JPH07253304A - Multi-axial positioning unit and length measuring method therefor - Google Patents

Abstract

PURPOSE:To provide a multi-axial positioning unit which enables highly accurate measurement over the entire range of a large work piece using a small moving mirror. CONSTITUTION:A plurality of length measuring lights 5a-5d for measuring the length in the direction of the X axis independently are so arranged to be almost parallel while a moving mirror 8a is always irradiated with at least one of the length measuring lights even when a stage 9 is moved in the direction of the Y axis. At the same time, at least one length measuring light 6a is provided to measure the movement of the stage in the direction of the Y axis and the length measured value obtained is collated with the positions of the plurality of length measuring lights to recognize which of the length measuring lights is irradiating the moving mirror 8a. The position of the stage in the direction of the X axis is determined by the length measured value based on the length measuring light thus recognized. When the stage 9 is moved in the direction of the Y axis, the length measured value by the length measuring light corresponding to the measurement of the length made before the movement is delivered as initial value of the length measured value of the length measuring light which comes to irradiate the moving mirror 8a simultaneously with the length measuring light involved as the moving mirror 8a moves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a semiconductor exposure apparatus, a three-dimensional coordinate measuring apparatus, and the like, and more particularly to a multi-axis positioning unit for measuring with high accuracy over a wide range.

[0002]

2. Description of the Related Art FIG. 6 shows a configuration example of a conventional high-precision positioning unit used in a semiconductor exposure apparatus, a three-dimensional coordinate measuring machine, or the like. Two reflecting mirrors (hereinafter, referred to as moving mirrors) for reflecting the length measuring light emitted from the laser light source 1 for length measuring, which move together with the movement of the XY moving stage 9, and their reflecting surfaces 8a, 8b is fixed to the XY moving stage 9 so that it is perpendicular to the X axis and the Y axis. Using the reflecting surfaces of the two moving mirrors as reference planes of the coordinate system, the laser interference length measuring device measures the moving amount of the moving stage 9 in each coordinate direction. When two (5a, 5b) length measurement lights are arranged for the X-axis length measurement as shown in this figure, the inclination of the stage 9 can be measured in addition to the movement amount of the stage 9. Therefore, if the reflecting surface of the moving mirror has irregularities, an error occurs between the actual moving amount of the stage 9 and the measured value of the moving amount of the stage 9 by the laser interferometer. The flatness is a very important factor that determines the positioning accuracy of the stage 9. Therefore, in order to improve the positioning accuracy, the flatness of the reflecting surface of the moving mirror should be better than the required positioning accuracy of the stage, or the shape of the reflecting surface of the moving mirror should be measured in advance and the The method of correcting the measured value of is taken.

Further, in the conventional structure of such a positioning unit, the moving mirror always keeps reflecting the length measuring light from the laser interference length measuring device even if the moving stage 9 moves in the X or Y direction. The size of the moving mirror needs to be larger than the movable range of the XY moving stage 9 in each axial direction. That is, in order to place a large work on the moving stage 9 of the positioning unit and position the stage 9 in a wide range, a moving mirror larger than the size of the work is required.

[0004]

For these reasons,
As it becomes necessary to position a stage with a larger work piece with higher precision in applications such as processing and measurement of short-wavelength optical elements, the conventional positioning unit configuration has a large shape with high precision. A moving mirror is required.

However, as the size of the work increases, a large moving mirror is required, the entire large moving mirror must be machined or measured with the required accuracy, and the required shape accuracy must be avoided while avoiding vibration and bending. Difficult to hold in.

The present invention has been made in view of such a conventional problem, and an object thereof is a multi-axis apparatus capable of measuring with high accuracy over the entire range of a large work using a small moving mirror. It is to provide a positioning unit.

[0007]

In order to achieve the above object, a multi-axis positioning unit according to the present invention comprises a moving stage which moves at least in a first axial direction and in a second axial direction substantially perpendicular to the first axial direction. And a first laser interferometric length measuring device having a plurality of length-measuring light beams substantially parallel to each other for measuring the position of the moving stage in the first axis direction, and the first laser interferometric length measuring device fixed to the moving stage. A plurality of length-measuring lights of the laser interference length-measuring device, a first movable mirror that receives at least one length-measuring light that is sequentially different as the movable stage moves in the second axis direction; A second laser interferometric length measuring device having one length measuring light for measuring the position of the movable stage in the second axis direction, and the second laser interferometric length fixed to the movable stage. Measure at least one device Based on the length measurement values of the second movable mirror that constantly receives light and the second laser interference length measuring device, any one of the length measuring values of the first laser interference length measuring device is currently measured by the first movable mirror. It is provided with a calculation means for determining whether or not the light is received and obtaining the length measurement result of the first laser interference length measuring device by the length measurement light.

In this multi-axis positioning unit, at least two of the plurality of length measuring lights of the first laser interference length measuring device irradiate the first movable mirror simultaneously at a specific position of the movable stage. When the two measuring lights adjacent to each other by the first laser interferometric measuring device are simultaneously received at the specific position of the moving stage, the calculating means receives the measuring light previously received. It is preferable to determine the initial value of the length measurement value newly received by the length measurement light according to the length measurement value according to.

[0009]

The principle of the present invention for solving the above problems will be described.

A plurality of measuring light beams from a laser interferometer measuring device for independently measuring the length in the first axis (X axis) direction are substantially parallel to each other, and the moving stage is in the second axis (Y axis) direction. Even if it moves, it is arranged so that at least one of the length measuring lights is always irradiated on the first movable mirror. Further, at least one length measuring light for measuring the stage movement in the second axis direction is provided, and by comparing this length measuring value with the positions of the light beams of the plurality of length measuring light obtained in advance, The length measuring light irradiating the moving mirror of No. 1 is recognized. A length measurement value in the first axis direction is obtained from the recognized length measurement value by the length measurement light.

When the moving stage moves in the direction of the second axis, the length measurement value obtained by the length measuring light measuring the position of the moving mirror before the movement is simultaneously measured with the length measuring light as the first moving mirror moves. It is passed as the initial value of the length measurement value of the length measurement light that has come to illuminate the first movable mirror. By repeating this procedure in accordance with the movement of the movable mirror, it is possible to continuously obtain the measured values of the stage position in the first axis direction even if the first movable mirror moves in the second axis direction by more than that dimension. Becomes

Thus, even if a small moving mirror is used, the measurement can be performed over the entire range of a large work.

[0013]

Embodiments of the multi-axis positioning unit of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of a positioning unit having a wide movement range in the Y-axis direction according to the present invention. This apparatus is composed of a laser interferometer, a moving mirror 8a, 8b, an XY moving stage 9, and an arithmetic unit 10. The laser interferometric length measuring device is the X-Y moving stage X
It is composed of an X-axis laser interferometer for measuring the axial position and a Y-axis laser interferometer for measuring the Y-axis position. The X-axis laser interferometer length measuring apparatus includes a laser light source 1a, beam splitters 2a to 2d, and detectors 3a to 3
d, interferometer units 4a to 4d. The Y-axis laser interferometer length measuring device comprises a laser light source 1b, a detector 3i, and an interferometer unit 4i. The arithmetic unit 10 is shared by the two-axis laser interferometer.

FIG. 9 shows a configuration example of the arithmetic unit 10. The arithmetic unit 10 can be configured by a general electronic computer or a personal computer. That is, as shown in the figure, the detector 3 is used as its main component.
An input / output control device 91 that receives the detection results from (3a to 3d and 3i are collectively referred to), a memory 92 that stores these data and a processing program, and a central processing unit that executes the processing program to process the data ( CPU) 93
And a display device 94 for displaying the processing result on the display screen.

Returning to FIG. 1, in the X-axis laser interferometer, the laser light emitted from the laser light source 1a is distributed to the interferometer units 4a, 4b, 4c, 4d by the beam splitters 2a, 2b, 2c, 2d. It Each laser beam is divided into two by the beam splitter in the interferometer unit (which is composed of a beam splitter and a fixed mirror (not shown)) 4a, 4b, 4c, and 4d, and is directed to the fixed mirror inside, and an XY moving stage. It is divided into light rays directed to the movable mirror 8a fixed to 9. Each of the constituent elements of the X-axis laser interferometric length measuring apparatus emits the length-measuring lights 5a to 5d substantially in parallel, and the length-measuring lights 5a to 5d are always emitted even if the XY moving stage 9 moves in the Y-axis direction. Is arranged so that the movable mirror 8a is irradiated with at least one of them. In the illustrated state, the length measuring light reflected by the movable mirror 8a is again reflected by the interferometer unit 4
a, 4b, the interferometer units 4a, 4b interfere with the light beams from the fixed mirrors inside, and enter the detectors 3a, 3b to measure the distance between the interferometer units 3a, 3b and the movable mirror 8a. To do.

Also in the Y-axis laser interferometer, the light beam (length measuring light 6a) emitted from the laser light source 1b is similarly moved to the interferometer 4i and the movable mirror 8 fixed to the XY moving stage 9.
Measure the distance in b. The position information of the stage 9 in the Y-axis direction is also used to detect which length measurement light of the X-axis length measurement is applied to the movable mirror 8a. That is, this Y-axis length measurement value and the length measurement lights 5a to 5d previously obtained
And the position of the ray of light is compared to identify which length measuring light is irradiating the movable mirror 8a.

In the state shown in FIG. 1, when the stage 9 moves in the Y-axis direction, the length measurement value of the length measuring light 5a, which has measured the position of the movable mirror before the movement, changes with the movement of the movable mirror 8a. At the same time as the length-measuring light 5a, it is passed as a length-measuring value of the length-measuring light 5b, which is emitted from the movable mirror 8a. The reason why it is necessary to "pass" the measured value is as follows. That is, this type of length measuring device measures the amount of relative movement from one position of the stage to another position, and suddenly irradiates the movable mirror 8a as in this example. This is because the stage position at that time cannot be known only by the length measuring light 5b. By repeating this procedure according to the movement of the movable mirror 8a, it becomes possible to continuously obtain the measured values of the stage position in the X-axis direction even if the movable mirror 8a moves in the Y-axis direction by more than the dimension thereof.

These measured values are taken into the arithmetic unit 10 and the position of the stage is obtained by the method described in the previous section.

The procedure of measuring the stage position of the apparatus of FIG. 1 will be described with reference to the flowchart of FIG.

First, the stage 9 is moved to a predetermined initial position, and the length measurement value of each length measurement light is reset (initialized) (71). The amount of movement in the X, Y, and both axis directions from this initial position is obtained by the length measuring device. The following steps 72 to 78 are performed periodically. In step 72, the stage is moved. This stage movement may be performed either automatically or manually. The stage Y coordinate value is calculated by the length measuring light 6a for detecting the stage position in the Y-axis direction (73). Then, based on the obtained stage Y coordinate value, which length measuring light of the length measuring lights 5a to 5d hits the movable mirror 8a is recognized. This recognition is based on the position and size of the movable mirror 8a with respect to the movable mirror 8b, and the length measurement lights 5a to 5a.
Since the position of the 5d in the Y-axis direction is known in advance, it can be easily performed. When only one length measuring light is incident on the movable mirror 8a (75, No), the length measuring value of the impinging beam is set as the X coordinate value of the stage (76), and the process returns to step 72.

In step 75, the length measuring lights are simultaneously set to 2
When it is determined that it is true, the length measurement value of the length measurement light that newly strikes the moving mirror 8a due to the movement of the stage is reset using the length measurement value of the other length measurement light that also strikes the moving mirror 8a at the same time. Yes (77). That is, the length measurement value of the length-measuring light previously hitting the movable mirror 8a is newly set to the movable mirror 8a.
It is passed as the length measurement value of the length measurement light that hits.
At the same time, the measured value is set as the X coordinate value (78). Then, the process returns to step 72. The length measurement value by the length measurement light that newly strikes the movable mirror 8a increases or decreases with the movement of the stage with reference to the passed length measurement value.

The apparatus of FIG. 1 can be used for the purpose of moving the stage to a desired known position or for detecting the position of the stage at an arbitrary unknown position. The same applies to other embodiments described later.

In FIG. 2, by arranging the length-measuring lights 5a to 5d so that two or more length-measuring lights always strike the movable mirror 8a, the XY movement stage 9 rotates about the Z-axis (the amount of tilt). ) Is another embodiment of the present invention having a configuration in which (1) can also be grasped. Although the stage 9 is not designed to rotate about the Z axis, there may be a slight inclination or rattling of the stage 9. In order to perform the length measurement with higher accuracy, it is preferable to detect such minute rotation around the Z axis.

In the example of FIG. 2, let us consider a case where the XY moving stage 9 moves in the Y direction from the side closer to the laser light source b side to the side farther from it. First, the length measuring lights 5a and 5b simultaneously illuminate the movable mirror 8a. As the stage 9 moves, the measuring light 5c moves with the moving mirror 8 at the same time as the measuring lights 5a and 5b.
Start irradiating a. At this time, the measuring lights 5a and 5b
The length measurement value of the length measurement light 5c is determined by extrapolation from the length measurement value of, the distance length of the length measurement light 5a and 5b, and the distance length of the length measurement light 5b and 5c which are obtained in advance. In this extrapolation process, since the movable mirror 8a is small, it is assumed that its reflecting surface has a linear inclination. By repeating this procedure with the movement of the XY moving stage 9 in the Y-axis direction, it is possible to grasp the coordinate value of the XY moving stage 9 as well as the rotation amount around the Z-axis.

The procedure of measuring the stage position in the embodiment of FIG. 2 will be described with reference to the flowchart of FIG.

First, the stage 9 is moved to a predetermined initial position, and the length measurement value of each length measurement light is reset (81).
Then, the stage is moved (82). The stage Y coordinate value is calculated by the length measurement light 6a that detects the stage position in the Y-axis direction (83). Then, based on the obtained stage Y coordinate value, which length measuring light of the length measuring lights 5a to 5h hits the movable mirror 8a is recognized. This recognition can be easily performed because the position and size of the movable mirror 8a with respect to the movable mirror 8b and the positions of the length-measuring lights 5a to 5h in the Y-axis direction are known in advance. When only two length measuring lights hit the moving mirror 8a (85, No), the X coordinate value and the tilt amount of the stage are calculated from the length measuring values of the two hit beams (86), and step 82 Return to. In step 86, as the X coordinate value, a length measurement value of a predetermined one of the two beams (for example, one farther from the laser light source 1a) is obtained. Instead of this, the average value of both may be used.

In step 85, the length measuring lights are simultaneously set to 3
If it is determined that the two books are hit at the same time, the moving mirror 8
The length measurement value of the third length measurement light is calculated by extrapolation using the length measurement values of the two length measurement lights that hit a at the same time, and the length measurement light newly hits the movable mirror 8a by the movement of the stage. The length measurement value of is reset with the calculated value (87). That is,
The length measurement value obtained by the length measurement light hitting the movable mirror 8a first is transferred as the length measurement value of the length measurement light newly hit on the movable mirror 8a. At the same time, the X coordinate value and the tilt amount of the stage are obtained by using the predetermined two of the length measurement values of the three length measurement lights that strike the movable mirror 8a (8
8). The X coordinate value in this case is also obtained in the same manner as in step 86. Then, the process returns to step 82. The length measurement value by the length measurement light that newly strikes the movable mirror 8a increases or decreases with the movement of the stage with reference to the passed length measurement value.

FIG. 3 shows a third embodiment of the present invention in which the measuring light of the XY moving stage and the arrangement of the moving mirror have a wide moving range in both the X and Y axes and can grasp the amount of rotation about the Z axis. It is a top view of an example. In this embodiment, at least one of the length measuring lights 5a to 5c strikes the movable mirror 8a at the same time, and at least two of the length measuring lights 6a to 6e strikes the movable mirror 8b at the same time. Here is an example of long light. Which of the measuring lights 6a to 6e is currently hitting the movable mirror 8b can be determined by the stage position in the X-axis direction at that time, and which of the measuring lights 5a to 5c is currently measuring light. It can be determined whether or not is hitting the movable mirror 8a based on the stage position in the Y-axis direction at that time. In this case, X,
The length measurement values are passed on both Y axes.

FIGS. 4 and 5 show the fourth embodiment of the present invention capable of grasping a wide range of movement in the X, Y, and Z axis directions and the amount of rotation around the three axes.
6A and 6B are a perspective view and a plan view of a schematic view of the arrangement of the movable mirror and the length-measuring light of the positioning unit according to the embodiment.

In this case, in order to grasp the rotation of the XY moving stage about the X and Y axes, the movable mirror 8c for measuring the Z-axis direction always has three or more measuring lights (on the movable mirror 8c). The measuring lights 7a to 7o are arranged so that three or more measuring lights whose irradiation points are not on a straight line are irradiated. Length measuring light 7a
Which length measuring light is currently shining on the movable mirror 8c out of 7 to 7o depends on the stage position in the X and Y axis directions at that time. For the measuring lights 7a-7o,
The length measurement values are transferred in the same manner as in the above embodiment. In this embodiment, the amount of tilt of the movable mirror 8c about the X and Y axes can also be obtained.

[0032]

According to the present invention, in the two-dimensional or more positioning unit using the laser interferometer, the size of the movable mirror of each axis is equal to or larger than the distance of the measuring light arranged parallel to the measurement coordinate axis. It only needs to be provided and does not depend on the size of the work. For this reason, it is not necessary to prepare a large moving mirror for a large work as in the conventional case, and a small moving mirror that can be processed with higher accuracy and that is less deformed during holding can be used.
As a result, it becomes possible to measure a large workpiece with high accuracy over the entire range. Furthermore, by making the moving mirror small, the mass of the moving stage can be reduced, and the positioning control of the moving stage can be made easier.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a third embodiment of the present invention.

FIG. 4 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional positioning unit.

7 is a flowchart showing a procedure for measuring the stage position in the embodiment of FIG.

FIG. 8 is a flowchart showing a procedure for measuring the stage position in the embodiment of FIG.

FIG. 9 is a block diagram showing a configuration example of an arithmetic unit in each embodiment.

[Explanation of symbols]

1, 1a, 1b: Laser light source 2a, 2b, 2c, 2d: Beam splitter 3a, 3b, 3c, 3d, 3i: Detector 4a, 4b, 4c, 4d, 4i: Interferometer unit consisting of fixed mirror and beam splitter 5a, 5b, 5c, 5d: Length measuring light for X-axis length measurement 6a, 6b, 6c, 6d, 6e: Length measuring light for Y-axis length measurement 7a to 7o: Length measuring light for Z-axis length measurement 8a , 8b, 8c: moving mirror 9: XY moving stage 10: arithmetic unit

Claims (6)

[Claims] 1. A moving stage that moves in at least a first axis direction and a second axis direction that is substantially perpendicular to the first axis direction, and a plurality of length measurement lights that are substantially parallel to each other, and in the first axis direction. A first laser interferometric length measuring device for measuring the position of the moving stage; and a plurality of length measuring lights of the first laser interferometric length measuring device fixed to the moving stage, of the moving stage, At least one that is sequentially different with the movement in the second axis direction
A first movable mirror for receiving a length measuring light beam; a second laser interference measuring device having at least one length measuring light beam for measuring the position of the movable stage in the second axis direction; A second movable mirror which is fixed to the movable stage and constantly receives at least one length-measuring light of the second laser interferometric length measuring device; and a second movable mirror based on the length measurement value of the second laser interferometric length measuring device. , It is determined which length measurement light of the first laser interference length measurement device is currently being received by the first movable mirror, and the length measurement result of the first laser interference length measurement device is determined by the length measurement light. A multi-axis positioning unit, comprising: 2. A plurality of length measurement lights of the first laser interferometer length measuring device are arranged such that at least two adjacent length measurement lights irradiate the first movable mirror at a specific position of the movable stage, When the arithmetic unit receives, at a specific position of the moving stage, two adjacent measuring lights of the first laser interferometric measuring device at the same time, the calculating unit obtains a length measurement value of the measuring light received previously. The initial value of the length measurement value by the newly received length measurement light is determined.
The described multi-axis positioning unit. 3. The multiaxial positioning according to claim 1, wherein the dimension of the first movable mirror in the second axial direction is shorter than the movable distance of the movable stage in the second axial direction. unit. 4. The at least three length measuring lights are provided as a plurality of length measuring lights of the first laser interference length measuring device, and at least two adjacent ones are always the first length measuring light regardless of the position of the moving stage. It is arranged to irradiate one moving mirror at the same time, and the arithmetic means constantly irradiates the first moving mirror.
The tilt amount of the moving stage is obtained based on the length measurement value of the length measuring light of the book, and the first moving mirror is adjacent to the first laser interference length measuring device at a specific position of the moving stage. When the length measurement light of a book is received at the same time, the initial value of the length measurement value of the newly received length measurement light is determined by the length measurement value of the two length measurement light received previously. The multi-axis positioning unit described in 1, 2, or 3. 5. A first and a second axis which move at least in a first axis direction and a second axis direction substantially perpendicular to the first axis direction and reflect length measurement light in the first axis direction and the second axis direction, respectively. A moving stage having a moving mirror, and a first measuring position of the moving stage in the first axis direction and the second axis direction, respectively.
And a second laser interferometer length measuring device in a multi-axis positioning unit, wherein two or more units are arranged substantially parallel to each other to independently measure the moving stage position along the first axis direction. Place the measuring light of
At that time, at any position within the moving range of the moving stage, at least one of the two or more length-measuring lights always irradiates the reflecting surface of the moving mirror along the second axis direction. The at least one length measuring light is arranged to measure the position of the moving stage,
At any position within the moving range of the moving stage, the at least one length measuring light always irradiates the reflecting surface of the moving mirror, and at the start of length measurement, the position of the moving stage is moved to the initial position. At the same time, the length measurement values in the first axis and second axis directions are initialized, the length measurement values in the second axis direction are obtained as the moving stage moves, and the obtained measurement values in the second axis direction are obtained. Based on the length value, which of the two or more length-measuring lights that are substantially parallel is detected by the movable mirror is detected, and the detected length-measuring light detects the direction of the first axis. Is obtained, and the position of the movable stage is obtained from the obtained measured values in each direction. 6. A plurality of length-measuring lights of the two or more length-measuring lights arranged substantially in parallel are simultaneously applied to the movable mirror along with the movement of the moving stage in the second axis direction. ,
The length measurement value obtained by the length measurement light previously emitted to the first movable mirror is transferred as an initial value of the length measurement value obtained by the length measurement light newly emitted to the first movable mirror. The positioning method in the multi-axis positioning unit according to claim 5.