JP3175058B2 - Substrate positioning device and substrate positioning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machine for a circular wafer substrate and a rectangular glass substrate incorporated in an exposure apparatus, a processing apparatus, an inspection apparatus, and the like for manufacturing a semiconductor element, a liquid crystal display element and the like. And a so-called pre-alignment device.

[0002]

2. Description of the Related Art FIG. 1 shows an apparatus for projecting and exposing a pattern of a reticle R on a rectangular glass substrate (hereinafter referred to as a plate) P via a projection lens PL. In the apparatus shown in FIG. 1, illumination light from an illumination system including a mercury lamp 1 and an elliptical mirror 2 illuminates a reticle R with uniform illuminance.

[0003] The plate P is placed on the holder 3 and sucked by vacuum, but for positioning on the holder 3,
The two orthogonal sides of the plate P are reference pins (rollers)
4A, 4B, and 4C are fixed in contact with each other. The holder 3 is held on an XY stage 5 that is two-dimensional in the X and Y directions, and the XY stage 5 is mounted on a surface plate (mounted on an anti-vibration table) 6.
Held on.

Further, in FIG. 1, a transfer arm 7 for exchanging and transferring a plate P is arranged on the front side of the apparatus.
The drive system 8 moves in the forward / backward and rotational directions. On the left side of the device, a carrier 9 is arranged toward the arm 7. A plurality of processing plates P are accommodated in the carrier 9 in parallel at regular intervals in the vertical direction. Further, the carrier 9 is configured to move up and down by a drive system 10, and performs vertical positioning so that the arm 7 can take out a desired plate in the carrier 9.

In the apparatus shown in FIG. 1, alignment microscopes GA, GB, GC and GD for photoelectrically detecting an alignment mark formed on the plate P are fixed on the outer periphery of the projection lens PL. Is established. Using the alignment systems GA to GB, the position of the plate P,
That is, the operation of determining the position of the XY stage 5 (or the minute rotation of the holder 3) is what is called fine alignment, and the reference pins 4A, 4B, 4
Positioning the plate P on the holder 3 using C is pre-alignment.

FIG. 2 shows an example of a conventional pre-alignment mechanism, and the same members as those shown in FIG. 1 are denoted by the same reference numerals. Three reference pins 4A, 4B on the holder 3,
4C is a rollable roller, and the plate P
Is a reference pin 4B, 4C and a pressing pin (roller) 4E.
The positioning is performed in the X direction by being sandwiched, and the positioning is performed in the Y direction by being sandwiched between the reference pin 4A and the pressing pin (roller) 4D. Press pins 4D, 4E
Are rotatably supported by the tips of the movers 11A and 11B, respectively, and the movers 11A and 11B swing in the directions of arrows KY and KX, whereby the plate P is pressed in the X and Y directions.

Although FIGS. 1 and 2 deal with a rectangular plate P, a pre-alignment mechanism of the same type is also incorporated in an exposure apparatus for processing a circular semiconductor wafer.

[0008]

In the prior art shown in FIG. 2, whether or not the plate P is correctly pre-aligned on the holder 3, that is, one side of the plate P contacts the reference pins 4B and 4C, and at the same time, the plate P It is difficult to recognize whether or not the other side perpendicular to the above has touched the reference pin 4A, and the arrows KX and KY of the pressing pins 4D and 4E are exclusively used.
This problem has been dealt with by empirically (experimentally) optimizing the pressing force in the direction and the pressing duration time.

Further, for reliable pre-alignment, the pressing pins 4D, 4E are driven with a pressing force much larger than the pressing force originally required for pre-alignment, and the pressing pins 4D, 4E, Or reference pin 4
A drawback such as distortion of the portion in contact with A to 4C has occurred. Immediately after pre-alignment, the plate P is vacuum-adsorbed onto the holder 3, so that the plate P is fixed on the holder 3 while the periphery of the plate P is distorted (the surface of the peripheral portion is curved).

SUMMARY OF THE INVENTION It is an object of the present invention to solve such a problem and to obtain a positioning device in which the pressing force of the substrate at the time of pre-alignment is reduced to eliminate any mechanical distortion (deformation) of the substrate.

[0011]

A substrate positioning apparatus according to the present invention is characterized in that a plurality of reference members (reference pins 4A, 4B, 4C) serving as references for positioning a substrate are slightly moved in a contact direction with the substrate. A plurality of movable members that support the reference member so as to be displaced between a first position and a second position that are separated from each other and that normally bias the reference member in the direction of the first position (pre-alignment preparation position) of the displacement. Members (20 to 23) are provided.

Furthermore, the substrate positioning device of the present invention is
A detection signal is output when the substrate is pressed by the operation of the pressing members (the pressing pins 4D and 4E) and each of the reference members (4A to 4C) is displaced from the first position to the second position (the pre-alignment reference position). Detectors (sensors 25: 2
5A to 25C), a determination circuit (AND circuit 27) for generating a signal (E0) indicating completion of the positioning of the substrate when all of the respective detection signals are output, and controlling at least the pressing members (4D, 4E). And an error processing device (control circuit 28) for performing positioning again. Also,
According to the method of positioning a substrate of the present invention, the reference members (4A to 4A) which are displaceably provided on the holder (3) by pressing the end surface of the substrate on the holder (3) with the pressing members (4D, 4E).
C) a method of positioning a substrate with respect to C), comprising: moving a pressing member (4D, 4E) toward the substrate; detecting a position of a reference member (4A to 4C); The method includes a step of determining whether the substrate is positioned based on the positions of the members (4A to 4C), and a step of repositioning the substrate when the substrate is not positioned within a predetermined time.

[0013]

With the substrate positioning apparatus of the present invention, the completion of positioning can be confirmed by the determination circuit, so that it is possible to prevent the substrate from continuously contacting the reference member with a pressing force that is problematic as in the prior art. Further, since the substrate positioning device of the present invention imparts an urging force to the movable member, the stress applied to the end surface of the substrate when the end surface of the substrate starts to contact the reference member due to the operation of the pressing member is the urging force of the movable member. And about the same. For this reason, the pressing force of the substrate by the pressing member only needs to be slightly larger than the urging force, and this point is more advantageous than before. Further, in the substrate positioning device of the present invention, when the substrate cannot be positioned, the error processing device positions the substrate again, so that the substrate positioning error can be reduced. Further, the method for positioning the substrate of the present invention,
Since the positioning of the substrate is performed again when the substrate is not positioned within the predetermined time, the positioning error of the substrate can be reduced.

[0014]

FIG. 3 is a plan view showing a positioning mechanism according to an embodiment of the present invention, in which members having the same functions as those in the mechanism shown in FIG. 2 are denoted by the same reference numerals. FIG. 2 shows a state in which the placed plate P is correctly pre-aligned, and shows three reference pins (rollers) 4A, 4B, 4C,
The arrangement of the two pressing pins (rollers) 4D and 4E in the plane is the same as that in FIG.

In this embodiment, three reference pins 4A, 4A
B and 4C are not directly supported by the holder 3, but are provided via a lever 20 which can move (swing) by a predetermined amount. Although only the mechanism for the reference pin 4B is described in FIG. 3, the other reference pins 4A and 4C have exactly the same mechanism. The lever 20 is supported on the holder 3 via a rotation shaft (pivot) 21. A reference pin 4B is rotatably supported at one end of the lever 20. The swing amount of the lever 20 is regulated by two fixing pins 22A and 22B implanted in the holder 3.
As shown in FIG. 3, when the reference pin 4B comes into contact with the plate P and the plate P is pushed in the direction of the arrow KX by the pressing pin 4E, one end of the lever 20 comes into contact with the fixed pin 22B. The position is the correct pre-alignment reference position of the reference pin 4B.

A tension spring 23 is provided between the other end of the lever 20 and the holder 3 to apply an urging force such that the other end of the lever 20 comes into contact with the fixing pin 22A. Therefore, in a state where there is no plate P, as shown in FIG. 4, the other end of the lever 20 is always in contact with the fixed pin 22A with a constant urging force by the spring 23. Here, the position of the reference pin 4B (4A, 4C) in the state as shown in FIG. 4 is called a pre-alignment preparation position, and the position of the reference pin in the state of FIG. 3 is called a pre-alignment reference position. To Therefore, three reference pins 4A, 4B, 4C
Moves two points slightly apart in the positioning direction (arrows KX and KY) of each side of the plate P to be aligned, that is, between the preparation position and the reference position. The moving amount varies depending on the size of the plate P and the transport accuracy, but is set to about several mm.

In this embodiment, a light shielding plate 2 is provided at one end of the lever 20 to check the quality of the pre-alignment.
4 is fixed horizontally, and is configured to rotate in the XY plane with the swing of the lever 20. As shown in FIG. 4, the light-shielding end of the light-shielding plate 24 is disposed so as to advance and retreat into the light beam IL of the sensor 25 such as a transmission (or reflection) photointerrupter. Then, as shown in FIG.
When (4A, 4C) comes to the reference position, the sensor 25
Of the light beam is completely or predeterminedly blocked by the light shielding plate 24. When the position of the reference pin 4B is incomplete,
Since the light beam IL of the sensor 25 is not partially or not light-shielded, a high photoelectric output is generated.

FIG. 5 shows a control system block of the pre-alignment mechanism shown in FIGS.
Sensors corresponding to each of A to 4C are sensors 25A, 25B, and 25C, respectively. Sensor 25A, 2
5B and 25C are output from inverters 26A, 26B, 2
The signal is applied to a 3-input AND circuit 27 via 6C. In this embodiment, when the pre-alignment is correctly achieved,
Since the luminous flux of each sensor is cut off, each inverter 26
The outputs of A, 26B, and 26C all become logic "0" (L level), and the AND circuit 27 in negative logic notation outputs logic "1".
Is output. When any one of the three sensors is not normal, the AND circuit 27 outputs “0”. The control circuit 28 outputs the output signal Eo of the AND circuit 27.
Is monitored as an error signal, and when the signal Eo becomes “1”, the next sequence is continued.

The control circuit 28 further includes an inverter 26
A, 26B, 26C each output signal A ₀, A₁, A_TwoEnter
And analyze which reference pin caused the error.
If the aera can be recovered to a degree, the recovery processing is executed.
For example, when a pre-alignment operation start command is
Actuates to move the pressure pins 4D and 4E in the KX and KY directions.
After starting the tutor (motor, air cylinder, etc.)
When the signal Eo remains "0" after a predetermined time has elapsed
Indicates that all three reference pins 4A to 4C are in an incomplete position.
The control circuit 28 arm plate P
Lift once from the top of holder 3 with 7 and place it again
The drive system 8 is controlled as described above. This allows you to play
The position when P is placed on the holder 3 again is not delicate
When the pre-alignment operation is performed again,
It may be positioned. This operation is performed by the holder 3
Up the plate P by a predetermined amount from the center
It can also be performed by a mechanism.

When the signals A ₀ and A ₂ of the sensors 25B and 25C for the reference pins 4B and 4C are "1" and the other signals A ₁ are "0", the Y direction of the plate P in FIG. It can be seen that the positioning of is not complete. In this case, the pressing pin 4D is retracted once, and then the plate P is
The actuator is controlled to press in the direction. As a result, incomplete positioning in the Y direction may be recovered.

As described above, the state of the error can be recognized to some extent by the state of the signal from each sensor. During the pre-alignment operation, air is blown from the suction surface of the holder 3 to keep the plate P moving smoothly, and when the signal Eo becomes “1”, the holder 3 is switched to suction and suction is performed by the vacuum sensor. Is confirmed, the pressing force of the two pressing pins 4D and 4E is released.

As described above, in this embodiment, since each of the reference pins 4A to 4C is installed so as to be finely movable in the positioning direction (arrows KX and KY), at the start of the pre-alignment operation, the end face (side) of the plate P is started. After the abutment with the reference pin, while the reference pin is displaced to the reference position, the spring 2
The plate end face is pressed with a force corresponding to the urging force of No. 3.

Therefore, the pressing force of the pressing pins 4D and 4E is
If the biasing force is slightly larger than each of the reference pins 4A to 4C, reliable pre-alignment is always possible,
It is not necessary to increase the pressing force of the pressing pins 4D and 4E more than necessary. FIG. 6 shows a wafer pre-alignment mechanism according to the second embodiment. Members having the same functions as those in FIG. 3 are given the same reference numerals. However, since the pre-alignment of the wafer is performed with reference to a linear flat OF provided around the wafer W, two reference pins 4B and 4C are arranged on the flat OF so as to be in contact at the same time. The reference pin 4A is arranged at a position rotated by 90 °.

Also in this embodiment, similarly to the example shown in FIG. 3, an unnecessary large pressing force is not applied to the end surface of the wafer W when the pre-alignment is achieved, and the accurate completion of the pre-alignment can be checked. Next, some modified examples of the present invention will be described with reference to FIG. FIG. 7 (A)
This is a modification of the movable member including the reference pin 4A, in which a roller serving as the reference pin 4A is pivotally supported at one end side of the movable metal fitting 32, and the movable metal fitting 32 is fixed to the fixed metal fitting 30 fixed to the holder 3 and a precision hinge. It is swingably connected via 31.

One end of the movable fitting 32 is fixed to the fixing fitting 3.
The swinging piece 30A extending from 0 restricts swinging from the state shown to the right. And the fixing bracket 30
A compression spring 33 is provided between the movable metal fitting 32 and the reference pin 4A at the pre-alignment reference position (the movable metal fitting 32).
(A position where one end of the abutment comes into contact with the locking piece 30A). Now, on the back side of the movable fitting 32, the tip of the metal adjustment screw 34 extending from the fixed fitting 30 side is arranged, and defines a reference position when the reference pin 4A is displaced during pre-alignment. That is, when the movable bracket 32 is displaced from the state shown in the figure, the displacement is locked by the back surface of the movable bracket 32 abutting on the tip of the screw 34. The screw 34 has a small pitch and is screwed through only the insulating plate 30B fixed to the fixing bracket 30 so as not to contact the fixing bracket 30. Also, a lead wire 34A electrically connected to the screw 34 is wired.

According to this embodiment, since the pre-alignment reference position of the reference pin 4A can be adjusted by fine adjustment of the screw 34, the overall pre-alignment achievement position and the accuracy can be adjusted in consideration of the substrate transfer accuracy. Can be easily optimized. FIG. 7B shows an example of a check circuit suitable for the mechanism shown in FIG. 7A. In FIG. 7A, a switch SWa () that closes when the tip of the screw 34 comes into contact with the back surface of the movable bracket 32 in FIG. SWb, SWc). In the case of FIG. 7A, since the movable bracket 32 is grounded, the power supply voltage is connected to the lead wire 34A via the resistors Ra (Rb, Rc), and the potential at the connection point is indicated by negative logic. By receiving the signal in the circuit 27, a pre-alignment completion signal Eo can be obtained.

When the fixture 30 is fixed to the holder 3 via an insulator, the fixture 30 and the movable fixture 32 are electrically floating from the ground. Therefore, a lead wire is also wired from the fixing bracket 30, the switches SWa, SWb, and SWc corresponding to each of the three reference pins are connected in series, and conduction and non-conduction of the series path are determined.
Pre-alignment completion may be checked.

In the case of a switch utilizing the contact between the tip of the screw 34 and the movable bracket 32 as shown in FIG. 7A, a minute (μm unit) metal powder may be generated by the contact. It is preferable to provide a dust prevention cover or the like.

[0029]

As described above, the substrate positioning apparatus according to the present invention comprises:
Since a movable reference member is provided to detect whether or not the positioning (pre-alignment) of the substrate has been performed correctly, the pressing force of the pressing member is smaller than the frictional force due to the contact between the mounting surface of the holding means and the substrate. Only need to be bigger,
Deformation and breakage of a part of the substrate that abuts on the pressing member can be prevented. For this reason, even if the substrate is sucked on the holding means (holder) after positioning, there is no deformation (bending, local curvature) of the substrate, and the exposure pattern does not distort the transfer pattern in the exposure apparatus. become. Further, when the substrate cannot be positioned, the error processing apparatus positions the substrate again, so that a substrate positioning error can be reduced. Further, in the method of positioning a substrate according to the present invention, the positioning of the substrate is performed again when the substrate is not positioned within the predetermined time, so that a positioning error of the substrate can be reduced.

Further, in the exposure apparatus, since the surface of the substrate is prevented from being deformed in the direction of the projection optical axis, the defocus of the pattern projection image can be reduced even if a projection optical system having a small depth of focus is used. There is. In addition, since an extremely large pressing force is not required, generation of dust due to breakage and abrasion of a part of the substrate end face can be suppressed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a conventionally used projection exposure apparatus.

FIG. 2 is a plan view showing a conventional pre-alignment mechanism.

FIG. 3 is a plan view showing a pre-alignment mechanism according to the first embodiment of the present invention.

FIG. 4 is an enlarged plan view showing a configuration around a reference pin of a pre-alignment mechanism.

FIG. 5 is a block diagram showing a configuration of a control system including a detection circuit.

FIG. 6 is a plan view showing a pre-alignment mechanism according to a second embodiment.

FIG. 7 is a diagram showing a modification of the pre-alignment mechanism and the detection circuit.

[Description of Signs of Main Parts]

 P plate W Wafer 3 Holder 4A, 4B, 4C Reference pin (roller) 4D, 4E Press pin (roller) 20 Movable lever 21 Rotary shaft 22A, 22B Lock pin 23 Tension spring 24 Light shielding plate 25, 25A, 25B, 25C Sensor 27 AND circuit (judgment circuit) 28 Control system

Claims (6)

(57) [Claims] 1. A holding means for mounting a substrate to be positioned, a plurality of reference members arranged in a predetermined positional relationship with respect to a mounting surface of the holding means, and A pressing member for pressing the substrate so as to abut against each of the reference members, and an apparatus for positioning the substrate on the mounting surface of the holding means, wherein each of the reference members is used when positioning the substrate. A plurality of movable members that are displaceably supported between a first position and a second position separated by a predetermined amount in a contact direction and are urged toward the first position by a predetermined urging force; A plurality of detectors that output a detection signal when each of the reference members is displaced from the first position to the second position by the operation of, when all of the plurality of detectors output the detection signal, Signal indicating completion of board positioning A determination circuit for generating a signal, and controlling at least the pressing member to re-execute the positioning.
An apparatus for positioning a substrate, the apparatus comprising: 2. The apparatus according to claim 1, wherein said holding means includes a suction device for sucking said substrate. 3. The substrate positioning device according to claim 1, wherein said holding means includes a release device for releasing the mounted state of said substrate on said mounting surface. Wherein said error - processing apparatus, the detection signal is a positioning device for the substrate according to any one of claims 1 to 3, wherein said performing the positioning again when not outputted within a predetermined time . 5. A reference member displaceably provided on the holder by pressing an end surface of the substrate on the holder with a pressing member.
The positioning method of a substrate for positioning the substrate against the, and moving toward the pressing member to the substrate, and detecting a position of said reference member, said substrate based on the position of the reference member Judging whether or not the substrate is positioned, and when the substrate is not positioned within a predetermined time, the substrate
Performing the positioning of the substrate again . 6. The positioning of the substrate is performed in a plurality of directions.
6. The position of the substrate according to claim 5, wherein
Placement method.