JPH10144601A - Command value determining method and stage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the swing of a vibration-isolation table by a method wherein a command value to a stage is so determined as to have the swing of the vibration- isolation table at least in one direction among a direction of the stage movement of the vibration-isolation table and a direction opposite to that direction immediately after the transfer start accelerated and have the swing speed zero at the initial position immediately after the acceleration. SOLUTION: When a large thrust command value is given to the driving part 18 of a linear motor when the transfer of a stage 16 is started, a surface plate (vibration- isolation table) 14 is displaced in a direction opposite to the transfer direction of the stage 16 by the counter force against the thrust of the stage 16. After that, the thrust command value is once turned to be zero and, immediately before or after the movement direction of the surface plate 14 is reversed in the same transfer direction of the stage 16, a negative thrust which reduces the acceleration of the stage 16 is applied to the driving part 18. In this case, the swing in a positive direction which is the same as in the direction of the stage 16 is accelerated by the negative thrust and the surface plate 14 is returned to the initial position quickly. With this constitution, the swing of the surface plate 14 can be reduced and the relative displacement between the stage 16 and the surface plate 14 can be reduced, so that the high precision positioning can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining a command value and a stage apparatus, and more particularly, to a relative position between a stage and a vibration isolation table during a settling period when the stage is positioned (or at constant speed control). The present invention relates to a method for determining a command value for a stage in which a change in (or speed) is reduced, and a stage device for controlling a stage by outputting a command value determined in advance by the determining method to a driving means of the stage.

[0002]

2. Description of the Related Art With the advancement of precision equipment such as a step-and-repeat type reduction projection type exposure apparatus, that is, a so-called stepper, a micro-vibration acting on a surface plate (anti-vibration table) from an installation floor is micro-G. There is a need for isolation at the level. Various types of vibration-damping pads for supporting the vibration-isolation table in this type of conventional device, such as a mechanical damper containing a compression coil spring in a damping liquid and a pneumatic damper, are used. Has functions.

A conventional stage apparatus used for precision equipment such as a stepper has a structure as shown in FIG.
In FIG. 8, on a surface plate (vibration isolation table) 84 horizontally supported by a vibration isolation pad 82, a stage 86 that can move on the surface plate 84 in a predetermined direction (the left-right direction in FIG. 8). It is installed. A substrate 90 is placed on the stage 86 via a holding member 88, and the stage 86 is driven by a motor 94 via a feed screw 92. The position of the stage 86 is measured by a laser interferometer 98 via a movable mirror 96, and the control device 100 controls the laser interferometer 9
The position of the stage 86 has been controlled by controlling the rotation of the motor 94 while monitoring the measurement value of No. 8.

In the case of a semiconductor exposure apparatus such as a stepper, especially, as the line width of a pattern becomes finer due to an increase in the density of an integrated circuit, the position of the stage is controlled with higher precision. A stage device using a linear motor has also been used.

[0005]

However, in the above-described conventional stage device, the vibration acting on the surface plate 84 from the installation floor can be prevented by the function of the vibration isolating pad 82, but the stage 86 is moved to the left side of the drawing, for example. When the rightward reaction force acts on the surface plate 84, the vibration isolating pad 82 is compressed,
In response to the extension, the platen 84 and the laser interferometer 98 attached to one end of the platen 84 are swung. This swing acts as a disturbance that changes the distance between the stage 86 and the laser interferometer 98, and deteriorates the positioning performance of the stage 86.

In order to improve such disadvantages, recently, various active vibration isolators for actively canceling the vibration of the surface plate by driving an actuator based on the output of a displacement sensor, an acceleration sensor or the like have been developed. Have been. However, in order to reduce the influence of the movement of the stage by the swing of the surface plate by the active vibration isolator, the above-described components such as the displacement sensor, the acceleration sensor, and the actuator must be added. And the control system becomes complicated.

By the way, the rocking of the surface plate (anti-vibration table) accompanying the movement of the stage is performed by using an air bearing and a linear motor by a device for driving the stage using the above-described feed screw and motor. The device for driving the stage is larger. This is because in the case of the linear motor, there is no mechanical connection between the stage and the surface plate, and a larger reaction force acts on the surface plate.

FIG. 9A shows an example of a command value given to a linear motor driving section in a conventional stage device. As shown in this figure, the command value is set to have a smooth curve so that the stage does not vibrate during the final positioning period (settling period). FIG. 9 (B) shows a temporal change (oscillation) of the displacement of the surface plate at this time.
An example is shown.

The swing of the surface plate as shown in FIG. 9B acts as a disturbance that changes the distance between the stage and the laser interferometer, thereby deteriorating the positioning performance of the stage. In the case of FIG. 9B, the platen is displaced at a maximum of about 90 μm, but the positioning accuracy required for a stage such as a current stepper is on the order of nanometers (nm), and the displacement of the platen at 90000 nm is Obviously, this greatly affects the positioning performance.

Further, when the stage moves at a high acceleration, the reaction force is further increased, so that the swing is further increased, the disturbance is increased, and the positioning performance is further deteriorated.

The present invention has been made under such circumstances, and a method of determining a command value for a stage capable of reducing the swing of a surface plate (anti-vibration table) when the stage is moved at high acceleration. To provide.

Another object of the present invention is to provide a stage device which can position a stage at high speed and with high accuracy without complicating the structure of the device.

[0013]

According to a first aspect of the present invention, there is provided a method for determining a command value for a stage (16) moving on an anti-vibration table (14).
The vibration isolation table (1) immediately after the start of the movement of the stage (16) in consideration of the vibration cycle of the apparatus main body including the vibration isolation table (14).
4) The vibration of the vibration isolation table (14) in at least one of the direction of the stage movement and the opposite direction is accelerated, and immediately after that, the vibration velocity becomes zero at the initial position of the vibration isolation table (14). A command value for the stage is determined such that

When the movement of the stage (16) is controlled based on the command value determined by this determination method, when the movement of the stage (16) starts, the reaction force of the thrust acting on the stage (16) causes The vibration isolation table (14) is mounted on the stage (1
6). Immediately after this, the anti-vibration table (14) swings in the opposite direction (i.e., stage moving direction). The swing of (14) is accelerated, whereby the anti-vibration table (14) returns to the initial position earlier than in the conventional example. Immediately after that, the anti-vibration table (1
The swing speed becomes zero at the initial position of 4). For this reason,
The anti-vibration table (14) stops immediately after swinging for half or one cycle, and returns to the initial position earlier than before, so that the anti-vibration table (14) can be moved even when the stage (16) is moved at high acceleration. ) Can be reduced.

According to a second aspect of the present invention, in the method for determining a command value according to the first aspect, the acceleration component of the command value becomes zero when the swing speed of the vibration isolation table (14) becomes zero. A command value for the stage is determined so that According to this, the command value for the stage is determined so that the acceleration component of the command value becomes zero when the swing speed of the vibration isolation table (14) becomes zero. When the movement of the stage (16) is controlled, servo control of the stage (16) for maintaining the state after positioning or after setting to the target speed becomes unnecessary.

According to a third aspect of the present invention, in the method of determining a command value according to the second aspect, the acceleration component of the command value until the swing speed of the vibration isolation table (14) becomes zero is integrated with time. Then, a command value for the stage is determined so as to reach the target speed. According to this, when the acceleration component of the command value until the swing speed of the vibration isolation table (14) becomes zero is integrated with time, the stage (1
Since the command value for 6) is determined, the target speed can be reliably set at the time when the thrust command is stopped.

According to a fourth aspect of the present invention, there is provided a stage (16) movable in a predetermined moving direction on a vibration isolation table (14) horizontally held via a vibration isolation pad (12). Position measuring means (28) for measuring the position of the stage (16); driving means (18 to 19) for driving the stage (16); and the position measuring means (2).
Control means (20) for controlling the driving means based on the measured value and the target value of (8), and outputting a command value predetermined by the determining method according to any one of claims 1 to 3 to the driving means. And

According to this, the control means (20) outputs to the driving means (18 to 19) a command value determined in advance by the determining method according to any one of claims 1 to 3, and outputs the command value of the stage (16). Since the movement is controlled, the swing of the vibration isolation table (14) can be reduced even when the stage (16) is moved at high acceleration, similarly to the first aspect of the invention. It is not necessary to newly provide an active vibration isolator or the like. Therefore, the stage can be positioned with high speed and high accuracy without complicating the device configuration.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

<< First Embodiment >> A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 schematically shows the configuration of a stage apparatus 10 according to the first embodiment. The stage device 10 is supported by a hydrostatic bearing 15 on a surface plate 14 as a vibration isolation table which is horizontally held through a plurality of (four in this example) vibration isolation pads 12 and moves in a predetermined moving direction ( Stage 1 that can move in the horizontal direction on the paper of FIG. 1)
6, a linear motor drive unit 18 for driving the stage 16 via a linear motor 19 (not shown in FIG. 1, see FIG. 2), and a control device 20 as control means for controlling the linear motor drive unit 18. And In the present embodiment, a driving unit is configured by the linear motor driving unit 18 and the linear motor 19.

As the vibration damping pad 12, a mechanical damper is used here. A sample (eg, a substrate such as a wafer) 24 is suction-held on a stage 16 via a holding member (eg, a wafer holder) 22. Stage 1
A movable mirror 26 having a reflecting surface in a direction perpendicular to the moving direction (a direction perpendicular to the plane of FIG. 1) is provided on the upper surface of one end (the left end in FIG. 1) of the movable mirror 6.
A laser interferometer 28 as a position measuring means is fixed to the upper surface of the extending portion 14a on the upper surface of one end of the surface plate 14 in opposition to the above. The laser interferometer 28 irradiates the movable mirror 26 with a laser beam, receives the reflected light, and
The position of the stage 16 is measured with a resolution of 1 μm.

The measured value of the laser interferometer 28 is
The control device 20 controls the linear motor 19 via the linear motor drive unit 18 based on the measurement value of the laser interferometer 28, thereby
6 is positioned at the target position. At this time,
The control device 20 gives a command value to be described later to the linear motor driving unit 18.

FIG. 2 schematically shows a configuration of a position control system of the stage device 10. Here, a control system operation at the time of positioning the stage 16 will be described with reference to FIG.

The controller 20 calculates the moving distance (or stepping distance) of the stage based on a target position command from a main computer (not shown) and the current position of the stage 16 measured by the laser interferometer 28. A command value determined in advance by a method for determining a command value according to the present invention, which will be described later, based on the calculation result,
Output to The linear motor drive unit 18 drives the linear motor 19 based on the command value. Thus, the stage 16 is moved by the thrust of the linear motor 19.

In this way, the stage 16 is moved by the linear motor drive unit 18 via the linear motor 19 in accordance with the command value. When the stage 16 reaches the target position, the measurement position of the laser interferometer 28 and the target position However, in the case of the present embodiment, immediately after this, the thrust command value becomes zero and the displacement of the surface plate 14 becomes zero as described later, and the stage 16 is quickly positioned at that position ( (See FIGS. 5A to 5C).

FIG. 3 shows an example of the thrust command value determined by the command value determining method according to the present invention used when the stage 16 is moved by 22 mm in the stage apparatus 10 according to the present embodiment. And FIG.
3 shows the time change of the displacement of the surface plate 14 when the thrust command value is output from the control device 20 to the linear motor drive unit 18. Here, the relationship between the movement of the stage 16 and the movement of the base 14 will be described with reference to these figures.

At the start of the movement of the stage 16, when a large thrust command value as indicated by the symbol A in FIG. 3 is given to the linear motor driving unit 18, the platen 14 is moved by the reaction force of the thrust of the stage 16. Is displaced in the direction opposite to the direction of movement. Thereafter, the thrust command value once becomes zero, and the platen 1
Immediately before or immediately after the movement direction of the stage 4 is reversed to become the same direction as the stage 16, a negative thrust as shown by a symbol B in FIG. Given. Here, stage 16
Has a negative thrust means that a force in the same direction as the movement direction of the stage 16 is applied to the surface plate 14. In this case, the platen 14 swings in the same positive direction as the stage 16 as indicated by the reference numeral D in FIG. 4 without being attenuated by the vibration isolation pad 12, but this swing is negative. The platen 14 is accelerated by the thrust, and quickly returns to the initial position. Here, when the base 14 returns to the initial position, the thrust command value has returned to zero (see FIG. 3).

Next, the platen 14 continues swinging in the positive direction until the maximum amplitude point in the positive direction (indicated by a in FIG. 4), and thereafter the direction of the swing becomes the negative direction. When about a quarter cycle has passed from the start of the swing of the surface plate 14 in the negative direction, the surface plate 1
When a thrust command value indicated by reference symbol C in FIG.
When 4 just returns to the initial position (reference numeral b in FIG. 4), its swing speed becomes zero, and the base 14 stops at the initial position b.

Therefore, in the present embodiment, the direction of movement of the surface plate 14, which is a thrust command value as shown in FIG. 3, ie, a large thrust command value (A) at the start of the movement of the stage 16, is reversed in advance. The platen 1 is a negative thrust command value (B) immediately before or immediately after the same direction as the stage 16. The platen 1 is zero when the platen 14 returns to the initial position.
4 starts the swing in the negative direction after passing the maximum amplitude point in the positive direction, and cancels the swing in the negative direction of the platen 14 when less than about a quarter period has passed from the maximum amplitude point a. A function of the thrust command value that satisfies the four requirements of the thrust command value is obtained by simulation in advance and stored in the memory in the control device 20.

At the time of actual positioning of the stage 16, the controller 20 outputs the thrust command values obtained by adjusting the magnitudes of the thrust command values (A) and (B) in accordance with the stepping distance. The data is output to the unit 18 and, as described above, the stage 16 is accurately positioned at the target position when the stage 16 comes to a standstill.

FIGS. 5A to 5C show the above-described thrust command values, the relative displacement of the stage 16 and the surface plate 14 at that time, and the displacement of the surface plate 14 in comparison with the case of the above-described conventional example. Respectively. In these figures, solid lines indicate the case of the present embodiment, and dotted lines indicate the case of the conventional example. As is clear from these figures, it is better to use the thrust command value determined by the command value determination method according to the present invention.
And the relative displacement between the stage 16 and the surface plate 14 during the settling period is reduced.

As described above, according to the present embodiment, when the stage 16 starts to move, the platen 14 swings in the opposite direction to the stage 16 due to the reaction force of the thrust acting on the stage 16. Immediately after, the surface plate 14 is accelerated when it starts swinging in the opposite direction (that is, the moving direction of the stage 16), whereby the surface plate 14 is in the case of the above-described conventional example (see the dotted line in FIG. 5C). It returns to the initial position earlier (see the solid line in FIG. 5C). Next, when the surface plate 14 swings in the opposite direction, its swing speed becomes zero at the initial position,
The swing of the surface plate 14 stops. For this reason, the platen 14 immediately stops after swinging for one cycle (one reciprocation), and when swinging in the moving direction of the stage 16, returns to the initial position quickly, so that the stage 16 is moved at high acceleration. The swing of the surface plate 14 can also be reduced when performing this operation. Accordingly, since the stage 16 does not increase the swing of the surface plate 14, disturbance to the stage 16 can be reduced, and high-speed, high-precision positioning can be performed.

<< Second Embodiment >> Next, a second embodiment of the present invention will be described with reference to FIGS. Here, the same components as those of the device of the above-described first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 6 schematically shows a configuration of a speed control system of the stage 16 device according to the second embodiment. This speed control system is a differentiating circuit 30 for differentiating the measured value (position) of the laser interferometer 28 between the laser interferometer 28 and the controller 20 in the position control system of FIG.
Is characterized by the fact that is inserted. The configuration of the other parts is the same as that of the position control system of FIG. 2, and the configuration of the stage device itself is the same as the device of the first embodiment.

Here, the operation of the control system at the time of positioning the stage 16 will be described with reference to FIG.

The controller 20 converts a target speed command from a main computer (not shown) into speed information from a differentiation circuit 30 obtained by differentiating information on the current position of the stage 16 measured by the laser interferometer 28. Stage 1 based on
6 is calculated, and a thrust command value described later is output to the linear motor drive unit 18 based on the calculation result. The linear motor drive unit 18 drives the linear motor 19 based on the command value. Thereby, the linear motor 19
The stage 16 is moved by the thrust.

In this way, the stage 16 is moved by the linear motor drive unit 18 via the linear motor 19 according to the command value. When the stage 16 reaches the target speed, the measurement speed of the laser interferometer 28 and the target speed However, in the case of the present embodiment, immediately after this, the thrust command value becomes zero and the displacement of the surface plate 14 becomes zero as described later, and the stage 16 is maintained at that speed (FIG. 7).
(A) to (C)).

FIG. 7A shows a command value determined by the command value determining method according to the present invention used when the stage 16 is moved at a constant speed of 400 mm / sec in the stage apparatus according to the present embodiment. FIG. 7B shows the stage 1 when the thrust command value is output from the control device 20 to the linear motor drive unit 18.
6 shows the relative displacement between the platen 6 and the platen 14, and FIG. 7C shows the time change of the displacement of the platen 14. In these figures, the case of the conventional example is shown for comparison. In these figures, solid lines indicate the case of the present embodiment, and dotted lines indicate the case of the conventional example.

The thrust command value shown in FIG. 7A is, as in the case of the above-described first embodiment, taken into consideration of the vibration cycle of the main body including the stage 16 and the surface plate 14, and Immediately after the start of the movement, the swing of the surface plate 14 in at least one of the direction of the stage movement of the surface plate 14 and the opposite direction is accelerated, and immediately thereafter, the oscillation speed becomes zero at the initial position of the surface plate 14. It is determined in advance. The thrust command value is determined so that the time integral (the area of the hatched portion) matches the target speed 400 (mm / sec).

As is apparent from FIG. 7, when the thrust command value determined by the determining method according to the present invention is used, the swing of the surface plate 14 becomes smaller (see FIG. 7C), and the constant speed is obtained. Stage 16 and surface plate 14 during the settling period up to
The change in the relative speed with respect to (b) is small (see FIG. 7B). Therefore, disturbance to the stage 16 can be reduced, and quick constant speed control with a shorter settling time than in the related art can be realized. Further, since the thrust command value is determined so that the time integral is equal to the target speed, there is an advantage that the target speed can be reliably set when the thrust command is stopped. The constant speed control of the present embodiment is performed by scanning the mask and the photosensitive substrate in synchronization with the projection optical system, and projecting and exposing the pattern of the mask onto the photosensitive substrate. It is suitable for control.

[0041]

As described above, according to the method for determining a command value according to the present invention, the swing of the anti-vibration table when the stage is moved at a high acceleration based on the determined command value is reduced. There is an unprecedented excellent effect that it can be performed.

Further, according to the stage apparatus of the present invention, there is an effect that the stage can be positioned with high speed and high accuracy without complicating the apparatus configuration.

[Brief description of the drawings]

FIG. 1 is a front view schematically showing a configuration of a stage device according to a first embodiment.

FIG. 2 is a block diagram schematically showing a configuration of a position control system of the apparatus shown in FIG.

FIG. 3 is a diagram showing an example of a thrust command value used when the stage is moved by a step of 22 mm in the apparatus of FIG. 1;

FIG. 4 is a diagram showing a time change of the displacement of the surface plate when the thrust command value of FIG. 3 is output from the control device to the linear motor driving unit.

5A and 5B are diagrams for explaining the effect of the first embodiment, wherein FIG. 5A shows a thrust command value, FIG. 5B shows a relative displacement between a stage and a surface plate, and FIG. It is a diagram which shows displacement in comparison with the case of a conventional example, respectively.

FIG. 6 is a block diagram schematically illustrating a configuration of a speed control system of a stage device according to a second embodiment.

7A and 7B are diagrams for explaining the effect of the second embodiment, in which FIG. 7A shows an example of a command value used when the stage is moved at a constant speed of 400 mm / sec, and FIG. The relative displacement between the stage and the surface plate when the thrust command value of (A) is output from the device to the linear motor driving unit, and the time change of the displacement of the surface plate when the thrust command value of (A) is output, and FIG. FIG.

FIG. 8 is an explanatory diagram showing a configuration of a conventional stage device.

9A and 9B are diagrams for explaining a problem to be solved by the present invention, wherein FIG. 9A is an example of a command value given to a linear motor driving unit in a conventional stage device, and FIG. It is a diagram which shows the time change of the displacement of a surface plate, respectively.

[Explanation of symbols]

 Reference Signs List 10 Stage device 12 Vibration isolation pad 14 Surface plate (vibration isolation table) 16 Stage 18 Linear motor drive unit 19 Linear motor 20 Control device 28 Laser interferometer

Claims (4)

[Claims] 1. A method for determining a command value for a stage moving on a vibration isolation table, the method comprising: determining vibrations of an apparatus body including the stage and the vibration isolation table; The vibration of the vibration isolation table in at least one of the direction of the stage movement of the table and the opposite direction is accelerated, and immediately after that, the vibration isolation table is moved to the initial position with respect to the stage so that the rocking speed becomes zero at the initial position. A method for determining a command value, comprising determining a command value. 2. A command value for the stage is determined so that an acceleration component of the command value becomes zero when the swing speed of the vibration isolation table becomes zero. How to determine the command value. 3. A command value for said stage is determined so that a target speed is obtained by time-integrating an acceleration component of a command value until the swing speed of said vibration isolation table becomes zero. Method of determining command value described in. 4. A stage movable in a predetermined moving direction on a vibration isolation table held horizontally via a vibration isolation pad; position measuring means for measuring a position of the stage; and driving for driving the stage. Means for controlling the driving means based on a measurement value and a target value of the position measuring means;
A stage device comprising: a control unit that outputs a command value predetermined by the determination method according to any one of claims 1 to 3 to the driving unit.