JP2001127140A - Substrate positioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more accurately detect the position of the outer periphery of a substrate by limiting unnecessary reflected light from the side face of the substrate. SOLUTION: A substrate positioning device optically detects the outer periphery of a substrate 1 by means of illuminating means 15 and 17 and light receiving means, and positions the substrate based on the detected results of the means. Illuminating angle adjusting means 20, 21, 22, and 23 which adjust the angle of illuminating luminous fluxes from the illuminating means 15 and 17 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate positioning device used in a semiconductor manufacturing device or the like.

[0002]

2. Description of the Related Art Conventionally, in pattern exposure in a semiconductor exposure apparatus, precise alignment between a projected mask pattern and a substrate pattern on an exposure stage is performed, and thereafter, the mask pattern is exposed. If
The exposure alignment mark on the substrate has a detectable area limited to a very narrow range. Therefore, before the above-mentioned precise alignment before exposure on the exposure stage, in order to position the alignment mark of the substrate within the detection range of the mark detecting means, the pre-alignment device is used in advance in the pre-alignment apparatus based on the outer shape of the substrate. Perform positioning, transport the substrate to the exposure stage by the transport means while maintaining that state,
The substrate is transferred to the exposure stage at a predetermined position.

FIG. 2 is a view for explaining a general form of a pre-alignment apparatus, and schematically shows a pre-alignment apparatus for aligning a wafer having an orientation flat. Notch in wafer,
That is, this positioning apparatus for positioning a wafer using an orientation flat includes a wafer chuck 2 for sucking a wafer 1 and a rotary stage 3 for holding the chuck and rotating the wafer 1 in a plane substantially parallel to the wafer surface. An X stage 4 and a Y stage 5 for holding the rotary stage 3 and moving the wafer in two directions XY perpendicular to each other in a plane perpendicular to the rotation axis; a driving motor 6 for the rotary stage 3; Encoder 7 for detecting rotational position, drive motor 8 for X stage 4, encoder 9 for detecting its position in X direction, drive motor 10 for Y stage 5, and encoder for detecting its position in Y direction 11, the angle of the rotary stage 3 and the X-stages 4 and Y by the encoders 7, 9 and 11.
The motor control means 12 detects the position of the stage 5 and controls each motor based on the position information.

The X stage 4 is arranged on the fixed base 13 so as to be movable in the X direction, and the Y stage 5 is arranged on the X stage 4 so as to be movable in the Y direction. The X motor encoder 9 and the Y motor encoder 11 are arranged. The X motor 8 and the Y motor 10 are driven by the control of the motor control means 12 in accordance with the output signal of the above, and the X stage 4 and the Y stage 5 are respectively moved. Further, the rotary stage 3 is rotatably arranged on the Y stage 5, and the motor control means 12 controls the motor 6 in accordance with the output signal of the encoder 7 to rotate the motor 6 by a specified angle. In this manner, the wafer 1 adsorbed on the wafer chuck 2 on the rotary stage 3 can be moved and rotated in two directions of XY.

A plurality of optical position detecting means 14 are fixedly mounted on the fixed base 13 for detecting the outer peripheral position of the wafer 1. FIG. 3 shows a more detailed configuration of the optical position detecting means 14. In the figure, 15 is a light emitting element such as a light emitting diode, 16 is a linear image sensor, 1
Denotes a wafer loaded on the optical path between the light emitting element 15 and the linear image sensor 16, 17 denotes optical means for Koehler illumination of the reference wafer 1 using the light emitting element 15 as a light source, and 18 denotes a linear image of the wafer 1 Image forming means including a lens, an aperture, and the like for forming an image on the image sensor 16;
Reference numeral 9 denotes an illumination optical system including a light emitting element 15 and an optical unit 17.

In this configuration, the wafer 1 is carried into the focus plane of the image forming means 18 and is illuminated by the illumination optical system 19.
Is illuminated, the outer peripheral portion is imaged on the linear image sensor 16 via the image forming means 18. Therefore, by processing the image information of the linear image sensor 16, the outer peripheral position of the wafer 1 can be detected.

FIG. 4 shows the arrangement of the linear image sensor 16 and the wafer 1 with respect to each axis. Linear image sensor 1
Numeral 6 has three linear image sensors 16A to 16C. The linear image sensors 16A and 16B are arranged parallel to the Y-axis and at a fixed distance from the Y-axis to finely position the wafer 1. The orientation flat is applied to both sensors. The linear image sensor 16C is arranged in parallel with the X-axis direction and at a position 90 degrees from the position where the orientation flat exists.

In the above-described configuration, while the wafer 1 is held on the wafer chuck 2, first, the center of the rotary stage 3 is moved to a position on a linear extension of the linear image sensor 16C and at a predetermined distance. . Next, 3
The rotary stage 3 is rotated by 60 degrees or more. During this time, the linear image sensor 16C detects the outer peripheral position of the wafer 1 from 0 ° to 360 ° at a sufficiently fine sampling interval by the encoder 7 for detecting the rotational position. Then, by processing the outer peripheral position information for each fixed angle by an arithmetic means such as a microprocessor (not shown), the eccentric amounts OX1 and OY1 of the wafer 1 with respect to the rotation center of the rotary stage 2 and the perpendicular bisector L of the orientation flat are obtained. Is calculated between the angle and the Y axis. Next, the wafer control unit 12 moves the wafer 1 in the X direction by -OX1, Y
The wafer 1 is roughly positioned by moving and rotating by OY1 in the direction and by -θ in the rotation direction. Next, the rotation stage 3, the X stage 4, and the Y stage 5 are determined based on the wafer edge position information to be imaged on the linear image sensors 16A to 16C and a predetermined pressing position error.
Are sequentially and minutely driven to perform precise alignment of the wafer 1. Thus, the pre-alignment operation of the wafer 1 is completed.

[0009]

When the light emitting element 15 of the illumination optical system 19 in FIG. 3 is a point light source and is located at a proper position with respect to the optical means 17, the wafer 1
Is completely parallel light. In this case, if the light is illuminated so as to be parallel to the side surface of the wafer 1, no reflection occurs on the side surface of the wafer 1. However,
When a light emitting diode or the like is used as the light emitting element 15, the light emitted from the light source is a light source having a finite area.
Are not completely parallel light beams as shown in FIG. Under such conditions, when an attempt is made to detect the outer peripheral position of the wafer 1 that has not been chamfered, the influence of the reflection of the illumination light by the side surface of the wafer 1 cannot be ignored.

Hereinafter, the problem of the reflected light will be described with reference to FIG. Now, as shown in FIG.
Height H as the focal plane of the linear image sensor 16,
It is assumed that a point A on the outer periphery of the wafer 1 forms an image on a point A ′ on the linear image sensor 16. At this time, the reflected light beam L2 of the light beam L1 incident on the side surface of the wafer 1 moves to the position B on the focus surface.
Since the light beam is equivalent to the light beam starting from
, The light is incident on an image forming position B ′ which should be shielded by the wafer 1.

For the reasons described above, the reflected light is combined with the image on the outer peripheral portion of the wafer 1 and the linear image sensor 16
Is a waveform as shown by a solid line 61 in FIG. 7, for example. The waveform shown by the broken line 62 is a waveform when there is no normal reflection on the side surface of the wafer. Under these conditions,
If an attempt is made to detect the outer peripheral position of the wafer by comparing the threshold value SL with the amount of received light for each image, the outer peripheral position will be erroneously detected by ΔX.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and has as its object to limit unnecessary reflected light on the side surface of a substrate and to enable more accurate detection of the outer peripheral position. I do.

[0013]

In order to solve the above-mentioned problems, a first substrate positioning device of the present invention optically detects an outer peripheral portion of a substrate by an illumination means and a light receiving means, and based on the detection result. In a substrate positioning device for positioning the substrate, an illumination angle adjusting means for adjusting an angle of an illumination light beam from the illumination means is provided.

The second substrate positioning device is the first substrate positioning device, wherein the illumination angle adjusting means can adjust the angle of the illumination light beam so that the illumination light beam does not enter the side surface of the substrate. Characterized in that:

A third substrate positioning device is the first substrate positioning device, wherein the illumination angle adjusting means restricts a position and an amount at which light reflected by the side surface of the substrate due to the illumination light beam enters the light receiving means. The angle of the illumination light beam can be adjusted so that

A fourth substrate positioning device is the first substrate positioning device, wherein the illumination angle adjusting means sets an angle between an optical axis of the illumination light beam and a side surface of the substrate to 0 ° to 10 °.
It is characterized in that it can be adjusted in the range of °.

A fifth substrate positioning device is the substrate positioning device according to any one of the first to fourth embodiments, wherein the illumination angle adjusting means is configured to reduce the detection error of the outer peripheral portion of the substrate by reducing the illumination light flux. It is characterized in that the angle can be adjusted.

A sixth substrate positioning device according to any one of the first to fifth substrate positioning devices, wherein the illumination means has a light emitting element and an optical means for forming the illumination light with light emitted therefrom. The angle of the illumination light beam can be adjusted by moving the light emitting element with respect to the optical means.

A seventh substrate positioning device is the substrate positioning device according to any one of the first to fifth aspects, wherein the illuminating means comprises a light emitting element, an optical means for forming the illuminating light with light emitted therefrom, And a holding member for holding the positional relationship described above, wherein the angle of the illumination light beam can be adjusted by adjusting the mounting angle of the whole to the substrate.

The eighth substrate positioning device comprises a first substrate positioning device.
In any one of the substrate positioning apparatus according to any one of the first to seventh aspects, the angle of the illumination light flux is adjusted by the illumination angle adjustment means based on information obtained by the light receiving means when the outer peripheral portion of the substrate is illuminated by the illumination light flux. It is characterized by having arithmetic and control means.

In the configuration of the present invention, since the angle of the illumination light beam can be adjusted, the angle of the illumination light beam is adjusted to limit the amount, position, and the like of the light reflected on the side surface of the substrate to the light receiving means. The influence of light is eliminated, and the outer peripheral portion of the substrate is accurately detected. Therefore, a stable substrate positioning operation can be performed regardless of whether or not the substrate is chamfered.

[0022]

FIG. 1 shows a main part of a substrate positioning apparatus according to an embodiment of the present invention. As the overall configuration of the device, a configuration as shown in FIG. 2 can be used. In FIG.
1 is a wafer carried into the pre-alignment apparatus, 15 is a light emitting element such as a light emitting diode, 16 is a linear image sensor, 17 is an optical means for Koehler-illuminating the wafer 1 as a reference using the light emitting element 15 as a light source, 18 Denotes an image forming means including a lens, an aperture, and the like for forming an image of the wafer 1 on the linear image sensor 16;
5 is a moving means for moving the light emitting elements in the circumferential direction of the wafer 1, 21 is a motor for moving the moving means 20 in the circumferential direction of the wafer, 22 is an encoder for detecting the position of the light emitting element 15, 23 Is a motor 21 based on the position information of the wafer edge obtained from the linear image sensor 16.
This is an arithmetic and control means for driving.

In the above configuration, the rough positioning of the wafer 1 is completed as described in the section of the prior art. Next, the light emitting elements 15 are driven in a direction A from the outer peripheral side of the wafer 1 toward the center. At this time, the imaging waveform information of the wafer edge portion to the linear image sensor 16 is taken into the arithmetic / control means 23 at a sufficiently fine sampling interval, and the waveform of the wafer edge portion monotonically increases, and the light emitting element 15 which changes steepest is obtained. Detect the position of. Then, from this position, the light emitting element 15 is further moved in the central direction A of the wafer 1 within a range where the amount of light incident on the linear image sensor 16 is sufficiently obtained, so that the total illuminating light flux is parallel to the side surface of the wafer 1 or the angle in the outer peripheral direction. Adjust to hold and fix. According to the method described above, reflection on the side surface of the wafer 1 is prevented, and thereafter, the outer peripheral position of the wafer 1 can be always stably detected.

The present invention can be implemented by appropriately modifying it within the scope. For example, in the above-described embodiment, the angle of the illumination light beam is adjusted by moving the light emitting element 15 with respect to the optical means 17, but the object of the present invention, that is, the restriction of the reflected light from the side of the substrate is achieved. Any configuration may be used as long as it adjusts the angle of the illuminating light beam in order to achieve this.

[0025]

As described above, according to the present invention, the means for adjusting the angle of the illuminating light beam is provided, so that unnecessary reflected light on the side surface of the substrate is restricted, and the reflection at the time of detecting the outer peripheral portion of the substrate is reduced. The effect of light can be reduced. Therefore, the outer peripheral position of the substrate can be detected more accurately, and the substrate can be stably positioned.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a substrate positioning device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a general configuration of a pre-alignment apparatus.

FIG. 3 is a diagram showing a more detailed configuration of a conventional optical position detecting means.

FIG. 4 is a diagram showing an arrangement of a linear image sensor and a wafer with respect to each axis in the apparatus of FIG. 2;

FIG. 5 is a diagram for explaining a light flux of a light emitting element that emits surface light.

FIG. 6 is a diagram for explaining the influence of reflection on the side surface of the substrate.

FIG. 7 is a diagram showing an image waveform of a one-dimensional linear image sensor.

[Explanation of symbols]

1: wafer, 2: wafer chuck, 3: rotary stage,
4: X stage, 5: Y stage, 6: rotary stage drive motor, 7: rotational position detection encoder, 8: X stage drive motor, 9: X direction position detection encoder, 1
0: Y stage drive motor, 11: Y direction position detection encoder, 12: Motor control means, 13: Fixed base,
14: optical position detecting means, 15: light emitting element, 16 (1
6A to 16C): linear image sensor, 17: optical means, 18: imaging means, 19: illumination optical system, 20: moving means, 21: light emitting means moving motor, 22: light emitting means position detection encoder, 23: arithmetic operation Control means;

Claims (8)

[Claims] 1. A substrate positioning apparatus for optically detecting an outer peripheral portion of a substrate by an illuminating unit and a light receiving unit and positioning the substrate based on the detection result, wherein an angle of an illuminating light beam from the illuminating unit is adjusted. A substrate positioning apparatus, comprising: 2. The illumination angle adjusting means according to claim 1, wherein said illumination angle adjusting means is capable of adjusting an angle of said illumination light beam so that said illumination light beam does not enter a side surface of said substrate. Substrate positioning device. 3. The illumination angle adjusting means is capable of adjusting the angle of the illumination light flux so as to limit the position and amount of the light reflected by the illumination light flux on the side surface of the substrate to the light receiving means. The substrate positioning apparatus according to claim 1, wherein 4. The illumination angle adjusting means is capable of adjusting an angle between an optical axis of the illumination light beam and a side surface of the substrate in a range of 0 ° to 10 °. 2. The substrate positioning device according to 1. 5. The illumination angle adjusting means according to claim 1, wherein said illumination angle adjusting means is capable of adjusting an angle of said illumination light flux so as to reduce a detection error of an outer peripheral portion of said substrate. The substrate positioning apparatus according to any one of claims 1 to 7. 6. The illumination means has a light emitting element and an optical means for forming the illumination light with light emitted from the light emitting element, and moves the light emitting element with respect to the optical means to thereby generate the illumination light flux. The substrate positioning device according to any one of claims 1 to 5, wherein the angle can be adjusted. 7. The illuminating means includes a light emitting element, an optical means for forming the illuminating light with light emitted from the illuminating element, and a holding member for maintaining a positional relationship between the illuminating element and the light emitting element. The substrate positioning apparatus according to any one of claims 1 to 5, wherein an angle of the illumination light beam can be adjusted by adjusting an angle. 8. An arithmetic and control unit for adjusting the angle of the illumination light beam by the illumination angle adjusting device based on information obtained by the light receiving device when the outer peripheral portion of the substrate is illuminated by the illumination light beam. The substrate positioning device according to any one of claims 1 to 7, wherein: