JPH05217837A - X-y movable table - Google Patents

Abstract

PURPOSE:To reduce the size and weight of an X table and of a Y table, and eventually the entire X-Y movable table. CONSTITUTION:In an X-Y movable table 1 which has a Y table 3 which moves in the Y direction and an X table which moves on the Y table in the X direction to cross at right angles with the X direction and which is designed to measure the location of each of the tables 3 and 5 using a laser interferometer 12, laser mirrors 11a and 11b of the laser interferometer 12 are located at the side of the tables 3 and 5 along the moving direction of the tables 3 and 5 and interferometers 9a, 9b and 9c are so located on the side edges of the X table 5 which face the laser mirrors 11a and 11b as to face the laser mirrors 11a and 11b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an X table and a Y table that move in a direction orthogonal to each other on a plane, and measures the position of each table using a laser interferometer. For example, the present invention relates to an optimum XY moving table used as a wafer table system of an X-ray exposure apparatus.

[0002]

2. Description of the Related Art An X-ray exposure apparatus is being developed as an apparatus used when manufacturing a VLSI. This X
The line exposure apparatus includes a mask table system that holds a mask on which a pattern is drawn and determines the position and orientation of the mask,
A wafer table system that holds a wafer on which a pattern on the mask is transferred and determines the position and orientation of the wafer, an alignment optical system that is used for aligning the mask and the wafer and setting an interval, and exchanges the mask and the wafer. A loader, a chamber for securing an exposure atmosphere, and the like are generally provided.

The pattern drawn on the mask is transferred onto the wafer by the X-ray as the exposure light, but the pattern on the mask is usually drawn for only one chip. Therefore, in order to expose the entire surface of the wafer, it is necessary to move the wafer in parallel in the X and Y directions on mutually orthogonal planes by the wafer table system.

A large wafer has a diameter of 8 inches, and in this case, in order to perform transfer on the entire surface of the wafer, the X and Y strokes of the wafer table system are 200 m.
It should be about m. Therefore, a laser interferometer is used to measure the position in this range on the order of microns or less.

Further, the wafer table system generally makes minute rotations in the X and Y planes (θ direction) due to problems such as assembly accuracy (yawing error). When this yawing error occurs in the wafer table system, the wafer also slightly rotates in the θ direction, and the error in the peripheral portion cannot be ignored. Therefore, it becomes necessary to correct this yawing error. For example, the distances at two points in the X direction on the wafer table system are obtained, and the displacement in the θ direction is measured from the difference in the distances.

That is, in this type of wafer table system, in order to measure the position in the XY direction and the position in the θ direction, one point in the Y direction on the wafer table system and two points in the X direction.
It is common practice to measure the position of a point and its position using a laser interferometer.

Hereinafter, a conventional general XY moving table used as the above-mentioned wafer table system will be described.
This will be described with reference to FIG.

That is, the XY moving table 1 has a rectangular Y table 3 movable in the Y direction along a pair of rails 2 extending parallel to the Y direction, and a Y table 3 parallel to the X direction on the Y table 3. And a rectangular X table 5 movable in the X direction along a pair of rails 4 laid on the
The wafer W is held on the X table 5.

Outside the XY moving table 1, a laser head 6 for generating a laser beam, benders 7a and 7b for bending the optical path of the laser beam, and a laser beam are located between the benders 7a and 7b. Beam splitter 8a,
8b, and interferometers 9a, 9b, 9c for branching the laser light into reference light and measurement light to secure the optical path of the reference light.
And detectors 10a, 10 for detecting the reference light and the measurement light
b and 10c are provided. On the other hand, the measuring light of the laser light is reflected at the side end portions of the two sides of the X table 5 which moves on the Y table 3 in the X direction and which face the interferometers 9a, 9b, 9c and are orthogonal to each other. A laser interferometer 12 is configured by fixing laser mirrors 11a and 11b returning the measurement light to the ferrometers 9a, 9b and 9c.

The laser interferometer 12 measures the positions of the X table 5 and the Y table 3, and thus the position of the wafer W, which will be described below.

That is, the laser light emitted from the laser head 6 is bent by the bender 7a, and the beam is split by the beam splitter 8a.
It is split into two laser beams. One of the branched laser lights is guided to the interferometer 9a, where it is branched into reference light and measurement light. This reference light is repeatedly reflected inside the interferometer 9a and is guided to the detector 10a. Further, the measurement light exits the interferometer 9a, reaches the laser mirror 11a held on the X table 5, is reflected here, returns to the interferometer 9a again, reaches the laser mirror 11a again, and is reflected. After that, it is guided to the detector 10a through the interferometer 9a.

Here, the optical path until the reference light is incident on the detector 10a is constant regardless of the position of the Y table 3, and the optical path until the measurement light is incident on the detector 10a is reflected by the measurement light. The Y table 3 depends on the position of the laser mirror 11a on the X table 5 in the Y direction.
It contains the location information of.

Therefore, by comparing the two, the distance y between the laser mirror 11a and the interferometer 9a in the Y direction at the point A where the measurement light is reflected by the laser mirror 11a held on the X table 5, and thus the Y table. Three positions can be measured.

On the other hand, the other of the laser beams split by the beam splitter 8a is further split by another beam splitter 8b.
It is split into two laser beams. One of the branched laser lights is directly bent, and the other is bent by another bender 7b to be guided to the interferometers 9b and 9c, respectively.

The respective laser lights guided to the interferometers 9b and 9c are branched into the reference light and the measuring light in the same manner as described above, and the measuring light makes two round trips between the laser mirror 11b and the reference light. Are interferometers 9b, 9
After repeating reflection in c, the detector 10
b, 10c.

Then, each of the detectors 10b and 10c
The distance x1 between the laser mirror 11b in the X direction and the interferometers 9b, 9c at points B and C at which the laser light is reflected on the laser mirror 11b held on the X table 5 by the reference light and the measurement light guided to , X2, and by extension, the position of the X table 5 at two locations can be measured.

Based on the positions (distances) x1 and x2 of the two points in the X direction and the position (distance) y of the one point in the Y direction thus obtained on the X table 5, the XY moving table 1 and, by extension, the wafer W. The position in the X and Y directions and the position in the θ direction can be obtained.

[0018]

However, in the conventional general XY moving table, it is necessary to hold two laser mirrors by the X table moving on the Y table, and especially, the X and Y strokes are large. If this is done, the length of this laser mirror will increase in proportion to this stroke, so that the size of this X table, and correspondingly, the size of the Y table, will also become considerably large, resulting in XY movement. The entire table becomes a heavy load. If the entire XY moving table becomes a heavy object in this way, there is a problem that not only the natural frequency decreases but also positioning takes time.

That is, for example, in the conventional example shown in FIG. 2, the length of the laser mirror 11a held by the X table 5 needs to be at least X strokes. Further, the laser mirror 11b needs to have a length corresponding to the Y stroke plus the distance between the two points B and C where the laser light hits. Therefore, for example, the X and Y strokes of the XY moving table 1 are 300 mm, and the distance between the two points B and C is 60 mm.
mm, in practice, the laser mirror 11a is 320 mm,
The laser mirror 11b needs to have a length of about 380 mm at a minimum. Therefore, such a large laser mirror 11
In order to hold a and 11b, the X table 5 and further the Y table 3 correspondingly become large, and the XY moving table 1 as a whole becomes large and becomes a heavy object.

In view of the above, it is an object of the present invention to provide an X table and a Y table, and further, an XY moving table which is compact and lightweight.

[0021]

In order to achieve the above object, an XY moving table according to the present invention has an X table and a Y table that move in a direction orthogonal to each other on a plane, and a laser interferometer and In an XY moving table configured to measure the position of each table by using a laser mirror of a laser interferometer, the laser mirror is arranged laterally of each table along each moving direction. In addition, the interferometer of the laser interferometer is held on the side edge of the X table facing the laser mirrors.

[0022]

According to the present invention constructed as described above, the laser disposed on the side of the X table and the Y table from the interferometer of the laser interferometer held on the side edge of the X table moving on the Y table. By receiving the reflected light of the laser light emitted toward the laser mirror of the interferometer with the interferometer, the position of each table can be reliably measured, which makes it necessary to hold the laser mirror on the X table. This makes it possible to reduce the size and, in turn, the size and weight of the entire XY moving table.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Note that this embodiment shows the one used in the wafer table system of the X-ray exposure apparatus, as in the above-mentioned conventional example, and the same members as those in FIG.

That is, the XY moving table 1 has a rectangular Y table 3 movable in the Y direction along a pair of rails 2 extending in parallel with the Y direction, and the Y table 3 is parallel to the X direction on the Y table 3. And a rectangular X table 5 movable in the X direction along a pair of rails 4 laid on the
The wafer W is held on the X table 5.

A laser head 6 for generating a laser beam and a bender 7a for guiding the laser beam to bend the optical path are provided outside the XY moving table 1, and a corner portion of the Y table 3 is provided with A bender 7b, which bends the optical path of the laser light, extends from the corner of the X-table 5 to both side edges which are orthogonal to each other, and beam splitters 8a and 8b for splitting the laser light and split the laser light into reference light and measurement light. Interferometer 9 that secures the optical path of the reference light by
a, 9b, 9c and detectors 10a, 10b, 10c for detecting the reference light and the measurement light are arranged.

On the other hand, on the side of the X table 5, along this moving direction, a laser mirror 11a which reflects the measurement light of the laser light and returns the measurement light to the interferometer 9a.
However, the measuring light of the laser light is reflected to the side of the Y table 3 along this moving direction by the interferometer 9b,
A laser interferometer 12 is configured by arranging laser mirrors 11b for returning the measurement light to 9c, respectively.

The laser interferometer 12 measures the positions of the X table 5 and the Y table 3, and thus the position of the wafer W, which will be described below.

That is, the laser light emitted from the laser head 6 is guided to a predetermined position via the benders 7a and 7b, and split into two laser lights by the beam splitter 8a. One of the branched laser lights is guided to the interferometer 9b, and is branched here to the reference light and the measurement light. This reference light is repeatedly reflected inside the interferometer 9b and is guided to the detector 10b. In addition, the measurement light exits the interferometer 9b and reaches the laser mirror 11b disposed on the side of the X table 5, is reflected here, returns to the interferometer 9b, and reaches the laser mirror 11b again. After being reflected by the detector 10 through the interferometer 9b.
guided by b.

Here, the optical path until the reference light is incident on the detector 10b is constant regardless of the position of the X table 5, and the measuring light is reflected on the optical path until the measuring light is incident on the detector 10b. It depends on the distance in the X direction to the laser mirror 11b, and includes the position information of the X table 5.

Therefore, by comparing the two, it is possible to measure the distance x1 between the interferometer 9b and the laser mirror 11b in the X direction, and thus the first position of the X table 5.

On the other hand, the other of the laser beams split by the beam splitter 8a is further split by another beam splitter 8b.
The laser light is branched into two laser lights, and the respective branched laser lights are guided to interferometers 9a and 9c, respectively.

The laser lights guided to the interferometers 9a and 9c are split into the reference light and the measuring light in the same manner as described above, and the measuring light includes the interferometer 9a, the laser mirror 11a and the interferometer 9c. After two round trips to and from the laser mirror 11b, the reference light is repeatedly reflected in the interferometers 9a and 9c and then guided to the detectors 10a and 10c, respectively.

Then, each of the detectors 10a and 10c
By comparing the reference light and measurement light guided to
Direction interferometer 9a and laser mirror 11a
It is possible to measure the distance y from the Y table 5, and the position of the Y table 5, the distance x2 between the interferometer 9c and the laser mirror 11b in the X direction, and the second position of the X table 5.

Based on the positions (distances) x1 and x2 of the two points in the X direction and the position (distance) y of the one point in the Y direction on the X table 5 thus obtained, the XY moving table 1 The position in the X and Y directions and the position in the θ direction can be obtained.

Thus, the X moving on the Y table 3 is moved.
Interferometer 9 held on the side edge of the table 5
The interferometers 9a, 9b and 9c reflect the reflected light of the laser light (measurement light) emitted from a, 9b and 9c toward the laser mirrors 11a and 11b arranged on the sides of the X table 5 and the Y table 3. By receiving it, the positions of the tables 3 and 5 can be measured with certainty, which eliminates the need to hold the laser mirrors 11a and 11b on the X table 5, thus reducing the size of the table and the overall size of the XY moving table. The weight can be reduced.

In the above embodiment, the XY moving table is used in the wafer table system of the X-ray exposure apparatus to measure the displacement in the θ direction, but the position in the X and Y directions ( When measuring only the distance), it is sufficient to measure the position of the X table 5 at one position without measuring at two positions.

[0037]

Since the present invention has the above-mentioned structure,
It is possible to reliably measure the position of each table without holding the laser mirror, whose length increases in proportion to the X and Y strokes, on the X table. This makes it possible to determine the sizes of the X table and the Y table. The size of the mirror can be made as small as possible regardless of the size of the mirror, and the overall size and weight of the XY moving table can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention applied to a wafer table system of an X-ray exposure apparatus.

FIG. 2 is a schematic diagram showing a conventional example.

[Explanation of symbols]

 1 XY moving table 3 Y table 5 X table 6 Laser head 7a, 7b Vendor 8a, 8b Boom splitter 9a, 9b, 9c Interferometer 10a, 10b, 10c Detector 11a, 11b Laser mirror 12 Laser interferometer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // G01B 7/34 Z 9106-2F

Claims (1)

[Claims] 1. A Y-table that moves in the Y-direction and an X-table that moves on the Y-table in an X-direction orthogonal to the moving direction, and the position of each table is measured using a laser interferometer. In the XY moving table thus arranged, the laser mirror of the laser interferometer is arranged laterally of each table along each moving direction, and on the side edge of the X table facing each laser mirror. An XY in which the interferometer of the laser interferometer is arranged toward each of the facing laser mirrors.
Moving table.