JP2013156884A - Stage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To respond to a request for enhancing the stability of holding of a finely positioned stage at a target position.SOLUTION: A driving control unit 9 performs coarse positioning control for positioning a stage 5 at a target position by moving the stage 5 toward the target position by a coarse adjustment driving unit until the absolute value of a position deviation becomes less than a first threshold, fine positioning control for positioning the stage 5 at the target position by moving the stage 5 toward the target position by a fine adjustment driving unit 9 until the absolute value of the position deviation becomes less than a second threshold after the coarse positioning control and holding control for holding the stage 5 at the target position by moving the stage 5 toward the target position by the fine adjustment driving unit 9 when the absolute value of the position deviation becomes larger than a third threshold after the fine positioning control.

Description

  The present invention relates to a stage device that is used in precision measuring devices and semiconductor manufacturing devices and performs high-precision positioning.

  2. Description of the Related Art In recent years, a stage apparatus used in a precision measuring apparatus or a semiconductor manufacturing apparatus is required to have a positioning accuracy of about several nanometers with the miniaturization of an LSI pattern. Furthermore, a stroke of 300 mm or more is required with an increase in wafer diameter. Moreover, the position variation from the stop position is required to be several nm or less during measurement and processing.

  As a stage device that performs high-precision positioning in this way, for example, Patent Document 1 discloses a coarse movement stage that can move a first stroke range (about 1 m) by a linear motor, and can move in the same direction as the coarse movement stage. A fine movement stage capable of moving within a second stroke range (approximately several μm) that is much smaller than the first stroke range, and a first feedback control for coarsely positioning the coarse movement stage at a target position A configuration including a system and a second feedback control system for finely positioning the fine movement stage is disclosed.

  By the way, after the fine movement stage is finely positioned, the stage position may fluctuate due to an external influence or the like. For example, if thermal expansion occurs in each member of the stage apparatus due to temperature fluctuation, the stage position may fluctuate slowly and greatly. Further, when a large disturbance vibration such as an external movement of a person is applied to the stage apparatus, the stage position may fluctuate quickly and greatly. In addition to this, for example, a minute vibration (disturbance noise) having a short vibration cycle by a peripheral device such as a vacuum pump may be applied to the stage device, and the stage position may be slightly vibrated.

  On the other hand, in the stage device of Patent Document 1 described above, the amount of deviation of the fine movement stage from the target position is measured by the second feedback control system, and the fine movement stage is automatically followed according to the amount of deviation. .

  However, in the case of such automatic tracking, since it takes time until the fine movement stage actually operates after receiving the control command, when the disturbance noise is added to the fine movement stage, the fine movement stage is added to the disturbance noise. The fine movement stage cannot easily follow and is easily displaced from the target position. In particular, when the disturbance noise and the natural vibration of the fine movement stage coincide with each other, the control operation causes the stage to vibrate, and further causes the stage to resonate.

  Therefore, there is a need for a stage apparatus that can stably hold the fine movement stage at the target position after fine movement positioning.

JP 2001-225241 A

  The present invention provides a stage apparatus that meets the demand to increase the stability of the finely positioned stage with respect to the target position.

  A stage apparatus according to an aspect of the present invention includes a stage, a coarse motion drive unit that moves the stage within a coarse motion stroke range, and the same direction as the coarse motion drive unit in a fine motion stroke range that is smaller than the coarse motion stroke range. A fine movement drive unit that moves the stage, a position detection unit that detects the current position of the stage, a target position, a first threshold value, and a second threshold value and a third threshold value that are smaller than the first threshold value. In addition, a position signal of the position detection unit is input, a position deviation that is a difference between the current position and the target position is calculated, and a magnitude relationship between the absolute value of the position deviation and the first to third threshold values is calculated. A drive control unit that controls the driving of the coarse motion drive unit and the fine motion drive unit by determining and outputting a drive signal to the coarse motion drive unit and the fine motion drive unit, the drive control The coarse motion for positioning the stage at the target position by moving the stage toward the target position by the coarse motion drive unit until the absolute value of the position deviation becomes smaller than the first threshold value. After the positioning control and the coarse movement positioning control, the stage is moved toward the target position by the fine movement driving unit until the absolute value of the position deviation becomes smaller than the second threshold value. Fine movement positioning control to position the stage at the target position, and after the fine movement positioning control, when the absolute value of the position deviation becomes larger than the third threshold value, the fine movement driving unit moves the stage to the target position. By moving the stage toward the target, holding control for holding the stage at the target position is performed.

  According to the stage device of one aspect of the present invention, the drive control unit moves the stage toward the target position by the fine movement drive unit when the position deviation becomes larger than the third threshold after the fine movement positioning control. In order to perform holding control, the stage is moved toward the target position with respect to large fluctuations in the stage position while suppressing the movement of the stage against minute vibrations (disturbance noise) and reducing the position displacement of the stage. The stage can be stably held at the target position.

It is a perspective view of the stage apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the flow of the drive method of the stage apparatus which concerns on one Embodiment of this invention. 3 is a flowchart showing in detail a flow of first fine feedback control of S104 in FIG. 3 is a flowchart showing in detail a flow of second fine feedback control of S109 in FIG. 5 is a graph showing the relationship between the passage of time and the position deviation of the stage device in the positioning control of the stage device of Experimental Example 1. 12 is a graph showing the relationship between the passage of time, the position deviation of the stage device, and the drive voltage in the positioning control of the stage device of Experimental Example 2. 14 is a graph showing the relationship between the passage of time, the position deviation of the stage device, and the drive voltage in the positioning control of the stage device of Experimental Example 3.

  Hereinafter, a stage apparatus according to an embodiment of the present invention will be described in detail with reference to FIG.

A stage apparatus 1 shown in FIG. 1 is for positioning a substrate 2 to be processed such as a wafer to be inspected or processed at a predetermined location in a precision measuring apparatus or a semiconductor manufacturing apparatus. The stage device 1 includes a flat base 3, a pair of guide members 4 such as a linear guide provided on the base 3, a stage 5 linearly guided in one direction by the guide members 4, A coarse drive unit 6 that moves the stage 5 in one direction within a coarse stroke range, and a fine drive unit 7 that moves the stage 5 in the same direction as the coarse drive unit 6 within a fine stroke range smaller than the coarse stroke range. And a position detection unit 8 that detects the current position of the stage 5 and a drive control unit 9 that controls the driving of the coarse movement drive unit 6 and the fine movement drive unit 7.

  The stage 5 is a complex of a coarse movement stage 10 provided on the guide member 4 and a fine movement stage 11 fixed on the coarse movement stage 10.

  The coarse movement stage 10 has a driven member 12 fixed in parallel with the guide member 4 on its upper surface, and a fine moving stage is applied to the driven member 12 by a driving force applied from the coarse movement driving unit 6. 11 and the guide member 4. As a result, the coarse movement stage 10 linearly moves in the coarse movement stroke range in one direction.

  The fine movement stage 11 has hinges 13 fixed at the four corners, and the hinge 13 is deformed by applying a driving force from the fine movement driving unit 7 to a side surface perpendicular to the guide member 4 of the fine movement stage 11. To do. Thereby, the fine movement stage 11 moves linearly in the fine movement stroke range in one direction. Further, the substrate 2 to be processed is placed on the fine movement stage 11.

  Thus, the stage 5 of this embodiment is positioned by positioning both the coarse movement stage 10 and the fine movement stage 11. Note that the stage 5 is not a complex of the coarse movement stage 10 and the fine movement stage 11 but may be composed of only a single stage to which driving force is applied from both the coarse movement drive unit 6 and the fine movement drive unit 7. I do not care.

  The coarse drive unit 6 has an ultrasonic motor including a piezoelectric element as a drive source. In the ultrasonic motor, the tip of the piezoelectric element is in contact with the driven member 12. When a voltage is applied to the piezoelectric element, the tip of the piezoelectric element draws an elliptical orbit due to the electrostrictive effect, and a frictional force is generated between the tip and the driven member 12, thereby causing coarse motion. The stage 10 is moved. Since the coarse motion stage 10 is moved by the coarse motion drive unit 6, the stroke (coarse motion stroke range) of the coarse motion stage 10 is as large as about 300 mm. However, the coarse motion stage 10 is positioned (coarse motion positioning). ) Has an accuracy of about several μm, and it is difficult to perform positioning with an accuracy of about several nm. In addition, as a drive source of the coarse motion drive part 6, you may use a servomotor or a linear motor other than an ultrasonic motor.

  The fine movement drive unit 7 has a piezo actuator as a drive source. The piezoelectric actuator is designed such that its tip is connected to the side surface of fine movement stage 11 so that the amount of displacement of the tip matches the amount of displacement of fine movement stage 11. When a voltage is applied to the piezo actuator, the tip of the piezo actuator is displaced linearly, thereby moving the fine movement stage 11. Since the fine movement stage 11 is moved by the fine movement drive unit 7, the stroke (fine movement stroke range) of movement of the fine movement stage 11 is as small as about 10 μm, but the positioning (fine movement positioning) of the fine movement stage 11 is about several nm. It can be performed at high speed with accuracy.

  The position detection unit 8 includes a position detection mirror 14 fixed on the fine movement stage 11 so as to be orthogonal to the guide member 4, a laser interferometer 15, and a laser light source (not shown).

  The drive control unit 9 outputs a drive signal to the coarse motion drive unit 6 based on a drive command from the host command device 16, and a coarse motion feedback control system 17 for moving the coarse motion stage 10, and a fine motion drive unit 7 includes a fine movement feedback control system 18 for outputting a drive signal to move the fine movement stage 11.

  The coarse motion feedback control system 17 performs coarse motion feedback control (coarse motion positioning control) for coarse motion positioning of the coarse motion stage 10 to a target position. The coarse motion feedback control system 17 includes a control computation unit 19 that performs various computation processes, an encoder counter 20 that converts a position signal from the laser interferometer 15 into actual position information, and a coarse motion feedback control program. A nonvolatile storage device 21 to be stored and a coarse motion D / A converter 22 that outputs a drive signal to the coarse motion drive unit 6 based on a computation result of the control computation unit 19 are configured. The coarse motion feedback control system 17 applies a predetermined drive signal (alternating voltage) from the coarse motion D / A converter 22 to the coarse motion drive unit 6 to cause the tip of the coarse motion drive unit 6 to move elliptically. Then, the coarse movement stage 10 is driven.

  The fine movement feedback control system 18 includes a first fine movement feedback control (fine movement positioning control) for finely positioning the fine movement stage 11 at the target position, and a second fine movement feedback control (holding control) for holding the fine movement stage 11 at the target position. ). The fine feedback control system 18 includes a control calculation unit 19 such as a CPU for performing various calculation processes, an encoder counter 20 for converting a position signal from the laser interferometer 15 into actual position information, and first and first control signals. 2 A non-volatile storage device 21 such as a memory for storing a fine movement feedback control program, and a fine movement D / A converter 23 that outputs a drive signal to the fine movement drive section 7 based on the calculation result of the control calculation section 19. ing. The fine movement feedback control system 18 applies a predetermined drive signal (DC voltage) from the fine movement D / A converter 23 to the fine movement drive section 7 and linearly displaces the tip of the fine movement drive section 7. Then, the fine movement stage 11 is driven.

  The calculation processing in the control calculation unit 19 includes a process of calculating a position difference between the current position and the target position input from the encoder counter 20 as a position deviation, a process of reading and writing various numerical values from the nonvolatile storage device 21, There are a process for determining the magnitude relationship of various numerical values, a process for calculating the voltage of the drive signal, a process for outputting the calculated voltage to the D / A converter, and the like.

  Next, a driving method of the stage device 1 based on a command from the higher order command device 16 will be described. In the driving method of the stage apparatus 1, as shown in FIG. 2, first, coarse motion feedback control is turned on (executed), the stage 5 is coarsely positioned at the target position, and then the coarse motion feedback control is turned off ( Stop). Next, the first fine movement feedback control is turned on, the stage 5 is finely positioned at the target position, and then the first fine movement feedback control is turned off. Next, the second fine feedback control is turned on to hold the stage 5 at the target position. In a steady state after the stage 5 is finely positioned, the coarse motion feedback control and the first fine motion feedback control are OFF, and only the second fine motion feedback control is ON, and the stage 5 is held at the target position. Yes.

  Hereinafter, according to the flowchart shown in FIG. 2, the calculation processing contents of the control calculation unit 19 in the driving method of the stage 1 will be described in detail.

  After the target position and the start command are input from the host command device 16, first, in step S100, the target position P1 and the fine movement positioning tolerance (second threshold) P2 are stored on the register of the control calculation unit 19. The permissible deviation of fine movement positioning is a value that is allowed as a position deviation when performing fine movement positioning, and regulates the precision of fine movement positioning, and is preferably set to 2 nm or more and 80 nm or less, for example, set to 5 nm. Is done. In addition, although not shown, the coarse motion positioning tolerance (first threshold) is also stored in the register of the control calculation unit 19. It is desirable to set the permissible deviation of the coarse motion positioning to less than half of the absolute value of the maximum displacement amount of the fine motion driving unit 7 measured in advance, and desirably set to 100 nm or more and 5000 nm or less, for example, 1 μm. Is set. Then, the process proceeds to S101.

  In S101, coarse motion feedback control is turned ON. Then, the process proceeds to S102.

  In S102, coarse movement positioning is performed by moving the coarse movement stage 10 to the target position using coarse movement feedback control. In this coarse movement positioning, the process proceeds to S103 when the absolute value of the position deviation becomes smaller than the allowable deviation (first threshold value) of the coarse movement positioning, that is, within the movable range of the fine movement drive unit 7. .

  In S103, coarse motion feedback control is turned off. Then, the process proceeds to S104.

  In S104, the first fine feedback control is turned on. Then, the process proceeds to S105.

  In S105, the output value of the encoder counter 20 is read, and the current position P3 of the fine movement stage 11 is recorded on the register of the control calculation unit 19. Then, the process proceeds to S106.

  In S106, the absolute value P4 of the position deviation is calculated by the following formula.

P4 = absolute value of (P1-P3) Then, the process proceeds to S107.

  In S107, the absolute value P4 of the position deviation calculated in S106 and the fine movement allowable deviation P2 are compared to determine the magnitude relationship. If the absolute value P4 of the position deviation is smaller than the fine movement allowable deviation P2, the process proceeds to S108. . Otherwise, the process proceeds to S105, and the first loop from S105 to S107 is repeated until the absolute value P4 of the position deviation becomes smaller than the fine movement allowable deviation P2. This first loop is executed every servo cycle of the control calculation unit 19, and is executed once every 0.4 milliseconds, for example.

  In S108, the first fine feedback control is turned off. Then, the process proceeds to S109.

  In S109, the second fine feedback control is turned on to be in a steady state.

  By driving the stage device 1 as described above, the stage 5 is coarsely positioned at the target position at a high speed by the coarse movement feedback control, and then finely positioned at the target position at a high speed and with high accuracy by the first fine movement feedback control described later. Further, the fine movement stage 11 can be stably finely held at the target position by the second fine movement feedback control described later.

  Next, the first fine feedback control in S104 described above will be described in detail according to the flowchart shown in FIG.

  First, in S200, the gain switching threshold value (fifth threshold value) T1, the first gain G1, and the second gain G2 are read from the nonvolatile storage device 21 onto the register of the control calculation unit 19.

The gain switching threshold T1 is used for switching between a range in which the fine movement stage 11 is moved at high speed and a range in which the fine movement stage 11 is moved with high accuracy, and is larger than the allowable deviation P2. The gain switching threshold T1 is preferably set to 3 nm or more and 100 nm or less.
Set to 5 nm. The first gain G1 is for moving the fine movement stage 11 at a high speed, and is larger than the second gain G2. The first gain G1 is set to 0.1, for example. The second gain G2 is for moving the fine movement stage with high accuracy. The second gain G2 is set to 0.05, for example. Then, the process proceeds to S201.

  In S <b> 201, the first gain G <b> 1 is also read from the nonvolatile storage device 21 and set on the register as an initial value of the gain G used in the arithmetic control unit 19. Then, the process proceeds to S201.

  The gain G varies the applied voltage of the drive signal in accordance with the position deviation (P1-P10) between the target position P1 and the current position P10 in S207, which will be described later, and as a result, the fine-movement D / A converter This is to change the applied voltage of the drive signal output from 23 to control the movement amount of fine movement drive unit 7. Therefore, when the gain G is the first gain G1, the gain G is larger than the second gain G2, and therefore, the fluctuation range of the applied voltage of the drive signal to the fine movement drive unit 7 with respect to the position deviation (P1-P10). Thus, the fine movement stage 11 can be moved more greatly.

  In S202, the output value of the encoder counter 20 is read, and the current position P10 of the fine movement stage 11 is recorded on the register of the control calculation unit 19. Then, the process proceeds to S203.

  In S203, the absolute value P11 of the position deviation is calculated by the following formula.

P11 = absolute value of (P1-P10) Then, the process proceeds to S204.

  In S204, the gain G and the first gain G1 are compared to determine the magnitude relationship. If the gain G is equal to the first gain G1, the process proceeds to S205. Otherwise, the process proceeds to S207.

  In S205, the absolute value P11 of the position deviation is compared with the gain switching threshold T1 to determine the magnitude relationship. If the absolute value P11 of the position deviation is smaller than the gain switching threshold T1, the process proceeds to S206. Otherwise, the process proceeds to S207.

  In S206, the second gain G2 is read from the nonvolatile memory device 21 and set as the gain G. Then, the process proceeds to S207.

  In S207, the current applied voltage V1 is read from the nonvolatile storage device 21 onto the register of the control calculation unit 19. Then, the process proceeds to S208.

  In S208, a new applied voltage V is calculated by adding the product of the position deviation (P1-P10) and the gain G as a change amount of the applied voltage in addition to the current applied voltage V1 by the following equation.

V = V1 + (P1-P10) × G
Then, the process proceeds to S209.

  In S209, the new applied voltage V is set as the current applied voltage V1, and the current applied voltage V1 is stored in the nonvolatile storage device 21. Then, the process proceeds to S210.

  In S210, the information on the new applied voltage V set in S208 is output to the fine movement D / A converter 23, and the applied voltage of the drive signal to the fine movement drive unit 7 is changed, so that the fine movement stage 11 is moved to the target position. Move towards. Then, the process proceeds to S202, and the second loop from S202 to S210 is repeated. This second loop is repeated until the above-described first loop ends and the process proceeds from S107 to S108. This second loop is executed every servo cycle of the control calculation unit 19, and is executed once every 0.4 milliseconds, for example.

  As described above, the fine movement stage 11 can be finely positioned at high speed and with high accuracy by moving the fine movement stage 11 to the target position using the first fine movement feedback control that repeats the second loop.

  In particular, in the first fine feedback control, two gains, a first gain G1 for moving the fine movement stage 11 at high speed and a second gain G2 for moving with high accuracy, are set. In S204 to S206, when the absolute value P11 of the position deviation becomes smaller than the gain switching threshold (fifth threshold) T1, the gain G is switched from the first gain G1 having a larger value to the second gain G2 having a smaller value. Are used. That is, when the position deviation is closer than the desired distance, the gain G is set to a small second gain G2, and the position deviation (P1) due to minute vibration (hereinafter referred to as disturbance noise) with respect to the fine movement stage 11 is set. -P10) error amplification can be suppressed, and the fine movement positioning accuracy of the fine movement stage 11 can be increased. For this reason, the fine movement stage 11 can be moved at high speed and with high accuracy to perform fine movement positioning.

  Further, since the above-described operation is performed from S204 to S206, once the gain G is switched from the gain G1 to the gain G2, the gain G does not return to the gain G1. Therefore, even if a sudden large disturbance vibration occurs near the target position, a stable positioning operation can be performed without vibrating the fine movement stage 11.

  Next, the second fine feedback control in S109 described above will be described in detail according to the flowchart shown in FIG.

  First, in S300, the fixed calculation fluctuation threshold value T2, the gain calculation fluctuation threshold value T3, the voltage fluctuation value V2, and the third gain G3 are read from the nonvolatile memory device 21 onto the register of the control calculation unit 19. Then, the process proceeds to S301.

  Here, the fixed calculation fluctuation threshold T2 is for excluding the influence of disturbance noise in the second fine movement feedback control. This fixed calculation fluctuation threshold T2 is preferably set to a value larger than the amplitude of the disturbance noise, and is preferably set to 2 nm or more and 10 nm or less, for example, 2 nm. The gain calculation fluctuation threshold T3 is used to follow disturbance vibration while reducing rapid fluctuation of the fine movement stage 11 due to large disturbance vibration. The gain calculation fluctuation threshold T3 is preferably set to a value larger than the fixed calculation fluctuation threshold T2, and is preferably set to 4 nm or more and 20 nm or less, for example, 4 nm. The fixed calculation fluctuation threshold T2 is preferably smaller than the allowable deviation P2 in order to make the position fluctuation of the fine movement stage smaller than the allowable deviation P2.

  Further, the voltage fluctuation value V2 makes the fine movement stage 11 a target position while reducing the influence of disturbance noise by suppressing the movement of the fine movement stage 11 by making the movement amount per unit time of the fine movement stage 11 constant. It is to move toward. The voltage fluctuation value V2 is preferably set to 0.1 mV or more and 10 mV, and is set to 0.3 mV, for example.

The third gain G3 is a fine movement stage 1 corresponding to a positional deviation with respect to a large disturbance vibration.
The amount of movement per unit time is increased. The third gain G3 is preferably set to 0.01 or more and 1.0 or less, for example, 0.08.

  In S301, the output value of the encoder counter 20 is read, and a value obtained by moving and averaging the output values is recorded on the register of the control calculation unit 19 as the current position P20 of the fine movement stage 11. Then, the process proceeds to S302.

  In S302, the position deviation P21 is calculated by the following equation.

P21 = P1-P20
Then, the process proceeds to S303.

  In step S <b> 303, the current applied voltage V <b> 1 is read from the nonvolatile storage device 21 and recorded on the register of the control calculation unit 19.

  In S304, the absolute value of the position deviation P21 is compared with the fixed calculation fluctuation threshold value T2, and the magnitude relationship is determined. If the absolute value of the position deviation P21 is larger than the fixed calculation fluctuation threshold value T2, the process proceeds to S305. Otherwise, the process proceeds to S307.

  In S305, the positional deviation P21 is compared with 0 to determine the magnitude relationship. If the positional deviation P21 is smaller than 0, the process proceeds to S306 (a). Otherwise, the process proceeds to S306 (b).

  In S306 (a), a value obtained by adding the voltage fluctuation value V2 to the current applied voltage V1 in S305 is set as a new current applied voltage V1 by the following equation.

V1 = V1 + V2
Then, the process proceeds to S307.

  In S306 (b), a value obtained by subtracting the voltage fluctuation value V2 from the current applied voltage V1 in S305 is set as a new current applied voltage V1 by the following equation.

V1 = V1-V2
Then, the process proceeds to S307.

  In S307, the absolute value of the position deviation P21 is compared with the gain calculation fluctuation threshold T3 to determine the magnitude relationship. If the absolute value of the position deviation P21 is larger than the gain calculation fluctuation threshold T3, the process proceeds to S308. Otherwise, the process proceeds to S309.

  In S308, the product of the position deviation P21 and the third gain G3 is added to the current applied voltage V1 in S307 as a new current applied voltage V1 using the following equation as a change amount of the applied voltage. Note that the current applied voltage V1 calculated in S308 has passed both S306 and S308, and both the addition or subtraction of the voltage fluctuation value V2 and the gain correction by the third gain G3 are performed.

V1 = V1 + (P1-P20) × G3
Then, the process proceeds to S309.

  In S309, the value of the current applied voltage V1 is stored in the nonvolatile storage device 21. Then, the process proceeds to S310.

  In S310, the value of the current applied voltage V1 is output to the fine movement D / A converter 23, the applied voltage of the drive signal of the fine movement drive unit 7 is changed, and the fine movement stage 11 is moved toward the target position. And it transfers to S301 and repeats the 3rd loop from S301 to S310. This third loop is continuously repeated while the fine movement stage 11 is in the position holding state. Further, in the third loop, S304 to S306 are set to have a lower execution frequency than other steps, and are executed once every 100 milliseconds, for example. Further, in the third loop, the steps other than S304 to S306 are executed every servo cycle of the control calculation unit 19 as in the first and second loops, and are executed at a frequency of once every 0.4 milliseconds, for example. The

  As described above, the fine movement stage 11 can be stably held by holding the fine movement stage 11 at the target position using the second fine movement feedback control that repeats the third loop.

  In particular, in the second fine feedback control, from S304 to S310, since the fixed calculation fluctuation threshold T2 is smaller than the gain calculation fluctuation threshold T3, the absolute value of the position deviation P21 is smaller than the fixed calculation fluctuation threshold T2. Since the process proceeds to S307 after S304 and further to S309 after S307, the currently applied voltage V1 does not change. Therefore, since the fine movement drive unit 7 does not change, noise having an amplitude smaller than the fixed calculation fluctuation threshold T2 can be ignored, and the positional deviation of the fine movement stage 11 due to this noise is reduced, and as a result, the fine movement stage 11 is moved. It can be held stably.

  When the absolute value P21 of the position deviation is larger than the fixed calculation fluctuation threshold T2 and smaller than the gain calculation fluctuation threshold T3, the process proceeds to S305 after S304, but proceeds to S309 after S307. The value of the current applied voltage V1 changes with the voltage fluctuation value V2 being a constant value as the displacement. Therefore, the fine movement stage 11 can be moved to the target position and held at the target position while keeping the displacement amount per unit time constant. In addition, since the amount of displacement per unit time is constant, the influence of the vibration period of disturbance noise can be reduced, and the fine movement stage 11 can be stably held without oscillating. The displacement amount per unit time is a displacement amount measured for each servo cycle of the control calculation unit 19. Further, the movement amount per unit time refers to the absolute value of the displacement amount per unit time.

  If the absolute value of the position deviation P21 is larger than the gain calculation variation threshold T3, the process proceeds to S305 after S304 and to S308 after S307, so that the gain using the third gain G3 is used. Since the correction is performed and the applied voltage changes according to the value of the position deviation, the applied voltage of the drive signal to the fine movement drive unit 7 increases as the position deviation increases, and the fine movement stage 11 moves per unit time. The amount is increased. Therefore, when the amount of movement from the target position exceeds a certain range, the fine movement stage 11 can be moved to the target position at high speed, and the position of the fine movement stage 11 can be stabilized even against a large disturbance vibration. Can be retained.

  In the third loop, S304 to S306 are set to be executed less frequently than the other steps of the third loop. As a result, the movement of the fine movement stage 11 due to the influence of disturbance noise can be reduced, and the fine movement stage 11 can be stably held at the target position.

In the third loop, steps other than S304 to S306 are set to be executed more frequently than S304 to S306. As a result, even when the fine movement stage 11 receives a large disturbance vibration, the fine movement stage 11 can be immediately moved, so that the fine movement stage 11 can be stably held at the target position.

  In S301, the output value of the encoder counter 20 is read, and a value obtained by moving and averaging the output values is recorded in the nonvolatile storage device 21 as the current position P20 of the fine movement stage 11. By using the moving average value in this way, components having different disturbance noise directions with respect to the target position are integrated and canceled out, so that the movement of the fine movement stage 11 due to the influence of the disturbance noise can be reduced. .

  EXAMPLES Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the following examples, and all modifications and embodiments within the scope of the present invention do not depart from the gist of the present invention. Included in range.

(Preparation of stage equipment)
Stage devices of Experimental Examples 1 to 3 having the same structure as that of the above-described embodiment but different in positioning control were manufactured.

  The stage device of Experimental Example 1 has steps from S100 to S104 in the positioning control of FIG. 2, but does not have steps after S105, and has the second fine feedback control of FIG. Not. Further, in the stage apparatus of Experimental Example 1, in the steady state after positioning, the coarse motion feedback control is OFF and the first fine motion feedback control is ON.

  The stage device of Experimental Example 2 has all the steps from Step 100 to Step 109 in the positioning control of FIG. 2, but has the steps of S307 and S308 in the second fine feedback control of FIG. The gain calculation variation threshold T3 and the third gain G3 are not used. In the stage device of Experimental Example 2, in the steady state after positioning, the coarse motion feedback control is OFF, the first fine motion feedback control is OFF, and the second fine motion feedback control is ON.

  The stage device of Experimental Example 3 has all the steps from Step 100 to Step 109 in the positioning control of FIG. 2, and has all the steps of S300 to S310 in the second fine feedback control in FIG. doing. In the stage device of Experimental Example 3, in the steady state after positioning, the coarse motion feedback control is OFF, the first fine motion feedback control is OFF, and the second fine motion feedback control is ON.

  Note that the stage devices of Experimental Examples 1 to 3 have all the steps from S200 to S210 in the first fine feedback control in FIG.

  Further, in the positioning control of the stage devices of Experimental Examples 1 to 3 described above, each numerical value is set as follows.

Coarse positioning tolerance: 1μm
Fine movement positioning tolerance P2: 5 nm
Gain switching threshold T1: 15 nm
Fixed calculation fluctuation threshold T2: 2 nm
Gain calculation fluctuation threshold T3: 4 nm
Voltage fluctuation value V2: 0.3 mV
First gain G1: 0.1
Second gain G2: 0.05
Third gain G3: 0.08
(Evaluation method)
In Experimental Examples 1 to 3, the stage device positioning control was performed, and the position deviation of the stage was measured when the steady state was obtained. In Experimental Examples 2 and 3, the applied voltage of the drive signal to the fine movement drive unit was measured.

(Evaluation results)
FIG. 5 is a graph showing the relationship between the passage of time and the position deviation of the stage in the positioning control of the stage device of Experimental Example 1. The horizontal axis in FIG. 5 indicates the elapsed time (sec) starting from the start of positioning control (S100), and the vertical axis in FIG. 5 indicates the position deviation (nm) of the stage.

  As shown in FIG. 5, in the stage apparatus of Experimental Example 1, the stage oscillates in a steady state. This is because in the first fine feedback control, there is a time delay from the feedback calculation to when the motor operates by changing the drive voltage and the stage position changes. As a result, the stage moves with a certain time delay with respect to the disturbance noise of the stage, and this movement amplifies the disturbance noise of the stage and causes the stage to oscillate.

  FIG. 6 is a graph showing the relationship between the passage of time, the stage position deviation, and the applied voltage of the drive signal in the positioning control of the stage apparatus of Experimental Example 2. The horizontal axis in FIG. 6 represents the elapsed time (sec) starting from the start of positioning control (S100). Of the vertical axes in FIG. 6, the first axis (left side) is the stage position deviation (nm). The second axis (right side) shows the applied voltage (mV) of the drive signal.

  As shown in FIG. 6, the stage apparatus of Experimental Example 2 does not oscillate in a steady state, and the stage position is stably held at the target position as compared with the stage apparatus of Experimental Example 1. . This is because the position of the stage is not controlled with respect to the disturbance noise of the stage in the second fine feedback control.

  On the other hand, in the stage apparatus of Experimental Example 2, the stage position is greatly deviated from the target position, and it takes time to return to the target position. This is because the steps S307 and S308 are not provided, so that the position control of the stage is delayed, and fast disturbance noise cannot be followed.

  FIG. 7 is a graph showing the relationship between the passage of time, the position deviation of the stage, and the applied voltage of the drive signal in the positioning control of the stage device of Experimental Example 3. The horizontal axis in FIG. 7 indicates the elapsed time (sec) starting from the start of positioning control (S100). Of the vertical axes in FIG. 7, the first axis (left side) is the stage position deviation (nm). The second axis (right side) shows the applied voltage (mV) of the drive signal.

  As shown in FIG. 7, the stage apparatus of Experimental Example 3 does not oscillate in a steady state. This is because the position of the stage is not controlled with respect to the disturbance noise of the stage in the second fine feedback control as in the second experimental example.

  Furthermore, in the stage apparatus of Experimental Example 3, only the driving voltage is changed and the position of the stage is not shifted from the target position. This is because the steps S307 and S308 are performed so that the gain correction of S308 works effectively for fast disturbance noise, and the stage position is controlled to be constant without being affected by the disturbance noise. is there.

  From the above results, according to the stage apparatus of the present invention, the second fine movement feedback control (holding control) using the fixed calculation fluctuation threshold T2 (third threshold) is performed, thereby suppressing the oscillation of the stage. It was confirmed that the position could be stably held at the target position.

DESCRIPTION OF SYMBOLS 1 Stage apparatus 2 Substrate 3 Base 4 Guide member 5 Stage 6 Coarse movement drive part 7 Fine movement drive part 8 Position detection part 9 Drive control part 10 Coarse movement stage 11 Fine movement stage 12 Driven member 13 Hinge 14 Position detection mirror 15 Laser interferometer 16 High-order command device 17 Coarse motion feedback control system 18 Fine motion feedback control system 19 Control operation unit 20 Encoder counter 21 Non-volatile memory device 22 Coarse motion D / A converter 23 Fine motion D / A converter

Claims (7)

Stage,
A coarse drive unit that moves the stage within a coarse stroke range;
A fine movement drive unit that moves the stage in the same direction as the coarse movement drive unit in a fine movement stroke range smaller than the coarse movement stroke range;
A position detector for detecting the current position of the stage;
A target position, a first threshold value, a second threshold value and a third threshold value smaller than the first threshold value are set, and a position signal of the position detection unit is input, and a difference between the current position and the target position is By calculating a certain position deviation, determining the magnitude relationship between the absolute value of the position deviation and the first to third threshold values, and outputting a drive signal to the coarse motion drive unit and the fine motion drive unit, A dynamic drive unit and a drive control unit for controlling the drive of the fine movement drive unit,
The drive control unit
Coarse positioning control for positioning the stage at the target position by moving the stage toward the target position by the coarse driving unit until the absolute value of the position deviation becomes smaller than the first threshold. When,
After the coarse movement positioning control, the stage is moved toward the target position by the fine movement drive unit until the absolute value of the position deviation becomes smaller than the second threshold, thereby moving the stage toward the target position. Fine positioning control to position
After the fine movement positioning control, when the absolute value of the position deviation becomes larger than the third threshold value, the fine movement driving unit moves the stage toward the target position, thereby moving the stage to the target position. A stage apparatus that performs holding control to hold in position. The stage apparatus according to claim 1, wherein
The drive control unit
A fourth threshold value that is larger than the third threshold value is further set, and further determines the magnitude relationship between the absolute value of the positional deviation and the fourth threshold value;
In the holding control, when the absolute value of the positional deviation is larger than the fourth threshold, the absolute value of the positional deviation is larger than the third threshold and smaller than the fourth threshold. A stage device characterized by increasing the amount of movement of the stage per unit time. The stage apparatus according to claim 2, wherein
In the holding control, when the absolute value of the position deviation is larger than the third threshold and smaller than the fourth threshold, the movement amount per unit time of the stage is made constant,
When the absolute value of the position deviation is larger than the fourth threshold value, the stage apparatus increases the amount of movement of the stage per unit time as the absolute value of the position deviation increases. The stage apparatus according to claim 3, wherein
In the holding control,
A stage device characterized in that the frequency of determination of the magnitude relationship between the absolute value of the position deviation and the third threshold is less than the frequency of judgment of the magnitude relationship between the absolute value of the position deviation and the fourth threshold. . The stage apparatus according to claim 1, wherein
In the fine movement positioning control,
A stage apparatus characterized by increasing the amount of movement of the stage per unit time as the absolute value of the position deviation increases. The stage apparatus according to claim 5, wherein
The drive control unit further sets a fifth threshold value that is greater than the second threshold value, and further determines a magnitude relationship between the absolute value of the position deviation and the fifth threshold value,
In the fine movement positioning control,
By changing the voltage of the drive signal in accordance with the position deviation, the amount of movement of the stage per unit time increases as the position deviation increases, and the absolute value of the position deviation is the fifth threshold value. If the absolute value of the position deviation is smaller than the fifth threshold value, the change amount of the voltage of the drive signal corresponding to the position deviation is made smaller than in the case where the absolute value of the position deviation is larger than the fifth threshold value. apparatus. The stage apparatus according to any one of claims 1 to 6,
The coarse drive unit has an ultrasonic motor, a linear motor or a servo motor,
The fine movement driving unit includes a piezo actuator.

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