JPH0527818A - Positioning deciding method and positioning controller using the same - Google Patents

Abstract

PURPOSE:To improve the throughput without deteriorating the accuracy of a positioning controller by considering that a moving object has moved to its target position when a state where the mean value and the maximum value of the difference between the position of the moving object and its target position are kept under each reference level lasts for a fixed period. CONSTITUTION:The difference between the present position and the target position of an XY stage 101 is sampled for a fixed period and the average value of the difference is obtained. Then the difference of the largest absolute value is obtained among those sampled differences between the present and target positions of the stage 101. When the mean absolute value is smaller than a reference level for decision, it is confirmed whether the absolute value of the largest difference is smaller than a reference level for decision or not. If so, the value of a built-in counter is counted up by one. A fact whether the value of the counter is equal to a decided level or not is confirmed in order to confirm whether a state where the mean value and the largest value of the difference between the measured position and the target position of a moving object are less than each prescribed level lasts for a fixed period or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device for a moving body, and more particularly to a positioning control device for a moving body that requires high-speed and highly accurate positioning of an XY stage or the like.

[0002]

2. Description of the Related Art Conventionally, a positioning control device, such as an XY stage for a reduction projection exposure apparatus, which requires high-speed and highly accurate positioning, moves a moving body from the step of moving the moving body to the next step. You need to make sure that the move is complete.

As a determination method for confirming the movement of the moving body, the position after the moving body is moved is measured, and the difference between the measured position and a predetermined target position is within a predetermined determination reference value. The positioning determination method (first determination method) is considered to be regarded as positioning completion if time continues. In the positioning control device, after the completion of positioning by such a determination method is confirmed, the process proceeds to the next step.

In such a positioning control device,
Since only the vibration amplitude was used as the confirmation means for the completion of positioning regardless of the frequency of the residual vibration, there were the following drawbacks.

Since the XY stage and the like of the reduction projection exposure apparatus require high-speed and highly accurate positioning, and the position measurement accuracy is extremely high, it is a moving body (XY stage).
Not only the vibration of itself but also the vibration of an external actuator (pulse motor etc.) is detected. These external vibrations have a high frequency, and if they have an amplitude up to a certain level, they do not affect the printing performance of the reduction projection exposure apparatus.

If the positioning is judged by the difference between the measured position and the target position being within a predetermined judgment reference value for a predetermined time, the positioning must be performed if the amplitude of vibration of any frequency does not fall below a certain value. However, since the positioning is not completed even with the high frequency vibration that does not affect the printing performance of the reduction projection exposure apparatus, the loss time becomes large, which is not preferable for increasing the throughput of the apparatus.

FIG. 5 is a diagram showing a state of positioning after the movement of the XY stage by the first determination method.

In FIG. 5, the horizontal axis represents time t,
The vertical axis shows the difference from the target position of the XY stage. Although the positioning waveform shown in FIG. 3 has a high-frequency vibration as a disturbance, this vibration does not affect the printing performance of the reduction projection exposure apparatus. However, in the first determination method, since the difference between the measured position of the XY stage and the target position does not fall within the determination reference ± T, the positioning is not completed even though the printing is possible.

As a positioning determination method for preventing the above problems, the difference between the measured position of the moving body and the target position is averaged, and the average value is compared with a predetermined determination condition to affect the device performance. There is a method (second determination method) of deciding the completion of positioning by ignoring high-frequency vibration that does not give

The second determination method is to increase the throughput of the apparatus by ignoring the high frequency vibration which does not affect the printing performance of the reduction projection exposure apparatus, but only the average value is determined. Since the judgment condition is used, vibrations above a certain frequency are ignored regardless of the amplitude, and positioning is completed. Therefore, reduction projection exposure is performed even when there is an external vibration having a large amplitude that affects the printing performance of the reduction projection exposure apparatus, resulting in poor resolution of the exposure pattern, resulting in poor accuracy. Resulting in.

FIG. 6 is a view showing a state of positioning after the movement of the XY stage by the second judgment method.

FIG. 7 shows an average of the waveforms of FIG. 6 according to the second determination method, in which high-frequency vibration having a large amplitude is present as a disturbance. In this way, no matter how large the amplitude is, it will pass the determination condition of the second determination method, resulting in poor accuracy of the device.

[0013]

Of the above-mentioned conventional positioning determination methods, the first determination method for performing positioning determination when the difference between the measured position and the target position falls within a predetermined determination reference value for a predetermined time period. However, since the positioning is not completed even with high-frequency vibration that does not affect the device, there is a problem that the loss time becomes large and the throughput of the device is low.

By averaging the difference between the measured position of the moving body and the target position and comparing the average value with a predetermined judgment condition, the positioning is completed by ignoring the high frequency vibration which does not affect the device performance. In the second determination method for determining, the problem is that the positioning is determined to be completed even when there is an external vibration with a large amplitude that affects the device performance, and the accuracy of the device deteriorates. is there.

The present invention has been made in view of the problems of the above-described conventional technique, and it is an object of the present invention to realize a positioning determination method capable of improving the throughput without deteriorating the accuracy of the apparatus. To aim.

[0016]

A positioning determination method according to the present invention is a positioning determination method performed by a positioning control device to confirm whether or not a movement of a moving body to a target position has been completed. Of the moving body to the target position when the average value and the maximum value of the difference between the position of the moving body and the target position within a predetermined value are equal to or less than a predetermined reference value for a certain period of time. Is considered complete.

The positioning control device of the present invention is a positioning control device for moving a moving body to a target position, and a position value measuring means for measuring the position of the moving body and a target for setting a target position for moving the moving body. A position setter and control means for controlling each operation of the positioning control device are provided, and the control means is the position of the moving body measured by the position measuring means and the target position set in the target position setter. The average value and the maximum value of the difference between the average value and the maximum value within a predetermined period, and the target of the moving body when the average value and the maximum value are equal to or less than a predetermined reference value for a certain period continues. It is assumed that the movement to the position is completed and moves to the next step.

In this case, the average value and the maximum value of the difference between the position of the moving body measured by the position measuring means and the target position set in the target position setting device within a predetermined period are calculated and output to the control device. A value calculator and a maximum value holder may be provided respectively.

[0019]

The target position of the moving body when the average value and the maximum value of the difference between the position of the moving body and the target position within a predetermined period are below a predetermined reference value for a certain period of time The move to is considered complete.

The disturbance of the frequency determined by the length of the above-mentioned predetermined period is averaged and compared with the reference value, so it is ignored and it is determined that the movement is completed. At this time, since the maximum value within the predetermined period is compared with the reference value, it is not determined that the movement is completed when there is vibration of an amplitude that affects the device performance.

[0021]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of a control circuit of an XY stage positioning apparatus according to an embodiment of the present invention.

The XY stage 101 is a driving motor 10
2 is driven by the XY stage 101.
The motor 102 and the motor 102 are coupled by, for example, a ball screw. The motor 102 is rotated by the output of the driver 103. Further, a tacho generator 104 for measuring the number of revolutions is added to the motor 102, and the output of the tacho generator 104 is fed back to the driver 103 for speed control. XY stage 10
The position 1 is input with the output signal of the length measuring instrument 105, and is measured by the current position counter 106 which constitutes a position measuring means together with the length measuring instrument 105. A laser interferometer was used as the length measuring device 105. Current position counter 106
The measured value by the CPU is sent via the main bus 108 to the CPU 107 which is the control means, and the CPU 107 receives the X value.
The position of the Y stage 101 is recognized.

The target position setter 109 is the XY stage 10.
1 latches the target position to be moved, and CP
U107 displays X according to the input to the external input device (not shown).
The movement target position of the Y stage 101 is set. Differentiator 1
10 is the current position counter 106 and the target position set value 109
The difference is output. This difference output is used as a position servo amplifier 1 feedback signal for position servo control.
11 is input. The output of the position servo amplifier 111 is input to the driver 103, whereby the XY stage 10
1 is driven by position servo control. The positioning completion signal 112 output by the CPU 107 is output when the CPU 107 determines that the positioning of the XY stage 101 is completed based on the value of the current position counter 106 and the movement target position. The external circuit receives the positioning completion signal. (Not shown) recognizes that the movement of the XY stage 101 is completed.

The CPU 107 determines whether or not the positioning is completed by checking whether the average value and the maximum value of the difference between the measured position of the moving body and the target position within a predetermined period continue for a certain period or less. This is done by doing.

FIG. 2 is a flow chart showing a method of determining completion of positioning of the XY stage 101 by the CPU 107.

When the movement of the XY stage 101N is started, the CPU 107 clears the value n of the built-in counter (step S200). Next, for a certain period S ₁ , X
The difference between the current position of the Y stage 101 and the target position is sampled, and the averaged value is obtained (step S20).
1). Subsequently, in the section of the constant period S ₁ for which the average value is obtained in step S201, the largest absolute value b of the sampled difference between the current position and the target position is obtained (step S202).

Next, the absolute value of the average value a is the judgment reference value T ₁
It is confirmed whether or not it is the following (step S203), and if it is the judgment reference value T ₁ or more, step S2 at the time of starting the positioning judgment.
Return to 00. If the absolute value of the average value a is less than or equal to the determination reference value T ₁ , then the absolute value of the maximum difference b is determined as the determination reference value T 1.
It is confirmed whether it is ₂ or less (step S204), and if it is the determination reference value T ₂ or more, step S at the time of starting the positioning determination.
Return to 200. When the absolute value of the average value a is less than or equal to the determination reference value T ₁ and the absolute value of the maximum difference value b is less than or equal to the determination reference value T ₂ , the value n of the built-in counter is incremented by 1 (step S205).

Next, it is confirmed whether the value n of the built-in counter is equal to a predetermined judgment value N (step S206). By confirming this, it is confirmed whether the state in which the average value and the maximum value of the difference between the measured position of the moving body and the target position are equal to or less than the predetermined values continues for a certain period. If the value n of the built-in counter is not equal to the predetermined determination value N, the procedure returns to step S201 for obtaining the average value a of the difference between the measured position of the moving body and the target position, and the above is performed until n becomes equal to N. Each step S2
Repeat 01 to S205. When n = N, it is determined that the positioning is completed, and the process ends.

However, in the above flow chart,
When the vibration frequency that does not affect the device performance is f ₁ or more, the amplitude is K or less, and the typical vibration frequency of the XY stage is f ₂ , S ₁ , N, and T ₂ satisfy the following conditions. It should be set to satisfy.

[0031]

[Equation 1] Fig. 3 shows XY with a large amplitude disturbance vibration after the movement is completed.
FIG. 6 is a diagram showing how typical positioning of the stage 101 is determined.

[0032] In the figure, the horizontal axis represents time, the target position and the difference of the XY stage are taken on the vertical axis, the maximum difference between the value a obtained by averaging, S ₁ segment every time S ₁ a waveform shown in FIG. 6 Values b and are shown. The value of the counter n is shown below the waveform. The determination value N = 4.

This positioning waveform has a vibration of high frequency f ₁ as a disturbance. Vibration of this frequency has amplitude K
The following items do not affect the printing performance of the reduction projection exposure apparatus. As shown in FIG. 3, the value of the counter n is counted up when | a | <T ₁ and | b | <T ₂ , and when the judgment value becomes equal to 4, the positioning is completed.

As described above, according to this embodiment, S ₁ , N,
By setting T ₂ as follows, when the disturbance vibration of the high frequency f _{1 is} the vibration of the amplitude K or more that affects the performance of the device, it is not detected and the positioning is not completed. _When the disturbance vibration _{1 is} a vibration having an amplitude of K or less that does not affect the performance of the apparatus, it can be ignored and a typical vibration frequency f ₂ of the XY stage can be captured.

FIG. 4 is a block diagram of a control circuit of an XY stage positioning apparatus according to another embodiment of the present invention.

In this embodiment, an average value calculator 413 and a maximum value holder 414 connected to the CPU 107 via the main bus 108 are provided in addition to the output of the target position setter 109 in addition to the embodiment shown in FIG. It was done. Since other configurations are the same as those shown in FIG. 1, the same reference numerals as those in FIG.

In this embodiment, the average value of the difference between the current position and the target position is averaged by the average value calculator 413. The maximum value holding unit 414 holds the maximum value of the difference between the current position and the target position within a certain section. CPU1
Based on the average value and the maximum value obtained by these, 07 determines the positioning completion according to the flowchart of FIG. As described above, by calculating the average value and performing the peak hold by the average value calculator 413 and the maximum value hold device 414, the CPU 1
It is possible to reduce the load of 07, control a plurality of axes simultaneously, and perform high-speed sampling.

[0038]

Since the present invention is constructed as described above, it has the following effects.

In the method according to the first aspect, high-frequency vibration having an amplitude that does not affect the device performance is ignored,
If there is a high-frequency vibration with a large amplitude that affects the performance of the device, it is not determined that the moving body is completed, so that there is an effect that the throughput of the entire device can be improved without adversely affecting the accuracy of the device.

According to the second aspect, there is an effect that the positioning control device having the above-mentioned effects can be realized.

According to the third aspect, in addition to the above effects, there is an effect that it is possible to realize a positioning control device which operates at high speed.

[Brief description of drawings]

FIG. 1 is a block diagram of a control circuit of an XY stage positioning apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the determination method of the present invention, and is a flowchart showing a method of determining the positioning completion of the XY stage 101 by the CPU 107 in FIG.

FIG. 3 is a diagram for explaining a determination method of the present invention, and is a diagram showing a typical determination state of positioning of the XY stage 101 on which disturbance vibration having a large amplitude is placed after completion of movement.

FIG. 4 is a block diagram of a control circuit of an XY stage positioning apparatus according to another embodiment of the present invention.

FIG. 5 is a diagram for explaining a conventional determination method.

FIG. 6 is a diagram for explaining a conventional determination method.

FIG. 7 is a diagram for explaining a conventional determination method.

[Explanation of symbols]

101 XY stage 102 motor 103 driver 104 Tacho Generator 105 length measuring machine 106 current position counter 107 CPU 108 Main Bus 109 Target position setter 110 differentiator 111 position servo amplifier 112 Positioning detection signal 413 Average value calculator 414 Maximum value hold device S200-S206 steps

Claims (3)

[Claims] 1. A positioning determination method performed by a positioning control device for confirming whether or not movement of a moving body to a target position has been completed, wherein the position of the moving body and the target position within a predetermined period are set. Positioning determination method characterized in that the movement of the moving body to the target position is considered to be completed when the average value and the maximum value of the differences between the two are below a predetermined reference value for a certain period of time. . 2. A positioning control device for moving a moving body to a target position, a position value measuring means for measuring the position of the moving body, a target position setting device for setting a target position for moving the moving body, and positioning. A control unit for controlling each operation of the control device, wherein the control unit has a predetermined period of difference between the position of the moving body measured by the position measuring unit and the target position set in the target position setting device. Calculate the average value and maximum value within
When the state in which the average value and the maximum value are equal to or less than a predetermined reference value continues for a certain period, the movement of the moving body to the target position is considered to be completed and the next step is performed. Positioning control device. 3. The positioning control device according to claim 2, wherein the difference between the position of the moving body measured by the position measuring means and the target position set by the target position setter is an average value and a maximum value within a predetermined period. An average value calculator and a maximum value hold device for obtaining a value and outputting the value to the control device are respectively provided, and the control means has a state in which the average value and the maximum value are equal to or less than a predetermined reference value. The positioning control device is characterized in that the movement of the moving body to the target position is considered to be completed and the process is moved to the next step when is continued for a certain period.