JP2003110004A - Position correcting method in conveying wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position correcting device upon conveying a wafer in which the wafer can be aligned without using a highly accurate robot in an aligner on which an XY table is not mounted. SOLUTION: When the aligner 1 and the robot 10 are set at prescribed positions, an angular alignment of a measuring wafer is carried out by the aligner 1. Then, the position is determined to be a reference position and the moving loci of a hand 14 are respectively measured in accordance with a plurality of times of movements having different moving distances in the extending direction of the hand 14, the swing direction of the hand 14, or the Y-axis direction of the robot 10. When the wafer W to be worked is conveyed, an amount of movement including an amount of each correction based on the measured results is supplied to command the robot 10 to move the hand 14 to a proper position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position correction method in wafer transfer that can hold a wafer at a normal position when aligning the wafer with an aligner having no XY table.

[0002]

2. Description of the Related Art Generally, an orientation flat or notch for detecting a position is formed at one or two positions on the edge of a wafer. Since the wafers are placed randomly in the transferred cassette, the orientation flat or notch is positioned at the proper position when performing various types of processing on the wafer. Must be done in. A device for aligning the wafer, that is, for aligning the wafer and for centering the wafer is generally called an aligner. After the wafer is held by the holding shaft, the orientation flat or notch position is adjusted by rotating the wafer half or once. Based on the detection result, the holding shaft is rotated by a predetermined angle to align the wafer at a regular position, and the holding shaft is moved in the XY directions to center the wafer.

However, since mounting the XY table on the aligner is complicated and costly,
There was also a need for an aligner that has a simple structure and is manufactured at a low cost. Therefore, in the case of an aligner in which an XY table is not installed, the angle of the wafer can be adjusted, but the centering of the wafer cannot be performed by the aligner. Therefore, by correcting the position of the robot hand, the wafer of the aligner can be replaced. I was aligning.

[0004]

However, in order for the robot to extend and contract or rotate the hand, a small gap for sliding at each joint is required, so that a mechanical operation including many joints is required. The element had a large total clearance, which caused a mechanical error. This mechanical error has been a factor that reduces the accuracy of hand conveyance.

That is, when the robot hand is instructed by the robot controller to extend, the arms 12 and 13 connected to the hand 14 rotate to linearly move the hand 14, as shown in FIG. 6 is instructed to move to a predetermined position, but actually, as shown in FIG. 6, the hand 14 draws a wave-like trajectory due to a mechanical error and is displaced from the normal position. Has been moved to a position.
For this reason, when the wafer W whose angle is adjusted is taken out by the hand 14, the hand 14 cannot hold the central position of the wafer W, and the carrying accuracy is lowered.

Therefore, when the robot hand moves in the X-axis and Y-axis directions without installing the XY table on the aligner, a high-precision robot is required. In addition to the occurrence of variations, it is extremely difficult to move the hand 14 in a straight line when the hand 14 is moved, because the gap cannot be made zero in the sliding portion. Therefore, it is necessary to correct the position of the wafer W by the hand 14 of the robot 10 in order to improve the alignment accuracy of the transferred wafer W.

The present invention solves the above-mentioned problems, and when a wafer is transferred by a robot to an aligner on which an XY table is not installed, the alignment accuracy can be improved by correcting the position of the robot hand. An object of the present invention is to provide a position correction method for transportation.

[0008]

In order to solve the above-mentioned problems, the position correcting method in wafer transfer according to the present invention is carried out as follows. That is,
A method for correcting a position in a wafer transfer for correcting a mechanical error in a hand movement of a robot during a wafer transfer, the aligner including a holding means for rotating the wafer and a detecting means for detecting an edge of the wafer. When,
When a robot equipped with a hand that grips and conveys a wafer is installed at a predetermined position, the measurement wafer is set on the aligner and the measurement wafer is angled, and then the angle is adjusted. By measuring the movement wafer of the hand by gripping the measurement wafer with the hand and moving it to the measurement position with reference to the position, the hand is transferred based on the measurement result when the processing wafer is transferred. Is corrected to a regular position.

Further, the angled measuring wafer is moved by the hand along the extension length direction of the hand, and the angle of the measuring wafer is adjusted at the moved position. It is more preferable that the movement trajectory of the hand can be measured by sequentially changing the movement distance of the hand and repeating the movement distance.

Further, the angle-adjusted measuring wafer is rotated along the turning angle of the hand, and the angle of the measuring wafer is adjusted at the position where the hand is rotated. The movement locus of the hand may be measured by sequentially changing the turning angle of the above and repeating.

Further, the angled measuring wafer is moved by the robot along the direction orthogonal to the extension direction of the hand, and the measuring wafer is angled at the moved position. The movement trajectory of the hand may be measured by sequentially changing the movement distance of the robot and repeating the movement distance.

[0012]

According to the position correcting method in wafer transfer of the present invention, when the aligner and the robot are installed at a predetermined position, the angle of the measuring wafer is adjusted and the position is moved to the measuring position as a reference. Since the movement trajectory is measured, the tendency of mechanical error of the hand can be confirmed between the reference position of the wafer and the measurement position. Then, by correcting the error based on the measurement result at the time of transporting the processing wafer, the hand can take out and transport the angled processing wafer at a regular position. Therefore, XY as an aligner
Even if the table is not provided, the center position of the wafer can be taken out at the normal position by correcting the position of the hand, so that the alignment accuracy can be improved without providing a highly accurate robot.

Specifically, the measurement of the movement trajectory is performed by three methods.

One is a method of measuring the movement locus by sequentially changing the extension distance from the reference position with respect to the extension direction of the hand with reference to the center position of the angle-matched wafer. According to this, when the measurement wafer is re-angled at the position moved along the extension direction of the hand, the center position of the measurement wafer at the moved position is measured, and the center position of the measurement wafer is actually moved with respect to the reference position. The position shift can be measured. By changing the moving distance little by little and measuring each position, a moving locus can be drawn. On the basis of this measurement, when the processing wafer is transferred, by correcting the positional deviation in the extension direction of the hand, the hand can correct the positional deviation in the extension direction.

The second method is a method of measuring the movement locus by sequentially changing the turning angle from the reference position with respect to the turning direction of the hand with the center position of the angle-matched wafer as a reference. According to this, when the measurement wafer is re-angled at the position moved along the turning angle of the hand, the center position of the measurement wafer at the moved position is measured, and the center position of the measurement wafer is measured with respect to the reference position. The position shift can be measured. By changing the turning angle little by little and measuring each position, the movement trajectory can be drawn. On the basis of this measurement, when the wafer for processing is transferred, the hand can correct the positional deviation with respect to the turning angle by correcting the positional deviation with respect to the turning of the hand.

Thirdly, with reference to the center position of the wafer whose angle is adjusted, the robot is moved sequentially from the reference position while changing the moving distance with respect to the direction orthogonal to the extension direction of the hand, and the movement locus is obtained. It is a method of measuring. According to this, when the measurement wafer is re-aligned at the position moved along the direction orthogonal to the extension direction of the hand, the center position of the measurement wafer at the moved position is measured, and the center position of the measurement wafer is measured with respect to the reference position. It is possible to measure the positional deviation due to the actual movement. By changing the movement distance of the robot little by little and measuring each position, the movement locus can be drawn. Based on this measurement, when the processing wafer is transferred, the robot corrects the positional deviation in the direction orthogonal to the extending direction of the hand by correcting the positional deviation in the direction orthogonal to the extending direction of the hand. be able to.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. The position correction method in the wafer transfer of the embodiment is to preliminarily measure a mechanical error generated in the robot hand when the aligner and the robot are installed at predetermined positions. When the wafer is transferred, the hand is corrected so that the wafer can be held at the regular position.

As shown in FIG. 1, the aligner 1 is provided with a holding shaft 2 for adsorbing and rotating the wafer W, and a detector 3 for detecting an edge of the wafer W rotated by the holding shaft 2. The position of the orientation flat or the notch of the wafer W can be arranged at a set regular angle.
On the other hand, the robot 10 arranged to face the aligner 1
Is a pair of arms 1 rotatably supported on the machine base 11.
2 and 13 and a hand 14 that is rotatably supported by the arm 13 and can hold the wafer W. The pair of arms 12 and 13 are driven by a motor (not shown) arranged in the machine base 11. In order to move the hand 14 in a stretchable manner, it can be bent and stretched.

When the aligner 1 and the robot 10 are installed at predetermined positions, the robot 10 drives the hand 14 to extend so that the wafer W for measurement is taken out from the cassette (not shown) and the holding shaft 2 of the aligner 1 is taken out. Then, the tendency of the mechanical error generated when the hand 14 is moved is measured.

When performing this measurement, first, the aligner 1
By rotating the holding shaft 2 of the
By detecting the position of the orientation flat or notch by projecting a light beam onto the edge of the wafer W, the center position of the wafer W held by the holding shaft 2 can be measured. The wafer W is rotated to the predetermined position, and the angle of the wafer W is adjusted. Then, as shown in FIG. 2, the central position of the wafer W in this state is set as P0 and set as a reference position.

With respect to the wafer W whose angle has been adjusted, the hand 14 once returned to the machine base 11 side of the robot 10 extends toward the center position of the wafer W again to hold the wafer W. become. If no mechanical error occurs when the hand 14 moves, as shown in FIG. 5, the hand 14 is extended by the commanded distance by the signal commanded by the controller of the robot 10 and set. It moves to the regular position (reference position). However, a mechanical error occurs in the robot 10 and the hand 1
The movement of No. 4 is obstructed, and the wave is extended as instructed while waving as shown in FIG. And this hand 1
The stopped position of 4 moves to a position deviated from the reference position P0.

The mechanical error of the hand 14 is caused by the robot 10.
It occurs due to the gathering of the respective parts in the connection part between the machine base 11 and the arm 12, the connection part between the arm 12 and the arm 13, and the connection part between the arm 13 and the hand 14.
Next, as shown in FIGS. 2 to 4, the movement trajectory of the hand 14 is measured.

The mechanical error in the robot 10 is caused by the hand 1
4 has a defective extension length (X-axis direction), a defective turning angle (θ angle) of the hand 14, and a defective length (Y-axis) orthogonal to the extending direction of the hand 14, and therefore the hand 14 The movement locus of will be measured in three stages.

First, the measurement is performed in the X-axis direction of the hand 14, and the angle-adjusted measurement wafer W (wafer W at the reference position P0) is extended and sucked by the hand 14. Then, from the reference position P0, for example, the measurement wafer W is transferred to a position extended by 1 mm in the X-axis direction and transferred onto the holding shaft 2 of the aligner 1. When the holding shaft 2 holding the measurement wafer W makes one rotation, the detection unit 3 causes the measurement wafer W to move.
Edge is detected and its center position P1 is measured. Subsequently, the measurement wafer W is transferred to the position extended by 2 mm in the X-axis direction from the reference position P0, and the center position P2 of the measurement wafer W is measured. As described above, when Pn is sequentially measured in the extension direction and the reduction direction along the X-axis direction, the movement locus as shown in FIG. 2 is drawn.

Therefore, when the actual processing wafer is transferred, if the difference between the set movement amount of the X-axis and the reference position P0 is obtained, the position of the difference is determined along the graph of FIG. By calculating, the X-axis correction amount can be calculated, and when the processing wafer on the aligner 1 is taken out by the hand 14, if the movement amount including the correction amount is set in advance, the processing wafer can be obtained. It can be taken out and transported almost accurately.

The second measurement is with respect to the turning angle of the hand 14, and the hand 14 extends and adsorbs the angled measurement wafer W (wafer W at the reference position P0). Then, from the reference position P0, for example, in FIG.
The measurement wafer W is transferred to the position where the hand 14 is rotated 1 deg counterclockwise from the rotation center position of the arm 12 and transferred onto the holding shaft 2 of the aligner 1. When the holding shaft 2 holding the measurement wafer W makes one revolution, the detector 3 detects the edge of the measurement wafer W and measures the center position P′1 thereof, as shown in FIG. Then, the measurement wafer W is transferred to the position rotated 2 degrees counterclockwise from the reference position P0 in the same manner as above, and the center position P′2 of the measurement wafer W is measured. As described above, when the measurement is sequentially performed up to P'n in the counterclockwise direction and the clockwise direction along the X-axis direction, the movement trajectory as shown in FIG. 3 is drawn.

Therefore, when the actual turning wafer is transferred, if the difference between the set turning angle and the reference position P0 is obtained, the position of the difference is obtained along the graph of FIG. The correction amount of the turning angle θ can be calculated, and when the processing wafer on the aligner 1 is taken out by the hand 14, if the transfer turning angle including the correction amount is set in advance, the processing wafer can be more easily processed. It can be taken out and transported at an accurate position.

The third measurement is a measurement with respect to the movement of the hand 14 in the Y-axis direction, and the hand 14 extends and adsorbs the angle-matched measurement wafer W (wafer W at the reference position P0). . Then, from the reference position P0, for example, a direction orthogonal to the extension direction (Y of the robot 10).
The wafer W for measurement is conveyed to a position extended by 1 mm (axial movement) and transferred to the holding shaft 2 of the aligner 1. When the holding shaft 2 holding the measurement wafer W makes one revolution, the detection unit 3 detects the edge of the wafer W and measures the center position P ″ 1. Subsequently, the robot 10 moves from the reference position P0 in the Y-axis direction. In the same position as above, the measurement wafer W
The center position P2 of the wafer W for measurement is conveyed and measured. As described above, when P ″ n is sequentially measured in the extension direction and the reduction direction along the Y-axis direction, the movement locus as shown in FIG. 4 is drawn.

Therefore, when the actual movement wafer is transferred, if the difference between the set movement amount of the robot 10 on the Y axis with respect to the reference position P0 is obtained, the difference is obtained along the graph of FIG. By calculating the position of, the Y-axis correction amount can be calculated.
When the upper processing wafer is taken out, if the movement amount including the correction amount is set in advance, the processing wafer can be taken out and conveyed at a substantially accurate position.

As a result, the aligner 1 and the robot 1
When 0 is set at the predetermined position, each measurement is performed, and if correction is performed based on the measurement result, as shown in FIG.
The hand 14 can move the processing wafer W whose angle is adjusted by the aligner from the position indicated by the chain double-dashed line to the regular position indicated by the solid line, and can transfer the processing wafer W.

As described above, according to the position correcting method in the wafer transfer of the embodiment, when the aligner 1 and the robot 10 are installed at predetermined positions, the angle of the measuring wafer W is adjusted and the position is used as a reference. As a result, the movement locus is drawn to draw the movement locus, so that the tendency of mechanical error of the hand can be confirmed between the reference position P0 where the measurement wafer W is aligned and the measurement position. . Then, the error is corrected based on the measurement result when the processing wafer is transferred, so that the hand 14 can take out and transfer the processing wafer whose angle has been adjusted at a regular position. Therefore, even if the aligner 1 does not have an XY table, the center position of the processing wafer W can be taken out by the correction of the robot 10, so that a robot with improved alignment accuracy can be provided without providing a highly accurate robot. can do.

Then, the above measurement is carried out by moving the hand 14 a plurality of times with different movement amounts in the extension direction of the hand 14.
The movement is performed a plurality of times with different turning angles with respect to the turning direction of the robot 10 and a plurality of times with different movement amounts with respect to the Y-axis direction of the robot 10 to draw a movement locus. Then, when the processing wafer is transported, if the processing wafer is corrected based on the measurement result, the processing wafer can be more accurately moved to the set regular position.

The hand 14 of the robot 10 is not connected by a pair of arms 12 and 13 like a link as shown in the figure, but the hand itself moves linearly with respect to the machine base. The same applies to robots.

[Brief description of drawings]

FIG. 1 is a plan view showing an arrangement state of an aligner and a robot.

FIG. 2 is a diagram showing a measurement result of a movement trajectory of a hand in an extension direction.

FIG. 3 is a diagram showing a measurement result of a movement trajectory of a hand 14 in a turning direction.

FIG. 4 is a diagram showing a measurement result of a movement trajectory of a robot in a Y-axis direction.

FIG. 5 is a plan view showing a state in which the hand extends in an ideal state.

FIG. 6 is a plan view showing a state in which the hand extends with a mechanical error.

[Explanation of symbols]

1 ... Aligner 2 ... holding shaft 3 ... Detector 10 ... Robot 14 ... Hand W ... Wafer

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Claims (4)

[Claims] 1. A method for correcting a position in a wafer transfer for correcting a mechanical error in a hand movement of a robot during a wafer transfer, comprising a holding means for rotating the wafer and a detecting means for detecting an edge of the wafer. And a robot having a hand for gripping and transporting the wafer are set at predetermined positions, the measurement wafer is set on the aligner and the angle of the measurement wafer is adjusted. After that, the angle-matched measurement wafer is grasped by the hand with respect to the position and moved to the measurement position, and the movement trajectory of the hand is measured. A position correction method in wafer transfer, wherein the hand is corrected and moved to a regular position based on the result. 2. The measuring wafer whose angle is adjusted,
By moving the hand along the direction of the extension length of the hand and adjusting the angle of the measurement wafer at the moved position, by repeating this while sequentially changing the moving distance of the hand, 2. The position correction method in wafer transfer according to claim 1, wherein the movement locus of is measured. 3. The angle-matched wafer for measurement,
By rotating the hand along the turning angle of the hand and adjusting the angle of the measurement wafer at the position where the hand is rotated, by repeating this while sequentially changing the turning angle of the hand, The position correction method in wafer transfer according to claim 1 or 2, wherein a movement locus is measured. 4. The angle-matched measurement wafer,
By moving the robot along the direction orthogonal to the extension direction of the hand and performing angle adjustment of the measurement wafer at the moved position, by repeating this while sequentially changing the moving distance of the robot,
4. The position correction method in wafer transfer according to claim 1, wherein the movement trajectory of the hand is measured.