KR20190036585A - Illumination Optical System, Exposure Apparatus And Device Fabrication Method - Google Patents

Abstract

The present invention provides an illumination optical system for illuminating a surface to be illuminated with light from a light source. The system comprises: a plurality of illumination systems for forming a predetermined illumination area with light from the light source; an optical system for holding a reflection surface for reflecting a light flux from the illumination system for each of the plurality of illumination systems; and a light shielding unit for shielding predetermined light components in a compound illumination area formed by light from the optical system and shaping a shape of the compound illumination area. The light fluxes from the plurality of illumination systems are reflected by the reflection surface so as to connect each illumination area, thereby forming one continuous compound illumination area on the surface to be illuminated.

Description

TECHNICAL FIELD [0001] The present invention relates to an illumination optical system exposure apparatus and a manufacturing method thereof,

The present invention relates to an illumination optical system, an exposure apparatus, and a device manufacturing method.

BACKGROUND ART [0002] A projection exposure apparatus has been conventionally used when a device such as a semiconductor element or a liquid crystal panel is manufactured by using a photolithography technique. The projection exposure apparatus includes an illumination optical system for illuminating a reticle (mask) on which a circuit pattern is formed, and a projection optical system for projecting the pattern of the reticle onto a substrate such as a wafer, and transfers the pattern of the reticle onto the substrate.

Optical systems such as an illumination optical system and a projection optical system generally have the feature that the points at the same distance from the optical axis of the optical system, that is, the points at the same image height, exhibit the same optical characteristics from the viewpoint of design.

An exposure apparatus including a projection optical system that applies such a feature to two concentric mirror systems (concave mirrors and convex mirrors) and projects a pattern of the reticle onto a wafer using a ring-shaped imaging area outside the axis (effective image area) Japanese Patent Application Laid-Open No. 60-232552.

18A to 18F are views for explaining a conventional exposure apparatus 1000 disclosed in Japanese Patent Laid-Open No. 60-232552. In the exposure apparatus 1000, the image forming region of the projection optical system 1300 is an arcuate region A formed with a predetermined radius centering on the optical axis O, as shown in Fig. 18B. The illumination optical system 1200 includes a projection optical system

It is necessary to illuminate the imaging area of the imaging lens 1300 with high illuminance.

In the illumination optical system 1200, the elliptical mirror 1210 condenses the light beam emitted by the mercury lamp 1100 at the light-converging point.

An optical integrator 1220 disposed in the vicinity of the condensing point uniformly illuminates the rear focal plane of the first condenser lens 1230 as the primary illuminated plane FIP )do. The light beam propagated through the primary illuminated surface (FIP) illuminates the reticle through the second condenser lens 1240.

However, the optical integrator 1220 includes a cylindrical lens array having optical refractive power as shown in Fig. 18C. Further, this optical power differs between two orthogonal directions as shown in Figs. 18D and 18E. Thus, as shown in Fig. 18F, a rectangular illumination area IA is formed on the primary illuminated plane FIP. The bar of the primary illuminated surface (FIP)

The light flux passing through the opening OP of the slit forms an arc illumination area on the reticle via the second condenser lens 1240 do. With this configuration, the illumination optical system 1200 can illuminate only the imaging area (arcuate area) of the projection optical system 1300.

Incidentally, since the conventional exposure apparatus uses an arc-shaped illumination area extracted from a rectangular illumination area as shown in Fig. 18F, the illumination efficiency is increased in proportion to the area ratio between the rectangular illumination area and the circular arc illumination area . As a result, the integrated illuminance (exposure amount) at the time of exposure is lowered, and the throughput (the number of wafers processed per unit time) is reduced as one of important parameters in the exposure apparatus.

The present invention provides an illumination optical system capable of forming an illumination region (for example, an arc-shaped illumination region) having a uniform illumination while suppressing a decrease in illumination efficiency.

According to a first aspect of the present invention, there is provided an illumination optical system for illuminating a surface to be illuminated with light from a light source, the illumination optical system comprising: a plurality of illumination systems for forming a predetermined illumination area from light from the light source; An optical system for holding a reflecting surface for reflecting a light flux from the illumination system for each of the plurality of illumination systems; And a light shielding unit for shielding a predetermined light component in a composite illumination area formed by light from the optical system and shaping the shape of the composite illumination area, wherein a light flux from the plurality of illumination systems Is reflected by the reflecting surface to form one continuous synthetic illumination area on the surface to be illuminated.

According to a second aspect of the present invention, there is provided a scanning type exposure apparatus for transferring a pattern of a reticle onto a substrate while scanning the reticle and a substrate, comprising: An illumination optical system and a projection optical system for projecting an image of the pattern of the reticle onto the substrate.

According to a third aspect of the present invention, there is provided a device manufacturing method comprising: exposing a substrate using an exposure apparatus; and developing the exposed substrate, wherein the exposure apparatus includes: And a projection optical system for projecting an image of the pattern of the reticle onto the substrate, wherein the illumination optical system forms a predetermined illumination area with light from the light source A plurality of illumination systems; An optical system for holding a reflecting surface for reflecting a light flux from the illumination system for each of the plurality of illumination systems; And a light shielding unit for shielding a predetermined light component in a composite illumination area formed by light from the optical system and shaping the shape of the composite illumination area, wherein a light flux from the plurality of illumination systems Is reflected by the reflection surface to form one continuous synthetic illumination area on the illuminated surface.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

While the present invention has been described with reference to exemplary embodiments, it is needless to say that the present invention is not limited to these exemplary embodiments. The scope of the following claims is to be construed as broadly as embracing all such modifications and equivalent structures and functions.

1 is a schematic view showing a configuration of an exposure apparatus according to an aspect of the present invention;
2 is a view showing a rectangular illumination area (along the xz cross section) formed by the illumination system in the illumination optical system of the exposure apparatus shown in Fig. 1; Fig.
3 is a view showing a rectangular illumination area (along the xz cross section) formed by the illumination system in the illumination optical system of the exposure apparatus shown in Fig. 1; Fig.
4 is a view showing a V-shaped synthetic illumination area formed by an optical member in the illumination optical system of the exposure apparatus shown in Fig. 1; Fig.
5 is a view showing the relationship between the combined illumination area and the light shielding unit (opening) shown in Fig. 4; Fig.
Fig. 6 is a view showing an arc-shaped illumination area formed on the reticle by the illumination optical system of the exposure apparatus shown in Fig. 1; Fig.
FIG. 7 is a view showing a multiple mirror mirror as an example of an optical member in the illumination optical system of the exposure apparatus shown in FIG. 1; FIG.
FIG. 8 is a view showing a relationship between the multi-mirror mirror shown in FIG. 7 and an illumination area formed by the illumination system;
9 is a view showing a V-shaped composite illumination area formed by the multi-mirror mirror shown in Fig. 7;
10 is a view showing a multi-lower prism as an example of an optical member in the illumination optical system of the exposure apparatus shown in Fig. 1; Fig.
11 is a schematic view showing a configuration of an exposure apparatus according to another aspect of the present invention;
12 is a view showing a rectangular illumination area (along the xz cross section) formed by the illumination system in the illumination optical system of the exposure apparatus shown in Fig. 11;
13 is a view showing a rectangular illumination region (along the xz cross section) formed by the illumination system in the illumination optical system of the exposure apparatus shown in Fig. 11;
14 is a view showing a first synthetic illumination area formed by an optical member in the illumination optical system of the exposure apparatus shown in Fig. 11;
15 is a view showing a second combined illumination area formed by the optical member in the illumination optical system of the exposure apparatus shown in Fig. 11;
FIG. 16 is a view showing the relationship between the second combined illumination area shown in FIG. 15 and the light shielding unit (opening); FIG.
17 is a schematic view showing a configuration of an exposure apparatus according to another aspect of the present invention;
18A to 18F are views for explaining a conventional exposure apparatus.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same members are denoted by the same reference numerals, and redundant explanations are omitted.

1 is a schematic view showing a configuration of an exposure apparatus 1 according to an aspect of the present invention. The exposure apparatus 1 is a scanning projection exposure apparatus (scanner) that transfers the pattern of the reticle 30 onto the wafer 50 in a step & scan manner.

The exposure apparatus 1 includes light sources 10A and 10B; An illumination optical system 20; A reticle stage (not shown) for mounting the reticle 30; A projection optical system 40; And a wafer page (not shown) on which the wafer 50 is mounted. However, the light sources 10A and 10B may be provided separately.

Each of the light sources 10A and 10B is an excimer laser such as an ArF excimer laser with a wavelength of about 193 nm or a KrF excimer laser with a wavelength of about 248 nm, for example. However, the light sources 10A and 10B are not limited to the excimer laser, and a F2 laser with a wavelength of about 157 nm or a lamp such as a mercury lamp or a xenon lamp may be used.

The illumination optical system 20 illuminates the reticle 30 with the light beams from the light sources 10A and 10B and illuminates the reticle 30 on a predetermined illuminated surface (for example, a reticle surface) Distribution). The illumination optical system 20 includes a plurality of illumination systems 210A and 210B; An optical member 220; A condenser system 230; A light shielding unit 240; And an imaging optical system 250.

In the illumination optical system 20, the light flux (illumination light) emitted by the light source 10A forms a uniform illumination region through the illumination system 210A. The illumination system 210A may take any form known in the art. The illumination system 210A includes, for example, an elliptical mirror for condensing the light flux from the light source 10A, an optical integrator, and a condenser lens, and has an optical arrangement for obtaining a rectangular illumination area uniform. Similarly, the light flux (illumination light flux) emitted by the light source 10B forms a uniform illumination area of a rectangular shape through the illumination system 210B.

The light beams from the illumination systems 210A and 210B are condensed on the illumination area composite surface CP when they are reflected by the optical member 220 disposed immediately before the illumination surface by the illumination systems 210A and 210B do. The illumination area composite surface CP is optically equivalent to the surface to be illuminated by the illumination systems 210A and 210B when the optical member 220 is not disposed in the optical path of the illumination optical system 20. [

The configuration and operation of the optical member 220 will be described later in detail.

The light propagating through the illumination area compound plane CP is diffused and enters the condenser system 230 and is condensed on the re-condensed surface RIP by the condensing action of the condenser system 230. In the vicinity of the reconstructed image surface RIP, a light shielding unit 240 having an arc-shaped opening 242 is disposed in this embodiment. The light shielding unit 240 is disposed at a position optically conjugate with respect to the reticle 30 (in this embodiment, between the optical member 220 and the reticle 30). The light-shielding unit 240 includes a light-

Shields predetermined light components of the composite illumination area CIA formed by the light source 220 (to be described later) and adjusts the shape of the composite illumination area CIA.

The light flux that has passed through the aperture 242 of the light shielding unit 240 is diffused and enters the imaging optical system 250 to be imaged on the reticle 30 by the focusing action of the imaging optical system 250.

Here, the illumination region formed by the illumination optical system 20 will be described. 2 is a view showing a rectangular illumination area IAL (along an x-z cross section) formed by the illumination system 210A. 3 is a view showing a rectangular illumination area IAR (along an x-z section) formed by the illumination system 210B. 2 and 3 show the illumination areas IAL and IAR formed when the optical member 220 is not disposed in the optical path of the illumination optical system 20. [ The illumination regions IAL and IAR shown in Figs. 2 and 3 are combined (connected) by the optical member 220 to form a V-shaped To form a composite illumination area (CIA). 4 is a view showing a V-shaped composite illumination area (CIA) formed by the optical member 220. Fig.

The V-shaped synthetic illumination area CIA formed on the illumination area composite surface CP is reproduced (formed) on the re-image plane RIP via the condenser system 230. However, as shown in Fig. 5, the light shielding unit 240 (The opening portion 242 of).

6, an arc-shaped illumination area IAF corresponding to the opening 242 of the light-shielding unit 240 is formed on the reticle 30 via the imaging optical system 250. [ 5 is a diagram showing the relationship between the combined illumination area CIA and the light shielding unit 240 (opening 242). FIG. 6 shows an illumination region 20 formed on the reticle 30 by the illumination optical system 20,

(IAF).

Thus, the illumination optical system 20 according to the present embodiment uses the arc-shaped illumination area IAF extracted from the V-shaped synthetic illumination area CIA. As a result, the illumination efficiency can be dramatically improved as compared with the conventional art (see FIG. 18) in which an arc-shaped illumination area is extracted from a rectangular illumination area. The illumination optical system 20 (the illumination system 210A, 210B and the optical member 220) is arranged so that the arcuate opening 242 of the light shielding unit 240 is inscribed in the composite illumination area CIA, It is preferable to form the shape composite illumination area (CIA). According to this, since the area of the combined illumination area (CIA) shielded by the light shielding unit 240 can be minimized, the illumination efficiency can be further improved.

Next, the optical member 220 will be described in detail. The optical member 220 precisely connects (composites) the rectangular illumination regions IAL and IAR formed by the illumination systems 210A and 210B to form a V-shaped illumination region IAF).

 The optical member 220 has a plurality of reflection surfaces for reflecting light fluxes from a plurality of illumination systems, and the plurality of reflection surfaces are illuminated by a light flux from a plurality of illumination systems, one continuous synthetic illumination area (CIA) As shown in Fig.

7, mirrors 222A and 224A, which reflect light beams from the illumination systems 210A and 210B, respectively, are configured to be orthogonal (perpendicular) to each other, A mirror (Dach mirror) 220A is used. The doh mirror 220A is an optical element whose adjacent reflection surfaces (in this embodiment, the mirrors 222A and 224A) are configured to be orthogonal to each other. 7 is a view showing a multi-mirror 220A serving as an example of the optical member 220. As shown in Fig.

7, when the convergent light components L1 and L2 from the illumination system 210A are incident on the doch mirror 220A, these light components are reflected by the mirror 222A at the light-converging point P1 and (P2). Similarly, when the convergent light component L3 from the illumination system 210B is incident on the diffracting mirror 220A, the light component is condensed on the light-converging point P3 when reflected by the mirror 224A. Therefore, these converged light components L1 to L3 travel in the optical axis direction (z direction) of the illumination optical system 20 via the multi-mirror 220A and contribute as illumination light.

The convergent light component L4 incident on the region other than the effective region of the mirror 224A is condensed at the light-converging point P4. Since the converged light component L4 does not enter the mirror 224A, the converged light component L4 does not advance in the z direction contributing as illumination light but proceeds in the y direction that does not contribute as illumination light.

8 is a diagram showing the relationship between the mirror 224A of the mirror portion 220A and the illumination region IAR formed by the illumination system 210B. 8, a light beam from the illumination system 210B is incident on the diffracting mirror 220A. Therefore, a rectangular illumination area IAR inclined with respect to the mirror 224A is formed by the mirror 224A do. However, as in the convergent light component L4, the light component of the area? That is not reflected by the mirror 224A (mirror mirror 220A) is not guided to the illumination area composite surface CP. That is, the rectangular illumination area IAR is shaped into a trapezoidal illumination area by the mirrors 220A.

The rectangular illumination regions IAL and IAR formed by the illumination systems 210A and 210B are connected (synthesized) by the shaping action of the doh mirror 220A, and as shown in Fig. 9, Thereby forming a V-shaped composite illumination area (CIA).

However, in FIG. 9, the illumination areas IAL and IAR are shown separately in order to facilitate understanding of the composite illumination area CIA, but these are strictly connected. That is, the illumination regions IAL and IAR are connected at one boundary line BL. Therefore, as long as the illumination systems 210A and 210B form the illumination areas IAL and IAR having uniform illuminance, the synthetic illumination area CIA formed by connecting (combining) these areas is, in principle, Including the boundary line BL, has a uniform illuminance. 9 is a view showing a V-shaped synthetic illumination area (CIA) formed by the Dahla mirror 220A.

In addition, when the joints between the mirrors 222A, 224A of the multiple mirror mirror 220A are cracked or broken, unevenness may occur in the composite illumination area CIA. In this case, it is possible to adjust (correct) the unevenness of illumination by the aberration of the imaging optical system 250. In detail, it is necessary to generate astigmatism only in the imaging optical system 250. [ Scorecard

A difference in the focus state of the vehicle can cause the beam to diverge only in one direction. Therefore, as long as the astigmatism (astigmatism in the direction orthogonal to the boundary line BL) in which the luminous flux diverges only in the y direction is generated in the imaging optical system 250 in Fig. 9, x direction), it is possible to prevent the light flux from being emitted from the boundary line BL

The unevenness of illumination can be adjusted. In order to generate the astigmatism, for example, a cylindrical lens may be used, or adjustment of only the astigmatism in the direction orthogonal to the boundary line BL may be omitted when the imaging optical system 250 is adjusted.

10, the optical member 220 includes two reflection type prisms 222B and 224B each having an inner surface 222Ba and an inner surface 222Ba forming a reflection surface for reflecting incident light The prism 220B may be used.

Each of the reflective prisms 222B and 224B may be, for example, a total reflection prism or an Amici prism.

The two reflection type prisms 222B and 224B are formed such that the inner surfaces 222Ba and 224Ba form angles of approximately 45 degrees with respect to the principal ray of the incident light beam, And 224Ba are orthogonal to each other. 10 is a view showing the multi-lower prism 220B as an example of the optical member 220. Fig.

In the diffraction prism 220B, the light flux from the illumination system 210A is condensed on the illumination area composite surface CP when it is totally reflected by the reflective prism 222B. Similarly, the light flux from the illumination system 210B is condensed on the illumination area composite surface CP when it is totally reflected by the reflective prism 224B. In this manner, since the multi-prism 220B uses total internal reflection, optical coating is unnecessary unless the convergent light component is incident at a wide angle. As a result, a reflectance close to 100% can be obtained. Further, since the multi-lower prism 220B does not require optical coating, the light-condensing efficiency with respect to the illumination light is high, and the multi-prism 220B has resistance against the heat generation in question, and therefore its deterioration is advantageously prevented. It is needless to say that the multi-prism 220B may be coated with an optical coating.

1, a V-shaped synthetic illumination area CIA is formed by two illumination systems 210A and 210B and one optical member 220 and an arc illumination area IAF is extracted therefrom Thereby improving illumination efficiency. However, as shown in Fig. 11, a U-shaped synthetic illumination area CIA is formed by three illumination systems 210A to 210C and two optical members 220 and 220 ' The illumination area IAF of the illumination area IAF may be extracted. In this way, a combined illumination area having a shape close to the shape of the illumination area (a shape close to the arc shape in this embodiment) required by a plurality of illumination systems and a plurality of optical members is formed to further improve illumination efficiency . 11 is a schematic view showing the configuration of an exposure apparatus 1 according to another aspect of the present invention.

An illumination region formed by the illumination optical system 20 of the exposure apparatus 1 shown in Fig. 11 will be described. 12 is a view showing a rectangular illumination area IAL (along an x-z cross section) formed by the illumination system 210A. 13 is a diagram showing a rectangular illumination area IAC (along an x-z cross section) formed by the illumination system 210B. The illumination regions IAL and IAC shown in Figs. 12 and 13 are connected (synthesized) by the optical member 220, respectively. By this operation, the first combined illumination area CIA1 as shown in Fig. 14 is formed on the first illumination area composite surface CP1. 14 is a view showing a first composite illumination area CIA1 formed by the optical member 220. Fig.

The light of the first synthetic illumination area CIA1 formed on the first illumination area synthetic surface CP1 is reflected by the optical member 220 'through the condenser system 230 and is reflected on the second illumination area synthetic surface CP2 To form an image. The optical member 220 'reflects light of a rectangular illumination area IAR (see FIG. 3) formed by the illumination system 210C and forms an image of the light on the second illumination area composite surface CP2 . Therefore, the optical member 220 'is formed by connecting the first composite illumination area CIA1 (illumination areas IAL and IAC) and rectangular illumination area IAR to the second illumination area composite surface CP2 Synthesized) to form a U-shaped second composite illumination area CIA2 as shown in Fig. Since the optical members 220 and 220 'precisely (accurately) connect the illumination areas IAL, IAC and IAR as described above, they are arranged in the illumination areas IAL, IAC, And the second composite illumination area CIA2 having a uniform illumination without any unevenness in illumination at the connection part between the first composite illumination area and the second composite illumination area IAR. Here, FIG. 15 is a diagram showing a second combined illumination area CIA2 formed by the optical member 220 '.

Shaped second synthetic illumination area CIA2 formed on the second illumination area composite surface CP2 is also reproduced (formed) on the re-image surface RIP through the condenser system 230. However, as shown in Fig. 16, Is partially extracted by (opening 242 of) the light shielding unit 240. [ Thus, on the reticle 30, an arc-shaped illumination area corresponding to the aperture 242 of the light shielding unit 240 is formed via the imaging optical system 250. [ 16 is a diagram showing the relationship between the second combined illumination area CIA2 and the light shielding unit 240 (opening 242).

11, the three rectangular illumination areas IAL, IAC, and IAR formed by the illumination systems 210A to 210C include two optical members 220 and 220 ' (Synthesized). 17, by using one optical member 220 " configured to orthogonally cross the three reflection surfaces for reflecting the light flux from the illumination systems 210A to 210C, the illumination areas IAL, < RTI ID = IAC) and IAR can be connected (synthesized) to the illumination optical system 20. This makes it possible to remarkably simplify the structure of the illumination optical system 20 and obtain high illumination efficiency. 1 is a schematic view showing a configuration of an exposure apparatus 1 according to another aspect.

Referring again to Figure 1, the reticle 30 has a circuit pattern and is supported and driven by a reticle stage (not shown). The diffracted light generated by the reticle 30 is projected onto the wafer 50 via the projection optical system 40. Since the exposure apparatus 1 is a scanner, the pattern of the reticle 30 is transferred to the wafer 50 by scanning the reticle 30 and the wafer 50. [

The projection optical system 40 projects the pattern of the reticle 30 onto the wafer 50. The projection optical system 40 may be a refractometer, a reflective refractometer, or a reflectometer.

The wafer 50 is a substrate onto which the pattern of the reticle 30 is projected (transferred), and is supported and driven by a wafer stage (not shown). However, instead of the wafer 50, a glass plate or other substrate may be used. The wafer 50 is coated with a resist.

In the exposure, the light emitted by the light sources 10A, 10B illuminates the reticle 30 by the illumination optical system 20. The light having the information of the pattern of the reticle 30 forms an image on the wafer 50 by the projection optical system 40. [ As described above, the illumination optical system 20 used in the exposure apparatus 1 can form an illumination region (for example, a rectangular illumination region) having a uniform illumination while suppressing a decrease in illumination efficiency. Therefore, the exposure apparatus 1 can provide a high-quality device (for example, a semiconductor element, an LCD element, an imaging element (CCD, etc.), a thin film magnetic head, etc.) with high throughput with high throughput.

Next, a method for manufacturing a device (for example, a semiconductor IC element or a liquid crystal display element) using the exposure apparatus 1 will be described. The device can be manufactured by the steps of exposing a substrate (e.g., a wafer or a glass substrate) coated with a photosensitizer by using the exposure apparatus 1, developing the substrate (photosensitive agent) do. Such a device manufacturing method can produce a device of higher quality than that manufactured by the prior art. Thus, the device manufacturing method using the exposure apparatus 1 and the resulting device constitute one aspect of the present invention.

While the present invention has been described with reference to exemplary embodiments, it is needless to say that the present invention is not limited to these exemplary embodiments. The scope of the following claims is to be construed as broadly as embracing all such modifications and equivalent structures and functions.

1: Exposure device 10A, 10B: Light source
20: illumination optical system 30: reticle
40: projection optical system 50: wafer
210A, 210B: illumination system 220: optical member
230: condenser system 240: shading unit
250: imaging optical system

Claims (8)

An illumination optical system for illuminating a surface to be illuminated with light from a light source,
A plurality of illumination systems for forming a predetermined illumination area from the light from the light source;
An optical system for holding a reflecting surface for reflecting a light flux from the illumination system for each of the plurality of illumination systems; And
And a light shielding unit for shielding a predetermined light component in a composite illumination area formed by light from the optical system and shaping the shape of the composite illumination area,
And a light flux from the plurality of illumination systems is reflected by the reflection surface so as to connect the respective illumination regions, thereby forming one continuous synthetic illumination region on the illumination surface. The illumination optical system according to claim 1, wherein the optical system includes a Dach mirror configured such that adjacent ones of the plurality of reflection surfaces are orthogonal to each other. The optical system according to claim 1, wherein the optical system includes two reflective prisms each having an inner surface configured to form one of the plurality of reflective surfaces,
Wherein the two reflection type prisms are arranged such that the inner surfaces thereof are orthogonal to each other so as to form an angle of substantially 45 DEG with respect to the principal ray of the incident light beam. The illumination optical system according to claim 1, wherein the combined illumination area is a V-shaped or U-shaped. The illumination optical system according to claim 4, wherein the light shielding unit has an arc-shaped opening portion in contact with the V-shaped or U-shaped synthetic illumination area. The illumination optical system according to claim 1, further comprising an imaging optical system configured to form an image of a light flux passing through the light shielding unit on the surface to be illuminated. The illumination optical system according to claim 6, wherein the imaging optical system has an astigmatism in a direction orthogonal to a boundary line of a light beam entering from the plurality of illumination systems and entering the combined illumination area. And a light shielding unit for shielding a predetermined light component in a composite illumination area formed by light from the optical system and shaping the shape of the composite illumination area,
And the light fluxes from the plurality of illumination systems are reflected by the reflection surface so as to connect the respective illumination regions, thereby forming one continuous synthetic illumination region on the illumination surface.

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