JPH09318321A - Length-measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a length-measuring apparatus which enables measuring of a moving value of a stage without being affected by Abbe's error. SOLUTION: This length-measuring apparatus is provided with X and Y stages 12 and 4 movable in the two-dimensional direction to move a sample 2 in an optional direction X and Y linear encoders 6 and 8 optically detect moving values of the stages and a calibrator 20 to electrically calibrate a detection data of the Y linear encoder by using a calibration value calculated on the basis of the moving values of the X and Y stages detected by the linear encoders. When the moving value of the X stage with respect to a reference position is represented by ΔX, the moving value of the Y stage ΔY and the straightness during the movement of the Y stage θ, a calibration value satisfies a value as given by ΔY-(ΔX×sinθ).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a length measuring device for measuring a moving amount of a stage movable in two dimensions.

[0002]

2. Description of the Related Art Conventionally, this type of length measuring device is constructed so that the moving amount of an XY stage movable in two dimensions can be measured by a linear encoder.
Therefore, for example, as shown in FIGS. 1 (a) and 2 (a) to (c), the length measuring device has an X on the fixed base 10.
X stage 12 that can move in any direction, and this X stage 1
Y stage 4 which is movable in the Y direction on which the sample 2 can be mounted, and an X linear encoder 6 which is fixed to a fixed base 10 and detects the amount of movement of the X stage 12.
A Y linear encoder 8 that is fixed to the X stage 12 and detects the amount of movement of the Y stage 4, and the Y stage 4
An observation optical system 18 which is capable of optically observing the sample 2 placed on the fixed base 10 and is fixed to the fixed base 10 is provided.

[0003]

Here, in the above length measuring apparatus, as shown in FIGS. 2A to 2C, the case where the sample 2 is moved in the XY directions (see FIG. 1A) is described. Think In this case, the observation optical system 18 and the X linear encoder 6 are both fixed to the fixed base 10, and the positional relationship thereof is always maintained constant. Therefore, the distance M between the observation point P of the observation optical system 18 and the X linear encoder 6 is always maintained at a constant value. As a result, with respect to the length measurement data in the X direction, the error of Abbe is always a constant value, so that the error amount can be removed by a simple calculation process. Therefore, a constant linearity is always maintained between the movement amount of the sample 2 and the detection data of the X linear encoder 6.

On the other hand, the observation point P of the observation optical system 18
The distance H between the Y linear encoder 8 and the linear encoder 8 for Y varies with the movement of the Y stage 4, so that the Abbe error generated in the length measurement data in the Y direction varies. When the Abbe error fluctuates in this way, there arises a problem that the error amount cannot be removed by a simple arithmetic process.

Specifically, first, an arbitrary reference point S is defined on the Y linear encoder 8. And Y
By moving the stage 4, the observation point P of the observation optical system 18 is positioned at the position of the distance H1 from the reference point S (see FIG. 2A). When the Y stage is moved in the Y direction in this state, the Y stage 4 moves along a predetermined locus due to mechanical errors of the X and Y stages 12 and 4 (see FIG. 2D). ).

Subsequently, the same operation as described above is performed with the observation point P being positioned at positions H2 and H3 from the reference point S (see FIGS. 2B and 2C). Even in this case, the Y stage 4 draws a locus as shown in FIG.

When such an operation is performed, FIG. 2 (d)
As is clear from the locus of the Y stage 4 shown in FIG. 3, when the distance H changes, the Abbe error changes, and the error amount of the length measurement data in the Y direction cannot be removed by a simple calculation process. It was not possible to expect a measurement accuracy higher than this error amount.

The present invention has been made to solve such a problem, and an object thereof is to provide a length measuring device capable of measuring the movement amount of a stage without being affected by the fluctuation state of the Abbe error. To do.

[0009]

In order to achieve such an object, the length measuring apparatus of the present invention comprises stage means movable in two dimensions so as to move a sample in an arbitrary direction. Length measuring means for detecting the amount of movement of the stage means,
A calibration device for electrically calibrating the detection data of the length measuring means using a calibration value calculated based on the amount of movement of the stage means detected by the length measuring means.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A length measuring apparatus according to an embodiment of the present invention will be described below with reference to FIG. In addition,
In the description of this embodiment, the same components as those of the above-described length measuring device are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1A, the length measuring apparatus according to the present embodiment moves the sample 2 in an arbitrary direction.
Length measurement is performed using stage means that can move in two dimensions, length measurement means that detects the amount of movement of this stage means, and a calibration value that is calculated based on the amount of distance between the length measurement means and the stage means. A calibration device 20 for electrically calibrating the detection data of the means.

The stage means includes an X stage 12 movable on the fixed base 10 in the X direction and a Y stage orthogonal to the X direction.
That can move on the X stage 12 in the direction
And a Y stage 4 capable of mounting the.

An X drive unit 14 is connected to the X stage 12, and by driving the X drive unit 14, the X stage 12 is moved to the V guide 10a and the flat guide formed on the fixed base 10. Move in the X direction along 10b. Further, a Y drive device 16 is connected to the Y stage 4, and by driving the Y drive device 16, the Y stage 4 is moved to the V guide 12 a and the flat guide formed on the X stage 12. Move in Y direction along 12b.

The length measuring means is fixed to the fixed base 10 and detects the moving amount of the X stage 12, and the X linear encoder 6 is fixed to the X stage 12 and the Y stage 4.
And a Y linear encoder 8 for detecting the movement amount of the.

These X and Y linear encoders 6,
Although it is possible to apply an optical detection function, a mechanical detection function, and an electrical detection function as the detection function of 8, the linear encoders 6 and 8 for X and Y applied to the present embodiment are As an example, the X and Y stages 12 and 4
Is configured to be able to optically detect the movement amount of the.

In the present embodiment, the X linear encoder 6 is an absolute type linear encoder capable of optically detecting the moving amount and moving direction of the X stage 12 with respect to a preset reference position (not shown). Encoder is applied, while Y linear encoder 8
At the current position (for example, the reference point S shown in FIG. 2).
In this case, an incremental linear encoder capable of optically detecting the movement amount and the movement direction of the Y stage 4 is applied. The absolute type linear encoder may be applied as the Y linear encoder 8.

Next, the operation of this embodiment will be described. While optically observing with the observation optical system 18, X
When moving the Y stages 12 and 4, the distance M between the observation point P of the observation optical system 18 and the X linear encoder 6 is as described above (see FIGS. 2A to 2D). Since it is always maintained at a constant value, the error of the Abbe is always maintained at a constant value for the length measurement data in the X direction.
Therefore, a constant linearity is always maintained between the movement amount of the sample 2 and the detection data of the X linear encoder 6.

On the other hand, the observation point P of the observation optical system 18
The distance H between the Y linear encoder 8 and the Y linear encoder 8 varies with the movement of the Y stage 4, and thus the Abbe error generated in the length measurement data in the Y direction varies. When the Abbe's error fluctuates in this way, the fluctuation error cannot be removed by simple arithmetic processing, so that linearity is maintained between the movement amount of the sample 2 and the detection data of the Y linear encoder 8. There is a problem that it will be difficult to do.

Therefore, the length measuring apparatus according to the present embodiment is provided with the calibration apparatus 20 for the X and Y stages 12 and 4 optically detected by the X and Y linear encoders 6 and 8. The calibration value calculated based on each movement amount is used to electrically calibrate the length measurement data in the Y direction.

Specifically, the movement amount of the X stage 12 with respect to the reference position is ΔX, and the movement amount of the Y stage 4 is Δ.
Assuming that the straightness of the Y and Y stages 4 when moving is θ, the detection data of the Y linear encoder 8 is electrically calibrated using a calibration value of ΔY− (ΔX × sin θ). . The straightness θ uses data measured in advance as a value in the yawing direction of the Y stage 4.

According to the present embodiment, since the variation amount of the Abbe error can be electrically calibrated by the calibration device 20, the linear encoders 6 and 8 for X and Y and the movement amount of the sample 2 can be adjusted. In the meantime, a constant linearity can be maintained. Therefore, for example, it becomes possible to measure the dimensions, coordinates, etc. of the sample 2 with high accuracy.

The reference position is defined by the calibration device 20 for calibrating the variation amount of the Abbe error, and the position can be set arbitrarily.
Further, in the above embodiment, the reference position is defined by applying the absolute type linear encoder 6 for X. However, for example, as shown in FIG. 1B, the reference position of the X stage 12 is detected. By fixing the possible reference position detector 22 to the fixed base 10,
The movement amount ΔX of the X stage 12 with respect to the reference position may be detected. In this case, as the X linear encoder 6, an incremental type linear encoder may be used. It should be noted that such a length measuring device (Fig. 1 (b))
Since the operation and effect of the reference) is the same as that of the above-mentioned embodiment, the description thereof is omitted.

[0023]

According to the present invention, it is possible to provide a length measuring device capable of measuring the amount of movement of the stage without being affected by the fluctuation state of the Abbe error.

[Brief description of drawings]

1A is a perspective view schematically showing a configuration of a length measuring device according to an embodiment of the present invention, and FIG. 1B is a schematic diagram of a configuration of a length measuring device according to a modification of the present invention. FIG.

2A to 2C are distances H1 and H from a reference point S.
2, H3 is an operation explanatory view for explaining an Abbe error generated when the Y stage is moved in a state where the observation point of the observation optical system is positioned at positions H2 and H3.
The figure which shows the movement locus of the Y stage which arises by the error of Abbe, when the operation of (c) is performed.

[Explanation of symbols]

2 ... sample, 4 ... Y stage, 6 ... X linear encoder, 8 ... Y linear encoder, 20 ... calibration device.

Claims (3)

[Claims] 1. A method for moving a sample in an arbitrary direction,
Using stage means movable in two-dimensional directions, length measuring means for detecting the movement amount of the stage means, and calibration values calculated based on the movement amount of the stage means detected by the length measuring means, A length measuring device comprising: a calibration device for electrically correcting the detection data of the length measuring means. 2. The stage means is arranged to move X on a fixed base.
And an Y stage movable on the X stage in a Y direction orthogonal to the X direction, and the length measuring means is fixed to the fixed base and The linear encoder for X which detects the amount of movement of the X stage, and the linear encoder for Y which is fixed to the X stage and detects the amount of movement of the Y stage are provided. Length measuring device. 3. The moving amount of the X stage is ΔX, and the Y is
The calibration value of the calibration device satisfies a value of ΔY− (ΔX × sin θ), where ΔY is a movement amount of the stage and θ is a straightness when the Y stage is moved. The measuring device described.