Illumination optical system, exposure apparatus, and method of manufacturing article

Abstract

The present application relates to an illumination optical system, an exposure apparatus, and a method of manufacturing an article. Provided is an illumination optical system that illuminates an illuminated surface, characterized by having: an optical integrator that forms a 2nd light source using light from a light source; and a deformation lens, the optical integrator including: an incident-side optical element in which a plurality of 1st optical elements are arranged; and an emission-side optical element including a plurality of 2nd optical elements arranged corresponding to each of the plurality of 1st optical elements, the deformation lens being disposed between the incident-side optical element and the emission-side optical element.

Description

Technical Field

[0001] This invention relates to an illumination optical system, an exposure apparatus, and a method for manufacturing an article. Background Technology

[0002] In the photolithography process for manufacturing semiconductor devices, an exposure apparatus is typically used to transfer a pattern formed on a master mask (or intermediate mask) onto a substrate (silicon substrate, glass substrate) coated with a photosensitive agent. Within this exposure apparatus, the miniaturization of the pattern transferred to the substrate means that even slight changes in exposure conditions can lead to increased defect rates and decreased yields.

[0003] Therefore, in an illumination optical system that illuminates the original, by making the cumulative exposure uniform within the illumination area, defects such as uneven linewidth of the pattern formed on the substrate due to uneven illuminance in the illumination area are suppressed. For example, regarding a scanning type exposure apparatus that transfers the pattern of the original onto the substrate by scanning the original and the substrate relative to each other with an exposure light of a slit shape, Japanese Patent Application Publication No. 10-340854 discloses a technique for making the cumulative exposure uniform. In Japanese Patent Application Publication No. 10-340854, the cumulative exposure is made uniform by using a variable slit device to vary the width of the slit-shaped exposure light in the scanning direction according to the position of the slit direction (the direction orthogonal to the scanning direction).

[0004] Furthermore, with the miniaturization of semiconductor devices, higher resolution is required in exposure equipment. To meet this requirement, the numerical aperture (NA) of the projection optics system is increased (high NA) and the wavelength of the exposure light is shortened. When the exposure light is shortened, the transmittance of the nitrile material generally decreases, and the types of nitrile materials that can be used in the projection optics system become extremely limited. Therefore, chromatic aberration correction in the projection optics system becomes difficult, requiring the wavelength of the exposure light to be narrow enough to negligible the effect of chromatic aberration. For example, in projection optics systems using light with wavelengths below 300 nm, the nitrile materials that can be used are limited to quartz and fluorite, so lasers are used as the exposure light (exposure light source). Specifically, excimer lasers are widely used as short-wavelength light sources in exposure equipment due to their very high energy and the potential for high throughput.

[0005] On the other hand, excimer lasers are pulsed lasers, so in scanning exposure apparatuses, when the scanning speed and the timing of the pulse oscillation are misaligned, uneven exposure may occur on the original and the substrate. To reduce the uneven exposure caused by the influence of pulse oscillation, a technique has been proposed to mitigate the synchronization accuracy of the scanning speed and pulse oscillation by making the light intensity distribution in the scanning direction on the illuminated surface (original) substantially an isosceles trapezoid or isosceles triangle. However, to make the light intensity distribution in the scanning direction on the illuminated surface substantially an isosceles trapezoid or isosceles triangle, light-reducing elements such as ND filters are considered, but this results in a loss of light.

[0006] Therefore, Japanese Patent Application Publication No. 7-230949 proposes a technique for forming light intensity distributions such as isosceles trapezoids and isosceles triangles with minimal light loss. In this publication, the principal ray of the light beam is focused to a position separated from the illuminated surface by a predetermined distance along the optical axis in a plane including the scanning direction in the illuminated surface and the optical axis of the illumination optical system, thus forming a tilted region in the light beam on the illuminated surface caused by blurring. By shaping the light intensity distribution in this tilted region into a predetermined shape, it is possible to suppress the reduction in illumination efficiency (light loss) while mitigating exposure deviation. To achieve this, Japanese Patent Application Publication No. 7-230949 includes a deformable lens such as a cylindrical lens in the illumination optical system that overlaps the light beam from the optical integrator onto the illuminated surface. According to the technology disclosed in Japanese Patent Application Publication No. 7-230949, the shape of the light intensity distribution in the scanning direction in the illuminated surface can be determined in a manner that minimizes the deviation in cumulative exposure caused by deviations in scanning speed and timing shifts in pulse oscillation. Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, when a deformable lens such as a cylindrical lens is used in an illumination optical system that superimposes a beam from an optical integrator onto the illuminated surface, the numerical aperture or exit pupil position of the illumination optical system differs in the scanning direction and in the direction orthogonal to the scanning direction. As a result, the transfer characteristics of the pattern transferred onto the substrate differ in the scanning direction and in the direction orthogonal to the scanning direction.

[0009] The present invention provides an illumination optical system that is advantageous for illuminating a surface.

[0010] As one aspect of the present invention, an illumination optical system illuminates a surface to be illuminated, characterized by having: an optical integrator that forms a secondary light source using light from a light source; and a deformable lens, the optical integrator comprising: an incident-side optical element having a plurality of first optical elements arranged thereon; and an exit-side optical element having a plurality of second optical elements arranged corresponding to each of the plurality of first optical elements, the deformable lens being disposed between the incident-side optical element and the exit-side optical element.

[0011] As another aspect of the present invention, an illumination optical system illuminates an illuminated surface, characterized by having an optical integrator that forms a secondary light source using light from a light source. The optical integrator includes: an incident-side optical element having a plurality of first optical elements arranged thereon; and an exit-side optical element including a plurality of second optical elements arranged corresponding to each of the plurality of first optical elements. The plurality of first optical elements and the plurality of second optical elements are periodically arranged in a first direction and in a second direction intersecting the first direction. The arrangement period of the plurality of first optical elements and the arrangement period of the plurality of second optical elements are different for at least one of the first direction and the second direction.

[0012] As another aspect of the present invention, an exposure apparatus for exposing a substrate via a master plate is characterized by comprising: the aforementioned illumination optical system for illuminating the master plate disposed on the illuminated surface; and a projection optical system for projecting the pattern of the master plate onto the substrate.

[0013] As another aspect of the present invention, an exposure apparatus that exposes the substrate via the original while moving the original and the substrate in a scanning direction is characterized by comprising: the aforementioned illumination optical system for illuminating the original disposed on the illuminated surface; and a projection optical system for projecting the pattern of the original onto the substrate.

[0014] As another aspect of the present invention, a method for manufacturing an article is characterized by comprising: a step of exposing a substrate using the aforementioned exposure apparatus; a step of developing the exposed substrate; and a step of manufacturing an article from the developed substrate.

[0015] Other objects or aspects of the invention will become clear from the following description of the embodiments with reference to the accompanying drawings.

[0016] The effects of the invention

[0017] According to the present invention, for example, an illumination optical system that facilitates the illumination of an illuminated surface can be provided. Attached Figure Description

[0018] Figure 1 This is a schematic cross-sectional view showing the structure of the exposure apparatus as one aspect of the present invention.

[0019] Figure 2 This is a schematic cross-sectional view showing an example of the structure from the optical integrator to the intermediate illumination surface.

[0020] Figure 3 This is a schematic cross-sectional view showing an example of the structure from the optical integrator to the intermediate illumination surface.

[0021] Figure 4 This is a schematic cross-sectional view showing the light illuminating a point on the central illumination surface.

[0022] Figure 5 This is a schematic cross-sectional view showing the light illuminating a point on the central illumination surface.

[0023] Figure 6 This is a schematic cross-sectional view showing an example of the structure from the optical integrator to the intermediate illumination surface.

[0024] Figure 7 This is a schematic cross-sectional view showing the light illuminating a point on the central illumination surface.

[0025] Figure 8 This is a schematic cross-sectional view showing an example of the structure from the optical integrator to the intermediate illumination surface.

[0026] Figure 9 This is a schematic cross-sectional view showing an example of the structure from the optical integrator to the intermediate illumination surface.

[0027] Figure 10 This is a schematic cross-sectional view showing another structure of the exposure apparatus EX as one aspect of the present invention.

[0028] Figure 11 This is a schematic cross-sectional view showing an example of the structure from the optical integrator to the intermediate illumination surface.

[0029] Figure 12 This is a schematic cross-sectional view showing an example of the structure from the optical integrator to the intermediate illumination surface.

[0030] Figure 13 This is a schematic cross-sectional view showing the light illuminating a point on the central illumination surface.

[0031] Figure 14 This is a schematic cross-sectional view showing the light illuminating a point on the central illumination surface.

[0032] Figure 15This is a schematic cross-sectional view showing an example of the structure from the optical integrator to the intermediate illumination surface.

[0033] Figure 16 This is a schematic cross-sectional view showing the light illuminating a point on the central illumination surface.

[0034] Figure 17 This is a schematic cross-sectional view showing an example of the structure from the optical integrator to the intermediate illumination surface.

[0035] Figure 18 This is a schematic cross-sectional view showing an example of the structure from the optical integrator to the intermediate illumination surface. Detailed Implementation

[0036] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Furthermore, the invention covered by the claims is not limited to the embodiments described below. Multiple features are described in the embodiments, but not all of these multiple features are necessarily essential to the invention; moreover, multiple features can be arbitrarily combined. Moreover, in the drawings, the same or identical structures are given the same reference numerals, and repeated descriptions are omitted.

[0037] <First Implementation>

[0038] Figure 1 This is a schematic cross-sectional view showing the structure of the exposure apparatus EX as one aspect of the present invention. The exposure apparatus EX is a photolithography apparatus used in the manufacturing process of devices such as semiconductor devices to form patterns on a substrate. In this embodiment, the exposure apparatus EX is a step-and-scan exposure apparatus (scanner) that transfers the pattern of the original 18 onto the substrate by exposing the substrate 21 while moving the original 18 and the substrate 21 in the scanning direction (scanning exposure). However, the exposure apparatus EX can also employ a step-and-repeat method or other exposure methods.

[0039] Exposure device EX, such as Figure 1 The device shown includes an illumination optical system IL that illuminates the master 18 (intermediate mask or mask) using light from the light source 1, and a projection optical system 20 that projects the pattern of the master 18 onto the substrate 21 (wafer, glass plate). In addition, the exposure apparatus EX includes a master stage 19 that moves while holding the master 18 and a substrate stage 22 that moves while holding the substrate 21.

[0040] In this embodiment, the light source 1 is a pulsed light source with pulse oscillation, such as an ArF excimer laser with a wavelength of about 193 nm or a KrF excimer laser with a wavelength of about 248 nm, which emits light (exposure light) to illuminate the original 18.

[0041] The illumination optical system IL includes a routing optical system 2, an emission angle preservation optical element 4, a diffraction optical element 5, a condenser lens 6, a prism unit 8, and a zoom lens unit 9. Additionally, the illumination optical system IL includes an optical integrator 100, a deformable lens 103, an aperture stop 11, a condenser lens 12, a field aperture 13, a shielding unit 15, an imaging optical system 16, and a curved mirror 17.

[0042] The routing optical system 2 guides light from the light source 1 via the curved mirror 3 to the emission angle preservation optical element 4. The emission angle preservation optical element 4 is located on the light source side of the diffractive optical element 5 and includes optical integrators such as compound eye lenses, microlens arrays, and fiber bundles. The emission angle preservation optical element 4 maintains a constant divergence angle of the light from the light source 1 while guiding it to the diffractive optical element 5. The emission angle preservation optical element 4 reduces the impact of output variations from the light source 1 on the light intensity distribution (pattern distribution) formed by the diffractive optical element 5.

[0043] The diffractive optical element 5 is disposed on a surface that is in a Fourier transform relationship with the pupil plane of the illumination optical system IL. The diffractive optical element 5 transforms the light intensity distribution from the light source 1 through diffraction in the pupil plane of the illumination optical system IL, which is a conjugate surface with the pupil plane of the projection optical system 20, and in the surface conjugate to the pupil plane of the illumination optical system IL, thereby forming a desired light intensity distribution. The diffractive optical element 5 may also be composed of a computer-generated hologram (CGH) designed by a computer to obtain a desired diffraction pattern in the diffraction pattern surface. In this embodiment, the shape of the light source formed on the pupil plane of the projection optical system 20 is referred to as the effective light source shape. Furthermore, "effective light source" refers to the light intensity distribution or light angle distribution in the illuminated surface and the conjugate surface of the illuminated surface.

[0044] In an illumination optical system IL, multiple diffractive optical elements 5 can also be arranged. For example, each of the multiple diffractive optical elements 5 is mounted (mounted) in one of the multiple slots corresponding to a turntable (not shown), and any diffractive optical element 5 is configured into the optical path of the illumination optical system IL. The multiple diffractive optical elements 5 form different effective light source shapes. These effective light source shapes include small circular shapes (relatively small circular shapes), large circular shapes (relatively large circular shapes), annular shapes, bipolar shapes, quadrupole shapes, and other shapes. The method of illuminating the illuminated surface with an annular shape, bipolar shape, or quadrupole shape as an effective light source is called deformable illumination.

[0045] Light from the emission angle preservation optical element 4 is diffracted by the diffractive optical element 5 and guided to the condenser lens 6. The condenser lens 6 focuses the light diffracted by the diffractive optical element 5, forming a diffraction pattern (light intensity distribution) on the diffraction surface 7.

[0046] The diffraction surface 7 is the surface that has an optical Fourier transform relationship with the diffraction optical element 5. By replacing the diffraction optical element 5 arranged in the optical path of the illumination optical system IL, the shape of the light intensity distribution formed on the diffraction surface 7 can be changed.

[0047] The light intensity distribution formed on the diffraction surface 7 is introduced into the optical integrator 100 via the prism unit 8 and the zoom lens unit 9 and the bending mirror 10.

[0048] The prism unit 8 adjusts the annularity and other properties of the light intensity distribution formed on the diffraction surface 7 and guides it to the zoom lens unit 9. The zoom lens unit 9 expands or reduces the light intensity distribution formed on the diffraction surface 7 while maintaining a roughly similar shape, and guides it to the optical integrator 100.

[0049] The optical integrator 100 forms a plurality of secondary light sources according to the intensity distribution of the incident light and guides them to the condenser lens 12. In this embodiment, the optical integrator 100 includes an incident-side integrating circuit 101 and an exit-side integrating circuit 102. A deformable lens 103 is disposed between the incident-side integrating circuit 101 and the exit-side integrating circuit 102. The detailed structure of the optical integrator 100 and the deformable lens 103 will be described later.

[0050] The aperture stop 11 is positioned near the exit surface of the optical integrator 100, i.e., the pupil surface of the illumination optical system IL.

[0051] The condenser lens 12 gathers a plurality of light rays guided from the optical integrator 100, and illuminates the intermediate illumination surface 14, which is the illuminated surface of the condenser lens 12, in an overlapping manner. When light rays are incident on the optical integrator 100 and focused by the condenser lens 12, the intermediate illumination surface 14 is illuminated with a light intensity distribution in a generally rectangular shape.

[0052] The imaging optical system 16 projects the light intensity distribution formed on the intermediate illumination surface 14 onto the illuminated surface 18, which is the illumination optical system IL, via the curved mirror 17. In this way, the original surface 18 and the intermediate illumination surface 14 become optically conjugate.

[0053] The shielding unit 15 is disposed on the central lighting surface 14.

[0054] The masking unit 15 is configured to define the illumination range of the original plate 18 maintained on the original plate stage 19, and is scanned synchronously with the original plate stage 19 and the substrate stage 22. Figure 1 In the process, the scanning direction of the masking unit 15 is the Z direction, while the scanning direction of the original 18 and the substrate 21 is the X direction.

[0055] The field aperture 13 is positioned separate from the intermediate illumination surface 14 and the shielding unit 15 along the optical axis (X direction) of the illumination optical system IL. The field aperture 13 defines the illumination range in the scanning direction (Z direction at the position of the field aperture 13) of the intermediate illumination surface 14, which serves as the illuminated surface of the condenser lens 12.

[0056] The field aperture 13 is positioned separate from the intermediate illumination surface 14 along the optical axis of the illumination optical system IL. Therefore, the light partially blocked by the field aperture 13 results in a roughly trapezoidal light intensity distribution in the intermediate illumination surface 14 along the scanning direction. This reduces the impact of uneven exposure caused by timing deviations in scanning speed or pulse oscillation in the exposure apparatus EX.

[0057] Furthermore, in this embodiment, the field aperture 13 is disposed near the central illumination surface 14, but it may also be disposed near the original image 18, which is the illuminated surface. In addition, in this embodiment, the field aperture 13 is disposed closer to the light source side than the central illumination surface 14, but it is not limited to this and may also be disposed closer to the original image side than the central illumination surface 14.

[0058] Alternatively, the field aperture 13 can also be a variable field aperture capable of changing the aperture width in the scanning direction for each direction orthogonal to the scanning direction (non-scanning direction (Y direction)). By changing the aperture width in the scanning direction of the field aperture 13, the length of the scanning direction in which the light intensity distribution is formed in the illumination area can be changed. This allows for the correction of unevenness in the cumulative exposure related to the non-scanning direction during scanning exposure.

[0059] The projection optics system 20 includes multiple optical components (lenses, mirrors, and other optical elements) that project the pattern of the original 18 onto the substrate 21. The resolution of the pattern of the original 18 depends on the numerical aperture (NA) of the projection optics system 20 and the effective light source shape.

[0060] During exposure, light emitted from the light source 1 illuminates the original plate 18 held on the original plate stage 19 through the illumination optics system IL. The pattern of the original plate 18 is imaged on the substrate 21 held on the substrate stage 22 by the projection optics system 20. At this time, the pattern of the original plate 18 is transferred to the substrate 21 by scanning the original plate 18 and the substrate 21 at a speed ratio that is the reduction ratio of the projection optics system 20.

[0061] The structure of the optical integrator 100 and the deformable lens 103 in the illumination optical system IL will be described below. Figure 2 as well as Figure 3 This is a schematic cross-sectional view showing the structure of a portion of the illumination optical system IL, specifically, the structure from the optical integrator 100 to the intermediate illumination surface 14. Figure 2The cross-section in the XY plane is shown. Figure 3 The cross-section in the XZ plane is shown.

[0062] In this embodiment, the optical integrator 100 is composed of an incident-side integrating circuit 101, which serves as an incident-side optical element, and an exit-side integrating circuit 102, which serves as an exit-side optical element. The incident-side integrating circuit 101 and the exit-side integrating circuit 102 are lens arrays (fly-eye lenses) arranged in the scanning direction (Z direction) and the non-scanning direction (Y direction) which is orthogonal (crossed) to the scanning direction.

[0063] The incident-side integrating circuit 101 includes a plurality of incident-side element lenses (first optical elements) 101a arranged periodically in the scanning direction (first direction) and the non-scanning direction (second direction). The emission-side integrating circuit 102 includes a plurality of emission-side element lenses (second optical elements) 102a arranged corresponding to each of the plurality of incident-side element lenses 101a. Furthermore, element lenses (not shown) are also arranged outside the XY and XZ planes. Figure 2 as well as Figure 3 The image illustrates, by way of example, a lens array consisting of five element lenses arranged in the scanning direction and five element lenses arranged in the non-scanning direction in each of the incident-side integrating circuit 101 and the emission-side integrating circuit 102.

[0064] An anamorphic lens 103 is disposed between the incident-side integrating circuit 101 and the exit-side integrating circuit 102. The anamorphic lens 103 is generally a lens whose optical power is not rotationally symmetric; in this embodiment, it is configured such that the focusing position of the light emitted from the condenser lens 12 differs in the scanning direction and the non-scanning direction. Figure 2 as well as Figure 3 In this context, the deformable lens 103 is a cylindrical lens with positive optical power in the scanning direction.

[0065] The light incident on the optical integrator 100 is split into many beams by the incident-side integrator circuit 101. The beams split by the incident-side integrator circuit 101 exit from the individual element lenses 101a of the incident-side integrator circuit 101, enter the element lenses 102a of the corresponding exit-side integrator circuit 102, and exit toward the condenser lens 12.

[0066] An aperture stop 11 is disposed near the emission surface of the optical integrator 100 (emission-side integrator circuit 102). The position of the aperture stop 11 corresponds to the pupil surface of the condenser lens 12.

[0067] The light emitted from the optical integrator 100 is focused by the condenser lens 12, illuminating the intermediate illumination surface 14 in an overlapping manner. At this time, the deformable lens 103 has no optical power in the non-scanning direction, so the exit angle of the light rays emitted from the incident-side integrating circuit 101 remains unchanged. Therefore, as... Figure 2 As shown, light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a in the incident-side integrating circuit 101 are emitted perpendicularly from the center of the optical surface of the corresponding element lens 102a in the exit-side integrating circuit 102. In other words, light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a in the incident-side integrating circuit 101 are emitted from the optical integrator 100 parallel to the optical axis (X-axis) of the illumination optical system IL. The light rays emitted parallel to the optical axis of the illumination optical system IL are focused by the condenser lens 12 with a focal length of fc to a position at a distance fc from the condenser lens 12 (principal point).

[0068] The intermediate illumination surface 14 is located at a distance fc from the principal point of the condenser lens 12. Therefore, the light intensity distribution in the non-scanning directions of the intermediate illumination surface 14 is as follows: Figure 2 The distribution shown is roughly rectangular.

[0069] Here, consider the case where the deformable lens 103 is not placed between the incident-side integrating circuit 101 and the exit-side integrating circuit 102, and the field aperture 13, which forms a trapezoidal light intensity distribution in the scanning direction, is positioned separately from the intermediate illumination surface 14 in the optical axis direction. In this case, a portion of the light must be blocked by the field aperture 13, resulting in a reduction in illumination efficiency.

[0070] Furthermore, consider the case where the field aperture 13 is positioned at a distance fc from the condenser lens 12 (the condenser position), and the intermediate illumination surface 14, which is optically conjugate with the original image 18, is positioned separate from the condenser position in the optical axis direction. In this case, the light blocked by the field aperture 13 can be suppressed to a minimum, but the light intensity distribution in the non-scanning direction of the intermediate illumination surface 14 also becomes approximately trapezoidal. Therefore, in order to uniformly illuminate the original image 18, the area of ​​the oblique edge of the light intensity distribution must be blocked using the shielding unit 15, resulting in a reduction in illumination efficiency.

[0071] Therefore, in order to suppress the reduction of illumination efficiency while forming a roughly trapezoidal light intensity distribution in the scanning direction, it is preferable to focus the light in the non-scanning direction to the position of the intermediate illumination surface 14 which is optically conjugate with the original 18, and focus the light in the scanning direction to the position of the field aperture 13.

[0072] On the other hand, as in this embodiment, consider the case where a deformable lens 103 with positive optical power in the scanning direction is disposed between the incident-side integrating circuit 101 and the exit-side integrating circuit 102. In this case, the light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a in the incident-side integrating circuit 101 are as follows: Figure 3 The light rays are refracted by the deformable lens 103 and incident on the emission-side integrator circuit 102. As a result, the light rays refracted by the deformable lens 103 are incident at a position offset from the center of the optical surface of the corresponding element lens 102a of the emission-side integrator circuit 102, which corresponds to the element lens 101a of the incident-side integrator circuit 101. Then, the light rays incident on the emission-side integrator circuit 102 are further refracted by each element lens 102a and emitted.

[0073] The incident angle of light rays towards each element lens 102a of the emission-side integrator circuit 102, as well as the offset of the incident position of the light rays from the center of the optical surface, both become larger the further away from the optical axis. Therefore, the exit angle of light rays from each element lens 102a of the emission-side integrator circuit 102 becomes larger the further away from the optical axis. In other words, the exit angle of light rays from each element lens 102a of the emission-side integrator circuit 102 changes monotonically with distance from the optical axis. As a result, light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a of the incident-side integrator circuit 101 are focused and emitted towards the condenser lens 12. Thus, the deformable lens 103 is configured such that the angle of light rays emitted from each element lens 102a changes monotonically from the center of the optical surface of the optical integrator 100 towards the periphery with respect to at least one of the scanning direction and the non-scanning direction.

[0074] When the light rays emitted from the center of the optical surface of each of the element lenses 101a incident perpendicularly to the incident side and from each of the element lenses 102a on the exit side are extended, as... Figure 4 As shown, they intersect at a point O on the optical axis located at a distance s from the principal point of the condenser lens 12 on the original side. This is equivalent to the light source of the object relative to the condenser lens 12 being located at a distance s from the condenser lens 12 on the original side.

[0075] Therefore, the focusing position of the light rays gathered by the condenser lens 12 is located at a distance d closer (towards the light source) than the intermediate illumination surface 14, which is located at a distance fc from the condenser lens 12. Consequently, the light intensity distribution in the scanning direction at the distance d from the intermediate illumination surface 14 on the light source side is approximately rectangular. On the other hand, at the intermediate illumination surface 14, the light intensity distribution is approximately trapezoidal in the scanning direction, located a distance d away from the focusing position.

[0076] Furthermore, if the field aperture 13, which defines the illumination area for the scanning direction and forms a roughly trapezoidal light intensity distribution, is positioned at the focusing position in the scanning direction (at a distance d from the central illumination surface 14 on the light source side), the light blocked by the field aperture 13 is suppressed to a minimum. Therefore, it is possible to form a roughly trapezoidal light intensity distribution in the scanning direction while minimizing the reduction in illumination efficiency.

[0077] The width L of the hypotenuse of the roughly trapezoidal light intensity distribution is represented by the illumination NA (NAIL) in the intermediate illumination surface 14 and the distance d by the following equation (1).

[0078] L=2d·tan[arcsin(NAIL)]···(1)

[0079] Therefore, based on the width L of the hypotenuse of the trapezoidal shape corresponding to the desired light intensity distribution and the illumination NA, the position of the field aperture 13 or the distance d from the central illumination surface 14 to the focusing position related to the scanning direction can be determined.

[0080] Furthermore, even if a deformable lens 103 is arranged between the incident-side integration circuit 101 and the emission-side integration circuit 102 in the optical integrator 100, the illumination NA in the intermediate illumination surface 14 will not be different in the scanning direction and the non-scanning direction.

[0081] Figure 5 This is a schematic cross-sectional view showing the illuminating light rays at a point on the intermediate illumination surface 14 in the XZ section. The condenser lens 12 has rotationally symmetric optical power, so the illuminating light rays at a point on the intermediate illumination surface 14 are the same in the scanning and non-scanning directions. The illumination NA (NAIL) is determined by the diameter EA of the aperture stop 11 and the focal length fc of the condenser lens 12, and is expressed by the following equation (2).

[0082] NAIL=EA / 2÷fc···(2)

[0083] Therefore, if the diameter EA of the aperture stop 11 and the focal length fc of the condenser lens 12 are the same in the scanning direction and the non-scanning direction (aperture stop 11 and condenser lens 12 are rotationally symmetrical), the illumination NA will not be different in the scanning direction and the non-scanning direction.

[0084] In this embodiment, the case where the field aperture 13 is positioned near the intermediate illumination surface 14 is described, but it is not limited to this. For example, the field aperture 13 may be positioned near the original image 18, which is optically conjugate with the intermediate illumination surface 14, or it may be positioned no closer to the light source side than the intermediate illumination surface 14, but closer to the original image side than the intermediate illumination surface 14.

[0085] In such a situation, such as Figure 6 As shown, the deformable lens 103 can be configured as a cylindrical lens with negative optical power in the scanning direction. Thus, light rays incident perpendicularly to the center of the optical surface of each of the element lenses 101a in the incident-side integrating circuit 101 diverge and exit towards the condenser lens 12. When the light rays incident perpendicularly to the center of the optical surface of each of the element lenses 101a in the incident side and exiting from each of the element lenses 102a in the exit side are extended, as... Figure 7 As shown, they intersect at a point O on the optical axis located at a distance s from the principal point of the condenser lens 12 on the light source side. This is equivalent to the light source, which is the object relative to the condenser lens 12, being located at a distance s from the condenser lens 12 on the light source side.

[0086] Therefore, the focusing position of the light rays gathered by the condenser lens 12 is located at a distance d further inward (on the original side) than the intermediate illumination surface 14, which is located at a distance fc from the condenser lens 12. Consequently, the light intensity distribution in the scanning direction at the distance d from the intermediate illumination surface 14 on the original side is approximately rectangular. On the other hand, at the intermediate illumination surface 14, the light intensity distribution is approximately trapezoidal in the scanning direction, located a distance d away from the focusing position.

[0087] Furthermore, if the field aperture 13 is positioned at a distance d from the central illumination surface 14 on the side of the original image, the light blocked by the field aperture 13 is suppressed to a minimum. Therefore, it is possible to form a roughly trapezoidal light intensity distribution in the scanning direction while minimizing the reduction in illumination efficiency.

[0088] However, in the structure where the light rays from the center of the optical surface of each of the element lenses 101a incident perpendicularly to the incident side diverge while exiting toward the condenser lens 12, the effective diameter of the condenser lens 12 becomes larger. Therefore, the structure where the light rays from the center of the optical surface of each of the element lenses 101a incident perpendicularly to the incident side converge while exiting toward the condenser lens 12 is advantageous from the perspective of manufacturing cost and the performance of the illumination optics system IL.

[0089] In this embodiment, the deformable lens 103 disposed between the incident-side integrating circuit 101 and the emission-side integrating circuit 102 in the optical integrator 100 is described as a cylindrical lens with optical power in the scanning direction. However, it is not limited to this, and the deformable lens 103 may also be a cylindrical lens with optical power in the non-scanning direction.

[0090] When the deformable lens 103 is configured as a cylindrical lens with optical power in the non-scanning direction, the field aperture 13 is positioned at a distance fc from the condenser lens 12. Furthermore, the intermediate illumination surface 14 is positioned at a predetermined distance d away, and the optical power of the deformable lens 103 in the non-scanning direction is set in such a way that the focusing position in the non-scanning direction coincides with the intermediate illumination surface 14.

[0091] Alternatively, the deformable lens 103 can be configured as a toroidal lens having non-zero optical power in both the scanning and non-scanning directions. In this case, the positions of the field aperture 13 and the intermediate illumination surface 14 can be set at predetermined distances from the position fc away from the condenser lens 12. Then, the optical power of the deformable lens 103 in the scanning direction and the optical power in the non-scanning direction can be set such that the focusing positions of the condenser lens 12 in the scanning and non-scanning directions are aligned with the field aperture 13 and the intermediate illumination surface 14, respectively.

[0092] For example, the field aperture 13 can be positioned closer to the light source than the distance fc from the condenser lens 12, and the intermediate illumination surface 14 can be positioned closer to the original image than the distance fc from the condenser lens 12. Then, the deformable lens 103 can be configured to have a positive optical power in the scanning direction and a negative optical power in the non-scanning direction.

[0093] Alternatively, the deformable lens 103 can be configured such that the surface on the light source side has optical power only in one of the scanning and non-scanning directions, and the surface on the original image side has optical power only in the other of the scanning and non-scanning directions. By configuring it in this way, the same effect as when the deformable lens 103 is configured as a toroidal lens can be obtained.

[0094] Furthermore, the deformable lens 103 can be either a diffractive optical element with different patterns in the scanning direction and the non-scanning direction, or a diffractive optical element with patterns arranged in one of the scanning direction and the non-scanning direction.

[0095] The deformable lens 103 is preferably positioned closer to the emission-side integrator 102 than the incident-side integrator 101. This is because light rays emitted from the incident-side elemental lens 101a are refracted by the deformable lens 103 and, while changing their distance from the optical axis, are incident on the corresponding emission-side elemental lens 102a. The change in the distance of the light rays emitted from the deformable lens 103 from the optical axis increases proportionally to the distance from the deformable lens 103 to the emission-side integrator 102. Therefore, when the distance between the deformable lens 103 and the emission-side integrator 102 is large, the light rays emitted from the incident-side elemental lens 101a are not incident on the corresponding emission-side elemental lens 102a but are incident on the adjacent elemental lens 102a. In this case, this leads to a decrease in illumination efficiency and a decrease in the uniformity of light intensity distribution on the illuminated surface. Therefore, the deformable lens 103 is preferably positioned near the emission-side integrator 102.

[0096] In this embodiment, an example is illustrated by arranging 5 element lenses in the scanning direction and 5 element lenses in the non-scanning direction in each of the incident-side integrating circuit 101 and the emission-side integrating circuit 102 (5×5 arrangement). However, the number of element lenses is not limited to this; it can be more or less than a 5×5 arrangement. Furthermore, the number of element lenses can be odd or even. Moreover, the number of element lenses in the scanning and non-scanning directions can be different, and the arrangement period of the element lenses can be significantly changed in both directions. Thus, the structure of the element lenses can be appropriately selected.

[0097] Furthermore, the element lens constituting the optical integrator 100 is not limited to a spherical lens. To adjust the light intensity distribution on the illuminated surface, the element lens can be an aspherical lens, or a diffractive lens such as a Fresnel zone plate or a Kinoform. Moreover, to adjust the aspect ratio of the light intensity distribution (the ratio of the width of the light intensity distribution in the scanning direction to the width in the non-scanning direction on the illuminated surface), the element lens can also be a tortuous lens, a cylindrical lens, or a deformable lens.

[0098] Reference Figure 8 as well as Figure 9 This explains the case where the lens element constituting the optical integrator is a cylindrical lens. Figure 8 as well as Figure 9 This is a schematic cross-sectional view showing the structure from the optical integrator 200 to the intermediate illumination surface 14 when the element lens constituting the optical integrator is a cylindrical lens. Figure 8 The cross-section in the XY plane is shown. Figure 9 The cross-section in the XZ plane is shown.

[0099] The optical integrator 200 consists of cylindrical lens arrays 201 and 202 on the incident side and cylindrical lens arrays 203 and 204 on the emission side. A deformable lens 103 is disposed between the cylindrical lens arrays 201 and 202 on the incident side and the cylindrical lens arrays 203 and 204 on the emission side. The deformable lens 103 is a cylindrical lens with positive optical power in the scanning direction.

[0100] Cylindrical lens arrays 201 and 203 are cylindrical lens arrays obtained by arranging element lenses that have curvature only in the scanning direction (Z direction) in the scanning direction. Cylindrical lens arrays 202 and 204 are cylindrical lens arrays obtained by arranging element lenses that have curvature only in the non-scanning direction (Y direction) in the non-scanning direction.

[0101] The element lenses of the cylindrical lens array 201 on the incident side and the element lenses of the cylindrical lens array 203 on the emission side are in a corresponding relationship. In addition, the element lenses of the cylindrical lens array 202 on the incident side and the element lenses of the cylindrical lens array 204 on the emission side are in a corresponding relationship.

[0102] The light incident on the optical integrator 200 is split into many beams by the cylindrical lens arrays 201 and 202 on the incident side in the scanning direction and the non-scanning direction, respectively. The light is emitted from each element lens of the cylindrical lens arrays 201 and 202 on the incident side, and is incident on the element lenses of the corresponding cylindrical lens arrays 203 and 204 on the emission side, respectively, and is emitted toward the condenser lens 12.

[0103] An aperture stop 11 is disposed near the exit surface of the optical integrator 200 (cylindrical lens array 204 on the exit side). The position of the aperture stop 11 corresponds to the pupil surface of the condenser lens 12.

[0104] The light emitted from the optical integrator 200 is focused by the condenser lens 12, illuminating the intermediate illumination surface 14 in an overlapping manner. At this time, the deformable lens 103 has no optical power in the non-scanning direction, so the exit angle of the light rays emitted from the cylindrical lens array 202 on the incident side does not change. Therefore, as... Figure 8 As shown, light rays incident perpendicularly to the center of the optical surface of each element lens of the cylindrical lens array 202 on the incident side are emitted perpendicularly from the center of the optical surface of the corresponding element lens of the cylindrical lens array 204 on the exiting side. In other words, light rays incident perpendicularly to the center of the optical surface of each element lens of the cylindrical lens array 202 on the incident side are emitted from the optical integrator 200 parallel to the optical axis (X-axis) of the illumination optical system IL. The light rays emitted parallel to the optical axis of the illumination optical system IL are converged by the condenser lens 12 with a focal length of fc to a position at a distance fc from the condenser lens 12 (principal point).

[0105] The intermediate illumination surface 14 is located at a distance fc from the principal point of the condenser lens 12. Therefore, the light intensity distribution in the non-scanning directions of the intermediate illumination surface 14 is as follows: Figure 8 The distribution shown is roughly rectangular.

[0106] Next, refer to Figure 9 This describes the light intensity distribution along the scanning direction in the intermediate illumination surface 14. Light rays incident perpendicularly to the center of the optical surface of each element lens in the cylindrical lens array 201 on the incident side, such as... Figure 9 The light rays are refracted by the deformable lens 103 and incident on the exit side of the cylindrical lens array 203. As a result, the light rays refracted by the deformable lens 103 are incident at a position offset from the center of the optical surface of the corresponding element lens of the exit side cylindrical lens array 203, which is the element lens of each of the element lenses of the incident side cylindrical lens array 201. Then, the light rays incident on the exit side cylindrical lens arrays 203 and 204 are further refracted by each element lens and emitted.

[0107] The incident angle of light rays towards each element lens of the cylindrical lens array 203 on the emission side, as well as the offset of the incident position of the light rays from the center of the optical surface towards the scanning direction, both become larger the further away from the optical axis. Therefore, the exit angle of light rays from each element lens of the cylindrical lens array 203 on the emission side becomes larger the further away from the optical axis. In other words, the exit angle of light rays from each element lens of the cylindrical lens array 203 on the emission side changes monotonically with distance from the optical axis. As a result, light rays that are perpendicularly incident on the center of the optical surface of each element lens in the cylindrical lens array 201 on the incident side are focused and emitted towards the condenser lens 12.

[0108] Therefore, the focusing position of the light rays gathered by the condenser lens 12 is located at a distance d closer (towards the light source) than the intermediate illumination surface 14, which is located at a distance fc from the condenser lens 12. Consequently, the light intensity distribution in the scanning direction at the distance d from the intermediate illumination surface 14 on the light source side is approximately rectangular. On the other hand, at the intermediate illumination surface 14, the light intensity distribution is approximately trapezoidal in the scanning direction, located a distance d away from the focusing position.

[0109] Furthermore, if the field aperture 13, which defines the illumination area for the scanning direction and forms a roughly trapezoidal light intensity distribution, is positioned at the focusing position in the scanning direction (at a distance d from the central illumination surface 14 on the light source side), the light blocked by the field aperture 13 is suppressed to a minimum. Therefore, even when the optical integrator is composed of a cylindrical lens array, a roughly trapezoidal light intensity distribution can be formed in the scanning direction while minimizing the reduction in illumination efficiency.

[0110] In this embodiment, cylindrical lens arrays 201, 202, 203, and 204 are arranged sequentially from the incident side toward the emission side. Cylindrical lens array 201 is an array of cylindrical lenses arranged in the scanning direction on the incident side, and cylindrical lens array 202 is an array of cylindrical lenses arranged in the non-scanning direction on the incident side. Cylindrical lens array 203 is an array of cylindrical lenses arranged in the scanning direction on the emission side, and cylindrical lens array 204 is an array of cylindrical lenses arranged in the non-scanning direction on the emission side. However, this configuration is not limited to this; various configurations can be implemented as long as the relationship between the incident side and the emission side is reversed.

[0111] For example, the cylindrical lens array 202 arranged in the non-scanning direction on the incident side may be positioned closer to the light source than the cylindrical lens array 201 arranged in the scanning direction on the incident side. Alternatively, the cylindrical lens array 204 arranged in the non-scanning direction on the emission side may be positioned closer to the light source than the cylindrical lens array 203 arranged in the scanning direction on the emission side.

[0112] Furthermore, it is also possible to have a structure in which the cylindrical lens arrays 201 and 203 arranged in the scanning direction on the incident and emission sides are positioned closer to the light source than the cylindrical lens array 202 arranged in the non-scanning direction on the incident side. In such a case, the deformable lens 103 can be arranged in at least one of (i) and (ii) below.

[0113] (i) Between the cylindrical lens array 201 and the cylindrical lens array 203 arranged in the scanning direction

[0114] (ii) Between the cylindrical lens array 202 and the cylindrical lens array 204 arranged in the non-scanning direction

[0115] Alternatively, deformable lenses 103 can be configured in (i) and (ii) respectively. However, for deformable lenses 103 configured closer to the light source side than cylindrical lens arrays 201 or 203 on the incident side, there is no effect on changing the focusing position of condenser lens 12 with respect to the arrangement direction of cylindrical lens arrays 201 or 203.

[0116] Furthermore, this embodiment illustrates, by way of example, that the individual element lenses constituting the optical integrator 100 or 200 are separately divided, but it is not limited thereto. For example, multiple element lenses can be integrally formed in a single optical element using techniques such as cutting, forming, and etching. The structure of the optical integrator can be modified and altered in various ways within its essential scope.

[0117] Thus, in this embodiment, the illumination optical system IL enables the reduction of light intensity distribution caused by pulse oscillations with minimal light loss, without altering the transfer characteristics of the pattern transferred to the substrate in the scanning and non-scanning directions. Furthermore, the exposure apparatus EX equipped with such an illumination optical system IL provides cost-effective and high-quality equipment (semiconductor devices, liquid crystal display devices, flat panel displays, etc.) with high throughput.

[0118] <Second Implementation Method>

[0119] Figure 10 This is a schematic cross-sectional view showing another structure of the exposure apparatus EX as one aspect of the present invention. In this embodiment, the exposure apparatus EX is compared to... Figure 1 The exposure apparatus EX shown has a different structure from the illumination optical system IL. Specifically, in this embodiment, the illumination optical system IL does not have a deformable lens 103, and its structure differs from that of the optical integrator 100, which forms a plurality of secondary light sources and guides them to the condenser lens 12 in accordance with the intensity distribution of the incident light.

[0120] The structure of the optical integrator 100 in the illumination optical system IL is described below. Figure 11 as well as Figure 12 This is a schematic cross-sectional view showing the structure of a portion of the illumination optical system IL, specifically, the structure from the optical integrator 100 to the intermediate illumination surface 14. Figure 11 The cross-section in the XY plane is shown. Figure 12 The cross-section in the XZ plane is shown.

[0121] The optical integrator 100 is similar to that in the first embodiment, consisting of an incident-side integrating circuit 101 as an incident-side optical element and an exit-side integrating circuit 102 as an exit-side optical element. The incident-side integrating circuit 101 and the exit-side integrating circuit 102 are lens arrays (fly-eye lenses) arranged in the scanning direction (Z direction) and the non-scanning direction (Y direction) which is orthogonal (crossed) to the scanning direction.

[0122] The incident-side integrating circuit 101 includes a plurality of incident-side element lenses (first optical elements) 101a arranged periodically in the scanning direction (first direction) and the non-scanning direction (second direction). The emission-side integrating circuit 102 includes a plurality of emission-side element lenses (second optical elements) 102a arranged corresponding to each of the plurality of incident-side element lenses 101a. Furthermore, element lenses (not shown) are also arranged outside the XY and XZ planes. Figure 11 as well as Figure 12The image illustrates, by way of example, a lens array consisting of five element lenses arranged in the scanning direction and five element lenses arranged in the non-scanning direction in each of the incident-side integrating circuit 101 and the emission-side integrating circuit 102.

[0123] The light incident on the optical integrator 100 is split into many beams by the incident-side integrator circuit 101. The beams split by the incident-side integrator circuit 101 are emitted from the individual element lenses 101a of the incident-side integrator circuit 101, and are respectively incident on the element lenses 102a of the corresponding emission-side integrator circuit 102, and are emitted toward the condenser lens 12.

[0124] An aperture stop 11 is disposed near the emission surface of the optical integrator 100 (emission-side integrator circuit 102). The position of the aperture stop 11 corresponds to the pupil surface of the condenser lens 12.

[0125] The light emitted from the optical integrator 100 is focused by the condenser lens 12, illuminating the intermediate illumination surface 14 in an overlapping manner. For example... Figure 11 As shown, light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a in the incident-side integrating circuit 101 are emitted perpendicularly from the center of the optical surface of the corresponding element lens 102a in the exit-side integrating circuit 102. In other words, light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a in the incident-side integrating circuit 101 are emitted from the optical integrator 100 parallel to the optical axis (X-axis) of the illumination optical system IL. The light rays emitted parallel to the optical axis of the illumination optical system IL are focused by the condenser lens 12 with a focal length of fc to a position at a distance fc from the condenser lens 12 (principal point).

[0126] The intermediate illumination surface 14 is located at a distance fc from the principal point of the condenser lens 12. Therefore, the light intensity distribution in the non-scanning directions of the intermediate illumination surface 14 is as follows: Figure 2 The distribution shown is roughly rectangular.

[0127] Here, we consider a case where the element lenses in the incident-side integrating circuit 101 and the emission-side integrating circuit 102 have the same arrangement period, and the field aperture 13, which forms a trapezoidal light intensity distribution in the scanning direction, is positioned separate from the intermediate illumination surface 14 in the optical axis direction. In this case, a portion of the light must be blocked by the field aperture 13, resulting in a reduction in illumination efficiency.

[0128] Furthermore, similar to the first embodiment, consider the case where the field aperture 13 is positioned at a distance fc from the condenser lens 12 (the focusing position), and the intermediate illumination surface 14, which is optically conjugate with the original image 18, is positioned separate from the focusing position in the optical axis direction. In this case, the light blocked by the field aperture 13 can be suppressed to a minimum, but the light intensity distribution in the non-scanning direction of the intermediate illumination surface 14 also becomes approximately trapezoidal. Therefore, in order to uniformly illuminate the original image 18, the area of ​​the oblique edge of the light intensity distribution must be blocked by the shielding unit 15, resulting in a reduction in illumination efficiency.

[0129] Therefore, in order to suppress the reduction of illumination efficiency while forming a roughly trapezoidal light intensity distribution in the scanning direction, it is preferable to focus the light in the non-scanning direction to the position of the intermediate illumination surface 14 which is optically conjugate with the original 18, and focus the light in the scanning direction to the position of the field aperture 13.

[0130] On the other hand, consider the case where the arrangement period of the element lenses in the incident-side integrating circuit 101 and the emission-side integrating circuit 102 are different, as in this embodiment. Figure 3 In the incident-side integrator circuit 101, the arrangement period of the element lens is longer than that of the element lens in the emission-side integrator circuit 102.

[0131] In this case, the light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a in the incident-side integrating circuit 101 are as follows: Figure 12 The light rays incident on the output side integrator 102 are then emitted from a position offset from the center of the optical surface of each corresponding element lens 102a.

[0132] The incident angle of light rays towards each element lens 102a of the emission-side integrator circuit 102, as well as the offset of the incident position of the light rays from the center of the optical surface, both increase with distance from the optical axis. Therefore, the exit angle of light rays from each element lens 102a of the emission-side integrator circuit 102 increases with distance from the optical axis. In other words, the exit angle of light rays from each element lens 102a of the emission-side integrator circuit 102 changes monotonically with distance from the optical axis. As a result, light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a in the incident-side integrator circuit 101 are focused and emitted towards the condenser lens 12.

[0133] When the light rays emitted from the center of the optical surface of each of the element lenses 101a incident perpendicularly to the incident side and from each of the element lenses 102a on the exit side are extended, as... Figure 13As shown, they intersect at a point O on the optical axis located at a distance s from the principal point of the condenser lens 12 on the original side. This is equivalent to the light source of the object relative to the condenser lens 12 being located at a distance s from the condenser lens 12 on the original side.

[0134] Therefore, the focusing position of the light rays gathered by the condenser lens 12 is located at a distance d closer (towards the light source) than the intermediate illumination surface 14, which is located at a distance fc from the condenser lens 12. Consequently, the light intensity distribution in the scanning direction at the distance d from the intermediate illumination surface 14 on the light source side is approximately rectangular. On the other hand, at the intermediate illumination surface 14, the light intensity distribution is approximately trapezoidal in the scanning direction, located a distance d away from the focusing position.

[0135] Furthermore, if the field aperture 13, which defines the illumination area for the scanning direction and forms a roughly trapezoidal light intensity distribution, is positioned at the focusing position in the scanning direction (at a distance d from the central illumination surface 14 on the light source side), the light blocked by the field aperture 13 is suppressed to a minimum. Therefore, it is possible to form a roughly trapezoidal light intensity distribution in the scanning direction while minimizing the reduction in illumination efficiency.

[0136] The width L of the hypotenuse of the roughly trapezoidal light intensity distribution is represented by the illumination NA (NAIL) in the intermediate illumination surface 14 and the distance d by the above equation (1).

[0137] Therefore, based on the width L of the hypotenuse of the trapezoidal shape corresponding to the desired light intensity distribution and the illumination NA, the position of the field aperture 13 or the distance d from the central illumination surface 14 to the focusing position related to the scanning direction can be determined.

[0138] Furthermore, regarding the element lenses in the incident-side integrator circuit 101 and the emission-side integrator circuit 102, only the arrangement period in the non-scanning direction is different, but thus the illumination NA in the intermediate illumination surface 14 will not be different in the scanning direction and the non-scanning direction.

[0139] Figure 14 This is a schematic cross-sectional view showing the illuminating light rays at a point on the intermediate illumination surface 14 in the XZ section. The condenser lens 12 has rotationally symmetric optical power, so the illuminating light rays at a point on the intermediate illumination surface 14 are the same in both the scanning and non-scanning directions. The illumination NA (NAIL) is determined by the diameter EA of the aperture stop 11 and the focal length fc of the condenser lens 12, as expressed by equation (2) above.

[0140] Therefore, if the diameter EA of the aperture stop 11 and the focal length fc of the condenser lens 12 are the same in the scanning direction and the non-scanning direction (aperture stop 11 and condenser lens 12 are rotationally symmetrical), then the illumination NA is the same in the scanning direction and the non-scanning direction.

[0141] Here, to make the arrangement periods of the element lenses in the incident-side integrating circuit 101 and the emission-side integrating circuit 102 different, the sizes of the element lenses in the incident-side integrating circuit 101 and the emission-side integrating circuit 102 can also be different. To make the arrangement periods different in the scanning direction, the widths of the element lenses in the scanning direction can be different. Alternatively, the arrangement period of the element lenses can be adjusted by making the sizes of the element lenses in the incident-side integrating circuit 101 and the emission-side integrating circuit 102 the same and by providing spacers between each element lens. By using spacers, the element lenses in the incident-side integrating circuit 101 and the emission-side integrating circuit 102 can be made the same, which can be expected to reduce the management and manufacturing costs of the components.

[0142] In this embodiment, the case where the field aperture 13 is positioned near the intermediate illumination surface 14 is described, but it is not limited to this. For example, the field aperture 13 may be positioned near the original image 18, which is optically conjugate with the intermediate illumination surface 14, or it may be positioned no closer to the light source side than the intermediate illumination surface 14, but closer to the original image side than the intermediate illumination surface 14.

[0143] When the field aperture 13 is positioned closer to the original image than the intermediate illumination surface 14, the structure of the optical integrator 100 in the non-scanning direction is the same as the structure of the optical integrator 100 when the field aperture 13 is positioned near the intermediate illumination surface 14. On the other hand, regarding the scanning direction, as... Figure 15 As shown, the arrangement period of the element lens in the incident-side integrator circuit 101 is shorter than that of the element lens in the emission-side integrator circuit 102.

[0144] Therefore, light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a in the incident-side integrating circuit 101 are emitted toward the condenser lens 12 while diverging. When the light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a in the incident side and emitted from each of the element lenses 102a in the emission side are extended, as... Figure 16 As shown, they intersect at a point O on the optical axis located at a distance s from the principal point of the condenser lens 12 on the light source side. This is equivalent to the light source, which is the object relative to the condenser lens 12, being located at a distance s from the condenser lens 12 on the light source side.

[0145] Therefore, the focusing position of the light rays gathered by the condenser lens 12 is located at a distance d further inward (on the original side) than the intermediate illumination surface 14, which is located at a distance fc from the condenser lens 12. Consequently, the light intensity distribution in the scanning direction at the distance d from the intermediate illumination surface 14 on the original side is approximately rectangular. On the other hand, at the intermediate illumination surface 14, the light intensity distribution is approximately trapezoidal in the scanning direction, located a distance d away from the focusing position.

[0146] Furthermore, if the field aperture 13 is positioned at a distance d from the central illumination surface 14 on the side of the original image, the light blocked by the field aperture 13 is suppressed to a minimum. Therefore, it is possible to form a roughly trapezoidal light intensity distribution in the scanning direction while minimizing the reduction in illumination efficiency.

[0147] However, in the structure where the light rays from the center of the optical surface of each of the element lenses 101a incident perpendicularly to the incident side diverge while exiting toward the condenser lens 12, the effective diameter of the condenser lens 12 becomes larger. Therefore, the structure where the light rays from the center of the optical surface of each of the element lenses 101a incident perpendicularly to the incident side converge while exiting toward the condenser lens 12 is advantageous from the perspective of manufacturing cost and the performance of the illumination optics system IL.

[0148] In this embodiment, the arrangement periods of the element lenses in the incident-side integration circuit 101 and the emission-side integration circuit 102 are different for the scanning direction in the optical integrator 100, but this is not a limitation. That is, the arrangement periods of the element lenses in the incident-side integration circuit 101 and the emission-side integration circuit 102 may also be different for the non-scanning direction.

[0149] In this case, the field aperture 13 is positioned at a distance fc from the condenser lens 12. Furthermore, the intermediate illumination surface 14 is set at a predetermined distance d away, and the alignment period of the element lenses in the non-scanning direction is set in such a way that the focusing position in the non-scanning direction is aligned with the intermediate illumination surface 14.

[0150] Alternatively, the arrangement period of the element lenses in the incident-side integrating circuit 101 and the emission-side integrating circuit 102 can be different for each of the scanning and non-scanning directions. In this case, the positions of the field aperture 13 and the intermediate illumination surface 14 can be set to positions that are respectively far from the position of the condenser lens 12 at a predetermined distance fc. Moreover, the arrangement period of the element lenses in the non-scanning direction can be set for each of the scanning and non-scanning directions such that the focusing positions of the condenser lens 12 in the scanning and non-scanning directions are respectively aligned with the field aperture 13 and the intermediate illumination surface 14.

[0151] For example, the field aperture 13 is positioned further from the light source than the distance fc from the condenser lens 12, and the intermediate illumination surface 14 is positioned further from the original image than the distance fc from the condenser lens 12. Furthermore, for the scanning direction, the arrangement period of the element lenses in the incident-side integrating circuit 101 is longer than the arrangement period of the element lenses in the emission-side integrating circuit 102. For the non-scanning direction, the arrangement period of the element lenses in the incident-side integrating circuit 101 is shorter than the arrangement period of the element lenses in the emission-side integrating circuit 102.

[0152] Here, the relationship between the focal length fc of the condenser lens 12, the focusing position where the light rays incident perpendicularly to the center of the optical surface of each of the element lenses in the incident-side integrating circuit 101 are focused by the condenser lens 12, and the arrangement period of the element lenses is explained. When the light rays incident perpendicularly to the center of the optical surface of each of the element lenses 101a in the incident side and emitted from each of the element lenses 102a in the emission side are extended, they intersect at a point O on the optical axis located at a distance s from the principal point of the condenser lens 12 on the original side. The position of point O can be regarded as the object position of the condenser lens 12. At this time, the direction of light propagation (positive direction of the X-axis) is set to positive, and the imaging position fc+d where the object at point O is imaged by the condenser lens 12 with focal length fc is represented by the following equation (3).

[0153] 1 / (fc+d)=(1 / s)+(1 / fc)···(3)

[0154] That is, when s is infinitely large, d = 0, and the focusing position coincides with the focal point of the focusing lens 12.

[0155] Next, consider the relationship between s and the arrangement period of the element lenses on the incident and exit sides of the optical integrator. If we use the distance h from the optical axis of the ray that is perpendicularly incident on the center of the optical surface of each of the element lenses 101a on the incident side and the angle θ from which the ray exits from the element lens 102a on the exit side, then when θ is sufficiently small, s is represented by the following equation (4).

[0156] s=h / θ···(4)

[0157] Here, when the arrangement period of the element lens of the incident side integrator circuit 101 is set to Pi, the element lens arranged on the optical axis is set to the 0th, and the element lens of the incident light is arranged in the nth position in the arrangement direction, h is represented by the following equation (5).

[0158] h = n × Pi···(5)

[0159] Here, when the number of element lenses arranged in the periodic direction is odd, consider setting the element lens arranged on the optical axis as the 0th element lens, and the element lens arranged adjacent to this element lens as the 1st element lens. That is, consider the distance h = Pi from the optical axis of the light ray that is perpendicularly incident on the center of the optical surface of the 1st element lens.

[0160] On the other hand, when the number of element lenses arranged in the periodic direction is even, there are no element lenses on the optical axis. Therefore, the element lens that is adjacent to the element lens across the optical axis is considered as the first element lens. Moreover, the distance h = 0.5 × Pi from the optical axis of the light ray that is perpendicularly incident on the center of the optical surface of this element lens is considered.

[0161] On the other hand, θ is represented by the focal length fo of the element lens 102a on the emission side, the offset e of the light rays that are perpendicularly incident on the center of the optical surface of each of the element lenses 101a on the incident side and incident on the element lens 102a on the emission side from the center of the optical surface of that element lens 102a.

[0162] When e is sufficiently small, it is represented by the following equation (6).

[0163] θ=e / fo···(6)

[0164] In addition, the arrangement period of the element lens of the emission side integrator circuit 102 is set to Po, which is represented by the following equation (7).

[0165] e=(Po-Pi)×n···(7)

[0166] Equations (4) to (7) can be expressed by the following equation (8).

[0167] s=(Pi×fо) / (Po-Pi)···(8)

[0168] By substituting equation (8) into equation (3), d can be obtained. That is, the focusing position of the condenser lens 12 can be determined by the focal length fc of the condenser lens 12, the arrangement periods Pi and Po of the element lenses of the incident-side integrating circuit 101 and the exit-side integrating circuit 102, and the focal length fo of the exit-side element lens 102a. By adjusting the arrangement periods Pi and Po of the element lenses of the incident-side integrating circuit 101 and the exit-side integrating circuit 102, d can be changed.

[0169] Here, as the absolute value of the difference |Po-Pi| between the arrangement period Pi of the element lenses in the incident-side integrator circuit 101 and the arrangement period Po of the element lenses in the exit-side integrator circuit 102 increases, the offset e also increases. When |e| exceeds Po / 2, light rays perpendicularly incident on the center of the optical surface of each of the element lenses 101a on the incident side cannot be incident on the corresponding element lens 102a on the exit side. As a result, this leads to a decrease in illumination efficiency and a decrease in the uniformity of light intensity distribution in the illuminated surface, which is therefore undesirable.

[0170] Therefore, it is preferable to satisfy the following equation (9).

[0171] |e|≤Po / 2···(9)

[0172] That is, the number of element lenses of the optical integrator is set to m, preferably satisfying the condition expressed by the following equation (10).

[0173] Po / 2≥|(Po-Pi)|×(m-1) / 2···(10)

[0174] In this embodiment, an example is illustrated where each of the incident-side integrating circuit 101 and the emission-side integrating circuit 102 is configured with 5 element lenses arranged in the scanning direction and 5 element lenses arranged in the non-scanning direction (5×5 arrangement). However, the number of element lenses is not limited to this; it can be more or less than a 5×5 arrangement. Furthermore, the number of element lenses can be odd or even. Moreover, the number of element lenses arranged in the scanning and non-scanning directions can be different, and the arrangement period of the element lenses can be significantly changed in both directions. Thus, the structure of the element lenses can be appropriately selected.

[0175] Furthermore, the element lens constituting the optical integrator 100 is not limited to a spherical lens. In order to adjust the light intensity distribution in the illuminated surface, the element lens can be set as an aspherical lens, or it can be set as a diffractive lens such as a Fresnel zone plate or a Cano lens. Moreover, in order to adjust the aspect ratio of the light intensity distribution (the ratio of the width of the light intensity distribution in the scanning direction to the width in the non-scanning direction), the element lens can also be set as a toric lens, cylindrical lens, or other deformable lens.

[0176] Reference Figure 17 as well as Figure 18 This explains the case where the lens element constituting the optical integrator is a cylindrical lens. Figure 17 as well as Figure 18 This is a schematic cross-sectional view showing the structure from the optical integrator 200 to the intermediate illumination surface 14 when the element lens constituting the optical integrator is a cylindrical lens. Figure 17 The cross-section in the XY plane is shown. Figure 18 The cross-section in the XZ plane is shown.

[0177] The optical integrator 200 consists of cylindrical lens arrays 201 and 202 on the incident side and cylindrical lens arrays 203 and 204 on the exit side. Cylindrical lens arrays 201 and 203 are cylindrical lens arrays formed by arranging element lenses with curvature only in the scanning direction (Z direction) in the scanning direction. Cylindrical lens arrays 202 and 204 are cylindrical lens arrays formed by arranging element lenses with curvature only in the non-scanning direction (Y direction) in the non-scanning direction.

[0178] The element lenses of the cylindrical lens array 201 on the incident side and the element lenses of the cylindrical lens array 203 on the emission side are in a corresponding relationship. In addition, the element lenses of the cylindrical lens array 202 on the incident side and the element lenses of the cylindrical lens array 204 on the emission side are in a corresponding relationship.

[0179] The light incident on the optical integrator 200 is split into many beams by the cylindrical lens arrays 201 and 202 on the incident side in the scanning direction and the non-scanning direction, respectively. The light is emitted from each element lens of the cylindrical lens arrays 201 and 202 on the incident side, and is incident on the element lenses of the corresponding cylindrical lens arrays 203 and 204 on the emission side, respectively, and is emitted toward the condenser lens 12.

[0180] An aperture stop 11 is disposed near the exit surface of the optical integrator 200 (cylindrical lens array 204 on the exit side). The position of the aperture stop 11 corresponds to the pupil surface of the condenser lens 12.

[0181] The light emitted from the optical integrator 200 is focused by the condenser lens 12, illuminating the intermediate illumination surface 14 in an overlapping manner. For example... Figure 17 As shown, regarding the non-scanning direction, the arrangement period of the element lenses in the cylindrical lens array 202 on the incident side is equal to the arrangement period of the element lenses in the cylindrical lens array 204 on the exiting side. Therefore, light rays that are perpendicularly incident on the center of the optical surface of each element lens in the cylindrical lens array 202 on the incident side are emitted perpendicularly from the center of the corresponding optical surface of each element lens in the cylindrical lens array 204 on the exiting side. In other words, light rays that are perpendicularly incident on the center of the optical surface of each element lens in the cylindrical lens array 202 on the incident side are emitted from the optical integrator 200 parallel to the optical axis (X-axis) of the illumination optical system IL. The light rays emitted parallel to the optical axis of the illumination optical system IL are focused by the condenser lens 12 with a focal length of fc to a position at a distance fc from the condenser lens 12 (principal point).

[0182] The intermediate illumination surface 14 is located at a distance fc from the principal point of the condenser lens 12. Therefore, the light intensity distribution in the non-scanning directions of the intermediate illumination surface 14 is as follows: Figure 17 The distribution shown is roughly rectangular.

[0183] Next, refer to Figure 18 Explain the light intensity distribution along the scanning direction in the intermediate illumination surface 14. For example... Figure 18 As shown, regarding the scanning direction, the arrangement period of the element lenses in the incident cylindrical lens array 201 is longer than that of the element lenses in the exiting cylindrical lens array 203. Therefore, the light rays incident perpendicularly to the center of the optical surface of each element lens in the incident cylindrical lens array 201 are as follows: Figure 18 The incident light is incident on the exiting cylindrical lens array 203. As a result, the light is incident at a position offset from the center of the optical surface of the corresponding element lens of the exiting cylindrical lens array 203, which is the element lens of each of the element lenses of the incident cylindrical lens array 201. Then, the light incident on the exiting cylindrical lens arrays 203 and 204 is further refracted by each element lens and emitted.

[0184] The incident angle of light rays towards each element lens of the cylindrical lens array 203 on the emission side, as well as the offset of the incident position of the light rays from the center of the optical surface towards the scanning direction, both become larger the further away from the optical axis and towards the periphery. Therefore, the exit angle of light rays from each element lens of the cylindrical lens array 203 on the emission side becomes larger the further away from the optical axis. In other words, the exit angle of light rays from each element lens of the cylindrical lens array 203 on the emission side changes monotonically with distance from the optical axis. As a result, light rays that are perpendicularly incident on the center of the optical surface of each element lens in the cylindrical lens array 201 on the incident side are focused and emitted towards the condenser lens 12.

[0185] Therefore, the focusing position of the light rays gathered by the condenser lens 12 is located at a distance d closer (towards the light source) than the intermediate illumination surface 14, which is located at a distance fc from the condenser lens 12. Consequently, the light intensity distribution in the scanning direction at a distance d from the intermediate illumination surface 14 on the light source side is approximately rectangular. On the other hand, in the intermediate illumination surface 14, the light intensity distribution at a distance d from the focusing position is approximately trapezoidal in the scanning direction.

[0186] Furthermore, if the field aperture 13, which defines the illumination area for the scanning direction and forms a roughly trapezoidal light intensity distribution, is positioned at the focusing position in the scanning direction (at a distance d from the central illumination surface 14 on the light source side), the light blocked by the field aperture 13 is suppressed to a minimum. Therefore, even when the optical integrator is composed of a cylindrical lens array, a roughly trapezoidal light intensity distribution can be formed in the scanning direction while minimizing the reduction in illumination efficiency.

[0187] In this embodiment, cylindrical lens arrays 201, 202, 203, and 204 are arranged sequentially from the incident side toward the emission side. Cylindrical lens array 201 is an array of cylindrical lenses arranged in the scanning direction on the incident side, and cylindrical lens array 202 is an array of cylindrical lenses arranged in the non-scanning direction on the incident side. Cylindrical lens array 203 is an array of cylindrical lenses arranged in the scanning direction on the emission side, and cylindrical lens array 204 is an array of cylindrical lenses arranged in the non-scanning direction on the emission side. However, this configuration is not limited to this; various configurations can be implemented as long as the relationship between the incident side and the emission side is reversed.

[0188] For example, the cylindrical lens array 202 arranged in the non-scanning direction on the incident side may be positioned closer to the light source than the cylindrical lens array 201 arranged in the scanning direction on the incident side. Alternatively, the cylindrical lens array 204 arranged in the non-scanning direction on the emission side may be positioned closer to the light source than the cylindrical lens array 203 arranged in the scanning direction on the emission side.

[0189] Furthermore, it is also possible to configure the cylindrical lens arrays 201 and 203 arranged in the scanning direction on the incident side and the emission side to be closer to the light source side than the cylindrical lens array 202 arranged in the non-scanning direction on the incident side.

[0190] Furthermore, this embodiment illustrates, by way of example, that the individual element lenses constituting the optical integrator 100 or 200 are separately divided, but it is not limited thereto. For example, multiple element lenses can be integrally formed in a single optical element using techniques such as cutting, forming, and etching. The structure of the optical integrator can be modified and altered in various ways within its essential scope.

[0191] Thus, in this embodiment, the illumination optical system IL enables the reduction of light intensity distribution caused by pulse oscillations with minimal light loss, without altering the transfer characteristics of the pattern transferred to the substrate in the scanning and non-scanning directions. Furthermore, the exposure apparatus EX equipped with such an illumination optical system IL provides cost-effective and high-quality equipment (semiconductor devices, liquid crystal display devices, flat panel displays, etc.) with high throughput.

[0192] <Third Implementation Method>

[0193] The article manufacturing method according to embodiments of the present invention is suitable for manufacturing articles such as flat panel displays, liquid crystal display elements, semiconductor elements, and MEMS. The manufacturing method includes a step of exposing a substrate coated with a photosensitive agent using the aforementioned exposure apparatus EX; and a step of developing the exposed photosensitive agent. Furthermore, the developed photosensitive agent pattern is used as a mask to perform etching, ion implantation, and other processes on the substrate to form a circuit pattern. These exposure, development, and etching processes are repeated to form a circuit pattern consisting of multiple layers on the substrate. In subsequent processes, the substrate with the circuit pattern is cut (processed) and chips are mounted, bonded, and inspected. Additionally, the manufacturing method may include other known processes (oxidation, film formation, vapor deposition, doping, planarization, resist stripping, etc.). Compared to conventional methods, the article manufacturing method of this embodiment is advantageous in at least one aspect of article performance, quality, productivity, and production cost.

[0194] The invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the claims are appended to disclose the scope of the invention.

Claims

1. An illumination optical system for illuminating a surface, characterized in that, have: An optical integrator that uses light from a light source to form a secondary light source; as well as A condenser lens that illuminates the surface to be illuminated using light from the optical integrator. The optical integrator includes: an incident-side optical element, with a plurality of first optical elements arranged thereon; And the emission-side optical elements, including a plurality of second optical elements arranged corresponding to each of the plurality of first optical elements. The plurality of first optical elements and the plurality of second optical elements are periodically arranged in a first direction and in a second direction intersecting the first direction. The arrangement period of the plurality of first optical elements and the arrangement period of the plurality of second optical elements are different with respect to at least one of the first and second directions. The focusing position of the light emitted from the condenser lens is different in the first direction and the second direction.

2. The illumination optical system according to claim 1, characterized in that, Each of the incident-side optical element and the emitting-side optical element is composed of a fly-eye lens having optical power in the first direction and the second direction.

3. The illumination optical system according to claim 1, characterized in that, Each of the incident-side optical element and the emitting-side optical element is composed of a cylindrical lens having optical power in the first direction and a cylindrical lens having optical power in the second direction.

4. The illumination optical system according to claim 1, characterized in that, The optical integrator is configured such that the angle of light rays incident perpendicularly to the center of the optical surface of each of the plurality of first optical elements and emitted from each of the plurality of second optical elements varies monotonically from the center of the optical surface of the optical integrator toward the periphery with respect to at least one of the first and second directions.

5. The illumination optical system according to claim 1, characterized in that, When the arrangement period of the plurality of first optical elements is set to Pi, the arrangement period of the plurality of second optical elements is set to Po, and the number of arrangements of the plurality of first optical elements and the plurality of second optical elements is set to m, the following condition is satisfied. Po / 2≥|(Po-Pi)|×(m-1) / 2.

6. An exposure apparatus for exposing a substrate via the original image while moving an original image and a substrate in a scanning direction, the exposure apparatus characterized by comprising: The illumination optical system according to any one of claims 1 to 5 illuminates the original plate disposed on the illuminated surface; and A projection optics system projects the original pattern onto the substrate.

7. The exposure apparatus according to claim 6, characterized in that, The illumination optics system uses light from a pulsed light source to illuminate the original.

8. The exposure apparatus according to claim 6, characterized in that, It also has: A shielding unit is disposed on the conjugate surface of the illuminated surface, defining the illumination area in the illuminated surface; as well as The field aperture is positioned at a location separate from the conjugate surface of the illuminated surface in the optical axis direction of the illumination optical system, defining the illumination area in the scanning direction.

9. The exposure apparatus according to claim 8, characterized in that, The field-of-view aperture is positioned closer to the light source than the shading unit. Regarding the scanning direction, the arrangement period of the plurality of first optical elements is longer than the arrangement period of the plurality of second optical elements.

10. The exposure apparatus according to claim 8, characterized in that, The field of view aperture is positioned further away from the original image than the shading unit. Regarding the scanning direction, the arrangement period of the plurality of first optical elements is shorter than the arrangement period of the plurality of second optical elements.

11. The exposure apparatus according to claim 8, characterized in that, The condenser lens illuminates the original image using light from the optical integrator. In the illumination optical system, the light rays from the center of the optical surface of each of the plurality of first optical elements of the incident optical element are incident perpendicularly to the incident side. The focusing position of the light rays in the scanning direction of the condenser lens coincides with the position of the field aperture, and the focusing position of the light rays in the direction intersecting the scanning direction of the condenser lens coincides with the illuminated surface.

12. A method for manufacturing a semiconductor device, characterized in that, have: The process of exposing a substrate using the exposure apparatus described in claim 6; The process of developing the exposed substrate; and The process of manufacturing semiconductor devices from the developed substrate.

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