JP2000106346A - Projection aligning device and method, and method for forming semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a high resolution and a large focus depth even if using a standard reticle by a method wherein, in an illuminating lights distributed outside of a center part within an illumination optical system, there is provided a movable optical member in a radiant direction centering an optical axis of the illumination optical system on a Fourier transform plane. SOLUTION: An emission side focal plane is disposed within a Fourier transform plane for a mask in a light path of an illumination optical system, and also at each center of a plurality of positions shifted from an optical axis AX of the illumination optical system, a plurality of first fly eye lenses 41a, 41b are disposed. An emission side focal plane is disposed within the Fourier transform plane for each incident end of the first fly eye lenses 41a, 41b, and also a plurality of second fly eye lenses 40a, 40b are provided in response to each of the first fly eye lenses 41a, 41b. In addition, there are provided beam splitters 20, 21 in which illumination beams from a light source are split and made incident on each of the second fly eye lenses 40a, 40b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for projecting and exposing a pattern used for forming a pattern of a semiconductor integrated circuit or a liquid crystal device.

[0002]

2. Description of the Related Art For forming a circuit pattern of a semiconductor element or the like,
In general, a process called a photolithographic technique is required. In this step, a method of transferring a reticle (mask) pattern onto a substrate such as a semiconductor wafer is usually adopted.
A photosensitive photoresist is applied on the substrate, and a circuit pattern is transferred to the photoresist according to an irradiation light image, that is, a pattern shape of a transparent portion of the reticle pattern. In a projection exposure apparatus (for example, a stepper), an image of a circuit pattern to be transferred, which is drawn on a reticle, is projected and formed on a substrate (wafer) via a projection optical system.

[0003] In an illumination optical system for illuminating the reticle, an optical integrator such as a fly-eye lens or fiber is used, so that the intensity distribution of illumination light applied to the reticle is made uniform. If a fly-eye lens is used to optimize the uniformity,
The focal plane on the reticle side (exit plane side) and the reticle plane (pattern plane) are almost connected by a Fourier transform, and the focal plane on the reticle side and the focal plane on the light source side (incident side) are also in a Fourier transform relation. Tied. Therefore, the pattern surface of the reticle and the focal plane on the light source side of the fly-eye lens (more precisely, the focal plane on the light source side of each lens of the fly-eye lens)
Are connected in an imaging relationship (conjugate relationship). For this reason, on the reticle, the illumination light from each optical element (secondary light source image) of the fly-eye lens is added (superimposed) by passing through a condenser lens or the like, and is averaged, thereby averaging the illuminance on the reticle. It is possible to make the property good.

In a conventional projection exposure apparatus, the light amount distribution of an illumination light beam incident on an optical integrator incidence surface such as a fly-eye lens described above is substantially circular (or rectangular) around the optical axis of the illumination optical system. It was almost uniform. FIG. 19 shows a schematic configuration of a conventional projection exposure apparatus (stepper) as described above. The illumination light beam L140 is a fly-eye lens 41c, a spatial filter (aperture stop) 5a, and a condenser lens 8 in the illumination optical system. Irradiate the pattern 10 of the reticle 9 through the. Here, the spatial filter 5a is arranged on the reticle-side focal plane 414c of the fly-eye lens 41c, that is, the Fourier transform plane 17 (hereinafter abbreviated as a pupil plane) for the reticle pattern 10, or in the vicinity thereof. It has an opening in a substantially circular area centered on the optical axis AX, and limits a secondary light source (surface light source) image formed in the pupil plane to a circular shape. The illumination light that has passed through the pattern 10 of the reticle 9 is imaged on the resist layer of the wafer 13 via the projection optical system 11. At this time, the illumination optical system (41c, 5c)
The ratio between the numerical aperture of a, 8) and the reticle-side numerical aperture of the projection optical system 11, that is, the so-called σ value, is determined by the aperture stop (for example, the aperture diameter of the spatial filter 5a).
About 0.6 is common.

The illumination light L140 is diffracted by the pattern 10 patterned on the reticle 9, and from the pattern 10, the 0th-order diffracted light Do, the + 1st-order diffracted light Dp, and -1
Next-order diffracted light Dm is generated. Each diffracted light (Do, D
m, Dp) are condensed by the projection optical system 11 and generate interference fringes on the wafer (substrate) 13. This interference fringe is an image of the pattern 10. At this time, the angle θ (reticle side) between the zero-order diffracted light Do and the ± first-order diffracted lights Dp and Dm is sin θ =
It is determined by λ / P (λ: exposure wavelength, P: pattern pitch).

By the way, when the pattern pitch becomes finer,
When sinθ becomes larger and sinθ becomes larger than the reticle-side numerical aperture (NA _R ) of the projection optical system 11, the ± first-order diffracted lights Dp and Dm become pupils (Fourier transform surfaces) 1 in the projection optical system 11.
The effective diameter is limited by 2 and cannot pass through the projection optical system 11. At this time, only the zero-order diffracted light Do reaches the wafer 13 and no interference fringes occur. That is, sinθ> NA
_{In the} case of _R , an image of the pattern 10 cannot be obtained, and the pattern 10 cannot be transferred onto the wafer 13.

From the above, in the conventional projection exposure apparatus, the pitch P at which sin θ = λ / P ≒ NA _R is given by the following equation. P ≒ λ / NA _R (1) From this, since the minimum pattern size is half the pitch P, the minimum pattern size is about 0.5 · λ / NA _R. A certain depth of focus is required due to the curvature of the wafer, the effect of the step on the wafer due to the process, or the thickness of the photoresist itself. Therefore, the practical minimum resolution pattern size is expressed as k · λ / NA _R. Where k
Is called a process coefficient, which is about 0.6 to 0.8.
Since the ratio between the reticle-side numerical aperture NA _R and the wafer-side numerical aperture NA _W is the same as the imaging magnification of the projection optical system, the minimum resolution pattern size on the reticle is k · λ / NA _R ,
The minimum pattern size on the wafer is k · λ / NA _W = k
· Λ / B · NA _R (where, B is the imaging magnification (reduction ratio)) becomes.

Therefore, in order to transfer a finer pattern, it was necessary to select whether to use an exposure light source having a shorter wavelength or a projection optical system having a larger numerical aperture. Of course, efforts can be made to optimize both the exposure wavelength and the numerical aperture. However, in the conventional projection exposure apparatus as described above, it is difficult at present at present to shorten the wavelength of the illumination light source (for example, 200 nm or less) because there is no suitable optical material usable as a transmission optical member. It is. Also, the numerical aperture of the projection optical system is already close to the theoretical limit at present, and it is almost impossible to increase the numerical aperture further. Furthermore, even if the aperture can be made larger than the current state, it should be noted that ± λ / 2NA ²
Decreases sharply with an increase in the numerical aperture, and the problem that the depth of focus required for actual use is further reduced becomes significant.

A so-called phase shift reticle, which shifts the phase of the light transmitted from a specific portion of the reticle circuit pattern by π from the phase of the light transmitted from another portion, is disclosed in, for example, Japanese Patent Publication No. Sho. It is proposed in, for example, JP-A-62-50811. Use of this phase shift reticle enables transfer of a finer pattern than in the past.

However, the phase shift reticle has many problems because the manufacturing process is complicated and the cost is high, and the inspection and repair methods have not been established yet. Therefore, as a projection exposure technique that does not use a phase shift reticle, an attempt has been made to improve the transfer resolution by improving the reticle illumination method. One of the illumination methods is to reach the reticle 9 by, for example, making the spatial filter 5a in FIG. 19 an annular aperture and cutting the illumination light flux distributed around the optical axis of the illumination optical system on the Fourier transform surface 17. This is to make the illumination light beam have a certain inclination.

[0011]

However, if a special illumination method is adopted such that the illumination light beam distribution in the Fourier transform plane of the illumination optical system is formed into an annular shape, the resolving power can be certainly improved even with a normal reticle. However, there has been a problem that it is difficult to guarantee a uniform illuminance distribution over the entire surface of the reticle. Further, in a system in which a member for simply cutting the illumination light beam such as a spatial filter as shown in FIG. 19 is provided, the illumination intensity (illuminance) on the reticle or the wafer is naturally significantly reduced. As a result, there is a problem that the exposure processing time is increased due to a decrease in illumination efficiency. Furthermore, since the luminous flux from the light source passes through the Fourier transform surface in the illumination optical system in a concentrated manner, the temperature rise due to light absorption of a light shielding member such as a spatial filter becomes remarkable, and the performance due to the thermal fluctuation of the illumination optical system. It is also necessary to consider measures for deterioration (air cooling, etc.).

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a projection exposure apparatus which can obtain a high resolution, a large depth of focus, and has excellent illuminance uniformity even when a normal reticle is used. With the goal.

[0013]

According to the present invention, a Fourier transform plane (1) for a mask in an optical path of an illumination optical system is used.
7) Or, a plurality of first fly-eye lenses in which the emission-side focal plane is arranged in a plane in the vicinity thereof and whose centers are respectively arranged at a plurality of positions decentered from the optical axis (AX) of the illumination optical system ( 41a, 41b), a Fourier transform plane for each of the incident ends of the plurality of first fly-eye lenses (41a, 41b), or an exit-side focal plane in the vicinity thereof, and a first fly-eye lens (41a, 41b). 41a, 4
1b) A plurality of second fly-eye lenses (40a, 40b) provided corresponding to each of the plurality of second fly-eye lenses (40a, 40b), and the illumination light flux from the light source is divided and incident on each of the plurality of second fly-eye lenses (40a, 40b). Light splitters (20, 21) were provided. The guide optical element is provided so that the light emitted from one of the plurality of second fly-eye lenses is incident on a corresponding one of the plurality of first fly-eye lenses.

[0014]

The operation of the present invention will be described with reference to FIG.
In FIG. 18, the second fly-eye lens groups 40a and 40b corresponding to the second fly-eye lens of the present invention are arranged in a plane perpendicular to the optical axis AX. 42b, the first of the present invention
First fly-eye lens group 4 corresponding to a fly-eye lens
1a and 42b. The illuminance distribution on the first fly-eye lens incident surface is made uniform by the second fly-eye lens group.

The light beam emitted from the first fly-eye lens group is applied to a reticle 9 by a condenser lens 8. The illuminance distribution on the reticle 9 is made uniform by the first and second fly-eye lens groups, and has extremely good uniformity. Here, the centers of the first fly-eye lens groups 41a and 41b are both located at positions apart from the optical axis AX. The first fly-eye lens group 4
Reticle-side focal planes 414a, 414b of 1a, 41b
Is substantially coincident with the Fourier transform surface 17 of the reticle pattern 10, so that the distance between the optical axis AX and the center of the first fly-eye lens is determined by the angle of incidence of the light beam emitted from the first fly-eye lens on the reticle 9. Is equivalent to

The circuit pattern 10 drawn on a reticle (mask) generally contains many periodic patterns. Therefore, from the reticle pattern 10 irradiated with the illumination light from one fly-eye lens group 41a, the 0th-order diffracted light component Do, the ± 1st-order diffracted light components Dp and Dm, and the higher-order diffracted light components are converted to the pattern fineness. Occurs in the direction corresponding to

At this time, since the illumination light beam (principal ray) is incident on the reticle 9 at an inclined angle, the generated diffracted light components of each order also have an inclination (angle shift) as compared with the case where the illumination is performed vertically. Generated from pattern 10. FIG.
The illumination light L130 in 8 enters the reticle 9 at an angle of ψ with respect to the optical axis. The illumination light L130 is diffracted by the reticle pattern 10, and is converted into a 0th-order diffracted light Do that travels in a direction inclined by 傾 with respect to the optical axis AX, a + 1st-order diffracted light Dp inclined by θp with respect to the 0th-order diffracted light, and a 0th-order diffracted light Do For θ
A -1st-order diffracted light Dm that advances by m is generated. However, since the illumination light L130 is incident on the reticle pattern at an angle に 対 し て with respect to the optical axis AX of the projection optical system 11 which is telecentric on both sides, the zero-order diffracted light Do is also at an angle に 対 し て with respect to the optical axis AX of the projection optical system. Proceed only in the inclined direction.

Accordingly, the + 1st-order light Dp travels in the direction of θp + ψ with respect to the optical axis AX, and the -1st-order diffracted light Dm travels in the direction of θm-ψ with respect to the optical axis AX. At this time, the diffraction angle θ
p and θm are respectively sin (θp + ψ) −sinψ = λ / P (2) sin (θm−ψ) + sinψ = λ / P (3)

Here, it is assumed that both the + 1st-order diffracted light Dp and the -1st-order diffracted light Dm are transmitted through the pupil 12 of the projection optical system 11. When the diffraction angle increases with miniaturization of the reticle pattern 10, firstly, the + 1st-order diffracted light Dp traveling in the direction of the angle θp + ψ cannot pass through the pupil 12 of the projection optical system 11. That is, the relationship becomes sin (θp + ψ)> NA _R. However, since the illumination light L130 is incident obliquely with respect to the optical axis AX, the -1st-order diffracted light Dm can be transmitted through the projection optical system 11 even at this diffraction angle. Ie
sin (θm−ψ) <NA _R

Therefore, the zero-order diffracted light Do
And interference fringes due to two light beams of the -1st-order diffracted light Dm. This interference fringe is an image of the reticle pattern 10. When the reticle pattern 10 has a line and space ratio of 1: 1, the image of the reticle pattern 10 is formed on a resist applied on the wafer 13 with a contrast of about 90%. Patterning becomes possible.

The resolution limit at this time is when sin (θm−ψ) = NA _R (4). Therefore, NA _R + sinψ = λ / PP = λ / (NA _R + sinψ) (5) This is the pitch of the smallest transferable pattern on the reticle side.

As an example, if sinψ is determined to be about 0.5 × NA _R , the minimum pitch of the pattern on the reticle that can be transferred is P = λ (NA _R + 0.5NA _R ) = 2λ / 3NA _R ( 6)

On the other hand, as shown in FIG. 19, in the case of a conventional exposure apparatus in which the distribution of the illumination light on the pupil 17 is within a circular area centered on the optical axis AX of the projection optical system 11, the resolution limit Was P ≒ λ / NA _R as shown in the equation (1). Therefore, it can be seen that a higher resolution than the conventional exposure apparatus can be realized. Next, the reticle pattern is irradiated with exposure light in a specific incident direction and an incident angle, and a depth of focus is formed by a method of forming an imaging pattern on a wafer using the 0th-order diffracted light component and the 1st-order diffracted light component. The reason for the increase will be described.

As shown in FIG. 18, the projection optical system 1
If the focal position coincides with one of the focal positions (the best imaging plane), each diffracted light that exits one point in the reticle pattern 10 and reaches one point on the wafer 13 passes through any part of the projection optical system 11. Have the same optical path length. For this reason, even when the 0th-order diffracted light component penetrates substantially the center (near the optical axis) of the pupil plane 12 of the projection optical system 11 as in the conventional case, the
The optical path lengths of the next-order diffracted light component and the other diffracted light components are equal, and the mutual wavelength aberration is also zero. However, when the wafer 13 is in a defocused state in which the focal position of the projection optical system 11 is not coincident, the optical path length of the high-order diffracted light obliquely incident is in front of the 0th-order diffracted light passing near the optical axis. The distance becomes shorter at a position away from the projection optical system 11) and becomes longer at a position behind the focal point (a direction approaching the projection optical system 11), and the difference depends on the difference in the incident angle. Therefore, each of the 0th-order, 1st-order,... Diffracted light forms a wavefront aberration, and blurs before and after the focal position.

The wavefront aberration due to the above-mentioned defocusing is represented by ΔF, the deviation from the focal position of the wafer 13, and the sine of the incident angle θ _W when each diffracted light is incident on one point on the wafer.
When (r = sinθ _W), it is an amount given by ΔFr ^2/2. At this time, r represents the distance of each diffracted light from the optical axis AX on the pupil plane 12. In the conventional projection exposure apparatus shown in FIG. 18, since the 0th-order diffracted light Do passes near the optical axis AX, r (0th-order) = 0, while the ± 1st-order diffracted lights Dp and Dm.
Is r (first order) = M · λ / P (M is the magnification of the projection optical system). Therefore, the 0th-order diffracted light Do and ± 1st-order diffracted lights Dp and Dm
Wavefront aberration due to defocus and is a ^{ΔF · M 2 (λ / P} ) 2/2.

On the other hand, in the projection exposure apparatus of the present invention,
As shown in FIG. 18, the 0th-order diffracted light component Do is generated in a direction inclined by an angle か ら from the optical axis AX. Therefore, the distance of the 0th-order diffracted light component from the optical axis AX on the pupil plane 19 is r (0th) = M
・ It is sinψ. On the other hand, the distance of the -1st-order diffracted light component Dm from the optical axis on the pupil plane is r (-1st) = M · sin (θm−ψ). At this time, if sinψ = sin (θm-ψ), the relative wavefront aberration due to defocusing of the 0th-order diffracted light component Do and the -1st-order diffracted light component Dm becomes zero, and the wafer 13
Is slightly deviated in the optical axis direction from the focal position, the image blur of the pattern 10 does not occur as much as in the related art. That is,
The depth of focus will increase. Further, since sin (θm−ψ) + sinψ = λ / P as shown in the equation (3), the incident angle の of the illumination light beam L130 on the reticle 9 becomes sin 、 = λ / With a 2P relationship, it is possible to greatly increase the depth of focus.

Further, according to the present invention, in order to divide the illumination light beam emitted from the light source into a plurality of light beams and guide them to each fly-eye lens, the light beam from the light source is utilized with only a slight loss in light quantity. The above-described projection exposure method with high resolution and large depth of focus can be realized.

[0028]

FIG. 1 shows an embodiment of the present invention, in which two polyhedral prisms are used as a light splitting optical system.
An illumination light beam emitted from a light source 1 such as a mercury lamp is focused by an elliptical mirror 2, converted into a substantially parallel light beam by a bending mirror 3 and an input lens 4, and incident on light splitting optical systems 20 and 21. Here, the light splitter has a first shape having a V-shaped concave portion.
And a second polyhedral prism 21 having a V-shaped convex portion. Due to the refraction of these two prisms, the illumination light beam is split into two light beams. Each light beam is separated into a separate second fly-eye lens 40.
a and 40b.

Here, the second fly-eye lenses 40a, 4a
Although 0b is two, this quantity may be arbitrary. In addition, the light dividing optical system is divided into two parts in accordance with the number of the second fly-eye lens groups. However, the light dividing optical system may be divided into any number according to the number of the second fly-eye lens groups. For example, the second
If the fly-eye lens group consists of four, the light splitting optical system 2
The first and second polygons 0 and 21 may each be constituted by a first polyhedral prism 20 having a quadrangular pyramid (pyramid) concave portion and a second polyhedral prism 21 having a quadrangular pyramid (pyramid) convex portion.

The illumination light emitted from the second fly-eye lens groups 40a and 40b is applied to guide optical systems 42a and 43, respectively.
a, 42b, 43b, the first fly-eye lens group 4
1a and 41b. At this time, only the light beam from the second fly-eye lens 40a enters the first fly-eye lens 41a, and only the light beam from the second fly-eye lens 40b enters the first fly-eye lens 41b.

The light beams emitted from the first fly-eye lenses 41a and 41b are guided to the condenser lenses 6, 8 and the bending mirror 7, and illuminate the pattern 10 formed on the lower surface of the reticle 9. The light transmitted and diffracted through the pattern 10 is condensed and imaged by the projection optical system 11 to form an image of the pattern 10 on the wafer 13. In the drawing, reference numeral 12 denotes a Fourier transform plane (hereinafter referred to as a projection optical system pupil plane) for the pattern 10 in the projection optical system 11, and a variable aperture (NA aperture) is provided on the projection optical system pupil plane. In some cases.

On the other hand, the illumination optical system also has an illumination optical system pupil plane 17 corresponding to the Fourier transform plane for the pattern 10, but the first fly-eye lenses 41a and 41 described above.
The reticle-side focal plane (emission-side focal plane) b is located at a position substantially coincident with the illumination optical system pupil plane 17. The exit surfaces of the second fly-eye lenses 40a and 40b are connected to the first fly-eye lenses 41a and 41a by guide optical systems 42 and 43, respectively.
1b is a Fourier transform surface with respect to the incident surface. However, it is not necessary to strictly maintain the Fourier transform relationship. In short, it is necessary that the light flux emitted from each element of the second fly-eye lens group is superimposed on the incident surface of the first fly-eye lens group. It is only necessary that the relationship be maintained.

Here, the configuration of each fly-eye lens will be described with reference to FIG. Each of FIGS. 10A to 10D is an enlarged view of one element of the fly-eye lens. An actual fly-eye lens, for example, 40a in FIG.
40b, 41a, 41b, etc. are an aggregate of these elements. Each element is arranged (collected) in the vertical direction in FIG. 10 and in the direction perpendicular to the paper surface to form one fly-eye lens.

FIG. 10A shows a case where the incident surface 401a and the light source side focal plane 403a coincide with each other, and the exit plane 402a and the reticle side focal plane 404b coincide with each other. In the embodiment of FIG. 1 and other embodiments, a fly-eye lens of the type shown in FIG. 10A is used unless otherwise specified. The parallel light flux 410a incident from the light source (the left side in the figure) has a reticle-side focal plane 404a as shown by a solid line.
On the other hand, a light beam (broken line) emitted from one point on the light source side focal plane 403a becomes a parallel light beam after emission. FIG.
The types shown in 0 (B) to (D) will be described later.

The second fly-eye lens group 40a in FIG.
The light source side focal planes of the first fly-eye lens group 40a and the first fly-eye lens groups 41a and 41b (here, coincide with the incident planes) have an image-forming relationship as described above. Therefore, the light beam incident on each element entrance surface in the second fly-eye lens group 40a, for example, is image-formed and projected on all the elements of the first fly-eye lens 41a. This means that the light flux from each element of the second fly-eye lens 40a is superimposed on one element in the first fly-eye lens 41a. Therefore, the illuminance distribution on the entrance surface of the first fly-eye lens is made uniform by the integration effect. Each element in the uniformed first fly-eye lens is further integrated (superimposed) to illuminate the reticle 9, so that the illuminance on the reticle 9 is very uniform.

The first fly-eye lens groups 41a, 4a
Since 1b is located at a position distant from the optical axis AX, the depth of focus of a projected image of a pattern having a specific direction and pitch in the reticle pattern 10 can be extremely increased. However, the direction and pitch of the reticle pattern 10 are expected to differ depending on the reticle 9 used. Therefore, to be optimal for each reticle 9,
The first fly-eye lens groups 41a and 41 are driven by the drive system 56.
b and guide optical systems 42a, 42b, 43a, 43
b or the second fly-eye lens groups 40a, 4b
0b, the position of the light splitting optical systems 20, 21 and the like can be changed. The drive system 56 operates according to the operation command of the main control system 50, and the setting conditions such as the position at this time are input from the keyboard 54. Alternatively, a barcode pattern on the reticle 9 may be read by the barcode reader 52, and setting may be performed based on the information. The above illumination conditions may be written in a barcode pattern on the reticle 9, or the main control system stores (inputs in advance) the reticle name and the illumination conditions corresponding thereto,
The illumination condition may be determined by collating the reticle name described in the barcode pattern with the stored content.

FIG. 2 shows the light splitting optical systems 20, 21 in FIG.
FIG. 4 is an enlarged view of the first fly-eye lens groups 41a and 41b. Here, the first polyhedral prism 20 and the second
The surfaces facing each other with the polygonal prism 21 are assumed to be parallel, and the entrance surface of the prism 20 and the exit surface of the prism 21 are perpendicular to the optical axis AX. The first polyhedral prism 20 is held by a holding member 22, and the second polyhedral prism 21 is held by a holding member 23. Each of the holding members 22 and 23 includes a movable member 24a,
It is held by 24b and 25a, 25b, and is movable on the fixing members 26a, 26b in the left-right direction in the figure, that is, the direction along the optical axis AX. This operation is performed by active members 27a, 27b, 28a, 28b such as motors. Further, since the first polyhedral prism 20 and the second polyhedral prism 21 can be moved independently, the interval between the two light beams to be emitted is changed in the radial direction around the optical axis AX by changing the interval between the two prisms. be able to.

A plurality of light beams emitted from the polyhedral prism 21 enter the second fly-eye lens group. In FIG. 2, one of the second fly-eye lens group, one of the first fly-eye lens group, and one guide optical system (42, 43) are held by one holding member 44a, 44b. Since the holding members are held by the movable members 45a and 45b, respectively, they are movable with respect to the fixed members 46a and 46b. This operation is performed by the active members 47a, 4
7b.

By holding and moving the second fly-eye lens, the first fly-eye lens, and the guide optical system integrally, the optical positional relationship between the first fly-eye lens and the second fly-eye lens can be changed. Without shifting, the position of the light beam emitted from the first fly-eye lens can be arbitrarily changed within a plane perpendicular to the optical axis AX. The holding member 4
Members 48a and 48b protruding from 4a and 44b are light shielding plates. Thereby, stray light generated from the light splitting optical system is blocked, and unnecessary light is prevented from reaching the reticle. Further, since the light shielding plates 48a and 48b are shifted from each other in the direction of the optical axis AX, the limitation on the movable range of the holding members 44a and b can be reduced.

In FIG. 2, the position of each split light beam can be changed in the radial direction with respect to the optical axis AX by changing the distance between the light splitting optical systems (polyhedral prisms) 20 and 21 in the optical axis direction. However, it is also possible to change each light beam in a concentric direction around the optical axis AX. FIG. 3 shows an embodiment in that case. A holding member 23 for holding a second polyhedral prism (pyramid prism) 21 is held by a fixing tool 25. The holding member 23 is the same as that shown in FIG. It is rotatable in the plane of the paper with respect to the fixture 25. This rotation is performed by a driving member 29 such as a motor provided on the fixture 29. A motor 29 is provided around the holder 23.
The gear 30 is provided in correspondence with the position of. FIG.
FIG. 3B is a cross-sectional view taken along the arrow 3A in FIG.

Here, the fixture 25 may be further held as shown in FIG. 2, and may be movable in the direction of the optical axis AX. Although FIG. 3 shows only an example of the case of the second polyhedral prism 21, the first polyhedral prism 20 can be similarly rotated (with respect to the optical axis AX). Also, instead of rotating each of the polyhedral prisms 20, 21 separately, the fixing members 26a, 26b in FIG.
With respect to the optical axis A with respect to another fixing portion (exposing device body, etc.)
It may rotate around X. The rotation mechanism in this case may be configured so that, for example, the holding member 23 in FIG. 3 holds the fixing members 26a and 26b shown in FIG. 1 instead of the polyhedral prism 21.

As described above, when a plurality of light beams emitted from the light splitting optical systems 20 and 21 change their positions in the radial direction and the concentric direction around the optical axis AX, the second fly on which these light beams are incident. The positions of the eye lens groups 40a and 40b also need to be variable accordingly. FIG. 4 shows an example of a mechanism that enables a two-dimensional (in-plane direction perpendicular to the optical axis AX) operation for this purpose. In FIG. 4, as shown in FIG. 2, the second fly-eye lenses 40a and 40b, the guide optical system 42
a, 42b, 43a, 43b and the first fly-eye lens 41a, 41b (the holding member 4)
4a and 44b) are views of the optical axis AX viewed from the reticle side. Each synthetic fly-eye lens 41A, 41
B, 41C, 41D are holding members 44A, 44B, 44
C, 44D, which are further movable members 45
A, 45B, 45C, 45D and the optical axis AX by the active members 46A, 46B, 46C, 46D.
It is movable in the radial direction around. The active members 46A, 46B, 46C and 46D are fixed to the fixing members 49.
A, 49B, 49C, 49D on the said radiation direction,
Since it can move in a direction substantially perpendicular (substantially concentric direction), the synthetic fly-eye lenses 41A, 41B, 41C,
1D is two-dimensionally movable in a plane perpendicular to the optical axis AX (in the paper). Thus, the reticle can be efficiently irradiated with each light beam split by the light splitting optical system.

The movable members 45A, 45B, 4
The operation directions of 5C and 45D are not limited to the radiation direction about the optical axis AX, but may be any directions perpendicular to the optical axis AX. Also, as shown in FIG. 2, in the case of a system that is movable only in one dimension, the direction is similarly set to the optical axis AX.
May be any direction perpendicular to. FIG. 5 shows a modification of the guide optical system, in which the guide optical systems 42a, 42b, 43
a and 43b are second fly-eye lenses 40a and 40b, respectively.
b, the first fly-eye lenses 41a and 41b are arranged eccentrically with respect to the respective centers.

The position of each illumination light beam emitted from each second fly-eye lens 40a, 40b is determined by the eccentric guide optical system 4.
2a, 42b, 43a, 43b, the first fly-eye lens 41a changes in an in-plane direction perpendicular to the optical axis AX.
It is incident on 41b. Further, the guide optical systems 42a, 42
By changing the degree of eccentricity of b, 43a, 43b, the position of each light beam on the entrance surface of the first fly-eye lens group 41a, 41b (position in a plane perpendicular to the optical axis AX) can be changed. . In FIG. 5, this change in the amount of eccentricity is performed by the active members 421a, 421b, 431a, and 431b. Active members 421a, 421b, 431a,
431b is a holding member 420a, 420b, 430a,
Guide optical systems 42a, 42b, 43 via 430b
a, 43b are movable. In addition, the incident surface (left end in the figure) of each second fly-eye lens 40a, 40b and the incident surface (left end in the figure) of each first fly-eye lens 41a, 41b.
Are almost formed in an image-forming relationship, but the guide optical system 42
If the operations of a, 42b, 43a, and 43b are in an in-plane direction perpendicular to the optical axis AX, this imaging relationship (in the optical axis AX direction) is not greatly disrupted. Each of the first fly-eye lenses 41a and 41b is also movable in an in-plane direction perpendicular to the optical axis AX by the active members 411a and 411b similarly to the guide optical system.

In the system shown in FIG. 5, a light beam emitted from each of the second fly-eye lenses 40a and 40b is transmitted to a guide optical system 42.
It is possible to move to an arbitrary position in a plane perpendicular to the optical axis AX by a, 42b, 43a, 43b. Therefore,
The second fly-eye lens groups 40a and 40b and the light splitting optical systems 20 and 21 may not be movable but may be fixed. In FIG. 5, these are held by the common holding member 22a. However, the guide optical system 4 as shown in FIG.
2a, 42b, 43a, 43b and the first fly-eye lens groups 41a, 41b,
The 0, 21 and second fly-eye lens groups 40a, 40b may be individually movable as shown in FIGS. In FIG. 5, each of the first and second fly-eye lenses has two lenses, but any number may be used.

FIGS. 6, 7 and 8 show modifications of the light dividing optical system. In the example of FIG. 6, the light splitting optical system includes a concave polygonal prism 20a and a convex lens (or a lens group having a positive power) 21a. The collimated illumination light beam emitted from the input lens 4 is split and diverged by the polyhedral prism 20a, but is condensed by the convex lens 21a and enters the second fly-eye lenses 40a and 40b. The inclination angle of the inclined surface of the polyhedron prism 20a is set to a theta _1, the change of this angle, the second fly-eye lens 40a, 4
The position in the plane perpendicular to the optical axis AX of each light beam after the division near 0b can be changed. For example, as shown in the figure,
theta ₁ and theta of two with different tilt angles ₂ polygonal prism 2
0a and 20b may be prepared, and these may be made replaceable by the active member 27c. Here, two polygonal prisms 2
0a and 20b are held by an integral holder 22a, and the holder 22a is held by a movable member 24c. The movable member 24c is movable with respect to the fixed member 26c based on the power of the active member 27c.

Although the two polyhedral prisms in FIG. 6 have different inclination angles of the inclined surfaces and the same direction, the directions may be different. Alternatively, one may be a V-shaped recess for dividing into two, and one may have a pyramid-shaped recess. Also, the second fly-eye lens groups 40a and 40b and the guide optical systems 42a and 42b and 4 in FIG.
3a, 43b, first fly-eye lens groups 41a, 41b
Has a configuration similar to that shown in FIG. 2, FIG. 4, and FIG.

FIG. 7 shows an optical fiber 2 as a light splitting optical system.
This is an example using 0c. The illumination light incident from the fiber incident part 20b is split into two light beams at the emission parts 21b and 21c. In addition, the emission portions 21b and 21c are held by the same holding members 44c and 44d as the synthetic fly-eye lens held integrally as shown in FIG. Accordingly, the position of each light beam automatically moves (follows) with the movement of each synthetic fly-eye lens.

FIG. 8 shows a plurality of mirrors 2 as a light splitting optical system.
This is an example using 0d, 21e, and 21f. First mirror 2
0d is a V-shaped mirror that divides a light beam into two. The second mirrors 21e and 21f are plane mirrors and guide each light beam to the first fly-eye lenses 40a and 40b. Here, it is assumed that the second mirrors 21e and 21f are integrally held by holding members 44e and 44f that integrally hold the composite fly eye.

7 and 8, the holding members 44c, 44d, 44e and 44f of the synthetic fly's eye can move in an in-plane direction perpendicular to the optical axis AX, as in FIG. 2 or FIG. The number of fly-eye lenses and the number of divisions by the light dividing optical system are not limited to two, but may be any number. In FIG. 7, the number of divisions of the fiber 20c may be changed, and in FIG.
A pyramid-type mirror (four-split) or the like may be used as the mirror 20d.

The configuration of the light splitting optical system is not limited to these. For example, the polygon prism 20 shown in FIG.
Instead of a and 20b, it is also possible to use a diffraction grating, especially a phase diffraction grating, a convex lens array, or the like. FIG. 9 shows the first fly-eye lens groups 41a and 41b.
This is a modification of the system from to the projection optical system 11. The illumination light emitted from the emission surface of the first fly-eye lens, that is, the Fourier transform surface for the reticle pattern 10,
The light is condensed and shaped by the relay lens 6a. At this time, a surface having an image forming relationship with the reticle pattern 10 is created by the action of the relay lens 6a. Therefore, by providing the field stop (illumination area stop) 14 on this surface, the illumination area on the reticle pattern surface can be limited.

The illuminating light is applied to the reticle 9 via the relay lens 6b, condenser lenses 6c and 8 and mirror 7 after the field stop 14. A reticle pattern 10 is provided between the relay lens 6b and the condenser lens 6c.
Appears on the Fourier transform surface 17b. Aperture stop 5 in FIG.
Is provided near the exit surface of the second fly-eye lens, but may be provided near the Fourier transform surface 17b.

Next, the fly-eye lens element used in the present invention will be described with reference to FIG. FIG.
(A) shows the incident surface 401a and the light source side focal plane 4 as described above.
03a, the exit surface 402a and the reticle-side focal plane 404
"a" is a matching model, which is used in the above embodiment.

However, in the configuration of FIG.
All the light beams inside the element of the fly-eye lens pass through the glass, and a light-converging point is generated inside the glass (fly-eye lens). For example, when a pulsed laser such as an excimer is used as a light source, the energy per pulse becomes extremely high, and if the focal point exists in the glass, the glass may be damaged by the light energy of the focal point.

FIGS. 10B and 10C show fly-eye lens elements for preventing this. FIG.
In (B), both the entrance surface 401b and the exit surface 402b are formed of convex lenses, but the reticle-side focal surface 404b is different from the exit surface 402b (the light source-side focal surface 403b and the entrance surface 401b coincide). This can be realized by changing the curvature of the entrance surface 401b and the exit surface 402b. In this case, the light beam from the light source has a condensing point outside the fly-eye lens element 400b.

FIG. 10C is a modification of FIG. 10B, and shows a fly-eye lens element 400c having a plane of incidence 401c. Also in this case, the light condensing point (reticle side focal plane 404c) can be projected outside the lens 400c. Further, the light beam is not condensed at all in the lens 400c. However, since the incident surface 401c does not have a refraction action, a light beam hits the inner wall of the fly-eye lens 400c except for perpendicular and parallel incident light, causing stray light. Therefore, FIG. 10C is particularly effective as the second fly-eye lens when the light source is a laser. This is because, when a laser light source is used, the incident light beam can be made substantially parallel light beam and can be vertically incident on the first fly-eye lens.

On the other hand, in the case of FIG.
As in the case of (C), use as a first fly-eye lens with a laser light source is suitable. The fly-eye lens element shown in FIG. 10D has two convex lenses 400d,
400e. Unlike FIGS. 10A to 10C, the space between the two convex lenses 400d and 400e is filled with a gas such as air, nitrogen, or helium. For example, when using an exposure wavelength of 200 nm or less,
Since there is no lens material having good transparency, FIG.
As shown in (D), it is better to reduce the number of transparent solid members such as glass as much as possible. In this case, it is preferable that the projection optical system uses a reflection optical system (which may include a partly refracting member), and the light splitting optical system uses a reflection mirror as shown in FIG.

Next, how to optimize these systems according to the reticle pattern to be exposed will be described.
Each position of the first fly-eye lens group (a position in a plane perpendicular to the optical axis) is preferably determined (changed) according to a reticle pattern to be transferred. The position determination method in this case is, as described in the operation section, an effect of improving the resolution and the depth of focus that are optimal for the fineness (pitch) of the pattern to which the illumination light flux from each first fly-eye lens group is to be transferred. The position (incident angle ψ) at which light is incident on the reticle pattern may be obtained so as to obtain

Next, a specific example of determining the position of each first fly-eye lens group will be described with reference to FIGS.
This will be described with reference to (C) and (D). FIG. 11 shows the reticle pattern 10 from the first fly-eye lens groups 41a and 41b.
FIG. 4 is a diagram schematically illustrating a portion up to and including a reticle-side focal plane 414a, 414b of a first fly-eye lens group 41;
Correspond to the Fourier transform surface 17 of the reticle pattern 10. At this time, a lens or a lens group that makes them have a Fourier transform relationship is represented as one lens 6. Further, the distance from the fly-eye lens-side principal point of the lens 6 to the reticle-side focal planes 414a and 414b of the fly-eye lens group 41 and the distance from the reticle-side principal point of the lens 6 to the reticle pattern 10 are both f.
And

FIGS. 12A and 12C are diagrams each showing an example of a partial pattern formed in the reticle pattern 10, and FIG. 12B is a diagram showing the case of the reticle pattern of FIG. At the center of the optimal first fly-eye lens group,
FIG. 12D shows the position on the Fourier transform plane 17 (pupil plane of the projection optical system). FIG. 12D shows the optimal position of each fly-eye lens group (optimum fly-eye lens) in the case of the reticle pattern shown in FIG. FIG. 4 is a diagram illustrating a position of a center of a lens group).

FIG. 12A shows a so-called one-dimensional line-and-space pattern in which a transparent portion and a light-shielding portion are arranged in a band in the Y direction with the same width, and they are arranged at a pitch P in the X direction.
Are arranged regularly. At this time, the optimum positions of the individual first fly-eye lenses are on the line segment Lα in the Y direction assumed in the Fourier transform plane and the line segment L as shown in FIG.
Any position on β. FIG. 12B is a diagram in which the Fourier transform surface 17 with respect to the reticle pattern 10 is viewed from the optical axis AX direction, and the coordinate system X, Y in the surface 17 is a diagram in which the reticle pattern 10 is viewed from the same direction. Same as A).

In FIG. 12B, the distances α and β from the center C through which the optical axis AX passes to the line segments Lα and Lβ are α
= Β, and when λ is the exposure wavelength, α = β = f ·
It is equal to (1/2) · (λ / P). This distance α · β is f
If it can be expressed as sinψ, then sinψ = λ / 2P, which is consistent with the numerical value described in the section of operation. Therefore, each first
Each center of the fly-eye lens (each barycenter of the light intensity distribution of the secondary light source image created by each of the first fly-eye lenses)
If the position is on the line segments Lα and Lβ, the 0th-order diffracted light generated by the illumination light from each fly-eye lens and ± with respect to the line and space pattern as shown in FIG.
Two diffracted lights with one of the first-order diffracted lights are:
In the pupil plane 12 of the projection optical system, the light passes through a position that is substantially equidistant from the optical axis AX. Therefore, as described above, the depth of focus for the line and space pattern (FIG. 12A) can be maximized, and high resolution can be obtained.

FIG. 12C shows a case where the reticle pattern is a so-called isolated space pattern, in which the pitch in the X direction (horizontal direction) is Px and the pitch in the Y direction (vertical direction) is Py. . FIG. 12D is a diagram showing the optimum position of each first fly-eye lens in this case, and the position and rotation relationship with FIG. 12C are shown in FIG.
This is the same as the relationship between (A) and (B). When illumination light is incident on a two-dimensional pattern as shown in FIG. 12C, two-dimensional patterns corresponding to the periodicity (X: Px, Y: Py) in the two-dimensional direction of the pattern are obtained.
Diffracted light is generated in the dimensional direction. In the two-dimensional pattern as shown in FIG. 12C, either one of the ± 1st-order diffracted lights in the diffracted light and the 0th-order diffracted light are set so as to be substantially equidistant from the optical axis AX on the pupil plane 12 of the projection optical system. Then, the depth of focus can be maximized. Since the pitch in the X direction is Px in the pattern of FIG.
If the center of each fly-eye lens group is on the line segments Lα and Lβ such that α = β = f （(）) （(λ / Px) as shown in FIG. Can be max. Similarly, r = ε = f · (1/2)
If the center of each fly-eye lens group is located on the line segments Lγ and Lε that become (λ / Py), the depth of focus can be maximized for the pattern Y-direction component.

As described above, when the illumination light flux from the fly-eye lens group arranged at each position shown in FIG. 12B or 12D enters the reticle pattern 10, the 0th-order light diffracted light component Do and the + 1st order Folded light component Dp or -1st order diffracted light component D
Any one of m passes through an optical path that is substantially equidistant from the optical axis AX on the pupil plane 12 in the projection optical system 11. Therefore,
As described in the operation section, a projection exposure apparatus having a high resolution and a large depth of focus can be realized.

The reticle pattern 10 shown in FIG.
Although only the two examples shown in (A) or (C) were considered, even for other patterns, attention was paid to the periodicity (fineness), and a + 1st-order or -1st-order diffracted light component from the pattern was used. The center of each fly-eye lens group is located at a position where two light beams, one of the components and the 0th-order diffracted light component, pass through an optical path that is substantially equidistant from the optical axis AX on the pupil plane 12 in the projection optical system. do it. The pattern examples in FIGS. 12A and 12C show the ratio (duty ratio) between the line portion and the space portion.
Is a 1: 1 pattern, so that ± 1st-order diffracted light becomes stronger in the generated diffracted light. For this reason, attention has been paid to the positional relationship between one of the ± 1st-order diffracted lights and the 0th-order diffracted light. However, when the pattern is different from the duty ratio of 1: 1 or the like, the other diffracted lights, for example, one of the ± 2nd-order diffracted lights The positional relationship between the zero-order diffracted light and the zero-order diffracted light may be substantially equidistant from the optical axis AX on the pupil plane 12 of the projection optical system.

The reticle pattern 10 is shown in FIG.
When a two-dimensional periodic pattern is included as in (D), when focusing on one specific 0th-order diffracted light component, on the pupil plane 12 of the projection optical system, the X-direction ( A first or higher order diffracted light component distributed in the first direction) and a first or higher order diffracted light component distributed in the Y direction (second direction) can exist. Therefore, if it is assumed that a two-dimensional pattern is favorably imaged with respect to one specific 0th-order diffracted light component, one of the higher-order diffracted light components distributed in the first direction can be used.
And one of the higher-order diffracted light components distributed in the second direction and a specific 0th-order diffracted light component, on the pupil plane 12, the optical axis AX
The position of a specific 0th-order diffracted light component (one first fly-eye lens) may be adjusted so as to be distributed at substantially the same distance from. For example, the center position of the first fly's eye lens in FIG. 12D may be matched with any of the points Pζ, Pη, Pκ, and Pμ. Each of the points Pζ, Pη, Pκ, and Pμ is a line segment Lα or Lβ (the position optimal for the periodicity in the X direction, ie, the 0th-order diffracted light and one of the ± 1st-order diffracted lights in the X direction are on the pupil plane 12 of the projection optical system). And the line segments Lγ and Lε (optimal positions for the periodicity in the Y direction), so that the optimal light source position in both the X and Y pattern directions Becomes

In the above description, a pattern having a two-dimensional direction is assumed at the same location on the reticle as a two-dimensional pattern. However, when a plurality of patterns having different directions exist at different positions in the same reticle pattern. The above method can be applied also to the above. When the pattern on the reticle has a plurality of directions or finenesses, the optimal position of the fly-eye lens group corresponds to each directionality and fineness of the pattern as described above, or The first fly-eye lens may be arranged at the average position of the optimum positions. In addition, the average position may be a load average taking into account the weight according to the fineness and importance of the pattern.

The 0th-order light component of the light beam emitted from each first fly-eye lens is obliquely incident on the wafer. At this time, if the direction of the center of gravity of the light quantity of these inclined incident light beams (plurality) is not perpendicular to the wafer, the wafer 1
At the time of minute defocusing of No. 3, a problem occurs that the position of the transferred image shifts in the in-plane direction of the wafer. In order to prevent this, the direction of the center of gravity of the light quantity on the image plane of the illuminating light beam (plural) from each fly-eye lens group or on a surface in the vicinity thereof is perpendicular to the wafer, that is, parallel to the optical axis AX. To be there.

That is, when the optical axis (center line) is assumed for each first fly-eye lens, the optical axis AX of the projection optical system 11
The vector sum of the product of the position vector of the optical axis (center line) in the Fourier transform plane with respect to the amount of light emitted from each fly-eye lens group may be set to zero.
As a simpler method, the number of first fly-eye lenses is 2m (m is a natural number), and the positions of m are determined by the above-described optimization method (FIG. 12), and the remaining m are m What is necessary is just to arrange | position at the position which becomes symmetrical about an optical axis AX with this.

As described above, when the position of each first fly-eye lens is determined, the position of the guide optical system (FIG. 5) and the state of the light splitting optical system (FIGS. 2, 3, and 6) are accordingly determined. Is determined. At this time, the position of the guide optical system, the light splitting optical system, the position of the second fly-eye lens, and the like are determined so that the illumination light is incident on the first fly-eye lens most efficiently (without loss of light amount).

In the above system, it is preferable that each operation unit is provided with a position detector such as an encoder. The main control system 50 or the drive system 56 in FIG. 1 moves, rotates, and exchanges each component based on the position information from these position detectors. Although the shape of the lens element of each fly-eye lens group is usually the effective area of the reticle or the circuit pattern area is often rectangular. Therefore,
The incident surface of each element of the first fly-eye lens (the reticle pattern and the image forming relationship: the exit surface and the reticle pattern surface are in a Fourier transform relationship, and the incident surface (the light source side focal plane) and the exit surface (the reticle side focal point) However, since it is a relationship of the Fourier transform), if the rectangular shape corresponds to the planar shape of the reticle pattern surface, only the pattern portion of the reticle can be efficiently illuminated.

The first fly-eye lens is formed as a set of the above-mentioned elements, and the total of all the incident surfaces may be any shape. However, since the total of all the incident surfaces and the incident surface of one element of the second fly-eye lens have an image-forming relationship, the shape is similar to the incident surface of one element of the second fly-eye lens. Light loss can be reduced. For example, if the incident surface of one element of the second fly-eye lens is rectangular, the entire incident surface of each first fly-eye lens is also rectangular. Alternatively, if the incident surface of one element of the second fly-eye lens is a regular hexagon,
The entire entrance surface of each first fly-eye lens may have a shape inscribed in a regular hexagon.

An image of the shape of the incident surface of one element of the second fly-eye lens is formed by the guide optical system for each first element.
When the light is projected so as to be slightly larger than the entire incident surface of the fly-eye lens, the effect of uniforming the illuminance of the first fly-eye lens is further enhanced. The size of the exit surface of each first fly-eye lens is such that the numerical aperture per light beam to be emitted (one width of the angular distribution on the reticle) is smaller than the numerical aperture on the reticle side of the projection optical system. The ratio is preferably about 0.1 to 0.3 times. This is because if the magnification is 0.1 or less, the fidelity of the transfer pattern (image) decreases, and if the magnification is 0.3 or more, the effect of high resolution and large depth of focus is diminished.

In the apparatus shown in the embodiment of the present invention, each optical system (the configuration shown in FIG. 2) of the first fly-eye lens group, the guide optical system, and the second fly-eye lens group from the light splitter is A corresponding part in a conventional illumination optical system, that is, a relay lens and one fly-eye lens may be exchangeable with an integrated one. As described above, each 0th-order diffracted light generated in the reticle pattern by the illumination light emitted from each of the first fly-eye lenses (41a, 41b,...) Is inclined substantially symmetrically with respect to the wafer. Incident. Unless the symmetry of the inclination of the plurality of 0th-order diffracted lights is sufficiently improved, the wafer cannot move from the best imaging plane to the optical axis AX.
When it shifts in the direction, an image shift is caused. Therefore, this will be described in detail with reference to FIGS.

FIG. 13 is a schematic diagram showing the system including the first fly-eye lenses 41a and 41b, the condenser lens 8, the reticle 9, and the lens system 11A on the front side of the projection optical system 11, as in FIG. It is shown in a typical manner.
Here, it is assumed that two one-dimensional grating patterns GR ₁ and GR ₂ having different pitches are formed on the reticle 9. The exit surfaces of the first fly-eye lenses 41a and 41b (more precisely, the surfaces on which a large number of point light source images are formed) are arranged substantially coincident with the Fourier transform surface 17, and divergent light from each point light source image is condensed. The light is collimated into a substantially parallel light beam by the lens 8 and superimposed on the reticle 9.

Here, the point light source image located at the center of the exit surface of the first fly-eye lens 41a is denoted by ISa, the illumination light from this point light source ISa is denoted by LA, and the point-light source image is denoted by LA. The point light source image located at the center is ISb,
The illumination light from the point light source ISb is defined as LB. In FIG. 13, a broken line from each point light source image toward the center of the reticle 9 represents the center line of each light beam. Illumination light LA, LB is optical axis A
The light is incident on the reticle 9 at an angle 傾 symmetrically with respect to X. The angle of incidence ± ψ corresponds to the grating pattern G on the reticle 9.
It is assumed to be optimized for the pitch of R _1. That is, the grating pattern GR _{1 is} irradiated by the illumination light LA.
The 0th-order diffracted light LAo and the -1st-order diffracted light Dma generated from the light are incident on the projection optical system at symmetric angles, and the 0th-order diffracted light LBo and the + _1st- order diffracted light Dpb generated from the grating pattern GR1 by irradiation of the illumination light LB. Means that the light enters the projection optical system at a symmetric angle. In addition, + generated by the illumination light LA
The first-order diffracted light Dpa and the -1st-order diffracted light Dmb generated by the illumination light LB cannot pass through the pupil 12 of the projection optical system even if it can enter the front lens system 11A of the projection optical system.

FIG. 14 schematically shows an optical path from the reticle 9 to the wafer 13 under the illumination conditions shown in FIG. 14, a projection optical system 11 includes a front lens system 11A and a rear lens system 11 with a pupil 12 interposed therebetween.
B, the front lens system 11A has a function of Fourier transforming light from the pattern on the reticle 9 to the plane of the pupil 12, and the rear lens system 11B is distributed on the plane of the pupil 12. It has the function of inverse Fourier transforming light onto the wafer. Further, since the projection optical system 11 is a telecentric system on both the reticle side and the wafer side, the projection optical system 11 travels from each center point of the grating patterns GR ₁ and GR ₂ on the reticle in parallel with the optical axis AX and enters the front lens system 11A. Light rays LL ₁ , LL ₂
Is the center point of the pupil 12 (the point through which the optical axis AX passes) CC
Obliquely, the light again reaches the wafer 13 from the rear lens system 11B in parallel with the optical axis AX.

[0078] First, symmetrical with respect to the illumination light LA and the 0-order diffracted light LAo and -1-order diffracted light Dma generated from the grating pattern GR ₁ by irradiation of (parallel light flux), while the principal ray LL ₁ of both parallel beams The light enters the front lens system 11A at an appropriate angle ψ, and converges as spots at two points Qa and Qb in the pupil 12. This point Qa, Qb is located symmetrically with respect to the pupil center point CC, the point Qa, the direction connecting the Qb coincides with the pitch direction of the grating pattern GR _1. Further, the point light source ISa is re-imaged at the point Qa by the 0th-order diffracted light LAo, and the point light source ISa is formed at the point Qb by the -1st-order diffracted light Dma.
a is re-imaged. Then, the zero-order diffracted light LAo and -1
The next-order diffracted light Dma is converted by the rear lens system 11B into parallel light beams having symmetrical incident angles, and intersects on the wafer 13. As a result, an image (interference fringe) GR _1a ′ of the grid pattern GR ₁ is formed on the wafer 13.

Here, assuming that the incidence angles of the 0th-order diffracted light LAo and the -1st-order diffracted light Dma on the wafer 13 are ψ ′ and the reduction magnification of the projection optical system 11 is 1 / M, M · sinψ = s
inψ´ relationship. The pitch P _{f of the} interference fringes generated on the wafer 13 is represented by the following equation. _{P f = λ / (sinψ' +} sinψ') = λ / 2sinψ' addition, if the pitch of the grating pattern GR ₁ and Pg _1, -1 order diffracted light Dma generated by the illumination light LA incident angle ψ
The diffraction angle from the 0th-order diffracted light is approximately 2 °, to be precise, λ / Pg ₁ = sinψ (incident angle) + sinψ (the angle of the _first -order diffracted light from the optical axis). Thus, the pitch P _f of the interference fringes on the wafer 13 is as follows.

P _f = λ / 2 sinψ ′ = λ / 2M sinψ = λ / 2M (λ / 2Pg ₁ ) = Pg ₁ / M That is, the image GR _1a in which the pitch of the grating pattern GR ₁ on the reticle is reduced to 1 / M as it is. 'Is projected. on the other hand,
Another illumination light LB for the reticle is illumination light LA
, The 0th-order diffracted light LBo and the + 1st-order diffracted light Dpb generated by the illumination light LB pass through the same optical path as the -1st-order diffracted light Dma and the 0th-order diffracted light LAo, respectively, and pass through the points Qb, After convergence in Qa, the wafer 13
Intersects as a parallel light beam above. At this time, an image (interference fringe) GR _1b ′ is generated by interference between the 0th-order diffracted light LBo and the + 1st-order diffracted light Dpb. The image GR _1b ′ and the above-described image GR _1a ′ are generated by being superimposed at exactly the same position because the two zero-order diffracted lights LAo and LBo are symmetrically incident on the principal ray LL ₁ . . Also, two images GR _1a ′, G
Since no constant interference occurs between R _1b ′, this 2
The image obtained by simply adding the intensity of the two images is the final image GR ₁
'. Two images GR _1a ′, GR _1b ′
Are the zero-order light of amplitude intensity 1 and the amplitude intensity of 0.63, respectively.
The illuminance (absolute value of the amplitude intensity) on the wafer 13 is as shown in FIG. 15 because it is caused by interference with the primary light of 7 (2 / π).

In FIG. 15, the horizontal axis represents the position x in the pitch direction, and the vertical axis represents the image plane illuminance. The contrast of the interference fringes obtained in the interference between the zero-order light and the first-order light has a peak value Ip
And the bottom value Ib, 100 · (Ip−I
b) / (Ip + Ib) [%].

Further, in each of the two images GR _1a ′ and GR _1b ′, since the 0th-order diffracted light and one 1st-order diffracted light have a symmetrical incident angle ψ ′, the wafer surface and the best image forming surface are different from each other. Optical axis A
Even if displaced in the X direction, they are superimposed without lateral displacement in the pitch direction. This means that in other words, for the grating pattern GR _1, means that the telecentricity of the projection image GR ₁ '(tele St. City) is guaranteed.

[0083] Next, the image pitch is larger lattice pattern GR ₂ than the lattice pattern GR _1, again 14
Think with reference to. Since the incident angles of the illumination lights LA and LB are symmetrically fixed at ψ, the zero-order diffracted light LAo ′ generated from the grating pattern GR ₂ by the illumination light LA.
The (parallel light beam) converges at a point Qa in the pupil 12 of the projection optical system, and then reaches the wafer 13 as a parallel light beam having an incident angle ψ ′. However, the -1st-order diffracted light Dma' generated from the grating pattern GR ₂ by the illumination light LA, to the pitch of the grating pattern GR ₂ is large, 0 does not pass through the symmetrical optical path-order diffracted light LAo'. That is, the -1st-order diffracted light D
ma ′ falls within the pupil 12 at the point Qa ′ between the points Qa and Qb, and enters the wafer 13 as a parallel light beam having an angle smaller than the incident angle ψ ′. Similarly, the zero-order diffracted light LBo ′ generated from the grating pattern GR ₂ by the irradiation of the illumination light LB.
And the + 1st-order diffracted light Dpb ′ do not pass through symmetric optical paths, and converge on the pupil 12 at points Qb and Qb ′, respectively. What is important here is that the two zero-order diffracted lights LAo ',
This means that LBo 'always passes through symmetric points Qa and Qb in the pupil 12 regardless of the pitch of the reticle grating pattern. Thereby, two first-order diffracted lights Dma ',
It is guaranteed that Dpb 'also always passes through symmetric points Qa' and Qb 'in the pupil 12.

By the way, even for the grating pattern GR ₂ , one image GR _2a ′ is generated by the interference between the zero-order diffracted light LAo ′ and the −1st-order diffracted light Dma ′, and the zero-order diffracted light LB
One image G due to interference between o 'and the + 1st-order diffracted light Dpb'
R _2b ′ is generated and these two images GR _2a ′, GR _2b ′
To form a final image GR ₂ ′.

FIG. 16 shows two images GR._2a', GR_2b´ raw
FIG. 16A shows the zero-order diffracted light LA.
o ′ and the −1st-order diffracted light Dma ′ are principal rays LL_TwoUnpaired against
This shows how it is called. At this time, as shown in FIG.
As shown, the wafer surface coincides with the best image plane and z = 0.
The image GR on the wafer_2aThe center of 'is the chief ray LL _Two
Located on top. However, the wafer surface is in the z direction from the best image surface.
+ Δz (or −Δz) in the direction (optical axis AX direction)
Then, the image GR on the wafer_2aThe center of 'is the chief ray LL_TwoFrom
A lateral shift occurs by -Δx (or + Δx) in the x direction. Figure
The straight line LTa in 16 (B) is the zero-order diffracted light LAo ′ and −1
Bisected by each center line with the next diffracted light Dma '
This is the center line, and the inclination of this straight line LTa is the telecentric error.
It has become. Here, the slope of the straight line LTa is -ε_aToss
Then, the lateral shift amount Δx is approximately expressed by the following equation.

Δx = Δz · sin (−ε _a ) Here, it goes without saying that the slope ε _a changes depending on the pitch Pg ₂ of the grid pattern GR ₂ . On the other hand, another pair of the 0th-order diffracted light LBo 'and the + 1st-order diffracted light Dpb' are also asymmetrically incident on the wafer as shown in FIG. As a result, as shown in FIG. 16D, the image GR _2b ′ is projected with a telecentric error along the straight line LTb. Slope of the line LTb has become a + epsilon _a, lateral deviation amount of the image GR _2b 'is expressed by Δx = Δz · sin (+ ε a).

Considering the case where the wafer surface is located at + Δz, consider the superposition of the image GR _2a ′ shifted by −Δx and the image GR _2b ′ shifted by + Δx. Image GR _2a
'And GR _2b ' each have the illuminance distribution shown in FIG. 15, and are defined as follows. GR _2a ′; K + Esin (ax−Δx) GR _2b ′; K + Esin (ax + Δx) where K is an offset value represented by K = (Ip + Ib) / 2, and E is E = (Ip−Ib) / 2. Where K and E are equal between the two images GR _2a ′ and GR _2b ′. By adding these two equations, the following equation for the image GR ₂ ′ is obtained.

2 (K + E · cosΔx · sinax) As is clear from this equation, two images GR_2a', GR_2b
′ (Image GR _Two´), shift the position in the x direction
The image GR does not include any factors that cause_2a', GR_2bof
The lateral shift amount Δx contributes exclusively as an image contrast change
are doing. That is, the wafer surface matches the best image surface.
The contrast is the best,
If it is shifted, only the contrast is reduced, and the image GR_Two´
Does not occur.

As described above, irrespective of the pitch of the grating pattern formed on the reticle, the symmetry of at least two illumination lights LA and LB to the reticle (the optical axis in the Fourier transform plane) If a point-symmetric relationship with respect to AX is maintained, projection without a telecentric error is always performed. Of course, since most of the pitch directions of the lattice pattern on the reticle are two-dimensional in the x direction and the y direction, as shown in FIG. 12D, four light source images (four first fly-eye images) are formed. It is desirable to dispose the lens) in terms of the depth of focus. However, only for the purpose of preventing a telecentric error from occurring in the projected image of the reticle pattern, the four first fly-eye lenses 41a to 41d are used.
May be arranged on the X axis and the Y axis in FIG. 12D, respectively. That is, in FIG. 12D, there are a total of four points: a point at which each of the lines Lγ and Lε intersects the Y axis and a point at which each of the lines Lα and Lβ intersects the X axis.

By the way, two symmetrical illumination lights LA and L
Images GR _1a ′, GR _1b generated by respective irradiations of B
Or the images GR _2a ′ and GR _2b ′ have their intensity values (Ip, I
b) were the same. That is, the offset K and the amplitude value E of each image are both equal. However, if the offset K and the amplitude value E are different from each other, a final image GR ₁ ′ obtained by combining the two images,
A cosax component in addition to a sinax component is superimposed on GR ₂ ′, and waveform distortion (distortion of image contrast) occurs. Therefore, it is desirable that the offset value K and the amplitude value E be as equal as possible.

FIG. 17A shows a configuration for measuring a difference in contrast between an image GR _1a ′ (GR _2a ′) and an image GR _1b ′ (GR _2b ′), and shows a wafer stage WST of a projection exposure apparatus.
A reference plate FM on which a minute transmission slit (multi-slit) is formed is provided thereon, and a photoelectric sensor DTC for receiving a projected image of a one-dimensional lattice pattern on the reticle 9 by the multi-slit and photoelectrically detecting the transmitted light amount is provided. . This configuration is equivalent to that shown in Japanese Patent Application Laid-Open No. 60-26343. As shown in FIG. 17B, on the reference plate FM, a transmission type multi-slit pattern (grating) Mx having a pitch in the X direction and a transmission type multi-slit pattern My having a pitch in the Y direction are formed. Have been.

For measurement, for example, a shutter (light-shielding plate) is inserted on the emission side of the first fly-eye lens 41b, and the illumination light LA from the first fly-eye lens 41a is inserted.
Only the reticle 9 is illuminated, and as shown in FIG. 17A, an image GR is formed by the 0th-order diffracted light LAo and the -1st-order diffracted light Dma.
Only _1a 'is imaged on the reference plate FM. And this image G
The wafer stage WST is moved so as to scan R _1a ′ in either the multi-slit pattern Mx or My in the pitch direction, and the waveform detector 51 analyzes the signal waveform obtained from the photoelectric sensor DTC at that time. The signal waveform is obtained as shown in FIG. 15, and the peak value Ip and bottom value Ib of the waveform are obtained.

Next, a shutter (light-shielding plate) is inserted on the emission side of the first fly-eye lens 41a, and only the illumination light LB from the first fly-eye lens 41b is irradiated on the reticle 9, and the image GR _{1b is} similarly formed. The peak value of the waveform corresponding to '
And the bottom value. Thereby, two images GR _1a
, GR _1b ′ can be quantitatively determined, and when the difference is extreme, the position adjustment of each fly-eye lens (40, 41) or the prism 20, 21
Is notified to the main control system 50 (see FIG. 1) that the position adjustment is necessary.

Further, in each embodiment of the present invention, a large number of point light source images are formed with a predetermined area on the exit surfaces of the first fly-eye lenses 41a, 41b,. As shown in detail in FIG. 13 above, the first fly-eye lens 41
Among the point light sources at the exit end of a, the illumination light from the point light source closest to the optical axis AX and the illumination light from the point light source farthest away from each other, the numerical aperture sinΔ of one oblique illumination light flux
ψ is determined. The numerical aperture sinΔψ is determined to be about 0.1 to 0.3 with respect to the numerical aperture NA _R of the projection optical system 11 on the reticle side. Of course, the tilted illumination light flux from the first fly-eye lens 41b that forms a pair with the first fly-eye lens 41a also has a similar numerical aperture. For this reason,
The incident angles of the two oblique illumination lights have a fixed range determined by ψ ± Δψ / 2, and the range ± Δψ / 2 determines the pitch of the grating pattern on the reticle under the condition (sin2ψ = λ / P).
Even if it does not exactly match g ₁ ) and slightly shifts, the effect can be sufficiently obtained.

It is also conceivable to provide a spatial filter in the pupil 12 of the projection optical system 11 for transmitting two zero-order diffracted light and one first-order diffracted light. However, the actual pattern formed on the reticle can be considered. If more nearly all of the image is imaged more faithfully, then the spatial filter should be rather absent. In addition, by using two illumination light beams symmetrically inclined in the pitch direction with respect to a one-dimensional lattice pattern,
Since the telecentricity error is offset, a method of continuously moving the wafer 13 by a fixed amount (on the order of μm) in the optical axis direction during exposure, or a method of performing exposure at two or three places separated in the optical axis direction is used together To further increase the depth of focus
The effect can be sufficiently obtained.

Further, in order to finely adjust the illuminance distribution on the reticle 9 and the incident angle ψ (or the numerical aperture sinΔψ), the first fly-eye lenses 41a and 41b are moved together or independently in the direction of the optical axis AX. You may make it do.

[0097]

As described above, according to the present invention, it is possible to realize a projection exposure apparatus having a higher resolution and a larger depth of focus than the conventional one while using a reticle having a normal transmission and shielding pattern. Moreover, according to the present invention, it is only necessary to replace the illumination optical system part of the projection exposure apparatus already operating at the semiconductor production site, and use the projection optical system of the operating apparatus as it is to increase the resolution further than before. That is, large integration is possible.

The illumination system used in the present invention is more complicated than the normal type, but the fly-eye lens is moved in the optical axis direction by two times.
Since the reticle is arranged in stages, the uniformity of the illuminance on the reticle surface and the wafer surface has good characteristics equal to or better than that of the conventional apparatus. Also, due to the effect of the two-stage fly-eye lens structure, even if the fly-eye lens is moved in a plane perpendicular to the optical axis, the uniformity of illuminance on the reticle and wafer surfaces remains unchanged.

Since the light splitting optical system efficiently guides the illumination light beam to the first-stage fly-eye lens, the amount of illumination light is not greatly reduced as compared with the conventional apparatus. Therefore,
There is almost no increase in the exposure time, and as a result, there is no decrease in the processing capacity (throughput). Further, as in the embodiment (FIG. 5), in a system in which the second-stage fly-eye lens closer to the reticle is movable, it is possible to obtain optimal illumination according to each reticle pattern.

Further, in a system in which the first and second fly-eye lenses and the guide optical system are integrally held and movable, the number of movable parts can be reduced, the structure is simplified, and the manufacturing and adjustment costs can be reduced. On the other hand, even in a system in which a plurality of guide optical systems and a corresponding first fly-eye lens are movable, the light splitting optical system and the second fly-eye lens group can be integrally held, so that the structure is simple and the manufacturing is also simple. In addition, adjustment costs can be reduced.

In a light splitting optical system or a system in which a part of the light splitting optical system is made variable, an optimum splitting optical system (two-division, four-division switching, etc.) can be used according to each division condition. In a system in which at least a part of the light splitting optical system is movable or rotatable, for example, by changing the interval between the polygonal prisms or rotating the polygonal prism, the splitting state of the light beam can be changed. Can be created.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a projection exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a part of an illumination optical system in FIG. 1;

FIG. 3 is a diagram showing a configuration of a prism when a light splitter in an illumination optical system is divided into four.

FIG. 4 is a diagram showing a structure of a moving mechanism of a fly-eye lens group.

FIG. 5 is a diagram showing a modification of a part of the configuration of the illumination optical system.

FIG. 6 is a diagram showing a first modification of the light splitter in the illumination optical system.

FIG. 7 is a diagram showing a second modification of the light splitter in the illumination optical system.

FIG. 8 is a diagram showing a third modification of the light splitter in the illumination optical system.

FIG. 9 is a diagram showing another configuration of the illumination optical system.

FIG. 10 is a diagram showing some structures of elements of a fly-eye lens.

FIG. 11 is a diagram illustrating the principle of arrangement of a fly-eye lens in an illumination optical system.

FIG. 12 is a diagram illustrating a method of arranging a fly-eye lens.

FIG. 13 is a diagram schematically showing a system from a first fly-eye lens to a lens system on the front side of a projection optical system.

FIG. 14 is a diagram schematically showing an optical path from a reticle to a wafer under the illumination conditions shown in FIG.

FIG. 15 is a diagram showing illuminance on a wafer under the illumination conditions shown in FIG.

FIG. 16 is a diagram showing a state of generation of two images GR _2a ′ and GR _2b ′ on a wafer under the illumination conditions shown in FIG.

FIG. 17 is a diagram showing a configuration suitable for measuring a difference in contrast between two images on a wafer under the illumination conditions shown in FIG. 13;

FIG. 18 is a diagram showing an apparatus configuration for explaining the principle of the present invention.

FIG. 19 is a view for explaining the principle of projection in a conventional projection exposure apparatus.

[Explanation of symbols]

 Reference Signs List 1 light source 8 condenser lens 9 reticle 11 projection lens 12 pupil 13 wafer 20, 21 prism 41a, 41b first fly-eye lens group 40a, 40b second fly-eye lens group 42a, 42b, 43a, 43b Guide optical element

Claims (22)

[Claims] 1. A projection exposure apparatus comprising: an illumination optical system that irradiates illumination light from a light source onto a mask; and a projection optical system that projects the illumination light onto a substrate. Illumination light distributed outside the center on the Fourier transform plane for the pattern,
A projection exposure apparatus comprising an optical member movable on the Fourier transform plane in a radial direction about an optical axis of the illumination optical system. 2. The projection exposure apparatus according to claim 1, wherein the illumination light moves in the radiation direction according to a pattern to be transferred onto the substrate. 3. The projection exposure apparatus according to claim 1, wherein the optical member includes an optical element movable along an optical axis of the illumination optical system. 4. The projection exposure apparatus according to claim 1, wherein the optical member is disposed between the light source and an optical integrator in the illumination optical system. 5. A Fourier transform plane in the illumination optical system such that the illumination light is incident on the mask at an incident angle corresponding to the fineness of the pattern and is inclined with respect to the optical axis of the illumination optical system. The projection exposure apparatus according to any one of claims 1 to 4, wherein a light amount distribution of the illumination light is determined. 6. The light quantity distribution is determined such that the illumination light is emitted from a plurality of regions on the Fourier transform surface in the illumination optical system, the distances of which are substantially equal to the optical axis, respectively. The projection exposure apparatus according to claim 5, wherein 7. A projection exposure apparatus comprising: an illumination optical system that irradiates illumination light from a light source onto a mask; and a projection optical system that projects the illumination light onto a substrate. A first light source for distributing the illumination light outside the optical axis of the illumination optical system when the illumination light is arranged outside the optical axis of the illumination optical system when forming a light quantity distribution in which the illumination light is distributed outside the central portion on the Fourier transform plane for the pattern A projection exposure apparatus, comprising: an optical member; and a second optical member disposed in the illumination optical system by replacing the first optical member when forming a light amount distribution different from the light amount distribution. 8. The projection exposure apparatus according to claim 7, wherein the first and second optical members are selected according to a pattern to be transferred onto the substrate. 9. The optical system according to claim 7, wherein the first and second optical members are respectively disposed between the light source and an optical integrator in the illumination optical system.
3. The projection exposure apparatus according to claim 1. 10. The first optical member is used for forming a light quantity distribution in which the illumination light is incident on the mask while the illumination light is inclined with respect to the optical axis of the illumination optical system at an incident angle corresponding to the fineness of the pattern. The projection exposure apparatus according to any one of claims 7 to 9, wherein: 11. The first optical member is used for forming a light quantity distribution in which the illumination light is respectively emitted from a plurality of regions on the Fourier transform surface in the illumination optical system, the distances of which are substantially equal to the optical axis. The projection exposure apparatus according to claim 10, wherein: 12. The projection exposure apparatus according to claim 7, wherein each of the first and second optical members is a diffraction element. 13. A diffracted light having different orders generated from the pattern by irradiation of the illumination light passes through a position on the pupil plane of the projection optical system, the distances of which from the optical axis are substantially equal. 11. The projection exposure apparatus according to claim 5, wherein the incident angle is determined. 14. An incident angle of the illumination light to the mask, ψ, a diffraction angle of two diffracted lights of the same order generated from the pattern by irradiation of the illumination light, θm, and the mask side of the projection optical system on the mask side. If the number of openings is referred to as NA _R, the one with sin (θm-ψ) of the two diffracted lights = NA as _R the relationship is satisfied, wherein the angle of incidence is determined according to claim 5 or The projection exposure apparatus according to claim 10. 15. The projection exposure according to claim 14, wherein the one diffracted light satisfying the relationship is substantially symmetric with respect to an optical axis of the projection optical system and a zero-order diffracted light generated from the pattern. apparatus. 16. The incident angle ψ is sinψ = λ / 2, where λ is the wavelength of the illumination light and P is the pitch of the pattern.
11. The projection exposure apparatus according to claim 5, wherein P is determined to be P. 17. When the pattern is provided along first and second directions intersecting each other, the 0th-order diffracted light generated from the pattern by the irradiation of the illumination light, the 0th-order diffracted light,
One of the higher-order diffracted lights distributed in the first direction around the first-order diffracted light and one of the higher-order diffracted lights distributed in the second direction around the zeroth-order diffracted light on the pupil plane of the projection optical system. 11. The incident angle is determined so as to be distributed at substantially the same distance from the optical axis.
3. The projection exposure apparatus according to claim 1. 18. The apparatus according to claim 18, further comprising: means for relatively moving an image plane of the projection optical system and the substrate along an optical axis of the projection optical system to increase a depth of focus during exposure of the substrate by the illumination light. The projection exposure apparatus according to claim 1. 19. A method for forming a semiconductor element, comprising a step of transferring a device pattern onto a wafer using the projection exposure apparatus according to claim 1. Description: 20. A projection exposure method for irradiating a mask with illumination light from a light source through an illumination optical system and exposing a substrate with the illumination light through a projection optical system, according to a pattern to be transferred onto the substrate. Move the optical member in the direction of the optical axis in the illumination optical system, the illumination light distributed outside the center on the Fourier transform surface for the pattern in the illumination optical system, on the Fourier transform surface, A projection exposure method characterized by moving in a radial direction about an optical axis of an illumination optical system. 21. A projection exposure method for irradiating an illumination light from a light source to a mask through an illumination optical system and exposing a substrate with the illumination light via a projection optical system, wherein the pattern of the mask in the illumination optical system is A first optical member for distributing the illumination light outside the optical axis of the illumination optical system is arranged in the illumination optical system when forming a light quantity distribution in which the illumination light is distributed outside the center on the Fourier transform plane. A projection exposure method, wherein a second optical member is disposed in the illumination optical system by exchanging the first optical member when a light amount distribution different from the light amount distribution is formed. 22. An image plane and the substrate are relatively moved along an optical axis of the projection optical system in order to increase a depth of focus during exposure of the substrate by the illumination light. 22. The projection exposure method according to 20 or 21.