JPH05160245A - Circular board positioning apparatus - Google Patents

Abstract

PURPOSE:To both accurately position a circular board at a high speed and to detect a defect of a peripheral edge of the board. CONSTITUTION:X-, Y-stages 10, 15 and a turntable 18 provided further thereon are provided on a DELTAtheta stage 1. Information representing a variation in a deviated amount from a rotating center of a peripheral edge of a wafer W during rotation of the turntable 18 is detected by an analog sensor 20. A defect discriminator detects the defect of the peripheral edge based on the detected information. A main control system so controls the rotation of the table 18 as to set a cutout in an X direction. After the cutout is set to the X direction, the control system controls the stages 10, 15 and the stage 1 based on the detected information at three positions of the peripheral edge of the wafer W by spot sensors 24, 27, 28. Thus, the positioning accuracy of the wafer W in an orthogonal coordinates system XY can be improved, and further the defect of the peripheral edge of the water can simultaneously be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning device for a circular substrate (semiconductor wafer) having notches (orientation flats, notches) suitable for a manufacturing device or an inspection device used in a semiconductor element manufacturing process, for example. In particular, the present invention relates to a positioning apparatus suitable for an exposure apparatus (stepper, aligner, etc.) that requires positioning accuracy.

[0002]

2. Description of the Related Art Conventionally, in an exposure apparatus and an inspection apparatus used in a semiconductor element manufacturing process, particularly a lithography process,
The wafer is positioned with respect to the apparatus by using an orientation flat (hereinafter referred to as OF) and a notch. Particularly in the exposure apparatus, the alignment accuracy must be increased in accordance with the higher integration and miniaturization of semiconductor elements, and accordingly, the demand for accurately positioning the wafer and mounting it on the apparatus is increasing. This type of positioning device is arranged in the wafer transfer path inside the exposure apparatus, and presses the wafer against a reference member that can abut the circumferential portion and the notch, for example.
Alternatively, a method of irradiating a light beam to the peripheral portion and optically detecting the notch is adopted. Here, in the former method, since the wafer is brought into direct contact with the reference member, chipping of the wafer, peeling of the resist, and the like are likely to occur, and moreover, they adhere to the surface of the wafer as foreign matter and reduce the yield. The method is the mainstream.

[0003]

However, in the prior art as described above, there is a defect in the peripheral portion of the wafer, for example, irregularities (chips or the like) are generated, or the resist layer partially protrudes from the wafer. If formed, there is a problem in that these irregularities may be erroneously detected and the positioning accuracy may be reduced. This can be a factor that lowers the alignment accuracy, that is, the yield and the like in the post-process, particularly the exposure process. Further, if a wafer in which the resist partially protrudes is carried into the exposure apparatus as it is, the resist adheres to the surface of the wafer as a foreign matter, and the yield may decrease.

The present invention has been made in consideration of the above points, and the circular substrate can be positioned with high accuracy and high speed, and the defect in the peripheral portion of the circular substrate can be detected to perform the post-process. It is an object of the present invention to obtain a positioning device capable of preventing a decrease in yield and the like due to unevenness of a circular substrate or peeling of a resist in (especially, exposure step).

[0005]

In order to solve such a problem, in the present invention, a circular substrate [wafer W] having notches [OF, notches] of a predetermined shape with respect to a predetermined rectangular coordinate system XY. A first rotary stage [Δθ stage 1] capable of minute rotation about a coordinate origin O of the Cartesian coordinate system XY; and a two-dimensional unit provided on the first rotary stage in the Cartesian coordinate system XY. Movable linear motion stage [X, Y stage 10, 15]; provided on the linear motion stage and holding at least one circular substrate.
A second rotary stage [turntable 18] which can rotate more than a rotation; non-contact detection of information indicating a change in displacement amount from the rotation center Tc of the peripheral portion of the circular substrate during rotation of the second rotary stage. A contact-type first detector [analog sensor 20]; based on the detected information, the notch of the circular substrate is cut in a predetermined direction on the orthogonal coordinate system XY [eg X
[Direction], the first positioning control means for controlling the stop of rotation of the second rotary stage [first signal processing system 32, stage controller 35, and main control system 36].
And a second non-contact type detector having detection points at at least three predetermined positions in the Cartesian coordinate system XY so that at least three positions on the peripheral portion of the circular substrate can be detected without contact. [Spot sensors 24, 27, 28] and; after the notch of the circular substrate is set in a predetermined direction by the first positioning control means, the detection information is obtained at at least three detection points of the second detector. Based on this, second positioning control means [second signal processing system 33, stage controller 35, and main control system 36] for controlling the linear movement stage and the first rotation stage is provided, and the center of the circular substrate is the origin of coordinates. The circular plate is always positioned in a substantially constant relationship with respect to O, the residual rotation error (Δα) of the circular substrate with respect to the Cartesian coordinate system XY is made substantially zero, and the circle is detected based on the information detected by the first detector. A detection means [defect determination section 37] for detecting a defect in the peripheral portion of the shaped substrate is provided.

[0006]

In the present invention, when the circular substrate is positioned, the non-contact information for detecting the change in the displacement amount from the rotation center of the peripheral portion of the circular substrate is detected during the rotation of the second rotary stage. By using the output information from the first detector of the mold, it is decided to detect a defect (a chip or the like) in the peripheral portion of the circular substrate. Therefore, for circular substrates that may cause a decrease in yield due to the above defects, for example, by notifying the operator by a buzzer or an error display, or by automating the apparatus (that is, for substrate processing Can be rejected as a defective product. Therefore, a defective circular substrate is not sent to a subsequent process, and it is possible to prevent a decrease in throughput, yield, etc. in the subsequent process, particularly in the exposure process.

[0007]

1 is a plan view showing the schematic construction of a positioning apparatus according to a first embodiment of the present invention, and FIG. 2 is a line A--A of FIG.
It is a cross-sectional view taken in the direction of the arrow, and in the present embodiment, a positioning device suitable for a wafer provided with OF (linear notch) will be described. The positioning device of this embodiment is incorporated in the stepper, particularly in the wafer transfer section.
Further, here, in order to simplify the description, a Cartesian coordinate system XY is defined in FIG. 1, and finally, the wafer center coincides with the origin O of the Cartesian coordinate system XY, and a rotation error of the wafer with respect to the Cartesian coordinate system XY is caused. It becomes zero, that is, the orientation of the OF (edge direction) is a predetermined OF matching direction (for example, the X direction).
The wafer is positioned so that it is parallel to.

In FIGS. 1 and 2, the Δθ stage 1 is supported on a base 2 via a base 3 and a guide bearing 4, and the center of rotation is the origin O of the orthogonal coordinate system XY.
It is installed so that it almost coincides with. Further, by driving the lever 7 fixed to the Δθ stage 1 by the Δθ motor 5 and the feed screw 6, the linear motion is converted into a rotational motion, and for example, it is possible to make a minute rotation about the origin O within a range of ± 2 °. Composed. The rotation amount of the Δθ stage 1 is fed with a resolution of about 0.5 μm, for example, by a digital micrometer 8 which is arranged so as to face the Δθ motor 5 and the feed screw 6 with the lever 7 in between and which is in contact with the side surface of the lever 7. It is detected by measuring the feed amount of the screw 6.

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

Although not shown, the θ motor 17 also includes means (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 these grooves 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.

Further, the transfer arm (fork) 30 sucks and holds the wafer W from the back surface by the vacuum suction surface 29 formed at the tip portion, and moves in the left-right direction (X direction) on the paper surface by a guide mechanism (not shown). It is configured to be possible. Therefore, the wafer W stored in the loader cassette (wafer carrier) is unloaded by the fork 30, placed on the fork 30 and moved above the turntable 18, and then the fork 30 and the turntable 18 are moved in the Z direction. The relative movement (the transfer arm 30 descends or the turntable 18 rises), and the wafer W is turned on the turntable 1.
It is delivered to 8 and adsorbed.

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.
It shall be held within and delivered to the turntable 18. Further, when the rotation center of the turntable 18 (Tc described later) is displaced from the rotation center of the Δθ stage 1 (origin O), the displacement amount may be larger than ± 5 mm. Positioning may be started in this state, but in order to do so, X, Y
The movement stroke of the stages 10 and 15 must be lengthened. Therefore, in this embodiment, the X, Y stage 10,
When 15 is at a predetermined neutral position, for example, the center of the moving stroke, the center of rotation of the Δθ stage 1 (origin O)
And the rotation center of the turntable 18 are substantially coincident with each other, and the wafer W is transferred at the neutral position.

Both the X and Y coordinate values of the X and Y stages 10 and 15 at the neutral position are set to zero, and the detection values of the digital micrometers 12 and 16 at this time are read and stored. The analog sensor 20 detects a change in position of the wafer edge from the rotation center Tc of the turntable 18 with the rotation of the wafer at a fixed point, and is used for a general OF alignment and a defect detection described later. In FIG. 1, the analog sensor 20 has a slit-shaped light receiving surface (not shown) arranged on the X axis toward the origin O (extending in the radial direction of the wafer), but the origin O (Δθ stage 1
It may be arranged anywhere on the circumference corresponding to the wafer size with the center of rotation as the center. As shown in FIG. 2, the analog sensor 20 includes a light source 21 that generates illumination light IL having a wavelength that does not expose the resist layer, a lens 22 that makes the illumination light IL a parallel light flux, and a light source 21 that sandwiches the wafer peripheral portion.
And a photoelectric detector 23 (position sensor, CCD linear sensor, etc.) which is arranged so as to face with.

As shown in FIG. 3, the analog sensor 20
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 the rotation angle information from the encoder 31 is also input, and the unit rotation angle of the turntable 18 is input. The position change of the wafer edge is detected every (for example, 0.5 °). Therefore, inside the first signal processing system 32, an A / D converter and a memory for digitally sampling the signal waveform from the analog sensor 20 in response to the up / down pulse from the encoder 31 are provided.

Further, the spot sensors 24, 27, 28 are for detecting the position of the wafer edge by moving the X, Y stages 10, 15, and detect a positioning error (ΔX, ΔY, Δα) described later. Used for. In FIG. 1, the spot sensor 24 is arranged on the X axis substantially symmetrically with respect to the origin O with respect to the analog sensor 20, and the spot sensors 27 and 28 are arranged substantially symmetrically with respect to each other with respect to the Y axis and arranged side by side in the X direction. Of course, these 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 forms a minute spot (for example, about 50 μm in diameter) on the wafer surface.
And a photoelectric detector 26 arranged so as to face the light projector 25 with the peripheral portion of the wafer interposed therebetween.

In FIG. 3, the second signal processing system 33 is 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 (digitizer) 12 are input to detect the position when the wafer edge crosses the minute spot light SP. 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, but since the beam diameter of the minute spot light cannot be ignored accurately, the X stage 10 After the photoelectric signal is sampled for each unit movement amount (for example, 0.5 μm) and converted into a digital value, the edge position is detected by a predetermined calculation process. Since the spot sensors 27 and 28 have exactly the same configuration and function, the description thereof will be omitted here.

Here, the spot sensor 24 may be arranged anywhere as long as it is a circumferential portion (excluding the intersection of the spot sensors 27 and 28 with the vertical bisector). On the other hand, the spot sensors 27 and 28 may be arranged along the OF matching direction so that the distance l between them is shorter than the OF length. Further, the spot sensors 27, 28 are movable with respect to the OF matching direction, for example, the movable range (rotation amount) of the Δθ stage 1.
It may be tilted by a minute angle according to. In this case, if the OF is driven into the spot sensors 27 and 28 and then the Δθ stage 1 is rotated by the tilt angle, the precise OF adjustment (described later in detail) can be similarly executed.

In FIG. 3, as will be described later in detail, the first signal processing system 32 obtains the characteristic on the waveform from the waveform data stored in the memory by a predetermined arithmetic processing,
This information is output to the main control system 36 and the defect determination section 37. The defect determination unit 37 receives the input data from the first signal processing system 32 and the information on the outer shape of the wafer to be detected as defects stored in advance in a memory (not shown) (for example, outer diameter, OF length, and these). (Permissible error amount, etc.) of the wafer) to detect defects (irregularities on the wafer, convex portions on the resist, etc.) in the peripheral portion of the wafer. In this embodiment, the defect determining section 37
Is configured to be displayed on a display device (a cathode ray tube or the like) 38. For example, the position and the size of the defect on the peripheral portion of the wafer on the screen are displayed. .. The size may be divided into several ranks and displayed.

In the memory of the defect determining section 37, the names of a plurality of types of wafers to be handled by the positioning device (ie, the exposure device) (for each wafer, or for each lot capable of storing a plurality of (about 25) wafers) are stored. ) And information regarding the outer shape corresponding to each name are registered in advance. Then, by reading the identification code (bar code or the like) formed on the wafer or the lot with a bar code reader or the like (not shown), the defect determining section 37 reads out the outer shape information corresponding to the name from the memory and detects the defect. Will be done. The outer shape information itself may be written in the identification code instead of the name. Further, the operator may directly input the outer shape information to the main control system 36, that is, the defect determination section 37 by using an input device (keyboard or the like).

The detection result of the defect determining section 37 is also output to the main control system 36, and the main control system 36 determines whether the wafer is good or bad and performs positioning, in other words, the wafer is transferred to the rear side. It is determined whether or not the process is to be sent to the process (exposure process), and if it is determined to be good, the general OF adjustment described later is immediately executed. On the other hand, if the main control system 36 determines that it is defective,
Alternatively, the operator is notified by displaying an error on the screen of the display device 38 to that effect. The quality of the wafer may be judged by the operator by looking at the defect detection result displayed on the screen of the display device 38. Further, a wafer determined to be defective will be removed from the apparatus (transfer line for wafer processing) by the operator, but the main control system 36 automates to automatically remove the wafer determined to be defective from the apparatus. It doesn't matter.

Further, the main control system 36 comprises the second signal processing system 3
Positioning error of the wafer W (Δ
X, ΔY, Δα), a predetermined control command is given to the stage controller 34, and the stage controller 3
4 drives the X, Y motors 11 and 14 and the Δθ motor 5 to perform 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 rough OF adjustment is output to the stage controller 35.

Next, the positioning operation of the apparatus having the above construction will be described with reference to FIG. FIG. 4 is a diagram showing a positioning sequence of the wafer with OF. First, the wafer W is Δθ
The amount of deviation of the wafer center Wc with respect to the rotation center (origin O) of the stage 1 is suppressed to within ± 5 mm and transferred to the turntable 18 (FIG. 4A). Then, the main control system 36 rotates the turntable 18, and the illumination light I not blocked by the wafer W in the analog sensor 20.
Photoelectrically detect L. At this time, in the present embodiment, since the defect detection is performed in the entire peripheral portion of the wafer as described later, it is necessary to rotate the turntable 18 at least once.

The first signal processing system 32 responds to the up / down pulse from the encoder 31 by the analog sensor 20.
The photoelectric signal from is sampled, each sampled value is converted into a digital value, and stored in a memory (not shown) in the order of addresses. As a result, signal waveform data corresponding to the wafer edge profile 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, the position change of the wafer edge from the rotation center Tc due to the rotation.

Further, the first signal processing system 32 uses software-based differential calculation processing (may be performed by hardware) to convert the waveform data of FIG. 5A into waveform data as shown in FIG. 5B. Convert to. In FIG. 5B, the zero cross point θ ₁ (differential value) is the rotation angle corresponding to the OF center. Therefore, 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.

By the way, the peripheral portion has an uneven portion (such as a chip).
For a defect-free wafer, only the OF portion is shown in FIG.
As shown in the figure, the maximum value, minimum value and zero
Loss point θ₁Will be obtained. However, the perimeter
In the case of a wafer in which a defect exists, the
In each defect, the maximum and minimum values are the same as in the OF part.
And zero crossing point θ₁Waveform data equivalent to
It is. Here, the waveform data of FIG.
Defects (chips) as defects along with the OF part on the peripheral edge of the
Also exists. The waveform data of FIG.
As is clear from the data,
Has a sharper signal change than the OF section.
Therefore, on the waveform data as shown in FIG.
The differential value (maximum value and minimum value) is the maximum value in the OF section.
And is larger than the minimum value. Incidentally, FIG. 5 (b)
Width of maximum value and minimum value on waveform data at
θ₁, Δθ₂Each of the
Angle α representing the size (width) of the pit ₁, Α₂Is equivalent to
It

From the above, by using the information on the outer shape of the wafer for which a defect is to be detected, the portion corresponding to the OF portion (maximum value, minimum value and zero crossing point θ on the differential waveform data of FIG. 5B). ₁ ) Identify. In other words, a value (here, Δθ ₁ ) that is closest to the width Δθ between the maximum value and the minimum value on the waveform data that is uniquely determined from the design angle α ₁ (FIG. 6) representing the OF portion is calculated from the waveform data. It suffices to select it and determine the portion where this value is obtained as the OF portion. As a result, a portion (width Δθ ₂ ) where the maximum value and the minimum value appear outside the specified OF portion is detected as a defect.
The position of the defect thus detected on the peripheral edge of the wafer is detected at the zero cross point (rotation angle value θ ₂ ) of the defect with reference to the OF portion (that is, rotation angle value θ ₁ ) specified previously. It is determined by Further, the degree (size) of the defect is the level (voltage value) of the photoelectric signal of the defect-corresponding portion in FIG. 5A or the maximum value and the minimum value of the defect-corresponding portion in FIG. 5B. Is obtained from the width (Δθ ₂ ) and so on. In the wafer W shown in FIG. 6, the former represents the length (depth) of the defect in the radial direction, and the latter represents the length of the defect in the circumferential direction.

Therefore, in this embodiment, the first signal processing system 32 is used.
After calculating the waveform data shown in FIG. 5B, the defect determining unit 37 determines that the waveform data (that is, the maximum value, the minimum value,
And the zero cross points θ ₁ and θ ₂ ) and the information on the outer shape of the wafer (OF length, etc.) are used to identify the OF portion on the waveform data, and the defect (the position, size, etc.) of the peripheral portion is also specified. ) Is detected. The detection result is displayed on the screen of the display device 38 and sent to the main control system 36. The main control system 36 determines the quality of the wafer based on this detection result. That is, whether or not the defect detected by the defect determination unit 37, in particular, its size (corresponding to the width Δθ ₂ here) exceeds a predetermined allowable value (or whether or not there is a defect regardless of its size). Is determined, and if it is determined to be good (or there is no defect), a rough OF adjustment described later is immediately executed. On the other hand, when the main control system 36 determines that there is a defect (or a defect), the main control system 36 informs the buzzer or that effect.
Notify the operator by displaying on the screen of FIG. As a result, with respect to a wafer determined to be defective, in other words, a wafer that is expected to reduce the yield and the like in a post-process (exposure process, etc.), an operator or an automatic positioning device (for wafer processing) (Transfer line)
Therefore, it is not carried into the exposure apparatus. Here, the description will be continued below assuming that the wafer on the apparatus is determined to be good. It should be noted that the quality of the wafer may be determined by considering not only the size of the defect (or the presence or absence thereof) but also the manufacturing error of the wafer. That is,
Wafer outer diameter and OF length are SEMI or JEID
It is also possible to determine whether or not it is within the allowable range set based on the standard such as A, and continue the positioning operation only for the wafers that satisfy both conditions.

Now, after the defect detection is completed, the main control system 3
6 monitors the output of the encoder 31 and rotates the turntable 18 counterclockwise in the plane of the drawing so as to obtain the rotation angle value θ ₁ , and the spot sensors 27, 28
To drive the OF. As a result, the spot sensor 2
The rotational deviation (tilt) of OF with respect to the line segment (X direction) connecting 7 and 28 is suppressed within a predetermined allowable range (for example, about ± 1 °), and the OF is aligned with the spot sensors 27 and 28 (generally OF). Matching) is completed (Fig. 4
(B)).

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

After the above-described general OF adjustment is completed, the main control system 36 finely moves the X stage 10, and the spot sensor 24 detects the position of the wafer edge in the X direction. When the X stage 10 is slightly moved here, the spot sensor 24 outputs a photoelectric signal as shown in FIG. FIG. 7A shows the relationship between the signal level (voltage) V and the scanning position in the X direction, and the second signal processing system 33 waveform-processes this photoelectric signal at a predetermined slice level SL ₁ to detect the wafer edge. The position (coordinate value X ₁ ) is calculated. Then, the main control system 36 sets the wafer W to the coordinate value X ₁ by using the X-digitizer 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 by using the spot sensors 27 and 28 in the same operation as the positioning in the X direction described above. Figure 7
(B) and (c) represent the photoelectric signals from the spot sensors 27 and 28, and the second signal processing system 33 performs waveform processing on these photoelectric signals with the slice levels SL ₂ and SL ₃ ,
The OF edge position (coordinate values Y ₁ , Y ₂ ) is detected. Then, the main control system 36 drives the OF into the spot sensors 27 and 28 by 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. 4 (d)). By the processing up to this point, the rotation center (origin O) of the Δθ stage 1 and the wafer center Wc substantially coincide with each other.

Next, the main control system 36 uses the coordinate values Y ₁ and Y ₂ to adjust the spot sensor 2 in order to perform precise OF adjustment.
Inclination of OF with respect to 7, 28, that is, Cartesian coordinate system XY
The residual rotation error Δα of the wafer W is calculated, and the Δθ stage 1 is swung while monitoring the measurement value of the digital camera 8 to correct the residual rotation error Δα to almost zero. Here, since the distance l between the spot sensors 27 and 28 is a known dimension (design value), the residual rotation error Δα is 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 are obtained.
And the residual rotation error Δα becomes almost zero, and the positioning of the wafer W is completed. When performing precise OF matching (that is, calculation of the residual rotation error Δα), the coordinate value Y
Instead of using ₁ and Y ₂ , the Y stage 15 may be slightly moved to detect the OF edge position again.

As described above, according to the present embodiment, the wafer can be positioned with high accuracy, and the rotation center of the Δθ stage 1 and the wafer center Wc are substantially aligned with each other prior to the precision OF alignment. The wafer W is not displaced in the X and Y directions due to the OF adjustment (rotation of the residual rotation error Δα). Further, since the peripheral edge of the wafer is detected for defects prior to the positioning operation, the wafer can be previously detected (from the positioning device or the transfer line) without performing the positioning operation for the wafer that may reduce the throughput or yield of the exposure apparatus. It can be removed. Also, positioning operation (general OF adjustment)
Since the defect detection is performed prior to the above, there is an advantage that the peripheral edge detection of the wafer by the analog sensor 20, which is necessary for both the rough OF alignment and the defect detection, can be performed only once.

By the way, in the present embodiment, the case where the peripheral portion has a concave portion (chipped) has been described, but naturally the convex portion can be detected in the same manner. Further, even if there is a defect in the OF portion in the above-mentioned embodiment, the position and size of the defect can be detected by optimizing the processing condition of the waveform data of FIG. Further, although the analog sensor 20 is used for roughly OF matching, even if a system using a CCD as the photoelectric detector 23 is adopted, defect detection can be performed in exactly the same manner as in the above embodiment.

In the above embodiment, the defect detection is performed prior to the positioning operation (general OF adjustment), but the defect detection may be performed at any timing. For example, after the positioning operation is completed, the turntable 18 is rotated once. As described above, the peripheral portion of the wafer may be detected by the analog sensor 20. Further, the main control system 36 determines the quality of the wafer based on the detection result of the defect determining section 37. However, for example, in the positioning apparatus, the defect determining section 37 may perform only defect detection. Is sent to the main body of the exposure apparatus or to the main control system on the side of the transfer apparatus (wafer loader), the quality of the wafer is judged here, and the wafer is sent to the exposure apparatus as it is, or the wafer is transferred to the cassette (lot). It is desirable to decide whether to return.

Further, in the above-mentioned embodiment, the positioning device suitable for the wafer having the OF has been described as an example.
The same effect can be obtained by applying the present invention to a positioning device suitable for a wafer having a notch 50 as shown in FIG. In FIG. 8, members having the same functions and functions as those of the apparatus shown in FIG. 1 are designated by the same reference numerals. As is apparent from FIG. 8, the difference from FIG. 1 is that the spot sensors 24, 27,
Since only the arrangement of 28 is described, the description of the configuration is omitted here, but the spot sensor 24 is arranged on the Y axis, the spot sensors 27 and 28 are substantially symmetrical with respect to the Y axis, and a predetermined angle from the Y axis (45 in the figure). It is only tilted. In the above embodiment, the positioning device is provided with the defect detection function, but it may be separated from the positioning device and used as a single defect inspection device.

In addition, the peripheral portion of the wafer has a predetermined width (1 to 7).
An apparatus that exposes only about (mm), that is, a so-called edge exposure apparatus can be provided with the defect detection function as in the above embodiment. In this type of device, in order to accurately control the exposure width, the exposure light flux and the wafer are separated according to the light intensity of the light flux that reaches the photoelectric detector without being shielded by the peripheral portion of the exposure light flux that exposes the resist layer. The entire area of the peripheral edge is exposed while relatively moving in the radial direction. Therefore, by using the photoelectric signal (corresponding to the waveform data of FIG. 5A) from the previous photoelectric detector, it becomes possible to detect the defect simultaneously with the edge exposure. At this time, in the above-mentioned apparatus, since the defect detection is performed at the same time as the edge exposure, the edge exposure is also performed on the wafer that can be determined to be defective from the detection result. Therefore, while rotating the wafer at least once, the peripheral portion of the wafer is irradiated with an illumination luminous flux having a wavelength range (non-exposure wavelength) different from that of the exposure luminous flux, and the light intensity of the luminous flux reaching the photoelectric detector without being shielded at the peripheral portion. A change (that is, corresponding to the waveform data of FIG. 5A representing the outer diameter information of the wafer) is detected. At this time, the wafer may be rotated while the illumination light flux and the wafer are relatively moved in the radial direction based on the detection signal from the photoelectric detector. After that, the previous detection result (wafer outer diameter information,
Alternatively, by using the relative position relationship between the illumination light flux and the wafer in the radial direction for each unit angle), the exposure light flux and the wafer are relatively moved in the radial direction to expose the entire peripheral edge portion. Of course, the exposure light flux and the illumination light flux are fixed in a predetermined positional relationship. As described above, in an apparatus in which an edge of a wafer is detected using an illumination light flux of a non-exposure wavelength prior to the edge exposure operation, it is possible to detect a defect in the edge of the wafer from the detection result as in the above embodiment. It will be possible. Therefore, it is not necessary to perform the edge exposure on the wafer determined to be defective from the defect detection result, and the throughput of the apparatus can be improved. Further, the edge exposure mechanism as described above (only the irradiation part of the exposure light flux and its light receiving part (photoelectric detector) may be incorporated) into the positioning device shown in FIG. 1, and in this case, the analog sensor 20 is used. It can be used as a system for detecting the edge of a wafer by using an illumination light flux having a non-exposure wavelength prior to the edge exposure operation.

[0038]

As described above, according to the present invention, the circular substrate positioning device is provided with the defect detecting function of the peripheral portion of the substrate, so that the yield of the circular substrate can be lowered in the subsequent steps (exposure step, etc.). There is an advantage that the positioning operation need not be performed. This makes it possible to improve throughput, yield, etc. in the entire semiconductor manufacturing line.

[Brief description of drawings]

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

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

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

FIG. 4 is a positioning sequence diagram of a wafer with OF.

FIG. 5 is a diagram for explaining the operation of the schematic OF adjustment.

FIG. 6 is a diagram for explaining a defect detection operation in one embodiment of the present invention.

FIG. 7 is a diagram showing a waveform of a photoelectric signal obtained from a spot sensor.

FIG. 8 is a plan view showing a schematic configuration of a wafer positioning device having a notch.

[Explanation of symbols]

 1 Δθ stage 10 X stage 15 Y stage 18 turntable 20 analog sensor 24, 27, 28 spot sensor 30 transfer arm (fork) 32 first signal processing system 33 second signal processing system 34 memory 36 main control system 37 defect determination unit 38 Display Device W Wafer

Claims (1)

[Claims] 1. An apparatus for positioning a circular substrate having a notch of a predetermined shape with respect to a predetermined rectangular coordinate system, comprising: a first rotary stage capable of minute rotation about a coordinate origin of the rectangular coordinate system. A linear motion stage provided on the first rotary stage and capable of two-dimensional movement within the orthogonal coordinate system; and a linear motion stage provided on the linear motion stage and capable of holding at least one rotation while holding the circular substrate. A second rotary stage; and a non-contact type first detector that non-contactly detects information indicating a change in displacement amount from a rotation center of a peripheral portion of the circular substrate during rotation of the second rotary stage. First positioning control means for controlling stop of rotation of the second rotary stage so as to set a notch of the circular substrate in a predetermined direction on the orthogonal coordinate system based on the detected information And the circular substrate A non-contact type second detector having detection points at at least three predetermined positions in the Cartesian coordinate system so that at least three positions of the peripheral portion can be detected without contact; 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 the detection information at at least three detection points of the second detector. Second positioning control means for positioning the center of the circular substrate in a substantially constant relationship with respect to the coordinate origin, and making the residual rotation error of the circular substrate relative to the Cartesian coordinate system substantially zero. And based on the information detected by the first detector,
A circular substrate positioning device comprising a detection means for detecting a defect in a peripheral portion of the circular substrate.