KR20250022862A - Lighting unit, exposure device, and exposure method - Google Patents

Abstract

The lighting unit comprises a first light source array (20A) having a plurality of first light source elements arranged having a first light emitting portion that emits light having a first wavelength characteristic, a first magnifying optical system (30A) that forms an enlarged image of each of the first light emitting portions of the first light source elements, a first optical system (81A) on which light from the first magnifying optical system enters, a second light source array (20B) having a plurality of second light source elements arranged having a second light emitting portion that emits light having a second wavelength characteristic different from the first wavelength characteristic, a second magnifying optical system (30B) that forms an enlarged image of each of the second light emitting portions of the second light source elements, a second optical system (81B) on which light from the second magnifying optical system enters, and a synthesizing optical element (DM2) that synthesizes light from the first optical system and light from the second optical system, and the synthesizing The optical element is positioned at or near the rear focal position of the first optical system and also at or near the rear focal position of the second optical system.

Description

Lighting unit, exposure device, and exposure method

It relates to a lighting unit, an exposure device, and an exposure method.

Recently, liquid crystal display panels have been widely used as display elements for personal computers, televisions, etc. Liquid crystal display panels are manufactured by forming a circuit pattern of thin film transistors on a plate (glass substrate) using a photolithography technique. As a device for this photolithography process, an exposure device is used that projects and exposes an original pattern formed on a mask onto a photoresist layer on a plate via a projection optical system (for example, Patent Document 1).

In general, there is a demand for the realization of a high-brightness surface light source that can be applied to various optical devices including the exposure device described above.

Japanese Patent Publication No. 2000-21712

According to the aspect of the first disclosure, the lighting unit comprises: a first light source array having a plurality of first light source elements arranged having a first light emitting portion that emits light having a first wavelength characteristic; a first magnifying optical system that forms an magnified image of each of the first light emitting portions of the first light source elements; a first optical system into which light from the first magnifying optical system enters; a second light source array having a plurality of second light source elements arranged having a second light emitting portion that emits light having a second wavelength characteristic different from the first wavelength characteristic; a second magnifying optical system that forms an magnified image of each of the second light emitting portions of the second light source elements; a second optical system into which light from the second magnifying optical system enters; and a synthesizing optical element that synthesizes light from the first optical system and light from the second optical system, wherein the synthesizing optical element is at or near a rear focus position of the first optical system, and further, is at a rear focus position of the second optical system. It is located at a location or in the vicinity of the location.

According to the second aspect of the disclosure, the exposure device comprises the illumination unit and a projection optical system that projects a pattern image of a mask illuminated by the illumination unit onto a photosensitive substrate.

According to an aspect of the third disclosure, an exposure method is an exposure method using the exposure device, including illuminating the mask using the illumination unit, and projecting a pattern image of the mask onto the photosensitive substrate using the projection optical system.

In addition, the configuration of the embodiment described below may be appropriately improved, and at least part of it may be replaced with another configuration. In addition, the configuration requirement that is not particularly limited to the arrangement is not limited to the arrangement disclosed in the embodiment, and may be arranged at a position where the function can be achieved.

Figure 1 is a schematic diagram showing the configuration of an exposure device related to the first embodiment.
Fig. 2 is a schematic diagram showing the configuration of a lighting unit related to the first embodiment.
Fig. 3(A) is a plan view schematically showing the configuration of the first and second light source arrays, and Fig. 3(B) is a drawing schematically showing the internal configuration of the first and second light source units.
Figure 4 is a graph showing an example of the relationship between the angle of incidence and illuminance on a dichroic mirror.
Figure 5 is a graph showing an example of the light distribution characteristics of the light-emitting portion of an LED chip.
FIG. 6(A) and FIG. 6(B) are drawings explaining an enlarged image formed on a predetermined surface in the second embodiment.
Figures 7(A) and 7(B) are drawings showing simulation results.

《Embodiment 1》

The exposure device (10) related to the first embodiment will be described based on FIGS. 1 to 4.

(Composition of exposure device)

First, the configuration of the exposure apparatus (10) related to the first embodiment will be described using Fig. 1. Fig. 1 is a drawing schematically showing the configuration of the exposure apparatus (10) related to the first embodiment.

The exposure device (10) is a scanning stepper (scanner) that transfers a pattern formed on the mask (MSK) onto the substrate (P) by driving the mask (MSK) and the glass substrate (hereinafter referred to as “substrate”) (P) in the same direction and at the same speed relative to the projection optical system (PL). The substrate (P) is, for example, a rectangular glass substrate used in a liquid crystal display (flat panel display), and has at least one side length or diagonal length of 500 mm or more.

Hereinafter, the direction (scanning direction) in which the mask (MSK) and the substrate (P) are driven during scanning exposure is set to the X-axis direction, the direction in a horizontal plane orthogonal thereto is set to the Y-axis direction, the direction orthogonal to the X-axis and Y-axis is set to the Z-axis direction, and the directions of rotation (tilt) around the X-axis, Y-axis, and Z-axis are set to the θx, θy, and θz directions, respectively.

The exposure device (10) is equipped with an illumination system (IOP), a mask stage (MST) that holds a mask (MSK), a projection optical system (PL), a body (70) that supports these, a substrate stage (PST) that holds a substrate (P), and a control system for these. The control system comprehensively controls each component of the exposure device (10).

The body (70) has a base (vibration isolator) (71), columns (72A, 72B), an optical plate (73), a support (74), and a slide guide (75). The base (vibration isolator) (71) is arranged on a floor (F) and supports the columns (72A, 72B) and the like by damping vibrations from the floor (F). The columns (72A, 72B) each have a frame shape, and the column (72A) is arranged on the inside of the column (72B). The optical plate (73) has a flat plate shape and is fixed to the ceiling of the column (72A). The support (74) is supported on the ceiling of the column (72B) via a slide guide (75). The slide guide (75) is equipped with an air ball lifter and a positioning mechanism, and positions the support (74) (i.e., the mask stage (MST) described later) at an appropriate position in the X-axis direction with respect to the optical plate (73).

The illumination system (IOP) is arranged above the body (70). The illumination system (IOP) irradiates illumination light (IL) onto the mask (MSK). The detailed configuration of the illumination system (IOP) will be described later.

The mask stage (MST) is supported on a support (74). A mask (MSK) having a pattern surface (the lower surface in Fig. 1) on which a circuit pattern is formed is fixed to the mask stage (MST) by, for example, vacuum suction (or electrostatic suction). The mask stage (MST) is driven by a predetermined stroke in the scanning direction (X-axis direction) and micro-driven in the non-scanning direction (Y-axis direction and θz direction) by, for example, a driving system including a linear motor.

Position information (including rotation information in the θz direction) of a mask stage (MST) in the XY plane is measured by an interferometer system. The interferometer system measures the position of the mask stage (MST) by irradiating a measuring beam onto a moving mirror (or a mirror-finished reflective surface (not shown)) formed at an end of the mask stage (MST) and receiving reflected light from the moving mirror. The measurement result is supplied to a control device (not shown), and the control device drives the mask stage (MST) via a driving system according to the measurement result of the interferometer system.

The projection optical system (PL) is supported on an optical plate (73) below (on the -Z side) the mask stage (MST). The projection optical system (PL) has the same configuration as the projection optical system disclosed in, for example, U.S. Patent No. 5,729,331, and includes a plurality (for example, seven) projection optical units (100) (multi-lens projection optical units) arranged in a zigzag shape, for example, in a projection area of a pattern image of the mask (MSK), and forms a rectangular image field whose length direction is the Y-axis direction. Here, four projection optical units (100) are arranged at predetermined intervals in the Y-axis direction, and the remaining three projection optical units (100) are arranged at predetermined intervals in the Y-axis direction, spaced apart from the four projection optical units (100) on the +X side. As each of the plurality of projection optical units (100), for example, one that forms an erect image with a bilateral telecentric magnification system is used. In addition, the projection areas of the plurality of projection optical units (100) arranged in a zigzag shape are integrated and called an exposure area.

When an illumination area on a mask (MSK) is illuminated by illumination light (IL) from an illumination system (IOP), a projection image (partially erected image) of a circuit pattern of the mask (MSK) within the illumination area is formed on an irradiated area (exposure area (conjugate to the illumination area)) on a substrate (P) arranged on the image surface side of the projection optical system (PL) by the illumination light (IL) transmitted through the mask (MSK). Here, a resist (sensitive agent) is applied to the surface of the substrate (P). By synchronously driving the mask stage (MST) and the substrate stage (PST), that is, driving the mask (MSK) in a scanning direction (X-axis direction) with respect to the illumination area (illumination light (IL)) and driving the substrate (P) in the same scanning direction with respect to the exposure area (illumination light (IL)), the substrate (P) is exposed and the pattern of the mask (MSK) is transferred onto the substrate (P).

The substrate stage (PST) is placed on a base (vibration isolator) (71) below (-Z side) the projection optical system (PL). A substrate (P) is held on the substrate stage (PST) via a substrate holder (not shown).

Position information (including rotation information (yaw amount (rotation amount θz in the θz direction), pitching amount (rotation amount θx in the θx direction), and rolling amount (rotation amount θy in the θy direction)) of the substrate stage (PST) in the XY plane is measured by an interferometer system. The interferometer system measures the position of the substrate stage (PST) by irradiating a measuring beam from an optical platen (73) onto a moving mirror (or a mirror-finished reflective surface (not shown)) formed at an end of the substrate stage (PST) and receiving reflected light from the moving mirror. The measurement result is supplied to a control device (not shown), and the control device drives the substrate stage (PST) according to the measurement result of the interferometer system.

In the exposure device (10), alignment measurement (e.g., EGA, etc.) is performed prior to exposure, and the result is used to expose the substrate P in the following order. First, according to the instructions of the control device, the mask stage MST and the substrate stage PST are synchronously driven in the X-axis direction. As a result, scanning exposure is performed for the first shot area on the substrate P. When the scanning exposure for the first shot area is completed, the control device moves (steps) the substrate stage PST to a position corresponding to the second shot area. Then, scanning exposure is performed for the second shot area. The control device similarly repeats stepping between the shot areas of the substrate P and scanning exposure for the shot areas, thereby transferring the pattern of the mask MSK to all the shot areas on the substrate P.

(Composition of the lighting system (IOP))

Next, the configuration of the illumination system (IOP) in the present embodiment will be described. The illumination system (IOP) has a plurality of illumination units (90) corresponding to each of a plurality of projection optical units (100) provided in the projection optical system (PL).

Fig. 2 is a drawing schematically showing the configuration of a lighting unit (90). As shown in Fig. 2, the lighting unit (90) has a first light source unit (OPU1), a second light source unit (OPU2), and an illumination optical system (80).

(Composition of light source unit)

The first light source unit (OPU1) has a first light source array (20A) and a first magnifying optical system (30A), and the second light source unit (OPU2) has a second light source array (20B) and a second magnifying optical system (30B).

Fig. 3(A) is a plan view schematically showing the configuration of the first light source array (20A) and the second light source array (20B). The first light source array (20A) has, for example, a plurality (5 x 5 in Fig. 3(A)) of LED (Light Emitting Diode) chips (23A) arranged on a substrate (21A). The number of LED chips (23A) may be appropriately changed as needed. Each of the plurality of LED chips (23A) has a light-emitting portion (231A), and the peak wavelength of light emitted from the light-emitting portion (231A) is in the range of 380 to 390 nm. That is, the light-emitting portion (231A) is an ultraviolet LED (UV LED). It is more preferable that the peak wavelength of light emitted from the light-emitting portion (231A) is 385 nm. The light-emitting surface of the light-emitting portion (231A) is square, and the length of one side is a1. The LED chips (23A) are arranged at a pitch (P1). The pitch (P1) is the distance between the centers of adjacent LED chips (23A).

The second light source array (20B) has, for example, a plurality (5 × 5 in FIG. 3(A)) of LED chips (23B) arranged on a substrate (21B). The number of LED chips (23B) may be appropriately changed as needed. Each of the plurality of LED chips (23B) has a light-emitting portion (231B), and the peak wavelength of light emitted from the light-emitting portion (231B) is in the range of 360 to 370 nm. That is, the light-emitting portion (231B) is a UV LED. It is more preferable that the peak wavelength of light emitted from the light-emitting portion (231B) is 365 nm. The light-emitting surface of the light-emitting portion (231B) is square, and the length of one side thereof is a2. The LED chips (23B) are arranged at a pitch (P2).

The array pitch (P1) of the LED chip (23A) and the array pitch (P2) of the LED chip (23B) may be the same or different. In addition, the length (a1) of one side of the light-emitting surface of the light-emitting portion (231A) and the length (a2) of one side of the light-emitting surface of the light-emitting portion (231B) may be the same or different. In addition, the LED chips (23A and 23B) may be arranged not on the substrate, but, for example, on a heat sink.

Fig. 3(B) is a drawing schematically showing the internal configuration of the first light source unit (OPU1) and the second light source unit (OPU2). In addition, since the internal configurations of the first light source unit (OPU1) and the second light source unit (OPU2) are the same, the configuration of the first light source unit (OPU1) is described here as a representative example. Here, the two directions in which the LED chips (23A) are arranged are the X1 direction and the Y1 direction. The X1 direction and the Y1 direction are orthogonal. In addition, the direction orthogonal to the X1 direction and the Y1 direction is called the Z1 direction. The Z1 direction is approximately parallel to the optical axis (OA) of the light emitted from the light emitting portion (231A). In Fig. 3(B), for the sake of clarity of the drawing, only four LED chips (23A) arranged in a row along the Y1 direction are shown.

As shown in Fig. 3(B), the first magnifying optical system (30A) is an magnifying optical system for forming an magnified image of the light-emitting portion (231A) of each LED chip (23A) on a predetermined surface (PP). The first magnifying optical system (30A) has a plurality of lens portions (31A) arranged to correspond to the arrangement of the LED chips (23A). Each lens portion (31A) is a bilateral telecentric optical system that magnifies and projects the light-emitting portion (231A) at a magnification M1.

In the present embodiment, each lens unit (31A) is provided with four plano-convex lenses, but is not limited thereto. Each lens unit (31A) may be provided with, for example, two biconvex lenses or three biconvex lenses. Furthermore, each lens unit (31A) may be provided with, for example, a plano-convex lens and a biconvex lens.

In the present embodiment, the lens unit (31A) magnifies and projects the light-emitting unit (231A) at a magnification M1 = (array pitch (P1) of LED chips (23A))/(length (a1) of one side of the light-emitting surface of the light-emitting unit (231A)). On the other hand, the lens unit (31B) provided in the second magnifying optical system (30B) magnifies and projects the light-emitting unit (231B) at a magnification M2 = (array pitch (P2) of LED chips (23B))/(length (a2) of one side of the light-emitting surface of the light-emitting unit (231B)). As a result, the magnified images of the plurality of light-emitting units (231A, 231B) almost touch each other on the predetermined surface PP.

(Composition of the lighting optical system (80))

Referring again to FIG. 2, the configuration of the illumination optical system (80) will be described. The illumination optical system (80) includes a first light-gathering optical system (first optical system) (81A) including a first dichroic mirror (DM1), a second light-gathering optical system (81B) (second optical system), a second dichroic mirror (DM2), an imaging optical system (83), a fly's eye lens (FEL), an aperture stop (85), and a condenser optical system (84).

The first light-gathering optical system (81A) forms a pupil of an enlarged image of the light-emitting portion (231A) formed by the first magnifying optical system (30A). That is, the rear focal position of the first light-gathering optical system (81A) becomes the position of the pupil. The first light-gathering optical system (81A) has a first dichroic mirror (DM1) in the middle of the optical path and reflects at least a part of light having a peak wavelength of 385 nm. As a result, the light beam is incident on the second dichroic mirror (DM2). In addition, the first light-gathering optical system (81A) may be configured not to include the first dichroic mirror (DM1), and in that case, the arrangement of the first light source unit (OPU1) and the arrangement of each lens of the first light-gathering optical system (81A) may be appropriately adjusted to configure the light beam to be incident on the second dichroic mirror (DM2). In addition, the first light-gathering optical system (81A) may be configured with one lens, or may be configured with a lens group including a plurality of lenses.

The second light-gathering optical system (81B) forms a pupil of an enlarged image of the light-emitting portion (231B) formed by the second magnifying optical system (30B). That is, the rear focus position of the second light-gathering optical system (81B) becomes the position of the pupil. The second light-gathering optical system (81B) may be composed of one lens, or may be composed of a lens group including a plurality of lenses.

The second dichroic mirror (DM2) transmits at least a portion of light having a peak wavelength of 385 nm and reflects at least a portion of light having a peak wavelength of 365 nm. As a result, a composite image is formed by superimposing the pupil image formed by the first light-gathering optical system (81A) and the pupil image formed by the second light-gathering optical system (81B).

In the present embodiment, the second dichroic mirror (DM2) forms a composite image by superimposing the pupil image formed by the first light-gathering optical system (81A) and the pupil image formed by the second light-gathering optical system (81B). That is, the second dichroic mirror (DM2) is arranged at a position that is the rear focus position of the first light-gathering optical system (81A) and the rear focus position of the second light-gathering optical system (81B). As a result, the second dichroic mirror (DM2) is subjected to Köhler illumination by the light emitted from the first light source unit (OPU1) and the light emitted from the second light source unit (OPU2). By using Kohler illumination, the change in the intensity of the light flux of the pupil image formed by the first focusing optical system (81A) and the change in the intensity of the light flux of the pupil image formed by the second focusing optical system (81B) can be made small. In addition, the second dichroic mirror (DM2) does not necessarily have to be arranged at a position which is the rear focus position of the first focusing optical system (81A) and the rear focus position of the second focusing optical system (81B), and may be arranged so as to be located in the vicinity of each of the rear focus positions. Here, the vicinity means within ±100 mm from the rear focus position along the optical axis, preferably within ±50 mm, and more preferably ±20 mm. In addition, the sign here represents the direction in which light from the light source travels along the optical axis as plus, and the opposite direction as minus.

Fig. 4 is a graph showing an example of the relationship between the incident angle and the illuminance to a dichroic mirror. In Fig. 4, the horizontal axis represents the incident angle to the dichroic mirror, and the vertical axis represents the illuminance of reflected light. The illuminance on the vertical axis is set to 1, which is the illuminance of reflected light when light is incident on the dichroic mirror at the design incident angle (α).

As shown in Fig. 4, when the dichroic mirror is critically illuminated (i.e., when the image of the light source is formed at the position of the dichroic mirror), the angle of incidence of the light flux onto the dichroic mirror is in the range of the design incident angle α ± 8°, and an illuminance change of 3% or more occurs. On the other hand, when the dichroic mirror is subjected to Köhler illumination, the angle of incidence of the light flux onto the dichroic mirror is in the range of the design incident angle α ± 4°, and the illuminance change can be reduced to 1% or less. In this way, by subjecting the second dichroic mirror (DM2) to Köhler illumination, the difference between the illuminance of the light incident on the second dichroic mirror (DM2) and the illuminance of the light reflected by the second dichroic mirror (DM2) can be reduced, and therefore, it is possible to realize illumination light (IL) having high brightness and little illuminance unevenness.

In this embodiment, the incident angle (θ) of light from the second focusing optical system (81B) to the second dichroic mirror (DM2) is set to 35°. The incident angle (θ) of 35° means that the incident angle (θ) is within a range of 35°±5°. In addition, the incident angle (θ) is preferably 25° or more and less than 45°, more preferably 25° or more and 42° or less, and still more preferably 35°±5°. Thereby, the second dichroic mirror (DM2) can reflect the light flux of the pupil image formed by the second focusing optical system (81B) with high efficiency.

Returning to FIG. 2, the lighting unit (90) is formed with a detector (DT10) for monitoring light having a peak wavelength of 385 nm, a detector (DT20) for monitoring light having a peak wavelength of 365 nm, and a detector (DT30) for monitoring light having a peak wavelength of 385 nm and light having a peak wavelength of 365 nm.

Specifically, the detector (DT10) detects the illuminance of light having a peak wavelength of 385 nm reflected by the first dichroic mirror (DM1). The detector (DT20) detects the illuminance of light having a peak wavelength of 365 nm reflected by the second dichroic mirror (DM2). The detector (DT30) detects the illuminance of light having a peak wavelength of 385 nm unintentionally reflected by the second dichroic mirror (DM2) and the illuminance of light having a peak wavelength of 365 nm unintentionally transmitted by the second dichroic mirror (DM2).

The detection results of the detectors (DT10 to DT30) are output to a control device (not shown), and the control device controls the values of current supplied to the LED chips (23A and 23B) provided in the first light source unit (OPU1) and the second light source unit (OPU2), respectively, based on the detection results of the detectors (DT10 to DT30).

The imaging optical system (83) is a bilateral telecentric optical system that projects the composite image synthesized by the second dichroic mirror (DM2) at an equal size onto the incident end of the fly's eye lens (FEL). In addition, the imaging optical system (83) may project the composite image synthesized by the second dichroic mirror (DM2) at a reduced size onto the incident end of the fly's eye lens (FEL).

A fly's eye lens (FEL) is configured by, for example, arranging a plurality of lens elements having a defined refractive power in a longitudinal and transverse direction so that their optical axes are parallel to the reference optical axis (AX). Each lens element constituting the fly's eye lens (FEL) has a rectangular cross-section similar to the shape of a field of view to be formed on a mask (MSK) (and further, the shape of an exposure area to be formed on a substrate (P)).

Accordingly, the light beam incident on the fly-eye lens (FEL) is split into wavefronts by a plurality of lens elements, and one light source image is formed on the rear focal plane (exit plane) of each lens element or its vicinity. That is, a substantial surface light source composed of a plurality of light source images, that is, a secondary light source, is formed on the rear focal plane (exit plane) of the fly-eye lens (FEL) or its vicinity. The light beam from the secondary light source formed on the rear focal plane (exit plane) of the fly-eye lens (FEL) or its vicinity enters the aperture stop (85) arranged in its vicinity. Furthermore, in the present embodiment, the rear focal plane (exit plane) of the fly-eye lens (FEL), the first light source array (20A), and the second light source array (20B) are optically conjugate.

The aperture stop (85) is arranged at a position optically nearly conjugate to the entrance pupil plane of the projection optical unit (100) and has a variable aperture for defining a range contributing to the illumination of the secondary light source. Then, the aperture stop (85) sets the σ value (ratio of the aperture diameter of the pupil plane of the projection optical unit (100) to the aperture diameter of the pupil plane) that determines the illumination condition to a desired value by changing the aperture diameter of the variable aperture. Light from the secondary light source through the aperture stop (85) is subjected to the focusing action of the condenser optical system (84) and then superimposes and illuminates a mask (MSK) on which a predetermined pattern is formed.

As described above in detail, the lighting unit (90) related to the first embodiment comprises a first light source array (20A) in which a plurality of LED chips (23A) having light emitting portions (231A) emitting light having a peak wavelength of 385 nm are arranged, a first magnifying optical system (30A) for forming an magnified image of each light emitting portion (231A) of the LED chips (23A), and a first light-gathering optical system (81A) for forming a pupil of the magnified image formed by the first magnifying optical system (30A). In addition, the lighting unit (90) has a second light source array (20B) in which a plurality of LED chips (23B) having light emitting portions (231B) emitting light having a peak wavelength of 365 nm are arranged, a second magnifying optical system (30B) that forms an magnified image of each light emitting portion (231B) of the LED chips (23B), and a second light-gathering optical system (81B) that forms a pupil of the magnified image formed by the second magnifying optical system (30B). In addition, the lighting unit (90) has a second dichroic mirror (DM2) that forms a composite image by superimposing the pupil image formed by the first light-gathering optical system (81A) and the pupil image formed by the second light-gathering optical system (81B).

Since the light flux of the pupil image formed by the first light-gathering optical system (81A) and the light flux of the pupil image formed by the second light-gathering optical system (81B) illuminate the second dichroic mirror (DM2) by Köhler, as described in Fig. 4, it is possible to realize illumination light (IL) having high brightness and less illuminance unevenness compared to the case where the second dichroic mirror (DM2) is critically illuminated.

In addition, in the first embodiment of the present invention, the first magnifying optical system (30A) is a lens array having a plurality of lens sections (31A) arranged to correspond to each of the light-emitting sections (231A), and the second magnifying optical system (30B) is a lens array having a plurality of lens sections (31B) arranged to correspond to each of the light-emitting sections (231B). And, the lens section (31A) of the first magnifying optical system (30A) is a bilateral telecentric optical system that magnifies and projects the light-emitting section (231A) at a magnification of (array pitch (P1) of LED chips (23A)/(length (a1) of one side of the light-emitting surface of the light-emitting section (231A)). In addition, the lens section (31B) of the second magnifying optical system (30B) is a bilateral telecentric optical system that magnifies and projects the light-emitting section (231B) at a magnification of (array pitch (P2) of LED chips (23B)/(length (a2) of one side of the light-emitting surface of the light-emitting section (231B)). As a result, a surface light source can be formed in which magnified images of a plurality of light-emitting sections (231A, 231B) almost touch each other on a predetermined surface (PP).

In addition, in the first embodiment of the present invention, the lighting unit (90) comprises a fly's eye lens (FEL) that outputs the light flux of the composite image synthesized by the second dichroic mirror (DM2) as a light flux with a uniform illuminance distribution, and a bilateral telecentric imaging optical system (83) that equiaxes the composite image synthesized by the second dichroic mirror (DM2) onto the incident end of the fly's eye lens (FEL). As a result, the mask (MSK) can be uniformly illuminated.

In addition, in the first embodiment of the present invention, the angle of incidence of the light flux of the pupil image formed by the second light-gathering optical system (81B) onto the second dichroic mirror (DM2) is 35°. As a result, the light flux of the pupil image formed by the second light-gathering optical system (81B) can be reflected with high efficiency.

In addition, in the first embodiment, light having a peak wavelength of 385 nm emitted from the first light source unit (OPU1) was reflected by the first dichroic mirror (DM1) and then incident on the second dichroic mirror (DM2), but the first dichroic mirror (DM1) may be omitted, and light having a peak wavelength of 385 nm emitted from the first light source unit (OPU1) may be directly incident on the second dichroic mirror (DM2).

In addition, in the first embodiment, the light emitting portion (231A) of the LED chip (23A) emitted light having a peak wavelength of 385 nm, and the light emitting portion (231B) of the LED chip (23B) emitted light having a peak wavelength of 365 nm. However, the light emitting portion (231A) of the LED chip (23A) may emitted light having a peak wavelength of 365 nm, and the light emitting portion (231B) of the LED chip (23B) may emitted light having a peak wavelength of 385 nm. In this case, the first dichroic mirror (DM1) may be configured to reflect at least a portion of the light having a peak wavelength of 365 nm, and the second dichroic mirror (DM2) may be configured to transmit at least a portion of the light having a peak wavelength of 365 nm and reflect at least a portion of the light having a peak wavelength of 385 nm.

In addition, the wavelength of light emitted by the first light source unit (OPU1) and the second light source unit (OPU2) is not limited to that described above, and the first light source unit (OPU1) and the second light source unit (OPU2) may be configured by appropriately combining LED chips that emit light having a peak wavelength within a range of 360 to 440 nm. For example, the first light source unit (OPU1) may be configured to emit light having a peak wavelength of 405 nm, and the second light source unit (OPU2) may be configured to emit light having a peak wavelength of 385 nm. In addition, the first light source unit (OPU1) may be configured to emit light having a peak wavelength of 395 nm, and the second light source unit (OPU2) may be configured to emit light having a peak wavelength of 385 nm. The combination of the wavelength of light emitted from the first light source unit (OPU1) and the wavelength of light emitted from the second light source unit (OPU2) is not limited to these examples. In addition, when the combination of the wavelength of light emitted from the first light source unit (OPU1) and the wavelength of light emitted from the second light source unit (OPU2) is a combination other than that in the first embodiment, it is preferable to appropriately change the material of the dichroic mirror depending on the wavelength used.

《Embodiment 2》

Next, the second embodiment will be described. The second embodiment differs from the first embodiment in the magnification ratios M1 and M2 of the light-emitting parts (231A and 231B) by the first magnifying optical system (30A) and the second magnifying optical system (30B).

(About LED chips)

Fig. 5 is a graph showing an example of the light distribution characteristics of the light emitting portion (231A) of the LED chip (23A). In Fig. 5, the solid line shows the theoretical light distribution characteristics (Lambert radiation) of the light emitting portion (231A), and the dotted line is a curve that actually measures the radiation intensity of light emitted from the light emitting portion (231A) and approximates the measurement result with a sixth-order polynomial.

In the example of Fig. 5, among the light emitted from the light emitting portion (231A), the radiation intensity of the light in the range of the emission angle being greater than -50° and less than 50° is higher than the radiation intensity of Lambert radiation, and the radiation intensity of the light in the range of the emission angle being less than or equal to -50° and greater than or equal to 50° is lower than the radiation intensity of Lambert radiation. In this way, among the light emitted from the light emitting portion (231A), there exists a range of emission angles in which the radiation intensity thereof becomes higher than the radiation intensity of Lambert radiation. Therefore, it is thought that by using light in the range of the emission angle (in the example of Fig. 5, a range of ±50°) among the light emitted from the light emitting portion (231A), the brightness of the light emitted from the first light source unit (OPU1) can be improved.

Therefore, in the second embodiment, the magnification M1 when the first magnifying optical system (30A) magnifies and projects the light emitting portion (231A) is set to satisfy the following equation (1).

P1/a1 < M1 ≤ sinα ₁ /sinθ ₁ … (1)

Here, P1 is the array pitch of the LED chips (23A), a1 is the length of one side of the light-emitting surface of the light-emitting portion (231A), α ₁ is the maximum emission angle of light emitted from the light-emitting portion (231A) at which the radiation intensity is higher than Lambert radiation, and θ ₁ is the maximum emission angle of light emitted from the first magnifying optical system (30A). In addition, sinθ ₁ is a value that sets the ratio (σ) of the numerical aperture of the illumination optical system (80) to the numerical aperture of the projection optical unit (100) to 1. In addition, in a case where the arrangement pitch (P1) of the LED chips (23A) in the X1 direction and the length (a1) of one side of the light-emitting surface of the light-emitting portion (231A) in Fig. 3 are different from the arrangement pitch (P1) of the LED chips (23A) in the Y1 direction and the length (a1) of one side of the light-emitting surface of the light-emitting portion (231A), it is sufficient to set so as to satisfy equation (1) in each of the X1 direction and the Y1 direction.

In addition, the magnification M2 when the second magnifying optical system (30B) magnifies and projects the light emitting portion (231B) is set to satisfy the following equation (2).

P2/a2 < M2 ≤ sinα ₂ /sinθ ₂ … (2)

Here, P2 is the array pitch of the LED chips (23B), a2 is the length of one side of the light-emitting surface of the light-emitting portion (231B), α ₂ is the maximum emission angle of light emitted from the light-emitting portion (231B) whose radiation intensity is higher than Lambert radiation, and θ ₂ is the maximum emission angle of light emitted from the second magnifying optical system (30B). In addition, sinθ ₂ is a value that sets the ratio (σ) of the numerical aperture of the illumination optical system (80) to the numerical aperture of the projection optical unit (100) to 1. In addition, in a case where the array pitch (P2) of the LED chips (23B) in the X1 direction and the length (a2) of one side of the light-emitting surface of the light-emitting portion (231B) in Fig. 3 are different from the array pitch (P2) of the LED chips (23B) in the Y1 direction and the length (a2) of one side of the light-emitting surface of the light-emitting portion (231B), it is sufficient to set so as to satisfy equation (2) in each of the X1 direction and the Y1 direction.

By enlarging the light emitting portions (231A and 231B) at a magnification M1 satisfying equation (1) and a magnification M2 satisfying equation (2), respectively, the enlarged images of the areas excluding the peripheral edges of the light emitting surfaces of the light emitting portions (231A and 231B) come into contact with each other on the predetermined surface (PP). This point will be explained.

Fig. 6(A) and Fig. 6(B) are drawings explaining an enlarged image formed on a predetermined surface (PP) in the second embodiment. More specifically, Fig. 6(A) is a plan view showing arranged LED chips (23A), and Fig. 6(B) is a plan view showing an enlarged image formed on a predetermined surface (PP). For the sake of simplicity of the drawings, the explanation is made using 2 × 2 rows of LED chips (23A).

As shown in Fig. 6(A), among the light-emitting surfaces of the light-emitting portion (231A) of the LED chip (23A), the peripheral edge portion is defined as the peripheral edge region (231b), and the region excluding the peripheral edge region (231b) is defined as the central region (231a). In this case, when an enlarged image of the light-emitting portion (231A) is formed with a magnification M1 that satisfies Equation (1), as shown in Fig. 6(B), the enlarged image (MI1) of the central region (231a) is in contact with each other in the predetermined surface (PP), and the enlarged image (MI2) of the light-emitting portion (231A) including the central region (231a) and the peripheral edge region (231b) is formed such that a portion overlaps.

By enlarging the light-emitting portions (231A and 231B) by magnifications M1 and M2 respectively satisfying equations (1) and (2), a surface light source can be formed on the predetermined surface (PP) by light having a radiation intensity higher than Lambert radiation, and thus it becomes possible to increase the intensity of the light emitted from the first light source unit (OPU1) and the second light source unit (OPU2). In other words, since a surface light source is formed by light emitted from a region (central region (231a)) among the light-emitting surfaces of the light-emitting portions (231A and 231B) that emits light having a radiation intensity higher than Lambert radiation, it is possible to increase the intensity of the light emitted from the first light source unit (OPU1) and the second light source unit (OPU2).

[Simulation 1]

The magnification M1 of the light-emitting portion (231A) by the first magnifying optical system (30A) was changed, and the illuminance on a predetermined surface of the magnified image formed by the first magnifying optical system (30A) was simulated. The simulation conditions are as follows.

LED Chip (23A): NVSU233B manufactured by Nichia Chemical Industries, Ltd.

Length of one side of the light-emitting surface of the light-emitting part (231A): 1.4 mm

Array pitch (P1): 4 mm

α ₁ : 50°

θ ₁ : 8°

In this case, the condition of magnification M1 is 4 mm/1.4 mm = 2.9 ＜ M1 ≤ sin50°/sin8°= 5.5. Therefore, the illuminance was simulated for the cases where magnification M1 = 2.79 and magnification M1 = 3.6 times.

Fig. 7(A) is a drawing showing the simulation results. In Fig. 7(A), the horizontal axis represents the magnification, and the vertical axis is the illuminance ratio when the illuminance at the magnification M1 = 2.79 is set to 1. As shown in Fig. 7(A), it was confirmed that the illuminance was improved by making the magnification M1 larger than P1/a1 compared to the case where the magnification M1 was set to P1/a1.

[Simulation 2]

The illuminance was simulated by changing the magnification M1 in the same manner as in Simulation 1, using an LED chip (23A) different from the LED chip (23A) used in Simulation 1. The simulation conditions are as follows.

LED Chip (23A): NWSU333B manufactured by Nichia Chemical Industries, Ltd.

Length of one side of the light-emitting surface of the light-emitting part (231A): 1.9 mm

Array pitch (P1): 7 mm

α ₁ : 50°

θ ₁ : 8°

In this case, the condition of magnification M1 is 7 mm/1.9 mm = 3.68 ＜ M1 ≤ sin50°/sin8°= 5.5. Therefore, the illuminance was simulated for the cases where magnification M1 = 3.68, magnification M1 = 4.38, and magnification M1 = 4.65.

Fig. 7(B) is a drawing showing the simulation results. In Fig. 7(B), the horizontal axis is the magnification, and the vertical axis is the illuminance ratio when the illuminance at the magnification M1 = 4.38 is set to 1. As shown in Fig. 7(B), it was confirmed that the illuminance was improved by making the magnification M1 larger than P1/a1 compared to the case where the magnification M1 was set to P1/a1.

As described above in detail, according to the second embodiment, the magnification M1 when the first magnifying optical system (30A) magnifies and projects the light-emitting portion (231A) satisfies P1/a1 < M1 ≤ sinα ₁ /sinθ ₁ , and the magnification M2 when the second magnifying optical system (30B) magnifies and projects the light-emitting portion (231B) satisfies P2/a2 < M2 ≤ sinα ₂ /sinθ ₂ .

By specifying the magnifications M1 and M2 in this way, it is possible to form a secondary light source by light having a higher radiation intensity than Lambert radiation, thereby increasing the intensity of light emitted from the first light source unit (OPU1) and the second light source unit (OPU2).

In addition, in the manufacturing process of the first light source array (20A) and the second light source array (20B), when arranging the LED chips (23A and 23B) on the substrate, there are cases where the LED chips (23A and 23B) are misaligned. Due to the misalignment, there are cases where the illuminance of the first light source array (20A) and the second light source array (20B) is reduced. In the present embodiment, by making the magnification M1 and the magnification M2 larger than P1/a1 and P2/a2, respectively, only the area inside the light-emitting surface of the light-emitting portion (231A, 231B) (area excluding the peripheral edge) can be used, so that even if the LED chips (23A and 23B) are misaligned, the illuminance reduction of the first light source array (20A) and the second light source array (20B) can be suppressed.

In addition, in the second embodiment, sinθ ₁ and sinθ ₂ are values that make the ratio (σ) of the numerical aperture of the illumination optical system (80) to the numerical aperture of the projection optical unit (100) 1. As a result, it is possible to realize illumination light (IL) having a brightness according to the numerical aperture required in the exposure apparatus (10).

The above-described embodiments are examples of preferred embodiments of the present invention. However, they are not limited thereto, and various modifications may be made without departing from the spirit of the present invention.

10: Exposure device
20A: 1st light source array
20B: Second light source array
23A, 23B: LED Chip
30A: 1st magnifying optical system
30B: Second magnifying optical system
31A, 31B: Lens section
81A: First light-gathering optical system
81B: Second light-gathering optical system
90 : Lighting Unit
100 : Projection optical unit
PL : Projection optics
FEL : Fly Eye Lens
DM2: Second dichroic mirror

Claims (16)

A first light source array including a plurality of first light source elements having a first light emitting section that emits light having a first wavelength characteristic,
A first magnifying optical system for forming an enlarged image of each of the first light-emitting portions of the first light source element;
A first optical system into which light from the first magnifying optical system is incident,
A second light source array having a plurality of second light source elements arranged such that the second light source elements have second light emitting units that emit light having second wavelength characteristics different from the first wavelength characteristics;
A second magnifying optical system for forming an enlarged image of each of the second light-emitting portions of the second light source elements;
A second optical system into which light from the second magnifying optical system is incident,
It comprises a synthetic optical element that synthesizes light from the first optical system and light from the second optical system,
An illumination unit wherein the composite optical element is arranged at a position at or near the rear focal point of the first optical system and at or near the rear focal point of the second optical system. In paragraph 1,
The above first magnifying optical system is a first lens array having a plurality of first lens sections arranged to correspond to each of the first light-emitting sections,
The second magnifying optical system is a lighting unit having a second lens array having a plurality of second lens sections arranged to correspond to each of the second light-emitting sections. In the second paragraph,
The first lens unit of the first lens array is a bilateral telecentric optical system that magnifies and projects the first light emitting unit by a magnification of (the arrangement pitch of the first light source elements)/(the length of one side of the light emitting surface of the first light emitting unit) or more.
The second lens section of the second lens array is a bilateral telecentric optical system that magnifies and projects the second light emitting section by a magnification of (the arrangement pitch of the second light source elements)/(the length of one side of the light emitting surface of the second light emitting section) or more. In any one of claims 1 to 3,
A light homogenizing element that emits light synthesized by the above-mentioned synthetic optical element as a light flux with a uniform illuminance distribution,
A lighting unit having a bilateral telecentric imaging optical system that projects light synthesized by the above-mentioned synthetic optical element in a magnified or reduced form onto the incident end of the above-mentioned light homogenizing element. In paragraph 4,
The above light homogenizing element is a lighting unit which is a fly-eye lens. In any one of claims 1 to 5,
A lighting unit, wherein the first light emitting unit and the second light emitting unit are each ultraviolet light emitting diodes. In any one of claims 1 to 6,
A lighting unit wherein the peak wavelength of light emitted from the first light emitting portion is within a range of 380 to 390 nm. In any one of claims 1 to 7,
A lighting unit wherein the peak wavelength of light emitted from the second light emitting portion is within a range of 360 to 370 nm. In any one of claims 1 to 8,
An illumination unit, wherein the composite optical element is a dichroic mirror that transmits at least a portion of light having the first wavelength characteristic and reflects at least a portion of light having the second wavelength characteristic. In any one of claims 1 to 8,
An illumination unit, wherein the composite optical element is a dichroic mirror that reflects at least a portion of light having the first wavelength characteristic and transmits at least a portion of light having the second wavelength characteristic. In any one of claims 1 to 10,
An illumination unit, wherein the angle of incidence of light from the second optical system to the composite optical element is 25° or more and less than 45°. In any one of claims 1 to 10,
An illumination unit, wherein the angle of incidence of light from the second optical system to the composite optical element is 25° or more and 42° or less. In any one of claims 1 to 10,
An illumination unit wherein the angle of incidence of light from the second optical system to the composite optical element is 35°. A lighting unit as described in any one of claims 1 to 13,
An exposure device having a projection optical system that projects a pattern image of a mask illuminated by the above lighting unit onto a photosensitive substrate. In Article 14,
An exposure device, wherein the photosensitive substrate has at least one side length or diagonal length of 500 mm or longer. An exposure method using an exposure device described in Article 14 or Article 15,
Illuminating the mask using the above lighting unit,
An exposure method comprising projecting a pattern image of the mask onto the photosensitive substrate using the projection optical system.