JP6576111B2 - Drive system, motor control method, lithographic apparatus, and article manufacturing method - Google Patents

Description

The present invention, drive system, control method for motors, relates to a lithographic apparatus and articles manufacturing method.

  Patent Documents 1 and 2 disclose a linear motor control system that measures thrust ripple and corrects the control amount (current command value) of the linear motor using the measurement result. FIG. 8 shows a control block diagram of the linear motor control system having two pairs of a pair of mover and stator. In this linear motor control system, one of the movers is first driven in order to measure a thrust ripple with little disturbance. At the same time, the thrust ripple is measured from the induced voltage and drive speed generated between the other mover and stator. Thus, a compensation value (compensation coefficient) for compensating the thrust ripple is calculated from the thrust ripple obtained for each driving position, and a table in which the compensation values corresponding to the driving position are arranged is created. Similarly, a table of compensation values for the thrust ripple of the other mover is created. And when driving a linear motor, the compensation value of the thrust ripple according to a drive position is taken out from a table, and a control command value is correct | amended. (Patent Documents 1 and 2)

JP 2001-218497 A JP 2006-211183 A

  In patent documents 1 and 2, in order to measure the thrust ripple in the section in which the linear motor can be driven, the mover is moved over the entire movable section. Here, the entire section of the movable section includes a section in which the mover moves while accelerating or decelerating (referred to as an acceleration / deceleration section) and a section in which the mover moves at a constant speed. However, the mover must stop at both ends of the movable section of the mover. Therefore, in the acceleration / deceleration section, the speed of the mover is reduced and the SN ratio of the induced voltage is reduced. For this reason, the thrust ripple compensation values at both ends have a large noise component and low accuracy. If the command value of the current driver is corrected using the compensation value in the acceleration / deceleration section where the speed of the mover is small, the driving position of the linear motor may be greatly deviated from the target position. As a result, the drive deviation of the linear motor becomes large, and the positioning accuracy may be reduced.

  An object of the present invention is to provide a drive system with high drive accuracy over the entire movable section of the mover.

One aspect of the present invention includes a motor including a stator and a mover, a processing unit that determines a compensation value for compensating thrust ripple in the motor, and a control unit that controls driving of the motor. The movable section includes a first section capable of driving the movable element at a speed equal to or higher than a first speed, and the movable element is driven at a speed equal to or higher than the first speed. it includes a second section which can not, the processing unit, the interaction of the said stator me by the Rukoto move said movable element in said first speed or faster in the first section movable element And determining the compensation value in the second section based on the compensation value in the first section obtained from the measured value of the induced voltage caused by the velocity and the speed of the mover, and the control unit determines the first section. Compensation value and the processing unit Driving the motor by using the compensation value in the determined second interval Ri, characterized in that.

  According to the present invention, it is possible to provide a drive system with high drive accuracy over the entire movable section of the mover.

It is the figure which showed schematic structure of the positioning stage which uses a linear motor. It is the figure which showed the compensation value of the thrust ripple obtained by the drive speed of the needle | mover, and the prior art. It is a block diagram of a linear motor. It is a conceptual diagram of the method of calculating the compensation value of the thrust ripple in a 2nd area. It is a control block diagram of the drive system in the present invention. It is a table of the compensation value of the thrust ripple created using the method of the present invention. It is a flowchart of the method of acquiring the table of compensation values. It is a control block diagram of the linear motor control system in a prior art.

  Hereinafter, preferred embodiments of a drive system of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a top view showing a schematic configuration of a positioning stage using a linear motor. In the present embodiment, a linear motor is used as a motor including a stator having a plurality of coils and a mover. However, for example, a planar motor may be used. In FIG. 1, the stage 11 is provided with a pair of movers 31 on both the left and right sides in the driving direction (Y-axis direction). The pair of movers 31 constitutes the left linear motor 13 and the right linear motor 14 in cooperation with a corresponding pair of stators 32. The configuration of the linear motor will be described later.

  The stage 11 is provided with a reflecting mirror 12, and the amount of displacement or position of the stage 11 in the Y-axis direction is measured by reflecting measurement light from a laser interferometer (measurement unit) (not shown). A control unit 49 described later includes a controller 41 using a PID control system, and generates a control command value that gives thrust to the linear motor 44 based on the position data of the stage 11 measured by the laser interferometer. The linear motor 44 generates a driving force in the Y-axis direction by passing a current through the coil by the current driver 42, and drives the stage 11 to achieve position control. In the present embodiment, the control unit 49 calculates a command value such as PID control performed by the controller 41, and according to the drive position extracted from the compensation value table of thrust ripple with respect to the calculated command value. Multiplying the thrust ripple compensation value. In the present embodiment, the control unit 49 may compensate for the thrust ripple by performing an operation other than multiplication such as addition or subtraction of the compensation value to the original control command value.

  FIG. 3 is a configuration diagram of the linear motor 44. The mover 31 has a magnet unit 62 configured as a magnet group composed of a plurality of permanent magnets, and a mover plate 63 for holding the magnet unit 62 and attaching it to the stage surface. The magnet unit 62 includes a main pole magnet 62a whose magnetic pole direction is the Z direction and an auxiliary pole magnet 62b whose Y direction is the Y direction. The magnetic pole directions of the main pole magnets 62a are opposite to each other via the auxiliary pole magnets 62b, and are arranged at equal intervals in the Y direction. The auxiliary pole magnet 62b is provided in such a direction that the polarity of the portion of the main pole magnet 62a facing the coil 61 repels the auxiliary pole magnet 62b. The stator 32 has a coil 61 provided at equal intervals in the Y direction on a yoke 65 made of a ferromagnetic material, and is arranged so as to sandwich the mover 31 from above and below.

The thrust F [N] of the linear motor 44 when the current is I [A] flows when the thrust generated when the current is 1 [A] flows through the linear motor 44 is K [N], It is represented by 1.
F = K × I (1)
From Formula 1, it can be seen that the thrust F is proportional to I regardless of the position of the mover 31. Here, the proportionality constant K [N / A] in Equation 1 is called a thrust constant.

  However, in the actual linear motor 44, the thrust constant K varies depending on the position of the mover 31 due to manufacturing errors and mounting errors of the magnets 62a and 62b and the coil 61. Therefore, even if a constant current is passed through the linear motor 44, the thrust generated in the linear motor 44 varies depending on the position of the mover 31. This unevenness of thrust is called thrust ripple. In order to suppress this thrust ripple, a thrust constant K corresponding to the position of the mover 31 is obtained in advance, and a compensation value (details will be described later) of the thrust ripple calculated based on the thrust constant K is stored in the mover 31. It is held in the drive system as a table corresponding to the position. Then, the control unit 49 that controls the driving of the linear motor 44 performs the control by multiplying the thrust ripple compensation value corresponding to the position of the mover 31 by the command value to the current driver when the mover 31 is driven.

A method of obtaining a thrust ripple compensation value will be described. When the mover 31 of the linear motor 44 is moved at a speed v [m / s], an induced voltage Ve [V] is generated by the interaction between the magnet and the coil. The thrust constant K can be obtained from the speed v and the induced voltage Ve using the following equation 2.
K = v / Ve (2)
In the linear motor 44 of the stage 11 shown in FIG. 1, current is supplied to only one of the two movable elements 31 to drive it. At that time, an induced voltage generated by the interaction between the other mover (magnet) and the stator (coil) is measured. In this way, a pure thrust constant K that does not include any disturbance force applied to the stage 11 can be obtained. The reciprocal of the value obtained by dividing the thrust constant K by the average value Km of K will be referred to as a thrust ripple compensation value.

  The linear motor 44 is driven over the entire movable section of the movable element 31 (indicated by the arrow in FIG. 2A) in order to measure the thrust ripple in the movable section of the movable element 31. However, as shown in FIG. 2B, since the mover 31 must stop at both ends of the movable section, the mover 31 cannot be driven at a speed higher than the first speed at both ends. The second section (acceleration / deceleration section) 92 is obtained. The second section may be, for example, all or a part of the acceleration / deceleration section. In the second section 92, the SN ratio of the induced voltage is small. As a result, as shown in FIG. 2C, the compensation value 71 of the thrust ripple in the second section 92 is low in accuracy because of a large noise component. If the value of the low-precision compensation value in the second section 92 is directly multiplied by the command value of the current driver 42, the drive position of the linear motor 44 is greatly deviated from the target position.

  In the first section 91 in which the movable element 31 can be driven at a speed equal to or higher than the first speed, the driving speed at which the S / N ratio of the induced voltage can be maintained, so that an accurate compensation value of the thrust ripple can be obtained. The first section is a constant speed section, for example. Further, as shown in FIG. 2 (c), the thrust ripple compensation value is a periodic signal having a change in phase and amplitude in accordance with the arrangement period of the coils. That is, the compensation value in the second section can be approximated based on the accurate compensation value in the first section.

  Therefore, the compensation value for the second section 92 is obtained based on the compensation value for the first section 91. FIG. 4 shows conceptual diagrams of the following three methods for determining the compensation value Kr in the second section 92 based on the compensation value Kr ′ in the first section 91.

[First method]
In the first method, as shown in FIG. 4A, the compensation value Kr ′ in the first section is determined as it is as the compensation value Kr in the second section. That is, in the first method, as shown in the following Expression 3, the phase and amplitude changes with respect to the arrangement period of the coils of the two compensation values in the first section and the second section are the same.
Kr = Kr '(3)
In the second method, as shown in FIG. 4B, the compensation value obtained by shifting the phase of the compensation value Kr ′ in the first interval and multiplying the amplitude by a certain ratio is used as the second interval. Is determined as the compensation value Kr. The relationship between the compensation value Kr ′ in the first section and the compensation value Kr in the second section is expressed by the following equation 4. Note that α> 0, β: real number, and Kr ′ (y) is a compensation value at the position y.
Kr (y−β) = αKr ′ (4)
Here, both the phase shift and the weighting of the amplitude are performed to determine the compensation value Kr in the second section. However, the compensation value Kr in the second interval may be determined by performing one of phase shifting and amplitude weighting. The phase shift and the weighting of the amplitude are necessary when a step occurs at the joint between the two sections when the compensation value of the first section is used as it is as the compensation value of the second section. Therefore, the amount of phase shift and the degree of weighting of the amplitude are set so as to suppress the amount of the step within the allowable range at the joint between the two sections. Since there is a manufacturing error between the coil used in the first section and the coil used in the second section, phase shift and amplitude weighting can reduce the difference in thrust ripple caused by this manufacturing error.

In the third method, as shown in FIG. 4C, the compensation values Kr ′ of a plurality of periods in the first section are averaged, and weighting is performed by multiplying the amplitude of the averaged compensation value by a certain ratio. To determine the compensation value Kr in the second interval. The relationship between the compensation value Kr ′ in the first section and the compensation value Kr in the second section is expressed by the following equation 4. N is the number of periods, i = 1 to N, and α> 0.
Kr = (α / N) ΣKr ′ (5)
With reference to the control block diagram shown in FIG. 5, the creation of a compensation value table over the entire movable section of the linear motor and its application method will be described. First, a control block diagram will be described. The current driver 42, the changeover switch 43, the linear motor 44, the induced voltage intake port 48, the compensation value calculator 51 for the first section, the compensation value calculator 52 for the second section, and the compensation value table 53 for all sections are linear Configure the motor individually. The compensation value calculator 51 for the first section and the compensation value calculator 52 for the second section constitute a processing unit 46 that acquires a compensation value. The controller 41 and the stage 11 shown by the chain line frame are common to the left and right linear motors.

  Next, creation of a compensation value table over the entire movable section of the linear motor will be described with reference to FIG. In S1, a normal initialization operation is performed. At this time, the selector switch 43 in FIG. 5 is connected to the current driver 42 side. The initialization operation completes initialization of the laser interferometer and origination of the stage 11, and the position servo system functions to drive the stage 11 to an arbitrary position. In S2, the operation of measuring the thrust ripple of the right linear motor 14 is started. At this time, in the changeover switch 43 of FIG. 5, the right linear motor 14 is connected to the induced voltage intake port (induced voltage acquisition unit) 48, and the left linear motor 13 is connected to the current driver 42 side.

  In S3, since the stage 11 is driven only by the left linear motor 13, the controller 41 drives with a small acceleration that does not generate the θZ moment. The controller 41 moves the stage 11 to the Y-minus side stroke limit. Next, while driving at a constant speed up to the stroke limit on the Y plus side, the induced voltage generated in the coil of the right linear motor 14, the position of the mover and the driving speed are measured. Then, based on the thrust ripple data (thrust ripple information) obtained in S <b> 3, the processing unit 46 creates a compensation value correction table for the first section by the first section compensation value calculator 51. Further, the processing unit 46 uses the compensation value calculator 52 for the second section to calculate the compensation value for the second section based on the compensation value for the first section, and creates a compensation value table 47 for all sections of the right linear motor. create. An example of a compensation value table obtained by this method is shown in FIG. In FIG. 6, the portion corresponding to the second section 92 is a portion excluding the waveform having the same shape for the central four cycles. The broken line in the second section shows the waveform of the compensation value table in the second section when this technique is not applied, and the solid line in the second section shows the waveform of the compensation value table when this technique is applied. As can be seen from the comparison between the solid line and the broken line, the compensation value in the second section to which the present method is applied has a form approximating the compensation value in the first section.

  In S4, the changeover switch 43 of the right linear motor 14 in FIG. 5 is connected to the current driver 42 side, and the changeover switch 43 of the left linear motor 13 is connected to the induced voltage intake port 48 side. In S5, a compensation value table 47 is created over the entire movable section of the left linear motor 13 by the same procedure as in S3.

  Finally, a method of applying the compensation value table 47 will be described. The changeover switch 43 is connected to the current driver 42 side for both the left and right linear motors. The control unit 49 extracts a compensation value corresponding to the detection position of the stage 11 from the compensation value table 47, performs correction by multiplying the command value from the controller 41 to the current driver 42, and sends the correction value to the current driver 42. With this correction, the thrust ripple can be reduced at both ends of the movable section of the linear motor in which an abnormality has occurred in the stage position deviation in the conventional method. In other words, the position deviation of the stage can be improved throughout the movable section of the linear motor.

  The drive system according to the present invention can be used, for example, as a drive system that drives a stage that holds a substrate of a lithography apparatus that performs pattern formation on the substrate. In the present embodiment, moving at a constant speed means moving while being controlled with the goal of moving at a constant speed.

  The article manufacturing method according to one aspect of the present invention is suitable for manufacturing an article such as a micro device such as a semiconductor device or an element having a fine structure. The article manufacturing method of the present embodiment includes a step of transferring a pattern (latent image pattern) to a resist applied to a substrate using a lithography apparatus, and developing (processing) the substrate on which the latent image pattern is transferred in such a step. Including the step of. Further, the manufacturing method may include other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, and the like).

  31: Movable element. 32: Stator. 49: Control unit. 44: Linear motor (motor). 46: Processing unit.

Claims (17)

A drive system including a motor including a stator and a mover, a processing unit that determines a compensation value for compensating for thrust ripple in the motor, and a control unit that controls driving of the motor,
The movable section of the mover includes a first section in which the mover can be driven at a speed equal to or higher than a first speed, and a second section in which the mover can not be driven at a speed higher than the first speed. Including
Wherein the processing unit includes a measured value of the induced voltage caused by the interaction of the said stator and said mover I by the Rukoto to the mover moves in the first speed or a speed in the first section, the based on the compensation values in the first section obtained from the movable element of the speed, to determine the compensation value in said second section,
The control unit drives the motor using a compensation value in the first section and a compensation value in the second section determined by the processing section.   2. The drive system according to claim 1, wherein the compensation value in the first section is a compensation value obtained by moving the mover at a constant speed equal to or higher than the first speed. 3. The drive system according to claim 1, wherein the stator includes a plurality of coils, and the compensation value in the first section has a period corresponding to an arrangement period of the plurality of coils.   The drive system according to claim 3, wherein the processing unit determines the compensation value in the first section as it is as the compensation value in the second section. A drive system including a motor including a stator and a mover, a processing unit that determines a compensation value for compensating for thrust ripple in the motor, and a control unit that controls driving of the motor,
The movable section of the mover includes a first section in which the mover can be driven at a speed equal to or higher than a first speed, and a second section in which the mover can not be driven at a speed higher than the first speed. Including
The processing unit determines a compensation value in the second section based on a compensation value in the first section obtained by moving the mover at a speed equal to or higher than the first speed in the first section. Composed of
The control unit is configured to drive the motor using a compensation value in the first section and a compensation value in the second section determined by the processing unit,
The stator includes a plurality of coils, and the compensation value in the first section has a period according to an arrangement period of the plurality of coils,
Wherein the processing unit, operated systems and determines the compensation value compensation values obtained by weighting multiplying a certain ratio compensation value in the second section in the first section. A drive system including a motor including a stator and a mover, a processing unit that determines a compensation value for compensating for thrust ripple in the motor, and a control unit that controls driving of the motor,
The movable section of the mover includes a first section in which the mover can be driven at a speed equal to or higher than a first speed, and a second section in which the mover can not be driven at a speed higher than the first speed. Including
The processing unit determines a compensation value in the second section based on a compensation value in the first section obtained by moving the mover at a speed equal to or higher than the first speed in the first section. Composed of
The control unit is configured to drive the motor using a compensation value in the first section and a compensation value in the second section determined by the processing unit,
The stator includes a plurality of coils, and the compensation value in the first section has a period according to an arrangement period of the plurality of coils,
When the compensation values of a plurality of periods are included in the first interval, the processing unit averages the compensation values of the plurality of periods and weights the averaged compensation values by a certain ratio. It operated systems and determines the obtained compensation value as the compensation value in the second section by. The drive system according to claim 3 , wherein the processing unit further gives a phase shift to the compensation value in the second section to the compensation value in the first section. An acquisition unit that acquires data of an induced voltage generated by an interaction between the mover and the stator when the mover is moved;
A measurement unit for measuring the position of the mover,
The processing unit includes the first section based on the data of the induced voltage in the first section acquired by the acquiring unit and the data of the position of the mover in the first section acquired by the measuring section. the drive system according to any one of claims 1 to 7, characterized in that to obtain the compensation values in the. The motor drive system according to any one of claims 1 to 8, characterized in that a linear motor. A method for controlling a motor including a stator and a mover,
The movable section of the mover includes a first section in which the mover can be driven at a speed equal to or higher than a first speed, and a second section in which the mover can not be driven at a speed higher than the first speed. ,
The control method is:
The measured value of the induced voltage generated by the interaction of the mover and the stator by Rukoto to the mover moves in the first speed or faster in the first period, based on the speed of the mover An acquisition step of acquiring a compensation value for compensating for the thrust ripple of the motor in the first section;
A determination step of determining a compensation value for compensating for the thrust ripple of the motor in the second section based on the compensation value in the first section;
A driving step of driving the motor using the compensation value in the first section and the compensation value in the second section;
The control method characterized by including. The stator comprises a plurality of coils, the compensation value in the first section, the control method according to claim 1 0, characterized in that it has a period corresponding to the arrangement period of the plurality of coils. In the determination step, the control method according to claim 1 1, wherein the determining directly as the compensation value in the second section of the compensation values in the first section. A method for controlling a motor including a stator and a mover,
The movable section of the mover includes a first section in which the mover can be driven at a speed equal to or higher than a first speed, and a second section in which the mover can not be driven at a speed higher than the first speed. ,
The control method is:
An obtaining step of obtaining a compensation value in the first section based on information on thrust ripple obtained by moving the mover at a speed equal to or higher than the first speed in the first section;
A determination step of determining a compensation value in the second section based on the compensation value in the first section;
A driving step of driving the motor using the compensation value in the first section and the compensation value in the second section,
The stator includes a plurality of coils, and the compensation value in the first section has a period according to an arrangement period of the plurality of coils,
In the determination step, the control method characterized by determining a compensation value obtained by weighting multiplying a certain ratio compensation value in the first section as a compensation value in the second section. A method for controlling a motor including a stator and a mover,
The movable section of the mover includes a first section in which the mover can be driven at a speed equal to or higher than a first speed, and a second section in which the mover can not be driven at a speed higher than the first speed. ,
The control method is:
An obtaining step of obtaining a compensation value in the first section based on information on thrust ripple obtained by moving the mover at a speed equal to or higher than the first speed in the first section;
A determination step of determining a compensation value in the second section based on the compensation value in the first section;
A driving step of driving the motor using the compensation value in the first section and the compensation value in the second section,
The stator includes a plurality of coils, and the compensation value in the first section has a period according to an arrangement period of the plurality of coils,
If included compensation values of a plurality of cycles to the first section, the at decision step, averages the compensation values of the plurality of periods, to the weighting multiplying a certain ratio to the averaged compensation value The control method is characterized in that the compensation value obtained by the step is determined as a compensation value in the second section. In the determination step, further, the control method according to claim 1 1, 1 3 or 1 4, characterized in that gives a phase shift with respect to the compensation value in the first section to the compensation value in said second section. A lithographic apparatus for performing pattern formation on a substrate,
A stage for holding a substrate;
The drive system according to any one of claims 1 to 9 , which drives the stage;
A lithographic apparatus comprising: Performing pattern formation on a substrate using the lithographic apparatus according to claim 16 ;
Processing the substrate on which the pattern has been formed in the step;
An article manufacturing method comprising:

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