Projection optical system and exposure device

Abstract

To provide a projection optical system and an exposure device capable of forming a sharp optical image with less light quantity loss.SOLUTION: Projecting optical systems 1, 1', 1", 20, 40 include: in order from an object side, first optical systems 2, 21 that are telecentric on both object side and image side; a first lens array 22 having two dimensionally arranged first lens elements 30; second lens arrays 23, 41 having two-dimensionally arranged second lens elements 31, 50; and a second optical system 24 that is telecentric on both object side and image side. A two-dimensional arrangement of the first lens array 22 and the two-dimensional arrangement of the second lens arrays 23, 41 coincide with each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a projection optical system and an exposure apparatus, and more particularly to a projection optical system using a spatial modulator and an exposure apparatus using this projection optical system. [Background technology]

[0002] A double-telecentric optical system is an optical system that is telecentric on both the object side and the image side. In a double-telecentric optical system, the size of the image does not change even if a positional shift in the optical axis direction occurs on either the object side or the image side. Therefore, double-telecentric optical systems are used in the projection optical system of exposure equipment.

[0003] A digital micromirror device (hereinafter, referred to as "DMD") is known as a spatial modulator. Patent Document 1 discloses a projection optical system and an exposure apparatus using a DMD. In this projection optical system, the DMD is located on the object plane, and an object is located on the image plane. The projection optical system has, in order from the object side, a DMD, a lens group, an optical system, and an additional lens. The optical system has a microlens array and a grating. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2004-514280 Summary of the Invention [Problem to be solved by the invention]

[0005] In the projection optical system disclosed in Patent Document 1, divergent light is emitted from the microlens array. If the spread of the divergent light is large, some of the light reaches the outside of the additional lens. The light that reaches the outside of the additional lens is reflected by the inner surface of the lens barrel. Stray light is generated from some of the reflected light. When the stray light reaches the image plane, flare occurs. As a result, the image becomes unclear due to the flare, or the contrast of the image decreases. A grating is arranged to suppress the occurrence of flare, but the grating causes a loss of light quantity.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a projection optical system and an exposure apparatus that are capable of forming a sharp optical image with little loss of light. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the objective, an embodiment of the projection optical system of the present invention includes, in order from the object side, a first optical system that is telecentric on both the object side and the image side, a first lens array having first lens elements arranged two-dimensionally, a second lens array having second lens elements arranged two-dimensionally, and a second optical system that is telecentric on both the object side and the image side, wherein the two-dimensional arrangement of the first lens array coincides with the two-dimensional arrangement of the second lens array.

[0008] In order to achieve the above-mentioned object, according to an aspect of the projection optical system of the present invention, in the second lens array, marginal rays are emitted parallel to the optical axis of the projection optical system, and a composite pupil image formed by the first optical system, the first lens array, and the second lens array is formed on the image plane of the second optical system by the second optical system.

[0009] In order to achieve the above-mentioned object, according to an embodiment of the projection optical system of the present invention, in the second lens array, the chief ray is emitted parallel to the optical axis of the projection optical system, and the second optical system forms an image of a composite object plane formed by the first optical system, the first lens array, and the second lens array on the image plane of the second optical system.

[0010] In order to achieve the above object, in an aspect of the projection optical system of the present invention, the magnification of the first optical system ranges from 1x to 10x.

[0011] In order to achieve the above object, in an aspect of the projection optical system of the present invention, the magnification of the second optical system is in the range of 0.05 to 7 times.

[0012] In order to achieve the above object, in one aspect of the projection optical system of the present invention, a spatial modulator having a plurality of spatial modulation elements is disposed on an object plane, and the following conditional expression (1) is satisfied. 2×(NA1×D1) / (P1×β1×β1)<0.71 (1) Where: NA1 is the numerical aperture of the first optical system, D1 is the air-equivalent length between the first and second lens arrays, β1 is the magnification of the first optical system, P1 is the pitch between two adjacent spatial light modulation elements, It is. In order to achieve the above object, in an aspect of the projection optical system of the present invention, a spatial modulator is placed on an object plane, and the spatial modulator is illuminated with light having a wavelength of 190 nm or more and 450 nm or less.

[0013] In order to achieve the above object, an embodiment of the projection optical system of the present invention satisfies the following conditional expression (2). (f1-D1) / f1<0.71 (2) Where: f1 is the focal length of the first lens element, D1 is the air-equivalent length between the first and second lens arrays, It is.

[0014] In order to achieve the above object, in an aspect of the projection optical system of the present invention, a spatial modulator is placed on an object plane, and the spatial modulator is illuminated with light having a wavelength of 190 nm or more and 450 nm or less.

[0015] In order to achieve the above-mentioned objective, an embodiment of an exposure apparatus of the present invention includes a light source, an illumination optical system that collects light from the light source, a spatial modulator having spatial modulation elements arranged two-dimensionally and illuminated by the illumination optical system, the above-mentioned projection optical system that is positioned between the spatial modulator and an object, and a stage that holds the object located on the image plane of the projection optical system. Effect of the Invention

[0016] According to the projection optical system and exposure apparatus of the present invention, it is possible to provide a projection optical system and exposure apparatus that can form a sharp optical image with little loss of light. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing the projection optical system of this embodiment. [Diagram 2] FIG. 2 is a diagram showing a spatial modulator. [Diagram 3] FIG. 3 is a diagram showing a lens array. [Figure 4] FIG. 4 is a schematic diagram showing the projection optical system of the first embodiment. [Diagram 5] FIG. 5 is a schematic diagram showing the projection optical system of the first embodiment. [Figure 6] FIG. 6 is a diagram showing a lens element and a light ray passing through the second optical system. [Figure 7] FIG. 7 is a schematic diagram showing a projection optical system according to the second embodiment. [Figure 8] FIG. 8 is a schematic diagram showing a projection optical system according to the second embodiment. [Figure 9] FIG. 9 is a diagram showing a lens element and a light ray passing through the second optical system. [Figure 10] FIG. 10 is a diagram showing an exposure apparatus of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The projection optical system of this embodiment includes, in order from the object side, a first optical system that is telecentric on both the object side and the image side, a first lens array having first lens elements arranged two-dimensionally, a second lens array having second lens elements arranged two-dimensionally, and a second optical system that is telecentric on both the object side and the image side, and the two-dimensional arrangement of the first lens array coincides with the two-dimensional arrangement of the second lens array.

[0019] Fig. 1 is a schematic diagram showing the projection optical system of this embodiment. As shown in Fig. 1, the projection optical system 1 includes, in order from the object side, a first optical system 2, a first lens array 3, a second lens array 4, and a second optical system 5. On the object plane 6, for example, a spatial modulator can be arranged.

[0020] 2 is a diagram showing a spatial modulator. The spatial modulator 10 has a plurality of spatial modulation elements 10a. The spatial modulation elements 10a are arranged two-dimensionally. When the spatial modulation elements 10a are square and each side has a length L, the distance between two adjacent spatial modulation elements 10a is also L. The spatial modulation elements 10a change the reflection direction of light, or switch between transmitting and blocking light.

[0021] A DMD can be used as the spatial modulator 10. In the DMD, a micromirror is used for the spatial modulation element 10a. The micromirror changes the reflection direction of light. A liquid crystal spatial modulator can be used as the spatial modulator 10. In the liquid crystal spatial modulator, a liquid crystal is used for the spatial modulation element 10a. The liquid crystal switches between transmitting and blocking light.

[0022] In the spatial modulator 10, the state of the spatial modulation elements 10a can be set to an on state or an off state. For example, the on state is a state in which light is incident on the projection optical system 1, and the off state is a state in which light is not incident on the projection optical system 1. By changing the state of each of the spatial modulation elements 10a, various patterns can be generated.

[0023] Returning to Fig. 1, the first optical system 2 is disposed on the image side of the object surface 6. The first optical system 2 is an optical system that is telecentric on both the object side and the image side.

[0024] A first lens array 3 is disposed on the image side of the first optical system 2. The first lens array 3 has first lens elements arranged two-dimensionally. A second lens array 4 is disposed on the image side of the first lens array 3. The second lens array 4 has second lens elements arranged two-dimensionally.

[0025] Fig. 3 is a diagram showing a lens array. The lens array 11 has a plurality of lens elements 11a. The plurality of lens elements 11a are arranged two-dimensionally. The lens element 11a has a lens surface 11b. The surface opposite to the lens surface 11b is a flat surface. In Fig. 3, the lens surface 11b is a convex surface. However, the lens surface 11b may be a concave surface.

[0026] In the first lens array 3, lens element 11a corresponds to the first lens element, and in the second lens array 4, lens element 11a corresponds to the second lens element.

[0027] Returning to Fig. 1, in the projection optical system 1, the object plane 6 is conjugate with the lens surface of the first lens array 3 by the first optical system 2. Therefore, a conjugate image 6' of the object plane 6 is formed on the lens surface of the first lens array 3. For ease of viewing, the conjugate image 6' is drawn at a position away from the lens surface of the first lens array 3 in Fig. 1.

[0028] The second optical system 5 is disposed on the image side of the second lens array 4. The second optical system 5 is an optical system that is telecentric on both the object side and the image side.

[0029] Two lens arrays are used in the projection optical system 1. The two-dimensional arrangement of the first lens array 3 coincides with the two-dimensional arrangement of the second lens array 4. The interval between two adjacent lens elements 11a is the same in the first lens array and the second lens array.

[0030] The light emitted from the first lens element is incident on the second lens element. Therefore, compared to a case where there is only one lens array, in the projection optical system 1, it is possible to allow as much of the light emitted from the first lens element as possible to be incident on the second optical system 5. As a result, there is little loss of light, and a sharp optical image can be formed.

[0031] Various patterns can be generated by the spatial modulator 10. When the spatial modulator 10 is placed on the object plane 6, the pattern generated by the spatial modulator 10 is projected onto the image plane 7. The image plane 7 is the image plane of the second optical system 5 or the image plane of the projection optical system 1. By positioning an object, for example, a photosensitive material, on the image plane 7, various patterns can be projected onto the photosensitive material.

[0032] The object side of the first optical system 2 is telecentric. Therefore, even if the spatial modulator 10 moves slightly in the optical axis direction relative to the object plane 6, the imaging magnification does not change. In addition, the image side of the second optical system 5 is telecentric. Therefore, even if the object moves slightly in the optical axis direction relative to the image plane 7, the imaging magnification does not change.

[0033] In this way, the imaging magnification does not change in the projection optical system 1. Therefore, even if the spatial modulator 10 is shifted in the optical axis direction or the object is shifted in the optical axis direction, the size of the pattern projected onto the image plane 7 can be kept constant.

[0034] As shown in Fig. 2, the shape of the spatial light modulating element 10a is a square. Therefore, as shown in Fig. 3, the shape of the lens element 11a is also a square. The distance between two adjacent lens elements 11a is the same as the distance between two adjacent spatial light modulating elements 10a. Since the distance between the two spatial light modulating elements 10a is L, the distance between the two lens elements 11a is also L. The distance L represents the pitch.

[0035] In FIG. 3, the shape of lens element 11a is square. When light passes through the entire surface of lens element 11a, the shape of the lens surface is square. When the light incident on each of spatial light modulation elements 10a is made circular, the light does not pass through the entire surface of lens element 11a. In this case, the shape of the lens surface of lens element 11a can be made circular. Since the shape of the light beam is circular, the shape of the pupil is also circular.

[0036] In the projection optical system 1, the two-dimensional arrangement of the first lens array and the two-dimensional arrangement of the second lens array match, so the interval between two adjacent lens elements 11a is the same in the first lens array and the second lens array.

[0037] The projection optical system of this embodiment will be described in more detail below. In the description, the projection optical system of the first embodiment and the projection optical system of the second embodiment will be used.

[0038] In the projection optical system of the first embodiment, marginal rays are emitted from the second lens array parallel to the optical axis of the projection optical system, and a composite pupil image formed by the first optical system, the first lens array, and the second lens array is formed on the image plane of the second optical system by the second optical system.

[0039] Fig. 4 is a schematic diagram showing the projection optical system of the first embodiment. The same components as in Fig. 1 are given the same numbers and their explanations are omitted. In Fig. 4, marginal rays emitted from on-axis object points are shown by solid lines, and chief rays emitted from off-axis object points are shown by dotted lines.

[0040] The marginal ray MR is light emitted from an on-axis object point OB1. The chief ray PR is light emitted from an off-axis object point OB2. The marginal ray MR and the chief ray PR enter the first optical system 2 and then exit from the first lens array 3.

[0041] In the projection optical system 1', a second lens array 4' is disposed on the image side of the first lens array 3. By appropriately setting the refractive power and position of the second lens array 4', the marginal rays MR can be emitted from the second lens array 4' parallel to the optical axis AX.

[0042] After entering the second optical system 5, the marginal rays MR reach the image plane 7. The second optical system 5 is a double-telecentric optical system, and the marginal rays MR are parallel to the optical axis AX on the object side. Therefore, the marginal rays MR exit the second optical system 5 parallel to the optical axis AX. At the image plane 7, the marginal rays MR are parallel to the optical axis AX.

[0043] Furthermore, the chief ray PR intersects with the optical axis AX on the image plane 7. The second optical system 5 forms on the image plane 7 a composite pupil image formed by the first optical system 2, the first lens array 3, and the second lens array 4'.

[0044] In the projection optical system of the first embodiment, each of the first lens elements has a planar object side surface and a curved image side surface with a convex surface facing the image side, and each of the second lens elements has a curved object side surface with a convex surface facing the object side and a planar image side surface.

[0045] Fig. 5 is a schematic diagram showing the projection optical system of the first embodiment. Fig. 5(a) is a schematic diagram from the object plane to the lens array. Fig. 5(b) is a schematic diagram from the lens array to the image plane. The same components as in Fig. 1 are given the same numbers and their explanations are omitted.

[0046] The projection optical system 20 has a first optical system 21, a first lens array 22, a second lens array 23, and a second optical system 24.

[0047] The first optical system 21 has a lens 21a and a lens 21b. In Fig. 5(a), the first optical system 21 is formed of two lenses. However, the first optical system 21 may be formed of two or more lenses.

[0048] The first optical system 21 is telecentric on both the object side and the image side. If the focal length of the lens 21a and the focal length of the lens 21b are f1, the lens 21a and the lens 21b are disposed at an interval of 2×f1.

[0049] An object plane 6 is located at the object-side focal point of lens 21a. A conjugate image 6' is formed at the image-side focal point of lens 21b. In the projection optical system 20, the object plane 6 is conjugate with the lens surface of the first lens array 22 by the first optical system 21. Therefore, the lens surface of the first lens array 22 is located at the image-side focal point of lens 21b.

[0050] In the first lens array 22, each of the first lens elements has a flat object side surface 22a and a curved image side surface 22b that is convex toward the image side. Thus, each of the first lens elements has positive refractive power.

[0051] In the second lens array 23, each of the second lens elements has a curved object side surface 23a that faces the object side and a flat image side surface 23b. Thus, each of the second lens elements has positive refractive power.

[0052] The second optical system 24 has a lens 24a and a lens 24b. In Fig. 5(b), the second optical system 24 is formed of two lenses. However, the second optical system 24 may be formed of two or more lenses.

[0053] The second optical system 24 is telecentric on both the object side and the image side. When the focal length of the lens 24a and the focal length of the lens 24b are f2, the lenses 24a and 24b are disposed at an interval of 2×f2.

[0054] In the projection optical system 20, a second lens array 23 is disposed between the first lens array 22 and the second optical system 24. From the second lens array 23, marginal rays MR are emitted parallel to the optical axis AX.

[0055] The marginal rays MR enter the second optical system 24 and then reach the image plane 7. The second optical system 24 is a double-telecentric optical system, and the marginal rays MR are parallel to the optical axis AX on the object side. Therefore, the marginal rays MR exit the second optical system 24 parallel to the optical axis AX. At the image plane 7, the marginal rays MR are parallel to the optical axis AX.

[0056] The chief ray PR intersects with the optical axis AX on the image plane 7. The second optical system 24 forms a synthetic pupil image on the image plane 7 by the first optical system 21, the first lens array 22, and the second lens array 23.

[0057] Fig. 6 is a diagram showing light rays passing through the lens element and the second optical system. Fig. 6(a) is a diagram showing light rays in a first arrangement example. Fig. 6(b) is a diagram showing light rays in a second arrangement example. Fig. 6(c) is a diagram showing light rays in a third arrangement example. The same components as Fig. 5(b) are given the same numbers and will not be described.

[0058] In the first arrangement example, the lens surface is illustrated, whereas in the second and third arrangement examples, the lens surface is omitted and the lenses are depicted as straight lines.

[0059] (First arrangement example) The first lens element 30 is a lens element of the first lens array 22. The first lens element 30 has a flat object side surface 30a and a curved image side surface 30b that is convex toward the image side. Since the object surface 6 is conjugate with the lens surface of the first lens array 22, a conjugate image 6' is located on the lens surface of the first lens element 30.

[0060] The second lens element 31 is a lens element of the second lens array 23. The second lens element 31 has a curved object side surface 31a with a convex surface facing the object side, and a flat image side surface 31b. If the focal length of the second lens element 31 is fa2, the second lens element 31 is disposed so that the object side focal point coincides with the conjugate image 6'. Therefore, the marginal ray MR is collimated by the second lens element 31. As a result, in the second lens array 23, the marginal ray MR is emitted parallel to the optical axis AX.

[0061] Chief ray PR emitted from first lens element 30 intersects with optical axis AX on the image side of first lens element 30. On the object side of the intersection, a composite optical system is formed by first optical system 21 and first lens array 22. Therefore, an exit pupil 32 of the composite optical system is formed at the intersection.

[0062] When the focal length of the first lens element 30 is fa1, in the first arrangement example, the relationship between fa1 and fa2 is fa1 = fa2 or fa1 ≒ fa2. Therefore, the second lens array 23 is located at the position of the exit pupil 32. In FIG. 5(a), the lens surface of the second lens element 31, that is, the lens surface of the second lens array 23, is arranged at the position of the exit pupil 32.

[0063] The second optical system 24 is arranged such that the object-side focal point of the lens 24a coincides with the exit pupil 32. Therefore, on the image plane 7 of the second optical system 24, the chief ray PR intersects the optical axis AX. As a result, an image of the exit pupil 32 is formed on the image plane 7 by the second optical system 24.

[0064] (Second arrangement example) Also in the second arrangement example, the second lens element 31 is arranged such that the object-side focal point coincides with the conjugate image 6'. Therefore, the peripheral ray MR is collimated by the second lens element 31. As a result, in the second lens array 23, the peripheral ray MR exits parallel to the optical axis AX.

[0065] The chief ray PR emitted from the first lens element 30 intersects the optical axis AX on the image side of the first lens element 30. A combined optical system is formed by the first optical system 21 and the first lens array 22 on the object side of the intersection position. Therefore, the exit pupil 32 of the combined optical system is formed at the intersection position.

[0066] In the second arrangement example, the relationship between fa1 and fa2 is fa1 < fa2. In this case, the exit pupil 32 is located near the object side of the second lens element 31. Therefore, the second lens element 31, that is, the second lens array 23, is located near the exit pupil 32.

[0067] A composite optical system formed by the second lens array 23 and the second optical system 24 is located on the image side of the exit pupil 32. The second optical system 24 is disposed so that the object-side focal point of the composite optical system coincides with the exit pupil 32. Therefore, at the image plane 7 of the second optical system 24, the chief ray PR intersects with the optical axis AX. As a result, an image of the exit pupil 32 is formed on the image plane 7 by the second optical system 24.

[0068] (Third arrangement example) In the third arrangement example, the second lens element 31 is also arranged so that the object-side focal point coincides with the conjugate image 6'. Therefore, the marginal ray MR is collimated by the second lens element 31. As a result, the marginal ray MR is emitted from the second lens array 23 in parallel with the optical axis AX.

[0069] Chief ray PR emitted from first lens element 30 intersects with optical axis AX on the image side of first lens element 30. On the object side of the intersection, a composite optical system is formed by first optical system 21 and first lens array 22. Therefore, an exit pupil 32 of the composite optical system is formed at the intersection.

[0070] However, the second lens element 31 is located between the first lens element 30 and the exit pupil 32. Therefore, the exit pupil 32 is projected by the second lens array 23. An exit pupil 33 is formed at the projection position.

[0071] In the third arrangement example, the relationship between fa1 and fa2 is fa1>fa2. In this case, the exit pupil 32 or the exit pupil 33 is located near the image side of the second lens element 31. Therefore, the second lens element 31, i.e., the second lens array 23, is located near the exit pupil 32 or the exit pupil 33.

[0072] The second optical system 24 is disposed such that the object-side focal point of the lens 24a coincides with the exit pupil 33. Therefore, the chief ray PR intersects with the optical axis AX on the image plane 7 of the second optical system 24. As a result, an image of the exit pupil 32 is formed on the image plane 7 by the second optical system 24.

[0073] In the projection optical system of the first embodiment, marginal rays MR are emitted parallel to the optical axis AX from the second lens array 23. Marginal rays MR are also emitted parallel to the optical axis AX from the second optical system 24. At the image plane 7, marginal rays MR are parallel to the optical axis AX.

[0074] Furthermore, at the image plane 7, the chief ray PR intersects with the optical axis AX. The first optical system 21, the first lens array 22, and the second lens array 23 form a composite optical system. The pupil formed by the composite optical system is projected onto the image plane 7 by the second optical system 24. As a result, an image of the pupil is formed on the image plane 7.

[0075] In the projection optical system of the second embodiment, the chief ray is emitted from the second lens array parallel to the optical axis of the projection optical system, and the second optical system forms an image of a composite object plane formed by the second optical system, the first lens array, and the second lens array on the image plane of the second optical system.

[0076] Fig. 7 is a schematic diagram showing a projection optical system of the second embodiment. The same components as in Fig. 1 are given the same numbers and their explanations are omitted. In Fig. 7 as well, the marginal rays emitted from an on-axis object point are shown by solid lines, and the chief rays emitted from an off-axis object point are shown by dotted lines.

[0077] The marginal ray MR is light emitted from an on-axis object point OB1. The chief ray PR is light emitted from an off-axis object point OB2. The marginal ray MR and the chief ray PR enter the first optical system 2 and then exit from the first lens array 3.

[0078] In the projection optical system 1", a second lens array 4" is disposed on the image side of the first lens array 3. By appropriately setting the refractive power and position of the second lens array 4", it is possible to emit chief rays PR from the second lens array 4" parallel to the optical axis AX.

[0079] After entering the second optical system 5, the chief ray PR reaches the image plane 7. The second optical system 5 is a double-telecentric optical system, and the chief ray PR is parallel to the optical axis AX on the object side. Therefore, the chief ray PR exits the second optical system 5 parallel to the optical axis AX. At the image plane 7, the chief ray PR is parallel to the optical axis AX.

[0080] Furthermore, at the image plane 7, the marginal rays MR intersect with the optical axis AX. By the second optical system 5, an image of a composite object plane formed by the first optical system 2, the first lens array 3, and the second lens array 4″ is formed on the image plane 7.

[0081] In the projection optical system of the second embodiment, each of the first lens elements has a planar object side surface and a curved image side surface with a convex surface facing the image side, and each of the second lens elements has a curved object side surface with a concave surface facing the object side and a planar image side surface.

[0082] Fig. 8 is a schematic diagram showing a projection optical system of the second embodiment. Fig. 8(a) is a schematic diagram from the object plane to the lens array. Fig. 8(b) is a schematic diagram from the lens array to the image plane. The same components as Fig. 5(a) and (b) are given the same numbers and will not be described.

[0083] The projection optical system 40 includes a first optical system 21, a first lens array 22, a second lens array 41, and a second optical system 24.

[0084] In the second lens array 41, each of the second lens elements has a curved object side surface 41a with a concave surface facing the object side, and a flat image side surface 41b, and therefore each of the second lens elements has negative refractive power.

[0085] In the projection optical system 40, a second lens array 41 is disposed between the first lens array 22 and the second optical system 24. A chief ray PR is emitted from the second lens array 41 in parallel to the optical axis AX.

[0086] The chief ray PR enters the second optical system 24 and then reaches the image plane 7. The second optical system 24 is a double-telecentric optical system, and the chief ray PR is parallel to the optical axis AX on the object side. Therefore, the chief ray PR exits the second optical system 24 parallel to the optical axis AX. At the image plane 7, the chief ray PR is parallel to the optical axis AX.

[0087] The marginal rays MR intersect with the optical axis AX at the image plane 7. By the second optical system 24, an image of the object plane combined by the first optical system 21, the first lens array 22, and the second lens array 41 is formed on the image plane 7.

[0088] 9 is a diagram showing a lens element and a light beam passing through the second optical system. The same components as those in FIG. 6(a) are given the same reference numbers and the description thereof will be omitted.

[0089] The second lens element 50 is a lens element of the second lens array 41. The second lens element 50 has a curved object-side surface 50a whose concave surface faces the object side, and a flat image-side surface 50b.

[0090] If the focal length of the second lens element 50 is fa3, the second lens element 50 is disposed such that its image-side focal point coincides with the image-side focal point of the first lens element 30. Therefore, the chief ray PR is collimated by the second lens element 50. As a result, in the second lens array 41, the chief ray PR is emitted parallel to the optical axis AX.

[0091] The second lens array 41 has negative refractive power. Therefore, a virtual image 6" of the conjugate image 6' is located on the object side of the second lens array 41. The second optical system 24 is positioned so that the object-side focal point of the lens 24a coincides with the virtual image 6". Therefore, at the image plane 7 of the second optical system 24, the marginal ray MR intersects with the optical axis AX. As a result, an image of the object plane 6 is formed on the image plane 7 by the second optical system 24.

[0092] In the projection optical system of the second embodiment, the chief ray PR is emitted parallel to the optical axis AX from the second lens array 41. The chief ray PR is also emitted parallel to the optical axis AX from the second optical system 24. At the image plane 7, the chief ray PR is parallel to the optical axis AX.

[0093] Furthermore, at the image plane 7, the marginal ray MR intersects with the optical axis AX. The first optical system 21, the first lens array 22, and the second lens array 41 form a composite optical system. The image of the object plane formed by the composite optical system is projected onto the image plane 7 by the second optical system 24. As a result, an image of the object plane is formed on the image plane 7.

[0094] In the projection optical system of the first embodiment and the projection optical system of the second embodiment, the image side surface of the first lens array and the object side surface of the second lens array are lens surfaces. By making the lens surfaces face each other, it is possible to ensure a sufficient thickness even if the focal length of the first lens array and the focal length of the second lens array are shortened. Therefore, it is possible to increase the strength of the first lens array and the strength of the second lens array.

[0095] In the projection optical system of this embodiment, the range of magnification of the first optical system is from 1x to 10x.

[0096] At an imaging magnification smaller than 1:1, the first lens element needs to be small. This makes it difficult to manufacture the first lens array. At an imaging magnification greater than 10:1, the first lens element becomes too large. This makes it difficult to maintain the shape of the first lens element. In terms of optical formulas, the range from 1:1 to 10:1 corresponds to -1:1 to -10:1.

[0097] In the projection optical system of this embodiment, the magnification range of the second optical system is from 0.05 to 7 times.

[0098] As described above, an optical image of the pattern generated by the spatial modulator 10 is formed on the image plane. At an imaging magnification smaller than 0.05x, the area of ​​the optical image becomes too small. Therefore, when the projection optical system is used in an exposure apparatus, the exposure area becomes too small. As a result, the throughput, i.e., mass production efficiency, decreases. At an imaging magnification larger than life-size, the numerical aperture (NA) on the image plane becomes small. Therefore, the resolving power of the projection optical system and the contrast of the optical image decrease. In terms of optics, 0.05x to life-size corresponds to -0.05x to -7x.

[0099] An embodiment of the projection optical system will be described below, however, the present invention is not limited to this embodiment.

[0100] The projection optical system in each embodiment is composed of, in order from the object side, a first optical system, a first lens array, a second lens array, and a second optical system.

[0101] The first optical system is an ideal imaging optical system, and is composed of an aberration-free first lens and an aberration-free second lens. If the first lens and the second lens are considered as thin lenses, the distance from the first lens to the second lens is equal to the sum of the focal length of the first lens and the focal length of the second lens. Therefore, the first optical system is a telecentric optical system on both the object side and the image side. The distance from the object surface to the first lens is equal to the focal length of the first lens.

[0102] The first lens array has a flat surface and a curved surface with a convex surface facing the image side. The flat surface is the object side surface and the curved surface is the image side surface. The curved surface can be a spherical surface or an aspheric surface. Synthetic quartz is used for the first lens array.

[0103] The second lens array has a curved surface with a convex surface facing the object side and a flat surface, or a curved surface with a concave surface facing the object side and a flat surface. The curved surface is the object side surface and the flat surface is the image side surface. The curved surface can be spherical or aspherical. Synthetic quartz is used for the second lens array.

[0104] In Examples 1 to 4, the second lens array has a curved surface with a convex surface facing the object side, and a flat surface. In Examples 5 to 8, the second lens array has a curved surface with a concave surface facing the object side, and a flat surface.

[0105] The second optical system is an ideal imaging optical system, and is composed of an aberration-free third lens and an aberration-free fourth lens. If the third lens and the fourth lens are considered as thin lenses, the distance from the third lens to the fourth lens is equal to the sum of the focal length of the third lens and the focal length of the fourth lens. Therefore, the second optical system is a telecentric optical system on both the object side and the image side.

[0106] The surface data shows, from the left, the surface number, the radius of curvature (r), the surface spacing (d), the refractive index at a wavelength of 365 nm (ni), and k, the Conic coefficient.

[0107] The unit of the radius of curvature r, surface spacing d, and other lengths is "mm." However, since the optical system can obtain the same optical performance even if it is proportionally enlarged or reduced, the unit is not limited to "mm."

[0108] (First embodiment) Surface Data Surface number rd ni 1∞11.47469 2 -0.030 0.051 3 0.024 1 1.47469 4∞ Numerical aperture on the entrance side of the first optical system: 0.06 First lens focal length: 100 Second lens focal length: 100 Magnification of the first optical system: 1x (-1x) Third lens focal length: 100 Focal length of 4th lens: 50 Magnification of the second optical system: 1 / 2x (-0.5x) Distance between second lens and first lens array: 99.322 Distance between the second lens array and the third lens: 99.3317

[0109] (Second Example) Surface Data Surface number rd ni 1∞11.47469 2 -0.023 0.053 3 0.025 1 1.47469 4∞ Numerical aperture on the entrance side of the first optical system: 0.06 First lens focal length: 100 Second lens focal length: 100 Magnification of the first optical system: 1x (-1x) Third lens focal length: 100 Focal length of 4th lens: 20 Magnification of the second optical system: 1 / 5x (-0.2x) Distance between second lens and first lens array: 99.322 Distance between the second lens array and the third lens: 99.3165

[0110] (Third Example) Surface Data Surface number rd ni 1∞11.47469 2 -0.045 0.053 3 0.025 1 1.47469 4∞ Numerical aperture on the entrance side of the first optical system: 0.06 First lens focal length: 100 Second lens focal length: 200 Magnification of the first optical system: 2x (-2x) Third lens focal length: 100 Focal length of 4th lens: 50 Magnification of the second optical system: 1 / 2x (-0.5x) Distance between second lens and first lens array: 199.322 Distance between the second lens array and the third lens: 99.346

[0111] (Fourth Example) Surface Data Surface number rd ni 1∞11.47469 2 -0.070 0.179 3 0.085 1 1.47469 4∞ Numerical aperture on the entrance side of the first optical system: 0.06 First lens focal length: 100 Second lens focal length: 200 Magnification of the first optical system: 2x (-2x) Third lens focal length: 100 Focal length of 4th lens: 200 Magnification of the second optical system: 2x (-2x) Distance between second lens and first lens array: 199.322 Distance between the second lens array and the third lens: 99.283

[0112] (Fifth Example) Surface Data Surface number rd ni 1∞11.47469 2 -0.037 0.025 3 -0.025 1 1.47469 4∞ 3rd page k=-1.0 Numerical aperture on the entrance side of the first optical system: 0.06 First lens focal length: 100 Second lens focal length: 100 Magnification of the first optical system: 1x (-1x) Third lens focal length: 100 Focal length of 4th lens: 50 Magnification of the second optical system: 1 / 2x (-0.5x) Distance between second lens and first lens array: 99.322 Distance between the second lens array and the third lens: 99.305

[0113] (Sixth Example) Surface Data Surface number rd ni 1∞11.47469 2 -0.037 0.030 3 -0.022 1 1.47469 4∞ 3rd page k=-1.0 Numerical aperture on the entrance side of the first optical system: 0.06 First lens focal length: 100 Second lens focal length: 100 Magnification of the first optical system: 1x (-1x) Third lens focal length: 100 Focal length of 4th lens: 20 Magnification of the second optical system: 1 / 5x (-0.2x) Distance between second lens and first lens array: 99.322 Distance between the second lens array and the third lens: 99.3035

[0114] (Seventh Example) Surface Data Surface number rd ni 6∞1 1.47469 7 -0.041 0.040 8 -0.022 1 1.47469 9∞ Numerical aperture on the entrance side of the first optical system: 0.06 First lens focal length: 100 Second lens focal length: 200 Magnification of the first optical system: 2x (-2x) Third lens focal length: 100 Focal length of 4th lens: 50 Magnification of the second optical system: 1 / 2x (-0.5x) Distance between second lens and first lens array: 199.322 Distance between the second lens array and the third lens: 99.3006

[0115] (Eighth Example) Surface Data Surface number rd ni 1∞11.47469 2 -0.049 0.042 3 -0.029 1 1.47469 4∞ Numerical aperture on the entrance side of the first optical system: 0.06 First lens focal length: 100 Second lens focal length: 200 Magnification of the first optical system: 2x (-2x) Third lens focal length: 100 Focal length of 4th lens: 200 Magnification of the second optical system: 2x (-2x) Distance between second lens and first lens array: 199.322 Distance between the second lens array and the third lens: 99.2971

[0116] The values ​​of f1, f2, D1, B1, B2, P1, and β1 are shown below. The corresponding values ​​of conditional expressions (1) and (2) described below are also shown below. In each embodiment, the value of NA1 is 0.06. Example f1 f2 D1 B1 P1 β1 2×(NA1×D1) / (P1×β1×β1) 1 0.063 0.051 0.051 0.010 0.01 -1 0.612 2 0.048 0.053 0.053 -0.055 0.01 -1 0.636 3 0.095 0.053 0.053 0.023 0.01 -2 0.159 4 0.147 0.179 0.179 -0.039 0.01 -2 0.537 Example f1 f2 D1 B2 P1 β1 (f1-D1) / f1 5 0.078 -0.053 0.025 -0.017 0.01 -1 0.6795 6 0.078 -0.048 0.030 -0.019 0.01 -1 0.6154 7 0.086 -0.046 0.040 -0.021 0.01 -1 0.5349 8 0.103 -0.061 0.042 -0.025 0.01 -1 0.5922 f1 is the focal length of the first lens element. f2 is the focal length of the second lens element. D1 is the distance (air-equivalent length) between the first lens array and the second lens array. B1 is the distance from the second lens array to the re-imaged exit pupil when the exit pupil of the image of the object plane emerging from the first lens array is re-imaged by the second lens array. B2 is the distance from the second lens array to the re-imaged image when the light beam of the image of the object plane emerging from the first lens array is re-imaged by the second lens array.

[0117] In the first to fourth embodiments, the following formula is established. f2=D1 1 / B1=1 / f2-1 / (D1-f1) In the fifth to eighth embodiments, the following formula is established. f2=D1-f1 1 / B2=1 / f1-1 / D1

[0118] The distance from the second lens to the first lens array and the distance from the third lens to the second lens array will be described using the first embodiment as an example. In the other embodiments, the actual distances can be calculated in a similar manner.

[0119] In the first embodiment, synthetic quartz is used for the first and second lens arrays. The wavelength in the surface data of the first embodiment is 365 nm, and the refractive index of synthetic quartz at this wavelength is 1.47469. In this case, the air equivalent length of 1 mm thickness is 0.678 mm.

[0120] The position of the first lens array relative to the first optical system can be expressed using the rear focal length of the second lens and the air equivalent length. If the rear focal length of the second lens is 100 mm and the thickness of the first lens array is 1 mm, the distance from the second lens to the first lens array is calculated as follows: 100mm-0.678mm=99.322mm

[0121] The position of the second lens array relative to the second optical system can be expressed using the front focal length of the third lens, the air equivalent length, and B1. If the rear focal length of the second lens is 100 mm, the thickness of the first lens array is 1 mm, and B1 is 0.01 mm, the distance from the third lens to the second lens array is calculated as follows: 10mm0-0.678mm+0.01mm=99.332mm

[0122] In the projection optical system of the first embodiment, a spatial modulator having a plurality of spatial modulation elements is disposed on the object plane, and satisfies the following conditional expression (1). 2×(NA1×D1) / (P1×β1×β1)<0.71 (1) Where: NA1 is the numerical aperture of the first optical system, D1 is the air-equivalent length between the first and second lens arrays, β1 is the magnification of the first optical system, P1 is the pitch between two adjacent spatial light modulation elements, It is.

[0123] In the projection optical system of the first embodiment, the second lens array allows as much light as possible emitted from the first lens array to be incident on the second optical system 5. Therefore, it is preferable that as much light as possible emitted from the first lens array be incident on the second lens array.

[0124] By satisfying conditional expression (1), it is possible to reduce the amount of light that travels outside the second lens array. Therefore, it is possible to make most of the light that is emitted from the first lens array enter the second lens array. As a result, it is possible to form a sharp optical image with little loss of light.

[0125] The projection optical system of the second embodiment satisfies the following conditional expression (2). (f1-D1) / f1<0.71 (2) Where: f1 is the focal length of the first lens element, D1 is the air-equivalent length between the first and second lens arrays, It is.

[0126] In the projection optical system of the second embodiment, the second lens array allows as much light as possible emitted from the first lens array to be incident on the second optical system 5. Therefore, it is preferable that as much light as possible emitted from the first lens array be incident on the second lens array.

[0127] By satisfying conditional expression (2), it is possible to reduce the amount of light that travels outside the second lens array. Therefore, most of the light that is emitted from the first lens array can be made to enter the second lens array. As a result, there is little loss of light, and a sharp optical image can be formed.

[0128] In the projection optical system of this embodiment, a spatial modulator is placed on the object plane, and the spatial modulator is illuminated with light having a wavelength of 190 nm or more and 450 nm or less.

[0129] By setting the wavelength of the irradiating light to 190 nm or more and 450 nm or less, the resolving power of the projection optical system and the contrast of the optical image are improved. By using ultraviolet light, the resolving power of the projection optical system and the contrast of the optical image are further improved.

[0130] The exposure apparatus of this embodiment includes a light source, an illumination optical system that collects light from the light source, a spatial modulator having spatial modulation elements arranged two-dimensionally and illuminated by the illumination optical system, a projection optical system of this embodiment that is arranged between the spatial modulator and an object, and a stage that holds the object located on the image plane of the projection optical system.

[0131] Fig. 10 is a diagram showing an exposure apparatus of this embodiment. The same components as those in Fig. 1 and Fig. 2 are given the same numbers and their explanations are omitted.

[0132] The exposure apparatus 60 includes a light source 61 , an illumination optical system 62 , a spatial modulator 10 , a projection optical system 1 , and a stage 63 .

[0133] Ultraviolet light is emitted from the light source 61. For example, an LED light source, a mercury lamp, etc. can be used as the light source 61. A light source that emits visible light can be used as the light source 61.

[0134] The illumination optical system 62 collects the ultraviolet light emitted from the light source 61. The ultraviolet light is irradiated onto the spatial modulator 10 by the illumination optical system 62. As a result, the spatial modulator 10 can be illuminated with the ultraviolet light. It is preferable to use Kohler illumination for illuminating the spatial modulator 10. By using Kohler illumination, the spatial modulator 10 can be illuminated in a state without illumination unevenness or with reduced illumination unevenness.

[0135] A stage 63 is disposed on the opposite side of the spatial light modulator 10 across the projection optical system 1. The stage 63 holds an object 64. The stage 63 moves in synchronization with the operation of the spatial light modulator 10.

[0136] The object 64 is located on the image plane of the projection optical system 1. Various patterns can be generated by the spatial modulator 10. Therefore, by placing the object 64, for example, a photosensitive material, on the image plane, various patterns can be projected onto the photosensitive material.

[0137] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Industrial Applicability]

[0138] The present invention is suitable for a projection optical system and an exposure apparatus that can form a sharp optical image with little loss of light. [Explanation of symbols]

[0139] 1, 1', 1” projection optics 2 First optical system 2a, 2b lenses 3 First Lens Array 4, 4', 4” Second Lens Array 5 Second optical system 6 Object plane 6' Conjugate image of object plane 6” Conjugate Virtual Image 7 Image plane 10 Spatial Modulator 10a Spatial modulation element 11 Lens Array 11a Lens element 11b Lens surface 20 Projection optical system 21 1st optical system 21a, 21b Lenses 22 First Lens Array 22a, 23a Object side 22b, 23b Elephant side 23 Second Lens Array 24 Second optical system 24a, 24b Lenses 30 first lens element 30a, 31a Object side 30b, 31b Elephant side 31 Second lens element 32, 33 exit pupil 40 Projection optical system 41 Second Lens Array 41a Object side 41b Elephant side 50 second lens element 50a Object side 50b elephant side 60 Exposure Equipment 61 Light source 62 Illumination optical system 63 Stages 64 Object AX optical axis MR Peripheral Rays PR Chief ray OB1 On-axis object point OB2 Off-axis object point

Claims

1. From the object side, a first optical system that is telecentric on both the object side and the image side; a first lens array having first lens elements arranged two-dimensionally; a second lens array having second lens elements arranged two-dimensionally; a second optical system that is telecentric on both the object side and the image side, A projection optical system, wherein the two-dimensional arrangement of the first lens array and the two-dimensional arrangement of the second lens array coincide with each other.

2. The second lens array emits marginal rays parallel to the optical axis of the projection optical system; 2. The projection optical system according to claim 1, wherein the second optical system forms a composite pupil image formed by the first optical system, the first lens array, and the second lens array on an image plane of the second optical system.

3. the second lens array emits a chief ray parallel to the optical axis of the projection optical system; 2. The projection optical system according to claim 1, wherein the second optical system forms an image of a composite object plane formed by the first optical system, the first lens array, and the second lens array on an image plane of the second optical system.

4. 4. The projection optical system according to claim 2, wherein the magnification of the first optical system ranges from 1x to 10x.

5. 4. The projection optical system according to claim 2, wherein the magnification of the second optical system ranges from 0.05 to 7.

6. A spatial modulator disposed on an object plane and having a plurality of spatial modulation elements, 3. The projection optical system according to claim 2, wherein the following conditional expression (1) is satisfied: 2 × (NA1 × D1) / (P1 × β1 × β1) < 0.71 (1) where: NA1 is the numerical aperture of the first optical system, D1 is the air-equivalent length between the first lens array and the second lens array, β1 is the magnification of the first optical system, P1 is the pitch between two adjacent spatial light modulation elements, is.

7. 7. The projection optical system according to claim 6, wherein the spatial modulator is illuminated with light having a wavelength of 190 nm or more and 450 nm or less.

8. A light source and an illumination optical system that collects light from the light source; a projection optical system according to claim 7; a stage for holding an object positioned on an image plane of the projection optical system, an exposure apparatus, wherein the spatial light modulation elements are arranged two-dimensionally, and the projection optical system, excluding the spatial light modulator, is disposed between the spatial light modulator and the object;

9. 4. The projection optical system according to claim 3, wherein the following conditional expression (2) is satisfied: (f1-D1) / f1<0.71 (2) where: f1 is the focal length of the first lens element, D1 is the air-equivalent length between the first lens array and the second lens array, is.

10. a spatial modulator disposed on an object plane and having a plurality of spatial modulation elements; 10. The projection optical system according to claim 9, wherein the spatial modulator is illuminated with light having a wavelength of 190 nm or more and 450 nm or less.

11. A light source and an illumination optical system that collects light from the light source; The projection optical system according to claim 10; a stage for holding an object positioned on an image plane of the projection optical system, an exposure apparatus, wherein the spatial light modulation elements are arranged two-dimensionally, and the projection optical system, excluding the spatial light modulator, is disposed between the spatial light modulator and the object;

Images