JP2003068607A - Aligner and exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aligner which enables exposure under the optimum illumination condition, without depending on the directivity of fine pattern on a reticle. SOLUTION: The aligner is provided with an illumination optical system (1-7) for illuminating the reticle (R), in which a pattern to be transferred is formed, and a projection optical system (PL) for forming an image of the pattern of the reticle on a substrate (W). The illumination optical system has a pupil-shape forming means (6) for forming four practical surface light sources on the pupil surface or the surface in the vicinity of the pupil surface. In order to make a resist pattern to be transferred or a substrate pattern to be formed via passing process have a desired size and form, the formation means (6) sets the position coordinates of the longitudinal direction of the four practical surface light sources to be made practically different from the position coordinates in the traversal direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus and an exposure method, and more particularly to an exposure apparatus and an exposure method for manufacturing a microdevice such as a semiconductor element, an image pickup element, a liquid crystal display element, a thin film magnetic head, etc. by a lithography process. .

[0002]

2. Description of the Related Art In a typical exposure apparatus of this type,
The light flux emitted from the light source forms a secondary light source as a substantial surface light source including a large number of light sources via a fly-eye lens as an optical integrator. The light flux from the secondary light source is incident on the condenser lens after being limited through an aperture stop arranged near the rear focal plane of the fly-eye lens.

The luminous flux condensed by the condenser lens illuminates a reticle (mask) having a predetermined pattern in a superimposed manner. The light transmitted through the reticle pattern forms an image on the wafer via the projection optical system. Thus, the reticle pattern is projected and exposed (transferred) on the wafer. Note that the pattern formed on the reticle is highly integrated, and it is essential to obtain a uniform illuminance distribution on the wafer in order to accurately transfer this fine pattern onto the wafer.

[0004]

In recent years, the size of the aperture (light transmitting portion) of the aperture stop arranged on the exit side of the fly-eye lens is changed to form the fly-eye lens. By changing the size of the next light source, the coherency of illumination σ (σ value = aperture stop diameter / pupil diameter of the projection optical system, or σ value = exit side numerical aperture of the illumination optical system / entrance side aperture of the projection optical system The technique of changing the number is drawing attention.

Further, by setting the shape of the aperture of the aperture stop arranged on the exit side of the fly-eye lens to be a ring shape or a four-hole shape (that is, a quadrupole shape), a fly-eye lens is used. A technique for limiting the shape of the secondary light source to a ring shape or a quadrupole shape to improve the depth of focus and the resolution of the projection optical system has attracted attention. However, in the conventional technique as described above, the optimum illumination condition cannot be realized without depending on the directionality of the fine pattern on the reticle.

The present invention has been made in view of the above problems, and an exposure apparatus and an exposure method capable of performing exposure under optimum illumination conditions without depending on the directionality of a fine pattern on a reticle. The purpose is to provide.

[0007]

In order to solve the above problems, in the first invention of the present invention, an illumination optical system for illuminating a reticle on which a pattern to be transferred is formed, and an image of the reticle pattern are formed on a substrate. In an exposure apparatus including a projection optical system formed above, the illumination optical system forms a pupil shape forming unit for forming four substantial surface light sources on a pupil surface of the illumination optical system or a surface in the vicinity thereof. The pupil shape forming means has the pupil planes of the four substantial surface light sources in order to make a resist pattern transferred or a substrate pattern formed through a process have a desired size and shape. Provided is an exposure apparatus, wherein the vertical position coordinate and the horizontal position coordinate on a surface in the vicinity thereof are set so as to be substantially different from each other.

According to a second aspect of the present invention, in an exposure apparatus comprising an illumination optical system for illuminating a reticle having a plurality of chip patterns, and a projection optical system for forming an image of the reticle pattern on a substrate, The illumination optical system has a pupil shape forming means for forming four substantially surface light sources on a pupil plane of the illumination optical system or a surface in the vicinity thereof, and the pupil shape forming means has a length of the chip pattern. Depending on the side direction,
At least one of a vertical position coordinate and a horizontal position coordinate on the pupil plane of the four substantial surface light sources or a surface in the vicinity thereof is defined as the vertical position coordinate and the horizontal position coordinate. There is provided an exposure apparatus characterized in that and are set so as to be substantially different from each other.

According to a preferred embodiment of the second aspect of the invention, the pupil shape forming means has the above-mentioned four features in order to make a resist pattern to be transferred or a substrate pattern formed through a process into a desired size and shape. The vertical position coordinate and the horizontal position coordinate on the pupil plane of the conventional surface light source or on the plane near the pupil plane are set to be substantially different from each other.

According to a preferred aspect of the first invention or the second invention, the pupil shape forming means is arranged in the vertical direction of the resist pattern or the substrate pattern obtained through the reticle on which the optical proximity effect is corrected. In order to adjust at least one of the line width and the line width in the horizontal direction, the position coordinate in the vertical direction and the position coordinate in the horizontal direction on the pupil plane or the plane in the vicinity of the four substantial surface light sources are calculated. Set. Further, the pupil shape forming means sets the ratio between the vertical position coordinate and the horizontal position coordinate on the pupil plane of the four substantial surface light sources or the plane in the vicinity thereof according to a ratio of 10% or more. It is preferable to set them differently. Further, it is preferable that the pupil shape forming unit sets each of the four substantial surface light sources to a circular shape.

Further, according to a preferred aspect of the first invention or the second invention, the pupil shape forming means has an aperture stop for limiting a light flux passing therethrough. In this case, it is preferable that the pupil shape forming unit has a plurality of aperture stops that are configured to be insertable into and removable from the illumination optical path. Further, it is preferable that the pupil shape forming unit has a diffractive optical element for converting a light beam into a light beam having a predetermined cross section. In this case, it is preferable that the pupil shape forming unit has a plurality of diffractive optical elements configured to be insertable into and removable from the illumination optical path.

According to a third aspect of the present invention, in an exposure method for illuminating a reticle through an illumination optical system and projecting an image of a pattern formed on the reticle onto a substrate, a resist pattern or process to be transferred is used. In order to make the formed substrate pattern have a desired size and shape, a vertical position coordinate and a horizontal direction on the pupil plane of the illumination optical system or a plane in the vicinity thereof are defined on the pupil plane or a plane in the vicinity thereof. Provided is an exposure method, which comprises forming four substantially planar light sources whose position coordinates are substantially different from each other.

According to a fourth aspect of the present invention, in the exposure method for illuminating a reticle having a plurality of chip patterns through an illumination optical system and projecting an image of the pattern formed on the reticle onto a substrate, the illumination optical Four substantial surface light sources are formed on a pupil surface of the system or a surface in the vicinity thereof, and the four substantially surface light sources are formed on the pupil surface or a surface in the vicinity thereof according to the long side direction of the chip pattern. In at least one of the vertical position coordinate and the horizontal position coordinate in, the exposure method is characterized in that the vertical position coordinate and the horizontal position coordinate are set to be substantially different from each other. provide.

According to a preferred aspect of the fourth invention, in order to make a resist pattern to be transferred or a substrate pattern formed through a process have a desired size and shape,
The position coordinates in the vertical direction and the position coordinates in the horizontal direction of the four substantial surface light sources on the pupil plane or a surface in the vicinity thereof are set to be substantially different.

According to a preferred aspect of the third invention or the fourth invention, a reticle having an optical proximity effect correction is used as the reticle, and the resist pattern obtained through the reticle having the optical proximity effect correction is used. Alternatively, in order to adjust at least one of a vertical line width and a horizontal line width of the substrate pattern, a vertical position of the four substantial surface light sources on the pupil plane or a plane in the vicinity thereof. Set coordinates and lateral position coordinates. Further, the ratios of the vertical position coordinates and the horizontal position coordinates on the pupil plane or the planes in the vicinity of the four substantial surface light sources may be set to be different according to a ratio of 10% or more. preferable.

A fifth aspect of the present invention is an exposure apparatus including an illumination optical system that illuminates a reticle on which a pattern to be transferred is formed, and a projection optical system that forms an image of the reticle pattern on a substrate. The illumination optical system has a pupil shape forming means for forming four substantially planar light sources on a pupil plane of the illumination optical system or a surface in the vicinity thereof, and the pupil shape forming means forms the pupil shape forming means. Let y be the position coordinates in the vertical direction on the pupil plane of the illumination optical system of the two substantial surface light sources or in the vicinity thereof, and let y be the pupil plane of the illumination optical system of the four substantial surface light sources or the vicinity thereof. When the position coordinate in the horizontal direction on the plane is x, the pupil shape forming means is configured to move the position coordinate y.
And a ratio of the position coordinate x to the first illumination mode that forms the four substantial surface light sources such that the ratio of the position coordinate x is 1.1 or more.
An exposure apparatus is provided which has a second illumination mode for forming the four substantial surface light sources so as to be 1.1 or less.

According to a sixth aspect of the present invention, in the exposure method of illuminating a reticle via an illumination optical system and projecting an image of a pattern formed on the reticle onto a substrate via a projection optical system, the illumination optical system is used. Four substantial surface light sources are formed on the pupil plane of the system or in the vicinity thereof, and vertical position coordinates of the four substantially surface light sources on the pupil plane of the illumination optical system or in the vicinity thereof are defined. Let y be x, and x be the lateral position coordinates of the four substantial surface light sources on the pupil plane of the illumination optical system or a surface in the vicinity thereof, then the ratio of the position coordinate x to the position coordinate y is 1 The first illumination mode that forms the four substantial surface light sources so as to be 1 or more, and the four illumination modes that the ratio of the position coordinate x to the position coordinate y is 1 / 1.1 or less. And a second illumination mode that forms a substantially surface light source. To provide an exposure method comprising Rukoto.

According to a seventh aspect of the present invention, in an exposure apparatus provided with an illumination optical system for illuminating a reticle on which a pattern to be transferred is formed, and a projection optical system for forming an image of the reticle pattern on a substrate. The illumination optical system has a pupil shape forming unit for forming four substantially planar light sources on a pupil plane of the illumination optical system or a surface in the vicinity thereof, and the pupil shape forming unit is the pupil shape forming unit. The center of gravity of one surface light source of the four substantial surface light sources formed by the forming means is 0.5 <r <1-rs, and sin ⁻¹ {(rs) / (1-rs)} The first illumination mode satisfying <θ <π / 4, and the gravity center position of the one surface light source of the four substantial surface light sources are 0.5 <r <1-rs, and π. / 4 <θ <π / 2 -sin -1 {(rs) / (1-rs)}, and a second illumination mode that satisfies To provide an exposure apparatus characterized and.

According to an eighth aspect of the present invention, in the exposure method of illuminating a reticle through an illumination optical system and projecting an image of a pattern formed on the reticle onto a substrate through a projection optical system, the illumination optical system Four substantial surface light sources are formed on the pupil plane of the system or a surface in the vicinity thereof, and the center of gravity of one of the four substantially surface light sources is 0.5 <r <1-rs. , And sin ⁻¹ {(rs) / (1-rs)} <θ <π / 4, and the one surface light source of the one of the four substantial surface light sources. A second illumination mode in which the position of the center of gravity satisfies 0.5 <r <1-rs, and π / 4 <θ <π / 2-sin ⁻¹ {(rs) / (1-rs)}, There is provided an exposure method characterized by having.

However, in the seventh and eighth inventions, r
Is a radius vector when the position of the center of gravity of the one surface light source is represented by polar coordinates (r, θ) on the surface of the pupil plane or in the vicinity thereof with the optical axis of the illumination optical system as a pole, and It is standardized with the radius of the pupil of the optical system being 1. Further, in the seventh and eighth inventions, θ is a polar coordinate (r, θ) with the optical axis of the illumination optical system as a pole on the center of gravity of the one surface light source on the pupil plane or on the surface in the vicinity thereof. This is the declination angle when expressed, and rs is the distance from the position of the center of gravity to the outermost edge of the one surface light source.

According to a preferred aspect of the seventh invention or the eighth invention, the four substantial surface light sources are arranged on the surface of the pupil plane or in the vicinity thereof in a rotational symmetry about the optical axis twice. To be done.

According to a preferred aspect of the fifth, sixth, seventh or eighth invention, in the first illumination mode, the ratio of the position coordinate x to the position coordinate y is 1.2 or more. The four substantial surface light sources are formed, and in the second illumination mode, the four substantial surface light sources are formed such that the ratio of the position coordinate x to the position coordinate y is 0.83 or less. To do.

According to a preferred aspect of the fifth, sixth, seventh or eighth invention, each aperture of the four light beams from the four substantial surface light sources with respect to the reticle side numerical aperture of the projection optical system is increased. When the number ratio is σs, 0.1 ≦ σs ≦ 0.3 is satisfied.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION In an exposure apparatus, as the pattern size becomes finer, k1 factor (line width = k1 × λ / N
A: When λ is a wavelength and NA is a numerical aperture), the resolution dimension deviates from the target dimension and becomes an abnormal line width, the fidelity of the resist pattern to the reticle pattern deteriorates, and the resolution pattern The phenomenon that the species dependence becomes remarkable appears. For example, a phenomenon in which a corner of a pattern which should be 90 degrees in design is rounded, a phenomenon in which a line end is shortened, a phenomenon in which a line width is widened or thinned, and the like appear. These phenomena are collectively called the optical proximity effect (OPE: Optical Prox).
imity Effect).

Originally, this OPE meant the effect of light at the time of transfer, but recently, in addition to the optical effect, the resist process such as exposure amount, resist type, resist development time, etching, and gate material It is used including various effects such as types (effects that occur throughout the wafer process (substrate process)). In the present invention,
Broadly defined OPE (effect that occurs throughout the wafer process) is used.

The causes of such OPE are optical factors in exposure (interference of transmitted light between adjacent patterns), resist process (baking temperature, baking time, developing time, resist type, exposure amount, etc.), The influence of the reflection of the substrate, the unevenness of the substrate, the etching, etc. may be mentioned. Specifically, in transfer, there is an effect derived from optical factors such as diffraction and interference of light, pattern dependence of resist dissolution rate in resist development, microloading effect when etching resist (etching rate is The phenomenon is that the hole diameter or the etching width decreases as the etching width decreases), and the effect of pattern dependence of the etching rate.

In order to achieve a desired performance as a semiconductor device, it is necessary to realize a desired size and shape of a design pattern on a wafer. For that purpose, it has been proposed to correct the pattern collapse (deviation of the finished dimension after etching) caused by OPE on the reticle (correct the design dimension on the reticle). The correction on this reticle is performed by the optical proximity correction (OPC: Op
It is called tical Proximity Correction).

As a method of applying such OPC to the reticle, for example, an auxiliary pattern (arranged at a position apart from the main pattern) on the main pattern, a serif pattern (correction convex pattern added to a corner of the pattern) , An insection pattern (correction concave pattern that cuts out pattern corners), a hammer head (correction mallet pattern added to the pattern), a method of increasing / decreasing the line width of the main pattern, etc. .

FIG. 1 is a diagram for explaining quadrupole illumination, which is optimum for manufacturing a three-chip DRAM chip. Also, in FIG.
It is a figure explaining the quadrupole illumination most suitable for manufacture of the DRAM chip of four pieces. As shown in FIG. 1A, it is assumed that three DRAM chips are manufactured in the field (25 mm × 33 mm) of the scan exposure machine. In this case, the memory cells have a minimum pitch in the vertical direction and a slightly longer pitch in the horizontal direction, as shown in FIG.

The optimum quadrupole illumination for the reticle pattern having the minimum pitch in the vertical direction as shown in FIG. 1 (b) is as shown in FIG. 1 (c). That is, in the quadrupole illumination most suitable for the manufacture of the three-piece DRAM chip, four substantial surface light sources formed on the pupil plane (or in the vicinity thereof) of the illumination optical system are arranged at the apexes of a square. The quadrupole illumination is not the usual quadrupole illumination, but four substantial surface light sources are arranged at the vertices of an elongated rectangle along the vertical direction (direction optically corresponding to the minimum pitch direction of the reticle pattern).

By the way, when a DRAM chip designed according to the design rule of 0.25 .mu.m is designed according to the design rule of 0.18 .mu.m, the area of each chip becomes small due to so-called chip shrink, and three chips are obtained by one exposure. It becomes possible to take four chips that had been taken. That is, as shown in FIG. 2A, four DRAM chips are manufactured within the field (25 mm × 33 mm) of the scan exposure machine. In this case, the memory cells have a minimum pitch in the horizontal direction and a slightly longer pitch in the vertical direction, as shown in FIG.

The optimum quadrupole illumination for the reticle pattern having the minimum lateral pitch as shown in FIG. 2 (b) is as shown in FIG. 2 (c). That is, the optimum quadrupole illumination for manufacturing a four-chip DRAM chip is not the normal quadrupole illumination in which four substantial surface light sources are arranged at the vertices of a square, but the lateral direction (the minimum pitch direction of the reticle pattern). Quadrupole illumination in which four substantially planar light sources are arranged at the vertices of an elongated rectangle along the direction (corresponding to the optical direction). In other words, comparing the case of three-piece and the case of four-piece, the minimum pitch direction of the reticle pattern is 90.
Since they are different from each other, the longitudinal directions of the rectangles in which the four substantially surface light sources are arranged are also different from each other by 90 degrees.

Regarding the active pattern (Active (Isolation) Pattern) of the memory cell, it is natural that the line width control in the direction in which the pattern pitch is the minimum (vertical direction in FIG. 1B) is important. Since it is necessary to make accurate contact with a trench node or a stack node corresponding to a capacitor, it is also important to control the line width in the direction orthogonal to the direction in which the pattern pitch is minimized (horizontal direction in FIG. 1B). Here, the active pattern is D
It is a pattern of a layer arranged on the most silicon substrate side in a RAM, and this layer is called an active layer, an isolation layer, an element isolation layer, an element isolation film, or the like.

Usually, when the reticle (mask) is formed, the above-mentioned OPE (optical proximity effect) is taken into consideration, and the above-mentioned OP
C (optical proximity correction) is applied to the reticle. However, in reality, there may be a situation where it is desired to perform line width control for correcting OPC due to the influence of the change in the resist process or the aberration of the projection optical system. In such cases, 4
By changing the shape of the rectangle in which the four substantially planar light sources of polar illumination are arranged, it becomes possible to control the line width so as to correct the OPC. Hereinafter, the simulation result will be described with respect to this point.

FIG. 3 is a diagram for explaining the form of quadrupole illumination assumed in the simulation. In addition, FIG.
It is a figure explaining the structure of the pattern assumed in the simulation. First, in the simulation,
KrF excimer laser light (wavelength 248n
m), the wafer side numerical aperture NA of the projection optical system is set to 0.
I assumed 82. Further, the maximum σ value of a quadrupole secondary light source including four surface light sources is assumed to be 0.90, and the σ value of each circular surface light source is assumed to be 0.15.

Referring to FIG. 3, vertical position coordinates (on the pupil plane (or a plane in the vicinity) of each circular surface light source formed on the pupil plane (or a plane in the vicinity thereof) of the illumination optical system ( (Y position) as a parameter and converted to NA.
The pitch is changed from 52 to 0.38 at a pitch of 0.02. The lateral position coordinate (X position) of each surface light source is fixed at 0.30. Thus, when the Y position of each surface light source has a maximum value of 0.52, the σ value of the quadrupole secondary light source has a maximum value of 0.90. On the other hand, when the Y position of each surface light source has the minimum value of 0.38, the σ value of the quadrupole secondary light source becomes a predetermined value that is somewhat smaller than the maximum value of 0.90.

Referring to FIG. 4, the pattern assumed in the simulation is an active pattern of 110 nm DRAM. The simulation assumes a 6% halftone phase shift reticle as the reticle. With the halftone phase shift reticle,
A pattern having a chromium (Cr) layer as a lower layer and a molybdenum silicon (MoSi) layer as an upper layer is formed on a glass (quartz) substrate. Here, the light transmittance of the pattern region (hatched portion in FIG. 4) is set to approximately 6% with respect to the light transmittance of the light transmitting region where no pattern is formed.
The phase of the light passing through the pattern area is set to be inverted with respect to the phase of the light passing through the light transmitting area.

In FIG. 5, the Y position of each surface light source is 0.5.
It is a figure which shows the aerial image of the best focus in 2 illumination conditions. Further, FIG. 6 is a diagram showing an aerial image of best focus under an illumination condition in which the Y position of each surface light source is 0.46. FIG. 7 is a diagram showing an aerial image of best focus under an illumination condition in which the Y position of each surface light source is 0.40. 5 to 7, the vertical direction 110
Contour lines display the intensity of the aerial image under each illumination condition when the slice level is adjusted to nm. The intensity of the white area is twice the intensity of the hatched area.

Since the simulation is premised on the use of a positive type resist, a portion having a high intensity (that is, a region other than the shaded portion) is lost as a resist image. In other words, in FIG. 5 to FIG. 7, the area other than the shaded area can be ignored. In addition, in FIGS. 5 to 7, a rectangle shown by a broken line 100 so as to overlap the shaded portion is obtained by simply reducing the reticle pattern by the projection magnification while ignoring the aberration, diffraction, etc. of the projection optical system. A pattern formation position, that is, an ideal pattern formation position is shown. In addition, the broken line 11 which is almost rectangular as a whole
1 indicates that the entire pattern is a repeating pattern of the area indicated by the broken line 111.

With reference to FIGS. 5 to 7, it can be seen that by changing the Y position of each surface light source, the horizontal size can be adjusted while maintaining the vertical size of the aerial image constant. . In other words, it is understood that the aspect ratio of the aerial image can be adjusted by changing at least one of the vertical position coordinate and the horizontal position coordinate of each surface light source.

FIG. 8 is a diagram showing the line width in the vertical direction of the active pattern under each illumination condition and each defocus state in which the Y position of each surface light source is different. In addition, FIG.
FIG. 4 is a diagram showing a lateral line width of an active pattern in each illumination condition where each surface light source has a different Y position and each defocused state. 8 and 9, the vertical axis represents the Y position (NA conversion) of each surface light source, and the horizontal axis represents the defocus amount (μm).

In the simulation, under each illumination condition in which the Y position of each surface light source varies between 0.38 and 0.52, the line width in the vertical direction is 11 in the best focus state.
The exposure amount is determined so as to be 0 nm, and 0.00 μm to 0.
The line width in the vertical direction and the line width in the horizontal direction of the active pattern in each defocus state in which the defocus amount changes within 20 μm were investigated.

Referring to FIGS. 8 and 9, 0.0 μm
Pattern width in the vertical direction, that is, CD (Critical Dimensio)
n: critical dimension) is 110 nm to 1
It is understood that when the exposure amount is set to be 20 nm, the lateral line width of the pattern can be controlled over a wide range of 660 nm to 760 nm by changing the Y position of each surface light source. The critical dimension CD, which is also called a short dimension, is a dimension value that generally indicates a line width, a space, a pattern position, etc. of a pattern of about 100 μm or less. It is used for managing process parameters such as exposure dose, developing conditions, etching conditions, and for dimensional management of products.

As described above, in the present invention, the vertical position coordinates and the horizontal position coordinates on the pupil planes (or the surfaces in the vicinity thereof) of the four substantial surface light sources are substantially different from each other. By setting, the resist pattern to be transferred or the substrate pattern (wafer pattern) formed through the process (wafer process) can have a desired size and shape.

When the reticle has a plurality of chip patterns, at least one of the vertical position coordinates and the horizontal position coordinates of the four substantial surface light sources is selected according to the long side direction of the chip patterns. By setting the vertical position coordinate and the horizontal position coordinate so that they are substantially different from each other, exposure can be performed according to the optimum illumination condition without depending on the directionality of the fine pattern on the reticle. it can.

Furthermore, by setting the vertical position coordinate and the horizontal position coordinate of the four surface light sources, the resist pattern or the substrate pattern obtained through the reticle subjected to the optical proximity correction is set. At least one of the vertical line width and the horizontal line width can be adjusted.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 10 is a view schematically showing the arrangement of the exposure apparatus according to the first embodiment of the present invention. The exposure apparatus shown in FIG. 10 has, for example, 248 nm (KrF) or 193 nm as the light source 1 for supplying exposure light (illumination light).
An excimer laser light source that supplies light having a wavelength of (ArF) is provided. The substantially parallel light flux emitted from the light source 1 has a rectangular cross section elongated in the direction perpendicular to the paper surface of FIG. 10, and enters a beam expander 2 including a pair of lenses 2a and 2b.

Each of the lenses 2a and 2b has a negative refracting power and a positive refracting power in the plane of FIG. 10, and functions as a plane parallel plate in a plane including the optical axis AX and orthogonal to the plane of the paper. Therefore, the light beam incident on the beam expander 2 is expanded in the plane of the paper of FIG. 10 and shaped into a light beam having a predetermined rectangular cross section.
The substantially parallel light flux that has passed through the beam expander 2 as a shaping optical system enters the first fly-eye lens 3.
The first fly-eye lens 3 is configured by arranging a large number of lens elements having a positive refractive power vertically and horizontally and densely. Each lens element forming the first fly-eye lens 3 has, for example, a square cross section.

Therefore, the light beam incident on the first fly-eye lens 3 is two-dimensionally divided by a large number of lens elements, and one light source (focusing point) is formed on the rear focal plane of each lens element. It Light fluxes from a large number of light sources formed on the rear focal plane of the first fly-eye lens 3 illuminate the second fly-eye lens 5 in a superimposed manner via the relay lens 4. The relay lens 4 is the first
The rear focal plane of the fly-eye lens 3 and the rear focal plane of the second fly-eye lens 5 are optically conjugate with each other.
In other words, the relay lens 4 connects the rear focal plane of the first fly-eye lens 3 and the incident surface of the second fly-eye lens 5 in a substantially Fourier transform relationship.

Like the first fly-eye lens 3, the second fly-eye lens 5 is constructed by arranging a large number of lens elements having a positive refractive power vertically and horizontally and densely. Each lens element forming the second fly-eye lens 5 has a rectangular cross-section similar to the shape of the illumination field to be formed on the reticle (mask) (and the shape of the exposure area to be formed on the wafer). Have. Therefore, the light flux incident on the second fly-eye lens 5 is two-dimensionally divided by a large number of lens elements, and a large number of light sources are respectively formed on the rear focal planes of the lens elements on which the light flux is incident.

In this way, a substantially square surface light source (hereinafter referred to as "secondary light source") is formed on the back focal plane of the second fly-eye lens 5. Second fly-eye lens 5
The light flux from the square-shaped secondary light source formed on the rear focal plane enters the aperture stop 6 arranged in the vicinity thereof. The aperture stop 6 is supported on a turret (rotating plate: not shown in FIG. 10) rotatable about a predetermined axis parallel to the optical axis AX.

FIG. 11 is a diagram schematically showing the structure of a turret in which a plurality of aperture stops are circumferentially arranged. Figure 1
As shown in FIG. 1, the turret substrate 40 is provided with eight aperture diaphragms 41 to 48 having a light transmission area shown by hatching in the drawing along the circumferential direction. The turret board 40 is
It is configured to be rotatable about an axis passing through the center point O and parallel to the optical axis AX. Therefore, the turret substrate 40
By rotating the, one aperture stop selected from the eight aperture stops 41 to 48 can be positioned in the illumination optical path. The rotation of the turret substrate 40 is
First drive system 2 that operates based on commands from the control system 21
2 is performed.

The turret substrate 40 is provided with four types of four-pole aperture stops 41 to 44, two types of annular aperture stops 45 and 46, and two types of circular aperture stops 47 and 48. Here, each of the four-pole aperture stops 41 to 44 has four
It has two eccentric circular transmission areas. Further, each of the ring-shaped aperture stops 45 and 46 has a ring-shaped transmission region. Further, each circular aperture stop 47 and 48 has a circular transmissive region.

Therefore, four types of 4-pole aperture diaphragms 41 to 41
By selecting one of the 44 quadrupole aperture stops and positioning it in the illumination optical path, it is possible to perform quadrupole illumination by limiting (defining) the light flux to a quadrupole shape. Further, by selecting one of the two types of annular aperture diaphragms 45 and 46 and positioning it in the illumination optical path, it is possible to limit the luminous flux to an annular shape and perform annular illumination. . Further, one of the two types of circular aperture diaphragms 47 and 48
By selecting one circular aperture stop and positioning it in the illumination optical path, it is possible to limit the luminous flux to a circular shape and perform circular illumination.

In FIG. 10, as the aperture stop 6, one 4-pole aperture stop selected from the four 4-pole aperture stops 41 to 44 is set. However, the configuration of the turret shown in FIG. 11 is merely an example, and the type and number of aperture stops to be arranged are not limited to this. Further, the aperture stop is not limited to the turret type aperture stop, and an aperture stop capable of appropriately changing the size and shape of the light transmission region may be fixedly installed in the illumination optical path. Further, instead of the two circular aperture diaphragms 47 and 48, an iris diaphragm capable of continuously changing the circular aperture diameter can be provided. In the turret system, the number of turrets is not limited to one. For example, in order to increase the types of aperture diaphragms selected, a plurality of turrets may be arranged so as to overlap in the optical axis direction. In addition, the size of the entire surface light source formed on the pupil plane of the illumination optical system (when four surface light sources are formed, the diameter of the circle circumscribing the four surface light sources) is changed to change the illumination σ value. For adjustment, the relay lens 4 may be a zoom lens whose focal length can be changed.

The light from the secondary light source, which has passed through the aperture stop 6 having the quadrupole opening (light transmitting portion), is subjected to the condensing action of the condenser optical system 7, and then a predetermined pattern is formed. The reticle R is illuminated in a superimposed manner. Note that the reticle R is replaced by the second reticle R that operates based on a command from the control system 21.
It is performed by the drive system 23. The light flux that has passed through the pattern of the reticle R forms an image of the reticle pattern on the wafer W, which is a photosensitive substrate, via the projection optical system PL. In this way, by performing the batch exposure or the scan exposure while two-dimensionally drivingly controlling the wafer W in the plane orthogonal to the optical axis AX of the projection optical system PL, the pattern of the reticle R is formed in each exposure region of the wafer W. It is sequentially exposed.

In batch exposure, so-called step
The reticle pattern is collectively exposed to each exposure area of the wafer according to the and repeat method. In this case, the shape of the illumination area on the reticle R is a rectangular shape close to a square, and the cross-sectional shape of each lens element of the second fly-eye lens 5 is also a rectangular shape close to a square. on the other hand,
In scan exposure, a reticle pattern is scan-exposed to each exposure area of the wafer while moving the reticle and the wafer relative to the projection optical system according to a so-called step-and-scan method. in this case,
The shape of the illumination area on the reticle R is a rectangular shape in which the ratio of the short side to the long side is, for example, 1: 3, and the cross-sectional shape of each lens element of the second fly-eye lens 5 is also a similar rectangular shape. Become.

In the first embodiment, four types of four-pole aperture stops 41 to 44 form four substantial surface light sources on the pupil plane (or in the vicinity thereof) of the illumination optical system (1 to 7). For forming the pupil shape. Then, information about various reticles to be sequentially exposed according to the step-and-repeat method or the step-and-scan method is input to the control system 21 via the input means 20 such as a keyboard. The control system 21 stores information such as optimum line width (resolution) and depth of focus for various reticles in an internal memory unit, and in response to an input from the input means 20, the first drive system 22 and the first drive system 22. An appropriate control signal is supplied to the 2-drive system 23.

Thus, as the reticle R is exchanged by the action of the second drive system 23, the first drive system 22 may use one of the four types of four-pole aperture diaphragms 41 to 44 as necessary. Is set in the illumination optical path. Here, when the quadrupole aperture stops 41 to 44 are set in the illumination optical path, the vertical position coordinates and the horizontal position coordinates on the pupil planes (or the surfaces in the vicinity thereof) of the four surface light sources are substantially the same. It is set to be substantially different. Here, the vertical position coordinates are as shown in FIG.
It is the coordinates of the center position of each surface light source along the vertical direction of the paper surface. The horizontal position coordinates are the coordinates of the center position of each surface light source along the direction perpendicular to the paper surface of FIG.

More specifically, when the 4-pole aperture stop 41 or 43 is set in the illumination optical path, the horizontal position coordinate is set larger than the vertical position coordinate. However, the ratio of the vertical position coordinate to the horizontal position coordinate is
The vertical position coordinate is 1, and the horizontal position coordinate is 1.1.
That is all. And 4 more than in the case of the 4-pole aperture stop 41.
In the case of the polar aperture stop 43, the lateral position coordinate is set to be larger. That is, the four-pole aperture diaphragms 41 and 43
Provides a first illumination mode that forms four substantial surface light sources in which the ratio of the horizontal position coordinate x to the vertical position coordinate y is 1.1 or more.

When the quadrupole aperture stop 42 or 44 is set in the illumination optical path, the vertical position coordinate is set larger than the horizontal position coordinate. However, the ratio of the vertical position coordinate to the horizontal position coordinate is 1.1 or more for the vertical position coordinate, where the horizontal position coordinate is 1. The 4-pole aperture stop 44 is larger than the 4-pole aperture stop 42.
In this case, the position coordinate in the vertical direction is set larger.
That is, in the 4-pole aperture diaphragms 42 and 44, the ratio of the horizontal position coordinate x to the vertical position coordinate y is 1 / 1.1.
A second forming four substantially planar light sources such as:
Of the lighting mode. As described above, in the quadrupole aperture stops 41 to 44, the ratios of the vertical position coordinates and the horizontal position coordinates of the four substantial surface light sources are set to be different according to the ratio of 10% or more. .

Therefore, in the first embodiment, one quadrupole aperture stop selected from four types of four-pole aperture stops 41 to 44 is set in the illumination optical path, and four substantial surface light source positions in the vertical direction are set. By setting the coordinates to be substantially different from the lateral position coordinates, the resist pattern to be transferred or the wafer pattern formed through the wafer process can have a desired size and shape.

When the reticle R has a plurality of chip patterns, the number of the reticle R is 4 depending on the long side direction of the chip patterns.
By setting at least one of the vertical position coordinate and the horizontal position coordinate of the two substantially planar light sources so that the vertical position coordinate and the horizontal position coordinate are substantially different, The exposure can be performed under the optimum illumination condition without depending on the directionality of the fine pattern on R. The first illumination mode in which the ratio of the horizontal position coordinates to the vertical position coordinates of the four substantial surface light sources is 1.1 or more, and the second lighting mode in which the ratio is 1 / 1.1 or less. Since it has both of the above illumination modes, exposure can be performed according to the optimal illumination condition without depending on the directionality of the fine pattern on the reticle R.

Furthermore, the resist pattern or wafer pattern obtained through the reticle R on which the optical proximity effect correction is performed by setting the vertical position coordinate and the horizontal position coordinate of the four surface light sources. At least one of the vertical line width and the horizontal line width can be adjusted. Although the optical path bending mirror for deflecting the optical path of the illumination optical system is omitted in the above-described first embodiment and second to fourth embodiments described later, when such an optical path bending mirror is provided, The vertical and horizontal directions of the four substantial surface light sources may be set in consideration of the deflection by the optical path bending mirror.

FIG. 12 is a schematic view showing the arrangement of an exposure apparatus according to the second embodiment of the present invention. The second embodiment has a similar configuration to the first embodiment, but basically differs only in that a diffractive optical element 8 is arranged instead of the first fly-eye lens 3 in the first embodiment. . The second embodiment will be described below, focusing on the differences from the first embodiment.

In the second embodiment, the luminous flux from the light source 1 is
It is incident on the diffractive optical element 8 via the beam expander 2. The diffractive optical element 8 is supported on a turret (rotating plate: not shown in FIG. 12) rotatable about a predetermined axis parallel to the optical axis AX. FIG. 13 is a diagram schematically showing a configuration of a turret in which a plurality of diffractive optical elements are circumferentially arranged. As shown in FIG. 13, the turret substrate 50 is provided with eight diffractive optical elements 51 to 58 along the circumferential direction.

The turret substrate 50 is constructed to be rotatable about an axis passing through the center point O and parallel to the optical axis AX. Therefore, by rotating the turret substrate 50, one diffractive optical element selected from the eight diffractive optical elements 51 to 58 can be positioned in the illumination optical path. The rotation of the turret substrate 50 is controlled by the control system 2
It is performed by the third drive system 24 that operates based on the command from 1.

Generally, the diffractive optical element (DOE) is formed by forming a step having a pitch on the order of the wavelength of exposure light (illumination light) on a glass substrate, and has a function of diffracting an incident beam to a desired angle. . Specifically, the diffractive optical elements 51 to 58 form a light intensity distribution having a predetermined shape in the far field (or the Fraunhofer diffraction region), that is, on the incident surface of the second fly-eye lens 5.
The turret substrate 50 includes four types of diffractive optical elements 51 to 54 for quadrupole illumination, two types of diffractive optical elements 55 and 56 for annular illumination, and two types of diffractive optical elements 57 for circular illumination. And 58 are provided. An example of such a diffractive optical element is, for example, Japanese Patent Laid-Open No. 2001-17.
The diffractive optical element disclosed in Japanese Patent No. 4615 or US Pat. No. 5,850,300 can be used.

As shown in FIG. 13, diffractive optical elements 51 to
Reference numeral 54 denotes a quadrupole illumination field corresponding to the four decentered circular transmission areas of the aperture stops 41 to 44, and the second fly-eye lens 5
Has a function of forming on the incident surface of. Further, the diffractive optical elements 55 and 56 have a function of forming an annular illumination field corresponding to the annular transmission areas of the aperture stops 45 and 46 on the incident surface of the second fly-eye lens 5. Further, the diffractive optical elements 57 and 58 have a function of forming a circular illumination field corresponding to the circular transmission areas of the aperture diaphragms 47 and 48 on the incident surface of the second fly-eye lens 5. Hereinafter, as the diffractive optical element 8, the diffractive optical elements 51 for quadrupole illumination
It is assumed that one diffractive optical element selected from 54 is used.

In this case, the light flux passing through the diffractive optical element 8 passes through the relay lens 4 and the second fly-eye lens 5
A quadrupole illumination field is formed on the incident surface of. Thus, a quadrupole secondary light source having substantially the same light intensity distribution as the illumination field formed by the light flux incident on the second fly-eye lens 5 is formed on the rear focal plane of the second fly-eye lens 5. It The light flux from the quadrupole secondary light source formed on the rear focal plane of the second fly-eye lens 5 is limited by the aperture stop 6 selected according to the diffractive optical element 8, and then the condenser optical system 7 The reticle R is illuminated via.

Therefore, in the second embodiment, four kinds of diffractive optical elements 51 to 54 for quadrupole illumination and a quadrupole aperture stop 4 are used.
1 to 44 constitute pupil shape forming means for forming four substantial surface light sources on the pupil plane (or in the vicinity thereof) of the illumination optical system. Thus, also in the second embodiment, one of the four types of diffractive optical elements 51 to 54 for quadrupole illumination is set in the illumination optical path along with the replacement of the reticle R, and four types are also provided. By setting one 4-pole aperture stop of the 4-pole aperture stops 41 to 44 in the illumination optical path, the same effect as that of the first embodiment can be obtained.

In the second embodiment, the diffractive optical element 8
Since the illumination field having a predetermined shape is formed on the entrance surface of the second fly-eye lens 5 by using, it is possible to favorably suppress the light amount loss in the aperture stop 6. Further, in the second embodiment, the aperture stop 6 is used as the pupil shape forming means,
For example, the arrangement of the aperture stop 6 can be omitted by using a microlens array instead of the second fly-eye lens 5.

The microlens array is an optical element composed of a large number of minute lenses having a positive refracting power and arranged vertically and horizontally and densely. Generally, a microlens array is
For example, it is configured by etching a parallel flat glass plate to form a group of minute lenses. Here, each microlens that constitutes the microlens array is
It is smaller than each lens element that constitutes the fly-eye lens. Further, unlike the fly-eye lens that includes lens elements that are isolated from each other, the microlens array is integrally formed with a large number of minute lenses that are not isolated from each other. However, the microlens array is the same as the fly-eye lens in that the lens elements having positive refracting power are arranged vertically and horizontally.

In the first embodiment described above, a microlens array may be used instead of at least one of the first fly-eye lens 3 and the second fly-eye lens 5. When the arrangement of the aperture stop 6 is omitted as described above, the diffractive optical elements 51 and 5 for quadrupole illumination are used.
3 is the horizontal position coordinate x with respect to the vertical position coordinate y
Provides a first illumination mode for forming four substantial surface light sources on the pupil plane of the illumination optical system with a ratio of 1.1 or more, thereby diffractive optical elements 52 and 5 for quadrupole illumination.
4 is a horizontal position coordinate x with respect to a vertical position coordinate y
The second illumination mode for forming four substantial surface light sources on the pupil plane of the illumination optical system such that the ratio of is less than 1 / 1.1 is provided.

In the second embodiment, the number of turret substrates 50 is not limited to one. For example, in order to increase the types of diffractive optical elements to be selected, a plurality of turrets may be arranged so as to overlap each other in the optical axis direction. In addition, the size of the entire surface light source formed on the pupil plane of the illumination optical system (when four surface light sources are formed, the diameter of the circle circumscribing the four surface light sources) is changed to change the illumination σ value. For adjustment, the relay lens 4 may be a zoom lens whose focal length can be changed.

FIG. 14 is a view schematically showing the arrangement of an exposure apparatus according to the third embodiment of the present invention. The third embodiment has a configuration similar to that of the second embodiment, but in place of the wavefront splitting type second fly's eye lens 5 in the second embodiment, an internal reflection type rod-type optical integrator 9 is arranged. Only fundamentally different. The third embodiment will be described below, focusing on the differences from the second embodiment.

In the third embodiment, a condenser lens 10 is provided in the optical path between the relay lens 4 and the rod type integrator 9 in response to the use of the rod type integrator 9 in place of the second fly's eye lens 5. The imaging optical system 11 is installed instead of the condenser optical system 10, and the aperture stop for limiting the secondary light source is removed. Here, in the synthetic optical system including the relay lens 4 and the condenser lens 10, the diffractive optical element 8 and the incident surface of the rod-type integrator 9 are optically conjugate with each other. Further, the imaging optical system 11 optically connects the exit surface of the rod type integrator 9 and the reticle R in a substantially conjugate manner.

The rod type integrator 9 is an internal reflection type glass rod made of a glass material such as quartz glass or fluorite, and utilizes total reflection at the boundary surface between the inside and the outside, that is, the inside surface to collect the light. A number of light source images corresponding to the number of internal reflections are formed along a plane parallel to the rod entrance plane. Here, most of the light source images formed are virtual images, but only the light source image at the center (condensing point) is the real image. That is, the light beam incident on the rod-type integrator 9 is angularly divided by internal reflection, and a secondary light source composed of a large number of light source images is formed along a plane that passes through the focal point and is parallel to the incident plane.

The light flux from the secondary light source formed on the incident side by the rod-type integrator 9 is superposed on the exit surface thereof, and then is passed through the imaging optical system 11 to the reticle R on which a predetermined pattern is formed. Illuminate uniformly. As described above, the imaging optical system 11 includes the rod-type integrator 9
And the reticle R (and thus the wafer W) are optically conjugate with each other. Therefore, on the reticle R, a rectangular illumination field similar to the cross-sectional shape of the rod type integrator 9 is formed.

As described above, also in the third embodiment, with the replacement of the reticle R, one of the four diffractive optical elements 51 to 54 for quadrupole illumination is set in the illumination optical path. In addition, four types of 4-pole aperture diaphragms 41-
By setting one 4-pole aperture stop of 44 in the illumination optical path, the same effect as in the second embodiment can be obtained. In addition, in the third embodiment, as described above, the installation of the aperture stop for limiting the secondary light source can be omitted.

Also in the third embodiment, the number of turret substrates 50 is not limited to one as in the second embodiment, and a plurality of turret substrates 50 may be arranged in the optical axis direction. In addition, the size of the entire surface light source formed on the pupil plane of the illumination optical system (when four surface light sources are formed, the diameter of the circle circumscribing the four surface light sources) is changed to change the illumination σ value. To make adjustments, relay lens 4 and condenser lens 10
At least one of the above may be a zoom lens.

FIG. 15 is a schematic view showing the arrangement of an exposure apparatus according to the fourth embodiment of the present invention. The fourth embodiment has a configuration similar to that of the second embodiment, but the first embodiment is arranged in order from the light source side in the optical path of the relay lens 4 in the second embodiment.
The only difference is that a V-groove axicon system 12 and a second V-groove axicon system 13 are arranged. The fourth embodiment will be described below, focusing on the differences from the second embodiment.

As shown in FIG. 15, the first V-groove axicon system 12 has, in order from the light source side, a first prism 12a having a flat surface facing the light source side and a concave refracting surface facing the reticle side.
And a second prism 12b having a flat surface facing the reticle and a convex refracting surface facing the light source. The concave refracting surface of the first prism 12a is composed of two planes parallel to the X direction and has a V-shaped convex cross section along the YZ plane.

The convex refracting surface of the second prism 12b is the first refraction surface.
The concave refracting surface of the prism 12a can be brought into contact with each other, in other words, the concave refracting surface of the first prism 12a is formed in a complementary manner. That is, the concave refracting surface of the second prism 12b is composed of two planes parallel to the X direction, and has a V-shaped concave cross section along the YZ plane. Further, at least one of the first prism 12a and the second prism 12b is configured to be movable along the optical axis AX, and the interval thereof is variable. The change in the interval of the first V-groove axicon system 12 is performed by the fourth drive system 25 that operates based on a command from the control system 21.

The second V-groove axicon system 13 includes, in order from the light source side, a first prism 13a having a flat surface facing the light source side and a concave refracting surface facing the reticle side, and a flat surface facing the reticle side and projecting toward the light source side. Second prism 1 with a curved refracting surface
3b and. The concave refracting surface of the first prism 13a is composed of two planes parallel to the Z direction, and X
It has a V-shaped convex cross section along the Y plane. The convex refracting surface of the second prism 13b is formed so as to be able to come into contact with the concave refracting surface of the first prism 13a, in other words, complementary to the concave refracting surface of the first prism 13a.

That is, the concave refracting surface of the second prism 13b is composed of two planes parallel to the Z direction, and has a V-shaped concave cross section along the XY plane. In addition, at least one of the first prism 13a and the second prism 13b is configured to be movable along the optical axis AX, and its interval is configured to be variable. As described above, the second V-groove axicon system 13 has the first V-groove axicon system 12 with the optical axis AX.
It has a form obtained by rotating it around 90 degrees. In addition,
The change in the spacing of the second V-groove axicon system 13 is controlled by the control system 21.
This is performed by the fifth drive system 26 that operates based on the command from.

Here, when the concave refracting surface of the first prism 12a and the convex refracting surface of the second prism 12b are in contact with each other, the first V-groove axicon system 12 functions as a plane-parallel plate, There is no effect on the quadrupole secondary light source formed on the back focal plane of the fly-eye lens 5. However, when the concave refracting surface of the first prism 12a and the convex refracting surface of the second prism 12b are separated, the first V-groove axicon system 12 functions as a plane-parallel plate along the X direction, but along the Z direction. Function as a beam expander. Therefore, the action of the first V-groove axicon system 12 does not change the horizontal position coordinates of the four surface light sources, but changes only the vertical position coordinates.

When the concave refracting surface of the first prism 13a and the convex refracting surface of the second prism 13b are in contact with each other, the second V-groove axicon system 13 functions as a plane-parallel plate and the second fly. There is no effect on the quadrupole secondary light source formed on the back focal plane of the eye lens 5. However, if the concave refracting surface of the first prism 13a and the convex refracting surface of the second prism 13b are separated, the second V-groove axicon system 13 functions as a plane-parallel plate along the Z direction, but along the X direction. Function as a beam expander. Therefore, by the action of the second V-groove axicon system 13, the vertical position coordinates of the four surface light sources do not change, but only the horizontal position coordinates change.

As described above, in the fourth embodiment, four types of diffractive optical elements 51 to 54 for quadrupole illumination are provided, but the action of the first V-groove axicon system 12 and the second V-groove axicon system 13 is as follows. Thus, the vertical position coordinates and the horizontal position coordinates of the four surface light sources can be continuously changed and set to desired values.

Also in the fourth embodiment, the ratios of the vertical position coordinates and the horizontal position coordinates of the four substantial surface light sources are set to be different according to the ratio of 10% or more, that is, 4 It is preferable that the ratio of the horizontal position coordinate x to the vertical position coordinate y of the two substantially planar light sources is set to 1.1 or more, or the ratio is set to 1 / 1.1 or less.

Also in the fourth embodiment, the number of turret substrates 50 is not limited to one as in the second embodiment, and a plurality of turret substrates 50 may be arranged so as to be stacked in the optical axis direction. The size of the entire surface light source formed on the pupil plane of the illumination optical system (when four surface light sources are formed,
The relay lens 4 may be a zoom lens in order to adjust the illumination σ value by changing the diameter of the circle circumscribing the four surface light sources.

In each of the above embodiments, when the ratio of the numerical aperture of each of the four light fluxes from the four surface light sources to the reticle side numerical aperture of the projection optical system is σs, 0.1 ≦ It is preferable to satisfy σs ≦ 0.3.
Here, if the value goes below the lower limit, the image fidelity decreases, and if it goes above the upper limit, the effect of expanding the depth of focus decreases, which is not preferable.

Further, in each of the above-mentioned embodiments, four surface light sources are formed on the pupil plane of the illumination optical system or a surface in the vicinity thereof. However, in the first illumination mode, these four substantial light sources are substantially formed. The gravity center position of one of the surface light sources satisfies 0.5 <r <1-rs, and sin ⁻¹ {(rs) / (1-rs)} <θ <π / 4, In the second illumination mode, the position of the center of gravity of the one surface light source of the four substantial surface light sources is 0.5 <r <1-rs, and π / 4 <θ <π / 2-sin ⁻¹ {(rs) / (1-rs)}, is preferably satisfied.

A detailed description will be given below with reference to FIG. 16 which is a schematic view of four substantial surface light sources formed in the pupil of the illumination optical system. In FIG. 16, the optical axis of the illumination optical system is the origin O.
The first of the four effective surface light sources in the XY coordinate system
One surface light source 60 located in the quadrant is shown. Figure 1
6, the polar coordinates with the optical axis (origin O) of the illumination optical system as a pole are set, and the coordinates of the barycentric position 61 of the surface light source 60 are (r,
θ). In FIG. 16, the radius of the pupil of the projection optical system is standardized as 1. Here, in FIG. 16, the radius of the image of the pupil of the projection optical system formed by the optical system located from the pupil of the projection optical system to the pupil of the illumination optical system is 1.

In FIG. 16, r is the radius vector when the barycentric position 61 is displayed in polar coordinates (the distance from the point O to the barycentric position 61), and θ is the declination (X-axis) when the barycentric position 61 is displayed in polar coordinates. And the radius). Further, rs is the distance from the center of gravity 61 in the surface light source 60 to the outermost edge. Although the surface light source 60 has a circular shape in FIG. 16, the shape of the surface light source 60 is not limited to a circular shape, and may be, for example, a quadrangular shape, a hexagonal shape, or a fan shape. If the surface light source 60 has a circular shape, rs is the radius of the surface light source 60. If the surface light source 60 is not circular, rs is the shortest distance from the center of gravity 61 of the surface light source 60 to the outermost edge. And

As shown in FIG. 16, in the first illumination mode, the center of gravity 61 of the surface light source 60 is 0.5 <r <1-rs, and sin ⁻¹ {(rs) / (1-rs)}. It is located within a region 62 represented by <θ <π / 4. Then, in the second illumination mode, the barycentric position 61 of the surface light source 60 is 0.5 <r <1-rs, and π / 4 <θ <π / 2-sin ⁻¹ {(rs) / (1- rs)}, which is located in the area 63.

By setting the first and second illumination modes as described above, it is possible to perform exposure under optimum illumination conditions without depending on the directionality of the fine pattern on the reticle R. Although the position of a specific one of the four surface light sources has been described with reference to FIG. 16, the four substantial surface light sources in each of the embodiments illuminate the pupil plane or a surface in the vicinity thereof. They are arranged in a twofold rotational symmetry about the optical axis of the optical system. It should be noted that n-fold rotational symmetry means that when an arbitrary space figure is rotated around an arbitrary space axis by an angle of an integer n of one complete rotation, a figure congruent with the original figure is obtained. Show.

When four substantial surface light sources are arranged so as to be rotationally symmetrical about the optical axis of the illumination optical system twice as described above, in the first illumination mode, the first quadrant of the four surface light sources is used. The first surface light source located at is 0.5 <r <1-rs, and sin ⁻¹ {(rs) / (1-rs)} <θ <π / 4, and the four surface light sources are Second located in the second quadrant of the
The surface light source of is satisfied by 0.5 <r <1-rs, and 3π / 4 <θ <π-sin ⁻¹ {(rs) / (1-rs)}, and among the four surface light sources, Third located in the third quadrant
The surface light source of 0.5 satisfies the following condition: 0.5 <r <1-rs, and π + sin ⁻¹ {(rs) / (1-rs)} <θ <5π / 4. Fourth located in the quadrant
It is preferable that the surface light source of 1 satisfies the following conditions: 0.5 <r <1-rs, and 7π / 4 <θ <2π-sin ⁻¹ {(rs) / (1-rs)}.

In this case, in the second illumination mode, the first surface light source located in the first quadrant among the four surface light sources has the following values: 0.5 <r <1-rs, and π / 4 < θ <(π / 2) -sin ^-1 {(rs) / (1-r
s)}, which is the second of the four surface light sources located in the second quadrant
Surface light source of 0.5 <r <1-rs, and (π / 2) + sin ⁻¹ {(rs) / (1-rs)} <θ <3π /
3 which is located in the 3rd quadrant among the 4 surface light sources and satisfies 4,
Surface light source of 0.5 <r <1-rs, and 5π / 4 <θ <(3π / 2) -sin ⁻¹ {(rs) / (1-r
s)}, and the 4th surface light source located in the 4th quadrant
Surface light source of 0.5 <r <1-rs, and (3π / 2) + sin ⁻¹ {(rs) / (1-rs)} <θ <7π
It is preferable to satisfy / 4 ,.

By setting the first and second illumination modes in this way, it is possible to perform exposure under optimum illumination conditions without depending on the directionality of the fine pattern on the reticle R. Further, in the above-described first, second and fourth embodiments, in the optical path between the reticle R and the condenser optical system 7 that collects the light from the secondary light source formed by the second fly-eye lens 5. A relay optical system for projecting an image of the uniform illumination surface formed by the condenser optical system 7 on the reticle R may be arranged. In this case, it is preferable to place a reticle blind (illumination field stop) at a position that is conjugate with the reticle R by the relay optical system.

In each of the above embodiments, 248
A KrF excimer laser that supplies light of a wavelength of nm or an ArF excimer laser that supplies light of a wavelength of 193 nm was applied as a light source. As a light source, an F ₂ laser that supplies light of a wavelength of 157 nm and a light of 146 nm wavelength are used. A laser light source that supplies light in the vacuum ultraviolet region, such as a Kr ₂ laser that supplies light or an Ar ₂ laser that supplies light with a wavelength of 126 nm, or light such as g-line (436 nm) or i-line (365 nm). A lamp light source such as an ultra-high pressure mercury lamp can be applied.

Further, in the exposure apparatus of each of the above embodiments,
A reticle (mask) is illuminated by an illumination device (illumination step), and a transfer pattern formed on the mask is exposed on a photosensitive substrate using a projection optical system (exposure step), whereby a microdevice (semiconductor element, Imaging devices, liquid crystal display devices, thin film magnetic heads, etc.) can be manufactured.
Hereinafter, an example of a method for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of each embodiment will be described with reference to the flowchart of FIG. Explain.

First, in step 301 of FIG. 17,
A metal film is deposited on one lot of wafers. In the next step 302, photoresist is applied on the metal film on the wafer of the 1 lot. Then step 30
3, the image of the pattern on the mask is sequentially exposed and transferred to each shot area on the wafer of the one lot through the projection optical system by using the exposure apparatus of each embodiment.
Then, in step 304, the photoresist on the one lot of wafers is developed, and then in step 3
In 05, the resist pattern is used as a mask on the wafers of one lot to perform etching, whereby a circuit pattern corresponding to the pattern on the mask is formed in each shot area on each wafer.

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

In the fourth embodiment, the relay lens 4
Although the first V-groove axicon system 12 and the second V-groove axicon system 13 are arranged in the optical path of, the so-called conical axicon system can be additionally provided. Alternatively, instead of the first V-groove axicon system 12 or the second V-groove axicon system 13, a conical axicon system can be arranged. Here, the conical axicon system includes a first prism having a conical convex refracting surface and a second prism having a conical concave refracting surface.
It is an axicon system consisting of a prism.

[0106]

As described above, according to the present invention, exposure can be performed under the optimum illumination condition without depending on the directionality of the fine pattern on the reticle. That is, the resist pattern to be transferred is set by setting the vertical position coordinate and the horizontal position coordinate on the pupil planes (or in the vicinity thereof) of the four substantial surface light sources to be substantially different. Alternatively, a substrate pattern (wafer pattern) formed through a process (wafer process)
Can be of any desired size and shape.

When the reticle has a plurality of chip patterns, at least one of the vertical position coordinate and the horizontal position coordinate of the four substantial surface light sources is set in accordance with the long side direction of the chip pattern. By setting the vertical position coordinate and the horizontal position coordinate so that they are substantially different from each other, exposure can be performed according to the optimum illumination condition without depending on the directionality of the fine pattern on the reticle. it can.

Further, by setting the vertical position coordinates and the horizontal position coordinates of the four substantial surface light sources, the resist pattern or substrate pattern obtained through the reticle subjected to the optical proximity correction is set. At least one of the vertical line width and the horizontal line width can be adjusted.

[Brief description of drawings]

FIG. 1 is a diagram illustrating quadrupole illumination, which is optimal for manufacturing a three-piece DRAM chip.

FIG. 2 is a diagram for explaining a quadrupole illumination most suitable for manufacturing a four-chip DRAM chip.

FIG. 3 is a diagram illustrating a form of quadrupole illumination assumed in a simulation.

FIG. 4 is a diagram illustrating a configuration of a pattern assumed in a simulation.

FIG. 5 is a diagram showing an aerial image of best focus under an illumination condition in which the Y position of each surface light source is 0.52.

FIG. 6 is a diagram showing an aerial image of best focus under an illumination condition in which the Y position of each surface light source is 0.46.

FIG. 7 is a diagram showing an aerial image of best focus under an illumination condition in which the Y position of each surface light source is 0.40.

FIG. 8 is a diagram showing line widths in the vertical direction of the active pattern under each illumination condition and each defocus state in which the Y position of each surface light source is different.

FIG. 9 is a diagram showing a horizontal line width of an active pattern under each illumination condition and each defocus state in which the Y position of each surface light source is different.

FIG. 10 is a diagram schematically showing a configuration of an exposure apparatus according to the first embodiment of the present invention.

FIG. 11 is a diagram schematically showing a configuration of a turret in which a plurality of aperture stops are circumferentially arranged.

FIG. 12 is a diagram schematically showing a configuration of an exposure apparatus according to a second embodiment of the present invention.

FIG. 13 is a diagram schematically showing a configuration of a turret in which a plurality of diffractive optical elements are circumferentially arranged.

FIG. 14 is a diagram schematically showing a configuration of an exposure apparatus according to a third embodiment of the present invention.

FIG. 15 is a view schematically showing the arrangement of an exposure apparatus according to the fourth embodiment of the present invention.

FIG. 16 is a diagram showing coordinates of each surface light source on an illumination pupil.

FIG. 17 is a flowchart showing an example of a method for obtaining a semiconductor device as a micro device.

[Explanation of symbols]

1 light source 2 beam expander 3,5 fly eye lens 4 relay lens 6 Aperture stop 7 Condenser optical system 8 Diffractive optical element 9 Rod type integrator 10 condenser lens 11 Imaging optical system 12,13 V groove axicon system 40,50 turret substrate 41-48 Aperture stop 51-58 Diffractive optical element R reticle PL projection optical system W wafer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeru Hikawa             Marunouchi 3 2-3 No. 3 shares, Chiyoda-ku, Tokyo             Ceremony Company Nikon (72) Inventor Kyoichi Suwa             Marunouchi 3 2-3 No. 3 shares, Chiyoda-ku, Tokyo             Ceremony Company Nikon (72) Inventor Toshiharu Nakajima             Marunouchi 3 2-3 No. 3 shares, Chiyoda-ku, Tokyo             Ceremony Company Nikon F term (reference) 2H095 BB01                 5F046 BA04 CB05 CB10 CB12 CB13                       CB14

Claims (24)

[Claims] 1. An exposure apparatus comprising: an illumination optical system that illuminates a reticle on which a pattern to be transferred is formed; and a projection optical system that forms an image of the pattern of the reticle on a substrate. A pupil shape forming means for forming four substantial surface light sources on a pupil surface of the illumination optical system or a surface in the vicinity thereof, the pupil shape forming means passing through a resist pattern or a process to be transferred. In order to make the formed substrate pattern have a desired size and shape, the vertical position coordinates and the horizontal position coordinates of the four substantial surface light sources on the pupil plane or a plane in the vicinity thereof are substantially equal to each other. The exposure apparatus is characterized in that the settings are made differently. 2. An exposure apparatus comprising an illumination optical system for illuminating a reticle having a plurality of chip patterns, and a projection optical system for forming an image of the pattern of the reticle on a substrate, wherein the illumination optical system comprises: It has a pupil shape forming means for forming four substantially surface light sources on the pupil surface of the illumination optical system or a surface in the vicinity thereof, and the pupil shape forming means, according to the long side direction of the chip pattern, At least one of a vertical position coordinate and a horizontal position coordinate on the pupil plane of the four substantial surface light sources or a surface in the vicinity thereof is defined as the vertical position coordinate and the horizontal position coordinate. The exposure apparatus is characterized in that and are set so as to be substantially different from each other. 3. The pupil shape forming means forms the resist pattern to be transferred or a substrate pattern formed through a process into a desired size and shape, so that the pupil planes of the four substantially surface light sources. 3. The exposure apparatus according to claim 2, wherein the vertical position coordinate and the horizontal position coordinate on the surface in the vicinity thereof are set to be substantially different from each other. 4. The pupil shape forming means includes at least one of a line width in a vertical direction and a line width in a horizontal direction of the resist pattern or the substrate pattern obtained via the reticle subjected to optical proximity correction. The vertical position coordinate and the horizontal position coordinate on the pupil plane of the four substantial surface light sources or on a plane in the vicinity thereof are set to adjust one of them. The exposure apparatus according to any one of 1. 5. The pupil shape forming means sets the ratio between the vertical position coordinate and the horizontal position coordinate of the four substantial surface light sources on the pupil plane or a surface in the vicinity thereof to 10% or more. 5. The exposure apparatus according to claim 1, wherein the exposure apparatus is set so as to be different according to the ratio of. 6. The exposure apparatus according to claim 1, wherein the pupil shape forming unit sets each of the four substantial surface light sources into a circular shape. . 7. The exposure apparatus according to claim 1, wherein the pupil shape forming unit has an aperture stop for limiting a light flux passing therethrough. 8. The exposure apparatus according to claim 7, wherein the pupil shape forming unit has a plurality of aperture diaphragms configured to be insertable into and removable from the illumination optical path. 9. The exposure apparatus according to claim 1, wherein the pupil shape forming unit has a diffractive optical element for converting a light beam into a light beam having a predetermined cross section. 10. The exposure apparatus according to claim 9, wherein the pupil shape forming unit has a plurality of diffractive optical elements configured to be insertable into and removable from the illumination optical path. 11. An exposure method for illuminating a reticle through an illumination optical system and projecting an image of a pattern formed on the reticle onto a substrate, wherein a resist pattern to be transferred or a substrate pattern formed through a process is formed. In order to have a desired size and shape, a vertical position coordinate and a horizontal position coordinate on the pupil surface or a surface in the vicinity of the pupil surface of the illumination optical system are substantially set. An exposure method, which comprises forming four substantially planar light sources that are set to be different from each other. 12. An exposure method for illuminating a reticle having a plurality of chip patterns through an illumination optical system and projecting an image of a pattern formed on the reticle onto a substrate, wherein a pupil plane of the illumination optical system or a pupil plane thereof is provided. Four substantial surface light sources are formed on the neighboring surface, and the position coordinates of the four substantial surface light sources in the vertical direction on the pupil plane or on the surface in the vicinity thereof according to the long side direction of the chip pattern. And at least one of the horizontal position coordinates is set such that the vertical position coordinates and the horizontal position coordinates are substantially different from each other. 13. A resist pattern to be transferred or a substrate pattern formed through a process has a desired size and shape on the surface of the pupil surface of the four substantial surface light sources or a surface in the vicinity thereof. 13. The exposure method according to claim 12, wherein the vertical position coordinate and the horizontal position coordinate are set so as to be substantially different from each other. 14. A reticle with optical proximity correction is used as the reticle, and the line width and width in the vertical direction of the resist pattern or the substrate pattern obtained through the reticle with optical proximity correction. In order to adjust at least one of the line widths in the direction, it is possible to set vertical position coordinates and horizontal position coordinates on the pupil plane of the four substantial surface light sources or on a plane in the vicinity thereof. The exposure method according to any one of claims 11 to 13, which is characterized. 15. The ratio between the vertical position coordinate and the horizontal position coordinate on the pupil plane of the four substantial surface light sources or on the surface in the vicinity thereof is set to be different according to a ratio of 10% or more. 15. The method according to claim 11, wherein
The exposure method according to any one of 1. 16. An exposure apparatus comprising an illumination optical system for illuminating a reticle on which a pattern to be transferred is formed, and a projection optical system for forming an image of the pattern of the reticle on a substrate, wherein the illumination optical system is A pupil plane of the illumination optical system or a plane near the pupil plane, which has pupil shape forming means for forming four substantial surface light sources, and the four substantial surface light sources formed by the pupil shape forming means Let y be the position coordinate in the vertical direction on the pupil plane of the illumination optical system or a surface in the vicinity thereof, and in the lateral direction on the pupil plane of the illumination optical system of the four substantial surface light sources or a surface in the vicinity thereof. When the position coordinate is x, the pupil shape forming unit forms the four substantial surface light sources so that the ratio of the position coordinate x to the position coordinate y is 1.1 or more. Mode and the position with respect to the position coordinate y An exposure apparatus having a second illumination mode for forming the four substantial surface light sources so that a ratio of coordinates x is 1 / 1.1 or less. 17. In the first illumination mode, the four substantial surface light sources are formed such that a ratio of the position coordinate x to the position coordinate y is 1.2 or more, and the second illumination is used. In the mode, the four substantial surface light sources are formed such that a ratio of the position coordinate x to the position coordinate y is 0.83 or less.
6. The exposure apparatus according to item 6. 18. When the ratio of the numerical apertures of the four light fluxes from the four substantial surface light sources to the reticle side numerical aperture of the projection optical system is σs, then 0.1 ≦ σs ≦ 0. The exposure apparatus according to claim 16 or 17, characterized in that 19. An exposure method of illuminating a reticle via an illumination optical system and projecting an image of a pattern formed on the reticle onto a substrate via a projection optical system, wherein a pupil plane of the illumination optical system or a pupil plane thereof is provided. 4 substantially surface light sources are formed on a surface in the vicinity of the pupil plane of the illumination optical system of the 4 substantially surface light sources, or a vertical position coordinate on a surface in the vicinity thereof is defined as y, and
Assuming that the lateral position coordinate of the two substantially planar light sources on the pupil plane of the illumination optical system or a surface in the vicinity thereof is x, the ratio of the position coordinate x to the position coordinate y is 1.1 or more. The first illumination mode forming the four substantial surface light sources and the four substantial surface light sources such that the ratio of the position coordinate x to the position coordinate y is 1 / 1.1 or less. And a second illumination mode for forming the exposure method. 20. In the first illumination mode, the four substantial surface light sources are formed such that a ratio of the position coordinate x to the position coordinate y is 1.2 or more, and the second illumination is used. 20. The exposure method according to claim 19, wherein in the mode, the four substantial surface light sources are formed such that a ratio of the position coordinate x to the position coordinate y is 0.83 or less. 21. When the ratio of the numerical apertures of the four light beams from the four substantial surface light sources to the reticle side numerical aperture of the projection optical system is σs, then 0.1 ≦ σs ≦ 0. The exposure method according to claim 19 or 20, characterized in that 22. An exposure apparatus comprising: an illumination optical system that illuminates a reticle on which a pattern to be transferred is formed; and a projection optical system that forms an image of the pattern of the reticle on a substrate. A pupil shape forming means for forming four substantial surface light sources on a pupil surface of the illumination optical system or a surface in the vicinity thereof, wherein the pupil shape forming means forms the pupil shape forming means. The center of gravity of one of the four surface light sources is 0.5 <r <1-rs, and sin ⁻¹ {(rs) / (1-rs)} <θ <π / 4. , And a centroid position of the one surface light source of the four substantial surface light sources is 0.5 <r <1-rs, and π / 4 <θ <π. / 2-sin ^-1 {(rs) / (1-rs)}, a second illumination mode satisfying Light equipment. Here, r is a radius vector when the position of the center of gravity of the one surface light source is expressed in polar coordinates (r, θ) with the optical axis of the illumination optical system as a pole on the pupil surface or the surface in the vicinity thereof. , Is standardized with the radius of the pupil of the projection optical system being 1; θ is the position of the center of gravity of the one surface light source on the pupil plane or on the plane in the vicinity thereof, and the optical axis of the illumination optical system is Is the argument when expressed in polar coordinates (r, θ) as
s is the distance from the position of the center of gravity of the one surface light source to the outermost edge. 23. The four substantially planar light sources are arranged in two-fold rotational symmetry about the optical axis on the pupil plane or on the plane in the vicinity thereof. Exposure equipment. 24. An exposure method of illuminating a reticle via an illumination optical system and projecting an image of a pattern formed on the reticle onto a substrate via a projection optical system, comprising: a pupil plane of the illumination optical system or a pupil plane thereof. Four substantial surface light sources are formed on neighboring surfaces, and the position of the center of gravity of one of the four substantially surface light sources is 0.5 <r <1-rs, and sin ⁻¹ { a first illumination mode satisfying (rs) / (1-rs)} <θ <π / 4, and the position of the center of gravity of the one surface light source of the four substantial surface light sources is 0.5. <R <1-rs, and π / 4 <θ <π / 2-sin ⁻¹ {(rs) / (1-rs)}, a second illumination mode satisfying Method. Here, r is a radius vector when the position of the center of gravity of the one surface light source is expressed in polar coordinates (r, θ) with the optical axis of the illumination optical system as a pole on the pupil surface or the surface in the vicinity thereof. , Is standardized with the radius of the pupil of the projection optical system being 1; θ is a position where the center of gravity of the one surface light source is the optical axis of the illumination optical system on the pupil plane or on the plane in the vicinity thereof. Is the argument when expressed in polar coordinates (r, θ) as
s is the distance from the position of the center of gravity of the one surface light source to the outermost edge.