the condition of satisfying the preset compensation update conditions, update the error compensation value of the interferometer according to the deviation between the actual position of the motion stage obtained by the visual detection system and the compensated position.

[0097] For example, it also includes: in the workflow of the error calibration device, when the system determines that the compensation update conditions (such as time trigger conditions, temperature trigger conditions, or error accumulation trigger conditions) are not met, the system will maintain the current calibration parameter state and continue to use the stored error compensation values ​​to perform the position calculation of the motion table in the global coordinate system.

[0098] For example, the preset compensation update conditions include any of the following:

[0099] (1) Time triggering condition: Whether the interferometer's working time has reached the preset cycle;

[0100] (2) Temperature triggering condition: Whether the ambient temperature fluctuation exceeds the preset threshold;

[0101] (3) Error accumulation triggering condition: whether the cumulative deviation between the motion table compensation position and the visual detection position exceeds the preset tolerance.

[0102] If any one of these three conditions is met, the system will automatically initiate the compensation update process and recalibrate the interferometer's error compensation value (x). offset y offset This design ensures measurement accuracy by enabling multi-dimensional monitoring and dynamic compensation of system errors.

[0103] Specifically, the motion stage is fixed at a certain position, and the interferometer measurement system readings are recorded. After the above deviation corrections are completed, the interferometer readings still have a systematic error that gradually accumulates over time within a certain period of time (e.g., within 10 minutes). Therefore, it is necessary to compensate for this error periodically. This application proposes three methods, Mode A to Mode C (any compensation mode can be selected), to compensate for this error:

[0104] Mode A: Acquire the zero-position signal of the grating ruler to trigger the interferometer coordinate reading reset.

[0105] Compared to interferometer measurement systems, grating ruler measurement systems are less sensitive to air refractive index and have higher anti-interference capabilities. This method uses the grating ruler measurement system to move the motion stage to zero position, and then resets the zero-position reading of the interferometer measurement system at the zero position of the grating ruler measurement system. Resetting the zero-position reading will clear the accumulated system error. The compensation accuracy of this method depends on the repeatability and accuracy of the grating ruler and motion stage returning to zero position.

[0106] Mode B: Obtain the average interferometer readings at a fixed detection position and calculate the error compensation value.

[0107] This method uses a grating ruler measurement system to move the motion stage to a fixed position, records the interferometer readings at that position over a period of time, and takes the average value (x). a ,y a ), Calculate the error compensation value:

[0108]

[0109] Where, x offset y offset x is the error compensation value for the interferometer. a-1 y a-1 This is the average interferometer reading at the same location at the previous moment. This error compensation value x will be added when subsequently acquiring the interferometer position. offset y offset The compensation accuracy of this method also depends on the repeatability and accuracy of the grating ruler and the motion table.

[0110] Mode C: Obtain the current coordinates of the fixed mark by the visual inspection system and calculate the error compensation value.

[0111] For example, the ambient temperature parameters of the interferometer are monitored in real time. When the temperature change exceeds a preset threshold, the actual coordinates of the fixed markers in the interferometer coordinate system are re-acquired through the visual detection system. The deviation between the re-acquired actual coordinates and the real-time compensation position coordinates of the current motion stage is calculated. Based on the calculated deviation value, the x-axis offset and y-axis offset in the error compensation parameters of the interferometer system are dynamically adjusted.

[0112] Specifically, this method requires installing a fixed marker pattern (referred to as a fixed marker) inside the device. During the initialization of the interferometer system, a visual inspection system is used to detect this fixed marker, and the coordinates of the current marker under the interferometer measurement system are recorded as the reference coordinates (x). b ,y b When updating the error compensation value, the visual inspection system is used again to detect the coordinates (x) of the fixed marker.c ,y c ), calculate the error compensation value x offset y offset :

[0113]

[0114] When acquiring interferometer positioning data subsequently, the system will automatically overlay x. offset y offset Error compensation value; the accuracy of this compensation method depends solely on the detection accuracy of the vision inspection system.

[0115] Please refer to Figure 5 , Figure 5 This is a flowchart illustrating an interferometer error calibration method provided in other embodiments of this application. An interferometer error calibration method includes:

[0116] S501: Calibration of interferometer surface profile parameters.

[0117] This step involves calibrating the surface parameters of the interferometer. This is done by measuring the surface profile of the mirror, acquiring relevant data, and generating the x-axis compensation value (M). x ) and y-axis compensation amount (M y The purpose is to correct the displacement error caused by the unevenness of the mirror surface, establish a nonlinear mapping relationship between the original interferometer readings and the actual physical displacement, and provide a basis for more accurate position calculations in the future.

[0118] S502: Use a vision inspection system to calibrate the non-orthogonal parameters of the xy-axis.

[0119] This step uses a vision inspection system and a marker board to calibrate the non-orthogonal parameters of the x and y axes. Specifically, a motion stage is moved to acquire images of the marker board, and then the non-orthogonal parameters (scaling factor S) are calculated through optimization. x / S y The rotation angle α is used to correct the deviation of the x and y axes caused by installation and other factors, and to eliminate the distortion that may be caused by mechanical installation in the interferometer coordinate system.

[0120] S503: Calculate the current position of the motion table using a six-degree-of-freedom model.

[0121] This step utilizes the interferometer's raw readings and the calibrated parameters (S). x / S y / α / M x / M y The calculation is performed using a six-degree-of-freedom model. First, the original readings are non-orthogonally corrected, then the compensation amount is superimposed, and finally the position of the motion stage after compensation in the global coordinate system is output, realizing real-time high-precision calculation of the position of the motion stage.

[0122] S504: Determine whether the compensation update conditions are met.

[0123] This step determines whether the compensation update conditions are met based on the three conditions mentioned above: first, whether the interferometer's working time reaches the preset period (e.g., 2 hours) for time triggering; second, whether the ambient temperature fluctuation exceeds the preset threshold (e.g., ±0.5℃) for temperature triggering; and third, whether the cumulative deviation between the motion stage compensation position and the visual detection position exceeds the preset tolerance (e.g., 500nm) for error triggering. By judging these conditions, the system error is dynamically monitored to ensure the timeliness of the compensation model.

[0124] If the compensation update conditions are met, proceed to the next step;

[0125] If the compensation update conditions are not met, return to step S503 and continue to use the stored error compensation values ​​to perform the position calculation of the motion table in the global coordinate system.

[0126] S505: Update interferometer error compensation using a visual inspection system.

[0127] When it is determined that compensation needs to be updated, this step utilizes a vision inspection system and a fixed marker pattern. First, the coordinates of the fixed markers are obtained through vision inspection. Then, based on the deviation between the actual position of the motion table obtained by the vision inspection system and the compensated position, the error compensation value (x) is calculated. offset y offset Finally, the error compensation value of the interferometer is updated. This visual feedback method can correct residual errors (such as environmental drift) and maintain the high-precision operation of the system.

[0128] In summary, this application has the following advantages: First, by simplifying the parameter calibration process (such as the measurement of the reflector surface type and the optimization algorithm for non-orthogonal coefficients), the operational complexity is significantly reduced, enabling technicians to quickly complete equipment calibration without professional training, thereby improving work efficiency and reducing human error. Second, the use of a small-size marker plate for staged calibration reduces processing costs compared to traditional large-size calibration schemes, and only requires the addition of a single marker pattern to the existing vision system of the equipment, avoiding the need to purchase additional high-precision sensors. Finally, this application is not limited to imprinting equipment; after modular design, it can be applied to the needs of different high-precision manufacturing equipment. Furthermore, for interferometers operating in different environments or conditions, calibration and compensation can quickly bring the interferometer to a stable working state.

[0129] The interferometer error calibration method described in this application is illustrated below with an example.

[0130] This application employs a systematic data acquisition and compensation analysis process for error calibration. First, 541 sets of interferometer measurement data are acquired in the X-axis direction from -270mm to 270mm with a 1mm step size. Simultaneously, 501 sets of data are acquired in the Y-axis direction from -250mm to 250mm with the same step size. After calculation using a recursive formula and smoothing, the following results are obtained: Figure 6 , 7 The compensation curve shown: Figure 6 The X-axis rotation compensation (urad) shows an upward trend followed by stabilization, while the translation compensation (nm) shows a characteristic of first decreasing and then increasing. Figure 7 The Y-axis rotation compensation (urad) shows a continuous decrease, while the translation compensation (nm) shows a trend of first decreasing and then increasing.

[0131] During the parameter calibration phase, the marker plates were fixed at the four quadrants of the motion stage (±90mm, ±90mm), corresponding to xy coordinates (-90, 90), (-90, -90), (90, -90), and (90, 90). Non-orthogonal parameters were calculated using a vision system. Specifically, the vision system detected all markers on the marker plates at the four coordinates and recorded their coordinates in the interferometer measurement coordinate system. An optimization algorithm was then used to calculate the non-orthogonal parameters. Before calibration, the x-axis and y-axis errors of the marker plates were 764nm and 621nm, respectively. After calibration, the x-axis and y-axis errors were 432nm and 336nm, respectively. Calibration significantly improved measurement accuracy: the x-axis error decreased from 764nm to 432nm (a reduction of 43.5%), and the y-axis error decreased from 621nm to 336nm (a reduction of 45.9%).

[0132] To further monitor system drift, fixed marker patterns were installed below the gantry to establish a reference coordinate system. Figure 8 The error compensation value x was recorded within 1 hour. offset y offset The variation pattern is as follows: offset x shows a stable decreasing trend, while offset y exhibits a fluctuating change that is first negative and then positive. The different variation patterns in the x and y axes indicate anisotropy in the structural stiffness / thermal expansion coefficient of the equipment. For example, temperature control needs to be strengthened in the x-axis, and vibration isolation measures need to be improved in the y-axis.

[0133] The interferometer error calibration device provided in this application is described below. The interferometer error calibration device described below can be referred to in correspondence with the interferometer error calibration method described above.

[0134] On the other hand, such as Figure 9As shown, this embodiment provides a measurement system error calibration device, including a first data processing module 901, a second data processing module 902, a position calculation module 903, and a compensation update module 904.

[0135] For example, the first data processing module 901 is configured to acquire first measurement data collected by the interferometer during the motion of the motion stage along the x-axis and y-axis, and perform compensation calculation processing based on the first measurement data to generate x-axis compensation and y-axis compensation.

[0136] For example, the second data processing module 902 is configured to acquire second measurement data of the marker plate arranged on the motion table, establish a coordinate system transformation matrix based on the second measurement data to perform parameter optimization processing, and obtain non-orthogonal parameters of the xy axis.

[0137] For example, the position calculation module 903 is configured to input the x-axis compensation amount, the y-axis compensation amount, the x-axis non-orthogonal error parameter and the y-axis non-orthogonal error parameter into a preset kinematic model to calculate the compensated position of the motion platform in the global coordinate system.

[0138] For example, the compensation update module 904 is configured to update the error compensation value of the interferometer based on the deviation between the actual position of the motion stage obtained by the visual inspection system and the compensated position, when the preset compensation update conditions are met.

[0139] Understandably, this application achieves dynamic compensation for multi-source errors through multi-technology collaboration: firstly, it utilizes a reflective mirror-type dynamic compensation technology, and then uses a first data processing module to calculate the x / y axis compensation amount (M) in real time. x / M y First, the nonlinear deviation of the interferometer caused by the error in the surface shape of the reflecting mirror is corrected. Second, a multi-position calibration method using a small-sized marker plate is adopted. The marker plate data is collected at multiple poses of the motion stage through the second data processing module to obtain data including the rotation angle α and the scaling factor S. x / S y The xy-axis non-orthogonal parameters are used to eliminate mechanical installation errors. Finally, the position calculation module inputs the surface compensation amount and the xy-axis non-orthogonal parameters into the preset kinematic model, outputting a high-precision position in the global coordinate system in real time. Combined with the actual position of the motion stage obtained by the vision inspection system, the error compensation value of the interferometer is dynamically updated. This three-level collaborative mechanism, which integrates mirror surface compensation, multi-position calibration optimization, and visual feedback correction, realizes multi-source collaborative calibration of interferometer system errors, mechanical non-orthogonal errors, and environmental drift errors, improving system accuracy by more than 40% (e.g., the x-axis error in the example above is reduced from 764nm to 432nm).

[0140] This embodiment also provides a computer-readable storage medium having a computer program stored thereon, the computer program being loaded by a processor to perform the steps of any of the methods in the above embodiments.

[0141] In the embodiments of this application, the storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc.

[0142] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0143] The foregoing has provided a detailed description of an interferometer error calibration method, apparatus, and computer-readable storage medium provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An interferometer error calibration method, characterized in that, include: Acquire the first measurement data collected by the interferometer during the motion of the motion stage along the x-axis and y-axis, and perform compensation calculation processing based on the first measurement data to generate x-axis compensation and y-axis compensation. Second measurement data of the marker plate arranged on the motion table is obtained, and a coordinate system transformation matrix is ​​established based on the second measurement data to perform parameter optimization processing to obtain the non-orthogonal parameters of the xy axis; The x-axis compensation amount, the y-axis compensation amount, the x-axis non-orthogonal error parameter, and the y-axis non-orthogonal error parameter are input into a preset kinematic model to calculate the compensated position of the motion table in the global coordinate system. Under the condition that the preset compensation update conditions are met, the error compensation value of the interferometer is updated according to the deviation between the actual position of the motion stage obtained by the visual inspection system and the compensated position.

2. The interferometer error calibration method according to claim 1, characterized in that, The compensation calculation process based on the first measurement data includes: Perform recursive calculations on the mirror surface data acquired by the interferometer to calculate the x / y axis translation compensation and rotation compensation for each measurement point; The x-axis compensation and y-axis compensation are obtained by calculating the mirror compensation at any position using a preset subspline interpolation.

3. The interferometer error calibration method according to claim 1, characterized in that, The step of establishing a coordinate system transformation matrix based on the second measurement data for parameter optimization includes: Construct an objective function that includes the x-axis scaling factor, the y-axis scaling factor, and the rotation angle; The objective function is solved using an unconstrained nonlinear optimization algorithm to obtain the xy-axis nonorthogonal parameters, which include x-axis nonorthogonal error parameters, y-axis nonorthogonal error parameters, and nonorthogonal coupling error parameters between the xy axes.

4. The interferometer error calibration method according to claim 1, characterized in that, The marking plate is a marking plate with a high-precision array pattern, and the acquisition of the second measurement data of the marking plate arranged on the motion table includes: The visual inspection system collects marking data multiple times at different coordinate positions on the motion platform; This ensures that the collected marker positions cover the working stroke of the motion table.

5. The interferometer error calibration method according to claim 4, characterized in that, The process of collecting marker data multiple times at different coordinate positions on the motion platform using a visual detection system includes: According to the preset movement path, the marker plate is moved sequentially to multiple different coordinate positions and fixed, and the movement path covers the working stroke of the motion table; For each fixed-position marker, the visual detection system moves sequentially to each marker, detects and records the marker position; Until the recorded marker position covers the working stroke of the motion table.

6. The interferometer error calibration method according to claim 1, characterized in that, The preset compensation update conditions include any one of the following: Whether the interferometer's operating time has reached the preset cycle; Does the ambient temperature fluctuation exceed the preset threshold? Does the cumulative deviation between the motion table compensation position and the visual detection position exceed the preset tolerance? 7. The interferometer error calibration method according to claim 6, characterized in that, Also includes: Real-time monitoring of the interferometer's ambient temperature parameters; when a temperature change exceeds a preset threshold: The actual coordinates of the fixed markers in the interferometer coordinate system are reacquired using a visual inspection system; The deviation between the re-acquired actual coordinates and the real-time compensated position coordinates of the current motion table is calculated. Based on the calculated deviation value, the x-axis offset and y-axis offset in the interferometer system error compensation parameters are dynamically adjusted.

8. The interferometer error calibration method according to claim 1, characterized in that, The preset kinematic model is a six-degree-of-freedom motion model, which includes: x-axis translation, y-axis translation component, z-axis translation; rotation around the x-axis, rotation around the y-axis, and rotation around the z-axis.

9. A measurement system error calibration device, characterized in that, include: The first data processing module is configured to acquire the first measurement data collected by the interferometer during the motion of the motion stage along the x-axis and y-axis, and to perform compensation calculation processing based on the first measurement data to generate x-axis compensation and y-axis compensation. The second data processing module is configured to acquire second measurement data from a marker plate arranged on the motion table, establish a coordinate system transformation matrix based on the second measurement data to perform parameter optimization processing, and obtain non-orthogonal parameters of the xy axis. The position calculation module is configured to input the x-axis compensation amount, the y-axis compensation amount, the x-axis non-orthogonal error parameter, and the y-axis non-orthogonal error parameter into a preset kinematic model to calculate the compensated position of the motion platform in the global coordinate system. The compensation update module is configured to update the error compensation value of the interferometer based on the deviation between the actual position of the motion stage obtained by the visual inspection system and the compensated position, provided that preset compensation update conditions are met.

10. A computer-readable storage medium, characterized in that, It stores a computer program, which is loaded by a processor to perform the steps in the interferometer error calibration method according to any one of claims 1-8.

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