JP2003161882A - Projection optical system, exposure apparatus and exposing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection optical system which is not substantially influenced by double refraction and has a fine optical property although a crystal material such as fluorite, etc., indicating inherent double refraction is used. <P>SOLUTION: The projection optical system is provided with a plurality of crystal transmission members made of the crystal material and an amorphous transmission member made of an amorphous material, and an image on a first face (R) is formed on a second face (W). A plurality of the crystal transmission members are provided with a first group of light transmission members (L22) having an optical axis approximately corresponding to a crystal axis [100] and a second group of crystal transmission members (L23) having an optical axis approximately corresponding to the crystal axis [100] and a position relationship for rotating on the optical axis at an angle of approximately 45° relative to the first group of the light transmission members. The amorphous transmission member (L19) has a predetermined double refraction distribution for correcting an influence by double refraction of a plurality of the crystal transmission members. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection optical system, an exposure apparatus and an exposure method, and is particularly suitable for an exposure apparatus used when manufacturing microdevices such as semiconductor elements and liquid crystal display elements in a photolithography process. The present invention relates to a projection optical system.

[0002]

2. Description of the Related Art When forming a fine pattern of an electronic device (microdevice) such as a semiconductor integrated circuit or a liquid crystal display, a photomask (also called a reticle) is formed by proportionally enlarging a pattern to be formed by about 4 to 5 times. There is used a method in which the pattern (1) is reduced and exposed and transferred onto a photosensitive substrate (substrate to be exposed) such as a wafer using a projection exposure apparatus. In this type of projection exposure apparatus, the exposure wavelength thereof continues to shift to the short wavelength side in order to cope with the miniaturization of semiconductor integrated circuits.

At present, the exposure wavelength is 248 nm of a KrF excimer laser, but the shorter wavelength Ar is used.
193 nm of the F excimer laser is also in the stage of practical application. Further, a projection exposure apparatus using a light source that supplies light in a wavelength band called a so-called vacuum ultraviolet region, such as an F ₂ laser having a wavelength of 157 nm, a Kr ₂ laser having a wavelength of 146 nm, and an Ar ₂ laser having a wavelength of 126 nm has been proposed. ing. Further, since high 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 having a larger numerical aperture is possible. Has been done.

As described above, with respect to the exposure light in the ultraviolet region having a short wavelength, the optical material (lens material) having good transmittance and uniformity is limited. In a projection optical system using an ArF excimer laser as a light source, synthetic quartz glass can be used as a lens material, but one type of lens material cannot satisfactorily correct chromatic aberration. Calcium crystals (fluorite) are used. On the other hand, F ₂
In a projection optical system using a laser as a light source, usable lens materials are substantially limited to calcium fluoride crystals (fluorite).

[0005]

Recently, intrinsic birefringence is present even in calcium fluoride crystal (fluorite), which is a crystal material belonging to the cubic system, with respect to ultraviolet rays having such a short wavelength. Has been reported. In an ultra-high precision optical system such as a projection optical system used for manufacturing an electronic device, the aberration caused by the birefringence of the lens material is fatal, and the lens configuration in which the influence of the birefringence is substantially avoided. And the adoption of lens design is essential.

The present invention has been made in view of the above-mentioned problems. Even if a crystalline material exhibiting an intrinsic birefringence such as fluorite is used, the present invention is excellent without being substantially affected by birefringence. An object is to provide a projection optical system having optical performance. Further, the present invention provides an exposure apparatus and an exposure method capable of performing high-resolution and high-precision projection exposure by using a projection optical system having good optical performance without being substantially affected by birefringence. The purpose is to provide.

[0007]

In order to solve the above problems, according to the first aspect of the present invention, a plurality of crystal transmitting members formed of a crystalline material belonging to a cubic system and a predetermined amorphous material are formed. In the projection optical system for forming an image of the first surface on the second surface, the plurality of crystal transparent members have a crystal axis [100] or a crystal axis [100]. And a crystal axis [100] or a crystal axis optically equivalent to the crystal axis [100], the first group of light-transmitting members formed so that the crystal axis and the optical axis that are optically equivalent to And a light axis of the second group, which is formed so as to substantially coincide with each other and has a positional relationship in which the light axis of the first group is relatively rotated by about 45 degrees with respect to the light axis of the first group. Wherein the at least one amorphous transparent member comprises the plurality of To provide a projection optical system characterized by having a predetermined birefringence distribution to compensate for the influence of the birefringence of the crystal transmission member. In this case, the predetermined birefringence distribution is preferably a birefringence distribution having a fast axis in the circumferential direction.

According to a preferred aspect of the first aspect of the present invention, the plurality of crystal transmitting members are arranged such that the crystal axis [111] or a crystal axis optically equivalent to the crystal axis [111] and an optical axis substantially coincide with each other. And the optical axis of the third group of light transmitting members formed on the crystal axis [111] or a crystal axis optically equivalent to the crystal axis [111] and the optical axis of the third group. About 60 degrees about the optical axis with respect to the light transmission member of
And a fourth group of light transmitting members having a positional relationship of being relatively rotated by a degree. In this case, the predetermined birefringence distribution is preferably a birefringence distribution having a fast axis in the circumferential direction or a birefringence distribution having a fast axis in the radial direction.

According to a second aspect of the present invention, a plurality of crystal transmitting members made of a crystalline material belonging to a cubic system and at least one amorphous transmitting member made of a predetermined amorphous material are provided. In the projection optical system that forms an image of one surface on the second surface, the plurality of crystal transmission members have crystal axes [100].
Alternatively, a fifth group of light transmitting members formed so that the crystal axis and the optical axis that are optically equivalent to the crystal axis [100] substantially coincide with each other, and [111] or the crystal axis [111] and the optical axis. A light transmitting member of the sixth group formed so that the crystal axis and the optical axis equivalent to the crystal axis [111] or the crystal axis and the optical axis optically equivalent to the crystal axis [111] And a light transmitting member of the seventh group having a positional relationship in which the light transmitting member of the sixth group is relatively rotated about the optical axis with respect to the light transmitting member of the sixth group, The projection optical system is characterized in that the at least one amorphous transmissive member has a predetermined birefringence distribution for compensating the effect of birefringence of the plurality of crystal transmissive members. In this case, the predetermined birefringence distribution is preferably a birefringence distribution having a fast axis in the radial direction.

According to a third aspect of the present invention, a plurality of crystal transmitting members made of a crystalline material belonging to a cubic system and at least one amorphous transmitting member made of a predetermined amorphous material are provided. In a projection optical system that forms an image of one surface on a second surface, the at least one amorphous transmissive member compensates for the effect of birefringence of the plurality of crystal transmissive members.
Provided is a projection optical system having a birefringence distribution which is substantially non-rotationally symmetric with respect to an optical axis.

According to a fourth aspect of the present invention, a plurality of crystal transmitting members made of a crystalline material belonging to a cubic system and at least one amorphous transmitting member made of a predetermined amorphous material are provided, and In the projection optical system that forms an image of one surface on the second surface, the at least one amorphous transmissive member has a predetermined birefringence distribution for compensating the effect of birefringence of the plurality of crystal transmissive members. , The diameter of the light flux when a light flux emitted from one point on the optical axis of the first surface is incident on each surface of the at least one amorphous transmissive member is Pn, and the effective of the at least one amorphous transmissive member is When the diameter is En,
There is provided a projection optical system characterized by satisfying the condition of Pn / En <0.7.

According to a preferred aspect of the first invention to the fourth invention, the predetermined amorphous material is quartz or quartz doped with fluorine. Further, the crystal material belonging to the cubic system is preferably calcium fluoride or barium fluoride.

In a fifth aspect of the present invention, an illumination system for illuminating the mask set on the first surface, and a photosensitive substrate set on the second surface with an image of a pattern formed on the mask. Provided is an exposure apparatus comprising the projection optical system according to any one of the first to fourth inventions for forming the above.

In a sixth aspect of the present invention, a mask on which a pattern is formed is illuminated, and an image of the illuminated pattern is formed on a photosensitive substrate via the projection optical system of the first aspect to the fourth aspect. An exposure method characterized by the above.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining the crystal axis orientation of fluorite. Referring to FIG. 1, crystal axes of fluorite are defined based on a cubic XYZ coordinate system. That is, the crystal axis [100] along the + X axis, the crystal axis [010] along the + Y axis, and the crystal axis [0] along the + Z axis.
01] are respectively defined.

Further, in the XZ plane, the crystal axis [100]
And a crystal axis [101] in a direction forming 45 degrees with the crystal axis [001] and a crystal axis [11] in a direction forming 45 degrees with the crystal axis [100] and the crystal axis [010] in the XY plane.
0] defines the crystal axis [011] in a direction forming 45 degrees with the crystal axis [010] and the crystal axis [001] in the YZ plane. In addition, + X axis, + Y axis and +
The crystal axis is [111] in a direction that forms an equal acute angle with the Z axis.
Is prescribed.

In FIG. 1, + X axis, + Y axis and +
Although only the crystallographic axes in the space defined by the Z axis are shown, the crystallographic axes are similarly defined in other spaces.
As described above, in the case of fluorite, in the crystal axis [111] direction shown by the solid line in FIG. 1 and the crystal axis [−111], [1-11], and [11-1] directions (not shown) equivalent to this, ,
Birefringence is almost zero (minimum).

Similarly, the crystal axis [10] shown by the solid line in FIG.
The birefringence is almost zero (minimum) also in the [0], [010], and [001] directions. On the other hand, crystal axes [110], [101], and [011] indicated by broken lines in FIG. 1 and crystal axes [−110], [−101], which are not shown and are equivalent thereto,
The birefringence is maximum in the [01-1] direction.

As mentioned above, a symposium on lithography (2nd In
In ternational Symposium on 157nm Lithography), it was announced by John H. Burnett of NIST in the US that the existence of intrinsic birefringence in fluorite was confirmed both experimentally and theoretically.

According to this presentation, fluorite has a crystal axis [11
0], [-110], [101], [-101], [0
11] and [01-1] in 6 directions, the wavelength is 157n.
Maximum 6.5 nm / cm, wavelength 193n for m light
It has a maximum birefringence value of 3.6 nm / cm for m light. These values of birefringence are substantially larger than the allowable value of random birefringence of 1 nm / cm, and the effect of birefringence may be accumulated through a plurality of lenses due to non-randomness. .

Burnett et al., In the above publication, disclose a technique for reducing the effects of birefringence. Figure 2 Burn
It is a figure explaining the method of ett et al., and has shown the distribution of the birefringence | refractive index with respect to the incident angle (angle of light rays and an optical axis) of a light ray. In FIG. 2, five concentric circles indicated by broken lines in the figure represent one degree of 10 degrees. Therefore, the innermost circle represents a region having an incident angle of 10 degrees with respect to the optical axis, and the outermost circle represents a region having an incident angle of 50 degrees with respect to the optical axis.

Further, black circles represent regions having a relatively large refractive index and no birefringence, and white circles represent regions having a relatively small refractive index and no birefringence. On the other hand, a thick circle and a long double arrow indicate a direction of a relatively large refractive index in a region having birefringence, and a thin circle and a short double arrow indicate a direction of a relatively small refractive index in a region having birefringence.
In the subsequent FIG. 3 as well, the above notations are the same.

In the method of Burnett et al., An optical axis and a crystal axis [111] of a pair of fluorite lenses (lenses made of fluorite).
And a pair of fluorite lenses are relatively rotated about the optical axis by 60 degrees. Therefore, the birefringence distribution in one fluorite lens is as shown in FIG. 2 (a), and the birefringence distribution in the other fluorite lens is as shown in FIG. 2 (b). As a result, the distribution of birefringence in the entire pair of fluorite lenses is as shown in FIG.

In this case, referring to FIGS. 2A and 2B, the region corresponding to the crystal axis [111] which coincides with the optical axis is a region having a relatively small refractive index and having no birefringence. Become. In addition, crystal axes [100], [010], [0
01] is a region having a relatively large refractive index and no birefringence. Furthermore, the crystal axis [110],
The regions corresponding to [101] and [011] are birefringent regions having a relatively small refractive index for polarized light in the circumferential direction and a relatively large refractive index for polarized light in the radial direction. in this way,
It can be seen that each fluorite lens is most affected by birefringence in the region of 35.26 degrees from the optical axis (angle formed by the crystal axis [111] and the crystal axis [110]).

On the other hand, referring to FIG. 2C, by rotating the pair of fluorite lenses relatively by 60 degrees,
It can be seen that the effects of the crystal axes [110], [101], and [011], which have the largest birefringence, can be reduced in the entire pair of fluorite lenses. Then, in a region of 35.26 degrees from the optical axis, a birefringent region having a smaller refractive index for the polarized light in the circumferential direction than that for the polarized light in the radial direction remains. In other words, by using the method of Burnett et al., A rotationally symmetrical distribution with respect to the optical axis remains, but the effect of birefringence can be considerably reduced.

In the method proposed in the present invention, the optical axis and the crystal axis [100] of the pair of fluorite lenses (generally, the transparent member formed of fluorite) (or the crystal axis [100] are optically equivalent to each other. The crystal axis) and the 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 crystal axes [010] and [001].

FIG. 3 is a diagram for explaining the method of the present invention, showing the distribution of birefringence with respect to the incident angle of light rays (angle formed by light rays and the optical axis). According to the method of the present invention, the birefringence distribution in one fluorite lens is as shown in FIG. 3A, and the birefringence distribution in the other fluorite lens is as shown in FIG. 3B. Become. As a result, the distribution of birefringence in the entire pair of fluorite lenses is as shown in FIG.

Referring to FIGS. 3 (a) and 3 (b), in the method of the present invention, the crystal axis [100] coincides with the optical axis.
The region corresponding to is a region having a relatively large refractive index and no birefringence. In addition, crystal axes [111], [1-1
The regions corresponding to 1], [-11-1], and [11-1] are regions having a relatively small refractive index and no birefringence. Furthermore, crystal axes [101], [10-1], [11]
The regions corresponding to [0] and [1-10] are birefringent regions having a relatively large refractive index for polarized light in the circumferential direction and a relatively small refractive index for polarized light in the radial direction. Thus, for each fluorite lens, 45 degrees from the optical axis (crystal axis [100]
It can be seen that the influence of the birefringence is maximized in the region of the angle between the and the crystal axis [101].

On the other hand, referring to FIG. 3C, by relatively rotating the pair of fluorite lenses by 45 degrees,
The crystal axes [101], [10-1], [110], and [1-10] having the maximum birefringence in the entire pair of fluorite lenses.
Is considerably diminished, and a birefringent region having a larger refractive index for polarized light in the circumferential direction than that for polarized light in the radial direction remains in the region of 45 degrees from the optical axis. In other words, by using the method of the present invention, the distribution of rotational symmetry with respect to the optical axis remains, but the influence of birefringence can be considerably reduced.

In the method of the present invention, one fluorite lens and the other fluorite lens are about 45 about the optical axis.
Rotating relative to each other by a certain degree means that predetermined crystal axes (for example, crystal axes [010], [0] and [0] that are oriented in directions different from the optical axes of the one fluorite lens and the other fluorite lens
01], [011] or [01-1]) is about 45 degrees relative to the optical axis. Specifically, for example, the relative angle between 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.
Means degrees.

Further, as is apparent from FIGS. 3A and 3B, when the optical axis is the crystal axis [100], rotational asymmetry due to the influence of birefringence about the optical axis. Is 9
Appears in a cycle of 0 degrees. Therefore, in the method of the present invention, the relative rotation of about 45 degrees about the optical axis means about 45 degrees + (n × 90) about the optical axis.
Relative rotation by 45 degrees, ie 45 degrees, 1
It has the same meaning as relatively rotating by 35 degrees, 225 degrees, 315 degrees, ... (where n is an integer).

On the other hand, in the method of Burnett et al., The relative rotation of one fluorite lens and the other fluorite lens by about 60 degrees about the optical axis means that one fluorite lens and the other fluorite lens are rotated. A predetermined crystal axis (for example, a crystal axis [-11
1], [11-1], or [1-11]) means that the relative angle with respect to the optical axis is about 60 degrees. Specifically, for example, the relative angle between the crystal axis [-111] of one fluorite lens and the crystal axis [-111] of the other fluorite lens about the optical axis is about 60 degrees. Means that.

As is clear from FIGS. 2A and 2B, when the optical axis is the crystal axis [111], rotational asymmetry due to the influence of birefringence about the optical axis is observed. Is 1
Appears in a cycle of 20 degrees. Therefore, in the method of Burnett et al., The relative rotation of about 60 degrees about the optical axis means that about 60 degrees + (n
X 120 degrees) relative rotation, ie 6
It has the same meaning as rotating relative to 0 degree, 180 degrees, or 300 degrees (where n is an integer).

As described above, the optical axis of the pair of fluorite lenses is aligned with the crystal axis [111], and the pair of fluorite lenses are relatively rotated about the optical axis by 60 degrees. , Or by making the optical axis of the pair of fluorite lenses coincide with the crystal axis [100] and relatively rotating the pair of fluorite lenses by 45 degrees about the optical axis, rotational symmetry with respect to the optical axis is obtained. Although the distribution remains, the effect of birefringence can be significantly reduced.

Here, the rotationally symmetric distribution remaining when the optical axis of the pair of fluorite lenses and the crystal axis [111] are made to rotate relative to each other by 60 degrees, and the optical axis of the pair of fluorite lenses. This is in the opposite direction to the rotationally symmetric distribution that remains when the crystal axis [100] is aligned and rotated by 45 degrees relative to each other. In other words, a pair of fluorite lenses (hereinafter referred to as “crystal axis [1
[11] pair lens ") and a pair of fluorite lenses in which the crystal axis [100] is matched and rotated by 45 degrees relative to each other (hereinafter referred to as" crystal axis [100] pair lens "). It is orthogonal to the fast axis at.

In other words, a pair of fluorite lenses having a crystal axis [100] and an optical axis of the pair of fluorite lenses that are rotated relative to each other by 45 degrees are advanced in the radial direction. The birefringence distribution with the axis remains, and the pair of fluorite lenses has the optical axis and the crystal axis [111] aligned with each other and rotated by 60 degrees. A certain birefringence distribution remains. When the sample has birefringence, the phase of light of two linearly polarized lights orthogonal to the vibration plane (polarization plane) passing through the sample changes due to the difference in refractive index. That is, the phase of one polarization is advanced or delayed with respect to one polarization, but the polarization direction of the phase advance is called the fast axis, and the polarization direction of the phase delay is called the slow axis. .

By the way, in the case of an amorphous lens (generally an amorphous transmissive member) formed of an amorphous material such as quartz or quartz doped with fluorine (hereinafter referred to as "modified quartz"), Birefringence does not occur in the ideal state. However, with quartz or modified quartz,
Birefringence due to internal stress appears when impurities are mixed in or when temperature distribution occurs when cooling quartz formed at high temperature.

Therefore, it is possible to generate a desired birefringence distribution in quartz or modified quartz by adjusting the amount and type of impurities mixed in the ingot or the thermal history. In other words, the desired birefringence distribution rotationally symmetric with respect to the optical axis or the desired birefringence distribution non-rotationally symmetric with respect to the optical axis is adjusted to the amorphous lens by adjusting at least one of the density distribution due to impurities and thermal history during manufacturing. Can be given to.

Examples of impurities include OH, Cl, metal impurities, and dissolved gas.
In the case of thod), it is considered that OH contained in several hundred ppm or more and then Cl contained in several tens ppm are dominant from the mixed amount. When the impurities are mixed in the ingot, the coefficient of thermal expansion of the material changes. Therefore, for example, when cooling after annealing, the amount of shrinkage of the part in which the impurities are mixed becomes large, and the internal stress due to the difference in the shrinkage becomes large. Occurs,
Stress birefringence occurs. The thermal history exists regardless of the manufacturing method such as the direct method, the VAD (vapor axial deposition) method, the sol-gel method, and the plasma burner method.

The projection optical system of the present invention includes a plurality of crystal transmitting members (such as fluorite lenses) formed of a crystal material belonging to a cubic system such as fluorite and quartz or modified quartz. At least one amorphous transparent member (quartz lens, modified quartz lens, etc.) formed of an amorphous material is provided, and an image of the first surface is formed on the second surface. That is, when applied to an exposure apparatus, the projection optical system of the present invention forms a pattern image of a mask (reticle) set on the first surface on a photosensitive substrate (wafer or the like) set on the second surface. .

In the first aspect of the invention, the plurality of crystal transmitting members are provided with a pair of lenses having the crystal axis [100] (the light transmitting members of the first group and the light transmitting members of the second group). Further, the amorphous transmissive member has a predetermined birefringence distribution for compensating the influence of birefringence of the plurality of crystal transmissive members. As mentioned above,
Introducing a pair lens with a crystal axis [100] can significantly reduce the effect of birefringence, but leaves a birefringence distribution having a fast axis in the radial direction. Therefore, in the projection optical system, when the birefringence distribution having the fast axis in the radial direction remains due to the action of the pair lens having the crystal axis [100], the birefringence distribution having the fast axis in the circumferential direction is not generated. By providing the crystal transparent member, good optical performance can be secured without being substantially affected by birefringence.

In the first invention, when a pair of lenses having the crystal axis [111] (light transmitting members of the third group and light transmitting member of the fourth group) are added to the plurality of crystal transmitting members, the crystal axes [1] are added.
By combining the pair lens of [00] and the pair lens of crystal axis [111], the remaining rotationally symmetric distribution can be suppressed small.

In this case, in the projection optical system, when the action of the pair lens of the crystal axis [100] is dominant and the birefringence distribution having the fast axis in the radial direction remains, the birefringence distribution in the circumferential direction is caused. By imparting a birefringence distribution having a fast axis to the amorphous transparent member, good optical performance can be ensured without being substantially affected by birefringence. On the contrary, the action of the pair lens of the crystal axis [111] is dominant,
When the birefringence distribution having the fast axis in the circumferential direction remains, the birefringence distribution having the fast axis in the radial direction is given to the amorphous transmissive member to substantially affect the birefringence. It is possible to secure good optical performance.

In the second invention, the plurality of crystal transmitting members are formed such that the crystal axis [100] (or the crystal axis optically equivalent to the crystal axis [100]) and the optical axis are substantially coincident with each other. A crystal axis [100] lens (a light transmitting member of the fifth group),
And a pair of lenses having a crystal axis [111] (a light transmitting member of the sixth group and a light transmitting member of the seventh group). Further, the amorphous transmissive member has a predetermined birefringence distribution for compensating the influence of birefringence of the plurality of crystal transmissive members.

As described above, the introduction of the pair lens having the crystal axis [111] can considerably reduce the influence of birefringence, but the birefringence distribution having the fast axis in the circumferential direction remains. On the other hand, when a crystal axis [100] lens (not a pair lens) is introduced, as shown in FIGS. 3 (a) and 3 (b), a compound having a four-fold rotational symmetry and having a fast axis in the radial direction as a whole is used. Refraction distribution remains. As a result, in the projection optical system of the second invention, the action of the pair lens having the crystal axis [111] becomes dominant, and the birefringence distribution having the fast axis in the circumferential direction remains.

Therefore, in the projection optical system of the second invention,
By providing the amorphous transmissive member with a birefringence distribution having a fast axis in the radial direction, good optical performance can be ensured without being substantially affected by birefringence. In addition,
By the action of the crystal axis [100] lens, 4
Although the θ component is generated, in the lithography, unlike the odd θ component, the even θ component does not substantially affect the resist image.

As will be specifically shown in the embodiments described later, the influence of birefringence of the plurality of crystal transmitting members on the image plane (second surface) is not necessarily rotationally symmetrical with respect to the optical axis (see FIG. 9 ( See a) to (c)). In other words,
The aberration due to the birefringence of the plurality of crystal transmitting members may have an in-plane distribution depending on the image height. In the third aspect of the present invention, the birefringence distribution that is substantially non-rotationally symmetric with respect to the optical axis is imparted to the amorphous transmissive member, so that the effect of the birefringence of the plurality of crystal transmissive members is compensated and the effect of the birefringence is substantially reduced. Good optical performance can be secured without being affected by the above.

In the fourth aspect of the invention, the amorphous transmissive member provided with the predetermined birefringence distribution satisfies the following conditional expression (1) on both the incident surface and the exit surface thereof. Pn / En <0.7 (1)

Here, En is the effective diameter of the amorphous transmissive member (that is, in the case of an exposure apparatus, a circle circumscribing the light beam emitted from the entire exposure area when incident on each surface of the amorphous transmissive member). Diameter). Further, Pn is the diameter of the light flux (hereinafter, referred to as “partial diameter”) when the light flux emitted from one point on the optical axis of the object surface (first surface) enters each surface of the amorphous transmissive member. .

In order to correct the in-image distribution of aberrations due to birefringence of a plurality of crystal transmission members, an amorphous transmission member provided with a predetermined birefringence distribution should be separated from the pupil plane of the projection optical system. That is, it is necessary that the amorphous transmissive member is arranged near the object plane or the image plane (second plane). Fourth
According to the invention, by satisfying the conditional expression (1) on both the entrance surface and the exit surface, the amorphous transmissive member provided with a predetermined birefringence distribution is arranged near the object plane or the image plane. The effect of birefringence of the plurality of crystal transmission members can be compensated for, and good optical performance can be secured without being substantially affected by birefringence.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 4 is a diagram schematically showing the configuration of an exposure apparatus equipped with the projection optical system according to the embodiment of the present invention. Note that in FIG. 4, the Z axis is parallel to the optical axis AX of the projection optical system PL, the Y axis is parallel to the paper surface of FIG. 4 in the plane perpendicular to the optical axis AX, and the Y axis is in the plane perpendicular to the optical axis AX. The X axis is set perpendicularly to the paper surface of FIG.

The exposure apparatus shown in FIG. 4 is equipped with, for example, an ArF excimer laser light source (wavelength 193 nm) as a light source LS for supplying illumination light in the ultraviolet region. The light emitted from the light source LS passes through the illumination optical system IL,
A reticle (mask) R on which a predetermined pattern is formed is illuminated. The optical path between the light source LS and the illumination optical system IL is sealed by a casing (not shown), and the space from the light source LS to the most reticle-side optical member in the illumination optical system IL absorbs exposure light. It is replaced with an inert gas such as helium gas or nitrogen, which has a low rate, or is maintained in a substantially vacuum state.

The reticle R is held parallel to the XY plane on the reticle stage RS via the reticle holder RH. A pattern to be transferred is formed on the reticle R, and for example, a rectangular pattern area having a long side along the X direction and a short side along the Y direction is illuminated in the entire pattern area. The reticle stage RS can be two-dimensionally moved along the reticle surface (that is, the XY plane) by the action of a drive system (not shown), and its position coordinates are measured by an interferometer RIF using a reticle moving mirror RM. And position controlled.

Light from the pattern formed on the reticle R forms a reticle pattern image on the wafer W, which is a photosensitive substrate, via the projection optical system PL. The wafer W is held parallel to the XY plane on the wafer stage WS via a wafer table (wafer holder) WT. Then, on the wafer W, a rectangular exposure region 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 region on the reticle R. A pattern image is formed on. Wafer stage WS
Can be two-dimensionally moved along the wafer surface (that is, the XY plane) by the action of a drive system (not shown), and its position coordinates are measured by an interferometer WIF using a wafer moving mirror WM and position control is performed. It is configured to be.

In the illustrated exposure apparatus, the projection optical system P
The projection optical system PL is configured so that the inside of the projection optical system PL is kept airtight between the optical member arranged closest to the reticle and the optical member arranged closest to the wafer among the optical members constituting L. The gas inside PL is replaced with an inert gas such as helium gas or nitrogen, or is maintained in a substantially vacuum state.

Further, the illumination optical system IL and the projection optical system PL
A reticle R, a reticle stage RS, and the like are arranged in a narrow optical path between and, and an inert gas such as nitrogen or helium gas is provided inside a casing (not shown) that hermetically surrounds the reticle R, the reticle stage RS, and the like. It is filled with gas or is held in a substantially vacuum state.

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

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 shapes having short sides along the Y direction. . Therefore, while controlling the positions of the reticle R and the wafer W using a drive system and interferometers (RIF, WIF), etc., the reticle stage RS and the reticle stage RS are formed along the short side direction of the rectangular exposure region and the illumination region, that is, the Y direction. By moving (scanning) the wafer stage WS, and thus the reticle R and the wafer W, in synchronization with each other, the wafer W has a width equal to the long side of the exposure area and a scanning amount (moving amount) of the wafer W. ), The reticle pattern is scan-exposed to a region having a length corresponding to (4). Alternatively, the pattern of the reticle R is sequentially exposed in each exposure region of the wafer W by performing batch exposure while controlling the two-dimensional drive of the wafer W in a plane orthogonal to the optical axis AX of the projection optical system PL. It

The projection optical system PL of this embodiment will be described below based on specific numerical examples. In the present embodiment, the transmissive member (refractive optical member: lens component) forming the projection optical system PL is formed of fluorite (CaF ₂ crystal) or quartz. The wavelength of ArF excimer laser light is 1
93 nm, the refractive index of fluorite for this exposure light is 1.5014548, and the refractive index of quartz is 1.560.
3261.

The height of the aspherical surface in the direction perpendicular to the optical axis is y, and the distance along the optical axis from the tangent plane at the apex of the aspherical surface to the position on the aspherical surface at the height y (sag amount). )
Is z, the vertex radius of curvature is r, the conic coefficient is κ,
When the n-th order aspherical coefficient is C _n , the following mathematical expression (a)
It is represented by. In Table (1) described later, the lens surface formed in an aspherical shape is marked with * on the right side of the surface number.

[0061]

[Formula 1] z = (y ² / r) / [1+ {1- (1 + κ) · y ² / r ² } ^1/2 ] + C ₄ · y ⁴ + C ₆ · y ⁶ + C ₈ · y ⁸ + C ₁₀ · _{^{y 10 + C 12 · y 12}} + C 14 · y 14 (a)

FIG. 5 is a view showing the lens arrangement of the projection optical system according to this embodiment. The projection optical system P of this embodiment
As shown in FIG. 5, L is a plano-concave lens L1 having an aspherical concave surface facing the wafer side, a plano-concave lens L2 having a flat surface facing the wafer side, and a flat surface facing the reticle side in order from the reticle side. Plano-convex lens L3, positive meniscus lens L4 having an aspherical concave surface facing the reticle, and biconvex lens L5
A biconvex lens L6, a positive meniscus lens L7 having a convex surface facing the reticle side, a plano-convex lens L8 having a flat surface facing the wafer side, and a plano-concave lens L9 having a flat surface facing the reticle side.
A biconcave lens L10, a planoconcave lens L11 having a flat surface on the wafer side, a biconcave lens L12 having an aspherical concave surface on the wafer side, a biconvex lens L13, and an aspherical concave surface on the wafer side. Biconcave lens L14, biconvex lens L15, positive meniscus lens L16 having a convex surface facing the reticle side, negative meniscus lens L17 having a convex surface facing the reticle side, biconvex lens L18, and biconvex lens L19.
And a positive meniscus lens L2 with the convex surface facing the reticle side
0, a positive meniscus lens L21 having an aspherical concave surface facing the wafer side, a positive meniscus lens L22 having a convex surface facing the reticle side, and a plano-convex lens L23 having a flat surface facing the wafer side.

Lenses L1 to L constituting the projection optical system PL
Of L23, L3, L8, L13, L15, L22 and L23 are fluorite lenses formed of fluorite, and lenses L1, L2, L4 to L7, L9 to L12, L14 and L1.
Reference numerals 6 to L21 are quartz lenses made of quartz. The quartz lens L19 constitutes an amorphous transmissive member to which a predetermined birefringence distribution should be given.

The following table (1) lists the values of specifications of the projection optical system according to this embodiment. In the main specifications of Table (1), λ is the wavelength of the exposure light, β is the projection magnification, NA is the image side (wafer side) numerical aperture, and Y is the image height (image field radius). . In the specifications of the optical members in Table (1), the surface number is the order of the surfaces from the reticle side, r is the radius of curvature of each surface (vertex curvature radius: mm in the case of an aspherical surface), and d is each. On-axis spacing of surfaces, that is, surface spacing (m
m), n is the refractive index with respect to the exposure light, En is the effective diameter (mm) of each surface, Pn is the partial diameter of each surface (that is, the light flux emitted from one point on the optical axis of the object surface is on each surface). The diameter of the light beam when it enters the lens is: mm), and Pn / En represents the ratio of the partial diameter to the effective diameter.

[0065]

[Table 1] (Main specifications) λ = 193 nm β = −0.25 NA = 0.85 Y = 12.1 mm (Specifications of optical member) Surface number r d n En Pn Pn / En (Reticle surface) 51.239 1 ∞ 25.713 1.5603261 119.1 22.3 0.19 (L1) 2 * 212.184 35.411 128.4 29.5 0.23 3 -103.137 37.006 1.5603261 131.2 46.3 0.35 (L2) 4 ∞ 1.500 192.4 66.1 0.34 5 ∞ 47.000 1.5014548 195.4 67.3 0.34 (L3) 6 -183.264 1.000 210.2 88.9 0.42 7 * -1577.700 39.307 1.5603261 236.3 91.9 0.39 (L4) 8 -337.812 1.000 249.6 104.7 0.42 9 562.286 40.593 1.5603261 272.6 107.6 0.39 (L5) 10 -730.269 9.069 274.2 113.7 0.41 11 351.942 42.024 1.5603261 275.4 116.5 0.42 (L6) 12 -2955.500 272.4 116.2 0.43 13 364.373 39.329 1.5603261 258.2 116.0 0.45 (L7) 14 2256.734 1.000 246.9 111.1 0.45 15 193.967 48.000 1.5014548 218.5 109.6 0.50 (L8) 16 ∞ 2.000 203.4 96.7 0.48 17 ∞ 40.000 1.5603261 199.5 95.8 0.48 (L9) 18 149.595 33.2 61 141.6 81.7 0.58 19 -234.916 14.000 1.5603261 136.5 77.7 0.57 (L10) 20 123.373 41.540 123.9 78.1 0.63 21 -298.867 43.000 1.5603261 126.7 91.4 0.72 (L11) 22 ∞ 22.620 139.3 109.2 0.78 23 -141.424 23.205 1.5603261 140.9 115.5 0.82 (L12) 24 * 2999.500 3.103 169.9 141.7 0.83 25 2240.569 41.586 1.5014548 173.0 145.5 0.84 (L13) 26 -172.475 1.000 182.8 161.2 0.88 27 -1401.661 41.000 1.5603261 194.0 172.7 0.89 (L14) 28 * 414.116 14.198 215.9 198.5 0.92 29 935.988 50.000 0.94 548159.1 205.8 ) 30 -232.953 1.000 228.4 218.5 0.96 31 254.204 40.000 1.5603261 260.6 256.0 0.98 (L16) 32 330.964 47.394 256.2 253.4 0.99 33 655.780 30.000 1.5603261 266.1 266.1 1.00 (L17) 34 287.989 12.313 270.2 269.6 27 1.00 35 393.731 50.000 1.5603261 273.2 273.2 36 -655.215 22.490 276.0 274.5 0.99 37 2633.133 50.000 1.5603261 284.0 278.0 0.98 (L19) 38 -339.998 3.810 285.3 278.2 0.98 39 185.000 46.380 1.5603261 250.8 237.9 0.95 (L20) 40 483.174 1.000 240.0 223.5 0.93 41 148.000 52.000 1.5603261 208.7 194.9 0.93 (L21) 42 * 196.741 5.000 171.3 153.8 0.90 43 136.419 47.655 1.5014548 153.4 137.8 0.90 (L22) 44 332.239 6.251 107.8 87.9 0.82 45 1.5734.387 35. 100.7 76.7 0.76 (L23) 46 ∞ 9.000 53.2 29.0 0.55 (wafer surface) (aspherical surface data) 2 surfaces κ = 1.00000 C ₄ = −1.33721 × 10 ⁻⁷ C ₆ = 4.57102 × 10 ⁻¹² C ₈ = −2.57741 × 10 ⁻¹⁶ C ₁₀ = 3.59697 × 10 ⁻²⁰ C ₁₂ = −5.61700 × 10 ⁻²⁴ C ₁₄ = 4.42067 × 10 ⁻²⁸ 7-plane κ = 1.0000 C ₄ = -4.11840 × 10 ⁻⁹ C ₆ = −2.19082 × 10 ⁻¹⁴ C ₈ = 5.55237 × 10 ⁻²¹ C ₁₀ = 2.26811 × 10 ⁻²³ C ₁₂ = −1.71805 × 10 ^{− 27} C ₁₄ = 2.95229 × 0 ^-32 24 surface _{κ = 1.000000 C 4 = 3.17136 ×} 10 -8 C 6 = -1.19732 × 10 -12 C 8 = -7.05241 × 10 -17 C 10 = 3.49842 × 10 ^-21 C ₁₂ = 4.62643 × 10 ^-26 C ₁₄ = -2.78134 × 10 ^-30 28 faces κ = 1.00000 C ₄ = 3.16556 × 10 ^-8 C ₆ = −2.55344 × 10 ^{− 13} C ₈ = −1.69524 × 10 ⁻¹⁸ C ₁₀ = 6.45379 × 10 ⁻²³ C ₁₂ = 1.11281 × 10 ⁻²⁶ C ₁₄ = −5.333626 × 10 ⁻³¹ 42 plane κ = 1.0000000 C ₄ = −2.49318 × 10 ⁻⁸ C ₆ = 1.14042 × 10 ⁻¹³ C ₈ = 4.68142 × 10 ⁻¹⁸ C ₁₀ = −8.53537 × 10 ⁻²² C ₁₂ = −3.165562 × 10 ⁻²⁶ C ₁₄ = 9.41438 × 10 ⁻³¹

Prior to a more detailed description of the present embodiment, first to third comparative examples will be described below. The following Table (2) shows the setting state of the crystal axis of each fluorite lens in the first comparative example. In Table (2), A indicates each fluorite lens, B indicates a crystal axis that coincides with the optical axis of each fluorite lens, and C indicates an angular position of a specific crystal axis other than the crystal axis B.

When the crystal axis B is the crystal axis [111], the angular position C is an angle with respect to the reference orientation of the crystal axis [-111], and the crystal axis B is the crystal axis [10].
0] is an angle with respect to the reference orientation of the crystal axis [010], for example. Here, the reference azimuth is, for example, an azimuth arbitrarily set so as to pass through the optical axis AX on the reticle surface.

Therefore, for example, (B, C) = (10
0,0) means that in a fluorite lens where the optical axis and the crystal axis [100] coincide with each other, the crystal axis [010] is arranged along the reference direction. Also, (B, C)
= (100,45) means that in the fluorite lens where the optical axis and the crystal axis [100] coincide, the crystal axis [010] is arranged at 45 degrees with respect to the reference direction. To do. That is, the fluorite lens of (B, C) = (100,0) and the fluorite lens of (B, C) = (100,45) form a lens pair of crystal axis [100]. become.

Further, for example, (B, C) = (111,
0) means that in the fluorite lens where the optical axis and the crystal axis [111] coincide with each other, the crystal axis [−111] is arranged along the reference direction. Also, (B, C) =
(111,60) means that in the fluorite lens where the optical axis and the crystal axis [111] coincide, the crystal axis [−111] is arranged so as to form 60 degrees with respect to the reference direction. To do. That is, the fluorite lens of (B, C) = (111,0) and the fluorite lens of (B, C) = (111,60) form a lens pair of the crystal axis [111]. become.

In the above description of the angular position C,
The setting of the reference azimuth does not have to be common to all the lenses, and may be common to each lens pair, for example. Further, the specific crystal axis that is the target of the angle measurement with respect to the reference orientation is not limited to the crystal axis [010] in the case of the lens pair of the crystal axis [100], and the crystal axis [11
In the case of the lens pair of [1], it is not limited to the crystal axis [-111], and can be set appropriately in units of each lens pair, for example. The notation in Table (2) is the same in the following Tables (3) to (5).

[0071]

[Table 2]

Referring to Table (2), in the first comparative example,
All fluorite lenses L3, L8, L13, L15, L2
2 and L23, the crystal axis [111] is set to coincide with the optical axis, and the crystal axis [111] is set to have the same rotational positional relationship with each other about the optical axis. However, the quartz lens L19 is not provided with birefringence distribution.

FIG. 6 is a diagram showing a point image intensity distribution (PSF: point spread function) in the first comparative example.
In FIG. 6, (a) shows the intensity distribution in the point image formed at the center of the projection visual field (the position of the optical axis AX), and (b) shows one end of the periphery of the projection visual field (lower side of the plane of FIG. 5). Intensity distribution in the point image formed, (c) shows the intensity distribution in the point image formed at the other end (upper side of the paper surface of FIG. 5) around the projection visual field.

In each point image intensity distribution, the light intensity in ideal image formation is 100%, 1% to 9% is 1% pitch, and 10% to 90% is 10% pitch. The light intensity distribution is represented by contour lines. Therefore, the outermost contour line corresponds to a light intensity of 1% of the light intensity in ideal imaging, and the innermost contour line corresponds to a light intensity of 90% of the light intensity in ideal imaging. The notation in FIG. 6 is the same in subsequent FIGS. 7 to 9.

In the first comparative example, the maximum light intensity in the point image formed at the center of the projection visual field is 95.18%, and the maximum light intensity in the point image formed at one end on the periphery of the projection visual field is 95.18%. 19%, and the maximum light intensity in the point image formed at the other end around the projection visual field is 95.61%.
That is, in the first comparative example, the crystal axis [111] is set so as to coincide with the optical axis in all the fluorite lenses, and therefore, the imaging performance of the projection optical system deteriorates due to the influence of the birefringence. You can see that

Further, referring to FIG. 6, since the crystal axis [111] is set so as to coincide with the optical axis in all the fluorite lenses, as shown in FIGS. The birefringence distribution with rotational symmetry tends to remain, and the light intensity distribution of the point image is generally triangular from the center of the projection field to the periphery. As a result, when exposure is performed through the projection optical system of the first comparative example, the line widths of the patterns are substantially different along the two directions orthogonal to each other on the photosensitive substrate (wafer), and a good line is obtained. The width uniformity cannot be ensured.

The following table (3) shows the setting state of the crystal axis of each fluorite lens in the second comparative example. Further, FIG. 7 is a diagram showing a point image intensity distribution in the second comparative example.

[0078]

[Table 3]

Referring to Table (3), in the second comparative example,
In all the fluorite lenses, the crystal axis [111] is set to coincide with the optical axis, and the fluorite lenses L3, L8, L13 are set.
And L22 and the fluorite lenses L15 and L23 are set to have a relative positional relationship of being rotated by 60 degrees about the optical axis. That is, the fluorite lens L
3, L8, L13 and L22 and the fluorite lenses L15 and L23 form a lens pair of crystal axis [111]. However, similar to the first comparative example, the quartz lens L19 is not provided with birefringence distribution.

In the second comparative example, the maximum light intensity in the point image formed at the center of the projection visual field is 96.24%, and the maximum light intensity in the point image formed at one end on the periphery of the projection visual field is 96.24%. 81%, and the maximum light intensity in the point image formed at the other end around the projection visual field is 96.82%.
That is, in the second comparative example, the effect of the birefringence is reduced by the action of the lens pair of the crystal axis [111], and the imaging performance of the projection optical system is improved as compared with the first comparative example. Recognize.

Further, referring to FIG. 7, the crystal axis [11
By the action of the lens pair of [1], the tendency of birefringence distribution with three-fold rotational symmetry is reduced, and the light intensity distribution of the point image from the center of the projection field to the periphery is generally higher than that of the first comparative example. It is close to a circle. As a result, in the second comparative example, the first
It can be seen that the line width uniformity of the projection optical system is improved as compared with the comparative example.

The following Table (4) shows the setting state of the crystal axis of each fluorite lens in the third comparative example. FIG. 8 is a diagram showing a point image intensity distribution in the third comparative example.

[0083]

[Table 4]

Referring to Table (4), in the third comparative example,
In the fluorite lenses L3, L8, L13 and L15, the crystal axis [111] is set to coincide with the optical axis, and the fluorite lenses L3, L8 and L15 and the fluorite lens L13 are only 60 degrees about the optical axis. It is set so as to have a relatively rotated positional relationship. That is, the fluorite lenses L3, L8, and L15 and the fluorite lens L13 form a lens pair of the crystal axis [111].

Further, in the fluorite lenses L22 and L23, the crystal axis [100] is set to coincide with the optical axis, and the fluorite lenses L22 and L23 are centered on the optical axis.
It is set to have a positional relationship in which it is relatively rotated by 5 degrees. That is, the fluorite lens L22 and the fluorite lens L23 form a lens pair of the crystal axis [100]. However, similarly to the first comparative example and the second comparative example, the birefringence distribution is not given to the quartz lens L19.

In the third comparative example, the maximum light intensity in the point image formed at the center of the projection visual field is 97.92%, and the maximum light intensity in the point image formed at one end around the projection visual field is 97.92%. 29%, and the maximum light intensity in the point image formed at the other end around the projection visual field is 97.31%.
That is, in the third comparative example, the effect of birefringence is further reduced by the combined action of the lens pair of the crystal axis [111] and the lens pair of the crystal axis [100], and the projection optical It can be seen that the imaging performance of the system is improved.

Further, referring to FIG. 8, the crystal axis [11
Due to the combined action of the lens pair of [1] and the lens pair of the crystal axis [100], the tendency of the birefringence distribution with three-fold rotational symmetry disappears substantially, and the light intensity of the point image extends from the center of the projection field to the periphery. The distribution is closer to a circular shape as a whole as compared with the second comparative example. As a result, it can be seen that in the third comparative example, the line width uniformity of the projection optical system is improved as compared with the second comparative example.

The following table (5) shows the setting state of the crystal axis of each fluorite lens in this embodiment. Further, FIG. 9 is a diagram showing a point image intensity distribution in the present embodiment.

[0089]

[Table 5]

Referring to Table (5), in the present embodiment,
Similar to the third comparative example, fluorite lenses L3, L8 and L1
5 and the fluorite lens L13 form a lens pair having a crystal axis [111], and the fluorite lens L22 and a fluorite lens L23 form a lens pair having a crystal axis [100]. However, unlike the first to third comparative examples, the quartz lens L19 has a predetermined birefringence distribution.

Specifically, the exposure light (193 nm) has a peripheral birefringence amount (distortion amount) of -3.8 nm / cm, a central birefringence amount of 0 nm / cm, and a central birefringence amount. The quartz lens L19 is provided with a birefringence distribution that changes in accordance with a quadratic function distribution from to the periphery, that is, a birefringence distribution that is rotationally symmetric with respect to the optical axis and has a fast axis in the circumferential direction. This is because the action of the pair lens having the crystal axis [100] is dominant in the third comparative example, and the birefringence distribution having the fast axis in the radial direction remains, so that the quartz lens L19 advances in the circumferential direction. This is because the biaxial refraction distribution having the phase axes cancels each other out.

In this embodiment, the maximum light intensity in the point image formed at the center of the projection visual field is 99.78%, and the maximum light intensity in the point image formed at one end of the periphery of the projection visual field is 99.57. %, And the maximum light intensity in the point image formed at the other end around the projection visual field is 99.55%.
That is, in the present embodiment, the effect of birefringence is very good due to the combined action of the lens pair of the crystal axis [111] and the lens pair of the crystal axis [100] and the compensation action by the birefringence distribution of the quartz lens L19. It can be seen that the image forming performance of the projection optical system is significantly improved as compared with the third comparative example.

Further, referring to FIG. 9, the crystal axis [11
1) and the lens pair of crystal axis [100] and the compensating effect of the birefringence distribution of the quartz lens L19, the light intensity distribution of the point image is entirely distributed from the center to the periphery of the projection field. It is almost circular.
As a result, it can be seen that the line width uniformity of the projection optical system is significantly improved in the present embodiment as compared with the third comparative example.

In this embodiment, a Si compound gas (a carrier gas such as O ₂ or H ₂ is used to send out the Si compound gas) which is a raw material of quartz, and a combustion gas (O ₂ ) for heating. Gas and H ₂ gas) flow out from the burner, and quartz is synthesized using the flame hydrolysis method of depositing quartz in the flame to obtain an ingot. Then, the ingot is cut out to obtain a disk material, and the disk material is annealed (or gradually cooled).

Then, in the present embodiment, the synthesis conditions during the synthesis of quartz and the thermal history during annealing are set so that the birefringence distribution of the refraction member made of quartz (that is, the quartz lens L19) has a desired birefringence distribution. Adjusting the conditions and. At this time, the parameters of the synthesis conditions include the burner structure, gas flow rate, exhaust flow rate, target swing pattern, and the like. In addition, such synthesis conditions and annealing conditions are
It may be obtained by trial and error, or may be determined using an empirical rule. For details of the method of giving a desired birefringence distribution to the quartz lens L19, for example, Japanese Patent Application No. 2001
Reference can be made to the specification and drawings.

In the present embodiment (and each comparative example) described above, the value of the intrinsic birefringence of fluorite is 7
Lithography Symposium held on 18th January (International-SEMATECH Calcium Fluoride Birefri
ngence Workshop) at NIST (National In
Institute of Standards and Technology) John H. Bur
The value published by nett et al. is used.

In the above embodiment, the birefringent light is used.
Fluorite is used as an academic material, but it is not limited to this.
However, other uniaxial crystals such as barium fluoride (B
aF ₂), Lithium fluoride (LiF), sodium fluoride
(NaF), strontium fluoride (SrF₂)Such
Can also be used. In this case, barium fluoride (B
aF₂) Etc., the crystal axis orientation is also determined according to the present invention.
It is preferable.

In the exposure apparatus of 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 ( By the exposure process, the microdevice (semiconductor element, image pickup element, liquid crystal display element,
Thin film magnetic heads, etc.) can be manufactured. 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 referred to the flowchart of FIG. Explain.

First, in step 301 of FIG.
A metal film is deposited on one lot of wafers. In the next step 302, photoresist is applied on the metal film on the wafer of the 1 lot. Then step 30
3, the image of the pattern on the mask is sequentially exposed and transferred to each shot area on the wafer of the one lot through the projection optical system using the exposure apparatus of the present embodiment.
Then, in step 304, the photoresist on the wafer of the one lot is developed, and then in step 3
At 05, the resist pattern is used as a mask on the wafers of one lot to perform etching, whereby a circuit pattern corresponding to the pattern on the mask is formed in each shot region on each wafer.

Then, a device such as a semiconductor element is manufactured by forming a circuit pattern on an upper layer. According to the above semiconductor device manufacturing method,
It is possible to obtain a semiconductor device having an extremely fine circuit pattern with high throughput. Note that step 30
In steps 1 to 305, a metal is vapor-deposited on the wafer, a resist is applied on the metal film, and each step of exposure, development, and etching is performed. Prior to these steps, a silicon film is formed on the wafer. Needless to say, after the oxide film is formed, a resist may be applied on the silicon oxide film, and each step such as exposure, development and etching may be performed.

Further, in the exposure apparatus of this embodiment, a predetermined pattern (circuit pattern,
It is also possible to obtain a liquid crystal display element as a microdevice by forming an electrode pattern or the like). Hereinafter, an example of the technique at this time will be described with reference to the flowchart in FIG. In FIG. 11, in a pattern forming step 401, a so-called photolithography step is performed in which the exposure apparatus of the present embodiment is used to transfer and expose a mask pattern onto a photosensitive substrate (such as a glass substrate coated with a resist). By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. After that, the exposed substrate undergoes a developing process, an etching process, a reticle peeling process, and the like to form a predetermined pattern on the substrate, and the process proceeds to the next color filter forming process 402.

Next, in the color filter forming step 402, 3 corresponding to R (Red), G (Green) and B (Blue)
Many sets of one dot are arranged in a matrix,
Alternatively, a color filter in which a set of filters of three stripes of R, G, and B is arranged in the horizontal scanning line direction is formed. Then, the color filter forming step 4
After 02, the cell assembling step 403 is executed. In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like. In the cell assembly step 403, for example, the pattern formation step 4
A liquid crystal panel (liquid crystal cell) is manufactured by injecting liquid crystal between the substrate having the predetermined pattern obtained in 01 and the color filter obtained in the color filter forming step 402.

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

In the above embodiment, the present invention is applied to the projection optical system mounted on the exposure apparatus,
The present invention is not limited to this, and the present invention can be applied to other general projection optical systems. Further, in the above-described embodiment, the ArF excimer laser light source that supplies the light having the wavelength of 193 nm is used, but the present invention is not limited to this. For example, the F ₂ laser light source that supplies the light having the wavelength of 157 nm or the wavelength of 248 nm is used. It is also possible to use a KrF excimer laser light source that supplies light. In addition,
F that supplies light having a wavelength of 157 nm, for example, as exposure light
_{2 When} using vacuum ultraviolet light such as a laser light source, use modified quartz (eg, fluorine-doped quartz) that is transparent to vacuum ultraviolet light as the amorphous material that forms the amorphous transparent member. It is preferable.

[0105]

As described above, in the present invention, even if an optical material having an intrinsic birefringence such as fluorite is used, it has good optical performance without being substantially affected by birefringence. A projection optical system can be realized. Therefore, in the present invention, the exposure apparatus and the exposure method using the projection optical system of the present invention, which have good optical performance without being substantially affected by birefringence, perform high-resolution and high-precision projection exposure. be able to. Further, by using the exposure apparatus equipped with the projection optical system of the present invention, it is possible to manufacture a good microdevice by high-precision projection exposure through a high-resolution projection optical system.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a crystal axis orientation of fluorite.

FIG. 2 is a diagram for explaining the method of Burnett et al., Showing a distribution of birefringence with respect to an incident angle of a light ray.

FIG. 3 is a diagram for explaining the method of the present invention, showing the distribution of birefringence with respect to the incident angle of light rays.

FIG. 4 is a diagram schematically showing a configuration of an exposure apparatus including a projection optical system according to an embodiment of the present invention.

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

FIG. 6 is a diagram showing a point image intensity distribution in a first comparative example.

FIG. 7 is a diagram showing a point image intensity distribution in a second comparative example.

FIG. 8 is a diagram showing a point image intensity distribution in a third comparative example.

FIG. 9 is a diagram showing a point image intensity distribution in the present embodiment.

FIG. 10 is a flowchart of a method for obtaining a semiconductor device as a micro device.

FIG. 11 is a flowchart of a method for obtaining a liquid crystal display element as a micro device.

[Explanation of symbols]

LS light source IL illumination optical system R reticle RS reticle stage PL projection optical system W wafer WS wafer stage L1 to L23 lens components

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshihiko Ozawa             Marunouchi 3 2-3 No. 3 shares, Chiyoda-ku, Tokyo             Ceremony Company Nikon F-term (reference) 2H087 KA21 LA01 NA00 NA02 NA04                       NA09 PA15 PA17 PB20 QA01                       QA05 QA18 QA22 QA25 QA33                       QA41 QA45 RA05 RA12 RA13                       UA03 UA04                 2H097 CA13 GB01 LA10                 5F046 BA04 CB12 CB25

Claims (12)

[Claims] 1. A plurality of crystal transmitting members made of a crystalline material belonging to a cubic system, and at least one amorphous transmitting member made of a predetermined amorphous material, wherein an image of a first surface is In the projection optical system formed on two surfaces, the plurality of crystal transmitting members are formed such that a crystal axis [100] or a crystal axis optically equivalent to the crystal axis [100] and an optical axis substantially coincide with each other. The first group of light transmitting members is formed so that the optical axis and the crystal axis [100] or a crystal axis optically equivalent to the crystal axis [100] and the optical axis of the first group substantially coincide with each other. A second group of light transmissive members having a positional relationship in which they are rotated relative to each other about the optical axis by about 45 degrees, and the at least one amorphous transmissive member is one of the plurality of crystal transmissive members. Predetermined birefringence distribution to compensate for the effect of birefringence A projection optical system, characterized by. 2. The projection optical system according to claim 1, wherein the predetermined birefringence distribution is a birefringence distribution having a fast axis in the circumferential direction. 3. The plurality of crystal transmitting members have crystal axes [1
[11] or the crystal axis [111] or the crystal axis [111] or the crystal axis [111] or the crystal axis [111]
[1] is formed so that the crystal axis and the optical axis are optically equivalent to each other and is rotated relative to the light transmitting member of the third group by about 60 degrees about the optical axis. The projection optical system according to claim 1, further comprising a fourth group of light transmitting members having. 4. The projection according to claim 3, wherein the predetermined birefringence distribution is a birefringence distribution having a fast axis in the circumferential direction or a birefringence distribution having a fast axis in the radial direction. Optical system. 5. A plurality of crystal transmitting members made of a crystalline material belonging to a cubic system and at least one non-crystalline transmitting member made of a predetermined non-crystalline material are provided, and an image of the first surface is In the projection optical system formed on two surfaces, the plurality of crystal transmitting members are formed such that a crystal axis [100] or a crystal axis optically equivalent to the crystal axis [100] and an optical axis substantially coincide with each other. And a light transmitting member of the fifth group,
[111] or a light transmissive member of the sixth group formed so that the crystal axis optically equivalent to the crystal axis [111] and the optical axis substantially coincide with the crystal axis [111] or the crystal axis [111]. 1
11] is optically equivalent to the crystal axis and the optical axis are substantially coincident with each other, and the positional relationship is such that the optical axis is rotated by about 60 degrees relative to the light transmitting member of the sixth group. And a light transmission member of the seventh group having, wherein the at least one amorphous transmission member has a predetermined birefringence distribution for compensating for an influence of birefringence of the plurality of crystal transmission members. Projection optical system. 6. The projection optical system according to claim 5, wherein the predetermined birefringence distribution is a birefringence distribution having a fast axis in the radial direction. 7. A plurality of crystal transmitting members made of a crystalline material belonging to a cubic system and at least one non-crystalline transmitting member made of a predetermined non-crystalline material are provided, and an image of the first surface is In the projection optical system formed on two surfaces, the at least one non-crystalline transmission member has a birefringence distribution substantially non-rotationally symmetric with respect to an optical axis in order to compensate for an influence of birefringence of the plurality of crystal transmission members. A projection optical system having: 8. A plurality of crystal transmitting members made of a crystalline material belonging to a cubic system and at least one amorphous transmitting member made of a predetermined non-crystalline material are provided, and an image of the first surface is In the projection optical system formed on two surfaces, the at least one amorphous transmission member has a predetermined birefringence distribution for compensating the influence of birefringence of the plurality of crystal transmission members, When the diameter of the light flux when a light flux emitted from one point on the optical axis is incident on each surface of the at least one amorphous transmissive member is Pn, and the effective diameter of the at least one amorphous transmissive member is En. , Pn / En <0.7, a projection optical system. 9. The projection optical system according to claim 1, wherein the predetermined amorphous material is quartz or quartz doped with fluorine. 10. The projection optical system according to claim 1, wherein the crystal material belonging to the cubic system is calcium fluoride or barium fluoride. 11. An illumination system for illuminating a mask set on the first surface, and an image of a pattern formed on the mask on a photosensitive substrate set on the second surface. Claims 1 to 1
An exposure apparatus comprising: the projection optical system according to any one of 0. 12. The mask set on the first surface is illuminated, and an image of a pattern formed on the mask is projected through the projection optical system according to claim 1. An exposure method characterized by performing projection exposure onto a photosensitive substrate set on a surface.