JP3254704B2 - Exposure apparatus and exposure method - Google Patents

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 on 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, a projected image of an original pattern is exposed at a predetermined position on a photosensitive substrate. For this reason, the relative positional relationship between the exposed area on the photosensitive substrate and the pattern projection image is determined in advance by some method. FIG. 1 is a diagram schematically showing a configuration of a conventional projection exposure apparatus (stepper). In FIG. 1, an exposure light source 1 is shown.
After being converged by the elliptical mirror 2, the reticle R is irradiated with a uniform illuminance distribution on the reticle R via a known illumination optical system (not shown). The transmitted light of the pattern area formed on the reticle R is image-formed and 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
It is placed on the holder 3 so as to coincide with the image plane of L. The holder 3 fixes the placed plate P by vacuum suction and is provided on the X stage 4 so as to be able to rotate slightly. The X stage 4 is provided to move on the Y stage 5 in the X direction, and the Y stage 5 is provided to move on the base in the Y direction.

The plate P is held by a transfer arm 6 of an autoloader 7 and transferred to a holder 3. Since the 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 movements of the X stage 4 and the Y stage 5, the X direction is adjusted 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 beams for length measurement from this laser interferometer are projected on the respective reflecting surfaces of moving mirrors fixed at right angles on two sides of the X stage 4, and the distances to these moving mirrors are measured as length measurement values. Is done. Then, the measured value represents the coordinate value of the plate P due to 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, a 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 exchangeably mounted on a reticle holder (not shown), the center of the pattern of the reticle R is always precisely aligned with the optical axis AX of the projection optical system PL.
Are not necessarily aligned to match. Therefore, only by monitoring the coordinate values of the X stage 4 and the Y stage 5 and positioning the plate P,
There is no guarantee that the pattern image IM is always positioned at a specific position on the plate P and the pattern image IM is exposed. Therefore, as one simple technique, an alignment mark provided on the pattern area of the reticle R and an alignment mark provided on the plate P are detected via the projection optical system PL, and the positional deviation between the two marks is reduced to 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 a positioning target position of the plate stage is calculated according to the reference coordinate value. There is a method of performing a positioning operation.

[0005] In addition to the above methods, various methods are conceivable.
Although they have been put into practical use, their methods themselves are not directly related to the present invention, and thus further description is omitted here. However, whatever the method, reticle R
The detection of the mark and the detection of the mark on the plate P are essential operations. However, in detecting a mark on the plate P, it is necessary to pre-align the plate P placed 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 a sensor (a microscope or the like) for detecting the mark on the plate P, and the mark search operation (the plate stage X,
(Movement in the Y direction) takes a long time. In the worst case, the mark cannot be captured, and an error of poor pre-alignment occurs.

Therefore, in order to enhance the pre-alignment accuracy of the plate P on the holder 3, positioning reference pins (rollers) 3a, 3b, 3c are planted at three places on the holder 3, as shown in FIG. Then, it is considered that the plate P is vacuum-adsorbed onto the holder 3 in a state where two orthogonal sides of the plate P are pressed against the reference pins. FIG. 2 shows the arrangement of the reference pins 3a, 3b and 3c on the holder 3 and the arrangement of the pressing members 3d and 3e of the plate P.
The side Ex extending in the X direction of the end face of the plate P is defined in the Y direction by contacting 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 a pressing member. By the pressing operation in the X direction of 3e, the X direction and the rotation direction (hereinafter referred to as the θ direction) are defined by contacting the two reference pins 3b and 3c. Since the plate P is always set at the same position on the holder 3 by the mechanical pre-alignment mechanism on the holder, the plate P
The search operation for detecting the upper mark can also be performed in an extremely small range. In addition, while the plate P is 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, and the pressing member 3d , 3e
Pushes the plate P in the X and Y directions, the holder 3 is switched to vacuum suction. When the vacuum suction is completed, the pressing members 3d and 3e are retracted.

[0007]

However, of this kind of plate P, the plate P used in the process of manufacturing a liquid crystal display element or the like has a size of 40 cm square or more, and the flatness is affected by the process. It can be extremely bad, like potato chips. When the plate P having the deteriorated flatness is positioned by the pre-alignment mechanism shown in FIG. 2, the following problem occurs. First, a part of the back surface of the plate P, which should have floated by the air flow, remains partially in contact with the holder 3. Second, the pressing members 3d and 3e must be pressed with a force against the increase in frictional force due to the partial contact. Third, the criteria P
Since the plate P is vacuum-sucked on the holder 3 while being held between the pressing members 3d, 3e and the pressing members 3d, 3c, the peripheral portion moves up and down due to the flattening of the plate P as the suction proceeds. Pins 3a, 3b, 3c, pressing members 3d, 3
Unnecessary stress is applied to the peripheral portion in contact with e.

[0008] These problems are related to each other and often cause a pre-alignment failure.
In addition, since the plate P is slid in a state where there is partial contact as in the first point, static electricity is generated between the plate P and the plate P when the plate P is removed from the holder or placed. There is a possibility that a circuit pattern or the like formed on P may be damaged (such as electrostatic breakdown). Further, the pressing force of the pressing members 3d, 3e is increased due to the first and second problems, thereby damaging the end surfaces of the plate P contacting the pressing members 3d, 3e or the reference pins 3a, 3b, 3c. Possible damage or dusting. Also, as in the third point, when vacuum suction is performed, since the plate P is held with a considerably large force, there is a possibility that poor suction may occur in some cases.

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

[0010]

According to 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 side for detecting a side defining an outer shape standard of the photosensitive substrate is eliminated. Means for associating the side with a reference coordinate system for managing the moving position of the movable stage, and the positional deviation (X,
(Y, θ directions) are corrected so that the rotation control of the holder and the position control of the X and Y stages are performed.

More specifically, according to the first aspect of the present invention, means for holding a mask (reticle R) on which an original image pattern to be exposed is formed, and a projection for projecting the original image pattern onto a predetermined image plane An optical system (PL) and a rectangular photosensitive substrate (P) having two sides orthogonal to each other and substantially parallel to the image plane are held, and a reference defined in a plane parallel to the image plane. Movable for moving the photosensitive substrate (P) in two coordinate axis directions (X-axis direction and Y-axis direction) orthogonal to each other in the coordinate systems X and Y, and in a rotation direction (θ direction) in the reference coordinate systems X and Y. Stage means (3, 4, 5)
When, after the photosensitive substrate (P) is placed on a movable stage means (holder 3) in the reference coordinate system X, delivery position in Y (loading position), the movable element to the outer sides of the photosensitive substrate (P) the movable piece causes the abutment to detect the position of the outer side on the basis of the amount of movement until abutment, the reference coordinate system X, orthogonal to each other two coordinate axes in the Y (X-axis direction and the Y-axis direction) The photosensitive substrate is detected by detecting position information on the outer side at two points for one coordinate axis (X-axis) and detecting the position information on the outer side at one point for the other coordinate axis (Y-axis). (P) Two coordinate axis directions in the reference coordinate systems X and Y (X-axis direction and Y-axis direction)
Deviation detecting means (10A, 10B, 10C) for detecting a positional deviation between the axial direction) and the rotational direction (θ direction), and the positional deviation in the rotational direction (θ direction) detected by the deviation detecting means is corrected. Drive means (30, Mθ) for rotating the photosensitive substrate (P) on the movable stage means (3, 4, 5) as described above
And a movable stage for projecting and exposing the original image pattern in accordance with the amount of each positional deviation in two coordinate axis directions (X-axis direction and Y-axis direction) detected by deviation detecting means (10A, 10B, 10C). An exposure apparatus provided with control means (26, 28) for controlling positioning coordinates for moving the means (4, 5) so as to be shifted from an expected position. Further, in the invention according to claim 2, in the exposure apparatus according to claim 1, the deviation detecting means includes one of the two orthogonal sides.
The mover is provided at each of two places on one side and one place on another side.
And capable of abutting against the three mover as (40), the three measuring device for measuring the amount of movement of the three mover (40) (10
A, 10B, 10C) and two coordinate axis directions (X-axis direction and Y-axis direction) and a rotation direction (θ direction) in the reference coordinate systems X and Y based on the measured values obtained by these three length measuring devices. And a calculation means (22) for calculating the position deviation. In the invention according to claim 3, the substrate (P) is placed, and the movable stage means (3,
4, 5) and position information defining the outer shape of the substrate (P) placed on the movable stage means (3, 4, 5) are defined by two coordinate axis directions (X, Y) orthogonal to each other in the reference coordinate systems X, Y. Board position detecting means (10A, 10B, 10C) for detecting one coordinate axis (X axis) of two axes (X axis direction and Y axis direction) and detecting it at one point for the other coordinate axis (Y axis).
Detecting means for detecting the amount of displacement of the substrate (P) with respect to the reference coordinate systems X, Y based on the detection results of the substrate position detecting means (10A, 10B, 10C) and the reference coordinate systems X, Y. (22, 24) and the deviation detecting means (2
Control means (26, 28) for changing at least a part of the values of the reference coordinate system X, Y with respect to the target position based on the detection result of (2, 24). ) And a holder (3) for moving the substrate (P) in the rotation direction in the reference coordinate systems X and Y, and at least one coordinate axis direction in the reference coordinate systems X and Y supporting the holder (3). And a stage (4, 5) for moving the substrate (P) and the holder (3), and a substrate position detecting means (10A, 10B, 10C)
Is provided on at least one of the holder (3) and the stage portions (4, 5). According to a fourth aspect of the present invention, in the exposure apparatus of the third aspect, the deviation detecting means (22, 24) converts the reference value stored in advance and the detection result of the substrate position detecting means (10A, 10B, 10C). On the basis of this, the amount related to the displacement of the substrate (P) with respect to the reference coordinate systems X and Y is calculated. According to a fifth aspect of the present invention, in the exposure apparatus of the fourth aspect, a reference mark (Mr) is formed on the substrate position detecting means (10A, 10B, 10C), and the reference mark (Mr) is formed.
A sensor (56) for detecting the position of the
The reference value is determined based on the detection result of 6). According to a sixth aspect of the present invention, in the exposure apparatus of the third aspect, the substrate position detecting means (56) is configured to detect the position information defining the outer shape of the substrate (P) in a non-contact manner. According to a seventh aspect of the present invention, in the exposure apparatus of the third aspect, the substrate position detecting means includes a plurality of detecting units (10
A, 10B, and 10C), and configured to detect position information that defines the outer shape of the substrate (P) at a plurality of positions on the substrate (P). According to an eighth aspect of the present invention, in the exposure apparatus according to the seventh aspect, the substrate position detecting means detects the position information defining the outer shape of the substrate (P) in a non-contact manner.
6). Claim 9
In the invention described above, means for holding a mask (reticle R) on which an original image pattern to be exposed is formed, a projection optical system (PL) for projecting the original image pattern onto a predetermined imaging plane,
The photosensitive substrate (P) is held substantially parallel to the image forming plane, and two coordinate axis directions (X-axis direction and X-axis direction) of a reference coordinate system X and Y defined in a plane parallel to the image forming plane. In an exposure method using a movable stage means (3, 4, 5) for moving a photosensitive substrate (P) in a rotation direction (θ direction) in a reference coordinate system X, Y). After the substrate (P) is placed on the movable stage means (holder 3) at the transfer position (loading position) in the reference coordinate system X, Y, the movable substrate can be brought into contact with the outer side of the photosensitive substrate (P). Contact the armature and the armature
The outer side is detected based on the amount of movement in the reference coordinate system X,
Two coordinate axis directions orthogonal to each other in Y (X-axis direction and Y-axis direction)
The position information on the outer side is detected at two points with respect to one coordinate axis (X axis) in the (axial direction), and the position information on the outer side is detected at one point with respect to the other coordinate axis (Y axis). Detecting the positional deviation between the two coordinate axis directions (X-axis direction and Y-axis direction) and the rotation direction (θ direction) in the reference coordinate system X, Y of the photosensitive substrate (P); and the rotation direction (θ direction). Rotating the photosensitive substrate (P) on the movable stage means (3) so as to correct the positional deviation between the two positions, and detecting two positions in the reference coordinate systems X and Y.
Each position deviation is compensated according to each position deviation in the coordinate axis direction.
Move the movable stage means (4, 5) to correct
A step of controlling so as to shift the position coordinates from the desired position Te, was provided. According to a tenth aspect of the present invention, in the exposure method according to the ninth aspect, the photosensitive substrate (P) has a rectangular shape having two sides orthogonal to each other, and two of one side of the two orthogonal sides and another. The amount of movement of each of the three movers (40) that can abut each of the one place on one side of is measured,
Based on the three measured values, 2 in the reference coordinate system X, Y
Direction (X-axis direction and Y-axis direction) and rotation direction (θ
Direction) is calculated. Claim 11
According to the described invention, there is provided an exposure method for forming a predetermined pattern at a predetermined position on a substrate (P), wherein a reference coordinate system X, Y
Placing the substrate (P) on the movable stage means (3, 4, 5) that moves to the target position based on the position information at
Position information defining the outer shape of the substrate (P) placed on the movable stage means (3, 4, 5) is transferred to a reference coordinate system X, Y
Detecting one of two coordinate axis directions (X-axis direction and Y-axis direction) orthogonal to each other at two points, and detecting the other coordinate axis (Y-axis) at one point And a reference coordinate system X, Y based on the detection result of the position information defining the outer shape of the substrate (P) and the reference coordinate systems X, Y.
Determining the amount of displacement of the substrate (P) with respect to Y, and changing at least a part of the value of the reference coordinate system with respect to the target position based on the amount of displacement. Substrate (P) on stage device
And a holder (3) for moving the substrate (P) in the rotation direction (θ direction) in the reference coordinate systems X and Y, and at least one in the reference coordinate systems X and Y supporting the holder (3). Substrate (P) and holder (3) in one coordinate axis direction
Stage portions (4, 5) for moving the substrate, and substrate position detecting means (10A, 10B, 10) provided on at least one of the holder (3) and the stage portions (4, 5).
By C), position information for defining the outer shape of the substrate (P) is obtained. According to a twelfth aspect of the present invention, in the exposure method according to the eleventh aspect, the amount relating to the displacement of the substrate (P) with respect to the reference coordinate systems X and Y is defined by a previously stored reference value and the outer shape of the substrate (P). The calculation is performed based on the detection result of the position information to be performed. According to a thirteenth aspect of the present invention, in the exposure method according to the eleventh aspect, a reference mark (Mr) is provided in the position information detecting section (40) for defining the outer shape of the substrate (P), and the reference mark (Mr) The reference value is determined based on the result of detecting the position. According to a fourteenth aspect of the present invention, in the exposure method according to the eleventh aspect, the position information defining the outer shape of the substrate (P) is detected in a non-contact manner with respect to the substrate (P). According to a fifteenth aspect of the present invention, in the exposure method according to the eleventh aspect, the position information defining the outer shape of the substrate (P) is detected at a plurality of positions on the substrate (P).
According to a sixteenth aspect of the present invention, in the exposure method according to the fifteenth aspect, at least one of the position information defining the outer shape of the substrate (P) is detected in a non-contact manner with respect to the substrate (P). .

[0012]

In the invention described in each of the claims, a mechanism for pressing the substrate (plate) from the outside is eliminated, the substrate conveyed on the movable stage is sucked on the holder, and then the outer position of the substrate is set to 3 Measure in points. Then, a deviation amount in the X and Y directions and a rotation error amount of the substrate with respect to a reference coordinate system (movable stage moving coordinate system) are obtained, and the stepping position is designed so that these deviation amounts are corrected at the time of projection exposure. An offset is added to the target value determined above.
Note that the rotation error amount of the substrate may be corrected by rotating the reticle side. As described above, since the peripheral edge of the substrate conveyed onto the holder (movable stage) is not restrained by the reference pins or the like, the substrate is reliably flattened by suction. Moreover, since the substrate itself does not slide on the holder, generation of static electricity,
Dust generation is prevented, and no damage is caused on the end face of the substrate.

[0013]

FIG. 3 is a functional block diagram showing a main part of an apparatus configuration according to an embodiment of the present invention. In the present embodiment, the length measuring devices 10A, 10A,
0B and 10C are attached. In FIG. 3, the imaginary line indicates the plate PI ideally placed on the holder 3, and the length measuring device 10 </ b> A moves in the Y direction to make 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 each have a contact that moves in the X direction and makes a light contact at two locations on the edge Ey of the plate P extending in the Y direction. The driving of the abutment is performed by the measurement control unit 20, and after the measurement by the contact of the abutment,
Each contact is driven to a predetermined retracted position. Also, the length measurement signals DY, DX, Dθ of the length measuring devices 10A, 10B, 10C.
Is input to the calculation unit 22, where each measured value is stored in the storage unit 2.
By calculating the deviation from the reference value stored in advance in FIG. 4, the two-dimensional displacement (ΔX, ΔY, Δθ) of the actual plate P with respect to the ideal position of the plate PI is calculated. Is calculated. Here the length measuring device 10
The reference values in the storage unit 24 given in advance to A, 10B, and 10C are Y _r , X _r1 , and X _r2 , respectively, and the length measurement values DY, D actually measured for the plate P
Assuming that X and Dθ are Y ₁ , X ₁ and X ₂ , the rotational deviation Δθ is expressed by the following equation, where L is the distance (span) between the abutments of the two length measuring devices 10 B and 10 C in the Y direction. .

Δθ ≒ arcsin ((X _r1 −X _r2 −X ₁ + X ₂ ) / L) (1) The parallel displacements ΔX and ΔY in the X direction and the Y direction have a small rotation displacement Δθ. The range is represented by the following equation. ΔY ≒ Y _r −Y ₁ (2) ΔX ≒ ((X _r1 −X ₁ ) + (X _r2 −X ₂ )) / 2 + N (3) where N in equation (3) is the length measuring device 10B. , 10C, according to the difference (Ycc−Ycp) in the Y direction between the midpoint Ycc of the span L of each abutment and the midpoint Ycp of the edge Ey of the plate pin, and when the difference is substantially zero, N becomes 0 and FIG.
In the arrangement, N is represented by the following equation.

N ≒ Δθ · (Ycc−Ycp) (4) The shift amounts (ΔX, ΔY, Δ
θ) is sent to the main control system 26, and the main control system 26 sends the rotational deviation 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 rotational deviation Δθ. On the other hand, with respect to the shift amounts ΔX and ΔY in the X and Y directions, the target positions of the X and Y stages 4 and 5 specified at the time of exposure to the plate P are corrected by the shift amounts ΔX and ΔY to adjust the stage control system 30. Is 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 are processed before and after mechanically. May be determined by the global alignment of the plates. In any case, those target positions are stored in the memory of the specifying 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 current position of the XY stage may be monitored by the X, Y interferometer, and the motors MX, MY may be stopped when the current position matches the corrected target position.

FIG. 4 shows three length measuring devices 10A, 10B, 1
An example of a specific structure of 0C is shown. Here, a length measuring device 10B is shown as a representative. The movable abutment 40 of the length measuring device 10B is
A roller is rotatably supported on one end of a U-shaped swinging member 100 rotatably supported on the axis 101 in the XY plane. A piston of an air cylinder 103 is engaged with the other end of the swing member 100, and a potentiometer 104 is engaged between a shaft 101 of the swing member 100 and an engagement point of the piston of the air cylinder 103. Have been. When the piston of the air cylinder 103 moves in the Y direction in such a structure, the swing member 100 rotates, and the roller 40 moves substantially in the X direction. Other two length measuring instruments 1
0A and 10C have exactly the same structure. The weak pressing force of the air cylinder 103 is increased by leverage of the swing member 100, and the contact force of the roller 40 with the plate edge is made 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 to the holder 3, the minute rotation position of the holder 3 is returned to the neutral point (or any 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 _No. 4 are determined so as to have a unique correspondence with respect to the movement reference coordinate system of the XY stage (defined by the X and Y interferometers). That is, it is necessary to always recognize the plate P on the holder 3 as a rotational position shift on the movement reference coordinate system. However, when measuring the edges with 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 amounts themselves result in residual rotation errors 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 to the rotation angle position (neutral point or reference angle position) of the holder 3 when the reference values _Xr1 , _Xr2 , and _Yr are set. However, when there is an angle sensor or the like that detects the minute rotation amount of the holder 3 with high accuracy, the rotation amount Δφ from the neutral point of the holder 3 or the reference angle position at the time of length measurement by the length measuring device is obtained. Since the above-mentioned unknown amount is known, the rotation deviation amount Δθ obtained by the above equation (1) is obtained.
The holder 4 may be corrected and rotated by the motor Mθ by a value that takes the residual rotation amount Δφ into consideration.

As another concept, three length measuring devices 10 are used.
A, 10B, and 10C may be fixed to the X stage 4 side serving as a base for the holder 3, and may be extended so that only the abutment contacts the edge of the plate P on the holder. In this case, since the X stage 4 will not be rotated in the mobile reference frame, the reference point X _r1, X _r2, Y _r also does not rotate in the reference coordinate system. Therefore holder 3
Regardless of how the holder 3 is rotated when the plate P is received above, the rotation deviation amount Δθ of the plate P is always obtained with reference to the movement reference coordinate system, regardless of the rotation.

In the above embodiment, the length measuring devices 10A, 10A
B and 10C store predetermined reference values 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, the test plate P is automatically conveyed onto the holder 3 with the angle value of the holder 3 in the neutral state at the time of device manufacturing or maintenance, and then the test plate P is placed on the holder 3 so as to minimize the displacement. Adjust the position manually.
After that, the test plate P is vacuum-sucked on the holder 3, and then a search mode for global alignment of the plate is executed. At this time, it is confirmed whether or not the alignment mark formed on the test plate P is within a range easily captured by the alignment sensor of the stepper. In particular, regarding the rotational displacement of the test plate P, the positions of the alignment marks formed at two places on the plate P are measured using an alignment sensor and an X, Y interferometer, and the position is measured in the X direction or Y direction.
It may be determined from the positional difference in the direction. As a result of the above confirmation, when the rotational displacement and the positional displacement in the X and Y directions are not yet sufficiently small, the vacuum suction of the holder 3 is released, and
The position of the test plate P is manually adjusted again.
These operations are repeated several times, and when the test plate P is driven to the almost ideal position (PI), the length measuring devices 10A, 10B,
Edge Ex, Ey of test plate of each contact of 10C
And 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, the reference values Y _r ,
Since both _Xr1 and _Xr2 are obtained as voltage values, these voltage values are converted into digital values and stored in the storage unit 24. The second method is to use three length measuring devices 10A, 10A,
A reference mark for positioning that is observable by the alignment sensor is engraved on a part of each of the movable abutments B and 10C, and the coordinate position of the XY stage when the reference mark is detected by the alignment sensor is measured. it is, is what determines the reference value Y _r, X _r1, X _r2 on a mobile reference frame. FIG. 5 is an enlarged view of the vicinity of the length measuring device 10B on the holder 3, and a roller 40 as a contact movable in the X direction is arranged on the length measuring device 10B so as to be able to contact the edge Ey of the plate P. ing. A reference mark Mr is formed on a part of the movable piece that supports the roller 40 at a height position substantially coincident with 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 fixed at a position at a fixed distance in the X direction from the outer peripheral surface of the roller 40 (a contact surface with the edge Ey). Have been.
Reference marks are provided for the other length measuring devices 10A and 10C with the same structure.

As an alignment sensor for observing the reference marks Mr, an off-axis 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 passing through the image plane.
The point C ₁ of spaced image plane a certain direction distance (base line amount), an objective lens 50 which is arranged to pass through the optical axis AXa, the beam splitter for splitting the reflected light from the illumination light and the plate 51, an imaging lens 52, and a mirror 5
3, an index plate 54, an imaging lens 55 for enlarging and photographing a pattern in a window formed on the index plate 54 and an image such as a mark on a plate formed in the window, and a CCD 56 as a television camera. And The CCD 56 is a window (or pattern) of the index plate 54 for the mark image on the plate.
In this embodiment, the image is used to observe the image of the reference mark Mr shown in FIG. The base line amount between the point C ₀ and the point C ₁ is set in advance as a mechanically fixed value.

Then, an arbitrary plate P is placed on the holder 3.
After sucking and feeding out the roller of the length measuring device, the XY stage
4 and 5 to move the reference mark attached to the length measuring instrument 10B.
The portion where the angle Mr should exist as the ideal position
0, and its coordinates (X
_p1, Y_p1) Is read and stored by an X, Y interferometer. this
In the stage, the reference mark is not necessarily placed at the center of the visual field of the objective lens 50.
Qu does not always come. Next, the field of view of the objective lens 50
At the center, ie, the center of the window of the index plate 54, the reference mark Mr
The XY stages 4 and 5 are slightly moved so that is positioned. This
Is reproduced on the TV monitor by the imaging signal of the CCD 56.
It can be confirmed by producing. And XY stage after fine movement
Coordinate value (X_p2, Y_p2) Is read and stored by the XY interferometer
I 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) To the length measuring device 10B
Measurement value DX and its reference value X_r1Equal to the difference
It will be good. Therefore, the value measured by the length measuring device 10B
The amount of deviation from DX (X_p1-X _p2Corrects the voltage component corresponding to)
The value obtained is the reference value X_r1It may be calculated as Also length measuring device
Similarly, for 10C, the reference mark is
The XY stage is moved so as to detect at 50. this
Since the length measuring device 10C is also used for measurement in the X direction, the XY
The X coordinate value of the tage is X_p1Fine movement with reference to
The X coordinate value when the reference mark of 10C is detected is X_p3When
I do. Therefore, the deviation from the measured value Dθ by the length measuring device 10C is
Quantity (X_p1-X_p3) Based on the value corrected for the voltage corresponding to
Value X_r2It may be calculated as

The above sequence can be similarly executed even when the alignment mark on the plate P sucked and held on the holder is detected by the off-axis alignment system shown in FIG. In a third method, among a plurality of plates P to be subjected to exposure processing, a result of global alignment or the like with respect to a first plate P is determined by using a length measuring device 10A during processing of second and subsequent plates P, 10B, 10C
Is used to correct the reference value. Here, the reference values set at the time of processing the first plate P are XR1, XR
2, YR, and the displacement amounts measured by the measuring device in accordance therewith are represented by ΔXf, ΔYf, and Δθf. Thereafter, the global alignment and the fine alignment are executed in a state where the positional deviation amount is corrected. At this time, the residual deviation amounts ΔXe, ΔYe, Δθ of the plate P are further increased.
e is obtained. It is preferable that the residual shift amounts ΔXe, ΔYe, and Δθe are extremely small. If the residual shift amounts are above a certain range, the reference values corresponding to the values are corrected. That is, 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, XR
2 may be corrected by an amount corresponding to ΔXe. When Δθe is large, the correction may be performed so that a difference in the amount corresponding to Δθe occurs between the reference values XR1 and XR2.

In this manner, the measurement accuracy of the length measuring devices 10A, 10B, and 10C for the second and subsequent plates P is improved, and the global alignment or fine alignment processing is smoothly performed. However, this method is possible when the reproducibility of the pre-alignment accuracy of the second and subsequent plates P automatically conveyed onto the holder 3 is good, and the pre-alignment accuracy varies for each plate P. When it ’s big, it ’s difficult.
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 having movable contactors
Is used to measure the positions of the edges Ex and Ey of the plate P, but the edges can be measured without any contact. As an example, it is conceivable to use an off-axis alignment type television camera (CCD 56) shown in FIG. In this case, the edge E of the plate P is located within the imaging range of the CCD 56, that is, within the window of the index plate 54.
x and Ey are sequentially positioned as shown in FIG.
Based on the image signal of CD56, edge Ex or Ey
Is detected, and the coordinate values of the XY stages 4 and 5 at that time are read from the interferometer. The edge Ey is measured at two locations separated by a fixed amount in the Y direction. Then, from the above measurement results, the amount of displacement (ΔX, ΔY, Δθ) of the plate P with respect to the movement reference coordinate system is obtained by calculation.

At this time, the edge Ey of the plate P picked up by the CCD 56 is observed on the television monitor, for example, as shown in FIG. FIG. 8A shows an image of an edge Ey shifted by ΔX _{1 in the} X direction with respect to a center line CL in the window of the index plate 54 parallel to the Y axis, and is orthogonal to the center line CL in FIG. 4 shows a waveform of a video signal VS obtained by a scanning line. Usually, since the plate P has a thickness of about 1 mm to several mm, in an alignment system having an epi-illumination system as shown in FIG. 6, a shadow is formed at the edge Ey and observed. For this reason, a bottom portion occurs in the waveform of the video signal VS, and the shift amount ΔX ₁ is obtained by detecting the bottom portion. The center line CL is the midpoint between the left and right edges of the window 54.

As described above, a one-dimensional (or two-dimensional) image sensor is embedded in at least three places in the holder 3 in addition to the non-contact length measuring system using the television camera, and the edges Ex and Ey are shadowed. You may make it detect. At this time, the pixel arrangement direction of the one-dimensional image sensor is set in a direction intersecting each of the edges Ex and Ey. The measurement procedure is as follows. And illuminating light is projected onto an edge portion corresponding to the position. The illumination light from the off-axis alignment system shown in FIG. 6 can be used. This is because the illumination light for observation of the alignment system is set in a wavelength region that has almost no sensitivity to the resist layer on the plate P. Then, the pixel positions where the shadow of the edge appears on the three image sensors may be detected, and the shift amount from the reference pixel on each image sensor may be obtained in advance.

[0028]

As described above, according to the inventions described in the claims, it is possible to position the substrate without mechanically pressing the substrate. For this reason, for example, it is effective for use in a liquid crystal device for performing pattern exposure on a large glass plate or the like, or for use in aligning a plate of an exposure apparatus. Large glass plates are liable to be distorted by heat treatment in the process, and the weight of the plate is large and the friction with the holder is large. is there. However, according to the invention described in each claim, the plate on the holder does not move to be pressed against the reference pin or the like after being placed. As a result, effects such as prevention of dust generation, prevention of unnecessary stress generated in the plate, prevention of poor suction to the holder, and the like can be obtained, and the operation rate of the exposure apparatus can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the overall configuration of a conventionally used rectangular plate exposure apparatus.

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

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

FIG. 4 is a perspective view showing an example of the structure of a length measuring device in FIG. 3;

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 a length measuring device.

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

[Explanation of Signs of Main Parts]

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

Claims (16)

(57) [Claims] 1. A means for holding a mask on which an original pattern to be exposed is formed, a projection optical system for projecting the original pattern onto a predetermined image plane, and substantially parallel to and orthogonal to the image plane. A rectangular photosensitive substrate having two sides is held, and two coordinate axis directions orthogonal to each other in a reference coordinate system defined in a plane parallel to the imaging plane, and a rotation direction in the reference coordinate system. Movable stage means for moving the photosensitive substrate, and after the photosensitive substrate is placed on the movable stage means at the transfer position in the reference coordinate system, the movable element is brought into contact with an outer side of the photosensitive substrate . Until the mover touches
The position of the outer side is detected based on the amount of movement of the outer side, position information on the outer side is detected at two points with respect to one of the coordinate axes orthogonal to each other in the reference coordinate system, and the outer side is detected with respect to the other coordinate axis. Location information about the side is 1
Deviation detection means for detecting a positional deviation between the two coordinate axis directions and the rotation direction in the reference coordinate system of the photosensitive substrate by detecting at a point; and correcting the positional deviation in the rotation direction detected by the deviation detection means. Rotation driving means for rotating the photosensitive substrate on the movable stage means, and projection exposure of the original pattern in accordance with the amount of each positional deviation in two coordinate axis directions detected by the deviation detecting means. An exposure apparatus, further comprising: control means for controlling a positioning coordinate when moving the movable stage means from an intended position. 2. The apparatus according to claim 1, wherein the deviation detecting means is provided in front of each of two points on one side of the two orthogonal sides and one point on the other side.
Three movable elements that can be contacted as movable elements ,
Three length measuring devices for measuring the amount of movement of the mover , and two length measuring units in the reference coordinate system based on the length measured by the three length measuring devices.
2. The exposure apparatus according to claim 1, further comprising a calculating unit that calculates a positional deviation between two coordinate axis directions and a rotation direction. 3. An exposure apparatus for forming a predetermined pattern at a predetermined position on a substrate, wherein the substrate is mounted and movable to move the substrate to a target position based on position information in a reference coordinate system. Stage means, position information defining the outer shape of the substrate mounted on the movable stage means, is detected at two points with respect to one coordinate axis of the coordinate axes orthogonal to each other in the reference coordinate system, and with respect to the other coordinate axis, Substrate position detecting means for detecting at one point; deviation detecting means for detecting an amount of displacement of the substrate with respect to the reference coordinate system based on the detection result of the substrate position detecting means and the reference coordinate system; Control means for changing at least a part of a value of the reference coordinate system with respect to the target position based on a detection result of the deviation detection means. A holder that holds and moves the substrate in the rotation direction in the reference coordinate system, and a stage that supports the holder and moves the substrate and the holder in at least one coordinate axis direction in the reference coordinate system. An exposure apparatus, wherein the substrate position detecting means is provided on at least one of the holder and the stage unit. 4. The apparatus according to claim 1, wherein the deviation detecting unit is configured to perform a detection based on a reference value stored in advance and a detection result of the substrate position detecting unit.
4. The exposure apparatus according to claim 3, wherein an amount related to a displacement of the substrate with respect to the reference coordinate system is calculated. 5. The apparatus according to claim 1, further comprising: a reference mark provided on the substrate position detection means; and a sensor for detecting a position of the reference mark, wherein the reference value is determined based on a detection result of the sensor. The exposure apparatus according to claim 4, wherein 6. An exposure apparatus according to claim 3, wherein said substrate position detecting means detects position information defining an outer shape of said substrate in a non-contact manner. 7. An exposure apparatus according to claim 3, wherein said substrate position detecting means has a plurality of detecting sections, and detects position information defining an outer shape of said substrate at a plurality of positions on said substrate. . 8. An exposure apparatus according to claim 7, wherein said substrate position detecting means has at least one detecting unit for detecting position information defining an outer shape of said substrate in a non-contact manner. 9. A means for holding a mask on which an original pattern to be exposed is formed, a projection optical system for projecting the original pattern onto a predetermined image plane, and holding a photosensitive substrate substantially parallel to the image plane. And movable stage means for moving the photosensitive substrate in two coordinate axis directions orthogonal to each other in a reference coordinate system defined in a plane parallel to the imaging plane, and in a rotation direction in the reference coordinate system. In the exposure method, after the photosensitive substrate is placed on the movable stage means at a transfer position in the reference coordinate system, a movable element that can contact an outer side of the photosensitive substrate is brought into contact with the photosensitive substrate. This mover
Detecting the outline side based on the amount of movement until contact, and detecting, at two points, position information regarding the outline side with respect to one of the coordinate axes orthogonal to each other in the reference coordinate system,
A step of detecting a positional deviation between the two coordinate axis directions and the rotational direction in the reference coordinate system of the photosensitive substrate by detecting position information on the outer side at one point with respect to the other coordinate axis; Rotating the photosensitive substrate on the movable stage means so as to correct the positional deviation of the two coordinate axes in the two coordinate axes detected in the reference coordinate system.
Depending on the position deviation, for correcting each positional deviation
Then, by moving the movable stage means, the positioning coordinates
An exposure method, comprising: controlling to shift from an intended position . 10. The photosensitive substrate has a rectangular shape having two sides orthogonal to each other, and one of the two sides orthogonal to each other has a rectangular shape.
3 places that can be abutted on each of two places and one place on the other side.
The moving amount of each of the two movers is measured, and a position deviation between two coordinate axis directions and a rotation direction in the reference coordinate system is calculated based on the three measured values. Exposure method. 11. An exposure method for forming a predetermined pattern at a predetermined position on a substrate, comprising: mounting the substrate on movable stage means that moves to a target position based on positional information in a reference coordinate system. Position information defining the outer shape of the substrate mounted on the movable stage means is detected at two points with respect to one of the coordinate axes orthogonal to each other in the reference coordinate system, and at one point with respect to the other coordinate axis. Based on the detection result of the position information that defines the outer shape of the substrate and the reference coordinate system, and obtaining an amount related to the displacement of the substrate with respect to the reference coordinate system, based on the amount related to the displacement. Changing the value of at least a part of the reference coordinate system with respect to the target position, wherein the movable stage device holds the substrate and moves forward in the reference coordinate system. A holder for moving the substrate in the rotation direction, and a stage for supporting the holder and moving the substrate and the holder in at least one coordinate axis direction in the reference coordinate system, wherein the holder or the stage An exposure method, wherein position information defining an outer shape of the substrate is obtained by substrate position detection means provided on at least one of the substrates. 12. The method according to claim 1, wherein the amount relating to the displacement of the substrate with respect to the reference coordinate system is calculated based on a reference value stored in advance and a detection result of position information defining an outer shape of the substrate. The exposure method according to claim 11. 13. The method according to claim 11, wherein a reference mark is provided in a position information detecting section that defines the outer shape of the substrate, and the reference value is determined based on a result of detecting the position of the reference mark. Exposure method. 14. The exposure method according to claim 11, wherein the position information defining the outer shape of the substrate is detected without contacting the substrate. 15. The exposure method according to claim 11, wherein position information defining an outer shape of the substrate is detected at a plurality of positions on the substrate. 16. The exposure method according to claim 15, wherein at least one of the position information defining the outer shape of the substrate is detected without contacting the substrate.