JPH05166701A - Projection photolithographing system - Google Patents

Abstract

PURPOSE:To prevent the sliding of a plate on a stage holder at the time of positioning the plate on the holder. CONSTITUTION:After a plate P is placed on a stage holder 3, a plurality of length measuring instruments 10A, 10B, and 10C which are lightly made to abut on the edge of the plate P are provided and the positional deviation of the plate from a stage moving coordinate system in the X-, Y-, and theta-directions are found from the measurements obtained by means of the instruments 10A, 10B, and 10C. Then the deviation in the theta-direction is corrected by rotating the holder 3 and deviation in the X- and Y-directions is corrected on stage 3 feeding coordinates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for projecting and exposing a circuit pattern or the like onto a square or rectangular photosensitive substrate.

[0002]

2. Description of the Related Art In this type of exposure apparatus, an original image such as a circuit pattern formed on a mask (or reticle) is projected and exposed on a photosensitive substrate at a predetermined magnification by a projection optical system. In many cases, the projected image of the original image pattern is exposed at a predetermined position on the photosensitive substrate. Therefore, the relative positional relationship between the exposed region on the photosensitive substrate and the pattern projection image is defined in advance by some method. FIG. 1 is a diagram schematically showing the configuration of a conventional projection exposure apparatus (stepper). In FIG. 1, an exposure light source 1
After being collected by the elliptic mirror 2, the illumination light from the illuminator irradiates the reticle R with a uniform illuminance distribution via a well-known illumination optical system (not shown). The transmitted light in the pattern area formed on the reticle R is image-projected on a rectangular photosensitive substrate (hereinafter referred to as a plate) P via a projection optical system PL. A resist layer is applied to the surface of the plate P, and this surface is applied to the projection optical system P.
It is placed on the holder 3 so as to coincide with the image plane of L. The holder 3 fixes the mounted plate P by vacuum suction, and is provided to be finely rotatable on the X stage 4. The X stage 4 is provided so as to move on the Y stage 5 in the X direction, and the Y stage 5 is provided so as to move on the base in the Y direction.

The plate P is held by the transfer arm 6 of the autoloader 7 and transferred onto the holder 3. Since this autoloader 7 is provided at a fixed position in the apparatus, when the plate P is loaded by the arm 6, the X stage 4 and the Y stage 5 are moved to be positioned at a predetermined loading position (delivery position). There is a need to. Although not shown in FIG. 1,
In order to measure the coordinate value of the plate P in the XY coordinate system defined by the movement of the X stage 4 and the Y stage 5, for the X direction so as to satisfy the Abbe measurement condition with respect to the optical axis of the projection optical system PL. And a laser interferometer for the Y direction. The laser beam for length measurement from this laser interferometer is projected on the respective reflecting surfaces of the movable mirrors which are fixed at right angles on the two sides of the X stage 4, and the distances to those movable mirrors are measured as the length measurement values. To be done. Then, the length measurement value represents the coordinate value of the plate P by the movement of the X stage 4 and the Y stage 5, and the coordinate value is monitored to monitor the X stage 4,
By positioning the Y stage 5, the pattern image IM (FIG. 1) of the reticle R can be projected and exposed at a predetermined position on the plate P.

However, since the reticle R is mounted on a reticle holder (not shown) in a replaceable manner, the pattern center point of the reticle R is always precise and the optical axis AX of the projection optical system PL.
Is not always aligned to match. Therefore, if only the coordinate values of the X stage 4 and the Y stage 5 are monitored and the plate P is positioned,
There is no guarantee that the pattern image IM is always exposed at a specific position on the plate P. Therefore, as one simple method, the alignment mark provided on the pattern area of the reticle R and the alignment mark provided on the plate P are detected via the projection optical system PL, and the positional deviation amount of both marks becomes zero. The coordinate values of the X stage 3 and the Y stage 5 (hereinafter collectively referred to as a plate stage) are stored as a reference, and the positioning target position of the plate stage is calculated according to the reference coordinate value, There is a method of performing a positioning operation.

In addition to the above methods, various methods are conceivable,
Although they have been put to practical use, those methods themselves are not directly related to the invention of the present application, and a further description thereof will be omitted here. However, no matter what method is used, the reticle R
The detection of the mark and the detection of the mark on the plate P are indispensable operations. However, in detecting the mark on the plate P, it is necessary to pre-align the plate P mounted on the holder 3 within an allowable range. That is, if the pre-alignment accuracy of the plate P on the holder 3 is poor, it becomes difficult to capture the mark within the detection range of the sensor (microscope or the like) that detects the mark on the plate P, and the mark search operation (plate stage X of
(Movement in the Y direction) takes a long time. Further, in the worst case, the mark cannot be captured, and an error of poor pre-alignment occurs.

Therefore, in order to improve the pre-alignment accuracy of the plate P on the holder 3, positioning reference pins (rollers) 3a, 3b, 3c are planted at three positions on the holder 3 as shown in FIG. Then, it is considered that the plate P is vacuum-sucked on the holder 3 in a state where two orthogonal sides of the plate P are pressed against the reference pin. FIG. 2 shows the arrangement of the reference pins 3a, 3b, 3c on the holder 3 and the arrangement of the pressing members 3d, 3e of the plate P.
The side Ex of the end surface of the plate P extending in the X direction is defined in the Y direction by abutting the reference pin 3a by the pressing operation of the pressing member 3d in the Y direction, and the side Ey of the plate P extending in the Y direction is pressed. By the pressing operation of 3e in the X direction, the X direction and the rotation direction (hereinafter referred to as θ direction) are defined by contacting the two reference pins 3b and 3c. The plate P is always set at the same position on the holder 3 by the mechanical pre-alignment mechanism on the holder.
The search operation for detecting the upper mark can be performed in an extremely small range. While the plate P is being pressed by the pressing members 3d and 3e, air flow is performed from the holder 3 so that the contact friction between the mounting surface of the holder 3 and the plate P is minimized. 3e
When the plate P has been pushed down in the X and Y directions, the holder 3 is switched to vacuum suction. The pressing members 3d and 3e are retracted when the vacuum suction is completed.

[0007]

However, among the plates P of this kind, the plate P used in the process of manufacturing a liquid crystal display device or the like has a size of 40 cm square or more, and moreover, the flatness due to the influence of the process. It can be extremely bad like a potato chip. Positioning the plate P whose flatness has deteriorated in this way by the pre-alignment mechanism of FIG. 2 causes the following problems. First, a part of the back surface of the plate P, which should have been floated by the airflow, remains partially in contact with the holder 3. Secondly, the pressing members 3d and 3e must be pressed by a force against the increase in frictional force due to the partial contact. Third, the standard P
Since the plate P is vacuum-sucked on the holder 3 while being held by the pressing members 3d, 3e and 3a, 3b, 3c, the peripheral part moves up and down due to the flattening of the plate P as the suction progresses. Pins 3a, 3b, 3c, pressing members 3d, 3
That is, unnecessary stress is applied to the peripheral portion in contact with e.

[0008] These problems have been a factor in causing pre-alignment defects and the like, which are often related to each other.
Further, since the plate P is slid in a state where there is a partial contact such as the first point, static electricity is generated between the plate P and the plate P when the plate P is taken out of the holder or placed. There is a possibility that the circuit pattern or the like formed on the P may be damaged (electrostatic destruction or the like). Further, due to the above-mentioned first and second problems, the pressing force of the pressing members 3d, 3e increases, thereby damaging the end surfaces of the plate P that abut the pressing members 3d, 3e or the reference pins 3a, 3b, 3c. There was a possibility of damage or dust generation. Even when vacuum suction is performed as in the third point, since the plate P is held by a considerably large force, there is a possibility that suction failure may occur in some cases.

In view of the above, it is an object of the present invention to solve these problems and provide a projection exposure apparatus which does not require positioning by mechanical pressing during prealignment.

[0010]

SUMMARY OF THE INVENTION In the present invention, a structure for pressing a photosensitive substrate against a reference pin or the like on a holder of a movable stage is abolished, and instead, a means for detecting a side defining an outline reference of the photosensitive substrate. , Means for associating that side with a reference coordinate system for managing the moving position of the movable stage, and the positional deviation (X,
The rotation control of the holder and the position control of the X and Y stages are performed so that the Y and θ directions are corrected.

More specifically, the projection optical system (PL) for projecting the original image pattern formed on the reticle (R) onto a predetermined image plane, and the plate (P) on a plane parallel to the image plane. In a device provided with two coordinate axis directions (X direction and Y direction) orthogonal to each other of the reference coordinate systems X and Y defined within, and movable stage means (3, 4, 5) for moving in the θ direction. , The plate (P) is placed on the holder (3) of the movable stage at the transfer position (loading position) in the reference coordinate systems X and Y, and then the plate (P)
The outer side of the plate (P) to detect the reference coordinate system X,
Deviation detecting means (10A, 10B, 10C) for measuring each positional deviation in the Y-axis direction, the Y-axis direction, and the θ direction in Y.
A rotation driving means (30, Mθ) for rotating the plate (P) so as to correct the θ direction of the deviation, and the amount of deviation of the polarized light in the X axis direction and the Y axis direction. Control for controlling the positioning coordinates of the X stage (4, 5) during the projection exposure of the original image pattern so as to deviate from the intended position (the position determined by design or the position specified by the result of global alignment of the plate). Means (26, 28) are provided.

[0012]

In the present invention, the mechanism for pressing the plate from the outside is eliminated, the plate conveyed on the stage is adsorbed on the holder, and then the outer position of the plate is measured. The deviation amount of the plate in the X and Y directions with respect to the coordinate system) and the rotation error amount are obtained,
An offset is added to the target value determined in the design of the stepping position so that the deviation amounts are corrected during the projection exposure. The rotation error amount of the plate may be corrected by rotating the reticle side. In this way, the plate conveyed onto the holder (movable stage) does not have its peripheral edge constrained by the reference pins or the like, so that flattening is reliably performed by suction. Moreover, since the plate itself does not slide on the holder, the generation of static electricity and dust are prevented,
There is no damage to the plate end surface.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 is a functional block diagram showing a main part of an apparatus configuration according to an embodiment of the present invention. In this embodiment, the length measuring devices 10A and 1A with movable contactors are provided at three locations around the holder 3.
0B and 10C are attached. In FIG. 3, an imaginary line indicates the plate PI ideally placed on the holder 3, and the length measuring device 10A moves in the Y direction and comes into light contact with the center of the edge Ex of the plate P extending in the X direction. The length-measuring devices 10B and 10C have contactors that move in the X-direction and make light contact with each other at two points of the edge Ey extending in the Y-direction of the plate P. The drive of these contactors is performed by the measurement control unit 20, and after the measurement by the contact of the contactors,
Each contactor is driven to a predetermined retracted position. Further, the length measuring signals DY, DX, Dθ of the respective length measuring devices 10A, 10B, 10C
Is input to the calculation unit 22, and here each measured value is stored in the storage unit 2.
By calculating how much the deviation from the reference value stored in advance in 4 is calculated, the two-dimensional displacement amount (ΔX, ΔY, Δθ) of the actual plate P with respect to the plate PI at the ideal position is calculated. To calculate. Here the length measuring device 10
The reference values in the storage unit 24 that are given in advance to A, 10B, and 10C are Y _r , X _r1 , and X _r2 , respectively, and the respective measured values DY and D actually measured for the plate P are set.
When X and Dθ are Y ₁ , X ₁ and X ₂ , the shift amount Δθ in the rotation direction is represented by the following equation, where the distance (span) in the Y direction between the abutments of the two length measuring devices 10B and 10C is L. ..

Δθ≈arcsin ((X _r1 −X _r2 −X ₁ + X ₂ ) / L) (1) Further, the parallel displacement amounts ΔX and ΔY in the X and Y directions are small in rotational displacement amount Δθ. In the range, it is expressed by the following equation. ΔY≈Y _r −Y ₁ (2) ΔX≈ ((X _r1 −X ₁ ) + (X _r2 −X ₂ )) / 2 + N (3) Here, N in the formula (3) is the length measuring device 10B. 10C changes depending on the difference (Ycc-Ycp) in the Y direction between the midpoint Ycc of the span L of each contactor and the midpoint Ycp of the edge Ey of the plate pin, and when the difference is almost zero, N is 0, and FIG.
In the arrangement of, N is represented by the following equation.

N.apprxeq..DELTA..theta..multidot. (Ycc-Ycp) (4) Deviation amount (.DELTA.X, .DELTA.Y, .DELTA.) Calculated as described above.
θ) is sent to the main control system 26, and the main control system 26 sends the rotation deviation amount Δθ to the stage control system 30.
The motor Mθ for minute rotation of the holder 3 is controlled. As a result, the holder 3 is rotated in a direction to correct the rotation deviation amount Δθ. On the other hand, regarding the displacement amounts ΔX and ΔY in the X and Y directions, the stage control system 30 is modified by correcting the target positions of the X and Y stages 4 and 5 designated at the time of exposure on the plate P by the displacement amounts ΔX and ΔY. Corrected by sending to. Originally, the target positions of the X and Y stages 4 and 5 are coordinate values for aligning the shot area on the plate P with the projected image of the reticle pattern, and they are processed in advance when they are mechanically determined. Sometimes it is determined by the global alignment of the plates. In any case, those target positions are stored in the memory of the designation unit 28. When the drive motors MX and MY for the X and Y stages 4 and 5 are controlled by the stage control system 30,
The motors MX and MY may be stopped when the current position of the XY stage is monitored by the X and Y interferometers and when it coincides with the corrected target position.

FIG. 4 shows three length measuring devices 10A, 10B and 1
An example of a specific structure of 0C is shown, and here, the length measuring device 10B is shown as a representative. The movable contactor 40 of the length measuring device 10B is
A roller is rotatably supported at one end of a U-shaped swing member 100 that is rotatably supported in the XY plane about the shaft 101. The piston of the air cylinder 103 is engaged with the other end of the swing member 100, and the potentiometer 104 is engaged between the shaft 101 of the swing member 100 and the engagement point of the piston of the air cylinder 103. Has been done. With such a structure, when the piston of the air cylinder 103 moves in the Y direction, the swing member 100 rotates, and the roller 40 moves in the X direction. The other two length measuring instruments 1
0A and 10C have exactly the same structure, and the weak pressing force of the air cylinder 103 is increased by the lever action of the swinging member 100 to make the contact force of the roller 40 to the plate edge desired.

As described above, in the configuration of FIG.
Since A, 10B, and 10C are fixed on the holder 3, when the plate P is transferred from the arm 6 onto the holder 3, the minute rotation position of the holder 3 is returned to the neutral point (or an arbitrary reference angle position). There is a need. It is the storage unit 2
This is because the reference values X _r1 , X _r2 , and Y _r stored in 4 are set so as to have a unique correspondence relationship with respect to the moving reference coordinate system of the XY stage (defined by the X and Y interferometers). That is, the plate P on the holder 3 must always be recognized as a rotational position shift on the moving reference coordinate system, but when measuring the edge with each of the length measuring devices 10A, 10B, and 10C, the reference value X _r1 , If X _r2 and Y _r are rotated by an unknown amount with respect to the reference coordinate system, the unknown amount itself becomes a residual rotation error of the plate P on the reference coordinate system. Therefore, when measuring with the length measuring devices 10A, 10B, and 10C,
It is necessary to return the holder 3 to the rotation angle position (the neutral point or the reference angle position) when the reference values X _r1 , X _r2 , and Y _r are set. However, if there is an angle sensor or the like that detects the minute rotation amount of the holder 3 with high accuracy, if the rotation amount Δφ from the neutral point of the holder 3 or the reference angle position is obtained during length measurement by the length measuring device, Since the unknown amount mentioned above is known, the rotation deviation amount Δθ obtained by the above equation (1)
It suffices to correctively rotate the holder 4 by the motor Mθ by a value including the residual rotation amount Δφ.

As another way of thinking, three length measuring devices 10
A, 10B, and 10C may be fixed to the X stage 4 side that is the base of the holder 3, and only the contactor may be extended so as to contact the edge of the plate P on the holder. In this case, since the X stage 4 does not rotate in the moving reference coordinate system, the reference points X _r1 , X _r2 and Y _r also do not rotate in the reference coordinate system. Therefore holder 3
Regardless of how the holder 3 rotates when receiving the plate P on the top, the rotation deviation amount Δθ of the plate P is always obtained with the movement reference coordinate system as a reference regardless of the rotation.

In the above embodiment, the length measuring devices 10A and 10A are used.
Each of B and 10C stores a predetermined reference value in the storage unit 24.
However, since there are several methods for determining the reference value, the method will be described below. First, when the rotation angle of the holder 3 is detected by a simple potentiometer or the like, the angle value is treated as an output voltage value obtained from the potentiometer. Therefore, at the time of manufacturing the device or at the time of maintenance, the angle value of the holder 3 is set to the neutral state and the test plate P is automatically conveyed onto the holder 3 and then the test plate P is displaced on the holder 3 so that the positional deviation is minimized. Adjust the position manually.
After that, the test plate P is vacuum-sucked on the holder 3, and then the search mode of the plate global alignment is executed. At this time, it is confirmed whether or not the alignment mark formed on the test plate P is within the range easily captured by the alignment sensor of the stepper. In particular, regarding the rotation deviation of the test plate P, the positions of the alignment marks formed at two positions on the plate P are measured using an alignment sensor and an X, Y interferometer, and the X direction or Y direction is measured.
You may make it calculate | require from the positional difference of a direction. As a result of the above confirmation, when the rotational displacement and the positional displacement in the X and Y directions are not sufficiently small, the vacuum suction of the holder 3 is released,
The position of the test plate P is manually adjusted again.
When the test plate P is driven to the almost ideal position (PI) by repeating these operations several times, the length measuring devices 10A, 10B,
Edges Ex, Ey of the test plate of each contactor of 10C
The measured values DY, DX, and Dθ at that time may be stored in the storage unit 24 as reference values Y _r , X _r1 , and X _r2 , respectively.

When the length measuring devices 10A, 10B and 10C are constituted by simple potentiometers, reference values Y _r ,
Since both X _r1 and X _r2 are obtained as voltage values, these voltage values are converted into digital values and stored in the storage unit 24. The second method uses three length measuring devices 10A and 10A.
A reference mark for locating a position that can be observed by an alignment sensor is engraved on a part of each of the movable contactors B and 10C, and the coordinate position of the XY stage when the reference mark is detected by the alignment sensor is measured. Thus, the reference values Y _r , X _r1 , and X _r2 are determined on the moving reference coordinate system. FIG. 5 is an enlarged view of the vicinity of the length measuring device 10B on the holder 3. In the length measuring device 10B, a roller 40 as an abutting member movable in the X direction is arranged so as to be able to abut on the edge Ey of the plate P. ing. Then, a reference mark Mr is formed on a part of the movable piece that pivotally supports the roller 40 at a height position substantially matching the surface of the plate P. The reference mark Mr is, for example, a linear pattern extending in the Y direction (parallel to the edge Ey), and is fixed at a position at a constant distance in the X direction from the outer peripheral surface of the roller 40 (contact surface with the edge Ey). Has been done.
The reference marks are provided in the other length measuring devices 10A and 10C with the same structure.

As an alignment sensor for observing the reference marks Mr, an off sensor having a television camera is used.
An axis type plate microscope or the like is suitable. FIG. 6 shows an example of an off-axis alignment system, in which the optical axis AX of the projection lens PL passes from the point C ₀ to X along the image plane.
An objective lens 50 arranged so that the optical axis AXa passes through a point C ₁ in the image plane that is separated by a certain distance (baseline amount) in the direction, and a beam splitter that splits the illumination light and the light reflected from the plate. 51, imaging lens 52, and mirror 5
3, an index plate 54, an image forming lens 55 for magnifying and photographing a pattern in a window formed in the index plate 54 and an image of a mark formed on the plate in the window, and a CCD 56 as a television camera. It has and. The CCD 56 is originally a window (or pattern) of the index plate 54 for the mark image on the plate.
It is used to obtain the amount of positional deviation with respect to, but in the present embodiment, it is used to observe the image of the reference mark Mr shown in FIG. The baseline amount between points C ₀ and C ₁ is preset as a mechanically fixed value.

Then, an arbitrary plate P is placed on the holder 3.
After adsorbing and extending the roller of the length measuring machine, XY stage
4 and 5 are moved and the reference mark attached to the length measuring device 10B
The portion where the Mr should exist as an ideal position is the objective lens 5
Positioned so that it is located within the field of view of 0, and its coordinates (X
_p1, Y_p1) Is read by an X, Y interferometer and stored. this
At the stage, the reference mark is not always located at the center of the field of view of the objective lens 50.
Ku does not always come. Next, the field of view of the objective lens 50
At the center, that is, at the center of the window of the index plate 54, the reference mark Mr is formed.
Finely move the XY stages 4 and 5 so that is positioned. This
The image of the CCD 56 is reproduced on the TV monitor.
It can be confirmed by living. And the XY stage after the slight movement
Coordinate value (X_p2, Y_p2) Is read and stored by the XY interferometer
To do. Since the length measuring device 10B is for measuring the length in the X direction,
Then, the deviation amount in the X direction (X_p1-X_p2) On the length measuring device 10B
Measured value DX and its reference value X_r1Equal to the difference between
It will be good. Therefore, the value measured by the length measuring device 10B
Deviation from DX (X_p1-X _p2) Corresponding to voltage correction
Value is the reference value X_r1Can be calculated as Also a length measuring machine
For 10C as well, the reference mark is similarly used for the objective lens.
The XY stage is moved so as to detect at 50. this
Since the length measuring device 10C is also for measuring in the X direction,
The X coordinate value of the tage is X_p1Finely move with reference to
X coordinate value when the reference mark of 10C is detected is X_p3When
To do. Therefore, deviation from the measured value Dθ by the length measuring device 10C
Quantity (X_p1-X_p3) Is based on the value corrected for the voltage corresponding to
Value X_r2Can be calculated as

The above sequence can be similarly executed when the alignment mark on the plate P suction-held on the holder is detected by the off-axis alignment system shown in FIG. In the third method, the result of global alignment or the like for the first plate P out of the plurality of plates P to be exposed is calculated by the length measuring device 10A during processing of the second and subsequent plates P, 10B, 10C
It is used to correct the standard value of. Here, the reference values set at the time of processing the first plate P are XR1 and XR.
2 and YR, and the positional displacement amounts measured by the measuring instrument in accordance with them are ΔXf, ΔYf, and Δθf. After that, the global alignment and the fine alignment are executed in a state in which this positional deviation amount is corrected. At that time, the residual deviation amounts ΔXe, ΔYe, Δθ of the plate P are further increased.
e is obtained. The residual displacement amounts ΔXe, ΔYe, and Δθe are preferably as small as possible. When the residual displacement amounts are above a certain range, the corresponding reference value is corrected. Ie Δ
When Ye is large, the reference value YR is corrected by an amount corresponding to ΔYe, and when ΔXe is large, the reference values XR1 and XR are corrected.
Both 2 may be corrected by an amount corresponding to ΔXe. Further, when Δθe is large, it may be corrected so that there is a difference in amount corresponding to Δθe between the reference values XR1 and XR2.

With the above arrangement, the measurement accuracy of the length measuring devices 10A, 10B, 10C for the second and subsequent plates P is enhanced, and the global alignment or fine alignment processing is smoothly executed. However, this method is possible when the reproducibility of the pre-alignment accuracy of each of the second and subsequent plates P that are automatically conveyed onto the holder 3 is good, and there are variations in the pre-alignment accuracy for each plate P. It's difficult when big
It is preferable to set the reference values X _r1 , X _r2 , and Y _r by the above method or the second method.

As described above, in each embodiment of the present invention, the roller 40
Measuring instruments 10A, 10B, 10C with movable contactors
Although the positions of the edges Ex and Ey of the plate P are measured by the above method, the edges can be measured without contact. As an example, it is conceivable to use the off-axis alignment type television camera (CCD 56) shown in FIG. In this case, the edge E of the plate P is captured within the imaging range of the CCD 56, that is, within the window of the index plate 54.
Position x, Ey in total at 3 places as shown in Fig.
Based on the image signal of CD56, the edge Ex or Ey
The relative displacement between the image and the window is detected, and the coordinate values of the XY stages 4 and 5 at that time are read from the interferometer. Note that the edge Ey is measured at two locations separated by a certain amount in the Y direction. Then, based on the above measurement results, the amount of displacement (ΔX, ΔY, Δθ) of the plate P with respect to the movement reference coordinate system is calculated.

At this time, the edge Ey of the plate P imaged by the CCD 56 is observed on the television monitor as shown in FIG. 8A, for example. FIG. 8A shows an image of an edge Ey deviated by ΔX _{1 in the} X direction with respect to the center line CL parallel to the Y axis in the window of the index plate 54, and is orthogonal to the center line CL of FIG. 8B. The waveform of the video signal VS obtained by the scanning line is shown. Normally, the plate P has a thickness of about 1 mm to several mm, and therefore, in the alignment system having the epi-illumination system as shown in FIG. 6, a shadow is formed at the edge Ey and observed. Therefore, a bottom portion is generated in the waveform of the video signal VS, and the shift amount ΔX ₁ can be obtained by detecting the position. The center line CL is the midpoint of the left and right edges of the window 54.

As described above, one-dimensional (or two-dimensional) image sensors are embedded in at least three places in the holder 3 in addition to the non-contact type length measuring system using the television camera, and the edges Ex and Ey are used as shadows. You may make it detect. At this time, the pixel arrangement direction of the one-dimensional image sensor is set to a direction intersecting with the edges Ex and Ey. As a measurement procedure, when the plate P that has been automatically conveyed is adsorbed on the holder 3, each one-dimensional image sensor The illumination light is projected onto the edge portion corresponding to the position. This illumination light can be from the off-axis alignment system of FIG. This is because the illumination light for observation of the alignment system is set in a wavelength range in which the resist layer on the plate P has almost no sensitivity. Then, the pixel positions where the shadow of the edge appears on the three image sensors are respectively detected, and the deviation amount from the reference pixel on each image sensor may be obtained in advance.

[0028]

INDUSTRIAL APPLICABILITY As described above, the present invention is effective when used for aligning plates of a liquid crystal device for performing pattern exposure on a large glass plate or the like, and for aligning plates of an exposure apparatus. Large glass plates are prone to distortion due to heat treatment in the process, and because the plate is heavy and the friction with the holder is large, it is very difficult to press it against the reference pin on the device side and stick it to the holder. is there. However, according to the present invention, since the plate on the holder does not move after being placed to press against the reference pin or the like, dust is prevented, unnecessary stress generated in the plate is prevented, It is possible to obtain an effect such as prevention of adsorption failure on the holder, and it is possible to increase the operation rate of the exposure apparatus.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of a square plate exposure apparatus that has been used conventionally.

FIG. 2 is a plan view showing a conventional configuration for positioning a substrate on a plate holder.

FIG. 3 is a functional block diagram showing a configuration of a positioning system according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing an example of the structure of the length measuring device in FIG.

FIG. 5 is a perspective view showing a configuration of a length measuring device used in a positioning method according to a second embodiment.

FIG. 6 is a perspective view showing the arrangement and configuration of a projection lens and an off-axis alignment system.

FIG. 7 is a diagram showing a procedure of a third embodiment in which an off-axis alignment system is used instead of the length measuring device.

FIG. 8 is a diagram showing a screen on a television monitor and a video signal waveform.

[Explanation of symbols for main parts]

 R Reticle PL Projection lens P Plate 3 Holder 4 X stage 5 Y stage 10A, 10B, 10C Length measuring device 22 Calculation unit 24 Reference value storage unit 40 Roller (operating contactor)

Claims (2)

[Claims] 1. A means for holding a mask on which an original image pattern to be exposed is formed, a projection optical system for projecting the original image pattern onto a predetermined image forming surface, and a rectangular photosensitive substrate substantially parallel to the image forming surface. And movable stage means for holding the substrate and moving the substrate in two coordinate axis directions orthogonal to each other in a reference coordinate system defined in a plane parallel to the image forming plane and in a rotation direction in the reference coordinate system. And a device for projecting and exposing an image of the original image pattern at a predetermined position on the photosensitive substrate, wherein the photosensitive substrate is placed on the movable stage means at a transfer position in the reference coordinate system, Deviation detecting means for detecting a positional deviation between the two coordinate axis directions of the photosensitive substrate in the reference coordinate system and a rotational direction by detecting an outer side of the photosensitive substrate; and the detected positional deviation in the rotational direction. Rotation driving means for rotating the photosensitive substrate on the movable stage means so as to be corrected; and, in accordance with the detected amount of each positional deviation in the two coordinate axis directions,
A projection exposure apparatus, comprising: a control unit that controls the positioning coordinates of the movable stage unit when the original image pattern is projected and exposed so as to be displaced from a desired position. 2. The photosensitive substrate has a rectangular shape having two sides that are orthogonal to each other, and the deviation detecting means has the two orthogonal sides.
Three movers capable of abutting at two locations on one side and one location on the other one of the sides, three length measuring devices for measuring the amount of movement of each of the movers, and The apparatus according to claim 1, further comprising: a calculation unit that calculates a positional deviation between two coordinate axis directions and a rotation direction in the reference coordinate system based on length measurement values obtained by three length measuring devices.