Master-slave motor system, synchronous control method, ellipsometer system and storage medium

Abstract

The invention provides a master-slave motor system, a Mueller matrix ellipsometer system, a master-slave motor synchronous control method and a storage medium. The master-slave motor system comprises a master motor, a slave motor, a phase compensation module and a second current loop control module. And the main motor rotates according to a preset target angle. And the slave motor and the master motor keep rotating synchronously. The phase compensation module determines a phase compensation current according to a derivative of a phase difference between the first rotation angle of the master motor and the second rotation angle of the slave motor. And the second current loop control module determines a second driving current for controlling the synchronous rotation of the slave motor and the main motor at least according to a second actual current flowing through the slave motor and the phase compensation current. According to the invention, high-precision synchronous rotation of the master motor and the slave motor in a double-rotation compensator structure can be ensured in a multi-frequency and multi-dynamic complex scene, so that the high-precision optical measurement requirement is met.

Description

Technical Field

[0001] The present invention relates to the field of optical measurement, and in particular, to a master-slave motor system, a Mueller matrix ellipsometer system, a synchronous control method for a master-slave motor, and a computer-readable storage medium. Background Art

[0002] A Mueller matrix ellipsometer is a high-precision optical measurement device, which has wide applications in the fields of semiconductors, optical thin films, and material characterization. It can provide comprehensive optical parameter information by analyzing the response of a detected sample to fully polarized light. The dual-rotating compensator structure is the core component of a Mueller matrix ellipsometer, which consists of two independently rotating compensators and optical elements. The existing technical solutions for implementing a dual-rotating compensator are mainly divided into two types: independent closed-loop control and simple synchronous control. Among them, the technical solution of independent closed-loop control uses independent PID control loops for the two compensator motors respectively. However, the coordination between the two motors in this solution is poor, and phase deviation is likely to occur, especially more obvious at high speeds. In addition, in the technical solution of simple synchronous control, through a master-slave control architecture, one motor is used as a reference signal source, and the other motor follows its speed and position. However, the communication delay and response lag between the master motor and the slave motor may lead to insufficient synchronization accuracy and cannot meet the requirements of high-precision measurement.

[0003] In order to overcome the above-mentioned defects existing in the prior art, there is an urgent need in the art for an improved master-slave motor system to ensure that the master-slave motors in the dual-rotating compensator structure can achieve high-precision synchronous rotation in complex scenarios with multiple frequencies and multiple dynamics, so as to meet the requirements of high-precision optical measurement. Summary of the Invention

[0004] The following gives a brief overview of one or more aspects to provide a basic understanding of these aspects. This overview is not an exhaustive survey of all contemplated aspects, and is neither intended to identify key or decisive elements of all aspects nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description to follow.

[0005] In order to overcome the above-mentioned defects existing in the prior art, the present invention provides a master-slave motor system, a Mueller matrix ellipsometer system, a synchronous control method for a master-slave motor, and a computer-readable storage medium, which can be used to ensure that the master-slave motors in the dual-rotating compensator structure can achieve high-precision synchronous rotation in complex scenarios with multiple frequencies and multiple dynamics, so as to meet the requirements of high-precision optical measurement by combining the technologies of dynamic compensation and real-time phase adjustment.

[0006] Specifically, the above master-slave motor system provided according to the first aspect of the present invention includes a master motor, a slave motor, a phase compensation module, and a second current loop control module. The master motor rotates according to a preset target angle. The slave motor rotates synchronously with the master motor. The phase compensation module determines a phase compensation current according to the derivative of the phase difference between the first rotation angle of the master motor and the second rotation angle of the slave motor. The second current loop control module determines a second drive current for controlling the slave motor to rotate synchronously with the master motor at least according to the second actual current flowing through the slave motor and the phase compensation current.

[0007] Further, in some embodiments of the present invention, the master-slave motor system further includes a first position loop control module, a first speed loop control module, and a first current loop control module. The first position loop control module determines a first target speed according to the difference between the target angle and the first rotation angle. The first speed loop control module determines a first target current according to the difference between the first target speed and the first actual speed of the master motor. The first current loop control module determines a first drive current for controlling the rotation of the master motor according to the difference between the first target current and the first actual current flowing through the master motor.

[0008] Further, in some embodiments of the present invention, the first position loop control module performs PID control according to the difference between the target angle and the first rotation angle to determine the first target speed. The first speed loop control module performs PI control according to the difference between the first target speed and the first actual speed to determine the first target current. The first current loop control module performs PI control according to the difference between the first target current and the first actual current to determine the first drive current.

[0009] Further, in some embodiments of the present invention, the master-slave motor system further includes a second position loop control module and a second speed loop control module. The second position loop control module determines a second target speed according to the first rotation angle, the second rotation angle, and the speed ratio between the master motor and the slave motor. The second speed loop control module determines a second target current according to the difference between the second target speed and the second actual speed of the slave motor. The second current loop control module determines the second drive current according to the second target current, the second actual current, and the phase compensation current.

[0010] Further, in some embodiments of the present invention, the second position loop control module performs PID control according to the first rotation angle, the second rotation angle, and the speed ratio between the main motor and the slave motor to determine the second target speed. The second speed loop control module performs PI control according to the difference between the second target speed and the second actual speed of the slave motor to determine the second target current. The second current loop control module performs PI control according to the second target current, the second actual current, and the phase compensation current to determine the second drive current.

[0011] Further, in some embodiments of the present invention, the master-slave motor system further includes a model predictive control module and the second speed loop control module. The model predictive control module is configured to predict the first predicted speed of the main motor at the next moment according to the first rotation angle and the first actual speed of the main motor at the current moment. The second speed loop control module is configured to determine the second target current according to the first predicted speed, the second actual speed of the slave motor, and the speed ratio between the main motor and the slave motor. The second current loop control module determines the second drive current according to the second target current, the second actual current, and the phase compensation current.

[0012] Further, in some embodiments of the present invention, the master-slave motor system further includes a model predictive control module, which is configured to perform rolling optimization according to the first actual speed ω of the main motor at the current moment 1 , the second actual speed ω of the slave motor at the current moment 2 , and the speed ratio between the main motor and the slave motor to determine the speed loop control quantity u that minimizes the objective function. The objective function is expressed as J=(ω 1 ×m - ω 2 ) 2 +μΔu 2 , where m is the speed ratio between the main motor and the slave motor, and μ is the weight of the speed loop control quantity u. The second current loop control module determines the second target current of the slave motor at the next moment according to the speed loop control quantity u, and combines the second actual current and the phase compensation current of the slave motor at the current moment to determine the second drive current.

[0013] Further, in some embodiments of the present invention, the master-slave motor system further includes a controller, which is configured to: obtain a phase difference between a first rotation angle of the master motor and a second rotation angle of the slave motor via the phase compensation module; in response to the phase difference being greater than a preset error threshold, determine a control period for rolling optimization of a speed loop control quantity u of a model predictive control module of the master-slave motor system according to a current computing power state; in response to the control period being less than a preset period upper limit, determine a second drive current via the second current loop control module according to the speed loop control quantity u output by the model predictive control module; and in response to the control period being greater than or equal to the period upper limit, predict a first predicted rotational speed of the master motor at the next moment via the model predictive control module, determine a second target current according to the first predicted rotational speed via a second speed loop control module of the slave motor, and then determine the second drive current according to the second target current via the second current loop control module.

[0014] Further, in some embodiments of the present invention, the controller is further configured to: in response to a speed switching instruction, determine an acceleration curve of the master motor according to first target rotational speeds before and after switching; perform weighted summation on the first target rotational speed at the next moment indicated by the acceleration curve and the first predicted rotational speed at the next moment output by the model predictive control module according to a preset weighting coefficient; and input a result of the weighted summation into a second speed loop control module of the slave motor to determine a corresponding second target current in combination with a second actual rotational speed of the slave motor at the current moment, and then determine a second drive current at the next moment via the second current loop control module according to the second target current, and a second actual current and a phase compensation current at the current moment.

[0015] In addition, the above-mentioned Mueller matrix ellipsometer system provided according to the second aspect of the present invention includes a light source, a polarizer, a first compensator, a second compensator, an analyzer, a master-slave motor system as provided in the first aspect of the present invention, and a detector. The light source is used to provide a detection beam for the semiconductor device. The polarizer is located at the rear end of the light source to adjust the detection beam into a first linearly polarized light. The first compensator is located at the rear end of the polarizer and is used to perform a first compensation based on the first Mueller matrix on the first linearly polarized light, and transmit the first linearly polarized light after the first compensation to the detection area on the surface of the sample to be measured. The second compensator is located at the rear end of the detection sample and is used to collect the reflected light output by the detection sample and perform a second compensation of the second Mueller matrix adapted to the first Mueller matrix on it. The analyzer is located at the rear end of the second compensator and is used to adapt the polarization of the reflected light after the second compensation to the polarization of the polarizer to obtain a corresponding second linearly polarized light. The master-slave motor system is used to drive the first compensator and the second compensator to rotate synchronously. The detector is located at the rear end of the analyzer and is used to collect the second linearly polarized light to characterize the device parameters of the detection area.

[0016] In addition, the above-mentioned synchronous control method of the master-slave motor provided according to the third aspect of the present invention includes the following steps: controlling the main motor to rotate according to a preset target angle; determining a phase compensation current according to the derivative of the phase difference between the first rotation angle of the main motor and the second rotation angle of the slave motor; determining a second drive current at least according to the second actual current flowing through the slave motor and the phase compensation current; and providing the second drive current to the slave motor to control it to rotate synchronously with the main motor.

[0017] In addition, the above-mentioned computer-readable storage medium provided according to the fourth aspect of the present invention stores computer instructions. When the computer instructions are executed by a processor, the synchronous control method of the master-slave motor as provided in the third aspect of the present invention is implemented. Description of the Drawings

[0018] After reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings, the above features and advantages of the present invention can be better understood. In the drawings, the components are not necessarily drawn to scale, and components with similar relevant characteristics or features may have the same or similar reference numerals.

[0019] Figure 1 The structural schematic diagram of the Mueller matrix ellipsometer system provided according to some embodiments of the present invention is shown.

[0020] Figure 2 The flowchart of the synchronous control method of the master-slave motor provided according to some embodiments of the present invention is shown.

[0021] Figure 3 Shows a schematic diagram of the rotation principle of the main motor provided according to some embodiments of the present invention.

[0022] Figure 4 Shows a schematic diagram of the rotation principle of the slave motor provided according to a reference example.

[0023] Figure 5 Shows a schematic diagram of the rotation principle of the slave motor provided according to some embodiments of the present invention.

[0024] Figure 6 Shows a schematic diagram of the rotation principle of the slave motor under the condition of limited computing power provided according to some embodiments of the present invention.

[0025] Figure 7 Shows a schematic diagram of the rotation principle of the slave motor under the condition of sufficient computing power provided according to some embodiments of the present invention.

[0026] Figure 8 Shows a schematic diagram of the acceleration curve provided according to some embodiments of the present invention. Detailed implementation manners

[0027] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention will be introduced in conjunction with preferred embodiments, this does not mean that the features of this invention are limited to this implementation manner. On the contrary, the purpose of introducing the invention in conjunction with the implementation manner is to cover other alternatives or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, many specific details will be included in the following description. The present invention can also be implemented without using these details. In addition, in order to avoid confusing or obscuring the key points of the present invention, some specific details will be omitted in the description.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0029] In addition, the "upper", "lower", "left", "right", "top", "bottom", "horizontal", and "vertical" used in the following description should be understood as the orientations shown in this section and the relevant drawings. Such relative terms are only for convenience of description and do not represent that the devices described need to be manufactured or operated in a specific orientation, so they should not be construed as a limitation on the present invention.

[0030] It can be understood that although terms such as "first", "second", "third", etc. can be used herein to describe various components, regions, layers, and / or parts, these components, regions, layers, and / or parts should not be limited by these terms, and these terms are only used to distinguish different components, regions, layers, and / or parts. Therefore, the first component, region, layer, and / or part discussed below can be referred to as the second component, region, layer, and / or part without departing from some embodiments of the present invention.

[0031] As described above, the existing technical solutions for implementing a dual-rotation compensator are mainly divided into two types: independent closed-loop control and simple synchronous control. Among them, the technical solution of independent closed-loop control adopts independent PID control loops for two compensator motors respectively. However, the coordination between the two motors in this solution is poor, and phase deviation is likely to occur, especially more obvious at high speeds. In addition, in the technical solution of simple synchronous control, through a master-slave control architecture, one motor is used as a reference signal source, and the other motor follows its speed and position. However, the communication delay and response lag between the master motor and the slave motor may lead to insufficient synchronization accuracy and cannot meet the high-precision measurement requirements.

[0032] In order to overcome the above-mentioned defects existing in the prior art, the present invention provides a master-slave motor system, a Mueller matrix ellipsometer system, a synchronous control method for a master-slave motor, and a computer-readable storage medium, which can be used to ensure high-precision synchronous rotation of the master-slave motors in a dual-rotation compensator structure in complex scenarios with multiple frequencies and multiple dynamics by combining dynamic compensation and real-time phase adjustment techniques, so as to meet the high-precision optical measurement requirements.

[0033] In some non-limiting embodiments, the above-mentioned master-slave motor system provided by the first aspect of the present invention can be configured in the above-mentioned Mueller matrix ellipsometer system provided by the second aspect of the present invention for implementation.

[0034] Specifically, please refer to Figure 1 。 Figure 1 Fig. shows a schematic structural diagram of a Mueller matrix ellipsometer system provided according to some embodiments of the present invention.

[0035] In Figure 1In the illustrated embodiment, the Mueller matrix ellipsometer system provided by the second aspect of the present invention includes a light source 11, a polarizer 12, a first compensator 13, a second compensator 14, an analyzer 15, the master-slave motor system (not shown) provided by the first aspect of the present invention, and a detector 16. Here, the light source 11 is used to provide a detection beam for semiconductor devices. The polarizer 12 is located at the rear end of the light source to adjust the detection beam into a first linearly polarized light. The first compensator 13 is located at the rear end of the polarizer 12 and is used to perform a first compensation on the first linearly polarized light based on a first Mueller matrix, and transmit the first linearly polarized light after the first compensation to the detection area on the surface of the detection sample 17. The second compensator 14 is located at the rear end of the detection sample 17 and is used to collect the reflected light output by the detection sample 17 and perform a second compensation of a second Mueller matrix adapted to the first Mueller matrix on it. The analyzer 15 is located at the rear end of the second compensator 14 and is used to polarize the reflected light after the second compensation to match the polarizer 12 to obtain a corresponding second linearly polarized light. The master-slave motor system is used to drive the first compensator 13 and the second compensator 14 to rotate synchronously. The detector 16 is located at the rear end of the analyzer 15 and is used to collect the second linearly polarized light to characterize the device parameters of the detection area.

[0036] During the process of detecting the detection sample 17, a technician can first determine the first Mueller matrix and the second Mueller matrix for compensating the amplitude change and / or phase change of the first linearly polarized light in the correction stage. Then, the Mueller matrix ellipsometer system can input polarized light to the detection sample via the light source 11 and the polarizer 12, and obtain the first measured spectral information of the reflected light output by the detection sample 17. Then, the Mueller matrix ellipsometer system can determine the first simulated spectral information of the second linearly polarized light after compensation according to the ellipsometry parameters of the standard sample, the system parameters of the Mueller matrix ellipsometer system, the first compensation parameters in the first Mueller matrix indicating the ellipsometry system error, and the second compensation parameters in the second Mueller matrix indicating the detector error. Then, the technician can fit the first measured spectral information and the first simulated spectral information to determine the device parameters of the detection area on the surface of the detection sample.

[0037] Specifically, for the specific solutions of determining the first Mueller matrix and the second Mueller matrix for compensating the amplitude change and / or phase change of the first linearly polarized light, and fitting the first measured spectral information and the first simulated spectral information to determine the parameters of the detection sample, reference can be made to the prior patent with the patent number 202310324470.2, which will not be elaborated here.

[0038] Furthermore, the master-slave motor system provided by the first aspect of the present invention includes a master motor, a slave motor, a phase compensation module, and a second current loop control module. Here, the master motor rotates according to a preset target angle θ refThe slave motor rotates in synchronization with the master motor. The phase compensation module is configured to determine a phase compensation current based on the derivative of the phase difference between the first rotation angle of the master motor and the second rotation angle of the slave motor. The second current loop control module is configured to determine a second drive current for controlling the slave motor to rotate in synchronization with the master motor based at least on the second actual current flowing through the slave motor and the phase compensation current.

[0039] In addition, in some non-limiting embodiments, the master-slave motor system provided by the first aspect of the present invention includes a memory and a controller. Herein, the memory includes, but is not limited to, the computer-readable storage medium provided by the foregoing fourth aspect, on which computer instructions are stored. The controller is connected to the memory and is configured to execute the computer instructions stored on the memory to implement the synchronous control method of the master-slave motor provided by the third aspect of the present invention.

[0040] The working principle of the above master-slave motor system will be described below in conjunction with some embodiments of the synchronous control method of the master-slave motor. Those skilled in the art can understand that these embodiments of the synchronous control method are only some non-limiting implementation manners provided by the present invention, aiming to clearly show the main concept of the present invention and provide some specific solutions convenient for the public to implement, rather than limiting all functions or all working modes of the master-slave motor system. Similarly, the master-slave motor system is also a non-limiting implementation manner provided by the present invention, and does not limit the execution subject and execution order of each step in these synchronous control methods of the master-slave motor.

[0041] Specifically, please refer to Figure 2 and Figure 3 . Figure 2 FIG. shows a schematic flowchart of a synchronous control method of a master-slave motor provided by some embodiments of the present invention. Figure 3 FIG. shows a schematic diagram of the principle of the rotation of the master motor provided by some embodiments of the present invention.

[0042] As Figure 2 and Figure 3 shown, the master-slave motor system can first control the master motor to rotate according to a preset target angle θ ref . Specifically, the above master motor 20 may include a first position loop control module 21, a first speed loop control module 22, and a first current loop control module 23.

[0043] The first position loop control module 21 may determine a first target rotational speed ω ref based on the difference between the target angle θ 1 and the first rotation angle θ 1 * . Specifically, the first position loop control module 21 may first determine based on the target angle θ ref and the first rotation angle θ1 Perform PID control on the difference to determine the first target angle θ 1 * Then, take the derivative of it to determine the first target rotational speed ω 1 * :

[0044]

[0045] Here, introducing a differential term in the first position loop control module 21 can suppress the sudden change of the position error and improve the fast response ability of the system. At the same time, the differential term can apply corrections in advance to improve the control effect. Therefore, perform PID control with the introduction of a differential term on the first position loop control module 21 to enhance the real-time performance and accuracy of the control.

[0046] After that, as Figure 3 shown, the first speed loop control module 22 can determine the first target current i 1 * based on the difference between the first target rotational speed ω 1 and the first actual rotational speed ω 1 * of the main motor 20. Specifically, the first speed loop control module 22 can first perform PI control based on the difference between the first target rotational speed ω 1 * and the first actual rotational speed ω 1 to determine the first target torque T 1 * , and then combine with the motor torque constant k t1 of the main motor 20 to determine the first target current i 1 * :

[0047]

[0048] Here, since the motor itself has an inertial characteristic and can naturally filter out high-frequency disturbances, no additional differential term is required. And since the speed feedback signal of the first speed loop control module 22 usually comes from an encoder and there will be noise in the signal, the differential term will amplify this noise, resulting in unstable control. Therefore, only perform PI control on the first speed loop control module 22 to enhance the stability of the control while maintaining the control accuracy.

[0049] After that again, as Figure 3 shown, the first current loop control module 23 can determine the first drive current U for controlling the rotation of the main motor 20 1 * based on the difference between the first target current i 1 and the first actual current i 1. Specifically, the first current loop control module 23 can determine the first drive current U according to the difference between the first target current i 1 * and the first actual current i 1 through PI control: 1 :

[0050]

[0051] Here, since the response speed of the first current loop control module 23 is faster than that of the first speed loop control module 22 and the first position loop control module 21, and the dynamic requirements are high, the differential term is likely to introduce noise and affect stability. In addition, due to the inductance characteristics of the motor windings, the current loop itself has a certain filtering effect, the integral term can provide steady-state accuracy, while the differential term has little significance. Moreover, only using PI control has a small computational load and can meet the requirements of high-frequency modulation such as above 10 kHz. Introducing the differential term has a large computational load and is not suitable for high-speed control. Therefore, only PI control is performed on the first current loop control module 23 to improve the stability and real-time performance of the control while maintaining the control accuracy.

[0052] In this way, the master-slave motor system provided in the first aspect of the present invention can provide the first drive current U to the main motor 20 based on independent PID closed-loop control 1 to control the main motor 20 to rotate according to the preset target angle θ ref .

[0053] Please refer to Figure 4 , Figure 4 which shows a schematic diagram of the rotation principle of the slave motor provided according to a reference example.

[0054] In Figure 4 the illustrated embodiment, the slave motor 30 includes a second position loop control module 31, a second speed loop control module 32, and a second current loop control module 33.

[0055] The second position loop control module 31 can determine the second target speed ω according to the first rotation angle θ 1 , the second rotation angle θ 2 , and the speed ratio m between the main motor 20 and the slave motor 30. Specifically, the second position loop control module 31 can first perform PID control according to the first rotation angle θ 2 * , the second rotation angle θ 1 , and the speed ratio m between the main motor 20 and the slave motor 30 to determine the second target angle θ 2 , and then take the derivative of it to determine the second target speed ω 2 * , 2* :

[0056]

[0057] After that, the second speed loop control module 32 can determine the second target current i according to the difference between the second target rotational speed ω 2 * and the second actual rotational speed ω of the slave motor 30 2 . Specifically, the second speed loop control module 32 can first perform PI control according to the difference between the second target rotational speed ω 2 * and the second actual rotational speed ω of the slave motor 30 to determine the second target torque T 2 * , and then combine with the motor torque constant k of the slave motor 30 2 to determine the second target current i 2 * : t2 2 * 2 :

[0058]

[0059] After that, as shown in Figure 4 , the second current loop control module 33 can determine the second drive current U according to the second target current i * 2 and the second actual current i 2 . Specifically, the second current loop control module 33 can perform PI control according to the second target current i 2 * and the second actual current i 2 to determine the second drive current U 2 : 1 :

[0060]

[0061] In this way, the existing master-slave motor system uses the first rotation angle of the master motor 20 as a reference signal source through the master-slave control architecture, and the slave motor 30 follows its rotational speed and position. However, the communication delay and response lag between the master motor 20 and the slave motor 30 may lead to insufficient synchronization accuracy and cannot meet the high-precision measurement requirements.

[0062] Furthermore, in some embodiments, the master-slave motor system provided in the first aspect of the present invention can also determine according to the first rotation angle θ of the master motor 20 1 and the second rotation angle θ of the slave motor 30 2Derivative of the phase difference therebetween to determine the phase compensation current, and based on the phase compensation current, determine the second drive current U for driving the slave motor 30 to rotate synchronously with the main motor 20 2 。

[0063] For details, please refer to Figure 5 , Figure 5 which shows a schematic diagram of the rotation principle of the slave motor provided according to some embodiments of the present invention.

[0064] In Figure 5 the illustrated embodiment, the slave motor 40 may include a second position loop control module 41, a second speed loop control module 42, a phase compensation module 43, and a second current loop control module 44.

[0065] The second position loop control module 41 may determine the second target speed ω 1 、second rotation angle θ 2 , and the speed ratio m between the main motor 20 and the slave motor 40. Specifically, the second position loop control module 41 may first perform PID control based on the first rotation angle θ 2 * 、second rotation angle θ 1 、second rotation angle θ 2 , and the speed ratio m between the main motor 20 and the slave motor 40 to determine the second target angle θ 2 * , and then take the derivative thereof to determine the second target speed ω 2 * :

[0066]

[0067]

[0068] After that, the second speed loop control module 42 may determine the second target current i 2 * based on the difference between the second target speed ω 2 and the second actual speed ω 2 * of the slave motor 40. Specifically, the second speed loop control module 42 may first perform PI control based on the difference between the second target speed ω 2 * and the second actual speed ω 2 of the slave motor 40 to determine the second target torque T 2 * , and then combine with the motor torque constant k t2 of the slave motor 30 to determine the second target current i 2 * :

[0069]

[0070] After that, the phase compensation module 43 can determine the phase compensation current according to the derivative of the phase difference between the first rotation angle θ of the main motor 20 1 and the second rotation angle θ of the slave motor 40 2 Specifically, the phase compensation module 43 can first determine the phase difference Δφ between the first rotation angle θ of the main motor 20 1 and the second rotation angle θ of the slave motor 40 2 :

[0071] Δφ = θ 1 *m - θ 2

[0072] Then, according to the derivative Δω of the phase difference Δφ, determine the target torque ΔT for phase compensation ω :

[0073]

[0074] ΔT ω = K p,φ Δω + K i,φ ∫Δωdt

[0075] Then, in combination with the motor torque constant k of the slave motor 30 t2 to determine the phase compensation current Δi ω :

[0076]

[0077] where m is the speed ratio between the main motor 20 and the slave motor 40.

[0078] After that, the second current loop control module 44 can determine the second drive current U for controlling the synchronous rotation of the slave motor 40 and the main motor 20 according to the above-mentioned second target current i 2 * , the second actual current i 2 and the phase compensation current Δi ω . Specifically, the second current loop control module 42 can perform PI control according to the second target current i 2 , the second actual current i 2 * , the second actual current i 2 and the phase compensation current Δi ω to determine the second drive current U 2 :

[0079]

[0080] After that, the master-slave motor system can supply the second drive current to the slave motor according to the second drive current determined above to control its synchronous rotation with the master motor.

[0081] In this way, the master-slave motor system provided by the first aspect of the present invention can directly add the output of the phase synchronization control to the output of the second speed loop control module 44 based on the dynamic phase closed-loop adjustment, tightly couple the phase synchronization control with the speed control, avoid additional control levels, simplify the control strategy, and thus improve the system response speed and control accuracy.

[0082] In addition, in some embodiments of the present invention, the master-slave motor system provided by the first aspect of the present invention may preferably further include a Model Predict Control (MPC) module, which is used in the normal measurement scenario of the Mueller matrix ellipsometer system. According to the first rotation angle θ of the master motor at the current moment 1 and the first actual rotational speed ω 1 , predict its first predicted rotational speed at the next moment to correct possible speed or position deviations in advance, and according to the first actual rotational speed ω of the master motor at the current moment 1 , and the second actual rotational speed ω of the slave motor at the current moment 2 , perform rolling optimization to determine the second drive current U for controlling the synchronous rotation of the slave motor and the master motor 2 .

[0083] For details, please refer to Figure 6 and Figure 7 . Figure 6 FIG. shows a schematic diagram of the rotation principle of the slave motor in the case of limited computing power according to some embodiments of the present invention. Figure 7 FIG. shows a schematic diagram of the rotation principle of the slave motor in the case of sufficient computing power according to some embodiments of the present invention.

[0084] In Figure 6 and Figure 7 shown in the embodiments, in the process of determining the second drive current U 2 , the master-slave motor system can first pass through the phase compensation module 53 to determine the phase difference Δφ between the first rotation angle θ 1 of the master motor 20, the second rotation angle θ 2 of the slave motor 50, and the speed ratio m between the master motor and the slave motor: 1 and the second rotation angle θ 2 :

[0085] Δφ = θ 1 *m - θ 2

[0086] In some embodiments, in response to the phase difference Δφ being greater than a preset error threshold, the master-slave motor system may determine, according to the current computing power state, the control period T for the rolling optimization of the speed-loop control quantity u by the model predictive control module 51 of the master-slave motor system. MPC .

[0087] After that, in response to the control period T MPC being greater than or equal to a preset period upper limit T s , the master-slave motor system may determine that the current computing power is insufficient, and thus predict, via the model predictive control module 51, the first predicted rotational speed of the main motor at the next moment (e.g., at the k + 1 moment), and determine the second target current i via the second speed-loop control module 53 of the slave motor 50 according to the first predicted rotational speed 2 * , and then determine the second drive current U via the second current-loop control module 54 according to the second target current i 2 * . 2 .

[0088] In Figure 6 the embodiment shown, the above master-slave motor system includes a model predictive control module 51, a phase compensation module 52, a second speed-loop control module 53, and a second current-loop control module 54.

[0089] The model predictive control module 51 may predict the first predicted rotational speed ω of the main motor at the next moment (e.g., at the k + 1 moment) according to the first rotational angle and the first actual rotational speed of the main motor 20 at the current moment (e.g., at the k moment). 1p .

[0090] Specifically, in the process of predicting the first predicted rotational speed ω 1p , the master-slave motor system may discretize based on the system model to respectively obtain the state-space equations of the main motor at the current moment (e.g., at the k moment) and the next moment (e.g., at the k + 1 moment):

[0091]

[0092] Here, ω 1 (k) is the first actual rotational speed of the main motor at the current moment k, ω 1 (k + 1) is the first actual rotational speed of the main motor at the next moment k + 1, A, B, D are parameter matrices related to the self-parameters of the main motor, C is the output matrix for mapping the state of the main motor to the actual measurement data, u is the speed-loop control quantity of the main motor, T L is the load of the main motor, y(k) is the motor rotational speed of the system output at the current moment, and y(k + 1) is the motor rotational speed of the system output at the next moment k + 1.

[0093] After that, the master-slave motor system can predict the first predicted rotational speed y of the main motor at the next moment (e.g., at the moment of k+1) via the model predictive control module 51 p (k+1|k):

[0094]

[0095] where I is the identity matrix, which is used to add compensation to the system prediction to ensure more accurate state prediction of the system.

[0096] The phase compensation module 52 can obtain the first rotation angle θ of the main motor 20 as described above 1 and the phase difference Δφ between the second rotation angle θ of the slave motor 2 to calculate the corresponding phase compensation current Δi ω .

[0097] The second speed loop control module 53 can first determine the corresponding second target torque T according to the above first predicted rotational speed ω 1p =y p (k+1|k) and the second actual rotational speed ω of the slave motor 50 2 , and then combine the motor torque constant k of the slave motor 50 2p * to determine the second target current i t2 : 2 * :

[0098]

[0099] The second current loop control module 54 can determine the second drive current U according to the second target current i 2 * , the second actual current i 2 and the phase compensation current Δi ω . 2 .

[0100] In this way, in the embodiment shown in Figure 6 , the above master-slave motor system provided by the first aspect of the present invention can, when the computing power of the controller is limited, only turn on the PID closed-loop control and determine the second drive current with reference to the first predicted rotational speed output by the model predictive control module 51. Here, since the PID closed-loop control does not require rolling optimization, it has strong real-time performance and low computational complexity, but it can only perform control based on local information and cannot achieve global optimization, so that the system cannot reach the best performance.

[0101] Optionally, in some other embodiments, in response to the control period T MPC being less than the preset period upper limit T s, the master-slave motor system can determine that the current computing power is sufficient, and thus directly, via the model predictive control module 51, based on the first actual speed ω of the main motor 20 at the current moment (e.g., the k-th moment) 1 , the second actual speed ω of the slave motor 50 at the current moment 2 , and the speed ratio m between the main motor 20 and the slave motor 50, perform rolling optimization to determine the speed loop control quantity u that minimizes the objective function, and then, via the second current loop control module 54, based on the speed loop control quantity u, the second actual current i of the slave motor 30 at the current moment k 2 and the phase compensation current Δi ω , determine the second drive current U 2 .

[0102] Specifically, during the process of performing rolling optimization, the master-slave motor system can assume that the above-mentioned first predicted speed y p (k + 1|k) is equal to the first actual speed ω of the main motor, and based on the first actual speed ω 1 , construct the objective function J: 1

[0103] J = (ω 1 × m - ω 2 ) 2 + μΔu 2

[0104] where m is the speed ratio between the main motor 20 and the slave motor 50, μ is the weight of the speed loop control quantity u, and the speed loop control quantity u can specifically be the second target torque T of the second speed loop control module 53 of the slave motor 50 2 * . The first part (ω 1 × m - ω 2 ) 2 in the objective function J is the error between the system output and the target output part, and its second part μΔu 2 is the change in the control input. Thus, the present invention can, when solving the minimum value of the above-mentioned objective function J, minimize the error between the system output and the target output as much as possible to achieve the accuracy of system control, and at the same time limit the change in the control input u to ensure its smoothness and stability.

[0105] After that, the master-slave motor system can perform rolling optimization and solution on the speed loop control quantity μ based on the above-mentioned objective function J to obtain the optimal control strategy for the speed of the slave motor 50, that is, the solution when the objective function J takes the minimum value, so as to determine the second drive current U 2 .

[0106] Thus, when the computing power of the controller is sufficient, the master-slave motor system provided by the first aspect of the present invention can directly determine the second drive current via the speed loop control quantity u calculated and output by the model predictive control module 51 through rolling optimization, so as to globally optimize the control strategy for the speed of the slave motor 50, and flexibly adjust the control input in a dynamic environment to ensure the stable and efficient operation of the system.

[0107] In addition, in the calibration and maintenance scenarios of the Mueller matrix ellipsometer system, the master-slave motor system may also need to switch the rotation speed. For example, the master-slave motor system needs to verify the running stability and synchronous control effect of the rotation compensator by switching the rotation speed. For another example, when the optical characteristics of the detected sample have strong reflectivity or obvious interference, it is necessary to rotate the compensator at a high speed to improve the data sampling efficiency. For yet another example, higher rotation speeds are also required in multi-wavelength measurement scenarios to capture the rapid changes of different wavelengths.

[0108] Please refer to Figure 8 。 Figure 8 The curve schematic diagram of the acceleration curve provided according to some embodiments of the present invention is shown.

[0109] As Figure 8 shown, in response to the speed switching instruction, the master-slave motor system can determine the acceleration curve of the master motor 20 according to the first target speeds before and after the switching. Here, the acceleration curve is the curve of the rotation speed of the master motor 20 changing with time. In the above acceleration curve, from the moment t 0 to the moment t 1 , the rotation speed of the master motor 20 changes from v 0 to v 1 , the slope of the acceleration curve first increases and then decreases, that is, the acceleration of the master motor 20 first increases and then decreases, and gradually stabilizes after the rotation speed of the master motor 20 accelerates to the first target speed v 1 . After that, the master-slave motor system can perform weighted summation on the first target speed at the next moment indicated by the acceleration curve and the first predicted speed at the next moment output by the model predictive control module according to the preset weighting coefficient. Then, the master-slave motor system can input the result of the weighted summation into the second speed loop control module 53 of the slave motor 50 to combine with the second actual speed ω 2 of the slave motor 50 at the current moment to determine the corresponding second target current i 2 * , and then determine the second drive current U 2 * at the next moment according to the second target current i 2 ω and the second actual current i 2 at the current moment and the phase compensation current Δi .

[0110] After that, the master-slave motor system can supply the second drive current U to the slave motor 50 2 to control its synchronous rotation with the master motor 20.

[0111] In this way, the master-slave motor system provided by the first aspect of the present invention can further estimate the dynamic behavior of the motor at the next moment based on the model predictive control algorithm, and adjust the real-time control parameters of the motor according to the prediction results to correct possible speed or position deviations in advance, thereby further improving the control accuracy of the master-slave motor system.

[0112] In summary, the master-slave motor system, Mueller matrix ellipsometer system, synchronous control method of master-slave motors, and computer-readable storage medium provided by the present invention can all be used to ensure the high-precision synchronous rotation of the master-slave motors in the double-rotation compensator structure under complex scenarios of multiple frequencies and multiple dynamics by combining the technologies of dynamic compensation and real-time phase adjustment, so as to meet the high-precision optical measurement requirements.

[0113] Although the above methods are illustrated and described as a series of actions for simplicity of explanation, it should be understood and appreciated that these methods are not limited by the order of the actions, because according to one or more embodiments, some actions may occur in a different order and / or concurrently with other actions not illustrated and described herein but understood by those skilled in the art.

[0114] Those skilled in the art will understand that information, signals, and data can be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols, and chips described throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0115] Those skilled in the art will further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, the various illustrative components, boxes, modules, circuits, and steps are described above in terms of their functional form. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Skilled artisans may implement the described functionality in different ways for each particular application, but such implementation decisions should not be construed as causing a departure from the scope of the present invention.

[0116] Although the controller described in the above embodiments can be implemented by a combination of software and hardware, it can be understood that the controller can also be implemented in software or hardware. For hardware implementation, the controller can be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, other electronic devices for performing the above functions, or a selected combination of the above devices. For software implementation, the controller can be implemented by independent software modules such as procedures and functions running on a general-purpose chip, where each module performs one or more of the functions and operations described herein.

[0117] The steps of the methods or algorithms described in connection with the embodiments disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read from, and write to, the storage medium. In an alternative, the storage medium can be integrated into the processor. The processor and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In an alternative, the processor and the storage medium can reside as discrete components in the user terminal.

[0118] In one or more exemplary embodiments, the described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code. The computer-readable medium includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The storage media may be any available media that can be accessed by a computer. By way of example and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. As used herein, the disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where the disk typically reproduces data magnetically, while the disc reproduces data optically with a laser. Combinations of the above should also be included within the scope of computer-readable media.

[0119] The foregoing description of the disclosure has been provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A master-slave motor system, characterized in that: include: The main motor rotates according to the preset target angle; A slave motor, rotating synchronously with the master motor; a phase compensation module, determining a phase compensation current according to a derivative of a phase difference between a first rotation angle of the master motor and a second rotation angle of the slave motor; as well as The second current loop control module determines a second driving current for controlling the slave motor to rotate synchronously with the master motor at least according to a second actual current flowing through the slave motor and the phase compensation current.

2. The master-slave motor system according to claim 1, characterized in that: Also includes: a first position loop control module, determining a first target rotation speed according to a difference between the target angle and the first rotation angle; a first speed loop control module, determining a first target current according to a difference between the first target speed and a first actual speed of the main motor; as well as The first current loop control module determines a first driving current for controlling the rotation of the main motor according to a difference between the first target current and a first actual current flowing through the main motor.

3. The master-slave motor system according to claim 2, characterized in that: The first position loop control module performs PID control according to the difference between the target angle and the first rotation angle to determine the first target rotation speed. The first speed loop control module performs PI control according to the difference between the first target speed and the first actual speed to determine the first target current. The first current loop control module performs PI control according to the difference between the first target current and the first actual current to determine the first driving current.

4. The master-slave motor system according to claim 1, characterized in that: Also includes: a second position loop control module, determining a second target rotation speed according to the first rotation angle, the second rotation angle, and a rotation speed ratio between the master motor and the slave motor; as well as The second speed loop control module determines a second target current according to a difference between the second target speed and the second actual speed of the slave motor, wherein: The second current loop control module determines the second driving current according to the second target current, the second actual current and the phase compensation current.

5. The master-slave motor system according to claim 4, characterized in that: The second position loop control module performs PID control according to the first rotation angle, the second rotation angle, and the speed ratio between the master motor and the slave motor to determine the second target speed. The second speed loop control module performs PI control according to the difference between the second target speed and the second actual speed of the slave motor to determine the second target current. The second current loop control module performs PI control according to the second target current, the second actual current and the phase compensation current to determine the second driving current.

6. The master-slave motor system according to claim 1, characterized in that: Also includes: A model prediction control module, used for predicting a first predicted speed of the main motor at a next moment according to a first rotation angle and a first actual speed of the main motor at a current moment; as well as The second speed loop control module is used to determine a second target current according to the first predicted speed, the second actual speed of the slave motor, and the speed ratio between the master motor and the slave motor, wherein: The second current loop control module determines the second driving current according to the second target current, the second actual current and the phase compensation current.

7. The master-slave motor system according to claim 1, characterized in that: Also includes: A model predictive control module is used to perform rolling optimization according to a first actual speed ω1 of the main motor at the current moment, a second actual speed ω2 of the slave motor at the current moment, and a speed ratio between the main motor and the slave motor to determine a speed loop control amount u that minimizes an objective function, wherein the objective function is expressed as J=(ω1×m-ω2) 2 +μΔu 2 , m is the speed ratio of the master motor to the slave motor, μ is the weight of the speed loop control variable u, The second current loop control module determines the second target current of the slave motor at the next moment according to the speed loop control quantity u, and determines the second drive current in combination with the second actual current and the phase compensation current of the slave motor at the current moment.

8. The master-slave motor system according to claim 6 or 7, characterized in that: The master-slave motor system also includes a controller, which is configured to: Obtaining, via the phase compensation module, a phase difference between a first rotation angle of the master motor and a second rotation angle of the slave motor; In response to the phase difference being greater than a preset error threshold, determining a control period for the model predictive control module of the master-slave motor system to perform rolling optimization of the speed loop control amount u according to the current computing power state; In response to the control cycle being less than a preset cycle upper limit, determining the second drive current via the second current loop control module according to the speed loop control amount u output by the model prediction control module; as well as In response to the control cycle being greater than or equal to the cycle upper limit, the first predicted speed of the main motor at the next moment is predicted via the model prediction control module, the second target current is determined according to the first predicted speed via the second speed loop control module of the slave motor, and the second drive current is determined according to the second target current via the second current loop control module.

9. The master-slave motor system according to claim 8, characterized in that: The controller is also configured to: In response to the speed switching instruction, determining an acceleration curve of the main motor according to a first target speed before and after the switching; According to a preset weighting coefficient, a weighted sum is performed on the first target speed at the next moment indicated by the acceleration curve and the first predicted speed at the next moment output by the model prediction control module; as well as The result of the weighted summation is input into the second speed loop control module of the slave motor to determine the corresponding second target current in combination with the second actual speed of the slave motor at the current moment, and then the second current loop control module determines the second drive current at the next moment based on the second target current, the second actual current at the current moment and the phase compensation current.

10. A Mueller matrix ellipsometer system, characterized in that: include: A light source for providing a detection beam for a semiconductor device; A polarizer, located at the rear end of the light source, to adjust the detection light beam into a first linear polarized light; A first compensator, located at the rear end of the polarizer, is used to perform a first compensation on the first linear polarized light based on a first Mueller matrix, and transmit the first linear polarized light after the first compensation to a detection area on the surface of the sample to be tested; A second compensator, located at the rear end of the detection sample, is used to collect the reflected light output by the detection sample and perform a second compensation of a second Mueller matrix adapted to the first Mueller matrix; A polarizer, located at the rear end of the second compensator, for adapting the reflected light after the second compensation to the polarization of the polarizer to obtain a corresponding second linearly polarized light; The master-slave motor system according to any one of claims 1 to 9, used to drive the first compensator and the second compensator to rotate synchronously; as well as The detector is located at the rear end of the polarization detector and is used to collect the second linearly polarized light to characterize the device parameters of the detection area.

11. A synchronous control method for a master and a slave motor, characterized in that: The following steps are involved: Control the main motor to rotate according to the preset target angle; Determining a phase compensation current according to a derivative of a phase difference between a first rotation angle of the master motor and a second rotation angle of the slave motor; determining a second driving current at least according to a second actual current flowing through the slave motor and the phase compensation current; as well as The second driving current is provided to the slave motor to control the slave motor to rotate synchronously with the master motor.

12. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the computer instructions are executed by the processor, the synchronous control method of the master and slave motors as claimed in claim 11 is implemented.

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