Motion system having settable feed forward control

Abstract

To provide a motion system (10) including a motion hardware system (100) and a motion control system configured to control the operation of the motion hardware system (100).SOLUTION: A motion control system includes feed forward control including an anti-vibration system controller (230) for controlling the operation of at least 3DOF of an active anti-vibration system (114) for compensation by the action of a reaction force (F) on a pedestal (112) against a reaction force predicted to act by a motion stage (102) of the pedestal (112) upon operation. The feed forward control includes: a memory (224) for saving a character string which defines a motion equation based on topology of the motion stage (102); and a processing unit (222) for processing the character string for computing the reaction force (F).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a motion system for imparting motion to equipment, particularly semiconductor processing equipment, comprising a motion stage mounted on a pedestal which rests on an active vibration isolation system controlled by a configurable feedforward control to compensate for expected reaction forces acting on the motion stage on the pedestal during operation. [Background technology]

[0002] Precision motion systems, in particular semiconductor processing equipment such as positioning devices, coordinate measuring machines or robots, are equipped with so-called active isolation systems (as disclosed in US Pat. No. 5,399,433) for isolating the precision motion system from ground vibrations. An active isolation system typically comprises several active bearings assembled between a granite base on which the precision motion system can be mounted and a machine frame that rests on the floor. Thus, an active isolation system ensures the operation of the precision motion system with as few parasitic movements as possible, resulting in high positioning or measurement accuracy.

[0003] It is known to use feedforward control to compensate for reaction forces generated by precision motion systems. This compensation scheme uses the known stage motions to calculate the forces and torques that the actuators should apply to the base to compensate for the reaction forces and avoid undesired base motion.

[0004] Patent document 2 discloses an embodiment of a feedforward control in an optical lithography apparatus having a lens system fixed to a machine frame of the apparatus. The optical lithography apparatus comprises a motion stage having an object table located below the lens system and displaceable relative to the lens system on a guide surface of a support member coupled to the motion stage. The optical lithography apparatus is provided with a force actuator system fixed to a reference frame of the device and controlled by the feedforward control. The force actuator system exerts a compensating force on the machine frame during operation in a direction opposite to the direction of a reaction force exerted simultaneously by the motion stage on the support member and with a value substantially equal to the value of the reaction force. The apparatus also includes a feedback damping system for preventing movements of the machine frame caused by forces other than the driving force exerted by the positioning device on the object table, such as seismic forces transmitted from the ground on which the optical lithography apparatus is mounted.

[0005] US Patent No. 5,399,633 discloses another motion system including a motion stage, a feedforward control, and a feedback damping system. The feedforward control comprises a control unit adapted to compensate for the effects of inertial forces generated by the motion stage. The control unit comprises a memory and a model of the forces that may occur suddenly, the memory including transfer functions of the moving parts of the motion stage that appropriately filter the quasi-continuous forces to take into account the motion stage dynamics.

[0006] The feedforward control of the above-mentioned prior art motion systems is inconveniently dependent on the specific topology of the degrees of freedom of the motion stage. In this regard, US Pat. No. 6,299,333 discloses a motion stage that can move in the X and Y directions in a plane and requires compensation of in-plane reaction forces, while US Pat. No. 6,299,333 discloses a motion stage with only one degree of freedom. However, there are a wide variety of motion stage topologies with various types and numbers of degrees of freedom. The calculation of the reaction forces to be compensated based on the motion of the motion stage is performed inside the feedforward control using equations of motion. These must be adapted to each type of motion stage topology in order to calculate the reaction forces.

[0007] This calculation of reaction forces based on the motion stage topology implies programming and compiling a programming language that cannot be done in the field. Therefore, if the motion stage topology changes during the development phase, a new program for feedforward control needs to be compiled, which is cumbersome and slow. In addition, to support different motion stage topologies, the motion system needs to store a library of different programs to execute the equations of motion corresponding to each topology, whereby none of these programs can be removed from the library to avoid breaking backward compatibility. Over time, maintaining a library with many outdated entries can become a serious burden and costly. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] U.S. Patent No. 6,021,991 [Patent Document 2] European Patent Application Publication No. 0502578 [Patent Document 3] European Patent Application Publication No. 1803969 Summary of the Invention [Problem to be solved by the invention]

[0009] It is therefore an object of the present invention to provide a motion system having feedforward control that can be easily adapted to the particular topology of a motion stage.

[0010] It is another object of the present invention to provide a motion system that can be adapted to any new motion stage topology directly in the field. [Means for solving the problem]

[0011] In particular, these objectives are achieved by a motion system comprising a hardware system and a motion control system configured to control the operation of the hardware system. The hardware system comprises a motion stage, a platform supporting the motion stage, and a machine frame resting on a ground surface. The platform comprises a pedestal and an active vibration isolation system arranged between the pedestal and the machine frame. The active vibration isolation system comprises actuators that together provide actuation of at least three degrees of freedom (DOF) of the pedestal. The motion control system comprises a feedforward control comprising an isolation system controller for controlling at least 3 DOF actuation of the active vibration isolation system to compensate for expected reaction forces exerted on the pedestal by the motion stage during operation by applying countervailing forces to the pedestal. The feedforward control comprises a memory for storing a string of characters input by an operator and for defining equations of motion based on a topology of the motion stage, and a processing unit for processing the string of characters to compute the reaction forces.

[0012] In one embodiment, the motion control system further comprises at least one position controller configured to obtain the position and acceleration of the motion axis of the motion stage, a master controller, and a digital bus. The master controller is configured to receive and process data for the position and acceleration of the motion axis of the motion stage corresponding to the equation of motion. The digital bus connects the at least one position controller to the master controller and the latter to the active vibration isolation system controller. The master controller is configured to calculate a reaction force in real time based on the string and send the calculated reaction force to the active vibration isolation system controller.

[0013] In one embodiment, the master controller is configured to provide a user interface for editing the stored strings.

[0014] In one embodiment, the user interface is connected to the master controller via a wired or wireless network.

[0015] In one embodiment, the user interface includes a computer, a portable computer, a tablet, a smartphone, and / or a touch screen.

[0016] In one embodiment, the motion system further comprises another memory, e.g. a hard drive, for storing predefined strings defining equations of motion for the motion stage corresponding to different topologies of the motion stage which can be selected using dedicated software.

[0017] In one embodiment, the string is of the form

number

number

[0018] In one embodiment, the adjustable parameters include terms representing mass, size, angular momentum, and / or inertia.

[0019] In one embodiment, the motion control system is configured to provide a user interface for editing values ​​of said adjustable parameters.

[0020] In one embodiment, the motion system further comprises sensors in an active vibration isolation system for providing both 3DOF or 6DOF measurements of the pedestal movement, and a damping control device for controlling the 3DOF or 6DOF actuators of the active vibration isolation system based on the output of the sensors to dampen any vibrations caused, for example, by seismic forces transmitted from the ground.

[0021] In one embodiment, the adjustable parameter p → Adjustment of the vector of adjustable parameters is performed by performing a grid search adjustment by modifying one or more items of the vector of adjustable parameters to find a set of parameters that allows reducing the energy of the output signal generated by the damping control device.

[0022] In one embodiment, the adjustable parameter p → The adjustment of the vector of adjustable parameters is performed by the software by performing a model-based sensitivity analysis adjustment of the vector of adjustable parameters based on derivatives of the equations of motion that enable reducing the energy of the output signal generated by the damping control device.

[0023] The invention will be better understood from the description of some embodiments given by way of example and illustrated in the drawings. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 shows a block diagram of a motion system comprising a motion hardware system and a motion control system adapted to control the hardware system as a function of the expected movement of a motion stage. [Diagram 2] FIG. 2 shows a schematic diagram of the motion system of FIG. 1 including a first topology motion stage. [Diagram 3] FIG. 3 shows a block diagram of a feedforward control and feedback damping system of the motion control system of FIG. [Figure 4] FIG. 4 shows a schematic diagram of a motion hardware system similar to that of FIG. 2, but including a motion stage having an alternative topology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Referring to FIG. 1, motion system 10 comprises motion hardware system 100 and motion control system 200 configured to control motion stage 102 of hardware system 100 and to compensate for expected reaction forces exerted by motion stage 102 on base 112 by controlling active vibration isolation system 114 via digital bus 260.

[0026] 2, the motion hardware system 100 comprises a motion stage 102 of a particular topology, a support assembly 110 that supports the motion stage 102, and a machine frame 116 that holds the support assembly 110 and rests on a ground surface 300. The support assembly 110 comprises a pedestal 112, e.g., a granite slab, and an active vibration isolation system 114 mounted between the pedestal 112 and the machine frame 116.

[0027] The stationary part of the motion stage 102 is fixed to the base 112. The active vibration isolation system 114 comprises actuators (not shown) for together providing actuation of at least three degrees of freedom (DOF) of the base 112. In the illustrated embodiment of FIG. 2, the motion stage 102 comprises first and second linear motion axes 103a, 103b arranged to move the carriage along two orthogonal axes x, y in a coordinate system x, y, z. In the embodiment of FIG. 2, the second linear motion axis 103b is stacked on the first linear motion axis 103a by being attached to the carriage of the first linear motion axis 103a. Thus, when motion is performed in the first linear motion axis 103a, the moving mass is the sum of the mass of the carriage of the first linear motion axis 103a and the total mass of the second linear motion axis 103b. The equations of motion must take this into account to calculate the reaction forces. If the topology is inverted and the first linear motion axis 103a is stacked on top of the second linear motion axis 103b, then we need different equations of motion corresponding to this topology.

[0028] Referring to FIG. 3, the motion control system includes a feedforward control section 210 having an anti-vibration system controller 230 for controlling the operation of at least 3 DOF of the active vibration isolation system 114 to compensate for expected reaction forces acting on the pedestal 112 due to the movement of the first and second linear motion axes 103a, 103b of the motion stage 102 on the pedestal 112 when the motion stage 102 is in operation to move an apparatus, particularly a semiconductor processing apparatus, to a specific position, by a reaction force F acting on the pedestal 112, thereby providing an accurate positioning system that is not affected by the reaction forces generated by the motion stage on the pedestal.

[0029] The feedforward control 210 comprises a memory 224 for storing a string defining an equation of motion based on the topology of the motion stage 102, and a processing unit 222 for processing the string to compute a reaction force vector F.

[0030] Advantageously, the string determining the reaction force vector F does not need to be compiled prior to its use and therefore does not need to be provided in a specific programming language. This feature allows an important level of flexibility regarding the topology of the motion stage.

[0031] In one embodiment, a user may provide a text file containing strings to be read by the processing unit 222 to calculate the reaction force F.

[0032] In one embodiment, a user may use a graphical programming language or graphical system modeling to generate a string of characters to be read by the processing unit 222 to calculate the reaction force F.

[0033] 2, the motion control system includes first and second position controllers 250a, 250b for the motion stage 102. The second position controller 250b controls the position y and acceleration y of the motion of the carriage to which the first linear motion axis 103a is attached so as to drive along the y axis.·· The first position controller 250a is configured to drive the second linear motion axis 103b along the x-axis and to obtain the position x and acceleration x of the movement of the carriage. ·· The motion control system 200 further comprises a master controller 220 and a digital bus 260 connecting the first and second position controllers 250 a, 250 b to the master controller 220 and connecting the master controller 220 to the active vibration isolation system controller 230.

[0034] The main controller 220 uses the digital bus 260 as a transmission means, and when operating according to the string for calculating the reaction force vector F, the position x and acceleration x of the first linear motion axis 103a and the second linear motion axis 103b of the motion stage 102 are ·· , y ·· The master controller 220 is configured to receive and process data for the inputs and outputs of ...

[0035] Advantageously, the master controller 220 includes a user interface that allows an operator to enter and / or edit the equations of motion that determine the reaction forces F. In one embodiment, the user interface allows the user to enter a string that corresponds to the topology of the motion stage.

[0036] In one embodiment, the user interface may be integrated into the master controller or may be connected to the master controller via a wired network. Alternatively, the user interface may be connected to the master controller via a wireless network, allowing its use from remote devices.

[0037] For example, the user interface may be a simple bus for data transfer, such as a USB port that allows a user to transfer a file containing strings of characters. Alternatively or complementary, the user interface may include a means for a user to directly input (write) strings of characters into the master controller 220. The user interface may include a computer, a remotely connected computer, a tablet, a smartphone, or any other such type of electronic device that allows for sharing data with the master controller.

[0038] The first and second position controllers 250a, 250b each include delay circuits that delay the signals for driving the first and second linear motion axes 103a, 103b of the motion stage 102 by a few milliseconds to account for the master controller's computation time and digital bus latency. This ensures that the actuators of the active vibration isolation system 114 are controlled by the active vibration isolation system controller 230 in sync with the reaction forces applied by the motion stage 102 to the base 112.

[0039] In an advantageous embodiment, the active vibration isolation system 114 further comprises an inertial sensor, e.g., a seismic sensor (not shown) that together provide a 3DOF or 6DOF measurement of the motion of the pedestal 112. The support assembly comprises a feedback damping system 240 that transmits measurements from the inertial sensor to a damping controller 245 for controlling actuators of the active vibration isolation system 114 based on the output of the inertial sensor at each sampling period, which damps any vibrations caused by, e.g., seismic forces transmitted from the ground 300. The force vector output of the damping controller 245 is added to the calculated reaction force F and used as a force reference for actuators (not shown) that provide at least three degrees of freedom (DOF) actuation of the pedestal 112. Thus, the motion system 10 can counter the reaction forces of the motion stage while being isolated from vibrations from the ground 300.

[0040] The strings can be retrieved from a configuration file that can contain a configurable set of equations of motion corresponding to different predefined motion stage topologies. This file can be downloaded to memory 224 of master controller 220.

[0041] The formula used by the master controller 220 to calculate the reaction force F

number

number

[0042] The equations of motion are, at each sampling period, three forces F for a 6DOF system to compensate for the motion stage reaction forces: x , F y , F z and three torques T x , T y , T z The force calculations are given in the form of at least three equations for calculating the torque. The force calculations use Newton's second law of motion, F=m a and its equivalent for rotational motion. The equation for the torque value may include gravity compensation to maintain platform level as the motion stage moves in a plane.

[0043] Adjustable parameters p → The vector of includes terms representing the mass, dimensions such as length, width, height, diameter, angular momentum, and inertia of the motion stage. Any other relevant physical quantities for determining the reaction force F can be included in the vector of adjustable parameters.

[0044] The motion control system may provide a user interface for editing the values ​​of these adjustable parameters.

[0045] Adjustable parameters p → One or more parameters of the vectors can be adjusted using dedicated software to enhance the performance of the controlled motion system. A string can be provided to the software, allowing the evaluation of an equation that determines the reaction forces, which makes it possible to perform parameter tuning experiments.

[0046] In one embodiment, grid search parameter tuning can be performed by software to simultaneously optimize one or more parameters. Typically, the adjustable parameters P → The two parameters (P,P') of the vector are adjusted simultaneously. The test parameter (P i ,P iFor each pair of (x,y′), the stage motion of the motion stage is repeated. For each experiment, the motion of the pedestal 112 is measured. A dimension reduction algorithm such as PCA (Principal Component Analysis) can then be used to define a cost function. The minimum of this cost function provides the optimal combination of parameters that can be used to compute the reaction force F. The cost function can be defined as the energy of the output signal generated by the damping controller.

[0047] In another embodiment, a model-based sensitivity analysis tuning is performed, enabling a fast convergence tuning scheme. Here, a representation model-based means an analysis that takes into account the specific equations of motion corresponding to the topology of the motion stage, and therefore also the reaction forces to be applied. With reference to FIG. 3, the lower part with the damping control device 245 and the support assembly 110 can be well approximated by a linear system. Furthermore, the motion stage dynamics, all components of which may be selected and defined by the user, can usually be modeled with high accuracy. Thus, the reaction force F can be calculated from the measured output

number

[0048] Model-based sensitivity analysis involves the tuning of a tunable parameter p around a given starting point. → The parameters p form a vector i Q for → In other words, p → Partial derivative Q with respect to → is estimated around the measured signal. Then, the signal Q → p →The method is based on well-established theories of online parameter tuning, optimal control, iterative control and iterative learning control.

[0049] Alternatively or complementary, delay adjustments can be applied to compensate for communication bus transmission times and / or various accumulated phase delays within the overall control loop.

[0050] In one embodiment, the applied delay is considered as one additional parameter τ for all motion stage axes. The sensitivity of the output signal Q to this parameter τ is → , which is defined as the variation of , and can be estimated by finite differences using additional measurements performed with slightly different stage delays. This approach can be used in conjunction with both of the described tuning techniques.

[0051] 4 shows a motion hardware system 100 having motion stages 102 with different topologies with three degrees of freedom, i.e., two orthogonal linear motions along the x-axis, y-axis, and one rotational motion about the z-axis. This level of flexibility in defining the equations of motion allows for compensation of reaction forces of virtually any topology of motion stages mounted on the support assembly 110. Motion stages may be stacked linear and rotational systems, parallel kinematic systems, systems with any number of degrees of freedom, etc.

[0052] In more complex examples, the user may introduce intermediate temporary variables to reduce the overall number of operations. The above equations of motion, which correspond to a rigid body model of the motion stage, can be extended with some internal dynamics of the input or output filters, thereby covering more detailed modeling of the motion stage and the motion stage control. [Explanation of symbols]

[0053] 10 Motion System 100 Motion Hardware System 102 Exercise Stage 103a, 103b First and second linear motion axes 110 Support Assembly 112 Pedestal (e.g., granite) 114 Active Anti-Vibration System 116 Machine Frame 200 Motion Control System 210 Feedforward Control 220 Main Control Unit 222 Processing Unit 224 Memory 230 Anti-vibration system control device 240 Feedback Damping System 245 Damping Control Device 250a, 250b Position control device 252 Delay Timer 260 Digital Bus 300 ground

Claims

1. A motion system (10) comprising a motion hardware system (100) and a motion control system (200) configured to control the operation of the motion hardware system (100), The motion hardware system (100) comprises a motion stage (102), a support assembly (110) that supports the motion stage (102), and a mechanical frame (116) that is placed on the ground (300). The support assembly (110) comprises a base (112) and an active vibration isolation system (114) positioned between the base (112) and the machine frame (116). The active vibration isolation system (114) includes an actuator that provides joint operation of at least three degrees of freedom (DOF) of the base (112), The motion control system (200) includes a feedforward control (210) for controlling the operation of the active vibration isolation system (114) with at least 3DOF, which compensates for the expected reaction force acting on the motion stage (102) of the base (112) during operation by a reaction force (F) acting on the base (112). In the motion system (10), The feedforward control (210) includes a memory (224) for storing a string of characters that defines the equations of motion based on the topology of the motion stage (102), and a processing unit (222) for processing the string of characters in order to calculate the reaction force (F). A motion system (10) characterized by the following.

2. The motion control system (200) is Position (x; y) and acceleration (x) of the motion axis of motion stage (102) ・・ , y ・・ At least one position control device (250a, 250b) configured to obtain the position (x; y) and acceleration (x) of the motion axis of the motion stage (102) that match the equation of motion, and ・・ , y ・・ A main control device (220) configured to receive and process data for ), and The at least one position control device (250a, 250b), a main control device (220), and a digital bus (260) linked to the main control device (220) and the active vibration isolation system control device (230), Furthermore, The motion system (10) according to claim 1, wherein the main control device (220) is configured to calculate the reaction force (F) in real time based on the string and to transmit the calculated reaction force (F) to the active vibration isolation system control device (230).

3. The main control unit (220) is configured to provide a user interface for inputting and / or editing stored strings. The motion system (10) according to claim 2.

4. The user interface is connected to the main control unit via a wired or wireless network. The motion system (10) according to claim 3.

5. The user interface includes a computer, portable computer, tablet, smartphone, and / or touchscreen. The motion system (10) according to claim 3 or 4.

6. The system further includes another memory for storing a predetermined string of characters that defines the equations of motion for the motion stage (102) corresponding to different topologies of the motion stage, which can be selected using dedicated software. The motion system (10) according to claim 2.

7. The above string is in the following format, i.e., [Math 1] This includes mathematical formulas related to the equation, F = (F ｘ , F ｙ , F ｚ , T ｘ , T ｙ , T ｚ ) Ｔ is the vector of the reaction force in at least 3 DOF, [Math 2] These are the position and acceleration vectors of the axes of each motion stage, p → This is a vector of adjustable parameters, f is a function that defines the equations of motion for a given motion stage topology. The motion system (10) according to claim 1.

8. The vector of the adjustable parameters (p → ) includes items representing mass, dimensions, angular momentum, and / or inertia, The motion system (10) according to claim 7.

9. The motion control system (200) controls the vector (p) of the adjustable parameters. → Configured to provide a user interface for editing the value of ), The motion system (10) according to claim 7.

10. To provide both 3DOF or 6DOF motion measurements of the base (112), a sensor in the active vibration isolation system (114) and A feedback damping system (240) including a damping control device (245) for controlling the 3DOF or 6DOF actuators of the active vibration isolation system (114) based on the output of a sensor, in order to dampen all vibrations caused by seismic forces transmitted from the ground (300), and Furthermore, The motion system (10) according to claim 7.

11. The vector of the adjustable parameters (p → The adjustment of the attenuation control device (245) is performed by software that performs a grid search to adjust the vector of the adjustable parameters in order to obtain a set of parameters that enable the reduction of the energy of the output signal generated by the attenuation control device (245). The motion system (10) according to claim 10.

12. The adjustable parameter vector (p → The adjustment of the ) is performed by software that performs a model-based sensitivity analysis adjustment of the vector of the adjustable parameters based on the derivative of the equation of motion, which enables a reduction in the energy of the output signal generated by the damping control device (245). The motion system (10) according to claim 10.

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