Illumination optical system, optical system adjustment method, and exposure apparatus

Abstract

To provide a technology with which it is possible to appropriately correct a spread angle of light ejected from a rod integrator even if there is variation in numerical aperture of optical fibers.SOLUTION: An illumination optical system 33 includes a plurality of optical fibers 511, a rod integrator 55, and a variable power optical system 53. The plurality of optical fibers 511 transmit light from a light source. The rod integrator 55 uniformly distributes light ejected from each of the optical fibers 511. The variable power optical system 53 is capable of changing an imaging magnification of the light ejected from each of the optical fibers 511.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The subject matter disclosed herein relates to an illumination optical system, an optical system adjustment method, and an exposure apparatus. [Background technology]

[0002] Conventionally, a pattern exposure apparatus equipped with an illumination optical system, a modulation element (such as a digital mirror device (DMD)), and a projection lens has been known. The illumination optical system uses a laser diode as a light source to uniformly illuminate the modulation element. The projection lens irradiates the resist (exposure surface) with pattern light (light modulation element image) controlled by the modulation element. Furthermore, a desired pattern is drawn on the resist by scanning the resist with the pattern light.

[0003] In a pattern exposure device, uniform illumination of the modulation element is required to stabilize exposure quality. Therefore, uniform light is formed by focusing the light from the light source into an optical fiber and then directing it from the optical fiber to a uniform optical element called a rod integrator.

[0004] An illumination optical system equipped with such a rod integrator is disclosed in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-171426 Summary of the Invention [Problem to be solved by the invention]

[0006] An optical fiber has a core and a cladding. The core and cladding have different refractive indices, and this difference in refractive index determines the characteristics of the light propagating inside the fiber. If there is variation in the refractive index of the core and cladding due to differences in product lots, the numerical aperture (NA) of the optical fiber will fluctuate, making it difficult to obtain the required light divergence angle.

[0007] An object of the present invention is to provide a technique that can appropriately correct the divergence angle of light emitted from an optical fiber even when there is variation in the numerical aperture of the optical fiber. [Means for solving the problem]

[0008] In order to solve the above problem, the first aspect comprises a plurality of optical fibers that transmit light from a light source, a rod integrator that uniformly distributes the light emitted from each of the optical fibers, and a variable magnification optical system that can change the imaging magnification of the light emitted from each of the optical fibers.

[0009] A second aspect is the illumination optical system of the first aspect, wherein the variable magnification optical system is located between the optical fiber and the rod integrator.

[0010] A third aspect is the illumination optical system of the second aspect, wherein the variable magnification optical system is capable of changing the imaging magnification while maintaining the focus position.

[0011] A fourth aspect is the illumination optical system of the third aspect, wherein the variable magnification optical system includes an objective lens, an imaging lens, and a movable lens that is movable between the objective lens and the imaging lens.

[0012] A fifth aspect is the illumination optical system of the second aspect, further comprising an angle adjustment mechanism that can tilt each of the optical fibers and the variable magnification optical system together so as to change the angle of incidence of light entering the rod integrator.

[0013] A sixth aspect is the illumination optical system of the fifth aspect, wherein the angle adjustment mechanism is capable of changing the angle of incidence in a first direction.

[0014] A seventh aspect is the illumination optical system of the sixth aspect, wherein the angle adjustment mechanism is capable of changing the angle of incidence in a second direction intersecting with the first direction.

[0015] An eighth aspect is an optical system adjustment method for adjusting an illumination optical system according to any one of the first to seventh aspects, comprising the steps of: a) acquiring a light intensity distribution of light emitted from a plurality of optical fibers using a light intensity sensor; and b) adjusting the imaging magnification of the variable magnification optical system using the light intensity distribution acquired by step a).

[0016] A ninth aspect is an optical system adjustment method for adjusting the illumination optical system of the eighth aspect, including the steps of c) calculating the center of gravity of the light beam emitted from the rod integrator using a light intensity sensor, and d) adjusting the angle of incidence of the light with respect to the rod integrator so that the center of gravity of the light beam is at a predetermined position.

[0017] A tenth aspect is an exposure apparatus comprising: a support portion for supporting an exposure object; an illumination optical system according to any one of the first to seventh aspects; a spatial modulator for modulating light from the illumination optical system; and a scanning mechanism for scanning the surface of the object held by the holding portion with light modulated by the spatial modulator. [Effects of the Invention]

[0018] According to the illumination optical systems of the first to seventh aspects, the divergence angle of light emitted from a plurality of optical fibers can be appropriately adjusted by the variable magnification optical system, so that even if there is variation in the numerical aperture of the optical fibers, the divergence angle of the light can be appropriately corrected.

[0019] According to the illumination optical system of the second aspect, the light whose divergence angle has been appropriately adjusted can be homogenized by the rod integrator.

[0020] According to the illumination optical system of the third aspect, the imaging magnification can be changed without adjusting the position of the variable magnification optical system relative to the rod integrator.

[0021] According to the illumination optical system of the fourth aspect, the imaging magnification can be changed without changing the focus position.

[0022] According to the illumination optical system of the fifth aspect, by adjusting the angle of incidence of light incident on the rod integrator, the light emitted from the rod integrator can be irradiated onto the object at an appropriate angle. Also, by tilting the optical fiber and the variable magnification optical system integrally with respect to the rod integrator, the total length of the tilting unit can be made shorter than when the rod integrator is also tilted. This reduces physical interference.

[0023] According to the optical system adjusting method of the eighth aspect, the light amount distribution of the light is used, so that the spread angle of the light can be appropriately adjusted to a required angle.

[0024] According to the ninth aspect of the optical system adjusting method, the incident angle can be appropriately adjusted using the position of the center of gravity of the light beam, and therefore, even if there are individual differences among the multiple optical fibers, the direction of the light emitted from the rod integrator can be appropriately adjusted. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a schematic perspective view of an exposure apparatus equipped with an illumination optical system according to an embodiment. [Figure 2] 1 is a schematic top view of an exposure apparatus equipped with an illumination optical system according to an embodiment. [Figure 3] FIG. 2 is a diagram illustrating a schematic configuration of a drawing processing unit. [Figure 4] 1 is a diagram showing a schematic configuration of an illumination optical system according to an embodiment. [Figure 5] FIG. 1 is a perspective view showing an illumination optical system according to an embodiment. [Figure 6] FIG. 1 is a perspective view showing an illumination optical system according to an embodiment. [Figure 7] 10 is a top view showing how the light quantity distribution (intensity distribution) of the light emitted from the bundle fiber is measured. FIG. [Figure 8] 10A and 10B are diagrams illustrating a light intensity distribution before and after the adjustment of the divergence angle; [Figure 9] 10A and 10B are diagrams illustrating a light intensity distribution before and after adjusting the incident angle; DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the components described in the embodiment are merely examples and are not intended to limit the scope of the present invention. In the drawings, the dimensions and numbers of each part may be exaggerated or simplified as necessary to facilitate understanding.

[0027] <1. Embodiment> FIG. 1 is a schematic perspective view of an exposure apparatus 1 equipped with an illumination optical system 33 according to one embodiment. FIG. 2 is a schematic top view of the exposure apparatus 1 equipped with an illumination optical system 33 according to one embodiment. The exposure apparatus 1 is an apparatus that irradiates the upper surface of a substrate W, such as a semiconductor substrate or a glass substrate, coated with a resist that is a photosensitive material, with spatially modulated light to write an exposure pattern on the upper surface of the substrate W. As shown in FIG. 1, the exposure apparatus 1 includes a base 10, a stage 11, a transport mechanism 12, a frame 20, multiple (two in this example) writing processing units 30, and a control unit 40.

[0028] The transport mechanism 12 is a device that transports the flat plate-shaped stage 11 in a horizontal direction at a substantially constant posture on the upper surface of the base 10. The transport mechanism 12 has a main scanning mechanism 13, a sub-scanning mechanism 14, a rotation mechanism 15, a lower support plate 16, and a middle support plate 17.

[0029] The main scanning mechanism 13 is a mechanism for moving the stage 11 in the main scanning direction. The sub-scanning mechanism 14 is a mechanism for moving the stage 11 in the sub-scanning direction. The substrate W is moved together with the stage 11 in the main scanning direction and the sub-scanning direction by the main scanning mechanism 13 and the sub-scanning mechanism 14.

[0030] The base 10 is a support base that supports the stage 11 and the transport mechanism 12. The base 10 is flat and extends in the main scanning direction and the sub-scanning direction. The lower support plate 16 is supported on the base 10 by a main scanning mechanism 13 so as to be movable in the main scanning direction. The middle support plate 17 is supported on the lower support plate 16 by a sub-scanning mechanism 14 so as to be movable in the sub-scanning direction. The stage 11 is supported on the middle support plate 17 by a rotation mechanism 15 so as to be rotatable about a vertical axis. The stage 11 has an upper surface on which a substrate W can be placed. The upper surface of the stage 11 is appropriately provided with chuck pins for holding the substrate W, multiple suction holes for sucking the substrate W, and the like. The stage 11 is an example of a holding unit.

[0031] The main scanning mechanism 13 is a mechanism that moves the lower support plate 16 in the main scanning direction relative to the base 10. The main scanning mechanism 13 has two linear motors 13a. The two linear motors 13a are arranged on the lower support plate 16 at an interval in the sub-scanning direction. The linear motor 13a has a stator 131 and a slider 133. The stator 131 is arranged on the upper surface of the base 10 along the main scanning direction. In other words, the two stators 131 are arranged parallel to each other on the upper surface of the base 10. The slider 133 is fixed to the lower support plate 16.

[0032] The linear motor 13a generates magnetic attractive and repulsive forces between the stator 131 and the slider 133 in response to a control signal from the control unit 40, and moves the slider 133 in the main scanning direction along the stator 131. This moves the lower support plate 16 in the main scanning direction.

[0033] The sub-scanning mechanism 14 is a mechanism that moves the middle support plate 17 in the sub-scanning direction relative to the lower support plate 16. The sub-scanning mechanism 14 has a linear motor 14a and two guide mechanisms 14b.

[0034] The linear motor 14a has a stator 141 and a slider 142. The stator 141 is disposed on the upper surface of the lower support plate 16 along the sub-scanning direction. The slider 142 is fixed to the middle support plate 17.

[0035] The two guide mechanisms 14b are provided at an interval in the main scanning direction. Each guide mechanism 14b has a guide rail 143 and a ball bearing 144. The guide rail 143 is disposed on the upper surface of the lower support plate 16 and extends along the sub-scanning direction. That is, the two guide rails 143 are disposed on the upper surface of the lower support plate 16, and the ball bearing 144 is fixed to the lower surface of the middle support plate 17. The ball bearing 144 is movable in the sub-scanning direction along the guide rail 143.

[0036] The linear motor 14a generates magnetic attractive and repulsive forces between the stator 141 and the slider 142 in response to a control signal from the control unit 40, causing the slider 142 to move in the sub-scanning direction along the stator 141. This causes the middle support plate 17 to move in the sub-scanning direction.

[0037] The rotation mechanism 15 is a mechanism that adjusts the angle (yawing angle) θ of the stage 11 around the vertical axis relative to the middle support plate 17. The rotation mechanism 15 includes, for example, a motor. The rotation mechanism 15 operates the motor in response to a control signal from the control unit 40, and rotates the stage 11 around the vertical axis relative to the middle support plate 17. This adjusts the angle θ of the stage 11.

[0038] The frame 20 is a structure for supporting the two imaging processing units 30. The frame 20 has two support columns 21 and a bridge portion 22. The two support columns 21 are arranged at an interval in the sub-scanning direction. Each support column 21 extends upward from the side of the base 10. The bridge portion 22 extends in the sub-scanning direction and connects the upper ends of the two support columns 21. The stage 11 holding the substrate W passes between the two support columns 21 and below the bridge portion 22. Each imaging processing unit 30 is attached to the bridge portion 22.

[0039] Each imaging processing unit 30 includes a laser light source 31, a laser driving unit 32, an illumination optical system 33, and an optical head 34. That is, the exposure device 1 includes two optical heads 34. The two optical heads 34 are fixed to the bridge portion 22 of the frame 20 with an interval between them in the sub-scanning direction.

[0040] The laser light source 31, laser driver 32, and illumination optical system 33 are housed, for example, inside the bridge portion 22 of the frame 20. The laser light source 31 has a plurality of (for example, 12) laser modules 311. The laser driver 32 is electrically connected to the laser light source 31. The laser driver 32 causes each laser module 311 of the laser light source 31 to emit light in response to a control signal from the control unit 40. The light from each laser module 311 is incident on the illumination optical system 33.

[0041] Control unit 40 is a device that controls the operation of each part of exposure apparatus 1. Control unit 40 is a computer that includes a processor 41 that includes a CPU (Central Processing Unit) and the like, a memory 42 such as RAM (Random Access Memory), and a storage unit 43 such as a hard disk drive. Memory 42 and storage unit 43 are electrically connected to processor 41 via a bus. A computer program P for controlling the operation of exposure apparatus 1 is stored in storage unit 43.

[0042] The control unit 40 is electrically connected to the drawing processing unit 30 including the laser driving unit 32 and the optical head 34, the main scanning mechanism 13 including the linear motor 13a, the sub-scanning mechanism 14 including the linear motor 14a, the rotation mechanism 15, etc. The processor 41 of the control unit 40 controls the operation of each of the above-mentioned units of the exposure apparatus 1 by executing the computer program P. This allows the drawing processing in the exposure apparatus 1 to proceed.

[0043] When the exposure apparatus 1 is in operation, exposure is performed by the optical head 34, and the transport mechanism 12 transports the substrate W. Specifically, while the main scanning mechanism 13 transports the substrate W in the main scanning direction, the optical head 34 irradiates the substrate W with patterned light. This exposes a strip-shaped area (hereinafter referred to as a "strip area") extending in the main scanning direction on the top surface of the substrate W. Thereafter, the sub-scanning mechanism 14 moves the stage 11 in the sub-scanning direction by the width of one strip-shaped area (width in the sub-scanning direction). The exposure apparatus 1 alternately and repeatedly performs such exposure in the main scanning direction and transport of the stage 11 in the sub-scanning direction. This allows a pattern to be written on the entire top surface of the substrate W.

[0044] Fig. 3 is a diagram showing a schematic configuration of the drawing processing unit 30. Fig. 4 is a diagram showing a schematic configuration of an illumination optical system 33 according to an embodiment.

[0045] The illumination optical system 33 includes a fiber bundle 51, a variable magnification optical system 53, and a rod integrator 55. The fiber bundle 51 includes a plurality of (e.g., 12) optical fibers 511, each having one core, and a holder 513 that holds the emission side ends of the plurality of optical fibers 511. The fiber bundle 51 is configured by bundling a plurality of optical fibers 511 together. In the holder 513, the emission side ends of the plurality of optical fibers 511 are arranged in a row at equal intervals. Light from each laser module 311 of the laser light source 31 is incident on the corresponding optical fiber 511.

[0046] As a method for arranging the optical fibers 511, for example, a plurality of optical fibers 511 may be pressed against a plane provided on the holder 513. Alternatively, a plurality of V-grooves may be provided on the holder 513, and the optical fibers 511 may be inserted into each V-groove. Furthermore, the optical fibers 511 may be passed through a plurality of holes provided in the holder 513.

[0047] The variable magnification optical system 53 is disposed downstream of the bundle fiber 51. Light emitted from each optical fiber 511 of the bundle fiber 51 is incident on the variable magnification optical system 53. The variable magnification optical system 53 is capable of changing the imaging magnification when imaging the light emitted from each optical fiber 511. The variable magnification optical system 53 is capable of changing the imaging magnification while maintaining the focus position (i.e., while keeping the focal position constant). As shown in FIG. 4, the variable magnification optical system 53 has, for example, an objective lens 531, an imaging lens 533, and a movable lens 535. The movable lens 535 is capable of moving between the objective lens 531 and the imaging lens 533. The imaging magnification is changed by adjusting the position of the movable lens 535.

[0048] The rod integrator 55 is disposed downstream of the variable magnification optical system 53. Light emitted from the variable magnification optical system 53 is incident on the rod integrator 55. The rod integrator 55 distributes the light emitted from each optical fiber 511 of the fiber bundle 51 uniformly. The rod integrator 55 is a solid rod integrator having a glass rod. The rod integrator 55 repeatedly and totally reflects the incident light inside the rod, thereby emitting a rectangular light beam with a uniform intensity within the beam cross section at the output end. That is, the light emitted from the fiber bundle 51 forms a rectangular, uniform secondary light source at the output end of the rod integrator 55. The rod integrator 55 may be a hollow rod integrator configured by arranging four flat glass sheets with reflective coatings in a square shape so that the surfaces with the reflective coatings surround a rectangular space. In this case, light is incident on a space surrounded by four flat glass plates and is repeatedly totally reflected within the space, thereby emitting a rectangular beam of light with uniform intensity within the beam cross section.

[0049] In this way, in the illumination optical system 33, light emitted from the laser light source 31 is incident on multiple optical fibers 511, allowing multiple light beams to be concentrated and utilized in a small area. To obtain the amount of light required for exposure, light emitted from multiple optical fibers 511 is required. The point light source distribution of the discrete optical fibers is converted into a uniform and even distribution by a rod integrator (uniform optical element), and then illuminates the spatial modulator 341 with the required divergence angle (numerical aperture) and irradiation size through multiple lenses.

[0050] As shown in FIG. 3, the light emitted from rod integrator 55 passes through an imaging lens and the like, and enters spatial modulator 341 of optical head .

[0051] The optical head 34 is an optical system that guides light from the illumination optical system 33 to the upper surface of the substrate W. The optical head 34 has a spatial modulator 341 and a projection optical system 343. The spatial modulator 341 modulates the light from the illumination optical system 33 so as to form pattern light according to input data from the control unit 40. As the spatial modulator 341, for example, a DMD (Digital Micromirror Device), which is a reflective light modulator, or a GLV (Grating Light Valve) (registered trademark), which is a diffraction grating type spatial modulator, can be used.

[0052] The projection optical system 343 collects the pattern light from the spatial modulator 341 and projects it onto the substrate W. This exposes a photosensitive material such as a resist coated on the upper surface of the substrate W. The projection optical system 343 includes, for example, a projection lens and a microlens array.

[0053] 5 and 6 are perspective views showing an illumination optical system 33 according to an embodiment. In FIGS. 5 and 6, an XYZ Cartesian coordinate system is defined to explain the positional relationship of elements. Here, the direction from the bundle fiber 51 toward the rod integrator 55 is defined as the plus (+)X direction, and the opposite direction is defined as the minus (-)X direction. Furthermore, with respect to the +X direction, the left direction is defined as the +Y direction, the right direction is defined as the -Y direction, the upward direction is defined as the +Z direction, and the downward direction is defined as the -Z direction. The Y direction coincides with the arrangement direction of the multiple optical fibers 511 in the bundle fiber 51.

[0054] 5, the illumination optical system 33 includes a first connector 57 and a second connector 59. The first connector 57 connects the holder 513 of the bundle fiber 51 and the variable magnification optical system 53. The second connector 59 connects the variable magnification optical system 53 and the rod integrator 55.

[0055] 5, second connector 59 has a first bracket 591, a second bracket 592, a third bracket 595, a contact plate 593, and two connector plates 594. First bracket 591 is fixed to variable magnification optical system 53 via fasteners such as bolts. Second bracket 592 is fixed to rod integrator 55. A cylindrical first protrusion 592a is provided on the top surface of second bracket 592. Furthermore, cylindrical second protrusions 592b are provided on the +Y side and the -Y side of second bracket 592, respectively.

[0056] The contact plate 593 is fixed to the first bracket 591 via a fixture. A notched recess 593a recessed in the -X direction is provided at the end of the contact plate 593 on the +X side. The notched recess 593a is in contact with the first convex portion 592a. As the notched recess 593a tilts around the Z axis around the first convex portion 592a, the angle θ of the bundle fiber 51 and the variable magnification optical system 53 about the Z axis relative to the rod integrator 55 changes. Z is adjusted. Z By adjusting this, the angle of incidence in the Y direction (first direction) of the light incident on the rod integrator 55 from the variable magnification optical system 53 is adjusted.

[0057] Two connecting plates 594 are plate-shaped members that connect second bracket 592 and third bracket 595. One connecting plate 594 is provided on the +Y side of second bracket 592 and third bracket 595, and the other connecting plate 594 is provided on the -Y side of second bracket 592 and third bracket 595. Connecting plate 594 is fixed to second bracket 592 and third bracket 595 via fasteners such as bolts.

[0058] The connecting plate 594 has a circular through-hole 594a. When the connecting plate 594 is fixed to the second bracket 592 and the third bracket 595, the second convex portion 592b of the second bracket 592 is inserted into the through-hole 594a. By inserting the second convex portion 592b into the through-hole 594a, the first bracket 591 and the connecting plate 594 can be tilted around the Y axis with the second convex portion 592b as the center. As a result, the angle θ of the bundle fiber 51 and the variable magnification optical system 53 with respect to the rod integrator 55 around the Y axis with the second convex portion 592b as the center is Y is adjusted. Y By adjusting this, the angle of incidence in the Z direction (second direction) of the light incident on the rod integrator 55 from the variable magnification optical system 53 is adjusted.

[0059] Angle θ Z and angle θ Y After this adjustment, two connecting plates 594 are fixed to the first bracket 591 and the second bracket 592. That is, the positions of the fiber bundle 51 and the variable magnification optical system 53 relative to the rod integrator 55 are fixed. This fixes the angle of incidence of light entering the rod integrator 55 from the variable magnification optical system 53.

[0060] The first convex portion 592a is disposed at the same position in the X and Y directions as the incident end of the rod integrator 55. The second convex portion 592b is disposed at the same position in the X and Z directions as the incident end of the rod integrator 55. Therefore, the second connector 59 makes it possible to tilt the bundle fiber 51 and the variable magnification optical system 53 in the Y and Z directions around the incident end of the rod integrator 55.

[0061] The second connector 59 tilts the plurality of optical fibers 511 (more specifically, the output end portions held by the holder 513) and the variable magnification optical system 53 together with respect to the rod integrator 55 so as to change the angle of incidence of light incident on the rod integrator 55. The second connector 59 is an example of an angle adjustment mechanism.

[0062] <Adjusting the spread angle> The optical fiber 511 may have a difference in refractive index between the core and the cladding depending on the production lot, which may cause variations in the divergence angle (numerical aperture) of the light emitted from the optical fiber 511. For example, if the numerical aperture varies by ±0.02, the numerical aperture of the bundle fiber 51 may vary by about ±10%. This may cause the numerical aperture of the spatial modulator 341 to fluctuate in the same way, which may result in a loss of light quantity or a decrease in resolution.

[0063] In the illumination optical system 33, the imaging magnification of the variable magnification optical system 53 of the illumination optical system 33 is adjusted to adjust the numerical aperture of the bundle fiber 51. Specifically, the imaging magnification of the variable magnification optical system 53 in the illumination optical system 33 is adjusted so that the divergence angle (numerical aperture) of the light emitted from the rod integrator 55 (hereinafter referred to as "emitted light") becomes a desired size.

[0064] 7 is a top view showing how the light quantity distribution (intensity distribution) of the output light emitted from the bundle fiber 51 is measured. The light quantity distribution of the output light is measured using a light quantity sensor 91. The light quantity sensor 91 has a photosensitive element such as a photodiode or a CCD (charge-coupled device), and a processing circuit that processes a signal from the photosensitive element. The light quantity sensor 91 is, for example, a line sensor.

[0065] The illumination optical system 33 is attached to a rotation mechanism 93. The rotation mechanism 93 is a mechanism that rotates the bundle fiber 51, the variable magnification optical system 53, and the rod integrator 55 together around a predetermined rotation axis. The rotation axis of the rotation mechanism 93 is set to the output end 55E of the rod integrator 55. The light intensity sensor 91 is fixed at a position sufficiently distant from the output end 55E of the rod integrator 55. Even if the light receiving surface of the light intensity sensor 91 is narrower than the spread of the emitted light, by rotating the emitted light with the rotation mechanism 93, the emitted light is irradiated from one end to the other end onto the light intensity sensor 91. This allows the amount of light from one end to the other end of the emitted light to be measured.

[0066] FIG. 8 is a diagram showing a light intensity distribution G11 before the adjustment of the divergence angle and a light intensity distribution G12 after the adjustment of the divergence angle. The light intensity distributions G11 and G12 show Gaussian distributions. Here, in the light intensity distributions G11 and G12, the light intensity in the Gaussian distribution is 13.5% (=1 / e 2 ) is defined as the divergence angle (numerical aperture) of the emitted light.

[0067] When adjusting the divergence angle, first, the light intensity distribution G11 before adjustment is acquired. Then, the divergence angle is calculated from the acquired light intensity distribution G11. Then, the imaging magnification of the variable magnification optical system 53 is adjusted so that the divergence angle becomes the required angle. As a result, it is possible to obtain output light having a desired divergence angle, as shown by the light intensity distribution G12.

[0068] As described above, by adjusting the imaging magnification of the variable magnification optical system 53, the numerical aperture of the bundle fiber 51 can be adjusted to a desired numerical aperture even when there is variation in the numerical aperture of the individual optical fibers 511. This reduces the loss of light quantity due to individual differences in the optical fibers 511. Furthermore, it is possible to reduce the reduction in the resolution of the pattern light when irradiating the spatial modulator 341 due to individual differences in the optical fibers 511.

[0069] In this example, the light intensity sensor 91 is smaller than the width of the spread of the emitted light, but a light intensity sensor having a light receiving surface larger than the width of the spread of the emitted light may be used instead of the light intensity sensor 91. In this case, the light intensity distribution of the emitted light can be measured without rotating the emitted light relative to the light intensity sensor.

[0070] Furthermore, in this example, as shown in FIG. 7, the light intensity distribution of the light emitted from the rod integrator 55 is measured, but this is not essential. For example, the rod integrator 55 may be removed to measure the light intensity distribution of the light emitted from the variable magnification optical system 53. Even in this case, the divergence angle of light can be adjusted to a required angle by adjusting the imaging magnification of the variable magnification optical system 53. In this way, by disposing the variable magnification optical system 53 between the bundle fiber 51 and the rod integrator 55, the divergence angle of light can be adjusted even without the rod integrator 55. This makes it easier to adjust the divergence angle.

[0071] <Adjusting the angle of incidence> Next, a method for adjusting the angle of incidence of light incident on rod integrator 55 from variable magnification optical system 53 will be described.

[0072] The direction of light emitted from each optical fiber 511 is likely to vary depending on the arrangement of the optical fibers 511, the polishing angle of the end face of the optical fiber core, and other factors. Therefore, it is difficult to precisely control the direction of light emitted from the holder 513 that holds a bundle of multiple optical fibers 511. If the direction of light emitted from the multiple optical fibers 511 is not appropriate, the light beam emitted from the rod integrator 55 will be emitted in an unexpected direction. As a result, light will not be appropriately incident on the spatial modulator 341, which may result in a loss of light intensity or a decrease in resolution.

[0073] In contrast, in the illumination optical system 33, the bundle fiber 51 and the variable magnification optical system 53 are unitized by the first connector 57, and by tilting this unit with respect to the rod integrator 55, it is possible to adjust the angle of incidence of light onto the rod integrator 55.

[0074] In the illumination optical system 33, the incident angle in the Y direction and the incident angle in the Z direction can be adjusted by tilting the fiber bundle 51 and the variable magnification optical system 53 about the Z axis and about the Y axis with respect to the rod integrator 55. Here, adjustment of the incident angle in the Y direction will be described, but the incident angle in the Z direction can also be adjusted in a similar manner.

[0075] FIG. 9 is a diagram showing a light intensity distribution G21 before adjusting the angle of incidence, and a light intensity distribution G22 after adjusting the angle of incidence. When adjusting the angle of incidence, first, the light intensity distribution G21 of the light emitted from the rod integrator 55 is acquired. The light intensity distribution G21 is acquired using a light intensity sensor 91 as shown in FIG. 7, and the luminous flux center of the emitted light is calculated from the acquired light intensity distribution G21. Specifically, the luminous flux center of gravity is the peak of the light intensity distribution or the central position of the half-width in the light intensity distribution. Then, based on the calculated luminous flux center of gravity, the angle θ of the contact plate 593 of the second connector 59 is adjusted so that the luminous flux center of gravity is at a predetermined position. Z is adjusted, and as a result, it is possible to obtain output light having a light intensity distribution G22 in which the position of the center of gravity of the light beam is corrected. By such adjustment, the incident angle in the Y direction can be corrected to an appropriate angle. Therefore, even if there are individual differences among the multiple optical fibers 511, it is possible to make the light appropriately incident on the spatial modulator 341.

[0076] As a method for controlling the direction of light emitted from the rod integrator 55, it is also possible to integrate the fiber bundle 51, the variable magnification optical system 53, and the rod integrator 55 and adjust the direction by tilting the entire unit. However, in this case, the overall length of the unit that is tilted increases, which may result in physical interference. In contrast, by configuring the fiber bundle 51 and the variable magnification optical system 53 to tilt relative to the rod integrator 55 as in this embodiment, the overall length of the unit that is tilted can be shortened. This reduces physical interference.

[0077] <2. Variations> Although the embodiments have been described above, the present invention is not limited to the above and various modifications are possible.

[0078] For example, in the above embodiment, the variable magnification optical system 53 is arranged between the bundle fiber 51 and the rod integrator 55. However, the variable magnification optical system 53 may be arranged downstream of the rod integrator 55 so that the light emitted from the rod integrator 55 is incident on the variable magnification optical system 53. In other words, the variable magnification optical system 53 may be arranged between the rod integrator 55 and the spatial modulator 341 of the optical head 34. Even with this configuration, it is possible to adjust the divergence angle of the light emitted from the bundle fiber 51 to a desired size.

[0079] Although the present invention has been described in detail, the above description is merely illustrative in all respects and does not limit the present invention. It is understood that countless variations not illustrated can be envisioned without departing from the scope of the present invention. The configurations described in the above embodiments and variations can be combined or omitted as appropriate as long as they are not mutually inconsistent. [Explanation of symbols]

[0080] 1. Exposure equipment 11 Stage (holding part) 13 Main scanning mechanism 14 Sub-scanning mechanism 33 Illumination optical system 51 Fiber bundle 53 Variable Magnification Optical System 55 Rod Integrator 59 2nd connector (angle adjustment mechanism) 341 Spatial Modulator 511 Optical Fiber 531 Objective Lens 533 Imaging Lens 535 Movable Lens

Claims

1. a plurality of optical fibers transmitting light from a light source; a rod integrator for uniformly distributing the light emitted from each of the optical fibers; a variable magnification optical system capable of changing an imaging magnification of light emitted from each of the optical fibers; An illumination optical system comprising:

2. 2. The illumination optical system according to claim 1, The variable magnification optical system is located between the optical fiber and the rod integrator.

3. 3. The illumination optical system according to claim 2, The variable magnification optical system is capable of changing the imaging magnification while maintaining a focus position.

4. 4. The illumination optical system according to claim 3, The variable magnification optical system is An objective lens; An imaging lens; a movable lens that is movable between the objective lens and the imaging lens; an illumination optical system including:

5. 3. The illumination optical system according to claim 2, an angle adjustment mechanism capable of tilting each of the optical fibers and the variable magnification optical system together so as to change an incident angle of light incident on the rod integrator; The illumination optical system further comprises:

6. 6. The illumination optical system according to claim 5, An illumination optical system, wherein the angle adjustment mechanism is capable of changing the angle of incidence in a first direction.

7. 7. The illumination optical system according to claim 6, The angle adjustment mechanism is capable of changing the angle of incidence in a second direction intersecting with the first direction.

8. 3. An optical system adjustment method for adjusting an illumination optical system according to claim 1, comprising the steps of: a) acquiring a light amount distribution of light emitted from a plurality of optical fibers using a light amount sensor; b) adjusting the imaging magnification of the variable magnification optical system using the light amount distribution acquired in step a); An optical system adjustment method comprising:

9. 9. An optical system adjustment method for adjusting an illumination optical system according to claim 8, comprising the steps of: c) calculating a luminous flux center of the light emitted from the rod integrator using a light quantity sensor; d) adjusting an angle of incidence of light with respect to the rod integrator so that the center of gravity of the light beam is at a predetermined position; An optical system adjustment method comprising:

10. An exposure apparatus comprising: A support portion for supporting an object to be exposed; An illumination optical system according to claim 1 or 2; a spatial modulator that modulates light from the illumination optical system; a scanning mechanism that scans a surface of the object held by the holding unit with light modulated by the spatial modulator; An exposure apparatus comprising:

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