JPH11219999A - Delivery method for substrate and aligner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of the wafer stage of an exposure device and to improve precision when positioning a wafer on the stage. SOLUTION: A lighting system support part 45 is inserted into the bottom surface of a wafer W which is to be exposed while it is so held from above by a wafer load arm 28, the position of outer periphery of the wafer W is sequentially detected by imaging devices 26L-26U, and the detection result is processed to obtain a deviation amount of a center of the wafer W and rotational error. After rotation error are corrected through a rotation upper/lower part 25, a wafer stage 22 is so moved that the center of the rotation upper/lower part 25 (loading position) matches the center of a wafer holder 21, and the wafer load arm 28 is lowered to place the wafer W on the wafer holder 21. Then, the wafer load arm 28 is drawn out from the wafer W by moving the wafer stage 22 in the direction of its original position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, an image pickup device (CCD, etc.), a liquid crystal display device, a thin film magnetic head, etc., in a lithography process. The present invention relates to a method of transferring a substrate to or from a substrate stage of an exposure apparatus used for transferring a mask pattern or drawing a mask pattern on the substrate. Further, the present invention relates to an exposure apparatus using such a method for transferring a substrate.

[0002]

2. Description of the Related Art When manufacturing a semiconductor device or the like, an exposure apparatus for transferring a pattern of a reticle as a mask to each shot area of a wafer (or a glass plate or the like) coated with a photoresist is conventionally a stepper. A projection exposure apparatus of an and repeat type (batch exposure type or stepper type) has been frequently used. On the other hand, recently, in order to respond to the demand for transferring a large-area circuit pattern with high accuracy without excessively increasing the burden on the projection optical system, a step movement is performed between shots to expose each shot area. When performing, the reticle and the wafer are synchronously moved with respect to the projection optical system, which is a so-called step
Attention has also been paid to a scanning exposure type projection exposure apparatus such as an AND scan method.

In these projection exposure apparatuses, in order to increase the throughput, an exposed wafer on a wafer stage for positioning and moving the wafer is unloaded, and an unexposed wafer is unloaded. It is necessary to perform a wafer loading operation of loading (loading) the wafer on the wafer stage at a high speed. A conventional wafer loader system includes a wafer upper and lower pin provided to be able to protrude and retract into a wafer holder of a wafer stage, a wafer carrying arm for placing a wafer on the wafer upper and lower pins, and a wafer carrying arm for removing a wafer from the wafer upper and lower pins. , Was equipped. When a wafer is placed on a wafer stage, for example, as disclosed in Japanese Patent Application Laid-Open No. 9-36202, the wafer is transferred from a wafer transfer line to a wafer loading arm in advance. Rough positioning (pre-alignment) was performed based on the outer shape.

Then, in order to exchange the wafer, the wafer stage is moved to a loading position, the suction of the wafer holder on the exposed wafer is turned off, and the wafer is raised together with the upper and lower pins of the wafer. The wafer unloading arm is inserted between the wafer and the wafer holder, and the wafer upper and lower pins are lowered to transfer the wafer to the wafer unloading arm.

Thereafter, the wafer unloading arm is unloaded from the loading position to the wafer transfer line side, and at the same time, the wafer loading arm holding the unexposed wafer is inserted into the loading position, and the upper and lower pins of the wafer are lifted to the upper and lower pins. The wafer had been delivered. Then, after the wafer loading arm is pulled out, the wafer upper and lower pins are lowered to place the wafer on the wafer holder, and then the suction by the wafer holder is turned on. Thereafter, the wafer stage is sequentially moved to a position where the search alignment mark on the wafer falls within the detection area of the alignment sensor, and the search alignment is performed.

In search alignment, for example, by detecting the positions of three one-dimensional search alignment marks on a wafer, the amount of displacement of the origin of the shot arrangement on the wafer and the amount of displacement of the rotation angle are detected. The actual rough arrangement coordinates of each shot area on the wafer have been obtained based on the detection result. Thereafter, the position of the fine alignment mark (wafer mark) attached to a predetermined number of shot areas (sample shots) on the wafer based on the rough arrangement coordinates is detected by an alignment sensor. For example, a final alignment (fine alignment) is performed by, for example, an EGA (Enhanced Global Alignment) method. Then, based on the result, the pattern image of the reticle is superimposed on each shot area on the wafer with high accuracy and exposed, and then the above-described wafer exchange is performed again.

[0007]

As described above, in the prior art, a wafer upper and lower pin is mounted in a wafer holder on a wafer stage so as to be able to protrude and retract, and the wafer upper and lower pins are moved up and down to make the wafer holder and Transfer of wafers has been performed between a wafer carrying arm and a wafer carrying arm.

However, such a configuration in which the wafer upper and lower pins are provided in the wafer holder has a disadvantage that the mechanism of the wafer stage for supporting the wafer holder is complicated and large. In particular, in order to increase the throughput, it is necessary to increase the step moving speed in the case of the batch exposure type and the step moving speed and the scanning speed in the case of the scanning exposure type. Might be. Therefore, in a state where the size of the wafer stage cannot be reduced, it is difficult to suppress the amount of heat generation and the like and increase the moving speed.

The conventional processing time for one wafer is a sum of a wafer exchange time, a search alignment time, a fine alignment time, and a time for actually transferring a reticle pattern image to each shot area (narrowly defined exposure time). Therefore, even if the wafer exchange time or the wafer alignment time is shortened, the throughput of the exposure process can be increased. Therefore, it is desired to shorten the wafer exchange time or the wafer alignment time as much as possible.

Further, conventionally, since the wafer is pre-aligned at a position distant from the projection exposure apparatus, the wafer is transferred onto the wafer stage by the wafer transfer arm. There was a risk that the accuracy would decrease. Therefore, conventionally, it is necessary to perform search alignment for roughly measuring the shot arrangement on the wafer before performing fine alignment after suction-holding the wafer on the wafer holder, and the time required for alignment is long. Had become. In order to eliminate such search alignment, it is necessary to improve the positioning accuracy of the wafer when the wafer is placed on the wafer holder.

For example, in the case where the position of the outer shape of the wafer is detected before the wafer is mounted on the wafer holder, when the reflected light from the wafer is received by the epi-illumination method, the material of the thin film on the surface of the wafer or the like is detected. Slope of the surface (step)
However, the state of the reflected light changes relatively largely depending on the state, etc., and the position detection accuracy may be reduced. In view of the above, the present invention provides a method of transferring a substrate, which can reduce the size of a stage for a substrate such as a wafer of an exposure apparatus and improve the positioning accuracy when placing the substrate on the stage. This is the first purpose.

Further, the present invention provides a method of transferring a substrate, which can shorten the time required for exchanging a substrate with a stage for a substrate of an exposure apparatus and can improve the positioning accuracy when placing the substrate on the stage. The second purpose is to provide. Another object of the present invention is to provide an exposure apparatus that can use such a method for transferring a substrate.

[0013]

According to a first method of transferring a substrate according to the present invention, an exposure apparatus for transferring a pattern of a mask (R1) onto a substrate (W) positioned or moved by a substrate stage (22). Of the substrate stage (2
In the method of transferring a substrate for transferring the substrate to and from 2), a loading arm (25, 28) for holding the substrate (W) and moving the substrate up and down is provided, and the loading arm is provided on the loading arm. While holding the substrate, the position of the substrate is detected on the basis of the outer shape or a predetermined alignment mark as a reference, and based on the detection result, the substrate stage is moved to a position for receiving the substrate, and After the loading arm is lowered to place the substrate on the substrate stage, the loading arm is removed from the substrate.

According to the present invention, when the substrate stage moves to the loading position of the substrate, that is, below the carrying arm, the carrying arm is lowered, so that the substrate is moved from the carrying arm to the substrate arm. The substrate is passed to the stage. Thereafter, the carrying arm can be pulled out, for example, by moving the substrate stage in the direction of the original position. Thus, there is no need to provide a member for raising and lowering the substrate on the substrate stage side, and the configuration of the substrate stage is simplified and downsized.

In a state where the substrate is held by the carrying arm, the position of the substrate (for example, the amount of displacement from a predetermined reference position, the rotation error with respect to the reference direction, and the like) is measured. Since the position of the substrate hardly changes when the arm for use is lowered onto the substrate stage, the positioning accuracy when placing the substrate on the substrate stage is improved. Therefore, search alignment can be almost omitted. Further, the position measurement (pre-alignment) of the substrate held by the carrying arm is performed in parallel with the final alignment (fine alignment) of another substrate and the exposure performed on the substrate stage. , The overall processing time is further reduced and the throughput is improved.

In this case, the loading arm (25, 2)
When detecting the position of the substrate (W) held in 8), the notch (N1,
N2), at least three positions are detected, the rotation angle of the substrate is calculated based on the detected positions, and the loading arm is rotated based on the calculation result to determine the rotation angle of the substrate. It is desirable to correct. Accordingly, when the substrate is placed on the substrate stage, the rotation error is corrected, so that the operation of correcting the rotation error on the substrate stage side can be omitted, and the processing time is further reduced.

Further, when the amount of displacement (.DELTA.WX, .DELTA.WY) of the center of the substrate from a predetermined detection center is obtained, the amount of displacement (.DELTA.WX, .DELTA.WY) is used, for example, when final alignment of the substrate is performed. Can be used as an offset. In addition, the amount of the displacement (ΔWX,
(WY), the loading position of the substrate stage may be corrected.

Next, a second method for transferring a substrate according to the present invention is a method for transferring a pattern of a mask (R1) onto a substrate (W) positioned or moved by a substrate stage (22). In a method of transferring a substrate for transferring the substrate to and from a stage (22), a loading arm (25, 28) for holding the substrate and lowering the substrate; A first arm (103, 10) for detecting the position of the substrate while holding the substrate on the carrying arm (25, 28).
4), and the substrate stage (2
2) to a position for receiving the substrate, lowering the loading arm to place the substrate on the substrate stage, and then removing the loading arm from the substrate (111, 113) To 116) and the positions of predetermined alignment marks (WM1 to WM3) on the substrate, and based on the detection result, the positional relationship between a plurality of exposure regions on the substrate and the pattern of the mask. (117, FIG. 12) and a fourth step (117) of sequentially transferring the pattern of the mask to a plurality of exposure regions on the substrate while performing alignment based on the obtained positional relationship. And FIG. 14), a fifth step (11) of moving the substrate stage to a position where the substrate is carried out, lifting the substrate with the carrying arm, and carrying the substrate out of the exposure apparatus. Those with a 112), the.

According to the present invention, the substrate is loaded by a combination of the operation of moving the substrate stage to the position where the substrate is loaded and the operation of lowering the loading arms (25, 28). The operation of moving the substrate stage to a position where the substrate is unloaded (preferably the same as the position where the substrate is loaded) and the operation of raising the unloading arm (38) are combined with the operation of the substrate. Is carried out, so that the substrate can be exchanged at a high speed. Further, since the position of the substrate held by the loading arm is detected in the first step,
The positioning accuracy of the substrate with respect to the substrate stage is improved. Further, since the positioning accuracy with respect to the substrate stage is improved, fine alignment can be performed substantially directly instead of search alignment in the third step, and the throughput is improved.

Next, a first exposure apparatus according to the present invention comprises a substrate stage (22) for positioning or moving a substrate (W1) and a pattern of a mask (R1) on the substrate on the substrate stage. (10, 1)
(3, 17), the loading arm (25, 2) for holding the substrate and moving the substrate up and down.
8), an image processing system (26, 45) for detecting the position of the substrate held by the loading arm, and the substrate stage and the loading arm based on the detection result of the image processing system. Control system for controlling operation (15, 5)
The control system moves the substrate stage to a position for receiving the substrate based on the position of the substrate detected by the image processing system, lowers the loading arm, and Is mounted on the substrate stage. According to the present invention, the first substrate transfer method of the present invention can be used.

In this case, the image processing system includes a movable illuminator (45) that can be freely inserted into and removed from the bottom of the loading arm (25, 28) and illuminates the substrate from the bottom, and an illumination by the movable illuminator. And an imaging device (26) for capturing an image of the outer shape of the substrate. By imaging the image of the substrate by the transmission illumination in this manner, the position of the substrate can be measured with high accuracy without being affected by unevenness in the reflectance of the surface of the edge portion of the substrate. Also,
When the carrying arm is lowered onto the substrate stage, the movable lighting device (45) is retracted so that the movable lighting device (45) does not become an obstacle.

When the substrate is large (for example, a wafer having a diameter of 12 inches (approximately 300 mm)), the movable lighting device (45) detects the position (26L) on the substrate when detecting the position of the substrate. , 26N1, 26R and 26
U, 26N2, 26R). As a result, the movable lighting device can be reduced in size, so that the evacuation becomes easy. Further, for example, a notch of 0 ° and a notch of 90 ° of a wafer having a diameter of 12 inches can be sequentially detected by rotating the same movable illumination device. Further, the movable illumination device includes, for example, a surface light source (fluorescent lamp, fluorescent plate, or the like) having a wide illumination field that can support both notch detection of a wafer and detection of an orientation flat portion of another wafer. You may.

The carrying arm (25, 28)
Are holding members (2) for holding the substrate from above.
8), and the tip (50) of the holding member (28) is placed on the mounting surface (21) of the substrate of the substrate stage (22).
A, 50B) are desirably formed with grooves (37A, 37B). By this, when the loading arm is lowered onto the substrate stage, the tips (50A, 50B) of the holding member fit into the grooves (37A, 37B) on the substrate stage, so that the substrate is easily mounted. Can be passed to the substrate stage. After this,
By moving the substrate stage in a direction parallel to the grooves (37A, 37B), the loading arm can be pulled out of the substrate stage.

However, the width of the grooves (37A, 37B) is widened, and after the substrate is placed on the substrate stage, the carry-in arm is extended and raised to pull out from the substrate stage. You may do so. Further, the apparatus further includes a vertically movable carrying-out arm for carrying out the substrate on the substrate stage (22), and the carrying-out arm also includes a holding member (38) for holding the substrate by holding it from above. The tip of this holding member (49A, 49A)
B) is also desirably housed in the grooves (37A, 37B) on the substrate stage. In this case, when unloading the substrate, the substrate stage is moved so that the tip of the unloading arm fits in the groove, and then the unloading arm is lifted to easily remove the substrate. Can be carried out.

Further, the loading arms (25, 28) are provided with a function of rotating and raising and lowering the substrate, and the loading arms (25, 2) are moved from the substrate transfer line.
8) It is desirable to separately provide a transfer arm (43) for transferring the substrate to be exposed. In this case, the unloading arm (38) has a function of receiving the substrate and moving to the transfer line of the substrate, and the transfer arm (43) and the unloading arm (3) are provided.
It is desirable that the base member (42) for supporting the image processing system (26) and the base member (48) for supporting the image processing system (26, 45) are independent of each other. When the projection optical system (17) is provided, it is desirable that the projection optical system (17) is also fixed to the latter base member (48). In this case, the influence of vibration when the substrate is transferred between the transfer line and the substrate stage is affected when the position of the substrate is detected on the loading arm and when the substrate is placed on the substrate stage. Since it does not reach the time of transfer, the positioning accuracy of the substrate with respect to the substrate stage is improved.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, the present invention is applied to a wafer loader system of a step-and-scan type projection exposure apparatus. FIG. 1 is a schematic configuration diagram showing a projection exposure apparatus of the present embodiment. In FIG. 1, at the time of exposure, an exposure light source such as a mercury lamp or an excimer laser light source, and the amount of exposure light from this exposure light source are controlled. ND
A dimmer such as a variable filter, an optical integrator (such as a fly-eye lens or a rod lens) for equalizing the illuminance distribution of the exposure light, a field stop that defines an illumination area, and illumination including a condenser lens system. The exposure light IL is emitted from the optical system 3 to a rectangular illumination area on the reticle R1. As the exposure light IL, i-line (wavelength 365 nm) of a mercury lamp, KrF (wavelength 248 n)
m), ArF (wavelength 193 nm), or F ₂ (wavelength 1
Excimer laser light such as 57 nm) or soft X-rays can be used.

Then, under the exposure light IL, the reticle R
An image of the pattern formed on the wafer W1 is projected through the projection optical system 17 at a projection magnification β (β is 1/5, 1/4, etc.) at a rectangular exposure area on a shot area to be exposed on the wafer W1. 3
0 (see FIG. 2). The surface of the wafer W1 is coated with a resist, and the illumination optical system 3 is provided with a measurement system for indirectly monitoring the amount of exposure to the resist. The illumination control system 4 controls the output of the exposure light source or the dimming rate of the dimmer based on the measurement result of this measurement system and the control information of the main control system 5 composed of a computer for controlling the operation of the entire apparatus. Then, the illuminance of the exposure light IL and the amount of exposure to the resist are optimized. The exposure amount also depends on the scanning speed of the wafer W1 and the width of the exposure area 30 in the scanning direction.

Hereinafter, the Z axis is taken parallel to the optical axis AX of the projection optical system 17, and the X axis is taken perpendicularly to the plane of FIG. 1 (non-scanning direction) in a plane perpendicular to the Z axis. The description will be made by taking the Y axis in parallel (scanning direction). At this time, reticle R
Numeral 1 is held on a reticle stage 10 by vacuum suction. The reticle stage 10 is supported on a reticle base 13 so as to float via an air bearing, and continuously moves in the Y direction by a driving mechanism such as a linear motor. At the same time, it slightly moves in the X, Y, and rotation directions. The side surfaces in the X and Y directions of the reticle stage 10 are each processed into a mirror surface as a movable mirror, and these mirror surfaces are irradiated with, for example, a three-axis laser beam from a reticle laser interferometer 12. Stage 1
The X coordinate, the Y coordinate, and the rotation angle of 0 are measured, and the measured values are supplied to the stage control system 16 and the main control system 5. The stage control system 16 controls the scanning operation and the positioning operation of the reticle stage 10 based on the measured values and the control information from the main control system 5.

On the other hand, the wafer W1 being exposed is held on a disk-shaped wafer holder 21 having a predetermined thickness by vacuum suction.
The wafer stage 22 is fixed above and supported by a wafer base 23 formed of a surface plate via an air bearing. As shown by the dotted line in FIG. 2, a light transmitting system 32E and a light receiving system 32
R, a plurality of measurement points in the exposure area 30 on the wafer W1 and the pre-read area on the near side in the scanning direction are irradiated with detection light, and the optical axis of the projection optical system 17 is measured at each measurement point. A multipoint oblique incidence type autofocus sensor (AF sensor) for detecting a position in the direction (focus position) is arranged, and the detection result of the AF sensor is continuously supplied to the stage control system 16. Stage control system 16
Is the exposure area 3 based on the detection result of the AF sensor.
The three Z driving units (not shown) in the wafer stage 22 by the auto focus method and the auto leveling method so that the focus position and the tilt angle of the surface of the wafer W1 coincide with the image plane of the projection optical system 17 within 0. ) Control the operation.

In FIG. 1, the wafer stage 22
The side surfaces in the X and Y directions are also machined into mirror surfaces as movable mirrors, and these mirror surfaces are attached to the laser interferometer 1 on the wafer side.
8, laser beams with a plurality of axes are emitted. The laser interferometer 18 measures an X coordinate, a Y coordinate, a rotation angle, and the like of the wafer stage 22 and transmits the measured values to the stage control system 1.
6 and the main control system 5. Coordinate system (X, Y) composed of X coordinate and Y coordinate of wafer stage 22 (wafer W) measured by laser interferometer 18 on the wafer side
Is called a coordinate system of the wafer stage or a stationary coordinate system.
The stage control system 16 determines the X direction of the wafer stage 22 based on the measured value and the control information from the main control system 5.
The operation in the Y direction is controlled. The wafer stage 22 moves stepwise and continuously in the X and Y directions on the reticle base 23 by, for example, a linear motor system.

When exposing the wafer W1,
After the exposure of one shot area on the wafer W1 is completed, the next shot area on the wafer W1 is moved to the projection optical system 1 by moving the wafer stage 22 stepwise.
7 is moved before the exposure area 30. Thereafter, the reticle stage 10 and the wafer stage 22 are driven, and the reticle R1 and the wafer W1 are synchronously scanned with respect to the projection optical system 17 using the projection magnification β as a speed ratio to expose the exposure light I
The operation of irradiating L is repeated by a step-and-scan method, and scanning exposure is performed on each shot area on the wafer W1.

When such exposure is superposition exposure, it is necessary to previously align each shot area on the wafer W1 with the pattern image of the reticle R1 with high accuracy. Further, it is necessary to measure the imaging characteristics and the like of the projection optical system 17 with high accuracy and correct them if possible. In order to perform the alignment, a reticle alignment microscope (not shown) is disposed above the reticle R1, and an off-axis type image processing type alignment sensor 19 is provided on a side surface of the projection optical system 17 in the −Y direction. is set up. The alignment sensor 19 detects the wafer W1
An illumination system for illuminating the upper test mark, an enlarged imaging system for forming an image of the test mark, and a two-dimensional image sensor such as a CCD type for imaging the image are provided. An image signal from the image pickup device is supplied to an alignment signal processing system 20. During alignment of the wafer, the alignment signal processing system 20 processes the image signal and moves the mark in the X direction and Y direction with respect to a predetermined detection center. The amount of displacement in the direction is obtained, and the amount of displacement is supplied to the main control system 5. The main control system 5 is also supplied with the coordinates of the wafer stage 22 measured by the laser interferometer 18 on the wafer side.
By adding the positional deviation amount of the test mark to the coordinates, the coordinates of the test mark on the coordinate system (X, Y) of the wafer stage are calculated.

FIG. 5A shows the projection optical system 1 shown in FIG.
In FIG. 5A, the projection optical system 17 is supported by a support member 48 made of a material having an extremely low expansion coefficient (such as Invar). That is, the distal end portion 17 a of the projection optical system 17 that holds the lens element closest to the wafer is housed in the cylindrical holding portion 48 a of the support member 48. Then, the distal end portion 17a of the projection optical system 17 and the holding portion 48a of the support member 48
Are indicated by dotted lines in FIG.

FIG. 2 shows the arrangement of the laser beam of the laser interferometer 18 for measuring the coordinates of the wafer stage 22. In FIG. 2, the center of the rectangular exposure area 30 is the optical axis AX of the projection optical system 17. It has become. The center of the circular detection field 19b of the alignment sensor 19 is the detection center 19a. The detection center 19a is, for example, a position where the center of an index mark in the alignment sensor 19 is projected on an image sensor for alignment. Are located in Then, from the laser interferometer 18 on the wafer side in FIG. 1 to the mirror surface 22x of the wafer stage 22 in the X direction, the five-axis laser beam composed of the first The laser beams are irradiated in parallel, and a three-axis laser beam including the first to third laser beams LBY to LBY3 is irradiated on the mirror surface 22y of the wafer stage 22 in the Y direction in parallel with the Y axis. .

In this case, the eight-axis laser beams LBX1 to LBX1
Each of the LBYs 3 is of a double-pass type. Each of the LBYs 3 interferes with a laser beam reflected from, for example, a reference mirror (not shown) provided on the side surface of the projection optical system 17 so that the displacement at the corresponding measurement point is a single-pass. It is measured with a finer resolution of 1/2 compared to the method. Then, the optical axis 31X of the two-axis laser beams LBX1 and LBX2 and the optical axis 31 of the one-axis laser beam LBX4
A is parallel to the X axis and is the optical axis AX of the projection optical system 17;
And two laser beams LBY1 and LBY on a straight line passing through the detection center 19a of the alignment sensor 19,
The optical axis 31Y of BY2 is parallel to the Y axis, and their optical axes AX
And on a straight line passing through the detection center 19a.

Therefore, during normal exposure, the average value of the displacement measured by the X-axis laser beams LBX1 and LBX2 is changed to the average value of the displacement measured by the X-coordinate of the wafer stage 22 and the Y-axis laser beams LBY1 and LBY2. Is the Y coordinate of the wafer stage 22, the displacement of the wafer stage 22 with respect to the optical axis AX of the projection optical system 17 can be measured with high accuracy without Abbe error caused by the yawing amount. Further, a difference between displacements measured by the laser beams LBX1 and LBX2,
Alternatively, the yawing amount of the wafer stage 22 can be obtained from the difference between the displacements measured by the laser beams LBY1 and LBY2. Further, in this example, as can be seen from FIG. 1, the optical path of the laser beam from the laser interferometer 18 deviates by a predetermined amount (referred to as HZ1) below the surface of the wafer W1 in the Z direction. Stage 22
Tilt angle around the X axis (pitching amount during scanning exposure),
Or the tilt angle around the Y axis (rolling amount during scanning exposure)
Occurs, Abbe errors are mixed in the Y coordinate and the X coordinate of the wafer stage 22, respectively.

In order to correct the Abbe error, a laser beam LBY3 is applied to a position shifted from the laser beams LBY1 and LBY2 by an interval HZ2 in the Z direction in FIG.
3 and the laser beam LBY
The pitching amount θX of the wafer stage 22 is obtained by dividing the difference from the Y coordinate detected via the LBY2 by the interval HZ2. This pitching amount θX
The stage control system 16 shown in FIG. 1 calculates θY ·
By subtracting HZ1, the Y coordinate obtained by correcting the Abbe error is obtained. Similarly, on the X axis, the laser beam LBX3 is irradiated at a position shifted in the Z direction with respect to the laser beams LBX1 and LBX2, and Abbe error caused by the rolling amount θY is corrected by using the measured value. I have.

On the other hand, when aligning the wafer, the displacement measured by the X-axis laser beam LBX4 is used as the X coordinate of the wafer stage 22, so that the displacement of the wafer stage 22 with respect to the detection center 19a of the alignment sensor 19 is used as a reference. , High-accuracy measurement without Abbe error caused by yawing amount. Also at this time, the laser beam LBX5 is applied to a position shifted from the laser beam LBX4 by the interval HZ2 in the Z direction in order to correct the Abbe error caused by the rolling amount of the wafer stage 22.

A reference plate 34 and an aerial image measurement system 3 are mounted on the wafer stage 22 around the wafer holder 21.
5, and an illuminance unevenness sensor 36. A reference mark 34a for the alignment sensor 19 and reference marks 34b and 34c for the reticle on the reticle stage 10 in FIG. 1 are formed on the surface of the reference plate 34. By using these reference marks, the reticle is used. (In this example, it is assumed to match the optical axis AX) and the detection center 1 of the alignment sensor 19
A baseline amount, which is an interval with 9a, is detected. Further, as the aerial image measurement system 35, for example, the knife edge 3
A photoelectric sensor or the like that receives the amount of light passing through 5a is provided. By processing a detection signal of the photoelectric sensor, the best focus position, image quality (resolution and the like) of a projected image by the projection optical system 17, and distortion are obtained. Are measured, and the measurement results are supplied to the main control system 5. Further, the illuminance unevenness sensor 36 measures the illuminance distribution and the like of the exposure light in the rectangular exposure area 30.

Now, in order to execute the above-described alignment and exposure, it is necessary to exchange a wafer and a reticle. Hereinafter, a reticle loader system and a wafer loader system of the projection exposure apparatus of FIG. 1 will be described. First,
Regarding the reticle loader system, a reticle load arm 6 and a reticle unload arm 7 are movably arranged near a reticle base 13 along a transfer mechanism (not shown). Suction units 9 and 8 are provided. The operation of these arms 6 and 7 is controlled by an R / W loader system control system 15 composed of a computer. Further, a reticle rotating upper and lower portion 14 having a spindle which can be protruded and retracted and is rotatable within the movement stroke of the reticle stage 10 within the reticle base 13 is disposed, and the imaging system 2 is disposed above the reticle rotating upper and lower portions 14. Are supplied to the image processing apparatus 1. The operation of the reticle rotating upper / lower part 14 is also R /
It is controlled by the W loader system control system 15.

When the reticle is replaced, the used reticle R1 is transferred to the suction section 8 of the reticle unload arm 7 via the raised spindle of the reticle rotating upper / lower section 14, and then the reticle R on the reticle load arm 6 is transferred. Is once mounted on the upper end of the spindle on which the reticle rotating upper and lower portions 14 protrude, and is suction-held. In this state, the image signal of the image sensor 2 is processed by the image processing apparatus 1 to determine the shift amount of the center position of the reticle R and the rotation error, and the result is supplied to the R / W loader system control system 15. Is done. The R / W loader system control system 15 controls the reticle stage 1 so as to correct the shift amount of the center position of the reticle R.
After the position of 0 is corrected and the rotation angle of the spindle is corrected via the reticle rotation upper and lower portions 14 so as to correct the rotation error, the spindle is lowered and the reticle R is mounted on the reticle stage 10. Thus, reticle R is loaded on reticle stage 10 in a state where pre-alignment has been performed.

Next, the loading of the wafer into the wafer holder 21 on the wafer stage 22 and the wafer holder 2
A wafer loader system for unloading a wafer from No. 1 will be described. In FIG. 1, a wafer loader system is disposed near the side surface of the projection optical system 17 in the −Y direction at a position that does not mechanically interfere with the laser interferometer 18 on the wafer side. That is, a wafer pre-alignment drive unit 24 is installed on a side surface of the projection optical system 17, and a rotating upper and lower unit 25 is arranged on the bottom surface of the wafer pre-alignment driving unit 24 in parallel with the Z axis. A load arm (wafer carrying arm) 28 is fixed. The wafer load arm 28 is an arm that holds the wafer W to be carried in from above and holds the wafer W. The wafer load arm 28 can be relatively displaced in the Z direction by, for example, a direct-acting spindle system by the rotating upper and lower portions 25, and can rotate. By rotating the upper and lower parts 25 as a whole, the wafer load arm 28 can be rotated clockwise and counterclockwise in a predetermined angle range around the center of rotation.

The wafer pre-alignment drive unit 24
Is provided with an image pickup device 26 for detecting the position of the contour of the outer shape of the wafer W held by the wafer load arm 28. The imaging device 26 includes a plurality of imaging devices arranged at different positions according to a plurality of detection positions of the outer shape of the wafer W as described later, and each imaging device includes an enlarged imaging system, a CCD type, and the like. It is composed of a two-dimensional image sensor. Further, in this example, an illumination system support portion having a plurality of illumination systems for transmitted illumination is removably arranged on the bottom surface of the wafer W held by the wafer load arm 28, and the imaging device 26 is provided by the transmitted illumination. Are supplied to the R / W loader system control system 15 via the wafer pre-alignment drive unit 24, and the R / W loader system control system 15 processes these image signals to perform image processing on the wafer W. (Hereinafter, referred to as “pre-alignment” in this example). Then, the wafer holder 2 on the wafer stage 22 is
The wafer W is transferred on the first wafer. The wafer loader system further includes a wafer unload arm for unloading the exposed wafer W1 on the wafer holder 21,
A wafer transfer arm for transferring the wafer W from the wafer transfer line to the wafer load arm 28 is also provided.

The wafer load arm 28 and the imaging device 26 each have a diameter of 12 inches (about 300 m).
m) is a member for a wafer (12-inch wafer), for example, when exposing a wafer (8-inch wafer) having a diameter of 8 inches (about 200 mm), another wafer load arm corresponding to the exposure, and the imaging device 27 Is used. Similarly, the wafer holder 21 is also for a 12-inch wafer,
When exposing an inch wafer, another small wafer holder is used. In addition, for example, the wafer holder 21 may be commonly used for wafers of a plurality of sizes.

Next, the support mechanism of the wafer loader system and the wafer unload arm will be described in detail. FIG.
FIG. 5A shows the support mechanism of the projection optical system 17 as described above. In FIG. 5A, a support member 48 made of a material having a low expansion coefficient for supporting the projection optical system 17 is shown.
, A wafer pre-alignment drive unit 24 is fixed, and the rotating upper and lower
5, the wafer load arm 28 is movably and rotatably held in the Z direction. In this case, the wafer W held by the wafer load arm 28 is configured to be able to move up and down in a range of (g1 + g2) from the bottom surface of the holding portion 48a holding the projection optical system 17 to the upper surface of the wafer holder 21 in the Z direction. , As an example, the interval (g1
+ G2) is 50 mm.

The wafer pre-alignment drive unit 24
The illumination system rotation shaft 46 is rotatably installed at a position on the bottom surface of the illumination device that does not contact the wafer W held by the wafer load arm 28, and an illumination system support unit having a plurality of illuminations at the lower end of the illumination system rotation shaft 46. 45 is fixed. At the time of pre-alignment of the wafer W, the wafer W is raised to a position close to the holding portion 48a due to the rising of the rotating upper and lower portions 25, and the bottom surface of the wafer W within the range of the gap g1 from the bottom surface of the holding portion 48a is illuminated. The illumination system support 45 is inserted by the rotation of the system rotation shaft 46. On the back side of the wafer pre-alignment drive unit 24, a wafer transfer mechanism support unit 42 is installed, and the wafer transfer mechanism support unit 42 is disposed within the range g2 from the bottom surface of the illumination system support unit 45 to the upper surface of the wafer holder 21. A wafer transfer arm 43 and a wafer unload arm (wafer unloading arm) 38 are attached. As an example, the interval (g1 + g2) is 50 m
m, the interval g2 is 30 mm (the interval g1 is 20 m
m), and the wafer unload arm 38 has the same shape as the wafer load arm 28.

The wafer transfer arm 43 can be moved in the Y direction by a drive unit (not shown) along a slit-shaped opening 42a formed parallel to the Y axis above the wafer unload arm 38. Further, the wafer transport mechanism support section 4
2, a slit-shaped opening 42b is formed below the opening 42a in parallel with the opening 42a, and the wafer unload arm 38 is supported along the opening 42b by a driving unit (not shown) so as to be movable in the Y direction. ing. Further, the wafer unload arm 38 is positioned in the width direction (Z direction) of the opening 42b.
Is supported so that it can be moved up and down within a predetermined range. The wafer transfer mechanism support section 42 is attached to a member different from the support member 48 that supports the projection optical system 17. As described above, the support member 48 for the projection optical system 17 and the wafer pre-alignment drive unit 24 and the wafer transfer mechanism support unit 42
Are fixed to different members from each other, vibrations generated in the wafer transfer arm 43 and the wafer unload arm 38 are not transmitted to the wafer pre-alignment drive unit 24 and the projection optical system 17, so that the pre-alignment and the Positioning at the time of exposure can be performed with high accuracy.

Although not shown, a wafer transfer line for transferring the unexposed and exposed wafers to a resist coater / developer or the like is provided on the right side of the wafer transfer mechanism support section 42. . Wafer transfer arm 43
Opens the wafer before exposure on the wafer transfer line through the opening 42
The wafer unload arm 38 plays a role of transporting the exposed wafer unloaded from the wafer holder 21 to the wafer transport line along the opening 42b along the line a. Further, when the wafer is transferred from the wafer transfer line to the wafer transfer arm 43, as an example, the position of the wafer and the rotation angle are roughly determined based on the outer shape via a turntable and a position detection device (not shown). Adjustments have been made. If the adjustment of the position and the like using the turntable or the like is regarded as the first preliminary alignment, the pre-alignment of the wafer W held on the wafer load arm 28 is performed in the same manner as the second preliminary alignment. Can also be considered.

As described above, when the wafer W is transferred from the wafer transfer arm 43 to the wafer load arm 28,
As shown in FIG. 5B, the illumination system support 45 is retracted by the rotation of the illumination system rotation shaft 46. Then, with the wafer load arm 28 lowered to a slightly lower height than the opening 42a in FIG.
After the center of the wafer W is moved to the center of the rotating upper and lower portions 25 by 3, the wafer W is transferred to the wafer load arm 28 by raising the wafer load arm 28. These rotating upper and lower portions 25, the illumination system rotating shaft 4
The operations of the wafer transfer arm 43 and the wafer unload arm 38 are controlled by the R / W loader system control system 15 shown in FIG. It exchanges timing information.

FIG. 3 is a plan view showing the positional relationship between the wafer stage 22 and the wafer loader system in the projection exposure apparatus of this embodiment. FIG. 3 shows a system for a 12-inch wafer. At this time, the wafer load arm 28
It has a structure in which a wafer W to be carried in is held from above, and suction portions 50A and 50B for holding the wafer by vacuum suction are formed at two contact portions with the wafer, as shown in FIG. The suction portions 50A and 50B protrude further below the bottom surface of the wafer W to be held. Similarly,
The wafer unload arm 38 shown in FIG. 3 also has suction portions 49A and 49B for holding a wafer to be unloaded (referred to as a wafer W1) from the bottom side by vacuum suction, and these suction portions 49A and 49B. Also protrude below the bottom surface of the wafer W1. Therefore, these suction units 50
Two grooves 37A, 37B are formed in parallel from the upper surface of the wafer holder 21 to the upper surface of the wafer stage 22 so that A, 50B, 49A, 49B do not contact the surface of the wafer holder 21 on the wafer stage 22.

The distance between the grooves 37A and 37B is equal to the distance between the suction parts 50A and 50B in the wafer load arm 28, that is, the suction parts 49A and 49A in the wafer unload arm 38.
The width of each of the grooves 37A, 37B is the same as the spacing of the suction parts 50A, 50B and 49A, 49B.
Are formed wider than the width of the lower end of each
The depth of each of the suction portions 50A, 50B
And 49A, 49B. In this example, depending on the result of the pre-alignment, the wafer load arm 28 is rotated by a predetermined angle via the rotating upper and lower portions 25, and the wafer stage 22 is driven in a state where the suction portions are inserted into the grooves 37A and 37B. In some cases, the width of the grooves 37A and 37B is set with a margin in order to meet the upper limit of the change in the distance between the suction portions 50A and 50B.

In this configuration, the wafer load arm 2
In order to transfer the wafer W from 8 to the wafer holder 21,
After moving the wafer stage 22 so that the center of the wafer holder 21 coincides with the center of the rotating upper and lower portions 25, the wafer load arm 28 is lowered to insert the suction portions 50A and 50B into the grooves 37A and 37B. 2
2 may be moved to the upper left in parallel with the grooves 37 and 37B. Conversely, when transferring the wafer W1 from the wafer holder 21 to the wafer unload arm 38, the center of the wafer unload arm 38 is made to coincide with the center of the rotating upper and lower portion 25 in advance, and the heights of the suction portions 49A and 49B are adjusted. The groove 37
The wafer stage 22 is moved in parallel with the grooves 37A and 37B in a state where the wafer holder 21
May be moved to the center of the rotating upper and lower portions 25, and then the wafer unload arm 38 may be raised.

As described above, the vertical movement of the wafer upper and lower pins, which is conventionally provided in the wafer holder so as to be freely retractable, is replaced by the lifting operation of the wafer load arm 28 and the wafer unload arm 38. For example, by replacing the retreat operation performed on the wafer load arm and the wafer unload arm with the movement operation of the wafer stage 22, it is not necessary to provide wafer upper and lower pins on the wafer holder 21 side. Accordingly, the configuration of the wafer stage 22 can be simplified, and
The step moving speed and the scanning speed of the wafer stage 22 can be reduced without increasing the output of a driving motor such as a linear motor for driving the wafer stage 22 and thus increasing the amount of heat generated. Can be easily improved, so that the throughput of the exposure step is improved.

The grooves 37A, 37 provided from the wafer holder 21 to the upper surface of the wafer stage 22 are provided.
The length of B is, in short, the suction parts 50A, 50B (or 49A,
49B) and the wafer W (or W1) as long as they do not overlap with each other.
Considering variations in the timing at which the wafer stage 8 is lowered and the timing at which the wafer stage 22 is moved, it is desirable to set the length to a certain margin.

However, if the thickness of the wafer holder 21 on the wafer stage 22 is not equal to the thickness of the suction portion 50A, 50B or 49
When the thickness is larger than the thickness of A and 49B, the grooves 37A and 37B may be provided only on the wafer holder 21 and need not be provided on the wafer stage 22 side. In this case, since the ends of the grooves 37A and 37B are in an open state, the degree of freedom in the timing of raising the wafer load arm 28 and lowering the wafer unload arm 38 is increased. And the throughput is improved.

On the other hand, when the thickness of the wafer holder 21 is substantially equal to or smaller than the thickness of the suction portions 50A, 50B or 49A, 49B as in this example, the upper surface of the wafer stage 22 is flat. In order to prevent contact with the suction portions 50A, 50B or 49A, 49B, the grooves 37A, 37B need to be formed long as shown by the solid line in FIG. This is because the wafer stage 22
This also applies to the case where the wafer holder 21 is also used, that is, the case where the upper surface of the wafer stage 22 and the upper surface of the wafer holder 21 are on the same plane. In this case, the groove 37A,
37B end part etc. and adsorption part 50A, 50B or 49A, 4
In order to prevent contact with the wafer 9B, for example, it is desirable to reduce the moving speed of the wafer stage 22 when replacing the wafer, so that the throughput may be reduced.

Therefore, in this embodiment, a step 39 having a predetermined depth is formed in a lower left portion of the wafer holder 21 on the upper surface of the wafer stage 22. The sum of the depth of the step portion 39 and the thickness of the wafer holder 21 is determined by the suction portions 50A and 50B.
Alternatively, the thickness is set so as to have a margin with respect to the thickness of 49A and 49B. Thereby, the groove portions 37A,
37B does not need to be formed inside the edge portion 39a of the step portion 39, so that the wafer stage 22 can be moved at a higher speed than in the case where the grooves 37A and 37B are formed longer, and the throughput is improved.

In FIG. 3, the wafer W held on the wafer load arm 28 is pre-aligned, and the wafer W2 to be exposed next to the wafer W is held on the wafer transfer arm 43. Wafer transfer arm 43
A suction portion 44 for vacuum-sucking the wafer is also formed at the tip of the device. In this case, the imaging device 26 is positioned above five locations on the outer periphery of the wafer W held by the wafer load arm 28.
L, 26N1, 26R, 26N2, 26U are arranged,
The detection centers of these five imaging devices 26L to 26U are respectively set on the same circumference centered on the rotation axis (center axis) of the rotating upper and lower part 25. On the bottom surface side of the wafer W, an illumination system support portion 45 is rotatable around an illumination system rotation shaft 46.
Are arranged, and in FIG. 3, the imaging devices 26L, 26N1, 2
The rotation angle of the illumination system support unit 45 is set so that the illumination system in the illumination system support unit 45 is arranged to face 6R.

FIGS. 6A to 6D are explanatory views of the operation when pre-alignment is performed on a 12-inch wafer W. FIG. This shows a state in which the evacuation is performed. The illumination system support section 45 includes six illumination systems 47L, 47N2, 47R1, 47
U, 47N1, 47R2 are fixed, and these illumination systems each include a light source for generating illumination light, a condenser lens, and the like. In the case of a 12-inch wafer W, for example, a notch N1 (hereinafter referred to as “0 ° direction”) according to the standard of the Semiconductor Industry Association (SIA) and a position rotated 90 ° with respect to the notch N1 are referred to. A certain 90 ° notch N2 is provided. The position and number of the notches are arbitrary, and an orientation flat or the like may be provided instead of the notches.

When such two notches N1 and N2 are provided, the image pickup device 2 is configured to observe the notches N1 and N2.
6N1 and 26N2 are installed, and the imaging devices 26L and 26R are installed so as to observe the left and right outer peripheries of the notch N1.
The imaging device 26 is configured to observe the left and right outer peripheries of the notch N2.
R and 26U are installed. When detecting the notch N1 and the positions of the outer periphery of the left and right wafers W,
As shown in FIG. 6B, the illumination system support 45 is rotated by 90 ° from the state shown in FIG.
6L, 26N1, 26R. Then, by processing the image signals of the imaging devices 26L and 26R, for example, a two-dimensional displacement amount of a point closest to the detection center on the outer periphery of the wafer W from the detection center is obtained.
As for the notch N1, by processing the image signal of the imaging device 26N1, for example, as shown in FIG. Intersection of a straight line that divides equally and an arc that virtually extends the outer periphery of the wafer W (hereinafter, referred to as an intersection)
A two-dimensional displacement amount from the detection center of Q2 (referred to as “center of notch”) is obtained.

Next, when detecting the notch N2 and the positions of the outer periphery of the left and right wafers W, as shown in FIG. 6C, the illumination system support 45 is further moved from the state of FIG. Is 9
The illumination system 47R2 in the illumination system support 45 is rotated by 0 °.
47N and 47U are imaging devices 26R and 26N, respectively.
2,26U. Then, the imaging devices 26R, 26R
By processing the U image signal, for example, a two-dimensional displacement amount of a point closest to the detection center on the outer periphery of the wafer W is obtained. The amount of displacement of the center of N2 is obtained.

After that, the R / W loader system control system 15 processes the displacement of the outer periphery of the wafer W and the center of the notches N1 and N2 by using the least square method or the like, whereby the rotation shown in FIG. The amount of displacement of the center of the wafer W with respect to the rotation axis of the upper and lower portions 25 in the X and Y directions (ΔWX,
ΔWY) and the wafer W based on the notches N1 and N2.
Is calculated (rotational error) ΔθW. The rotation error ΔθW based on the notches N1 and N2 is, for example, an average value of the inclination angles of the straight lines connecting the centers of the notches N1 and N2 and the center of the wafer W with respect to the Y axis and the X axis. Thereafter, the R / W loader system control system 15 rotates the rotating upper / lower portion 25 of FIG. 3 so as to cancel the rotation error ΔθW, corrects the rotation angle of the wafer W, and shifts the position error (ΔWX, ΔWY) is supplied to the main control system 5. In the main control system 5, the position deviation amount (ΔWX, ΔWY) is
Is added to the offset when the final alignment (fine alignment) is performed.

As described above, in the present embodiment, the position of the wafer W at the two sets of measurement points is detected by rotating the illumination system support 45 in two steps. Even if the wafer is an inch wafer, the illumination system support portion 45 can be downsized, and the wafer loader system can be downsized. 3 and 6 show a mechanism for a 12-inch wafer, but when the exposure target wafer is an 8-inch wafer, the mechanisms shown in FIGS. 4 and 7 are used, respectively.

FIG. 4 is a plan view corresponding to FIG. 3 showing a wafer loader system for performing exposure on an 8-inch wafer. In FIG. A large disk-shaped wafer holder 21S is fixed to the groove, and grooves 37SA and 37SB are formed in parallel so as to contact both ends of the wafer holder 21S. Also in this case, when the wafer holder 21S is thick, the grooves 37SA and 37SB do not need to be formed on the wafer stage 22.
Or, even when integrated with the wafer stage 22,
By providing the step portion 39, the groove portions 37SA, 37
The SB does not need to be formed inside the edge portion 39a of the step portion 39, so that the wafer stage 22 can be moved at a high speed, and the throughput is improved. Note that the wafer stage 22 may be further miniaturized.

The size of the wafer load arm 28S for holding the 8-inch wafer WS during pre-alignment is also reduced. ,
27L are arranged. Also, the wafer load arm 2
Suction unit 50 that also holds wafer W from the bottom surface in 8S.
A, 50B are formed, and these suction portions 50A, 50B are formed.
Are set in the grooves 37SA and 37SB.
Further, the illumination system support portion 45 is removably inserted into and removed from the bottom surface of the wafer WS by rotating about the illumination system rotation shaft 46 as a center.
S are arranged, and five illumination systems are mounted in the illumination system support part 45S. In addition, the wafer unload arm 3
8S is also downsized to match the 8-inch wafer WS1,
An 8-inch wafer WS2 is also mounted on the wafer transfer arm 43. Other configurations are the same as those in the example of FIG.

FIGS. 7A and 7B are explanatory diagrams of the operation when pre-alignment is performed on an 8-inch wafer WS. FIG. 7A shows that the illumination system support portion 45S is connected to the wafer WS.
3 shows a state in which it has been retracted from the bottom surface of FIG. Lighting system support 4
5S has five illumination systems 48L, 48D, 48N1, 4
8N2 and 48R are fixed. The 8-inch wafer WS is also provided with a notch N1 ′ in the 0 ° direction and / or a notch in the 90 ° direction at a position rotated by 90 ° with respect to, for example, the SIA standard. Also in this example, the position and the number of the notches are arbitrary, and an orientation flat or the like may be provided instead of the notches.

In the example of FIG. 7A, the notch N1 'at 0 °
The imaging devices 27N1, 27N2 are installed so as to observe notches (not shown) at 90 ° and the imaging devices 27D, 27L, 27R are installed so as to observe the position of the outer periphery of the wafer WS clockwise from the notch N1 ′. Have been. When detecting the position of the outer periphery of the wafer WS, FIG.
As shown in FIG. 7B, the illumination system support 45S rotates 90 ° from the state shown in FIG.
The illumination systems 48N1 to 48N2 are provided in the imaging device 27, respectively.
N1 to 27N2. And five imaging devices 2
By processing the image signals of 7N1 to 27N2,
4, the amount of displacement of the center of the wafer WS with respect to the rotation axis of the rotating upper and lower portions 25 in the X direction and the Y direction, and the notch N1 '
The rotation error of the wafer WS based on the above is calculated.

As described above, in the case of an 8-inch wafer, even if an illumination system for simultaneously illuminating the detection visual fields of all the imaging devices 27N1 to 27N2 is provided, the illumination system support portion 45S does not become so large. Can be illuminated. Therefore, pre-alignment can be performed at high speed. A more detailed method for detecting the center position and the rotation angle of the wafer from the positions detected in the plurality of detection areas on the outer periphery of the wafer is described in, for example, Japanese Patent Application No. 9-362.
No. 02. Further, an 8-inch wafer may have an orientation flat other than the notch. In order to use both the illumination of the orientation flat and the illumination of the notch, an illumination system supporting portion 45S may be provided with a fluorescent lamp or a fluorescent plate having a large illumination area.

Next, a series of operations at the time of pre-alignment of the wafer W shown in FIG. 3 will be described with reference to the flowchart of FIG. 8 and FIG. 9A to 9F schematically show the lower part of the projection optical system 17 and the wafer loader system, respectively. First, in step 101 of FIG.
The wafer load arm 28 in FIG. 9A is moved to a wafer receiving position at a height that does not mechanically interfere with the wafer unload arm 38. At this time, it is assumed that the illumination system support unit 45 has been retracted. Then, the wafer transfer arm 43
(Assuming the wafer W) is moved along the wafer transfer mechanism support section 42 in the + Y direction to the wafer receiving position. Then, in step 102, the vacuum suction of the wafer transfer arm 43 is turned off, and the vacuum suction of the suction units 50A and 50B (see FIG. 3) of the wafer load arm 28 is turned on, so that the wafer load arm 28 is moved in the Z direction. Raise to the pre-alignment position. As a result, the wafer W is delivered to the suction portions 50A and 50B of the wafer load arm 28.

In the next step 103, the illumination system support 45 is moved to the first measurement position (the state shown in FIG. 6B) on the bottom surface of the wafer W via the illumination system rotation shaft 46, and the illumination light is reduced. Irradiate. This state is the state shown in FIG. Then, the imaging devices 26L, 26N1,
The 26R image signal is taken into the R / W loader system control system 15 of FIG. Next, the illumination system support unit 45 is further moved to the second measurement position (the state shown in FIG. 6C) on the bottom surface of the wafer W via the illumination system rotation shaft 46, and the imaging apparatus shown in FIG. 2
The image signals of 6R, 26N2, and 26U are taken into the R / W loader system control system 15 of FIG.

In the subsequent step 104, R /
The W loader system control system 15 processes these image signals as described above, and uses the amount of displacement (ΔWX, ΔWY) of the center of the wafer W with respect to the rotation axis of the rotating upper and lower portions 25 and the notch as a reference. The calculated rotation error ΔθW is calculated. Further, in step 105, the R / W loader system control system 15 rotates the wafer load arm 28 by −ΔθW via the rotating upper / lower part 25 and keeps the wafer load arm 28 on standby. It is supplied to the main control system 5. In the present example, the positional deviation amounts (ΔWX, ΔWY) are considered as offsets when the final alignment of the wafer W is performed. Instead, for example, when the wafer stage 22 is moved to the loading position in FIG. Alternatively, the position of wafer stage 22 may be shifted by the position shift amount (ΔWX, ΔWY). Thereafter, in step 106, as shown in FIG. 9 (b), the pre-alignment is completed by rotating the illumination system rotation shaft 46 to retract the illumination system support 45. Thereafter, the wafer exchange is performed. Further, during the execution of the pre-alignment, the exposure on the wafer W1 is being executed on the wafer stage 22 in parallel.

Next, an example of the wafer exchange, the final alignment of the wafer, and the exposure operation of the wafer will be described with reference to the flowchart of FIG. In step 111 of FIG. 10, the wafer stage 22 is moved so that the center of the wafer holder 21 (also referred to as the “center of the wafer stage 22”) matches the wafer loading position, as shown in FIG. 9B. . The “loading position” in this example is a point at which a plane including the surface of the wafer holder 21 intersects with the center line (rotation axis) of the rotation upper and lower portion 25 of the wafer load arm 28. In the following, the wafer holder 2
Driving wafer stage 22 so that the center of 1 moves to a predetermined point is simply referred to as moving wafer stage 22 to the predetermined point. Further, as shown in FIG. 9B, before the wafer stage 22 moves to the loading position, the center of the wafer unload arm 38 reaches above the loading position in advance along the wafer transfer mechanism support portion 42, and The positions of the suction portions 49A and 49B (see FIG. 3) of the wafer unload arm 38 in the Z direction are set to positions that fit in the grooves 37A and 37B on the wafer stage 22. This position is referred to as a “wafer delivery position”. Accordingly, the wafer stage 22 is moved to the loading position after the exposure of the wafer W1 is completed, so that the suction portions 49A and 49B of the wafer unload arm 38 are inserted into the bottom surface of the wafer W1. At this time, the wafer load arm 28 is on standby so as to overlap the wafer unload arm 38.

In step 112, the vacuum suction of the wafer holder 21 is turned off, the vacuum suction of the wafer unload arm 38 is turned on, and the wafer unload arm 38 is moved in the Z direction by a predetermined amount (here, the wafer W).
1 and suction portions 49A, 49 of wafer unload arm 38
B is raised to a position where it does not mechanically interfere with the wafer stage 22 or the wafer holder 21). by this,
The exposed wafer W1 is transferred from the wafer holder 21 to the wafer unload arm 38. Thereafter, in step 113, as shown in FIG. 9C, the wafer load arm 28 is moved in the -Z direction while the wafer unload arm 38 is retracted in the -Y direction along the wafer transfer mechanism support portion 42. Then, it is lowered to a position where it does not mechanically interfere with the wafer unload arm 38 and waits. This avoids contact when the movement timing of the wafer unload arm 38 is deviated, and reduces the distance from the wafer load arm 28 to the wafer stage 22 after the wafer unload arm 38 is retracted. This is because it can be shortened.

Then, in step 114, FIG.
As shown in (d), the wafer load arm 28 is lowered to the wafer transfer position. Thus, the suction portions 50A and 50B of the wafer load arm 28 of FIG. 3 are stored in the grooves 37A and 37B on the wafer stage 22.
Thus, the suction portions 50A, 50B are formed by the grooves 37A, 37B.
Immediately before being stored in B, the vacuum suction of the wafer load arm 28 is turned off. In the next step 115, by turning on the vacuum suction of the wafer holder 21,
An unexposed wafer W is transferred from the wafer load arm 28 to the wafer holder 21. In parallel with this operation, FIG.
In (d), the wafer unload arm 38 is further
The wafer W1 is moved in the Y direction to a wafer transfer line (not shown), and returns after passing the wafer W1 to the wafer transfer line.

In the next step 116, FIG.
As shown in (2), after moving the wafer stage 22 and pulling out the wafer load arm 28 from the bottom surface of the wafer W,
The wafer load arm 28 is raised. Specifically, FIG.
As shown in FIG.
B to the upper left in parallel with the wafer load arm 2
When the suction portions 50A and 50B of the wafer 8 come off the back surface of the wafer W, the wafer load arm 2
8 is moved up to a position where the wafer transfer arm 43 can receive the transferred wafer, that is, a wafer receiving position. In a subsequent step 117, as shown in FIG. 9F, the wafer stage 22 is sequentially moved to the alignment position, the baseline amount measurement position, and the exposure position, and the final alignment (fine alignment) with respect to the wafer W is performed. And exposure. In parallel with this, after the center of the wafer transfer arm 43 on which the next wafer W2 to be exposed is mounted moves to the center of the wafer load arm 28, the wafer load arm 28 is raised, so that the wafer load arm 28 The wafer W2 is delivered. This is the same as the operation of steps 101 and 102 in FIG. At this time, the wafer unload arm 38 waits at the wafer transfer position as shown in FIG. Thereafter, in step 118, the above operation is repeated to expose the next wafer.

Next, the wafer W in step 117 in FIG.
FIG. 1 shows an example of alignment and exposure operation for
This will be described with reference to FIGS. First, FIG. 11 shows a state in which the wafer stage 22 has been moved to the loading position P1 (indicated by an asterisk; the same applies hereinafter) as in step 111, that is, the center of the wafer holder 21 has been moved on the center line of the rotating upper and lower part 25. In this FIG. 11,
The wafer W is delivered from the wafer load arm 28 onto the wafer holder 21. Even in this state, the end of the side surface of the wafer stage 22 is irradiated with the laser beam from the laser interferometer 18 in FIG. 1, and the position of the wafer stage 22 is measured with high accuracy.

Next, FIG. 12 shows a trajectory of the wafer stage 22 when a final alignment (fine alignment) of the wafer W is performed, that is, a trajectory 40 of the center of the wafer holder 21. The wafer stage 22 shown in FIG. After moving from the state to the upper left along the grooves 37A and 37B, the suction portions 50A and 50B of the wafer load arm 28 are separated from the bottom surface of the wafer W, and then three alignment positions P2 and P3 are sequentially shown as indicated by a trace 40. , P4. In this example, it is assumed that two-dimensional fine alignment wafer marks are respectively attached to all the shot areas on the wafer W, and three shot marks that do not exist on the same straight line previously selected from the shot areas are assumed. Wafer marks WM1, WM2 in the shot area (sample shot)
The coordinates (X, Y) of WM3 are set to the alignment sensor 1 in FIG.
9 and processing this measurement result to calculate the array coordinates of all shot areas on the wafer W. This can be regarded as EGA (Enhanced Global Alignment) type alignment in which the number of sample shots to be measured is at least three. This method can also be called a three-point EGA method. In addition,
The number of sample shots may be set to, for example, three or more (for example, eight). Further, since the EGA type alignment method is disclosed in, for example, Japanese Patent Application Laid-Open No. 61-44429, a detailed description thereof will be omitted.

Then, the first alignment position P2 is
It is determined by correcting the designed shot arrangement of the wafer W with the result of the pre-alignment step of FIG. That is, the misalignment of the center of the wafer W obtained in step 105 of FIG. The array coordinates obtained by adding ΔWX, ΔWY) as an offset are referred to as array coordinates (SX1, SY1) after the first offset correction. Then, from the array coordinates of the wafer mark WM1 after the first offset correction, the position of the wafer stage 22 for matching the wafer mark WM1 with the detection center 19a in the detection field 19b of the alignment sensor 19 is obtained. This position is the first alignment position P2. As a result, the wafer stage 22 moves to the first alignment position P2.
Is reached, the wafer mark WM1 on the wafer W falls within the observation visual field 19a. For this reason, in the present embodiment, the search alignment step for obtaining a rough shot arrangement on the wafer W is not required. This is possible because the pre-alignment accuracy of the present embodiment is high.

When measuring the coordinates (XM1, YM1) of the wafer mark WM1 via the alignment sensor 19, the amount of displacement (ΔEX1, ΔEY1) in the X and Y directions with respect to the detection center 19a of the wafer mark WM1.
Is calculated, and the array coordinates after the first offset correction (S
X1, SY1) is further shifted by the positional deviation amount (ΔEX1, ΔE
Y1) is corrected and the array coordinates (SX2, SX2) after the second offset correction are obtained. The X coordinates of the wafer stage 22 at the alignment positions P2 to P4 are adjusted so that the laser beams LBX4 and LB
It is measured using X5. Then, the displacement amount (ΔEX
After moving the wafer stage 22 so as to correct (1, ΔEY1), the coordinates (XM1 ′, YM1 ′) of the wafer mark WM1 are measured again via the alignment sensor 19. This is because, in the peripheral portion of the observation field of view 19b of the image processing method, there is a possibility that the position detection accuracy may be reduced due to the aberration of the imaging system. is there. Accordingly, when the aberration of the imaging system is extremely small even in the peripheral portion, or when particularly strict overlay accuracy is not required, it is not necessary to re-measure the position of the wafer mark WM1.

Next, referring to FIG.
2 is moved to the second alignment position P3, and the coordinates (X
M2, YM2) are measured. Its alignment position P3
Are the array coordinates (SX) after the second offset correction described above.
2, SX2), the wafer mark WM2 is aligned with the alignment sensor 19 based on the array coordinates of the wafer mark WM2.
Is the position of the wafer stage 22 determined to match the detection center 19a. In this case, in this example, a straight line connecting the coordinates (XM1 ′, YM1 ′) of the wafer mark WM1 and the coordinates (XM2, YM2) of the wafer mark WM2 is
An inclination angle に 対 す る with respect to a straight line connecting both marks WM1 and WM2 is determined in the design, and the wafer mark WM1 is calculated by the inclination angle Θ.
Is rotated about the second coordinate array (SX2, SX2) after the second offset correction, and the third offset and array coordinates (SX3, SX3) after the rotation angle correction are obtained.

Also here, the wafer W is tilted by the angle Θ.
Is the detection center 1 of the alignment sensor 19
9a, the position of the wafer stage 22 is finely adjusted, and the coordinates (XM2 ′, YM2) of the second wafer mark are again adjusted.
2 ') is measured. Thereafter, based on the third offset and the array coordinates (SX3, SX3) after the rotation angle correction, the wafer stage 22 is moved to the third alignment position P4.
To measure the coordinates (XM3, YM3) of the wafer mark WM3 via the alignment sensor 19. Then, from the measured values of the coordinates of the three wafer marks WM1, WM2, and WM3, the X direction and the Y direction of the shot array on the wafer W are determined.
Determine six conversion parameters including directional scaling, rotation, orthogonality error, and offsets in the X and Y directions, and use these conversion parameters to convert a designed shot array on the wafer W, The array coordinates of all shot areas on the wafer W are calculated. with this,
This means that the fine alignment of the wafer W has been completed.

Next, as shown in FIG. 13, the wafer stage 22 is moved to the baseline amount measurement position P5. At the baseline amount measurement position P5, the wafer stage 22
The upper reference plate 34 substantially overlaps the optical axis AX of the projection optical system 17 and the detection center 19a of the alignment sensor 19. In this state, the amount of misalignment between the alignment mark on the reticle R1 in FIG. 1 and the corresponding reference mark is measured, and the amount of misalignment between the detection center 19a of the alignment sensor 19 and the corresponding reference mark is measured. By adding the amount of displacement to the interval between the reference marks, a baseline, which is the interval between the center of the pattern image of the reticle R1 (here, coincident with the optical axis AX) and the detection center 19a of the alignment sensor 19, is obtained. The quantity BL is measured with high accuracy. Thereafter, the wafer W obtained in FIG.
By driving the wafer stage 22 based on the coordinates obtained by correcting the array coordinates of the upper shot area by the baseline amount, each shot area and the pattern image of the reticle R1 can be superimposed with high accuracy.

Then, as shown in FIG. 14, the wafer stage 22 is moved to the exposure start position P6 to start scanning exposure on each shot area SA on the wafer W. That is, the X coordinate of the wafer stage 22 is measured by using the laser beams LBX1 to LBX3 so that the Abbe error does not occur in the exposure area 30 by the projection optical system 17, and the shot area SA is traced by the exposure area 30. The wafer stage 22 is driven so as to meander and scan as indicated by 41. Thereafter, when exposure of all shot areas is completed, wafer stage 22 reaches exposure end position P7.
Thereafter, as shown by the trajectory 40, the wafer stage 22 is moved to the loading position P1 so that the wafer stage 22 moves parallel to the grooves 37A and 37B near the loading position P1. At this time, since the wafer unload arm 38 is waiting at the loading position P1 in advance, the wafer W can be transferred to the wafer unload arm 38 as it is.

According to the above embodiment, as shown in FIG. 5, the lower end of the rotating upper / lower section 25 attached to the wafer pre-alignment drive section 24 fixed to the support member 48 for supporting the projection optical system 17 is provided. In the wafer load arm 28, pre-alignment of the wafer to be exposed is performed,
Since the wafer is transferred to the wafer holder 21 on the wafer stage 22 while maintaining the position of the wafer, the positioning accuracy when the wafer is transferred to the wafer holder 21 is improved as compared with the related art. Therefore, the search alignment can be omitted, the time required for the entire alignment is reduced, and the throughput of the exposure process is improved.

The height of the wafer load arm 28 and the wafer unload arm 3 when performing pre-alignment
8 is shifted in the Z direction so that pre-alignment can be performed in parallel during the exposure operation.
Further, the throughput is improved. Furthermore, in this example, since the illumination system support portion 45 is retracted by rotating the illumination system rotation shaft 46, there is also an effect that generation of foreign matter in a region through which the wafer passes is suppressed.

The projection optical system 17 according to the above-described embodiment is used.
Is based on a refraction system. For example, ArF (wavelength 19
When excimer laser light or the like is used as exposure light, since there are few glass materials having good transmittance, a catadioptric system (catadioptric system) may be used as the projection optical system 17. The present invention can be applied to the case. Also, a wafer loader system of an exposure apparatus (for example, a scanning exposure type) using extreme ultraviolet light (EUVL or XVL) having a wavelength of about 100 nm or less as an exposure beam, and a soft X-ray or the like, or an electron beam drawing without using a mask The present invention is also applicable to a wafer loader system of the apparatus. Since it is desirable to make the optical path of extreme ultraviolet light or the like vacuum, instead of holding the substrate such as a reticle or a wafer by vacuum suction in the above-described embodiment, the substrate is held by a three-point support method in which the degree of parallelism is set strictly. Or it is necessary to apply a holding method by electrostatic attraction.

As the alignment sensor 19,
Instead of the image processing method, a laser step alignment (LSA) method, a two-beam interference method (LIA method), or the like may be used. Further, in the above embodiment, a step-and-scan type (scanning exposure type) projection exposure apparatus has been described, but the present invention relates to a batch exposure type projection exposure apparatus such as a stepper, or a projection optical system. The present invention is also applicable to a proximity type exposure apparatus that is not used. Further, the present invention can be applied to a wafer stage or the like of an electron beam exposure apparatus. As described above, the present invention is not limited to the above-described embodiment, and can take various configurations without departing from the gist of the present invention.

[0088]

According to the first method of transferring a substrate of the present invention, there is no need to provide a member for raising and lowering the substrate on the substrate stage side, so that the substrate stage can be downsized and the moving speed of the substrate stage can be reduced. And the positioning accuracy (controllability) can be improved. Further, after measuring the position of the substrate on the loading arm, the substrate is transferred to the substrate stage as it is, so that there is an advantage that the positioning accuracy when the substrate is placed on the substrate stage can be improved.

According to the second method of transferring a substrate of the present invention, a substrate is transferred by a combination of a horizontal movement of a substrate stage and a vertical movement of a carry-in arm and a carry-out arm. Therefore, the time required to exchange the substrate with the substrate stage can be reduced. Further, after measuring the position of the substrate on the loading arm, the substrate is transferred to the substrate stage as it is, so that the positioning accuracy when placing the substrate on the substrate stage can be improved. Therefore, in the third step, search alignment can be almost omitted, so that the throughput of the exposure step can be improved.

According to the first exposure apparatus of the present invention,
The method of transferring the first substrate can be used. And
When the carrying arm is provided, the method of transferring the second substrate can be used.

[Brief description of the drawings]

FIG. 1 is a partially cut-away configuration diagram illustrating a schematic configuration of a projection exposure apparatus used in an example of an embodiment of the present invention.

FIG. 2 is a plan view partially illustrating a laser beam array of the laser interferometer 18 of FIG.

FIG. 3 is a plan view showing a wafer stage 22 and a wafer loader system for a 12-inch wafer in FIG. 1;

FIG. 4 is a plan view showing a wafer stage 22 and a wafer loader system for an 8-inch wafer in FIG. 1;

FIG. 5A is a configuration diagram in which a support mechanism of the projection optical system 17 of FIG. 1 and a wafer loader system are partially cut away,
FIG. 4B is a main part diagram showing a case where the wafer is transferred from the wafer transfer arm 43 to the wafer load arm 28.

FIG. 6 is an explanatory diagram of a measurement method when performing pre-alignment of a 12-inch wafer in one example of the embodiment.

FIG. 7 is an explanatory diagram of a measurement method when pre-alignment of an 8-inch wafer is performed in an example of the embodiment.

FIG. 8 is a flowchart showing an operation when pre-alignment of a wafer is performed in an example of the embodiment.

FIG. 9 is a diagram for explaining a series of operations when performing wafer pre-alignment and wafer replacement.

FIG. 10 is a flowchart showing an operation in a case where wafer exchange, wafer alignment, and wafer exposure are performed in one example of the embodiment.

FIG. 11 is a plan view showing a state where the wafer stage 22 is at a loading position.

FIG. 12 is a plan view showing a state where the wafer stage 22 is moved to an alignment position and alignment is performed.

FIG. 13 is a plan view showing a state where the wafer stage 22 is moved to a baseline amount measurement position and a baseline amount is measured.

FIG. 14 shows a wafer stage 2 when exposing a wafer.
2 is a plan view showing the operation of FIG.

[Explanation of symbols]

 Reference Signs List 3 illumination optical system 4 illumination control system 5 main control system R, R1 reticle 10 reticle stage 12, 18 laser interferometer 13 reticle base 15 R / W loader system control system 16 stage control system 17 projection optical system W, W1 wafer 19 alignment Sensor 21 Wafer holder 22 Wafer stage 23 Wafer base 24 Wafer pre-alignment drive unit 25 Rotating vertical unit 26, 27 Imaging device 28 Wafer load arm 37A, 37A Groove 38 Wafer unload arm 42 Wafer transfer mechanism support 43 Wafer transfer arm 45 Illumination system Supporting part 46 Lighting system rotation axis 47L-47U Lighting part of lighting system for 12 inch wafer 48L-48D Lighting part of lighting system for 8 inch wafer 49A, 49B, 50A, 50B Suction part

Claims (8)

[Claims] 1. A method for transferring a substrate to and from the substrate stage of an exposure apparatus that transfers a pattern of a mask onto a substrate that is positioned or moved by the substrate stage. A loading arm for raising and lowering the substrate by detecting the position of the substrate on the basis of an outer shape or a predetermined alignment mark while holding the substrate on the loading arm; In a state where the substrate stage is moved to a position for receiving the substrate based on the above, after the loading arm is lowered and the substrate is placed on the substrate stage, the loading arm is removed from the substrate. Characteristic board transfer method. 2. When detecting the position of the substrate held by the carry-in arm, at least three positions including a notch formed in an outer peripheral portion of the substrate are detected. 2. The method according to claim 1, wherein a rotation angle of the substrate is calculated based on a position, and the rotation angle of the substrate is corrected by rotating the loading arm based on the calculation result. 3. A method for transferring a substrate to and from a substrate stage of an exposure apparatus that transfers a pattern of a mask onto a substrate that is positioned or moved by a substrate stage. A loading arm for lowering the substrate, and an unloading arm for holding the substrate and lifting the substrate, wherein a position of the substrate is detected while the substrate is held by the loading arm. Moving the substrate stage to a position for receiving the substrate based on the detection result, lowering the loading arm and placing the substrate on the substrate stage, and then moving the loading arm A second step of removing from the substrate, detecting a position of a predetermined alignment mark on the substrate, and a plurality of exposure regions on the substrate based on the detection result. A third step of obtaining a positional relationship with the pattern of the mask, and a fourth step of sequentially transferring the pattern of the mask to a plurality of exposure regions on the substrate while performing alignment based on the obtained positional relationship. And a fifth step of moving the substrate stage to a position at which the substrate is unloaded, lifting the substrate with the unloading arm, and unloading the substrate from the exposure apparatus. 4. An exposure apparatus, comprising: a substrate stage for positioning or moving a substrate; and an exposure unit for transferring a mask pattern onto the substrate on the substrate stage. A loading arm for raising and lowering the substrate, an image processing system for detecting a position of the substrate held by the loading arm, and the substrate stage based on a detection result of the image processing system.
And a control system for controlling the operation of the loading arm, wherein the control system moves the substrate stage to a position for receiving the substrate based on the position of the substrate detected by the image processing system. An exposure apparatus for lowering the loading arm and placing the substrate on the substrate stage. 5. An image processing system, comprising: a movable illumination device that illuminates the substrate from the bottom side so as to be able to be taken in and out of the bottom surface of the loading arm; An imaging device for imaging;
The exposure apparatus according to claim 4, comprising: 6. The exposure apparatus according to claim 5, wherein when the substrate is large, the movable illuminating device moves following a detection position on the substrate when detecting the position of the substrate. . 7. The carrying arm includes a holding member that holds the substrate from above and holds the substrate, and a groove for accommodating a tip portion of the holding member on a mounting surface of the substrate stage on which the substrate is mounted. 7. The exposure apparatus according to claim 4, wherein the exposure apparatus is formed. 8. An unloading arm for unloading the substrate on the substrate stage, wherein the unloading arm further comprises a holding member for holding the substrate from above and holding the substrate. 8. The exposure apparatus according to claim 7, wherein a tip portion of the exposure device is also housed in a groove on the substrate stage.