JP3180357B2 - Apparatus and method for positioning circular substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer positioning apparatus provided with a notch (orientation flat, notch) suitable for a manufacturing apparatus or an inspection apparatus used in, for example, a semiconductor device manufacturing process, and particularly to a positioning accuracy. The present invention relates to a positioning device suitable for an exposure apparatus (stepper, aligner, etc.) requiring the following.

[0002]

2. Description of the Related Art Conventionally, in an exposure apparatus and an inspection apparatus used in a semiconductor element manufacturing process, particularly in a lithography process,
The wafer is positioned with respect to the apparatus using an orientation flat (hereinafter referred to as OF) or a notch. In particular, in an exposure apparatus, alignment accuracy must be increased in accordance with high integration and miniaturization of semiconductor elements, and accordingly, there is an increasing demand for accurately positioning a wafer and mounting the wafer on the apparatus. This type of positioning device is disposed in a wafer transfer path inside the exposure device, and for example, a method of pressing a wafer against a reference member capable of contacting a circumferential portion and a notch,
Alternatively, a method is employed in which a notch is optically detected by irradiating a light beam to the peripheral portion. Here, in the former method, the wafer is brought into direct contact with the reference member, so that chipping of the wafer and peeling of the resist are liable to occur, and these adhere as foreign matter to the wafer surface to lower the yield. The method is the mainstream.

FIG. 16 is a schematic diagram showing a schematic configuration of a conventional positioning device, and FIG. 17 is a sectional view taken along the line CC of FIG. As shown in FIGS. 16 and 17, XY is movable on the base 106 via the guide member 107 in the X and Y directions.
The stage 100 is supported, and the XY stage 100
On the upper side, a Δθ stage 101 is provided so as to be able to rotate slightly about the origin O of the orthogonal coordinate system XY. Also, Δθ
A stepping motor 105 is provided on the lower surface of the stage 101 so that the axis thereof substantially coincides with the origin O. Further, a wafer chuck (turntable) 102 is fixed to the axis of the stepping motor 105, and holds the wafer W infinitely. A rotatable θ stage is formed. A vacuum suction groove 102a is formed on the surface of the turntable 102, and the space surrounded by the groove 102a and the back surface of the wafer is decompressed to suck the wafer W onto the turntable 102. Also,
The outer shape measurement sensor 103 includes a halogen lamp 108 and a lens 109, irradiates the peripheral portion of the wafer with illumination light from the back surface via a mirror 110, and projects the shadow of the wafer W onto the line image sensor 111 to thereby determine the position of the wafer edge. Is detected. Reference numeral 104 denotes a wafer transfer belt, which moves down to a position where the wafer edge reaches the center of the outer shape measurement sensor 103 and lowers, and transfers the wafer W to the turntable 102.

In the apparatus having the above structure, the distance ρ from the center of rotation of the turntable 102 to the wafer edge is detected by the outer shape measuring sensor 103 in accordance with each rotation angle while the turntable 102 is being rotated. After determining the orientation of the OF based on the
Positioning in the rotation direction (OF adjustment) within the range of the rotation angle setting accuracy of 2 (determined by the resolution of the stepping motor 105)
I do. Further, based on the above data, Δθ stage 1
After oscillating 01 to more precisely adjust the orientation of the OF,
By driving the Y stage 100, the wafer center is moved to the position (the origin O) where the rotation center of the turntable 102 was before correction. At this time, by measuring the distance ρ at three or four points (P ₁ , P ₂ , P _{3 in} FIG. 16) of the circumferential portion other than the OF, the X and Y of the XY stage 100 are measured.
A correction amount in the direction is calculated. As a result, the rectangular coordinate system X
The wafer W is accurately positioned with respect to Y without shifting two-dimensionally (including rotation).

Further, the resist layer formed on the surface of the wafer is easily peeled off at the peripheral portion, and the peeled resist adheres to the surface of the wafer as foreign matter, which causes a problem that the yield is reduced. Therefore, in order to prevent the resist from being peeled off, the wafer is rotated while irradiating the peripheral portion with exposure light using a dedicated exposure apparatus, and the peripheral portion is selectively exposed with a predetermined exposure width (about 1 to 7 mm). . Specifically, a light-emitting portion (for example, an optical fiber) that is disposed in close proximity to the peripheral portion and emits an exposure light beam, and an exposure light beam that is disposed to face the light-emitting portion across the peripheral portion and is not shielded by the peripheral portion And a light receiving unit that receives the light is integrally movable in the radial direction of the wafer. During the peripheral exposure, the light emitting unit, the light receiving unit, and the wafer are relatively moved in the radial direction in accordance with a change in the detection signal of the light receiving unit, and control is performed such that the peripheral portion is always exposed with a constant exposure width. . Recently, it has been proposed to incorporate such a peripheral exposure apparatus into the above-described positioning apparatus.

[0006]

However, in the prior art as described above, since the Δθ stage 101 is disposed on the XY stage 100, the XY stage 1
The weight load of 00 increases. Therefore, there is a problem that the XY stage is enlarged, the driving speed is reduced, and the servo following performance is reduced. Further, when a large stage having such a heavy weight is driven during the peripheral exposure or the inspection, there is a problem that the alignment accuracy and the inspection accuracy may be reduced due to the vibration generated by the movement of the stage.

When a wafer is attracted to a wafer chuck, the center of the wafer chuck and the center of the wafer chuck cannot be accurately matched. For this reason, when detecting the wafer edge using the outer shape measurement sensor, the wafer is rotated eccentrically, and the light receiving surface of the line image sensor needs to have a certain length in the radial direction of the wafer. For example, O
In the case of a 6-inch wafer provided with F, the length of the light receiving surface is usually required to be about 6 mm in the radial direction of the wafer in the OF section, and this is taken into account by the amount of deviation (eccentricity) between the wafer center and the chuck center. In addition, in practice, the length of the light receiving surface needs to be about 20 mm. Therefore, a conventional analog sensor has a problem that high-precision positioning cannot be achieved due to low resolution and linearity, and uneven illumination of a halogen lamp. Also, the CCD has a sensor resolution of several μm.
m, and there is a problem that the detection time may be longer depending on the relationship of the sweep frequency at the time of detection.

Further, in order to improve the positioning accuracy in the apparatus having the above structure, a high-precision encoder or a stepping motor must be used for rotationally positioning the turntable. There is also a problem that it becomes heavy. In addition, in order to perform peripheral exposure with the above-described dedicated exposure apparatus, a servo operation for newly driving the light emitting unit and the light receiving unit integrally so that the peripheral portion is always exposed with a fixed exposure width. Means must be provided for Further, by performing an edge exposure with an optical system for equalizing the light intensity distribution of the exposure light beam and, for example, an exposure light beam having a large numerical aperture (NA) emitted from an optical fiber, the exposure width can be made smaller than a predetermined exposure width. If an optical system for reducing the numerical aperture of the exposure light beam is provided in order to suppress the exposure light beam from flowing further inward (center side of the wafer) and a part of the resist being removed in the developing process, that is, to suppress so-called film loss, the weight of the light emitting portion is increased. And the servo condition may become severe. Further, there is a problem that the servo condition in the OF is stricter than that in the circumferential portion, and the exposure width in the OF varies greatly.

The present invention has been made in view of the above points, and it is a first object of the present invention to provide a positioning apparatus capable of positioning a circular substrate with high accuracy and high speed without lowering the yield or throughput. The purpose is. Also,
A second object of the present invention is to obtain a positioning device that can position a circular substrate with high accuracy and high speed, and also has a peripheral exposure function that can control an exposure width in a notch with the same accuracy as that of a circumferential portion.
The purpose is.

[0010]

In order to solve such a problem, in the apparatus for positioning a circular substrate according to the first aspect of the present invention, a predetermined notch [OF, notch] is defined with respect to an orthogonal coordinate system XY. For positioning a circular substrate [wafer W] provided with a first rotation stage [Δθ] capable of minute rotation about a coordinate origin O of an orthogonal coordinate system XY.
Stage 1]; a linear motion stage [X, Y provided on the first rotary stage and movable two-dimensionally in the orthogonal coordinate system XY.
Stages 10 and 15]; provided on a linear motion stage;
A second rotary stage [turntable 18] that can hold the circular substrate and can rotate at least one or more rotations; a rotation center T _{C of} a peripheral portion of the circular substrate during rotation of the second rotary stage.
A non-contact type first detector [analog sensor 20] for non-contactly detecting information representing a change in the displacement amount from the sensor; based on the detected information, a notch in the circular substrate is defined in a rectangular coordinate system XY. First positioning control means [first signal processing system 32, stage controller 35, and main control system 36] for controlling the stop of the rotation of the second rotary stage so as to be set in the above predetermined direction [X direction]. A second non-contact type detector having at least three predetermined detection points in a rectangular coordinate system XY so as to detect at least three positions on the peripheral portion of the circular substrate in a non-contact manner. [Spot sensors 24, 27, 28]; after the notch is set in a predetermined direction by the first positioning control means, based on the detection information at at least three detection points of the second detector, Linear stage and 1st A second positioning control means [second signal processing system 33, stage controller 35, and main control system 36], whereby the center of the circular substrate is almost always positioned with respect to the coordinate origin O. Positioning is performed in a fixed relationship, and the residual rotation error (Δα or Δβ) of the circular substrate with respect to the rectangular coordinate system XY is made substantially zero. According to a second aspect of the present invention, when the linear motion stage is positioned at a predetermined neutral position, the rotation center of the second rotary stage is at the coordinate origin O.
It is configured to substantially match with. 4. The circular substrate positioning device according to claim 3, wherein the second positioning control means calculates a residual rotation error based on detection information from the second detector [main control system 36]; And a control circuit [main control system 36] for controlling the first rotary stage in accordance with the residual rotation error calculated by the arithmetic circuit.
According to a fourth aspect of the present invention, the control circuit finely moves the linear motion stage to make the center of the circular substrate substantially coincide with the coordinate origin O, and then finely moves the first rotary stage to reduce the rotation error. It is almost zero. According to a fifth aspect of the present invention, there is provided a positioning device for a circular substrate, wherein the control circuit has a servo circuit for servo-controlling the linear motion stage based on detection information from the second detector, and the servo circuit servo-controls the linear motion stage. While slightly moving the linear motion stage or the first rotary stage, the center of the circular substrate and the coordinate origin O are almost coincident, or the residual rotation error is almost zero. In the circular substrate positioning apparatus according to the sixth aspect, the control circuit calculates the diameter of the circular substrate together with the residual rotation error based on the detection information from the second detector, and the control circuit detects the information on the calculated diameter and detects the diameter. The linear motion stage is finely moved in accordance with the information to make the center of the circular substrate substantially coincide with the coordinate origin O, and then the first rotary stage is finely moved to make the residual rotation error almost zero. Claim 7
In the circular substrate positioning apparatus described above, the second detector emits an illumination light beam in a wavelength range insensitive to the resist layer of the circular substrate [a light projector 25]; The light-emitting device includes a light-receiving device [photoelectric detector 26] that is disposed substantially opposite to the light-emitting device, and the light-emitting device emits a parallel light beam that forms a minute spot at the periphery of the circular substrate. The positioning device for a circular substrate according to claim 8, wherein the positioning device for the circular substrate includes a light emitting unit [light emitting unit 42] for emitting an exposure light beam having a characteristic of sensitizing a resist layer of the circular substrate, and a peripheral portion of the circular substrate. Exposure means [peripheral exposure section 40] having a light receiving section [light receiving section 44] disposed so as to be substantially opposed to the light emitting section, and exposure conditions using an exposure light beam based on information on an appropriate exposure amount of the resist layer. And an exposure control means [main control system 36] for determining at least one of the rotation speed of the circular substrate by the second rotation stage, and the exposure control means substantially matches the center of the circular substrate with the coordinate origin O and rotates the circular substrate. After the residual error becomes substantially zero, the peripheral portion of the circular substrate is controlled while controlling the linear motion stage so that the exposure light beam irradiates the peripheral portion within a predetermined range in the radial direction of the circular substrate. And selectively exposing the resist layer. The positioning device according to claim 9 of the present invention is a positioning device for positioning a circular substrate [wafer W] having a notch [OF, notch] of a predetermined shape in an orthogonal coordinate system XY. [Ejector 2] that emits substantially parallel light beams that become minute spots at at least three places on the peripheral edge of
5], and a detection device [photoelectric detector 26] that is disposed substantially opposite to the emission device and detects a parallel light beam. The positioning device according to claim 10, wherein the stage (X stage 10, Y stage 15) that moves in the orthogonal coordinate system XY while holding the circular substrate, and control that controls the position of the stage based on the detection result of the detection device. Device [Main control system 3
6]. The positioning method according to claim 11 of the present invention is a positioning method for positioning a circular substrate [wafer W] having a notch [OF, notch] of a predetermined shape with respect to a rectangular coordinate system, Substantially parallel light flux S that becomes a minute spot at at least three places on the periphery
The method includes a step of emitting P and a step of detecting the position of the circular substrate by detecting the parallel light flux SP. According to a twelfth aspect of the present invention, the positioning method includes the step of adjusting the position of the circular substrate based on the detection of the position of the circular substrate.
In the positioning method according to the thirteenth aspect, the position of the circular substrate is detected by using a light beam IL different from the substantially parallel light beam which becomes the minute spot before the substantially parallel light beam which becomes the minute spot is emitted to the peripheral portion of the circular substrate. Includes steps.

[0011]

In the apparatus for positioning a circular substrate according to the first to eighth aspects of the present invention, since the first rotary stage is disposed below the linear motion stage, the inconvenience relating to the weight load of the linear motion stage is eliminated. Further, when correcting the residual rotation error of the circular substrate, the second detector detects the peripheral portion using the minute spot light (parallel light beam). Therefore, it is possible to detect the peripheral edge with higher accuracy than an image sensor (such as a CCD), and it is not necessary to mount a high-precision encoder or a stepping motor on the second rotary stage.

Further, the first rotary stage is constituted so as to be capable of minute rotation about the coordinate origin of the orthogonal coordinate system as a center, and after the above-mentioned origin and the center of the circular substrate are substantially coincident with each other, the first rotary stage is swung. Thus, the residual rotation error of the circular substrate is substantially zero. For this reason, even if the first rotary stage is swung, the center of the circular substrate does not deviate from the origin, so that the operation of aligning the center of the circular substrate with the origin again becomes unnecessary, and the throughput and the positioning accuracy decrease. Can be prevented.

Further, in the positioning apparatus of the present invention, the linear motion stage is used as a drive source for the servo operation of the peripheral edge exposure, and the exposure means (exposure light beam) and the circular substrate are relatively moved in the radial direction. . For this reason, there is no need to newly provide a unit for moving the exposure unit in the radial direction, so that an optical system for making the light intensity uniform can be easily added in the light emitting unit. In addition, when exposing a linear notch, for example, if the stroke in one direction (Y direction) of the translation stage is increased, the translation stage can be moved one-dimensionally along the notch. The exposure width in the notch can be controlled with the same accuracy as the circumference. In the positioning device according to the ninth aspect of the present invention, since the emission device emits a parallel light beam that becomes a minute spot light at three locations on the peripheral portion of the circular substrate, and the detection device detects the parallel light beam,
High-precision edge detection becomes possible. In the positioning device according to the tenth aspect, since the control device controls the position of the stage based on the detection result of the detection device, the circular substrate can be positioned with high accuracy with respect to the rectangular coordinate system. The positioning method according to claims 11 to 13 of the present invention emits a parallel light beam that becomes a minute spot light at three positions on the peripheral edge portion of the circular substrate, detects the position of the circular substrate based on the parallel light beam, and Since the substrate is positioned, the circular substrate can be positioned with high accuracy with respect to the rectangular coordinate system.

[0014]

FIG. 1 is a plan view showing a schematic configuration of a positioning apparatus according to a first embodiment of the present invention, and FIG.
In this embodiment, a positioning device suitable for a wafer having an OF (linear notch) will be described. It is assumed that the positioning device of the present embodiment is incorporated in a stepper, particularly in a wafer transfer unit.
For simplicity of description, an orthogonal coordinate system XY is defined in FIG. 1, and finally, the wafer center coincides with the origin O of the orthogonal coordinate system XY, and the rotation error of the wafer with respect to the orthogonal coordinate system XY is reduced. Zero, that is, the OF direction (edge direction) is a predetermined OF alignment direction (for example, X direction)
It is assumed that the wafer is positioned so as to be parallel to.

In FIG. 1 and FIG. 2, a Δθ stage 1 is supported on a base 2 via a base 3 and a guide bearing 4, and its rotation center is at an origin O of a rectangular coordinate system XY.
It is installed so that it almost matches. Further, by driving the lever 7 fixed to the Δθ stage 1 with the Δθ motor 5 and the feed screw 6, the linear motion is converted into a rotary motion, and for example, it is possible to minutely rotate around the origin O within a range of ± 2 °. Be composed. The rotation amount of the Δθ stage 1 is fed by a digital micrometer 8 which is disposed opposite the Δθ motor 5 and the feed screw 6 with the lever 7 interposed therebetween and abuts the side surface of the lever 7 with a resolution of, for example, about 0.5 μm. It is detected by measuring the feed amount of the screw 6.

An X stage 10 that moves along a guide member 9 extending in the X direction is disposed on the Δθ stage 1, and further moves along a guide member 13 that extends in the Y direction on the X stage 10. Y stage 15 is arranged. The X and Y stages 10 and 15 are driven by stepping motors (X motor) 11 and (Y motor) 14,
The position is detected by the digital micrometers 12 and 16 with a resolution of, for example, about 0.5 μm. A θ stage (turntable) 18, which holds the wafer W and can rotate indefinitely, is provided on the Y stage 15, and the turntable 18 is fixed to a lower portion of the X stage 10 via a motor holder 55 via a θ motor 17 rotates at a predetermined speed.

Although not shown, the θ motor 17 is also provided with a means (an encoder 31 described later) for detecting the amount of rotation of the turntable 18. On the surface of the turntable 18, a concave portion extending in the radial direction from the center and an annular concave portion (vacuum suction groove) 18a are formed, and a sleeve shape communicating with an intake hole (not shown) provided on the bottom surface of the groove 18a. By connecting the hole 19 to a vacuum source and reducing the pressure, the space surrounded by the back surface of the wafer W and the groove 18a becomes negative pressure, and the wafer W is attracted to the turntable 18.

The transfer arm (fork) 30 sucks and holds the wafer W from the back surface by a vacuum suction surface 29 formed at the tip, and moves in the horizontal direction (X direction) on the paper by a guide mechanism (not shown). It is configured to be possible. Therefore, the wafer W stored in the loader cassette (wafer carrier) is carried out by the fork 30, is placed on the fork 30, moves to above the turntable 18, and the fork 30 and the turntable 18 move in the Z direction. The relative movement (the transfer arm 30 is lowered, or the turntable 18 is raised), and the wafer W is turned on the turntable 1
8 to be absorbed.

At this time, the deviation amount of the wafer center from the rotation center (origin O) of the Δθ stage 1 is, for example, ± 5 mm.
And is delivered to the turntable 18. If the rotation center (Tc described later) of the turntable 18 is displaced from the rotation center (origin O) of the Δθ stage 1, the deviation amount may be larger than ± 5 mm. Positioning may be started in this state, but for that purpose, X, Y
The moving stroke of the stages 10, 15 must be lengthened. Therefore, in this embodiment, the X and Y stages 10,
When 15 is at a predetermined neutral position, for example, at the center of the movement stroke, the rotation center of the Δθ stage 1 (origin O)
And the rotation center of the turntable 18 are substantially coincident with each other, and transfer of the wafer W is performed at the neutral position.

The X and Y coordinate values of the X and Y stages 10 and 15 at the neutral position are both set to zero, and the detected values of the digital micrometers 12 and 16 at this time are read and stored. The analog sensor 20 detects a fixed point of a change in the position of the wafer edge from the rotation center Tc of the turntable 18 due to the rotation of the wafer, and is used for the general OF adjustment described later. In FIG. 1, the analog sensor 20 has a slit-shaped light receiving surface (not shown) on the X axis toward the origin O (extending in the radial direction of the wafer).
Although they are arranged, they may be arranged anywhere on the circumference corresponding to the wafer size centered on the origin O (the rotation center of the Δθ stage 1). As shown in FIG. 2, the analog sensor 20 includes illumination light IL having a wavelength that does not expose the resist layer.
, A lens 22 that converts the illumination light IL into a parallel light beam, and a photoelectric detector 23 (position sensor, CCD linear sensor, or the like) arranged to face the light source 21 across the wafer peripheral portion. Be composed.

As shown in FIG.
The (photoelectric detector 23) outputs a photoelectric signal corresponding to the intensity of the received illumination light IL to the first signal processing system 32, where rotation angle information from the encoder 31 is also input, and the unit rotation angle of the turntable 18 is output. A change in the position of the wafer edge is detected every (for example, 0.5 °). Therefore, an A / D converter and a memory for digitally sampling a signal waveform from the analog sensor 20 in response to an up / down pulse from the encoder 31 are provided inside the first signal processing system 32.

The spot sensors 24, 27 and 28 are used to detect the position of the wafer edge by moving the X and Y stages 10 and 15, and to detect the positioning errors (ΔX, ΔY, Δα) described later. Used for In FIG. 1, the spot sensor 24 is disposed on the X axis substantially symmetrically with respect to the origin O and the analog sensor 20, and the spot sensors 27 and 28 are disposed substantially symmetrically with respect to the Y axis and arranged in the X direction. Naturally, they are arranged according to the size standard of the wafer to be positioned. As shown in FIG. 2, the spot sensor 24 is a projector 25 that generates a parallel light beam SP (non-exposure wavelength) that becomes a minute spot (for example, about 50 μm in diameter) on the wafer surface.
And a photoelectric detector 26 disposed opposite to the light projector 25 with the wafer peripheral portion interposed therebetween.

In FIG. 3, the second signal processing system 33 has an A /
A spot sensor 24 having a D converter, a memory, etc.
The photoelectric signal from the (photoelectric detector 26) and the position information from the digital micrometer (Digi-My) 12 are input, and the position when the wafer edge crosses the minute spot light SP is detected. Here, the second signal processing system 33 may detect the edge position based on the presence or absence of the photoelectric signal from the spot sensor 24. However, since the beam diameter of the minute spot light cannot be ignored accurately, the X stage 10 After the photoelectric signal is sampled and converted into a digital value for each unit movement amount (for example, 0.5 μm), the edge position is detected by a predetermined arithmetic processing. Since the spot sensors 27 and 28 have exactly the same configuration and function, the description is omitted here.

Here, the spot sensor 24 may be arranged anywhere on the circumference (except for the intersection with the vertical bisector of the spot sensors 27 and 28). On the other hand, the spot sensors 27 and 28 may be arranged along the OF alignment direction so that the interval 1 is shorter than the length of the OF. Further, the spot sensors 27 and 28 move, for example, in the movable range (rotation amount) of the Δθ stage 1 with respect to the OF alignment direction.
May be tilted by a small angle according to. In this case, if the OF is driven into the spot sensors 27 and 28 and then the [Delta] [theta] stage 1 is rotated by the above-described tilt angle, the precise OF adjustment (described later) can be similarly performed.

In FIG. 3, the main control system 36 calculates a positioning error (ΔX, ΔY, Δα) of the wafer W based on the detection signal of the second signal processing system 33, and then sends a predetermined control command to the stage controller 34. The stage controller 34 drives the X and Y motors 11 and 14 and the Δθ motor 5 to execute wafer positioning. In addition, based on the detection signal of the first signal processing system 32, a command corresponding to the drive amount of the θ motor 17 at the time of the approximate OF adjustment is output to the stage controller 35.

Next, the positioning operation of the apparatus having the above configuration will be described with reference to FIG. FIG. 4 is a diagram showing a positioning sequence of the OF-equipped wafer. First, the wafer W is Δθ
The shift amount of the wafer center Wc with respect to the center of rotation (origin O) of the stage 1 is transferred to the turntable 18 while being kept within ± 5 mm (FIG. 4A). Then, while rotating the turntable 18, the main control system 36 rotates the illumination light I which is not blocked by the wafer W in the analog sensor 20.
L is photoelectrically detected.

The first signal processing system 32 responds to an up / down pulse from the encoder 31 to
, And converts each sampled value into a digital value and stores it in a memory (not shown) in address order. As a result, signal waveform data corresponding to the profile of the wafer edge as shown in FIG. 5A is obtained in the memory of the first signal processing system 32. FIG. 5A shows the relationship between the level (voltage) V of the photoelectric signal and the rotation angle θ, that is, a change in the position of the wafer edge from the rotation center Tc due to the rotation.

Further, the first signal processing system 32 converts the waveform data shown in FIG. 5A into the waveform data shown in FIG. FIG.
In (b), the zero cross point θ ₁ (differential value) is the rotation angle corresponding to the OF center. Then, the first signal processing system 32 uses the waveform data stored in the memory to determine the rotation angle value θ ₁ of the zero cross point between the maximum value (peak value) and the minimum value (bottom value) on the waveform. Ask for.

Next, the main control system 36 while monitoring the output of the encoder 31, is rotated counterclockwise the turntable 18 so that the rotation angle value theta ₁ is obtained in the paper, the spot sensor 27, 28 For OF. As a result, the rotational deviation (inclination) of the OF with respect to the line segment (X direction) connecting the spot sensors 27 and 28 is suppressed within a predetermined allowable range (for example, about ± 1 °), and the OF with respect to the spot sensors 27 and 28 is Fit (Overview O
F adjustment) is completed (FIG. 4B).

In this embodiment, since the turntable 18 is used only for the approximate OF adjustment, a high-precision θ motor or encoder is not required, and the portion above the Y stage 15 can be reduced in weight. For example, the resolution of the encoder 31 and the stop accuracy of the θ motor 17 are set to 0.5 ° and ± 1 °, and a lightweight encoder or motor satisfying these conditions may be used. When the stepping motor is used as the θ motor 17, a counter for counting the number of drive pulses to the stepping motor and a memory for inputting the count value of the counter as an address value are provided.
If the 0 photoelectric signal is digitally sampled through an A / D converter, the same waveform data as in FIG. 5A can be obtained. In this case, an encoder is not required, and the weight can be further reduced.

After the above-described approximate OF adjustment is completed, the main control system 36 finely moves the X stage 10 and detects the position of the wafer edge in the X direction by the spot sensor 24. Here, when the X stage 10 is slightly moved, a photoelectric signal as shown in FIG. 6A is output from the spot sensor 24. FIGS. 6 (a) represents the relationship between the scan position of the signal level (voltage) V and X-direction, the second signal processing system 33 and the waveform processing the photoelectric signal by a predetermined slice level SL _1, the wafer edge The position (coordinate value X ₁ ) is calculated. Then, the main control system 36 sets the wafer W to the above-mentioned coordinate value X ₁ using the X Digimy 12, that is, drives the wafer edge into the spot sensor 24. As a result, the positioning of the wafer W in the X direction is completed (FIG. 4C).

Next, the main control system 36 detects the position of the wafer edge in the Y direction using the spot sensors 27 and 28 in the same operation as the above-described positioning in the X direction. FIG.
(B) and (c) show the photoelectric signals from the spot sensors 27 and 28, and the second signal processing system 33 performs waveform processing on these photoelectric signals at the slice levels SL ₂ and SL ₃ ,
An edge position (coordinate values Y ₁ , Y ₂ ) of the OF is detected. Then, the main control system 36 drives the OF into the spot sensors 27 and 28 using the Y digitizer 16, that is, when the Y digitizer 16 detects the coordinate value (Y ₁ + Y ₂ ) / 2, Y
The motor 14 is stopped. As a result, the positioning of the wafer W in the Y direction is completed (FIG. 4D). By the processing up to this point, the center of rotation (origin O) of the Δθ stage 1 substantially coincides with the wafer center Wc.

Next, the main control system 36 calculates the spot sensor 2 from the coordinate values Y ₁ and Y _{2 in} order to perform precise OF adjustment.
The inclination of the OF with respect to 7, 28, that is, the orthogonal coordinate system XY
, The residual rotation error Δα of the wafer W is calculated, and the Δθ stage 1 is oscillated while monitoring the measurement value of the digitizer 8 to correct the residual rotation error Δα to substantially zero. Here, since the interval l between the spot sensors 27 and 28 is a known dimension (design value), the residual rotation error Δα can be obtained by the calculation of Δα = (Y ₁ −Y ₂ ) / l. As a result, the precision OF alignment of the wafer W is completed (FIG. 4E), and the positional deviation amounts ΔX and ΔY
And the residual rotation error Δα are both substantially zero, and the positioning of the wafer W is completed. Note that the coordinate value Y is used for precise OF adjustment (that is, calculation of the residual rotation error Δα).
_1, without using a Y _2, may be configured to detect the edge position of the re-OF and fine movement of the Y stage 15.

As described above, in the present embodiment, the wafer can be positioned with high accuracy, and the center of rotation of the Δθ stage 1 and the wafer center Wc are substantially coincident with each other prior to the precise OF alignment. The wafer W is not displaced in the X and Y directions due to the OF alignment (rotation of the residual rotation error Δα). By the way, in the above embodiment, after the wafer edge is driven into the spot sensor 24 for positioning in the X direction, the spot sensor 27,
Although the positioning in the Y direction is performed by 28, the order may of course be reversed. However, assuming that positioning in the X direction is performed prior to detection of the OF edge position (coordinate values Y ₁ , Y ₂ ), the distance l between the spot sensors 27 and 28 for positioning in the Y direction and the rotation direction is assumed. Can be spread out in advance, and there is an advantage that the detection accuracy of the residual rotation error Δα is improved. Also,
In the above embodiment, the photoelectric signal from the spot sensor is digitally sampled for each unit movement amount of the X and Y stages, and then the waveform processing is performed at a predetermined slice level to determine the position of the wafer edge. When a predetermined voltage value (for example, a voltage value corresponding to the slice level in FIG. 6) is reached, the position of the wafer edge may be obtained by latching the output value of the digitizer (counter).

Further, as described above, the deviation amount of the wafer center from the rotation center (origin O) of the Δθ stage 1 is ±
The wafer W is kept within 5 mm and the turntable 18
Therefore, when the positioning in the Y direction is performed as shown in FIG. 4D, the wafer edge may come off from the spot sensor 24. Further, due to manufacturing tolerances of the wafer, for example, outer shape tolerance (approximately ± 0.5 mm in diameter) and dimensional tolerance of OF (approximately 2.5 mm), the rotation center of the Δθ stage 1 (original origin) prior to precise OF alignment. O) and the designed wafer center are almost the same. For this reason, the actual wafer center does not exactly coincide with the origin O, and the wafer W is displaced in the X and Y directions with the precise OF alignment.
The wafer edge can deviate from 4, 27, 28. Therefore,
After finishing the precision OF alignment, X and Y stages 10, 15 again
It is desirable to detect the position of the wafer edge by finely moving the wafer edge and drive the wafer edge to the spot sensors 24, 27 and 28.

Here, if the edge of the wafer is driven again with respect to the spot sensor after the completion of the precise OF alignment, the positioning time for one wafer naturally becomes long. Therefore, in the above embodiment, the positioning in the X direction (FIG. 4)
When (c)) ends, the main control system 36 starts servo control of the X stage 10 according to the photoelectric signal from the spot sensor 24. That is, the main control system 36 sets the level of the photoelectric signal from the spot sensor 24 to the same voltage value as the slice level SL ₁ (FIG. 6A) used for calculating the wafer edge position (coordinate value X ₁ ), for example. So that
The X stage 10 is finely moved by the stage controller 35. As a result, the positioning in the Y direction (FIG. 4D)
Is performed, the wafer edge does not deviate from the spot sensor 24, that is, the positioning accuracy in the X direction does not decrease. The main control system 36 previously obtains the level (voltage value) of the photoelectric signal output when the illumination light beam SP from the light projector 25 constituting the spot sensor 24 enters the photoelectric detector 26 without being interrupted by the wafer edge. In the servo control as described above, the X stage 10 may be driven in accordance with the level of the photoelectric signal from the spot sensor 24 with reference to a value of approximately 1/2 of this voltage value.

Further, even if the precise OF alignment is performed while the X stage 10 is servo-controlled, the wafer W
Is displaced in the Y direction, and the wafer edge may deviate from the spot sensors 27 and 28. Therefore, when performing the positioning in the Y direction (FIG. 4D), the main control system 36 slightly moves the Y stage 15 to position the wafer edge (coordinate values Y ₁ , Y
_{After 2} ) is obtained, the wafer edge (OF) is driven into the spot sensor 27 (or 28) based on the detected value. Then, at the time when the driving of the wafer edge in the Y direction is completed, the servo control of the Y stage 15 is started according to the photoelectric signal from the spot sensor 27 by the same operation as described above. That is, the main control system 36 sets the level of the photoelectric signal from the spot sensor 27 to the same voltage value as the slice level SL ₂ (FIG. 6B) used for always calculating the wafer edge position (coordinate value Y ₁ ). The Y stage 15 is finely moved by the stage controller 35 so that As a result, precision OF alignment (FIG. 4)
(E)), the wafer edge is spot sensor 2
7, that is, the positioning accuracy in the Y direction does not decrease.

Further, if the actual wafer center does not exactly coincide with the origin O due to wafer manufacturing tolerance, and a positioning error exceeding a predetermined allowable accuracy (generally, about ± 15 μm) may be left. As shown in FIG. 7, the spot sensors 37 and 38 for measuring the diameter (the same configuration as the spot sensor 24) are arranged substantially symmetrically with respect to the X axis passing through the origin O. Then, in the above embodiment, the Y stage 15 is finely moved after the positioning is completed, and the spot sensors 24, 37, and 38 are moved.
To detect the position of the wafer edge. Thereafter, the actual wafer diameter is determined from the three coordinate values, and the X and Y stages 10 and 15 are finely moved again according to the diameter. As a result, the origin O and the actual wafer center can be accurately matched, and a decrease in positioning accuracy due to the above-mentioned tolerance can be prevented.

In the above embodiment, when positioning the wafer W in the Y direction (FIG. 4D), the spot sensor 2
If the position of the wafer edge is also detected by 4, 37 and 38, the actual wafer center and the origin O can be accurately matched before the precise OF alignment, and the Y stage 15 is again moved for diameter measurement. There is no need for fine movement.

Here, the interval 1 between the spot sensors 27 and 28 may be determined in accordance with the approximate OF alignment accuracy, that is, the stop accuracy of the θ motor 17 and the detection resolution of the encoder 31 and the analog sensor 20. Further, the movement strokes of the X and Y stages 10 and 15 are dependent on the variation in the position of the wafer taken out of the wafer carrier on the fork 30 and the accuracy of wafer transfer between the fork 30 and the turntable 18 (normally ± (Approximately 5 μm), and the amount of variation (± 5 mm), which is determined by the overall OF alignment accuracy. Furthermore, the movable range of the Δθ stage 1 (that is, the moving stroke of the feed screw 6) may be determined according to the approximate OF alignment accuracy, and in this embodiment, may be set to about ± 1.5 to 2 °. If the accuracy of the approximate OF alignment is set to be high, the movable range of the Δθ stage 1 can be relatively small, and the interval 1 between the spot sensors 27 and 28 can be widened. Big and heavy. Therefore, it is actually desirable to determine the movable range of the Δθ stage 1 in consideration of the balance between the two. Further, the approximate OF alignment accuracy does not need to be ± 1 °, and the angle is set such that when the Y stage 15 is slightly moved after the approximate OF alignment is completed, the OF crosses the minute spot light of the spot sensors 27 and 28 almost simultaneously. It should be done.

Now, in the first embodiment, X,
Y-stages 10 and 15 are finely moved, and spot sensors 24,
By detecting the position of the wafer edge by means of 27 and 28 (FIG. 6), positioning in the X and Y directions and precise OF alignment (FIGS. 4C to 4E) have been performed. However,
Even if the position of the wafer edge is not accurately determined as described above, while monitoring the photoelectric signals from the spot sensors 24, 27, and 28, for example, each signal level becomes a predetermined voltage value (FIG. 6).
The X and Y stages 10, 15 and the Δθ stage 1 are finely moved so as to be at the middle slice level SL _{1 to} SL ₃ ) so as to drive the wafer edge to the spot sensors 24, 27, 28. You may. In this case, there is no need to particularly provide position detectors for the X, Y and Δθ stages, and there is an advantage that the weight of the apparatus can be reduced. In addition, if the above configuration is adopted, a position detector (such as a digitizer, an interferometer, etc.) is not required. However, since the X and Y stages 10 and 15 are actually set at the neutral position, the position detector is used. (The detection accuracy may be low).

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 8 is a plan view showing a schematic configuration of a positioning device according to the present embodiment. In the present embodiment, a positioning device suitable for a wafer having a notch will be described. The members having the same functions and functions as those of the device of the first embodiment (FIG. 1) are denoted by the same reference numerals. As is clear from FIG. 8, in this embodiment, the spot sensors 24, 27, 28
The only difference is the arrangement.

As shown in FIG. 8, the spot sensor 24 is disposed on the Y axis, and the spot sensors 27 and 28 are substantially symmetric with respect to the Y axis and at a predetermined angle (45 in the figure) from the Y axis.
°) is arranged only inclined. Note that the three sets of spot sensors are divided into one set and two sets with respect to the X axis (or Y axis), and the two sets are opposed (not necessarily symmetrical) across the Y axis (X axis). In this case, the notch is driven by a set of spot sensors (not necessarily on the X or Y axis).

Next, the positioning operation of the apparatus according to this embodiment will be described with reference to FIG. FIG. 9 is a diagram showing a positioning sequence of a notched wafer. Here, FIG.
The operations shown in FIGS. 4A to 4D correspond to the first embodiment (FIG. 4A).
To (d)), and will be briefly described here. By the way, after the wafer W is transferred from the fork 30 to the turntable 18 (FIG. 9A), the rotation notch 50 with respect to the Y-axis is, for example, within about ± 1 ° by the approximate notch alignment by the analog sensor 20. And is driven into the spot sensor 24 (FIG. 9).
(B)). And the main control system 36 is the X, Y stage 1
0 and 15 at the same time, and the spot sensor 28 and the origin O
The wafer W is slightly moved in a direction along a line segment connecting (a direction inclined approximately 45 ° with respect to the orthogonal coordinate system XY). The second signal processing system 33 performs a waveform process on the photoelectric signal of the spot sensor 28 to calculate a two-dimensional position of the wafer edge, and the main control system 36 uses the X and Y digitizers 12 and 16 to move the wafer W to the above coordinate values. , That is, the wafer edge is driven into the spot sensor 28 (FIG. 9C). Similarly, the wafer edge is driven into the spot sensor 27 (FIG. 9).
(D)).

As a result, the wafer center Wc and the origin O (Δ
the rotation center of the θ stage 1) and the deviation Δ
X and ΔY are suppressed to almost zero, and the positioning in the X and Y directions is completed. Next, the main control system 36 finely moves the X stage 10 to perform precise notch alignment (FIG. 9E), and relatively moves the notch 50 and the minute spot light SP of the spot sensor 24 (FIG. 10A). )). As a result, the spot sensor 24 10 outputs a photoelectric signal (b), the second signal processing system 33 performs waveform processing by the slice level SL ₄ the photoelectric signal edge positions (coordinate values X _2,
X ₃ ) is detected. Note that the coordinate value X in FIG.
₀ is the stop position (substantially on the Y axis) of the X stage 10 when the positioning in the X and Y directions is completed. Then, the main control system 36 calculates the inclination of the notch 50 with respect to the Y axis from the coordinate values X ₂ and X ₃ , that is, the residual rotation error Δβ of the wafer W with respect to the orthogonal coordinate system XY as shown in FIG. It is calculated from Equation 1 shown below. Here, Wr is the radius of the wafer W.

[0046]

(Equation 1) Thereafter, the main control system 36 oscillates the Δθ stage 1 to execute precise notch alignment, and corrects the residual rotation error Δβ to substantially zero. As a result, the displacement amounts ΔX and ΔY of the wafer center Wc with respect to the origin O of the rectangular coordinate system XY and the residual rotation error Δβ with respect to the rectangular coordinate system XY become substantially zero,
The positioning of the wafer W ends. In this embodiment, the wafer center Wc with respect to the origin O is also associated with the precision notch alignment.
There is no deviation.

As described above, in this embodiment, the X stage 10 is finely moved at the time of precise notch alignment. X
Although sufficient accuracy can be obtained with the stage 10, it is desirable to swing the Δθ stage 1 when the setting accuracy of the approximate notch alignment is poor or when it is necessary to perform the precise notch alignment with higher accuracy. At this time, if the left and right edge positions of the notch 50 detected by the second signal processing system 33 (the rotation angles of the Δθ stage 1) are θ ₂ and θ ₃ ,
The Δθ motor 5 may be stopped when the Δθ digitizer 8 detects a value corresponding to (θ ₂ + θ ₃ ) / 2.

Further, as shown in FIG. 11, the spot sensor 39 is arranged substantially symmetrically with respect to the X axis with respect to the spot sensor 28, the actual wafer diameter is obtained using the spot sensors 27, 28 and 39, and the X and Y stages are again measured. Fine movement of the reference numerals 10 and 15 makes it possible to accurately match the actual wafer center with the origin O. When the positioning in the X and Y directions is completed (FIG. 9D), the spot sensor 27
The actual wafer diameter is measured by 28 and 39, and as shown in FIG. 11, the spot sensor 24 (spot light SP)
An offset in the Y direction is given to the wafer W according to the diameter so as to be substantially at the center of the notch in the direction. After that, if a sequence that performs precision notch alignment is adopted, it is possible to always detect a fixed position of the notch, for example, the position of the substantially central edge where chipping or dripping is unlikely to occur, and the residual rotation error due to chipping or dripping etc. A decrease in the detection accuracy of Δβ can be prevented.

When the wafer edge is driven into the spot sensor 27 (FIG. 9D) or when the precision OF
When performing the alignment (FIG. 9E), the X and Y stages 10 and 15 are servo-controlled based on the photoelectric signals from the spot sensors 27 and 28 by the same operation as the first embodiment,
It is desirable that the wafer edge does not deviate from the spot sensors 27 and 28. Further, even if the position of the wafer edge is not accurately determined as in the above-described embodiment, while monitoring the photoelectric signals from the spot sensors 27 and 28 as in the first embodiment, for example, each signal level becomes a predetermined voltage value. Alternatively, the X and Y stages 10 and 15 may be finely moved so as to drive the wafer edge to the spot sensors 27 and 28. In this embodiment, since the notched wafer is positioned, FIG.
As can be seen from (a), even if the wafer edge is driven into the spot sensor 24, precise OF alignment cannot be performed. Therefore, it is needless to say that it is necessary to finely move the X stage 10 or the Δθ stage 1 for precise OF alignment.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 12 is a cross-sectional view (a cross-sectional view taken along the line BB of FIG. 1) showing a schematic configuration of the positioning device according to the present embodiment. In the present embodiment, a positioning device having a peripheral exposure function will be described. In the present embodiment, in the apparatus of the first embodiment (FIG. 1), the peripheral edge exposing section 40 is arranged on the Y axis so as to face the spot sensors 27 and 28 with respect to the X axis. For this reason, here, the peripheral exposure unit 4
Only the configuration of 0 will be described. The members having the same functions and functions as those of the device of the first embodiment (FIG. 2) are denoted by the same reference numerals.

In FIG. 12, the light emitting section 42 disposed above the peripheral portion of the wafer is provided with a light source 41 for exposure. The light source 41 generates an exposure light beam (far-ultraviolet light) having a wavelength such that the resist layer is exposed to light. May be connected to the light emitting section 42. Further, between the light emitting unit 42 and the wafer W,
An aperture (for example, a rectangular aperture, an aperture, etc.) for defining the exposure light beam 45 emitted from the light emitting section 42 on the wafer W into a predetermined shape.
A light shielding plate 43 having a fan-shaped opening is provided. Further, the photoelectric detector 44 is provided with the light emitting section 4 with the peripheral portion of the wafer therebetween.
The exposure light beam 45 which is arranged to face the wafer 2 and is not blocked by the wafer W is received to detect the wafer edge.

Incidentally, in order to prevent the resist layer from being thinned,
It is desirable to insert a lens system inside the light emitting unit 42 or between the light emitting unit 42 and the wafer W to reduce the numerical aperture (NA) of the exposure light beam 45. Further, if an optical system for uniformizing the light intensity distribution of the exposure light beam 45 (such as a Koehler illumination system in which the exit end of the optical fiber is arranged on a pupil plane (a stop surface) of the optical system) is arranged inside the light emitting unit 42, Peripheral exposure can be performed under more appropriate conditions.

In performing the peripheral exposure, for example, data relating to the proper exposure amount of the used resist stored in the stepper body (or the memory 34) is input to the main control system 36, and the resist is exposed to the far ultraviolet light. Exposure conditions (exposure light intensity, etc.) to prevent foaming
And the rotation speed of the turntable 18 is determined. still,
If the exposure light intensity is weakened to suppress the bubbling of the resist, the rotation speed must be reduced in order to obtain an appropriate exposure amount, and the throughput of the exposure processing may be reduced. Therefore, in such a case, when exposing one wafer to the peripheral edge, the intensity of the exposure light in the first rotation may be suppressed to the foaming exposure amount or less, and the turntable 18 may be rotated twice or more. .

Further, the main control system 36 has a memory 34 in advance.
The exposure light beam 45 and the wafer W are relatively moved in the radial direction according to the data on the required exposure area (distance from the edge) input to (FIG. 3) and the wafer edge detection signal from the light receiving unit 44. . In particular, in this embodiment, the exposure light beam 45 is fixed, and a drive signal for finely moving the Y stage 15 is output to the stage controller 35. Next, when the turntable 18 is rotated at a predetermined speed and exposure is started, the above-described driving is performed so that the exposure light beam 45 emitted from the light emitting unit 42 always exposes a region from the wafer edge to a predetermined distance in the radial direction from the wafer edge. Y stage 1 by signal
The position of the exposure light beam 45 with respect to the wafer edge is servo-controlled by slightly moving 5.

Next, the operation of the apparatus according to this embodiment will be described with reference to FIG. FIG. 13 is a diagram showing a peripheral exposure sequence of an OF-equipped wafer. Since the positioning operation has been described in the first embodiment, the description is omitted here. Now, the wafer W is accurately positioned with respect to the orthogonal coordinate system XY (FIG. 13A), and the main control system 36 executes the peripheral edge exposure of the circumferential portion, so that the exposure light beam 45
The turntable 18 is rotated by a predetermined angle so that the laser beam irradiates the required exposure area near the boundary between the OF and the circumference (FIG. 13B). Thereafter, a shutter (not shown) disposed between the light source 41 and the light emitting unit 42 is opened to start irradiating the peripheral light with the exposure light flux 45, and further, the turntable 18 is rotated at a rotational speed corresponding to the appropriate exposure amount. Rotate with.
At this time, the main control system 36 determines, based on the data on the necessary exposure area and the wafer edge detection signal from the light receiving unit 44,
The Y stage 15 is servo-controlled so that the positional relationship (exposure width) between the exposure light beam 45 and the wafer edge is always constant. As a result, the peripheral portion of the circumferential portion is exposed with an appropriate exposure amount and with an accurate exposure width (FIG. 13C).

Next, the main control system 36 outputs a stop command of the θ motor 17 to the stage controller 35 when the OF is detected from the change of the wafer edge detection signal of the light receiving section 44. As a result, the rotation of the turntable 18 is stopped when the OF and the X direction substantially match (FIG. 13).
(D)). At this time, the θ motor may be stopped when the turntable 18 is rotated by a predetermined angle based on various data obtained by the positioning operation without using the wafer edge detection signal. Then, the X stage 10 is driven to linearly move the wafer W in the X direction, and the peripheral edge exposure of the OF is executed. As a result, the peripheral portion is always exposed with an accurate exposure width at the same accuracy as the circumferential portion even if the wafer has dimensional variations and OF is used (FIG. 13).
(E)).

Here, considering the stopping accuracy of the turntable 18 and the detection resolution of the encoder 26, FIG.
In (d), the turntable 18 can be stopped while the OF is inclined with respect to the X direction. For this reason, FIG.
It is desirable that the Y stage 15 is finely moved to perform the servo control of the exposure width also in the peripheral exposure of the OF shown in FIG. At this time, for example, two slit-shaped position sensors are formed on the light receiving unit 44 so as to be substantially parallel to each other, and a wafer edge detection signal output from each sensor is used. By finely moving the Y stage 15 so that the output (voltage) of the two sensors or the difference between the outputs is always constant, the exposure width can be controlled more accurately. Further FIG.
Even in the OF detection in 3 (d), it is possible to sufficiently follow the rotation of the turntable 18 and to perform the OF detection with high accuracy.

As described above, in this embodiment, after the wafer edge is positioned with respect to the exposure light beam 45 (FIG. 13).
(B)), the peripheral exposure was started, but FIG.
The peripheral edge exposure may be started immediately from the state of FIG. First, the turntable 18 is rotated once to expose the circumference at a predetermined width (FIG. 14A). At this time, the main control system 36 determines the presence or absence of the OF based on a change in the wafer edge detection signal, and stops the servo control when the OF is detected so that the exposure is not performed. Next, based on various data obtained in the previous positioning operation, for example, information on the wafer center position and the position and length of the OF, the exposure of the OF may be performed by linearly moving the X stage 10 (FIG. 14).
(B)).

In this method, a boundary portion between the circumferential portion and the OF portion (a double hatched portion in FIG. 14B) is double-exposed, but the resist coating device (spinner) applies the resist to the hatched portion. Is deposited, so that there is no problem even if the exposure amount is slightly increased as compared with other portions. Further, in the above embodiment, the wafer center Wc is shifted from the rotation center Tc of the turntable 18 within the range of the previously set initial wafer variation (± 5 mm). Therefore, when the turntable 18 rotates, the wafer W is eccentrically rotated,
The amount of movement of the Y stage under servo control increases. Here, when the rotation center Tc of the turntable 18 matches the origin O, that is, when the X and Y stages 10 and 15 are in the neutral position (FIG. 4A), the positioning in the X and Y directions is completed. If the coordinate values of the X and Y stages 10 and 15 when the wafer center Wc and the origin O match later (FIG. 4E) are read from the X and Y digital cameras 12 and 16, the turntable 18 The shift amount between the rotation center Tc and the wafer center Wc can be calculated.

Therefore, prior to the peripheral exposure, the wafer W is mounted on the fork 30 from the turntable 18 and the X and Y stages 10 and 15 are moved so that the above-mentioned amount of displacement becomes substantially zero. The wafer W is delivered. As a result, the rotation center Tc of the turntable 18 substantially coincides with the wafer center Wc (origin O), the eccentricity of the wafer W when the turntable 18 rotates is substantially zero, and the Y stage 15 is driven by servo control. The amount is small. This amount of eccentricity is determined only by the mechanical transfer accuracy between the fork 30 and the turntable 18, and
For example, it can be suppressed within 10 μm.

Further, if an accurate wafer diameter, that is, an actual wafer center is obtained by using the spot sensors 37 and 38 (FIG. 7) for diameter measurement described in the first embodiment, the rotation center Tc of the turntable 18 can be determined. Thus, the actual wafer center can be accurately matched. In addition, after the actual wafer center is accurately matched with the rotation center Tc of the turntable 18, the rotation of the turntable 18 is performed based on various data (such as the position and length of the OF) obtained by the positioning operation. (The output value of the encoder 31 is monitored) and the Y stage 15 (and further the X stage 10)
, The exposure width can be controlled with high accuracy even in open control.

It is to be noted that the wafer W is
It is needless to say that the peripheral exposure can be similarly performed by the open control based on the actual position of the wafer center and various data without changing the position. In addition, it is apparent that the edge exposure can be similarly performed by the open control even when the optical fiber of the light emitting unit is moved in the radial direction, which has been conventionally performed.

When the Δθ stage 1 is further rotated, Δ
X and Y stages 10 and 15 provided on θ stage 1
Does not move along the X and Y axes, and the moving coordinate system rotates with respect to the rectangular coordinate system XY. Therefore, when performing the peripheral exposure, it is desirable to sequentially correct the stage position in accordance with the rotation amount, or to correct the stage movement amount by software by holding the rotation amount in a memory.

After the peripheral exposure is completed, it is desirable to perform the positioning again, particularly the precise OF alignment, before carrying the wafer into the stepper. This is because the digitizers 12 and 16 have high resolution and high reproducibility, and the X and Y stages 10 and 15 are driven again to the coordinate values at the end of positioning, so that the wafer center Wc and the origin O can be matched with sufficient accuracy. In this embodiment, the encoder 31
And the θ motor 17 have a low accuracy and cannot obtain a sufficient positioning accuracy.

In this embodiment, the exposure operation of the wafer with the OF is described. However, in the case of the wafer with the notch, the entire peripheral portion is exposed by the same operation as the exposure operation of the circumferential portion described in the above embodiment. Good. Further, a sequence may be adopted in which after the pattern exposure by the stepper is completed, the wafer W is carried into the above-described apparatus again and the peripheral edge exposure is performed.

Further, for example, by using a dichroic mirror, the illumination light beam of the analog sensor 20 and the exposure light beam of the peripheral exposure unit 40 can be switched, and the optical system (2
(The two colors are achromatic) so that the analog sensor 20 and the peripheral exposure unit 40 can be integrated. Furthermore, the illumination light beam of the analog sensor 20 may be a light beam having an exposure wavelength, and the analog sensor 20 may have an edge detection function at the time of peripheral exposure.

As described above, in the first, second and third embodiments of the present invention, the spot sensors 24, 27, 28 and 37,
38, a minute spot light (parallel light beam) was applied. This is because, as shown in FIG. 15, when a minute parallel light beam is not used for the spot sensor, the edge position can be detected by being shifted by Δd depending on the presence or absence of chamfering at the wafer edge. In consideration of (unevenness) and the linearity of the photoelectric sensor, a parallel light beam having a small area is used.

[0068]

As described above, according to the apparatus for positioning a circular substrate according to the first to eighth aspects of the present invention, the second rotary stage disposed on the linear motion stage is applied only to the approximate notch. Therefore, there is no need to mount a high-resolution encoder and a stepping motor, and a lightweight and inexpensive configuration can be obtained. In addition, since the first rotary stage is disposed below the linear motion stage, the weight load on the linear motion stage can be reduced, and high-speed, high-precision positioning can be performed. Further, by reducing the weight of the portion above the linear motion stage, it is possible to reduce the vibration that can be caused by the high speed movement of the linear motion stage, and it is possible to eliminate the adverse effects during positioning and peripheral exposure.

In addition, since a minute spot light substantially parallel to the second detector is applied, highly accurate position detection can be performed. Further, if the lever 7 shown in FIG. 1 is elongated so as to increase the positioning accuracy of the first rotary stage, specifically, to increase the distance between the stage rotation center and the lever driving point, the rotation of the circular substrate is particularly enhanced. The positioning accuracy in the direction can also be improved.

Further, the first rotary stage is constituted so as to be rotatable about the coordinate origin of the rectangular coordinate system substantially, and after the above-mentioned origin and the center of the circular substrate are substantially coincident with each other, the first rotary stage is swung. Positioning of the circular substrate in the rotation direction is executed. Therefore, even when positioning in the rotation direction is performed, the center of the circular substrate does not deviate from the origin and the operation of aligning the center of the circular substrate again with the origin is not required, thereby preventing a decrease in throughput and positioning accuracy. it can.

In positioning the circular substrate in the X or Y direction and the rotation direction, the direct drive stage is servo-controlled based on the output from the second detector (spot sensor). For this reason, for example, when the first rotary stage is rocked to perform the positioning in the rotation direction, even if the rotation center (coordinate origin) of the first rotary stage is deviated from the actual center of the circular substrate, the X and Y directions are different. There is an advantage that the positioning accuracy is not reduced.

Further, in the present invention, only the sensor for peripheral edge exposure is incorporated in the positioning device, and the sensor and the circular substrate are relatively moved in the radial direction using the stage mechanism of the positioning device as it is. Therefore, it is not necessary to add a driving means, and the exposure width can be accurately controlled even in the case of a notch. In addition, based on various information obtained by the positioning operation of the circular substrate (the center position of the circular substrate, the length of the notch, and the like), even when performing the peripheral exposure while performing the open control of the linear motion stage, the same as the servo control is performed. There is an advantage that the exposure width of the circular substrate can be controlled with high accuracy and there is no need to provide a servo control mechanism. Since the positioning device according to the ninth to tenth aspects of the present invention uses a parallel light beam that becomes a minute spot light, it is possible to detect the peripheral edge with high accuracy, and to position the circular substrate with high accuracy. The positioning method according to claims 11 to 13 of the present invention,
Since a parallel light beam that becomes a minute spot light is used, the peripheral edge can be detected with high accuracy, and the circular substrate can be positioned with high accuracy.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of a circular substrate positioning device according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

FIG. 3 is a block diagram of a control system according to the first embodiment of the present invention.

FIG. 4 is a positioning sequence diagram of an OF-equipped wafer.

FIG. 5 is a diagram provided to explain an operation of a general OF adjustment.

FIG. 6 is a diagram illustrating a waveform of a photoelectric signal obtained from a spot sensor.

FIG. 7 is a diagram illustrating an arrangement of spot sensors for diameter measurement.

FIG. 8 is a plan view illustrating a schematic configuration of a circular substrate positioning device according to a second embodiment of the present invention.

FIG. 9 is a positioning sequence diagram of a notched wafer.

FIG. 10 is a diagram for explaining an operation of measuring a residual rotation error of a notched wafer;

FIG. 11 is a view for explaining an example of a modification of the operation of the second embodiment of the present invention.

FIG. 12 is a sectional view taken along the line BB of FIG. 1 showing a schematic configuration of a circular substrate positioning device according to a third embodiment of the present invention.

FIG. 13 is a peripheral exposure sequence diagram of an OF-equipped wafer.

FIG. 14 is a view for explaining an example of a modification of the operation of the third embodiment of the present invention.

FIG. 15 is a diagram illustrating a specific configuration of a spot sensor.

FIG. 16 is a schematic diagram showing a schematic configuration of a conventional positioning device.

FIG. 17 is a sectional view taken along the line CC of FIG. 16;

[Explanation of symbols]

 Reference Signs List 1 Δθ stage 10 X stage 15 Y stage 18 Turntable 20 Analog sensor 24, 27, 28, 37 to 39 Spot sensor 30 Transfer arm (fork) 36 Main control system 40 Peripheral exposure unit W Wafer

────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Naomasa Shiraishi 1-6-3 Nishioi, Shinagawa-ku, Tokyo Examiner, Nikon Oi Works Co., Ltd. Mikio Fukasawa (58) Field surveyed (Int.Cl. ⁷ , DB (Name) H01L 21/68

Claims (13)

(57) [Claims] 1. An apparatus for positioning a circular substrate having a notch of a predetermined shape with respect to a rectangular coordinate system, comprising: a first rotary stage capable of minute rotation about a coordinate origin of the rectangular coordinate system; A linear stage provided on the first rotary stage and movable two-dimensionally in the rectangular coordinate system; a second linear stage provided on the linear stage and capable of rotating at least one rotation while holding the circular substrate A rotation stage; a non-contact type first detector for detecting, in a non-contact manner, information representing a change in the amount of displacement of the peripheral portion of the circular substrate from the center of rotation during rotation of the second rotation stage; First positioning control means for controlling stop of rotation of the second rotary stage so as to set the notch of the circular substrate in a predetermined direction on the rectangular coordinate system based on the detected information; Periphery of the circular substrate A second non-contact type detector having detection points at at least three predetermined positions in the rectangular coordinate system so that at least three positions of the minute can be detected in a non-contact manner; After the notch is set in a predetermined direction by the positioning control means, the linear motion stage and the first rotary stage are controlled based on detection information at at least three detection points of the second detector. Second positioning control means, whereby the center of the circular substrate is always positioned in a substantially constant relationship with respect to the coordinate origin, and the residual rotation error of the circular substrate with respect to the rectangular coordinate system is reduced. An apparatus for positioning a circular substrate, which is substantially zero. 2. The apparatus according to claim 1, wherein when the translation stage is positioned at a predetermined neutral position, the rotation center of the second rotation stage substantially coincides with the coordinate origin. 2. A device for positioning a circular substrate according to claim 1. 3. The second positioning control means includes an arithmetic circuit for calculating the residual rotation error based on detection information from the second detector; and controlling the translation stage in accordance with the detection information. 2. The apparatus for positioning a circular substrate according to claim 1, further comprising a control circuit for controlling the first rotation stage in accordance with the residual rotation error calculated by the arithmetic circuit. 4. The control circuit finely moves the linear motion stage to make the center of the circular substrate substantially coincide with the coordinate origin, and then finely moves the first rotary stage to substantially reduce the rotation error. 4. The apparatus for positioning a circular substrate according to claim 3, wherein the position is set to zero. 5. The control circuit includes a servo circuit that servo-controls the translation stage based on detection information from the second detector, and the servo circuit servo-controls the translation stage. 5. The circular shape according to claim 4, wherein the linear motion stage or the first rotary stage is finely moved while making the center of the circular substrate substantially coincide with the coordinate origin, or the residual rotation error is made substantially zero. Substrate positioning device. 6. The control circuit calculates a diameter of the circular substrate together with the residual rotation error based on detection information from the second detector, and the control circuit calculates information on the calculated diameter. And finely moving the translation stage in accordance with the detection information so that the center of the circular substrate substantially coincides with the coordinate origin, and then finely moves the first rotary stage to reduce the residual rotation error to substantially zero. The positioning device for a circular substrate according to claim 4, wherein the positioning is performed. 7. The projector according to claim 1, wherein the second detector emits an illumination light beam in a wavelength range insensitive to a resist layer of the circular substrate; and substantially opposes the projector with a peripheral portion of the circular substrate interposed therebetween. 2. The circular substrate positioning apparatus according to claim 1, further comprising: a light receiver that is arranged in such a manner that the light projector emits a parallel light beam that forms a minute spot at a peripheral portion of the circular substrate. 8. A device for positioning a circular substrate, wherein the light emitting unit emits an exposure light beam having a characteristic of sensitizing a resist layer of the circular substrate, and substantially faces the light emitting unit with a peripheral portion of the circular substrate interposed therebetween. Exposure means having a light receiving portion arranged as described above; and at least one of an exposure condition by the exposure light beam and a rotation speed of the circular substrate by the second rotation stage based on information on an appropriate exposure amount of the resist layer. And the exposure control unit determines that the center of the circular substrate substantially coincides with the coordinate origin, and the rotation residual error becomes substantially zero, and then the exposure light beam is exposed to the peripheral portion. While controlling the linear motion stage to irradiate the resist layer within a predetermined range in the radial direction of the circular substrate, while selectively exposing the resist layer at the peripheral portion of the circular substrate. 2. The device for positioning a circular substrate according to claim 1, wherein the device emits light. 9. A positioning device for positioning a circular substrate provided with a notch of a predetermined shape with respect to a rectangular coordinate system, wherein substantially parallel light beams that become minute spots are emitted at at least three places on a peripheral portion of the circular substrate. A positioning device, comprising: an emitting device; and a detecting device that is disposed to substantially face the emitting device and detects the parallel light flux. 10. A stage that holds the circular substrate and moves in the rectangular coordinate system, and a control device that controls a position of the stage based on a detection result of the detection device. The positioning device according to claim 9, wherein 11. A positioning method for positioning a circular substrate provided with a notch of a predetermined shape with respect to a rectangular coordinate system, wherein substantially parallel light beams that become minute spots are emitted at at least three peripheral portions of the circular substrate. And a step of detecting the position of the circular substrate by detecting the parallel light beam. 12. The method according to claim 11, further comprising the step of adjusting the position of the circular substrate based on the position detection of the circular substrate. 13. A step of detecting the position of the circular substrate using a light beam different from the substantially parallel light beam which becomes the minute spot before emitting the almost parallel light beam which becomes the minute spot to the peripheral portion of the circular substrate. The positioning method according to claim 11, comprising: