JP2002164419A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aligner that is constituted so as to improve a wafer positioning precision. SOLUTION: A drive mechanism 10 of a wafer chuck 3 that sucks and supports the wafer W comprises a drive shaft 11 installed on a lower surface of the wafer chuck 3, a motor 15 coupled via the gears 12, 13 to the drive shaft 11, and an encoder 17 directly adhered to the drive shaft 11. A notch formed at an outer circumferential edge of the wafer W, by the rotation of the wafer W sucked and held by the wafer chuck 3, the edge is image-pickuped with a CCD camera and the position is detected. When the difference between the position of the wafer W and a reference rotation position is measured, a motor 15 is controlled so as to stop at the absolute position of the encoder 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aligner for aligning notches or orientation flats formed on an outer peripheral portion of a wafer or a substrate made of a disk, such as glass, and disposing them at regular positions.

[0002]

2. Description of the Related Art As is well known, a disk-shaped substrate (hereinafter described as a silicon wafer or a wafer) includes:
As a mark indicating a reference rotation position in the circumferential direction of the wafer, an orientation flat cut in a chord shape, a notch cut out in a V-shape or a U-shape, and the like are formed on the outer peripheral portion. When a process such as semiconductor gate formation is performed on a wafer, it is required that the individual wafer be set on the processing stage in a state where the position of the orientation flat or notch always coincides with the reference rotation position. It had been.

On the other hand, a plurality of wafers are usually arranged in a cassette in a random state and arranged vertically. Therefore, if the wafer is taken out of the cassette by the transfer robot and set directly on the processing stage, the wafer is set on the processing stage in a state where the position of the orientation flat or the notch does not coincide with the reference rotation position, and On the other hand, the desired processing cannot be performed.

[0004] Therefore, the wafer taken out of the cassette is carried into an aligner (including an orientation flat aligning device), and the position of the orientation flat or notch is made to coincide with a reference rotation position by the aligner, and then the wafer is set on a processing stage. The method was adopted.

Conventionally, as shown in FIGS. 3 to 5, the aligner M is provided at one end of the machine base 1 with a wafer chuck 3 as a wafer support plate rotatably arranged within the machine base 1. And a sensor chamber 2 having a sensor 5 for detecting the outer peripheral edge of the substrate W. Wafer chuck 3
As shown in FIG. 5, by the conventional drive mechanism 40,
It is arranged so as to be rotatable (θ rotation) with respect to the axis and to be movable in two axes (X axis, Y axis) with respect to the upper surface of the machine base 1.

A drive shaft 41 for rotating the wafer chuck 3 is disposed below the wafer chuck 3.
Has been connected to the motor 42 via gears 44 and 45 via a reduction gear, and has been driven to rotate. Further, an encoder 46 as a position sensor for detecting the rotation angle position of the motor 42 is connected to the motor 42 so that the rotating motor 42
The current position of the rotation angle of the output shaft 43 is detected and the wafer W
The rotation of the motor 42 is controlled in order to correct the position deviation of the wafer from the sensor 5 which has detected the orientation flat position or the notch position.

[0007]

However, in recent years, the wafer W whose position is corrected by the aligner M is positioned at a predetermined position with a high precision with respect to the orientation flat position or the notch position in response to a high precision requirement from the user. I had to be. The rotation drive mechanism 40 of the conventional wafer chuck 3 includes:
A drive shaft 41 for driving the wafer chuck 3 is provided with a motor 42.
Through gears 44 and 45, and the drive shaft 4
Since the current position during one rotation is detected by the encoder 46 connected to the motor 42, the rotation angle position of the output shaft 43 of the motor 42 detected by the encoder 46 is equivalent to the backlash between the gears 44 and 45. This slightly deviates from the rotational angle position of the drive shaft 41. Therefore, the current position of the drive shaft 41 transmitted from the encoder 46 cannot absorb the error due to the backlash of the gears 44 and 45, and the error affects the positioning accuracy of the substrate, and the positioning accuracy is reduced. Could not escape.

An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to provide an aligner that can maintain high accuracy by absorbing an error due to gear backlash.

[0009]

An aligner according to the present invention has the following configuration to solve the above-mentioned problems. That is, a support plate that supports the substrate, a driving unit that rotationally drives the support plate, and a sensor that detects a notch position or an orientation flat position formed on the outer peripheral edge of the substrate, and the notch position of the substrate or An aligner configured to detect an orientation flat position and position the substrate at a set position, wherein the driving unit includes a driving shaft connected to the support plate, the driving shaft and a transmission unit. A drive motor connected through the drive shaft, and position sensor means for sequentially detecting the angular position of the substrate being rotated, wherein the position sensor means is fixedly arranged on the drive shaft. Things.

[0010]

Since the aligner of the present invention is constructed as described above, the wafer chuck holding the substrate is rotated together with the substrate by rotating the drive shaft via the transmission means by driving the motor. You. On this occasion,
The rotational angular position of the drive shaft is detected by position sensor means directly connected to the drive shaft.

On the other hand, the orientation flat position or the notch position of the substrate is detected by a sensor for detecting the outer peripheral edge of the substrate being rotated. Rotate the drive shaft to stop at the set position. At this time, since the position sensor detects the rotational angle position of the rotating drive shaft, the correction angle is controlled by the rotational angle obtained by correcting the drive shaft. The error of the backlash caused by the engagement does not appear. Therefore, the positioning accuracy of the substrate can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. Since the appearance of the aligner of the embodiment is the same as that of FIGS. 3 and 4 described in the section of the related art, the same portions will be described with the same reference numerals. The substrate whose position is to be corrected by the present aligner is a wafer or glass formed in a disk shape, and an orientation flat or a V-shaped notch is formed on the outer peripheral edge of the substrate. The substrate described below will be described as a notched wafer.

The aligner M is, as shown in FIGS.
A machine base 1 formed in a housing shape, a wafer support plate (hereinafter, referred to as a wafer chuck) 3 disposed in the machine base 1, and an outer peripheral portion of a wafer W sucked and held by the wafer chuck 3 And a sensor 5 for detecting one notch. The wafer chuck 3 sucks the wafer W and rotates the wafer W by the driving mechanism 10 arranged in the machine base 1, so that the sensor 5 detects the notch position of the wafer W and detects a deviation from the reference rotation position. Measure.

As shown in FIG. 1, the driving mechanism 10 has a driving shaft 11 mounted on the lower surface of the wafer chuck 3 and a large gear 12 integrally disposed below the driving shaft 11 as shown in FIG. A motor 15 that is drivingly connected via a small gear 13 fixed to an output shaft 16 and an encoder 17 as a position sensor that is externally fitted to the drive shaft 11 below the large gear 12. It is configured.

The wafer chuck 3 is formed in a disk shape.
A suction surface 31 for sucking and holding the lower surface of the wafer W and a suction hole 32 are formed.
Are arranged to face the air passage 112 formed at the bottom.

The drive shaft 11 has a wafer chuck 3 at its upper end.
A mounting portion 111 for fixing to the lower surface of the wafer is formed with a large diameter, an air passage 112 is formed inside, and a lower portion is formed via a rotary joint 18 so that a wafer can be sucked by a vacuum device (not shown). I have. Further, the drive shaft 11 is rotatably supported by a holder 19 attached to the internal frame 1a in order to be rotatably supported by the internal frame 1a in the machine base 1.

The motor 15 may be of any type as long as it is equipped with a reduction gear and emits a pulse. A small gear 13 is fixed to the output shaft 16 of the motor 15 so that the rotation of the motor 15 is
3 is transmitted to the large gear 12 meshed.

The encoder 17 is directly mounted on the lower portion of the drive shaft 11 and always detects the rotational angle position of the rotating drive shaft 11.

The sensor 5 is disposed in the sensor chamber 2 disposed at one end of the machine base 1 so as to protrude upward, and in this embodiment, photographs the outer peripheral edge of the rotated wafer W. A CCD camera is used and is mounted at a lower portion (below the wafer W) in the sensor chamber 2 and arranged so as to be able to photograph the outer peripheral edge of the wafer W. The CCD camera 5 detects the position of one notch formed by photographing the outer peripheral edge of the wafer W while the wafer W held by the wafer chuck 3 is rotating. Is sent to the control unit and subjected to image processing to detect the position. Then, the positional deviation from the reference rotation position set by the control unit is measured. In addition, even if the sensor 5 is not a CCD camera,
A light beam type detection sensor that emits a light beam to detect the position of the notch may be used.

The aligner M configured as described above is
When the wafer W is transferred to the wafer chuck 3 by a robot hand (not shown), a vacuum device (not shown) is driven, and the suction holes 32 of the wafer chuck 3 and the air in the air passage 112 in the drive shaft 11 are sucked. The lower surface of the wafer W is held by suction on the wafer chuck 3. Then, the motor 15 is driven. The rotation of the output shaft 16 decelerated by the reduction gear causes the small gear 13 to rotate.
When the large gear 12 meshed with is rotated, the drive shaft 11 is slowly rotated in one direction.

When the wafer W rotates with respect to the center of rotation of the wafer chuck 3, the CCD camera 5 shoots an image toward the outer peripheral edge of the wafer W, and the image is sent to the control unit at the same time. Then, the position of the notch is detected. The position of the notch is represented by a rotation angle, and an angle corresponding to the correction is calculated by comparing with the set position.

On the other hand, the current rotation angle position of the rotating drive shaft 11 is detected by the encoder 17, and the rotation angle corresponding to the correction detected by the CCD camera 5 is set as an absolute position in the encoder 17. Then, the motor 15 rotates until it reaches the absolute position set by the encoder 17, and stops rotating at the set absolute position. Therefore, drive shaft 1
Since the first corrected position coincides with the set absolute position, the absolute stop position of the drive shaft 11 does not change and stops at the correct position even if backlash occurs between the large gear and the small gear. be able to.

Then, the wafer W whose position has been corrected is transferred by the hand of the robot and conveyed by releasing the suction by the vacuum device.

The drive mechanism shown in FIG. 2 shows another embodiment, and is configured so that the drive of the motor 15 is transmitted to the drive shaft 11 via a pulley and a belt. A small pulley 21 is fixed to the output shaft 16 of the motor 15, while a large pulley 22 is formed on the drive shaft 11, and a belt 2 is provided between the small pulley 21 and the large pulley 22.
3 is wound. An encoder 17 is mounted below the drive shaft 11. Therefore, even if the belt 23 slips between the pulleys 21 and 22 and a rotation error occurs between the output shaft of the motor 15 and the drive shaft 11, the encoder 17 is mounted on the drive shaft 11. Therefore, as described above, the position of the drive shaft 11 is corrected at a normal position.

As described above, the wafer chuck 3 holding the wafer W is driven by the motor 15 to drive the gears 12 and 1.
3, or with the rotation of the drive shaft 11 via the pulleys 21 and 22 and the belt 23, thereby being rotated together with the wafer W. At this time, the rotation angle position of the drive shaft 11 is
Are directly detected by the encoder 17.

On the other hand, the orientation flat position or notch position of the wafer W is detected by the CCD camera 5 for detecting the outer peripheral edge of the rotating wafer W, and if there is a positional deviation from the set reference rotation position, Drive shaft 1 for the correction amount
1 is rotated to stop at the set position. On this occasion,
Since the encoder 17 detects the rotation angle position of the rotating drive shaft 11, the correction angle is controlled by the rotation angle obtained by correcting the drive shaft.
No rotation error appears in the meshing of the gears 12 and 13 between the gears 5, or due to slippage between the pulleys 21 and 22 and the belt 23. Therefore, the positioning accuracy of the wafer W can be improved.

It should be noted that the aligner M of the present invention is not limited to the above-described embodiment, and any other encoder may be used as the position sensor means as long as it can always detect the rotational angle position. May be an optical sensor instead of a CCD camera.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating a rotation drive mechanism of a wafer chuck according to one embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing a rotation drive mechanism of a wafer chuck according to another embodiment of the present invention.

FIG. 3 is a front view showing an aligner equipped with a rotation drive mechanism.

FIG. 4 is a plan view of the same.

FIG. 5 is a partial cross-sectional view showing a conventional wafer chuck rotation drive mechanism.

[Explanation of symbols]

 M: Aligner 1 ... Machine base 3 ... Wafer chuck 5 ... CCD camera 10 ... Rotation drive mechanism 11 ... Drive shaft 12 ... Large gear 13 ... Small gear 15 ... Motor 17 ... Encoder

Claims (1)

[Claims] A substrate that supports the substrate; a driving unit that rotationally drives the substrate; and a sensor that detects a notch position or an orientation flat position formed on an outer peripheral edge of the substrate. An aligner configured to detect a notch position or an orientation flat position, and to position the substrate at a set position, wherein the driving unit includes a driving shaft connected to the support plate, and the driving shaft. A drive motor connected via transmission means; and a position sensor means for sequentially detecting an angular position of the substrate being rotated, wherein the position sensor means is fixedly arranged on the drive shaft. A unique aligner.