Probe station screw pitch compensation method based on EtherCAT control system

Abstract

The invention relates to the technical field of semiconductor equipment testing, and particularly discloses a probe station screw pitch compensation method based on an EtherCAT control system, and the method comprises the steps: S1, carrying out the error measurement; s2, error modeling is carried out; s3, carrying out real-time error detection; s4, error compensation calculation; s5, position correction; s6, recording and optimizing data; s7, monitoring and feedback are carried out; the EtherCAT system supports high-speed synchronous communication, millisecond-level feedback and compensation can be achieved, accumulation of position errors is greatly reduced, the compensation value can be dynamically adjusted by combining real-time feedback data and an error model, the influence of environment changes on equipment precision can be adapted, complex error distribution is accurately described through a high-order polynomial error model, and the accuracy of the system is improved. The compensation precision can reach the submicron level, the operation state of equipment is monitored in real time, a closed-loop compensation mechanism is formed, the possible uncertainty of an open-loop system is reduced, and the adaptability of the system to error changes is improved through long-term accumulation and optimization of feedback data.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor device testing, and particularly relates to a pitch compensation method for a probe station under an EtherCAT control system. Background Art

[0002] In semiconductor testing equipment, as a key testing platform, the positioning accuracy of the probe station directly affects the accuracy and reliability of testing. The pitch error of the probe station, that is, the difference between the actual moving distance of each moving axis and the theoretically set value, is one of the main factors affecting the positioning accuracy. Most traditional pitch compensation methods for probe stations rely on manual calibration and static error models, and these methods have many deficiencies.

[0003] First of all, the compensation methods in the prior art often rely on offline measurement and calibration, and cannot reflect the actual error situation of the probe station during operation in real time. Since the probe station will be affected by various factors such as temperature fluctuations and mechanical wear during use, its error distribution will change over time. Therefore, the static error model cannot accurately describe this dynamic error change, resulting in limited compensation effect.

[0004] Secondly, the compensation accuracy of the prior art is limited. Most traditional compensation methods use low-order polynomials or simple linear models to describe the error distribution. This simplified processing cannot accurately capture complex error characteristics. Especially under high-precision testing requirements, the compensation accuracy often cannot reach the sub-micron level.

[0005] In view of this, the inventor proposes a pitch compensation method for a probe station under an EtherCAT control system to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a pitch compensation method for a probe station under an EtherCAT control system to solve the problems raised in the above background art.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A pitch compensation method for a probe station under an EtherCAT control system includes the following steps:

[0009] S1. Measure the actual pitch error of each moving axis of the probe station through a laser interferometer or a high-precision sensor to obtain error data;

[0010] S2. Generate a pitch error model by performing statistical analysis and curve fitting on the error data;

[0011] S3. During the operation of the probe station, the current positions and deviations of each axis are collected through the real-time detection module, and the deviation data is compared with the pitch error model to obtain a deviation signal;

[0012] S4. The main control module calculates the compensation value for the deviation signal and generates a correction instruction based on the pitch error model;

[0013] S5. The correction instruction is sent to the servo control module through the EtherCAT network, and the servo motor adjusts the actual position of the probe station according to the instruction to achieve position correction;

[0014] S6. Record the real-time compensation data generated during the position correction process, analyze the compensation effect, optimize the error model, and generate a new error model;

[0015] S7. During the operation, the system status is monitored in real time through sensors, the feedback data is compared with the result of the position correction, and the correction instruction is adjusted according to the feedback to obtain the compensation value of the pitch of the probe station.

[0016] Preferably, the pitch error model adopts a multi-point fitting method, and a multi-segment error compensation model is established according to different operating positions of the probe station.

[0017] Preferably, the calculation of the compensation value includes user-defined parameters such as the starting position, ending position, compensation interval, and number of compensation points.

[0018] Preferably, the modeling formula of the pitch error model is:

[0019] Δ(x) = a0 + a1x + a2x2 +... + anxn

[0020] Δ(x): Pitch error, unit is micrometer, μm;

[0021] x: Position coordinate, which is the position of the measurement point, and the value range is determined by the effective stroke of the probe station, unit is millimeter, mm;

[0022] a0, a1,..., an: Polynomial fitting coefficients, calculated based on error measurement data;

[0023] The number of an is related to the fitting order, and an appropriate order is selected according to the actual error distribution.

[0024] Preferably, the calculation formula for the position correction is:

[0025] Pnew = Pcmd + C(x)

[0026] Pnew: The corrected target position, which is the final instruction position executed by the servo module, unit is millimeter, mm;

[0027] Pcmd: The original target position, which is input by the user or generated by the control system, with the unit of millimeter, mm;

[0028] C(x): The compensation value, with the unit of micrometer, μm.

[0029] Preferably, the update formula of the new error model is:

[0030] Δ′(x) = Δ(x) + k·(Δfb(x) - Δ(x))

[0031] Δ'(x): The optimized error model;

[0032] k: The learning rate coefficient, with the value range of 0 < k ≤ 1, which controls the optimization rate. The larger the value, the faster the optimization but the less stable; the smaller the value, the more stable the optimization but the slower the speed;

[0033] Δfb(x) is the real-time feedback error, which is used to correct the model.

[0034] Preferably, the calculation formula of the compensation value of the probe table pitch is:

[0035] C(x) = -Δ(x) + Δfb(x)

[0036] Where C(x): The compensation value, with the unit of micrometer, μm;

[0037] Δ(x): The theoretical error in the error model, which comes from the error modeling formula;

[0038] Δfb(x): The real-time feedback error, which is measured by the position sensor, collected in real time, and reflects the actual position deviation.

[0039] Compared with the prior art, the beneficial effects of the present invention are:

[0040] (1) The EtherCAT system of the present invention supports high-speed synchronous communication, can achieve millisecond-level feedback and compensation, greatly reduce the accumulation of position errors, and combine real-time feedback data and error models to dynamically adjust the compensation value to adapt to the influence of environmental changes (such as temperature, mechanical wear) on the equipment accuracy.

[0041] (2) The present invention accurately describes the complex error distribution through the high-order polynomial error model, and the compensation accuracy can reach the sub-micrometer level. By monitoring the operation state of the equipment in real time, a closed-loop compensation mechanism is formed to reduce the uncertainty that may occur in the open-loop system. Through the long-term accumulation and optimization of feedback data, the adaptability of the system to error changes is improved, the service life of the equipment is extended, and the automated error modeling and compensation process significantly reduces the time for manual calibration and adjustment. Brief Description of the Drawings

[0042] Figure 1Flowchart of a pitch compensation method for a probe station based on an EtherCAT control system according to the present invention. Detailed implementation manners

[0043] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] Embodiment 1:

[0045] Please refer to Figure 1 As shown, a pitch compensation method for a probe station based on an EtherCAT control system includes the following steps:

[0046] S1. Measure the actual pitch errors of each moving axis of the probe station through a laser interferometer or a high-precision sensor to obtain error data;

[0047] S2. Generate a pitch error model by statistically analyzing and curve fitting the error data;

[0048] S3. During the operation of the probe station, collect the current positions and deviations of each axis through a real-time detection module, compare the deviation data with the pitch error model to obtain a deviation signal;

[0049] S4. Calculate the compensation value for the deviation signal through the main control module, and generate a correction instruction based on the pitch error model;

[0050] S5. Send the correction instruction to the servo control module through the EtherCAT network, and the servo motor adjusts the actual position of the probe station according to the instruction to achieve position correction;

[0051] S6. Record the real-time compensation data generated during the position correction process, analyze the compensation effect, optimize the error model, and generate a new error model;

[0052] S7. During the operation, monitor the system status in real time through a sensor, compare the feedback data with the result of the position correction to ensure the accuracy and stability of the compensation operation, and adjust the correction instruction according to the feedback to obtain the compensation value of the probe station pitch.

[0053] Specifically, the pitch error model adopts a multi-point fitting method, and a multi-segment error compensation model is established according to different operating positions of the probe station.

[0054] Specifically, the calculation of the compensation value includes user-defined parameters such as the starting position, ending position, compensation interval, and number of compensation points.

[0055] Specifically, the modeling formula of the pitch error model is:

[0056] Δ(x) = a0 + a1x + a2x2 +... + anxn

[0057] Δ(x): Pitch error, unit is micrometer, μm;

[0058] x: Position coordinate, which is the position of the measurement point, and the value range is determined by the effective travel of the probe station, unit is millimeter, mm;

[0059] a0, a1,..., an: Polynomial fitting coefficients, calculated based on error measurement data;

[0060] The number of an is related to the fitting order, and an appropriate order is selected according to the actual error distribution, such as a cubic or quintic polynomial;

[0061] By establishing the pitch error model Δ(x), the error change law of the probe station at different positions can be described, providing a theoretical basis for real-time compensation.

[0062] Specifically, the calculation formula for position correction is:

[0063] Pnew = Pcmd + C(x)

[0064] Pnew: Corrected target position, the final instruction position executed by the servo module, unit is millimeter, mm;

[0065] Pcmd: Original target position, input by the user or generated by the control system, unit is millimeter, mm;

[0066] C(x): Compensation value, unit is micrometer, μm;

[0067] By adjusting the target position, the motion error of the probe station is dynamically compensated to ensure that the positioning accuracy meets the requirements.

[0068] Specifically, the update formula for the new error model is:

[0069] Δ′(x) = Δ(x) + k·(Δfb(x) - Δ(x))

[0070] Δ'(x): Optimized error model;

[0071] k: Learning rate coefficient, value range 0 < k ≤ 1, controlling the optimization rate, the larger the value, the faster the optimization but less stable, the smaller the value, the more stable the optimization but slower;

[0072] Δfb(x) is the real-time feedback error used to correct the model;

[0073] By correcting the error model with real-time feedback data, the compensation accuracy is continuously improved to adapt to the error changes caused by the long-term operation of the equipment.

[0074] Specifically, the calculation formula for the compensation value of the probe table pitch is:

[0075] C(x) = -Δ(x) + Δfb(x)

[0076] where C(x): compensation value, unit is micrometer, μm;

[0077] Δ(x): theoretical error in the error model, derived from the error modeling formula;

[0078] Δfb(x): real-time feedback error, measured by the position sensor, collected in real time, reflecting the actual position deviation;

[0079] Calculate the compensation value C(x) in real time, and adjust the position of the probe table through the servo control module to achieve dynamic correction of the pitch error.

[0080] As can be seen from the above, the EtherCAT system in the present invention supports high-speed synchronous communication, can achieve millisecond-level feedback and compensation, greatly reduce the accumulation of position errors, and combined with real-time feedback data and the error model, can dynamically adjust the compensation value to adapt to the influence of environmental changes (such as temperature, mechanical wear) on the equipment accuracy.

[0081] Through the high-order polynomial error model, the complex error distribution can be accurately described, and the compensation accuracy can reach the sub-micrometer level. By real-time monitoring the operation state of the equipment, a closed-loop compensation mechanism is formed to reduce the uncertainty that may occur in the open-loop system. Through the long-term accumulation and optimization of feedback data, the adaptability of the system to error changes is improved, the service life of the equipment is extended, and the automated error modeling and compensation process significantly reduces the time for manual calibration and adjustment.

[0082] Embodiment 2:

[0083] Application of High-Precision Pitch Error Compensation in Semiconductor Testing

[0084] Background Description

[0085] A certain semiconductor probe table is used for chip testing, and the minimum distance between test points is 50μm. The installation accuracy of the guide rail and lead screw of the probe table is 0.01mm, and there is a cumulative pitch error, resulting in the probe being unable to accurately align with the test points and affecting the test results.

[0086] Experimental Steps and Parameters

[0087] Error Measurement

[0088] The pitch error of the probe station's X-axis is measured using a laser interferometer, with measurements taken every 10 mm over a total travel of 200 mm.

[0089] Measurement data: Error point position (mm): {0, 10, 20, …, 200}

[0090] Error values (μm): {0, -5, -10, -15, …, -100}

[0091] Error modeling

[0092] Fitted using a cubic polynomial: Δ(x) = -0.025x^2 + 0.1x - 5

[0093] Parameters: Fitting coefficients a0 = -5, a1 = 0.1, a2 = -0.025

[0094] Real-time error detection

[0095] Real-time position sampling frequency: 100 Hz.

[0096] Detect the current deviation Δfb(x) through a position sensor.

[0097] Error compensation calculation

[0098] Deviation feedback example: Current position x = 50 mm, feedback error Δfb(50) = -6 μm

[0099] Calculate the compensation value: C(50) = -Δ(50) + Δfb(50) = 25 - 6 = 19 μm

[0100] Position correction

[0101] Corrected target position: Pnew = Pcmd + C(50) = 50.019 mm

[0102] Data recording and optimization

[0103] Record the compensation values and actual effects, and optimize the model:

[0104] Δ'(x) = Δ(x) + 0.1·(Δfb(x) - Δ(x))

[0105] Effect analysis

[0106] Maximum error without compensation: -100 μm.

[0107] Maximum residual error after compensation: ±2 μm.

[0108] Positioning accuracy is improved by approximately 98%.

[0109] Example 3:

[0110] Application of Dynamic Compensation in Precision Machining

[0111] Background Description

[0112] When a certain precision machining equipment processes micron-level parts, the pitch error fluctuates due to environmental temperature changes, affecting the machining quality. The stroke range is 300 mm, and the target accuracy is ±3 μm.

[0113] Experimental Steps and Parameters

[0114] Error Measurement

[0115] Use a high-precision displacement sensor to measure the actual position of the machining head, measure once every 5 mm, and the total stroke is 300 mm.

[0116] Measurement data: Error point position (mm): {0, 5, 10, …, 300} Error value (μm): {0, -3, -6, -9, …, -90}

[0117] Error Modeling

[0118] Use a fifth-degree polynomial fitting: Δ(x) = -0.001x 3 +0.015x 2 -0.2x - 3

[0119] Real-time Error Detection and Compensation Calculation

[0120] Current position x = 150 mm, feedback error Δfb(150) = -85 μm

[0121] Calculate the compensation value: C(150) = -Δ(150) + Δfb(150) = 75 - 85 = -10 μm

[0122] Position Correction

[0123] Corrected target position: Pnew = Pcmd + C(150) = 150.01 mm

[0124] Monitoring and Feedback

[0125] During the operation of the system, record the temperature and error data in real time, discover the influence of temperature changes on the error, and dynamically adjust the compensation model.

[0126] Effect Analysis

[0127] Maximum error without compensation: -90 μm

[0128] Maximum residual error after compensation: ±3 μm

[0129] The system adapts to temperature changes, dynamically adjusts the compensation, and improves the machining consistency.

[0130] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0131] In the drawings of the disclosed embodiments of the present invention, only the structures related to the disclosed embodiments are involved. Other structures can refer to the general design. Without conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0132] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A probe station pitch compensation method based on EtherCAT control system, characterized in that: It includes the following steps: S1. Measure the actual pitch error of each moving axis of the probe station through a laser interferometer or a high-precision sensor to obtain error data; S2. Generate a pitch error model by performing statistical analysis and curve fitting on the error data; S3. During the operation of the probe station, collect the current position and deviation of each axis through a real-time detection module, compare the deviation data with the pitch error model to obtain a deviation signal; S4. Calculate the compensation value for the deviation signal through the main control module, and generate a correction instruction based on the pitch error model; S5. Send the correction instruction to the servo control module through the EtherCAT network, and the servo motor adjusts the actual position of the probe station according to the instruction to achieve position correction; S6. Record the real-time compensation data generated during the position correction process, analyze the compensation effect, optimize the error model, and generate a new error model; S7. During the operation, monitor the system status in real time through a sensor, compare the feedback data with the result of the position correction, and adjust the correction instruction according to the feedback to obtain the compensation value of the probe station pitch.

2. According to a probe station pitch compensation method based on EtherCAT control system according to claim 1, it is characterized in that, The pitch error model adopts a multi-point fitting method to establish a multi-segment error compensation model according to different operating positions of the probe station.

3. The probe station pitch compensation method based on the EtherCAT control system according to claim 1, characterized in that: The calculation of the compensation value includes user-defined parameters such as the starting position, ending position, compensation interval, and number of compensation points.

4. The probe station pitch compensation method based on the EtherCAT control system according to claim 1, characterized in that: The modeling formula of the pitch error model is: Δ(x) = a0 + a1x + a2x2 +... + anxn Δ(x): Pitch error, unit is micrometer, μm; x: Position coordinate, which is the position of the measurement point, and the value range is determined by the effective stroke of the probe station, unit is millimeter, mm; a0, a1,..., an: Polynomial fitting coefficients, calculated based on the error measurement data; The number of an is related to the fitting order, and an appropriate order is selected according to the actual error distribution.

5. The probe station pitch compensation method based on EtherCAT control system according to claim 1, characterized in that: The calculation formula for the position correction is: Pnew = Pcmd + C(x) Pnew: The corrected target position, which is the final instruction position executed by the servo module, unit is millimeter, mm; Pcmd: The original target position, input by the user or generated by the control system, unit is millimeter, mm; C(x): Compensation value, unit is micrometer, μm.

6. The probe station pitch compensation method based on the EtherCAT control system according to claim 1, characterized in that: The update formula for the new error model is: Δ′(x) = Δ(x) + k·(Δfb(x) - Δ(x)) Δ'(x): Optimized error model; k: Learning rate coefficient, the value range is 0 < k ≤ 1, which controls the optimization rate. The larger the value, the faster the optimization but the less stable. The smaller the value, the more stable the optimization but the slower the speed; Δfb(x) is the real-time feedback error for correcting the model.

7. The probe station pitch compensation method based on the EtherCAT control system according to claim 1, characterized in that: The calculation formula for the compensation value of the probe station pitch is: C(x) = -Δ(x) + Δfb(x) where C(x): Compensation value, unit is micrometer, μm; Δ(x): Theoretical error in the error model, derived from the error modeling formula; Δfb(x): Real-time feedback error, measured by the position sensor, collected in real time, and reflects the actual position deviation.

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