JPH0822948A - Scanning aligner - Google Patents

Abstract

PURPOSE:To reduce the effect of the fluctuations of the air to wafer stage position-measuring laser interferometers. CONSTITUTION:A wafer 6 is held on a wafer X stage 10, the stage 10 is placed on a wafer Y stage 9 movably in a direction X, the stage 9 is placed on a scan stage 8 movably in a direction Y and the stage 8 is placed on a device base 8 movably in the direction Y. After shot regions on the wafer 6 are positioned at a scanning start position using the stages 10 and 9, the stage 8 is scanned in a direction +Y or a direction -Y to perform exposure. The position of the stage 8 is measured using laser interferometers 26 to 28 or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning type exposure apparatus for sequentially exposing a pattern on a mask onto a photosensitive substrate by synchronously scanning the mask and the photosensitive substrate in predetermined directions, and more particularly to a photosensitive substrate. Suitable for applying to a step-and-scan projection type scanning exposure apparatus that exposes a mask pattern to each shot area by a scanning exposure method after moving the above shot areas to a scanning start position by a stepping method Is.

[0002]

2. Description of the Related Art For example, when a semiconductor device, a liquid crystal display device, a thin film magnetic head, or the like is manufactured by a photolithography process, a wafer (or a glass plate, etc.) to which a reticle (or photomask, etc.) pattern is coated with a photosensitive material A projection exposure apparatus for transferring onto the top is used. Conventionally, mainly
A step-and-repeat type reduction projection type exposure apparatus (stepper or the like) that sequentially transfers and exposes an image of a reticle pattern onto each shot area of a wafer has been widely used.

However, in recent years, since one chip pattern has become large in a semiconductor element or the like, there is also a need for an exposure apparatus capable of exposing a pattern having a larger area. However, the resolution and other imaging performance (distortion, field curvature, etc.) over the entire wide exposure field of the projection optical system.
Is difficult to maintain to a predetermined accuracy. Therefore, the scanning exposure apparatus is currently receiving attention. An exposure apparatus, which should be called a prototype of this scanning type exposure apparatus, includes a reflection projection optical system having a projection magnification of 1 ×, a reticle stage holding a 1 × reticle (a so-called mask in a narrow sense), and a wafer stage holding a wafer. Is a mirror projection aligner that scans and exposes a reticle and a wafer at the same speed by coupling the same to a common moving column. The catadioptric optical system of the same magnification has good chromatic aberration in a wide exposure wavelength range because it does not use a refraction element (lens), and has two or more kinds of bright line spectra (for example, g-line and The exposure intensity can be increased by simultaneously using (h-line, etc.), and therefore high-speed scanning exposure is possible.
In the reflective projection optical system, the S (sagittal) image plane and the M
(Meridional) Since the point at which both astigmatism with the image plane is zero is limited to near the image height position at a certain distance from the optical axis of the catoptric system, the shape of the exposure light that illuminates the reticle is wide. It is a so-called arc slit, which is a part of the narrow annular zone.

In such an equal-magnification scanning exposure apparatus, when a projection optical system is used in which the pattern image of the reticle projected on the wafer does not have a mirror image relationship, the reticle and the wafer are integrated. The exposure is completed by holding the movable column in an aligned state and then causing the movable column to perform one-dimensional scanning in the lateral direction of the arc slit illumination light. On the other hand, when using a unit-magnification projection optical system in which the reticle pattern image projected on the wafer has a mirror image relationship, it is necessary to move the reticle stage and the wafer stage in opposite directions at the same speed. is there.

Further, as a conventional scanning type exposure method, there is also a method in which a reticle stage and a wafer stage are relatively scanned at a speed ratio corresponding to the magnification in a state in which a refraction element or the like is incorporated to enlarge or reduce the projection magnification. Are known. In this case, as the projection optical system of the scanning type exposure apparatus, a combination of a reflection element and a refraction element, or a combination of only the refraction element is used, and a reduced projection in which the reflection element and the refraction element are combined. An example of an optical system is disclosed in JP-A-63
It is disclosed in Japanese Patent Publication No. 163319.

[0006]

However, when a conventional scanning type exposure apparatus having a projection optical system with a reduction magnification is used, the exposure area on the wafer is only about several tens of millimeters, and so on. Unlike the double scanning exposure apparatus, the entire surface of the wafer cannot be exposed by one scanning exposure. Therefore, it is necessary to perform exposure by the step-and-scan method in which each shot on the wafer is moved to the scanning start position with respect to the visual field of the projection optical system by the step-and-repeat method, and then each scanning exposure is performed. Therefore, the stroke of the wafer stage is almost equal to the diameter of the wafer, and the path (optical path) of the laser interferometer for measuring the position of the wafer stage needs to have the same length as the diameter of the wafer.
However, in such a long path of the laser interferometer, the influence of air fluctuation is great, and there is a disadvantage in that the control accuracy of the position and speed of the wafer during scanning exposure is deteriorated. Therefore, in order to reduce the influence of the fluctuation of the air, measures such as covering the path of the laser interferometer with a cover and flowing temperature-controlled air are taken, but still sufficient control accuracy can be obtained. Not not.

Therefore, the applicant of the present invention continuously performs relative alignment between the reticle and the wafer during the scanning exposure so that the laser interferometer is not displaced even if it is affected by air fluctuations. A projection type scanning exposure apparatus is proposed in Japanese Patent Laid-Open No. 4-307720. However, in such an apparatus, when the wafer mark for alignment is partially damaged by the process of etching the wafer, the process of forming a film on the wafer by vapor deposition, etc., the alignment accuracy is There is an inconvenience that it decreases.

In view of the above problems, the present invention reduces the influence of air fluctuations on the laser interferometer for measuring the position of the wafer stage to reduce the influence of air fluctuations on the wafer (photosensitive substrate) during scanning exposure.
It is an object of the present invention to provide a scanning type exposure apparatus in which the control accuracy of the position and speed of is improved. Another object of the present invention is to provide a scanning type exposure apparatus with improved alignment accuracy.

[0009]

A scanning type exposure apparatus according to the present invention illuminates a mask (1) on which a transfer pattern is formed, and illuminates the mask (1) in a first direction (Y direction or-).
By scanning the photosensitive substrate (6) in the second direction (-Y direction or Y direction) in synchronization with the scanning in the Y direction), the pattern of the mask (1) is sequentially obtained on the substrate (6). In a scanning type exposure apparatus that exposes each of the above exposure areas, a positioning substrate stage (9, 10) for positioning the substrate (6) on a two-dimensional plane parallel to the exposure surface of the substrate,
Position measuring means (58, 59) for measuring the two-dimensional position of the positioning substrate stage, and a scanning substrate stage (8) for scanning the substrate (6) in the second direction during scanning exposure. And an interferometer (20 to 31) for measuring the position of the scanning substrate stage (8) in the second direction.

In this case, the alignment marks (47, 48) formed on the mask (1) and the substrate (6).
An alignment system (AL) is provided for detecting the amount of positional deviation relative to the alignment marks (45, 46) formed on the substrate (6) via the positioning substrate stage (9, 10). When the positioning is performed, it is preferable that the amount of positional deviation detected by the alignment system (AL) falls within a predetermined allowable range.

Further, it is preferable that the positioning substrate stage (9, 10) is mounted on the scanning substrate stage (8). Further, the scanning substrate stage (8) may be placed on the positioning substrate stage (9, 10).

[0012]

According to the present invention, the interferometers (20 to 3) for monitoring the position of the scanning substrate stage (8) during scanning exposure.
Since the path of 1) may be as short as the moving distance (scan length) of the substrate (6) during scanning exposure, the influence of air fluctuations on the interferometer is extremely small, and the substrate (6) during scanning exposure.
The position and speed of the are controlled with high precision.

Further, using an alignment system (AL),
A predetermined relative displacement amount between the alignment marks (47, 48) formed on the mask (1) and the alignment marks (45, 46) formed on the substrate (6) before the start of scanning is determined. In order to bring the mask (1) and the substrate (6) within the permissible range, the mask (1) and the substrate (6) are aligned with high precision. Even in the subsequent scanning exposure, the alignment accuracy is maintained with high accuracy.

When the positioning substrate stage (9, 10) is placed on the scanning substrate stage (8), the positioning substrate stage (8) is used for positioning even if scanning is performed. Since the positional relationship between the substrate stage (9, 10) and the substrate (6) is maintained stably, the alignment accuracy is maintained with high accuracy. On the other hand, when the scanning substrate stage (8) is placed on the positioning substrate stage (9, 10), it is necessary to perform control for preventing positional deviation during scanning exposure. The stage (8) can be made lighter.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the scanning type exposure apparatus according to the present invention will be described below with reference to FIGS. In this embodiment, the present invention is applied to a step-and-scan projection exposure apparatus that reduces a pattern on a reticle to 1/4 by a projection optical system and exposes each shot area on a wafer by a scanning exposure method. It is a thing.

FIG. 1 shows a schematic configuration of the projection exposure apparatus of this embodiment. In FIG. 1, the exposure illumination light IL emitted from an illumination optical system (not shown) is almost directed to the reticle 1. The light is reflected by a dichroic mirror 51 arranged at an inclination angle of 45 °, irradiated onto a rectangular illumination area (hereinafter referred to as “slit-shaped illumination area”) 49 on the reticle 1, and drawn in the illumination area 49. The circuit pattern is exposed on the surface of the wafer 6 via the projection optical system 3. Here, in FIG. 1, the optical axis of the projection optical system 3 (A
The Z axis is taken parallel to (X), the X axis is taken parallel to the paper surface of FIG. 1 and the Y axis is taken perpendicularly to the paper surface of FIG.

When the projection magnification of the projection optical system 3 is β (β = 1/4 in the present embodiment), when the circuit pattern of the reticle 1 is exposed on the surface of the wafer 6, illumination light is emitted. With respect to the slit-shaped illumination area by the IL, the reticle 1 is scanned in the front direction (−Y direction) at a constant speed V _R with respect to the paper surface of FIG. is scanned at a constant speed V _W = β · V _R in the backward direction (Y direction) with respect to.

The reticle 1 on which a circuit pattern is drawn is vacuum-sucked on a reticle stage 2, and this reticle stage 2 is X-axis in a two-dimensional plane (XY plane) perpendicular to the optical axis AX of the projection optical system 3. The reticle 2 is positioned in the Y direction, the Y direction, and the rotation direction (θ direction). Further, the reticle stage 2 can scan the reticle 1 in the Y direction (scanning direction) at a predetermined scanning speed. That is, the reticle stage 2 has a movement stroke in the Y direction that is sufficient to allow the entire area of the pattern drawn on the reticle 1 to pass over the slit-shaped illumination area of the illumination light IL.
Position coordinates (x _r , in the two-dimensional plane of the reticle stage 2
y _r , θ _r ) is a moving mirror 53 on the reticle stage 2,
And at least three systems of laser interferometers 52 arranged in the periphery. In the position coordinates, x _r represents the X coordinate, y _r represents the Y coordinate, and θ _r represents the rotation angle in the two-dimensional plane. The position of the reticle stage 2 is the laser interferometer 52.
Is constantly detected with a resolution of, for example, about 0.01 μm. The position information of the reticle stage 2 from the laser interferometer 52 is sent to a stage control system (not shown).

2 and 3 are a perspective view and a plan view, respectively, showing the structure around the wafer stage of the projection exposure apparatus of this embodiment. The structure around the wafer stage will be described in detail with reference to FIGS. The wafer stage is a collective term for the entire stage including the wafer X stage 10, the wafer Y stage 9, and the scan stage 8.

The wafer 6 is held by vacuum suction on a wafer X stage 10 which is movable in the X direction by a length corresponding to the diameter of the largest wafer exposed by this projection exposure apparatus, and the wafer X stage 10 has a maximum length. The wafer is mounted on a wafer Y stage 9 which is movable in the Y direction by a length corresponding to the diameter of the wafer. Further, the wafer Y stage 9 is mounted on the scan stage 8 having a stroke in the Y direction that is β times (¼) the stroke of the reticle stage 2 in the Y direction, and the scan stage 8 is mounted on the apparatus base 7. It is placed.

The wafer Y stage 9 comprises a linear motor 1
3, 14 moves in the Y direction relative to the scan stage 8 to move the wafer Y relative to the scan stage 8.
The relative position of the stage 9 in the Y direction is determined by the linear motor 13,
It is measured by a linear encoder 58 arranged in parallel with 14. The linear motor 13 is composed of a linear guide fixed on the scan stage 8, a stator installed in parallel with the linear guide, and a mover fixed on the wafer Y stage 9 side. The same applies to other linear motors. The linear encoder 58 is composed of an optical scale 58b on the scan stage 8 and a detector 58a fixed to the wafer Y stage 9, and the linear encoder 58 measures the position with a resolution of about 1 μm.

Next, the wafer X stage 10 is moved in the X direction relative to the wafer Y stage 9 by the linear motor 15. The relative position of the wafer X stage 10 with respect to the wafer Y stage 9 in the X direction is arranged in parallel with the linear motor 15 by a linear encoder 59.
It is measured by an optical scale 59b and a detector 59a.

Further, the scan stage 8 is moved by the linear motors 11 and 12 in the Y direction relative to the device base 7, and the relative positions of the scan stage 8 with respect to the device base 7 are the four directions of the scan stage 8. It is measured by the arranged laser interferometers 20 to 31.
The laser interferometers 20 to 22 are fixed to the interferometer pedestal 16 provided at the end of the device base 7 in the −Y direction, and the laser interferometers 26 to 28 are provided at the end of the device base 7 in the + Y direction. It is fixed to the interferometer pedestal 18 and measures the Y-direction coordinate and the rotation angle of the scan stage 8 together. Specifically, by the average value of the measurement values of the laser interferometers 20 to 22,
The coordinates in the Y direction are monitored, the rotation angle (yawing) in the XY plane of the scan stage 8 is measured by the difference between the measurement value of the laser interferometer 20 and the measurement value of the laser interferometer 21, and the laser interferometers 20 and 21 are measured. The pitching of the scan stage 8 is measured by the difference between the average value of the measurement values of 1 and the measurement value of the laser interferometer 22. Laser interferometer 26-28
In the same manner, the position of the scan stage 8 is measured by the same operation, and the position measurement accuracy of the scan stage 8 is improved by averaging the measurement results of the laser interferometers 20 to 22.

The laser interferometers 23 to 25 are fixed to the interferometer pedestal 17 provided at the end of the device base 7 in the + X direction, and the laser interferometers 29 to 31 in the -X direction of the device base 7. It is fixed to an interferometer pedestal 19 provided at the end, and both measure the position and rotation angle of the scan stage 8 in the X direction. If at least three laser interferometers are provided in the Y direction and two in the X direction, all the behaviors of the scan stage 8 can be measured. In this embodiment, many laser interferometers are used and their outputs are averaged. By doing so, the accuracy is being improved. A movable mirror (not shown) that reflects the laser beam from the laser interferometers 20 to 31 is fixed to the end of the scan stage 8 corresponding to each of the laser interferometers 20 to 31. .

Wafer X stage 10 and wafer Y stage
9, a linear encoder 59 that detects the relative position with respect to
C The relative position between the Y stage 9 and the scan stage 8 is detected.
Output linear encoder 58 and scan stage 8
From laser interferometers 20-31 to detect the position of
All position information about the stage is a stage system (not shown)
Position information from the laser interferometers 20-31 sent to your system
Position coordinate of the scan stage 8 (x_w , Y_w , Θ
_w ) Is detected. At this position coordinate, x _w Is X seat
Mark, y_w Is the Y coordinate, θ_w Represents the rotation angle in the two-dimensional plane
You In addition, the stage control system is based on these position information.
Through the linear motors 11, 12, 13, 14, 15 etc.
Then, the operation of the entire wafer stage is controlled.

Further, in FIG. 1, irradiation for projecting an image of a pinhole, a slit pattern or the like obliquely with respect to the optical axis AX toward the exposure surface of the wafer 6 near the image plane of the projection optical system 3. An oblique incidence type focus position detection system including an optical system 4 and a light receiving optical system 5 that receives a reflected light beam of the projected image on the surface of the wafer 6 through a slit is provided. The position of the surface of the wafer 6 in the Z direction is detected by the focus position detection systems 4 and 5, and based on the detection information, autofocus is performed so that the surface of the wafer 6 matches the image plane of the projection optical system 3. Be seen.

Next, the alignment optical system AL of this embodiment shown in FIG. 1 will be described. The alignment optical system AL of the present example measures the amount of positional deviation between the reticle mark and the wafer mark by an FIA (Field Image Alig).
nment) type alignment optical system. FIG. 4 is a configuration diagram showing the alignment optical system AL. In FIG. 4, the alignment optical system AL is composed of two systems of alignment observation systems AL1 and AL2, both of which can detect the amount of positional deviation in the X and Y directions. As shown in FIG. 1, two alignment observation systems AL1 and AL2 of the alignment optical system AL
The respective illumination light fluxes AB1 and AB2 emitted from
The different areas of the reticle 1 are irradiated through different areas of the dichroic mirror 51, and after passing through the reticle 1, the different areas of the surface of the wafer 6 are irradiated through the projection optical system 3. Wafer 6
Of the illumination luminous fluxes AB1 and AB2 radiated on the surface of the
Are reflected by the surface of the wafer 6, and the respective reflected light fluxes after passing through the projection optical system 3 again pass through different regions of the dichroic mirror 51 together with the respective reflected light fluxes reflected by the reticle 1 and are aligned. Alignment observation systems AL1 and AL of each optical system AL
Incident on 2.

In one of the alignment observation systems AL1, the alignment light AB1 emitted from the light source 32 passes through the condenser lens 33, the beam splitter 34, and the objective lens 35, and then passes through the dichroic mirror 51 shown in FIG. The reticle mark 47 formed on the wafer No. 1 and the wafer mark 45 formed on the wafer 6 are irradiated. Then, the alignment light reflected by the reticle mark 47 and the wafer mark 45 passes through the objective lens 35 of FIG. 4 again, returns to the beam splitter 34, and the beam splitter 3
The alignment light reflected by 4 passes through the imaging lens 36 and is received by the two-dimensional CCD image pickup device 37.

On the other hand, in the alignment observation system AL2,
The alignment light AB2 emitted from the light source 38 passes through the condenser lens 39, the beam splitter 40, and the objective lens 41, and then passes through the dichroic mirror 51 of FIG. 1 to transmit the reticle mark 48 and the wafer 6 formed on the reticle 1. The wafer mark 46 formed above is irradiated. Then, the alignment light reflected by the reticle mark 48 and the wafer mark 46 passes through the objective lens 41 of FIG. 4 again, is reflected by the beam splitter 40, and then passes through the imaging lens 42 to be transmitted by the two-dimensional CCD image pickup device 43. Received light.

FIG. 5 shows a two-dimensional CCD image pickup device 37 and 4.
3 shows a state in which the image captured in 3 is displayed on the CRT display 44. In FIG. 5, a two-dimensional CCD image pickup device 37
A set of images 47A and 45A of the reticle mark 47 and the wafer mark 45, respectively, and a respective image 48 of the reticle mark 48 and the wafer mark 46 taken by the two-dimensional CCD image sensor 43.
A set of images consisting of A and 46A is electrically combined,
It is displayed on one screen of the CRT display 44. By processing this image, the amount of positional deviation between the reticle marks 47, 48 and the corresponding wafer marks 45, 46 is detected.

FIG. 6 is a plan view of FIG. 1. As shown in FIG. 6, two alignment observation systems AL1 and AL2 are used.
Are arranged on the outer side of the hatched slit-shaped illumination area 49. Also, the reticle mark 4 formed on the end portion of the scanning exposure area 50 on the reticle 1 as a left-right pair.
7, 48 and conjugate images 45R of the wafer marks 45, 46,
Alignment observation system AL so that 46R can be observed
1, AL2 are arranged. Further, the alignment observation systems AL1 and AL2 of the two systems have variable intervals in the X direction so that they can cope with exposure shots of various sizes. Note that, in FIG. 1, for convenience of description, the reticle marks 47 and 48 are drawn so as to be on both sides of the illumination area 49 in the X direction, but the reticle marks 47 and 4 are illustrated.
The positional relationship between 8 and the illumination area 49 is actually as shown in FIG.

Next, an example of the positioning of the wafer stage and the exposure operation by the scanning exposure method in this example will be described. In FIG. 1, the wafer 6 carried onto the wafer X stage 10 by a wafer loader (not shown) is vacuum-sucked on the wafer X stage 10, and its alignment is performed with an accuracy of ± several μm or less by a rough alignment system (not shown). Done. Next, the wafer marks 45 and 46 attached to the shot area to be exposed on the wafer 6 first.
However, two alignment observation systems AL1 and AL2 in FIG.
Be positioned within the field of view of. At this time, the wafer 6 is positioned by the wafer X stage 10 and the wafer Y stage 9 based on the measurement values of the linear encoders 58 and 59,
At the same time, the reticle marks 47 and 48 are also positioned within the visual fields of the two alignment observation systems AL1 and AL2.

Next, the alignment observation system AL1 measures the relative positional deviation amount (Δx ₁ , Δy ₁ ) between the position of the reticle mark 47 and the position of the wafer mark 45, and the alignment observation system AL2 measures the reticle mark. The amount of relative positional deviation between the position of 48 and the position of the wafer mark 46 (Δx
₂ , Δy ₂ ) is measured. Δx ₁ and Δx ₂ represent the amount of positional deviation in the X direction, and Δy ₁ and Δy ₂ represent the amount of positional deviation in the Y direction. Then, the reticle stage 2 is finely moved so that all the values of the positional deviation amounts Δx ₁ , Δy ₁ , Δx ₂ , and Δy ₂ become 0 (or a predetermined reference value). With the above operation, the alignment is completed. However, regarding Δx ₁ and Δx ₂ , the projection optical system 3
Both cannot be set to 0 (or a reference value) at the same time unless the magnification of is changed. Therefore, for example, the alignment is performed by center distribution so that Δx ₁ = −Δx ₂ .
However, by actually adjusting the magnification of the projection optical system 3,
Δx ₁ and Δx ₂ may be set to 0 (or reference values) at the same time.

Further, the relative positional deviation amount between the reticle marks 47 and 48 and the corresponding wafer marks 45 and 46 is 0.
(Or a predetermined reference value), the initial position (x _r0 , y _r0 , θ _r0 ) of the reticle stage 2 is measured by the laser interferometer 52 on the reticle side, and at the same time, a plurality of laser interferometers 20 to 31 are operated. The initial position (x _w0 , y _w0 , θ _w0 ) of the scan stage 8 is measured by the average of the measured values.

Scanning exposure starts after the initial position is measured
Is done. During exposure, the wafer X stage 10 moves the wafer Y stage.
The wafer Y stay is fixed so that it does not move on the tage 9.
The 9 is fixed so that it does not move on the scan stage 8.
It Then, the position of the reticle stage 2 (x_r , Y_r ,
θ_r ) And the position of the scan stage 8 (x_w , Y_w , Θ
_w ), So that the relationship with
The Kuru stage 2 is servo-controlled. This place
Projection optical system 3 has a projection magnification β of ¼ and an inverted image
Is used to project.

X _r −x _r0 = −4 (x _w −x _w0 ) (1) y _r −y _r0 = −4 (y _w −y _w0 ) (2) θ _r −θ _r0 = θ _w −θ _w0 (3) After the exposure of a predetermined scanning exposure range on the reticle 1 is completed, the scan stage 8 is returned to the scanning start point, and two wafer marks (not shown) attached to the shot area to be exposed next are set. By the wafer X stage 10 and the wafer Y stage 9, two systems of alignment observation systems AL1 and A
Positioned within the field of view of L2. At the same time, the reticle marks 47 and 48 also have two alignment observation systems AL1 and A.
Positioned within the field of view of L2. Thereafter, the pattern of the reticle 1 is exposed in each shot area of the wafer 6 by repeating the same procedure as the above-described first exposure.

As described above, the scan stage 8 returns to the original position every time one scanning exposure is completed and the same scanning is repeated again. Therefore, this scan stage 8
Since the path of the plurality of laser interferometers 20 to 31 for monitoring the position of 1 is sufficient for the scanning length, the influence of air fluctuation during scanning exposure is extremely small. On the other hand, since the laser interferometer 52 that monitors the position of the reticle stage 2 is allowed to have coarse accuracy by the reciprocal of the reduction magnification of the projection optical system 3, the influence of air fluctuations does not pose a problem. In addition, 1
When one scanning exposure is completed, the scan stage 8 and the reticle stage 2 may be driven in opposite directions to perform the next scanning exposure, that is, the reciprocal scanning may be performed.

Further, in this embodiment, the projection optical system 3 having a reduction ratio of 1/4 is used, but the reduction ratio is not limited,
For example, in a projection optical system that has a reduction magnification of 1 / m and projects an inverted image, during exposure, the position of the reticle stage 2 (x _r , y _r , θ _r ) and the position of the scan stage 8 (x _w , The reticle stage 2 may be servo-controlled so that the relation of (y _w , θ _w ) always satisfies the following relational expression.

X _r −x _r0 = −m (x _w −x _w0 ) (4) y _r −y _r0 = −m (y _w −y _w0 ) (5) θ _r −θ _r0 = θ _w −θ _w0 (6)

Next, another embodiment of the scanning type exposure apparatus according to the present invention will be described with reference to FIGS. 7 and 8, parts corresponding to those in FIGS. 1 to 3 are designated by the same reference numerals, and detailed description thereof will be omitted. 7 and 8 are a perspective view and a plan view, respectively, showing the structure around the wafer stage of the step-and-scan type projection exposure apparatus of this example. In FIGS. Is held by vacuum suction on the scan stage 8A having a stroke in the Y direction that is β times the stroke in the Y direction of the reticle stage (not shown) (β is the projection magnification of the projection optical system used). Further, the scan stage 8A is held on a wafer X stage 10A which is movable in the X direction by a length corresponding to the diameter of the largest wafer to be exposed, and the wafer X stage 10A has a length corresponding to the diameter of the largest wafer. The wafer Y stage 9A is mounted on a wafer Y stage 9A that is movable only in the Y direction, and the wafer Y stage 9A is mounted on the apparatus base 7. In this case, the scan stage 8A uses the linear motors 11A and 12A to move the wafer X
The wafer X stage 1 is scanned with respect to the stage 10A.
0A is wafer Y stage 9A by linear motor 15A
The wafer Y stage 9A is scanned with respect to the apparatus base 7 by the linear motors 13A and 14A.

The relative position of the scan stage 8A with respect to the wafer X stage 10A is measured by two laser interferometers 20 to 30 arranged on each side of the scan stage 8A, two on each side. Further, these laser interferometers 20 are provided at the end of the scan stage 8A.
A movable mirror (not shown) that reflects the laser beam from each of .about.30 is fixed. The X coordinate of the wafer X stage 10A is measured by the linear encoder 59A, and the Y coordinate of the wafer Y stage 9A is measured by the linear encoder 58A. Other configurations are similar to those of the embodiment of FIG.

As described above, the wafer stage of this example is
Structurally, the scan stage 8A and the wafer X stage 10
A and wafer Y are mounted on the stage 9A. Therefore, at the time of scanning exposure, after each shot area of the wafer 6 is moved to the scan start position via the lower wafer X stage 10A and the wafer Y stage 9A, the wafer 6 is scanned by the scan stage 8A. The configuration of this example has an advantage that the path of the laser interferometers 20 to 30 can be shortened to the scanning length and the scan stage 8A can be downsized.

Although the present invention is applied to the scanning exposure apparatus of the projection type in the above-described embodiment, the present invention is also applied to the scanning exposure apparatus of the proximity method which does not use the projection optical system. it can. In addition, the linear encoder 58,
As the 59, not only an optical type encoder but also a magnetic type or electrostatic capacity type encoder can be used. Further, an interferometer may be used instead of the linear encoders 58 and 59. However, when a linear encoder other than the interferometer is used, the resolution is inferior to the case where the interferometer is used, but the configuration is simple and the cost is low, and the influence of air fluctuation is small. As described above, the present invention is not limited to the above-described embodiments, and various configurations can be taken without departing from the gist of the present invention.

[0044]

According to the scanning type exposure apparatus of the present invention, since the path of the interferometer can be shortened to the scanning length, the photosensitive substrate during the scanning exposure (without being affected by air fluctuations during the scanning exposure). There is an advantage that the position and speed of a wafer or the like) can be controlled with high accuracy. Further, by providing an alignment system, the relative positional deviation amount between the alignment mark formed on the mask (reticle, etc.) and the alignment mark formed on the photosensitive substrate is kept within a predetermined allowable range. When the scanning exposure is started after that, the scanning exposure is performed in a state where the mask and the photosensitive substrate are accurately aligned. Also,
Since it is not necessary to form the alignment mark over the entire scanning region, a somewhat large alignment mark is allowed. Therefore, even if the alignment mark (wafer mark) is damaged due to the processing during the process,
It has the advantage that it does not significantly affect the alignment accuracy.

Further, when the positioning substrate stage is placed on the scanning substrate stage, the positional relationship between the photosensitive substrate and the positioning substrate stage during the scanning exposure is unlikely to change, so that the alignment accuracy is improved. Is maintained with high accuracy. Further, when the scanning substrate stage is placed on the positioning substrate stage, there is an advantage that the scanning substrate stage can be downsized and high-speed scanning becomes easy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a scanning exposure apparatus according to the present invention.

FIG. 2 is a perspective view showing the wafer stage of FIG.

FIG. 3 is a plan view showing the wafer stage of FIG.

4 is a configuration diagram showing an alignment optical system AL of FIG.

5 is a diagram showing an image on a CRT display of a reticle mark and a wafer mark observed by the alignment optical system of FIG.

6 is a plan view showing a positional relationship between a reticle mark and a wafer mark with respect to a slit-shaped illumination region 49 when performing alignment by the alignment optical system of FIG.

FIG. 7 is a perspective view showing a structure around a wafer stage of another embodiment of the scanning exposure apparatus according to the present invention.

FIG. 8 is a plan view showing a wafer stage of the projection exposure apparatus of FIG.

[Explanation of symbols]

 1 Reticle 2 Reticle Stage 3 Projection Optical System 6 Wafer 7 Device Base 8,8A Scan Stage 9,9A Wafer Y Stage 10,10A Wafer X Stage 20-31 Laser Interferometer 32,38 Alignment Light Source 37,43 Two-dimensional CCD Image sensor 45,46 Wafer mark 47,48 Reticle mark 52 Laser interferometer on the reticle 58,59 Linear encoder AL Alignment optical system AL1, AL2 Alignment observation system

Claims (4)

[Claims] 1. A pattern of the mask by illuminating a mask on which a transfer pattern is formed and scanning the photosensitive substrate in the second direction in synchronization with scanning of the mask in the first direction. In a scanning exposure apparatus that sequentially exposes each exposure area on the substrate, and a two-dimensional positioning substrate stage that positions the substrate on a two-dimensional plane parallel to the exposure surface of the substrate. Position measuring means for measuring a specific position, a scanning substrate stage for scanning the substrate in the second direction during scanning exposure, and an interference for measuring the position of the scanning substrate stage in the second direction. And a scanning type exposure apparatus. 2. An alignment system for detecting a relative positional deviation amount between the alignment mark formed on the mask and the alignment mark formed on the substrate is provided, and the alignment system is provided via the positioning substrate stage. 2. The scanning type exposure apparatus according to claim 1, wherein the amount of positional deviation detected by the alignment system is driven within a predetermined allowable range when the substrate is positioned by the above method. 3. The scanning exposure apparatus according to claim 1, wherein the positioning substrate stage is mounted on the scanning substrate stage. 4. The scanning exposure apparatus according to claim 1, wherein the scanning substrate stage is placed on the positioning substrate stage.