JPH1064806A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the occurrence of a focusing error caused by the difference between the image forming magnifications of two surface position detecting optical systems. SOLUTION: An aligner is provided with first and second projection optical systems PO1 and PO2 which project a first light pattern upon first and second substrates 1 and 2 from oblique directions and first and second image forming optical systems 4-6 and 9 which form the images of first and second light patterns at first and second image forming magnifications. The device is also provided with control means 8 and 10 which maintain the interval between the two substrates nearly constantly based on the positional information of the images of the first and second light patterns and a correcting means 9P1 which corrects the interval error between the two substrates which occurs due to the difference between the two image forming magnifications.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an exposure apparatus, and more particularly to a method of focusing two large substrates on an exposure projection optical system in the exposure apparatus.

[0002]

2. Description of the Related Art A pattern formed on a large mask is collectively transferred onto a large plate by performing exposure while relatively moving a mask and a plate with respect to a projection optical system for exposure at the same magnification. A scanning type exposure apparatus is known. In such a scanning type exposure apparatus, the mask and the plate can be focused on the projection optical system for exposure by keeping the distance between the mask and the plate constant. Japanese Patent Application Laid-Open No. 7-2 filed by the present applicant
Japanese Patent No. 21012 discloses that the distance between the mask and the plate is kept constant by keeping the distance between the projected slit image formed on the sensor via the mask and the projected slit image formed on the sensor via the plate constant. An exposure apparatus having a focusing system for holding constant is disclosed.

[0003]

In the conventional focusing system disclosed in the above publication, a mask surface for detecting a position of a mask surface based on a position of a projection slit image formed on a sensor via a mask. A position detecting optical system is provided, and a plate surface position detecting optical system for detecting the position of the plate surface based on the position of the projection slit image formed on the sensor via the plate. Therefore, when the imaging magnification in the mask surface position detection optical system and the imaging magnification in the plate surface position detection optical system are different from each other due to a manufacturing error or the like, the distance between the two projection slit images formed on the sensor is changed. Even if the distance is kept constant, the distance between the mask and the plate cannot be kept constant. As a result, in the conventional exposure apparatus, there is a disadvantage that an error in the interval between the mask and the plate, that is, a focusing error occurs due to a difference in imaging magnification between the two surface position detecting optical systems.

The present invention has been made in view of the above-mentioned problems, and provides an exposure apparatus capable of avoiding occurrence of a focusing error due to a difference in imaging magnification between two surface position detecting optical systems. The purpose is to do.

[0005]

In order to solve the above-mentioned problems, in the present invention, a pattern formed on a first substrate is exposed to a light-sensitive second image through a projection optical system for exposure of approximately equal magnification.
In an exposure apparatus for transferring onto a substrate, a first projection optical system for projecting a first light pattern of a predetermined shape on the first substrate from an oblique direction, and condensing light from the first light pattern Then, a first imaging optical system for forming an image of the first light pattern at a first imaging magnification and a second light pattern having a predetermined shape on the second substrate are inclined. A second projection optical system for projecting light from the second direction, and a second projection optical system for condensing light from the second light pattern so as to be substantially equal to the first imaging magnification.
A second imaging optical system for forming an image of the second light pattern at an imaging magnification of; and receiving the images of the first and second light patterns, the first light pattern Light receiving means for outputting position information of the image of the second light pattern and position information of the image of the second light pattern; position information of the image of the first light pattern and position information of the image of the second light pattern; Control means for keeping the distance between the first substrate and the second substrate substantially constant, based on a difference between the first imaging magnification and the second imaging magnification. And a correcting means for correcting an error in the distance between the first substrate and the second substrate.

According to a preferred aspect of the present invention, the correcting means corrects the difference between the first image forming magnification and the second image forming magnification by using the first image forming optical system and the first image forming optical system. Magnification correction means provided in at least one of the second imaging optical systems, wherein the control means is configured to control an image of the first light pattern and an image of the second light pattern. By keeping the distance substantially constant, the distance between the first substrate and the second substrate is controlled to be substantially constant. In this case, at least one of the first imaging optical system and the second imaging optical system is movable along the optical axis with the first subsystem fixed along the optical axis. A second subsystem, wherein the magnification correction means moves the second subsystem by a predetermined distance along the optical axis, thereby providing the first imaging magnification and the second imaging magnification. It is preferable to correct the difference. Further, according to another preferred aspect of the present invention, the correction unit is configured to determine a position of an image of the first light pattern based on a difference between the first imaging magnification and the second imaging magnification. Position information correcting means for correcting position information of at least one of information and position information of an image of the second light pattern, wherein the control means corrects the position information via the position information correcting means. The distance between the first substrate and the second substrate is controlled to be substantially constant based on the position information of the image of the first light pattern and the position information of the image of the second light pattern.

[0007]

FIG. 2 is a diagram for explaining the principle of surface position detection according to the present invention. In FIG. 2, a light beam R11 incident on the substrate surface 1 at an incident angle θ via a projection optical system (not shown) forms a slit image at a position PAF1 on the substrate surface 1. The reflected light beam R12 from the slit image formed on the substrate surface 1 becomes a light beam R13 via the telecentric imaging optical system 5 on the substrate surface 1 side, and re-forms the slit image at the position PPS1 on the image sensor 7. Here, assuming that the imaging magnification of the imaging optical system 5 is β, the position PPS1 on the image sensor 7 is replaced by the position PAF on the substrate surface 1.
A projection slit image having a magnification β of the slit image formed in 1 is formed.

When the substrate surface 1 moves downward by δ as shown by a broken line in the figure, the light beam R11 incident on the substrate surface 1 at an incident angle θ via the projection optical system is moved to a position PAF on the substrate surface 1.
1 ', the reflected light beam R12' from the substrate surface 1 becomes a light beam R13 'via the imaging optical system 5, and is slit on the image sensor 7 at a position PPS1' separated from the position PPS1 by a distance Δ. Recreate the image.

The movement amount δ of the substrate surface 1 and the image sensor 7
The relationship shown in the following equation (1) is established between the above and the movement amount Δ of the slit image formation position.

Δ = Δ / (2β sin θ) (1) As described above, in the surface position detection optical system shown in FIG. 2, the movement amount Δ of the slit image formation position on the image sensor 7
, The amount of movement δ of the substrate surface 1 as the detection surface, and thus the surface position of the substrate surface 1 can be detected.

FIG. 3 is a view for explaining a focusing error which occurs in the prior art due to a difference in imaging magnification between two surface position detecting optical systems. In FIG. 3, a substrate surface 1 such as a mask surface is connected via a projection optical system (not shown).
Incident on the substrate surface 1 at an incident angle θ forms a slit image at a position PAF1 on the substrate surface 1. The reflected light R12 from the slit image formed on the substrate surface 1 passes through the reflecting mirror 4, the imaging optical system 5, and the right-angle reflecting prism 6 to form a light R13.
And a slit image is re-formed at the position PPS1 on the image sensor 7. That is, at the position PPS1 on the image sensor 7, a projection slit image having the magnification β1 (imaging magnification of the imaging optical system 5) of the slit image formed at the position PAF1 on the substrate surface 1 is formed.

When the substrate surface 1 moves upward by δ1 as shown by a broken line in the figure, the light beam R11 incident on the substrate surface 1 at an incident angle θ via the projection optical system is moved to a position PAF on the substrate surface 1.
1 ', the reflected light beam R12' from the substrate surface 1 becomes a light beam R13 'via the reflecting mirror 4, the imaging optical system 5, and the right-angle reflecting prism 6, and becomes upward from the position PPS1 on the image sensor 7 in the figure. Position PPS moved by Δ1
Re-form the slit image at 1 '.

On the other hand, the light ray R21 incident on the substrate surface 2 such as a plate surface at an incident angle θ via another projection optical system (not shown) forms a slit image at a position PAF2 on the substrate surface 2. The reflected light beam R22 from the slit image formed on the substrate surface 2 becomes a light beam R23 via the reflecting mirror 4 ', the imaging optical system 5' and the right-angle reflecting prism 6, and the slit image is formed at the position PPS2 on the image sensor 7. Reshape.
That is, at the position PPS2 on the image sensor 7, a projection slit image having a magnification β2 (imaging magnification of the imaging optical system 5 ′) of the slit image formed at the position PAF2 on the substrate surface 2 is formed.

When the substrate surface 2 moves downward by δ2 as shown by the broken line in the figure, the light beam R21 incident on the substrate surface 2 at the incident angle θ via the projection optical system is moved to the position PAF on the substrate surface 2.
2 ', the reflected light beam R22' from the substrate surface 2 becomes a light beam R23 'via a reflecting mirror 4', an imaging optical system 5 'and a right-angle reflecting prism 6, and is reflected from the position PPS2 on the image sensor 7. Position P moved by Δ2 in the middle and lower direction
The PS2 'slit image is re-formed.

As described above, when the substrate surface 1 and the substrate surface 2 are respectively located at positions shown by solid lines in the drawing, the interval between the two slit images formed on the image sensor 7 is Δ12. However, when the substrate surface 1 moves upward by δ1 and the substrate surface 2 moves downward by δ2 as shown by a broken line in the drawing, the interval between the two slit images formed on the image sensor 7 increases to Δ12 ′. . The change amount δΔ of the interval between the two slit images on the image sensor 7 is represented by the following equation (2).

Δ = Δ12′−Δ12 = 2 (β1δ1-β2δ2) sinθ (2)

The difference between the imaging magnification β1 of the imaging optical system 5 and the imaging magnification β2 of the imaging optical system 5 ', that is, a magnification error dβ
Using (dβ = β2−β1), the above equation (2) can be modified to the following equation (3).

ΔΔ = 2 β1δ1- (β1 + dβ) δ2｝ sinθ = 2 ｛β1 (δ1-δ2) -dβδ2｝ sinθ (3)

Referring to the above equation (3), the condition for δΔ = 0 is that the relationship shown in the following equation (4) is established.

Δ1−δ2 = dβδ2 / β1 (4)

In the above equation (4), the magnification error dβ =
If 0, δ1−δ2 = 0. That is, if there is no difference in imaging magnification between the two imaging optical systems 5 and 5 ',
Distance Δ between two slit images on image sensor 7
By keeping 12 constant, the distance between the two substrate surfaces 1 and 2 can be kept constant. However, 2
When there is a difference in the imaging magnification between the two imaging optical systems 5 and 5 ′, even if the distance Δ12 between the two slit images on the image sensor 7 is kept constant, the two substrate surfaces 1 and 2
An error of dβδ2 / β1 occurs in the interval between.

In view of the above, the present invention includes a correcting means for correcting an error in the interval between the two substrates caused by the difference between the two imaging magnifications. The correction means is, for example, 2
Magnification correction means provided in one of the imaging optical systems to correct the difference between the two imaging magnifications, and by keeping the distance between the images of two light patterns (for example, slit images) substantially constant, The distance between the two substrates is controlled to be substantially constant.
More specifically, one of the imaging optical systems includes a first subsystem fixed along the optical axis and a second subsystem movable along the optical axis. Then, the magnification correction means moves the second subsystem by a predetermined distance along the optical axis,
The difference between the two imaging magnifications is corrected. The correction means is position information correction means for correcting the position information of at least one of the light pattern images based on, for example, a difference between the two imaging magnifications. , The distance between the two substrates is controlled to be substantially constant.

The present invention can also be applied to a scanning type exposure apparatus which transfers a pattern while relatively moving two large substrates along a predetermined direction with respect to an exposure projection optical system. In this case, the interval between the two substrates can be always kept substantially constant during the scanning exposure. As mentioned above,
In the present invention, by correcting the magnification and correcting the image position information,
An occurrence of an error in the interval between the two substrates due to the difference between the two imaging magnifications is suppressed. As a result, exposure can be performed with the distance between the two substrates kept substantially constant, and defocusing of the transfer pattern can be substantially avoided.

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a view schematically showing a configuration of a main part of an exposure apparatus according to an embodiment of the present invention. In FIG. 1, the second
The X axis is parallel to the plane of FIG. 1 in the exposure plane of the plate 2, and the Z axis is perpendicular to the plane of FIG. 1 in the exposure plane of the plate 2. Each axis is set.

In the exposure apparatus of the present embodiment, the mask 1, which is the first substrate on which the pattern to be transferred is formed, is illuminated by an illumination optical system (not shown). The light transmitted through the mask 1 is
Through the exposure optical system 3 for exposure at the same magnification, the second photosensitive
A mask pattern image is formed on a plate 2 serving as a substrate.
In this way, the mask 1 and the plate 2 are integrally moved relative to the exposure projection optical system 3 along the Z-axis direction, so that the pattern formed over the entire pattern area of the mask 1 is It is possible to collectively transfer the entire exposure area. The plate 2 is Y
It is supported on a plate stage 10 that can move along the direction.

As described above, the exposure projection optical system 3
It is a 1 × optical system. Therefore, when the mask 1 moves by ΔY in the + Y direction, the image forming position of the mask pattern image formed via the projection optical system 3 for exposure is ΔY in the + Y direction.
Just move. That is, in the exposure apparatus using the projection optical system for exposure at the same magnification, by performing exposure while keeping the distance between the mask 1 and the plate 2 constant, it is possible to avoid the defocus of the transfer pattern.

Therefore, the exposure apparatus of the present embodiment uses the mask 1
A focusing system (autofocus system) AF for keeping the distance between the lens and the plate 2 constant. In the focusing AF, light emitted from the light source 11 illuminates the slit plate SL1 via the lens 12. The slit plate SL1 has a slit-shaped opening extending perpendicularly to the plane of FIG. The light beam R11 passing through the opening of the slit plate SL1 passes through the lens 13 through the mask 1
Obliquely incident on the pattern surface (lower surface in the figure) at an incident angle θ. Thus, the position PAF1 on the pattern surface of the mask 1
, An image of the opening of the slit plate SL1, that is, a slit image is formed. Thus, the light source 11, the lens 12,
The slit plate SL1 and the lens 13 constitute a projection optical system PO1 for projecting a light pattern of a predetermined shape such as a slit image on the pattern surface of the mask 1 from an oblique direction.

The reflected light beam R12 from the slit image formed on the pattern surface of the mask 1 is reflected downward by the reflecting mirror 4 in the figure, and then is reflected by the imaging optical system 5 which is telecentric toward the object side (mask 1 side). Incident. The light beam R12 passing through the imaging optical system 5 enters the right-angle reflecting prism 6 via the aperture stop AP1 positioned at the rear focal position of the imaging optical system 5. The light reflected to the right side in the figure by the right-angle reflecting prism 6 becomes a light ray R13, and the position PP
A slit image is re-formed at S1. That is, at the position PPS1 on the image sensor 7, a projection slit image (light) of magnification βm (imaging magnification of the imaging optical system 5 on the mask side) of the slit image formed at the position PAF1 on the pattern surface of the mask 1 is formed. An image of the pattern) is formed.

On the other hand, the light emitted from the light source 11 'illuminates the slit plate SL2 via the lens 12'. The slit plate SL2 has a slit-shaped opening extending perpendicularly to the plane of FIG. The light passing through the opening of the slit plate SL2 obliquely enters the exposure surface (upper surface in the drawing) of the plate 2 at an incident angle θ via the lens 13 ′. Thus, an image of the opening of the slit plate SL2, that is, a slit image is formed at the position PAF2 on the exposure surface of the plate 2. As described above, the light source 11 ′, the lens 12 ′, the slit plate SL 2 and the lens 13 ′ are provided with the projection optical system PO 2 for projecting a light pattern having a predetermined shape such as a slit image on the exposure surface of the plate 2 from an oblique direction. Is composed.

The reflected light beam R22 from the slit image formed on the exposure surface of the plate 2 is reflected upward by a reflecting mirror 4 'in the figure, and then is telecentrically formed on the object side (plate 2 side). Incident on. The imaging optical system 9 is
It is composed of a subsystem 9P1 movable along the optical axis and a subsystem 9P2 fixed along the optical axis. The light beam R22 passing through the imaging optical system 9 enters the right-angle reflecting prism 6 via the aperture stop AP2 positioned at the rear focal position of the imaging optical system 9. The light reflected to the right side in the figure by the right-angle reflecting prism 6 becomes a ray R23, and re-forms a slit image at the position PPS2 on the image sensor 7. That is, at the position PPS2 on the image sensor 7, a projected slit image (light) of the magnification βp (imaging magnification of the plate-side imaging optical system 9) of the slit image formed at the position PAF2 on the exposure surface of the plate 2 An image of the pattern) is formed.

The image sensor 7 supplies to the control system 8 information on the interval between the positions PPS1 and PPS2 where two slit images are formed. The control system 8 appropriately drives the plate stage 10 along the Y-axis direction via a drive system (not shown) based on the position information from the image sensor 7,
Distance L between pattern surface of mask 1 and exposure surface of plate 2
Is controlled to be substantially constant during exposure.

As described above, in the present embodiment, the image forming optical system 9 on the plate side is a subsystem 9P that can move along the optical axis.
1 and a subsystem 9P2 fixed along the optical axis. Therefore, even if there is a magnification error due to, for example, a manufacturing error between the imaging magnification βm of the imaging optical system 5 on the mask side and the imaging magnification βp of the imaging optical system 9 on the plate side, the subsystem 9P1 Along the optical axis (along the Y-axis direction)
By appropriately moving, the magnification error between the two imaging optical systems can be corrected. Then, in a state where the magnification error between the two imaging optical systems is corrected, the image sensor 7
By keeping the interval between the two upper slit images constant, the interval L between the pattern surface of the mask 1 and the exposure surface of the plate 2 can be always kept constant. as a result,
High-precision exposure without defocusing of the transfer pattern becomes possible.

In the above-described embodiment, the position of the slit image formed on the image sensor 7 based on the reflected light on the upper surface of the mask 1 (the back surface opposite to the pattern surface) in the figure is determined. The position of the slit image formed on the image sensor 7 based on the reflected light on the lower surface of the plate 2 (the back surface opposite to the exposure surface) in FIG. It is desirable to define the reflection deflection direction of the right-angle reflection prism 6 so as to be lower than the PPS 2 in the figure.

In the above-described embodiment, the mask 1 with the imaging magnification βm of the imaging optical system 9 on the mask side and the imaging magnification βp of the imaging optical system 9 on the plate side are matched. The distance L between the pattern surface and the exposure surface of the plate 2 is always kept constant. That is, the interval L is always kept constant while the magnification error between the two imaging optical systems is corrected. However, it is also possible to always keep the distance L between the pattern surface of the mask 1 and the exposure surface of the plate 2 constant while the magnification error of the two imaging optical systems remains. Hereinafter, a description will be given of a method of keeping the interval L constant by correcting the image formation position information without correcting the magnification error.

First, the moving amount Δ1 of the slit image on the image sensor 7 when the mask 1 is moved along the Y direction by a predetermined distance δ1 is detected. Then, based on the relationship between the movement amount δ1 of the mask 1 and the movement amount Δ1 of the slit image on the image sensor 7, the image forming magnification βm of the image forming optical system 5 on the mask side is obtained according to the above equation (1). Similarly, the moving amount Δ2 of the slit image on the image sensor 7 when the plate 2 is moved along the Y direction by a predetermined distance δ2
Is detected. Then, the imaging magnification βp of the plate-side imaging optical system 9 is obtained from the relationship between the movement amount δ2 of the plate 2 and the movement amount Δ2 of the slit image on the image sensor 7 according to the above-described equation (1).

When the imaging magnification βm of the imaging optical system 5 is different from the imaging magnification βp of the imaging optical system 9, for example, the actual movement amount Δ2 of the slit image on the image sensor 7 is multiplied by a correction coefficient. Thus, the correction movement amount Δ2 ′ in the ideal state where the imaging magnification βp of the imaging optical system 9 matches the imaging magnification βm of the imaging optical system 5 is obtained. Thus, in the control system 8, the actual movement amount Δ1 of the slit image accompanying the movement of the mask 1
And correction amount Δ of slit image due to movement of plate 2
By controlling so that 2 ′ coincides, the mask 1
The distance L between the pattern surface and the exposure surface of the plate 2 can always be kept constant.

In the above-described embodiment, the mask pattern is collectively transferred onto the plate by performing exposure while relatively moving the large mask and the large plate with respect to the projection optical system for exposure at the same magnification. The present invention is applied to a scanning type exposure apparatus. However, the present invention can also be applied to a non-scanning type exposure apparatus having a 1 × exposure optical system. In the above-described embodiment, a slit image extending in a predetermined direction is formed on each substrate surface. However, it is apparent that a light pattern having a predetermined shape may be generally projected from an oblique direction.

[0034]

As described above, according to the present invention, by correcting the magnification and correcting the image position information, the occurrence of an error in the interval between the two substrates due to the difference between the two imaging magnifications is suppressed. Exposure can be performed in a state in which the distance between them is kept substantially constant, and defocus of the transfer pattern can be substantially avoided.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a configuration of a main part of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of surface position detection according to the present invention.

FIG. 3 is a diagram illustrating a focusing error generated due to a difference in imaging magnification between two surface position detection optical systems in the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mask 2 Plate 3 Exposure projection optical system 4, 4 'reflective mirror 5, 5', 9 Imaging optical system 6 Right angle reflection prism 7 Image sensor 8 Control system 9P1, 9P2 Subsystem 10 Plate stage 11, 11 'Light source 12 , 13, 12 ', 13' Lens SL1, SL2 Slit plate PO1, PO2 Projection optical system AP1, AP2 Aperture stop L Distance between two substrates

Claims (5)

[Claims] An exposure apparatus for transferring a pattern formed on a first substrate onto a photosensitive second substrate via a projection optical system for exposure at approximately the same magnification, wherein the first substrate has a predetermined shape. A first projection optical system for projecting a first light pattern from an oblique direction, and condensing light from the first light pattern to form the first light under a first imaging magnification. A first imaging optical system for forming an image of a pattern, a second projection optical system for projecting a second light pattern of a predetermined shape on the second substrate from an oblique direction, and the second light The light from the pattern is condensed to form the second image under a second image magnification substantially equal to the first image magnification.
A second imaging optical system for forming an image of the light pattern; receiving the images of the first and second light patterns; positional information of the image of the first light pattern; and the second light A light receiving unit for outputting position information of an image of a pattern; and a first substrate and the second substrate based on position information of an image of the first light pattern and position information of an image of the second light pattern. Control means for keeping the distance between the two substrates substantially constant; and the first substrate and the second substrate generated due to a difference between the first imaging magnification and the second imaging magnification. An exposure apparatus, comprising: a correction unit configured to correct an error in the interval of (d). 2. The image forming apparatus according to claim 1, wherein the correction unit corrects the difference between the first imaging magnification and the second imaging magnification.
Magnification correction means provided in at least one of the imaging optical system and the second imaging optical system, wherein the control means controls the image of the first light pattern and the second
2. The exposure apparatus according to claim 1, wherein the distance between the first substrate and the second substrate is controlled to be substantially constant by keeping the distance between the image of the light pattern and the image of the light pattern substantially constant. 3. An image forming optical system according to claim 1, wherein at least one of said first image forming optical system and said second image forming optical system has a first subsystem fixed along an optical axis and a second optical system fixed along an optical axis. A movable second subsystem, wherein the magnification correction means moves the second subsystem by a predetermined distance along the optical axis, thereby providing the first imaging magnification and the second imaging power. The exposure apparatus according to claim 2, wherein a difference from an image magnification is corrected. 4. The image forming apparatus according to claim 1, wherein the correction unit is configured to determine position information of an image of the first light pattern and the second light pattern based on a difference between the first imaging magnification and the second imaging magnification. Position information correction means for correcting at least one of the position information of the image of the image of the first light pattern of the image of the first light pattern corrected through the position information correction means 2. The exposure apparatus according to claim 1, wherein an interval between the first substrate and the second substrate is controlled to be substantially constant based on position information and position information of an image of the second light pattern. 3. . 5. The scanning exposure device according to claim 1, wherein the control unit performs a pattern transfer of the first substrate while relatively moving the first substrate and the second substrate along a predetermined direction with respect to the projection optical system for exposure. 5. The exposure apparatus according to claim 1, wherein a distance between the first substrate and the second substrate is always kept substantially constant.