JPH04225514A - Projection-type aligner - Google Patents

Abstract

PURPOSE:To improve the resolution and the focus depth at projection exposure of a circuit pattern, etc. CONSTITUTION:The illuminating luminous flux from a light source 1 is applied on an reticle 16 through a plurality of fly's-eye lens groups 11A, 11B, 11C, and 11D being separated from each other, and a reticule pattern 17 is projected and imaged on a wafer (photosensitive substrate) 20 by a projecting optical system 18. Each emission end side 11b of the fly's-eye lens groups 11A-11D is conjugated with the pupil 19 of the projecting optical system 18, and the center of each fly's-eye lens group 11A-11D is provided movably at the position eccentric from the optical axis AX. High resolution and large focus depth promotion can be accomplished, and also the uniformity of the distribution of the illuminance on the reticule can favorably be maintained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus used for transferring circuit patterns of semiconductor integrated devices or the like or patterns of liquid crystal devices.

0002

2. Description of the Related Art Forming circuit patterns for semiconductors and the like generally requires a process called photolithography. This step typically involves transferring a reticle (mask) pattern onto a sample substrate such as a semiconductor wafer. A photosensitive photoresist is coated on the sample substrate, and a circuit pattern is transferred to the photoresist according to the irradiation light image, that is, the pattern shape of the transparent portion of the reticle pattern. In a projection exposure apparatus, a circuit pattern drawn on a reticle to be transferred is projected and imaged onto a sample substrate (wafer) via a projection optical system.

[0003] Further, an optical integrator such as a fly's eye lens or fiber is used in an illumination optical system for illuminating the reticle, and the intensity distribution of the illumination light irradiated onto the reticle is made uniform. In order to achieve optimal uniformity, when a fly-eye lens is used, the reticle-side focal plane and the reticle plane are connected through a nearly Fourier transform relationship, and the reticle-side focal plane and the light source-side focal plane are also connected. They are connected by Fourier transform. Therefore, the pattern surface of the reticle and the light source side focal plane of the fly's eye lens (more precisely, the light source side focal plane of each lens of the fly's eye lens) are connected in an imaging relationship (conjugate relationship). Therefore, on the reticle, the illumination light from each element (secondary light source image) of the fly-eye lens is added (superimposed) and averaged, making it possible to improve the uniformity of illumination on the reticle. It has become.

In a conventional projection exposure apparatus, the light intensity distribution of the illumination light beam incident on the entrance surface of an optical integrator such as the above-mentioned fly's eye lens is distributed within a substantially circular (or rectangular) center around the optical axis of the illumination optical system. I tried to make it almost uniform. FIG. 13 shows the above-mentioned conventional projection optical system, in which the illumination light flux L130 of the reticle 16 is transmitted to the reticle pattern 1 via the fly's eye lens 11, the spatial filter 12, and the condenser lens 15 in the illumination optical system.
7. Here, the spatial filter 12 is a reticle-side focal plane 11b of the fly-eye lens 11, that is, a Fourier transform plane (hereinafter abbreviated as pupil plane) for the reticle 16.
, or located near it, and the optical axis AX of the projection optical system
It has an aperture with an approximately circular area centered at , and limits the 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 17 of the reticle 16 is imaged onto the resist layer of the wafer 20 via the projection optical system 18. Here, the solid line representing the luminous flux represents the chief ray of light emitted from one point.

At this time, the illumination optical system (11, 12, 15)
The ratio of the numerical aperture of the projection optical system 18 to the reticle-side numerical aperture of the projection optical system 18, the so-called σ value, is determined by the aperture stop (for example, the aperture diameter of the spatial filter 12), and the value is generally about 0.3 to 0.6. be. The illumination light L130 is diffracted by a pattern 17 patterned on the reticle 16, and the pattern 17 generates 0th-order diffracted light D0, +1st-order diffracted light DP, and -1st-order diffracted light Dm. Each diffracted light (D0,
Dm, DP) are focused by the projection optical system 18 and generate interference fringes on the wafer (sample substrate) 20. This interference fringe is an image of the pattern 17. At this time, the 0th order diffracted light D0
The angle θ (on the reticle side) formed by the ±1st-order diffracted lights DP and Dm is determined by sin θ=λ/P (λ: exposure wavelength, P: pattern pitch).

As the pattern pitch becomes finer, sin θ increases, and when sin θ becomes larger than the numerical aperture (NAR) on the reticle side of the projection optical system 18, the ±1st-order diffracted light DP
, Dm cannot pass through the projection optical system. At this time, only the 0th order diffracted light D0 reaches the wafer 20, and no interference fringes are generated. In other words, when sin θ>NAR, an image of the pattern 17 cannot be obtained and the pattern 17 cannot be transferred onto the wafer 20.

From the above, in conventional exposure apparatuses, the pitch P such that sin θ=λ/P≈NAR is given by the following equation. P≒λ/NAR (1) Since the minimum pattern size is half the pitch P, the minimum pattern size is about 0.5·λ/NAR, but in actual photolithography, wafer curvature and wafer distortion due to the process A certain depth of focus is required due to effects such as steps or the thickness of the photoresist itself. Therefore, the practical minimum resolution pattern size is k・λ/NA
It is expressed as Here, k is called a process coefficient and is 0.
It will be about 6 to 0.8. The ratio of the reticle-side numerical aperture NAR to the wafer-side numerical aperture NAW is the same as the imaging magnification of the projection optical system, so the minimum resolution pattern size on the reticle is k・λ/NAR, and the minimum pattern size on the wafer is k・λ/NAW =k・λ/B・NAR (
However, B is the imaging magnification (reduction ratio).

Therefore, in order to transfer a finer pattern, it is necessary to choose between using an exposure light source with a shorter wavelength or using a projection optical system with a larger numerical aperture. Of course, efforts to optimize both wavelength and numerical aperture are also conceivable. Also, the phase of the transmitted light from a specific part of the transmitted part of the circuit pattern of the reticle can be determined by
A so-called phase shift reticle that shifts the phase of transmitted light from other transmitting portions by π has been proposed in Japanese Patent Publication No. 50811/1983. By using this phase shift reticle, it is possible to transfer finer patterns than before.

[0009]

[Problems to be Solved by the Invention] However, in conventional exposure apparatuses, it is difficult to make the illumination light source have a shorter wavelength than the current one (for example, 200 nm or less) because there is no suitable optical material that can be used as a transmissive optical member. This is currently difficult for several reasons. Furthermore, the numerical aperture of the projection optical system is already close to its theoretical limit at present, and it is almost impossible to increase the aperture further.

[0010] Furthermore, even if it is possible to make the aperture larger than the current one, the depth of focus expressed by ±λ/2NA2 will rapidly decrease as the numerical aperture increases, and the depth of focus required for actual use will decrease. The problem of decreasing numbers is becoming more and more obvious. On the other hand, with respect to phase shift reticles, many problems remain, such as the complicated manufacturing process and high cost, and the methods for inspection and repair that have not yet been established.

The present invention has been made in view of the above problems, and an object of the present invention is to realize a projection type exposure apparatus that can obtain high resolution and a large depth of focus even when using a normal reticle.

0012

[Means for Solving the Problems] A projection type exposure apparatus according to the present invention is constructed as shown in FIG. 12 in principle. In FIG. 12, members that are the same as in the prior art are given the same reference numerals. In FIG. 12, fly-eye lenses (11A, 11
B), the reticle side focal plane 11b is the reticle 1
Approximately the position of the Fourier transform plane (pupil plane 19 of the projection lens 18) with respect to the circuit pattern (reticle pattern) 17 on 6
The fly's eye lenses (11A, 11B) are arranged in a dispersed manner into a plurality of fly's eye lens groups. In addition, the illumination light amount distribution at the reticle side focal plane 11b of the fly-eye lenses 11A, 11B is
In order to make the light almost zero except for the individual fly-eye lens positions 11B, a light shielding member 10 is placed on the light source side of the fly-eye lens.
will be established. Therefore, the illumination light amount distribution on the reticle-side focal plane 11b of the fly-eye lenses 11A, 11B exists only at the positions of each fly-eye lens group 11A, 11B, and becomes almost zero at other locations.

Since the reticle-side focal plane 11b of the fly-eye lens groups 11A and 11B is approximately equal to the Fourier transform plane for the reticle pattern 17, the fly-eye lens group 1
1A, 11B at the reticle side focal plane 11b (
The positional coordinates of the luminous flux) correspond to the incident angle ψ of the illumination luminous flux with respect to the reticle pattern 17. Therefore, the reticle pattern 17 is
It is possible to adjust the angle of incidence of the illumination light beam incident on the illumination beam.

Here, the fly eye lens groups 11A, 11
B is preferably arranged symmetrically with respect to the optical axis AX, and each fly's eye lens group is composed of at least one lens element. Furthermore, in the present invention, since the fly-eye lens groups 11A and 11B are configured to be movable independently in the in-plane direction perpendicular to the optical axis, it is possible to move and adjust the position of each fly-eye lens group. Accordingly, it is possible to arbitrarily control the angle of incidence of each irradiation light beam (a plurality of beams) incident on the reticle 16.

[0015]

[Operation] The circuit pattern 17 drawn on the reticle (mask) generally includes many periodic patterns. Therefore, from the reticle pattern 17 irradiated with the illumination light from one fly-eye lens group 11A, the 0th-order diffracted light component D0, the ±1st-order diffracted light components DP, Dm, and the higher-order diffracted light components are reflected in the fineness of the pattern. Occurs in the corresponding direction.

At this time, since the illumination light beam (principal ray) is incident on the reticle 16 at an inclined angle, the generated diffracted light components of each order also have an inclination (angular deviation) compared to when the illumination is perpendicular. It is generated from the reticle pattern 17. Illumination light L120 in FIG. 12 is incident on the reticle 16 at an angle of ψ with respect to the optical axis. The illumination light L120 is diffracted by the reticle pattern 17, and becomes 0th-order diffracted light D0 that travels in a direction tilted by ψ with respect to the optical axis AX, +1st-order diffracted light DP tilted by θP with respect to the 0th-order diffracted light, and 0th-order diffracted light D0. -1st-order diffracted light D traveling at an angle of θm
generate m. However, since the illumination light L120 is incident on the reticle pattern at an angle ψ with respect to the optical axis AX of the projection optical system 18 which is telecentric on both sides,
The next diffracted light D0 also travels in a direction inclined by an angle ψ with respect to the optical axis AX of the projection optical system.

Therefore, the +1st order light DP travels in the direction θP +ψ with respect to the optical axis AX, and the -1st order diffracted light Dm travels in the direction θm −ψ with respect to the optical axis AX. At this time, the diffraction angles θP and θm are respectively sin(θP +ψ)−sinψ=λ/P (2)
sin(θm −ψ)+ sinψ=λ/P (3)
It is.

Here, it is assumed that both the +1st-order diffracted light DP and the -1st-order diffracted light Dm are transmitted through the pupil 19 of the projection optical system 18. When the diffraction angle increases with the miniaturization of the reticle pattern 17, the +1st-order diffracted light DP traveling in the direction of the angle θP +ψ becomes unable to pass through the pupil 19 of the projection optical system 18. That is, sin(θP +ψ)>NA
It becomes a relationship of R. However, since the illumination light L120 is incident at an angle with respect to the optical axis AX, the −1st-order diffracted light Dm can enter the projection optical system 18 even at this diffraction angle. In other words, the relationship is sin(θm −ψ)<NAR.

Therefore, on the wafer 20, the 0th order diffracted light D0
Interference fringes are generated by the two beams of -1st-order diffracted light Dm and -1st-order diffracted light Dm. These interference fringes are images of the reticle pattern 17, and when the reticle pattern 17 has a 1:1 line-and-space pattern, the contrast is about 90% and the image of the reticle pattern 17 is applied to the resist coated on the wafer 20. Patterning becomes possible.

[0020] The resolution limit at this time is when sin (θm - ψ) = NAR (4), so NAR + sin ψ = λ/P P = λ/ (NAR + sin ψ) (5) can be transferred. This is the pitch of the minimum pattern on the reticle side.

As an example, let sinψ be 0.5×NAR
If it is determined in terms of degree, the minimum pitch of the pattern on the reticle that can be transferred is as follows.

On the other hand, as shown in FIG. 13, in the case of a conventional exposure apparatus in which the distribution of illumination light on the pupil 19 is within a circular region centered on the optical axis AX of the projection optical system 18, the resolution limit As shown in equation (1), P≒λ/NAR. Therefore, it can be seen that higher resolution than the conventional exposure apparatus can be achieved. Next, the reticle pattern is irradiated with exposure light at a specific incident direction and angle, and the 0th-order diffracted light component and 1st
The reason why the depth of focus also increases depending on the method of forming an imaged pattern on a wafer using the second-order diffraction light component will be explained.

As shown in FIG. 12, the wafer 20 is connected to the projection optical system 1.
If it matches the focal position (best imaging plane) of No. 8,
Each diffracted light beam that leaves one point in the reticle pattern 17 and reaches one point on the wafer 20 has the same optical path length no matter which part of the projection optical system 18 it passes through. Therefore, even when the 0th-order diffracted light component passes through the approximate center (near the optical axis) of the pupil plane 19 of the projection optical system 18 as in the conventional case, the optical path lengths of the 0th-order diffracted light component and other diffracted light components are equal. , the mutual wavefront aberration is also zero. However, when the wafer 20 is in a defocused state where it does not match the focal position of the projection optical system 18, the optical path length of the high-order diffracted light that is incident obliquely is in front of the focal point ( It is shorter in the direction away from the projection optical system 18), and longer in the direction behind the focal point (in the direction closer to the projection optical system 18), and the difference therebetween corresponds to the difference in incidence angle. Therefore, the 0th-order, 1st-order, etc. diffracted lights mutually form wavefront aberrations, resulting in blurring in front and behind the focal position.

The wavefront aberration due to the above-mentioned defocus is caused by the amount of deviation from the focal position of the wafer 20 being ΔF, and each diffracted light beam being -
The sine of the incident angle θw when it is incident on
θw), it is the amount given by ΔFr2/2. (At this time, r represents the distance of each diffracted light from the optical axis AX at the pupil plane 19. In the conventional projection exposure apparatus shown in FIG. 13, the 0th order diffracted light D0 passes near the optical axis AX. ,
r (0th order) = 0, while ±1st order diffracted light DP, Dm
is r (first order)=M·λ/P (M is the magnification of the projection optical system).

Therefore, the wavefront aberration due to defocusing of the 0th-order diffracted light D0 and the ±1st-order diffracted lights DP and Dm is ΔF・
M2(λ/P)2/2. On the other hand, in the projection exposure apparatus according to the present invention, as shown in FIG. The distance from r (0th order) = M・si
It is nψ.

On the other hand, the distance of the −1st order diffracted light component Dm from the optical axis on the pupil plane is r (−1st order)=M·sin(θm
−ψ). And at this time, sinψ=sin(
θm −ψ), the relative wavefront aberration due to defocus between the 0th-order diffracted light component D0 and the -1st-order diffracted light component Dm becomes zero, and even if the wafer 20 is slightly shifted from the focal position in the optical axis direction, the pattern 17 is This means that image blur will not be as large as in the past. That is, the depth of focus will increase. Also, as in equation (3), sin(θm −ψ)+
Since sin ψ = λ/P, if the angle of incidence ψ of the illumination light beam L120 on the reticle 16 is in the relationship sin ψ = λ/2P with respect to the pattern of pitch P, it is possible to greatly increase the depth of focus. be.

[0027]

Embodiment FIG. 1 shows a projection type exposure apparatus (stepper) according to a first embodiment of the present invention, in which a fly-eye lens group 11
A diffraction grating pattern 5 is provided as an optical member (part of the input optical system of the present invention) for concentrating the light intensity distribution of illumination light on the light source side focal plane 11a of each of A and 11B.

The illumination light flux generated by the mercury lamp 1 is focused on the second focal point f0 of the elliptical mirror 2, and then irradiated onto the diffraction grating pattern 5 via the mirror 3 and the lens system 4 such as a relay system. The illumination method at this time may be the Koehler illumination method or the critical illumination method, but the critical illumination method is more desirable in order to obtain a strong amount of light. The diffracted light generated from the diffraction grating pattern 5 is concentrated and incident on each of the fly's eye lens groups 11A and 11B by the relay lens 9. At this time, the fly eye lens groups 11A, 1
The light source side focal plane 11a of 1B and the diffraction grating pattern 5 have a substantially Fourier transform relationship via the relay lens 9. In FIG. 1, the illumination light to the diffraction grating pattern 5 is shown as a parallel light beam, but in reality it is a diverging light beam, so the fly-eye lens groups 11A and 11B
The incident light beam has a certain size (thickness).

On the other hand, fly-eye lens groups 11A and 11B
The reticle-side focal plane 11b is arranged in the in-plane direction perpendicular to the optical axis AX so as to substantially coincide with the Fourier transform plane (pupil conjugate plane) of the reticle pattern 17. Further, each of the fly-eye lens groups 11A and 11B is movable independently in the in-plane direction perpendicular to the optical axis AX, and is held by a movable member (position adjustment member of the present invention) that makes the fly-eye lens groups movable. , the details of which will be described later.

Individual fly-eye lens groups 11A, 11B
It is desirable that they have the same shape and the same material (refractive index). Further, each lens element of the individual fly-eye lens groups 11A and 11B shown in FIG. 1 is a biconvex lens, and an example in which the light source side focal plane 11a and the entrance plane coincide with the reticle side focal plane 11b and the exit plane, respectively. However, the fly's eye lens element does not need to strictly satisfy this relationship, and may be a plano-convex lens, a convex-plano lens, or a plano-concave lens.

Note that the light source side focal plane 1 of the fly-eye lens group
1a and the reticle side focal plane 11b are of course in a Fourier transform relationship. Therefore, in the example of FIG. 1, the reticle-side focal plane 11b of the fly-eye lens group, that is, the exit surface of the fly-eye lens groups 11A and 11B, is in an imaging relationship (conjugate) with the diffraction grating pattern 5. Now, the reticle-side focal plane 1 of the fly-eye lens groups 11A and 11B.
The light beam emitted from 1b passes through a condenser lens 13,
15. Illuminate the reticle 16 with a uniform illuminance distribution via the mirror 14. In this embodiment, fly eye lens group 1
A light shielding member 12 is disposed on the exit side of the beams 1A and 11B to cut off the 0th order diffracted light from the diffraction grating pattern 5. The light shielding member 12 is a metal plate with an opening cut out to match the fly's eye lens group, or a glass, quartz substrate, etc., on which an opaque material such as metal is patterned. The opening of the light shielding member 12 includes a fly eye lens group 11A, and a fly eye lens group 11A, respectively.
11B. For this reason, the illumination light intensity distribution near the reticle side focal plane 11b of the fly-eye lens groups 11A and 11B is
It can be set to zero at positions other than 1A and 11B.

Therefore, the illumination light that illuminates the reticle pattern 17 is only the luminous flux (luminous flux from the secondary light source image) emitted from each fly-eye lens group 11A, 11B, and therefore the angle of incidence on the reticle pattern 17 is is also restricted to only beams with specific angles of incidence. In the embodiment, since the fly-eye lens groups 11A and 11B are movable, the opening of the light shielding member 12 must also be movable, or the light shielding member 12 itself must be replaceable ( The light shielding member 12 will be described later).

The diffracted light generated from the reticle pattern 17 on the thus illuminated reticle 16 is focused and imaged by the telecentric projection optical system 18, as described in FIG. The image of pattern 17 is transferred. When diffracting the illumination light beam using the aforementioned diffraction grating pattern 5 and concentrating the diffracted light on a specific position (fly's eye lens group) within the light source side focal plane of the fly's eye lens groups 11A and 11B, The concentration position changes depending on the pitch and directionality of the diffraction grating pattern 5. Therefore, in order to concentrate the illumination light on the position of each fly's eye lens 11A, 11B, the diffraction grating pattern 5
determine the pitch and direction of the

Furthermore, as mentioned above, the fly eye lens 11
An image of the diffraction grating pattern 5 is formed on the reticle side focal plane 11b of the reticle side focal plane 11b, and the reticle pattern plane 17 and the reticle side focal plane 1 of the fly-eye lens groups 11A and 11B are formed.
1b is in a relationship with the Fourier transform plane, so that the illumination intensity distribution on the reticle 16 will not be made non-uniform due to defects in the diffraction grating pattern 5 or dust. Further, the diffraction grating pattern 5 itself does not form an image on the reticle 16 and deteriorate the illuminance uniformity. The diffraction grating pattern 5 may be formed by patterning a light-shielding film such as Cr on the surface of a transparent substrate, such as a glass substrate, or may be a so-called phase grating in which a dielectric film such as SiO2 is patterned. It may be. In the case of a phase grating, generation of zero-order diffracted light can be suppressed.

Furthermore, the diffraction grating pattern 5 may be not only a transparent pattern but also a reflective pattern. For example, a high reflectance film, that is, a metal film such as Al, or a dielectric multilayer film patterned in the shape of a diffraction grating may be used on the surface of a flat reflecting mirror made of glass. It may also be a high reflectance mirror whose steps are patterned in the shape of a diffraction grating.

When the diffraction grating pattern 5 is reflective, as shown in FIG. The diffracted light may be concentrated near the fly-eye lens groups 11A and 11B via the relay lens 9. Note that even when the individual fly-eye lens groups 11A and 11B move, the respective fly-eye lens groups 11A and 1
It is assumed that the diffraction grating pattern 5 or 5A can be replaced with one having a different pitch so that the illumination light can be concentrated near 1B. Furthermore, the diffraction grating pattern 5 or 5A may be rotatable in any direction within a plane perpendicular to the optical axis AX.

By doing this, the reticle pattern 17
The pitch direction of the line and space pattern inside is X,
It is also possible to deal with cases where the direction is different from the Y direction. Further, the relay lens 9 can be a zoom lens system (such as an afocal zoom expander) consisting of a plurality of lenses, and the focal length can be changed to change the light condensing position. However, at this time, the relationship between the diffraction grating pattern 5 or 5A and the light source side focal plane 11a of the fly's eye lens groups 11A and 11B should not be compromised.

Incidentally, FIG. 1 shows a main control system 50 that controls the apparatus in an integrated manner, and a bar code BC representing a name formed on the side of the reticle pattern 17 while the reticle 16 is being conveyed directly above the projection optical system 18. a barcode reader 52 that reads the information, a keyboard 54 that inputs commands and data from the operator, and fly-eye lens groups 11A, 11.
Drive system of movable parts that move B (motor, gear train, etc.)
56 are provided. In the main control system 50, the names of a plurality of reticles to be handled by this stepper and the operation parameters of the stepper corresponding to each name are registered in advance. The main control system 50 is a barcode reader 52.
When the camera reads the reticle barcode BC, information on the movement position (position within the pupil conjugate plane) of the fly-eye lens groups 11A and 11B registered in advance is sent to the drive system as one of the operating parameters corresponding to the name. 56. As a result, each fly-eye lens group 11A, 11B is
The position is adjusted as explained in the figure. The above operations can also be executed by the operator directly inputting commands and data to the main control system 50 from the keyboard 54.

The first embodiment has been described above, but
The optical member that concentrates the light intensity distribution on the light source side focal plane of the fly-eye lens group near the position of each fly-eye lens is not limited to the diffraction grating pattern 5 or 5A. In place of the reflective diffraction grating pattern 5A shown in FIG. 2, a movable plane mirror 6 is arranged as shown in FIG. 3, and a driving member 6a such as a motor for rotating the plane mirror 6 is provided. Then, if the plane mirror 6 is rotated or vibrated by the driving member 6a, the fly-eye lens groups 11A, 1
The light quantity distribution within the light source side focal plane (incident plane) 11a of 1B can be changed over time. If the plane mirror 6 is rotated to a plurality of appropriate angular positions during the exposure operation, the light intensity distribution within the light source side focal plane 11a of the fly-eye lens groups 11A and 11B can be adjusted to any one of the plurality of fly-eye lens groups.
The light can be concentrated only in the vicinity of the two fly-eye lens groups. Note that when using such a movable reflecting mirror 6, the relay lens system 9 may be omitted.

Furthermore, each fly-eye lens group 11A
, 11B move, the angular coordinates of the plurality of angular positions of the plane mirror 6 described above may be changed to concentrate the reflected light flux near the fly's eye lens group at the new position. By the way, although the light shielding member 12 shown in FIG. 3 is provided on the entrance surface side of the fly-eye lens groups 11A and 11B, it may be provided on the exit surface side as in FIG.

FIG. 4 shows an optical fiber bundle 7 as an optical member for converging the illumination light flux on each of the fly's eye lens groups.
It is a schematic diagram when using. Figure 1 shows the side of the light source from the relay lens system 4 and the side of the reticle from the fly-eye lens group 11.
Assume that it has the same configuration as . Illumination light generated from the light source and transmitted through the relay lens system 4 is adjusted to have a predetermined numerical aperture (NA) and enters the entrance portion 7a of the optical fiber bundle 7. The optical fiber bundle 7 is divided into a plurality of bundles corresponding to the number of fly-eye lens groups while reaching the emission part 7b, and each emission part 7b is arranged near the light source side focal plane 11a of the fly-eye lens groups 11A and 11B. It is arranged so as to be integrated with each fly-eye lens group. Further, at this time, a lens (for example, a field lens) may be provided between each emission part 7b of the optical fiber bundle 7 and the fly-eye lens group 11, and the lens may be used to
The light source side focal plane 11a of the optical fiber 1 and the light exit surface of the optical fiber exit section 7b may be in a Fourier transform relationship.

Furthermore, each injection section 7b (or the lens between the injection section 7b and the fly's eye lens group 11b) is rotated one-dimensionally or two-dimensionally within a plane perpendicular to the optical axis by a driving member such as a motor. If movable, each fly-eye lens group 11
Even when A and 11B move, the illumination light flux can be concentrated near the position of each fly-eye lens group after the movement.

FIG. 5 shows an example in which a prism 8 having a plurality of refractive surfaces is used as an optical member for concentrating the illumination light flux on each fly's eye lens group. The prism 8 in FIG. 5 has an optical axis A
It is divided into two refractive surfaces with X as the boundary, and the optical axis A
Illumination light incident above X is refracted upward and optical axis AX
Illumination light incident further downward is refracted downward. Therefore, the light source side focal plane 1 of the fly-eye lens groups 11A and 11B
Illumination light can be concentrated near the individual fly-eye lens groups 11A and 11B on 1a according to the refraction angle of the prism 8.

The number of divisions of the refractive surface of the prism 8 is not limited to two, but may be divided into any number of surfaces depending on the number of fly-eye lens groups. Furthermore, the divisional positions do not have to be symmetrical with respect to the optical axis AX. By replacing the prism 8, individual fly-eye lens groups 1
Even if lenses 1A and 11B move, the illumination light can be accurately focused on the positions of the respective fly-eye lens groups 11A and 11B.

Further, the prism 8 at this time may be a polarizing light splitter such as a Wollaston prism. However, in this case, since the polarization directions of the divided light beams are different, it is better to take into account the polarization characteristics of the resist of the wafer 20 and align the polarization characteristics in one direction. In addition, in place of the prism 8, a reflecting mirror with a plurality of reflecting surfaces at different angles is used as shown in Fig. 3.
If arranged like this, the driving member 6a becomes unnecessary. Needless to say, it is good to have a function for replacing the prism etc. in the apparatus. Also, when such a prism or the like is used, the relay lens system 9 can be omitted.

FIG. 6 shows a plurality of mirrors 8a, 8b,
This is an example using 8c and 8d. The illumination light transmitted through the relay lens system 4 is reflected by the primary mirrors 8b and 8c so as to be separated into two directions, guided to the secondary mirrors 8a and 8d, and reflected again to the light source of the fly-eye lens group 11. It reaches the side focal plane 11a. If each mirror 8a, 8b, 8c, 8d is provided with a position adjustment mechanism and a rotation angle adjustment mechanism around the optical axis AX, each fly-eye lens group 11A, 11
Even after moving B, the illumination light flux can be concentrated in the vicinity of each of the fly-eye lenses 11A and 11B. Furthermore, each of the mirrors 8a, 8b, 8c, and 8d may be a plane mirror, a convex mirror, or a concave mirror.

Further, a lens may be provided between each of the secondary mirrors 8a, 8d and the fly's eye lens group 11.
In FIG. 6, primary mirrors 8b, 8c, secondary mirrors 8a, 8
Although two mirrors are provided for each of the mirrors d, the number is not limited to this, and the mirrors may be appropriately arranged depending on the number of fly-eye lens groups. In each of the above embodiments, the number of fly-eye lens groups is two, but it goes without saying that the number of fly-eye lens groups may be three or more. Regarding the optical components that concentrate the illumination light on each fly-eye lens group, we have mentioned that the light is mainly concentrated in two places, but the illumination light can be concentrated in multiple positions depending on the number of fly-eye lens groups. Needless to say, it's a shame. In all of the above embodiments, it is possible to concentrate the illumination light at an arbitrary position (corresponding to the position of the fly's eye lens group). Further, the optical member for concentrating illumination light on each fly's eye lens group is not limited to the type mentioned in the embodiment, and may be of any other type.

Further, the light shielding member 12 has a structure as shown in FIG. 12 described above.
It may be replaced with the light shielding member 10 provided near the light source side focal plane 11a of the fly-eye lens, or the light shielding member 10 shown in FIG. 12 may be used in combination with each of the embodiments shown in FIGS. 1 to 5. You may do so. Moreover, the light shielding members 10 and 12 are
Although it can be placed at any arbitrary position, not limited to the reticle-side focal plane 11b of the fly-eye lens group or the light source-side focal plane 11a, a suitable location is, for example, between the two focal planes 11a and 11b. be.

Furthermore, the individual fly-eye lens groups 11A,
The optical member that concentrates the illumination light only in the vicinity of the reticle 11B is for preventing loss of the amount of illumination light illuminating the reticle 16, and is used to achieve high resolution and a large depth of focus, which are the characteristics of the projection exposure apparatus of the present invention. It is not directly related to the configuration for obtaining the effect. Therefore, the optical member may be a lens system having a large diameter enough to allow illumination light to enter the flood of each fly's eye lens group after position adjustment.

FIG. 7 is a diagram showing the configuration of a projection exposure apparatus according to another embodiment of the present invention, and the mirror 14, condenser lens 15, reticle 16, and projection optical system 18 are shown in FIG.
It is similar to Also, fly eye lens groups 11A and 11B
The light source side has one of the configurations shown in FIGS. 1 to 5 described above or FIG. 12. A light shielding member 12a having an arbitrary opening (transmission part) is provided near the reticle-side focal plane 11b of the fly-eye lens groups 11A and 11B,
The illumination light flux emitted from the fly-eye lens groups 11A and 11B is restricted.

Since the Fourier transform of the reticle-side focal plane 11b of the fly-eye lens group 11 with respect to the relay lens 13a becomes a conjugate plane with the reticle pattern 17, a variable field stop (reticle blind) 13d is provided here. Then, it is Fourier-transformed again by the relay lens 13b and reaches the conjugate plane (Fourier plane) 12b of the reticle-side focal plane 11b of the fly-eye lens group 11. The aforementioned light shielding member 12a may be provided on this Fourier plane 12b.

The illumination light flux from each fly-eye lens group 11A, 11B is further transmitted to condenser lenses 13C, 15,
It is guided to a reticle 16 by a mirror 14. It should be noted that if the system is such that the illumination light beam incident on each fly's eye lens group 11A, 11B can be effectively concentrated only there, there is no problem even if the light shielding member is not provided at the position 12a or 12b. Even in this case, the field diaphragm (reticle blind) 1
3D can be used.

In any of the above embodiments, the diameter of each opening of the light shielding members 10, 12, 12a (or the area of each exit end of the fly-eye lens group) is the diameter of each opening of the light shielding members 10, 12, 12a. It is desirable that the ratio of the numerical aperture for the reticle 16 to the reticle-side numerical aperture (NAR) of the projection optical system 18, the so-called σ value, be set to about 0.1 to 0.3. When the σ value is smaller than 0.1, the pattern fidelity of the transferred image deteriorates, and when it is larger than 0.3, the effect of improving resolution and increasing the depth of focus becomes weak.

In addition, in order to satisfy the σ value condition (approximately 0.1<σ<0.3) determined by one of the fly-eye lens groups, the area of the exit end of each fly-eye lens group 11A, 11B is increased. The size (size in the in-plane direction perpendicular to the optical axis) may be determined according to the illumination light flux (emission light flux). In addition, a variable aperture stop (equivalent to the light shielding member 12) is provided near the reticle-side focal plane 11b of each fly-eye lens group 11A, 11B, so that the numerical aperture of the light beam from each fly-eye lens group can be varied. , the σ value may be changed. In addition, by providing a variable aperture diaphragm (NA limiting diaphragm) near the pupil (entrance pupil or exit pupil) 19 in the projection optical system 18, the NA and σ value of the projection system can be further optimized. .

[0055] Furthermore, the light beam incident on each fly-eye lens group is illuminated widely to a certain extent outside the entrance end face of each fly-eye lens group, and the distribution of the amount of light incident on each fly-eye lens group is uniform. It is preferable if there is one, since the uniformity of illuminance on the reticle pattern surface can be further improved. Next, an example of a movable part that moves the fly's eye lens group will be described with reference to FIGS. 8 and 9.

FIG. 8 is a diagram of the movable portion viewed from the optical axis direction, and FIG. 9 is a diagram viewed from the direction perpendicular to the optical axis. In FIG. 8, four fly-eye lens groups 11A, 11B, 11C, and 11D are arranged as a plurality of fly-eye lens groups at approximately equal distances from the optical axis. In addition, fly eye lens groups 11A, 1
Each of 1B, 11C, and 11D is 3 as shown in FIG.
Although it is composed of two lens elements, it is not limited to this, and in extreme cases, a fly-eye lens group may be composed of one lens element. Now, in FIGS. 8 and 9, fly-eye lens groups 11A and 11B
, 11C, 11D are jigs 80A, 80B, 80C, 80
These jigs 80A, 80B, 80C
, 80D further includes support rods 70A, 70B, 70C, 70
It is supported by movable members 71A, 71B, 71C, and 71D via D. These support rods 70A, 70B, 70C,
70D can be expanded and contracted in the optical axis direction by drive elements such as motors and gears included in movable members 71A, 71B, 71C, and 71D. In addition, movable members 71A and 71B
, 71C, 71D themselves are also fixed guides 72A, 72B,
72C, 72D, and therefore the individual fly-eye lens groups 11A, 11B, 11C, 11D are movable independently in the in-plane direction perpendicular to the optical axis.

Each position (in a plane perpendicular to the optical axis) of the fly-eye lens groups 11A, 11B, 11C, and 11D shown in FIGS. 8 and 9 is determined according to the reticle pattern to be transferred ( change) is better. As described in the section on operation, the position determination method in this case is such that the illumination light flux from each fly-eye lens group has the effect of improving the resolution and depth of focus that is optimal for the fineness (pitch) of the pattern to be transferred. What is necessary is to set the position (incident angle ψ) at which the light is incident on the reticle pattern so that Next, specific examples of position determination for each fly-eye lens group are shown in FIGS. 10, 11(A), (B), and (C).
, (D). FIG. 10 is a diagram schematically showing the portion from the fly-eye lens groups 11A and 11B to the reticle pattern 17, and the reticle-side focal plane 11b of the fly-eye lens group 11 coincides with the Fourier transform plane 12c of the reticle pattern 17. ing. Further, at this time, a lens or a lens group that brings the two into a Fourier transform relationship is represented as a single lens 15. Furthermore, it is assumed that the distance from the fly-eye lens-side principal point of the lens 15 to the reticle-side focal plane 11b of the fly-eye lens group 11 and the distance from the reticle-side principal point of the lens 15 to the reticle pattern 17 are both f.

FIGS. 11(A) and 11(C) both show examples of a partial pattern formed in the reticle pattern 17, and FIG. 11(B) shows an example of a partial pattern formed in the reticle pattern 17. Fig. 11(D) shows the position of the center of the optimum fly-eye lens group on the Fourier transform plane (or pupil plane of the projection optical system), and Fig. 11(D) shows the optimum position of each fly-eye lens in the case of the reticle pattern of Fig. 11(C). FIG. 3 is a diagram showing the position of the groups (the optimal position of the center of each fly-eye lens group).

FIG. 11A shows a so-called one-dimensional line-and-space pattern, in which transmitting parts and light-blocking parts are arranged in a band shape with equal width in the Y direction, and they are arranged at a pitch P in the X direction.
are arranged regularly. At this time, the optimal position of each fly-eye lens group is on the line segment Lα and the line segment Lβ in the Y direction assumed in the Fourier transform plane, as shown in FIG. 11(B).
Any position above. FIG. 11(B) is a diagram of the Fourier transform surface 12c (11b) for the reticle pattern 17 viewed from the optical axis AX direction, and the coordinate system X, Y within the surface 12c is the same as that for the reticle pattern 17 viewed from the same direction. It is the same as FIG. 11(A). Now, in FIG. 11(B), the distances α and β from the center C through which the optical axis AX passes to each line segment Lα and Lβ are α=β, and when λ is the exposure wavelength, α=β=f・( 1/2)・(λ/P). If these distances α and β are expressed as f・sinψ, then sinψ=λ
/2P, which is consistent with the numerical value stated in the section of the effect. Therefore, if the center of each fly-eye lens group (the center of gravity of the light intensity distribution of the secondary light source image created by each fly-eye lens group) is on the line segments Lα and Lβ, then FIG.
For the line and space pattern shown in (A), the 0 generated by the illumination light from each fly's eye lens
The two diffracted lights, either the second-order diffracted light or the ±1st-order diffracted light, pass through positions on the projection optical system pupil plane 19 that are approximately equidistant from the optical axis AX. Therefore, as described above, the depth of focus for the line and space pattern (FIG. 11(A)) can be maximized and high resolution can be obtained.

Next, FIG. 11C shows a case where the reticle pattern is a so-called isolated space pattern, and the pitch of the pattern in the X direction (lateral direction) is Px, the pitch in the Y direction (
(vertical direction) pitch is Py. FIG. 11(D) is a diagram showing the optimal position of each fly-eye lens group in this case, and the positional and rotational relationship with FIG. 11(C) is shown in FIG. 11(A).
, (B). As shown in FIG. 11(C), 2
When illumination light is incident on a dimensional pattern, diffracted light is generated in a two-dimensional direction according to the two-dimensional periodicity (X: Px, Y: Py) of the pattern. Even in a two-dimensional pattern as shown in FIG. 11(C), either one of the 0th-order diffracted light and the ±1st-order diffracted light in the diffracted light is approximately equidistant from the optical axis AX on the projection optical system pupil plane 19. In this way, the depth of focus can be maximized. In the pattern of Figure 11(C),
Since the pitch in the direction is Px, as shown in FIG. 11(D), the line segment L where α=β=f・(1/2)・(λ/Px)
If the center of each fly-eye lens group is located on α and Lβ, the depth of focus can be maximized for the X-direction component of the pattern. Similarly, γ=ε=f・(1/2)・(λ/P
If the center of each fly-eye lens group is located on the line segments Lγ and Lε corresponding to y), the depth of focus can be maximized for the Y-direction component of the pattern.

As described above, when the illumination light flux from the fly's eye lens group arranged at each position shown in FIG. Either the diffracted light component DR or the -1st-order diffracted light component Dm passes through an optical path that is approximately equidistant from the optical axis AX on the pupil plane 19 in the projection optical system 18. Therefore, as described in the operation section, a projection type exposure apparatus with high resolution and a large depth of focus can be realized. In the above, only the two examples shown in FIGS. 11(A) and 11(C) were considered as the reticle pattern 17, but we focused on the periodicity (fineness) of other patterns as well. Two light beams of either the order diffracted light component or the -1st order diffracted light component and the 0th order diffracted light component are aligned on the optical axis AX at the pupil plane 19 in the projection optical system.
The center of each fly-eye lens group may be placed at a position such that the optical path passes approximately equidistant from the center of the fly-eye lens group. Also, Figure 11(A)
, (C) pattern example has the ratio of the line part to the space part (
Since the pattern had a duty ratio (duty ratio) of 1:1, the ±1st-order diffracted light was strong among the generated diffracted lights. For this reason, ±
We focused on the positional relationship between one of the 1st-order diffracted lights and the 0th-order diffracted light, but if the pattern differs from the duty ratio of 1:1, other diffracted lights, for example, one of the ±2nd-order diffracted lights and the 0th-order diffracted light. The positional relationship may be such that the projection optical system pupil plane 19 is approximately equidistant from the optical axis AX.

Furthermore, the reticle pattern 17 is shown in FIG.
), a specific one
When focusing on the two 0th-order diffracted light components, on the pupil plane 19 of the projection optical system, there are first-order and higher-order diffracted light components distributed in the X direction (first direction) centered on the one 0th-order diffracted light component, and Y There may be first-order or higher-order diffracted light components distributed in the direction (second direction). Therefore, if a two-dimensional pattern is to be imaged well with respect to one particular zero-order diffracted light component, one of the higher-order diffraction light components distributed in the first direction and one of the higher-order diffraction light components distributed in the second direction. A specific 0th-order diffracted light component (
All you have to do is adjust the position of one fly-eye lens group. For example, the center position of the fly's eye lens in FIG. 11(D) may be made to coincide with any one of points Pζ, Pη, Pκ, and Pμ. The points Pζ, Pη, Pκ, and Pμ are all located on the line segment Lα or Lβ (the optimal position for the periodicity in the X direction, that is, one of the 0th-order diffracted light and the ±1st-order diffracted light in the Since this is the intersection of the line segments Lγ and Lε (the optimal position for the periodicity in the Y direction), the light source position is optimal for both the X and Y pattern directions. be.

[0063] In the above, it is assumed that the two-dimensional pattern is a pattern having two-dimensional directionality at the same location on the reticle, but if there are multiple patterns having different directionality at different positions on the same reticle pattern. The above method can also be applied. If the pattern on the reticle has multiple directions or fineness,
The optimal position of the fly's eye lens group corresponds to each directionality and fineness of the pattern as described above, or the fly's eye lens group may be arranged at an average position of each optimal position. Further, this average position may be a weighted average that is weighted according to the degree of fineness and importance of the pattern.

An example of determining the position of a plurality of fly-eye lens groups has been described above, and the illumination light beam is directed to each fly-eye lens group by the aforementioned optical member (diffraction grating pattern, movable mirror, prism, fiber, etc.). Although the beams are concentrated in accordance with the moving position, it is not necessary to provide an optical member for such concentration. Furthermore, the light beams emitted from each fly-eye lens group are incident on the reticle at an angle. At this time, if the direction of the center of gravity of the light intensity of these inclined incident light beams (plurality) is not perpendicular to the reticle, a problem will occur in which the position of the transferred image will shift in the in-plane direction of the wafer when the wafer 20 is slightly defocused. . In order to prevent this, the direction of the center of gravity of the illumination light beams from each fly-eye lens group is perpendicular to the reticle pattern, that is, parallel to the optical axis AX.

That is, assuming that each fly-eye lens group has an optical axis (center line), 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 18 is , and the amount of light emitted from each fly-eye lens group so that the vector sum of the products becomes zero. Also,
A simpler method is to set the number of fly-eye lens groups to 2m (m is a natural number), determine the positions of m of them using the optimization method described above (Fig. 12), and the remaining m lenses to They may be placed at positions that are symmetrical about the axis AX.

Furthermore, there are, for example, n devices (n is a natural number).
of fly-eye lens groups, and the number of required fly-eye lens groups is m, which is less than n,
The remaining (n−m) fly-eye lens groups do not need to be used. In order to avoid using the (n-m) fly-eye lens groups, it is sufficient to provide the light shielding member 10 or 12 at the position of the (n-m) fly-eye lens groups. Further, at this time, it is preferable that the optical member that concentrates the illumination light on the position of each fly-eye lens group does not concentrate the illumination light on these (n−m) fly-eye lenses.

It is desirable that the position of the opening of the light shielding member 10 or 12 is variable in accordance with the movement of each fly's eye lens group. Alternatively, a mechanism for replacing the light shielding members 10 and 12 depending on the position of each fly's eye lens may be provided, and several types of light shielding members may be included in the apparatus. In addition, as shown in FIG. 9, each fly-eye lens group 11A, 11
Jigs 80A, 80B, 8 that hold B, 11C, 11D
When 0C and 80D have light shielding blades 81A and 81B, respectively, the aperture of the light shielding member 12 may be considerably larger than the diameter of the fly's eye lens, and therefore one light shielding member 12 can be used for each of the various fly's eye lens positions. I can handle it. Also,
When each of the light shielding blades 81A, 81B is slightly shifted in the optical axis direction, the restriction on the movement range of each fly's eye lens group is reduced.

In the above embodiment, the light source is a mercury lamp 1.
Although the explanation has been made using the above, other bright line lamps, lasers (excimer, etc.), or continuous spectrum light sources may be used. Furthermore, although most of the optical members in the illumination optical system are lenses, they may also be mirrors (concave mirror, convex mirror). Whether the projection optical system is a refractive system or a reflective system,
Alternatively, it may be a catadioptric system. Further, in the above embodiments, a projection optical system that is telecentric on both sides is used, but a projection optical system that is telecentric on one side or a non-telecentric system may be used. Furthermore, monochromating means such as an interference filter may be provided in the illumination optical system in order to utilize only light of a specific wavelength among the illumination light generated from the light source.

In addition, fly-eye lens groups 11A and 11B
, 11C, and 11D near the light source side focal plane 11a, a light scattering member such as a diffuser plate or an optical fiber bundle may be used to make the illumination light uniform. Alternatively, in addition to the fly's eye lens group 11 used in the embodiment of the present invention, an optical integrator such as a fly's eye lens (hereinafter referred to as another fly's eye lens) may be used to uniformize the illumination light. At this time, the separate fly's eye lens is an optical member that makes the illumination light amount distribution in the vicinity of the light source side focal plane 11a of the fly's eye lens group 11 variable, for example, FIGS.
It is desirable that the light source (lamp) 1 be closer to the light source (lamp) than the diffraction grating pattern 5 or 6 shown in FIG.

Furthermore, it is preferable that the cross-sectional shape of the lens element of another fly's eye lens is a regular hexagon rather than a square (rectangle). FIG. 14 shows the configuration around the wafer stage of a projection exposure apparatus applied to each embodiment of the present invention, in which a beam 100A is obliquely irradiated into the projection field of view on the wafer 20 of the projection optical system 18, The reflected beam 100
An oblique incidence type autofocus sensor that receives B light is provided. This focus sensor detects the deviation in the direction of the optical axis AX between the surface of the wafer 20 and the best image forming plane of the projection optical system 18.
The motor 112 of the Z stage 110 on which 0 is placed is servo-controlled. As a result, the Z stage 110 moves slightly in the vertical direction (optical axis direction) relative to the XY stage 114, and exposure is always performed in the best focus state. In an exposure apparatus capable of such focus control, the apparent depth of focus can be further expanded by moving the Z stage 110 in the optical axis direction with controlled speed characteristics during the exposure operation. This method uses the projection optical system 18
Any type of stepper can be used as long as the image side (wafer side) of the stepper is telecentric.

FIG. 15(A) shows the distribution of the amount of light (dose) in the optical axis direction obtained in the resist layer as the Z stage 110 moves during exposure, or the existence probability.
B) represents the speed characteristic of the Z stage 110 for obtaining the distribution as shown in FIG. 15(A). In both FIGS. 15(A) and 15(B), the vertical axis represents the wafer position in the Z (optical axis) direction.
) represents the existence probability, and the horizontal axis of FIG. 15(B) represents the speed V of the Z stage 110. Also in the same figure, position Z0
is the best focus position.

Here, the existence probabilities are set to approximately equal maximum values at two positions +Z1 and -Z1 which are vertically separated from the position Z0 by the theoretical focal depth ±ΔD0 f of the projection optical system 18, and the positions between them are set to +Z3 to -Z3. In the range of , the probability of existence is kept to a small value. For that purpose, Z
The stage 110 moves up and down at a constant speed of low speed V1 at a position -Z2 when the shutter inside the illumination system starts opening, and immediately after the shutter is fully opened, it moves up and down at a high speed of V2.
accelerate to. While the Z stage 110 is moving up and down at a constant speed of V2, the existence probability is pushed to a low value, and when it reaches the position +Z3, the Z stage 110 starts decelerating toward the low speed V1, and the position +Z1 The probability of existence reaches its maximum value. At this time, a shutter closing command is output almost simultaneously, and the shutter is completely closed at position +Z2.

In this way, the light amount distribution (existence probability) in the optical axis direction of the exposure amount given to the resist layer of the wafer 20 is determined by 2
If the speed of the Z stage 110 is controlled so that the maximum value is reached at a point, uniform resolution can be obtained over a wide range in the optical axis direction, although the contrast of the pattern formed on the resist layer is slightly reduced.

The progressive focus exposure method described above can be used in exactly the same way with a projection exposure apparatus that employs a special illumination method as shown in each embodiment of the present invention, and the apparent depth of focus is The image is enlarged by an amount corresponding to approximately the product of the enlargement obtained by the illumination method of the present invention and the enlargement obtained by the cumulative focus exposure method. Moreover, because it uses a special lighting method, the resolution itself is also high. For example, the minimum line width that can be exposed by combining a phase shift reticle with a conventional 1/5 reduction i-line stepper (projection lens NA 0.42) is about 0.3 to 0.35 μm, and the magnification rate of the depth of focus is The maximum is about 40%. On the other hand, when we incorporated a special illumination method like the present invention into the same i-line stepper and experimented with an ordinary reticle, we found that
The minimum line width was about 0.25 to 0.3 μm, and the depth of focus expansion rate was also about the same as when using a phase shift reticle.

[0075]

As described above, according to the present invention, it is possible to realize a projection type exposure apparatus having a higher resolution and a larger depth of focus than conventional ones, while using a normal mask. Moreover, according to the present invention, it is only necessary to change the illumination system of the projection exposure equipment already in operation at the semiconductor production site, and the projection optical system of the equipment in operation can be used as is to achieve higher resolution than before. becomes possible.

Furthermore, in the present invention, since a plurality of fly-eye lens groups are arranged separately from each other on the surface corresponding to the Fourier transform of the mask in the illumination optical system, even if the fly-eye lens groups are movable, they do not move on the mask or the photosensitive substrate. Another advantage is that the uniformity of the illumination light does not vary greatly. Furthermore, according to the method of concentrating illumination light on the fly-eye lens group shown in each embodiment of the present invention, the loss of the amount of illumination light from the light source can be minimized, so the throughput of the exposure apparatus is also extremely high. It also has the effect of not causing any deterioration.

[Brief explanation of the drawing]

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

[Figure 2] First concentration of illumination light to the fly-eye lens group
It is a figure showing a modification of .

[Figure 3] Second concentration of illumination light on the fly-eye lens group
It is a figure showing a modification of .

[Figure 4] Third stage of concentration of illumination light on the fly-eye lens group
It is a figure showing a modification of .

[Figure 5] Fourth stage of concentration of illumination light on the fly-eye lens group
It is a figure showing a modification of .

[Figure 6] Fifth step of concentrating illumination light on the fly-eye lens group
It is a figure showing a modification of .

7 is a diagram showing an illumination system when a reticle blind is incorporated into the apparatus of FIG. 1. FIG.

FIG. 8 is a plan view of the arrangement of four movable fly's eye lens groups and the configuration of their movable members as viewed from the optical axis direction.

FIG. 9 is a diagram of the configuration of FIG. 8 viewed from a direction perpendicular to the optical axis.

FIG. 10 is a diagram schematically showing the optical path from the fly-eye lens group to the projection optical system.

FIGS. 11A and 11C are plan views showing an example of a reticle pattern formed on a mask. (B), (D
) is a diagram illustrating the arrangement of each fly-eye lens group on the pupil conjugate plane corresponding to each of (A) and (C).

FIG. 12 is a diagram explaining the principle of the present invention.

FIG. 13 is a diagram showing the configuration of a conventional projection exposure apparatus.

FIG. 14 is a diagram showing a configuration around a wafer stage of a projection exposure apparatus.

FIG. 15 shows the existence probability of the exposure amount when performing the progressive focus exposure method using the Z stage of the wafer stages;
It is a graph which shows the speed characteristic of Z stage.

[Explanation of symbols]

5 Diffraction grating pattern 9 Lens systems 11A, 11B, 11C, 11D Fly-eye lens systems 10, 12 Light shielding member (spatial filter) 15
Main condenser lens 16 Reticle 17 Reticle pattern 18 Projection optical system 19 Pupil 20 Wafer

Claims (3)

[Claims] 1. An illumination optical system that shapes illumination light from a light source into a substantially uniform intensity distribution and irradiates the uniform illumination light onto a mask having a periodic pattern portion; A projection exposure apparatus comprising: a projection optical system that forms and projects an image onto a photosensitive substrate; and a stage that holds the photosensitive substrate so that the surface of the photosensitive substrate is placed near the image forming surface of the projection optical system; In the optical path of the illumination optical system, two parts separated from each other are located near the plane corresponding to the Fourier transform of the pattern of the mask or its conjugate plane.
a plurality of fly-eye lens groups that form a second light source image; a position adjustment member that is set at discrete positions decentered with respect to the optical axis of the optical system; a position adjustment member that sets at least two of the plurality of fly eye lens groups after being set by the position adjustment member; A projection exposure apparatus comprising: an input optical system through which illumination light from the light source is input. [Claim 2] The plurality of fly-eye lens groups have a length of 2 m.
(however, m≧1), and each center of the m fly-eye lens groups among the 2m fly-eye lens groups is connected to the 0th-order diffracted light component generated from the pattern of the mask, and the 0-order diffracted light component generated from the pattern of the mask. At least one of the ±1st-order diffracted light components spreading at an angle corresponding to the fineness of the pattern with respect to the second-order diffracted light component is distributed at approximately equal distance from the optical axis on the pupil plane of the projection optical system. , are eccentrically arranged within the Fourier transform equivalent plane or its conjugate plane, and each center of the remaining m fly-eye lens groups is
2. The apparatus according to claim 1, wherein the apparatus is arranged substantially symmetrically with respect to the optical axis and the center of each of the fly's eye lens groups. 3. When focusing on diffracted light generated from the mask by illumination light from any one of the at least two fly-eye lens groups, the diffracted light is located on the pupil plane of the projection optical system. a 0th-order diffracted light component distributed in the pupil plane, and a 1st-order or higher order diffracted light component distributed in a first direction on the pupil plane depending on the two-dimensional periodic structure of the pattern of the mask. Three diffracted light components, one of the diffracted light components and one of the higher-order diffracted light components of the first order or higher distributed on the pupil plane in a second direction that intersects the first direction with the zero-order diffracted light component as the center. , wherein the center of the arbitrary one fly-eye lens group is arranged eccentrically from the optical axis so that the lenses are distributed at approximately equal distance from the optical axis on the pupil plane. equipment.