JPH10173031A - Circular substrate positioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circular substrate positioner capable of accurately detecting a notch to position, using an optical means. SOLUTION: A notch wafer 1 having a notch 1a is held on a rotary table with its center aligned to the rotary center of the table. The edge of the wafer 1 irradiated uniformly by an illuminating means 3 to form a clear image of the edge of the wafer 1 on photo detectors SPDs 5a, 5b having slits through an imaging lens 4. The two SPDs 5a, 5b are disposed with the lengths of their mutually parallel slits set in a radial direction of the wafer 1. A controller 7 monitors the outputs of the SPDs 5a, 5b to control a motor 8 to stop the rotary table 2 at such a position that the output signals of both SPDs are higher than those provided when the other edge image than the notch 1a is formed on the SPDs, and equal to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circular substrate positioning device for positioning a circular substrate having a notch.
In particular, the present invention relates to a circular substrate positioning apparatus which can accurately position optically and is suitable for positioning a semiconductor wafer having a notch such as a notch or an orientation flat.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional example of a positioning device for positioning a notch wafer. In this device, first, the notch 1a is roughly positioned. That is, the notch wafer 1
Is mounted on the rotary table 2 and rotated by the notch detecting means for detecting the beam emitted from the light emitting device 9 by the light receiving device 10. The motor control unit 15 controls the motor control unit 15 so that the beam 11 passes through the notch 1 a. By controlling the motor 8, the notch 1
The rotary table 2 is stopped by detecting the rough position a.

[0003] Next, after the two reference pins 13 move in the direction of the arrow, the pressing pin 12 also moves in the direction of the arrow.
Further, the pressing pin 12 is pressed against the notch 1 a of the notch wafer 1 by the spring 14. When the positioning of the notch wafer 1 is completed in this way, the pressing pins 12 and the reference pins 13 are retracted to the original positions in this order, and a series of operations is completed.

In addition to the above-described mechanical positioning device, for example, in Japanese Patent Application Laid-Open No. 3-159255, a light emitting portion and a light receiving portion are arranged near the periphery of a circular substrate, and the notch position of the circular substrate is set. Positioning is performed by optical detection.
In this device, the light receiving section is configured by two rectangular light receiving elements arranged in parallel. The outputs from the two light receiving elements are calculated, and the notch position is detected from the difference signal between them. I have.

[0005]

However, in the conventional mechanical positioning device shown in FIG. 4, since pins are pressed against the edge of the wafer, problems such as generation of dust and damage to the wafer are caused. There is also a problem that the number of parts constituting the apparatus is large and complicated.

Further, in the above positioning apparatus disclosed in Japanese Patent Application Laid-Open No. 3-159255, there is a problem that the edge image of the wafer incident on the light receiving element is not clear, and the detection accuracy of the notch position is low. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to provide a circular substrate positioning apparatus capable of optically detecting and positioning a notch with high accuracy.

[0008]

In order to achieve the above object, a circular substrate positioning apparatus according to the present invention holds a circular substrate in a state where the center of the circular substrate having a notch coincides with the center of rotation. A rotary table for rotating the rotary table, a control unit for controlling the rotation of the rotary table, an illuminating unit for illuminating an edge of the circular substrate, and an imaging unit for forming an edge image of the circular substrate by the illumination of the illuminating unit. Image means;
And two light receiving elements having slits arranged at positions where an edge image of the circular substrate is formed by the image forming means.

Since the edge image of the circular substrate obtained by the illumination of the illumination means is formed by the imaging means, and the formed sharp edge image of the profile is received by the light receiving element through the slit. The rotational position of the circular substrate can be accurately detected. Further, since the two light receiving elements are provided, an accurate rotation position of the circular substrate can be determined by comparing output signals of both light receiving elements.

Further, according to the present invention, in the above, the two light receiving elements each have the same slit, and the circular shape of the circular substrate has an edge image of the notch formed by the imaging means. Slits are arranged at intervals equal to or less than the width or length in the circumferential direction, and the longitudinal direction of the slits is arranged in the radial direction of the circular substrate.

As described above, the slits of the same shape of the two light receiving elements are formed at intervals equal to or less than the circumferential width or length of the cutout image formed by the image forming means, and the longitudinal direction of the slit is circular. If it is arranged in the radial direction of the substrate, the detection sensitivity to the notch at the edge of the circular substrate is good. Further, the output signals of the two light receiving elements are controlled to a position where the output signal is larger than the output signal when an edge image other than the cutout portion is formed on the light receiving elements and the output signals of the two light receiving elements are the same. If the positioning is performed by the means, the notch of the circular substrate has a symmetrical shape in which the center position in the circumferential direction of the circular substrate is usually cut out most, so that it is surely positioned at a predetermined position. A circular substrate can be positioned.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the circular substrate positioning apparatus of the present invention. In FIG. 1, reference numeral 1 denotes a notch wafer having a notch 1a, and the notch wafer 1 is suction-held on a rotary table 2. The turntable 2 is driven to rotate by a motor 8, and the drive of the motor 8 is controlled by a control unit 7. Notch wafer 1
The illumination means 3 and the imaging lens 4 are arranged vertically so as to sandwich the edge part (peripheral part). The edge portion of the notch wafer 1 is uniformly illuminated by the illumination means 3,
An edge image E of an edge portion including the notch 1a of the notch wafer 1 is formed by an imaging lens 4 into a slit SPD.
(Silicon photodiode, light receiving element) A notch detection optical system is formed so as to form an image on 5. SPD5 with slit is SPD5a with slit 6a
And an SPD 5b having a slit 6b attached thereto. The longitudinal directions of the slit openings S of these two SPDs 5a, 5b are arranged parallel to each other and at right angles to the edge image E of the notch wafer 1 (radial direction of the notch wafer 1) as shown in FIG. You. Further, the length of the slit opening S is longer than the maximum length in the radial direction of the edge image of the notch 1a. Also two SPs
The output signal corresponding to the amount of light received by D5a, 5b is
It is input to the control unit 7.

The notch wafer 1 is transported onto the rotary table 2 by transport means (not shown), and the center of the notch wafer 1 and the rotation center of the rotary table 2 are accurately determined using a center position detecting device (not shown). Matched.
For example, a center position detecting device that matches the centers includes:
An apparatus disclosed in Japanese Patent Application No. 62-214694, which performs optical non-contact, is known.

When the rotary table 2 is rotated, S
An edge image E at each circumferential position of the notch wafer 1 is sequentially formed on the PD 5 by the imaging lens 4, but when an edge portion other than the notch 1a is formed, the SPD 5 shown in FIG.
An edge image E as shown in FIG. in this case,
Since a slit is bonded to the SPD 5, the actual S
The light reception image received by the PD 5 is indicated by hatching in FIG. 3A, and the outputs of the SPDs 5a and 5b are the same amount but at a small level.

Next, when the notch 1a of the notch wafer 1 comes to be imaged on the SPD 5, that is, as shown in FIG. 2B, the edge image E of the notch 1a slightly enters the range of the SPD 5. As shown in FIG. 3B, the light reception image received by the SPD 5 hardly changes in the SPD 5a, but the image received by the SPD 5b increases, and the output of the SPD 5b increases.

Further, the edge image E of the notch 1a is
As shown in FIG. 2C, when the two SPDs 5a and 5b are imaged symmetrically, the light-receiving image of the SPD 5 becomes the image shown in FIG.
(C), as compared with the state of FIG.
The outputs of D5a and 5b are both large, and the output of SPD5a and the output of SPD5b are at the same level.

The control unit 7 monitors the outputs of the SPDs 5a and 5b, and detects edge images other than the notch 1a at the SPDs 5a and 5b.
5b, and each output is the same (that is, the output of SPD 5a and the output of SPD 5a).
The motor 8 is controlled so as to stop the turntable 2 at a position where the difference between the outputs of the PDs 5b becomes 0). By performing such control, the notch 1a of the notch wafer 1 is positioned at the position shown in FIG.

In the above embodiment, the notch wafer is positioned based on the detection of the notch 1a, which is a notch. However, the present invention can be similarly applied to a wafer having an orientation flat. Also, two slit openings S
May not be parallel to each other as in the above-described embodiment, and if the two slit openings are located in line-symmetric positions with respect to the radial direction of the circular substrate, for example, they may be arranged in an eight-shape. Good.

[0020]

As is apparent from the above description, according to the present invention, the edge image of the circular substrate obtained by the illumination of the illumination means is formed by the imaging means, and the formed sharp contour is formed. Since the edge image having the edge is received by the light receiving element through the slit, the rotational position of the circular substrate can be detected with high sensitivity, and the positioning accuracy of the circular substrate can be improved. Furthermore,
Since two light receiving elements are provided, an accurate rotational position of the circular substrate can be determined by comparing output signals of both light receiving elements.

In addition, since the positioning is performed without contact with the circular substrate by the optical means, effects such as reduction of damage to the circular substrate and generation of dust can be obtained. Furthermore, since the device can be configured with a small number of components, an inexpensive positioning device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a circular substrate positioning device according to the present invention.

FIG. 2 is a diagram showing an image formation state of an edge image on an SPD (light receiving element) having a slit with respect to each rotation position of the notch wafer in FIG. 1 as viewed from the slit side.

FIG. 3 is a diagram showing an image formation state of the edge image in FIG. 2 as viewed from the SPD side.

FIG. 4 is a schematic configuration diagram showing a conventional circular substrate positioning device.

[Explanation of symbols]

 Reference Signs List 1 notch wafer 1a notch 2 turntable 3 illumination means 4 imaging lens 5, 5a, 5b SPD (light receiving element) 6a, 6b slit 7 control unit 8 motor E edge image S slit opening

Claims (3)

[Claims] 1. A rotary table for holding and rotating a circular substrate in a state where the center of the circular substrate having a notch coincides with the center of rotation, control means for controlling rotation of the rotary table, Illuminating means for illuminating an edge portion of the circular substrate; imaging means for imaging an edge image of the circular substrate by illumination of the illuminating means; and a position at which the edge image of the circular substrate is imaged by the imaging means Placed in the
A circular substrate positioning device, comprising: two light receiving elements having slits. 2. The two light-receiving elements, each slit having the same shape, and a circumferential width or length of the circular substrate, which is provided by an edge image of the notch formed by the imaging means. 2. The circular substrate positioning apparatus according to claim 1, wherein the slits are arranged at intervals of less than or equal to each other, and a longitudinal direction of the slits is arranged in a radial direction of the circular substrate. 3. An output signal of the two light receiving elements is larger than an output signal when an edge image other than the notch is formed on the light receiving element, and the output signals of the two light receiving elements are the same. 3. The circular substrate positioning device according to claim 2, wherein the position is determined by the control means.