JPH10247681A - Method and device for detecting positional deviation, positioning device, and aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the positional deviation of a wafer which occurs when the wafer is transported by only detecting the positions of the two outer edges of the wafer containing notches on a wafer stage. SOLUTION: On a wafer positioning device 14, the position (including rotation) of a wafer W is accurately detected even when a manufacturing error, etc., is contained in the circularity of the wafer W by detecting the positions of the three outer edges containing notches of the wafer W before transportation by means of sensors 32a-32c. Of the three outer edges of the wafer W detected on the positioning device 14 after the wafer W is carried onto a substrate stage WS, the position of the two outer edges of the wafer W containing the notches are detected by means of sensors 40a, and 40b. Then the positional deviation of the wafer W before and after the wafer W is transported is accurately calculated based on the detected results of the positions of the two outer edges and the detected results on the positioning device 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a displacement, a positioning apparatus and an exposure apparatus, and more particularly to a substrate positioning apparatus such as a wafer pre-alignment apparatus by a transfer system such as a wafer loader. Position shift detecting method and apparatus for detecting a position shift before and after transfer of a substrate such as a wafer transferred on a substrate stage, a positioning device for positioning the substrate at a desired position on the substrate stage, and applications of these devices. Related to an exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, a semiconductor device, an image pickup device (CC)
D), in a photolithography step (a step of forming a resist image of a mask pattern on a substrate) for manufacturing a liquid crystal display element or a thin film magnetic head, etc., a reticle pattern as a mask is projected via a projection optical system. An exposure apparatus such as a projection exposure apparatus (stepper or the like) for exposing a wafer (or a glass plate or the like) coated with a photoresist or a proximity type exposure apparatus for directly transferring a mask pattern onto a wafer is used. I have.

For example, since a semiconductor element is formed by stacking a large number of layers of circuit patterns on a wafer in a predetermined positional relationship, when exposing a circuit pattern of the second layer and thereafter on the wafer by such an exposure apparatus, It is necessary to perform high-accuracy alignment (alignment) between a reticle and a circuit pattern in each shot area of a wafer during exposure.

In this case, the final alignment between the reticle and the circuit pattern on the wafer (fine alignment)
Is performed by detecting the position of a position detection mark formed on the wafer by an alignment sensor provided in the exposure apparatus. Before that, the position shift and rotation in the two-dimensional plane of the wafer are performed based on the outer edge of the wafer. Prealignment is required to keep the deviation within a certain allowable value.

Generally, in an exposure apparatus, a wafer is held on a substrate stage by, for example, vacuum suction via a holding mechanism called a wafer holder, and each shot area on the wafer is exposed while moving this stage. . In this case, the wafer as the substrate to be exposed is loaded onto the wafer holder by a transfer system called a wafer loader, and is unloaded after the exposure. The wafer pre-alignment method in the conventional exposure apparatus is roughly classified into the following three methods. That is, after the wafer is pre-aligned to a predetermined position on the wafer pre-alignment apparatus, the wafer is transferred (loaded) onto the wafer holder by the wafer loader. That is, in this case, the pre-alignment is not performed after the conveyance.

After pre-aligning the wafer at a predetermined position on the wafer pre-alignment apparatus, the wafer is transferred (loaded) onto a wafer holder by a wafer loader. Subsequently, the wafer position is re-measured on the wafer holder, and the result is fed back to the wafer stage position and the rotation amount.

After roughly pre-aligning the wafer on the wafer pre-alignment apparatus, the wafer is transferred (loaded) onto a wafer holder by a wafer loader. Subsequently, the pre-alignment is again performed correctly on the wafer holder.

[0008] Of the above three methods, the method has a problem in accuracy, and has a disadvantage that it cannot meet future demands for higher accuracy. In addition, the method of (1) takes a long time for pre-alignment and has a problem in terms of throughput.
Since a high-precision positioning mechanism or the like is required on the wafer holder (or wafer stage), the size of the wafer stage and, consequently, the entire apparatus is increased, and as a result the footprint (apparatus installation area) is undesirably increased. Therefore, it can be said that the above method is the most realistic method in the future.

A wafer is generally circular and has a notch or an orientation flat (hereinafter abbreviated as “OF”) or the like formed on an outer peripheral portion thereof as a reference for an in-plane rotational position. However, if OF is formed, 1
Since the area of a single wafer becomes smaller than that of the notch, which leads to a decrease in device production per wafer, etc.,
In the future, the reference for the rotational position seems to be unified to a notch (a V-shaped notch).

[0010]

In the case of a notched wafer, if there is no manufacturing variation in the roundness of the wafer itself or in the radius in the circumferential direction with respect to the center of the wafer, the notch position and the position other than the notch are in principle. If two outer edges are detected at one location on the outer peripheral portion of the wafer, the position of the wafer (more precisely, the position of the center of the wafer) and rotation should be determined. However, actual wafers have manufacturing variations, and in order to suppress this effect, another position is added, and the position of the wafer outer edge is detected at three positions to detect the position of the wafer.

FIG. 4 is a schematic plan view showing a pre-alignment apparatus 114 in a conventional exposure apparatus employing the above-described pre-alignment method, and a vicinity of the wafer stage WS. In the apparatus shown in FIG. 4, three positions including notches of the wafer W held by a not-shown pre-alignment mechanism on the pre-alignment device 114 are detected by the pre-alignment sensors 132a, 132b, and 132c to position the wafer W at a predetermined position. After the wafer W is transferred to a wafer holder (not shown) on the wafer stage WS by the wafer W transfer arm 138, the wafer W is transferred to the wafer holder. In some cases, the wafer W cannot be placed at a desired position on the wafer holder.

Therefore, after the wafer W is mounted on the wafer holder, three positions including the notch of the wafer W are also detected above the wafer stage WS at the loading position shown in FIG. 4 in order to detect the position of the wafer W again. Prealignment sensors 140a, 140b and 140c are provided, and these prealignment sensors 140a to 140c are provided.
The position deviation from the desired position of the wafer W is obtained again from the detection result of c, and the amount of this position deviation is used as an offset of an interferometer (not shown) for managing the position of the wafer stage WS, for example. Had been done.

However, recently, in order to cope with high integration of semiconductor elements, the wafer size is increased in diameter, and in an exposure apparatus, the projection optical system PL is further increased in diameter as the NA and the field are increased. (See PL shown by a solid line and PL shown by an imaginary line in FIG. 4), and three exposure positions that can detect three outer edge positions of a wafer placed on a wafer holder in a conventional exposure apparatus Arranging all the sensors has been difficult in terms of space. FIG. 4 illustrates a state where the sensor 140c cannot be arranged.

As a first measure for avoiding such inconvenience, the position (loading position) of the wafer stage WS for transferring the wafer W to the wafer holder is set to the right side or the upper side in FIG. 4 from the position shown in FIG. if,
Although it is possible to install the sensor 140c at the position shown in FIG. 4, it is necessary to make the moving distance (stroke) of the wafer stage WS longer, and the entire exposure apparatus including the wafer stage WS is required. There was an inconvenience of increasing the size.

As a second method, it is possible in principle to detect the position of the wafer W based on the outer shape of the wafer W using only two sensors such as the sensors 140a and 140b in FIG. However, these two sensors 140
In the alignment sequence using only the a and 140b, the X and Y directions of the notch are adjusted based on the output of the sensor 140a for detecting the notch, and the remaining sensors 140a and 140b are aligned.
Only a special sequence for adjusting the position of the wafer W in the radial direction (r direction) in b can be adopted. However, in the actual exposure process or other semiconductor manufacturing processes, various devices including new and old are mixed, and in these devices, various sequences as described later are employed, and all of them are Since the sequence is based on the three sensor outputs in consideration of the above-described wafer manufacturing variations, if the above-described special alignment sequence is adopted, the compatibility of the pre-alignment sequence with these devices cannot be maintained, There is a disadvantage that sharing of the pre-alignment device becomes impossible.

SUMMARY OF THE INVENTION The present invention has been made under such circumstances, and an object of the present invention is to provide a method of detecting a position of a substrate by detecting two outer edge positions including a cutout portion of the substrate on a substrate stage. Position can be accurately detected, and even if a plurality of substrate stages are provided in different devices, there is no particular problem. It is to provide a detection method.

It is another object of the present invention to provide a method of manufacturing a substrate by simply arranging a second outer edge position detecting system for detecting two outer edge positions including a cutout portion of a substrate on a substrate stage. It is an object of the present invention to provide a position shift detecting device capable of accurately calculating the position shift before and after the transfer.

It is another object of the present invention to dispose a substrate by simply disposing a second outer edge position detection system for detecting two outer edge positions including a cutout portion on the substrate stage. An object of the present invention is to provide a positioning device that can be positioned at a desired position on a stage.

It is another object of the present invention to prevent an increase in the moving range (stroke) of a substrate stage even when a large-diameter wafer is used as a sensitive substrate, thereby preventing the apparatus from being enlarged. It is an object of the present invention to provide an exposure apparatus capable of performing the above-described steps.

[0020]

According to the first aspect of the present invention, a substrate positioning device (14) is provided by a transport system (16).
A position shift before and after the transfer of the substrate (W) conveyed to one or more substrate stages (WS) from above, wherein the position shift before and after the transfer on the substrate positioning device (14) is performed. A first step of detecting at least three outer edge positions including a predetermined notch (N) of the substrate (W);
On any one of the substrate stages (WS), of the at least three outer edge positions of the substrate detected in the first step, at least two outer edge positions including the cutout (N) are detected. The first and second steps;
Calculating a positional shift before and after the transfer of the substrate (W) based on the detection result of the step.

According to this, in the first step, at least three outer edge positions including the predetermined cutout portion of the substrate before the transfer are detected on the substrate positioning device. Next, when the substrate is transferred from the substrate positioning device to a predetermined substrate stage by the transfer system, in the second step, at least three outer edge positions of the substrate detected in the first step are detected on the substrate stage. At least two outer edge positions including the inner and notch portions are detected. Then, in the third step, the positional deviation before and after the transfer of the substrate is calculated based on the detection results of the first and second steps. As described above, according to the present invention, even if there is a manufacturing error or the like in the roundness of the substrate, by detecting the three outer edge positions including the cutout portion of the substrate before transport on the substrate positioning device, The position (including rotation) of the substrate can be accurately detected, and two of the three outer edges including the cutout portion among the three outer edge positions of the substrate detected on the substrate positioning device after being transported onto the substrate stage. Only by detecting the position, it is possible to accurately calculate the positional deviation before and after the transfer of the substrate based on the detection results of the two locations and the detection result of the outer edge position detected on the substrate positioning device. Therefore, on the substrate stage, it is possible to accurately detect a positional shift due to the transport of the substrate only by detecting two outer edge positions including the cutout portion of the substrate. In this case, since the position of the substrate is accurately detected on the substrate positioning device based on the three outer edge positions of the substrate, a plurality of substrate stages are respectively provided in different devices, for example, various types of exposure devices of old and new types. Even if the substrate positioning device is used, the substrate positioning device can be shared.

According to a second aspect of the present invention, a transport system (16) is provided.
A position shift detector for detecting a position shift before and after the transfer of the substrate (W) transferred from the substrate positioning device (14) to the substrate stage (WS) by the substrate positioning device (14). A first outer edge detection system (32a, 32b, 32c) for detecting at least three outer edge positions including a predetermined notch (N) of the substrate (W)
And at least two of the at least three outer edge positions of the substrate (W) detected by the first outer edge detection system on the substrate stage (WS), including the cutout portion (N). A second outer edge detection system (40) for detecting the outer edge position
a, 40b); and calculating means (50) for calculating a displacement between before and after the transfer of the substrate (W) based on the detection results of the first and second outer edge detection systems.

According to this, by the first outer edge detection system,
At least three outer edge positions including a predetermined cutout portion of the substrate before transport are detected on the substrate positioning device. Next, when the substrate is transferred from the substrate positioning device to the substrate stage by the transfer system, the second outer edge detection system detects the at least three outer edges of the substrate detected by the first outer edge detection system on the substrate stage. Out of the positions, at least two outer edge positions including the notch are detected. And
The calculating unit calculates the positional deviation before and after the transfer of the substrate based on the detection results of the first and second outer edge detection systems.
As described above, according to the present invention, the first outer edge position detection system detects three outer edge positions including the cutout portion of the substrate before transport on the substrate positioning device, so that the roundness of the substrate is improved. Even if there is a manufacturing error or the like, the position (including rotation) of the substrate can be accurately detected, and after being transferred onto the substrate stage, the position is detected by the second outer edge position detection system by the first outer edge position detection system. Even when only the two outer edge positions including the notch portion are detected among the three outer edge positions of the substrate, the calculation is performed based on the detection results of the two locations and the detection result of the first outer edge position detection system. The means can accurately calculate the positional deviation before and after the transfer of the substrate. Therefore, on the substrate stage (the term “on the substrate stage” as used herein includes not only the meaning on the stage itself, but also the meaning above the stage, or both on the stage and above the stage: And 5), it is sufficient to dispose a second outer edge position detection system for detecting two outer edge positions including the cutout portion of the substrate.

In this case, it is premised that the positional deviation is accurately detected if the detected values of the first outer edge detecting system and the detected values of the second outer edge detecting system are accurately associated with each other. For example, as in the invention according to claim 3, the correspondence between the detection value of the first outer edge detection system (32a, 32b, 32c) and the detection value of the second outer edge detection system (40a, 40b) is as follows. When the substrate (W) is transported in advance from the substrate positioning device (14) to the substrate stage (WS) by the transport system (16), the first and second outer edge detection systems respectively detect the substrate (W). This may be performed using the difference between the same reference position and the outer edge position. In this case, the plurality of substrates are transported in advance from the substrate positioning device to the substrate stage by the transport system, and the difference between the same reference position and the outer edge position in each of the substrates is detected by the first and second outer edge detection systems. May be detected, and the detected value of the first outer edge detection system and the detected value of the second outer edge detection system may be associated with each other using the average value of the detected values.

According to a fourth aspect of the present invention, a transport system (16) is provided.
A substrate (W) conveyed from the substrate positioning device (14) by the positioning device (14) at a predetermined position on the substrate stage (WS). W) a first outer edge detection system (32a, 32b, 32c) for detecting at least three outer edge positions including the predetermined notch (N); and the first outer edge on the substrate stage (WS). A second outer edge detection system (40a, 40a) that detects at least two outer edge positions including the notch (N) among the at least three outer edge positions of the substrate (W) detected by the detection system.
b) moving means for moving the substrate (W) relative to the substrate stage (WS) in a two-dimensional plane;
4) and; control means (50) for controlling the moving means such that the substrate is positioned at a desired position on the substrate stage based on the detection results of the first and second outer edge detection systems. Have.

According to this, by the first outer edge detection system,
At least three outer edge positions including a predetermined cutout portion of the substrate before transport are detected on the substrate positioning device. Next, when the substrate is transferred from the substrate positioning device to the substrate stage by the transfer system, the second outer edge detection system detects the at least three outer edges of the substrate detected by the first outer edge detection system on the substrate stage. Out of the positions, at least two outer edge positions including the notch are detected. And
The control means controls the moving means such that the substrate is positioned at a desired position on the substrate stage based on the detection results of the first and second outer edge detection systems. Here, the control of the moving means by the control means calculates a position shift amount based on a detection result of the first outer edge detection system and the second outer edge detection system,
A control method that makes this zero may be used.
The servo control may be such that the detection result of the second outer edge detection system matches the detection result of the outer edge detection system.

As described above, according to the present invention, the first outer edge position detection system detects three outer edge positions including the cutout portion of the substrate before transport on the substrate positioning device.
Even if there is a manufacturing error or the like in the roundness of the substrate, the position (including rotation) of the substrate can be accurately detected, and after the substrate is conveyed onto the substrate stage, the second outer edge position detection system detects the first outer edge. Of the three outer edge positions of the substrate detected by the position detection system, only the detection of the two outer edge positions including the notch portion results in the detection results of the two positions and the detection result of the first outer edge position detection system. Based on the above, the substrate is positioned at a desired position on the substrate stage by the control means. Therefore, it is sufficient to dispose a second outer edge position detection system for detecting two outer edge positions including a cutout portion of the substrate on the substrate stage, and the substrate can be positioned at a desired position on the substrate stage.

According to a fifth aspect of the present invention, there is provided an exposure apparatus for exposing a pattern of a mask (R) to a sensitive substrate (W) on a substrate stage (WS), wherein the sensitive substrate (W) is provided on a substrate coordinate system. The apparatus according to any one of claims 2 to 4 is provided for positioning with respect to the position (1). According to this, as described above, the second outer edge position detection system for detecting the two outer edge positions including the cutout portion of the substrate may be arranged on the substrate stage, so that a large-diameter wafer is used as the sensitive substrate. However, it is not necessary to increase the moving range (stroke) of the substrate stage, and it is possible to prevent an increase in the size of the apparatus. Particularly, in the case of a projection exposure apparatus using a large-diameter projection optical system, the effect is large.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.
A description will be given based on FIG.

FIG. 1 shows a schematic configuration of an exposure apparatus 10 according to an embodiment to which a positioning apparatus according to the present invention is applied.

The exposure apparatus 10 includes an exposure apparatus body 12,
A pre-alignment device 14 as a substrate positioning device,
And a wafer transfer mechanism 16 that constitutes a part of the wafer loader as a transfer system.

The exposure apparatus body 12 includes an illumination optical system I for uniformly illuminating a reticle R as a mask from above.
OP, a reticle holder RS for holding the reticle R, a projection optical system PL for reducing and projecting an image of a circuit pattern formed on the reticle R onto a wafer W as a substrate (and a sensitive substrate) having a surface coated with a photoresist, A wafer stage WS or the like as a substrate stage that holds the wafer W and moves two-dimensionally on the base BS in the X-axis direction (the horizontal direction in the paper of FIG. 1) and the Y-axis direction (the orthogonal direction in the paper of FIG. 1). It has.

A movable mirror 20 composed of an L-shaped mirror is provided at an end of the upper surface of the wafer stage WS, and a length measuring beam is irradiated toward the movable mirror 20 from a laser interferometer 22 disposed outside. The XY coordinates of the wafer stage WS are measured by the laser interferometer 22. The measurement value of the laser interferometer 22 is transmitted to the main controller 5
The main controller 50 controls the position of the wafer stage WS while monitoring the measurement value of the laser interferometer 22. Here, in actuality, as shown in FIG. 2, X
A laser interferometer 22X and a Y laser interferometer 22Y for projecting a length measurement beam in the Y-axis direction to the movable mirror 20 are provided, but these are typically illustrated as the laser interferometer 22 in FIG. .

A wafer holder 18 is mounted on the upper surface of wafer stage WS.
8, the wafer W is vacuum-sucked, and in this state, the reticle R
The exposure of the upper pattern onto the wafer W is performed by the main controller 50.
Is performed by, for example, a stepping and repeat method. Prior to this exposure, the main controller 50 pre-aligns the wafer W to a predetermined position on the wafer holder 18 as described later, and then determines the position of the alignment mark formed on the wafer W by the fine alignment sensor 23. To detect the position of the existing circuit pattern on the wafer W more accurately, and based on the result, accurately position the wafer W at the overlay exposure position. Therefore, in the exposure apparatus 10 of the present embodiment, high-accuracy overlay exposure is performed.

Further, on the wafer stage WS,
A center-up 24 as a moving means capable of minute movement in the XY direction and minute rotation about the Z axis orthogonal to the XY plane and capable of moving up and down in the Z axis direction is provided in a state penetrating the wafer holder 18. The operation of the center-up 24 is also controlled by the main controller 50 via a center-up drive mechanism (not shown). The positioning operation of the wafer W using the center up 24 will be described later in detail.

The pre-alignment apparatus 14 includes a transfer table 28 on which a wafer cassette 26 for storing a plurality of wafers W at predetermined intervals in a vertical direction, a pre-alignment mechanism 30 provided on the transfer table 28, Outer edge portion 3 of wafer W sucked and held by this pre-alignment mechanism 30
Three pre-alignment sensors 3 for detecting the position of a place
2a, 32b and 32c (FIG. 1 shows a state in which the pre-alignment sensors 32b and 32c are overlapped: see FIG. 2) and a first outer edge detection system. The pre-alignment mechanism 30 is constituted by a drive shaft capable of minute movement in the XY directions and minute rotation about the Z axis orthogonal to the XY plane, and capable of moving up and down in the Z axis direction, similarly to the center up 24 described above. In addition, a vacuum suction unit is provided on the upper end surface of the drive shaft. The operation of the pre-alignment mechanism 30 is also controlled by the main controller 50 via a drive system (not shown).

The three pre-alignment sensors constituting the first outer edge detection system are arranged at positions at a center angle of 120 degrees on the circumference of a predetermined radius (substantially the same as the radius of the wafer W). In this case, the pre-alignment sensor 32a is arranged at a position where the notch N (V-shaped notch) of the wafer W held on the pre-alignment mechanism 30 can be detected. As these pre-alignment sensors, image processing type sensors including an imaging element and an image processing circuit are used.

Here, a method of pre-alignment of the wafer W by the pre-alignment apparatus 14 will be described. An unprocessed (pre-exposure) wafer W taken out of the wafer cassette 16 by a transfer arm (not shown) constituting a wafer loader (not shown) is placed on the pre-alignment mechanism 30 and vacuum-adsorbed. The vacuum-adsorbed wafer W is indicated by a virtual line W1 in FIGS. In this state, the main controller 5
0, the position of the notch N of the wafer W is changed to the first position.
Pre-alignment sensor 32a constituting an outer edge detection system
, The rotation and position of the wafer W are roughly adjusted. The pre-alignment sensor 32a is shown in FIG.
As shown in (A), a notch N on the outer periphery of the wafer W
Is detectable in the X direction and the Y direction in the figure.

On the other hand, the targets to be detected by the pre-alignment sensors 32b and 32c constituting the first outer edge detection system are as follows:
Instead of a two-dimensional pattern such as a notch, a one-dimensional position on the outer edge of the wafer may be used. Therefore, the pre-alignment sensors 32b and 32c are connected to the wafer W shown in FIG.
It is sufficient that the one-dimensional position in the radial direction (r direction) can be detected. Also, the pre-alignment sensors 32b and 32c
Is a notch N detected by the pre-alignment sensor 32a.
, The outer edge of the wafer W at a position separated by a central angle of 120 degrees is detected.

Subsequently, the main controller 50 drives the pre-alignment mechanism 30 while monitoring the detection values of the respective pre-alignment sensors 32a, 32b, 32c. In this case, since the radius and roundness of the wafer W vary due to manufacturing errors, the detection values of the sensors at predetermined positions are not always constant. Therefore, main controller 50 accurately adjusts wafer W to a predetermined position in consideration of the manufacturing error.

As a specific sequence for this alignment, the following three sequences can be adopted.

A. Pre-alignment sensors 32b, 32
A method in which the detection value of c and the detection value of the pre-alignment sensor 32a in the Y direction are set to predetermined values. That is,
Positioning is performed using two points separated by 120 degrees from the notch position as a reference for the translation position.

B. X of the pre-alignment sensor 32a,
A method in which the detection values in both Y directions become predetermined values and the differences between the detection values of the pre-alignment sensors 32b and 32c and the respective predetermined values become equal. That is, alignment is performed using the notch as a reference for the translation position.

C. The Y detection value of the pre-alignment sensor 32a is set to a predetermined value, and the pre-alignment sensor 32a
And the difference between the X detection value of the pre-alignment sensor and the detection values of the pre-alignment sensors 32b and 32c, and the respective predetermined values. That is, the alignment is performed using the center of the wafer as a reference for the translation position.

In any of the above three sequences, the main controller 50 stores the detected values of the pre-alignment sensors 32a, 32b, 32c in the memory after the completion of the alignment.

The wafer transfer mechanism 16 is positioned above the base BS in FIG.
An X guide 34 extending in the axial direction;
(See arrows A and A ′ in FIG. 1 and FIG. 2). The operation of the transfer arm 38 is also controlled by the main controller 50 via a drive system (not shown).

Here, the transfer operation of the wafer W by the transfer arm 38 and the transfer operation of the wafer W between the transfer arm 38, the pre-alignment mechanism 30, and the wafer holder 18 will be briefly described.

As described above, the pre-alignment mechanism 3
After adjusting the position and rotation of the wafer W according to 0,
The main controller 50 drives the pre-alignment mechanism 30 holding the wafer W upward to move the wafer W to the transfer arm 38.
Lift above the moving surface of the. Next, the main controller 5
At 0, the transfer arm 38 is driven in the direction of arrow A integrally with the slider 36 via a drive system (not shown) to be positioned below the wafer W. In this state, the main controller 50 drives the pre-alignment mechanism 30 downward, and moves the pre-alignment mechanism 3 at the position where the wafer W abuts the transfer arm 38.
0 is released from the suction of the wafer W. At the same time,
The main controller 50 starts suction of the transfer arm 38.
Thus, the wafer W is suction-held by the transfer arm 38. Next, main controller 50 drives the transfer arm holding wafer W in the direction of arrow A ′, and transfers wafer W to a position above wafer holder 18. The wafer W being transferred is indicated by a virtual line W2 in FIG.

When the wafer W is transferred to a predetermined position above the wafer holder by the transfer arm 38, the main controller 50 drives the center-up 24 upward by a predetermined amount via a center-up driving mechanism (not shown). This allows
The upper surface of the center-up 24 contacts the wafer W. Next, the main controller 50 starts the suction of the center-up 24 and simultaneously releases the suction of the wafer W by the transfer arm 38. After that, the main controller 50 drives the center-up 24 further upward by a predetermined amount, drives the transfer arm 38 in the direction of arrow A, and retreats from the wafer holder 18.
Thus, the wafer W is transferred from the transfer arm 38 to the center-up 24. In FIG. 2, the wafer W held by the center up 24 is shown by a solid line.

Due to the influence of the vibration of the whole apparatus at the time of transferring the wafer W from the transfer arm 38 to the center up 24, the center up 24 receiving the wafer from the transfer arm 38 as described above is directly lowered. There is a case where the wafer W cannot be placed at a desired position on the wafer holder 18 only by performing the operation.

In consideration of this point, in the present embodiment, in order to detect (measure) the position of the wafer W transferred to the center-up 24 again, it is attached to the exposure apparatus main body 12 side, for example, to the projection optical system PL. Thus, a second outer edge detection system is provided. As shown in FIGS. 1 and 2, the second outer edge detection system includes two pre-alignment sensors 4 arranged above the wafer holder 18 at a predetermined distance in the XY plane.
0a and 40b. As these pre-alignment sensors 40a and 40b, similarly to the first outer edge detection system, an image processing type sensor including an image sensor and an image processing circuit is used. Here, the arrangement of these pre-alignment sensors 40a and 40b will be described in more detail.
Is arranged at a position where the notch of the wafer W transferred from the transfer arm 38 onto the center-up 24 can be imaged, and the other pre-alignment sensor 40b is positioned on the circumference having substantially the same radius as the wafer W. Is arranged at a position forming a central angle of 120 degrees counterclockwise from the arrangement position. That is, in the case of the present embodiment, the pre-alignment sensors 40a, 40a,
0b is the same as that of the pre-alignment sensors 32a and 32b constituting the first outer edge detection system described above.
When a and 32b are moved in parallel in the X-axis direction by a predetermined distance, the positional relationship is such that they substantially overlap the pre-alignment sensors 40a and 40b, respectively. For this reason, in the present embodiment, of the three outer edge positions of the wafer W detected by the first outer edge detection system, two outer edge positions including the notch N are changed to the second outer edge positions.
Can be detected by the outer edge detection system.

Then, the position of the wafer W above the wafer holder 18 is detected by using the pre-alignment sensors 40a and 40b constituting the second outer edge detection system.
The transfer error of the wafer W from the transfer arm 38 to the wafer holder 18 can be corrected. The details will be described later.

Next, correction of the positional deviation before and after the transfer of the wafer W transferred from the pre-alignment device 14 to the position above the wafer holder 18 by the transfer arm 38, and mainly the error in the transfer of the wafer W from the transfer arm 38 to the wafer holder 18 described above. The correction method will be described in detail.

As described above, the wafer W is transferred from the pre-alignment mechanism 30 to the transfer arm 38, transferred to a position above the wafer holder 18 by the transfer arm 38, and transferred to the center up 24 on the wafer stage WS.
At this time, the wafer W is slightly shifted from a desired position due to the influence of the vibration of the apparatus at the time of transfer.
In most cases, it is located at a position above the position 8.

Therefore, main controller 50 detects the position of wafer W by pre-alignment sensors 40a and 40b constituting a second outer edge detection system. At the time of this detection, main controller 50 controls pre-alignment sensor 40a.
The position detection values in both the X and Y directions and the position detection value in the r direction of the pre-alignment sensor 40b are stored in the internal memory at the time of pre-alignment on the pre-alignment device 14, and are performed by the pre-alignment sensors 32a and 32a. 32b
The center-up 24 is driven two-dimensionally in XY so that the same value as the detected value is obtained, and the relative position of the wafer W with respect to the wafer holder 18 and the wafer stage WS is adjusted. In this case, main controller 50 sets transfer arm of wafer W based on the difference between the detected values of pre-alignment sensor 40a and pre-alignment sensor 32a, and the difference between the detected values of pre-alignment sensor 40b and pre-alignment sensor 32b. 38, and the center up 24 is adjusted so that the position shift becomes zero.
May be driven, but the pre-alignment sensor 40a,
The center-up 24 may be driven by servo control so that the detection value of 40b matches the detection value of the pre-alignment sensors 32a and 32b stored in the memory. As a result, the above-described transfer error of the wafer W from the transfer arm 38 to the wafer holder 18 is corrected, and the positioning of the wafer W to a desired position on the wafer holder 18 is completed.

In this state, the main controller 50 drives the center up 24 downward to release the suction of the wafer W by the center up 24 when the upper surface of the center up 24 is flush with the upper surface of the wafer holder 18. The suction of the wafer W by the wafer holder 18 is started, whereby the delivery of the wafer W is completed.

Here, in order to accurately position the wafer W at a desired position on the wafer holder 18 by the above-described series of procedures, a first outer edge detection system provided on the pre-alignment apparatus 40 side is configured. The detection values of the pre-alignment sensors 32a and 32b, the detection values of the pre-alignment sensors 40a and 40b constituting the second outer edge detection system provided above the wafer stage WS on the exposure apparatus body 12, and the "desired position" It is premised that an accurate correspondence is made between the pre-alignment and the transfer arm on the pre-alignment mechanism 30 as described above, for example, for several wafers actually during the initial adjustment of the apparatus. The operation is carried out in accordance with the flow of transfer by 38 → re-measurement of the outer edge position on the wafer holder 18, and for each wafer, for example, The difference between the "desired position" measured using the alignment sensor 23 and the "outer edge position" detected by each of the pre-alignment sensors 32a, 32b, 40a, 40b is fed back to the detection value of each pre-alignment sensor. Can be adjusted. in this case,
A plurality of wafers are transported in advance from the pre-alignment device 14 onto the wafer stage WS by the transport arm 38,
For each wafer, the first and second outer edge detection systems have the same reference position, for example, the fine alignment sensor 2
3 and the difference between the “desired position” and the outer edge position, and using the average value thereof, the difference between the detected value of the first outer edge detection system and the detected value of the second outer edge detection system. You may make it correspond. Of course, for the device in use,
Such adjustment can be performed at regular intervals to check the pre-alignment accuracy.

As described above, according to the exposure apparatus 10 of the present embodiment, the position of the three outer edges including the notch N of the wafer W on the pre-alignment device 14 is determined by the pre-alignment sensor constituting the first outer edge detection system. 32a, 32b, 3
In step 2c, based on these detected values, positioning is performed at a desired position in consideration of manufacturing variations of the wafer W, and the position detected values of the pre-alignment sensors 32a, 32b, and 32c in the positioning state are stored in a memory. After being transferred onto the wafer holder 18, the pre-alignment sensors 32a, 32
b and the pre-alignment sensors 40a and 40b constituting a second outer edge detection system for detecting the same outer edge position on the wafer holder 18 as the sensors 32a and 32b.
Based on the position detection values, the wafer W is positioned at a desired position. Therefore, even if only two outer edges of the wafer W are detected on the wafer holder 18, the wafer W is accurately positioned at a desired position on the wafer holder (wafer stage) without being affected by manufacturing variations of the wafer W. It becomes possible to do. Further, in this case, even if the diameter of the wafer increases and the projection optical system PL increases in size, there is no possibility that the outer edge detection system and the projection optical system PL will interfere with each other.
There is no need to extend the movement range of the wafer stage.

Since the positions of the three outer edges including the notch N of the wafer W are detected by the pre-alignment sensors 32a, 32b, and 32c on the pre-alignment device 14, the above-described a. ~ C. Can be adopted, and the above a. ~ C. Whichever is adopted,
By performing the position detection on the wafer holder 18 as described above, the a. ~ C. It is possible to perform a pre-alignment equivalent to each of the above sequences. Therefore, even if the pre-alignment apparatus 14 is shared with another conventional exposure apparatus or another semiconductor manufacturing apparatus, it is possible to realize pre-alignment with high compatibility between different models without causing any inconvenience. Becomes

In the above embodiment, the wafer stage W
A center-up 24 that can move in the XY plane is provided on S, and the center-up 24 is moved based on the detection results of the first and second outer edge detection systems, thereby stopping at a predetermined loading position. Wafer stage W
The case where the wafer W is positioned at a desired position on S has been described. However, the present invention is not limited to this. For example, after placing the wafer W on the wafer holder 18 in substantially the same procedure as described above,
Main controller 50 calculates the positional deviation before and after the transfer of wafer W based on the detection results of the first and second outer edge detection systems, drives wafer stage WS so that this positional deviation becomes zero, and adjusts wafer holder 18. Then, the wafer W may be positioned at a desired position, and the position of the wafer stage WS at this time may be measured by the laser interferometers 22X and 22Y. Even in this case, main controller 50 can detect an accurate position of wafer W on the wafer coordinate system.

Alternatively, after mounting wafer W on wafer holder 18 in substantially the same procedure as above, main controller 50 transfers wafer W based on the detection results of the first and second outer edge detection systems. Even if the positional deviation before and after is calculated, and this positional deviation is added as an offset to the measurement values of the laser interferometers 22X and 22Y, and thereafter the position of the wafer stage WS is controlled using this offset, the same high accuracy as described above can be obtained. Can be pre-aligned, and the subsequent fine alignment using the alignment mark can be performed without any trouble.

As is clear from the above description, in the above-described embodiment, the main controller 50 constitutes the calculating means and the controlling means, and the pre-alignment sensors 32a, 32a
2b, 32c and pre-alignment sensors 40a, 40
b and the main controller 50 constitute a misalignment detecting device according to the present invention.
2a, 32b, 32c and pre-alignment sensor 40
a, 40b, the center-up 24 and the main controller 50 constitute a positioning device according to the present invention.

In the above-described embodiment, a case has been described in which an image processing type sensor for imaging the outer edge shape of a wafer and detecting the image from the image signal is used as the pre-alignment sensor constituting the first and second outer edge detection systems. However, the present invention is not limited to this. For example, a laser detection type sensor that irradiates a sheet-like laser beam near the outer edge of the wafer and detects the outer edge position of the wafer from its transmittance (or reflectance), and the like. It goes without saying that other types of sensors may be used.

[0064]

As described above, according to the first aspect of the present invention, on the substrate stage, only the two outer edge positions including the cutout portion of the substrate are detected, and the positional deviation accompanying the transport of the substrate is obtained. Is excellent, and even if a plurality of substrate stages are provided in different devices, the substrate positioning device can be shared without any trouble. A detection method is provided.

According to the second and third aspects of the present invention, the substrate can be formed simply by disposing the second outer edge position detection system for detecting two outer edge positions including the cutout portion of the substrate on the substrate stage. It is possible to provide an excellent position shift detecting device capable of accurately calculating the position shift before and after the transfer.

According to the fourth aspect of the present invention, the substrate can be mounted on the substrate stage simply by disposing the second outer edge position detection system for detecting two outer edge positions including the cutout portion of the substrate. An excellent positioning device that can be positioned at a desired position on the stage can be provided.

According to the fifth aspect of the present invention, even when a large-diameter wafer is used as the sensitive substrate, the range of movement (stroke) of the substrate stage does not increase, and the apparatus can be prevented from being enlarged. It is possible to provide an excellent exposure apparatus that can perform the exposure.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a configuration of an exposure apparatus according to one embodiment.

FIG. 2 is a plan view for explaining the operation of the apparatus shown in FIG. 1 and showing main components.

FIGS. 3A and 3B are diagrams showing a detection target of each pre-alignment sensor constituting a first outer edge detection system, wherein FIG. 3A is a diagram showing a notch portion of a wafer, and FIG. FIG.

FIG. 4 is a diagram for explaining a problem to be solved by the invention.

[Explanation of symbols]

Reference Signs List 10 Exposure device 14 Pre-alignment device (substrate positioning device) 16 Wafer transfer mechanism (transfer system) 24 Center up (moving means) 32a, 32b, 32c Pre-alignment sensor (first outer edge detection system) 40a, 40b Pre-alignment sensor ( Second outer edge detection system) 50 Main controller (calculation means, control means) WS Wafer stage (substrate stage) W Wafer (substrate, sensitive substrate) N Notch (notch) R Reticle (mask)

Claims (5)

[Claims] 1. A transfer system comprising:
Or a displacement detection method for detecting a displacement of a substrate conveyed on two or more substrate stages before and after the conveyance, wherein at least three of the substrates including a predetermined cutout portion of the substrate before the conveyance on the substrate positioning device are included. A first step of detecting an outer edge position of a portion; at least two of the at least three outer edge positions of the substrate detected in the first step, including the cutout portion, on any one of the substrate stages; A displacement detection method comprising: a second step of detecting an outer edge position of a location; and a third step of calculating a displacement between before and after the transfer of the substrate based on the detection results of the first and second steps. 2. A displacement detection device for detecting a displacement of a substrate conveyed from a substrate positioning device onto a substrate stage by a transport system before and after the substrate is transported. A first outer edge detection system for detecting at least three outer edge positions including the notch portion; a first outer edge detection system for detecting at least three outer edge positions of the substrate detected by the first outer edge detection system on the substrate stage At least two of which include the notch
A second outer edge detection system for detecting an outer edge position of a location; and a calculating means for calculating a positional shift before and after the transfer of the substrate based on the detection results of the first and second outer edge detection systems. Detection device. 3. The correspondence between the detection value of the first outer edge detection system and the detection value of the second outer edge detection system is as follows. 3. The position according to claim 2, wherein the difference between the same reference position and the same outer edge position detected by the first and second outer edge detection systems is used when the sheet is conveyed to the position. Deviation detection device. 4. A positioning device for positioning a substrate conveyed from a substrate positioning device by a conveyance system at a predetermined position on a substrate stage, wherein the predetermined notch portion of the substrate before being conveyed on the substrate positioning device. A first outer edge detection system for detecting at least three outer edge positions including: a cutout of the at least three outer edge positions of the substrate detected by the first outer edge detection system on the substrate stage At least 2 including notch
A second outer edge detection system for detecting an outer edge position of a location; moving means for relatively moving the substrate in a two-dimensional plane with respect to the substrate stage; based on detection results of the first and second outer edge detection systems Control means for controlling the moving means so that the substrate is positioned at a desired position on the substrate stage. 5. An exposure apparatus for exposing a pattern on a mask to a sensitive substrate on a substrate stage, the exposure apparatus being used for positioning the sensitive substrate at a desired position on a substrate coordinate system. An exposure apparatus comprising the apparatus according to claim 1.