JP3360319B2 - Projection exposure apparatus and method of forming semiconductor element - Google Patents

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 disposed 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 D ₀ , the + 1st-order diffracted light D _P , and −
First-order diffracted light _Dm is generated. Each diffracted light (D ₀ ,
D _m , D _p ) 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 0th-order diffracted light D ₀ and ±
The angle θ (the reticle side) between the first-order diffracted lights D _P and D _m is si
nθ = 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 D _P and D _m become pupils (Fourier transform plane) in the projection optical system 11.
The effective diameter is limited by 12 and cannot pass through the projection optical system 11. At this time, only the _zero-order diffracted light D ₀ reaches the wafer 13 and no interference fringes occur. That is, sinθ> N
When the A _R is not obtained image of the pattern 10, it becomes impossible to transfer the pattern 10 on 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 of the pitch P, the minimum pattern size is about 0.5 · λ / NA _R , but in the actual photolithography process, Some degree of depth of focus is required due to curvature, the effects of process steps, etc., or the thickness of the photoresist itself. For this reason, the practical minimum resolution pattern size is expressed as k · λ / NA _R. here,
k is called a process coefficient and 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 situation, the depth of focus represented by ± λ / 2NA ² will decrease rapidly with the increase of the numerical aperture, and the depth of focus required for actual use will increase. The problem of decreasing becomes more pronounced.

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 projection exposure apparatus of the present invention, an illumination optical system (3 to 8) for irradiating illumination light from a light source (1) to a mask (9) and a pattern image of the mask to a substrate ( 13) a projection optical system (11) for projecting onto the projection optical system; In the projection exposure apparatus according to the first aspect of the present invention, the plurality of first optical integrators (41a, 41b) whose centers are respectively arranged at a plurality of positions decentered from the optical axis (AX) of the illumination optical system are provided. A plurality of second optical integrators (40a, 40b) arranged in pairs with the plurality of first optical integrators, and a light splitter for inputting illumination light from a light source to each of the plurality of second optical integrators (20, 21; 20a, 20b; 20c; 20
d) is provided. Claim 11 of the present invention
In the projection exposure apparatus described in (1), the pupil plane (1
It is used when the light amount distribution of the illumination light on the predetermined surface (17) in the illumination optical system substantially conjugate to 2) is enhanced in a plurality of regions decentered from the optical axis (AX) of the illumination optical system, A pair of prisms (20, 21) relatively movable along the optical axis of the illumination optical system is provided. Further, in the projection exposure apparatus according to claim 15 of the present invention, the light source (1) and the optical integrator (41a,
41b) and a pupil plane (12) of the projection optical system
The light amount distribution of the illumination light on the predetermined surface (17) in the illumination optical system substantially conjugate to the above is increased in a plurality of regions decentered from the optical axis (AX) of the illumination optical system, and this light amount distribution is made variable. The optical system includes a pair of prisms (20, 21) whose distance in the optical axis direction of the illumination optical system is variable in order to adjust the position of each area on a predetermined surface.

[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 D _{O, the} ± 1st-order diffracted light components D _P , D _m , and higher-order diffracted light components become Occurs in a direction corresponding to the degree of fineness.

At this time, the angle at which the illumination light beam (principal ray) is inclined
Incident on the reticle 9 in degrees, the generated diffraction of each order
The light component is also tilted (not angled) compared to when illuminated vertically.
) From the reticle pattern 10. Figure 1
The illumination light L130 in FIG.
It is incident on the tickle 9. Illumination light L130 is reticle putter
And is tilted by ン with respect to the optical axis AX.
0th order diffracted light D traveling in the direction₀, Θ for the 0th order diffracted light_PIs
Inclined + 1st order diffracted light D_P, And zero-order diffracted light D₀Against
And θ_m-1st order diffracted light D _mOccurs. I
However, the illumination light L130 is telecentric on both sides.
The lens is tilted by an angle に 対 し て with respect to the optical axis AX of the projection optical system 11.
0th order diffracted light D₀Also
In a direction inclined by an angle に 対 し て with respect to the optical axis AX of the projection optical system
proceed.

Accordingly, the + 1st-order light D _P travels in the direction of θ _P + に 対 し て with respect to the optical axis AX, and the −1st-order diffracted light D _m is transmitted along the optical axis AX.
Proceeds in the direction of θ _m −ψ. At this time, the diffraction angle θ
_P, theta _m is sin (θ _P + ψ), respectively - a sinψ = λ / P (2) sin (θ m -ψ) + sinψ = λ / P (3).

[0019] Here, + 1-order diffracted light D _P, -1 both-order diffracted light D _m is assumed to transmit pupil 12 of the projection optical system 11. When the diffraction angle increases with the miniaturization of the reticle pattern 10, the reticle pattern 10 first advances in the direction of the angle θ _P + ψ.
1-order diffracted light D _P can not be transmitted through the pupil 12 of the projection optical system 11. That is, a relationship of sin (θ _P + ψ)> NA _R is established. But since the illumination light L130 is incident inclined with respect to the optical axis AX, -1-order diffracted light D _m at a diffraction angle in this case is permeable to the projection optical system 11. Ie
sin (θ _m −ψ) <NA _R

Therefore, the zero-order diffracted light D ₀ is placed on the wafer 13.
If -1 interference fringes caused by two light beams of the diffracted light D _m occurs. 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 (θ _m -ψ) = NA _R (4), and therefore, NA _R + sinψ = λ / PP = λ / (NA _R + sinψ) ( 5) is the pitch of the smallest transferable pattern on the reticle side.

As an example, assuming that sinψ is set to 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, the 0th-order diffracted light component is transmitted to the pupil plane 1 of the projection optical
2, the optical path lengths of the 0th-order diffracted light component and the other diffracted light components are equal,
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. Projection optical system 1
1 is far from the focal point (projection optical system 1).
In the case of (approaching 1), the length becomes longer, 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 defocusing of the foregoing, the amount of shift from the focus position of the wafer 13 [Delta] F, the sine of the incident angle theta _w when the diffracted light is incident on one point on the wafer r
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 D ₀ passes near the optical axis AX, r (0th-order) = 0, while ± 1st-order diffracted light D _P ,
D _m is r (first order) = M · λ / P (M is the magnification of the projection optical system). Therefore, the 0th-order diffracted light D ₀ and the ± 1st-order diffracted light D
_P, the wavefront aberration due to defocus of the D _m is the ^{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 D ₀ 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 · sinψ. On the other hand, the distance of the −1st-order diffracted light component D _m from the optical axis on the pupil plane is r (−1st) = M · sin (θ)
_m −ψ). At this time, sinψ = sin (θ _m
If a -ψ), 0 relative wavefront aberration due to defocusing of the order diffracted light component D ₀ and -1-order diffracted light component D _m becomes zero, even the wafer 13 is slightly deviated in the optical axis direction from the focal position pattern 10 Will not occur as much as before. That is, the depth of focus increases. Also,
As shown in equation (3), sin (θ _m −ψ) + sinψ = λ / P
Therefore, the angle of incidence 照明 of the illumination light beam L130 on the reticle 9 is sinψ = λ / 2P with respect to the pattern of the pitch P.
In this case, 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 was a first polyhedral prism 20 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. And
Each light beam is a separate second fly-eye lens 40a,
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, if the second fly-eye lens group is composed 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 40b enters the first fly-eye lens 41b.

The light beams emitted from the first fly-eye lenses 41a and 41b are guided by the condenser lenses 6 and 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 (here, coincident with the entrance planes) of the first fly-eye lens group 41a and the first fly-eye lens group 41b are, as described above,
It has an imaging relationship. Therefore, the light beam incident on each element incident 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, the first fly-eye lens groups 41a and 41 are driven by the drive system 56 so as to be optimal for each reticle 9.
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 an operation command from the main control system 50. At this time, setting conditions such as the position 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 gear 30 is provided around the holder 23 in correspondence with the position of the motor 29. 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 (the exposure 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 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.
Fly-eye lenses 40a, 40b, 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, B,
C and D are held by holding members 44A, B, C and D, which are further held by movable members 45A, B, C and D, and about the optical axis AX by active members 46A, B, C and D. It is movable in the radial direction. The active members 46A, B, C, and D are fixed members 49A, B, C, and D, respectively.
The upper part of the synthetic fly-eye lens 4 can be moved in a direction substantially perpendicular to the above radiation direction (substantially concentric direction).
1A, 1B, 1C, and 1D are two-dimensionally movable in a plane perpendicular to the optical axis AX (in the paper). Thus, each light beam split by the light splitting optical system can be efficiently irradiated on the reticle.

Incidentally, the movable members 45A, B, C, D in FIG.
Is not limited to the radiation direction about the optical axis AX, but may be any direction perpendicular to the optical axis AX. Also, as shown in FIG. 2, even in the case of a system that is movable only in one dimension, the direction may be any direction perpendicular to the optical axis AX. FIG. 5 shows a modification of the guide optical system. The guide optical systems 42a, 42b, 43a, and 43b are eccentric with respect to the centers of the second fly-eye lenses 40a and 40b and the first fly-eye lenses 41a and 41b. Are located.

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 polyhedral 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, 40
The position in the plane perpendicular to the optical axis AX of each divided light beam near b can be changed. For example, as shown in the figure, θ
₁ and θ of the two having 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 20
a 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 different from the fixed member 26c in the active member 2
It is movable based on the power of 7c.

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, 40b in FIG. 6 guide optical systems 42a, 42b, 43
The holding mechanism for the first and second fly-eye lenses 41a and 41b has the same configuration as that shown in FIGS.

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 elements of the fly-eye lens used in the present invention will be described with reference to FIG. FIG. 10A shows a model in which the incident surface 401a and the light source side focal plane 403a coincide with each other, and the exit surface 402a and the reticle side focal plane 404a coincide with each other, as described above, and 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 the plane of incidence 401c as a plane. 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 an exposure wavelength of 200 nm or less is used, since there is no lens material having good transmittance, FIG.
It is better to reduce 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 unit 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, it is assumed that the distance from the fly-eye lens-side principal point of the lens 6 to the reticle-side focal plane 414ab 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.

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 view showing the case of the reticle pattern shown in FIG. FIG. 12D shows the position of the optimum center of the first fly-eye lens group on the Fourier transform plane 17 (pupil plane of the projection optical system). FIG. 12D shows each fly that is optimal for the reticle pattern shown in FIG. FIG. 4 is a diagram illustrating a position of an eye lens group (an optimum position of the center of each fly-eye 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 have 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 view of the Fourier transform surface 17 with respect to the reticle pattern 10 viewed from the optical axis AX direction, and the coordinate system X, Y in the surface 17 is a view of the reticle pattern 10 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 respective 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 sin ψ, then sin ψ = λ / 2P, which is consistent with the numerical value described in the section of the operation. Therefore, if the respective centers of the first fly-eye lenses (the respective centers of gravity of the light amount distributions of the secondary light source images formed by the respective first fly-eye lenses) are located on the line segments Lα and Lβ, FIG. For the line-and-space pattern as shown in ()), two diffracted lights, one of the 0th-order diffracted light and ± 1st-order diffracted light generated by the illumination light from each fly-eye lens, are projected onto the pupil plane of the projection optical system. At 12, it passes through a position that is approximately 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.

Next, 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 enters a two-dimensional pattern as shown in FIG.
Diffracted light is generated in a two-dimensional direction according to the periodicity in the dimensional direction (X: Px, Y: Py). 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. 12C, as shown in FIG. 12D, a line segment Lα satisfying α = β = fｆ (１ ／) ・ (λ / Px) is obtained. If the center of each fly-eye lens group is on Lβ, the depth of focus can be maximized for the X-direction component of the pattern. 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 are (λ / Py), the depth of focus can be maximized for the pattern Y-direction component.

As described above, when the illumination light beam 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 D ₀ and +1 either one order diffracted light component D _R or -1-order diffracted light component D _m DOO is, the pupil plane 12 of the projection optical system 11
Passes through an optical path that is approximately equidistant from the optical axis AX. Therefore, as described in the section of operation, 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.

Further, reticle pattern 10 corresponds to 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 projection optical system pupil plane 12) And the line segment Lγ, Lε (the position optimal for the periodicity in the Y direction), and therefore the optimal light source position in both the X direction and the Y direction. Become.

In the above description, a two-dimensional pattern having a two-dimensional direction at the same location on the reticle has been assumed, but 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 in which a weight according to the fineness or importance of the pattern is added.

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,
At the time of minute defocusing of No. 3, there is a problem that the position of the transferred image is shifted in the wafer plane direction. 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 position vector of the optical axis (center line) in the Fourier transform plane with respect to the optical axis AX of the projection optical system 11 , And the vector sum of the product of the quantity of light emitted from each fly-eye lens group should be 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-mentioned 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 entrance surface (reticle pattern and imaging relationship: the exit surface and the reticle pattern surface of each element of the first fly-eye lens are in a Fourier transform relationship, and the entrance surface (light source side focal plane) and the exit surface (reticle side). Since the focal point is naturally a relationship of the Fourier transform), if it is a rectangle corresponding to the planar shape of the reticle pattern surface, only the reticle pattern portion 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.

The 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.

Further, 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 from 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-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.
Generated from the zero-order diffracted light LA ₀ and -1-order diffracted light D _ma is incident on the projection optical system in a symmetrical angle, 0-order diffracted light LB generated from the grating pattern GR ₁ by the irradiation of illumination light LB
_{The 0th} and + 1st order diffracted lights D _pb enter the projection optical system at symmetric angles. The + 1st-order diffracted light _Dpa generated by the illumination light LA and the -1st-order diffracted light D generated by the illumination light LB
_{Even if mb} can enter the front lens system 11A of the projection optical system, it cannot pass through the pupil 12 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. Rays LL ₁ , L
L ₂ is the center point of the pupil 12 (the point through which the optical axis AX passes)
After obliquely passing through the CC, the light reaches the wafer 13 from the rear lens system 11B again in parallel with the optical axis AX.

First, the zero-order diffracted light LA ₀ generated from the grating pattern GR ₁ by the irradiation of the illumination light LA (parallel light beam).
If -1-order diffracted light D _ma, the front lens system 11A in a symmetrical angle ψ both against left principal ray LL ₁ of the parallel light beams
And spots at two points Qa and Qb in the pupil 12 and converge. These points Qa and Qb are pupil center points CC
Located symmetrically, the point Qa, the direction connecting the Qb coincides with the pitch direction of the grating pattern GR ₁ with respect. further,
At the point Qa, the point light source ISa is re-imaged by the _0th-order diffracted light LA0, and at the point Qb, the point light source Ia is formed by the -1st-order diffracted light _Dma .
Sa is re-imaged. Then, the zero-order diffracted light LA ₀ and-
The first-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. Thus, an image (interference fringe) GR _1a ′ of the grid pattern GR ₁ is formed on the wafer 13.

Here, the zero-order diffracted light LA₀, -1st order diffracted light
D_ma, And the projection angles of
Assuming that the reduction magnification of the optical system 11 is 1 / M, M · sinψ =
 sinψ '. And on the wafer 13
Pitch P of generated interference fringes _fIs represented by the following equation. P_f= Λ / (sinψ '+ sinψ') = λ / 2 sinψ '₁The pitch of_g1Then
-1st-order diffracted light D generated by illumination light LA having an angle of incidence ψ_ma
The diffraction angle from the 0th-order diffracted light is approximately 2 °,
Is λ / P_g1= Sinψ (incident angle) + sinψ (first-order diffracted light
Angle from the optical axis). Therefore, the wafer 13
The pitch P of the above interference fringes_fBecomes as follows.

[0079] _{P f = λ / 2 sinψ '} = λ / 2M sinψ = λ / 2M (λ / 2P g1) = P g1 / M Namely, an image in which the pitch of the grating pattern GR ₁ on the reticle as it is 1 / M GR _1a ′ is projected. on the other hand,
Another illumination light LB for the reticle is illumination light LA
Is incident exactly symmetrically with respect to, and generated by the illumination light LB 0-order diffracted light LB ₀ and +1 order diffracted light D _pb, -1 through-order diffracted light D _ma, 0-order diffracted light LA ₀ and same optical path for each destination , Points Qb and Qa, and then 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 LB ₀ 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 LA ₀ and LB ₀ are symmetrically incident on the principal ray LL ₁ . Is done. Also, two images GR _1a ′,
Since no steady interference occurs between GR _1b ′, the two images are simply added in intensity to obtain the final image GR.
Projected as 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 (Ip−Ib) / (Ip + Ib) [%] using the following equation and the bottom value Ib.

Further, since the two images GR _1a ′ and GR _1b ′ each have the symmetrical incident angle ψ ′ between the 0th-order diffracted light and one 1st-order diffracted light, 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.

[0082] 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 fixed symmetrically at ψ, the zero-order diffracted light LA ₀ ′ 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 D _ma ′ generated from the grating pattern GR ₂ by the illumination light LA has a large pitch of the grating pattern GR ₂ , and therefore the 0th-order diffracted light LA ₀ ′.
Does not pass through a symmetric optical path. 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 LB generated from the grating pattern GR ₂ by the irradiation of the illumination light LB
_{The 0} ′ and + 1st-order diffracted lights D _pb ′ do not pass through optical paths symmetric to each other, and fall on the points Qb and Qb ′ on the pupil 12, respectively. What is important here is that the two zero-order diffracted lights LA ₀ ′,
LB ₀ ′ always passes through symmetrical points Qa and Qb in the pupil 12 regardless of the pitch of the reticle grating pattern. Thereby, two first-order diffracted lights D _ma ',
It is guaranteed that D _pb ′ also always passes through symmetric points Qa ′ and Qb ′ in the pupil 12.

By the way, also for the grating pattern GR ₂ , one image GR _2a ′ is generated by the interference between the _zero-order diffracted light LA ₀ ′ and the −1st-order diffracted light D _ma ′, and the zero-order diffracted light LB
One image G due to interference between ₀ 'and the + 1st order diffracted light D _pb '
R _2b ′ is generated and these two images GR _2a ′, GR _2b ′
To form a final image GR ₂ ′.

FIG. 16 shows how two images GR _2a ′ and GR _2b ′ are generated. FIG. 16A shows the zero-order diffracted light LA.
₀ 'and the -1st-order diffracted light D _ma' shows how the the has become asymmetrical with respect to the principal ray LL _2. At this time, FIG.
When the wafer surface coincides with the best image plane and is at z = 0, the center of the image GR _2a ′ on the wafer becomes the principal ray LL
Located on _two . However, the wafer surface is z from the best image surface.
When the image GR _2a ′ is displaced in the direction (optical axis AX direction) by + Δz (or −Δz), the center of the image GR _2a ′ on the wafer is laterally shifted by −Δx (or + Δx) in the x direction from the principal ray LL ₂ .
The straight line LTa in FIG. 16B is the zero-order diffracted light LA ₀ ′ and −
This is a center line that is bisected by each center line with the first-order diffracted light D _ma ′, and the inclination of this straight line LTa is a telecentric error. Here, if the slope of the line LTa and-epsilon _a, 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 P _g2 of the grid pattern GR ₂ . Meanwhile, another one
The set of 0th-order diffracted light LB ₀ ′ and + 1st-order diffracted light D _pb ′ also asymmetrically enter 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. Statue G
Since both R _2a ′ and GR _2b ′ have the illuminance distribution shown in FIG. 15, they are defined as follows. _{GR 2a '; K + Esin (} ax-Δx) GR 2b'; K + Esin (ax + Δx) where, K is an offset value expressed by K = (Ip + Ib) / 2, E is E = (Ip-Ib) / 2 Where K and E are equal between the two images GR _2a ′ and GR _2b ′. When these two equations are added, the following equation for the image GR ₂ ′ is obtained.

2 (K + E · cosΔx · sinax) As is apparent from this equation, two images GR_2a’, G
R_2b′ (Image GR _Two') Indicates the position in the x direction.
The image GR does not include any factors that cause_2a’, G
R_2b′ Is mainly determined by the contrast change of the image.
And has contributed. In other words, the wafer surface is
The best contrast,
A shift in the z-direction will only cause a reduction in contrast,
GR_TwoDoes 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, the two symmetrical illumination lights LA and L
The images GR _1a ′, G generated by the respective illuminations of B
R _1b ′ or the images GR _2a ′ and GR _2b ′ have their intensity values (I
p, Ib) were both equal. 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 G obtained by combining the two images is obtained.
A cosax component in addition to the sinax component is superimposed on R ₁ ′ and GR ₂ ′, causing waveform distortion (distortion of image contrast). Therefore, it is desirable that the offset value K and the amplitude value E be as equal as possible.

FIG. 17A shows an image GR _1a ′ (GR _2a ′) and an image G
This shows a configuration for measuring a difference in contrast with R _1b ′ (GR _2b ′). A reference plate FM having a fine transmission slit (multi-slit) is provided on a wafer stage WST of a projection exposure apparatus, and a reticle is provided. 9 is provided with a photoelectric sensor DTC that receives a projected image of the one-dimensional lattice pattern on the multi-slit 9 and photoelectrically detects the amount of transmitted light. 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 exit side of the first fly-eye lens 41b, and the illumination light LA from the first fly-eye lens 41a is inserted.
Only irradiated on the reticle 9, the image GR by as shown in FIG. 17 (A) 0-order diffracted light LA ₀ and -1-order diffracted light D _ma
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 G
Since the contrast difference and the absolute intensity difference between R _1a ′ and GR _1b ′ are quantitatively obtained, when the difference is extreme, the position adjustment of each fly-eye lens (40, 41), the prism 20,
The main control system 50 (see FIG. 1) notifies that the position adjustment of 21 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
The numerical aperture sinΔ of one oblique illumination light flux is obtained by the illumination light from the point light source closest to the optical axis AX and the illumination light from the point light source farthest from the point light sources at the exit end of “a”.
ψ is determined. This numerical aperture sinΔψ is set 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 ± Δ 格子 / 2 determines the pitch of the grating pattern on the reticle under the condition (sin2ψ = λ /
P _g1 ) does not exactly match, and even if it is slightly shifted, the effect can be sufficiently obtained.

It is conceivable to provide a spatial filter in the pupil 12 of the projection optical system 11 for transmitting two 0th-order diffracted light and one 1st-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 the one-dimensional lattice pattern, the telecentricity error is canceled out. μm order), or when using a method of exposing at two or three locations separated in the optical axis direction, to further increase the depth of focus.
The effect can be sufficiently obtained.

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

[0096]

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 a normal type, but the fly-eye lens is moved in the optical axis direction by two.
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 becomes simple, 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 the 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 system in which the light splitting optical system or a part thereof 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 view showing a state of generation of two images GR _2a ′ and GR _2b ′ on the 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

Continuation of the front page (56) References JP-A-4-329623 (JP, A) JP-A-4-267515 (JP, A) JP-A-58-147708 (JP, A) JP-A-4-225514 (JP) JP-A-4-225357 (JP, A) JP-A-5-47637 (JP, A) JP-A-2-3907 (JP, A) JP-A-4-179958 (JP, A) 3-111614 (JP, A) JP-A-3-16114 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/20

Claims (40)

(57) [Claims] 1. A projection exposure apparatus comprising: an illumination optical system for irradiating illumination light from a light source onto a mask; and a projection optical system for projecting a pattern image of the mask onto a substrate, wherein an optical axis of the illumination optical system is provided. A plurality of first optical integrators each having a center disposed at a plurality of positions decentered from the first optical integrator; a plurality of second optical integrators each disposed in a pair with the plurality of first optical integrators; A projection exposure apparatus, comprising: an optical integrator; and a light splitter that causes illumination light from the light source to enter the optical integrator. 2. The plurality of first optical integrators.
Are respectively substantially conjugate with the pupil plane of the projection optical system.
The projection according to claim 1, wherein an end face is arranged.
Shadow exposure device. 3. The plurality of second optical integrators.
Are respectively substantially conjugate with the pupil plane of the projection optical system.
An end surface is disposed, and the other end surface is connected to the plurality of first optical devices.
The other end of the cal integrator is substantially
3. The investment according to claim 2, wherein
Shadow exposure device. 4. The first and second optical integrators.
The exit side focal plane, which is the one end face,
Fly eye arranged substantially conjugate with the pupil plane of the shadow optics
4. The projection dew according to claim 3, wherein the projection dew is a lens.
Light device. 5. A holding member which integrally holds said pair of first and second optical integrators and is movable in a plane perpendicular to an optical axis of said illumination optical system in accordance with the number of said pairs. the projection exposure apparatus according to any one of claims 1 to 4, wherein providing a plurality. 6. The projection exposure apparatus according to claim 5 , wherein each of the plurality of holding members holds a guide optical element disposed between the first and second optical integrators. 7. The light splitter is at least partially movable or
The projection exposure apparatus according to any one of claims 1 to 6 , wherein the projection exposure apparatus is exchangeable and changes an area where the illumination light is distributed in a plane perpendicular to an optical axis of the illumination optical system. . 8. The projection exposure apparatus according to claim 7 , wherein said light splitter includes a pair of prisms which are relatively movable along an optical axis of said illumination optical system. 9. The light splitter according to claim 1 , wherein said light splitter is provided with an optical axis of said illumination optical system.
Including deflection elements for deflecting the illumination light in different directions
The projection exposure apparatus according to claim 7, wherein: 10. The illumination light according to claim 6, wherein the illumination light is provided on a pupil plane of the projection optical system.
The amount of light on a predetermined surface in the illumination optical system substantially conjugate
The cloth is high in a plurality of areas decentered from the optical axis of the illumination optical system.
The plurality of first optical integrators
Is that the position is set corresponding to the plurality of areas.
The investment according to any one of claims 1 to 9, characterized in that:
Shadow exposure device. 11. An illumination system for irradiating a mask with illumination light from a light source.
A bright optical system and a pattern image of the mask on a substrate.
The projection optical system, the illumination optical system being substantially conjugate with a pupil plane of the projection optical system.
The light amount distribution of the illumination light on a predetermined surface in the
For use in multiple areas decentered from the optical axis of the system
Is relatively movable along the optical axis of the illumination optical system.
A projection exposure apparatus comprising a pair of prisms.
Place. 12. The pair of prisms includes the light source and the prism.
Between the optical integrator in the illumination optical system
The projection exposure according to claim 11, wherein the projection exposure is performed.
apparatus. 13. The pair of prisms are arranged on the predetermined surface.
Note that the interval is adjusted according to the light amount distribution to be set.
13. The projection exposure apparatus according to claim 11, wherein 14. The pair of prisms are located at positions of the respective regions.
The interval is adjusted when the position is changed.
A projection exposure apparatus according to any one of claims 11 to 13. 15. An illumination device for irradiating a mask with illumination light from a light source.
A bright optical system and a pattern image of the mask on a substrate.
A projection exposure apparatus provided with a projection optical system, comprising: a light source;
And substantially the same as the pupil plane of the projection optical system.
Of the illumination light on a predetermined surface in the illumination optical system conjugate to
The light amount distribution is divided into a plurality of areas decentered from the optical axis of the illumination optical system.
Optical system that makes the light amount distribution variable while increasing the
Wherein the optical system is provided for each of the regions on the predetermined surface.
In order to adjust the position, the position of the illumination optical system with respect to the optical axis direction is adjusted.
A pair of prisms whose intervals are variable.
Projection exposure apparatus. 16. The pair of prisms are arranged on the predetermined surface.
The interval is set in accordance with the position of each of the regions.
A projection according to any one of claims 11 to 15, characterized in that:
Exposure equipment. 17. The method according to claim 17, wherein the pair of prisms are arranged on the predetermined surface.
Each of the above-described regions is arranged in a radial direction with the optical axis of the illumination optical system as a center.
17. The method according to claim 11, wherein the region is moved.
The projection exposure apparatus according to claim 1. 18. The method according to claim 18, wherein the pair of prisms are mounted on the substrate.
Of the illumination optical system with respect to the periodic direction of the pattern to be captured
Move each area so that the distance from the optical axis is changed
The method according to any one of claims 11 to 17, wherein
Projection exposure apparatus. 19. The illumination optical system according to claim 19, wherein the pair of prisms includes :
Distance between the optical axis can be maintained equally crucible ho in the plurality of regions of
Moving each of the areas so as to be changed while changing
The projection dew according to any one of claims 11 to 18, wherein
Light device. 20. At least different fineness on the substrate
When transferring each pattern, the pair of prisms
The illumination optics according to the fineness of each pattern
The distance from the optical axis of the system is set approximately equal in the plurality of regions.
Moving each of the areas so that
Item 20. The projection exposure apparatus according to any one of Items 11 to 19. 21. A pair of prisms each having an incident surface.
One of the exit surfaces is inclined with the optical axis of the illumination optical system at the apex.
And the other is a plane substantially perpendicular to the optical axis.
The method according to any one of claims 11 to 20, wherein
Projection exposure apparatus. 22. A pattern to be transferred onto the substrate is a first pattern.
When including a periodic structure in the direction, the plurality of regions may
According to the fineness of the pattern in the first direction,
The distance from the optical axis of the illumination optical system in the first direction is substantially
22. The method according to claim 10, wherein:
The projection exposure apparatus according to claim 1. 23. The pattern is orthogonal to the first direction.
When including a periodic structure in the second direction, the plurality of regions
According to the fineness of the pattern in the second direction
The distance from the optical axis of the illumination optical system in the second direction
Is set substantially equal.
The projection exposure apparatus according to claim 1. 24. The pattern to be transferred onto the substrate is a first pattern.
When including a periodic structure in the direction, the plurality of regions may
Crosses the optical axis of the illumination optical system on the predetermined surface, and
A first axis defined along a second direction orthogonal to the first direction
24. The method according to claim 10, wherein:
The projection exposure apparatus according to any one of the above. 25. The pattern is also periodic in the second direction.
When including the structure, the plurality of regions, the first axis,
The optical axis of the illumination optical system is orthogonal to the first axis, and
It is delimited by a second axis defined along a first way direction
And the distance from the optical axis in the second direction is
25. The method according to claim 24, wherein the values are set substantially equal.
Projection exposure apparatus. 26. A pattern to be transferred onto the substrate is a first pattern.
When including a periodic structure in the direction, the plurality of regions may
Substantially parallel to a second direction orthogonal to the first direction, and
The distance according to the fineness of the pattern in the first direction
A pair of light sources separated from the optical axis of the illumination optical system in the first direction;
11. The display device according to claim 10, wherein the first line segment is arranged on the first line segment.
The projection exposure apparatus according to any one of claims 25 to 25. 27. The pattern is also periodic in the second direction.
When including the structure, the plurality of regions, the first direction and
Substantially parallel, and of the pattern in the second direction.
The distance from the optical axis of the illumination optical system is a distance corresponding to the degree of fineness.
A pair of second line segments separated in a second direction, and the pair of first line segments;
3. The image display device according to claim 2, wherein the plurality of line segments are arranged on each line segment.
7. The projection exposure apparatus according to 6. 28. The plurality of regions include the pair of first line segments.
And a pair of the second line segments.
28. The projection exposure apparatus according to claim 27. 29. The light quantity distribution is such that two diffracted lights having different orders generated from the pattern of the mask by irradiation of light emitted from the center of each of the regions are formed on an optical axis on a pupil plane of the projection optical system. 29. The projection exposure apparatus according to claim 10, wherein the position of each of the regions is determined so as to pass through a position having a distance substantially equal to the distance. 30. The projection exposure apparatus according to claim 29, wherein the two diffracted lights are one of ± n order diffracted lights and a 0 order diffracted light. 31. An angle of incidence of light emitted from the center of each of the regions to the mask, θm a diffraction angle of ± n-order diffracted light generated from a pattern of the mask, and a mask-side opening of the projection optical system. when the number and NA _R, claim 10, characterized in that the resolution limit of the projection optical system when said ± n one by sin-order diffracted light (θm-ψ) = NA _R the relationship is satisfied 30. The projection exposure apparatus according to claim 30. 32. The light quantity distribution is such that, when the wavelength of the illumination light is λ and the pattern pitch of the mask is P, the incident angle 光 of the light emitted from the center of each area to the mask is sinψ = λ / The position of each said area | region is determined so that the relationship of 2P may be satisfy | filled, 4-10 characterized by the above-mentioned.
The projection exposure apparatus according to claim 1. 33. Before light emitted from the center of each of the regions.
The incident angle on the mask is ψ, the wavelength of the illumination light is λ,
If the number of mask-side numerical aperture of the projection optical system is NA _R, the group
The minimum pitch of a pattern that can be transferred onto a plate is λ / (NA _R +
(sin の).
The projection exposure apparatus according to claim 1. 34. The wavelength of said illumination light is λ, said projection optical system
When the number of the mask-side opening and NA _R, pattern of the mask
Contains periodic structures with a pitch smaller than λ / NA _R
The method according to any one of claims 10 to 33, wherein
Projection exposure apparatus. 35. A pattern to be transferred onto the substrate is a first pattern.
And a periodic structure in each of the second directions, the light amount distribution is based on the 0th-order diffracted light generated from the pattern of the mask by irradiation of light emitted from the center of each region, and the 0th-order diffracted light as a center. One of the higher-order diffracted lights distributed in the first direction and one of the higher-order diffracted lights distributed in the second direction with the zero-order diffracted light as a center are substantially equal to the optical axis on the pupil plane of the projection optical system. 35. The projection exposure apparatus according to claim 10, wherein the position of each of the regions is determined so as to be distributed in a distance. 36. A ratio of a numerical aperture of light emitted from each of the regions to a numerical aperture on the mask side of the projection optical system is 0.1 to 0.5.
36. The number is set to about three.
The projection exposure apparatus according to any one of the above. 37. The light quantity distribution, wherein the light quantity centroid is the illumination.
2. The optical system according to claim 1, wherein the optical axis substantially coincides with the optical axis of the optical system.
The projection exposure apparatus according to any one of 0 to 36. 38. The plurality of regions are m (m is a natural number).
A first area and the m number of optical axes of the illumination optical system;
The first region and m second regions arranged substantially symmetrically.
Only, each of the first regions is generated from the pattern of the mask.
Pupil plane of the projection optical system
The position is determined to be distributed approximately equidistant from the optical axis above.
The method according to any one of claims 10 to 37, wherein
3. The projection exposure apparatus according to claim 1. 39. During exposure of the substrate by the illumination light,
4. A driving unit for relatively moving the substrate and the image plane of the projection optical system in an optical axis direction.
9. The projection exposure apparatus according to claim 8. 40. A method for forming a semiconductor element, comprising a step of transferring a circuit pattern onto a wafer using the projection exposure apparatus according to claim 1. Description: