WO2003088330A1

WO2003088330A1 - Projection optical system, exposure system and exposure method

Info

Publication number: WO2003088330A1
Application number: PCT/JP2003/004142
Authority: WO
Inventors: Yasuhiro Omura; Toshihiko Ozawa
Original assignee: Nikon Corporation
Priority date: 2002-04-03
Filing date: 2003-03-31
Publication date: 2003-10-23
Also published as: JP2003297729A; AU2003221102A1; TW200402603A

Abstract

An projection optical system having good optical features without being substantially affected by double refraction even when a crystal material showing an intrinsic double refraction such as fluorite is used. The projection optical system includes a crystal transmitting member formed of a crystal material to form an image on a first plane (R) onto a second plane (W). A light transmitting phase correcting member (PC) is provided for correcting the phase difference between mutually orthogonal polarization components produced due to a crystal transmitting member. The phase correcting member is formed of a uniaxial crystal with its optical axis almost agreeing with the optical axis (AX1) of an optical system.

Description

Description Projection optical system, exposure apparatus and exposure method

The present invention relates to a projection optical system, an exposure apparatus, and an exposure method, and more particularly to a projection optical system suitable for an exposure apparatus used when a micro device such as a semiconductor element or a liquid crystal display element is manufactured in a photolithography process. It is. Background art

When forming micropatterns for electronic devices (microdevices) such as semiconductor integrated circuits and liquid crystal displays, the pattern of the photomask (also referred to as a reticle) drawn by enlarging the pattern to be formed by about 4 to 5 times is projected. A method of reducing exposure transfer onto a photosensitive substrate (substrate to be exposed) such as a wafer using an exposure apparatus is used. In this type of projection exposure apparatus, the exposure wavelength keeps shifting to shorter wavelengths in order to cope with miniaturization of semiconductor integrated circuits.

At present, the exposure wavelength of the KrF excimer laser is 248 nm, but the shorter wavelength of the ArF excimer laser, 193 nm, is entering the stage of practical use. Further, the wavelength 1 5 7 nm of F ₂ laser and the wavelength 1 4 6 nm of K r ₂ laser and foremost, the wave length 1 2 6 nm of A r _2, single The first class, the wavelength band so-called vacuum ultraviolet region A projection exposure apparatus using a light source for supplying light has also been proposed. In addition, since higher resolution can be achieved by increasing the numerical aperture (NA) of the projection optical system, not only development for shortening the exposure wavelength, but also development of a projection optical system with a larger numerical aperture Has also been made.

Optical materials (lens materials) with good transmittance and uniformity for exposure light in the ultraviolet region having such a short wavelength are limited. In a projection optical system that uses an ArF excimer laser as a light source, synthetic quartz glass can be used as a lens material, but chromatic aberration cannot be sufficiently corrected with one type of lens material. Lens Calcium iodide crystals (fluorite) are used. On the other hand, the projecting projection optical system as a light source an F ₂ laser, the lens material available is limited to substantially calcium fluoride crystal (fluorite).

Recently, it has been reported that intrinsic birefringence exists for calcium fluoride crystal (fluorite), which is a crystal material belonging to the cubic system, for ultraviolet rays having such a short wavelength. In an ultra-high-precision optical system such as a projection optical system used in the manufacture of electronic devices, aberrations caused by the birefringence of the lens material are fatal, and a lens configuration that substantially avoids the effects of birefringence It is essential to adopt lens design.

The present invention has been made in view of the above-mentioned problems. For example, even when a crystalline material having intrinsic birefringence such as fluorite is used, good optical properties are obtained without substantially being affected by birefringence. It is an object to provide a projection optical system having high performance. Further, according to the present invention, there is provided an exposure apparatus and an exposure method capable of performing high-resolution and high-accuracy projection exposure using a projection optical system having good optical performance substantially without being affected by birefringence. The purpose is to provide the law. Disclosure of the invention

According to a first aspect of the present invention, there is provided a projection optical system that includes a crystal transmission member formed of a crystalline material and forms an image of a first surface on a second surface. The present invention provides a projection optical system including a light transmissive phase correcting member for correcting a phase difference between mutually orthogonal polarization components generated due to the above. As the polarization components orthogonal to each other, the R polarization component oscillating in the direction including the above normal line (radiation direction R) in the plane with the optical axis as the normal line, and the oscillation direction orthogonal to the R polarization component are considered. It is preferable to employ a polarized light component (a polarized light component having a vibration direction in the circumferential direction 0 around the normal line).

According to a preferred aspect of the first invention, the phase correction member is formed of a uniaxial crystal and has an optical axis substantially coincident with an optical axis of an optical system. Further, the crystal transmission member is formed of fluorite (C a F ₂ ) and has a crystal axis [111] or the crystal axis [111]. A pair of light transmitting members formed so that a crystal axis optically equivalent to the crystal axis [11 1] and an optical axis of the optical system substantially coincide with each other; and the phase correction member has a refractive index with respect to ordinary light. When No is defined and Ne is the refractive index with respect to extraordinary light, it is formed of a negative uniaxial crystal satisfying Ne <No, and is formed so that its optical axis substantially coincides with the optical axis.

Alternatively, all of the crystal transmission members are formed of fluorite (C aF ₂ ), and the crystal axis [11 1] or a crystal axis optically equivalent to the crystal axis [11 1] and the optical system When the refractive index for ordinary light is No and the refractive index for extraordinary light is Ne, the phase correction member is formed of a negative uniaxial crystal that satisfies Ne <No. It is preferable that the optical axis is formed so as to substantially coincide with the optical axis. It is preferable that the negative uniaxial crystal is quartz (Si ₂ ) or Leicauff (LiCaAlF ₆ ).

Alternatively, the crystal transmission member is made of fluorite (CaF ₂ ), and the crystal axis [100] or a crystal axis optically equivalent to the crystal axis [100] substantially coincides with the optical axis of the optical system. When the refractive index for ordinary light is No and the refractive index for extraordinary light is Ne, the phase correction member is a positive uniaxial member that satisfies Ne> No. It is preferable that the optical axis is formed of a crystalline crystal and that its optical axis substantially coincides with the optical axis. Preferably, the positive uniaxial crystal is magnesium fluoride (MgF ₂ ).

Alternatively, the crystal transmission member is formed of fluorite (CaF ₂ ), and the crystal axis [110] or a crystal axis optically equivalent to the crystal axis [110] and the optical axis of the optical system are different. The phase correction member has a pair of light transmitting members formed so as to substantially coincide with each other. When the refractive index for ordinary light is No and the refractive index for extraordinary light is Ne, a negative value satisfying Ne <No is satisfied. It is preferable that the optical axis is formed of a uniaxial crystal and that its optical axis substantially coincides with the optical axis. Incidentally, the negative uniaxial crystal is preferably a crystal (S i 0 ₂₎ or Raikafu _{(L i C aA 1 F 6} ).

According to a preferred aspect of the first invention, the phase correction member is disposed near the first surface, near the second surface, or near a surface optically conjugate with the first surface. Have been. Further, it is preferable that the phase correction member is arranged at a pupil position of the optical system or in the vicinity thereof. Note that, in the phase correction member, the distance between the first surface and the second surface is L, the first surface, the second surface, a surface optically conjugate with the first surface, or Assuming that the distance from the pupil position to the phase correction member is D, the arrangement is preferably such that IDZLI ≦ 0.15 is satisfied. Further, it is preferable that a plurality of the phase correction members are provided.

Further, according to a preferred aspect of the first invention, at least one concave reflecting mirror is further provided, wherein the concave reflecting mirror is configured such that a light beam traveling toward the concave reflecting mirror and a light beam reflected from the concave reflecting mirror are formed. A reciprocating optical path that passes therethrough is formed, and the phase correction member is disposed in the forward and backward optical paths. In this case, it is preferable that the concave reflecting mirror is used at approximately the same magnification, and is arranged at or near the pupil position of the optical system.

The projection optical system is a re-imaging optical system that forms an intermediate image of the first surface in an optical path between the first surface and the second surface, and the phase correction member includes the intermediate image. It is located near the formation position of. Further, the projection optical system includes one concave reflecting mirror, and forms a double-image catadioptric refraction that forms an intermediate image of the first surface in an optical path between the first surface and the second surface. It is an optical system, and it is preferable that the concave reflecting mirror is disposed in an optical path between the first surface and the intermediate image.

Alternatively, the projection optical system includes one concave reflecting mirror, and forms an intermediate image of the first surface in an optical path between the first surface and the second surface. It is an optical system, and it is preferable that the optical axes of all the light transmitting members and the concave reflecting mirror that constitute the projection optical system are set substantially parallel to each other. Alternatively, the projection optical system includes one concave reflecting mirror, and forms a first intermediate image and a second intermediate image of the first surface in an optical path between the first surface and the second surface. It is a reflection-refractive optical system of the image forming type, and it is preferable that the concave reflecting mirror is arranged in an optical path between the first intermediate image and the second intermediate image.

Further, according to a preferred aspect of the first invention, all optical members constituting the projection optical system are light transmitting members. Further, the projection optical system has a single optical axis extending linearly, and all the optical members constituting the projection optical system have the optical axis of the single optical axis. It is preferable that they are arranged so as to substantially coincide with one optical axis. Further, the projection optical system is an optical system that is substantially telecentric on both the first surface side and the second surface side, and the phase correction member is formed of a uniaxial crystal and has an optical axis that is an optical system. It is preferable that it is formed so as to substantially coincide with the optical axis and has a parallel plane shape. Further, it is preferable that an image of the first surface is formed on the second surface based on light having a wavelength of 200 nm or less.

In the second invention of the present invention, an illumination system for illuminating the mask set on the first surface, and an image of a pattern formed on the mask is placed on a photosensitive substrate set on the second surface. There is provided an exposure apparatus comprising the projection optical system according to the first invention for forming.

In the third invention of the present invention, the mask set on the first surface is illuminated, and the image of the pattern formed on the mask is set on the second surface via the projection optical system of the first invention. An exposure method is provided, which comprises projecting and exposing on a photosensitive substrate. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram for explaining the crystal axis orientation of fluorite.

2A to 2C are diagrams for explaining the method of Burnett et al., And show the distribution of the birefringence index with respect to the incident angle of a light beam.

FIGS. 3A to 3C are diagrams for explaining the first method proposed in the present invention, and show the distribution of the birefringence index with respect to the incident angle of a light beam.

FIGS. 4A to 4C are diagrams for explaining the second method proposed in the present invention, and show the distribution of the birefringence index with respect to the incident angle of a light beam.

FIG. 5 is a diagram showing a phase map at a pupil of a projection optical system including a fluorite pair lens having a crystal axis of [111].

FIG. 6 is a diagram showing a phase map at a pupil of a projection optical system including a fluorite pair lens having a crystal axis of [100].

FIG. 7 is a diagram showing a phase map at the pupil of the projection optical system including the fluorite pair lens with the crystal axis [111] and the fluorite pair with the crystal axis [100]. FIG. 8 is a diagram showing a phase map at a pupil of a projection optical system including a plane-parallel plate formed of a positive uniaxial crystal.

FIG. 9 is a diagram showing a phase map at a pupil of a projection optical system including a plane-parallel plate formed of a negative uniaxial crystal.

FIG. 10 is a diagram showing a phase map at a pupil of a projection optical system including a fluorite pair lens having a crystal axis [111] and a plane-parallel plate formed of a negative uniaxial crystal.

FIG. 11 is a diagram showing a phase map at a pupil of a projection optical system including a fluorite pair lens having a crystal axis of [100] and a plane-parallel plate formed of a positive uniaxial crystal.

FIG. 12 is a view schematically showing a configuration of an exposure apparatus having a projection optical system according to an embodiment of the present invention.

FIG. 13 is a diagram schematically showing a configuration of a projection optical system according to Example 1 of the present embodiment.

FIG. 14 is a diagram schematically showing a configuration of a projection optical system according to a first modification of the first embodiment.

FIG. 15 is a diagram schematically showing a configuration of a projection optical system according to a second modification of the first embodiment.

FIG. 16 is a diagram schematically showing a configuration of a projection optical system according to a third modification of the first embodiment.

FIG. 17 is a diagram schematically showing a configuration of a projection optical system according to a fourth modification of the first embodiment.

FIG. 18 is a diagram schematically showing a configuration of a projection optical system according to a fifth modification of the first embodiment.

FIG. 19 is a diagram schematically showing a configuration of a projection optical system according to Example 2 of the present embodiment.

FIG. 20 is a diagram schematically showing a configuration of a projection optical system according to a first modification of the second embodiment.

FIG. 21 is a diagram schematically showing a configuration of a projection optical system according to a second modification of the second embodiment. Two

-7-FIG. 22 is a diagram schematically showing a configuration of a projection optical system according to Example 3 of the present embodiment.

FIG. 23 is a diagram schematically showing a configuration of a projection optical system according to a first modification of the third embodiment.

FIG. 24 is a diagram schematically showing a configuration of a projection optical system according to a second modification of the third embodiment.

FIG. 25 is a diagram schematically showing a configuration of a projection optical system according to Example 4 of the present embodiment.

FIG. 26 is a diagram schematically showing a configuration of a projection optical system according to a first modification of the fourth embodiment.

FIG. 27 is a diagram schematically showing a configuration of a projection optical system according to a second modification of the fourth embodiment.

FIG. 28 is a diagram schematically showing a configuration of a projection optical system according to Example 5 of the present embodiment.

FIG. 29 is a diagram schematically showing a configuration of a projection optical system according to a first modification of the fifth embodiment.

FIG. 30 is a diagram schematically showing a configuration of a projection optical system according to a second modification of the fifth embodiment.

FIG. 31 is a flowchart of a method for obtaining a semiconductor device as a micro device.

FIG. 32 is a flowchart of a method for obtaining a liquid crystal display element as a micro device. BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a diagram for explaining the crystal axis orientation of fluorite. Referring to FIG. 1, the crystal axis of fluorite is defined based on a cubic XYZ coordinate system. That is, the crystal axis [100] is defined along the + X axis, the crystal axis [010] is defined along the + Y axis, and the crystal axis [001] is defined along the + Z axis. . In addition, the crystal axis [101] is in a direction at 45 degrees to the crystal axis [100] and the crystal axis [001] in the XZ plane, and the direction is 45 degrees to the crystal axis [100] and the crystal axis [010] in the XY plane. The crystal axis [1 10] is defined in the YZ plane, and the crystal axis [01 1] is defined in a direction forming 45 degrees with the crystal axis [010] and the crystal axis [001] in the YZ plane. Furthermore, the crystal axis [1 1 1] is defined in a direction that forms an equal acute angle to the + X axis, the + Y axis, and the + Z axis.

Although FIG. 1 shows only the crystal axis in the space defined by the + X axis, + Y axis, and + Z axis, the crystal axis is similarly defined in other spaces. In the case of fluorite, the direction of the crystal axis [1 1 1] shown by the solid line in Fig. 1 and the equivalent crystal axes [1 1 1 1], [1-1 1], [1 1 1 1] In the direction, the birefringence is almost zero (minimum). Similarly, the crystal axes indicated by solid lines in FIG. 1 [100], [010], [00]

In the 1] direction, birefringence is almost zero (minimum). On the other hand, the crystal axes [1 10], [10 1], [01 1] indicated by broken lines in FIG.

In the [1-110], [1-101], and [01-1] directions, the birefringence is maximum.

By the way, at the 2nd International Symposium on 157nm Lithography (May 15, 2001)

John H. Burnett et al. Of IST reported that both empirical and theoretical studies have confirmed the existence of intrinsic birefringence in fluorite. According to this announcement, fluorite has crystal axes [1 10], [-1 10], [10

1], [-101], [01 1], and [01-1] in the six directions, a maximum of 6.5 nmZcm for light with a wavelength of 157 nm, and a maximum of 3. It has a value of birefringence of 6 nm / cm. These birefringence values are substantially larger than the permissible value of random birefringence of 1 nm / cm, and the effect of birefringence accumulates through multiple lenses to the extent that it is not random. there is a possibility.

Burnett et al. In the above-mentioned presentation disclosed a method for reducing the effects of birefringence. 2A to 2C are diagrams for explaining the method of Burnett et al., And show the distribution of the birefringence index with respect to the incident angle of a light ray (the angle between the light ray and the optical axis). In Figs.2A to 2C, five concentric circles indicated by broken lines in the figure represent 10 degrees on one scale. You. Therefore, the innermost circle represents a region with an incident angle of 10 degrees with respect to the optical axis, and the outermost circle represents a region with an incident angle of 50 degrees with respect to the optical axis.

A black circle indicates a region having a relatively large refractive index and no birefringence, and a white circle indicates a region having a relatively small refractive index and no birefringence. On the other hand, a thick circle and a long double arrow indicate the direction of a relatively large refractive index in a birefringent area, and a thin circle and a short double arrow indicate a relatively small refractive index direction in a birefringent area. The following notation is the same in FIGS. 3A to 3C below.

In the method of Burnett et al., The optical axis and crystal axis [1 1 1] of a pair of fluorite lenses (a lens formed of fluorite) (or a crystal axis optically equivalent to the crystal axis [1 1 1]) And a pair of fluorite lenses are relatively rotated about the optical axis by 60 degrees. Therefore, the distribution of birefringence in one fluorite lens is as shown in FIG. 2A, and the distribution of birefringence in the other fluorite lens is as shown in FIG. 2B. As a result, the distribution of birefringence in the entire pair of fluorite lenses is as shown in FIG. 2C.

In this case, referring to FIGS. 2A and 2B, the region corresponding to the crystal axis [11 1] coincident with the optical axis is a region having a relatively small refractive index and no birefringence. The regions corresponding to the crystal axes [100], [010], and [001] are regions having a relatively large refractive index and no birefringence. Further, the regions corresponding to the crystal axes [1 10], [101], [01 1] are birefringent regions having a relatively small refractive index for circumferentially polarized light and a relatively large refractive index for radially polarized light. Becomes Thus, each fluorite lens is maximally affected by birefringence in the range of 35.26 degrees from the optical axis (the angle between the crystal axis [1 1 1] and the crystal axis [1 10]). You can see.

On the other hand, referring to FIG. 2C, by rotating the pair of fluorite lenses relatively by 60 degrees, the crystal axis [1 110], It can be seen that the effects of [101] and [01 1] are reduced. Then, in a region at 35.26 degrees from the optical axis, a birefringent region having a smaller refractive index for circumferentially polarized light than that for radially polarized light remains. In other words, Burnett et al. By using this method, the distribution that is rotationally symmetric with respect to the optical axis remains, but the effect of birefringence can be significantly reduced.

In the first method proposed in the present invention, the optical axis and the crystal axis [100] (or the crystal axis [100]) of a pair of fluorite lenses (generally, a transmission member formed of fluorite) are used. And a pair of fluorite lenses are relatively rotated about the optical axis by about 45 degrees. Here, the crystal axes that are optically equivalent to the crystal axis [100] are the crystal axes [010] and [001].

FIGS. 3A to 3C are diagrams for explaining the first method proposed in the present invention, and show the distribution of the birefringence index with respect to the incident angle of a light ray (the angle between the light ray and the optical axis). I have. In the first method proposed in the present invention, the distribution of the birefringence in one fluorite lens is as shown in FIG. 3A, and the distribution of the birefringence in the other fluorite lens is in FIG. 3B. As shown. As a result, the distribution of the birefringence of the entire pair of fluorite lenses is as shown in FIG. 3C.

Referring to FIGS. 3A and 3B, in the first method proposed in the present invention, the region corresponding to the crystal axis [100] coinciding with the optical axis has a birefringence having a relatively large refractive index. It is an area without. The regions corresponding to the crystal axes [1 1 1], [1-11], [1-1 1-1], [1 1-1] are the regions with relatively small refractive index and no birefringence. Become. Furthermore, the regions corresponding to the crystal axes [101], [10-1], [1 10], [1-10] have relatively large refractive indices for circumferentially polarized light and have relatively large refractive indices for radially polarized light. This results in a relatively small birefringent region. Thus, it can be seen that the individual fluorite lenses are most affected by the birefringence in the range of 45 degrees from the optical axis (the angle between the crystal axis [100] and the crystal axis [101]).

On the other hand, referring to FIG. 3C, by rotating the pair of fluorite lenses relatively by 45 degrees, the crystal axes of the pair of fluorite lenses having the maximum birefringence [10 1], [ The effects of 10-1], [1 10], and [1 _ 10] are considerably reduced, and the refractive index for circumferentially polarized light is larger than that for radially polarized light in the region at 45 degrees from the optical axis. A birefringent region will remain. In other words, by using the first method proposed in the present invention, a distribution which is rotationally symmetric with respect to the optical axis remains, Can be significantly reduced.

In the first method proposed in the present invention, to relatively rotate one fluorite lens and the other fluorite lens about the optical axis by about 45 degrees means that one fluorite lens and the other fluorite lens A predetermined crystal axis (eg, crystal axis [0 1 0], [00 1], [0 1 1] or [0 1–1]) oriented in a different direction from the optical axis of the fluorite lens Means about 45 degrees relative to. Specifically, for example, the relative angle of the crystal axis [010] of one fluorite lens and the crystal axis [010] of the other fluorite lens about the optical axis is about 45 degrees. means.

In addition, as is clear from FIGS. 3A and 3B, when the crystal axis [100] is used as the optical axis, the rotational asymmetry of the effect of birefringence around the optical axis is 90 degrees. Appears with a period. Therefore, in the first method proposed in the present invention, relatively rotating about the optical axis by about 45 degrees means that relatively rotating about the optical axis is about 45 degrees + (nX 90 degrees). This is equivalent to rotating relatively by 45 degrees, 135 degrees, 225 degrees, or 315 degrees (where n is an integer).

On the other hand, in the method of Burnett et al., Rotating one fluorite lens and the other fluorite lens relatively by about 60 degrees about the optical axis means that one fluorite lens and the other fluorite lens A predetermined crystal axis oriented in a direction different from the optical axis of the lens (for example, the crystal axis [—11 1], [11-1], or [1 1 1 1]) This means that the relative angle is about 60 degrees. Specifically, for example, the relative angle of the crystal axis [—111] of one fluorite lens and the crystal axis [111] of the other fluorite lens about the optical axis is about Means 60 degrees.

Also, as is clear from FIGS. 2A and 2B, when the crystal axis [1 1 1] is the optical axis, the rotational asymmetry of the effect of birefringence around the optical axis is 120 degrees. Appears periodically. Therefore, in the method of Burnett et al., Relative rotation about the optical axis by about 60 degrees is equivalent to about 60 degrees + (nXl (20 degrees) is equivalent to rotating relatively by 60 degrees, 180 degrees, or 300 degrees (where n is an integer).

In the second method proposed in the present invention, the optical axis and the crystal axis [110] (or the crystal axis [110]) of a pair of fluorite lenses (generally, a transmission member formed of fluorite) are used. And a pair of fluorite lenses are relatively rotated about the optical axis by about 90 degrees. Here, the crystal axis that is optically equivalent to the crystal axis [1 10] is the crystal axis [1-110], [10 1], [-101], [0 1 1], [01-1] It is.

FIGS. 4A to 4C are diagrams for explaining the second method proposed in the present invention, and show the distribution of the birefringence index with respect to the incident angle of a light beam. In the second method proposed in the present invention, the distribution of birefringence in one fluorite lens is as shown in FIG. 4A, and the distribution of birefringence in the other fluorite lens is in FIG. 4B. As shown. As a result, the distribution of the birefringence indices in the entire pair of fluorite lenses is as shown in FIG. 4C.

Referring to FIGS. 4A and 4B, in the second method proposed in the present invention, the region corresponding to the crystal axis [1 10] which is coincident with the optical axis corresponds to the polarization in one direction. The birefringence region has a relatively large refractive index and a relatively small refractive index for polarized light in the other direction (a direction orthogonal to one direction). The region corresponding to the crystal axes [100] and [0 10] is a region with a relatively large refractive index and no birefringence. Furthermore, the region corresponding to the crystal axes [1 1 1] and [1 1 1] is a region with a relatively small refractive index and no birefringence.

On the other hand, referring to FIG. 4C, by rotating the pair of fluorite lenses relative to each other by 90 degrees, the influence of the crystal axis [110] where the birefringence is the maximum in the pair of fluorite lenses as a whole is reduced. Nearly, there is no birefringence near the optical axis with an intermediate refractive index. That is, by using the second method proposed in the present invention, good imaging performance can be secured without being substantially affected by birefringence.In the second method proposed in the present invention, One fluorite lens and the other The relative rotation of the fluorite lens by about 90 degrees about the optical axis means that a given crystal axis oriented in a direction different from the optical axis of one fluorite lens and the other fluorite lens (eg, Means that the relative angle of the crystal axes [001], [—1 1 1], [—1 10], or [1 1 1 1]) around the optical axis is about 90 degrees . Specifically, for example, the relative angle about the optical axis between the crystal axis [001] of one fluorite lens and the crystal axis [001] of the other fluorite lens is about 90 degrees. means.

In addition, as is clear from FIGS. 4A and 4B, when the crystal axis [110] is used as the optical axis, the rotational asymmetry of the effect of the birefringence around the optical axis becomes 180 degrees. appear. Therefore, in the second method proposed in the present invention, relatively rotating about the optical axis by about 90 degrees means relatively rotating about the optical axis by about 90 degrees + (nX 180 degrees). Has the same meaning as rotating by 90 degrees and 270 degrees '·' (where n is an integer.

As described above, by aligning the optical axis of the pair of fluorite lenses with the crystal axis [1 1 1] and rotating the pair of fluorite lenses relatively by 60 degrees about the optical axis, Or by aligning the optical axis of the pair of fluorite lenses with the crystal axis [100] and relatively rotating the pair of fluorite lenses by 45 degrees about the optical axis, or the pair of fluorite lenses The effect of birefringence can be significantly reduced by aligning the optical axis of the fluorite with the crystal axis [1 10] and rotating the pair of fluorite lenses relatively by 90 degrees about the optical axis. .

Here, a rotationally symmetric distribution remaining when the optical axis of the pair of fluorite lenses and the crystal axis [1 1 1] are matched and rotated by 60 degrees, and the optical axis of the pair of fluorite lenses It is opposite to the rotationally symmetric distribution that remains when the crystal axis [100] is aligned and rotated 45 degrees relative to each other. In other words, the progression of a pair of fluorite lenses (hereinafter, referred to as “fluorite parent lens of crystal axis [11 1]) whose optical axis and crystal axis [1 11] are aligned and rotated relative to each other by 60 degrees. A pair of fluorite lenses with the phase axis aligned with the crystal axis [100] and rotated relative to each other by 45 degrees (hereinafter referred to as “fluorite pair lens with crystal axis [100]”) U) is orthogonal to the fast axis.

In other words, birefringence distribution with a fast axis in the radial direction remains in the fluorite pair lens with the crystal axis [100], and advances in the circumferential direction with the fluorite pair lens with the crystal axis [1 1 1]. A birefringent distribution with a phase axis remains. When birefringence exists in a sample, the phase of two linearly polarized lights orthogonal to the vibrating plane (polarization plane) passing through the sample changes due to the difference in the refractive index. In other words, the phase of one polarized light will lead or lag the other, but the polarization direction of the one with the leading phase is called the fast axis, and the polarization direction of the one with the late phase is called the slow axis. .

Thus, the optical axis of the pair of fluorite lenses and the crystal axis [1 1 1] are matched and the fluorite pair lens of the crystal axis [1 1 1] is rotated by 60 degrees and the light of the pair of fluorite lenses is rotated. It can be seen that the effect of the birefringence can be further reduced by combining the fluorite pair lens with the crystal axis [100] rotated by 45 degrees with the axis coincident with the crystal axis [100]. ■

Incidentally, Raikafu _{(L i C aA l F 6} ) and crystal (S i 0 ₂₎ and fluoride magnesite Shiumu (MgF ₂₎ uniaxial parallel plane plate formed of crystals such as (hereinafter, "uniaxial crystal parallel A flat plate has the property of providing a phase difference between polarization components orthogonal to each other. In other words, when light passes through the uniaxial crystal parallel plane plate, for example, an R-polarized component and an R-polarized component that oscillate in a direction including the normal (radiation direction R) in a plane whose normal is the optical axis. And a polarization component having a vibration direction orthogonal to the polarization component (a polarization component having a vibration direction in the circumferential direction 0 around the normal).

Therefore, in the present invention, the phase difference between mutually orthogonal polarization components generated due to the crystal transmission member formed of the crystalline material, for example, due to the birefringence of the fluorite lens formed of fluorite The phase difference between the generated R-polarized component and the zero-polarized component is determined by the action of a phase correction member such as a plane parallel plate formed of a uniaxial crystal (the position between the R-polarized component and the zero-polarized component). (Operation of giving a phase difference). As a result, according to the present invention, for example, in the case of a projection optical system including a plurality of fluorite lenses, the effect of birefringence can be reduced favorably by the use of the phase correction member, and the effect of birefringence is substantially reduced Receiving Good optical performance can be ensured without breaking. In addition, it is preferable that the uniaxial crystal parallel plate is formed so that its optical axis substantially coincides with the optical axis of the optical system. With this configuration, a phase difference that is rotationally symmetric with respect to the optical axis can be provided in the pupil of the optical system, and for example, the influence of the birefringence of the fluorite lens can be favorably reduced.

FIG. 5 is a diagram showing a phase map at a pupil of a projection optical system including a fluorite pair lens having a crystal axis [111]. FIG. 6 is a diagram showing a phase map at a pupil of a projection optical system including a fluorite pair lens having a crystal axis of [100]. Fig. 7 shows the crystal axis

FIG. 3 is a diagram showing a phase map at a pupil of a projection optical system including a fluorite pair lens of [1 1 1] and a fluorite pair lens of a crystal axis [100].

Referring to the pupil phase map in FIG. 5, as described above, in the case of the projection optical system including the fluorite pair lens with the crystal axis [111], the complex of the fluorite pair lens with the crystal axis [111] is assumed. It can be seen that birefringence distribution has a fast axis in the circumferential direction and a slow axis in the radial direction due to refraction. On the other hand, referring to the pupil phase map in FIG. 6, as described above, in the projection optical system including the fluorite pair lens with the crystal axis [100], the birefringence of the fluorite pair lens with the crystal axis [100] is This indicates that the birefringence distribution has a slow axis in the circumferential direction and a fast axis in the radial direction.

Therefore, referring to the pupil phase map in FIG. 7, as described above, the crystal axis

In the case of the projection optical system including the fluorite pair lens of [1 1 1] and the fluorite pair lens of the crystal axis [100], the fluorite pair lens of the crystal axis [1 1 1] and the fluorite pair of the crystal axis [100] are used. It can be seen that the effect of birefringence caused by the fluorite lens can be favorably reduced by the combination with the stone base lens. Although not shown, in the case of the projection optical system including the fluorite pair lens with the crystal axis [1 10], like the projection optical system including the fluorite pair lens with the crystal axis [1 11], Due to the birefringence of the fluorite pair lens with the crystal axis [1 10], the birefringence distribution has a fast axis in the circumferential direction and a slow axis in the radial direction. FIG. 8 is a diagram showing a phase map at a pupil of a projection optical system including a parallel plane plate formed of a positive uniaxial crystal (hereinafter, referred to as “positive uniaxial crystal parallel plane plate”). Fig. 9 shows a plane-parallel plate made of a negative uniaxial crystal (hereinafter referred to as “negative uniaxial connection”). FIG. 6 is a diagram showing a phase map at a pupil of a projection optical system including a crystal parallel plane plate. Further, FIG. 10 is a diagram showing a phase map at a pupil of a projection optical system including a fluorite pair lens having a crystal axis [111] and a negative uniaxial crystal parallel plane plate.

FIG. 11 is a diagram showing a phase map at a pupil of a projection optical system including a fluorite pair lens having a crystal axis [100] and a positive uniaxial crystal parallel plane plate. The negative uniaxial crystal, for example as crystal (S i 0 ₂₎ and Raikafu (L i C a A 1 F 6), the refractive index and No for ordinary, the refractive index for the extraordinary light and Ne When Ne ^ <No is satisfied. Conversely, a positive uniaxial crystal satisfies Ne> No, for example, magnesium fluoride (MgF ₂ ). Negative uniaxial crystal less light is transmitted with a wavelength of size less than 200 nm, Raikafu _{(L i C aA l F 6} ) is its leading candidate.

Referring to the pupil phase map in FIG. 8, the projection optical system including the positive uniaxial crystal parallel plane plate has the same structure as the projection optical system including the fluorite pair lens with the crystal axis [111]. It can be seen that a birefringent distribution having a fast axis in the circumferential direction and a slow axis in the radial direction is generated by the action of the positive uniaxial crystal parallel plane plate. On the other hand, referring to the pupil phase map in FIG. 9, in the case of a projection optical system including a negative uniaxial crystal parallel plane plate, the crystal axis

As in the case of the projection optical system including the [100] fluorite pair lens, the birefringence has a slow axis in the circumferential direction and a fast axis in the radial direction due to the action of the negative uniaxial crystal parallel plane plate. It can be seen that a folding distribution occurs.

Therefore, in the present invention, as shown in the pupil phase map of FIG. 10, by combining the fluorite pair lens with the crystal axis [111] and the negative uniaxial crystal parallel plane plate, the crystal axis [ As in the case of combining the fluorite pair lens of [111] and the fluorite pair lens of the crystal axis [100], the effect of the birefringence caused by the fluorite lens can be reduced well. In general, there have been few attempts to form a fluorite lens by aligning the optical axis with the crystal axis [100], and it is difficult to reduce internal distortion to a small extent, and the workability is not very good.

In this embodiment, it is difficult to reduce the internal strain and the workability is not so good. Without using the fluorite pair lens with the crystal axis [100], the crystal axis [1 1 1] This is very advantageous because it can achieve the same effect as the combination of a fluorite pair lens and a fluorite pair lens with a crystal axis of [100]. In particular, by aligning the optical axis with the crystal axis [1 1 1] in all fluorite lenses constituting the projection optical system and combining these fluorite lenses with a negative uniaxial crystal parallel plane plate, However, the internal distortion of the fluorite lens can be kept small, and its workability is also improved. Further, in the present invention, as shown in the pupil phase map of FIG. 11, by combining a fluorite pair lens with a crystal axis [100] and a positive uniaxial crystal parallel plane plate, the crystal axis [100] It can be seen that the effect of the birefringence caused by the fluorite lens can be reduced favorably, as in the case of combining the fluorite pair lens with the fluorite pair lens with the crystal axis [11 1]. Further, although not shown in the drawings, the present invention has a birefringence distribution similar to that of the fluorite pair lens having the crystal axis [111], and the negative uniaxial crystal parallel to the fluorite bay lens having the crystal axis [110]. By combining with a flat plate, the effect of birefringence caused by the fluorite lens can be reduced in the same way as when the fluorite pair lens with the crystal axis [1 10] and the fluorite pair lens with the crystal axis [100] are combined. Good reduction can be achieved.

An embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 12 is a diagram schematically showing a configuration of an exposure apparatus including a projection optical system according to the embodiment of the present invention. In FIG. 12, the Z axis is parallel to the optical axis AX of the projection optical system PL, the Y axis is parallel to the plane of FIG. 12 in the plane perpendicular to the optical axis AX, and the plane is perpendicular to the optical axis AX. In Fig. 12, the X axis is set perpendicular to the paper of Fig. 12. The exposure apparatus shown in FIG. 12, as a light source LS for supplying illumination light in the ultraviolet region, for example, includes a A r F excimer laser primary light source (wavelength 193 nm) or F ₂ laser primary light source (wavelength 157 nm) ing. The light emitted from the light source LS illuminates a reticle (mask) R on which a predetermined pattern is formed, via an illumination optical system IL. The optical path between the light source LS and the illumination optical system IL is sealed by casing (not shown), and the space from the light source LS to the optical member closest to the reticle side in the illumination optical system IL is exposed. It has been replaced with an inert gas such as helium gas or nitrogen, which has a low light absorption rate, or has been maintained in a nearly vacuum state. Picture 42

-18-The reticle R is held parallel to the XY plane on the reticle stage RS via a reticle holder RH. A pattern to be transferred is formed on the reticle R. For example, a rectangular pattern region having a long side along the X direction and a short side along the Y direction in the entire pattern region is illuminated. The reticle stage RS can be moved two-dimensionally along the reticle plane (that is, the XY plane) by the action of a drive system (not shown), and its position coordinates are determined by an interferometer RIF using a reticle moving mirror RM. And the position is controlled. Light from the pattern formed on the reticle R forms a reticle pattern image on the wafer W as a photosensitive substrate via the projection optical system PL. The wafer W is held in parallel with the XY plane on the wafer stage WS via a wafer table (wafer holder) WT. Then, on the wafer W, a rectangular exposure area having a long side along the X direction and a short side along the Y direction so as to optically correspond to the rectangular illumination area on the reticle R. A pattern image is formed on the substrate. The wafer stage WS can be moved two-dimensionally along the wafer surface (that is, the XY plane) by the action of a drive system (not shown), and its position coordinates are determined by an interferometer WIF using a wafer moving mirror WM. It is configured to be measured and position controlled.

In the illustrated exposure apparatus, the projection optical system PL is disposed between the optical member arranged closest to the reticle side and the optical member arranged closest to the edge side of the optical members constituting the projection optical system PL. The inside of the projection optical system PL is configured to maintain an airtight state, and the gas inside the projection optical system PL is replaced with an inert gas such as helium gas or nitrogen, or is maintained in a substantially vacuum state.

Further, a reticle R and a reticle stage RS are disposed in a narrow optical path between the illumination optical system IL and the projection optical system PL, but a casing (not shown) that hermetically surrounds the reticle R and the reticle stage RS. ) Is filled with an inert gas such as nitrogen or helium gas, or is kept almost in a vacuum state.

In the narrow optical path between the projection optical system PL and the wafer W, the wafer W and wafer stage WS are arranged. An inert gas such as nitrogen or helium gas is filled in a casing (not shown) that hermetically surrounds the throat, or is maintained in a substantially vacuum state. Thus, an atmosphere in which the exposure light is hardly absorbed is formed over the entire optical path from the light source LS to the wafer W.

As described above, the illumination area on the reticle R and the exposure area on the wafer W (that is, the effective exposure area) defined by the projection optical system PL are rectangular with short sides along the Y direction. Therefore, while controlling the position of reticle R and wafer W using a drive system and an interferometer (RIF, WIF), etc., the reticle stage along the short side direction of the rectangular exposure area and illumination area, that is, along the Y direction. By moving (scanning) the RS and the wafer stage WS and thus the reticle R and the wafer W synchronously, the wafer W has a width equal to the long side of the exposure area and the wafer W A reticle pattern is scanned and exposed in an area having a length corresponding to the scanning amount (moving amount). Alternatively, the reticle R pattern is sequentially formed on each exposure area of the wafer W by performing the batch exposure while controlling the wafer W two-dimensionally in a plane orthogonal to the optical axis AX of the projection optical system PL. Exposed.

FIG. 13 is a diagram schematically showing a configuration of a projection optical system according to Example 1 of the present embodiment. Referring to FIG. 13, the projection optical system of the first embodiment includes a refraction-type first imaging optical system G for forming a first intermediate image of a pattern of a reticle R disposed on a first surface. Has one. A first optical path bending mirror Ml is arranged near the position where the first intermediate image formed by the first imaging optical system G1 is formed. The first optical path bending mirror Ml deflects the light beam toward the first intermediate image or the light beam from the first intermediate image toward the catadioptric second imaging optical system G2.

The second imaging optical system G2 has a concave reflecting mirror CM and two negative lenses, and based on the light flux from the first intermediate image, a second intermediate image (first An image of the intermediate image (a secondary image of the pattern) is formed near the formation position of the first intermediate image. A second optical path bending mirror M2 is arranged near the position where the second intermediate image formed by the second imaging optical system G2 is formed. The second optical path bending mirror M2 deflects the light beam toward the second intermediate image or the light beam from the second intermediate image toward the refraction type third imaging optical system G3. This Here, the reflecting surface of the first optical path bending mirror M1 and the reflecting surface of the second optical path bending mirror M2 are positioned so as not to spatially overlap.

The third imaging optical system G3 converts a reduced image of the reticle R pattern (the image of the second intermediate image and the final image of the projection optical system) based on the light flux from the second intermediate image, It is formed on the wafer W arranged on the second surface. Note that the first imaging optical system G1 has an optical axis AX1 extending linearly, the third imaging optical system G3 has an optical axis AX3 extending linearly, and the optical axis AX1 And the optical axis AX3 are set so as to coincide with the reference optical axis AX which is a common single optical axis.

On the other hand, the second imaging optical system G2 also has a linearly extending optical axis AX2, and this optical axis AX2 is set to be orthogonal to the reference optical axis AX. Further, both the first optical path bending mirror Ml and the second optical path bending mirror M2 have a planar reflecting surface, and are integrally formed as one optical member (one optical path bending mirror) having two reflecting surfaces. It is configured. The line of intersection of these two reflecting surfaces (strictly, the line of intersection of the virtual extension surface) is AX 1 of the first imaging optical system G 1, AX 2 of the second imaging optical system G 2, and third imaging It is set to intersect AX 3 of optical system G 3 at one point.

As described above, the projection optical system according to the first embodiment includes one concave reflecting mirror CM, and is provided in the optical path between the first surface on which the reticle R is set and the second surface on which the wafer W is set. This is a three-time imaging type catadioptric optical system that forms a first intermediate image and a second intermediate image of the reticle R. The concave reflecting mirror CM is disposed in an optical path between the first intermediate image and the second intermediate image, and is a reciprocating beam through which light traveling toward the concave reflecting mirror CM and light reflected from the concave reflecting mirror CM pass. An optical path is formed. Further, the concave reflecting mirror CM is used at approximately the same magnification, and is arranged at or near the pupil position of the optical system.

The projection optical system of each embodiment including the first embodiment is an optical system that is almost telecentric on both the reticle R side (first surface side) and the wafer W side (second surface side). By constructing a telecentric optical system on both sides, even if there is a slight misalignment in the position of the reticle R (object position) or the position of the wafer W (image position) along the optical axis direction, An image can be formed at a magnification, and no image displacement occurs in a direction perpendicular to the optical axis. In this case, the phase correction member PC 0304142

-21- Because of the difficulty, it is desirable to have the form of a parallel plane plate.

In the first embodiment, as shown in FIG. 13, the phase correction member PC is arranged near the reticle R in the optical path between the reticle and the first imaging optical system G1. More specifically, all the fluorite lenses constituting the projection optical system are formed such that the crystal axis [111] and the optical axes (AX1 to AX3) are almost coincident. The phase correction member PC is a plane parallel plate made of a negative uniaxial crystal such as crystal (Si ₂ ) or Leicauff (LiCaA 1 F ₆ ) (ie, a negative uniaxial crystal parallel plane). The optical axis is formed so as to substantially coincide with the optical axis AX1 of the first imaging optical system G1.

As a result, in the first embodiment, as described above, the influence of the birefringence of the fluorite lens constituting the projection optical system is caused by the phase difference imparting action of the phase correcting member PC formed of the negative uniaxial crystal parallel plane plate. Can be satisfactorily reduced, and a projection optical system having good optical performance substantially without being affected by birefringence can be realized. In addition, since the phase difference is adjusted according to the incident angle in the phase correction member PC using a uniaxial crystal, the phase correction member placed near the reticle R (first surface) in the telecentric projection optical system on both sides By the action of the PC, the phase difference in the pupil can be corrected uniformly over the entire area of the visual field.

In the first embodiment, a configuration is also possible in which the optical axis of the phase correction member PC is not formed so as to substantially coincide with the optical axis of the optical system. Also, the optical axes of all the fluorite lenses need not be substantially coincident with the crystal axis [111], but may be substantially coincident with the crystal axis [100] or the crystal axis [1 10]. In this case, the phase correction member PC is formed of a negative uniaxial crystal or a positive uniaxial crystal as necessary. The relationship between the crystal axis orientation of the fluorite lens and the characteristics of the phase correction member PC is the same in each of the following examples and modifications.

FIG. 14 is a diagram schematically showing a configuration of a projection optical system according to a first modification of the first embodiment. FIG. 15 is a diagram schematically showing a configuration of a projection optical system according to a second modification of the first embodiment. FIG. 16 is a diagram schematically showing a configuration of a projection optical system according to a third modification of the first embodiment. Fig. 17 shows the first implementation TJP03 / 04142

FIG. 22 is a drawing schematically showing a configuration of a projection optical system according to a fourth modification of the example. FIG. 18 is a view schematically showing a configuration of a projection optical system according to a fifth modification of the first embodiment.

The projection optical systems according to the first to fifth modifications have a configuration similar to that of the projection optical system according to the first embodiment. This is different from the first embodiment. Specifically, in the first modified example, as shown in FIG. 14, the phase correction member PC is disposed in the optical path between the first imaging optical system G1 and the first optical path bending mirror Ml. . In other words, the phase correction member PC is arranged near the formation position of the first intermediate image, that is, near the plane optically conjugate with the reticle R. Therefore, similarly to the first embodiment, the phase difference correction in the pupil is performed over the entire field of view by the action of the phase correction member PC arranged near the optically conjugate surface with the reticle R (first surface). It can be performed evenly over the whole area.

In the second modification, as shown in FIG. 15, the phase correction member PC is arranged near the wafer W in the optical path between the third imaging optical system G3 and the wafer W. Therefore, similarly to the first embodiment, the phase difference correction in the pupil is evenly performed over the entire field of view by the action of the position correction member PC arranged near the wafer W (second surface). It can be carried out. In the third modification, as shown in FIG. 16, a phase correction member PC is provided in the optical path between the second imaging optical system G2 and the optical path bending mirrors Ml and M2, that is, to the concave reflecting mirror CM. It is arranged in the reciprocating optical path through which the light beam going and the light beam reflected from the concave reflector CM pass.

Thus, by arranging the phase correction member PC in the reciprocating optical path, the correction effect can be enhanced. In particular, since the concave reflecting mirror CM is used at approximately the same magnification and is arranged at or near the pupil position of the projection optical system, the phase difference correction in the pupil can be performed uniformly over the entire field of view. it can. In the fourth modification, as shown in FIG. 17, the phase correction member PC is arranged at or near the pupil position in the optical path of the first imaging optical system G1. In this case, the phase difference in the visual field can be adjusted by the action of the phase correction member PC arranged at or near the pupil position.

In the fifth modification, as shown in FIG. 18, the phase correction member PC It is arranged at or near the pupil position in the optical path of the system G3. In this case, the phase difference in the visual field can be adjusted by the action of the phase correction member PC arranged at or near the pupil position as in the fourth modification. In the first embodiment and its modifications, the projection optical system includes only one phase correction member PC. However, the present invention is not limited to this, and the projection optical system may include a plurality of phase correction members PC. Modifications including are also possible. This is the same in the following embodiments and related modifications.

FIG. 19 is a diagram schematically showing a configuration of a projection optical system according to Example 2 of the present embodiment. Referring to FIG. 19, the projection optical system of the second embodiment includes a catadioptric first imaging optical system G1 for forming an intermediate image of a reticle pattern. The first imaging optical system G1 has a concave reflecting mirror CM and a plurality of lenses, and forms an approximately equal-magnification intermediate image based on the light beam from the reticle R. A first optical path bending mirror M1 is arranged near a position where an intermediate image formed by the first imaging optical system G1 is formed. The first optical path bending mirror M1 deflects the light beam from the intermediate image toward the second optical path bending mirror M2. Further, the second optical path bending mirror M2 deflects the light beam from the intermediate image toward the refraction type second imaging optical system G2. The second imaging optical system G2 forms the final image of the pattern of the reticle R on the wafer W based on the light flux from the intermediate image. Note that the first imaging optical system G1 and the second imaging optical system G2 both have linearly extending optical axes AX1 and AX2, respectively, and the optical axis AX1 and the optical axis AX2 are mutually separated. They are set almost parallel.

As described above, the projection optical system of the second embodiment includes one concave reflecting mirror CM, and is provided in the optical path between the first surface on which the reticle R is set and the second surface on which the wafer W is set. This is a double-imaging type catadioptric optical system that forms an intermediate image of the reticle R at the same time. The concave reflector CM is disposed in the optical path between the reticle R and the intermediate image, and forms a reciprocating optical path through which the light beam traveling toward the concave mirror CM and the light beam reflected from the concave mirror CM pass. I have.

Further, the optical axes of all the lenses (light transmitting members) constituting the projection optical system and the optical axis of the concave reflecting mirror CM are set substantially parallel to each other. In addition, concave reflector C M is used at approximately the same magnification, and is arranged at or near the pupil position of the optical system. In the second embodiment, as shown in FIG. 19, since the phase correction member PC is arranged near the reticle R in the optical path between the reticle scale and the first imaging optical system G1, the first embodiment As in the example, the phase difference correction in the pupil can be performed uniformly over the entire area in the visual field.

FIG. 20 is a diagram schematically showing a configuration of a projection optical system according to a first modification of the second embodiment. FIG. 21 is a diagram schematically showing a configuration of a projection optical system according to a second modification of the second embodiment. The projection optical system according to the first and second modifications of the second embodiment has a configuration similar to that of the projection optical system according to the second embodiment, but the arrangement of the phase correction member PC formed of a uniaxial crystal parallel flat plate. Only the position is different from the second embodiment. Specifically, in the first modified example of the second embodiment, as shown in FIG. 20, a phase shift occurs in a reciprocating optical path through which the light beam traveling toward the concave reflector CM and the light beam reflected from the concave reflector CM pass. Since the correction member PC is arranged, the correction effect can be enhanced. In addition, since the concave reflecting mirror CM is used at approximately the same magnification and is arranged at or near the pupil position of the projection optical system, phase difference correction in the pupil is performed in the entire field of view! : Can be performed evenly. In the second modified example of the second embodiment, as shown in FIG. 21, a position complementing member PC is located near the wafer W in the optical path between the second imaging optical system G2 and the wafer W. Since they are arranged, the phase difference in the pupil can be corrected evenly over the entire field of view.

FIG. 22 is a diagram schematically showing a configuration of a projection optical system according to Example 3 of the present embodiment. Referring to FIG. 22, the projection optical system according to the third embodiment includes a catadioptric first imaging optical system G1 for forming an intermediate image of a reticle pattern. The first imaging optical system G1 has a concave reflecting mirror CM, a plurality of lenses, and a first optical path bending mirror Ml, and forms an approximately equal-magnification intermediate image based on the light beam from the reticle R. A second optical path bending mirror M2 is arranged near a position where an intermediate image formed by the first imaging optical system G1 is formed.

Further, the second optical path bending mirror M2 deflects the light beam toward the intermediate image or the light beam from the intermediate image toward the refraction type second imaging optical system G2. The second imaging optical system G 2 is P03 04142

-25-Based on the luminous flux from the intermediate image, a final image of the pattern of the reticle R is formed on the wafer W. The first imaging optical system G1 has an optical axis AX1 bent in an L-shape by a first optical path bending mirror Ml, and the second imaging optical system G2 has a linearly extending optical axis. Has AX 2. Further, the first optical path bending mirror Ml and the second optical path bending mirror M2 both have a planar reflecting surface, and are integrally formed as one optical member (one optical path bending mirror) having two reflecting surfaces. It is configured.

As described above, the projection optical system according to the third embodiment includes one concave reflecting mirror CM, and is arranged in the optical path between the first surface on which the reticle R is set and the second surface on which the wafer W is set. This is a double-imaging type catadioptric optical system that forms an intermediate image of the reticle R at the same time. The concave reflector CM is disposed in the optical path between the reticle R and the intermediate image, and forms a reciprocating optical path through which the light beam traveling toward the concave reflector CM and the light beam reflected from the concave mirror CM pass. I have.

The concave reflecting mirror CM is used at approximately the same magnification, and is arranged at or near the pupil position of the optical system. In the third embodiment, as shown in FIG. 22, the phase correction member PC is arranged near the reticle R in the optical path between the reticle R and the first imaging optical system G1. As in the embodiment and the second embodiment, the phase difference in the pupil can be corrected uniformly over the entire field of view.

FIG. 23 is a diagram schematically showing a configuration of a projection optical system according to a first modification of the third embodiment. FIG. 24 is a diagram schematically showing a configuration of a projection optical system according to a second modification of the third embodiment. The projection optical systems of the first modification and the second modification of the third embodiment have a configuration similar to that of the projection optical system of the third embodiment, but the arrangement of the phase correction member PC formed of a uniaxial crystal parallel flat plate. Only the position is different from the third embodiment. Specifically, in the first modified example of the third embodiment, as shown in FIG. 23, since the lens is arranged at or near the pupil position in the optical path of the second imaging optical system G2, The phase difference in the visual field can be adjusted by the action of the complementary member PC. In the second modification of the third embodiment, as shown in FIG. 24, the first phase correction member PC1 is disposed near the reticle R, and the second phase correction member PC2 is positioned at or near the pupil position. The phase difference correction in the pupil by the action of the first phase correction member PC 1 The phase difference can be adjusted evenly over the entire area, and the phase difference in the field of view can be adjusted by the operation of the second phase correction member PC2.

FIG. 25 is a diagram schematically showing a configuration of a projection optical system according to Example 4 of the present embodiment. Referring to FIG. 25, the projection optical system of the fourth embodiment includes a catadioptric first imaging optical system G1 for forming an intermediate image of a reticle scale pattern, and a luminous flux from the intermediate image. And a refraction-type second imaging optical system G2 for forming a final image of the pattern of the reticle R on the wafer W based on the information. The first imaging optical system G 1 has a concave reflecting mirror CM 1, a convex reflecting mirror CM 2, and a plurality of lenses, and forms an approximately 1 × intermediate image based on a light beam from the reticle R.

The first imaging optical system G1 has a linearly extending optical axis AX1, the second imaging optical system G2 has a linearly extending optical axis AX2, and the optical axis AX1 And the optical axis AX2 are set to coincide with the reference optical axis AX, which is a common single optical axis. As described above, in the fourth embodiment, since all the optical members are arranged along a single linear optical axis, it is very advantageous from the viewpoint of adjusting the optical system.

As described above, the projection optical system of the fourth embodiment includes one concave reflecting mirror CM1, and is provided in the optical path between the first surface on which the reticle R is set and the second surface on which the wafer W is set. This is a double-imaging catadioptric optical system that forms an intermediate image of the reticle R. In the fourth embodiment, as shown in FIG. 25, the phase correction member PC is disposed near the reticle R in the optical path between the reticle R and the first imaging optical system G1. Examples As in the third embodiment, the phase difference correction in the pupil can be performed uniformly over the entire field of view.

FIG. 26 is a diagram schematically showing a configuration of a projection optical system according to a first modification of the fourth embodiment. FIG. 27 is a diagram schematically showing a configuration of a projection optical system according to a second modification of the fourth embodiment. The projection optical systems of the first and second modifications of the fourth embodiment have a configuration similar to that of the projection optical system of the fourth embodiment, but the arrangement of a phase correction member PC formed of a uniaxial crystal parallel flat plate. Only the position is different from the fourth embodiment. Specifically, in the first modified example of the fourth embodiment, as shown in FIG. 26, since the lens is arranged at or near the pupil position in the optical path of the second imaging optical system G2, Complement The phase difference in the field of view can be adjusted by the action of the positive member PC. In the second modification of the fourth embodiment, as shown in FIG. 27, since the phase correction member PC is arranged near the wafer W, the phase difference correction in the pupil is performed over the entire field of view. Can be performed equally.

FIG. 28 is a diagram schematically showing a configuration of a projection optical system according to Example 5 of the present embodiment. Referring to FIG. 28, the projection optical system of the fifth embodiment is a refraction type optical system in which all optical members are lenses (light transmitting members), and all the optical members are linear single lenses. It is arranged along the optical axis AX. In the fifth embodiment, as shown in FIG. 28, since the phase correction member PC is arranged near the reticle R, the phase difference correction in the pupil is performed in the same manner as in the first to fourth embodiments. Can be performed uniformly over the entire field of view.

FIG. 29 is a diagram schematically showing a configuration of a projection optical system according to a first modification of the fifth embodiment. FIG. 30 is a diagram schematically showing a configuration of a projection optical system according to a second modification of the fifth embodiment. The projection optical systems of the first and second modifications of the fifth embodiment have a configuration similar to that of the projection optical system of the fifth embodiment, but the arrangement of the phase correction member PC formed of a uniaxial crystal parallel flat plate. Only the position is different from the fifth embodiment. Specifically, in the first modified example of the fifth embodiment, as shown in FIG. 29, since it is arranged at or near the pupil position of the optical system, the position within the visual field is obtained by the action of the phase correction member PC. The phase difference can be adjusted. On the other hand, in the second modification of the fifth embodiment, as shown in FIG. 30, since the phase correction member PC is arranged near the wafer W, the phase difference correction in the pupil is performed over the entire field of view. Can be performed evenly over

In the above-described embodiment, fluorite is used as the birefringent optical material. However, the present invention is not limited to this. For example, barium fluoride (BaF ₂ ) may be used. In this case, it is preferable that the crystal axis orientation such as barium fluoride (B a F ₂₎ are also determined in accordance with the onset bright.

In the exposure apparatus according to the above-described embodiment, the reticle (mask) is illuminated by the illumination device (illumination step), and the transfer pattern formed on the mask is exposed on the photosensitive substrate using the projection optical system (exposure step). ) By this, micro devices (semiconductor elements, Imaging devices, liquid crystal display devices, thin-film magnetic heads, etc.). Hereinafter, an example of a method for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of the present embodiment will be described with reference to the flowchart of FIG. This will be described with reference to FIG.

First, in step 301 of FIG. 31, a metal film is deposited on one lot of wafers. In the next step 302, a photoresist is applied on the metal film on the wafer of the lot. Then, in step 303, using the exposure apparatus of the present embodiment, an image of the pattern on the mask is sequentially exposed and transferred to each shot area on the one lot of wafers via the projection optical system. . Then, in step 304, after developing the photoresist on the one lot of wafers, in step 305, etching is performed on the one lot of wafers by using the resist pattern as a mask. A circuit pattern corresponding to the pattern on the mask is formed in each shot area on each wafer.

Thereafter, a device such as a semiconductor element is manufactured by forming a circuit pattern of an upper layer and the like. According to the above-described semiconductor device manufacturing method, a semiconductor device having an extremely fine circuit pattern can be obtained with high throughput. In steps 301 to 305, a metal is vapor-deposited on the wafer, a resist is applied on the metal film, and the respective steps of exposure, development, and etching are performed. Prior to forming a silicon oxide film on the wafer in advance, it is needless to say that a resist may be applied on the silicon oxide film, and each step of exposure, development, etching and the like may be performed.

Further, in the exposure apparatus of the present embodiment, a liquid crystal display element as a microdepth can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate). Hereinafter, an example of the technique at this time will be described with reference to the flowchart of FIG. In FIG. 32, in a pattern forming step 401, a so-called optical liquid crystal is used to transfer and expose a mask pattern onto a photosensitive substrate (eg, a glass substrate coated with a resist) using the exposure apparatus of the present embodiment. The process is executed. By this photolithography process, on the photosensitive substrate 4142

A predetermined pattern including a large number of electrodes and the like is formed. Thereafter, the exposed substrate is subjected to various processes such as an imaging process, an etching process, and a resist stripping process, so that a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming process 402. I do.

Next, in the color fill formation process 402, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix, or , G, B are formed as a color filter in which a plurality of sets of three stripe filters are arranged in the horizontal scanning line direction. Then, after the color filter forming step 402, a cell assembling step 403 is performed. In the cell assembling step 403, the liquid crystal is formed by using the substrate having the predetermined pattern obtained in the pattern forming step 401, the color filter obtained in the color filter forming step 402, and the like. Assemble the panel (liquid crystal cell). In the cell assembling step 403, for example, a liquid crystal is placed between the substrate having the predetermined pattern obtained in the pattern forming step 401 and the color filter obtained in the color filter forming step 402. To produce a liquid crystal panel (liquid crystal cell).

Then, in a module assembling step 404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display element, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

In the above-described embodiment, the present invention is applied to the projection optical system mounted on the exposure apparatus. However, the present invention is not limited to this, and may be applied to other general projection optical systems. Can also be applied. Further, in the embodiment described above, but using a 1 9 3 nm A r F excimer one The primary light source or 1 5 7 nm F ₂ laser primary light sources you supplying wavelength light supplying wave wavelength light of, However, the present invention is not limited to this. For example, another appropriate light source that supplies light having a wavelength of 200 nm or less can be used. Industrial applicability As described above, in the present invention, for example, a crystal transmission member such as a fluorite lens constituting a projection optical system is formed by a phase difference imparting action of a phase correction member formed of a parallel plane plate formed of a uniaxial crystal. The effect of birefringence can be reduced favorably, and a projection optical system having good optical performance substantially without being affected by birefringence can be realized.

Therefore, according to the present invention, in the exposure apparatus and the exposure method using the projection optical system of the present invention having good optical performance substantially without being affected by birefringence, high-resolution and high-precision projection exposure is performed. be able to. Further, by using an exposure apparatus equipped with the projection optical system of the present invention, a good microphone opening device can be manufactured by high-precision projection exposure through a high-resolution projection optical system.

Claims

The scope of the claims

1. A projection optical system including a crystal transmission member formed of a crystalline material and forming an image of a first surface on a second surface,

A projection optical system comprising: a light transmissive phase correction member for correcting a phase difference between mutually orthogonal polarization components generated by the crystal transmission member.

2. In the projection optical system according to claim 1,

The projection optical system, wherein the phase correction member is formed of a uniaxial crystal and has an optical axis substantially coincident with an optical axis of the optical system.

3.In the projection optical system according to claim 1 or 2,

The crystal transmission member is formed of fluorite (CaF ₂ ), and a crystal axis [111] or a crystal axis optically equivalent to the crystal axis [111] and an optical axis of the optical system are almost equal. A pair of light transmitting members formed so as to coincide with each other;

When the refractive index for ordinary light is No and the refractive index for extraordinary light is Ne, the phase correction member is formed of a negative uniaxial crystal satisfying Ne and No, and its optical axis is substantially equal to the optical axis. A projection optical system characterized by being formed so as to match.

4. In the projection optical system according to claim 1 or 2,

All of the crystal permeable members are formed of fluorite (C aF ₂ ) and have a crystal axis [1 1

13 or the crystal axis optically equivalent to the crystal axis [111] and the optical axis of the optical system are formed so as to substantially coincide with each other;

When the refractive index for ordinary light is No and the refractive index for extraordinary light is Ne, the phase correction member is formed of a negative uniaxial crystal satisfying Ne and No, and its optical axis is substantially equal to the optical axis. Projection optics characterized by being formed to coincide

5. The projection optical system according to claim 3 or 4, wherein the negative uniaxial crystal is quartz (S i 0 ₂ ) or Leicaf (L i Ca A 1 F ₆ ). A projection optical system, characterized in that:

6. In the projection optical system according to claim 1 or 2,

The crystal transmission member is formed of fluorite (CaF ₂ ), and has a crystal axis [100] or a crystal axis optically equivalent to the crystal axis [100] and an optical axis of an optical system so as to substantially coincide with each other. Having a pair of light transmitting members formed,

When the refractive index for ordinary light is No and the refractive index for extraordinary light is Ne, the phase correction member is formed of a positive uniaxial crystal satisfying Ne> No, and its optical axis is substantially equal to the optical axis. A projection optical system characterized by being formed so as to match.

7. The projection optical system according to claim 6, wherein

The projection optical system, wherein the positive uniaxial crystal is magnesium fluoride (MgF ₂ ).

8. In the projection optical system according to claim 1 or 2,

The crystal transmission member is made of fluorite (CaF ₂ ), and the crystal axis [110] or a crystal axis optically equivalent to the crystal axis [110] and the optical axis of the optical system substantially coincide with each other. Having a pair of light transmitting members formed like

When the refractive index for ordinary light is No and the refractive index for extraordinary light is Ne, the phase correction member is formed of a negative uniaxial crystal satisfying Ne <No, and its optical axis is substantially equal to the optical axis. A projection optical system characterized by being formed so as to match.

9. The projection optical system according to claim 8, wherein

The negative uniaxial crystal, quartz (S I_〇 ₂₎ or Raikafu projection optical system, characterized in that the (L i C a A 1 F 6).

10. The projection optical system according to any one of claims 1 to 9, wherein

The projection optical system, wherein the phase correction member is disposed near the first surface, near the second surface, or near a surface optically conjugate with the first surface.

11. The projection optical system according to any one of claims 1 to 10, wherein

The said phase correction member is arrange | positioned in the pupil position of an optical system, or its vicinity, The projection optical system characterized by the above-mentioned.

1. In the projection optical system according to any one of claims 1 to 11,

A projection optical system comprising a plurality of the phase correction members.

13. In the projection optical system according to any one of claims 1 to 12,

Further comprising at least one concave reflector,

The concave reflecting mirror forms a reciprocating optical path through which light rays traveling toward the concave reflecting mirror and light rays reflected from the concave reflecting mirror pass.

The projection optical system, wherein the phase correction member is disposed in the reciprocating optical path.

14. The projection optical system according to claim 13, wherein:

The concave reflecting mirror is used at approximately the same magnification, and at or near a pupil position of an optical system. A projection optical system, wherein

15. In the projection optical system according to any one of claims 1 to 14,

The projection optical system is a re-imaging optical system that forms an intermediate image of the first surface in an optical path between the first surface and the second surface,

The projection optical system, wherein the phase correction member is arranged near a position where the intermediate image is formed.

16. The projection optical system according to any one of claims 1 to 15, wherein

The projection optical system includes one concave reflecting mirror, and forms a double image catadioptric optical system that forms an intermediate image of the first surface in an optical path between the first surface and the second surface. Wherein the concave reflecting mirror is disposed in an optical path between the first surface and the intermediate image.

17. The projection optical system according to any one of claims 1 to 15, wherein

The projection optical system includes one concave reflecting mirror, and forms a double image catadioptric optical system that forms an intermediate image of the first surface in an optical path between the first surface and the second surface. Wherein the optical axes of all the light transmitting members constituting the projection optical system and the optical axes of the concave reflecting mirrors are set substantially parallel to each other.

18. In the projection optical system according to any one of claims 1 to 15,

The projection optical system includes one concave reflecting mirror, and forms a first intermediate image and a second intermediate image of the first surface in an optical path between the first surface and the second surface. It is an image type refracting optical system, The projection optical system, wherein the concave reflecting mirror is arranged in an optical path between the first intermediate image and the second intermediate image.

1 9. In the projection optical system according to any one of claims 1 to 12,

A projection optical system, wherein all optical members constituting the projection optical system are light transmitting members.

20. In the projection optical system according to any one of claims 1 to 19,

The projection optical system has a single optical axis extending linearly,

The projection optical system, wherein all optical members constituting the projection optical system are arranged so that their optical axes substantially coincide with the single optical axis.

21. In the projection optical system according to any one of claims 1 to 20,

The projection optical system is an optical system that is substantially telecentric on both the first surface side and the second surface side,

The projection optical system, wherein the phase correction member is formed of a uniaxial crystal and has an optical axis substantially coincident with an optical axis of the optical system, and has a parallel plane form.

22. In the projection optical system according to any one of claims 1 to 21,

A projection optical system, wherein an image of the first surface is formed on the second surface based on light having a wavelength of 200 nm or less.

2 3. An illumination system for illuminating the mask set on the first surface, and the mask And a projection optical system according to any one of claims 1 to 22 for forming an image of a pattern formed on a photosensitive substrate set on the second surface. An exposure apparatus, comprising:

24. A mask set on the first surface is illuminated, and a mask formed on the mask via the projection optical system according to any one of claims 1 to 22. An exposure image projected onto a photosensitive substrate set on the second surface.