JP5398185B2 - Projection optical system, exposure apparatus, and device manufacturing method - Google Patents

Description

  The present invention relates to a projection optical system, an exposure apparatus provided with the projection optical system, and a device manufacturing method for manufacturing a device using the exposure apparatus.

  A flat panel display (hereinafter referred to as FPD) is manufactured by a photolithography process. In the photolithography process, an original pattern is projected onto a substrate coated with a photosensitive agent (generally a glass plate in FPD manufacturing) by a projection optical system to expose the substrate. In an exposure apparatus for exposing a substrate, it is important to reduce overlay errors. The overlay error is caused by, for example, alignment error, aberration (distortion), and magnification error. Among these, the alignment error can be reduced by adjusting the relative position between the original and the substrate with high accuracy, but the aberration and the magnification error cannot be corrected by the alignment.

  The magnification error can be caused by expansion and contraction of a substrate such as a glass plate due to factors such as heat generated by the production process. Due to the shrinkage of the substrate, the overlay accuracy after the second process is deteriorated. Further, different expansion and contraction may occur in the scanning direction in scanning exposure and in a direction perpendicular thereto. In order to reduce errors due to the expansion and contraction of the substrate, it is conceivable to perform exposure by giving a relative speed difference between the original and the substrate for the expansion and contraction in the scanning direction. For expansion and contraction in the direction perpendicular to the scanning direction, a method of arranging a flat plate glass in the vicinity of the original plate or the substrate and bending the parallel plate glass to refract light and finely adjust the magnification is considered. It has been.

Patent Documents 1 and 2 disclose a magnification correction method. Patent Document 1 discloses that two lenses that are rotationally symmetric with respect to the optical axis are arranged close to each other in the projection optical system and one of them is driven in the optical axis direction. Patent Document 2 discloses that at least one of at least two toric optical members that are rotationally asymmetric with respect to the optical axis of the projection optical system is rotated with respect to the optical axis or moved in the optical axis direction. .
Japanese Patent Laid-Open No. 62-35620 Japanese Patent Registration No. 3341269

  However, in order to correct the magnification in the scanning direction of the substrate, a method that gives a relative speed difference between the original and the substrate causes a specific asymmetric distortion aberration when the good image area is arcuate. sell. In order to correct this, it is necessary to drive another optical member for correcting aberration. This complicates the mechanical mechanism and generates drive aberration residue.

  Further, in order to correct the magnification in the direction orthogonal to the scanning direction of the substrate, it is difficult to accurately bend the parallel flat glass into the target shape with the method of bending the parallel flat glass, and nonlinear aberration error components are generated. . Moreover, in order to cope with the recent increase in size of the substrate, the parallel flat glass must also be increased in size, which may cause an error.

  In the methods described in Patent Documents 1 and 2, magnification correction with respect to the scanning direction and magnification correction with respect to a direction orthogonal thereto cannot be performed individually.

  The present invention has been made in view of the above background, and an object thereof is to make it possible to individually perform magnification correction in two orthogonal directions, for example.

The first aspect of the present invention, the first concave reflecting surface in the optical path to the image plane from the object surface, a convex reflective surface, there the second concave reflecting surface in turn, an image of an object which definitive said object plane to said image plane It relates to a projection optical system for projecting the exposure apparatus includes a first refractive optical unit and the second refractive optical unit, wherein the first refractive optical unit comprises two or more bus is a second direction perpendicular to the first direction of having a cylindrical surface, the second refractive optical unit comprises two or more cylindrical surface generatrix is the first direction, the first refractive optical unit of the projection optical system in the first direction The projection magnification is adjustable, and the second refractive optical unit is configured to adjust the projection magnification of the projection optical system in the second direction.

  A second aspect of the present invention relates to an exposure apparatus, and the exposure apparatus includes the projection optical system described above, and exposes the substrate by projecting an original pattern onto the substrate by the projection optical system.

  A third aspect of the present invention relates to a device manufacturing method, wherein the device manufacturing method includes a step of exposing a substrate coated with a photoagent by an exposure apparatus according to claim 7, and a step of developing the photosensitizer. Including.

  In the present invention, for example, magnification correction in two orthogonal directions can be performed individually.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a view showing a schematic configuration of an exposure apparatus EX according to a preferred embodiment of the present invention. FIG. 2 is a diagram schematically showing the configuration of the projection optical system PO of the exposure apparatus EX shown in FIG. In FIG. 2, a bending mirror (mirror with zero power) MD for bending the optical axis AX of the projection optical system PO is omitted. The folding mirror MD may be considered to bend the optical path. For example, the bending mirror MD bends the optical axis AX 90 degrees by the reflecting surface MA between the object surface O on which the original M is disposed and the first concave reflecting surface M1, and the second concave reflecting surface M3 and the substrate P are disposed. The optical axis AX can be arranged to be bent 90 degrees by the reflecting surface MB with respect to the image plane I.

  In an actual configuration, it is advantageous that the folding mirror MD is provided to reduce the size of the projection optical system PO, but the folding mirror MD is not essential. In this specification, in order to describe a spatial direction, an XYZ coordinate system in which a Z direction is defined in parallel to the optical axis AX in a state where the bending mirror MD is removed is used.

  The exposure apparatus EX is suitable for manufacturing a device having a large area such as a flat panel display such as a liquid crystal display, but can also be applied to manufacturing a semiconductor device such as an LSI or other devices.

  The exposure apparatus EX includes an illumination optical system IL that illuminates an original (which may also be referred to as a mask or a reticle) M, an original stage MST that holds the original M, a projection optical system PO, and a substrate (for example, a plate such as a glass plate) P. A holding substrate stage PST may be provided. The original M is disposed on the object plane O of the projection optical system PO, and the substrate P is disposed on the image plane I of the projection optical system PO.

  The exposure apparatus EX is typically configured as a scanning exposure apparatus. In the exposure apparatus EX, the original stage MST and the substrate stage are scanned so that the original M and the substrate P are scanned while illuminating the original M with the light formed in a strip shape (for example, arc shape, rectangular slit shape) by the illumination optical system IL. PST is driven to scan. As a result, the pattern of the original M is transferred to the photosensitive agent on the substrate P.

  The projection optical system PO has a good image area at a position shifted from the optical axis AX, and the good image area is used to project the pattern of the original M onto the substrate P. The projection optical system PO has a first refractive optical unit A, a first concave reflective surface M1, a convex reflective surface M2, a second concave reflective surface M3, and a second refractive optical unit B on the optical path from the object plane O to the image plane I. Are arranged in order. Between the first refractive optical unit A and the first concave reflecting surface M1, the reflecting surface MA of the bending mirror MD can be disposed. Between the second concave reflecting surface M3 and the second refractive optical unit B, the reflecting surface MB of the folding mirror MD can be disposed.

  The first refractive optical unit A and the second refractive optical unit B are not limited to the above positions, and can be disposed in an optical path from the object plane O to the image plane I. The first concave reflective surface M1 and the second concave reflective surface M3 are typically reflective surfaces having the same center of curvature. The first concave reflecting surface M1 has a positive power, the convex reflecting surface M2 has a negative power, and the second concave reflecting surface has a positive power.

  The first refractive optical unit A and the second refractive optical unit B are optical units that correct the projection magnification of the projection optical system PO. More specifically, the first refractive optical unit A is arranged so that the projection magnification of the projection optical system PO in the first direction ((X direction in a state in which the bending mirror MD is removed when it is provided)) can be adjusted. In addition, the second refractive optical unit A can adjust the projection magnification of the projection optical system PO in the second direction orthogonal to the first direction (the Y direction when the folding mirror MD is removed). Is arranged.

  The first refractive optical unit A and the second refractive optical unit B each have two or more cylindrical surfaces. The first refractive optical unit A is driven by the first actuator AA so that the projection magnification in the first direction (the X direction when the folding mirror MD is removed is the X direction) is the first target projection magnification. sell. The second refractive optical unit B is driven by the second actuator BA so that the projection magnification in the second direction (the Y direction when the folding mirror MD is removed is the Y direction) is the second target projection magnification. sell. Here, the first target projection magnification and the second target projection magnification are determined by, for example, detecting the position of the alignment mark already formed on the substrate P by a measurement unit such as an alignment scope (not shown). Can do.

  The first refractive optical unit A typically can have two cylindrical surfaces. As combinations of the characteristics (power) of the two cylindrical surfaces, convex and convex, concave and concave, convex and concave are conceivable. Here, in order to make the change in the projection magnification with respect to the change in the focus position insensitive, it is preferable that the projection optical system PO has a telecentric configuration. Therefore, the combination of the characteristics (power) of the two cylindrical surfaces is preferably a combination of convex and concave. The cylindrical surface buses included in the first refractive optical unit A are typically parallel to each other.

  The second refractive optical unit B also typically has two cylindrical surfaces, and the combination of characteristics (power) is preferably a combination of convex and concave. Further, the cylindrical buses included in the second refractive optical unit B are typically parallel to each other.

  The buses of the two or more cylindrical surfaces included in the first refractive optical unit A are in a third direction (Y that is perpendicular to the optical axis AX of the projection optical system PO) (in a state where the bending mirror MD is removed). Direction). The buses of two or more cylindrical surfaces included in the second refracting optical unit B are the first one orthogonal to the optical axis AX of the projection optical system PO and the third direction (in the state where the bending mirror MD is removed). Parallel to four directions (X direction).

  3 and 4 are diagrams illustrating a configuration example of the first refractive optical unit A. FIG. Here, FIG. 3 is a cross-sectional view of the first refractive optical unit A cut along the XZ plane, and FIG. 4 is a cross-sectional view of the first refractive optical unit A cut along the YZ plane. The first refractive optical unit A includes a refractive optical element A11 disposed on the object plane O side and a refractive optical element A12 disposed on the image plane I side. The refractive optical element A11 has a convex cylindrical surface CA11 on the image plane I side, and has a convex power as a whole. The refractive optical element A12 has a concave cylindrical surface CA12 on the object plane O side, and has a concave power as a whole. The first refractive optical unit A can have more cylindrical surfaces. That is, the first refractive optical unit A can have two or more cylindrical surfaces. The buses of the two or more cylindrical surfaces CA11 and CA12 of the first refractive optical unit A are in a third direction (in a state where the bending mirror MD is removed, in a state where the bending mirror MD is removed) perpendicular to the optical axis AX of the projection optical system PO ( Parallel to the Y direction). In order to correct the projection magnification in the first direction of the projection optical system PO (the X direction when the folding mirror MD is removed), at least one of the two or more cylindrical surfaces CA11 and CA12 is required. One is driven in the direction of the optical axis AX by the first actuator AA.

  5 and 6 are diagrams illustrating a configuration example of the second refractive optical unit B. FIG. Here, FIG. 5 is a cross-sectional view of the second refractive optical unit B cut along the XZ plane, and FIG. 6 is a cross-sectional view of the second refractive optical unit B cut along the YZ plane. The second refractive optical unit B includes a refractive optical element B11 disposed on the object plane O side and a refractive optical element B12 disposed on the image plane I side. The refractive optical element B11 has a concave cylindrical surface CB11 on the image plane I side, and has a concave power as a whole. The refractive optical element B12 has a convex cylindrical surface CB12 on the object plane O side, and has a convex power as a whole. The second refractive optical unit B can have more cylindrical surfaces. That is, the second refractive optical unit B can have two or more cylindrical surfaces. The buses of the two or more cylindrical surfaces CB11 and CB12 of the second refractive optical unit B are in a fourth direction (in a state where the bending mirror MD is removed, in a state where it is removed) perpendicular to the optical axis AX of the projection optical system PO ( X direction). In order to correct the projection magnification in the second direction of the projection optical system PO (the Y direction when the bending mirror MD is removed), at least one of the two or more cylindrical surfaces CB11 and CB12 is required. One is driven in the direction of the optical axis AX by the second actuator AB.

  According to this embodiment, it is possible to individually correct the projection magnification in two orthogonal directions, for example, the scanning direction and the direction orthogonal thereto. Thereby, for example, the projection magnification in the scanning direction and the direction orthogonal to the scanning direction can be individually corrected according to the pattern already formed on the substrate, and the overlay accuracy of the image after the second process can be improved. .

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described. Matters not specifically mentioned here can follow the first embodiment.

  7 and 8 are diagrams illustrating a configuration example of the first refractive optical unit A in the second embodiment. Here, FIG. 7 is a cross-sectional view of the first refractive optical unit A cut along the XZ plane, and FIG. 8 is a cross-sectional view of the first refractive optical unit A cut along the YZ plane.

  The first refractive optical unit A includes a refractive optical element A21 disposed on the object plane O side and a refractive optical element A22 disposed on the image plane I side. The refractive optical element A21 has a convex cylindrical surface CA11 as a first surface which is a surface on the image plane I side, and a curved surface (spherical surface or aspheric surface) S11 as a second surface which is a surface on the object plane O side. It has a convex power as a whole. The refractive optical element A22 has a concave cylindrical surface CA12 on the object plane O side, and has a concave power as a whole. The first refractive optical unit A can have more cylindrical surfaces. That is, the first refractive optical unit A can have two or more cylindrical surfaces. The buses of the two or more cylindrical surfaces CA11 and CA12 of the first refractive optical unit A are in a third direction (in a state where the bending mirror MD is removed, in a state where the bending mirror MD is removed) perpendicular to the optical axis AX of the projection optical system PO ( Parallel to the Y direction). In order to correct the projection magnification in the first direction of the projection optical system PO (the X direction when the folding mirror MD is removed), at least one of the two or more cylindrical surfaces CA11 and CA12 is required. One is driven in the direction of the optical axis AX by the first actuator AA.

  9 and 10 are diagrams illustrating a configuration example of the second refractive optical unit B. FIG. Here, FIG. 9 is a cross-sectional view of the second refractive optical unit B cut along the XZ plane, and FIG. 10 is a cross-sectional view of the second refractive optical unit B cut along the YZ plane. The second refractive optical unit B includes a refractive optical element B21 disposed on the object plane O side and a refractive optical element B22 disposed on the image plane I side. The refractive optical element B21 has a concave cylindrical surface CB11 on the image plane I side, and has a concave power as a whole. The refractive optical element B22 has a convex cylindrical surface CB12 as a first surface that is a surface on the object plane O side, and a curved surface (spherical surface or aspheric surface) S22 as a second surface that is a surface on the image plane I side. It has a convex power as a whole. The second refractive optical unit B can have more cylindrical surfaces. That is, the second refractive optical unit B can have two or more cylindrical surfaces. The buses of the two or more cylindrical surfaces CB11 and CB12 of the second refractive optical unit B are in a fourth direction (in a state where the bending mirror MD is removed, in a state where it is removed) perpendicular to the optical axis AX of the projection optical system PO ( X direction). In order to correct the projection magnification in the second direction of the projection optical system PO (the Y direction when the bending mirror MD is removed), at least one of the two or more cylindrical surfaces CB11 and CB12 is used. One is driven in the direction of the optical axis AX by the second actuator AB.

  In the above example, both the first refractive optical unit A and the second refractive optical unit B have a curved surface on the back surface of the cylindrical surface, but one of the first refractive optical unit A and the second refractive optical unit B is cylindrical. You may have a curved surface in the back surface.

  According to this embodiment, a small-sized and high-performance projection optical system can be configured by making the back surface of the cylindrical surface a curved surface (spherical surface or aspherical surface). In particular, by forming the curved surface into an aspherical shape, it is possible to expand a belt-like (for example, arc-shaped) good image area while maintaining off-axis optical performance (astigmatism, curvature of field) performance. If a spherical or aspherical lens is disposed in addition to the first and second refractive optical units to achieve a desired off-axis optical performance (astigmatism, curvature of field), the refractive optics in the projection optical system The number of elements increases. Therefore, if the exposure wavelength is broadened to increase the exposure throughput, an increase in chromatic aberration due to an increase in refractive optical elements in the projection optical system cannot be ignored. Therefore, as described above, it is preferable to provide a curved surface on the back surface of the cylindrical surface for magnification correction, and this makes it possible to configure a compact and high-performance projection optical system.

[Others]
In the first and second embodiments, when the overall imaging magnification of the projection optical system PO is 1 (equal magnification), the first concave reflecting surface M1 and the second concave reflecting surface M3 have the same radius of curvature. It is comprised so that it may have. When the imaging magnification of the projection optical system PO is set to other than 1, the radius of curvature of the first concave reflecting surface M1 and the radius of curvature of the second concave reflecting surface M3 can be determined according to the imaging magnification.

[Device manufacturing method]
A device manufacturing method according to a preferred embodiment of the present invention is suitable for manufacturing, for example, a liquid crystal device and a semiconductor device. A pattern of an original is formed on the photosensitive agent on the substrate coated with the photosensitive agent using the above exposure apparatus. A step of transferring and a step of developing the photosensitive agent can be included. Furthermore, the device is manufactured through other known processes (etching, resist peeling, dicing, bonding, packaging, and the like).

It is a figure which shows schematic structure of the exposure apparatus of suitable embodiment of this invention. It is a figure which shows typically the structure of the projection optical system of the exposure apparatus shown in FIG. It is sectional drawing of the XZ plane of the 1st refractive optical unit of 1st Embodiment. It is sectional drawing of the YZ plane of the 1st refractive optical unit of 1st Embodiment. It is sectional drawing of the XZ plane of the 2nd refractive optical unit of 1st Embodiment. It is sectional drawing of the YZ plane of the 2nd refractive optical unit of 1st Embodiment. It is sectional drawing of the XZ plane of the 1st refractive optical unit of 2nd Embodiment. It is sectional drawing of the YZ plane of the 1st refractive optical unit of 2nd Embodiment. It is sectional drawing of the XZ plane of the 2nd refractive optical unit of 2nd Embodiment. It is sectional drawing of the YZ plane of the 2nd refractive optical unit of 2nd Embodiment.

Explanation of symbols

IL: illumination optical system PO: projection optical system M: original MST: original stage P: substrate PST: substrate stage M1: first concave reflecting surface M2: convex reflecting surface M3: second concave reflecting surface A: first refractive optical unit B: First refractive optical unit O: Object plane I: Image plane

Claims (10)

The first concave reflecting surface in the optical path to the image plane from the object surface, a convex reflective surface, there the second concave reflecting surface in turn, a projection optical system for projecting an image of an object definitive on the object plane to said image plane,
A first refractive optical unit and a second refractive optical unit;
The first refractive optical unit has two or more cylindrical surfaces whose generating lines are in a second direction orthogonal to the first direction,
The second refractive optical unit has two or more cylindrical surfaces whose buses are in the first direction ,
The first refractive optical unit is adjustable the projection magnification of the projection optical system in the first direction,
The second refractive optical unit is configured to be capable of adjusting a projection magnification of the projection optical system in the second direction.
A projection optical system characterized by that. At least one of the first refractive optical unit and the second refractive optical unit includes a refractive optical element having a first surface and a second surface, the first surface is a cylindrical surface, and the second surface is a curved surface. is there,
The projection optical system according to claim 1. A first actuator that drives the first refractive optical unit so that a projection magnification in the first direction becomes a first target projection magnification;
A second actuator for driving the second refractive optical unit so that the projection magnification in the second direction becomes a second target projection magnification;
The projection optical system according to claim 1, wherein the projection optical system is a projection optical system. The first refractive optical unit is located on an optical path between the object surface and the first concave reflecting surface, the second refractive optical unit, the light between the second concave reflecting surface and the image surface some on the road,
The projection optical system according to claim 1, wherein the projection optical system is a projection optical system. The projection optical system according to claim 2, wherein the second surface is an aspherical surface. The first refractive optical unit has a refractive optical element in which the object side surface is an aspherical surface and the image surface side surface is a cylindrical surface;
6. The second refractive optical unit includes a refractive optical element in which the object-side surface is a cylindrical surface and the image-side surface is an aspherical surface. The projection optical system described in 1. An exposure apparatus comprising the projection optical system according to any one of claims 1 to 6, wherein the projection optical system projects an original pattern onto a substrate to expose the substrate. An exposure apparatus that exposes the substrate while scanning the original and the substrate in the scanning direction,
A projection optical system according to any one of claims 1 to 6 , comprising:
Wherein the first direction Ri the scanning direction der,
The second direction is Ri perpendicular der in the scanning direction,
The projection magnification of the projection optical system in the scanning direction can be adjusted by changing the interval between two or more cylindrical surfaces of the first refractive optical unit,
An exposure apparatus, wherein a projection magnification of the projection optical system in a direction perpendicular to the scanning direction can be adjusted by changing an interval between two or more cylindrical surfaces of the second refractive optical unit. Changing the interval between the two or more cylindrical surfaces of the first refractive optical unit so that the projection magnification in the scanning direction becomes the first target projection magnification;
According to claim 8, characterized in that the projection magnification in a direction perpendicular to the scanning direction so that the second target projection magnification, changing the distance between the two or more cylindrical surface of the second refractive optical unit Exposure equipment. A device manufacturing method comprising:
A step of exposing a substrate coated with a photosensitive agent by the exposure apparatus according to any one of claims 7 to 9 ,
Developing the photosensitizer;
A device manufacturing method comprising:

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