JP2000098231A - Reflection reduction image-formation optical system, exposure device provided with it and exposing method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection reduction image-formation optical system by which a sufficient image-formation performance is obtained regardless of a simple constitution. SOLUTION: The reflection reduction image-formation optical system performs the reduction and the formation of the image of an object on an image surface possesses plural reflection surfaces. When NA on an image side is set to be NAw and the image reduction of the optical system is set to be β, the expression; NAm=NAw×β is satisfied. In this constitution, a light beam, whose angle Θ1 obtained by the optical axis of the reflection reduction image- formation optical system is set to be minimum, and the light beam, whose angle Θ2 obtained by the optical axis is set to be maximum, satisfy the expressions of SIN Θ1>0.1 NAm and SIN Θ<4 NAm, within an arbitrary plane including the optical axis of the reflection reduction image-formation optical system among the light beams made incident on the reflection reduction image-formation optical system from an object surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reflection reduction imaging optical system, and more particularly to a reflection reduction imaging optical system for lithography for manufacturing semiconductor devices.
The present invention further provides an exposure apparatus having the optical system,
The present invention relates to an exposure method using a reflection reduction imaging optical system.

[0002]

2. Description of the Related Art With the increase in the integration density of semiconductor devices, the development of a technique using X-rays as light for exposing a wafer has been promoted. Japanese Patent Application Laid-Open No. 63-31315 discloses a technique in which X-rays from a mask are reflected in the order of a first concave mirror, a convex mirror, and a second concave mirror to reduce the size of a wafer for exposure. The publication also states that the mask and the first
Between the concave mirror of the or between the second concave mirror and the wafer,
Alternatively, a configuration is disclosed in which plane mirrors are arranged on both sides to avoid interference between the wafer and light beams during scanning.
Further, Japanese Patent Application Laid-Open No. 9-251097 discloses that a first concave mirror, a plane mirror, a convex mirror, and a second concave mirror are coaxially arranged in order from the object (mask or reticle) side. There is disclosed a reflection reduction imaging optical system for X-ray lithography in which a convex mirror is formed in an aspherical shape, the convex mirror is arranged on a pupil plane, and formed so as to be telecentric on the image (wafer) side.

[0003]

Problems to be Solved by the Invention
In the configuration disclosed in Japanese Patent No. 1315, the wafer may interfere with the light beam in the synchronous scan between the mask and the wafer, which may cause the light beam to be shaken. Further, in this configuration, the incident angle of X-rays on the plane mirror is about 45 °, and the X-ray reflecting mirror is generally formed by laminating multilayer films. Aberration occurs.

Further, in the configuration of Japanese Patent Application Laid-Open No. 9-251097, since the optical path length from the reflecting mirror closest to the mask to the mask among the reflecting mirrors is long, the apparatus is enlarged. Furthermore, in order to avoid vignetting of a light beam which occurs when a reflecting optical system is constituted by a plurality of mirror systems, the NA on the wafer side is as small as 0.06, and a sufficient resolution cannot be obtained.

The purpose of the present invention is to reduce the size of the entire reflecting optical system and to form an image of the mask M at a predetermined position without causing luminous flux from an object. Therefore, the present invention uses a reflection reduction imaging optical system capable of obtaining sufficient imaging performance with a simple configuration, an exposure apparatus including the reflection reduction imaging optical system, and a reflection reduction imaging optical system. An object of the present invention is to provide an exposure method.

[0006]

In order to achieve the above object, a reflection reduction imaging optical system according to the first aspect of the present invention includes a reflection reduction imaging system for reducing and forming an image of an object on an image plane. In the reduction imaging optical system, the reflection reduction imaging optical system has a plurality of reflecting surfaces, NA on the image side is NAw, reduction magnification of the optical system is β, NAm = NAw × β, the object Of the light rays incident on the reflection reduction imaging optical system from above, in any plane including an optical axis of the reflection reduction imaging optical system or an axis parallel to the optical axis, the optical axis or the optical axis The light ray having the smallest angle Θ1 with the parallel axis and the light ray having the largest angle Θ2 with the optical axis or the axis parallel to the optical axis are SI
NΘ1> 0.1NAm and SINΘ2 <4NAm
It is configured to satisfy.

[0007]

Embodiments of the present invention will be described. The present invention relates to a prior application filed by the same applicant, Japanese Patent Application No.
The present invention relates to a projection optical system used in the exposure apparatus described in No. 47400, and a schematic configuration of the exposure apparatus will be described below with reference to FIG.

A light beam (parallel light beam) supplied from a light source means such as a laser light source enters a reflection element group 2 as a multiple light source forming optical system (optical integrator) almost perpendicularly. Here, the reflection element group 2 is configured such that many reflection elements (optical elements) E are two-dimensionally densely arranged along a predetermined first reference plane P1 perpendicular to the YZ plane. Specifically, as shown in FIG.
A large number of reflective elements E having a reflective curved surface whose contour (outer shape) is formed in an arc shape are provided. And this reflection element group 2
Has five rows of reflective elements arranged in a large number along the Z direction along the Y direction. The five rows of reflecting elements are configured to be substantially circular as a whole. The outline shape (arc shape) of the reflection element E is
This is similar to the shape of an arc-shaped illumination region IF formed on a reflection mask 5 as a surface to be irradiated, which will be described later. Each of the reflection elements E has a shape in which a part of a reflection curved surface having a predetermined curvature radius RE is cut out in a predetermined region eccentric from an optical axis AX (not shown) so that an outline (outer shape) becomes an arc shape. The center CE of the arc-shaped reflection element E is located at a height hE from the optical axis AXE. Therefore, the decentered reflecting surface RSE of each reflecting element E is constituted by an eccentric spherical mirror having a predetermined radius of curvature RE. The reflection surface RSE
Indicates an effective reflection area of the reflection element E that effectively reflects a light beam incident from the light source unit 1. Therefore, the laser light (parallel light beam) L incident in a direction parallel to the optical axis AxE of the reflective element E is condensed at the focal position FE on the optical axis AxE of the reflective element E to form the light source image I. .

Returning to FIG. 1, the laser beam (parallel light beam) incident on the reflecting element group 2 almost perpendicularly is split into a wavefront in an arc shape by the reflection action of a large number of reflecting elements E and deviated from the incident light beam. Light source images corresponding to the number of the large number of reflective elements E are formed at the position P2. In other words, assuming that laser light is incident from a direction parallel to each optical axis AxE of a number of reflection elements E constituting the reflection element group 2, each light is reflected and condensed by each reflection element E. Light source images I are respectively formed on a plane P2 passing through the focal position FE existing on the axis AxE. On the surface P2 on which a large number of light source images I are formed, a large number of secondary light sources are substantially formed. Accordingly, the reflection element group 2 has a function as a light source image forming optical system that forms a large number of light source images I, that is, a multiple light source forming optical system that forms a large number of secondary light sources.

The light beams from the multiple light source images I enter a condenser mirror 3 having an optical axis AxC as a condenser optical system. The condenser reflecting mirror 3 is composed of a single spherical mirror having an effective reflecting surface at a position away from the optical axis AxC, and the spherical mirror has a predetermined radius of curvature RC. Optical axis Ax of condenser reflector 3
C passes through a center position (a position where the optical axis AxC intersects with a plane P2 on which the light source image I is formed) at which a large number of light source images I are formed by the optical element group 2. However, condenser reflector 3
Exists on this optical axis AxC. Note that the optical axis AxC of the condenser reflecting mirror 3 is parallel to each optical axis AxE1 of many optical elements E1 constituting the optical element group 2. Each light flux from a large number of light source images I is reflected and condensed by a condenser reflecting mirror 3 and then reflected by a reflective mask 5 as a surface to be irradiated via a plane mirror 4 as a deflecting mirror.
Are illuminated in an arc in a superimposed manner. The center of curvature OIF of the arc-shaped illumination area IF exists on the optical axis AxP of the projection optical system. Also, if the plane mirror 4 in FIG. 1 is removed, the illumination area IF is formed at the position of the irradiated surface IP in FIG. 1, and the center of curvature OIF of the illumination area IF at this time is Present on the optical axis AxC. Therefore, in the example shown in FIG. 1, the optical axis AxC of the condenser optical system 3 is not deflected by 90 ° by the plane mirror 4.
When the optical axis AxC of the condenser optical system 3 is deflected by 90 ° at the virtual reflecting surface 4a of the plane mirror 4 shown in FIG.
P is coaxial on the reflection mask 5. Therefore, it can be said that these optical axes (AxC, AxP) are optically coaxial. Therefore, the condenser optical system 3 and the projection optical system 6 are arranged so that each optical axis (AxC, AxP) passes optically through the center of curvature OIF of the arc-shaped illumination region IF.

A predetermined circuit pattern is formed on the surface of the reflective mask 5.
Mask stage M movable two-dimensionally along a plane
S is held. The light reflected by the reflective mask 5 is imaged via a projection optical system 6 onto a wafer W coated with a resist as a photosensitive substrate, where the pattern image of the arc-shaped reflective mask 5 is formed. Projected and transferred. The wafer 7 is held on a substrate stage WS that can move two-dimensionally along the XY plane.

Here, the mask stage MS moves two-dimensionally along the XY plane via the first drive system D1, and the substrate stage WS moves along the XY plane via the second drive system D2. Move in a dimension. These two drive systems (D1,
In D2), each drive amount is controlled by the control system 8. Therefore, the control system 8 has two drive systems (D1, D2).
By moving the mask stage MS and the substrate stage WS in directions opposite to each other (in the direction of the arrow) via
The entire pattern formed on the reflective mask 5 is scanned and exposed on the wafer W via the projection optical system 6. Thereby, a good circuit pattern in the photolithography process for manufacturing a semiconductor device is transferred onto the wafer W, so that a good semiconductor device can be manufactured.

FIG. 3 is a schematic diagram showing a first embodiment of the reflection reduction imaging optical system for X-ray lithography according to the present invention, which is shown as the projection optical system 6 in FIG. FIG. 4 shows aberration diagrams of the first embodiment. As shown in the drawing, the optical system according to the present invention comprises a first concave mirror M1, a flat mirror or a convex mirror M3 having a large flat or radius of curvature, in the order of rays traveling from the reflective mask M side to the wafer W side. The second concave mirror M4 and the second concave mirror M4 are arranged coaxially and the wafer W side is telecentric, and the optical path length from the reflective mask M to the first concave mirror M1 is reduced. The reflecting surfaces of at least three or more of the reflecting mirrors are reflection reduction imaging optical systems for X-ray lithography formed in an aspherical shape.

Hereinafter, the reason and operation of the above-described configuration will be described. In the present invention, in particular, the reduction magnification β is 1
This is effective for an optical system of ３ to 1/10. With the optical system according to the present invention, even if the NA (NAw) on the wafer W side is larger than 0.1, the vignetting of the light beam that occurs when the optical system is configured by a plurality of reflection systems is avoided without increasing the size of the entire system. Further, aberrations (astigmatism, curvature of field, and coma) relating to off-axis imaging with respect to the arc-shaped region (ring field RF) are more favorably corrected.

For this purpose, as shown in FIG. 7, the reflection reduction imaging optical system 6 according to the present invention reduces and forms an image of the reflection type mask M illuminated by the illumination light flux IL on the surface of the wafer W. When the NA on the wafer W side (image side) is NAw, the reduction magnification of the optical system is β, and NAm = NAw × β, the light is reflected from an arbitrary effective area on the reflective mask surface and the reflected reduced image is formed. Of the light rays incident on the optical system 6, in an arbitrary plane including the optical axis AxP of the reflection reduction imaging optical system or an axis AxQ parallel thereto, a light ray having a minimum incident angle Θ1 and a light ray having a maximum incident angle Θ2 are obtained. On the other hand, it is configured so as to satisfy the following conditional expressions: SINΘ1> 0.1NAm (1) and SINΘ2 <4NAm (2). Here, the SIN
If Θ1 exceeds the conditional expression (1) “0.1 NAm”, the illuminating light beam and the incident light beam reflected by the reflective mask M interfere with each other, and it becomes easy for vignetting of the light beam to occur. The entire optical system is undesirably large. On the other hand, if the SIN # 2 exceeds the conditional expression (2) “4NAm”, the reflected light from the reflective mask M may be uneven in brightness, which is not preferable. Furthermore, because of the polarization characteristics of polarized light depending on the direction within the mask plane, uneven resolution may occur due to the direction, which is not preferable. Further, when there is a step in the mask pattern, shadows occur in the line width direction, resulting in a line width error, which is not preferable.

Here, in order to further reduce the unevenness in brightness of the reflected light, the unevenness in resolution due to the reflection characteristic of the polarized light, and the line width error, conditional expression (2) further satisfies SINΘ2 <3NAm. (3) As shown in FIG. 3, the optical system according to the present invention includes a first concave mirror M1, a flat mirror M2 and a convex mirror M3 having a large flat surface or radius of curvature in the order in which light rays travel from the reflective mask M toward the wafer W. , The second concave mirror M4
And four reflecting mirrors are arranged coaxially, and the wafer W side is configured to be telecentric. At least three or more of the four reflecting mirrors are formed in an aspherical shape, and aberrations relating to off-axis imaging with respect to an arc-shaped region (ring field RF) (astigmatism, image Surface curvature and coma aberration) are better corrected.

Further, assuming that the optical path length from the reflection type mask M to the first concave mirror M1 is D, it is necessary to satisfy D <1200 mm (4). The present invention uses an X-ray having a wavelength of 13 nm as a light source, and envisions an optical system for printing a pattern having a line width of 70 nm or less, and a device for evacuating the optical path is required. The apparatus is undesirably increased in size. Further, using another light source, a medium (an inert gas such as He gas, nitrogen gas, and air, and air) in the optical path.
When the above-mentioned condition range is exceeded, when the medium fluctuates due to heat or the like, the medium is easily affected by the fluctuation and deteriorates the imaging performance. Further, D <800 mm (5) is preferable in order to further reduce the size and reduce the influence of fluctuation, and D <400 mm (6) in order to further reduce the size and reduce the effect of fluctuation. Is preferred.

It is preferable that at least one of the reflecting mirrors has a radius of curvature at the apex of infinity. In particular, it is preferable that the reflecting mirror M2 has a large radius of curvature. , | R |> 3000 mm (7) is preferable, and | R |> 1000 mm (8) has a sufficient effect. However, if it exceeds this range, the curvature of the image plane in the ring field RF becomes large, which is not preferable for practical use.

The present invention assumes an optical system for printing a pattern with a line width of 70 nm or less using X-rays having a wavelength of 13 nm as a light source. The reflectivity of the surface of the reflecting mirror used in the present optical system is low. Since the number of reflecting mirrors is preferably as small as possible, the above-described four-mirror configuration is shown. However, it goes without saying that a configuration in which a reflecting mirror is further added still includes the features of the present invention. However, in that case, measures such as increasing the power of the light source are required.

According to the above arrangement, the size of the entire reflecting optical system can be reduced, and the image of the reflective mask M can be favorably formed at a predetermined position without vignetting of the light beam from the object. The aperture stop position is on or near the convex mirror M3 and on or near the second concave mirror M4, and the light beam with the minimum incident angle Θ1 and the light beam with the maximum incident angle Θ2 on the mask M side and the wafer W The side defines a telecentric ray.

The term "telecentric" as used herein means that if an off-axis chief ray has a tilt Θw, the center of gravity of a light beam shifts when defocused within the depth of focus, but the shift amount is a line printed on the wafer. Width (40 at 13nm wavelength)
(Up to 70 nm) is preferable. That is, if the NA of the wafer W is NAw, the wavelength of the light source is λ, and T = (resolution / depth of focus) = (0.61λ / NAw) / (2λ / NAw ² ) = 0.30 (NAw), then Θw (Unit: radian) is preferably Δw <T / 2, that is, Δw <0.15 (NAw) (9). In order to further suppress the shift of the light beam, it is more preferable that Θw <T / 3, that is, Θw <0.10 (NAw) (10). Further, in order to further suppress the shift of the light beam, it is most preferable that Θw <T / 10, that is, Θw <0.030 (NAw) (11).

As described above, in the reflection reduction optical system according to the present invention, since the reduction side, that is, the wafer W side is a telecentric ring field, the same exposure condition can be obtained regardless of the location in the ring field RF.
Further, since the angle of incidence of light on each of the reflecting surfaces M1 to M4 (the angle from the normal of the reflecting surface) is almost 0 °, wavefront aberration due to phase shift by each reflecting surface formed by the multilayer film is generated. Is suppressed.

Hereinafter, the specifications of this embodiment will be described. In [Overall Specifications], β is the reduction magnification of the reflection reduction optical system, Θ1 is the minimum incident angle from the mask, Θ2 is the maximum incident angle from the mask, Θw is the inclination angle of the principal ray on the wafer side (unit: Radian), NAw is the numerical aperture on the wafer side, NAm = NAw ×
β and RF represent a ring field. [Reflector specifications]
The first column is the number of the reflection surface from the mask M side, and the second column is the second column.
Column R is a vertex radius of curvature of each reflecting surface, third column D is a vertex interval of each reflecting surface, fourth column Φ is an effective diameter of each reflecting surface,
(Unit of R, D, Φ: mm). The aspheric shape is
It is expressed by the following equation.

[0024]

Table 1 S (Y) = (Y ² / R) / [1+ ｛1- (1+
^{K) (Y 2 / R 2} )} 0.5] + C4Y 4 + C6Y 6 + C8Y
⁸ + C10Y ¹⁰ + C12Y ¹² + C14Y ¹⁴ Y: Height in the direction perpendicular to the optical axis S (Y): Displacement in the optical axis direction at height Y R: Radius of curvature K: Conic coefficient Cn: nth order aspheric coefficient (N: 4, 6, 8, 10, 1
2, 14) Em: × 10 ^−m (m: positive integer)

[0025]

Table 2 [Overall Specifications of Example 1] Magnification β: -0.25 (-) SIN０．００1: 0.00520 SINΘ2: 0.08846 w: 0 (complete telecentric) Mask side NAm: 0.04 (Wafer side NAw: 0.16) Mask side RF inner radius: 80 (Wafer side RF inner radius: 20) Mask side RF outer radius: 84 (Wafer side RF outer radius: 21)

[0026]

Table 3 [Reflection Mirror Specifications of Example 1] Reflection surface number R D Φ M: ２０４ 204.778320 1: −689.28272 −66.922497 Aspherical reflection surface K = −0.246746 C4 = 0. 291983E-08 C6 = -0.941799E-12 C8 = 0.796612E-16 C10 = -0.283781E-20 2: １６ 164.665248 Aspherical reflective surface K = 0.000000 C4 = 0.130336E-08 C6 = -0.955739E-12 C8 = 0.128585E-15 C10 = -0.747147E-20 3: 209.668185 -235.855378 48.9 Aspherical reflective surface K = 1.906295 C4 = 0.341266E-07 C6 = 0.759121E-12 C8 = 0.326635E −14 C10 = −0.342118E−17 C12 = 0.157360E−20 4: 295.3232280 268.9911962 126.9 Aspherical reflective surface K = 0.046240 C4 = 0.218171E−09 C6 = 0.351419E− 14 C8 = 0.252583E-18 C10 = -0.415062E-22 C12 = 0.283044E-26 W: ∞

[0027]

Table 4 [Overall Specifications of Example 2] Magnification β: -0.25 (-) SIN０．００1: 0.00689 SINΘ2: 0.09288 w: 0 (complete telecentric) Mask side NAm: 0.04 (Wafer side NAw: 0.16) Mask side RF inner radius: 80 (Wafer side RF inner radius: 20) Mask side RF outer radius: 84 (Wafer side RF outer radius: 21)

[0028]

Table 5 [Reflection Mirror Specifications of Example 2] Reflection surface number R D Φ M: １８188.181979 1: −582.04702 −60.438860 Aspherical reflection surface K = 0.664782 C4 = 0.2020884E -09 C6 = 0.300766E-12 C8 = -0.302981E-16 C10 = 0.139215E-20 2: -3920.65749 141.522837 Aspherical reflective surface K = 0.000000 C4 = 0.587422E-08 C6 = 0.390832E-12 C8 = -0.649038E-16 C10 = 0.475712E-20 3: 209.61809 -254.155901 52.4 Aspherical reflective surface K = 2.667734 C4 = 0.449671E-07 C6 = 0.431318E-11 C8 =- .805710E-15 C10 = 0.837313E-18 C12 = -0.751918E-22 4: 298.70118 264.3351744 130.7 Aspherical reflective surface K = 0.040532 C4 = 0.188198E-09 C6 = 0. 353975E-14 C8 = 0.567359E-19 C10 = -0.629708E-23 C12 = 0.501309E-27 W: ∞ FIGS. 4 and 6 show the reflection and reduction optical systems of the first and second embodiments. FIG. 3 shows a coma aberration diagram on a wafer W. This coma aberration diagram is obtained by tracing light rays from the mask M side using light having a wavelength of 13 nm. Here, FIG. 4A is a coma aberration diagram in the meridional direction at an image height Y = 21 mm, FIG. 4B is a coma aberration diagram in the meridional direction at an image height Y = 20.5 mm, and FIG. High Y = 20m
FIG. 4D is a coma aberration diagram in the meridional direction at m.
4A is a coma aberration diagram in the sagittal direction at an image height Y = 21 mm, FIG. 4E is a coma aberration diagram in a sagittal direction at an image height Y = 20.5 mm, and FIG. 4F is a sagittal direction diagram at an image height Y = 20 mm. It is a coma aberration figure. FIG.
6A is a coma aberration diagram in the meridional direction when the image height Y is 21 mm, FIG. 6B is a coma aberration diagram in the meridional direction when the image height Y is 20.5 mm, and FIG.
FIG. 6D is a coma aberration diagram in the sagittal direction when the image height Y is 21 mm, FIG. 6E is a coma aberration diagram in the sagittal direction when the image height Y is 20.5 mm, FIG. 6F shows the object height Y = 2.
It is a coma aberration figure in the sagittal direction at 0 mm.

As can be seen from the figure, according to the present embodiment, good image forming performance is obtained. As described above, according to the present embodiment, a mask M and a wafer W are synchronously scanned in a ring field, so that an exposure apparatus with a wide field of view can be obtained. In the ring field, an image with high resolution and low distortion can be obtained. Is obtained.

The present invention assumes an optical system for printing a pattern having a line width of 70 nm or less using X-rays having a wavelength of 13 nm as a light source. However, since the present optical system is constituted by a reflecting mirror, it has a different wavelength. Needless to say, it can be used satisfactorily. That is, 1 nm hard X-ray, 5 to 15 nm soft X-ray, 126 nm, 146 nm, 157 nm, 172
nm light source, 193 nm ArF excimer laser light source, 248 nm KrF excimer laser light source, and the like.

Although the reflecting mirrors M1, M2, M3, and M4 are shown symmetrically with respect to the optical axis AxP, portions that are not used (light is not reflected) may be deleted (off-axis type). Further, for the sake of arrangement, even if a plane mirror is arranged at an arbitrary position in the optical path and the optical path is bent three-dimensionally, it is substantially the same as the present invention. Although the reflection reduction imaging optical system according to the present invention has been described using a reflection type mask, it goes without saying that the same imaging performance can be obtained even when a transmission type mask is used.

[0032]

As described above, according to the present invention, a reflection reduction imaging optical system suitable for, for example, X-ray lithography, which can obtain sufficient imaging performance with a simple configuration, can be obtained. By applying this optical system to an exposure apparatus, a good mask pattern image can be transferred onto a photosensitive substrate. Also, by using such an optical system in a photolithography process of transferring a mask pattern image onto a photosensitive substrate, a good mask pattern image can be transferred onto the photosensitive substrate. Thereby, a good semiconductor device can be manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an exposure apparatus using a reflection reduction imaging optical system of the present invention.

FIG. 2 is a front view showing a configuration of a reflection element group 2 shown in FIG. 1;

FIG. 3 is a configuration diagram showing a first embodiment of the present invention.

FIG. 4 is an aberration diagram of the first embodiment.

FIG. 5 is a configuration diagram showing a second embodiment of the present invention.

FIG. 6 is an aberration diagram of the second embodiment.

FIG. 7 is a schematic diagram illustrating light rays incident from a reflective mask.

[Explanation of symbols]

 M: Mask W: Wafer M1: First concave mirror M2: Reflecting mirror M3: Convex mirror M4: Second concave mirror

Claims (6)

[Claims] 1. A reflection reduction imaging optical system for reducing and forming an image of an object on an image plane, wherein the reflection reduction imaging optical system has a plurality of reflection surfaces and has an NA on the image side. NAw, the reduction magnification of the optical system is β, NAm = NAw × β, and among the light rays incident on the reflection reduction imaging optical system from above the object plane, the optical axis or optical axis of the reflection reduction imaging optical system In an arbitrary plane including a parallel axis, a light ray having the smallest angle と 1 with the optical axis or an axis parallel to the optical axis, and an angle Θ2 between the optical axis or an axis parallel to the optical axis. A reflection-reduction imaging optical system characterized in that a light beam having a maximum value of SINΘ1> 0.1NAm and SINΘ2 <4NAm are satisfied. 2. The reflection-reduction imaging optical system includes four reflecting mirrors, and at least three of the four reflecting mirrors have aspherical reflecting surfaces. The reflection reduction imaging optical system according to claim 1, wherein: 3. An optical path length on the optical axis from the first reflecting surface receiving light from the object to the object among the plurality of reflecting mirrors, wherein D <1200 mm. The reflection reduction imaging optical system according to claim 1 or 2, wherein: 4. The reflection reduction imaging optical system according to claim 2, wherein at least one of said reflecting mirrors has a vertex curvature radius of infinity. 5. A mask stage for holding a mask on the object plane, a substrate stage for holding a photosensitive substrate on the image plane, and an illumination system for illuminating the mask with exposure light from a predetermined oblique direction; The reflection reduction imaging optical system according to any one of claims 1 to 4, wherein light reflected from the mask in an oblique direction is collected, and a pattern image of the mask is projected on the photosensitive substrate. An exposure apparatus, wherein a pattern on the entire surface of the mask is exposed on the photosensitive substrate by moving a mask stage and a substrate stage relative to the reflection reduction imaging optical system. 6. An exposure method using a reflection reduction imaging optical system according to claim 1, wherein an illumination step of illuminating a mask disposed on said object plane, and reflection reduction imaging is performed. Projecting the pattern image of the mask on a photosensitive substrate set on the image plane by an optical system.